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/* Scalar Replacement of Aggregates (SRA) converts some structure references into scalar references, exposing them to the scalar optimizers. Copyright (C) 2003, 2004, 2005, 2006, 2007 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 "tree.h" /* These RTL headers are needed for basic-block.h. */ #include "rtl.h" #include "tm_p.h" #include "hard-reg-set.h" #include "basic-block.h" #include "diagnostic.h" #include "langhooks.h" #include "tree-inline.h" #include "tree-flow.h" #include "tree-gimple.h" #include "tree-dump.h" #include "tree-pass.h" #include "timevar.h" #include "flags.h" #include "bitmap.h" #include "obstack.h" #include "target.h" /* expr.h is needed for MOVE_RATIO. */ #include "expr.h" #include "params.h" /* This object of this pass is to replace a non-addressable aggregate with a set of independent variables. Most of the time, all of these variables will be scalars. But a secondary objective is to break up larger aggregates into smaller aggregates. In the process we may find that some bits of the larger aggregate can be deleted as unreferenced. This substitution is done globally. More localized substitutions would be the purvey of a load-store motion pass. The optimization proceeds in phases: (1) Identify variables that have types that are candidates for decomposition. (2) Scan the function looking for the ways these variables are used. In particular we're interested in the number of times a variable (or member) is needed as a complete unit, and the number of times a variable (or member) is copied. (3) Based on the usage profile, instantiate substitution variables. (4) Scan the function making replacements. */ /* The set of todo flags to return from tree_sra. */ static unsigned int todoflags; /* The set of aggregate variables that are candidates for scalarization. */ static bitmap sra_candidates; /* Set of scalarizable PARM_DECLs that need copy-in operations at the beginning of the function. */ static bitmap needs_copy_in; /* Sets of bit pairs that cache type decomposition and instantiation. */ static bitmap sra_type_decomp_cache; static bitmap sra_type_inst_cache; /* One of these structures is created for each candidate aggregate and each (accessed) member or group of members of such an aggregate. */ struct sra_elt { /* A tree of the elements. Used when we want to traverse everything. */ struct sra_elt *parent; struct sra_elt *groups; struct sra_elt *children; struct sra_elt *sibling; /* If this element is a root, then this is the VAR_DECL. If this is a sub-element, this is some token used to identify the reference. In the case of COMPONENT_REF, this is the FIELD_DECL. In the case of an ARRAY_REF, this is the (constant) index. In the case of an ARRAY_RANGE_REF, this is the (constant) RANGE_EXPR. In the case of a complex number, this is a zero or one. */ tree element; /* The type of the element. */ tree type; /* A VAR_DECL, for any sub-element we've decided to replace. */ tree replacement; /* The number of times the element is referenced as a whole. I.e. given "a.b.c", this would be incremented for C, but not for A or B. */ unsigned int n_uses; /* The number of times the element is copied to or from another scalarizable element. */ unsigned int n_copies; /* True if TYPE is scalar. */ bool is_scalar; /* True if this element is a group of members of its parent. */ bool is_group; /* True if we saw something about this element that prevents scalarization, such as non-constant indexing. */ bool cannot_scalarize; /* True if we've decided that structure-to-structure assignment should happen via memcpy and not per-element. */ bool use_block_copy; /* True if everything under this element has been marked TREE_NO_WARNING. */ bool all_no_warning; /* A flag for use with/after random access traversals. */ bool visited; }; #define IS_ELEMENT_FOR_GROUP(ELEMENT) (TREE_CODE (ELEMENT) == RANGE_EXPR) #define FOR_EACH_ACTUAL_CHILD(CHILD, ELT) \ for ((CHILD) = (ELT)->is_group \ ? next_child_for_group (NULL, (ELT)) \ : (ELT)->children; \ (CHILD); \ (CHILD) = (ELT)->is_group \ ? next_child_for_group ((CHILD), (ELT)) \ : (CHILD)->sibling) /* Helper function for above macro. Return next child in group. */ static struct sra_elt * next_child_for_group (struct sra_elt *child, struct sra_elt *group) { gcc_assert (group->is_group); /* Find the next child in the parent. */ if (child) child = child->sibling; else child = group->parent->children; /* Skip siblings that do not belong to the group. */ while (child) { tree g_elt = group->element; if (TREE_CODE (g_elt) == RANGE_EXPR) { if (!tree_int_cst_lt (child->element, TREE_OPERAND (g_elt, 0)) && !tree_int_cst_lt (TREE_OPERAND (g_elt, 1), child->element)) break; } else gcc_unreachable (); child = child->sibling; } return child; } /* Random access to the child of a parent is performed by hashing. This prevents quadratic behavior, and allows SRA to function reasonably on larger records. */ static htab_t sra_map; /* All structures are allocated out of the following obstack. */ static struct obstack sra_obstack; /* Debugging functions. */ static void dump_sra_elt_name (FILE *, struct sra_elt *); extern void debug_sra_elt_name (struct sra_elt *); /* Forward declarations. */ static tree generate_element_ref (struct sra_elt *); /* Return true if DECL is an SRA candidate. */ static bool is_sra_candidate_decl (tree decl) { return DECL_P (decl) && bitmap_bit_p (sra_candidates, DECL_UID (decl)); } /* Return true if TYPE is a scalar type. */ static bool is_sra_scalar_type (tree type) { enum tree_code code = TREE_CODE (type); return (code == INTEGER_TYPE || code == REAL_TYPE || code == VECTOR_TYPE || code == ENUMERAL_TYPE || code == BOOLEAN_TYPE || code == POINTER_TYPE || code == OFFSET_TYPE || code == REFERENCE_TYPE); } /* Return true if TYPE can be decomposed into a set of independent variables. Note that this doesn't imply that all elements of TYPE can be instantiated, just that if we decide to break up the type into separate pieces that it can be done. */ bool sra_type_can_be_decomposed_p (tree type) { unsigned int cache = TYPE_UID (TYPE_MAIN_VARIANT (type)) * 2; tree t; /* Avoid searching the same type twice. */ if (bitmap_bit_p (sra_type_decomp_cache, cache+0)) return true; if (bitmap_bit_p (sra_type_decomp_cache, cache+1)) return false; /* The type must have a definite nonzero size. */ if (TYPE_SIZE (type) == NULL || TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST || integer_zerop (TYPE_SIZE (type))) goto fail; /* The type must be a non-union aggregate. */ switch (TREE_CODE (type)) { case RECORD_TYPE: { bool saw_one_field = false; for (t = TYPE_FIELDS (type); t ; t = TREE_CHAIN (t)) if (TREE_CODE (t) == FIELD_DECL) { /* Reject incorrectly represented bit fields. */ if (DECL_BIT_FIELD (t) && (tree_low_cst (DECL_SIZE (t), 1) != TYPE_PRECISION (TREE_TYPE (t)))) goto fail; saw_one_field = true; } /* Record types must have at least one field. */ if (!saw_one_field) goto fail; } break; case ARRAY_TYPE: /* Array types must have a fixed lower and upper bound. */ t = TYPE_DOMAIN (type); if (t == NULL) goto fail; if (TYPE_MIN_VALUE (t) == NULL || !TREE_CONSTANT (TYPE_MIN_VALUE (t))) goto fail; if (TYPE_MAX_VALUE (t) == NULL || !TREE_CONSTANT (TYPE_MAX_VALUE (t))) goto fail; break; case COMPLEX_TYPE: break; default: goto fail; } bitmap_set_bit (sra_type_decomp_cache, cache+0); return true; fail: bitmap_set_bit (sra_type_decomp_cache, cache+1); return false; } /* Return true if DECL can be decomposed into a set of independent (though not necessarily scalar) variables. */ static bool decl_can_be_decomposed_p (tree var) { /* Early out for scalars. */ if (is_sra_scalar_type (TREE_TYPE (var))) return false; /* The variable must not be aliased. */ if (!is_gimple_non_addressable (var)) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Cannot scalarize variable "); print_generic_expr (dump_file, var, dump_flags); fprintf (dump_file, " because it must live in memory\n"); } return false; } /* The variable must not be volatile. */ if (TREE_THIS_VOLATILE (var)) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Cannot scalarize variable "); print_generic_expr (dump_file, var, dump_flags); fprintf (dump_file, " because it is declared volatile\n"); } return false; } /* We must be able to decompose the variable's type. */ if (!sra_type_can_be_decomposed_p (TREE_TYPE (var))) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Cannot scalarize variable "); print_generic_expr (dump_file, var, dump_flags); fprintf (dump_file, " because its type cannot be decomposed\n"); } return false; } return true; } /* Return true if TYPE can be *completely* decomposed into scalars. */ static bool type_can_instantiate_all_elements (tree type) { if (is_sra_scalar_type (type)) return true; if (!sra_type_can_be_decomposed_p (type)) return false; switch (TREE_CODE (type)) { case RECORD_TYPE: { unsigned int cache = TYPE_UID (TYPE_MAIN_VARIANT (type)) * 2; tree f; if (bitmap_bit_p (sra_type_inst_cache, cache+0)) return true; if (bitmap_bit_p (sra_type_inst_cache, cache+1)) return false; for (f = TYPE_FIELDS (type); f ; f = TREE_CHAIN (f)) if (TREE_CODE (f) == FIELD_DECL) { if (!type_can_instantiate_all_elements (TREE_TYPE (f))) { bitmap_set_bit (sra_type_inst_cache, cache+1); return false; } } bitmap_set_bit (sra_type_inst_cache, cache+0); return true; } case ARRAY_TYPE: return type_can_instantiate_all_elements (TREE_TYPE (type)); case COMPLEX_TYPE: return true; default: gcc_unreachable (); } } /* Test whether ELT or some sub-element cannot be scalarized. */ static bool can_completely_scalarize_p (struct sra_elt *elt) { struct sra_elt *c; if (elt->cannot_scalarize) return false; for (c = elt->children; c; c = c->sibling) if (!can_completely_scalarize_p (c)) return false; for (c = elt->groups; c; c = c->sibling) if (!can_completely_scalarize_p (c)) return false; return true; } /* A simplified tree hashing algorithm that only handles the types of trees we expect to find in sra_elt->element. */ static hashval_t sra_hash_tree (tree t) { hashval_t h; switch (TREE_CODE (t)) { case VAR_DECL: case PARM_DECL: case RESULT_DECL: h = DECL_UID (t); break; case INTEGER_CST: h = TREE_INT_CST_LOW (t) ^ TREE_INT_CST_HIGH (t); break; case RANGE_EXPR: h = iterative_hash_expr (TREE_OPERAND (t, 0), 0); h = iterative_hash_expr (TREE_OPERAND (t, 1), h); break; case FIELD_DECL: /* We can have types that are compatible, but have different member lists, so we can't hash fields by ID. Use offsets instead. */ h = iterative_hash_expr (DECL_FIELD_OFFSET (t), 0); h = iterative_hash_expr (DECL_FIELD_BIT_OFFSET (t), h); break; default: gcc_unreachable (); } return h; } /* Hash function for type SRA_PAIR. */ static hashval_t sra_elt_hash (const void *x) { const struct sra_elt *e = x; const struct sra_elt *p; hashval_t h; h = sra_hash_tree (e->element); /* Take into account everything back up the chain. Given that chain lengths are rarely very long, this should be acceptable. If we truly identify this as a performance problem, it should work to hash the pointer value "e->parent". */ for (p = e->parent; p ; p = p->parent) h = (h * 65521) ^ sra_hash_tree (p->element); return h; } /* Equality function for type SRA_PAIR. */ static int sra_elt_eq (const void *x, const void *y) { const struct sra_elt *a = x; const struct sra_elt *b = y; tree ae, be; if (a->parent != b->parent) return false; ae = a->element; be = b->element; if (ae == be) return true; if (TREE_CODE (ae) != TREE_CODE (be)) return false; switch (TREE_CODE (ae)) { case VAR_DECL: case PARM_DECL: case RESULT_DECL: /* These are all pointer unique. */ return false; case INTEGER_CST: /* Integers are not pointer unique, so compare their values. */ return tree_int_cst_equal (ae, be); case RANGE_EXPR: return tree_int_cst_equal (TREE_OPERAND (ae, 0), TREE_OPERAND (be, 0)) && tree_int_cst_equal (TREE_OPERAND (ae, 1), TREE_OPERAND (be, 1)); case FIELD_DECL: /* Fields are unique within a record, but not between compatible records. */ if (DECL_FIELD_CONTEXT (ae) == DECL_FIELD_CONTEXT (be)) return false; return fields_compatible_p (ae, be); default: gcc_unreachable (); } } /* Create or return the SRA_ELT structure for CHILD in PARENT. PARENT may be null, in which case CHILD must be a DECL. */ static struct sra_elt * lookup_element (struct sra_elt *parent, tree child, tree type, enum insert_option insert) { struct sra_elt dummy; struct sra_elt **slot; struct sra_elt *elt; if (parent) dummy.parent = parent->is_group ? parent->parent : parent; else dummy.parent = NULL; dummy.element = child; slot = (struct sra_elt **) htab_find_slot (sra_map, &dummy, insert); if (!slot && insert == NO_INSERT) return NULL; elt = *slot; if (!elt && insert == INSERT) { *slot = elt = obstack_alloc (&sra_obstack, sizeof (*elt)); memset (elt, 0, sizeof (*elt)); elt->parent = parent; elt->element = child; elt->type = type; elt->is_scalar = is_sra_scalar_type (type); if (parent) { if (IS_ELEMENT_FOR_GROUP (elt->element)) { elt->is_group = true; elt->sibling = parent->groups; parent->groups = elt; } else { elt->sibling = parent->children; parent->children = elt; } } /* If this is a parameter, then if we want to scalarize, we have one copy from the true function parameter. Count it now. */ if (TREE_CODE (child) == PARM_DECL) { elt->n_copies = 1; bitmap_set_bit (needs_copy_in, DECL_UID (child)); } } return elt; } /* Create or return the SRA_ELT structure for EXPR if the expression refers to a scalarizable variable. */ static struct sra_elt * maybe_lookup_element_for_expr (tree expr) { struct sra_elt *elt; tree child; switch (TREE_CODE (expr)) { case VAR_DECL: case PARM_DECL: case RESULT_DECL: if (is_sra_candidate_decl (expr)) return lookup_element (NULL, expr, TREE_TYPE (expr), INSERT); return NULL; case ARRAY_REF: /* We can't scalarize variable array indices. */ if (in_array_bounds_p (expr)) child = TREE_OPERAND (expr, 1); else return NULL; break; case ARRAY_RANGE_REF: /* We can't scalarize variable array indices. */ if (range_in_array_bounds_p (expr)) { tree domain = TYPE_DOMAIN (TREE_TYPE (expr)); child = build2 (RANGE_EXPR, integer_type_node, TYPE_MIN_VALUE (domain), TYPE_MAX_VALUE (domain)); } else return NULL; break; case COMPONENT_REF: /* Don't look through unions. */ if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) != RECORD_TYPE) return NULL; child = TREE_OPERAND (expr, 1); break; case REALPART_EXPR: child = integer_zero_node; break; case IMAGPART_EXPR: child = integer_one_node; break; default: return NULL; } elt = maybe_lookup_element_for_expr (TREE_OPERAND (expr, 0)); if (elt) return lookup_element (elt, child, TREE_TYPE (expr), INSERT); return NULL; } /* Functions to walk just enough of the tree to see all scalarizable references, and categorize them. */ /* A set of callbacks for phases 2 and 4. They'll be invoked for the various kinds of references seen. In all cases, *BSI is an iterator pointing to the statement being processed. */ struct sra_walk_fns { /* Invoked when ELT is required as a unit. Note that ELT might refer to a leaf node, in which case this is a simple scalar reference. *EXPR_P points to the location of the expression. IS_OUTPUT is true if this is a left-hand-side reference. USE_ALL is true if we saw something we couldn't quite identify and had to force the use of the entire object. */ void (*use) (struct sra_elt *elt, tree *expr_p, block_stmt_iterator *bsi, bool is_output, bool use_all); /* Invoked when we have a copy between two scalarizable references. */ void (*copy) (struct sra_elt *lhs_elt, struct sra_elt *rhs_elt, block_stmt_iterator *bsi); /* Invoked when ELT is initialized from a constant. VALUE may be NULL, in which case it should be treated as an empty CONSTRUCTOR. */ void (*init) (struct sra_elt *elt, tree value, block_stmt_iterator *bsi); /* Invoked when we have a copy between one scalarizable reference ELT and one non-scalarizable reference OTHER without side-effects. IS_OUTPUT is true if ELT is on the left-hand side. */ void (*ldst) (struct sra_elt *elt, tree other, block_stmt_iterator *bsi, bool is_output); /* True during phase 2, false during phase 4. */ /* ??? This is a hack. */ bool initial_scan; }; #ifdef ENABLE_CHECKING /* Invoked via walk_tree, if *TP contains a candidate decl, return it. */ static tree sra_find_candidate_decl (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED) { tree t = *tp; enum tree_code code = TREE_CODE (t); if (code == VAR_DECL || code == PARM_DECL || code == RESULT_DECL) { *walk_subtrees = 0; if (is_sra_candidate_decl (t)) return t; } else if (TYPE_P (t)) *walk_subtrees = 0; return NULL; } #endif /* Walk most expressions looking for a scalarizable aggregate. If we find one, invoke FNS->USE. */ static void sra_walk_expr (tree *expr_p, block_stmt_iterator *bsi, bool is_output, const struct sra_walk_fns *fns) { tree expr = *expr_p; tree inner = expr; bool disable_scalarization = false; bool use_all_p = false; /* We're looking to collect a reference expression between EXPR and INNER, such that INNER is a scalarizable decl and all other nodes through EXPR are references that we can scalarize. If we come across something that we can't scalarize, we reset EXPR. This has the effect of making it appear that we're referring to the larger expression as a whole. */ while (1) switch (TREE_CODE (inner)) { case VAR_DECL: case PARM_DECL: case RESULT_DECL: /* If there is a scalarizable decl at the bottom, then process it. */ if (is_sra_candidate_decl (inner)) { struct sra_elt *elt = maybe_lookup_element_for_expr (expr); if (disable_scalarization) elt->cannot_scalarize = true; else fns->use (elt, expr_p, bsi, is_output, use_all_p); } return; case ARRAY_REF: /* Non-constant index means any member may be accessed. Prevent the expression from being scalarized. If we were to treat this as a reference to the whole array, we can wind up with a single dynamic index reference inside a loop being overridden by several constant index references during loop setup. It's possible that this could be avoided by using dynamic usage counts based on BB trip counts (based on loop analysis or profiling), but that hardly seems worth the effort. */ /* ??? Hack. Figure out how to push this into the scan routines without duplicating too much code. */ if (!in_array_bounds_p (inner)) { disable_scalarization = true; goto use_all; } /* ??? Are we assured that non-constant bounds and stride will have the same value everywhere? I don't think Fortran will... */ if (TREE_OPERAND (inner, 2) || TREE_OPERAND (inner, 3)) goto use_all; inner = TREE_OPERAND (inner, 0); break; case ARRAY_RANGE_REF: if (!range_in_array_bounds_p (inner)) { disable_scalarization = true; goto use_all; } /* ??? See above non-constant bounds and stride . */ if (TREE_OPERAND (inner, 2) || TREE_OPERAND (inner, 3)) goto use_all; inner = TREE_OPERAND (inner, 0); break; case COMPONENT_REF: /* A reference to a union member constitutes a reference to the entire union. */ if (TREE_CODE (TREE_TYPE (TREE_OPERAND (inner, 0))) != RECORD_TYPE) goto use_all; /* ??? See above re non-constant stride. */ if (TREE_OPERAND (inner, 2)) goto use_all; inner = TREE_OPERAND (inner, 0); break; case REALPART_EXPR: case IMAGPART_EXPR: inner = TREE_OPERAND (inner, 0); break; case BIT_FIELD_REF: /* A bit field reference (access to *multiple* fields simultaneously) is not currently scalarized. Consider this an access to the complete outer element, to which walk_tree will bring us next. */ goto use_all; case VIEW_CONVERT_EXPR: case NOP_EXPR: /* Similarly, a view/nop explicitly wants to look at an object in a type other than the one we've scalarized. */ goto use_all; case WITH_SIZE_EXPR: /* This is a transparent wrapper. The entire inner expression really is being used. */ goto use_all; use_all: expr_p = &TREE_OPERAND (inner, 0); inner = expr = *expr_p; use_all_p = true; break; default: #ifdef ENABLE_CHECKING /* Validate that we're not missing any references. */ gcc_assert (!walk_tree (&inner, sra_find_candidate_decl, NULL, NULL)); #endif return; } } /* Walk a TREE_LIST of values looking for scalarizable aggregates. If we find one, invoke FNS->USE. */ static void sra_walk_tree_list (tree list, block_stmt_iterator *bsi, bool is_output, const struct sra_walk_fns *fns) { tree op; for (op = list; op ; op = TREE_CHAIN (op)) sra_walk_expr (&TREE_VALUE (op), bsi, is_output, fns); } /* Walk the arguments of a CALL_EXPR looking for scalarizable aggregates. If we find one, invoke FNS->USE. */ static void sra_walk_call_expr (tree expr, block_stmt_iterator *bsi, const struct sra_walk_fns *fns) { sra_walk_tree_list (TREE_OPERAND (expr, 1), bsi, false, fns); } /* Walk the inputs and outputs of an ASM_EXPR looking for scalarizable aggregates. If we find one, invoke FNS->USE. */ static void sra_walk_asm_expr (tree expr, block_stmt_iterator *bsi, const struct sra_walk_fns *fns) { sra_walk_tree_list (ASM_INPUTS (expr), bsi, false, fns); sra_walk_tree_list (ASM_OUTPUTS (expr), bsi, true, fns); } /* Walk a MODIFY_EXPR and categorize the assignment appropriately. */ static void sra_walk_modify_expr (tree expr, block_stmt_iterator *bsi, const struct sra_walk_fns *fns) { struct sra_elt *lhs_elt, *rhs_elt; tree lhs, rhs; lhs = TREE_OPERAND (expr, 0); rhs = TREE_OPERAND (expr, 1); lhs_elt = maybe_lookup_element_for_expr (lhs); rhs_elt = maybe_lookup_element_for_expr (rhs); /* If both sides are scalarizable, this is a COPY operation. */ if (lhs_elt && rhs_elt) { fns->copy (lhs_elt, rhs_elt, bsi); return; } /* If the RHS is scalarizable, handle it. There are only two cases. */ if (rhs_elt) { if (!rhs_elt->is_scalar && !TREE_SIDE_EFFECTS (lhs)) fns->ldst (rhs_elt, lhs, bsi, false); else fns->use (rhs_elt, &TREE_OPERAND (expr, 1), bsi, false, false); } /* If it isn't scalarizable, there may be scalarizable variables within, so check for a call or else walk the RHS to see if we need to do any copy-in operations. We need to do it before the LHS is scalarized so that the statements get inserted in the proper place, before any copy-out operations. */ else { tree call = get_call_expr_in (rhs); if (call) sra_walk_call_expr (call, bsi, fns); else sra_walk_expr (&TREE_OPERAND (expr, 1), bsi, false, fns); } /* Likewise, handle the LHS being scalarizable. We have cases similar to those above, but also want to handle RHS being constant. */ if (lhs_elt) { /* If this is an assignment from a constant, or constructor, then we have access to all of the elements individually. Invoke INIT. */ if (TREE_CODE (rhs) == COMPLEX_EXPR || TREE_CODE (rhs) == COMPLEX_CST || TREE_CODE (rhs) == CONSTRUCTOR) fns->init (lhs_elt, rhs, bsi); /* If this is an assignment from read-only memory, treat this as if we'd been passed the constructor directly. Invoke INIT. */ else if (TREE_CODE (rhs) == VAR_DECL && TREE_STATIC (rhs) && TREE_READONLY (rhs) && targetm.binds_local_p (rhs)) fns->init (lhs_elt, DECL_INITIAL (rhs), bsi); /* If this is a copy from a non-scalarizable lvalue, invoke LDST. The lvalue requirement prevents us from trying to directly scalarize the result of a function call. Which would result in trying to call the function multiple times, and other evil things. */ else if (!lhs_elt->is_scalar && !TREE_SIDE_EFFECTS (rhs) && is_gimple_addressable (rhs)) fns->ldst (lhs_elt, rhs, bsi, true); /* Otherwise we're being used in some context that requires the aggregate to be seen as a whole. Invoke USE. */ else fns->use (lhs_elt, &TREE_OPERAND (expr, 0), bsi, true, false); } /* Similarly to above, LHS_ELT being null only means that the LHS as a whole is not a scalarizable reference. There may be occurrences of scalarizable variables within, which implies a USE. */ else sra_walk_expr (&TREE_OPERAND (expr, 0), bsi, true, fns); } /* Entry point to the walk functions. Search the entire function, invoking the callbacks in FNS on each of the references to scalarizable variables. */ static void sra_walk_function (const struct sra_walk_fns *fns) { basic_block bb; block_stmt_iterator si, ni; /* ??? Phase 4 could derive some benefit to walking the function in dominator tree order. */ FOR_EACH_BB (bb) for (si = bsi_start (bb); !bsi_end_p (si); si = ni) { tree stmt, t; stmt_ann_t ann; stmt = bsi_stmt (si); ann = stmt_ann (stmt); ni = si; bsi_next (&ni); /* If the statement has no virtual operands, then it doesn't make any structure references that we care about. */ if (ZERO_SSA_OPERANDS (stmt, (SSA_OP_VIRTUAL_DEFS | SSA_OP_VUSE))) continue; switch (TREE_CODE (stmt)) { case RETURN_EXPR: /* If we have "return <retval>" then the return value is already exposed for our pleasure. Walk it as a USE to force all the components back in place for the return. If we have an embedded assignment, then <retval> is of a type that gets returned in registers in this ABI, and we do not wish to extend their lifetimes. Treat this as a USE of the variable on the RHS of this assignment. */ t = TREE_OPERAND (stmt, 0); if (TREE_CODE (t) == MODIFY_EXPR) sra_walk_expr (&TREE_OPERAND (t, 1), &si, false, fns); else sra_walk_expr (&TREE_OPERAND (stmt, 0), &si, false, fns); break; case MODIFY_EXPR: sra_walk_modify_expr (stmt, &si, fns); break; case CALL_EXPR: sra_walk_call_expr (stmt, &si, fns); break; case ASM_EXPR: sra_walk_asm_expr (stmt, &si, fns); break; default: break; } } } /* Phase One: Scan all referenced variables in the program looking for structures that could be decomposed. */ static bool find_candidates_for_sra (void) { bool any_set = false; tree var; referenced_var_iterator rvi; FOR_EACH_REFERENCED_VAR (var, rvi) { if (decl_can_be_decomposed_p (var)) { bitmap_set_bit (sra_candidates, DECL_UID (var)); any_set = true; } } return any_set; } /* Phase Two: Scan all references to scalarizable variables. Count the number of times they are used or copied respectively. */ /* Callbacks to fill in SRA_WALK_FNS. Everything but USE is considered a copy, because we can decompose the reference such that the sub-elements needn't be contiguous. */ static void scan_use (struct sra_elt *elt, tree *expr_p ATTRIBUTE_UNUSED, block_stmt_iterator *bsi ATTRIBUTE_UNUSED, bool is_output ATTRIBUTE_UNUSED, bool use_all ATTRIBUTE_UNUSED) { elt->n_uses += 1; } static void scan_copy (struct sra_elt *lhs_elt, struct sra_elt *rhs_elt, block_stmt_iterator *bsi ATTRIBUTE_UNUSED) { lhs_elt->n_copies += 1; rhs_elt->n_copies += 1; } static void scan_init (struct sra_elt *lhs_elt, tree rhs ATTRIBUTE_UNUSED, block_stmt_iterator *bsi ATTRIBUTE_UNUSED) { lhs_elt->n_copies += 1; } static void scan_ldst (struct sra_elt *elt, tree other ATTRIBUTE_UNUSED, block_stmt_iterator *bsi ATTRIBUTE_UNUSED, bool is_output ATTRIBUTE_UNUSED) { elt->n_copies += 1; } /* Dump the values we collected during the scanning phase. */ static void scan_dump (struct sra_elt *elt) { struct sra_elt *c; dump_sra_elt_name (dump_file, elt); fprintf (dump_file, ": n_uses=%u n_copies=%u\n", elt->n_uses, elt->n_copies); for (c = elt->children; c ; c = c->sibling) scan_dump (c); for (c = elt->groups; c ; c = c->sibling) scan_dump (c); } /* Entry point to phase 2. Scan the entire function, building up scalarization data structures, recording copies and uses. */ static void scan_function (void) { static const struct sra_walk_fns fns = { scan_use, scan_copy, scan_init, scan_ldst, true }; bitmap_iterator bi; sra_walk_function (&fns); if (dump_file && (dump_flags & TDF_DETAILS)) { unsigned i; fputs ("\nScan results:\n", dump_file); EXECUTE_IF_SET_IN_BITMAP (sra_candidates, 0, i, bi) { tree var = referenced_var (i); struct sra_elt *elt = lookup_element (NULL, var, NULL, NO_INSERT); if (elt) scan_dump (elt); } fputc ('\n', dump_file); } } /* Phase Three: Make decisions about which variables to scalarize, if any. All elements to be scalarized have replacement variables made for them. */ /* A subroutine of build_element_name. Recursively build the element name on the obstack. */ static void build_element_name_1 (struct sra_elt *elt) { tree t; char buffer[32]; if (elt->parent) { build_element_name_1 (elt->parent); obstack_1grow (&sra_obstack, '$'); if (TREE_CODE (elt->parent->type) == COMPLEX_TYPE) { if (elt->element == integer_zero_node) obstack_grow (&sra_obstack, "real", 4); else obstack_grow (&sra_obstack, "imag", 4); return; } } t = elt->element; if (TREE_CODE (t) == INTEGER_CST) { /* ??? Eh. Don't bother doing double-wide printing. */ sprintf (buffer, HOST_WIDE_INT_PRINT_DEC, TREE_INT_CST_LOW (t)); obstack_grow (&sra_obstack, buffer, strlen (buffer)); } else { tree name = DECL_NAME (t); if (name) obstack_grow (&sra_obstack, IDENTIFIER_POINTER (name), IDENTIFIER_LENGTH (name)); else { sprintf (buffer, "D%u", DECL_UID (t)); obstack_grow (&sra_obstack, buffer, strlen (buffer)); } } } /* Construct a pretty variable name for an element's replacement variable. The name is built on the obstack. */ static char * build_element_name (struct sra_elt *elt) { build_element_name_1 (elt); obstack_1grow (&sra_obstack, '\0'); return XOBFINISH (&sra_obstack, char *); } /* Instantiate an element as an independent variable. */ static void instantiate_element (struct sra_elt *elt) { struct sra_elt *base_elt; tree var, base; for (base_elt = elt; base_elt->parent; base_elt = base_elt->parent) continue; base = base_elt->element; elt->replacement = var = make_rename_temp (elt->type, "SR"); DECL_SOURCE_LOCATION (var) = DECL_SOURCE_LOCATION (base); DECL_ARTIFICIAL (var) = 1; if (TREE_THIS_VOLATILE (elt->type)) { TREE_THIS_VOLATILE (var) = 1; TREE_SIDE_EFFECTS (var) = 1; } if (DECL_NAME (base) && !DECL_IGNORED_P (base)) { char *pretty_name = build_element_name (elt); DECL_NAME (var) = get_identifier (pretty_name); obstack_free (&sra_obstack, pretty_name); SET_DECL_DEBUG_EXPR (var, generate_element_ref (elt)); DECL_DEBUG_EXPR_IS_FROM (var) = 1; DECL_IGNORED_P (var) = 0; TREE_NO_WARNING (var) = TREE_NO_WARNING (base); } else { DECL_IGNORED_P (var) = 1; /* ??? We can't generate any warning that would be meaningful. */ TREE_NO_WARNING (var) = 1; } if (dump_file) { fputs (" ", dump_file); dump_sra_elt_name (dump_file, elt); fputs (" -> ", dump_file); print_generic_expr (dump_file, var, dump_flags); fputc ('\n', dump_file); } } /* Make one pass across an element tree deciding whether or not it's profitable to instantiate individual leaf scalars. PARENT_USES and PARENT_COPIES are the sum of the N_USES and N_COPIES fields all the way up the tree. */ static void decide_instantiation_1 (struct sra_elt *elt, unsigned int parent_uses, unsigned int parent_copies) { if (dump_file && !elt->parent) { fputs ("Initial instantiation for ", dump_file); dump_sra_elt_name (dump_file, elt); fputc ('\n', dump_file); } if (elt->cannot_scalarize) return; if (elt->is_scalar) { /* The decision is simple: instantiate if we're used more frequently than the parent needs to be seen as a complete unit. */ if (elt->n_uses + elt->n_copies + parent_copies > parent_uses) instantiate_element (elt); } else { struct sra_elt *c, *group; unsigned int this_uses = elt->n_uses + parent_uses; unsigned int this_copies = elt->n_copies + parent_copies; /* Consider groups of sub-elements as weighing in favour of instantiation whatever their size. */ for (group = elt->groups; group ; group = group->sibling) FOR_EACH_ACTUAL_CHILD (c, group) { c->n_uses += group->n_uses; c->n_copies += group->n_copies; } for (c = elt->children; c ; c = c->sibling) decide_instantiation_1 (c, this_uses, this_copies); } } /* Compute the size and number of all instantiated elements below ELT. We will only care about this if the size of the complete structure fits in a HOST_WIDE_INT, so we don't have to worry about overflow. */ static unsigned int sum_instantiated_sizes (struct sra_elt *elt, unsigned HOST_WIDE_INT *sizep) { if (elt->replacement) { *sizep += TREE_INT_CST_LOW (TYPE_SIZE_UNIT (elt->type)); return 1; } else { struct sra_elt *c; unsigned int count = 0; for (c = elt->children; c ; c = c->sibling) count += sum_instantiated_sizes (c, sizep); return count; } } /* Instantiate fields in ELT->TYPE that are not currently present as children of ELT. */ static void instantiate_missing_elements (struct sra_elt *elt); static void instantiate_missing_elements_1 (struct sra_elt *elt, tree child, tree type) { struct sra_elt *sub = lookup_element (elt, child, type, INSERT); if (sub->is_scalar) { if (sub->replacement == NULL) instantiate_element (sub); } else instantiate_missing_elements (sub); } static void instantiate_missing_elements (struct sra_elt *elt) { tree type = elt->type; switch (TREE_CODE (type)) { case RECORD_TYPE: { tree f; for (f = TYPE_FIELDS (type); f ; f = TREE_CHAIN (f)) if (TREE_CODE (f) == FIELD_DECL) { tree field_type = TREE_TYPE (f); /* canonicalize_component_ref() unwidens some bit-field types (not marked as DECL_BIT_FIELD in C++), so we must do the same, lest we may introduce type mismatches. */ if (INTEGRAL_TYPE_P (field_type) && DECL_MODE (f) != TYPE_MODE (field_type)) field_type = TREE_TYPE (get_unwidened (build3 (COMPONENT_REF, field_type, elt->element, f, NULL_TREE), NULL_TREE)); instantiate_missing_elements_1 (elt, f, field_type); } break; } case ARRAY_TYPE: { tree i, max, subtype; i = TYPE_MIN_VALUE (TYPE_DOMAIN (type)); max = TYPE_MAX_VALUE (TYPE_DOMAIN (type)); subtype = TREE_TYPE (type); while (1) { instantiate_missing_elements_1 (elt, i, subtype); if (tree_int_cst_equal (i, max)) break; i = int_const_binop (PLUS_EXPR, i, integer_one_node, true); } break; } case COMPLEX_TYPE: type = TREE_TYPE (type); instantiate_missing_elements_1 (elt, integer_zero_node, type); instantiate_missing_elements_1 (elt, integer_one_node, type); break; default: gcc_unreachable (); } } /* Make one pass across an element tree deciding whether to perform block or element copies. If we decide on element copies, instantiate all elements. Return true if there are any instantiated sub-elements. */ static bool decide_block_copy (struct sra_elt *elt) { struct sra_elt *c; bool any_inst; /* We shouldn't be invoked on groups of sub-elements as they must behave like their parent as far as block copy is concerned. */ gcc_assert (!elt->is_group); /* If scalarization is disabled, respect it. */ if (elt->cannot_scalarize) { elt->use_block_copy = 1; if (dump_file) { fputs ("Scalarization disabled for ", dump_file); dump_sra_elt_name (dump_file, elt); fputc ('\n', dump_file); } /* Disable scalarization of sub-elements */ for (c = elt->children; c; c = c->sibling) { c->cannot_scalarize = 1; decide_block_copy (c); } /* Groups behave like their parent. */ for (c = elt->groups; c; c = c->sibling) { c->cannot_scalarize = 1; c->use_block_copy = 1; } return false; } /* Don't decide if we've no uses. */ if (elt->n_uses == 0 && elt->n_copies == 0) ; else if (!elt->is_scalar) { tree size_tree = TYPE_SIZE_UNIT (elt->type); bool use_block_copy = true; /* Tradeoffs for COMPLEX types pretty much always make it better to go ahead and split the components. */ if (TREE_CODE (elt->type) == COMPLEX_TYPE) use_block_copy = false; /* Don't bother trying to figure out the rest if the structure is so large we can't do easy arithmetic. This also forces block copies for variable sized structures. */ else if (host_integerp (size_tree, 1)) { unsigned HOST_WIDE_INT full_size, inst_size = 0; unsigned int max_size, max_count, inst_count, full_count; /* If the sra-max-structure-size parameter is 0, then the user has not overridden the parameter and we can choose a sensible default. */ max_size = SRA_MAX_STRUCTURE_SIZE ? SRA_MAX_STRUCTURE_SIZE : MOVE_RATIO * UNITS_PER_WORD; max_count = SRA_MAX_STRUCTURE_COUNT ? SRA_MAX_STRUCTURE_COUNT : MOVE_RATIO; full_size = tree_low_cst (size_tree, 1); full_count = count_type_elements (elt->type, false); inst_count = sum_instantiated_sizes (elt, &inst_size); /* ??? What to do here. If there are two fields, and we've only instantiated one, then instantiating the other is clearly a win. If there are a large number of fields then the size of the copy is much more of a factor. */ /* If the structure is small, and we've made copies, go ahead and instantiate, hoping that the copies will go away. */ if (full_size <= max_size && (full_count - inst_count) <= max_count && elt->n_copies > elt->n_uses) use_block_copy = false; else if (inst_count * 100 >= full_count * SRA_FIELD_STRUCTURE_RATIO && inst_size * 100 >= full_size * SRA_FIELD_STRUCTURE_RATIO) use_block_copy = false; /* In order to avoid block copy, we have to be able to instantiate all elements of the type. See if this is possible. */ if (!use_block_copy && (!can_completely_scalarize_p (elt) || !type_can_instantiate_all_elements (elt->type))) use_block_copy = true; } elt->use_block_copy = use_block_copy; /* Groups behave like their parent. */ for (c = elt->groups; c; c = c->sibling) c->use_block_copy = use_block_copy; if (dump_file) { fprintf (dump_file, "Using %s for ", use_block_copy ? "block-copy" : "element-copy"); dump_sra_elt_name (dump_file, elt); fputc ('\n', dump_file); } if (!use_block_copy) { instantiate_missing_elements (elt); return true; } } any_inst = elt->replacement != NULL; for (c = elt->children; c ; c = c->sibling) any_inst |= decide_block_copy (c); return any_inst; } /* Entry point to phase 3. Instantiate scalar replacement variables. */ static void decide_instantiations (void) { unsigned int i; bool cleared_any; bitmap_head done_head; bitmap_iterator bi; /* We cannot clear bits from a bitmap we're iterating over, so save up all the bits to clear until the end. */ bitmap_initialize (&done_head, &bitmap_default_obstack); cleared_any = false; EXECUTE_IF_SET_IN_BITMAP (sra_candidates, 0, i, bi) { tree var = referenced_var (i); struct sra_elt *elt = lookup_element (NULL, var, NULL, NO_INSERT); if (elt) { decide_instantiation_1 (elt, 0, 0); if (!decide_block_copy (elt)) elt = NULL; } if (!elt) { bitmap_set_bit (&done_head, i); cleared_any = true; } } if (cleared_any) { bitmap_and_compl_into (sra_candidates, &done_head); bitmap_and_compl_into (needs_copy_in, &done_head); } bitmap_clear (&done_head); if (!bitmap_empty_p (sra_candidates)) todoflags |= TODO_update_smt_usage; mark_set_for_renaming (sra_candidates); if (dump_file) fputc ('\n', dump_file); } /* Phase Four: Update the function to match the replacements created. */ /* Mark all the variables in V_MAY_DEF or V_MUST_DEF operands for STMT for renaming. This becomes necessary when we modify all of a non-scalar. */ static void mark_all_v_defs_1 (tree stmt) { tree sym; ssa_op_iter iter; update_stmt_if_modified (stmt); FOR_EACH_SSA_TREE_OPERAND (sym, stmt, iter, SSA_OP_ALL_VIRTUALS) { if (TREE_CODE (sym) == SSA_NAME) sym = SSA_NAME_VAR (sym); mark_sym_for_renaming (sym); } } /* Mark all the variables in virtual operands in all the statements in LIST for renaming. */ static void mark_all_v_defs (tree list) { if (TREE_CODE (list) != STATEMENT_LIST) mark_all_v_defs_1 (list); else { tree_stmt_iterator i; for (i = tsi_start (list); !tsi_end_p (i); tsi_next (&i)) mark_all_v_defs_1 (tsi_stmt (i)); } } /* Mark every replacement under ELT with TREE_NO_WARNING. */ static void mark_no_warning (struct sra_elt *elt) { if (!elt->all_no_warning) { if (elt->replacement) TREE_NO_WARNING (elt->replacement) = 1; else { struct sra_elt *c; FOR_EACH_ACTUAL_CHILD (c, elt) mark_no_warning (c); } elt->all_no_warning = true; } } /* Build a single level component reference to ELT rooted at BASE. */ static tree generate_one_element_ref (struct sra_elt *elt, tree base) { switch (TREE_CODE (TREE_TYPE (base))) { case RECORD_TYPE: { tree field = elt->element; /* Watch out for compatible records with differing field lists. */ if (DECL_FIELD_CONTEXT (field) != TYPE_MAIN_VARIANT (TREE_TYPE (base))) field = find_compatible_field (TREE_TYPE (base), field); return build3 (COMPONENT_REF, elt->type, base, field, NULL); } case ARRAY_TYPE: todoflags |= TODO_update_smt_usage; if (TREE_CODE (elt->element) == RANGE_EXPR) return build4 (ARRAY_RANGE_REF, elt->type, base, TREE_OPERAND (elt->element, 0), NULL, NULL); else return build4 (ARRAY_REF, elt->type, base, elt->element, NULL, NULL); case COMPLEX_TYPE: if (elt->element == integer_zero_node) return build1 (REALPART_EXPR, elt->type, base); else return build1 (IMAGPART_EXPR, elt->type, base); default: gcc_unreachable (); } } /* Build a full component reference to ELT rooted at its native variable. */ static tree generate_element_ref (struct sra_elt *elt) { if (elt->parent) return generate_one_element_ref (elt, generate_element_ref (elt->parent)); else return elt->element; } static tree sra_build_assignment (tree dst, tree src) { /* We need TYPE_CANONICAL to compare the types of dst and src efficiently, but that's only introduced in GCC 4.3. */ return build2 (MODIFY_EXPR, void_type_node, dst, src); } /* Generate a set of assignment statements in *LIST_P to copy all instantiated elements under ELT to or from the equivalent structure rooted at EXPR. COPY_OUT controls the direction of the copy, with true meaning to copy out of EXPR into ELT. */ static void generate_copy_inout (struct sra_elt *elt, bool copy_out, tree expr, tree *list_p) { struct sra_elt *c; tree t; if (!copy_out && TREE_CODE (expr) == SSA_NAME && TREE_CODE (TREE_TYPE (expr)) == COMPLEX_TYPE) { tree r, i; c = lookup_element (elt, integer_zero_node, NULL, NO_INSERT); r = c->replacement; c = lookup_element (elt, integer_one_node, NULL, NO_INSERT); i = c->replacement; t = build2 (COMPLEX_EXPR, elt->type, r, i); t = sra_build_assignment (expr, t); SSA_NAME_DEF_STMT (expr) = t; append_to_statement_list (t, list_p); } else if (elt->replacement) { if (copy_out) t = sra_build_assignment (elt->replacement, expr); else t = sra_build_assignment (expr, elt->replacement); append_to_statement_list (t, list_p); } else { FOR_EACH_ACTUAL_CHILD (c, elt) { t = generate_one_element_ref (c, unshare_expr (expr)); generate_copy_inout (c, copy_out, t, list_p); } } } /* Generate a set of assignment statements in *LIST_P to copy all instantiated elements under SRC to their counterparts under DST. There must be a 1-1 correspondence of instantiated elements. */ static void generate_element_copy (struct sra_elt *dst, struct sra_elt *src, tree *list_p) { struct sra_elt *dc, *sc; FOR_EACH_ACTUAL_CHILD (dc, dst) { sc = lookup_element (src, dc->element, NULL, NO_INSERT); gcc_assert (sc); generate_element_copy (dc, sc, list_p); } if (dst->replacement) { tree t; gcc_assert (src->replacement); t = sra_build_assignment (dst->replacement, src->replacement); append_to_statement_list (t, list_p); } } /* Generate a set of assignment statements in *LIST_P to zero all instantiated elements under ELT. In addition, do not assign to elements that have been marked VISITED but do reset the visited flag; this allows easy coordination with generate_element_init. */ static void generate_element_zero (struct sra_elt *elt, tree *list_p) { struct sra_elt *c; if (elt->visited) { elt->visited = false; return; } FOR_EACH_ACTUAL_CHILD (c, elt) generate_element_zero (c, list_p); if (elt->replacement) { tree t; gcc_assert (elt->is_scalar); t = fold_convert (elt->type, integer_zero_node); t = sra_build_assignment (elt->replacement, t); append_to_statement_list (t, list_p); } } /* Generate an assignment VAR = INIT, where INIT may need gimplification. Add the result to *LIST_P. */ static void generate_one_element_init (tree var, tree init, tree *list_p) { /* The replacement can be almost arbitrarily complex. Gimplify. */ tree stmt = sra_build_assignment (var, init); gimplify_and_add (stmt, list_p); } /* Generate a set of assignment statements in *LIST_P to set all instantiated elements under ELT with the contents of the initializer INIT. In addition, mark all assigned elements VISITED; this allows easy coordination with generate_element_zero. Return false if we found a case we couldn't handle. */ static bool generate_element_init_1 (struct sra_elt *elt, tree init, tree *list_p) { bool result = true; enum tree_code init_code; struct sra_elt *sub; tree t; unsigned HOST_WIDE_INT idx; tree value, purpose; /* We can be passed DECL_INITIAL of a static variable. It might have a conversion, which we strip off here. */ STRIP_USELESS_TYPE_CONVERSION (init); init_code = TREE_CODE (init); if (elt->is_scalar) { if (elt->replacement) { generate_one_element_init (elt->replacement, init, list_p); elt->visited = true; } return result; } switch (init_code) { case COMPLEX_CST: case COMPLEX_EXPR: FOR_EACH_ACTUAL_CHILD (sub, elt) { if (sub->element == integer_zero_node) t = (init_code == COMPLEX_EXPR ? TREE_OPERAND (init, 0) : TREE_REALPART (init)); else t = (init_code == COMPLEX_EXPR ? TREE_OPERAND (init, 1) : TREE_IMAGPART (init)); result &= generate_element_init_1 (sub, t, list_p); } break; case CONSTRUCTOR: FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (init), idx, purpose, value) { if (TREE_CODE (purpose) == RANGE_EXPR) { tree lower = TREE_OPERAND (purpose, 0); tree upper = TREE_OPERAND (purpose, 1); while (1) { sub = lookup_element (elt, lower, NULL, NO_INSERT); if (sub != NULL) result &= generate_element_init_1 (sub, value, list_p); if (tree_int_cst_equal (lower, upper)) break; lower = int_const_binop (PLUS_EXPR, lower, integer_one_node, true); } } else { sub = lookup_element (elt, purpose, NULL, NO_INSERT); if (sub != NULL) result &= generate_element_init_1 (sub, value, list_p); } } break; default: elt->visited = true; result = false; } return result; } /* A wrapper function for generate_element_init_1 that handles cleanup after gimplification. */ static bool generate_element_init (struct sra_elt *elt, tree init, tree *list_p) { bool ret; push_gimplify_context (); ret = generate_element_init_1 (elt, init, list_p); pop_gimplify_context (NULL); /* The replacement can expose previously unreferenced variables. */ if (ret && *list_p) { tree_stmt_iterator i; for (i = tsi_start (*list_p); !tsi_end_p (i); tsi_next (&i)) find_new_referenced_vars (tsi_stmt_ptr (i)); } return ret; } /* Insert STMT on all the outgoing edges out of BB. Note that if BB has more than one edge, STMT will be replicated for each edge. Also, abnormal edges will be ignored. */ void insert_edge_copies (tree stmt, basic_block bb) { edge e; edge_iterator ei; bool first_copy; first_copy = true; FOR_EACH_EDGE (e, ei, bb->succs) { /* We don't need to insert copies on abnormal edges. The value of the scalar replacement is not guaranteed to be valid through an abnormal edge. */ if (!(e->flags & EDGE_ABNORMAL)) { if (first_copy) { bsi_insert_on_edge (e, stmt); first_copy = false; } else bsi_insert_on_edge (e, unsave_expr_now (stmt)); } } } /* Helper function to insert LIST before BSI, and set up line number info. */ void sra_insert_before (block_stmt_iterator *bsi, tree list) { tree stmt = bsi_stmt (*bsi); if (EXPR_HAS_LOCATION (stmt)) annotate_all_with_locus (&list, EXPR_LOCATION (stmt)); bsi_insert_before (bsi, list, BSI_SAME_STMT); } /* Similarly, but insert after BSI. Handles insertion onto edges as well. */ void sra_insert_after (block_stmt_iterator *bsi, tree list) { tree stmt = bsi_stmt (*bsi); if (EXPR_HAS_LOCATION (stmt)) annotate_all_with_locus (&list, EXPR_LOCATION (stmt)); if (stmt_ends_bb_p (stmt)) insert_edge_copies (list, bsi->bb); else bsi_insert_after (bsi, list, BSI_SAME_STMT); } /* Similarly, but replace the statement at BSI. */ static void sra_replace (block_stmt_iterator *bsi, tree list) { sra_insert_before (bsi, list); bsi_remove (bsi, false); if (bsi_end_p (*bsi)) *bsi = bsi_last (bsi->bb); else bsi_prev (bsi); } /* Scalarize a USE. To recap, this is either a simple reference to ELT, if elt is scalar, or some occurrence of ELT that requires a complete aggregate. IS_OUTPUT is true if ELT is being modified. */ static void scalarize_use (struct sra_elt *elt, tree *expr_p, block_stmt_iterator *bsi, bool is_output, bool use_all) { tree list = NULL, stmt = bsi_stmt (*bsi); if (elt->replacement) { /* If we have a replacement, then updating the reference is as simple as modifying the existing statement in place. */ if (is_output) mark_all_v_defs (stmt); *expr_p = elt->replacement; update_stmt (stmt); } else { /* Otherwise we need some copies. If ELT is being read, then we want to store all (modified) sub-elements back into the structure before the reference takes place. If ELT is being written, then we want to load the changed values back into our shadow variables. */ /* ??? We don't check modified for reads, we just always write all of the values. We should be able to record the SSA number of the VOP for which the values were last read. If that number matches the SSA number of the VOP in the current statement, then we needn't emit an assignment. This would also eliminate double writes when a structure is passed as more than one argument to a function call. This optimization would be most effective if sra_walk_function processed the blocks in dominator order. */ generate_copy_inout (elt, is_output, generate_element_ref (elt), &list); if (list == NULL) return; mark_all_v_defs (list); if (is_output) sra_insert_after (bsi, list); else { sra_insert_before (bsi, list); if (use_all) mark_no_warning (elt); } } } /* Scalarize a COPY. To recap, this is an assignment statement between two scalarizable references, LHS_ELT and RHS_ELT. */ static void scalarize_copy (struct sra_elt *lhs_elt, struct sra_elt *rhs_elt, block_stmt_iterator *bsi) { tree list, stmt; if (lhs_elt->replacement && rhs_elt->replacement) { /* If we have two scalar operands, modify the existing statement. */ stmt = bsi_stmt (*bsi); /* See the commentary in sra_walk_function concerning RETURN_EXPR, and why we should never see one here. */ gcc_assert (TREE_CODE (stmt) == MODIFY_EXPR); TREE_OPERAND (stmt, 0) = lhs_elt->replacement; TREE_OPERAND (stmt, 1) = rhs_elt->replacement; update_stmt (stmt); } else if (lhs_elt->use_block_copy || rhs_elt->use_block_copy) { /* If either side requires a block copy, then sync the RHS back to the original structure, leave the original assignment statement (which will perform the block copy), then load the LHS values out of its now-updated original structure. */ /* ??? Could perform a modified pair-wise element copy. That would at least allow those elements that are instantiated in both structures to be optimized well. */ list = NULL; generate_copy_inout (rhs_elt, false, generate_element_ref (rhs_elt), &list); if (list) { mark_all_v_defs (list); sra_insert_before (bsi, list); } list = NULL; generate_copy_inout (lhs_elt, true, generate_element_ref (lhs_elt), &list); if (list) { mark_all_v_defs (list); sra_insert_after (bsi, list); } } else { /* Otherwise both sides must be fully instantiated. In which case perform pair-wise element assignments and replace the original block copy statement. */ stmt = bsi_stmt (*bsi); mark_all_v_defs (stmt); list = NULL; generate_element_copy (lhs_elt, rhs_elt, &list); gcc_assert (list); mark_all_v_defs (list); sra_replace (bsi, list); } } /* Scalarize an INIT. To recap, this is an assignment to a scalarizable reference from some form of constructor: CONSTRUCTOR, COMPLEX_CST or COMPLEX_EXPR. If RHS is NULL, it should be treated as an empty CONSTRUCTOR. */ static void scalarize_init (struct sra_elt *lhs_elt, tree rhs, block_stmt_iterator *bsi) { bool result = true; tree list = NULL; /* Generate initialization statements for all members extant in the RHS. */ if (rhs) { /* Unshare the expression just in case this is from a decl's initial. */ rhs = unshare_expr (rhs); result = generate_element_init (lhs_elt, rhs, &list); } /* CONSTRUCTOR is defined such that any member not mentioned is assigned a zero value. Initialize the rest of the instantiated elements. */ generate_element_zero (lhs_elt, &list); if (!result) { /* If we failed to convert the entire initializer, then we must leave the structure assignment in place and must load values from the structure into the slots for which we did not find constants. The easiest way to do this is to generate a complete copy-out, and then follow that with the constant assignments that we were able to build. DCE will clean things up. */ tree list0 = NULL; generate_copy_inout (lhs_elt, true, generate_element_ref (lhs_elt), &list0); append_to_statement_list (list, &list0); list = list0; } if (lhs_elt->use_block_copy || !result) { /* Since LHS is not fully instantiated, we must leave the structure assignment in place. Treating this case differently from a USE exposes constants to later optimizations. */ if (list) { mark_all_v_defs (list); sra_insert_after (bsi, list); } } else { /* The LHS is fully instantiated. The list of initializations replaces the original structure assignment. */ gcc_assert (list); mark_all_v_defs (bsi_stmt (*bsi)); mark_all_v_defs (list); sra_replace (bsi, list); } } /* A subroutine of scalarize_ldst called via walk_tree. Set TREE_NO_TRAP on all INDIRECT_REFs. */ static tree mark_notrap (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED) { tree t = *tp; if (TREE_CODE (t) == INDIRECT_REF) { TREE_THIS_NOTRAP (t) = 1; *walk_subtrees = 0; } else if (IS_TYPE_OR_DECL_P (t)) *walk_subtrees = 0; return NULL; } /* Scalarize a LDST. To recap, this is an assignment between one scalarizable reference ELT and one non-scalarizable reference OTHER. IS_OUTPUT is true if ELT is on the left-hand side. */ static void scalarize_ldst (struct sra_elt *elt, tree other, block_stmt_iterator *bsi, bool is_output) { /* Shouldn't have gotten called for a scalar. */ gcc_assert (!elt->replacement); if (elt->use_block_copy) { /* Since ELT is not fully instantiated, we have to leave the block copy in place. Treat this as a USE. */ scalarize_use (elt, NULL, bsi, is_output, false); } else { /* The interesting case is when ELT is fully instantiated. In this case we can have each element stored/loaded directly to/from the corresponding slot in OTHER. This avoids a block copy. */ tree list = NULL, stmt = bsi_stmt (*bsi); mark_all_v_defs (stmt); generate_copy_inout (elt, is_output, other, &list); mark_all_v_defs (list); gcc_assert (list); /* Preserve EH semantics. */ if (stmt_ends_bb_p (stmt)) { tree_stmt_iterator tsi; tree first; /* Extract the first statement from LIST. */ tsi = tsi_start (list); first = tsi_stmt (tsi); tsi_delink (&tsi); /* Replace the old statement with this new representative. */ bsi_replace (bsi, first, true); if (!tsi_end_p (tsi)) { /* If any reference would trap, then they all would. And more to the point, the first would. Therefore none of the rest will trap since the first didn't. Indicate this by iterating over the remaining statements and set TREE_THIS_NOTRAP in all INDIRECT_REFs. */ do { walk_tree (tsi_stmt_ptr (tsi), mark_notrap, NULL, NULL); tsi_next (&tsi); } while (!tsi_end_p (tsi)); insert_edge_copies (list, bsi->bb); } } else sra_replace (bsi, list); } } /* Generate initializations for all scalarizable parameters. */ static void scalarize_parms (void) { tree list = NULL; unsigned i; bitmap_iterator bi; EXECUTE_IF_SET_IN_BITMAP (needs_copy_in, 0, i, bi) { tree var = referenced_var (i); struct sra_elt *elt = lookup_element (NULL, var, NULL, NO_INSERT); generate_copy_inout (elt, true, var, &list); } if (list) { insert_edge_copies (list, ENTRY_BLOCK_PTR); mark_all_v_defs (list); } } /* Entry point to phase 4. Update the function to match replacements. */ static void scalarize_function (void) { static const struct sra_walk_fns fns = { scalarize_use, scalarize_copy, scalarize_init, scalarize_ldst, false }; sra_walk_function (&fns); scalarize_parms (); bsi_commit_edge_inserts (); } /* Debug helper function. Print ELT in a nice human-readable format. */ static void dump_sra_elt_name (FILE *f, struct sra_elt *elt) { if (elt->parent && TREE_CODE (elt->parent->type) == COMPLEX_TYPE) { fputs (elt->element == integer_zero_node ? "__real__ " : "__imag__ ", f); dump_sra_elt_name (f, elt->parent); } else { if (elt->parent) dump_sra_elt_name (f, elt->parent); if (DECL_P (elt->element)) { if (TREE_CODE (elt->element) == FIELD_DECL) fputc ('.', f); print_generic_expr (f, elt->element, dump_flags); } else if (TREE_CODE (elt->element) == RANGE_EXPR) fprintf (f, "["HOST_WIDE_INT_PRINT_DEC".."HOST_WIDE_INT_PRINT_DEC"]", TREE_INT_CST_LOW (TREE_OPERAND (elt->element, 0)), TREE_INT_CST_LOW (TREE_OPERAND (elt->element, 1))); else fprintf (f, "[" HOST_WIDE_INT_PRINT_DEC "]", TREE_INT_CST_LOW (elt->element)); } } /* Likewise, but callable from the debugger. */ void debug_sra_elt_name (struct sra_elt *elt) { dump_sra_elt_name (stderr, elt); fputc ('\n', stderr); } void sra_init_cache (void) { if (sra_type_decomp_cache) return; sra_type_decomp_cache = BITMAP_ALLOC (NULL); sra_type_inst_cache = BITMAP_ALLOC (NULL); } /* Main entry point. */ static unsigned int tree_sra (void) { /* Initialize local variables. */ todoflags = 0; gcc_obstack_init (&sra_obstack); sra_candidates = BITMAP_ALLOC (NULL); needs_copy_in = BITMAP_ALLOC (NULL); sra_init_cache (); sra_map = htab_create (101, sra_elt_hash, sra_elt_eq, NULL); /* Scan. If we find anything, instantiate and scalarize. */ if (find_candidates_for_sra ()) { scan_function (); decide_instantiations (); scalarize_function (); } /* Free allocated memory. */ htab_delete (sra_map); sra_map = NULL; BITMAP_FREE (sra_candidates); BITMAP_FREE (needs_copy_in); BITMAP_FREE (sra_type_decomp_cache); BITMAP_FREE (sra_type_inst_cache); obstack_free (&sra_obstack, NULL); return todoflags; } static bool gate_sra (void) { return flag_tree_sra != 0; } struct tree_opt_pass pass_sra = { "sra", /* name */ gate_sra, /* gate */ tree_sra, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_TREE_SRA, /* tv_id */ PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ 0, /* properties_provided */ PROP_smt_usage, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_dump_func /* todo_flags_finish */ | TODO_update_ssa | TODO_ggc_collect | TODO_verify_ssa, 0 /* letter */ };
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