URL
https://opencores.org/ocsvn/openrisc/openrisc/trunk
Subversion Repositories openrisc
[/] [openrisc/] [trunk/] [gnu-stable/] [gcc-4.5.1/] [gcc/] [tree-vrp.c] - Rev 856
Go to most recent revision | Compare with Previous | Blame | View Log
/* Support routines for Value Range Propagation (VRP). Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. Contributed by Diego Novillo <dnovillo@redhat.com>. This file is part of GCC. GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see <http://www.gnu.org/licenses/>. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "ggc.h" #include "flags.h" #include "tree.h" #include "basic-block.h" #include "tree-flow.h" #include "tree-pass.h" #include "tree-dump.h" #include "timevar.h" #include "diagnostic.h" #include "toplev.h" #include "intl.h" #include "cfgloop.h" #include "tree-scalar-evolution.h" #include "tree-ssa-propagate.h" #include "tree-chrec.h" /* Set of SSA names found live during the RPO traversal of the function for still active basic-blocks. */ static sbitmap *live; /* Return true if the SSA name NAME is live on the edge E. */ static bool live_on_edge (edge e, tree name) { return (live[e->dest->index] && TEST_BIT (live[e->dest->index], SSA_NAME_VERSION (name))); } /* Local functions. */ static int compare_values (tree val1, tree val2); static int compare_values_warnv (tree val1, tree val2, bool *); static void vrp_meet (value_range_t *, value_range_t *); static tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code, tree, tree, bool, bool *, bool *); /* Location information for ASSERT_EXPRs. Each instance of this structure describes an ASSERT_EXPR for an SSA name. Since a single SSA name may have more than one assertion associated with it, these locations are kept in a linked list attached to the corresponding SSA name. */ struct assert_locus_d { /* Basic block where the assertion would be inserted. */ basic_block bb; /* Some assertions need to be inserted on an edge (e.g., assertions generated by COND_EXPRs). In those cases, BB will be NULL. */ edge e; /* Pointer to the statement that generated this assertion. */ gimple_stmt_iterator si; /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */ enum tree_code comp_code; /* Value being compared against. */ tree val; /* Expression to compare. */ tree expr; /* Next node in the linked list. */ struct assert_locus_d *next; }; typedef struct assert_locus_d *assert_locus_t; /* If bit I is present, it means that SSA name N_i has a list of assertions that should be inserted in the IL. */ static bitmap need_assert_for; /* Array of locations lists where to insert assertions. ASSERTS_FOR[I] holds a list of ASSERT_LOCUS_T nodes that describe where ASSERT_EXPRs for SSA name N_I should be inserted. */ static assert_locus_t *asserts_for; /* Value range array. After propagation, VR_VALUE[I] holds the range of values that SSA name N_I may take. */ static value_range_t **vr_value; /* For a PHI node which sets SSA name N_I, VR_COUNTS[I] holds the number of executable edges we saw the last time we visited the node. */ static int *vr_phi_edge_counts; typedef struct { gimple stmt; tree vec; } switch_update; static VEC (edge, heap) *to_remove_edges; DEF_VEC_O(switch_update); DEF_VEC_ALLOC_O(switch_update, heap); static VEC (switch_update, heap) *to_update_switch_stmts; /* Return the maximum value for TYPE. */ static inline tree vrp_val_max (const_tree type) { if (!INTEGRAL_TYPE_P (type)) return NULL_TREE; return TYPE_MAX_VALUE (type); } /* Return the minimum value for TYPE. */ static inline tree vrp_val_min (const_tree type) { if (!INTEGRAL_TYPE_P (type)) return NULL_TREE; return TYPE_MIN_VALUE (type); } /* Return whether VAL is equal to the maximum value of its type. This will be true for a positive overflow infinity. We can't do a simple equality comparison with TYPE_MAX_VALUE because C typedefs and Ada subtypes can produce types whose TYPE_MAX_VALUE is not == to the integer constant with the same value in the type. */ static inline bool vrp_val_is_max (const_tree val) { tree type_max = vrp_val_max (TREE_TYPE (val)); return (val == type_max || (type_max != NULL_TREE && operand_equal_p (val, type_max, 0))); } /* Return whether VAL is equal to the minimum value of its type. This will be true for a negative overflow infinity. */ static inline bool vrp_val_is_min (const_tree val) { tree type_min = vrp_val_min (TREE_TYPE (val)); return (val == type_min || (type_min != NULL_TREE && operand_equal_p (val, type_min, 0))); } /* Return whether TYPE should use an overflow infinity distinct from TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to represent a signed overflow during VRP computations. An infinity is distinct from a half-range, which will go from some number to TYPE_{MIN,MAX}_VALUE. */ static inline bool needs_overflow_infinity (const_tree type) { return INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type); } /* Return whether TYPE can support our overflow infinity representation: we use the TREE_OVERFLOW flag, which only exists for constants. If TYPE doesn't support this, we don't optimize cases which would require signed overflow--we drop them to VARYING. */ static inline bool supports_overflow_infinity (const_tree type) { tree min = vrp_val_min (type), max = vrp_val_max (type); #ifdef ENABLE_CHECKING gcc_assert (needs_overflow_infinity (type)); #endif return (min != NULL_TREE && CONSTANT_CLASS_P (min) && max != NULL_TREE && CONSTANT_CLASS_P (max)); } /* VAL is the maximum or minimum value of a type. Return a corresponding overflow infinity. */ static inline tree make_overflow_infinity (tree val) { #ifdef ENABLE_CHECKING gcc_assert (val != NULL_TREE && CONSTANT_CLASS_P (val)); #endif val = copy_node (val); TREE_OVERFLOW (val) = 1; return val; } /* Return a negative overflow infinity for TYPE. */ static inline tree negative_overflow_infinity (tree type) { #ifdef ENABLE_CHECKING gcc_assert (supports_overflow_infinity (type)); #endif return make_overflow_infinity (vrp_val_min (type)); } /* Return a positive overflow infinity for TYPE. */ static inline tree positive_overflow_infinity (tree type) { #ifdef ENABLE_CHECKING gcc_assert (supports_overflow_infinity (type)); #endif return make_overflow_infinity (vrp_val_max (type)); } /* Return whether VAL is a negative overflow infinity. */ static inline bool is_negative_overflow_infinity (const_tree val) { return (needs_overflow_infinity (TREE_TYPE (val)) && CONSTANT_CLASS_P (val) && TREE_OVERFLOW (val) && vrp_val_is_min (val)); } /* Return whether VAL is a positive overflow infinity. */ static inline bool is_positive_overflow_infinity (const_tree val) { return (needs_overflow_infinity (TREE_TYPE (val)) && CONSTANT_CLASS_P (val) && TREE_OVERFLOW (val) && vrp_val_is_max (val)); } /* Return whether VAL is a positive or negative overflow infinity. */ static inline bool is_overflow_infinity (const_tree val) { return (needs_overflow_infinity (TREE_TYPE (val)) && CONSTANT_CLASS_P (val) && TREE_OVERFLOW (val) && (vrp_val_is_min (val) || vrp_val_is_max (val))); } /* Return whether STMT has a constant rhs that is_overflow_infinity. */ static inline bool stmt_overflow_infinity (gimple stmt) { if (is_gimple_assign (stmt) && get_gimple_rhs_class (gimple_assign_rhs_code (stmt)) == GIMPLE_SINGLE_RHS) return is_overflow_infinity (gimple_assign_rhs1 (stmt)); return false; } /* If VAL is now an overflow infinity, return VAL. Otherwise, return the same value with TREE_OVERFLOW clear. This can be used to avoid confusing a regular value with an overflow value. */ static inline tree avoid_overflow_infinity (tree val) { if (!is_overflow_infinity (val)) return val; if (vrp_val_is_max (val)) return vrp_val_max (TREE_TYPE (val)); else { #ifdef ENABLE_CHECKING gcc_assert (vrp_val_is_min (val)); #endif return vrp_val_min (TREE_TYPE (val)); } } /* Return true if ARG is marked with the nonnull attribute in the current function signature. */ static bool nonnull_arg_p (const_tree arg) { tree t, attrs, fntype; unsigned HOST_WIDE_INT arg_num; gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg))); /* The static chain decl is always non null. */ if (arg == cfun->static_chain_decl) return true; fntype = TREE_TYPE (current_function_decl); attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype)); /* If "nonnull" wasn't specified, we know nothing about the argument. */ if (attrs == NULL_TREE) return false; /* If "nonnull" applies to all the arguments, then ARG is non-null. */ if (TREE_VALUE (attrs) == NULL_TREE) return true; /* Get the position number for ARG in the function signature. */ for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl); t; t = TREE_CHAIN (t), arg_num++) { if (t == arg) break; } gcc_assert (t == arg); /* Now see if ARG_NUM is mentioned in the nonnull list. */ for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t)) { if (compare_tree_int (TREE_VALUE (t), arg_num) == 0) return true; } return false; } /* Set value range VR to VR_VARYING. */ static inline void set_value_range_to_varying (value_range_t *vr) { vr->type = VR_VARYING; vr->min = vr->max = NULL_TREE; if (vr->equiv) bitmap_clear (vr->equiv); } /* Set value range VR to {T, MIN, MAX, EQUIV}. */ static void set_value_range (value_range_t *vr, enum value_range_type t, tree min, tree max, bitmap equiv) { #if defined ENABLE_CHECKING /* Check the validity of the range. */ if (t == VR_RANGE || t == VR_ANTI_RANGE) { int cmp; gcc_assert (min && max); if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE) gcc_assert (!vrp_val_is_min (min) || !vrp_val_is_max (max)); cmp = compare_values (min, max); gcc_assert (cmp == 0 || cmp == -1 || cmp == -2); if (needs_overflow_infinity (TREE_TYPE (min))) gcc_assert (!is_overflow_infinity (min) || !is_overflow_infinity (max)); } if (t == VR_UNDEFINED || t == VR_VARYING) gcc_assert (min == NULL_TREE && max == NULL_TREE); if (t == VR_UNDEFINED || t == VR_VARYING) gcc_assert (equiv == NULL || bitmap_empty_p (equiv)); #endif vr->type = t; vr->min = min; vr->max = max; /* Since updating the equivalence set involves deep copying the bitmaps, only do it if absolutely necessary. */ if (vr->equiv == NULL && equiv != NULL) vr->equiv = BITMAP_ALLOC (NULL); if (equiv != vr->equiv) { if (equiv && !bitmap_empty_p (equiv)) bitmap_copy (vr->equiv, equiv); else bitmap_clear (vr->equiv); } } /* Set value range VR to the canonical form of {T, MIN, MAX, EQUIV}. This means adjusting T, MIN and MAX representing the case of a wrapping range with MAX < MIN covering [MIN, type_max] U [type_min, MAX] as anti-rage ~[MAX+1, MIN-1]. Likewise for wrapping anti-ranges. In corner cases where MAX+1 or MIN-1 wraps this will fall back to varying. This routine exists to ease canonicalization in the case where we extract ranges from var + CST op limit. */ static void set_and_canonicalize_value_range (value_range_t *vr, enum value_range_type t, tree min, tree max, bitmap equiv) { /* Nothing to canonicalize for symbolic or unknown or varying ranges. */ if ((t != VR_RANGE && t != VR_ANTI_RANGE) || TREE_CODE (min) != INTEGER_CST || TREE_CODE (max) != INTEGER_CST) { set_value_range (vr, t, min, max, equiv); return; } /* Wrong order for min and max, to swap them and the VR type we need to adjust them. */ if (tree_int_cst_lt (max, min)) { tree one = build_int_cst (TREE_TYPE (min), 1); tree tmp = int_const_binop (PLUS_EXPR, max, one, 0); max = int_const_binop (MINUS_EXPR, min, one, 0); min = tmp; /* There's one corner case, if we had [C+1, C] before we now have that again. But this represents an empty value range, so drop to varying in this case. */ if (tree_int_cst_lt (max, min)) { set_value_range_to_varying (vr); return; } t = t == VR_RANGE ? VR_ANTI_RANGE : VR_RANGE; } /* Anti-ranges that can be represented as ranges should be so. */ if (t == VR_ANTI_RANGE) { bool is_min = vrp_val_is_min (min); bool is_max = vrp_val_is_max (max); if (is_min && is_max) { /* We cannot deal with empty ranges, drop to varying. */ set_value_range_to_varying (vr); return; } else if (is_min /* As a special exception preserve non-null ranges. */ && !(TYPE_UNSIGNED (TREE_TYPE (min)) && integer_zerop (max))) { tree one = build_int_cst (TREE_TYPE (max), 1); min = int_const_binop (PLUS_EXPR, max, one, 0); max = vrp_val_max (TREE_TYPE (max)); t = VR_RANGE; } else if (is_max) { tree one = build_int_cst (TREE_TYPE (min), 1); max = int_const_binop (MINUS_EXPR, min, one, 0); min = vrp_val_min (TREE_TYPE (min)); t = VR_RANGE; } } set_value_range (vr, t, min, max, equiv); } /* Copy value range FROM into value range TO. */ static inline void copy_value_range (value_range_t *to, value_range_t *from) { set_value_range (to, from->type, from->min, from->max, from->equiv); } /* Set value range VR to a single value. This function is only called with values we get from statements, and exists to clear the TREE_OVERFLOW flag so that we don't think we have an overflow infinity when we shouldn't. */ static inline void set_value_range_to_value (value_range_t *vr, tree val, bitmap equiv) { gcc_assert (is_gimple_min_invariant (val)); val = avoid_overflow_infinity (val); set_value_range (vr, VR_RANGE, val, val, equiv); } /* Set value range VR to a non-negative range of type TYPE. OVERFLOW_INFINITY indicates whether to use an overflow infinity rather than TYPE_MAX_VALUE; this should be true if we determine that the range is nonnegative based on the assumption that signed overflow does not occur. */ static inline void set_value_range_to_nonnegative (value_range_t *vr, tree type, bool overflow_infinity) { tree zero; if (overflow_infinity && !supports_overflow_infinity (type)) { set_value_range_to_varying (vr); return; } zero = build_int_cst (type, 0); set_value_range (vr, VR_RANGE, zero, (overflow_infinity ? positive_overflow_infinity (type) : TYPE_MAX_VALUE (type)), vr->equiv); } /* Set value range VR to a non-NULL range of type TYPE. */ static inline void set_value_range_to_nonnull (value_range_t *vr, tree type) { tree zero = build_int_cst (type, 0); set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv); } /* Set value range VR to a NULL range of type TYPE. */ static inline void set_value_range_to_null (value_range_t *vr, tree type) { set_value_range_to_value (vr, build_int_cst (type, 0), vr->equiv); } /* Set value range VR to a range of a truthvalue of type TYPE. */ static inline void set_value_range_to_truthvalue (value_range_t *vr, tree type) { if (TYPE_PRECISION (type) == 1) set_value_range_to_varying (vr); else set_value_range (vr, VR_RANGE, build_int_cst (type, 0), build_int_cst (type, 1), vr->equiv); } /* Set value range VR to VR_UNDEFINED. */ static inline void set_value_range_to_undefined (value_range_t *vr) { vr->type = VR_UNDEFINED; vr->min = vr->max = NULL_TREE; if (vr->equiv) bitmap_clear (vr->equiv); } /* If abs (min) < abs (max), set VR to [-max, max], if abs (min) >= abs (max), set VR to [-min, min]. */ static void abs_extent_range (value_range_t *vr, tree min, tree max) { int cmp; gcc_assert (TREE_CODE (min) == INTEGER_CST); gcc_assert (TREE_CODE (max) == INTEGER_CST); gcc_assert (INTEGRAL_TYPE_P (TREE_TYPE (min))); gcc_assert (!TYPE_UNSIGNED (TREE_TYPE (min))); min = fold_unary (ABS_EXPR, TREE_TYPE (min), min); max = fold_unary (ABS_EXPR, TREE_TYPE (max), max); if (TREE_OVERFLOW (min) || TREE_OVERFLOW (max)) { set_value_range_to_varying (vr); return; } cmp = compare_values (min, max); if (cmp == -1) min = fold_unary (NEGATE_EXPR, TREE_TYPE (min), max); else if (cmp == 0 || cmp == 1) { max = min; min = fold_unary (NEGATE_EXPR, TREE_TYPE (min), min); } else { set_value_range_to_varying (vr); return; } set_and_canonicalize_value_range (vr, VR_RANGE, min, max, NULL); } /* Return value range information for VAR. If we have no values ranges recorded (ie, VRP is not running), then return NULL. Otherwise create an empty range if none existed for VAR. */ static value_range_t * get_value_range (const_tree var) { value_range_t *vr; tree sym; unsigned ver = SSA_NAME_VERSION (var); /* If we have no recorded ranges, then return NULL. */ if (! vr_value) return NULL; vr = vr_value[ver]; if (vr) return vr; /* Create a default value range. */ vr_value[ver] = vr = XCNEW (value_range_t); /* Defer allocating the equivalence set. */ vr->equiv = NULL; /* If VAR is a default definition, the variable can take any value in VAR's type. */ sym = SSA_NAME_VAR (var); if (SSA_NAME_IS_DEFAULT_DEF (var)) { /* Try to use the "nonnull" attribute to create ~[0, 0] anti-ranges for pointers. Note that this is only valid with default definitions of PARM_DECLs. */ if (TREE_CODE (sym) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (sym)) && nonnull_arg_p (sym)) set_value_range_to_nonnull (vr, TREE_TYPE (sym)); else set_value_range_to_varying (vr); } return vr; } /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */ static inline bool vrp_operand_equal_p (const_tree val1, const_tree val2) { if (val1 == val2) return true; if (!val1 || !val2 || !operand_equal_p (val1, val2, 0)) return false; if (is_overflow_infinity (val1)) return is_overflow_infinity (val2); return true; } /* Return true, if the bitmaps B1 and B2 are equal. */ static inline bool vrp_bitmap_equal_p (const_bitmap b1, const_bitmap b2) { return (b1 == b2 || (b1 && b2 && bitmap_equal_p (b1, b2))); } /* Update the value range and equivalence set for variable VAR to NEW_VR. Return true if NEW_VR is different from VAR's previous value. NOTE: This function assumes that NEW_VR is a temporary value range object created for the sole purpose of updating VAR's range. The storage used by the equivalence set from NEW_VR will be freed by this function. Do not call update_value_range when NEW_VR is the range object associated with another SSA name. */ static inline bool update_value_range (const_tree var, value_range_t *new_vr) { value_range_t *old_vr; bool is_new; /* Update the value range, if necessary. */ old_vr = get_value_range (var); is_new = old_vr->type != new_vr->type || !vrp_operand_equal_p (old_vr->min, new_vr->min) || !vrp_operand_equal_p (old_vr->max, new_vr->max) || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv); if (is_new) set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max, new_vr->equiv); BITMAP_FREE (new_vr->equiv); return is_new; } /* Add VAR and VAR's equivalence set to EQUIV. This is the central point where equivalence processing can be turned on/off. */ static void add_equivalence (bitmap *equiv, const_tree var) { unsigned ver = SSA_NAME_VERSION (var); value_range_t *vr = vr_value[ver]; if (*equiv == NULL) *equiv = BITMAP_ALLOC (NULL); bitmap_set_bit (*equiv, ver); if (vr && vr->equiv) bitmap_ior_into (*equiv, vr->equiv); } /* Return true if VR is ~[0, 0]. */ static inline bool range_is_nonnull (value_range_t *vr) { return vr->type == VR_ANTI_RANGE && integer_zerop (vr->min) && integer_zerop (vr->max); } /* Return true if VR is [0, 0]. */ static inline bool range_is_null (value_range_t *vr) { return vr->type == VR_RANGE && integer_zerop (vr->min) && integer_zerop (vr->max); } /* Return true if max and min of VR are INTEGER_CST. It's not necessary a singleton. */ static inline bool range_int_cst_p (value_range_t *vr) { return (vr->type == VR_RANGE && TREE_CODE (vr->max) == INTEGER_CST && TREE_CODE (vr->min) == INTEGER_CST && !TREE_OVERFLOW (vr->max) && !TREE_OVERFLOW (vr->min)); } /* Return true if VR is a INTEGER_CST singleton. */ static inline bool range_int_cst_singleton_p (value_range_t *vr) { return (range_int_cst_p (vr) && tree_int_cst_equal (vr->min, vr->max)); } /* Return true if value range VR involves at least one symbol. */ static inline bool symbolic_range_p (value_range_t *vr) { return (!is_gimple_min_invariant (vr->min) || !is_gimple_min_invariant (vr->max)); } /* Return true if value range VR uses an overflow infinity. */ static inline bool overflow_infinity_range_p (value_range_t *vr) { return (vr->type == VR_RANGE && (is_overflow_infinity (vr->min) || is_overflow_infinity (vr->max))); } /* Return false if we can not make a valid comparison based on VR; this will be the case if it uses an overflow infinity and overflow is not undefined (i.e., -fno-strict-overflow is in effect). Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR uses an overflow infinity. */ static bool usable_range_p (value_range_t *vr, bool *strict_overflow_p) { gcc_assert (vr->type == VR_RANGE); if (is_overflow_infinity (vr->min)) { *strict_overflow_p = true; if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min))) return false; } if (is_overflow_infinity (vr->max)) { *strict_overflow_p = true; if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max))) return false; } return true; } /* Like tree_expr_nonnegative_warnv_p, but this function uses value ranges obtained so far. */ static bool vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p) { return (tree_expr_nonnegative_warnv_p (expr, strict_overflow_p) || (TREE_CODE (expr) == SSA_NAME && ssa_name_nonnegative_p (expr))); } /* Return true if the result of assignment STMT is know to be non-negative. If the return value is based on the assumption that signed overflow is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change *STRICT_OVERFLOW_P.*/ static bool gimple_assign_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p) { enum tree_code code = gimple_assign_rhs_code (stmt); switch (get_gimple_rhs_class (code)) { case GIMPLE_UNARY_RHS: return tree_unary_nonnegative_warnv_p (gimple_assign_rhs_code (stmt), gimple_expr_type (stmt), gimple_assign_rhs1 (stmt), strict_overflow_p); case GIMPLE_BINARY_RHS: return tree_binary_nonnegative_warnv_p (gimple_assign_rhs_code (stmt), gimple_expr_type (stmt), gimple_assign_rhs1 (stmt), gimple_assign_rhs2 (stmt), strict_overflow_p); case GIMPLE_SINGLE_RHS: return tree_single_nonnegative_warnv_p (gimple_assign_rhs1 (stmt), strict_overflow_p); case GIMPLE_INVALID_RHS: gcc_unreachable (); default: gcc_unreachable (); } } /* Return true if return value of call STMT is know to be non-negative. If the return value is based on the assumption that signed overflow is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change *STRICT_OVERFLOW_P.*/ static bool gimple_call_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p) { tree arg0 = gimple_call_num_args (stmt) > 0 ? gimple_call_arg (stmt, 0) : NULL_TREE; tree arg1 = gimple_call_num_args (stmt) > 1 ? gimple_call_arg (stmt, 1) : NULL_TREE; return tree_call_nonnegative_warnv_p (gimple_expr_type (stmt), gimple_call_fndecl (stmt), arg0, arg1, strict_overflow_p); } /* Return true if STMT is know to to compute a non-negative value. If the return value is based on the assumption that signed overflow is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change *STRICT_OVERFLOW_P.*/ static bool gimple_stmt_nonnegative_warnv_p (gimple stmt, bool *strict_overflow_p) { switch (gimple_code (stmt)) { case GIMPLE_ASSIGN: return gimple_assign_nonnegative_warnv_p (stmt, strict_overflow_p); case GIMPLE_CALL: return gimple_call_nonnegative_warnv_p (stmt, strict_overflow_p); default: gcc_unreachable (); } } /* Return true if the result of assignment STMT is know to be non-zero. If the return value is based on the assumption that signed overflow is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change *STRICT_OVERFLOW_P.*/ static bool gimple_assign_nonzero_warnv_p (gimple stmt, bool *strict_overflow_p) { enum tree_code code = gimple_assign_rhs_code (stmt); switch (get_gimple_rhs_class (code)) { case GIMPLE_UNARY_RHS: return tree_unary_nonzero_warnv_p (gimple_assign_rhs_code (stmt), gimple_expr_type (stmt), gimple_assign_rhs1 (stmt), strict_overflow_p); case GIMPLE_BINARY_RHS: return tree_binary_nonzero_warnv_p (gimple_assign_rhs_code (stmt), gimple_expr_type (stmt), gimple_assign_rhs1 (stmt), gimple_assign_rhs2 (stmt), strict_overflow_p); case GIMPLE_SINGLE_RHS: return tree_single_nonzero_warnv_p (gimple_assign_rhs1 (stmt), strict_overflow_p); case GIMPLE_INVALID_RHS: gcc_unreachable (); default: gcc_unreachable (); } } /* Return true if STMT is know to to compute a non-zero value. If the return value is based on the assumption that signed overflow is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't change *STRICT_OVERFLOW_P.*/ static bool gimple_stmt_nonzero_warnv_p (gimple stmt, bool *strict_overflow_p) { switch (gimple_code (stmt)) { case GIMPLE_ASSIGN: return gimple_assign_nonzero_warnv_p (stmt, strict_overflow_p); case GIMPLE_CALL: return gimple_alloca_call_p (stmt); default: gcc_unreachable (); } } /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges obtained so far. */ static bool vrp_stmt_computes_nonzero (gimple stmt, bool *strict_overflow_p) { if (gimple_stmt_nonzero_warnv_p (stmt, strict_overflow_p)) return true; /* If we have an expression of the form &X->a, then the expression is nonnull if X is nonnull. */ if (is_gimple_assign (stmt) && gimple_assign_rhs_code (stmt) == ADDR_EXPR) { tree expr = gimple_assign_rhs1 (stmt); tree base = get_base_address (TREE_OPERAND (expr, 0)); if (base != NULL_TREE && TREE_CODE (base) == INDIRECT_REF && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) { value_range_t *vr = get_value_range (TREE_OPERAND (base, 0)); if (range_is_nonnull (vr)) return true; } } return false; } /* Returns true if EXPR is a valid value (as expected by compare_values) -- a gimple invariant, or SSA_NAME +- CST. */ static bool valid_value_p (tree expr) { if (TREE_CODE (expr) == SSA_NAME) return true; if (TREE_CODE (expr) == PLUS_EXPR || TREE_CODE (expr) == MINUS_EXPR) return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST); return is_gimple_min_invariant (expr); } /* Return 1 if VAL < VAL2 0 if !(VAL < VAL2) -2 if those are incomparable. */ static inline int operand_less_p (tree val, tree val2) { /* LT is folded faster than GE and others. Inline the common case. */ if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST) { if (TYPE_UNSIGNED (TREE_TYPE (val))) return INT_CST_LT_UNSIGNED (val, val2); else { if (INT_CST_LT (val, val2)) return 1; } } else { tree tcmp; fold_defer_overflow_warnings (); tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2); fold_undefer_and_ignore_overflow_warnings (); if (!tcmp || TREE_CODE (tcmp) != INTEGER_CST) return -2; if (!integer_zerop (tcmp)) return 1; } /* val >= val2, not considering overflow infinity. */ if (is_negative_overflow_infinity (val)) return is_negative_overflow_infinity (val2) ? 0 : 1; else if (is_positive_overflow_infinity (val2)) return is_positive_overflow_infinity (val) ? 0 : 1; return 0; } /* Compare two values VAL1 and VAL2. Return -2 if VAL1 and VAL2 cannot be compared at compile-time, -1 if VAL1 < VAL2, 0 if VAL1 == VAL2, +1 if VAL1 > VAL2, and +2 if VAL1 != VAL2 This is similar to tree_int_cst_compare but supports pointer values and values that cannot be compared at compile time. If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to true if the return value is only valid if we assume that signed overflow is undefined. */ static int compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p) { if (val1 == val2) return 0; /* Below we rely on the fact that VAL1 and VAL2 are both pointers or both integers. */ gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1)) == POINTER_TYPE_P (TREE_TYPE (val2))); /* Convert the two values into the same type. This is needed because sizetype causes sign extension even for unsigned types. */ val2 = fold_convert (TREE_TYPE (val1), val2); STRIP_USELESS_TYPE_CONVERSION (val2); if ((TREE_CODE (val1) == SSA_NAME || TREE_CODE (val1) == PLUS_EXPR || TREE_CODE (val1) == MINUS_EXPR) && (TREE_CODE (val2) == SSA_NAME || TREE_CODE (val2) == PLUS_EXPR || TREE_CODE (val2) == MINUS_EXPR)) { tree n1, c1, n2, c2; enum tree_code code1, code2; /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME', return -1 or +1 accordingly. If VAL1 and VAL2 don't use the same name, return -2. */ if (TREE_CODE (val1) == SSA_NAME) { code1 = SSA_NAME; n1 = val1; c1 = NULL_TREE; } else { code1 = TREE_CODE (val1); n1 = TREE_OPERAND (val1, 0); c1 = TREE_OPERAND (val1, 1); if (tree_int_cst_sgn (c1) == -1) { if (is_negative_overflow_infinity (c1)) return -2; c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1); if (!c1) return -2; code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR; } } if (TREE_CODE (val2) == SSA_NAME) { code2 = SSA_NAME; n2 = val2; c2 = NULL_TREE; } else { code2 = TREE_CODE (val2); n2 = TREE_OPERAND (val2, 0); c2 = TREE_OPERAND (val2, 1); if (tree_int_cst_sgn (c2) == -1) { if (is_negative_overflow_infinity (c2)) return -2; c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2); if (!c2) return -2; code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR; } } /* Both values must use the same name. */ if (n1 != n2) return -2; if (code1 == SSA_NAME && code2 == SSA_NAME) /* NAME == NAME */ return 0; /* If overflow is defined we cannot simplify more. */ if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1))) return -2; if (strict_overflow_p != NULL && (code1 == SSA_NAME || !TREE_NO_WARNING (val1)) && (code2 == SSA_NAME || !TREE_NO_WARNING (val2))) *strict_overflow_p = true; if (code1 == SSA_NAME) { if (code2 == PLUS_EXPR) /* NAME < NAME + CST */ return -1; else if (code2 == MINUS_EXPR) /* NAME > NAME - CST */ return 1; } else if (code1 == PLUS_EXPR) { if (code2 == SSA_NAME) /* NAME + CST > NAME */ return 1; else if (code2 == PLUS_EXPR) /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */ return compare_values_warnv (c1, c2, strict_overflow_p); else if (code2 == MINUS_EXPR) /* NAME + CST1 > NAME - CST2 */ return 1; } else if (code1 == MINUS_EXPR) { if (code2 == SSA_NAME) /* NAME - CST < NAME */ return -1; else if (code2 == PLUS_EXPR) /* NAME - CST1 < NAME + CST2 */ return -1; else if (code2 == MINUS_EXPR) /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that C1 and C2 are swapped in the call to compare_values. */ return compare_values_warnv (c2, c1, strict_overflow_p); } gcc_unreachable (); } /* We cannot compare non-constants. */ if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)) return -2; if (!POINTER_TYPE_P (TREE_TYPE (val1))) { /* We cannot compare overflowed values, except for overflow infinities. */ if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2)) { if (strict_overflow_p != NULL) *strict_overflow_p = true; if (is_negative_overflow_infinity (val1)) return is_negative_overflow_infinity (val2) ? 0 : -1; else if (is_negative_overflow_infinity (val2)) return 1; else if (is_positive_overflow_infinity (val1)) return is_positive_overflow_infinity (val2) ? 0 : 1; else if (is_positive_overflow_infinity (val2)) return -1; return -2; } return tree_int_cst_compare (val1, val2); } else { tree t; /* First see if VAL1 and VAL2 are not the same. */ if (val1 == val2 || operand_equal_p (val1, val2, 0)) return 0; /* If VAL1 is a lower address than VAL2, return -1. */ if (operand_less_p (val1, val2) == 1) return -1; /* If VAL1 is a higher address than VAL2, return +1. */ if (operand_less_p (val2, val1) == 1) return 1; /* If VAL1 is different than VAL2, return +2. For integer constants we either have already returned -1 or 1 or they are equivalent. We still might succeed in proving something about non-trivial operands. */ if (TREE_CODE (val1) != INTEGER_CST || TREE_CODE (val2) != INTEGER_CST) { t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2); if (t && integer_onep (t)) return 2; } return -2; } } /* Compare values like compare_values_warnv, but treat comparisons of nonconstants which rely on undefined overflow as incomparable. */ static int compare_values (tree val1, tree val2) { bool sop; int ret; sop = false; ret = compare_values_warnv (val1, val2, &sop); if (sop && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))) ret = -2; return ret; } /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX), 0 if VAL is not inside VR, -2 if we cannot tell either way. FIXME, the current semantics of this functions are a bit quirky when taken in the context of VRP. In here we do not care about VR's type. If VR is the anti-range ~[3, 5] the call value_inside_range (4, VR) will return 1. This is counter-intuitive in a strict sense, but the callers currently expect this. They are calling the function merely to determine whether VR->MIN <= VAL <= VR->MAX. The callers are applying the VR_RANGE/VR_ANTI_RANGE semantics themselves. This also applies to value_ranges_intersect_p and range_includes_zero_p. The semantics of VR_RANGE and VR_ANTI_RANGE should be encoded here, but that also means adapting the users of these functions to the new semantics. Benchmark compile/20001226-1.c compilation time after changing this function. */ static inline int value_inside_range (tree val, value_range_t * vr) { int cmp1, cmp2; cmp1 = operand_less_p (val, vr->min); if (cmp1 == -2) return -2; if (cmp1 == 1) return 0; cmp2 = operand_less_p (vr->max, val); if (cmp2 == -2) return -2; return !cmp2; } /* Return true if value ranges VR0 and VR1 have a non-empty intersection. Benchmark compile/20001226-1.c compilation time after changing this function. */ static inline bool value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1) { /* The value ranges do not intersect if the maximum of the first range is less than the minimum of the second range or vice versa. When those relations are unknown, we can't do any better. */ if (operand_less_p (vr0->max, vr1->min) != 0) return false; if (operand_less_p (vr1->max, vr0->min) != 0) return false; return true; } /* Return true if VR includes the value zero, false otherwise. FIXME, currently this will return false for an anti-range like ~[-4, 3]. This will be wrong when the semantics of value_inside_range are modified (currently the users of this function expect these semantics). */ static inline bool range_includes_zero_p (value_range_t *vr) { tree zero; gcc_assert (vr->type != VR_UNDEFINED && vr->type != VR_VARYING && !symbolic_range_p (vr)); zero = build_int_cst (TREE_TYPE (vr->min), 0); return (value_inside_range (zero, vr) == 1); } /* Return true if T, an SSA_NAME, is known to be nonnegative. Return false otherwise or if no value range information is available. */ bool ssa_name_nonnegative_p (const_tree t) { value_range_t *vr = get_value_range (t); if (INTEGRAL_TYPE_P (t) && TYPE_UNSIGNED (t)) return true; if (!vr) return false; /* Testing for VR_ANTI_RANGE is not useful here as any anti-range which would return a useful value should be encoded as a VR_RANGE. */ if (vr->type == VR_RANGE) { int result = compare_values (vr->min, integer_zero_node); return (result == 0 || result == 1); } return false; } /* If OP has a value range with a single constant value return that, otherwise return NULL_TREE. This returns OP itself if OP is a constant. */ static tree op_with_constant_singleton_value_range (tree op) { value_range_t *vr; if (is_gimple_min_invariant (op)) return op; if (TREE_CODE (op) != SSA_NAME) return NULL_TREE; vr = get_value_range (op); if (vr->type == VR_RANGE && operand_equal_p (vr->min, vr->max, 0) && is_gimple_min_invariant (vr->min)) return vr->min; return NULL_TREE; } /* Extract value range information from an ASSERT_EXPR EXPR and store it in *VR_P. */ static void extract_range_from_assert (value_range_t *vr_p, tree expr) { tree var, cond, limit, min, max, type; value_range_t *var_vr, *limit_vr; enum tree_code cond_code; var = ASSERT_EXPR_VAR (expr); cond = ASSERT_EXPR_COND (expr); gcc_assert (COMPARISON_CLASS_P (cond)); /* Find VAR in the ASSERT_EXPR conditional. */ if (var == TREE_OPERAND (cond, 0) || TREE_CODE (TREE_OPERAND (cond, 0)) == PLUS_EXPR || TREE_CODE (TREE_OPERAND (cond, 0)) == NOP_EXPR) { /* If the predicate is of the form VAR COMP LIMIT, then we just take LIMIT from the RHS and use the same comparison code. */ cond_code = TREE_CODE (cond); limit = TREE_OPERAND (cond, 1); cond = TREE_OPERAND (cond, 0); } else { /* If the predicate is of the form LIMIT COMP VAR, then we need to flip around the comparison code to create the proper range for VAR. */ cond_code = swap_tree_comparison (TREE_CODE (cond)); limit = TREE_OPERAND (cond, 0); cond = TREE_OPERAND (cond, 1); } limit = avoid_overflow_infinity (limit); type = TREE_TYPE (limit); gcc_assert (limit != var); /* For pointer arithmetic, we only keep track of pointer equality and inequality. */ if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR) { set_value_range_to_varying (vr_p); return; } /* If LIMIT is another SSA name and LIMIT has a range of its own, try to use LIMIT's range to avoid creating symbolic ranges unnecessarily. */ limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL; /* LIMIT's range is only interesting if it has any useful information. */ if (limit_vr && (limit_vr->type == VR_UNDEFINED || limit_vr->type == VR_VARYING || symbolic_range_p (limit_vr))) limit_vr = NULL; /* Initially, the new range has the same set of equivalences of VAR's range. This will be revised before returning the final value. Since assertions may be chained via mutually exclusive predicates, we will need to trim the set of equivalences before we are done. */ gcc_assert (vr_p->equiv == NULL); add_equivalence (&vr_p->equiv, var); /* Extract a new range based on the asserted comparison for VAR and LIMIT's value range. Notice that if LIMIT has an anti-range, we will only use it for equality comparisons (EQ_EXPR). For any other kind of assertion, we cannot derive a range from LIMIT's anti-range that can be used to describe the new range. For instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10], then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is no single range for x_2 that could describe LE_EXPR, so we might as well build the range [b_4, +INF] for it. One special case we handle is extracting a range from a range test encoded as (unsigned)var + CST <= limit. */ if (TREE_CODE (cond) == NOP_EXPR || TREE_CODE (cond) == PLUS_EXPR) { if (TREE_CODE (cond) == PLUS_EXPR) { min = fold_build1 (NEGATE_EXPR, TREE_TYPE (TREE_OPERAND (cond, 1)), TREE_OPERAND (cond, 1)); max = int_const_binop (PLUS_EXPR, limit, min, 0); cond = TREE_OPERAND (cond, 0); } else { min = build_int_cst (TREE_TYPE (var), 0); max = limit; } /* Make sure to not set TREE_OVERFLOW on the final type conversion. We are willingly interpreting large positive unsigned values as negative singed values here. */ min = force_fit_type_double (TREE_TYPE (var), TREE_INT_CST_LOW (min), TREE_INT_CST_HIGH (min), 0, false); max = force_fit_type_double (TREE_TYPE (var), TREE_INT_CST_LOW (max), TREE_INT_CST_HIGH (max), 0, false); /* We can transform a max, min range to an anti-range or vice-versa. Use set_and_canonicalize_value_range which does this for us. */ if (cond_code == LE_EXPR) set_and_canonicalize_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); else if (cond_code == GT_EXPR) set_and_canonicalize_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv); else gcc_unreachable (); } else if (cond_code == EQ_EXPR) { enum value_range_type range_type; if (limit_vr) { range_type = limit_vr->type; min = limit_vr->min; max = limit_vr->max; } else { range_type = VR_RANGE; min = limit; max = limit; } set_value_range (vr_p, range_type, min, max, vr_p->equiv); /* When asserting the equality VAR == LIMIT and LIMIT is another SSA name, the new range will also inherit the equivalence set from LIMIT. */ if (TREE_CODE (limit) == SSA_NAME) add_equivalence (&vr_p->equiv, limit); } else if (cond_code == NE_EXPR) { /* As described above, when LIMIT's range is an anti-range and this assertion is an inequality (NE_EXPR), then we cannot derive anything from the anti-range. For instance, if LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does not imply that VAR's range is [0, 0]. So, in the case of anti-ranges, we just assert the inequality using LIMIT and not its anti-range. If LIMIT_VR is a range, we can only use it to build a new anti-range if LIMIT_VR is a single-valued range. For instance, if LIMIT_VR is [0, 1], the predicate VAR != [0, 1] does not mean that VAR's range is ~[0, 1]. Rather, it means that for value 0 VAR should be ~[0, 0] and for value 1, VAR should be ~[1, 1]. We cannot represent these ranges. The only situation in which we can build a valid anti-range is when LIMIT_VR is a single-valued range (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case, build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */ if (limit_vr && limit_vr->type == VR_RANGE && compare_values (limit_vr->min, limit_vr->max) == 0) { min = limit_vr->min; max = limit_vr->max; } else { /* In any other case, we cannot use LIMIT's range to build a valid anti-range. */ min = max = limit; } /* If MIN and MAX cover the whole range for their type, then just use the original LIMIT. */ if (INTEGRAL_TYPE_P (type) && vrp_val_is_min (min) && vrp_val_is_max (max)) min = max = limit; set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv); } else if (cond_code == LE_EXPR || cond_code == LT_EXPR) { min = TYPE_MIN_VALUE (type); if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE) max = limit; else { /* If LIMIT_VR is of the form [N1, N2], we need to build the range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for LT_EXPR. */ max = limit_vr->max; } /* If the maximum value forces us to be out of bounds, simply punt. It would be pointless to try and do anything more since this all should be optimized away above us. */ if ((cond_code == LT_EXPR && compare_values (max, min) == 0) || (CONSTANT_CLASS_P (max) && TREE_OVERFLOW (max))) set_value_range_to_varying (vr_p); else { /* For LT_EXPR, we create the range [MIN, MAX - 1]. */ if (cond_code == LT_EXPR) { tree one = build_int_cst (type, 1); max = fold_build2 (MINUS_EXPR, type, max, one); if (EXPR_P (max)) TREE_NO_WARNING (max) = 1; } set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); } } else if (cond_code == GE_EXPR || cond_code == GT_EXPR) { max = TYPE_MAX_VALUE (type); if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE) min = limit; else { /* If LIMIT_VR is of the form [N1, N2], we need to build the range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for GT_EXPR. */ min = limit_vr->min; } /* If the minimum value forces us to be out of bounds, simply punt. It would be pointless to try and do anything more since this all should be optimized away above us. */ if ((cond_code == GT_EXPR && compare_values (min, max) == 0) || (CONSTANT_CLASS_P (min) && TREE_OVERFLOW (min))) set_value_range_to_varying (vr_p); else { /* For GT_EXPR, we create the range [MIN + 1, MAX]. */ if (cond_code == GT_EXPR) { tree one = build_int_cst (type, 1); min = fold_build2 (PLUS_EXPR, type, min, one); if (EXPR_P (min)) TREE_NO_WARNING (min) = 1; } set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); } } else gcc_unreachable (); /* If VAR already had a known range, it may happen that the new range we have computed and VAR's range are not compatible. For instance, if (p_5 == NULL) p_6 = ASSERT_EXPR <p_5, p_5 == NULL>; x_7 = p_6->fld; p_8 = ASSERT_EXPR <p_6, p_6 != NULL>; While the above comes from a faulty program, it will cause an ICE later because p_8 and p_6 will have incompatible ranges and at the same time will be considered equivalent. A similar situation would arise from if (i_5 > 10) i_6 = ASSERT_EXPR <i_5, i_5 > 10>; if (i_5 < 5) i_7 = ASSERT_EXPR <i_6, i_6 < 5>; Again i_6 and i_7 will have incompatible ranges. It would be pointless to try and do anything with i_7's range because anything dominated by 'if (i_5 < 5)' will be optimized away. Note, due to the wa in which simulation proceeds, the statement i_7 = ASSERT_EXPR <...> we would never be visited because the conditional 'if (i_5 < 5)' always evaluates to false. However, this extra check does not hurt and may protect against future changes to VRP that may get into a situation similar to the NULL pointer dereference example. Note that these compatibility tests are only needed when dealing with ranges or a mix of range and anti-range. If VAR_VR and VR_P are both anti-ranges, they will always be compatible, because two anti-ranges will always have a non-empty intersection. */ var_vr = get_value_range (var); /* We may need to make adjustments when VR_P and VAR_VR are numeric ranges or anti-ranges. */ if (vr_p->type == VR_VARYING || vr_p->type == VR_UNDEFINED || var_vr->type == VR_VARYING || var_vr->type == VR_UNDEFINED || symbolic_range_p (vr_p) || symbolic_range_p (var_vr)) return; if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE) { /* If the two ranges have a non-empty intersection, we can refine the resulting range. Since the assert expression creates an equivalency and at the same time it asserts a predicate, we can take the intersection of the two ranges to get better precision. */ if (value_ranges_intersect_p (var_vr, vr_p)) { /* Use the larger of the two minimums. */ if (compare_values (vr_p->min, var_vr->min) == -1) min = var_vr->min; else min = vr_p->min; /* Use the smaller of the two maximums. */ if (compare_values (vr_p->max, var_vr->max) == 1) max = var_vr->max; else max = vr_p->max; set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv); } else { /* The two ranges do not intersect, set the new range to VARYING, because we will not be able to do anything meaningful with it. */ set_value_range_to_varying (vr_p); } } else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE) || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE)) { /* A range and an anti-range will cancel each other only if their ends are the same. For instance, in the example above, p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible, so VR_P should be set to VR_VARYING. */ if (compare_values (var_vr->min, vr_p->min) == 0 && compare_values (var_vr->max, vr_p->max) == 0) set_value_range_to_varying (vr_p); else { tree min, max, anti_min, anti_max, real_min, real_max; int cmp; /* We want to compute the logical AND of the two ranges; there are three cases to consider. 1. The VR_ANTI_RANGE range is completely within the VR_RANGE and the endpoints of the ranges are different. In that case the resulting range should be whichever range is more precise. Typically that will be the VR_RANGE. 2. The VR_ANTI_RANGE is completely disjoint from the VR_RANGE. In this case the resulting range should be the VR_RANGE. 3. There is some overlap between the VR_ANTI_RANGE and the VR_RANGE. 3a. If the high limit of the VR_ANTI_RANGE resides within the VR_RANGE, then the result is a new VR_RANGE starting at the high limit of the VR_ANTI_RANGE + 1 and extending to the high limit of the original VR_RANGE. 3b. If the low limit of the VR_ANTI_RANGE resides within the VR_RANGE, then the result is a new VR_RANGE starting at the low limit of the original VR_RANGE and extending to the low limit of the VR_ANTI_RANGE - 1. */ if (vr_p->type == VR_ANTI_RANGE) { anti_min = vr_p->min; anti_max = vr_p->max; real_min = var_vr->min; real_max = var_vr->max; } else { anti_min = var_vr->min; anti_max = var_vr->max; real_min = vr_p->min; real_max = vr_p->max; } /* Case 1, VR_ANTI_RANGE completely within VR_RANGE, not including any endpoints. */ if (compare_values (anti_max, real_max) == -1 && compare_values (anti_min, real_min) == 1) { /* If the range is covering the whole valid range of the type keep the anti-range. */ if (!vrp_val_is_min (real_min) || !vrp_val_is_max (real_max)) set_value_range (vr_p, VR_RANGE, real_min, real_max, vr_p->equiv); } /* Case 2, VR_ANTI_RANGE completely disjoint from VR_RANGE. */ else if (compare_values (anti_min, real_max) == 1 || compare_values (anti_max, real_min) == -1) { set_value_range (vr_p, VR_RANGE, real_min, real_max, vr_p->equiv); } /* Case 3a, the anti-range extends into the low part of the real range. Thus creating a new low for the real range. */ else if (((cmp = compare_values (anti_max, real_min)) == 1 || cmp == 0) && compare_values (anti_max, real_max) == -1) { gcc_assert (!is_positive_overflow_infinity (anti_max)); if (needs_overflow_infinity (TREE_TYPE (anti_max)) && vrp_val_is_max (anti_max)) { if (!supports_overflow_infinity (TREE_TYPE (var_vr->min))) { set_value_range_to_varying (vr_p); return; } min = positive_overflow_infinity (TREE_TYPE (var_vr->min)); } else if (!POINTER_TYPE_P (TREE_TYPE (var_vr->min))) min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min), anti_max, build_int_cst (TREE_TYPE (var_vr->min), 1)); else min = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (var_vr->min), anti_max, size_int (1)); max = real_max; set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); } /* Case 3b, the anti-range extends into the high part of the real range. Thus creating a new higher for the real range. */ else if (compare_values (anti_min, real_min) == 1 && ((cmp = compare_values (anti_min, real_max)) == -1 || cmp == 0)) { gcc_assert (!is_negative_overflow_infinity (anti_min)); if (needs_overflow_infinity (TREE_TYPE (anti_min)) && vrp_val_is_min (anti_min)) { if (!supports_overflow_infinity (TREE_TYPE (var_vr->min))) { set_value_range_to_varying (vr_p); return; } max = negative_overflow_infinity (TREE_TYPE (var_vr->min)); } else if (!POINTER_TYPE_P (TREE_TYPE (var_vr->min))) max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min), anti_min, build_int_cst (TREE_TYPE (var_vr->min), 1)); else max = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (var_vr->min), anti_min, size_int (-1)); min = real_min; set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); } } } } /* Extract range information from SSA name VAR and store it in VR. If VAR has an interesting range, use it. Otherwise, create the range [VAR, VAR] and return it. This is useful in situations where we may have conditionals testing values of VARYING names. For instance, x_3 = y_5; if (x_3 > y_5) ... Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is always false. */ static void extract_range_from_ssa_name (value_range_t *vr, tree var) { value_range_t *var_vr = get_value_range (var); if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING) copy_value_range (vr, var_vr); else set_value_range (vr, VR_RANGE, var, var, NULL); add_equivalence (&vr->equiv, var); } /* Wrapper around int_const_binop. If the operation overflows and we are not using wrapping arithmetic, then adjust the result to be -INF or +INF depending on CODE, VAL1 and VAL2. This can return NULL_TREE if we need to use an overflow infinity representation but the type does not support it. */ static tree vrp_int_const_binop (enum tree_code code, tree val1, tree val2) { tree res; res = int_const_binop (code, val1, val2, 0); /* If we are using unsigned arithmetic, operate symbolically on -INF and +INF as int_const_binop only handles signed overflow. */ if (TYPE_UNSIGNED (TREE_TYPE (val1))) { int checkz = compare_values (res, val1); bool overflow = false; /* Ensure that res = val1 [+*] val2 >= val1 or that res = val1 - val2 <= val1. */ if ((code == PLUS_EXPR && !(checkz == 1 || checkz == 0)) || (code == MINUS_EXPR && !(checkz == 0 || checkz == -1))) { overflow = true; } /* Checking for multiplication overflow is done by dividing the output of the multiplication by the first input of the multiplication. If the result of that division operation is not equal to the second input of the multiplication, then the multiplication overflowed. */ else if (code == MULT_EXPR && !integer_zerop (val1)) { tree tmp = int_const_binop (TRUNC_DIV_EXPR, res, val1, 0); int check = compare_values (tmp, val2); if (check != 0) overflow = true; } if (overflow) { res = copy_node (res); TREE_OVERFLOW (res) = 1; } } else if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1))) /* If the singed operation wraps then int_const_binop has done everything we want. */ ; else if ((TREE_OVERFLOW (res) && !TREE_OVERFLOW (val1) && !TREE_OVERFLOW (val2)) || is_overflow_infinity (val1) || is_overflow_infinity (val2)) { /* If the operation overflowed but neither VAL1 nor VAL2 are overflown, return -INF or +INF depending on the operation and the combination of signs of the operands. */ int sgn1 = tree_int_cst_sgn (val1); int sgn2 = tree_int_cst_sgn (val2); if (needs_overflow_infinity (TREE_TYPE (res)) && !supports_overflow_infinity (TREE_TYPE (res))) return NULL_TREE; /* We have to punt on adding infinities of different signs, since we can't tell what the sign of the result should be. Likewise for subtracting infinities of the same sign. */ if (((code == PLUS_EXPR && sgn1 != sgn2) || (code == MINUS_EXPR && sgn1 == sgn2)) && is_overflow_infinity (val1) && is_overflow_infinity (val2)) return NULL_TREE; /* Don't try to handle division or shifting of infinities. */ if ((code == TRUNC_DIV_EXPR || code == FLOOR_DIV_EXPR || code == CEIL_DIV_EXPR || code == EXACT_DIV_EXPR || code == ROUND_DIV_EXPR || code == RSHIFT_EXPR) && (is_overflow_infinity (val1) || is_overflow_infinity (val2))) return NULL_TREE; /* Notice that we only need to handle the restricted set of operations handled by extract_range_from_binary_expr. Among them, only multiplication, addition and subtraction can yield overflow without overflown operands because we are working with integral types only... except in the case VAL1 = -INF and VAL2 = -1 which overflows to +INF for division too. */ /* For multiplication, the sign of the overflow is given by the comparison of the signs of the operands. */ if ((code == MULT_EXPR && sgn1 == sgn2) /* For addition, the operands must be of the same sign to yield an overflow. Its sign is therefore that of one of the operands, for example the first. For infinite operands X + -INF is negative, not positive. */ || (code == PLUS_EXPR && (sgn1 >= 0 ? !is_negative_overflow_infinity (val2) : is_positive_overflow_infinity (val2))) /* For subtraction, non-infinite operands must be of different signs to yield an overflow. Its sign is therefore that of the first operand or the opposite of that of the second operand. A first operand of 0 counts as positive here, for the corner case 0 - (-INF), which overflows, but must yield +INF. For infinite operands 0 - INF is negative, not positive. */ || (code == MINUS_EXPR && (sgn1 >= 0 ? !is_positive_overflow_infinity (val2) : is_negative_overflow_infinity (val2))) /* We only get in here with positive shift count, so the overflow direction is the same as the sign of val1. Actually rshift does not overflow at all, but we only handle the case of shifting overflowed -INF and +INF. */ || (code == RSHIFT_EXPR && sgn1 >= 0) /* For division, the only case is -INF / -1 = +INF. */ || code == TRUNC_DIV_EXPR || code == FLOOR_DIV_EXPR || code == CEIL_DIV_EXPR || code == EXACT_DIV_EXPR || code == ROUND_DIV_EXPR) return (needs_overflow_infinity (TREE_TYPE (res)) ? positive_overflow_infinity (TREE_TYPE (res)) : TYPE_MAX_VALUE (TREE_TYPE (res))); else return (needs_overflow_infinity (TREE_TYPE (res)) ? negative_overflow_infinity (TREE_TYPE (res)) : TYPE_MIN_VALUE (TREE_TYPE (res))); } return res; } /* Extract range information from a binary expression EXPR based on the ranges of each of its operands and the expression code. */ static void extract_range_from_binary_expr (value_range_t *vr, enum tree_code code, tree expr_type, tree op0, tree op1) { enum value_range_type type; tree min, max; int cmp; value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; /* Not all binary expressions can be applied to ranges in a meaningful way. Handle only arithmetic operations. */ if (code != PLUS_EXPR && code != MINUS_EXPR && code != POINTER_PLUS_EXPR && code != MULT_EXPR && code != TRUNC_DIV_EXPR && code != FLOOR_DIV_EXPR && code != CEIL_DIV_EXPR && code != EXACT_DIV_EXPR && code != ROUND_DIV_EXPR && code != TRUNC_MOD_EXPR && code != RSHIFT_EXPR && code != MIN_EXPR && code != MAX_EXPR && code != BIT_AND_EXPR && code != BIT_IOR_EXPR && code != TRUTH_AND_EXPR && code != TRUTH_OR_EXPR) { /* We can still do constant propagation here. */ tree const_op0 = op_with_constant_singleton_value_range (op0); tree const_op1 = op_with_constant_singleton_value_range (op1); if (const_op0 || const_op1) { tree tem = fold_binary (code, expr_type, const_op0 ? const_op0 : op0, const_op1 ? const_op1 : op1); if (tem && is_gimple_min_invariant (tem) && !is_overflow_infinity (tem)) { set_value_range (vr, VR_RANGE, tem, tem, NULL); return; } } set_value_range_to_varying (vr); return; } /* Get value ranges for each operand. For constant operands, create a new value range with the operand to simplify processing. */ if (TREE_CODE (op0) == SSA_NAME) vr0 = *(get_value_range (op0)); else if (is_gimple_min_invariant (op0)) set_value_range_to_value (&vr0, op0, NULL); else set_value_range_to_varying (&vr0); if (TREE_CODE (op1) == SSA_NAME) vr1 = *(get_value_range (op1)); else if (is_gimple_min_invariant (op1)) set_value_range_to_value (&vr1, op1, NULL); else set_value_range_to_varying (&vr1); /* If either range is UNDEFINED, so is the result. */ if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED) { set_value_range_to_undefined (vr); return; } /* The type of the resulting value range defaults to VR0.TYPE. */ type = vr0.type; /* Refuse to operate on VARYING ranges, ranges of different kinds and symbolic ranges. As an exception, we allow BIT_AND_EXPR because we may be able to derive a useful range even if one of the operands is VR_VARYING or symbolic range. Similarly for divisions. TODO, we may be able to derive anti-ranges in some cases. */ if (code != BIT_AND_EXPR && code != TRUTH_AND_EXPR && code != TRUTH_OR_EXPR && code != TRUNC_DIV_EXPR && code != FLOOR_DIV_EXPR && code != CEIL_DIV_EXPR && code != EXACT_DIV_EXPR && code != ROUND_DIV_EXPR && code != TRUNC_MOD_EXPR && (vr0.type == VR_VARYING || vr1.type == VR_VARYING || vr0.type != vr1.type || symbolic_range_p (&vr0) || symbolic_range_p (&vr1))) { set_value_range_to_varying (vr); return; } /* Now evaluate the expression to determine the new range. */ if (POINTER_TYPE_P (expr_type) || POINTER_TYPE_P (TREE_TYPE (op0)) || POINTER_TYPE_P (TREE_TYPE (op1))) { if (code == MIN_EXPR || code == MAX_EXPR) { /* For MIN/MAX expressions with pointers, we only care about nullness, if both are non null, then the result is nonnull. If both are null, then the result is null. Otherwise they are varying. */ if (range_is_nonnull (&vr0) && range_is_nonnull (&vr1)) set_value_range_to_nonnull (vr, expr_type); else if (range_is_null (&vr0) && range_is_null (&vr1)) set_value_range_to_null (vr, expr_type); else set_value_range_to_varying (vr); return; } gcc_assert (code == POINTER_PLUS_EXPR); /* For pointer types, we are really only interested in asserting whether the expression evaluates to non-NULL. */ if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1)) set_value_range_to_nonnull (vr, expr_type); else if (range_is_null (&vr0) && range_is_null (&vr1)) set_value_range_to_null (vr, expr_type); else set_value_range_to_varying (vr); return; } /* For integer ranges, apply the operation to each end of the range and see what we end up with. */ if (code == TRUTH_AND_EXPR || code == TRUTH_OR_EXPR) { /* If one of the operands is zero, we know that the whole expression evaluates zero. */ if (code == TRUTH_AND_EXPR && ((vr0.type == VR_RANGE && integer_zerop (vr0.min) && integer_zerop (vr0.max)) || (vr1.type == VR_RANGE && integer_zerop (vr1.min) && integer_zerop (vr1.max)))) { type = VR_RANGE; min = max = build_int_cst (expr_type, 0); } /* If one of the operands is one, we know that the whole expression evaluates one. */ else if (code == TRUTH_OR_EXPR && ((vr0.type == VR_RANGE && integer_onep (vr0.min) && integer_onep (vr0.max)) || (vr1.type == VR_RANGE && integer_onep (vr1.min) && integer_onep (vr1.max)))) { type = VR_RANGE; min = max = build_int_cst (expr_type, 1); } else if (vr0.type != VR_VARYING && vr1.type != VR_VARYING && vr0.type == vr1.type && !symbolic_range_p (&vr0) && !overflow_infinity_range_p (&vr0) && !symbolic_range_p (&vr1) && !overflow_infinity_range_p (&vr1)) { /* Boolean expressions cannot be folded with int_const_binop. */ min = fold_binary (code, expr_type, vr0.min, vr1.min); max = fold_binary (code, expr_type, vr0.max, vr1.max); } else { /* The result of a TRUTH_*_EXPR is always true or false. */ set_value_range_to_truthvalue (vr, expr_type); return; } } else if (code == PLUS_EXPR || code == MIN_EXPR || code == MAX_EXPR) { /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to VR_VARYING. It would take more effort to compute a precise range for such a case. For example, if we have op0 == 1 and op1 == -1 with their ranges both being ~[0,0], we would have op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0]. Note that we are guaranteed to have vr0.type == vr1.type at this point. */ if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE) { set_value_range_to_varying (vr); return; } /* For operations that make the resulting range directly proportional to the original ranges, apply the operation to the same end of each range. */ min = vrp_int_const_binop (code, vr0.min, vr1.min); max = vrp_int_const_binop (code, vr0.max, vr1.max); /* If both additions overflowed the range kind is still correct. This happens regularly with subtracting something in unsigned arithmetic. ??? See PR30318 for all the cases we do not handle. */ if (code == PLUS_EXPR && (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) && (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) { min = build_int_cst_wide (TREE_TYPE (min), TREE_INT_CST_LOW (min), TREE_INT_CST_HIGH (min)); max = build_int_cst_wide (TREE_TYPE (max), TREE_INT_CST_LOW (max), TREE_INT_CST_HIGH (max)); } } else if (code == MULT_EXPR || code == TRUNC_DIV_EXPR || code == FLOOR_DIV_EXPR || code == CEIL_DIV_EXPR || code == EXACT_DIV_EXPR || code == ROUND_DIV_EXPR || code == RSHIFT_EXPR) { tree val[4]; size_t i; bool sop; /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs, drop to VR_VARYING. It would take more effort to compute a precise range for such a case. For example, if we have op0 == 65536 and op1 == 65536 with their ranges both being ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so we cannot claim that the product is in ~[0,0]. Note that we are guaranteed to have vr0.type == vr1.type at this point. */ if (code == MULT_EXPR && vr0.type == VR_ANTI_RANGE && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0))) { set_value_range_to_varying (vr); return; } /* If we have a RSHIFT_EXPR with any shift values outside [0..prec-1], then drop to VR_VARYING. Outside of this range we get undefined behavior from the shift operation. We cannot even trust SHIFT_COUNT_TRUNCATED at this stage, because that applies to rtl shifts, and the operation at the tree level may be widened. */ if (code == RSHIFT_EXPR) { if (vr1.type == VR_ANTI_RANGE || !vrp_expr_computes_nonnegative (op1, &sop) || (operand_less_p (build_int_cst (TREE_TYPE (vr1.max), TYPE_PRECISION (expr_type) - 1), vr1.max) != 0)) { set_value_range_to_varying (vr); return; } } else if ((code == TRUNC_DIV_EXPR || code == FLOOR_DIV_EXPR || code == CEIL_DIV_EXPR || code == EXACT_DIV_EXPR || code == ROUND_DIV_EXPR) && (vr0.type != VR_RANGE || symbolic_range_p (&vr0))) { /* For division, if op1 has VR_RANGE but op0 does not, something can be deduced just from that range. Say [min, max] / [4, max] gives [min / 4, max / 4] range. */ if (vr1.type == VR_RANGE && !symbolic_range_p (&vr1) && !range_includes_zero_p (&vr1)) { vr0.type = type = VR_RANGE; vr0.min = vrp_val_min (TREE_TYPE (op0)); vr0.max = vrp_val_max (TREE_TYPE (op1)); } else { set_value_range_to_varying (vr); return; } } /* For divisions, if op0 is VR_RANGE, we can deduce a range even if op1 is VR_VARYING, VR_ANTI_RANGE, symbolic or can include 0. */ if ((code == TRUNC_DIV_EXPR || code == FLOOR_DIV_EXPR || code == CEIL_DIV_EXPR || code == EXACT_DIV_EXPR || code == ROUND_DIV_EXPR) && vr0.type == VR_RANGE && (vr1.type != VR_RANGE || symbolic_range_p (&vr1) || range_includes_zero_p (&vr1))) { tree zero = build_int_cst (TREE_TYPE (vr0.min), 0); int cmp; sop = false; min = NULL_TREE; max = NULL_TREE; if (vrp_expr_computes_nonnegative (op1, &sop) && !sop) { /* For unsigned division or when divisor is known to be non-negative, the range has to cover all numbers from 0 to max for positive max and all numbers from min to 0 for negative min. */ cmp = compare_values (vr0.max, zero); if (cmp == -1) max = zero; else if (cmp == 0 || cmp == 1) max = vr0.max; else type = VR_VARYING; cmp = compare_values (vr0.min, zero); if (cmp == 1) min = zero; else if (cmp == 0 || cmp == -1) min = vr0.min; else type = VR_VARYING; } else { /* Otherwise the range is -max .. max or min .. -min depending on which bound is bigger in absolute value, as the division can change the sign. */ abs_extent_range (vr, vr0.min, vr0.max); return; } if (type == VR_VARYING) { set_value_range_to_varying (vr); return; } } /* Multiplications and divisions are a bit tricky to handle, depending on the mix of signs we have in the two ranges, we need to operate on different values to get the minimum and maximum values for the new range. One approach is to figure out all the variations of range combinations and do the operations. However, this involves several calls to compare_values and it is pretty convoluted. It's simpler to do the 4 operations (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP MAX1) and then figure the smallest and largest values to form the new range. */ else { gcc_assert ((vr0.type == VR_RANGE || (code == MULT_EXPR && vr0.type == VR_ANTI_RANGE)) && vr0.type == vr1.type); /* Compute the 4 cross operations. */ sop = false; val[0] = vrp_int_const_binop (code, vr0.min, vr1.min); if (val[0] == NULL_TREE) sop = true; if (vr1.max == vr1.min) val[1] = NULL_TREE; else { val[1] = vrp_int_const_binop (code, vr0.min, vr1.max); if (val[1] == NULL_TREE) sop = true; } if (vr0.max == vr0.min) val[2] = NULL_TREE; else { val[2] = vrp_int_const_binop (code, vr0.max, vr1.min); if (val[2] == NULL_TREE) sop = true; } if (vr0.min == vr0.max || vr1.min == vr1.max) val[3] = NULL_TREE; else { val[3] = vrp_int_const_binop (code, vr0.max, vr1.max); if (val[3] == NULL_TREE) sop = true; } if (sop) { set_value_range_to_varying (vr); return; } /* Set MIN to the minimum of VAL[i] and MAX to the maximum of VAL[i]. */ min = val[0]; max = val[0]; for (i = 1; i < 4; i++) { if (!is_gimple_min_invariant (min) || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) || !is_gimple_min_invariant (max) || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) break; if (val[i]) { if (!is_gimple_min_invariant (val[i]) || (TREE_OVERFLOW (val[i]) && !is_overflow_infinity (val[i]))) { /* If we found an overflowed value, set MIN and MAX to it so that we set the resulting range to VARYING. */ min = max = val[i]; break; } if (compare_values (val[i], min) == -1) min = val[i]; if (compare_values (val[i], max) == 1) max = val[i]; } } } } else if (code == TRUNC_MOD_EXPR) { bool sop = false; if (vr1.type != VR_RANGE || symbolic_range_p (&vr1) || range_includes_zero_p (&vr1) || vrp_val_is_min (vr1.min)) { set_value_range_to_varying (vr); return; } type = VR_RANGE; /* Compute MAX <|vr1.min|, |vr1.max|> - 1. */ max = fold_unary_to_constant (ABS_EXPR, TREE_TYPE (vr1.min), vr1.min); if (tree_int_cst_lt (max, vr1.max)) max = vr1.max; max = int_const_binop (MINUS_EXPR, max, integer_one_node, 0); /* If the dividend is non-negative the modulus will be non-negative as well. */ if (TYPE_UNSIGNED (TREE_TYPE (max)) || (vrp_expr_computes_nonnegative (op0, &sop) && !sop)) min = build_int_cst (TREE_TYPE (max), 0); else min = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (max), max); } else if (code == MINUS_EXPR) { /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to VR_VARYING. It would take more effort to compute a precise range for such a case. For example, if we have op0 == 1 and op1 == 1 with their ranges both being ~[0,0], we would have op0 - op1 == 0, so we cannot claim that the difference is in ~[0,0]. Note that we are guaranteed to have vr0.type == vr1.type at this point. */ if (vr0.type == VR_ANTI_RANGE) { set_value_range_to_varying (vr); return; } /* For MINUS_EXPR, apply the operation to the opposite ends of each range. */ min = vrp_int_const_binop (code, vr0.min, vr1.max); max = vrp_int_const_binop (code, vr0.max, vr1.min); } else if (code == BIT_AND_EXPR) { bool vr0_int_cst_singleton_p, vr1_int_cst_singleton_p; vr0_int_cst_singleton_p = range_int_cst_singleton_p (&vr0); vr1_int_cst_singleton_p = range_int_cst_singleton_p (&vr1); if (vr0_int_cst_singleton_p && vr1_int_cst_singleton_p) min = max = int_const_binop (code, vr0.max, vr1.max, 0); else if (vr0_int_cst_singleton_p && tree_int_cst_sgn (vr0.max) >= 0) { min = build_int_cst (expr_type, 0); max = vr0.max; } else if (vr1_int_cst_singleton_p && tree_int_cst_sgn (vr1.max) >= 0) { type = VR_RANGE; min = build_int_cst (expr_type, 0); max = vr1.max; } else { set_value_range_to_varying (vr); return; } } else if (code == BIT_IOR_EXPR) { if (range_int_cst_p (&vr0) && range_int_cst_p (&vr1) && tree_int_cst_sgn (vr0.min) >= 0 && tree_int_cst_sgn (vr1.min) >= 0) { double_int vr0_max = tree_to_double_int (vr0.max); double_int vr1_max = tree_to_double_int (vr1.max); double_int ior_max; /* Set all bits to the right of the most significant one to 1. For example, [0, 4] | [4, 4] = [4, 7]. */ ior_max.low = vr0_max.low | vr1_max.low; ior_max.high = vr0_max.high | vr1_max.high; if (ior_max.high != 0) { ior_max.low = ~(unsigned HOST_WIDE_INT)0u; ior_max.high |= ((HOST_WIDE_INT) 1 << floor_log2 (ior_max.high)) - 1; } else if (ior_max.low != 0) ior_max.low |= ((unsigned HOST_WIDE_INT) 1u << floor_log2 (ior_max.low)) - 1; /* Both of these endpoints are conservative. */ min = vrp_int_const_binop (MAX_EXPR, vr0.min, vr1.min); max = double_int_to_tree (expr_type, ior_max); } else { set_value_range_to_varying (vr); return; } } else gcc_unreachable (); /* If either MIN or MAX overflowed, then set the resulting range to VARYING. But we do accept an overflow infinity representation. */ if (min == NULL_TREE || !is_gimple_min_invariant (min) || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) || max == NULL_TREE || !is_gimple_min_invariant (max) || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) { set_value_range_to_varying (vr); return; } /* We punt if: 1) [-INF, +INF] 2) [-INF, +-INF(OVF)] 3) [+-INF(OVF), +INF] 4) [+-INF(OVF), +-INF(OVF)] We learn nothing when we have INF and INF(OVF) on both sides. Note that we do accept [-INF, -INF] and [+INF, +INF] without overflow. */ if ((vrp_val_is_min (min) || is_overflow_infinity (min)) && (vrp_val_is_max (max) || is_overflow_infinity (max))) { set_value_range_to_varying (vr); return; } cmp = compare_values (min, max); if (cmp == -2 || cmp == 1) { /* If the new range has its limits swapped around (MIN > MAX), then the operation caused one of them to wrap around, mark the new range VARYING. */ set_value_range_to_varying (vr); } else set_value_range (vr, type, min, max, NULL); } /* Extract range information from a unary expression EXPR based on the range of its operand and the expression code. */ static void extract_range_from_unary_expr (value_range_t *vr, enum tree_code code, tree type, tree op0) { tree min, max; int cmp; value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; /* Refuse to operate on certain unary expressions for which we cannot easily determine a resulting range. */ if (code == FIX_TRUNC_EXPR || code == FLOAT_EXPR || code == BIT_NOT_EXPR || code == CONJ_EXPR) { /* We can still do constant propagation here. */ if ((op0 = op_with_constant_singleton_value_range (op0)) != NULL_TREE) { tree tem = fold_unary (code, type, op0); if (tem && is_gimple_min_invariant (tem) && !is_overflow_infinity (tem)) { set_value_range (vr, VR_RANGE, tem, tem, NULL); return; } } set_value_range_to_varying (vr); return; } /* Get value ranges for the operand. For constant operands, create a new value range with the operand to simplify processing. */ if (TREE_CODE (op0) == SSA_NAME) vr0 = *(get_value_range (op0)); else if (is_gimple_min_invariant (op0)) set_value_range_to_value (&vr0, op0, NULL); else set_value_range_to_varying (&vr0); /* If VR0 is UNDEFINED, so is the result. */ if (vr0.type == VR_UNDEFINED) { set_value_range_to_undefined (vr); return; } /* Refuse to operate on symbolic ranges, or if neither operand is a pointer or integral type. */ if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0)) && !POINTER_TYPE_P (TREE_TYPE (op0))) || (vr0.type != VR_VARYING && symbolic_range_p (&vr0))) { set_value_range_to_varying (vr); return; } /* If the expression involves pointers, we are only interested in determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */ if (POINTER_TYPE_P (type) || POINTER_TYPE_P (TREE_TYPE (op0))) { bool sop; sop = false; if (range_is_nonnull (&vr0) || (tree_unary_nonzero_warnv_p (code, type, op0, &sop) && !sop)) set_value_range_to_nonnull (vr, type); else if (range_is_null (&vr0)) set_value_range_to_null (vr, type); else set_value_range_to_varying (vr); return; } /* Handle unary expressions on integer ranges. */ if (CONVERT_EXPR_CODE_P (code) && INTEGRAL_TYPE_P (type) && INTEGRAL_TYPE_P (TREE_TYPE (op0))) { tree inner_type = TREE_TYPE (op0); tree outer_type = type; /* If VR0 is varying and we increase the type precision, assume a full range for the following transformation. */ if (vr0.type == VR_VARYING && TYPE_PRECISION (inner_type) < TYPE_PRECISION (outer_type)) { vr0.type = VR_RANGE; vr0.min = TYPE_MIN_VALUE (inner_type); vr0.max = TYPE_MAX_VALUE (inner_type); } /* If VR0 is a constant range or anti-range and the conversion is not truncating we can convert the min and max values and canonicalize the resulting range. Otherwise we can do the conversion if the size of the range is less than what the precision of the target type can represent and the range is not an anti-range. */ if ((vr0.type == VR_RANGE || vr0.type == VR_ANTI_RANGE) && TREE_CODE (vr0.min) == INTEGER_CST && TREE_CODE (vr0.max) == INTEGER_CST && (!is_overflow_infinity (vr0.min) || (vr0.type == VR_RANGE && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type) && needs_overflow_infinity (outer_type) && supports_overflow_infinity (outer_type))) && (!is_overflow_infinity (vr0.max) || (vr0.type == VR_RANGE && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type) && needs_overflow_infinity (outer_type) && supports_overflow_infinity (outer_type))) && (TYPE_PRECISION (outer_type) >= TYPE_PRECISION (inner_type) || (vr0.type == VR_RANGE && integer_zerop (int_const_binop (RSHIFT_EXPR, int_const_binop (MINUS_EXPR, vr0.max, vr0.min, 0), size_int (TYPE_PRECISION (outer_type)), 0))))) { tree new_min, new_max; new_min = force_fit_type_double (outer_type, TREE_INT_CST_LOW (vr0.min), TREE_INT_CST_HIGH (vr0.min), 0, 0); new_max = force_fit_type_double (outer_type, TREE_INT_CST_LOW (vr0.max), TREE_INT_CST_HIGH (vr0.max), 0, 0); if (is_overflow_infinity (vr0.min)) new_min = negative_overflow_infinity (outer_type); if (is_overflow_infinity (vr0.max)) new_max = positive_overflow_infinity (outer_type); set_and_canonicalize_value_range (vr, vr0.type, new_min, new_max, NULL); return; } set_value_range_to_varying (vr); return; } /* Conversion of a VR_VARYING value to a wider type can result in a usable range. So wait until after we've handled conversions before dropping the result to VR_VARYING if we had a source operand that is VR_VARYING. */ if (vr0.type == VR_VARYING) { set_value_range_to_varying (vr); return; } /* Apply the operation to each end of the range and see what we end up with. */ if (code == NEGATE_EXPR && !TYPE_UNSIGNED (type)) { /* NEGATE_EXPR flips the range around. We need to treat TYPE_MIN_VALUE specially. */ if (is_positive_overflow_infinity (vr0.max)) min = negative_overflow_infinity (type); else if (is_negative_overflow_infinity (vr0.max)) min = positive_overflow_infinity (type); else if (!vrp_val_is_min (vr0.max)) min = fold_unary_to_constant (code, type, vr0.max); else if (needs_overflow_infinity (type)) { if (supports_overflow_infinity (type) && !is_overflow_infinity (vr0.min) && !vrp_val_is_min (vr0.min)) min = positive_overflow_infinity (type); else { set_value_range_to_varying (vr); return; } } else min = TYPE_MIN_VALUE (type); if (is_positive_overflow_infinity (vr0.min)) max = negative_overflow_infinity (type); else if (is_negative_overflow_infinity (vr0.min)) max = positive_overflow_infinity (type); else if (!vrp_val_is_min (vr0.min)) max = fold_unary_to_constant (code, type, vr0.min); else if (needs_overflow_infinity (type)) { if (supports_overflow_infinity (type)) max = positive_overflow_infinity (type); else { set_value_range_to_varying (vr); return; } } else max = TYPE_MIN_VALUE (type); } else if (code == NEGATE_EXPR && TYPE_UNSIGNED (type)) { if (!range_includes_zero_p (&vr0)) { max = fold_unary_to_constant (code, type, vr0.min); min = fold_unary_to_constant (code, type, vr0.max); } else { if (range_is_null (&vr0)) set_value_range_to_null (vr, type); else set_value_range_to_varying (vr); return; } } else if (code == ABS_EXPR && !TYPE_UNSIGNED (type)) { /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a useful range. */ if (!TYPE_OVERFLOW_UNDEFINED (type) && ((vr0.type == VR_RANGE && vrp_val_is_min (vr0.min)) || (vr0.type == VR_ANTI_RANGE && !vrp_val_is_min (vr0.min) && !range_includes_zero_p (&vr0)))) { set_value_range_to_varying (vr); return; } /* ABS_EXPR may flip the range around, if the original range included negative values. */ if (is_overflow_infinity (vr0.min)) min = positive_overflow_infinity (type); else if (!vrp_val_is_min (vr0.min)) min = fold_unary_to_constant (code, type, vr0.min); else if (!needs_overflow_infinity (type)) min = TYPE_MAX_VALUE (type); else if (supports_overflow_infinity (type)) min = positive_overflow_infinity (type); else { set_value_range_to_varying (vr); return; } if (is_overflow_infinity (vr0.max)) max = positive_overflow_infinity (type); else if (!vrp_val_is_min (vr0.max)) max = fold_unary_to_constant (code, type, vr0.max); else if (!needs_overflow_infinity (type)) max = TYPE_MAX_VALUE (type); else if (supports_overflow_infinity (type) /* We shouldn't generate [+INF, +INF] as set_value_range doesn't like this and ICEs. */ && !is_positive_overflow_infinity (min)) max = positive_overflow_infinity (type); else { set_value_range_to_varying (vr); return; } cmp = compare_values (min, max); /* If a VR_ANTI_RANGEs contains zero, then we have ~[-INF, min(MIN, MAX)]. */ if (vr0.type == VR_ANTI_RANGE) { if (range_includes_zero_p (&vr0)) { /* Take the lower of the two values. */ if (cmp != 1) max = min; /* Create ~[-INF, min (abs(MIN), abs(MAX))] or ~[-INF + 1, min (abs(MIN), abs(MAX))] when flag_wrapv is set and the original anti-range doesn't include TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */ if (TYPE_OVERFLOW_WRAPS (type)) { tree type_min_value = TYPE_MIN_VALUE (type); min = (vr0.min != type_min_value ? int_const_binop (PLUS_EXPR, type_min_value, integer_one_node, 0) : type_min_value); } else { if (overflow_infinity_range_p (&vr0)) min = negative_overflow_infinity (type); else min = TYPE_MIN_VALUE (type); } } else { /* All else has failed, so create the range [0, INF], even for flag_wrapv since TYPE_MIN_VALUE is in the original anti-range. */ vr0.type = VR_RANGE; min = build_int_cst (type, 0); if (needs_overflow_infinity (type)) { if (supports_overflow_infinity (type)) max = positive_overflow_infinity (type); else { set_value_range_to_varying (vr); return; } } else max = TYPE_MAX_VALUE (type); } } /* If the range contains zero then we know that the minimum value in the range will be zero. */ else if (range_includes_zero_p (&vr0)) { if (cmp == 1) max = min; min = build_int_cst (type, 0); } else { /* If the range was reversed, swap MIN and MAX. */ if (cmp == 1) { tree t = min; min = max; max = t; } } } else { /* Otherwise, operate on each end of the range. */ min = fold_unary_to_constant (code, type, vr0.min); max = fold_unary_to_constant (code, type, vr0.max); if (needs_overflow_infinity (type)) { gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR); /* If both sides have overflowed, we don't know anything. */ if ((is_overflow_infinity (vr0.min) || TREE_OVERFLOW (min)) && (is_overflow_infinity (vr0.max) || TREE_OVERFLOW (max))) { set_value_range_to_varying (vr); return; } if (is_overflow_infinity (vr0.min)) min = vr0.min; else if (TREE_OVERFLOW (min)) { if (supports_overflow_infinity (type)) min = (tree_int_cst_sgn (min) >= 0 ? positive_overflow_infinity (TREE_TYPE (min)) : negative_overflow_infinity (TREE_TYPE (min))); else { set_value_range_to_varying (vr); return; } } if (is_overflow_infinity (vr0.max)) max = vr0.max; else if (TREE_OVERFLOW (max)) { if (supports_overflow_infinity (type)) max = (tree_int_cst_sgn (max) >= 0 ? positive_overflow_infinity (TREE_TYPE (max)) : negative_overflow_infinity (TREE_TYPE (max))); else { set_value_range_to_varying (vr); return; } } } } cmp = compare_values (min, max); if (cmp == -2 || cmp == 1) { /* If the new range has its limits swapped around (MIN > MAX), then the operation caused one of them to wrap around, mark the new range VARYING. */ set_value_range_to_varying (vr); } else set_value_range (vr, vr0.type, min, max, NULL); } /* Extract range information from a conditional expression EXPR based on the ranges of each of its operands and the expression code. */ static void extract_range_from_cond_expr (value_range_t *vr, tree expr) { tree op0, op1; value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; /* Get value ranges for each operand. For constant operands, create a new value range with the operand to simplify processing. */ op0 = COND_EXPR_THEN (expr); if (TREE_CODE (op0) == SSA_NAME) vr0 = *(get_value_range (op0)); else if (is_gimple_min_invariant (op0)) set_value_range_to_value (&vr0, op0, NULL); else set_value_range_to_varying (&vr0); op1 = COND_EXPR_ELSE (expr); if (TREE_CODE (op1) == SSA_NAME) vr1 = *(get_value_range (op1)); else if (is_gimple_min_invariant (op1)) set_value_range_to_value (&vr1, op1, NULL); else set_value_range_to_varying (&vr1); /* The resulting value range is the union of the operand ranges */ vrp_meet (&vr0, &vr1); copy_value_range (vr, &vr0); } /* Extract range information from a comparison expression EXPR based on the range of its operand and the expression code. */ static void extract_range_from_comparison (value_range_t *vr, enum tree_code code, tree type, tree op0, tree op1) { bool sop = false; tree val; val = vrp_evaluate_conditional_warnv_with_ops (code, op0, op1, false, &sop, NULL); /* A disadvantage of using a special infinity as an overflow representation is that we lose the ability to record overflow when we don't have an infinity. So we have to ignore a result which relies on overflow. */ if (val && !is_overflow_infinity (val) && !sop) { /* Since this expression was found on the RHS of an assignment, its type may be different from _Bool. Convert VAL to EXPR's type. */ val = fold_convert (type, val); if (is_gimple_min_invariant (val)) set_value_range_to_value (vr, val, vr->equiv); else set_value_range (vr, VR_RANGE, val, val, vr->equiv); } else /* The result of a comparison is always true or false. */ set_value_range_to_truthvalue (vr, type); } /* Try to derive a nonnegative or nonzero range out of STMT relying primarily on generic routines in fold in conjunction with range data. Store the result in *VR */ static void extract_range_basic (value_range_t *vr, gimple stmt) { bool sop = false; tree type = gimple_expr_type (stmt); if (INTEGRAL_TYPE_P (type) && gimple_stmt_nonnegative_warnv_p (stmt, &sop)) set_value_range_to_nonnegative (vr, type, sop || stmt_overflow_infinity (stmt)); else if (vrp_stmt_computes_nonzero (stmt, &sop) && !sop) set_value_range_to_nonnull (vr, type); else set_value_range_to_varying (vr); } /* Try to compute a useful range out of assignment STMT and store it in *VR. */ static void extract_range_from_assignment (value_range_t *vr, gimple stmt) { enum tree_code code = gimple_assign_rhs_code (stmt); if (code == ASSERT_EXPR) extract_range_from_assert (vr, gimple_assign_rhs1 (stmt)); else if (code == SSA_NAME) extract_range_from_ssa_name (vr, gimple_assign_rhs1 (stmt)); else if (TREE_CODE_CLASS (code) == tcc_binary || code == TRUTH_AND_EXPR || code == TRUTH_OR_EXPR || code == TRUTH_XOR_EXPR) extract_range_from_binary_expr (vr, gimple_assign_rhs_code (stmt), gimple_expr_type (stmt), gimple_assign_rhs1 (stmt), gimple_assign_rhs2 (stmt)); else if (TREE_CODE_CLASS (code) == tcc_unary) extract_range_from_unary_expr (vr, gimple_assign_rhs_code (stmt), gimple_expr_type (stmt), gimple_assign_rhs1 (stmt)); else if (code == COND_EXPR) extract_range_from_cond_expr (vr, gimple_assign_rhs1 (stmt)); else if (TREE_CODE_CLASS (code) == tcc_comparison) extract_range_from_comparison (vr, gimple_assign_rhs_code (stmt), gimple_expr_type (stmt), gimple_assign_rhs1 (stmt), gimple_assign_rhs2 (stmt)); else if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS && is_gimple_min_invariant (gimple_assign_rhs1 (stmt))) set_value_range_to_value (vr, gimple_assign_rhs1 (stmt), NULL); else set_value_range_to_varying (vr); if (vr->type == VR_VARYING) extract_range_basic (vr, stmt); } /* Given a range VR, a LOOP and a variable VAR, determine whether it would be profitable to adjust VR using scalar evolution information for VAR. If so, update VR with the new limits. */ static void adjust_range_with_scev (value_range_t *vr, struct loop *loop, gimple stmt, tree var) { tree init, step, chrec, tmin, tmax, min, max, type, tem; enum ev_direction dir; /* TODO. Don't adjust anti-ranges. An anti-range may provide better opportunities than a regular range, but I'm not sure. */ if (vr->type == VR_ANTI_RANGE) return; chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var)); /* Like in PR19590, scev can return a constant function. */ if (is_gimple_min_invariant (chrec)) { set_value_range_to_value (vr, chrec, vr->equiv); return; } if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) return; init = initial_condition_in_loop_num (chrec, loop->num); tem = op_with_constant_singleton_value_range (init); if (tem) init = tem; step = evolution_part_in_loop_num (chrec, loop->num); tem = op_with_constant_singleton_value_range (step); if (tem) step = tem; /* If STEP is symbolic, we can't know whether INIT will be the minimum or maximum value in the range. Also, unless INIT is a simple expression, compare_values and possibly other functions in tree-vrp won't be able to handle it. */ if (step == NULL_TREE || !is_gimple_min_invariant (step) || !valid_value_p (init)) return; dir = scev_direction (chrec); if (/* Do not adjust ranges if we do not know whether the iv increases or decreases, ... */ dir == EV_DIR_UNKNOWN /* ... or if it may wrap. */ || scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec), true)) return; /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of negative_overflow_infinity and positive_overflow_infinity, because we have concluded that the loop probably does not wrap. */ type = TREE_TYPE (var); if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type)) tmin = lower_bound_in_type (type, type); else tmin = TYPE_MIN_VALUE (type); if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type)) tmax = upper_bound_in_type (type, type); else tmax = TYPE_MAX_VALUE (type); if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED) { min = tmin; max = tmax; /* For VARYING or UNDEFINED ranges, just about anything we get from scalar evolutions should be better. */ if (dir == EV_DIR_DECREASES) max = init; else min = init; /* If we would create an invalid range, then just assume we know absolutely nothing. This may be over-conservative, but it's clearly safe, and should happen only in unreachable parts of code, or for invalid programs. */ if (compare_values (min, max) == 1) return; set_value_range (vr, VR_RANGE, min, max, vr->equiv); } else if (vr->type == VR_RANGE) { min = vr->min; max = vr->max; if (dir == EV_DIR_DECREASES) { /* INIT is the maximum value. If INIT is lower than VR->MAX but no smaller than VR->MIN, set VR->MAX to INIT. */ if (compare_values (init, max) == -1) { max = init; /* If we just created an invalid range with the minimum greater than the maximum, we fail conservatively. This should happen only in unreachable parts of code, or for invalid programs. */ if (compare_values (min, max) == 1) return; } /* According to the loop information, the variable does not overflow. If we think it does, probably because of an overflow due to arithmetic on a different INF value, reset now. */ if (is_negative_overflow_infinity (min)) min = tmin; } else { /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */ if (compare_values (init, min) == 1) { min = init; /* Again, avoid creating invalid range by failing. */ if (compare_values (min, max) == 1) return; } if (is_positive_overflow_infinity (max)) max = tmax; } set_value_range (vr, VR_RANGE, min, max, vr->equiv); } } /* Return true if VAR may overflow at STMT. This checks any available loop information to see if we can determine that VAR does not overflow. */ static bool vrp_var_may_overflow (tree var, gimple stmt) { struct loop *l; tree chrec, init, step; if (current_loops == NULL) return true; l = loop_containing_stmt (stmt); if (l == NULL || !loop_outer (l)) return true; chrec = instantiate_parameters (l, analyze_scalar_evolution (l, var)); if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) return true; init = initial_condition_in_loop_num (chrec, l->num); step = evolution_part_in_loop_num (chrec, l->num); if (step == NULL_TREE || !is_gimple_min_invariant (step) || !valid_value_p (init)) return true; /* If we get here, we know something useful about VAR based on the loop information. If it wraps, it may overflow. */ if (scev_probably_wraps_p (init, step, stmt, get_chrec_loop (chrec), true)) return true; if (dump_file && (dump_flags & TDF_DETAILS) != 0) { print_generic_expr (dump_file, var, 0); fprintf (dump_file, ": loop information indicates does not overflow\n"); } return false; } /* Given two numeric value ranges VR0, VR1 and a comparison code COMP: - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for all the values in the ranges. - Return BOOLEAN_FALSE_NODE if the comparison always returns false. - Return NULL_TREE if it is not always possible to determine the value of the comparison. Also set *STRICT_OVERFLOW_P to indicate whether a range with an overflow infinity was used in the test. */ static tree compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1, bool *strict_overflow_p) { /* VARYING or UNDEFINED ranges cannot be compared. */ if (vr0->type == VR_VARYING || vr0->type == VR_UNDEFINED || vr1->type == VR_VARYING || vr1->type == VR_UNDEFINED) return NULL_TREE; /* Anti-ranges need to be handled separately. */ if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE) { /* If both are anti-ranges, then we cannot compute any comparison. */ if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE) return NULL_TREE; /* These comparisons are never statically computable. */ if (comp == GT_EXPR || comp == GE_EXPR || comp == LT_EXPR || comp == LE_EXPR) return NULL_TREE; /* Equality can be computed only between a range and an anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */ if (vr0->type == VR_RANGE) { /* To simplify processing, make VR0 the anti-range. */ value_range_t *tmp = vr0; vr0 = vr1; vr1 = tmp; } gcc_assert (comp == NE_EXPR || comp == EQ_EXPR); if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0) return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node; return NULL_TREE; } if (!usable_range_p (vr0, strict_overflow_p) || !usable_range_p (vr1, strict_overflow_p)) return NULL_TREE; /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the operands around and change the comparison code. */ if (comp == GT_EXPR || comp == GE_EXPR) { value_range_t *tmp; comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR; tmp = vr0; vr0 = vr1; vr1 = tmp; } if (comp == EQ_EXPR) { /* Equality may only be computed if both ranges represent exactly one value. */ if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0) { int cmp_min = compare_values_warnv (vr0->min, vr1->min, strict_overflow_p); int cmp_max = compare_values_warnv (vr0->max, vr1->max, strict_overflow_p); if (cmp_min == 0 && cmp_max == 0) return boolean_true_node; else if (cmp_min != -2 && cmp_max != -2) return boolean_false_node; } /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */ else if (compare_values_warnv (vr0->min, vr1->max, strict_overflow_p) == 1 || compare_values_warnv (vr1->min, vr0->max, strict_overflow_p) == 1) return boolean_false_node; return NULL_TREE; } else if (comp == NE_EXPR) { int cmp1, cmp2; /* If VR0 is completely to the left or completely to the right of VR1, they are always different. Notice that we need to make sure that both comparisons yield similar results to avoid comparing values that cannot be compared at compile-time. */ cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p); cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p); if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1)) return boolean_true_node; /* If VR0 and VR1 represent a single value and are identical, return false. */ else if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0 && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0 && compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0 && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0) return boolean_false_node; /* Otherwise, they may or may not be different. */ else return NULL_TREE; } else if (comp == LT_EXPR || comp == LE_EXPR) { int tst; /* If VR0 is to the left of VR1, return true. */ tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p); if ((comp == LT_EXPR && tst == -1) || (comp == LE_EXPR && (tst == -1 || tst == 0))) { if (overflow_infinity_range_p (vr0) || overflow_infinity_range_p (vr1)) *strict_overflow_p = true; return boolean_true_node; } /* If VR0 is to the right of VR1, return false. */ tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p); if ((comp == LT_EXPR && (tst == 0 || tst == 1)) || (comp == LE_EXPR && tst == 1)) { if (overflow_infinity_range_p (vr0) || overflow_infinity_range_p (vr1)) *strict_overflow_p = true; return boolean_false_node; } /* Otherwise, we don't know. */ return NULL_TREE; } gcc_unreachable (); } /* Given a value range VR, a value VAL and a comparison code COMP, return BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the values in VR. Return BOOLEAN_FALSE_NODE if the comparison always returns false. Return NULL_TREE if it is not always possible to determine the value of the comparison. Also set *STRICT_OVERFLOW_P to indicate whether a range with an overflow infinity was used in the test. */ static tree compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val, bool *strict_overflow_p) { if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED) return NULL_TREE; /* Anti-ranges need to be handled separately. */ if (vr->type == VR_ANTI_RANGE) { /* For anti-ranges, the only predicates that we can compute at compile time are equality and inequality. */ if (comp == GT_EXPR || comp == GE_EXPR || comp == LT_EXPR || comp == LE_EXPR) return NULL_TREE; /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */ if (value_inside_range (val, vr) == 1) return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node; return NULL_TREE; } if (!usable_range_p (vr, strict_overflow_p)) return NULL_TREE; if (comp == EQ_EXPR) { /* EQ_EXPR may only be computed if VR represents exactly one value. */ if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0) { int cmp = compare_values_warnv (vr->min, val, strict_overflow_p); if (cmp == 0) return boolean_true_node; else if (cmp == -1 || cmp == 1 || cmp == 2) return boolean_false_node; } else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1 || compare_values_warnv (vr->max, val, strict_overflow_p) == -1) return boolean_false_node; return NULL_TREE; } else if (comp == NE_EXPR) { /* If VAL is not inside VR, then they are always different. */ if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1 || compare_values_warnv (vr->min, val, strict_overflow_p) == 1) return boolean_true_node; /* If VR represents exactly one value equal to VAL, then return false. */ if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0 && compare_values_warnv (vr->min, val, strict_overflow_p) == 0) return boolean_false_node; /* Otherwise, they may or may not be different. */ return NULL_TREE; } else if (comp == LT_EXPR || comp == LE_EXPR) { int tst; /* If VR is to the left of VAL, return true. */ tst = compare_values_warnv (vr->max, val, strict_overflow_p); if ((comp == LT_EXPR && tst == -1) || (comp == LE_EXPR && (tst == -1 || tst == 0))) { if (overflow_infinity_range_p (vr)) *strict_overflow_p = true; return boolean_true_node; } /* If VR is to the right of VAL, return false. */ tst = compare_values_warnv (vr->min, val, strict_overflow_p); if ((comp == LT_EXPR && (tst == 0 || tst == 1)) || (comp == LE_EXPR && tst == 1)) { if (overflow_infinity_range_p (vr)) *strict_overflow_p = true; return boolean_false_node; } /* Otherwise, we don't know. */ return NULL_TREE; } else if (comp == GT_EXPR || comp == GE_EXPR) { int tst; /* If VR is to the right of VAL, return true. */ tst = compare_values_warnv (vr->min, val, strict_overflow_p); if ((comp == GT_EXPR && tst == 1) || (comp == GE_EXPR && (tst == 0 || tst == 1))) { if (overflow_infinity_range_p (vr)) *strict_overflow_p = true; return boolean_true_node; } /* If VR is to the left of VAL, return false. */ tst = compare_values_warnv (vr->max, val, strict_overflow_p); if ((comp == GT_EXPR && (tst == -1 || tst == 0)) || (comp == GE_EXPR && tst == -1)) { if (overflow_infinity_range_p (vr)) *strict_overflow_p = true; return boolean_false_node; } /* Otherwise, we don't know. */ return NULL_TREE; } gcc_unreachable (); } /* Debugging dumps. */ void dump_value_range (FILE *, value_range_t *); void debug_value_range (value_range_t *); void dump_all_value_ranges (FILE *); void debug_all_value_ranges (void); void dump_vr_equiv (FILE *, bitmap); void debug_vr_equiv (bitmap); /* Dump value range VR to FILE. */ void dump_value_range (FILE *file, value_range_t *vr) { if (vr == NULL) fprintf (file, "[]"); else if (vr->type == VR_UNDEFINED) fprintf (file, "UNDEFINED"); else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE) { tree type = TREE_TYPE (vr->min); fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : ""); if (is_negative_overflow_infinity (vr->min)) fprintf (file, "-INF(OVF)"); else if (INTEGRAL_TYPE_P (type) && !TYPE_UNSIGNED (type) && vrp_val_is_min (vr->min)) fprintf (file, "-INF"); else print_generic_expr (file, vr->min, 0); fprintf (file, ", "); if (is_positive_overflow_infinity (vr->max)) fprintf (file, "+INF(OVF)"); else if (INTEGRAL_TYPE_P (type) && vrp_val_is_max (vr->max)) fprintf (file, "+INF"); else print_generic_expr (file, vr->max, 0); fprintf (file, "]"); if (vr->equiv) { bitmap_iterator bi; unsigned i, c = 0; fprintf (file, " EQUIVALENCES: { "); EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi) { print_generic_expr (file, ssa_name (i), 0); fprintf (file, " "); c++; } fprintf (file, "} (%u elements)", c); } } else if (vr->type == VR_VARYING) fprintf (file, "VARYING"); else fprintf (file, "INVALID RANGE"); } /* Dump value range VR to stderr. */ void debug_value_range (value_range_t *vr) { dump_value_range (stderr, vr); fprintf (stderr, "\n"); } /* Dump value ranges of all SSA_NAMEs to FILE. */ void dump_all_value_ranges (FILE *file) { size_t i; for (i = 0; i < num_ssa_names; i++) { if (vr_value[i]) { print_generic_expr (file, ssa_name (i), 0); fprintf (file, ": "); dump_value_range (file, vr_value[i]); fprintf (file, "\n"); } } fprintf (file, "\n"); } /* Dump all value ranges to stderr. */ void debug_all_value_ranges (void) { dump_all_value_ranges (stderr); } /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V, create a new SSA name N and return the assertion assignment 'V = ASSERT_EXPR <V, V OP W>'. */ static gimple build_assert_expr_for (tree cond, tree v) { tree n; gimple assertion; gcc_assert (TREE_CODE (v) == SSA_NAME); n = duplicate_ssa_name (v, NULL); if (COMPARISON_CLASS_P (cond)) { tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond); assertion = gimple_build_assign (n, a); } else if (TREE_CODE (cond) == TRUTH_NOT_EXPR) { /* Given !V, build the assignment N = false. */ tree op0 = TREE_OPERAND (cond, 0); gcc_assert (op0 == v); assertion = gimple_build_assign (n, boolean_false_node); } else if (TREE_CODE (cond) == SSA_NAME) { /* Given V, build the assignment N = true. */ gcc_assert (v == cond); assertion = gimple_build_assign (n, boolean_true_node); } else gcc_unreachable (); SSA_NAME_DEF_STMT (n) = assertion; /* The new ASSERT_EXPR, creates a new SSA name that replaces the operand of the ASSERT_EXPR. Register the new name and the old one in the replacement table so that we can fix the SSA web after adding all the ASSERT_EXPRs. */ register_new_name_mapping (n, v); return assertion; } /* Return false if EXPR is a predicate expression involving floating point values. */ static inline bool fp_predicate (gimple stmt) { GIMPLE_CHECK (stmt, GIMPLE_COND); return FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (stmt))); } /* If the range of values taken by OP can be inferred after STMT executes, return the comparison code (COMP_CODE_P) and value (VAL_P) that describes the inferred range. Return true if a range could be inferred. */ static bool infer_value_range (gimple stmt, tree op, enum tree_code *comp_code_p, tree *val_p) { *val_p = NULL_TREE; *comp_code_p = ERROR_MARK; /* Do not attempt to infer anything in names that flow through abnormal edges. */ if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op)) return false; /* Similarly, don't infer anything from statements that may throw exceptions. */ if (stmt_could_throw_p (stmt)) return false; /* If STMT is the last statement of a basic block with no successors, there is no point inferring anything about any of its operands. We would not be able to find a proper insertion point for the assertion, anyway. */ if (stmt_ends_bb_p (stmt) && EDGE_COUNT (gimple_bb (stmt)->succs) == 0) return false; /* We can only assume that a pointer dereference will yield non-NULL if -fdelete-null-pointer-checks is enabled. */ if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op)) && gimple_code (stmt) != GIMPLE_ASM) { unsigned num_uses, num_loads, num_stores; count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores); if (num_loads + num_stores > 0) { *val_p = build_int_cst (TREE_TYPE (op), 0); *comp_code_p = NE_EXPR; return true; } } return false; } void dump_asserts_for (FILE *, tree); void debug_asserts_for (tree); void dump_all_asserts (FILE *); void debug_all_asserts (void); /* Dump all the registered assertions for NAME to FILE. */ void dump_asserts_for (FILE *file, tree name) { assert_locus_t loc; fprintf (file, "Assertions to be inserted for "); print_generic_expr (file, name, 0); fprintf (file, "\n"); loc = asserts_for[SSA_NAME_VERSION (name)]; while (loc) { fprintf (file, "\t"); print_gimple_stmt (file, gsi_stmt (loc->si), 0, 0); fprintf (file, "\n\tBB #%d", loc->bb->index); if (loc->e) { fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index, loc->e->dest->index); dump_edge_info (file, loc->e, 0); } fprintf (file, "\n\tPREDICATE: "); print_generic_expr (file, name, 0); fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]); print_generic_expr (file, loc->val, 0); fprintf (file, "\n\n"); loc = loc->next; } fprintf (file, "\n"); } /* Dump all the registered assertions for NAME to stderr. */ void debug_asserts_for (tree name) { dump_asserts_for (stderr, name); } /* Dump all the registered assertions for all the names to FILE. */ void dump_all_asserts (FILE *file) { unsigned i; bitmap_iterator bi; fprintf (file, "\nASSERT_EXPRs to be inserted\n\n"); EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi) dump_asserts_for (file, ssa_name (i)); fprintf (file, "\n"); } /* Dump all the registered assertions for all the names to stderr. */ void debug_all_asserts (void) { dump_all_asserts (stderr); } /* If NAME doesn't have an ASSERT_EXPR registered for asserting 'EXPR COMP_CODE VAL' at a location that dominates block BB or E->DEST, then register this location as a possible insertion point for ASSERT_EXPR <NAME, EXPR COMP_CODE VAL>. BB, E and SI provide the exact insertion point for the new ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E must not be NULL. */ static void register_new_assert_for (tree name, tree expr, enum tree_code comp_code, tree val, basic_block bb, edge e, gimple_stmt_iterator si) { assert_locus_t n, loc, last_loc; basic_block dest_bb; #if defined ENABLE_CHECKING gcc_assert (bb == NULL || e == NULL); if (e == NULL) gcc_assert (gimple_code (gsi_stmt (si)) != GIMPLE_COND && gimple_code (gsi_stmt (si)) != GIMPLE_SWITCH); #endif /* Never build an assert comparing against an integer constant with TREE_OVERFLOW set. This confuses our undefined overflow warning machinery. */ if (TREE_CODE (val) == INTEGER_CST && TREE_OVERFLOW (val)) val = build_int_cst_wide (TREE_TYPE (val), TREE_INT_CST_LOW (val), TREE_INT_CST_HIGH (val)); /* The new assertion A will be inserted at BB or E. We need to determine if the new location is dominated by a previously registered location for A. If we are doing an edge insertion, assume that A will be inserted at E->DEST. Note that this is not necessarily true. If E is a critical edge, it will be split. But even if E is split, the new block will dominate the same set of blocks that E->DEST dominates. The reverse, however, is not true, blocks dominated by E->DEST will not be dominated by the new block created to split E. So, if the insertion location is on a critical edge, we will not use the new location to move another assertion previously registered at a block dominated by E->DEST. */ dest_bb = (bb) ? bb : e->dest; /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and VAL at a block dominating DEST_BB, then we don't need to insert a new one. Similarly, if the same assertion already exists at a block dominated by DEST_BB and the new location is not on a critical edge, then update the existing location for the assertion (i.e., move the assertion up in the dominance tree). Note, this is implemented as a simple linked list because there should not be more than a handful of assertions registered per name. If this becomes a performance problem, a table hashed by COMP_CODE and VAL could be implemented. */ loc = asserts_for[SSA_NAME_VERSION (name)]; last_loc = loc; while (loc) { if (loc->comp_code == comp_code && (loc->val == val || operand_equal_p (loc->val, val, 0)) && (loc->expr == expr || operand_equal_p (loc->expr, expr, 0))) { /* If the assertion NAME COMP_CODE VAL has already been registered at a basic block that dominates DEST_BB, then we don't need to insert the same assertion again. Note that we don't check strict dominance here to avoid replicating the same assertion inside the same basic block more than once (e.g., when a pointer is dereferenced several times inside a block). An exception to this rule are edge insertions. If the new assertion is to be inserted on edge E, then it will dominate all the other insertions that we may want to insert in DEST_BB. So, if we are doing an edge insertion, don't do this dominance check. */ if (e == NULL && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb)) return; /* Otherwise, if E is not a critical edge and DEST_BB dominates the existing location for the assertion, move the assertion up in the dominance tree by updating its location information. */ if ((e == NULL || !EDGE_CRITICAL_P (e)) && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb)) { loc->bb = dest_bb; loc->e = e; loc->si = si; return; } } /* Update the last node of the list and move to the next one. */ last_loc = loc; loc = loc->next; } /* If we didn't find an assertion already registered for NAME COMP_CODE VAL, add a new one at the end of the list of assertions associated with NAME. */ n = XNEW (struct assert_locus_d); n->bb = dest_bb; n->e = e; n->si = si; n->comp_code = comp_code; n->val = val; n->expr = expr; n->next = NULL; if (last_loc) last_loc->next = n; else asserts_for[SSA_NAME_VERSION (name)] = n; bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name)); } /* (COND_OP0 COND_CODE COND_OP1) is a predicate which uses NAME. Extract a suitable test code and value and store them into *CODE_P and *VAL_P so the predicate is normalized to NAME *CODE_P *VAL_P. If no extraction was possible, return FALSE, otherwise return TRUE. If INVERT is true, then we invert the result stored into *CODE_P. */ static bool extract_code_and_val_from_cond_with_ops (tree name, enum tree_code cond_code, tree cond_op0, tree cond_op1, bool invert, enum tree_code *code_p, tree *val_p) { enum tree_code comp_code; tree val; /* Otherwise, we have a comparison of the form NAME COMP VAL or VAL COMP NAME. */ if (name == cond_op1) { /* If the predicate is of the form VAL COMP NAME, flip COMP around because we need to register NAME as the first operand in the predicate. */ comp_code = swap_tree_comparison (cond_code); val = cond_op0; } else { /* The comparison is of the form NAME COMP VAL, so the comparison code remains unchanged. */ comp_code = cond_code; val = cond_op1; } /* Invert the comparison code as necessary. */ if (invert) comp_code = invert_tree_comparison (comp_code, 0); /* VRP does not handle float types. */ if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (val))) return false; /* Do not register always-false predicates. FIXME: this works around a limitation in fold() when dealing with enumerations. Given 'enum { N1, N2 } x;', fold will not fold 'if (x > N2)' to 'if (0)'. */ if ((comp_code == GT_EXPR || comp_code == LT_EXPR) && INTEGRAL_TYPE_P (TREE_TYPE (val))) { tree min = TYPE_MIN_VALUE (TREE_TYPE (val)); tree max = TYPE_MAX_VALUE (TREE_TYPE (val)); if (comp_code == GT_EXPR && (!max || compare_values (val, max) == 0)) return false; if (comp_code == LT_EXPR && (!min || compare_values (val, min) == 0)) return false; } *code_p = comp_code; *val_p = val; return true; } /* Try to register an edge assertion for SSA name NAME on edge E for the condition COND contributing to the conditional jump pointed to by BSI. Invert the condition COND if INVERT is true. Return true if an assertion for NAME could be registered. */ static bool register_edge_assert_for_2 (tree name, edge e, gimple_stmt_iterator bsi, enum tree_code cond_code, tree cond_op0, tree cond_op1, bool invert) { tree val; enum tree_code comp_code; bool retval = false; if (!extract_code_and_val_from_cond_with_ops (name, cond_code, cond_op0, cond_op1, invert, &comp_code, &val)) return false; /* Only register an ASSERT_EXPR if NAME was found in the sub-graph reachable from E. */ if (live_on_edge (e, name) && !has_single_use (name)) { register_new_assert_for (name, name, comp_code, val, NULL, e, bsi); retval = true; } /* In the case of NAME <= CST and NAME being defined as NAME = (unsigned) NAME2 + CST2 we can assert NAME2 >= -CST2 and NAME2 <= CST - CST2. We can do the same for NAME > CST. This catches range and anti-range tests. */ if ((comp_code == LE_EXPR || comp_code == GT_EXPR) && TREE_CODE (val) == INTEGER_CST && TYPE_UNSIGNED (TREE_TYPE (val))) { gimple def_stmt = SSA_NAME_DEF_STMT (name); tree cst2 = NULL_TREE, name2 = NULL_TREE, name3 = NULL_TREE; /* Extract CST2 from the (optional) addition. */ if (is_gimple_assign (def_stmt) && gimple_assign_rhs_code (def_stmt) == PLUS_EXPR) { name2 = gimple_assign_rhs1 (def_stmt); cst2 = gimple_assign_rhs2 (def_stmt); if (TREE_CODE (name2) == SSA_NAME && TREE_CODE (cst2) == INTEGER_CST) def_stmt = SSA_NAME_DEF_STMT (name2); } /* Extract NAME2 from the (optional) sign-changing cast. */ if (gimple_assign_cast_p (def_stmt)) { if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)) && ! TYPE_UNSIGNED (TREE_TYPE (gimple_assign_rhs1 (def_stmt))) && (TYPE_PRECISION (gimple_expr_type (def_stmt)) == TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs1 (def_stmt))))) name3 = gimple_assign_rhs1 (def_stmt); } /* If name3 is used later, create an ASSERT_EXPR for it. */ if (name3 != NULL_TREE && TREE_CODE (name3) == SSA_NAME && (cst2 == NULL_TREE || TREE_CODE (cst2) == INTEGER_CST) && INTEGRAL_TYPE_P (TREE_TYPE (name3)) && live_on_edge (e, name3) && !has_single_use (name3)) { tree tmp; /* Build an expression for the range test. */ tmp = build1 (NOP_EXPR, TREE_TYPE (name), name3); if (cst2 != NULL_TREE) tmp = build2 (PLUS_EXPR, TREE_TYPE (name), tmp, cst2); if (dump_file) { fprintf (dump_file, "Adding assert for "); print_generic_expr (dump_file, name3, 0); fprintf (dump_file, " from "); print_generic_expr (dump_file, tmp, 0); fprintf (dump_file, "\n"); } register_new_assert_for (name3, tmp, comp_code, val, NULL, e, bsi); retval = true; } /* If name2 is used later, create an ASSERT_EXPR for it. */ if (name2 != NULL_TREE && TREE_CODE (name2) == SSA_NAME && TREE_CODE (cst2) == INTEGER_CST && INTEGRAL_TYPE_P (TREE_TYPE (name2)) && live_on_edge (e, name2) && !has_single_use (name2)) { tree tmp; /* Build an expression for the range test. */ tmp = name2; if (TREE_TYPE (name) != TREE_TYPE (name2)) tmp = build1 (NOP_EXPR, TREE_TYPE (name), tmp); if (cst2 != NULL_TREE) tmp = build2 (PLUS_EXPR, TREE_TYPE (name), tmp, cst2); if (dump_file) { fprintf (dump_file, "Adding assert for "); print_generic_expr (dump_file, name2, 0); fprintf (dump_file, " from "); print_generic_expr (dump_file, tmp, 0); fprintf (dump_file, "\n"); } register_new_assert_for (name2, tmp, comp_code, val, NULL, e, bsi); retval = true; } } return retval; } /* OP is an operand of a truth value expression which is known to have a particular value. Register any asserts for OP and for any operands in OP's defining statement. If CODE is EQ_EXPR, then we want to register OP is zero (false), if CODE is NE_EXPR, then we want to register OP is nonzero (true). */ static bool register_edge_assert_for_1 (tree op, enum tree_code code, edge e, gimple_stmt_iterator bsi) { bool retval = false; gimple op_def; tree val; enum tree_code rhs_code; /* We only care about SSA_NAMEs. */ if (TREE_CODE (op) != SSA_NAME) return false; /* We know that OP will have a zero or nonzero value. If OP is used more than once go ahead and register an assert for OP. The FOUND_IN_SUBGRAPH support is not helpful in this situation as it will always be set for OP (because OP is used in a COND_EXPR in the subgraph). */ if (!has_single_use (op)) { val = build_int_cst (TREE_TYPE (op), 0); register_new_assert_for (op, op, code, val, NULL, e, bsi); retval = true; } /* Now look at how OP is set. If it's set from a comparison, a truth operation or some bit operations, then we may be able to register information about the operands of that assignment. */ op_def = SSA_NAME_DEF_STMT (op); if (gimple_code (op_def) != GIMPLE_ASSIGN) return retval; rhs_code = gimple_assign_rhs_code (op_def); if (TREE_CODE_CLASS (rhs_code) == tcc_comparison) { bool invert = (code == EQ_EXPR ? true : false); tree op0 = gimple_assign_rhs1 (op_def); tree op1 = gimple_assign_rhs2 (op_def); if (TREE_CODE (op0) == SSA_NAME) retval |= register_edge_assert_for_2 (op0, e, bsi, rhs_code, op0, op1, invert); if (TREE_CODE (op1) == SSA_NAME) retval |= register_edge_assert_for_2 (op1, e, bsi, rhs_code, op0, op1, invert); } else if ((code == NE_EXPR && (gimple_assign_rhs_code (op_def) == TRUTH_AND_EXPR || gimple_assign_rhs_code (op_def) == BIT_AND_EXPR)) || (code == EQ_EXPR && (gimple_assign_rhs_code (op_def) == TRUTH_OR_EXPR || gimple_assign_rhs_code (op_def) == BIT_IOR_EXPR))) { /* Recurse on each operand. */ retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), code, e, bsi); retval |= register_edge_assert_for_1 (gimple_assign_rhs2 (op_def), code, e, bsi); } else if (gimple_assign_rhs_code (op_def) == TRUTH_NOT_EXPR) { /* Recurse, flipping CODE. */ code = invert_tree_comparison (code, false); retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), code, e, bsi); } else if (gimple_assign_rhs_code (op_def) == SSA_NAME) { /* Recurse through the copy. */ retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), code, e, bsi); } else if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (op_def))) { /* Recurse through the type conversion. */ retval |= register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), code, e, bsi); } return retval; } /* Try to register an edge assertion for SSA name NAME on edge E for the condition COND contributing to the conditional jump pointed to by SI. Return true if an assertion for NAME could be registered. */ static bool register_edge_assert_for (tree name, edge e, gimple_stmt_iterator si, enum tree_code cond_code, tree cond_op0, tree cond_op1) { tree val; enum tree_code comp_code; bool retval = false; bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0; /* Do not attempt to infer anything in names that flow through abnormal edges. */ if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name)) return false; if (!extract_code_and_val_from_cond_with_ops (name, cond_code, cond_op0, cond_op1, is_else_edge, &comp_code, &val)) return false; /* Register ASSERT_EXPRs for name. */ retval |= register_edge_assert_for_2 (name, e, si, cond_code, cond_op0, cond_op1, is_else_edge); /* If COND is effectively an equality test of an SSA_NAME against the value zero or one, then we may be able to assert values for SSA_NAMEs which flow into COND. */ /* In the case of NAME == 1 or NAME != 0, for TRUTH_AND_EXPR defining statement of NAME we can assert both operands of the TRUTH_AND_EXPR have nonzero value. */ if (((comp_code == EQ_EXPR && integer_onep (val)) || (comp_code == NE_EXPR && integer_zerop (val)))) { gimple def_stmt = SSA_NAME_DEF_STMT (name); if (is_gimple_assign (def_stmt) && (gimple_assign_rhs_code (def_stmt) == TRUTH_AND_EXPR || gimple_assign_rhs_code (def_stmt) == BIT_AND_EXPR)) { tree op0 = gimple_assign_rhs1 (def_stmt); tree op1 = gimple_assign_rhs2 (def_stmt); retval |= register_edge_assert_for_1 (op0, NE_EXPR, e, si); retval |= register_edge_assert_for_1 (op1, NE_EXPR, e, si); } } /* In the case of NAME == 0 or NAME != 1, for TRUTH_OR_EXPR defining statement of NAME we can assert both operands of the TRUTH_OR_EXPR have zero value. */ if (((comp_code == EQ_EXPR && integer_zerop (val)) || (comp_code == NE_EXPR && integer_onep (val)))) { gimple def_stmt = SSA_NAME_DEF_STMT (name); if (is_gimple_assign (def_stmt) && (gimple_assign_rhs_code (def_stmt) == TRUTH_OR_EXPR /* For BIT_IOR_EXPR only if NAME == 0 both operands have necessarily zero value. */ || (comp_code == EQ_EXPR && (gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR)))) { tree op0 = gimple_assign_rhs1 (def_stmt); tree op1 = gimple_assign_rhs2 (def_stmt); retval |= register_edge_assert_for_1 (op0, EQ_EXPR, e, si); retval |= register_edge_assert_for_1 (op1, EQ_EXPR, e, si); } } return retval; } /* Determine whether the outgoing edges of BB should receive an ASSERT_EXPR for each of the operands of BB's LAST statement. The last statement of BB must be a COND_EXPR. If any of the sub-graphs rooted at BB have an interesting use of the predicate operands, an assert location node is added to the list of assertions for the corresponding operands. */ static bool find_conditional_asserts (basic_block bb, gimple last) { bool need_assert; gimple_stmt_iterator bsi; tree op; edge_iterator ei; edge e; ssa_op_iter iter; need_assert = false; bsi = gsi_for_stmt (last); /* Look for uses of the operands in each of the sub-graphs rooted at BB. We need to check each of the outgoing edges separately, so that we know what kind of ASSERT_EXPR to insert. */ FOR_EACH_EDGE (e, ei, bb->succs) { if (e->dest == bb) continue; /* Register the necessary assertions for each operand in the conditional predicate. */ FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE) { need_assert |= register_edge_assert_for (op, e, bsi, gimple_cond_code (last), gimple_cond_lhs (last), gimple_cond_rhs (last)); } } return need_assert; } /* Compare two case labels sorting first by the destination label uid and then by the case value. */ static int compare_case_labels (const void *p1, const void *p2) { const_tree const case1 = *(const_tree const*)p1; const_tree const case2 = *(const_tree const*)p2; unsigned int uid1 = DECL_UID (CASE_LABEL (case1)); unsigned int uid2 = DECL_UID (CASE_LABEL (case2)); if (uid1 < uid2) return -1; else if (uid1 == uid2) { /* Make sure the default label is first in a group. */ if (!CASE_LOW (case1)) return -1; else if (!CASE_LOW (case2)) return 1; else return tree_int_cst_compare (CASE_LOW (case1), CASE_LOW (case2)); } else return 1; } /* Determine whether the outgoing edges of BB should receive an ASSERT_EXPR for each of the operands of BB's LAST statement. The last statement of BB must be a SWITCH_EXPR. If any of the sub-graphs rooted at BB have an interesting use of the predicate operands, an assert location node is added to the list of assertions for the corresponding operands. */ static bool find_switch_asserts (basic_block bb, gimple last) { bool need_assert; gimple_stmt_iterator bsi; tree op; edge e; tree vec2; size_t n = gimple_switch_num_labels(last); #if GCC_VERSION >= 4000 unsigned int idx; #else /* Work around GCC 3.4 bug (PR 37086). */ volatile unsigned int idx; #endif need_assert = false; bsi = gsi_for_stmt (last); op = gimple_switch_index (last); if (TREE_CODE (op) != SSA_NAME) return false; /* Build a vector of case labels sorted by destination label. */ vec2 = make_tree_vec (n); for (idx = 0; idx < n; ++idx) TREE_VEC_ELT (vec2, idx) = gimple_switch_label (last, idx); qsort (&TREE_VEC_ELT (vec2, 0), n, sizeof (tree), compare_case_labels); for (idx = 0; idx < n; ++idx) { tree min, max; tree cl = TREE_VEC_ELT (vec2, idx); min = CASE_LOW (cl); max = CASE_HIGH (cl); /* If there are multiple case labels with the same destination we need to combine them to a single value range for the edge. */ if (idx + 1 < n && CASE_LABEL (cl) == CASE_LABEL (TREE_VEC_ELT (vec2, idx + 1))) { /* Skip labels until the last of the group. */ do { ++idx; } while (idx < n && CASE_LABEL (cl) == CASE_LABEL (TREE_VEC_ELT (vec2, idx))); --idx; /* Pick up the maximum of the case label range. */ if (CASE_HIGH (TREE_VEC_ELT (vec2, idx))) max = CASE_HIGH (TREE_VEC_ELT (vec2, idx)); else max = CASE_LOW (TREE_VEC_ELT (vec2, idx)); } /* Nothing to do if the range includes the default label until we can register anti-ranges. */ if (min == NULL_TREE) continue; /* Find the edge to register the assert expr on. */ e = find_edge (bb, label_to_block (CASE_LABEL (cl))); /* Register the necessary assertions for the operand in the SWITCH_EXPR. */ need_assert |= register_edge_assert_for (op, e, bsi, max ? GE_EXPR : EQ_EXPR, op, fold_convert (TREE_TYPE (op), min)); if (max) { need_assert |= register_edge_assert_for (op, e, bsi, LE_EXPR, op, fold_convert (TREE_TYPE (op), max)); } } return need_assert; } /* Traverse all the statements in block BB looking for statements that may generate useful assertions for the SSA names in their operand. If a statement produces a useful assertion A for name N_i, then the list of assertions already generated for N_i is scanned to determine if A is actually needed. If N_i already had the assertion A at a location dominating the current location, then nothing needs to be done. Otherwise, the new location for A is recorded instead. 1- For every statement S in BB, all the variables used by S are added to bitmap FOUND_IN_SUBGRAPH. 2- If statement S uses an operand N in a way that exposes a known value range for N, then if N was not already generated by an ASSERT_EXPR, create a new assert location for N. For instance, if N is a pointer and the statement dereferences it, we can assume that N is not NULL. 3- COND_EXPRs are a special case of #2. We can derive range information from the predicate but need to insert different ASSERT_EXPRs for each of the sub-graphs rooted at the conditional block. If the last statement of BB is a conditional expression of the form 'X op Y', then a) Remove X and Y from the set FOUND_IN_SUBGRAPH. b) If the conditional is the only entry point to the sub-graph corresponding to the THEN_CLAUSE, recurse into it. On return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then an ASSERT_EXPR is added for the corresponding variable. c) Repeat step (b) on the ELSE_CLAUSE. d) Mark X and Y in FOUND_IN_SUBGRAPH. For instance, if (a == 9) b = a; else b = c + 1; In this case, an assertion on the THEN clause is useful to determine that 'a' is always 9 on that edge. However, an assertion on the ELSE clause would be unnecessary. 4- If BB does not end in a conditional expression, then we recurse into BB's dominator children. At the end of the recursive traversal, every SSA name will have a list of locations where ASSERT_EXPRs should be added. When a new location for name N is found, it is registered by calling register_new_assert_for. That function keeps track of all the registered assertions to prevent adding unnecessary assertions. For instance, if a pointer P_4 is dereferenced more than once in a dominator tree, only the location dominating all the dereference of P_4 will receive an ASSERT_EXPR. If this function returns true, then it means that there are names for which we need to generate ASSERT_EXPRs. Those assertions are inserted by process_assert_insertions. */ static bool find_assert_locations_1 (basic_block bb, sbitmap live) { gimple_stmt_iterator si; gimple last; gimple phi; bool need_assert; need_assert = false; last = last_stmt (bb); /* If BB's last statement is a conditional statement involving integer operands, determine if we need to add ASSERT_EXPRs. */ if (last && gimple_code (last) == GIMPLE_COND && !fp_predicate (last) && !ZERO_SSA_OPERANDS (last, SSA_OP_USE)) need_assert |= find_conditional_asserts (bb, last); /* If BB's last statement is a switch statement involving integer operands, determine if we need to add ASSERT_EXPRs. */ if (last && gimple_code (last) == GIMPLE_SWITCH && !ZERO_SSA_OPERANDS (last, SSA_OP_USE)) need_assert |= find_switch_asserts (bb, last); /* Traverse all the statements in BB marking used names and looking for statements that may infer assertions for their used operands. */ for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si)) { gimple stmt; tree op; ssa_op_iter i; stmt = gsi_stmt (si); if (is_gimple_debug (stmt)) continue; /* See if we can derive an assertion for any of STMT's operands. */ FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE) { tree value; enum tree_code comp_code; /* Mark OP in our live bitmap. */ SET_BIT (live, SSA_NAME_VERSION (op)); /* If OP is used in such a way that we can infer a value range for it, and we don't find a previous assertion for it, create a new assertion location node for OP. */ if (infer_value_range (stmt, op, &comp_code, &value)) { /* If we are able to infer a nonzero value range for OP, then walk backwards through the use-def chain to see if OP was set via a typecast. If so, then we can also infer a nonzero value range for the operand of the NOP_EXPR. */ if (comp_code == NE_EXPR && integer_zerop (value)) { tree t = op; gimple def_stmt = SSA_NAME_DEF_STMT (t); while (is_gimple_assign (def_stmt) && gimple_assign_rhs_code (def_stmt) == NOP_EXPR && TREE_CODE (gimple_assign_rhs1 (def_stmt)) == SSA_NAME && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (def_stmt)))) { t = gimple_assign_rhs1 (def_stmt); def_stmt = SSA_NAME_DEF_STMT (t); /* Note we want to register the assert for the operand of the NOP_EXPR after SI, not after the conversion. */ if (! has_single_use (t)) { register_new_assert_for (t, t, comp_code, value, bb, NULL, si); need_assert = true; } } } /* If OP is used only once, namely in this STMT, don't bother creating an ASSERT_EXPR for it. Such an ASSERT_EXPR would do nothing but increase compile time. */ if (!has_single_use (op)) { register_new_assert_for (op, op, comp_code, value, bb, NULL, si); need_assert = true; } } } } /* Traverse all PHI nodes in BB marking used operands. */ for (si = gsi_start_phis (bb); !gsi_end_p(si); gsi_next (&si)) { use_operand_p arg_p; ssa_op_iter i; phi = gsi_stmt (si); FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE) { tree arg = USE_FROM_PTR (arg_p); if (TREE_CODE (arg) == SSA_NAME) SET_BIT (live, SSA_NAME_VERSION (arg)); } } return need_assert; } /* Do an RPO walk over the function computing SSA name liveness on-the-fly and deciding on assert expressions to insert. Returns true if there are assert expressions to be inserted. */ static bool find_assert_locations (void) { int *rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS); int *bb_rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS); int *last_rpo = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS); int rpo_cnt, i; bool need_asserts; live = XCNEWVEC (sbitmap, last_basic_block + NUM_FIXED_BLOCKS); rpo_cnt = pre_and_rev_post_order_compute (NULL, rpo, false); for (i = 0; i < rpo_cnt; ++i) bb_rpo[rpo[i]] = i; need_asserts = false; for (i = rpo_cnt-1; i >= 0; --i) { basic_block bb = BASIC_BLOCK (rpo[i]); edge e; edge_iterator ei; if (!live[rpo[i]]) { live[rpo[i]] = sbitmap_alloc (num_ssa_names); sbitmap_zero (live[rpo[i]]); } /* Process BB and update the live information with uses in this block. */ need_asserts |= find_assert_locations_1 (bb, live[rpo[i]]); /* Merge liveness into the predecessor blocks and free it. */ if (!sbitmap_empty_p (live[rpo[i]])) { int pred_rpo = i; FOR_EACH_EDGE (e, ei, bb->preds) { int pred = e->src->index; if (e->flags & EDGE_DFS_BACK) continue; if (!live[pred]) { live[pred] = sbitmap_alloc (num_ssa_names); sbitmap_zero (live[pred]); } sbitmap_a_or_b (live[pred], live[pred], live[rpo[i]]); if (bb_rpo[pred] < pred_rpo) pred_rpo = bb_rpo[pred]; } /* Record the RPO number of the last visited block that needs live information from this block. */ last_rpo[rpo[i]] = pred_rpo; } else { sbitmap_free (live[rpo[i]]); live[rpo[i]] = NULL; } /* We can free all successors live bitmaps if all their predecessors have been visited already. */ FOR_EACH_EDGE (e, ei, bb->succs) if (last_rpo[e->dest->index] == i && live[e->dest->index]) { sbitmap_free (live[e->dest->index]); live[e->dest->index] = NULL; } } XDELETEVEC (rpo); XDELETEVEC (bb_rpo); XDELETEVEC (last_rpo); for (i = 0; i < last_basic_block + NUM_FIXED_BLOCKS; ++i) if (live[i]) sbitmap_free (live[i]); XDELETEVEC (live); return need_asserts; } /* Create an ASSERT_EXPR for NAME and insert it in the location indicated by LOC. Return true if we made any edge insertions. */ static bool process_assert_insertions_for (tree name, assert_locus_t loc) { /* Build the comparison expression NAME_i COMP_CODE VAL. */ gimple stmt; tree cond; gimple assert_stmt; edge_iterator ei; edge e; /* If we have X <=> X do not insert an assert expr for that. */ if (loc->expr == loc->val) return false; cond = build2 (loc->comp_code, boolean_type_node, loc->expr, loc->val); assert_stmt = build_assert_expr_for (cond, name); if (loc->e) { /* We have been asked to insert the assertion on an edge. This is used only by COND_EXPR and SWITCH_EXPR assertions. */ #if defined ENABLE_CHECKING gcc_assert (gimple_code (gsi_stmt (loc->si)) == GIMPLE_COND || gimple_code (gsi_stmt (loc->si)) == GIMPLE_SWITCH); #endif gsi_insert_on_edge (loc->e, assert_stmt); return true; } /* Otherwise, we can insert right after LOC->SI iff the statement must not be the last statement in the block. */ stmt = gsi_stmt (loc->si); if (!stmt_ends_bb_p (stmt)) { gsi_insert_after (&loc->si, assert_stmt, GSI_SAME_STMT); return false; } /* If STMT must be the last statement in BB, we can only insert new assertions on the non-abnormal edge out of BB. Note that since STMT is not control flow, there may only be one non-abnormal edge out of BB. */ FOR_EACH_EDGE (e, ei, loc->bb->succs) if (!(e->flags & EDGE_ABNORMAL)) { gsi_insert_on_edge (e, assert_stmt); return true; } gcc_unreachable (); } /* Process all the insertions registered for every name N_i registered in NEED_ASSERT_FOR. The list of assertions to be inserted are found in ASSERTS_FOR[i]. */ static void process_assert_insertions (void) { unsigned i; bitmap_iterator bi; bool update_edges_p = false; int num_asserts = 0; if (dump_file && (dump_flags & TDF_DETAILS)) dump_all_asserts (dump_file); EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi) { assert_locus_t loc = asserts_for[i]; gcc_assert (loc); while (loc) { assert_locus_t next = loc->next; update_edges_p |= process_assert_insertions_for (ssa_name (i), loc); free (loc); loc = next; num_asserts++; } } if (update_edges_p) gsi_commit_edge_inserts (); statistics_counter_event (cfun, "Number of ASSERT_EXPR expressions inserted", num_asserts); } /* Traverse the flowgraph looking for conditional jumps to insert range expressions. These range expressions are meant to provide information to optimizations that need to reason in terms of value ranges. They will not be expanded into RTL. For instance, given: x = ... y = ... if (x < y) y = x - 2; else x = y + 3; this pass will transform the code into: x = ... y = ... if (x < y) { x = ASSERT_EXPR <x, x < y> y = x - 2 } else { y = ASSERT_EXPR <y, x <= y> x = y + 3 } The idea is that once copy and constant propagation have run, other optimizations will be able to determine what ranges of values can 'x' take in different paths of the code, simply by checking the reaching definition of 'x'. */ static void insert_range_assertions (void) { need_assert_for = BITMAP_ALLOC (NULL); asserts_for = XCNEWVEC (assert_locus_t, num_ssa_names); calculate_dominance_info (CDI_DOMINATORS); if (find_assert_locations ()) { process_assert_insertions (); update_ssa (TODO_update_ssa_no_phi); } if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n"); dump_function_to_file (current_function_decl, dump_file, dump_flags); } free (asserts_for); BITMAP_FREE (need_assert_for); } /* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays and "struct" hacks. If VRP can determine that the array subscript is a constant, check if it is outside valid range. If the array subscript is a RANGE, warn if it is non-overlapping with valid range. IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR. */ static void check_array_ref (location_t location, tree ref, bool ignore_off_by_one) { value_range_t* vr = NULL; tree low_sub, up_sub; tree low_bound, up_bound = array_ref_up_bound (ref); low_sub = up_sub = TREE_OPERAND (ref, 1); if (!up_bound || TREE_NO_WARNING (ref) || TREE_CODE (up_bound) != INTEGER_CST /* Can not check flexible arrays. */ || (TYPE_SIZE (TREE_TYPE (ref)) == NULL_TREE && TYPE_DOMAIN (TREE_TYPE (ref)) != NULL_TREE && TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (ref))) == NULL_TREE) /* Accesses after the end of arrays of size 0 (gcc extension) and 1 are likely intentional ("struct hack"). */ || compare_tree_int (up_bound, 1) <= 0) return; low_bound = array_ref_low_bound (ref); if (TREE_CODE (low_sub) == SSA_NAME) { vr = get_value_range (low_sub); if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE) { low_sub = vr->type == VR_RANGE ? vr->max : vr->min; up_sub = vr->type == VR_RANGE ? vr->min : vr->max; } } if (vr && vr->type == VR_ANTI_RANGE) { if (TREE_CODE (up_sub) == INTEGER_CST && tree_int_cst_lt (up_bound, up_sub) && TREE_CODE (low_sub) == INTEGER_CST && tree_int_cst_lt (low_sub, low_bound)) { warning_at (location, OPT_Warray_bounds, "array subscript is outside array bounds"); TREE_NO_WARNING (ref) = 1; } } else if (TREE_CODE (up_sub) == INTEGER_CST && tree_int_cst_lt (up_bound, up_sub) && !tree_int_cst_equal (up_bound, up_sub) && (!ignore_off_by_one || !tree_int_cst_equal (int_const_binop (PLUS_EXPR, up_bound, integer_one_node, 0), up_sub))) { warning_at (location, OPT_Warray_bounds, "array subscript is above array bounds"); TREE_NO_WARNING (ref) = 1; } else if (TREE_CODE (low_sub) == INTEGER_CST && tree_int_cst_lt (low_sub, low_bound)) { warning_at (location, OPT_Warray_bounds, "array subscript is below array bounds"); TREE_NO_WARNING (ref) = 1; } } /* Searches if the expr T, located at LOCATION computes address of an ARRAY_REF, and call check_array_ref on it. */ static void search_for_addr_array (tree t, location_t location) { while (TREE_CODE (t) == SSA_NAME) { gimple g = SSA_NAME_DEF_STMT (t); if (gimple_code (g) != GIMPLE_ASSIGN) return; if (get_gimple_rhs_class (gimple_assign_rhs_code (g)) != GIMPLE_SINGLE_RHS) return; t = gimple_assign_rhs1 (g); } /* We are only interested in addresses of ARRAY_REF's. */ if (TREE_CODE (t) != ADDR_EXPR) return; /* Check each ARRAY_REFs in the reference chain. */ do { if (TREE_CODE (t) == ARRAY_REF) check_array_ref (location, t, true /*ignore_off_by_one*/); t = TREE_OPERAND (t, 0); } while (handled_component_p (t)); } /* walk_tree() callback that checks if *TP is an ARRAY_REF inside an ADDR_EXPR (in which an array subscript one outside the valid range is allowed). Call check_array_ref for each ARRAY_REF found. The location is passed in DATA. */ static tree check_array_bounds (tree *tp, int *walk_subtree, void *data) { tree t = *tp; struct walk_stmt_info *wi = (struct walk_stmt_info *) data; location_t location; if (EXPR_HAS_LOCATION (t)) location = EXPR_LOCATION (t); else { location_t *locp = (location_t *) wi->info; location = *locp; } *walk_subtree = TRUE; if (TREE_CODE (t) == ARRAY_REF) check_array_ref (location, t, false /*ignore_off_by_one*/); if (TREE_CODE (t) == INDIRECT_REF || (TREE_CODE (t) == RETURN_EXPR && TREE_OPERAND (t, 0))) search_for_addr_array (TREE_OPERAND (t, 0), location); if (TREE_CODE (t) == ADDR_EXPR) *walk_subtree = FALSE; return NULL_TREE; } /* Walk over all statements of all reachable BBs and call check_array_bounds on them. */ static void check_all_array_refs (void) { basic_block bb; gimple_stmt_iterator si; FOR_EACH_BB (bb) { edge_iterator ei; edge e; bool executable = false; /* Skip blocks that were found to be unreachable. */ FOR_EACH_EDGE (e, ei, bb->preds) executable |= !!(e->flags & EDGE_EXECUTABLE); if (!executable) continue; for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si)) { gimple stmt = gsi_stmt (si); struct walk_stmt_info wi; if (!gimple_has_location (stmt)) continue; if (is_gimple_call (stmt)) { size_t i; size_t n = gimple_call_num_args (stmt); for (i = 0; i < n; i++) { tree arg = gimple_call_arg (stmt, i); search_for_addr_array (arg, gimple_location (stmt)); } } else { memset (&wi, 0, sizeof (wi)); wi.info = CONST_CAST (void *, (const void *) gimple_location_ptr (stmt)); walk_gimple_op (gsi_stmt (si), check_array_bounds, &wi); } } } } /* Convert range assertion expressions into the implied copies and copy propagate away the copies. Doing the trivial copy propagation here avoids the need to run the full copy propagation pass after VRP. FIXME, this will eventually lead to copy propagation removing the names that had useful range information attached to them. For instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>, then N_i will have the range [3, +INF]. However, by converting the assertion into the implied copy operation N_i = N_j, we will then copy-propagate N_j into the uses of N_i and lose the range information. We may want to hold on to ASSERT_EXPRs a little while longer as the ranges could be used in things like jump threading. The problem with keeping ASSERT_EXPRs around is that passes after VRP need to handle them appropriately. Another approach would be to make the range information a first class property of the SSA_NAME so that it can be queried from any pass. This is made somewhat more complex by the need for multiple ranges to be associated with one SSA_NAME. */ static void remove_range_assertions (void) { basic_block bb; gimple_stmt_iterator si; /* Note that the BSI iterator bump happens at the bottom of the loop and no bump is necessary if we're removing the statement referenced by the current BSI. */ FOR_EACH_BB (bb) for (si = gsi_start_bb (bb); !gsi_end_p (si);) { gimple stmt = gsi_stmt (si); gimple use_stmt; if (is_gimple_assign (stmt) && gimple_assign_rhs_code (stmt) == ASSERT_EXPR) { tree rhs = gimple_assign_rhs1 (stmt); tree var; tree cond = fold (ASSERT_EXPR_COND (rhs)); use_operand_p use_p; imm_use_iterator iter; gcc_assert (cond != boolean_false_node); /* Propagate the RHS into every use of the LHS. */ var = ASSERT_EXPR_VAR (rhs); FOR_EACH_IMM_USE_STMT (use_stmt, iter, gimple_assign_lhs (stmt)) FOR_EACH_IMM_USE_ON_STMT (use_p, iter) { SET_USE (use_p, var); gcc_assert (TREE_CODE (var) == SSA_NAME); } /* And finally, remove the copy, it is not needed. */ gsi_remove (&si, true); release_defs (stmt); } else gsi_next (&si); } } /* Return true if STMT is interesting for VRP. */ static bool stmt_interesting_for_vrp (gimple stmt) { if (gimple_code (stmt) == GIMPLE_PHI && is_gimple_reg (gimple_phi_result (stmt)) && (INTEGRAL_TYPE_P (TREE_TYPE (gimple_phi_result (stmt))) || POINTER_TYPE_P (TREE_TYPE (gimple_phi_result (stmt))))) return true; else if (is_gimple_assign (stmt) || is_gimple_call (stmt)) { tree lhs = gimple_get_lhs (stmt); /* In general, assignments with virtual operands are not useful for deriving ranges, with the obvious exception of calls to builtin functions. */ if (lhs && TREE_CODE (lhs) == SSA_NAME && (INTEGRAL_TYPE_P (TREE_TYPE (lhs)) || POINTER_TYPE_P (TREE_TYPE (lhs))) && ((is_gimple_call (stmt) && gimple_call_fndecl (stmt) != NULL_TREE && DECL_IS_BUILTIN (gimple_call_fndecl (stmt))) || !gimple_vuse (stmt))) return true; } else if (gimple_code (stmt) == GIMPLE_COND || gimple_code (stmt) == GIMPLE_SWITCH) return true; return false; } /* Initialize local data structures for VRP. */ static void vrp_initialize (void) { basic_block bb; vr_value = XCNEWVEC (value_range_t *, num_ssa_names); vr_phi_edge_counts = XCNEWVEC (int, num_ssa_names); FOR_EACH_BB (bb) { gimple_stmt_iterator si; for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si)) { gimple phi = gsi_stmt (si); if (!stmt_interesting_for_vrp (phi)) { tree lhs = PHI_RESULT (phi); set_value_range_to_varying (get_value_range (lhs)); prop_set_simulate_again (phi, false); } else prop_set_simulate_again (phi, true); } for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si)) { gimple stmt = gsi_stmt (si); /* If the statement is a control insn, then we do not want to avoid simulating the statement once. Failure to do so means that those edges will never get added. */ if (stmt_ends_bb_p (stmt)) prop_set_simulate_again (stmt, true); else if (!stmt_interesting_for_vrp (stmt)) { ssa_op_iter i; tree def; FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF) set_value_range_to_varying (get_value_range (def)); prop_set_simulate_again (stmt, false); } else prop_set_simulate_again (stmt, true); } } } /* Visit assignment STMT. If it produces an interesting range, record the SSA name in *OUTPUT_P. */ static enum ssa_prop_result vrp_visit_assignment_or_call (gimple stmt, tree *output_p) { tree def, lhs; ssa_op_iter iter; enum gimple_code code = gimple_code (stmt); lhs = gimple_get_lhs (stmt); /* We only keep track of ranges in integral and pointer types. */ if (TREE_CODE (lhs) == SSA_NAME && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs)) /* It is valid to have NULL MIN/MAX values on a type. See build_range_type. */ && TYPE_MIN_VALUE (TREE_TYPE (lhs)) && TYPE_MAX_VALUE (TREE_TYPE (lhs))) || POINTER_TYPE_P (TREE_TYPE (lhs)))) { value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; if (code == GIMPLE_CALL) extract_range_basic (&new_vr, stmt); else extract_range_from_assignment (&new_vr, stmt); if (update_value_range (lhs, &new_vr)) { *output_p = lhs; if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Found new range for "); print_generic_expr (dump_file, lhs, 0); fprintf (dump_file, ": "); dump_value_range (dump_file, &new_vr); fprintf (dump_file, "\n\n"); } if (new_vr.type == VR_VARYING) return SSA_PROP_VARYING; return SSA_PROP_INTERESTING; } return SSA_PROP_NOT_INTERESTING; } /* Every other statement produces no useful ranges. */ FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) set_value_range_to_varying (get_value_range (def)); return SSA_PROP_VARYING; } /* Helper that gets the value range of the SSA_NAME with version I or a symbolic range containing the SSA_NAME only if the value range is varying or undefined. */ static inline value_range_t get_vr_for_comparison (int i) { value_range_t vr = *(vr_value[i]); /* If name N_i does not have a valid range, use N_i as its own range. This allows us to compare against names that may have N_i in their ranges. */ if (vr.type == VR_VARYING || vr.type == VR_UNDEFINED) { vr.type = VR_RANGE; vr.min = ssa_name (i); vr.max = ssa_name (i); } return vr; } /* Compare all the value ranges for names equivalent to VAR with VAL using comparison code COMP. Return the same value returned by compare_range_with_value, including the setting of *STRICT_OVERFLOW_P. */ static tree compare_name_with_value (enum tree_code comp, tree var, tree val, bool *strict_overflow_p) { bitmap_iterator bi; unsigned i; bitmap e; tree retval, t; int used_strict_overflow; bool sop; value_range_t equiv_vr; /* Get the set of equivalences for VAR. */ e = get_value_range (var)->equiv; /* Start at -1. Set it to 0 if we do a comparison without relying on overflow, or 1 if all comparisons rely on overflow. */ used_strict_overflow = -1; /* Compare vars' value range with val. */ equiv_vr = get_vr_for_comparison (SSA_NAME_VERSION (var)); sop = false; retval = compare_range_with_value (comp, &equiv_vr, val, &sop); if (retval) used_strict_overflow = sop ? 1 : 0; /* If the equiv set is empty we have done all work we need to do. */ if (e == NULL) { if (retval && used_strict_overflow > 0) *strict_overflow_p = true; return retval; } EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi) { equiv_vr = get_vr_for_comparison (i); sop = false; t = compare_range_with_value (comp, &equiv_vr, val, &sop); if (t) { /* If we get different answers from different members of the equivalence set this check must be in a dead code region. Folding it to a trap representation would be correct here. For now just return don't-know. */ if (retval != NULL && t != retval) { retval = NULL_TREE; break; } retval = t; if (!sop) used_strict_overflow = 0; else if (used_strict_overflow < 0) used_strict_overflow = 1; } } if (retval && used_strict_overflow > 0) *strict_overflow_p = true; return retval; } /* Given a comparison code COMP and names N1 and N2, compare all the ranges equivalent to N1 against all the ranges equivalent to N2 to determine the value of N1 COMP N2. Return the same value returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow infinity in the comparison. */ static tree compare_names (enum tree_code comp, tree n1, tree n2, bool *strict_overflow_p) { tree t, retval; bitmap e1, e2; bitmap_iterator bi1, bi2; unsigned i1, i2; int used_strict_overflow; static bitmap_obstack *s_obstack = NULL; static bitmap s_e1 = NULL, s_e2 = NULL; /* Compare the ranges of every name equivalent to N1 against the ranges of every name equivalent to N2. */ e1 = get_value_range (n1)->equiv; e2 = get_value_range (n2)->equiv; /* Use the fake bitmaps if e1 or e2 are not available. */ if (s_obstack == NULL) { s_obstack = XNEW (bitmap_obstack); bitmap_obstack_initialize (s_obstack); s_e1 = BITMAP_ALLOC (s_obstack); s_e2 = BITMAP_ALLOC (s_obstack); } if (e1 == NULL) e1 = s_e1; if (e2 == NULL) e2 = s_e2; /* Add N1 and N2 to their own set of equivalences to avoid duplicating the body of the loop just to check N1 and N2 ranges. */ bitmap_set_bit (e1, SSA_NAME_VERSION (n1)); bitmap_set_bit (e2, SSA_NAME_VERSION (n2)); /* If the equivalence sets have a common intersection, then the two names can be compared without checking their ranges. */ if (bitmap_intersect_p (e1, e2)) { bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR) ? boolean_true_node : boolean_false_node; } /* Start at -1. Set it to 0 if we do a comparison without relying on overflow, or 1 if all comparisons rely on overflow. */ used_strict_overflow = -1; /* Otherwise, compare all the equivalent ranges. First, add N1 and N2 to their own set of equivalences to avoid duplicating the body of the loop just to check N1 and N2 ranges. */ EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1) { value_range_t vr1 = get_vr_for_comparison (i1); t = retval = NULL_TREE; EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2) { bool sop = false; value_range_t vr2 = get_vr_for_comparison (i2); t = compare_ranges (comp, &vr1, &vr2, &sop); if (t) { /* If we get different answers from different members of the equivalence set this check must be in a dead code region. Folding it to a trap representation would be correct here. For now just return don't-know. */ if (retval != NULL && t != retval) { bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); return NULL_TREE; } retval = t; if (!sop) used_strict_overflow = 0; else if (used_strict_overflow < 0) used_strict_overflow = 1; } } if (retval) { bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); if (used_strict_overflow > 0) *strict_overflow_p = true; return retval; } } /* None of the equivalent ranges are useful in computing this comparison. */ bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); return NULL_TREE; } /* Helper function for vrp_evaluate_conditional_warnv. */ static tree vrp_evaluate_conditional_warnv_with_ops_using_ranges (enum tree_code code, tree op0, tree op1, bool * strict_overflow_p) { value_range_t *vr0, *vr1; vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL; vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL; if (vr0 && vr1) return compare_ranges (code, vr0, vr1, strict_overflow_p); else if (vr0 && vr1 == NULL) return compare_range_with_value (code, vr0, op1, strict_overflow_p); else if (vr0 == NULL && vr1) return (compare_range_with_value (swap_tree_comparison (code), vr1, op0, strict_overflow_p)); return NULL; } /* Helper function for vrp_evaluate_conditional_warnv. */ static tree vrp_evaluate_conditional_warnv_with_ops (enum tree_code code, tree op0, tree op1, bool use_equiv_p, bool *strict_overflow_p, bool *only_ranges) { tree ret; if (only_ranges) *only_ranges = true; /* We only deal with integral and pointer types. */ if (!INTEGRAL_TYPE_P (TREE_TYPE (op0)) && !POINTER_TYPE_P (TREE_TYPE (op0))) return NULL_TREE; if (use_equiv_p) { if (only_ranges && (ret = vrp_evaluate_conditional_warnv_with_ops_using_ranges (code, op0, op1, strict_overflow_p))) return ret; *only_ranges = false; if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME) return compare_names (code, op0, op1, strict_overflow_p); else if (TREE_CODE (op0) == SSA_NAME) return compare_name_with_value (code, op0, op1, strict_overflow_p); else if (TREE_CODE (op1) == SSA_NAME) return (compare_name_with_value (swap_tree_comparison (code), op1, op0, strict_overflow_p)); } else return vrp_evaluate_conditional_warnv_with_ops_using_ranges (code, op0, op1, strict_overflow_p); return NULL_TREE; } /* Given (CODE OP0 OP1) within STMT, try to simplify it based on value range information. Return NULL if the conditional can not be evaluated. The ranges of all the names equivalent with the operands in COND will be used when trying to compute the value. If the result is based on undefined signed overflow, issue a warning if appropriate. */ static tree vrp_evaluate_conditional (enum tree_code code, tree op0, tree op1, gimple stmt) { bool sop; tree ret; bool only_ranges; /* Some passes and foldings leak constants with overflow flag set into the IL. Avoid doing wrong things with these and bail out. */ if ((TREE_CODE (op0) == INTEGER_CST && TREE_OVERFLOW (op0)) || (TREE_CODE (op1) == INTEGER_CST && TREE_OVERFLOW (op1))) return NULL_TREE; sop = false; ret = vrp_evaluate_conditional_warnv_with_ops (code, op0, op1, true, &sop, &only_ranges); if (ret && sop) { enum warn_strict_overflow_code wc; const char* warnmsg; if (is_gimple_min_invariant (ret)) { wc = WARN_STRICT_OVERFLOW_CONDITIONAL; warnmsg = G_("assuming signed overflow does not occur when " "simplifying conditional to constant"); } else { wc = WARN_STRICT_OVERFLOW_COMPARISON; warnmsg = G_("assuming signed overflow does not occur when " "simplifying conditional"); } if (issue_strict_overflow_warning (wc)) { location_t location; if (!gimple_has_location (stmt)) location = input_location; else location = gimple_location (stmt); warning_at (location, OPT_Wstrict_overflow, "%s", warnmsg); } } if (warn_type_limits && ret && only_ranges && TREE_CODE_CLASS (code) == tcc_comparison && TREE_CODE (op0) == SSA_NAME) { /* If the comparison is being folded and the operand on the LHS is being compared against a constant value that is outside of the natural range of OP0's type, then the predicate will always fold regardless of the value of OP0. If -Wtype-limits was specified, emit a warning. */ tree type = TREE_TYPE (op0); value_range_t *vr0 = get_value_range (op0); if (vr0->type != VR_VARYING && INTEGRAL_TYPE_P (type) && vrp_val_is_min (vr0->min) && vrp_val_is_max (vr0->max) && is_gimple_min_invariant (op1)) { location_t location; if (!gimple_has_location (stmt)) location = input_location; else location = gimple_location (stmt); warning_at (location, OPT_Wtype_limits, integer_zerop (ret) ? G_("comparison always false " "due to limited range of data type") : G_("comparison always true " "due to limited range of data type")); } } return ret; } /* Visit conditional statement STMT. If we can determine which edge will be taken out of STMT's basic block, record it in *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return SSA_PROP_VARYING. */ static enum ssa_prop_result vrp_visit_cond_stmt (gimple stmt, edge *taken_edge_p) { tree val; bool sop; *taken_edge_p = NULL; if (dump_file && (dump_flags & TDF_DETAILS)) { tree use; ssa_op_iter i; fprintf (dump_file, "\nVisiting conditional with predicate: "); print_gimple_stmt (dump_file, stmt, 0, 0); fprintf (dump_file, "\nWith known ranges\n"); FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE) { fprintf (dump_file, "\t"); print_generic_expr (dump_file, use, 0); fprintf (dump_file, ": "); dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]); } fprintf (dump_file, "\n"); } /* Compute the value of the predicate COND by checking the known ranges of each of its operands. Note that we cannot evaluate all the equivalent ranges here because those ranges may not yet be final and with the current propagation strategy, we cannot determine when the value ranges of the names in the equivalence set have changed. For instance, given the following code fragment i_5 = PHI <8, i_13> ... i_14 = ASSERT_EXPR <i_5, i_5 != 0> if (i_14 == 1) ... Assume that on the first visit to i_14, i_5 has the temporary range [8, 8] because the second argument to the PHI function is not yet executable. We derive the range ~[0, 0] for i_14 and the equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for the first time, since i_14 is equivalent to the range [8, 8], we determine that the predicate is always false. On the next round of propagation, i_13 is determined to be VARYING, which causes i_5 to drop down to VARYING. So, another visit to i_14 is scheduled. In this second visit, we compute the exact same range and equivalence set for i_14, namely ~[0, 0] and { i_5 }. But we did not have the previous range for i_5 registered, so vrp_visit_assignment thinks that the range for i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)' is not visited again, which stops propagation from visiting statements in the THEN clause of that if(). To properly fix this we would need to keep the previous range value for the names in the equivalence set. This way we would've discovered that from one visit to the other i_5 changed from range [8, 8] to VR_VARYING. However, fixing this apparent limitation may not be worth the additional checking. Testing on several code bases (GCC, DLV, MICO, TRAMP3D and SPEC2000) showed that doing this results in 4 more predicates folded in SPEC. */ sop = false; val = vrp_evaluate_conditional_warnv_with_ops (gimple_cond_code (stmt), gimple_cond_lhs (stmt), gimple_cond_rhs (stmt), false, &sop, NULL); if (val) { if (!sop) *taken_edge_p = find_taken_edge (gimple_bb (stmt), val); else { if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "\nIgnoring predicate evaluation because " "it assumes that signed overflow is undefined"); val = NULL_TREE; } } if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\nPredicate evaluates to: "); if (val == NULL_TREE) fprintf (dump_file, "DON'T KNOW\n"); else print_generic_stmt (dump_file, val, 0); } return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; } /* Searches the case label vector VEC for the index *IDX of the CASE_LABEL that includes the value VAL. The search is restricted to the range [START_IDX, n - 1] where n is the size of VEC. If there is a CASE_LABEL for VAL, its index is placed in IDX and true is returned. If there is no CASE_LABEL for VAL and there is one that is larger than VAL, it is placed in IDX and false is returned. If VAL is larger than any CASE_LABEL, n is placed on IDX and false is returned. */ static bool find_case_label_index (gimple stmt, size_t start_idx, tree val, size_t *idx) { size_t n = gimple_switch_num_labels (stmt); size_t low, high; /* Find case label for minimum of the value range or the next one. At each iteration we are searching in [low, high - 1]. */ for (low = start_idx, high = n; high != low; ) { tree t; int cmp; /* Note that i != high, so we never ask for n. */ size_t i = (high + low) / 2; t = gimple_switch_label (stmt, i); /* Cache the result of comparing CASE_LOW and val. */ cmp = tree_int_cst_compare (CASE_LOW (t), val); if (cmp == 0) { /* Ranges cannot be empty. */ *idx = i; return true; } else if (cmp > 0) high = i; else { low = i + 1; if (CASE_HIGH (t) != NULL && tree_int_cst_compare (CASE_HIGH (t), val) >= 0) { *idx = i; return true; } } } *idx = high; return false; } /* Searches the case label vector VEC for the range of CASE_LABELs that is used for values between MIN and MAX. The first index is placed in MIN_IDX. The last index is placed in MAX_IDX. If the range of CASE_LABELs is empty then MAX_IDX < MIN_IDX. Returns true if the default label is not needed. */ static bool find_case_label_range (gimple stmt, tree min, tree max, size_t *min_idx, size_t *max_idx) { size_t i, j; bool min_take_default = !find_case_label_index (stmt, 1, min, &i); bool max_take_default = !find_case_label_index (stmt, i, max, &j); if (i == j && min_take_default && max_take_default) { /* Only the default case label reached. Return an empty range. */ *min_idx = 1; *max_idx = 0; return false; } else { bool take_default = min_take_default || max_take_default; tree low, high; size_t k; if (max_take_default) j--; /* If the case label range is continuous, we do not need the default case label. Verify that. */ high = CASE_LOW (gimple_switch_label (stmt, i)); if (CASE_HIGH (gimple_switch_label (stmt, i))) high = CASE_HIGH (gimple_switch_label (stmt, i)); for (k = i + 1; k <= j; ++k) { low = CASE_LOW (gimple_switch_label (stmt, k)); if (!integer_onep (int_const_binop (MINUS_EXPR, low, high, 0))) { take_default = true; break; } high = low; if (CASE_HIGH (gimple_switch_label (stmt, k))) high = CASE_HIGH (gimple_switch_label (stmt, k)); } *min_idx = i; *max_idx = j; return !take_default; } } /* Visit switch statement STMT. If we can determine which edge will be taken out of STMT's basic block, record it in *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return SSA_PROP_VARYING. */ static enum ssa_prop_result vrp_visit_switch_stmt (gimple stmt, edge *taken_edge_p) { tree op, val; value_range_t *vr; size_t i = 0, j = 0; bool take_default; *taken_edge_p = NULL; op = gimple_switch_index (stmt); if (TREE_CODE (op) != SSA_NAME) return SSA_PROP_VARYING; vr = get_value_range (op); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\nVisiting switch expression with operand "); print_generic_expr (dump_file, op, 0); fprintf (dump_file, " with known range "); dump_value_range (dump_file, vr); fprintf (dump_file, "\n"); } if (vr->type != VR_RANGE || symbolic_range_p (vr)) return SSA_PROP_VARYING; /* Find the single edge that is taken from the switch expression. */ take_default = !find_case_label_range (stmt, vr->min, vr->max, &i, &j); /* Check if the range spans no CASE_LABEL. If so, we only reach the default label */ if (j < i) { gcc_assert (take_default); val = gimple_switch_default_label (stmt); } else { /* Check if labels with index i to j and maybe the default label are all reaching the same label. */ val = gimple_switch_label (stmt, i); if (take_default && CASE_LABEL (gimple_switch_default_label (stmt)) != CASE_LABEL (val)) { if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " not a single destination for this " "range\n"); return SSA_PROP_VARYING; } for (++i; i <= j; ++i) { if (CASE_LABEL (gimple_switch_label (stmt, i)) != CASE_LABEL (val)) { if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " not a single destination for this " "range\n"); return SSA_PROP_VARYING; } } } *taken_edge_p = find_edge (gimple_bb (stmt), label_to_block (CASE_LABEL (val))); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, " will take edge to "); print_generic_stmt (dump_file, CASE_LABEL (val), 0); } return SSA_PROP_INTERESTING; } /* Evaluate statement STMT. If the statement produces a useful range, return SSA_PROP_INTERESTING and record the SSA name with the interesting range into *OUTPUT_P. If STMT is a conditional branch and we can determine its truth value, the taken edge is recorded in *TAKEN_EDGE_P. If STMT produces a varying value, return SSA_PROP_VARYING. */ static enum ssa_prop_result vrp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p) { tree def; ssa_op_iter iter; if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\nVisiting statement:\n"); print_gimple_stmt (dump_file, stmt, 0, dump_flags); fprintf (dump_file, "\n"); } if (!stmt_interesting_for_vrp (stmt)) gcc_assert (stmt_ends_bb_p (stmt)); else if (is_gimple_assign (stmt) || is_gimple_call (stmt)) { /* In general, assignments with virtual operands are not useful for deriving ranges, with the obvious exception of calls to builtin functions. */ if ((is_gimple_call (stmt) && gimple_call_fndecl (stmt) != NULL_TREE && DECL_IS_BUILTIN (gimple_call_fndecl (stmt))) || !gimple_vuse (stmt)) return vrp_visit_assignment_or_call (stmt, output_p); } else if (gimple_code (stmt) == GIMPLE_COND) return vrp_visit_cond_stmt (stmt, taken_edge_p); else if (gimple_code (stmt) == GIMPLE_SWITCH) return vrp_visit_switch_stmt (stmt, taken_edge_p); /* All other statements produce nothing of interest for VRP, so mark their outputs varying and prevent further simulation. */ FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) set_value_range_to_varying (get_value_range (def)); return SSA_PROP_VARYING; } /* Meet operation for value ranges. Given two value ranges VR0 and VR1, store in VR0 a range that contains both VR0 and VR1. This may not be the smallest possible such range. */ static void vrp_meet (value_range_t *vr0, value_range_t *vr1) { if (vr0->type == VR_UNDEFINED) { copy_value_range (vr0, vr1); return; } if (vr1->type == VR_UNDEFINED) { /* Nothing to do. VR0 already has the resulting range. */ return; } if (vr0->type == VR_VARYING) { /* Nothing to do. VR0 already has the resulting range. */ return; } if (vr1->type == VR_VARYING) { set_value_range_to_varying (vr0); return; } if (vr0->type == VR_RANGE && vr1->type == VR_RANGE) { int cmp; tree min, max; /* Compute the convex hull of the ranges. The lower limit of the new range is the minimum of the two ranges. If they cannot be compared, then give up. */ cmp = compare_values (vr0->min, vr1->min); if (cmp == 0 || cmp == 1) min = vr1->min; else if (cmp == -1) min = vr0->min; else goto give_up; /* Similarly, the upper limit of the new range is the maximum of the two ranges. If they cannot be compared, then give up. */ cmp = compare_values (vr0->max, vr1->max); if (cmp == 0 || cmp == -1) max = vr1->max; else if (cmp == 1) max = vr0->max; else goto give_up; /* Check for useless ranges. */ if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && ((vrp_val_is_min (min) || is_overflow_infinity (min)) && (vrp_val_is_max (max) || is_overflow_infinity (max)))) goto give_up; /* The resulting set of equivalences is the intersection of the two sets. */ if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) bitmap_and_into (vr0->equiv, vr1->equiv); else if (vr0->equiv && !vr1->equiv) bitmap_clear (vr0->equiv); set_value_range (vr0, vr0->type, min, max, vr0->equiv); } else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE) { /* Two anti-ranges meet only if their complements intersect. Only handle the case of identical ranges. */ if (compare_values (vr0->min, vr1->min) == 0 && compare_values (vr0->max, vr1->max) == 0 && compare_values (vr0->min, vr0->max) == 0) { /* The resulting set of equivalences is the intersection of the two sets. */ if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) bitmap_and_into (vr0->equiv, vr1->equiv); else if (vr0->equiv && !vr1->equiv) bitmap_clear (vr0->equiv); } else goto give_up; } else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE) { /* For a numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4], only handle the case where the ranges have an empty intersection. The result of the meet operation is the anti-range. */ if (!symbolic_range_p (vr0) && !symbolic_range_p (vr1) && !value_ranges_intersect_p (vr0, vr1)) { /* Copy most of VR1 into VR0. Don't copy VR1's equivalence set. We need to compute the intersection of the two equivalence sets. */ if (vr1->type == VR_ANTI_RANGE) set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv); /* The resulting set of equivalences is the intersection of the two sets. */ if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) bitmap_and_into (vr0->equiv, vr1->equiv); else if (vr0->equiv && !vr1->equiv) bitmap_clear (vr0->equiv); } else goto give_up; } else gcc_unreachable (); return; give_up: /* Failed to find an efficient meet. Before giving up and setting the result to VARYING, see if we can at least derive a useful anti-range. FIXME, all this nonsense about distinguishing anti-ranges from ranges is necessary because of the odd semantics of range_includes_zero_p and friends. */ if (!symbolic_range_p (vr0) && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0)) || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0))) && !symbolic_range_p (vr1) && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1)) || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1)))) { set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min)); /* Since this meet operation did not result from the meeting of two equivalent names, VR0 cannot have any equivalences. */ if (vr0->equiv) bitmap_clear (vr0->equiv); } else set_value_range_to_varying (vr0); } /* Visit all arguments for PHI node PHI that flow through executable edges. If a valid value range can be derived from all the incoming value ranges, set a new range for the LHS of PHI. */ static enum ssa_prop_result vrp_visit_phi_node (gimple phi) { size_t i; tree lhs = PHI_RESULT (phi); value_range_t *lhs_vr = get_value_range (lhs); value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; int edges, old_edges; struct loop *l; copy_value_range (&vr_result, lhs_vr); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\nVisiting PHI node: "); print_gimple_stmt (dump_file, phi, 0, dump_flags); } edges = 0; for (i = 0; i < gimple_phi_num_args (phi); i++) { edge e = gimple_phi_arg_edge (phi, i); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\n Argument #%d (%d -> %d %sexecutable)\n", (int) i, e->src->index, e->dest->index, (e->flags & EDGE_EXECUTABLE) ? "" : "not "); } if (e->flags & EDGE_EXECUTABLE) { tree arg = PHI_ARG_DEF (phi, i); value_range_t vr_arg; ++edges; if (TREE_CODE (arg) == SSA_NAME) { vr_arg = *(get_value_range (arg)); } else { if (is_overflow_infinity (arg)) { arg = copy_node (arg); TREE_OVERFLOW (arg) = 0; } vr_arg.type = VR_RANGE; vr_arg.min = arg; vr_arg.max = arg; vr_arg.equiv = NULL; } if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "\t"); print_generic_expr (dump_file, arg, dump_flags); fprintf (dump_file, "\n\tValue: "); dump_value_range (dump_file, &vr_arg); fprintf (dump_file, "\n"); } vrp_meet (&vr_result, &vr_arg); if (vr_result.type == VR_VARYING) break; } } /* If this is a loop PHI node SCEV may known more about its value-range. */ if (current_loops && (l = loop_containing_stmt (phi)) && l->header == gimple_bb (phi)) adjust_range_with_scev (&vr_result, l, phi, lhs); if (vr_result.type == VR_VARYING) goto varying; old_edges = vr_phi_edge_counts[SSA_NAME_VERSION (lhs)]; vr_phi_edge_counts[SSA_NAME_VERSION (lhs)] = edges; /* To prevent infinite iterations in the algorithm, derive ranges when the new value is slightly bigger or smaller than the previous one. We don't do this if we have seen a new executable edge; this helps us avoid an overflow infinity for conditionals which are not in a loop. */ if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE && edges <= old_edges) { if (!POINTER_TYPE_P (TREE_TYPE (lhs))) { int cmp_min = compare_values (lhs_vr->min, vr_result.min); int cmp_max = compare_values (lhs_vr->max, vr_result.max); /* If the new minimum is smaller or larger than the previous one, go all the way to -INF. In the first case, to avoid iterating millions of times to reach -INF, and in the other case to avoid infinite bouncing between different minimums. */ if (cmp_min > 0 || cmp_min < 0) { /* If we will end up with a (-INF, +INF) range, set it to VARYING. Same if the previous max value was invalid for the type and we'd end up with vr_result.min > vr_result.max. */ if (vrp_val_is_max (vr_result.max) || compare_values (TYPE_MIN_VALUE (TREE_TYPE (vr_result.min)), vr_result.max) > 0) goto varying; if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)) || !vrp_var_may_overflow (lhs, phi)) vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min)); else if (supports_overflow_infinity (TREE_TYPE (vr_result.min))) vr_result.min = negative_overflow_infinity (TREE_TYPE (vr_result.min)); else goto varying; } /* Similarly, if the new maximum is smaller or larger than the previous one, go all the way to +INF. */ if (cmp_max < 0 || cmp_max > 0) { /* If we will end up with a (-INF, +INF) range, set it to VARYING. Same if the previous min value was invalid for the type and we'd end up with vr_result.max < vr_result.min. */ if (vrp_val_is_min (vr_result.min) || compare_values (TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)), vr_result.min) < 0) goto varying; if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)) || !vrp_var_may_overflow (lhs, phi)) vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)); else if (supports_overflow_infinity (TREE_TYPE (vr_result.max))) vr_result.max = positive_overflow_infinity (TREE_TYPE (vr_result.max)); else goto varying; } } } /* If the new range is different than the previous value, keep iterating. */ if (update_value_range (lhs, &vr_result)) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Found new range for "); print_generic_expr (dump_file, lhs, 0); fprintf (dump_file, ": "); dump_value_range (dump_file, &vr_result); fprintf (dump_file, "\n\n"); } return SSA_PROP_INTERESTING; } /* Nothing changed, don't add outgoing edges. */ return SSA_PROP_NOT_INTERESTING; /* No match found. Set the LHS to VARYING. */ varying: set_value_range_to_varying (lhs_vr); return SSA_PROP_VARYING; } /* Simplify boolean operations if the source is known to be already a boolean. */ static bool simplify_truth_ops_using_ranges (gimple_stmt_iterator *gsi, gimple stmt) { enum tree_code rhs_code = gimple_assign_rhs_code (stmt); tree val = NULL; tree op0, op1; value_range_t *vr; bool sop = false; bool need_conversion; op0 = gimple_assign_rhs1 (stmt); if (TYPE_PRECISION (TREE_TYPE (op0)) != 1) { if (TREE_CODE (op0) != SSA_NAME) return false; vr = get_value_range (op0); val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, &sop); if (!val || !integer_onep (val)) return false; val = compare_range_with_value (LE_EXPR, vr, integer_one_node, &sop); if (!val || !integer_onep (val)) return false; } if (rhs_code == TRUTH_NOT_EXPR) { rhs_code = NE_EXPR; op1 = build_int_cst (TREE_TYPE (op0), 1); } else { op1 = gimple_assign_rhs2 (stmt); /* Reduce number of cases to handle. */ if (is_gimple_min_invariant (op1)) { /* Exclude anything that should have been already folded. */ if (rhs_code != EQ_EXPR && rhs_code != NE_EXPR && rhs_code != TRUTH_XOR_EXPR) return false; if (!integer_zerop (op1) && !integer_onep (op1) && !integer_all_onesp (op1)) return false; /* Limit the number of cases we have to consider. */ if (rhs_code == EQ_EXPR) { rhs_code = NE_EXPR; op1 = fold_unary (TRUTH_NOT_EXPR, TREE_TYPE (op1), op1); } } else { /* Punt on A == B as there is no BIT_XNOR_EXPR. */ if (rhs_code == EQ_EXPR) return false; if (TYPE_PRECISION (TREE_TYPE (op1)) != 1) { vr = get_value_range (op1); val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, &sop); if (!val || !integer_onep (val)) return false; val = compare_range_with_value (LE_EXPR, vr, integer_one_node, &sop); if (!val || !integer_onep (val)) return false; } } } if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) { location_t location; if (!gimple_has_location (stmt)) location = input_location; else location = gimple_location (stmt); if (rhs_code == TRUTH_AND_EXPR || rhs_code == TRUTH_OR_EXPR) warning_at (location, OPT_Wstrict_overflow, _("assuming signed overflow does not occur when " "simplifying && or || to & or |")); else warning_at (location, OPT_Wstrict_overflow, _("assuming signed overflow does not occur when " "simplifying ==, != or ! to identity or ^")); } need_conversion = !useless_type_conversion_p (TREE_TYPE (gimple_assign_lhs (stmt)), TREE_TYPE (op0)); /* Make sure to not sign-extend -1 as a boolean value. */ if (need_conversion && !TYPE_UNSIGNED (TREE_TYPE (op0)) && TYPE_PRECISION (TREE_TYPE (op0)) == 1) return false; switch (rhs_code) { case TRUTH_AND_EXPR: rhs_code = BIT_AND_EXPR; break; case TRUTH_OR_EXPR: rhs_code = BIT_IOR_EXPR; break; case TRUTH_XOR_EXPR: case NE_EXPR: if (integer_zerop (op1)) { gimple_assign_set_rhs_with_ops (gsi, need_conversion ? NOP_EXPR : SSA_NAME, op0, NULL); update_stmt (gsi_stmt (*gsi)); return true; } rhs_code = BIT_XOR_EXPR; break; default: gcc_unreachable (); } if (need_conversion) return false; gimple_assign_set_rhs_with_ops (gsi, rhs_code, op0, op1); update_stmt (gsi_stmt (*gsi)); return true; } /* Simplify a division or modulo operator to a right shift or bitwise and if the first operand is unsigned or is greater than zero and the second operand is an exact power of two. */ static bool simplify_div_or_mod_using_ranges (gimple stmt) { enum tree_code rhs_code = gimple_assign_rhs_code (stmt); tree val = NULL; tree op0 = gimple_assign_rhs1 (stmt); tree op1 = gimple_assign_rhs2 (stmt); value_range_t *vr = get_value_range (gimple_assign_rhs1 (stmt)); if (TYPE_UNSIGNED (TREE_TYPE (op0))) { val = integer_one_node; } else { bool sop = false; val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, &sop); if (val && sop && integer_onep (val) && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) { location_t location; if (!gimple_has_location (stmt)) location = input_location; else location = gimple_location (stmt); warning_at (location, OPT_Wstrict_overflow, "assuming signed overflow does not occur when " "simplifying %</%> or %<%%%> to %<>>%> or %<&%>"); } } if (val && integer_onep (val)) { tree t; if (rhs_code == TRUNC_DIV_EXPR) { t = build_int_cst (NULL_TREE, tree_log2 (op1)); gimple_assign_set_rhs_code (stmt, RSHIFT_EXPR); gimple_assign_set_rhs1 (stmt, op0); gimple_assign_set_rhs2 (stmt, t); } else { t = build_int_cst (TREE_TYPE (op1), 1); t = int_const_binop (MINUS_EXPR, op1, t, 0); t = fold_convert (TREE_TYPE (op0), t); gimple_assign_set_rhs_code (stmt, BIT_AND_EXPR); gimple_assign_set_rhs1 (stmt, op0); gimple_assign_set_rhs2 (stmt, t); } update_stmt (stmt); return true; } return false; } /* If the operand to an ABS_EXPR is >= 0, then eliminate the ABS_EXPR. If the operand is <= 0, then simplify the ABS_EXPR into a NEGATE_EXPR. */ static bool simplify_abs_using_ranges (gimple stmt) { tree val = NULL; tree op = gimple_assign_rhs1 (stmt); tree type = TREE_TYPE (op); value_range_t *vr = get_value_range (op); if (TYPE_UNSIGNED (type)) { val = integer_zero_node; } else if (vr) { bool sop = false; val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop); if (!val) { sop = false; val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, &sop); if (val) { if (integer_zerop (val)) val = integer_one_node; else if (integer_onep (val)) val = integer_zero_node; } } if (val && (integer_onep (val) || integer_zerop (val))) { if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) { location_t location; if (!gimple_has_location (stmt)) location = input_location; else location = gimple_location (stmt); warning_at (location, OPT_Wstrict_overflow, "assuming signed overflow does not occur when " "simplifying %<abs (X)%> to %<X%> or %<-X%>"); } gimple_assign_set_rhs1 (stmt, op); if (integer_onep (val)) gimple_assign_set_rhs_code (stmt, NEGATE_EXPR); else gimple_assign_set_rhs_code (stmt, SSA_NAME); update_stmt (stmt); return true; } } return false; } /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has a known value range VR. If there is one and only one value which will satisfy the conditional, then return that value. Else return NULL. */ static tree test_for_singularity (enum tree_code cond_code, tree op0, tree op1, value_range_t *vr) { tree min = NULL; tree max = NULL; /* Extract minimum/maximum values which satisfy the the conditional as it was written. */ if (cond_code == LE_EXPR || cond_code == LT_EXPR) { /* This should not be negative infinity; there is no overflow here. */ min = TYPE_MIN_VALUE (TREE_TYPE (op0)); max = op1; if (cond_code == LT_EXPR && !is_overflow_infinity (max)) { tree one = build_int_cst (TREE_TYPE (op0), 1); max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one); if (EXPR_P (max)) TREE_NO_WARNING (max) = 1; } } else if (cond_code == GE_EXPR || cond_code == GT_EXPR) { /* This should not be positive infinity; there is no overflow here. */ max = TYPE_MAX_VALUE (TREE_TYPE (op0)); min = op1; if (cond_code == GT_EXPR && !is_overflow_infinity (min)) { tree one = build_int_cst (TREE_TYPE (op0), 1); min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one); if (EXPR_P (min)) TREE_NO_WARNING (min) = 1; } } /* Now refine the minimum and maximum values using any value range information we have for op0. */ if (min && max) { if (compare_values (vr->min, min) == 1) min = vr->min; if (compare_values (vr->max, max) == -1) max = vr->max; /* If the new min/max values have converged to a single value, then there is only one value which can satisfy the condition, return that value. */ if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min)) return min; } return NULL; } /* Simplify a conditional using a relational operator to an equality test if the range information indicates only one value can satisfy the original conditional. */ static bool simplify_cond_using_ranges (gimple stmt) { tree op0 = gimple_cond_lhs (stmt); tree op1 = gimple_cond_rhs (stmt); enum tree_code cond_code = gimple_cond_code (stmt); if (cond_code != NE_EXPR && cond_code != EQ_EXPR && TREE_CODE (op0) == SSA_NAME && INTEGRAL_TYPE_P (TREE_TYPE (op0)) && is_gimple_min_invariant (op1)) { value_range_t *vr = get_value_range (op0); /* If we have range information for OP0, then we might be able to simplify this conditional. */ if (vr->type == VR_RANGE) { tree new_tree = test_for_singularity (cond_code, op0, op1, vr); if (new_tree) { if (dump_file) { fprintf (dump_file, "Simplified relational "); print_gimple_stmt (dump_file, stmt, 0, 0); fprintf (dump_file, " into "); } gimple_cond_set_code (stmt, EQ_EXPR); gimple_cond_set_lhs (stmt, op0); gimple_cond_set_rhs (stmt, new_tree); update_stmt (stmt); if (dump_file) { print_gimple_stmt (dump_file, stmt, 0, 0); fprintf (dump_file, "\n"); } return true; } /* Try again after inverting the condition. We only deal with integral types here, so no need to worry about issues with inverting FP comparisons. */ cond_code = invert_tree_comparison (cond_code, false); new_tree = test_for_singularity (cond_code, op0, op1, vr); if (new_tree) { if (dump_file) { fprintf (dump_file, "Simplified relational "); print_gimple_stmt (dump_file, stmt, 0, 0); fprintf (dump_file, " into "); } gimple_cond_set_code (stmt, NE_EXPR); gimple_cond_set_lhs (stmt, op0); gimple_cond_set_rhs (stmt, new_tree); update_stmt (stmt); if (dump_file) { print_gimple_stmt (dump_file, stmt, 0, 0); fprintf (dump_file, "\n"); } return true; } } } return false; } /* Simplify a switch statement using the value range of the switch argument. */ static bool simplify_switch_using_ranges (gimple stmt) { tree op = gimple_switch_index (stmt); value_range_t *vr; bool take_default; edge e; edge_iterator ei; size_t i = 0, j = 0, n, n2; tree vec2; switch_update su; if (TREE_CODE (op) == SSA_NAME) { vr = get_value_range (op); /* We can only handle integer ranges. */ if (vr->type != VR_RANGE || symbolic_range_p (vr)) return false; /* Find case label for min/max of the value range. */ take_default = !find_case_label_range (stmt, vr->min, vr->max, &i, &j); } else if (TREE_CODE (op) == INTEGER_CST) { take_default = !find_case_label_index (stmt, 1, op, &i); if (take_default) { i = 1; j = 0; } else { j = i; } } else return false; n = gimple_switch_num_labels (stmt); /* Bail out if this is just all edges taken. */ if (i == 1 && j == n - 1 && take_default) return false; /* Build a new vector of taken case labels. */ vec2 = make_tree_vec (j - i + 1 + (int)take_default); n2 = 0; /* Add the default edge, if necessary. */ if (take_default) TREE_VEC_ELT (vec2, n2++) = gimple_switch_default_label (stmt); for (; i <= j; ++i, ++n2) TREE_VEC_ELT (vec2, n2) = gimple_switch_label (stmt, i); /* Mark needed edges. */ for (i = 0; i < n2; ++i) { e = find_edge (gimple_bb (stmt), label_to_block (CASE_LABEL (TREE_VEC_ELT (vec2, i)))); e->aux = (void *)-1; } /* Queue not needed edges for later removal. */ FOR_EACH_EDGE (e, ei, gimple_bb (stmt)->succs) { if (e->aux == (void *)-1) { e->aux = NULL; continue; } if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "removing unreachable case label\n"); } VEC_safe_push (edge, heap, to_remove_edges, e); e->flags &= ~EDGE_EXECUTABLE; } /* And queue an update for the stmt. */ su.stmt = stmt; su.vec = vec2; VEC_safe_push (switch_update, heap, to_update_switch_stmts, &su); return false; } /* Simplify STMT using ranges if possible. */ static bool simplify_stmt_using_ranges (gimple_stmt_iterator *gsi) { gimple stmt = gsi_stmt (*gsi); if (is_gimple_assign (stmt)) { enum tree_code rhs_code = gimple_assign_rhs_code (stmt); switch (rhs_code) { case EQ_EXPR: case NE_EXPR: case TRUTH_NOT_EXPR: case TRUTH_AND_EXPR: case TRUTH_OR_EXPR: case TRUTH_XOR_EXPR: /* Transform EQ_EXPR, NE_EXPR, TRUTH_NOT_EXPR into BIT_XOR_EXPR or identity if the RHS is zero or one, and the LHS are known to be boolean values. Transform all TRUTH_*_EXPR into BIT_*_EXPR if both arguments are known to be boolean values. */ if (INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt)))) return simplify_truth_ops_using_ranges (gsi, stmt); break; /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR and BIT_AND_EXPR respectively if the first operand is greater than zero and the second operand is an exact power of two. */ case TRUNC_DIV_EXPR: case TRUNC_MOD_EXPR: if (INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt))) && integer_pow2p (gimple_assign_rhs2 (stmt))) return simplify_div_or_mod_using_ranges (stmt); break; /* Transform ABS (X) into X or -X as appropriate. */ case ABS_EXPR: if (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt)))) return simplify_abs_using_ranges (stmt); break; default: break; } } else if (gimple_code (stmt) == GIMPLE_COND) return simplify_cond_using_ranges (stmt); else if (gimple_code (stmt) == GIMPLE_SWITCH) return simplify_switch_using_ranges (stmt); return false; } /* If the statement pointed by SI has a predicate whose value can be computed using the value range information computed by VRP, compute its value and return true. Otherwise, return false. */ static bool fold_predicate_in (gimple_stmt_iterator *si) { bool assignment_p = false; tree val; gimple stmt = gsi_stmt (*si); if (is_gimple_assign (stmt) && TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)) == tcc_comparison) { assignment_p = true; val = vrp_evaluate_conditional (gimple_assign_rhs_code (stmt), gimple_assign_rhs1 (stmt), gimple_assign_rhs2 (stmt), stmt); } else if (gimple_code (stmt) == GIMPLE_COND) val = vrp_evaluate_conditional (gimple_cond_code (stmt), gimple_cond_lhs (stmt), gimple_cond_rhs (stmt), stmt); else return false; if (val) { if (assignment_p) val = fold_convert (gimple_expr_type (stmt), val); if (dump_file) { fprintf (dump_file, "Folding predicate "); print_gimple_expr (dump_file, stmt, 0, 0); fprintf (dump_file, " to "); print_generic_expr (dump_file, val, 0); fprintf (dump_file, "\n"); } if (is_gimple_assign (stmt)) gimple_assign_set_rhs_from_tree (si, val); else { gcc_assert (gimple_code (stmt) == GIMPLE_COND); if (integer_zerop (val)) gimple_cond_make_false (stmt); else if (integer_onep (val)) gimple_cond_make_true (stmt); else gcc_unreachable (); } return true; } return false; } /* Callback for substitute_and_fold folding the stmt at *SI. */ static bool vrp_fold_stmt (gimple_stmt_iterator *si) { if (fold_predicate_in (si)) return true; return simplify_stmt_using_ranges (si); } /* Stack of dest,src equivalency pairs that need to be restored after each attempt to thread a block's incoming edge to an outgoing edge. A NULL entry is used to mark the end of pairs which need to be restored. */ static VEC(tree,heap) *stack; /* A trivial wrapper so that we can present the generic jump threading code with a simple API for simplifying statements. STMT is the statement we want to simplify, WITHIN_STMT provides the location for any overflow warnings. */ static tree simplify_stmt_for_jump_threading (gimple stmt, gimple within_stmt) { /* We only use VRP information to simplify conditionals. This is overly conservative, but it's unclear if doing more would be worth the compile time cost. */ if (gimple_code (stmt) != GIMPLE_COND) return NULL; return vrp_evaluate_conditional (gimple_cond_code (stmt), gimple_cond_lhs (stmt), gimple_cond_rhs (stmt), within_stmt); } /* Blocks which have more than one predecessor and more than one successor present jump threading opportunities, i.e., when the block is reached from a specific predecessor, we may be able to determine which of the outgoing edges will be traversed. When this optimization applies, we are able to avoid conditionals at runtime and we may expose secondary optimization opportunities. This routine is effectively a driver for the generic jump threading code. It basically just presents the generic code with edges that may be suitable for jump threading. Unlike DOM, we do not iterate VRP if jump threading was successful. While iterating may expose new opportunities for VRP, it is expected those opportunities would be very limited and the compile time cost to expose those opportunities would be significant. As jump threading opportunities are discovered, they are registered for later realization. */ static void identify_jump_threads (void) { basic_block bb; gimple dummy; int i; edge e; /* Ugh. When substituting values earlier in this pass we can wipe the dominance information. So rebuild the dominator information as we need it within the jump threading code. */ calculate_dominance_info (CDI_DOMINATORS); /* We do not allow VRP information to be used for jump threading across a back edge in the CFG. Otherwise it becomes too difficult to avoid eliminating loop exit tests. Of course EDGE_DFS_BACK is not accurate at this time so we have to recompute it. */ mark_dfs_back_edges (); /* Do not thread across edges we are about to remove. Just marking them as EDGE_DFS_BACK will do. */ for (i = 0; VEC_iterate (edge, to_remove_edges, i, e); ++i) e->flags |= EDGE_DFS_BACK; /* Allocate our unwinder stack to unwind any temporary equivalences that might be recorded. */ stack = VEC_alloc (tree, heap, 20); /* To avoid lots of silly node creation, we create a single conditional and just modify it in-place when attempting to thread jumps. */ dummy = gimple_build_cond (EQ_EXPR, integer_zero_node, integer_zero_node, NULL, NULL); /* Walk through all the blocks finding those which present a potential jump threading opportunity. We could set this up as a dominator walker and record data during the walk, but I doubt it's worth the effort for the classes of jump threading opportunities we are trying to identify at this point in compilation. */ FOR_EACH_BB (bb) { gimple last; /* If the generic jump threading code does not find this block interesting, then there is nothing to do. */ if (! potentially_threadable_block (bb)) continue; /* We only care about blocks ending in a COND_EXPR. While there may be some value in handling SWITCH_EXPR here, I doubt it's terribly important. */ last = gsi_stmt (gsi_last_bb (bb)); if (gimple_code (last) != GIMPLE_COND) continue; /* We're basically looking for any kind of conditional with integral type arguments. */ if (TREE_CODE (gimple_cond_lhs (last)) == SSA_NAME && INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_lhs (last))) && (TREE_CODE (gimple_cond_rhs (last)) == SSA_NAME || is_gimple_min_invariant (gimple_cond_rhs (last))) && INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_rhs (last)))) { edge_iterator ei; /* We've got a block with multiple predecessors and multiple successors which also ends in a suitable conditional. For each predecessor, see if we can thread it to a specific successor. */ FOR_EACH_EDGE (e, ei, bb->preds) { /* Do not thread across back edges or abnormal edges in the CFG. */ if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX)) continue; thread_across_edge (dummy, e, true, &stack, simplify_stmt_for_jump_threading); } } } /* We do not actually update the CFG or SSA graphs at this point as ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet handle ASSERT_EXPRs gracefully. */ } /* We identified all the jump threading opportunities earlier, but could not transform the CFG at that time. This routine transforms the CFG and arranges for the dominator tree to be rebuilt if necessary. Note the SSA graph update will occur during the normal TODO processing by the pass manager. */ static void finalize_jump_threads (void) { thread_through_all_blocks (false); VEC_free (tree, heap, stack); } /* Traverse all the blocks folding conditionals with known ranges. */ static void vrp_finalize (void) { size_t i; prop_value_t *single_val_range; bool do_value_subst_p; if (dump_file) { fprintf (dump_file, "\nValue ranges after VRP:\n\n"); dump_all_value_ranges (dump_file); fprintf (dump_file, "\n"); } /* We may have ended with ranges that have exactly one value. Those values can be substituted as any other const propagated value using substitute_and_fold. */ single_val_range = XCNEWVEC (prop_value_t, num_ssa_names); do_value_subst_p = false; for (i = 0; i < num_ssa_names; i++) if (vr_value[i] && vr_value[i]->type == VR_RANGE && vr_value[i]->min == vr_value[i]->max && is_gimple_min_invariant (vr_value[i]->min)) { single_val_range[i].value = vr_value[i]->min; do_value_subst_p = true; } if (!do_value_subst_p) { /* We found no single-valued ranges, don't waste time trying to do single value substitution in substitute_and_fold. */ free (single_val_range); single_val_range = NULL; } substitute_and_fold (single_val_range, vrp_fold_stmt, false); if (warn_array_bounds) check_all_array_refs (); /* We must identify jump threading opportunities before we release the datastructures built by VRP. */ identify_jump_threads (); /* Free allocated memory. */ for (i = 0; i < num_ssa_names; i++) if (vr_value[i]) { BITMAP_FREE (vr_value[i]->equiv); free (vr_value[i]); } free (single_val_range); free (vr_value); free (vr_phi_edge_counts); /* So that we can distinguish between VRP data being available and not available. */ vr_value = NULL; vr_phi_edge_counts = NULL; } /* Main entry point to VRP (Value Range Propagation). This pass is loosely based on J. R. C. Patterson, ``Accurate Static Branch Prediction by Value Range Propagation,'' in SIGPLAN Conference on Programming Language Design and Implementation, pp. 67-78, 1995. Also available at http://citeseer.ist.psu.edu/patterson95accurate.html This is essentially an SSA-CCP pass modified to deal with ranges instead of constants. While propagating ranges, we may find that two or more SSA name have equivalent, though distinct ranges. For instance, 1 x_9 = p_3->a; 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0> 3 if (p_4 == q_2) 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>; 5 endif 6 if (q_2) In the code above, pointer p_5 has range [q_2, q_2], but from the code we can also determine that p_5 cannot be NULL and, if q_2 had a non-varying range, p_5's range should also be compatible with it. These equivalences are created by two expressions: ASSERT_EXPR and copy operations. Since p_5 is an assertion on p_4, and p_4 was the result of another assertion, then we can use the fact that p_5 and p_4 are equivalent when evaluating p_5's range. Together with value ranges, we also propagate these equivalences between names so that we can take advantage of information from multiple ranges when doing final replacement. Note that this equivalency relation is transitive but not symmetric. In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we cannot assert that q_2 is equivalent to p_5 because q_2 may be used in contexts where that assertion does not hold (e.g., in line 6). TODO, the main difference between this pass and Patterson's is that we do not propagate edge probabilities. We only compute whether edges can be taken or not. That is, instead of having a spectrum of jump probabilities between 0 and 1, we only deal with 0, 1 and DON'T KNOW. In the future, it may be worthwhile to propagate probabilities to aid branch prediction. */ static unsigned int execute_vrp (void) { int i; edge e; switch_update *su; loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS); rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa); scev_initialize (); insert_range_assertions (); to_remove_edges = VEC_alloc (edge, heap, 10); to_update_switch_stmts = VEC_alloc (switch_update, heap, 5); threadedge_initialize_values (); vrp_initialize (); ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node); vrp_finalize (); /* ASSERT_EXPRs must be removed before finalizing jump threads as finalizing jump threads calls the CFG cleanup code which does not properly handle ASSERT_EXPRs. */ remove_range_assertions (); /* If we exposed any new variables, go ahead and put them into SSA form now, before we handle jump threading. This simplifies interactions between rewriting of _DECL nodes into SSA form and rewriting SSA_NAME nodes into SSA form after block duplication and CFG manipulation. */ update_ssa (TODO_update_ssa); finalize_jump_threads (); /* Remove dead edges from SWITCH_EXPR optimization. This leaves the CFG in a broken state and requires a cfg_cleanup run. */ for (i = 0; VEC_iterate (edge, to_remove_edges, i, e); ++i) remove_edge (e); /* Update SWITCH_EXPR case label vector. */ for (i = 0; VEC_iterate (switch_update, to_update_switch_stmts, i, su); ++i) { size_t j; size_t n = TREE_VEC_LENGTH (su->vec); tree label; gimple_switch_set_num_labels (su->stmt, n); for (j = 0; j < n; j++) gimple_switch_set_label (su->stmt, j, TREE_VEC_ELT (su->vec, j)); /* As we may have replaced the default label with a regular one make sure to make it a real default label again. This ensures optimal expansion. */ label = gimple_switch_default_label (su->stmt); CASE_LOW (label) = NULL_TREE; CASE_HIGH (label) = NULL_TREE; } if (VEC_length (edge, to_remove_edges) > 0) free_dominance_info (CDI_DOMINATORS); VEC_free (edge, heap, to_remove_edges); VEC_free (switch_update, heap, to_update_switch_stmts); threadedge_finalize_values (); scev_finalize (); loop_optimizer_finalize (); return 0; } static bool gate_vrp (void) { return flag_tree_vrp != 0; } struct gimple_opt_pass pass_vrp = { { GIMPLE_PASS, "vrp", /* name */ gate_vrp, /* gate */ execute_vrp, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_TREE_VRP, /* tv_id */ PROP_ssa, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_cleanup_cfg | TODO_ggc_collect | TODO_verify_ssa | TODO_dump_func | TODO_update_ssa /* todo_flags_finish */ } };
Go to most recent revision | Compare with Previous | Blame | View Log