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/* Miscellaneous SSA utility functions. Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009 Free Software Foundation, Inc. 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 "tree.h" #include "flags.h" #include "rtl.h" #include "tm_p.h" #include "target.h" #include "ggc.h" #include "langhooks.h" #include "hard-reg-set.h" #include "basic-block.h" #include "output.h" #include "expr.h" #include "function.h" #include "diagnostic.h" #include "bitmap.h" #include "pointer-set.h" #include "tree-flow.h" #include "gimple.h" #include "tree-inline.h" #include "varray.h" #include "timevar.h" #include "hashtab.h" #include "tree-dump.h" #include "tree-pass.h" #include "toplev.h" /* Pointer map of variable mappings, keyed by edge. */ static struct pointer_map_t *edge_var_maps; /* Add a mapping with PHI RESULT and PHI DEF associated with edge E. */ void redirect_edge_var_map_add (edge e, tree result, tree def, source_location locus) { void **slot; edge_var_map_vector old_head, head; edge_var_map new_node; if (edge_var_maps == NULL) edge_var_maps = pointer_map_create (); slot = pointer_map_insert (edge_var_maps, e); old_head = head = (edge_var_map_vector) *slot; if (!head) { head = VEC_alloc (edge_var_map, heap, 5); *slot = head; } new_node.def = def; new_node.result = result; new_node.locus = locus; VEC_safe_push (edge_var_map, heap, head, &new_node); if (old_head != head) { /* The push did some reallocation. Update the pointer map. */ *slot = head; } } /* Clear the var mappings in edge E. */ void redirect_edge_var_map_clear (edge e) { void **slot; edge_var_map_vector head; if (!edge_var_maps) return; slot = pointer_map_contains (edge_var_maps, e); if (slot) { head = (edge_var_map_vector) *slot; VEC_free (edge_var_map, heap, head); *slot = NULL; } } /* Duplicate the redirected var mappings in OLDE in NEWE. Since we can't remove a mapping, let's just duplicate it. This assumes a pointer_map can have multiple edges mapping to the same var_map (many to one mapping), since we don't remove the previous mappings. */ void redirect_edge_var_map_dup (edge newe, edge olde) { void **new_slot, **old_slot; edge_var_map_vector head; if (!edge_var_maps) return; new_slot = pointer_map_insert (edge_var_maps, newe); old_slot = pointer_map_contains (edge_var_maps, olde); if (!old_slot) return; head = (edge_var_map_vector) *old_slot; if (head) *new_slot = VEC_copy (edge_var_map, heap, head); else *new_slot = VEC_alloc (edge_var_map, heap, 5); } /* Return the variable mappings for a given edge. If there is none, return NULL. */ edge_var_map_vector redirect_edge_var_map_vector (edge e) { void **slot; /* Hey, what kind of idiot would... you'd be surprised. */ if (!edge_var_maps) return NULL; slot = pointer_map_contains (edge_var_maps, e); if (!slot) return NULL; return (edge_var_map_vector) *slot; } /* Used by redirect_edge_var_map_destroy to free all memory. */ static bool free_var_map_entry (const void *key ATTRIBUTE_UNUSED, void **value, void *data ATTRIBUTE_UNUSED) { edge_var_map_vector head = (edge_var_map_vector) *value; VEC_free (edge_var_map, heap, head); return true; } /* Clear the edge variable mappings. */ void redirect_edge_var_map_destroy (void) { if (edge_var_maps) { pointer_map_traverse (edge_var_maps, free_var_map_entry, NULL); pointer_map_destroy (edge_var_maps); edge_var_maps = NULL; } } /* Remove the corresponding arguments from the PHI nodes in E's destination block and redirect it to DEST. Return redirected edge. The list of removed arguments is stored in a vector accessed through edge_var_maps. */ edge ssa_redirect_edge (edge e, basic_block dest) { gimple_stmt_iterator gsi; gimple phi; redirect_edge_var_map_clear (e); /* Remove the appropriate PHI arguments in E's destination block. */ for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi); gsi_next (&gsi)) { tree def; source_location locus ; phi = gsi_stmt (gsi); def = gimple_phi_arg_def (phi, e->dest_idx); locus = gimple_phi_arg_location (phi, e->dest_idx); if (def == NULL_TREE) continue; redirect_edge_var_map_add (e, gimple_phi_result (phi), def, locus); } e = redirect_edge_succ_nodup (e, dest); return e; } /* Add PHI arguments queued in PENDING_STMT list on edge E to edge E->dest. */ void flush_pending_stmts (edge e) { gimple phi; edge_var_map_vector v; edge_var_map *vm; int i; gimple_stmt_iterator gsi; v = redirect_edge_var_map_vector (e); if (!v) return; for (gsi = gsi_start_phis (e->dest), i = 0; !gsi_end_p (gsi) && VEC_iterate (edge_var_map, v, i, vm); gsi_next (&gsi), i++) { tree def; phi = gsi_stmt (gsi); def = redirect_edge_var_map_def (vm); add_phi_arg (phi, def, e, redirect_edge_var_map_location (vm)); } redirect_edge_var_map_clear (e); } /* Given a tree for an expression for which we might want to emit locations or values in debug information (generally a variable, but we might deal with other kinds of trees in the future), return the tree that should be used as the variable of a DEBUG_BIND STMT or VAR_LOCATION INSN or NOTE. Return NULL if VAR is not to be tracked. */ tree target_for_debug_bind (tree var) { if (!MAY_HAVE_DEBUG_STMTS) return NULL_TREE; if (TREE_CODE (var) != VAR_DECL && TREE_CODE (var) != PARM_DECL) return NULL_TREE; if (DECL_HAS_VALUE_EXPR_P (var)) return target_for_debug_bind (DECL_VALUE_EXPR (var)); if (DECL_IGNORED_P (var)) return NULL_TREE; if (!is_gimple_reg (var)) return NULL_TREE; return var; } /* Called via walk_tree, look for SSA_NAMEs that have already been released. */ static tree find_released_ssa_name (tree *tp, int *walk_subtrees, void *data_) { struct walk_stmt_info *wi = (struct walk_stmt_info *) data_; if (wi && wi->is_lhs) return NULL_TREE; if (TREE_CODE (*tp) == SSA_NAME) { if (SSA_NAME_IN_FREE_LIST (*tp)) return *tp; *walk_subtrees = 0; } else if (IS_TYPE_OR_DECL_P (*tp)) *walk_subtrees = 0; return NULL_TREE; } /* Insert a DEBUG BIND stmt before the DEF of VAR if VAR is referenced by other DEBUG stmts, and replace uses of the DEF with the newly-created debug temp. */ void insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var) { imm_use_iterator imm_iter; use_operand_p use_p; gimple stmt; gimple def_stmt = NULL; int usecount = 0; tree value = NULL; if (!MAY_HAVE_DEBUG_STMTS) return; /* If this name has already been registered for replacement, do nothing as anything that uses this name isn't in SSA form. */ if (name_registered_for_update_p (var)) return; /* Check whether there are debug stmts that reference this variable and, if there are, decide whether we should use a debug temp. */ FOR_EACH_IMM_USE_FAST (use_p, imm_iter, var) { stmt = USE_STMT (use_p); if (!gimple_debug_bind_p (stmt)) continue; if (usecount++) break; if (gimple_debug_bind_get_value (stmt) != var) { /* Count this as an additional use, so as to make sure we use a temp unless VAR's definition has a SINGLE_RHS that can be shared. */ usecount++; break; } } if (!usecount) return; if (gsi) def_stmt = gsi_stmt (*gsi); else def_stmt = SSA_NAME_DEF_STMT (var); /* If we didn't get an insertion point, and the stmt has already been removed, we won't be able to insert the debug bind stmt, so we'll have to drop debug information. */ if (gimple_code (def_stmt) == GIMPLE_PHI) { value = degenerate_phi_result (def_stmt); if (value && walk_tree (&value, find_released_ssa_name, NULL, NULL)) value = NULL; } else if (is_gimple_assign (def_stmt)) { bool no_value = false; if (!dom_info_available_p (CDI_DOMINATORS)) { struct walk_stmt_info wi; memset (&wi, 0, sizeof (wi)); /* When removing blocks without following reverse dominance order, we may sometimes encounter SSA_NAMEs that have already been released, referenced in other SSA_DEFs that we're about to release. Consider: <bb X>: v_1 = foo; <bb Y>: w_2 = v_1 + bar; # DEBUG w => w_2 If we deleted BB X first, propagating the value of w_2 won't do us any good. It's too late to recover their original definition of v_1: when it was deleted, it was only referenced in other DEFs, it couldn't possibly know it should have been retained, and propagating every single DEF just in case it might have to be propagated into a DEBUG STMT would probably be too wasteful. When dominator information is not readily available, we check for and accept some loss of debug information. But if it is available, there's no excuse for us to remove blocks in the wrong order, so we don't even check for dead SSA NAMEs. SSA verification shall catch any errors. */ if ((!gsi && !gimple_bb (def_stmt)) || walk_gimple_op (def_stmt, find_released_ssa_name, &wi)) no_value = true; } if (!no_value) value = gimple_assign_rhs_to_tree (def_stmt); } if (value) { /* If there's a single use of VAR, and VAR is the entire debug expression (usecount would have been incremented again otherwise), and the definition involves only constants and SSA names, then we can propagate VALUE into this single use, avoiding the temp. We can also avoid using a temp if VALUE can be shared and propagated into all uses, without generating expressions that wouldn't be valid gimple RHSs. Other cases that would require unsharing or non-gimple RHSs are deferred to a debug temp, although we could avoid temps at the expense of duplication of expressions. */ if (CONSTANT_CLASS_P (value) || gimple_code (def_stmt) == GIMPLE_PHI || (usecount == 1 && (!gimple_assign_single_p (def_stmt) || is_gimple_min_invariant (value))) || is_gimple_reg (value)) value = unshare_expr (value); else { gimple def_temp; tree vexpr = make_node (DEBUG_EXPR_DECL); def_temp = gimple_build_debug_bind (vexpr, unshare_expr (value), def_stmt); DECL_ARTIFICIAL (vexpr) = 1; TREE_TYPE (vexpr) = TREE_TYPE (value); if (DECL_P (value)) DECL_MODE (vexpr) = DECL_MODE (value); else DECL_MODE (vexpr) = TYPE_MODE (TREE_TYPE (value)); if (gsi) gsi_insert_before (gsi, def_temp, GSI_SAME_STMT); else { gimple_stmt_iterator ngsi = gsi_for_stmt (def_stmt); gsi_insert_before (&ngsi, def_temp, GSI_SAME_STMT); } value = vexpr; } } FOR_EACH_IMM_USE_STMT (stmt, imm_iter, var) { if (!gimple_debug_bind_p (stmt)) continue; if (value) FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter) /* unshare_expr is not needed here. vexpr is either a SINGLE_RHS, that can be safely shared, some other RHS that was unshared when we found it had a single debug use, or a DEBUG_EXPR_DECL, that can be safely shared. */ SET_USE (use_p, value); else gimple_debug_bind_reset_value (stmt); update_stmt (stmt); } } /* Insert a DEBUG BIND stmt before STMT for each DEF referenced by other DEBUG stmts, and replace uses of the DEF with the newly-created debug temp. */ void insert_debug_temps_for_defs (gimple_stmt_iterator *gsi) { gimple stmt; ssa_op_iter op_iter; def_operand_p def_p; if (!MAY_HAVE_DEBUG_STMTS) return; stmt = gsi_stmt (*gsi); FOR_EACH_PHI_OR_STMT_DEF (def_p, stmt, op_iter, SSA_OP_DEF) { tree var = DEF_FROM_PTR (def_p); if (TREE_CODE (var) != SSA_NAME) continue; insert_debug_temp_for_var_def (gsi, var); } } /* Delete SSA DEFs for SSA versions in the TOREMOVE bitmap, removing dominated stmts before their dominators, so that release_ssa_defs stands a chance of propagating DEFs into debug bind stmts. */ void release_defs_bitset (bitmap toremove) { unsigned j; bitmap_iterator bi; /* Performing a topological sort is probably overkill, this will most likely run in slightly superlinear time, rather than the pathological quadratic worst case. */ while (!bitmap_empty_p (toremove)) EXECUTE_IF_SET_IN_BITMAP (toremove, 0, j, bi) { bool remove_now = true; tree var = ssa_name (j); gimple stmt; imm_use_iterator uit; FOR_EACH_IMM_USE_STMT (stmt, uit, var) { ssa_op_iter dit; def_operand_p def_p; /* We can't propagate PHI nodes into debug stmts. */ if (gimple_code (stmt) == GIMPLE_PHI || is_gimple_debug (stmt)) continue; /* If we find another definition to remove that uses the one we're looking at, defer the removal of this one, so that it can be propagated into debug stmts after the other is. */ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, dit, SSA_OP_DEF) { tree odef = DEF_FROM_PTR (def_p); if (bitmap_bit_p (toremove, SSA_NAME_VERSION (odef))) { remove_now = false; break; } } if (!remove_now) BREAK_FROM_IMM_USE_STMT (uit); } if (remove_now) { gimple def = SSA_NAME_DEF_STMT (var); gimple_stmt_iterator gsi = gsi_for_stmt (def); if (gimple_code (def) == GIMPLE_PHI) remove_phi_node (&gsi, true); else { gsi_remove (&gsi, true); release_defs (def); } bitmap_clear_bit (toremove, j); } } } /* Return true if SSA_NAME is malformed and mark it visited. IS_VIRTUAL is true if this SSA_NAME was found inside a virtual operand. */ static bool verify_ssa_name (tree ssa_name, bool is_virtual) { if (TREE_CODE (ssa_name) != SSA_NAME) { error ("expected an SSA_NAME object"); return true; } if (TREE_TYPE (ssa_name) != TREE_TYPE (SSA_NAME_VAR (ssa_name))) { error ("type mismatch between an SSA_NAME and its symbol"); return true; } if (SSA_NAME_IN_FREE_LIST (ssa_name)) { error ("found an SSA_NAME that had been released into the free pool"); return true; } if (is_virtual && is_gimple_reg (ssa_name)) { error ("found a virtual definition for a GIMPLE register"); return true; } if (is_virtual && SSA_NAME_VAR (ssa_name) != gimple_vop (cfun)) { error ("virtual SSA name for non-VOP decl"); return true; } if (!is_virtual && !is_gimple_reg (ssa_name)) { error ("found a real definition for a non-register"); return true; } if (SSA_NAME_IS_DEFAULT_DEF (ssa_name) && !gimple_nop_p (SSA_NAME_DEF_STMT (ssa_name))) { error ("found a default name with a non-empty defining statement"); return true; } return false; } /* Return true if the definition of SSA_NAME at block BB is malformed. STMT is the statement where SSA_NAME is created. DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set, it means that the block in that array slot contains the definition of SSA_NAME. IS_VIRTUAL is true if SSA_NAME is created by a VDEF. */ static bool verify_def (basic_block bb, basic_block *definition_block, tree ssa_name, gimple stmt, bool is_virtual) { if (verify_ssa_name (ssa_name, is_virtual)) goto err; if (definition_block[SSA_NAME_VERSION (ssa_name)]) { error ("SSA_NAME created in two different blocks %i and %i", definition_block[SSA_NAME_VERSION (ssa_name)]->index, bb->index); goto err; } definition_block[SSA_NAME_VERSION (ssa_name)] = bb; if (SSA_NAME_DEF_STMT (ssa_name) != stmt) { error ("SSA_NAME_DEF_STMT is wrong"); fprintf (stderr, "Expected definition statement:\n"); print_gimple_stmt (stderr, SSA_NAME_DEF_STMT (ssa_name), 4, TDF_VOPS); fprintf (stderr, "\nActual definition statement:\n"); print_gimple_stmt (stderr, stmt, 4, TDF_VOPS); goto err; } return false; err: fprintf (stderr, "while verifying SSA_NAME "); print_generic_expr (stderr, ssa_name, 0); fprintf (stderr, " in statement\n"); print_gimple_stmt (stderr, stmt, 4, TDF_VOPS); return true; } /* Return true if the use of SSA_NAME at statement STMT in block BB is malformed. DEF_BB is the block where SSA_NAME was found to be created. IDOM contains immediate dominator information for the flowgraph. CHECK_ABNORMAL is true if the caller wants to check whether this use is flowing through an abnormal edge (only used when checking PHI arguments). If NAMES_DEFINED_IN_BB is not NULL, it contains a bitmap of ssa names that are defined before STMT in basic block BB. */ static bool verify_use (basic_block bb, basic_block def_bb, use_operand_p use_p, gimple stmt, bool check_abnormal, bitmap names_defined_in_bb) { bool err = false; tree ssa_name = USE_FROM_PTR (use_p); if (!TREE_VISITED (ssa_name)) if (verify_imm_links (stderr, ssa_name)) err = true; TREE_VISITED (ssa_name) = 1; if (gimple_nop_p (SSA_NAME_DEF_STMT (ssa_name)) && SSA_NAME_IS_DEFAULT_DEF (ssa_name)) ; /* Default definitions have empty statements. Nothing to do. */ else if (!def_bb) { error ("missing definition"); err = true; } else if (bb != def_bb && !dominated_by_p (CDI_DOMINATORS, bb, def_bb)) { error ("definition in block %i does not dominate use in block %i", def_bb->index, bb->index); err = true; } else if (bb == def_bb && names_defined_in_bb != NULL && !bitmap_bit_p (names_defined_in_bb, SSA_NAME_VERSION (ssa_name))) { error ("definition in block %i follows the use", def_bb->index); err = true; } if (check_abnormal && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (ssa_name)) { error ("SSA_NAME_OCCURS_IN_ABNORMAL_PHI should be set"); err = true; } /* Make sure the use is in an appropriate list by checking the previous element to make sure it's the same. */ if (use_p->prev == NULL) { error ("no immediate_use list"); err = true; } else { tree listvar; if (use_p->prev->use == NULL) listvar = use_p->prev->loc.ssa_name; else listvar = USE_FROM_PTR (use_p->prev); if (listvar != ssa_name) { error ("wrong immediate use list"); err = true; } } if (err) { fprintf (stderr, "for SSA_NAME: "); print_generic_expr (stderr, ssa_name, TDF_VOPS); fprintf (stderr, " in statement:\n"); print_gimple_stmt (stderr, stmt, 0, TDF_VOPS); } return err; } /* Return true if any of the arguments for PHI node PHI at block BB is malformed. DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set, it means that the block in that array slot contains the definition of SSA_NAME. */ static bool verify_phi_args (gimple phi, basic_block bb, basic_block *definition_block) { edge e; bool err = false; size_t i, phi_num_args = gimple_phi_num_args (phi); if (EDGE_COUNT (bb->preds) != phi_num_args) { error ("incoming edge count does not match number of PHI arguments"); err = true; goto error; } for (i = 0; i < phi_num_args; i++) { use_operand_p op_p = gimple_phi_arg_imm_use_ptr (phi, i); tree op = USE_FROM_PTR (op_p); e = EDGE_PRED (bb, i); if (op == NULL_TREE) { error ("PHI argument is missing for edge %d->%d", e->src->index, e->dest->index); err = true; goto error; } if (TREE_CODE (op) != SSA_NAME && !is_gimple_min_invariant (op)) { error ("PHI argument is not SSA_NAME, or invariant"); err = true; } if (TREE_CODE (op) == SSA_NAME) { err = verify_ssa_name (op, !is_gimple_reg (gimple_phi_result (phi))); err |= verify_use (e->src, definition_block[SSA_NAME_VERSION (op)], op_p, phi, e->flags & EDGE_ABNORMAL, NULL); } if (TREE_CODE (op) == ADDR_EXPR) { tree base = TREE_OPERAND (op, 0); while (handled_component_p (base)) base = TREE_OPERAND (base, 0); if ((TREE_CODE (base) == VAR_DECL || TREE_CODE (base) == PARM_DECL || TREE_CODE (base) == RESULT_DECL) && !TREE_ADDRESSABLE (base)) { error ("address taken, but ADDRESSABLE bit not set"); err = true; } } if (e->dest != bb) { error ("wrong edge %d->%d for PHI argument", e->src->index, e->dest->index); err = true; } if (err) { fprintf (stderr, "PHI argument\n"); print_generic_stmt (stderr, op, TDF_VOPS); goto error; } } error: if (err) { fprintf (stderr, "for PHI node\n"); print_gimple_stmt (stderr, phi, 0, TDF_VOPS|TDF_MEMSYMS); } return err; } /* Verify common invariants in the SSA web. TODO: verify the variable annotations. */ void verify_ssa (bool check_modified_stmt) { size_t i; basic_block bb; basic_block *definition_block = XCNEWVEC (basic_block, num_ssa_names); ssa_op_iter iter; tree op; enum dom_state orig_dom_state = dom_info_state (CDI_DOMINATORS); bitmap names_defined_in_bb = BITMAP_ALLOC (NULL); gcc_assert (!need_ssa_update_p (cfun)); verify_stmts (); timevar_push (TV_TREE_SSA_VERIFY); /* Keep track of SSA names present in the IL. */ for (i = 1; i < num_ssa_names; i++) { tree name = ssa_name (i); if (name) { gimple stmt; TREE_VISITED (name) = 0; stmt = SSA_NAME_DEF_STMT (name); if (!gimple_nop_p (stmt)) { basic_block bb = gimple_bb (stmt); verify_def (bb, definition_block, name, stmt, !is_gimple_reg (name)); } } } calculate_dominance_info (CDI_DOMINATORS); /* Now verify all the uses and make sure they agree with the definitions found in the previous pass. */ FOR_EACH_BB (bb) { edge e; gimple phi; edge_iterator ei; gimple_stmt_iterator gsi; /* Make sure that all edges have a clear 'aux' field. */ FOR_EACH_EDGE (e, ei, bb->preds) { if (e->aux) { error ("AUX pointer initialized for edge %d->%d", e->src->index, e->dest->index); goto err; } } /* Verify the arguments for every PHI node in the block. */ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { phi = gsi_stmt (gsi); if (verify_phi_args (phi, bb, definition_block)) goto err; bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (gimple_phi_result (phi))); } /* Now verify all the uses and vuses in every statement of the block. */ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple stmt = gsi_stmt (gsi); use_operand_p use_p; bool has_err; if (check_modified_stmt && gimple_modified_p (stmt)) { error ("stmt (%p) marked modified after optimization pass: ", (void *)stmt); print_gimple_stmt (stderr, stmt, 0, TDF_VOPS); goto err; } if (is_gimple_assign (stmt) && TREE_CODE (gimple_assign_lhs (stmt)) != SSA_NAME) { tree lhs, base_address; lhs = gimple_assign_lhs (stmt); base_address = get_base_address (lhs); if (base_address && SSA_VAR_P (base_address) && !gimple_vdef (stmt) && optimize > 0) { error ("statement makes a memory store, but has no VDEFS"); print_gimple_stmt (stderr, stmt, 0, TDF_VOPS); goto err; } } else if (gimple_debug_bind_p (stmt) && !gimple_debug_bind_has_value_p (stmt)) continue; /* Verify the single virtual operand and its constraints. */ has_err = false; if (gimple_vdef (stmt)) { if (gimple_vdef_op (stmt) == NULL_DEF_OPERAND_P) { error ("statement has VDEF operand not in defs list"); has_err = true; } if (!gimple_vuse (stmt)) { error ("statement has VDEF but no VUSE operand"); has_err = true; } else if (SSA_NAME_VAR (gimple_vdef (stmt)) != SSA_NAME_VAR (gimple_vuse (stmt))) { error ("VDEF and VUSE do not use the same symbol"); has_err = true; } has_err |= verify_ssa_name (gimple_vdef (stmt), true); } if (gimple_vuse (stmt)) { if (gimple_vuse_op (stmt) == NULL_USE_OPERAND_P) { error ("statement has VUSE operand not in uses list"); has_err = true; } has_err |= verify_ssa_name (gimple_vuse (stmt), true); } if (has_err) { error ("in statement"); print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS); goto err; } FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE|SSA_OP_DEF) { if (verify_ssa_name (op, false)) { error ("in statement"); print_gimple_stmt (stderr, stmt, 0, TDF_VOPS|TDF_MEMSYMS); goto err; } } FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE|SSA_OP_VUSE) { op = USE_FROM_PTR (use_p); if (verify_use (bb, definition_block[SSA_NAME_VERSION (op)], use_p, stmt, false, names_defined_in_bb)) goto err; } FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS) { if (SSA_NAME_DEF_STMT (op) != stmt) { error ("SSA_NAME_DEF_STMT is wrong"); fprintf (stderr, "Expected definition statement:\n"); print_gimple_stmt (stderr, stmt, 4, TDF_VOPS); fprintf (stderr, "\nActual definition statement:\n"); print_gimple_stmt (stderr, SSA_NAME_DEF_STMT (op), 4, TDF_VOPS); goto err; } bitmap_set_bit (names_defined_in_bb, SSA_NAME_VERSION (op)); } } bitmap_clear (names_defined_in_bb); } free (definition_block); /* Restore the dominance information to its prior known state, so that we do not perturb the compiler's subsequent behavior. */ if (orig_dom_state == DOM_NONE) free_dominance_info (CDI_DOMINATORS); else set_dom_info_availability (CDI_DOMINATORS, orig_dom_state); BITMAP_FREE (names_defined_in_bb); timevar_pop (TV_TREE_SSA_VERIFY); return; err: internal_error ("verify_ssa failed"); } /* Return true if the uid in both int tree maps are equal. */ int int_tree_map_eq (const void *va, const void *vb) { const struct int_tree_map *a = (const struct int_tree_map *) va; const struct int_tree_map *b = (const struct int_tree_map *) vb; return (a->uid == b->uid); } /* Hash a UID in a int_tree_map. */ unsigned int int_tree_map_hash (const void *item) { return ((const struct int_tree_map *)item)->uid; } /* Return true if the DECL_UID in both trees are equal. */ int uid_decl_map_eq (const void *va, const void *vb) { const_tree a = (const_tree) va; const_tree b = (const_tree) vb; return (a->decl_minimal.uid == b->decl_minimal.uid); } /* Hash a tree in a uid_decl_map. */ unsigned int uid_decl_map_hash (const void *item) { return ((const_tree)item)->decl_minimal.uid; } /* Return true if the DECL_UID in both trees are equal. */ static int uid_ssaname_map_eq (const void *va, const void *vb) { const_tree a = (const_tree) va; const_tree b = (const_tree) vb; return (a->ssa_name.var->decl_minimal.uid == b->ssa_name.var->decl_minimal.uid); } /* Hash a tree in a uid_decl_map. */ static unsigned int uid_ssaname_map_hash (const void *item) { return ((const_tree)item)->ssa_name.var->decl_minimal.uid; } /* Initialize global DFA and SSA structures. */ void init_tree_ssa (struct function *fn) { fn->gimple_df = GGC_CNEW (struct gimple_df); fn->gimple_df->referenced_vars = htab_create_ggc (20, uid_decl_map_hash, uid_decl_map_eq, NULL); fn->gimple_df->default_defs = htab_create_ggc (20, uid_ssaname_map_hash, uid_ssaname_map_eq, NULL); pt_solution_reset (&fn->gimple_df->escaped); pt_solution_reset (&fn->gimple_df->callused); init_ssanames (fn, 0); init_phinodes (); } /* Deallocate memory associated with SSA data structures for FNDECL. */ void delete_tree_ssa (void) { referenced_var_iterator rvi; tree var; /* Remove annotations from every referenced local variable. */ FOR_EACH_REFERENCED_VAR (var, rvi) { if (is_global_var (var)) continue; if (var_ann (var)) { ggc_free (var_ann (var)); *DECL_VAR_ANN_PTR (var) = NULL; } } htab_delete (gimple_referenced_vars (cfun)); cfun->gimple_df->referenced_vars = NULL; fini_ssanames (); fini_phinodes (); /* We no longer maintain the SSA operand cache at this point. */ if (ssa_operands_active ()) fini_ssa_operands (); delete_alias_heapvars (); htab_delete (cfun->gimple_df->default_defs); cfun->gimple_df->default_defs = NULL; pt_solution_reset (&cfun->gimple_df->escaped); pt_solution_reset (&cfun->gimple_df->callused); if (cfun->gimple_df->decls_to_pointers != NULL) pointer_map_destroy (cfun->gimple_df->decls_to_pointers); cfun->gimple_df->decls_to_pointers = NULL; cfun->gimple_df->modified_noreturn_calls = NULL; cfun->gimple_df = NULL; /* We no longer need the edge variable maps. */ redirect_edge_var_map_destroy (); } /* Return true if the conversion from INNER_TYPE to OUTER_TYPE is a useless type conversion, otherwise return false. This function implicitly defines the middle-end type system. With the notion of 'a < b' meaning that useless_type_conversion_p (a, b) holds and 'a > b' meaning that useless_type_conversion_p (b, a) holds, the following invariants shall be fulfilled: 1) useless_type_conversion_p is transitive. If a < b and b < c then a < c. 2) useless_type_conversion_p is not symmetric. From a < b does not follow a > b. 3) Types define the available set of operations applicable to values. A type conversion is useless if the operations for the target type is a subset of the operations for the source type. For example casts to void* are useless, casts from void* are not (void* can't be dereferenced or offsetted, but copied, hence its set of operations is a strict subset of that of all other data pointer types). Casts to const T* are useless (can't be written to), casts from const T* to T* are not. */ bool useless_type_conversion_p (tree outer_type, tree inner_type) { /* Do the following before stripping toplevel qualifiers. */ if (POINTER_TYPE_P (inner_type) && POINTER_TYPE_P (outer_type)) { /* Do not lose casts between pointers to different address spaces. */ if (TYPE_ADDR_SPACE (TREE_TYPE (outer_type)) != TYPE_ADDR_SPACE (TREE_TYPE (inner_type))) return false; /* If the outer type is (void *) or a pointer to an incomplete record type or a pointer to an unprototyped function, then the conversion is not necessary. */ if (VOID_TYPE_P (TREE_TYPE (outer_type)) || ((TREE_CODE (TREE_TYPE (outer_type)) == FUNCTION_TYPE || TREE_CODE (TREE_TYPE (outer_type)) == METHOD_TYPE) && (TREE_CODE (TREE_TYPE (outer_type)) == TREE_CODE (TREE_TYPE (inner_type))) && !TYPE_ARG_TYPES (TREE_TYPE (outer_type)) && useless_type_conversion_p (TREE_TYPE (TREE_TYPE (outer_type)), TREE_TYPE (TREE_TYPE (inner_type))))) return true; /* Do not lose casts to restrict qualified pointers. */ if ((TYPE_RESTRICT (outer_type) != TYPE_RESTRICT (inner_type)) && TYPE_RESTRICT (outer_type)) return false; } /* From now on qualifiers on value types do not matter. */ inner_type = TYPE_MAIN_VARIANT (inner_type); outer_type = TYPE_MAIN_VARIANT (outer_type); if (inner_type == outer_type) return true; /* If we know the canonical types, compare them. */ if (TYPE_CANONICAL (inner_type) && TYPE_CANONICAL (inner_type) == TYPE_CANONICAL (outer_type)) return true; /* Changes in machine mode are never useless conversions unless we deal with aggregate types in which case we defer to later checks. */ if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type) && !AGGREGATE_TYPE_P (inner_type)) return false; /* If both the inner and outer types are integral types, then the conversion is not necessary if they have the same mode and signedness and precision, and both or neither are boolean. */ if (INTEGRAL_TYPE_P (inner_type) && INTEGRAL_TYPE_P (outer_type)) { /* Preserve changes in signedness or precision. */ if (TYPE_UNSIGNED (inner_type) != TYPE_UNSIGNED (outer_type) || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type)) return false; /* We don't need to preserve changes in the types minimum or maximum value in general as these do not generate code unless the types precisions are different. */ return true; } /* Scalar floating point types with the same mode are compatible. */ else if (SCALAR_FLOAT_TYPE_P (inner_type) && SCALAR_FLOAT_TYPE_P (outer_type)) return true; /* Fixed point types with the same mode are compatible. */ else if (FIXED_POINT_TYPE_P (inner_type) && FIXED_POINT_TYPE_P (outer_type)) return true; /* We need to take special care recursing to pointed-to types. */ else if (POINTER_TYPE_P (inner_type) && POINTER_TYPE_P (outer_type)) { /* Don't lose casts between pointers to volatile and non-volatile qualified types. Doing so would result in changing the semantics of later accesses. For function types the volatile qualifier is used to indicate noreturn functions. */ if (TREE_CODE (TREE_TYPE (outer_type)) != FUNCTION_TYPE && TREE_CODE (TREE_TYPE (outer_type)) != METHOD_TYPE && TREE_CODE (TREE_TYPE (inner_type)) != FUNCTION_TYPE && TREE_CODE (TREE_TYPE (inner_type)) != METHOD_TYPE && (TYPE_VOLATILE (TREE_TYPE (outer_type)) != TYPE_VOLATILE (TREE_TYPE (inner_type))) && TYPE_VOLATILE (TREE_TYPE (outer_type))) return false; /* We require explicit conversions from incomplete target types. */ if (!COMPLETE_TYPE_P (TREE_TYPE (inner_type)) && COMPLETE_TYPE_P (TREE_TYPE (outer_type))) return false; /* Do not lose casts between pointers that when dereferenced access memory with different alias sets. */ if (get_deref_alias_set (inner_type) != get_deref_alias_set (outer_type)) return false; /* We do not care for const qualification of the pointed-to types as const qualification has no semantic value to the middle-end. */ /* Otherwise pointers/references are equivalent if their pointed to types are effectively the same. We can strip qualifiers on pointed-to types for further comparison, which is done in the callee. Note we have to use true compatibility here because addresses are subject to propagation into dereferences and thus might get the original type exposed which is equivalent to a reverse conversion. */ return types_compatible_p (TREE_TYPE (outer_type), TREE_TYPE (inner_type)); } /* Recurse for complex types. */ else if (TREE_CODE (inner_type) == COMPLEX_TYPE && TREE_CODE (outer_type) == COMPLEX_TYPE) return useless_type_conversion_p (TREE_TYPE (outer_type), TREE_TYPE (inner_type)); /* Recurse for vector types with the same number of subparts. */ else if (TREE_CODE (inner_type) == VECTOR_TYPE && TREE_CODE (outer_type) == VECTOR_TYPE && TYPE_PRECISION (inner_type) == TYPE_PRECISION (outer_type)) return useless_type_conversion_p (TREE_TYPE (outer_type), TREE_TYPE (inner_type)); else if (TREE_CODE (inner_type) == ARRAY_TYPE && TREE_CODE (outer_type) == ARRAY_TYPE) { /* Preserve string attributes. */ if (TYPE_STRING_FLAG (inner_type) != TYPE_STRING_FLAG (outer_type)) return false; /* Conversions from array types with unknown extent to array types with known extent are not useless. */ if (!TYPE_DOMAIN (inner_type) && TYPE_DOMAIN (outer_type)) return false; /* Nor are conversions from array types with non-constant size to array types with constant size or to different size. */ if (TYPE_SIZE (outer_type) && TREE_CODE (TYPE_SIZE (outer_type)) == INTEGER_CST && (!TYPE_SIZE (inner_type) || TREE_CODE (TYPE_SIZE (inner_type)) != INTEGER_CST || !tree_int_cst_equal (TYPE_SIZE (outer_type), TYPE_SIZE (inner_type)))) return false; /* Check conversions between arrays with partially known extents. If the array min/max values are constant they have to match. Otherwise allow conversions to unknown and variable extents. In particular this declares conversions that may change the mode to BLKmode as useless. */ if (TYPE_DOMAIN (inner_type) && TYPE_DOMAIN (outer_type) && TYPE_DOMAIN (inner_type) != TYPE_DOMAIN (outer_type)) { tree inner_min = TYPE_MIN_VALUE (TYPE_DOMAIN (inner_type)); tree outer_min = TYPE_MIN_VALUE (TYPE_DOMAIN (outer_type)); tree inner_max = TYPE_MAX_VALUE (TYPE_DOMAIN (inner_type)); tree outer_max = TYPE_MAX_VALUE (TYPE_DOMAIN (outer_type)); /* After gimplification a variable min/max value carries no additional information compared to a NULL value. All that matters has been lowered to be part of the IL. */ if (inner_min && TREE_CODE (inner_min) != INTEGER_CST) inner_min = NULL_TREE; if (outer_min && TREE_CODE (outer_min) != INTEGER_CST) outer_min = NULL_TREE; if (inner_max && TREE_CODE (inner_max) != INTEGER_CST) inner_max = NULL_TREE; if (outer_max && TREE_CODE (outer_max) != INTEGER_CST) outer_max = NULL_TREE; /* Conversions NULL / variable <- cst are useless, but not the other way around. */ if (outer_min && (!inner_min || !tree_int_cst_equal (inner_min, outer_min))) return false; if (outer_max && (!inner_max || !tree_int_cst_equal (inner_max, outer_max))) return false; } /* Recurse on the element check. */ return useless_type_conversion_p (TREE_TYPE (outer_type), TREE_TYPE (inner_type)); } else if ((TREE_CODE (inner_type) == FUNCTION_TYPE || TREE_CODE (inner_type) == METHOD_TYPE) && TREE_CODE (inner_type) == TREE_CODE (outer_type)) { tree outer_parm, inner_parm; /* If the return types are not compatible bail out. */ if (!useless_type_conversion_p (TREE_TYPE (outer_type), TREE_TYPE (inner_type))) return false; /* Method types should belong to a compatible base class. */ if (TREE_CODE (inner_type) == METHOD_TYPE && !useless_type_conversion_p (TYPE_METHOD_BASETYPE (outer_type), TYPE_METHOD_BASETYPE (inner_type))) return false; /* A conversion to an unprototyped argument list is ok. */ if (!TYPE_ARG_TYPES (outer_type)) return true; /* If the unqualified argument types are compatible the conversion is useless. */ if (TYPE_ARG_TYPES (outer_type) == TYPE_ARG_TYPES (inner_type)) return true; for (outer_parm = TYPE_ARG_TYPES (outer_type), inner_parm = TYPE_ARG_TYPES (inner_type); outer_parm && inner_parm; outer_parm = TREE_CHAIN (outer_parm), inner_parm = TREE_CHAIN (inner_parm)) if (!useless_type_conversion_p (TYPE_MAIN_VARIANT (TREE_VALUE (outer_parm)), TYPE_MAIN_VARIANT (TREE_VALUE (inner_parm)))) return false; /* If there is a mismatch in the number of arguments the functions are not compatible. */ if (outer_parm || inner_parm) return false; /* Defer to the target if necessary. */ if (TYPE_ATTRIBUTES (inner_type) || TYPE_ATTRIBUTES (outer_type)) return targetm.comp_type_attributes (outer_type, inner_type) != 0; return true; } /* For aggregates we rely on TYPE_CANONICAL exclusively and require explicit conversions for types involving to be structurally compared types. */ else if (AGGREGATE_TYPE_P (inner_type) && TREE_CODE (inner_type) == TREE_CODE (outer_type)) return false; return false; } /* Return true if a conversion from either type of TYPE1 and TYPE2 to the other is not required. Otherwise return false. */ bool types_compatible_p (tree type1, tree type2) { return (type1 == type2 || (useless_type_conversion_p (type1, type2) && useless_type_conversion_p (type2, type1))); } /* Return true if EXPR is a useless type conversion, otherwise return false. */ bool tree_ssa_useless_type_conversion (tree expr) { /* If we have an assignment that merely uses a NOP_EXPR to change the top of the RHS to the type of the LHS and the type conversion is "safe", then strip away the type conversion so that we can enter LHS = RHS into the const_and_copies table. */ if (CONVERT_EXPR_P (expr) || TREE_CODE (expr) == VIEW_CONVERT_EXPR || TREE_CODE (expr) == NON_LVALUE_EXPR) return useless_type_conversion_p (TREE_TYPE (expr), TREE_TYPE (TREE_OPERAND (expr, 0))); return false; } /* Strip conversions from EXP according to tree_ssa_useless_type_conversion and return the resulting expression. */ tree tree_ssa_strip_useless_type_conversions (tree exp) { while (tree_ssa_useless_type_conversion (exp)) exp = TREE_OPERAND (exp, 0); return exp; } /* Internal helper for walk_use_def_chains. VAR, FN and DATA are as described in walk_use_def_chains. VISITED is a pointer set used to mark visited SSA_NAMEs to avoid infinite loops. We used to have a bitmap for this to just mark SSA versions we had visited. But non-sparse bitmaps are way too expensive, while sparse bitmaps may cause quadratic behavior. IS_DFS is true if the caller wants to perform a depth-first search when visiting PHI nodes. A DFS will visit each PHI argument and call FN after each one. Otherwise, all the arguments are visited first and then FN is called with each of the visited arguments in a separate pass. */ static bool walk_use_def_chains_1 (tree var, walk_use_def_chains_fn fn, void *data, struct pointer_set_t *visited, bool is_dfs) { gimple def_stmt; if (pointer_set_insert (visited, var)) return false; def_stmt = SSA_NAME_DEF_STMT (var); if (gimple_code (def_stmt) != GIMPLE_PHI) { /* If we reached the end of the use-def chain, call FN. */ return fn (var, def_stmt, data); } else { size_t i; /* When doing a breadth-first search, call FN before following the use-def links for each argument. */ if (!is_dfs) for (i = 0; i < gimple_phi_num_args (def_stmt); i++) if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data)) return true; /* Follow use-def links out of each PHI argument. */ for (i = 0; i < gimple_phi_num_args (def_stmt); i++) { tree arg = gimple_phi_arg_def (def_stmt, i); /* ARG may be NULL for newly introduced PHI nodes. */ if (arg && TREE_CODE (arg) == SSA_NAME && walk_use_def_chains_1 (arg, fn, data, visited, is_dfs)) return true; } /* When doing a depth-first search, call FN after following the use-def links for each argument. */ if (is_dfs) for (i = 0; i < gimple_phi_num_args (def_stmt); i++) if (fn (gimple_phi_arg_def (def_stmt, i), def_stmt, data)) return true; } return false; } /* Walk use-def chains starting at the SSA variable VAR. Call function FN at each reaching definition found. FN takes three arguments: VAR, its defining statement (DEF_STMT) and a generic pointer to whatever state information that FN may want to maintain (DATA). FN is able to stop the walk by returning true, otherwise in order to continue the walk, FN should return false. Note, that if DEF_STMT is a PHI node, the semantics are slightly different. The first argument to FN is no longer the original variable VAR, but the PHI argument currently being examined. If FN wants to get at VAR, it should call PHI_RESULT (PHI). If IS_DFS is true, this function will: 1- walk the use-def chains for all the PHI arguments, and, 2- call (*FN) (ARG, PHI, DATA) on all the PHI arguments. If IS_DFS is false, the two steps above are done in reverse order (i.e., a breadth-first search). */ void walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data, bool is_dfs) { gimple def_stmt; gcc_assert (TREE_CODE (var) == SSA_NAME); def_stmt = SSA_NAME_DEF_STMT (var); /* We only need to recurse if the reaching definition comes from a PHI node. */ if (gimple_code (def_stmt) != GIMPLE_PHI) (*fn) (var, def_stmt, data); else { struct pointer_set_t *visited = pointer_set_create (); walk_use_def_chains_1 (var, fn, data, visited, is_dfs); pointer_set_destroy (visited); } } /* Return true if T, an SSA_NAME, has an undefined value. */ bool ssa_undefined_value_p (tree t) { tree var = SSA_NAME_VAR (t); /* Parameters get their initial value from the function entry. */ if (TREE_CODE (var) == PARM_DECL) return false; /* Hard register variables get their initial value from the ether. */ if (TREE_CODE (var) == VAR_DECL && DECL_HARD_REGISTER (var)) return false; /* The value is undefined iff its definition statement is empty. */ return gimple_nop_p (SSA_NAME_DEF_STMT (t)); } /* Emit warnings for uninitialized variables. This is done in two passes. The first pass notices real uses of SSA names with undefined values. Such uses are unconditionally uninitialized, and we can be certain that such a use is a mistake. This pass is run before most optimizations, so that we catch as many as we can. The second pass follows PHI nodes to find uses that are potentially uninitialized. In this case we can't necessarily prove that the use is really uninitialized. This pass is run after most optimizations, so that we thread as many jumps and possible, and delete as much dead code as possible, in order to reduce false positives. We also look again for plain uninitialized variables, since optimization may have changed conditionally uninitialized to unconditionally uninitialized. */ /* Emit a warning for T, an SSA_NAME, being uninitialized. The exact warning text is in MSGID and LOCUS may contain a location or be null. */ static void warn_uninit (tree t, const char *gmsgid, void *data) { tree var = SSA_NAME_VAR (t); gimple context = (gimple) data; location_t location; expanded_location xloc, floc; if (!ssa_undefined_value_p (t)) return; /* TREE_NO_WARNING either means we already warned, or the front end wishes to suppress the warning. */ if (TREE_NO_WARNING (var)) return; /* Do not warn if it can be initialized outside this module. */ if (is_global_var (var)) return; location = (context != NULL && gimple_has_location (context)) ? gimple_location (context) : DECL_SOURCE_LOCATION (var); xloc = expand_location (location); floc = expand_location (DECL_SOURCE_LOCATION (cfun->decl)); if (warning_at (location, OPT_Wuninitialized, gmsgid, var)) { TREE_NO_WARNING (var) = 1; if (xloc.file != floc.file || xloc.line < floc.line || xloc.line > LOCATION_LINE (cfun->function_end_locus)) inform (DECL_SOURCE_LOCATION (var), "%qD was declared here", var); } } struct walk_data { gimple stmt; bool always_executed; bool warn_possibly_uninitialized; }; /* Called via walk_tree, look for SSA_NAMEs that have empty definitions and warn about them. */ static tree warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data_) { struct walk_stmt_info *wi = (struct walk_stmt_info *) data_; struct walk_data *data = (struct walk_data *) wi->info; tree t = *tp; /* We do not care about LHS. */ if (wi->is_lhs) { /* Except for operands of INDIRECT_REF. */ if (!INDIRECT_REF_P (t)) return NULL_TREE; t = TREE_OPERAND (t, 0); } switch (TREE_CODE (t)) { case ADDR_EXPR: /* Taking the address of an uninitialized variable does not count as using it. */ *walk_subtrees = 0; break; case VAR_DECL: { /* A VAR_DECL in the RHS of a gimple statement may mean that this variable is loaded from memory. */ use_operand_p vuse; tree op; /* If there is not gimple stmt, or alias information has not been computed, then we cannot check VUSE ops. */ if (data->stmt == NULL) return NULL_TREE; /* If the load happens as part of a call do not warn about it. */ if (is_gimple_call (data->stmt)) return NULL_TREE; vuse = gimple_vuse_op (data->stmt); if (vuse == NULL_USE_OPERAND_P) return NULL_TREE; op = USE_FROM_PTR (vuse); if (t != SSA_NAME_VAR (op) || !SSA_NAME_IS_DEFAULT_DEF (op)) return NULL_TREE; /* If this is a VUSE of t and it is the default definition, then warn about op. */ t = op; /* Fall through into SSA_NAME. */ } case SSA_NAME: /* We only do data flow with SSA_NAMEs, so that's all we can warn about. */ if (data->always_executed) warn_uninit (t, "%qD is used uninitialized in this function", data->stmt); else if (data->warn_possibly_uninitialized) warn_uninit (t, "%qD may be used uninitialized in this function", data->stmt); *walk_subtrees = 0; break; case REALPART_EXPR: case IMAGPART_EXPR: /* The total store transformation performed during gimplification creates uninitialized variable uses. If all is well, these will be optimized away, so don't warn now. */ if (TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME) *walk_subtrees = 0; break; default: if (IS_TYPE_OR_DECL_P (t)) *walk_subtrees = 0; break; } return NULL_TREE; } /* Look for inputs to PHI that are SSA_NAMEs that have empty definitions and warn about them. */ static void warn_uninitialized_phi (gimple phi) { size_t i, n = gimple_phi_num_args (phi); /* Don't look at memory tags. */ if (!is_gimple_reg (gimple_phi_result (phi))) return; for (i = 0; i < n; ++i) { tree op = gimple_phi_arg_def (phi, i); if (TREE_CODE (op) == SSA_NAME) warn_uninit (op, "%qD may be used uninitialized in this function", NULL); } } static unsigned int warn_uninitialized_vars (bool warn_possibly_uninitialized) { gimple_stmt_iterator gsi; basic_block bb; struct walk_data data; data.warn_possibly_uninitialized = warn_possibly_uninitialized; calculate_dominance_info (CDI_POST_DOMINATORS); FOR_EACH_BB (bb) { data.always_executed = dominated_by_p (CDI_POST_DOMINATORS, single_succ (ENTRY_BLOCK_PTR), bb); for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { struct walk_stmt_info wi; data.stmt = gsi_stmt (gsi); if (is_gimple_debug (data.stmt)) continue; memset (&wi, 0, sizeof (wi)); wi.info = &data; walk_gimple_op (gsi_stmt (gsi), warn_uninitialized_var, &wi); } } /* Post-dominator information can not be reliably updated. Free it after the use. */ free_dominance_info (CDI_POST_DOMINATORS); return 0; } static unsigned int execute_early_warn_uninitialized (void) { /* Currently, this pass runs always but execute_late_warn_uninitialized only runs with optimization. With optimization we want to warn about possible uninitialized as late as possible, thus don't do it here. However, without optimization we need to warn here about "may be uninitialized". */ warn_uninitialized_vars (/*warn_possibly_uninitialized=*/!optimize); return 0; } static unsigned int execute_late_warn_uninitialized (void) { basic_block bb; gimple_stmt_iterator gsi; /* Re-do the plain uninitialized variable check, as optimization may have straightened control flow. Do this first so that we don't accidentally get a "may be" warning when we'd have seen an "is" warning later. */ warn_uninitialized_vars (/*warn_possibly_uninitialized=*/1); FOR_EACH_BB (bb) for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) warn_uninitialized_phi (gsi_stmt (gsi)); return 0; } static bool gate_warn_uninitialized (void) { return warn_uninitialized != 0; } struct gimple_opt_pass pass_early_warn_uninitialized = { { GIMPLE_PASS, "*early_warn_uninitialized", /* name */ gate_warn_uninitialized, /* gate */ execute_early_warn_uninitialized, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_NONE, /* tv_id */ PROP_ssa, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ 0 /* todo_flags_finish */ } }; struct gimple_opt_pass pass_late_warn_uninitialized = { { GIMPLE_PASS, "*late_warn_uninitialized", /* name */ gate_warn_uninitialized, /* gate */ execute_late_warn_uninitialized, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_NONE, /* tv_id */ PROP_ssa, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ 0 /* todo_flags_finish */ } }; /* Compute TREE_ADDRESSABLE and DECL_GIMPLE_REG_P for local variables. */ void execute_update_addresses_taken (bool do_optimize) { tree var; referenced_var_iterator rvi; gimple_stmt_iterator gsi; basic_block bb; bitmap addresses_taken = BITMAP_ALLOC (NULL); bitmap not_reg_needs = BITMAP_ALLOC (NULL); bool update_vops = false; /* Collect into ADDRESSES_TAKEN all variables whose address is taken within the function body. */ FOR_EACH_BB (bb) { for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple stmt = gsi_stmt (gsi); enum gimple_code code = gimple_code (stmt); /* Note all addresses taken by the stmt. */ gimple_ior_addresses_taken (addresses_taken, stmt); /* If we have a call or an assignment, see if the lhs contains a local decl that requires not to be a gimple register. */ if (code == GIMPLE_ASSIGN || code == GIMPLE_CALL) { tree lhs = gimple_get_lhs (stmt); /* We may not rewrite TMR_SYMBOL to SSA. */ if (lhs && TREE_CODE (lhs) == TARGET_MEM_REF && TMR_SYMBOL (lhs)) bitmap_set_bit (not_reg_needs, DECL_UID (TMR_SYMBOL (lhs))); /* A plain decl does not need it set. */ else if (lhs && handled_component_p (lhs)) { var = get_base_address (lhs); if (DECL_P (var)) bitmap_set_bit (not_reg_needs, DECL_UID (var)); } } } for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { size_t i; gimple phi = gsi_stmt (gsi); for (i = 0; i < gimple_phi_num_args (phi); i++) { tree op = PHI_ARG_DEF (phi, i), var; if (TREE_CODE (op) == ADDR_EXPR && (var = get_base_address (TREE_OPERAND (op, 0))) != NULL && DECL_P (var)) bitmap_set_bit (addresses_taken, DECL_UID (var)); } } } /* When possible, clear ADDRESSABLE bit or set the REGISTER bit and mark variable for conversion into SSA. */ if (optimize && do_optimize) FOR_EACH_REFERENCED_VAR (var, rvi) { /* Global Variables, result decls cannot be changed. */ if (is_global_var (var) || TREE_CODE (var) == RESULT_DECL || bitmap_bit_p (addresses_taken, DECL_UID (var))) continue; if (TREE_ADDRESSABLE (var) /* Do not change TREE_ADDRESSABLE if we need to preserve var as a non-register. Otherwise we are confused and forget to add virtual operands for it. */ && (!is_gimple_reg_type (TREE_TYPE (var)) || !bitmap_bit_p (not_reg_needs, DECL_UID (var)))) { TREE_ADDRESSABLE (var) = 0; if (is_gimple_reg (var)) mark_sym_for_renaming (var); update_vops = true; if (dump_file) { fprintf (dump_file, "No longer having address taken "); print_generic_expr (dump_file, var, 0); fprintf (dump_file, "\n"); } } if (!DECL_GIMPLE_REG_P (var) && !bitmap_bit_p (not_reg_needs, DECL_UID (var)) && (TREE_CODE (TREE_TYPE (var)) == COMPLEX_TYPE || TREE_CODE (TREE_TYPE (var)) == VECTOR_TYPE) && !TREE_THIS_VOLATILE (var) && (TREE_CODE (var) != VAR_DECL || !DECL_HARD_REGISTER (var))) { DECL_GIMPLE_REG_P (var) = 1; mark_sym_for_renaming (var); update_vops = true; if (dump_file) { fprintf (dump_file, "Decl is now a gimple register "); print_generic_expr (dump_file, var, 0); fprintf (dump_file, "\n"); } } } /* Operand caches needs to be recomputed for operands referencing the updated variables. */ if (update_vops) { FOR_EACH_BB (bb) for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple stmt = gsi_stmt (gsi); if (gimple_references_memory_p (stmt) || is_gimple_debug (stmt)) update_stmt (stmt); } /* Update SSA form here, we are called as non-pass as well. */ update_ssa (TODO_update_ssa); } BITMAP_FREE (not_reg_needs); BITMAP_FREE (addresses_taken); } struct gimple_opt_pass pass_update_address_taken = { { GIMPLE_PASS, "addressables", /* name */ NULL, /* gate */ NULL, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_NONE, /* tv_id */ PROP_ssa, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_update_address_taken | TODO_dump_func /* todo_flags_finish */ } };
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