1 /* SCC value numbering for trees
2 Copyright (C) 2006, 2007, 2008, 2009, 2010
3 Free Software Foundation, Inc.
4 Contributed by Daniel Berlin <dan@dberlin.org>
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
24 #include "coretypes.h"
27 #include "basic-block.h"
28 #include "tree-pretty-print.h"
29 #include "gimple-pretty-print.h"
30 #include "tree-inline.h"
31 #include "tree-flow.h"
33 #include "tree-dump.h"
37 #include "tree-iterator.h"
38 #include "alloc-pool.h"
39 #include "tree-pass.h"
42 #include "langhooks.h"
45 #include "tree-ssa-propagate.h"
46 #include "tree-ssa-sccvn.h"
48 /* This algorithm is based on the SCC algorithm presented by Keith
49 Cooper and L. Taylor Simpson in "SCC-Based Value numbering"
50 (http://citeseer.ist.psu.edu/41805.html). In
51 straight line code, it is equivalent to a regular hash based value
52 numbering that is performed in reverse postorder.
54 For code with cycles, there are two alternatives, both of which
55 require keeping the hashtables separate from the actual list of
56 value numbers for SSA names.
58 1. Iterate value numbering in an RPO walk of the blocks, removing
59 all the entries from the hashtable after each iteration (but
60 keeping the SSA name->value number mapping between iterations).
61 Iterate until it does not change.
63 2. Perform value numbering as part of an SCC walk on the SSA graph,
64 iterating only the cycles in the SSA graph until they do not change
65 (using a separate, optimistic hashtable for value numbering the SCC
68 The second is not just faster in practice (because most SSA graph
69 cycles do not involve all the variables in the graph), it also has
72 One of these nice properties is that when we pop an SCC off the
73 stack, we are guaranteed to have processed all the operands coming from
74 *outside of that SCC*, so we do not need to do anything special to
75 ensure they have value numbers.
77 Another nice property is that the SCC walk is done as part of a DFS
78 of the SSA graph, which makes it easy to perform combining and
79 simplifying operations at the same time.
81 The code below is deliberately written in a way that makes it easy
82 to separate the SCC walk from the other work it does.
84 In order to propagate constants through the code, we track which
85 expressions contain constants, and use those while folding. In
86 theory, we could also track expressions whose value numbers are
87 replaced, in case we end up folding based on expression
90 In order to value number memory, we assign value numbers to vuses.
91 This enables us to note that, for example, stores to the same
92 address of the same value from the same starting memory states are
96 1. We can iterate only the changing portions of the SCC's, but
97 I have not seen an SCC big enough for this to be a win.
98 2. If you differentiate between phi nodes for loops and phi nodes
99 for if-then-else, you can properly consider phi nodes in different
100 blocks for equivalence.
101 3. We could value number vuses in more cases, particularly, whole
105 /* The set of hashtables and alloc_pool's for their items. */
107 typedef struct vn_tables_s
112 struct obstack nary_obstack;
113 alloc_pool phis_pool;
114 alloc_pool references_pool;
117 static htab_t constant_to_value_id;
118 static bitmap constant_value_ids;
121 /* Valid hashtables storing information we have proven to be
124 static vn_tables_t valid_info;
126 /* Optimistic hashtables storing information we are making assumptions about
127 during iterations. */
129 static vn_tables_t optimistic_info;
131 /* Pointer to the set of hashtables that is currently being used.
132 Should always point to either the optimistic_info, or the
135 static vn_tables_t current_info;
138 /* Reverse post order index for each basic block. */
140 static int *rpo_numbers;
142 #define SSA_VAL(x) (VN_INFO ((x))->valnum)
144 /* This represents the top of the VN lattice, which is the universal
149 /* Unique counter for our value ids. */
151 static unsigned int next_value_id;
153 /* Next DFS number and the stack for strongly connected component
156 static unsigned int next_dfs_num;
157 static VEC (tree, heap) *sccstack;
160 DEF_VEC_P(vn_ssa_aux_t);
161 DEF_VEC_ALLOC_P(vn_ssa_aux_t, heap);
163 /* Table of vn_ssa_aux_t's, one per ssa_name. The vn_ssa_aux_t objects
164 are allocated on an obstack for locality reasons, and to free them
165 without looping over the VEC. */
167 static VEC (vn_ssa_aux_t, heap) *vn_ssa_aux_table;
168 static struct obstack vn_ssa_aux_obstack;
170 /* Return the value numbering information for a given SSA name. */
175 vn_ssa_aux_t res = VEC_index (vn_ssa_aux_t, vn_ssa_aux_table,
176 SSA_NAME_VERSION (name));
177 gcc_checking_assert (res);
181 /* Set the value numbering info for a given SSA name to a given
185 VN_INFO_SET (tree name, vn_ssa_aux_t value)
187 VEC_replace (vn_ssa_aux_t, vn_ssa_aux_table,
188 SSA_NAME_VERSION (name), value);
191 /* Initialize the value numbering info for a given SSA name.
192 This should be called just once for every SSA name. */
195 VN_INFO_GET (tree name)
197 vn_ssa_aux_t newinfo;
199 newinfo = XOBNEW (&vn_ssa_aux_obstack, struct vn_ssa_aux);
200 memset (newinfo, 0, sizeof (struct vn_ssa_aux));
201 if (SSA_NAME_VERSION (name) >= VEC_length (vn_ssa_aux_t, vn_ssa_aux_table))
202 VEC_safe_grow (vn_ssa_aux_t, heap, vn_ssa_aux_table,
203 SSA_NAME_VERSION (name) + 1);
204 VEC_replace (vn_ssa_aux_t, vn_ssa_aux_table,
205 SSA_NAME_VERSION (name), newinfo);
210 /* Get the representative expression for the SSA_NAME NAME. Returns
211 the representative SSA_NAME if there is no expression associated with it. */
214 vn_get_expr_for (tree name)
216 vn_ssa_aux_t vn = VN_INFO (name);
218 tree expr = NULL_TREE;
220 if (vn->valnum == VN_TOP)
223 /* If the value-number is a constant it is the representative
225 if (TREE_CODE (vn->valnum) != SSA_NAME)
228 /* Get to the information of the value of this SSA_NAME. */
229 vn = VN_INFO (vn->valnum);
231 /* If the value-number is a constant it is the representative
233 if (TREE_CODE (vn->valnum) != SSA_NAME)
236 /* Else if we have an expression, return it. */
237 if (vn->expr != NULL_TREE)
240 /* Otherwise use the defining statement to build the expression. */
241 def_stmt = SSA_NAME_DEF_STMT (vn->valnum);
243 /* If the value number is a default-definition or a PHI result
245 if (gimple_nop_p (def_stmt)
246 || gimple_code (def_stmt) == GIMPLE_PHI)
249 if (!is_gimple_assign (def_stmt))
252 /* FIXME tuples. This is incomplete and likely will miss some
254 switch (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)))
257 if ((gimple_assign_rhs_code (def_stmt) == VIEW_CONVERT_EXPR
258 || gimple_assign_rhs_code (def_stmt) == REALPART_EXPR
259 || gimple_assign_rhs_code (def_stmt) == IMAGPART_EXPR)
260 && TREE_CODE (gimple_assign_rhs1 (def_stmt)) == SSA_NAME)
261 expr = fold_build1 (gimple_assign_rhs_code (def_stmt),
262 gimple_expr_type (def_stmt),
263 TREE_OPERAND (gimple_assign_rhs1 (def_stmt), 0));
267 expr = fold_build1 (gimple_assign_rhs_code (def_stmt),
268 gimple_expr_type (def_stmt),
269 gimple_assign_rhs1 (def_stmt));
273 expr = fold_build2 (gimple_assign_rhs_code (def_stmt),
274 gimple_expr_type (def_stmt),
275 gimple_assign_rhs1 (def_stmt),
276 gimple_assign_rhs2 (def_stmt));
281 if (expr == NULL_TREE)
284 /* Cache the expression. */
291 /* Free a phi operation structure VP. */
296 vn_phi_t phi = (vn_phi_t) vp;
297 VEC_free (tree, heap, phi->phiargs);
300 /* Free a reference operation structure VP. */
303 free_reference (void *vp)
305 vn_reference_t vr = (vn_reference_t) vp;
306 VEC_free (vn_reference_op_s, heap, vr->operands);
309 /* Hash table equality function for vn_constant_t. */
312 vn_constant_eq (const void *p1, const void *p2)
314 const struct vn_constant_s *vc1 = (const struct vn_constant_s *) p1;
315 const struct vn_constant_s *vc2 = (const struct vn_constant_s *) p2;
317 if (vc1->hashcode != vc2->hashcode)
320 return vn_constant_eq_with_type (vc1->constant, vc2->constant);
323 /* Hash table hash function for vn_constant_t. */
326 vn_constant_hash (const void *p1)
328 const struct vn_constant_s *vc1 = (const struct vn_constant_s *) p1;
329 return vc1->hashcode;
332 /* Lookup a value id for CONSTANT and return it. If it does not
336 get_constant_value_id (tree constant)
339 struct vn_constant_s vc;
341 vc.hashcode = vn_hash_constant_with_type (constant);
342 vc.constant = constant;
343 slot = htab_find_slot_with_hash (constant_to_value_id, &vc,
344 vc.hashcode, NO_INSERT);
346 return ((vn_constant_t)*slot)->value_id;
350 /* Lookup a value id for CONSTANT, and if it does not exist, create a
351 new one and return it. If it does exist, return it. */
354 get_or_alloc_constant_value_id (tree constant)
357 struct vn_constant_s vc;
360 vc.hashcode = vn_hash_constant_with_type (constant);
361 vc.constant = constant;
362 slot = htab_find_slot_with_hash (constant_to_value_id, &vc,
363 vc.hashcode, INSERT);
365 return ((vn_constant_t)*slot)->value_id;
367 vcp = XNEW (struct vn_constant_s);
368 vcp->hashcode = vc.hashcode;
369 vcp->constant = constant;
370 vcp->value_id = get_next_value_id ();
371 *slot = (void *) vcp;
372 bitmap_set_bit (constant_value_ids, vcp->value_id);
373 return vcp->value_id;
376 /* Return true if V is a value id for a constant. */
379 value_id_constant_p (unsigned int v)
381 return bitmap_bit_p (constant_value_ids, v);
384 /* Compare two reference operands P1 and P2 for equality. Return true if
385 they are equal, and false otherwise. */
388 vn_reference_op_eq (const void *p1, const void *p2)
390 const_vn_reference_op_t const vro1 = (const_vn_reference_op_t) p1;
391 const_vn_reference_op_t const vro2 = (const_vn_reference_op_t) p2;
393 return vro1->opcode == vro2->opcode
394 && types_compatible_p (vro1->type, vro2->type)
395 && expressions_equal_p (vro1->op0, vro2->op0)
396 && expressions_equal_p (vro1->op1, vro2->op1)
397 && expressions_equal_p (vro1->op2, vro2->op2);
400 /* Compute the hash for a reference operand VRO1. */
403 vn_reference_op_compute_hash (const vn_reference_op_t vro1, hashval_t result)
405 result = iterative_hash_hashval_t (vro1->opcode, result);
407 result = iterative_hash_expr (vro1->op0, result);
409 result = iterative_hash_expr (vro1->op1, result);
411 result = iterative_hash_expr (vro1->op2, result);
415 /* Return the hashcode for a given reference operation P1. */
418 vn_reference_hash (const void *p1)
420 const_vn_reference_t const vr1 = (const_vn_reference_t) p1;
421 return vr1->hashcode;
424 /* Compute a hash for the reference operation VR1 and return it. */
427 vn_reference_compute_hash (const vn_reference_t vr1)
429 hashval_t result = 0;
431 vn_reference_op_t vro;
432 HOST_WIDE_INT off = -1;
435 FOR_EACH_VEC_ELT (vn_reference_op_s, vr1->operands, i, vro)
437 if (vro->opcode == MEM_REF)
439 else if (vro->opcode != ADDR_EXPR)
451 result = iterative_hash_hashval_t (off, result);
454 && vro->opcode == ADDR_EXPR)
458 tree op = TREE_OPERAND (vro->op0, 0);
459 result = iterative_hash_hashval_t (TREE_CODE (op), result);
460 result = iterative_hash_expr (op, result);
464 result = vn_reference_op_compute_hash (vro, result);
468 result += SSA_NAME_VERSION (vr1->vuse);
473 /* Return true if reference operations P1 and P2 are equivalent. This
474 means they have the same set of operands and vuses. */
477 vn_reference_eq (const void *p1, const void *p2)
481 const_vn_reference_t const vr1 = (const_vn_reference_t) p1;
482 const_vn_reference_t const vr2 = (const_vn_reference_t) p2;
483 if (vr1->hashcode != vr2->hashcode)
486 /* Early out if this is not a hash collision. */
487 if (vr1->hashcode != vr2->hashcode)
490 /* The VOP needs to be the same. */
491 if (vr1->vuse != vr2->vuse)
494 /* If the operands are the same we are done. */
495 if (vr1->operands == vr2->operands)
498 if (!expressions_equal_p (TYPE_SIZE (vr1->type), TYPE_SIZE (vr2->type)))
501 if (INTEGRAL_TYPE_P (vr1->type)
502 && INTEGRAL_TYPE_P (vr2->type))
504 if (TYPE_PRECISION (vr1->type) != TYPE_PRECISION (vr2->type))
507 else if (INTEGRAL_TYPE_P (vr1->type)
508 && (TYPE_PRECISION (vr1->type)
509 != TREE_INT_CST_LOW (TYPE_SIZE (vr1->type))))
511 else if (INTEGRAL_TYPE_P (vr2->type)
512 && (TYPE_PRECISION (vr2->type)
513 != TREE_INT_CST_LOW (TYPE_SIZE (vr2->type))))
520 HOST_WIDE_INT off1 = 0, off2 = 0;
521 vn_reference_op_t vro1, vro2;
522 vn_reference_op_s tem1, tem2;
523 bool deref1 = false, deref2 = false;
524 for (; VEC_iterate (vn_reference_op_s, vr1->operands, i, vro1); i++)
526 if (vro1->opcode == MEM_REF)
532 for (; VEC_iterate (vn_reference_op_s, vr2->operands, j, vro2); j++)
534 if (vro2->opcode == MEM_REF)
542 if (deref1 && vro1->opcode == ADDR_EXPR)
544 memset (&tem1, 0, sizeof (tem1));
545 tem1.op0 = TREE_OPERAND (vro1->op0, 0);
546 tem1.type = TREE_TYPE (tem1.op0);
547 tem1.opcode = TREE_CODE (tem1.op0);
550 if (deref2 && vro2->opcode == ADDR_EXPR)
552 memset (&tem2, 0, sizeof (tem2));
553 tem2.op0 = TREE_OPERAND (vro2->op0, 0);
554 tem2.type = TREE_TYPE (tem2.op0);
555 tem2.opcode = TREE_CODE (tem2.op0);
558 if (!vn_reference_op_eq (vro1, vro2))
563 while (VEC_length (vn_reference_op_s, vr1->operands) != i
564 || VEC_length (vn_reference_op_s, vr2->operands) != j);
569 /* Copy the operations present in load/store REF into RESULT, a vector of
570 vn_reference_op_s's. */
573 copy_reference_ops_from_ref (tree ref, VEC(vn_reference_op_s, heap) **result)
575 if (TREE_CODE (ref) == TARGET_MEM_REF)
577 vn_reference_op_s temp;
579 memset (&temp, 0, sizeof (temp));
580 /* We do not care for spurious type qualifications. */
581 temp.type = TYPE_MAIN_VARIANT (TREE_TYPE (ref));
582 temp.opcode = TREE_CODE (ref);
583 temp.op0 = TMR_INDEX (ref);
584 temp.op1 = TMR_STEP (ref);
585 temp.op2 = TMR_OFFSET (ref);
587 VEC_safe_push (vn_reference_op_s, heap, *result, &temp);
589 memset (&temp, 0, sizeof (temp));
590 temp.type = NULL_TREE;
591 temp.opcode = ERROR_MARK;
592 temp.op0 = TMR_INDEX2 (ref);
594 VEC_safe_push (vn_reference_op_s, heap, *result, &temp);
596 memset (&temp, 0, sizeof (temp));
597 temp.type = NULL_TREE;
598 temp.opcode = TREE_CODE (TMR_BASE (ref));
599 temp.op0 = TMR_BASE (ref);
601 VEC_safe_push (vn_reference_op_s, heap, *result, &temp);
605 /* For non-calls, store the information that makes up the address. */
609 vn_reference_op_s temp;
611 memset (&temp, 0, sizeof (temp));
612 /* We do not care for spurious type qualifications. */
613 temp.type = TYPE_MAIN_VARIANT (TREE_TYPE (ref));
614 temp.opcode = TREE_CODE (ref);
620 /* The base address gets its own vn_reference_op_s structure. */
621 temp.op0 = TREE_OPERAND (ref, 1);
622 if (host_integerp (TREE_OPERAND (ref, 1), 0))
623 temp.off = TREE_INT_CST_LOW (TREE_OPERAND (ref, 1));
626 /* Record bits and position. */
627 temp.op0 = TREE_OPERAND (ref, 1);
628 temp.op1 = TREE_OPERAND (ref, 2);
631 /* The field decl is enough to unambiguously specify the field,
632 a matching type is not necessary and a mismatching type
633 is always a spurious difference. */
634 temp.type = NULL_TREE;
635 temp.op0 = TREE_OPERAND (ref, 1);
636 temp.op1 = TREE_OPERAND (ref, 2);
638 tree this_offset = component_ref_field_offset (ref);
640 && TREE_CODE (this_offset) == INTEGER_CST)
642 tree bit_offset = DECL_FIELD_BIT_OFFSET (TREE_OPERAND (ref, 1));
643 if (TREE_INT_CST_LOW (bit_offset) % BITS_PER_UNIT == 0)
646 = double_int_add (tree_to_double_int (this_offset),
648 (tree_to_double_int (bit_offset),
650 ? 3 : exact_log2 (BITS_PER_UNIT),
651 HOST_BITS_PER_DOUBLE_INT, true));
652 if (double_int_fits_in_shwi_p (off))
658 case ARRAY_RANGE_REF:
660 /* Record index as operand. */
661 temp.op0 = TREE_OPERAND (ref, 1);
662 /* Always record lower bounds and element size. */
663 temp.op1 = array_ref_low_bound (ref);
664 temp.op2 = array_ref_element_size (ref);
665 if (TREE_CODE (temp.op0) == INTEGER_CST
666 && TREE_CODE (temp.op1) == INTEGER_CST
667 && TREE_CODE (temp.op2) == INTEGER_CST)
669 double_int off = tree_to_double_int (temp.op0);
670 off = double_int_add (off,
672 (tree_to_double_int (temp.op1)));
673 off = double_int_mul (off, tree_to_double_int (temp.op2));
674 if (double_int_fits_in_shwi_p (off))
692 if (is_gimple_min_invariant (ref))
698 /* These are only interesting for their operands, their
699 existence, and their type. They will never be the last
700 ref in the chain of references (IE they require an
701 operand), so we don't have to put anything
702 for op* as it will be handled by the iteration */
704 case VIEW_CONVERT_EXPR:
708 /* This is only interesting for its constant offset. */
709 temp.off = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (TREE_TYPE (ref)));
714 VEC_safe_push (vn_reference_op_s, heap, *result, &temp);
716 if (REFERENCE_CLASS_P (ref)
717 || (TREE_CODE (ref) == ADDR_EXPR
718 && !is_gimple_min_invariant (ref)))
719 ref = TREE_OPERAND (ref, 0);
725 /* Build a alias-oracle reference abstraction in *REF from the vn_reference
726 operands in *OPS, the reference alias set SET and the reference type TYPE.
727 Return true if something useful was produced. */
730 ao_ref_init_from_vn_reference (ao_ref *ref,
731 alias_set_type set, tree type,
732 VEC (vn_reference_op_s, heap) *ops)
734 vn_reference_op_t op;
736 tree base = NULL_TREE;
738 HOST_WIDE_INT offset = 0;
739 HOST_WIDE_INT max_size;
740 HOST_WIDE_INT size = -1;
741 tree size_tree = NULL_TREE;
742 alias_set_type base_alias_set = -1;
744 /* First get the final access size from just the outermost expression. */
745 op = VEC_index (vn_reference_op_s, ops, 0);
746 if (op->opcode == COMPONENT_REF)
747 size_tree = DECL_SIZE (op->op0);
748 else if (op->opcode == BIT_FIELD_REF)
752 enum machine_mode mode = TYPE_MODE (type);
754 size_tree = TYPE_SIZE (type);
756 size = GET_MODE_BITSIZE (mode);
758 if (size_tree != NULL_TREE)
760 if (!host_integerp (size_tree, 1))
763 size = TREE_INT_CST_LOW (size_tree);
766 /* Initially, maxsize is the same as the accessed element size.
767 In the following it will only grow (or become -1). */
770 /* Compute cumulative bit-offset for nested component-refs and array-refs,
771 and find the ultimate containing object. */
772 FOR_EACH_VEC_ELT (vn_reference_op_s, ops, i, op)
776 /* These may be in the reference ops, but we cannot do anything
777 sensible with them here. */
779 /* Apart from ADDR_EXPR arguments to MEM_REF. */
780 if (base != NULL_TREE
781 && TREE_CODE (base) == MEM_REF
783 && DECL_P (TREE_OPERAND (op->op0, 0)))
785 vn_reference_op_t pop = VEC_index (vn_reference_op_s, ops, i-1);
786 base = TREE_OPERAND (op->op0, 0);
793 offset += pop->off * BITS_PER_UNIT;
801 /* Record the base objects. */
803 base_alias_set = get_deref_alias_set (op->op0);
804 *op0_p = build2 (MEM_REF, op->type,
806 op0_p = &TREE_OPERAND (*op0_p, 0);
817 /* And now the usual component-reference style ops. */
819 offset += tree_low_cst (op->op1, 0);
824 tree field = op->op0;
825 /* We do not have a complete COMPONENT_REF tree here so we
826 cannot use component_ref_field_offset. Do the interesting
830 || !host_integerp (DECL_FIELD_OFFSET (field), 1))
834 offset += (TREE_INT_CST_LOW (DECL_FIELD_OFFSET (field))
836 offset += TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (field));
841 case ARRAY_RANGE_REF:
843 /* We recorded the lower bound and the element size. */
844 if (!host_integerp (op->op0, 0)
845 || !host_integerp (op->op1, 0)
846 || !host_integerp (op->op2, 0))
850 HOST_WIDE_INT hindex = TREE_INT_CST_LOW (op->op0);
851 hindex -= TREE_INT_CST_LOW (op->op1);
852 hindex *= TREE_INT_CST_LOW (op->op2);
853 hindex *= BITS_PER_UNIT;
865 case VIEW_CONVERT_EXPR:
882 if (base == NULL_TREE)
885 ref->ref = NULL_TREE;
887 ref->offset = offset;
889 ref->max_size = max_size;
890 ref->ref_alias_set = set;
891 if (base_alias_set != -1)
892 ref->base_alias_set = base_alias_set;
894 ref->base_alias_set = get_alias_set (base);
899 /* Copy the operations present in load/store/call REF into RESULT, a vector of
900 vn_reference_op_s's. */
903 copy_reference_ops_from_call (gimple call,
904 VEC(vn_reference_op_s, heap) **result)
906 vn_reference_op_s temp;
909 /* Copy the type, opcode, function being called and static chain. */
910 memset (&temp, 0, sizeof (temp));
911 temp.type = gimple_call_return_type (call);
912 temp.opcode = CALL_EXPR;
913 temp.op0 = gimple_call_fn (call);
914 temp.op1 = gimple_call_chain (call);
916 VEC_safe_push (vn_reference_op_s, heap, *result, &temp);
918 /* Copy the call arguments. As they can be references as well,
919 just chain them together. */
920 for (i = 0; i < gimple_call_num_args (call); ++i)
922 tree callarg = gimple_call_arg (call, i);
923 copy_reference_ops_from_ref (callarg, result);
927 /* Create a vector of vn_reference_op_s structures from REF, a
928 REFERENCE_CLASS_P tree. The vector is not shared. */
930 static VEC(vn_reference_op_s, heap) *
931 create_reference_ops_from_ref (tree ref)
933 VEC (vn_reference_op_s, heap) *result = NULL;
935 copy_reference_ops_from_ref (ref, &result);
939 /* Create a vector of vn_reference_op_s structures from CALL, a
940 call statement. The vector is not shared. */
942 static VEC(vn_reference_op_s, heap) *
943 create_reference_ops_from_call (gimple call)
945 VEC (vn_reference_op_s, heap) *result = NULL;
947 copy_reference_ops_from_call (call, &result);
951 /* Fold *& at position *I_P in a vn_reference_op_s vector *OPS. Updates
952 *I_P to point to the last element of the replacement. */
954 vn_reference_fold_indirect (VEC (vn_reference_op_s, heap) **ops,
957 unsigned int i = *i_p;
958 vn_reference_op_t op = VEC_index (vn_reference_op_s, *ops, i);
959 vn_reference_op_t mem_op = VEC_index (vn_reference_op_s, *ops, i - 1);
961 HOST_WIDE_INT addr_offset;
963 /* The only thing we have to do is from &OBJ.foo.bar add the offset
964 from .foo.bar to the preceeding MEM_REF offset and replace the
965 address with &OBJ. */
966 addr_base = get_addr_base_and_unit_offset (TREE_OPERAND (op->op0, 0),
968 gcc_checking_assert (addr_base && TREE_CODE (addr_base) != MEM_REF);
969 if (addr_base != op->op0)
971 double_int off = tree_to_double_int (mem_op->op0);
972 off = double_int_sext (off, TYPE_PRECISION (TREE_TYPE (mem_op->op0)));
973 off = double_int_add (off, shwi_to_double_int (addr_offset));
974 mem_op->op0 = double_int_to_tree (TREE_TYPE (mem_op->op0), off);
975 op->op0 = build_fold_addr_expr (addr_base);
976 if (host_integerp (mem_op->op0, 0))
977 mem_op->off = TREE_INT_CST_LOW (mem_op->op0);
983 /* Fold *& at position *I_P in a vn_reference_op_s vector *OPS. Updates
984 *I_P to point to the last element of the replacement. */
986 vn_reference_maybe_forwprop_address (VEC (vn_reference_op_s, heap) **ops,
989 unsigned int i = *i_p;
990 vn_reference_op_t op = VEC_index (vn_reference_op_s, *ops, i);
991 vn_reference_op_t mem_op = VEC_index (vn_reference_op_s, *ops, i - 1);
996 def_stmt = SSA_NAME_DEF_STMT (op->op0);
997 if (!is_gimple_assign (def_stmt))
1000 code = gimple_assign_rhs_code (def_stmt);
1001 if (code != ADDR_EXPR
1002 && code != POINTER_PLUS_EXPR)
1005 off = tree_to_double_int (mem_op->op0);
1006 off = double_int_sext (off, TYPE_PRECISION (TREE_TYPE (mem_op->op0)));
1008 /* The only thing we have to do is from &OBJ.foo.bar add the offset
1009 from .foo.bar to the preceeding MEM_REF offset and replace the
1010 address with &OBJ. */
1011 if (code == ADDR_EXPR)
1013 tree addr, addr_base;
1014 HOST_WIDE_INT addr_offset;
1016 addr = gimple_assign_rhs1 (def_stmt);
1017 addr_base = get_addr_base_and_unit_offset (TREE_OPERAND (addr, 0),
1020 || TREE_CODE (addr_base) != MEM_REF)
1023 off = double_int_add (off, shwi_to_double_int (addr_offset));
1024 off = double_int_add (off, mem_ref_offset (addr_base));
1025 op->op0 = TREE_OPERAND (addr_base, 0);
1030 ptr = gimple_assign_rhs1 (def_stmt);
1031 ptroff = gimple_assign_rhs2 (def_stmt);
1032 if (TREE_CODE (ptr) != SSA_NAME
1033 || TREE_CODE (ptroff) != INTEGER_CST)
1036 off = double_int_add (off, tree_to_double_int (ptroff));
1040 mem_op->op0 = double_int_to_tree (TREE_TYPE (mem_op->op0), off);
1041 if (host_integerp (mem_op->op0, 0))
1042 mem_op->off = TREE_INT_CST_LOW (mem_op->op0);
1045 if (TREE_CODE (op->op0) == SSA_NAME)
1046 op->op0 = SSA_VAL (op->op0);
1047 if (TREE_CODE (op->op0) != SSA_NAME)
1048 op->opcode = TREE_CODE (op->op0);
1051 if (TREE_CODE (op->op0) == SSA_NAME)
1052 vn_reference_maybe_forwprop_address (ops, i_p);
1053 else if (TREE_CODE (op->op0) == ADDR_EXPR)
1054 vn_reference_fold_indirect (ops, i_p);
1057 /* Optimize the reference REF to a constant if possible or return
1058 NULL_TREE if not. */
1061 fully_constant_vn_reference_p (vn_reference_t ref)
1063 VEC (vn_reference_op_s, heap) *operands = ref->operands;
1064 vn_reference_op_t op;
1066 /* Try to simplify the translated expression if it is
1067 a call to a builtin function with at most two arguments. */
1068 op = VEC_index (vn_reference_op_s, operands, 0);
1069 if (op->opcode == CALL_EXPR
1070 && TREE_CODE (op->op0) == ADDR_EXPR
1071 && TREE_CODE (TREE_OPERAND (op->op0, 0)) == FUNCTION_DECL
1072 && DECL_BUILT_IN (TREE_OPERAND (op->op0, 0))
1073 && VEC_length (vn_reference_op_s, operands) >= 2
1074 && VEC_length (vn_reference_op_s, operands) <= 3)
1076 vn_reference_op_t arg0, arg1 = NULL;
1077 bool anyconst = false;
1078 arg0 = VEC_index (vn_reference_op_s, operands, 1);
1079 if (VEC_length (vn_reference_op_s, operands) > 2)
1080 arg1 = VEC_index (vn_reference_op_s, operands, 2);
1081 if (TREE_CODE_CLASS (arg0->opcode) == tcc_constant
1082 || (arg0->opcode == ADDR_EXPR
1083 && is_gimple_min_invariant (arg0->op0)))
1086 && (TREE_CODE_CLASS (arg1->opcode) == tcc_constant
1087 || (arg1->opcode == ADDR_EXPR
1088 && is_gimple_min_invariant (arg1->op0))))
1092 tree folded = build_call_expr (TREE_OPERAND (op->op0, 0),
1095 arg1 ? arg1->op0 : NULL);
1097 && TREE_CODE (folded) == NOP_EXPR)
1098 folded = TREE_OPERAND (folded, 0);
1100 && is_gimple_min_invariant (folded))
1105 /* Simplify reads from constant strings. */
1106 else if (op->opcode == ARRAY_REF
1107 && TREE_CODE (op->op0) == INTEGER_CST
1108 && integer_zerop (op->op1)
1109 && VEC_length (vn_reference_op_s, operands) == 2)
1111 vn_reference_op_t arg0;
1112 arg0 = VEC_index (vn_reference_op_s, operands, 1);
1113 if (arg0->opcode == STRING_CST
1114 && (TYPE_MODE (op->type)
1115 == TYPE_MODE (TREE_TYPE (TREE_TYPE (arg0->op0))))
1116 && GET_MODE_CLASS (TYPE_MODE (op->type)) == MODE_INT
1117 && GET_MODE_SIZE (TYPE_MODE (op->type)) == 1
1118 && compare_tree_int (op->op0, TREE_STRING_LENGTH (arg0->op0)) < 0)
1119 return build_int_cst_type (op->type,
1120 (TREE_STRING_POINTER (arg0->op0)
1121 [TREE_INT_CST_LOW (op->op0)]));
1127 /* Transform any SSA_NAME's in a vector of vn_reference_op_s
1128 structures into their value numbers. This is done in-place, and
1129 the vector passed in is returned. */
1131 static VEC (vn_reference_op_s, heap) *
1132 valueize_refs (VEC (vn_reference_op_s, heap) *orig)
1134 vn_reference_op_t vro;
1137 FOR_EACH_VEC_ELT (vn_reference_op_s, orig, i, vro)
1139 if (vro->opcode == SSA_NAME
1140 || (vro->op0 && TREE_CODE (vro->op0) == SSA_NAME))
1142 vro->op0 = SSA_VAL (vro->op0);
1143 /* If it transforms from an SSA_NAME to a constant, update
1145 if (TREE_CODE (vro->op0) != SSA_NAME && vro->opcode == SSA_NAME)
1146 vro->opcode = TREE_CODE (vro->op0);
1148 if (vro->op1 && TREE_CODE (vro->op1) == SSA_NAME)
1149 vro->op1 = SSA_VAL (vro->op1);
1150 if (vro->op2 && TREE_CODE (vro->op2) == SSA_NAME)
1151 vro->op2 = SSA_VAL (vro->op2);
1152 /* If it transforms from an SSA_NAME to an address, fold with
1153 a preceding indirect reference. */
1156 && TREE_CODE (vro->op0) == ADDR_EXPR
1157 && VEC_index (vn_reference_op_s,
1158 orig, i - 1)->opcode == MEM_REF)
1159 vn_reference_fold_indirect (&orig, &i);
1161 && vro->opcode == SSA_NAME
1162 && VEC_index (vn_reference_op_s,
1163 orig, i - 1)->opcode == MEM_REF)
1164 vn_reference_maybe_forwprop_address (&orig, &i);
1165 /* If it transforms a non-constant ARRAY_REF into a constant
1166 one, adjust the constant offset. */
1167 else if (vro->opcode == ARRAY_REF
1169 && TREE_CODE (vro->op0) == INTEGER_CST
1170 && TREE_CODE (vro->op1) == INTEGER_CST
1171 && TREE_CODE (vro->op2) == INTEGER_CST)
1173 double_int off = tree_to_double_int (vro->op0);
1174 off = double_int_add (off,
1176 (tree_to_double_int (vro->op1)));
1177 off = double_int_mul (off, tree_to_double_int (vro->op2));
1178 if (double_int_fits_in_shwi_p (off))
1186 static VEC(vn_reference_op_s, heap) *shared_lookup_references;
1188 /* Create a vector of vn_reference_op_s structures from REF, a
1189 REFERENCE_CLASS_P tree. The vector is shared among all callers of
1192 static VEC(vn_reference_op_s, heap) *
1193 valueize_shared_reference_ops_from_ref (tree ref)
1197 VEC_truncate (vn_reference_op_s, shared_lookup_references, 0);
1198 copy_reference_ops_from_ref (ref, &shared_lookup_references);
1199 shared_lookup_references = valueize_refs (shared_lookup_references);
1200 return shared_lookup_references;
1203 /* Create a vector of vn_reference_op_s structures from CALL, a
1204 call statement. The vector is shared among all callers of
1207 static VEC(vn_reference_op_s, heap) *
1208 valueize_shared_reference_ops_from_call (gimple call)
1212 VEC_truncate (vn_reference_op_s, shared_lookup_references, 0);
1213 copy_reference_ops_from_call (call, &shared_lookup_references);
1214 shared_lookup_references = valueize_refs (shared_lookup_references);
1215 return shared_lookup_references;
1218 /* Lookup a SCCVN reference operation VR in the current hash table.
1219 Returns the resulting value number if it exists in the hash table,
1220 NULL_TREE otherwise. VNRESULT will be filled in with the actual
1221 vn_reference_t stored in the hashtable if something is found. */
1224 vn_reference_lookup_1 (vn_reference_t vr, vn_reference_t *vnresult)
1229 hash = vr->hashcode;
1230 slot = htab_find_slot_with_hash (current_info->references, vr,
1232 if (!slot && current_info == optimistic_info)
1233 slot = htab_find_slot_with_hash (valid_info->references, vr,
1238 *vnresult = (vn_reference_t)*slot;
1239 return ((vn_reference_t)*slot)->result;
1245 static tree *last_vuse_ptr;
1247 /* Callback for walk_non_aliased_vuses. Adjusts the vn_reference_t VR_
1248 with the current VUSE and performs the expression lookup. */
1251 vn_reference_lookup_2 (ao_ref *op ATTRIBUTE_UNUSED, tree vuse, void *vr_)
1253 vn_reference_t vr = (vn_reference_t)vr_;
1258 *last_vuse_ptr = vuse;
1260 /* Fixup vuse and hash. */
1262 vr->hashcode = vr->hashcode - SSA_NAME_VERSION (vr->vuse);
1263 vr->vuse = SSA_VAL (vuse);
1265 vr->hashcode = vr->hashcode + SSA_NAME_VERSION (vr->vuse);
1267 hash = vr->hashcode;
1268 slot = htab_find_slot_with_hash (current_info->references, vr,
1270 if (!slot && current_info == optimistic_info)
1271 slot = htab_find_slot_with_hash (valid_info->references, vr,
1279 /* Callback for walk_non_aliased_vuses. Tries to perform a lookup
1280 from the statement defining VUSE and if not successful tries to
1281 translate *REFP and VR_ through an aggregate copy at the defintion
1285 vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_)
1287 vn_reference_t vr = (vn_reference_t)vr_;
1288 gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
1291 HOST_WIDE_INT offset, maxsize;
1292 static VEC (vn_reference_op_s, heap) *lhs_ops = NULL;
1294 bool lhs_ref_ok = false;
1296 /* First try to disambiguate after value-replacing in the definitions LHS. */
1297 if (is_gimple_assign (def_stmt))
1299 VEC (vn_reference_op_s, heap) *tem;
1300 tree lhs = gimple_assign_lhs (def_stmt);
1301 /* Avoid re-allocation overhead. */
1302 VEC_truncate (vn_reference_op_s, lhs_ops, 0);
1303 copy_reference_ops_from_ref (lhs, &lhs_ops);
1305 lhs_ops = valueize_refs (lhs_ops);
1306 gcc_assert (lhs_ops == tem);
1307 lhs_ref_ok = ao_ref_init_from_vn_reference (&lhs_ref, get_alias_set (lhs),
1308 TREE_TYPE (lhs), lhs_ops);
1310 && !refs_may_alias_p_1 (ref, &lhs_ref, true))
1314 base = ao_ref_base (ref);
1315 offset = ref->offset;
1316 maxsize = ref->max_size;
1318 /* If we cannot constrain the size of the reference we cannot
1319 test if anything kills it. */
1323 /* def_stmt may-defs *ref. See if we can derive a value for *ref
1324 from that defintion.
1326 if (is_gimple_reg_type (vr->type)
1327 && is_gimple_call (def_stmt)
1328 && (fndecl = gimple_call_fndecl (def_stmt))
1329 && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
1330 && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_MEMSET
1331 && integer_zerop (gimple_call_arg (def_stmt, 1))
1332 && host_integerp (gimple_call_arg (def_stmt, 2), 1)
1333 && TREE_CODE (gimple_call_arg (def_stmt, 0)) == ADDR_EXPR)
1335 tree ref2 = TREE_OPERAND (gimple_call_arg (def_stmt, 0), 0);
1337 HOST_WIDE_INT offset2, size2, maxsize2;
1338 base2 = get_ref_base_and_extent (ref2, &offset2, &size2, &maxsize2);
1339 size2 = TREE_INT_CST_LOW (gimple_call_arg (def_stmt, 2)) * 8;
1340 if ((unsigned HOST_WIDE_INT)size2 / 8
1341 == TREE_INT_CST_LOW (gimple_call_arg (def_stmt, 2))
1342 && operand_equal_p (base, base2, 0)
1343 && offset2 <= offset
1344 && offset2 + size2 >= offset + maxsize)
1346 tree val = build_zero_cst (vr->type);
1347 unsigned int value_id = get_or_alloc_constant_value_id (val);
1348 return vn_reference_insert_pieces (vuse, vr->set, vr->type,
1349 VEC_copy (vn_reference_op_s,
1350 heap, vr->operands),
1355 /* 2) Assignment from an empty CONSTRUCTOR. */
1356 else if (is_gimple_reg_type (vr->type)
1357 && gimple_assign_single_p (def_stmt)
1358 && gimple_assign_rhs_code (def_stmt) == CONSTRUCTOR
1359 && CONSTRUCTOR_NELTS (gimple_assign_rhs1 (def_stmt)) == 0)
1362 HOST_WIDE_INT offset2, size2, maxsize2;
1363 base2 = get_ref_base_and_extent (gimple_assign_lhs (def_stmt),
1364 &offset2, &size2, &maxsize2);
1365 if (operand_equal_p (base, base2, 0)
1366 && offset2 <= offset
1367 && offset2 + size2 >= offset + maxsize)
1369 tree val = build_zero_cst (vr->type);
1370 unsigned int value_id = get_or_alloc_constant_value_id (val);
1371 return vn_reference_insert_pieces (vuse, vr->set, vr->type,
1372 VEC_copy (vn_reference_op_s,
1373 heap, vr->operands),
1378 /* For aggregate copies translate the reference through them if
1379 the copy kills ref. */
1380 else if (gimple_assign_single_p (def_stmt)
1381 && (DECL_P (gimple_assign_rhs1 (def_stmt))
1382 || TREE_CODE (gimple_assign_rhs1 (def_stmt)) == MEM_REF
1383 || handled_component_p (gimple_assign_rhs1 (def_stmt))))
1386 HOST_WIDE_INT offset2, size2;
1388 VEC (vn_reference_op_s, heap) *rhs = NULL;
1389 vn_reference_op_t vro;
1395 /* See if the assignment kills REF. */
1396 base2 = ao_ref_base (&lhs_ref);
1397 offset2 = lhs_ref.offset;
1398 size2 = lhs_ref.size;
1400 && !operand_equal_p (base, base2, 0))
1402 || offset2 + size2 < offset + maxsize)
1405 /* Find the common base of ref and the lhs. lhs_ops already
1406 contains valueized operands for the lhs. */
1407 i = VEC_length (vn_reference_op_s, vr->operands) - 1;
1408 j = VEC_length (vn_reference_op_s, lhs_ops) - 1;
1409 while (j >= 0 && i >= 0
1410 && vn_reference_op_eq (VEC_index (vn_reference_op_s,
1412 VEC_index (vn_reference_op_s, lhs_ops, j)))
1418 /* i now points to the first additional op.
1419 ??? LHS may not be completely contained in VR, one or more
1420 VIEW_CONVERT_EXPRs could be in its way. We could at least
1421 try handling outermost VIEW_CONVERT_EXPRs. */
1425 /* Now re-write REF to be based on the rhs of the assignment. */
1426 copy_reference_ops_from_ref (gimple_assign_rhs1 (def_stmt), &rhs);
1427 /* We need to pre-pend vr->operands[0..i] to rhs. */
1428 if (i + 1 + VEC_length (vn_reference_op_s, rhs)
1429 > VEC_length (vn_reference_op_s, vr->operands))
1431 VEC (vn_reference_op_s, heap) *old = vr->operands;
1432 VEC_safe_grow (vn_reference_op_s, heap, vr->operands,
1433 i + 1 + VEC_length (vn_reference_op_s, rhs));
1434 if (old == shared_lookup_references
1435 && vr->operands != old)
1436 shared_lookup_references = NULL;
1439 VEC_truncate (vn_reference_op_s, vr->operands,
1440 i + 1 + VEC_length (vn_reference_op_s, rhs));
1441 FOR_EACH_VEC_ELT (vn_reference_op_s, rhs, j, vro)
1442 VEC_replace (vn_reference_op_s, vr->operands, i + 1 + j, vro);
1443 VEC_free (vn_reference_op_s, heap, rhs);
1444 vr->hashcode = vn_reference_compute_hash (vr);
1446 /* Adjust *ref from the new operands. */
1447 if (!ao_ref_init_from_vn_reference (&r, vr->set, vr->type, vr->operands))
1449 /* This can happen with bitfields. */
1450 if (ref->size != r.size)
1454 /* Do not update last seen VUSE after translating. */
1455 last_vuse_ptr = NULL;
1457 /* Keep looking for the adjusted *REF / VR pair. */
1461 /* Bail out and stop walking. */
1465 /* Lookup a reference operation by it's parts, in the current hash table.
1466 Returns the resulting value number if it exists in the hash table,
1467 NULL_TREE otherwise. VNRESULT will be filled in with the actual
1468 vn_reference_t stored in the hashtable if something is found. */
1471 vn_reference_lookup_pieces (tree vuse, alias_set_type set, tree type,
1472 VEC (vn_reference_op_s, heap) *operands,
1473 vn_reference_t *vnresult, bool maywalk)
1475 struct vn_reference_s vr1;
1483 vr1.vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
1484 VEC_truncate (vn_reference_op_s, shared_lookup_references, 0);
1485 VEC_safe_grow (vn_reference_op_s, heap, shared_lookup_references,
1486 VEC_length (vn_reference_op_s, operands));
1487 memcpy (VEC_address (vn_reference_op_s, shared_lookup_references),
1488 VEC_address (vn_reference_op_s, operands),
1489 sizeof (vn_reference_op_s)
1490 * VEC_length (vn_reference_op_s, operands));
1491 vr1.operands = operands = shared_lookup_references
1492 = valueize_refs (shared_lookup_references);
1495 vr1.hashcode = vn_reference_compute_hash (&vr1);
1496 if ((cst = fully_constant_vn_reference_p (&vr1)))
1499 vn_reference_lookup_1 (&vr1, vnresult);
1505 if (ao_ref_init_from_vn_reference (&r, set, type, vr1.operands))
1507 (vn_reference_t)walk_non_aliased_vuses (&r, vr1.vuse,
1508 vn_reference_lookup_2,
1509 vn_reference_lookup_3, &vr1);
1510 if (vr1.operands != operands)
1511 VEC_free (vn_reference_op_s, heap, vr1.operands);
1515 return (*vnresult)->result;
1520 /* Lookup OP in the current hash table, and return the resulting value
1521 number if it exists in the hash table. Return NULL_TREE if it does
1522 not exist in the hash table or if the result field of the structure
1523 was NULL.. VNRESULT will be filled in with the vn_reference_t
1524 stored in the hashtable if one exists. */
1527 vn_reference_lookup (tree op, tree vuse, bool maywalk,
1528 vn_reference_t *vnresult)
1530 VEC (vn_reference_op_s, heap) *operands;
1531 struct vn_reference_s vr1;
1537 vr1.vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
1538 vr1.operands = operands = valueize_shared_reference_ops_from_ref (op);
1539 vr1.type = TREE_TYPE (op);
1540 vr1.set = get_alias_set (op);
1541 vr1.hashcode = vn_reference_compute_hash (&vr1);
1542 if ((cst = fully_constant_vn_reference_p (&vr1)))
1548 vn_reference_t wvnresult;
1550 ao_ref_init (&r, op);
1552 (vn_reference_t)walk_non_aliased_vuses (&r, vr1.vuse,
1553 vn_reference_lookup_2,
1554 vn_reference_lookup_3, &vr1);
1555 if (vr1.operands != operands)
1556 VEC_free (vn_reference_op_s, heap, vr1.operands);
1560 *vnresult = wvnresult;
1561 return wvnresult->result;
1567 return vn_reference_lookup_1 (&vr1, vnresult);
1571 /* Insert OP into the current hash table with a value number of
1572 RESULT, and return the resulting reference structure we created. */
1575 vn_reference_insert (tree op, tree result, tree vuse)
1580 vr1 = (vn_reference_t) pool_alloc (current_info->references_pool);
1581 if (TREE_CODE (result) == SSA_NAME)
1582 vr1->value_id = VN_INFO (result)->value_id;
1584 vr1->value_id = get_or_alloc_constant_value_id (result);
1585 vr1->vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
1586 vr1->operands = valueize_refs (create_reference_ops_from_ref (op));
1587 vr1->type = TREE_TYPE (op);
1588 vr1->set = get_alias_set (op);
1589 vr1->hashcode = vn_reference_compute_hash (vr1);
1590 vr1->result = TREE_CODE (result) == SSA_NAME ? SSA_VAL (result) : result;
1592 slot = htab_find_slot_with_hash (current_info->references, vr1, vr1->hashcode,
1595 /* Because we lookup stores using vuses, and value number failures
1596 using the vdefs (see visit_reference_op_store for how and why),
1597 it's possible that on failure we may try to insert an already
1598 inserted store. This is not wrong, there is no ssa name for a
1599 store that we could use as a differentiator anyway. Thus, unlike
1600 the other lookup functions, you cannot gcc_assert (!*slot)
1603 /* But free the old slot in case of a collision. */
1605 free_reference (*slot);
1611 /* Insert a reference by it's pieces into the current hash table with
1612 a value number of RESULT. Return the resulting reference
1613 structure we created. */
1616 vn_reference_insert_pieces (tree vuse, alias_set_type set, tree type,
1617 VEC (vn_reference_op_s, heap) *operands,
1618 tree result, unsigned int value_id)
1624 vr1 = (vn_reference_t) pool_alloc (current_info->references_pool);
1625 vr1->value_id = value_id;
1626 vr1->vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
1627 vr1->operands = valueize_refs (operands);
1630 vr1->hashcode = vn_reference_compute_hash (vr1);
1631 if (result && TREE_CODE (result) == SSA_NAME)
1632 result = SSA_VAL (result);
1633 vr1->result = result;
1635 slot = htab_find_slot_with_hash (current_info->references, vr1, vr1->hashcode,
1638 /* At this point we should have all the things inserted that we have
1639 seen before, and we should never try inserting something that
1641 gcc_assert (!*slot);
1643 free_reference (*slot);
1649 /* Compute and return the hash value for nary operation VBO1. */
1652 vn_nary_op_compute_hash (const vn_nary_op_t vno1)
1657 for (i = 0; i < vno1->length; ++i)
1658 if (TREE_CODE (vno1->op[i]) == SSA_NAME)
1659 vno1->op[i] = SSA_VAL (vno1->op[i]);
1661 if (vno1->length == 2
1662 && commutative_tree_code (vno1->opcode)
1663 && tree_swap_operands_p (vno1->op[0], vno1->op[1], false))
1665 tree temp = vno1->op[0];
1666 vno1->op[0] = vno1->op[1];
1670 hash = iterative_hash_hashval_t (vno1->opcode, 0);
1671 for (i = 0; i < vno1->length; ++i)
1672 hash = iterative_hash_expr (vno1->op[i], hash);
1677 /* Return the computed hashcode for nary operation P1. */
1680 vn_nary_op_hash (const void *p1)
1682 const_vn_nary_op_t const vno1 = (const_vn_nary_op_t) p1;
1683 return vno1->hashcode;
1686 /* Compare nary operations P1 and P2 and return true if they are
1690 vn_nary_op_eq (const void *p1, const void *p2)
1692 const_vn_nary_op_t const vno1 = (const_vn_nary_op_t) p1;
1693 const_vn_nary_op_t const vno2 = (const_vn_nary_op_t) p2;
1696 if (vno1->hashcode != vno2->hashcode)
1699 if (vno1->opcode != vno2->opcode
1700 || !types_compatible_p (vno1->type, vno2->type))
1703 for (i = 0; i < vno1->length; ++i)
1704 if (!expressions_equal_p (vno1->op[i], vno2->op[i]))
1710 /* Initialize VNO from the pieces provided. */
1713 init_vn_nary_op_from_pieces (vn_nary_op_t vno, unsigned int length,
1714 enum tree_code code, tree type, tree op0,
1715 tree op1, tree op2, tree op3)
1718 vno->length = length;
1722 /* The fallthrus here are deliberate. */
1723 case 4: vno->op[3] = op3;
1724 case 3: vno->op[2] = op2;
1725 case 2: vno->op[1] = op1;
1726 case 1: vno->op[0] = op0;
1732 /* Initialize VNO from OP. */
1735 init_vn_nary_op_from_op (vn_nary_op_t vno, tree op)
1739 vno->opcode = TREE_CODE (op);
1740 vno->length = TREE_CODE_LENGTH (TREE_CODE (op));
1741 vno->type = TREE_TYPE (op);
1742 for (i = 0; i < vno->length; ++i)
1743 vno->op[i] = TREE_OPERAND (op, i);
1746 /* Initialize VNO from STMT. */
1749 init_vn_nary_op_from_stmt (vn_nary_op_t vno, gimple stmt)
1753 vno->opcode = gimple_assign_rhs_code (stmt);
1754 vno->length = gimple_num_ops (stmt) - 1;
1755 vno->type = gimple_expr_type (stmt);
1756 for (i = 0; i < vno->length; ++i)
1757 vno->op[i] = gimple_op (stmt, i + 1);
1758 if (vno->opcode == REALPART_EXPR
1759 || vno->opcode == IMAGPART_EXPR
1760 || vno->opcode == VIEW_CONVERT_EXPR)
1761 vno->op[0] = TREE_OPERAND (vno->op[0], 0);
1764 /* Compute the hashcode for VNO and look for it in the hash table;
1765 return the resulting value number if it exists in the hash table.
1766 Return NULL_TREE if it does not exist in the hash table or if the
1767 result field of the operation is NULL. VNRESULT will contain the
1768 vn_nary_op_t from the hashtable if it exists. */
1771 vn_nary_op_lookup_1 (vn_nary_op_t vno, vn_nary_op_t *vnresult)
1778 vno->hashcode = vn_nary_op_compute_hash (vno);
1779 slot = htab_find_slot_with_hash (current_info->nary, vno, vno->hashcode,
1781 if (!slot && current_info == optimistic_info)
1782 slot = htab_find_slot_with_hash (valid_info->nary, vno, vno->hashcode,
1787 *vnresult = (vn_nary_op_t)*slot;
1788 return ((vn_nary_op_t)*slot)->result;
1791 /* Lookup a n-ary operation by its pieces and return the resulting value
1792 number if it exists in the hash table. Return NULL_TREE if it does
1793 not exist in the hash table or if the result field of the operation
1794 is NULL. VNRESULT will contain the vn_nary_op_t from the hashtable
1798 vn_nary_op_lookup_pieces (unsigned int length, enum tree_code code,
1799 tree type, tree op0, tree op1, tree op2,
1800 tree op3, vn_nary_op_t *vnresult)
1802 struct vn_nary_op_s vno1;
1803 init_vn_nary_op_from_pieces (&vno1, length, code, type, op0, op1, op2, op3);
1804 return vn_nary_op_lookup_1 (&vno1, vnresult);
1807 /* Lookup OP in the current hash table, and return the resulting value
1808 number if it exists in the hash table. Return NULL_TREE if it does
1809 not exist in the hash table or if the result field of the operation
1810 is NULL. VNRESULT will contain the vn_nary_op_t from the hashtable
1814 vn_nary_op_lookup (tree op, vn_nary_op_t *vnresult)
1816 struct vn_nary_op_s vno1;
1817 init_vn_nary_op_from_op (&vno1, op);
1818 return vn_nary_op_lookup_1 (&vno1, vnresult);
1821 /* Lookup the rhs of STMT in the current hash table, and return the resulting
1822 value number if it exists in the hash table. Return NULL_TREE if
1823 it does not exist in the hash table. VNRESULT will contain the
1824 vn_nary_op_t from the hashtable if it exists. */
1827 vn_nary_op_lookup_stmt (gimple stmt, vn_nary_op_t *vnresult)
1829 struct vn_nary_op_s vno1;
1830 init_vn_nary_op_from_stmt (&vno1, stmt);
1831 return vn_nary_op_lookup_1 (&vno1, vnresult);
1834 /* Return the size of a vn_nary_op_t with LENGTH operands. */
1837 sizeof_vn_nary_op (unsigned int length)
1839 return sizeof (struct vn_nary_op_s) - sizeof (tree) * (4 - length);
1842 /* Allocate a vn_nary_op_t with LENGTH operands on STACK. */
1845 alloc_vn_nary_op_noinit (unsigned int length, struct obstack *stack)
1847 return (vn_nary_op_t) obstack_alloc (stack, sizeof_vn_nary_op (length));
1850 /* Allocate and initialize a vn_nary_op_t on CURRENT_INFO's
1854 alloc_vn_nary_op (unsigned int length, tree result, unsigned int value_id)
1856 vn_nary_op_t vno1 = alloc_vn_nary_op_noinit (length,
1857 ¤t_info->nary_obstack);
1859 vno1->value_id = value_id;
1860 vno1->length = length;
1861 vno1->result = result;
1866 /* Insert VNO into TABLE. If COMPUTE_HASH is true, then compute
1867 VNO->HASHCODE first. */
1870 vn_nary_op_insert_into (vn_nary_op_t vno, htab_t table, bool compute_hash)
1875 vno->hashcode = vn_nary_op_compute_hash (vno);
1877 slot = htab_find_slot_with_hash (table, vno, vno->hashcode, INSERT);
1878 gcc_assert (!*slot);
1884 /* Insert a n-ary operation into the current hash table using it's
1885 pieces. Return the vn_nary_op_t structure we created and put in
1889 vn_nary_op_insert_pieces (unsigned int length, enum tree_code code,
1890 tree type, tree op0,
1891 tree op1, tree op2, tree op3,
1893 unsigned int value_id)
1897 vno1 = alloc_vn_nary_op (length, result, value_id);
1898 init_vn_nary_op_from_pieces (vno1, length, code, type, op0, op1, op2, op3);
1899 return vn_nary_op_insert_into (vno1, current_info->nary, true);
1902 /* Insert OP into the current hash table with a value number of
1903 RESULT. Return the vn_nary_op_t structure we created and put in
1907 vn_nary_op_insert (tree op, tree result)
1909 unsigned length = TREE_CODE_LENGTH (TREE_CODE (op));
1912 vno1 = alloc_vn_nary_op (length, result, VN_INFO (result)->value_id);
1913 init_vn_nary_op_from_op (vno1, op);
1914 return vn_nary_op_insert_into (vno1, current_info->nary, true);
1917 /* Insert the rhs of STMT into the current hash table with a value number of
1921 vn_nary_op_insert_stmt (gimple stmt, tree result)
1923 unsigned length = gimple_num_ops (stmt) - 1;
1926 vno1 = alloc_vn_nary_op (length, result, VN_INFO (result)->value_id);
1927 init_vn_nary_op_from_stmt (vno1, stmt);
1928 return vn_nary_op_insert_into (vno1, current_info->nary, true);
1931 /* Compute a hashcode for PHI operation VP1 and return it. */
1933 static inline hashval_t
1934 vn_phi_compute_hash (vn_phi_t vp1)
1941 result = vp1->block->index;
1943 /* If all PHI arguments are constants we need to distinguish
1944 the PHI node via its type. */
1945 type = TREE_TYPE (VEC_index (tree, vp1->phiargs, 0));
1946 result += (INTEGRAL_TYPE_P (type)
1947 + (INTEGRAL_TYPE_P (type)
1948 ? TYPE_PRECISION (type) + TYPE_UNSIGNED (type) : 0));
1950 FOR_EACH_VEC_ELT (tree, vp1->phiargs, i, phi1op)
1952 if (phi1op == VN_TOP)
1954 result = iterative_hash_expr (phi1op, result);
1960 /* Return the computed hashcode for phi operation P1. */
1963 vn_phi_hash (const void *p1)
1965 const_vn_phi_t const vp1 = (const_vn_phi_t) p1;
1966 return vp1->hashcode;
1969 /* Compare two phi entries for equality, ignoring VN_TOP arguments. */
1972 vn_phi_eq (const void *p1, const void *p2)
1974 const_vn_phi_t const vp1 = (const_vn_phi_t) p1;
1975 const_vn_phi_t const vp2 = (const_vn_phi_t) p2;
1977 if (vp1->hashcode != vp2->hashcode)
1980 if (vp1->block == vp2->block)
1985 /* If the PHI nodes do not have compatible types
1986 they are not the same. */
1987 if (!types_compatible_p (TREE_TYPE (VEC_index (tree, vp1->phiargs, 0)),
1988 TREE_TYPE (VEC_index (tree, vp2->phiargs, 0))))
1991 /* Any phi in the same block will have it's arguments in the
1992 same edge order, because of how we store phi nodes. */
1993 FOR_EACH_VEC_ELT (tree, vp1->phiargs, i, phi1op)
1995 tree phi2op = VEC_index (tree, vp2->phiargs, i);
1996 if (phi1op == VN_TOP || phi2op == VN_TOP)
1998 if (!expressions_equal_p (phi1op, phi2op))
2006 static VEC(tree, heap) *shared_lookup_phiargs;
2008 /* Lookup PHI in the current hash table, and return the resulting
2009 value number if it exists in the hash table. Return NULL_TREE if
2010 it does not exist in the hash table. */
2013 vn_phi_lookup (gimple phi)
2016 struct vn_phi_s vp1;
2019 VEC_truncate (tree, shared_lookup_phiargs, 0);
2021 /* Canonicalize the SSA_NAME's to their value number. */
2022 for (i = 0; i < gimple_phi_num_args (phi); i++)
2024 tree def = PHI_ARG_DEF (phi, i);
2025 def = TREE_CODE (def) == SSA_NAME ? SSA_VAL (def) : def;
2026 VEC_safe_push (tree, heap, shared_lookup_phiargs, def);
2028 vp1.phiargs = shared_lookup_phiargs;
2029 vp1.block = gimple_bb (phi);
2030 vp1.hashcode = vn_phi_compute_hash (&vp1);
2031 slot = htab_find_slot_with_hash (current_info->phis, &vp1, vp1.hashcode,
2033 if (!slot && current_info == optimistic_info)
2034 slot = htab_find_slot_with_hash (valid_info->phis, &vp1, vp1.hashcode,
2038 return ((vn_phi_t)*slot)->result;
2041 /* Insert PHI into the current hash table with a value number of
2045 vn_phi_insert (gimple phi, tree result)
2048 vn_phi_t vp1 = (vn_phi_t) pool_alloc (current_info->phis_pool);
2050 VEC (tree, heap) *args = NULL;
2052 /* Canonicalize the SSA_NAME's to their value number. */
2053 for (i = 0; i < gimple_phi_num_args (phi); i++)
2055 tree def = PHI_ARG_DEF (phi, i);
2056 def = TREE_CODE (def) == SSA_NAME ? SSA_VAL (def) : def;
2057 VEC_safe_push (tree, heap, args, def);
2059 vp1->value_id = VN_INFO (result)->value_id;
2060 vp1->phiargs = args;
2061 vp1->block = gimple_bb (phi);
2062 vp1->result = result;
2063 vp1->hashcode = vn_phi_compute_hash (vp1);
2065 slot = htab_find_slot_with_hash (current_info->phis, vp1, vp1->hashcode,
2068 /* Because we iterate over phi operations more than once, it's
2069 possible the slot might already exist here, hence no assert.*/
2075 /* Print set of components in strongly connected component SCC to OUT. */
2078 print_scc (FILE *out, VEC (tree, heap) *scc)
2083 fprintf (out, "SCC consists of: ");
2084 FOR_EACH_VEC_ELT (tree, scc, i, var)
2086 print_generic_expr (out, var, 0);
2089 fprintf (out, "\n");
2092 /* Set the value number of FROM to TO, return true if it has changed
2096 set_ssa_val_to (tree from, tree to)
2101 && TREE_CODE (to) == SSA_NAME
2102 && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (to))
2105 /* The only thing we allow as value numbers are VN_TOP, ssa_names
2106 and invariants. So assert that here. */
2107 gcc_assert (to != NULL_TREE
2109 || TREE_CODE (to) == SSA_NAME
2110 || is_gimple_min_invariant (to)));
2112 if (dump_file && (dump_flags & TDF_DETAILS))
2114 fprintf (dump_file, "Setting value number of ");
2115 print_generic_expr (dump_file, from, 0);
2116 fprintf (dump_file, " to ");
2117 print_generic_expr (dump_file, to, 0);
2120 currval = SSA_VAL (from);
2122 if (currval != to && !operand_equal_p (currval, to, OEP_PURE_SAME))
2124 VN_INFO (from)->valnum = to;
2125 if (dump_file && (dump_flags & TDF_DETAILS))
2126 fprintf (dump_file, " (changed)\n");
2129 if (dump_file && (dump_flags & TDF_DETAILS))
2130 fprintf (dump_file, "\n");
2134 /* Set all definitions in STMT to value number to themselves.
2135 Return true if a value number changed. */
2138 defs_to_varying (gimple stmt)
2140 bool changed = false;
2144 FOR_EACH_SSA_DEF_OPERAND (defp, stmt, iter, SSA_OP_ALL_DEFS)
2146 tree def = DEF_FROM_PTR (defp);
2148 VN_INFO (def)->use_processed = true;
2149 changed |= set_ssa_val_to (def, def);
2154 static bool expr_has_constants (tree expr);
2155 static tree valueize_expr (tree expr);
2157 /* Visit a copy between LHS and RHS, return true if the value number
2161 visit_copy (tree lhs, tree rhs)
2163 /* Follow chains of copies to their destination. */
2164 while (TREE_CODE (rhs) == SSA_NAME
2165 && SSA_VAL (rhs) != rhs)
2166 rhs = SSA_VAL (rhs);
2168 /* The copy may have a more interesting constant filled expression
2169 (we don't, since we know our RHS is just an SSA name). */
2170 if (TREE_CODE (rhs) == SSA_NAME)
2172 VN_INFO (lhs)->has_constants = VN_INFO (rhs)->has_constants;
2173 VN_INFO (lhs)->expr = VN_INFO (rhs)->expr;
2176 return set_ssa_val_to (lhs, rhs);
2179 /* Visit a nary operator RHS, value number it, and return true if the
2180 value number of LHS has changed as a result. */
2183 visit_nary_op (tree lhs, gimple stmt)
2185 bool changed = false;
2186 tree result = vn_nary_op_lookup_stmt (stmt, NULL);
2189 changed = set_ssa_val_to (lhs, result);
2192 changed = set_ssa_val_to (lhs, lhs);
2193 vn_nary_op_insert_stmt (stmt, lhs);
2199 /* Visit a call STMT storing into LHS. Return true if the value number
2200 of the LHS has changed as a result. */
2203 visit_reference_op_call (tree lhs, gimple stmt)
2205 bool changed = false;
2206 struct vn_reference_s vr1;
2208 tree vuse = gimple_vuse (stmt);
2210 vr1.vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
2211 vr1.operands = valueize_shared_reference_ops_from_call (stmt);
2212 vr1.type = gimple_expr_type (stmt);
2214 vr1.hashcode = vn_reference_compute_hash (&vr1);
2215 result = vn_reference_lookup_1 (&vr1, NULL);
2218 changed = set_ssa_val_to (lhs, result);
2219 if (TREE_CODE (result) == SSA_NAME
2220 && VN_INFO (result)->has_constants)
2221 VN_INFO (lhs)->has_constants = true;
2227 changed = set_ssa_val_to (lhs, lhs);
2228 vr2 = (vn_reference_t) pool_alloc (current_info->references_pool);
2229 vr2->vuse = vr1.vuse;
2230 vr2->operands = valueize_refs (create_reference_ops_from_call (stmt));
2231 vr2->type = vr1.type;
2233 vr2->hashcode = vr1.hashcode;
2235 slot = htab_find_slot_with_hash (current_info->references,
2236 vr2, vr2->hashcode, INSERT);
2238 free_reference (*slot);
2245 /* Visit a load from a reference operator RHS, part of STMT, value number it,
2246 and return true if the value number of the LHS has changed as a result. */
2249 visit_reference_op_load (tree lhs, tree op, gimple stmt)
2251 bool changed = false;
2255 last_vuse = gimple_vuse (stmt);
2256 last_vuse_ptr = &last_vuse;
2257 result = vn_reference_lookup (op, gimple_vuse (stmt), true, NULL);
2258 last_vuse_ptr = NULL;
2260 /* If we have a VCE, try looking up its operand as it might be stored in
2261 a different type. */
2262 if (!result && TREE_CODE (op) == VIEW_CONVERT_EXPR)
2263 result = vn_reference_lookup (TREE_OPERAND (op, 0), gimple_vuse (stmt),
2266 /* We handle type-punning through unions by value-numbering based
2267 on offset and size of the access. Be prepared to handle a
2268 type-mismatch here via creating a VIEW_CONVERT_EXPR. */
2270 && !useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (op)))
2272 /* We will be setting the value number of lhs to the value number
2273 of VIEW_CONVERT_EXPR <TREE_TYPE (result)> (result).
2274 So first simplify and lookup this expression to see if it
2275 is already available. */
2276 tree val = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (op), result);
2277 if ((CONVERT_EXPR_P (val)
2278 || TREE_CODE (val) == VIEW_CONVERT_EXPR)
2279 && TREE_CODE (TREE_OPERAND (val, 0)) == SSA_NAME)
2281 tree tem = valueize_expr (vn_get_expr_for (TREE_OPERAND (val, 0)));
2282 if ((CONVERT_EXPR_P (tem)
2283 || TREE_CODE (tem) == VIEW_CONVERT_EXPR)
2284 && (tem = fold_unary_ignore_overflow (TREE_CODE (val),
2285 TREE_TYPE (val), tem)))
2289 if (!is_gimple_min_invariant (val)
2290 && TREE_CODE (val) != SSA_NAME)
2291 result = vn_nary_op_lookup (val, NULL);
2292 /* If the expression is not yet available, value-number lhs to
2293 a new SSA_NAME we create. */
2296 result = make_ssa_name (SSA_NAME_VAR (lhs), gimple_build_nop ());
2297 /* Initialize value-number information properly. */
2298 VN_INFO_GET (result)->valnum = result;
2299 VN_INFO (result)->value_id = get_next_value_id ();
2300 VN_INFO (result)->expr = val;
2301 VN_INFO (result)->has_constants = expr_has_constants (val);
2302 VN_INFO (result)->needs_insertion = true;
2303 /* As all "inserted" statements are singleton SCCs, insert
2304 to the valid table. This is strictly needed to
2305 avoid re-generating new value SSA_NAMEs for the same
2306 expression during SCC iteration over and over (the
2307 optimistic table gets cleared after each iteration).
2308 We do not need to insert into the optimistic table, as
2309 lookups there will fall back to the valid table. */
2310 if (current_info == optimistic_info)
2312 current_info = valid_info;
2313 vn_nary_op_insert (val, result);
2314 current_info = optimistic_info;
2317 vn_nary_op_insert (val, result);
2318 if (dump_file && (dump_flags & TDF_DETAILS))
2320 fprintf (dump_file, "Inserting name ");
2321 print_generic_expr (dump_file, result, 0);
2322 fprintf (dump_file, " for expression ");
2323 print_generic_expr (dump_file, val, 0);
2324 fprintf (dump_file, "\n");
2331 changed = set_ssa_val_to (lhs, result);
2332 if (TREE_CODE (result) == SSA_NAME
2333 && VN_INFO (result)->has_constants)
2335 VN_INFO (lhs)->expr = VN_INFO (result)->expr;
2336 VN_INFO (lhs)->has_constants = true;
2341 changed = set_ssa_val_to (lhs, lhs);
2342 vn_reference_insert (op, lhs, last_vuse);
2349 /* Visit a store to a reference operator LHS, part of STMT, value number it,
2350 and return true if the value number of the LHS has changed as a result. */
2353 visit_reference_op_store (tree lhs, tree op, gimple stmt)
2355 bool changed = false;
2357 bool resultsame = false;
2359 /* First we want to lookup using the *vuses* from the store and see
2360 if there the last store to this location with the same address
2363 The vuses represent the memory state before the store. If the
2364 memory state, address, and value of the store is the same as the
2365 last store to this location, then this store will produce the
2366 same memory state as that store.
2368 In this case the vdef versions for this store are value numbered to those
2369 vuse versions, since they represent the same memory state after
2372 Otherwise, the vdefs for the store are used when inserting into
2373 the table, since the store generates a new memory state. */
2375 result = vn_reference_lookup (lhs, gimple_vuse (stmt), false, NULL);
2379 if (TREE_CODE (result) == SSA_NAME)
2380 result = SSA_VAL (result);
2381 if (TREE_CODE (op) == SSA_NAME)
2383 resultsame = expressions_equal_p (result, op);
2386 if (!result || !resultsame)
2390 if (dump_file && (dump_flags & TDF_DETAILS))
2392 fprintf (dump_file, "No store match\n");
2393 fprintf (dump_file, "Value numbering store ");
2394 print_generic_expr (dump_file, lhs, 0);
2395 fprintf (dump_file, " to ");
2396 print_generic_expr (dump_file, op, 0);
2397 fprintf (dump_file, "\n");
2399 /* Have to set value numbers before insert, since insert is
2400 going to valueize the references in-place. */
2401 if ((vdef = gimple_vdef (stmt)))
2403 VN_INFO (vdef)->use_processed = true;
2404 changed |= set_ssa_val_to (vdef, vdef);
2407 /* Do not insert structure copies into the tables. */
2408 if (is_gimple_min_invariant (op)
2409 || is_gimple_reg (op))
2410 vn_reference_insert (lhs, op, vdef);
2414 /* We had a match, so value number the vdef to have the value
2415 number of the vuse it came from. */
2418 if (dump_file && (dump_flags & TDF_DETAILS))
2419 fprintf (dump_file, "Store matched earlier value,"
2420 "value numbering store vdefs to matching vuses.\n");
2422 def = gimple_vdef (stmt);
2423 use = gimple_vuse (stmt);
2425 VN_INFO (def)->use_processed = true;
2426 changed |= set_ssa_val_to (def, SSA_VAL (use));
2432 /* Visit and value number PHI, return true if the value number
2436 visit_phi (gimple phi)
2438 bool changed = false;
2440 tree sameval = VN_TOP;
2441 bool allsame = true;
2444 /* TODO: We could check for this in init_sccvn, and replace this
2445 with a gcc_assert. */
2446 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (PHI_RESULT (phi)))
2447 return set_ssa_val_to (PHI_RESULT (phi), PHI_RESULT (phi));
2449 /* See if all non-TOP arguments have the same value. TOP is
2450 equivalent to everything, so we can ignore it. */
2451 for (i = 0; i < gimple_phi_num_args (phi); i++)
2453 tree def = PHI_ARG_DEF (phi, i);
2455 if (TREE_CODE (def) == SSA_NAME)
2456 def = SSA_VAL (def);
2459 if (sameval == VN_TOP)
2465 if (!expressions_equal_p (def, sameval))
2473 /* If all value numbered to the same value, the phi node has that
2477 if (is_gimple_min_invariant (sameval))
2479 VN_INFO (PHI_RESULT (phi))->has_constants = true;
2480 VN_INFO (PHI_RESULT (phi))->expr = sameval;
2484 VN_INFO (PHI_RESULT (phi))->has_constants = false;
2485 VN_INFO (PHI_RESULT (phi))->expr = sameval;
2488 if (TREE_CODE (sameval) == SSA_NAME)
2489 return visit_copy (PHI_RESULT (phi), sameval);
2491 return set_ssa_val_to (PHI_RESULT (phi), sameval);
2494 /* Otherwise, see if it is equivalent to a phi node in this block. */
2495 result = vn_phi_lookup (phi);
2498 if (TREE_CODE (result) == SSA_NAME)
2499 changed = visit_copy (PHI_RESULT (phi), result);
2501 changed = set_ssa_val_to (PHI_RESULT (phi), result);
2505 vn_phi_insert (phi, PHI_RESULT (phi));
2506 VN_INFO (PHI_RESULT (phi))->has_constants = false;
2507 VN_INFO (PHI_RESULT (phi))->expr = PHI_RESULT (phi);
2508 changed = set_ssa_val_to (PHI_RESULT (phi), PHI_RESULT (phi));
2514 /* Return true if EXPR contains constants. */
2517 expr_has_constants (tree expr)
2519 switch (TREE_CODE_CLASS (TREE_CODE (expr)))
2522 return is_gimple_min_invariant (TREE_OPERAND (expr, 0));
2525 return is_gimple_min_invariant (TREE_OPERAND (expr, 0))
2526 || is_gimple_min_invariant (TREE_OPERAND (expr, 1));
2527 /* Constants inside reference ops are rarely interesting, but
2528 it can take a lot of looking to find them. */
2530 case tcc_declaration:
2533 return is_gimple_min_invariant (expr);
2538 /* Return true if STMT contains constants. */
2541 stmt_has_constants (gimple stmt)
2543 if (gimple_code (stmt) != GIMPLE_ASSIGN)
2546 switch (get_gimple_rhs_class (gimple_assign_rhs_code (stmt)))
2548 case GIMPLE_UNARY_RHS:
2549 return is_gimple_min_invariant (gimple_assign_rhs1 (stmt));
2551 case GIMPLE_BINARY_RHS:
2552 return (is_gimple_min_invariant (gimple_assign_rhs1 (stmt))
2553 || is_gimple_min_invariant (gimple_assign_rhs2 (stmt)));
2554 case GIMPLE_TERNARY_RHS:
2555 return (is_gimple_min_invariant (gimple_assign_rhs1 (stmt))
2556 || is_gimple_min_invariant (gimple_assign_rhs2 (stmt))
2557 || is_gimple_min_invariant (gimple_assign_rhs3 (stmt)));
2558 case GIMPLE_SINGLE_RHS:
2559 /* Constants inside reference ops are rarely interesting, but
2560 it can take a lot of looking to find them. */
2561 return is_gimple_min_invariant (gimple_assign_rhs1 (stmt));
2568 /* Replace SSA_NAMES in expr with their value numbers, and return the
2570 This is performed in place. */
2573 valueize_expr (tree expr)
2575 switch (TREE_CODE_CLASS (TREE_CODE (expr)))
2578 if (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
2579 && SSA_VAL (TREE_OPERAND (expr, 0)) != VN_TOP)
2580 TREE_OPERAND (expr, 0) = SSA_VAL (TREE_OPERAND (expr, 0));
2583 if (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME
2584 && SSA_VAL (TREE_OPERAND (expr, 0)) != VN_TOP)
2585 TREE_OPERAND (expr, 0) = SSA_VAL (TREE_OPERAND (expr, 0));
2586 if (TREE_CODE (TREE_OPERAND (expr, 1)) == SSA_NAME
2587 && SSA_VAL (TREE_OPERAND (expr, 1)) != VN_TOP)
2588 TREE_OPERAND (expr, 1) = SSA_VAL (TREE_OPERAND (expr, 1));
2596 /* Simplify the binary expression RHS, and return the result if
2600 simplify_binary_expression (gimple stmt)
2602 tree result = NULL_TREE;
2603 tree op0 = gimple_assign_rhs1 (stmt);
2604 tree op1 = gimple_assign_rhs2 (stmt);
2606 /* This will not catch every single case we could combine, but will
2607 catch those with constants. The goal here is to simultaneously
2608 combine constants between expressions, but avoid infinite
2609 expansion of expressions during simplification. */
2610 if (TREE_CODE (op0) == SSA_NAME)
2612 if (VN_INFO (op0)->has_constants
2613 || TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)) == tcc_comparison)
2614 op0 = valueize_expr (vn_get_expr_for (op0));
2615 else if (SSA_VAL (op0) != VN_TOP && SSA_VAL (op0) != op0)
2616 op0 = SSA_VAL (op0);
2619 if (TREE_CODE (op1) == SSA_NAME)
2621 if (VN_INFO (op1)->has_constants)
2622 op1 = valueize_expr (vn_get_expr_for (op1));
2623 else if (SSA_VAL (op1) != VN_TOP && SSA_VAL (op1) != op1)
2624 op1 = SSA_VAL (op1);
2627 /* Avoid folding if nothing changed. */
2628 if (op0 == gimple_assign_rhs1 (stmt)
2629 && op1 == gimple_assign_rhs2 (stmt))
2632 fold_defer_overflow_warnings ();
2634 result = fold_binary (gimple_assign_rhs_code (stmt),
2635 gimple_expr_type (stmt), op0, op1);
2637 STRIP_USELESS_TYPE_CONVERSION (result);
2639 fold_undefer_overflow_warnings (result && valid_gimple_rhs_p (result),
2642 /* Make sure result is not a complex expression consisting
2643 of operators of operators (IE (a + b) + (a + c))
2644 Otherwise, we will end up with unbounded expressions if
2645 fold does anything at all. */
2646 if (result && valid_gimple_rhs_p (result))
2652 /* Simplify the unary expression RHS, and return the result if
2656 simplify_unary_expression (gimple stmt)
2658 tree result = NULL_TREE;
2659 tree orig_op0, op0 = gimple_assign_rhs1 (stmt);
2661 /* We handle some tcc_reference codes here that are all
2662 GIMPLE_ASSIGN_SINGLE codes. */
2663 if (gimple_assign_rhs_code (stmt) == REALPART_EXPR
2664 || gimple_assign_rhs_code (stmt) == IMAGPART_EXPR
2665 || gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR)
2666 op0 = TREE_OPERAND (op0, 0);
2668 if (TREE_CODE (op0) != SSA_NAME)
2672 if (VN_INFO (op0)->has_constants)
2673 op0 = valueize_expr (vn_get_expr_for (op0));
2674 else if (gimple_assign_cast_p (stmt)
2675 || gimple_assign_rhs_code (stmt) == REALPART_EXPR
2676 || gimple_assign_rhs_code (stmt) == IMAGPART_EXPR
2677 || gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR)
2679 /* We want to do tree-combining on conversion-like expressions.
2680 Make sure we feed only SSA_NAMEs or constants to fold though. */
2681 tree tem = valueize_expr (vn_get_expr_for (op0));
2682 if (UNARY_CLASS_P (tem)
2683 || BINARY_CLASS_P (tem)
2684 || TREE_CODE (tem) == VIEW_CONVERT_EXPR
2685 || TREE_CODE (tem) == SSA_NAME
2686 || is_gimple_min_invariant (tem))
2690 /* Avoid folding if nothing changed, but remember the expression. */
2691 if (op0 == orig_op0)
2694 result = fold_unary_ignore_overflow (gimple_assign_rhs_code (stmt),
2695 gimple_expr_type (stmt), op0);
2698 STRIP_USELESS_TYPE_CONVERSION (result);
2699 if (valid_gimple_rhs_p (result))
2706 /* Try to simplify RHS using equivalences and constant folding. */
2709 try_to_simplify (gimple stmt)
2713 /* For stores we can end up simplifying a SSA_NAME rhs. Just return
2714 in this case, there is no point in doing extra work. */
2715 if (gimple_assign_copy_p (stmt)
2716 && TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME)
2719 switch (TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)))
2721 case tcc_declaration:
2722 tem = get_symbol_constant_value (gimple_assign_rhs1 (stmt));
2728 /* Do not do full-blown reference lookup here, but simplify
2729 reads from constant aggregates. */
2730 tem = fold_const_aggregate_ref (gimple_assign_rhs1 (stmt));
2734 /* Fallthrough for some codes that can operate on registers. */
2735 if (!(TREE_CODE (gimple_assign_rhs1 (stmt)) == REALPART_EXPR
2736 || TREE_CODE (gimple_assign_rhs1 (stmt)) == IMAGPART_EXPR
2737 || TREE_CODE (gimple_assign_rhs1 (stmt)) == VIEW_CONVERT_EXPR))
2739 /* We could do a little more with unary ops, if they expand
2740 into binary ops, but it's debatable whether it is worth it. */
2742 return simplify_unary_expression (stmt);
2744 case tcc_comparison:
2746 return simplify_binary_expression (stmt);
2755 /* Visit and value number USE, return true if the value number
2759 visit_use (tree use)
2761 bool changed = false;
2762 gimple stmt = SSA_NAME_DEF_STMT (use);
2764 VN_INFO (use)->use_processed = true;
2766 gcc_assert (!SSA_NAME_IN_FREE_LIST (use));
2767 if (dump_file && (dump_flags & TDF_DETAILS)
2768 && !SSA_NAME_IS_DEFAULT_DEF (use))
2770 fprintf (dump_file, "Value numbering ");
2771 print_generic_expr (dump_file, use, 0);
2772 fprintf (dump_file, " stmt = ");
2773 print_gimple_stmt (dump_file, stmt, 0, 0);
2776 /* Handle uninitialized uses. */
2777 if (SSA_NAME_IS_DEFAULT_DEF (use))
2778 changed = set_ssa_val_to (use, use);
2781 if (gimple_code (stmt) == GIMPLE_PHI)
2782 changed = visit_phi (stmt);
2783 else if (!gimple_has_lhs (stmt)
2784 || gimple_has_volatile_ops (stmt)
2785 || stmt_could_throw_p (stmt))
2786 changed = defs_to_varying (stmt);
2787 else if (is_gimple_assign (stmt))
2789 tree lhs = gimple_assign_lhs (stmt);
2792 /* Shortcut for copies. Simplifying copies is pointless,
2793 since we copy the expression and value they represent. */
2794 if (gimple_assign_copy_p (stmt)
2795 && TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
2796 && TREE_CODE (lhs) == SSA_NAME)
2798 changed = visit_copy (lhs, gimple_assign_rhs1 (stmt));
2801 simplified = try_to_simplify (stmt);
2804 if (dump_file && (dump_flags & TDF_DETAILS))
2806 fprintf (dump_file, "RHS ");
2807 print_gimple_expr (dump_file, stmt, 0, 0);
2808 fprintf (dump_file, " simplified to ");
2809 print_generic_expr (dump_file, simplified, 0);
2810 if (TREE_CODE (lhs) == SSA_NAME)
2811 fprintf (dump_file, " has constants %d\n",
2812 expr_has_constants (simplified));
2814 fprintf (dump_file, "\n");
2817 /* Setting value numbers to constants will occasionally
2818 screw up phi congruence because constants are not
2819 uniquely associated with a single ssa name that can be
2822 && is_gimple_min_invariant (simplified)
2823 && TREE_CODE (lhs) == SSA_NAME)
2825 VN_INFO (lhs)->expr = simplified;
2826 VN_INFO (lhs)->has_constants = true;
2827 changed = set_ssa_val_to (lhs, simplified);
2831 && TREE_CODE (simplified) == SSA_NAME
2832 && TREE_CODE (lhs) == SSA_NAME)
2834 changed = visit_copy (lhs, simplified);
2837 else if (simplified)
2839 if (TREE_CODE (lhs) == SSA_NAME)
2841 VN_INFO (lhs)->has_constants = expr_has_constants (simplified);
2842 /* We have to unshare the expression or else
2843 valuizing may change the IL stream. */
2844 VN_INFO (lhs)->expr = unshare_expr (simplified);
2847 else if (stmt_has_constants (stmt)
2848 && TREE_CODE (lhs) == SSA_NAME)
2849 VN_INFO (lhs)->has_constants = true;
2850 else if (TREE_CODE (lhs) == SSA_NAME)
2852 /* We reset expr and constantness here because we may
2853 have been value numbering optimistically, and
2854 iterating. They may become non-constant in this case,
2855 even if they were optimistically constant. */
2857 VN_INFO (lhs)->has_constants = false;
2858 VN_INFO (lhs)->expr = NULL_TREE;
2861 if ((TREE_CODE (lhs) == SSA_NAME
2862 /* We can substitute SSA_NAMEs that are live over
2863 abnormal edges with their constant value. */
2864 && !(gimple_assign_copy_p (stmt)
2865 && is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))
2867 && is_gimple_min_invariant (simplified))
2868 && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
2869 /* Stores or copies from SSA_NAMEs that are live over
2870 abnormal edges are a problem. */
2871 || (gimple_assign_single_p (stmt)
2872 && TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
2873 && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt))))
2874 changed = defs_to_varying (stmt);
2875 else if (REFERENCE_CLASS_P (lhs) || DECL_P (lhs))
2877 changed = visit_reference_op_store (lhs, gimple_assign_rhs1 (stmt), stmt);
2879 else if (TREE_CODE (lhs) == SSA_NAME)
2881 if ((gimple_assign_copy_p (stmt)
2882 && is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))
2884 && is_gimple_min_invariant (simplified)))
2886 VN_INFO (lhs)->has_constants = true;
2888 changed = set_ssa_val_to (lhs, simplified);
2890 changed = set_ssa_val_to (lhs, gimple_assign_rhs1 (stmt));
2894 switch (get_gimple_rhs_class (gimple_assign_rhs_code (stmt)))
2896 case GIMPLE_UNARY_RHS:
2897 case GIMPLE_BINARY_RHS:
2898 case GIMPLE_TERNARY_RHS:
2899 changed = visit_nary_op (lhs, stmt);
2901 case GIMPLE_SINGLE_RHS:
2902 switch (TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)))
2905 /* VOP-less references can go through unary case. */
2906 if ((gimple_assign_rhs_code (stmt) == REALPART_EXPR
2907 || gimple_assign_rhs_code (stmt) == IMAGPART_EXPR
2908 || gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR)
2909 && TREE_CODE (TREE_OPERAND (gimple_assign_rhs1 (stmt), 0)) == SSA_NAME)
2911 changed = visit_nary_op (lhs, stmt);
2915 case tcc_declaration:
2916 changed = visit_reference_op_load
2917 (lhs, gimple_assign_rhs1 (stmt), stmt);
2919 case tcc_expression:
2920 if (gimple_assign_rhs_code (stmt) == ADDR_EXPR)
2922 changed = visit_nary_op (lhs, stmt);
2927 changed = defs_to_varying (stmt);
2931 changed = defs_to_varying (stmt);
2937 changed = defs_to_varying (stmt);
2939 else if (is_gimple_call (stmt))
2941 tree lhs = gimple_call_lhs (stmt);
2943 /* ??? We could try to simplify calls. */
2945 if (stmt_has_constants (stmt)
2946 && TREE_CODE (lhs) == SSA_NAME)
2947 VN_INFO (lhs)->has_constants = true;
2948 else if (TREE_CODE (lhs) == SSA_NAME)
2950 /* We reset expr and constantness here because we may
2951 have been value numbering optimistically, and
2952 iterating. They may become non-constant in this case,
2953 even if they were optimistically constant. */
2954 VN_INFO (lhs)->has_constants = false;
2955 VN_INFO (lhs)->expr = NULL_TREE;
2958 if (TREE_CODE (lhs) == SSA_NAME
2959 && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
2960 changed = defs_to_varying (stmt);
2961 /* ??? We should handle stores from calls. */
2962 else if (TREE_CODE (lhs) == SSA_NAME)
2964 if (gimple_call_flags (stmt) & (ECF_PURE | ECF_CONST))
2965 changed = visit_reference_op_call (lhs, stmt);
2967 changed = defs_to_varying (stmt);
2970 changed = defs_to_varying (stmt);
2977 /* Compare two operands by reverse postorder index */
2980 compare_ops (const void *pa, const void *pb)
2982 const tree opa = *((const tree *)pa);
2983 const tree opb = *((const tree *)pb);
2984 gimple opstmta = SSA_NAME_DEF_STMT (opa);
2985 gimple opstmtb = SSA_NAME_DEF_STMT (opb);
2989 if (gimple_nop_p (opstmta) && gimple_nop_p (opstmtb))
2990 return SSA_NAME_VERSION (opa) - SSA_NAME_VERSION (opb);
2991 else if (gimple_nop_p (opstmta))
2993 else if (gimple_nop_p (opstmtb))
2996 bba = gimple_bb (opstmta);
2997 bbb = gimple_bb (opstmtb);
3000 return SSA_NAME_VERSION (opa) - SSA_NAME_VERSION (opb);
3008 if (gimple_code (opstmta) == GIMPLE_PHI
3009 && gimple_code (opstmtb) == GIMPLE_PHI)
3010 return SSA_NAME_VERSION (opa) - SSA_NAME_VERSION (opb);
3011 else if (gimple_code (opstmta) == GIMPLE_PHI)
3013 else if (gimple_code (opstmtb) == GIMPLE_PHI)
3015 else if (gimple_uid (opstmta) != gimple_uid (opstmtb))
3016 return gimple_uid (opstmta) - gimple_uid (opstmtb);
3018 return SSA_NAME_VERSION (opa) - SSA_NAME_VERSION (opb);
3020 return rpo_numbers[bba->index] - rpo_numbers[bbb->index];
3023 /* Sort an array containing members of a strongly connected component
3024 SCC so that the members are ordered by RPO number.
3025 This means that when the sort is complete, iterating through the
3026 array will give you the members in RPO order. */
3029 sort_scc (VEC (tree, heap) *scc)
3031 VEC_qsort (tree, scc, compare_ops);
3034 /* Insert the no longer used nary ONARY to the hash INFO. */
3037 copy_nary (vn_nary_op_t onary, vn_tables_t info)
3039 size_t size = sizeof_vn_nary_op (onary->length);
3040 vn_nary_op_t nary = alloc_vn_nary_op_noinit (onary->length,
3041 &info->nary_obstack);
3042 memcpy (nary, onary, size);
3043 vn_nary_op_insert_into (nary, info->nary, false);
3046 /* Insert the no longer used phi OPHI to the hash INFO. */
3049 copy_phi (vn_phi_t ophi, vn_tables_t info)
3051 vn_phi_t phi = (vn_phi_t) pool_alloc (info->phis_pool);
3053 memcpy (phi, ophi, sizeof (*phi));
3054 ophi->phiargs = NULL;
3055 slot = htab_find_slot_with_hash (info->phis, phi, phi->hashcode, INSERT);
3056 gcc_assert (!*slot);
3060 /* Insert the no longer used reference OREF to the hash INFO. */
3063 copy_reference (vn_reference_t oref, vn_tables_t info)
3067 ref = (vn_reference_t) pool_alloc (info->references_pool);
3068 memcpy (ref, oref, sizeof (*ref));
3069 oref->operands = NULL;
3070 slot = htab_find_slot_with_hash (info->references, ref, ref->hashcode,
3073 free_reference (*slot);
3077 /* Process a strongly connected component in the SSA graph. */
3080 process_scc (VEC (tree, heap) *scc)
3084 unsigned int iterations = 0;
3085 bool changed = true;
3091 /* If the SCC has a single member, just visit it. */
3092 if (VEC_length (tree, scc) == 1)
3094 tree use = VEC_index (tree, scc, 0);
3095 if (VN_INFO (use)->use_processed)
3097 /* We need to make sure it doesn't form a cycle itself, which can
3098 happen for self-referential PHI nodes. In that case we would
3099 end up inserting an expression with VN_TOP operands into the
3100 valid table which makes us derive bogus equivalences later.
3101 The cheapest way to check this is to assume it for all PHI nodes. */
3102 if (gimple_code (SSA_NAME_DEF_STMT (use)) == GIMPLE_PHI)
3103 /* Fallthru to iteration. */ ;
3111 /* Iterate over the SCC with the optimistic table until it stops
3113 current_info = optimistic_info;
3118 /* As we are value-numbering optimistically we have to
3119 clear the expression tables and the simplified expressions
3120 in each iteration until we converge. */
3121 htab_empty (optimistic_info->nary);
3122 htab_empty (optimistic_info->phis);
3123 htab_empty (optimistic_info->references);
3124 obstack_free (&optimistic_info->nary_obstack, NULL);
3125 gcc_obstack_init (&optimistic_info->nary_obstack);
3126 empty_alloc_pool (optimistic_info->phis_pool);
3127 empty_alloc_pool (optimistic_info->references_pool);
3128 FOR_EACH_VEC_ELT (tree, scc, i, var)
3129 VN_INFO (var)->expr = NULL_TREE;
3130 FOR_EACH_VEC_ELT (tree, scc, i, var)
3131 changed |= visit_use (var);
3134 statistics_histogram_event (cfun, "SCC iterations", iterations);
3136 /* Finally, copy the contents of the no longer used optimistic
3137 table to the valid table. */
3138 FOR_EACH_HTAB_ELEMENT (optimistic_info->nary, nary, vn_nary_op_t, hi)
3139 copy_nary (nary, valid_info);
3140 FOR_EACH_HTAB_ELEMENT (optimistic_info->phis, phi, vn_phi_t, hi)
3141 copy_phi (phi, valid_info);
3142 FOR_EACH_HTAB_ELEMENT (optimistic_info->references, ref, vn_reference_t, hi)
3143 copy_reference (ref, valid_info);
3145 current_info = valid_info;
3148 DEF_VEC_O(ssa_op_iter);
3149 DEF_VEC_ALLOC_O(ssa_op_iter,heap);
3151 /* Pop the components of the found SCC for NAME off the SCC stack
3152 and process them. Returns true if all went well, false if
3153 we run into resource limits. */
3156 extract_and_process_scc_for_name (tree name)
3158 VEC (tree, heap) *scc = NULL;
3161 /* Found an SCC, pop the components off the SCC stack and
3165 x = VEC_pop (tree, sccstack);
3167 VN_INFO (x)->on_sccstack = false;
3168 VEC_safe_push (tree, heap, scc, x);
3169 } while (x != name);
3171 /* Bail out of SCCVN in case a SCC turns out to be incredibly large. */
3172 if (VEC_length (tree, scc)
3173 > (unsigned)PARAM_VALUE (PARAM_SCCVN_MAX_SCC_SIZE))
3176 fprintf (dump_file, "WARNING: Giving up with SCCVN due to "
3177 "SCC size %u exceeding %u\n", VEC_length (tree, scc),
3178 (unsigned)PARAM_VALUE (PARAM_SCCVN_MAX_SCC_SIZE));
3182 if (VEC_length (tree, scc) > 1)
3185 if (dump_file && (dump_flags & TDF_DETAILS))
3186 print_scc (dump_file, scc);
3190 VEC_free (tree, heap, scc);
3195 /* Depth first search on NAME to discover and process SCC's in the SSA
3197 Execution of this algorithm relies on the fact that the SCC's are
3198 popped off the stack in topological order.
3199 Returns true if successful, false if we stopped processing SCC's due
3200 to resource constraints. */
3205 VEC(ssa_op_iter, heap) *itervec = NULL;
3206 VEC(tree, heap) *namevec = NULL;
3207 use_operand_p usep = NULL;
3214 VN_INFO (name)->dfsnum = next_dfs_num++;
3215 VN_INFO (name)->visited = true;
3216 VN_INFO (name)->low = VN_INFO (name)->dfsnum;
3218 VEC_safe_push (tree, heap, sccstack, name);
3219 VN_INFO (name)->on_sccstack = true;
3220 defstmt = SSA_NAME_DEF_STMT (name);
3222 /* Recursively DFS on our operands, looking for SCC's. */
3223 if (!gimple_nop_p (defstmt))
3225 /* Push a new iterator. */
3226 if (gimple_code (defstmt) == GIMPLE_PHI)
3227 usep = op_iter_init_phiuse (&iter, defstmt, SSA_OP_ALL_USES);
3229 usep = op_iter_init_use (&iter, defstmt, SSA_OP_ALL_USES);
3232 clear_and_done_ssa_iter (&iter);
3236 /* If we are done processing uses of a name, go up the stack
3237 of iterators and process SCCs as we found them. */
3238 if (op_iter_done (&iter))
3240 /* See if we found an SCC. */
3241 if (VN_INFO (name)->low == VN_INFO (name)->dfsnum)
3242 if (!extract_and_process_scc_for_name (name))
3244 VEC_free (tree, heap, namevec);
3245 VEC_free (ssa_op_iter, heap, itervec);
3249 /* Check if we are done. */
3250 if (VEC_empty (tree, namevec))
3252 VEC_free (tree, heap, namevec);
3253 VEC_free (ssa_op_iter, heap, itervec);
3257 /* Restore the last use walker and continue walking there. */
3259 name = VEC_pop (tree, namevec);
3260 memcpy (&iter, VEC_last (ssa_op_iter, itervec),
3261 sizeof (ssa_op_iter));
3262 VEC_pop (ssa_op_iter, itervec);
3263 goto continue_walking;
3266 use = USE_FROM_PTR (usep);
3268 /* Since we handle phi nodes, we will sometimes get
3269 invariants in the use expression. */
3270 if (TREE_CODE (use) == SSA_NAME)
3272 if (! (VN_INFO (use)->visited))
3274 /* Recurse by pushing the current use walking state on
3275 the stack and starting over. */
3276 VEC_safe_push(ssa_op_iter, heap, itervec, &iter);
3277 VEC_safe_push(tree, heap, namevec, name);
3282 VN_INFO (name)->low = MIN (VN_INFO (name)->low,
3283 VN_INFO (use)->low);
3285 if (VN_INFO (use)->dfsnum < VN_INFO (name)->dfsnum
3286 && VN_INFO (use)->on_sccstack)
3288 VN_INFO (name)->low = MIN (VN_INFO (use)->dfsnum,
3289 VN_INFO (name)->low);
3293 usep = op_iter_next_use (&iter);
3297 /* Allocate a value number table. */
3300 allocate_vn_table (vn_tables_t table)
3302 table->phis = htab_create (23, vn_phi_hash, vn_phi_eq, free_phi);
3303 table->nary = htab_create (23, vn_nary_op_hash, vn_nary_op_eq, NULL);
3304 table->references = htab_create (23, vn_reference_hash, vn_reference_eq,
3307 gcc_obstack_init (&table->nary_obstack);
3308 table->phis_pool = create_alloc_pool ("VN phis",
3309 sizeof (struct vn_phi_s),
3311 table->references_pool = create_alloc_pool ("VN references",
3312 sizeof (struct vn_reference_s),
3316 /* Free a value number table. */
3319 free_vn_table (vn_tables_t table)
3321 htab_delete (table->phis);
3322 htab_delete (table->nary);
3323 htab_delete (table->references);
3324 obstack_free (&table->nary_obstack, NULL);
3325 free_alloc_pool (table->phis_pool);
3326 free_alloc_pool (table->references_pool);
3334 int *rpo_numbers_temp;
3336 calculate_dominance_info (CDI_DOMINATORS);
3338 constant_to_value_id = htab_create (23, vn_constant_hash, vn_constant_eq,
3341 constant_value_ids = BITMAP_ALLOC (NULL);
3346 vn_ssa_aux_table = VEC_alloc (vn_ssa_aux_t, heap, num_ssa_names + 1);
3347 /* VEC_alloc doesn't actually grow it to the right size, it just
3348 preallocates the space to do so. */
3349 VEC_safe_grow_cleared (vn_ssa_aux_t, heap, vn_ssa_aux_table, num_ssa_names + 1);
3350 gcc_obstack_init (&vn_ssa_aux_obstack);
3352 shared_lookup_phiargs = NULL;
3353 shared_lookup_references = NULL;
3354 rpo_numbers = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS);
3355 rpo_numbers_temp = XCNEWVEC (int, last_basic_block + NUM_FIXED_BLOCKS);
3356 pre_and_rev_post_order_compute (NULL, rpo_numbers_temp, false);
3358 /* RPO numbers is an array of rpo ordering, rpo[i] = bb means that
3359 the i'th block in RPO order is bb. We want to map bb's to RPO
3360 numbers, so we need to rearrange this array. */
3361 for (j = 0; j < n_basic_blocks - NUM_FIXED_BLOCKS; j++)
3362 rpo_numbers[rpo_numbers_temp[j]] = j;
3364 XDELETE (rpo_numbers_temp);
3366 VN_TOP = create_tmp_var_raw (void_type_node, "vn_top");
3368 /* Create the VN_INFO structures, and initialize value numbers to
3370 for (i = 0; i < num_ssa_names; i++)
3372 tree name = ssa_name (i);
3375 VN_INFO_GET (name)->valnum = VN_TOP;
3376 VN_INFO (name)->expr = NULL_TREE;
3377 VN_INFO (name)->value_id = 0;
3381 renumber_gimple_stmt_uids ();
3383 /* Create the valid and optimistic value numbering tables. */
3384 valid_info = XCNEW (struct vn_tables_s);
3385 allocate_vn_table (valid_info);
3386 optimistic_info = XCNEW (struct vn_tables_s);
3387 allocate_vn_table (optimistic_info);
3395 htab_delete (constant_to_value_id);
3396 BITMAP_FREE (constant_value_ids);
3397 VEC_free (tree, heap, shared_lookup_phiargs);
3398 VEC_free (vn_reference_op_s, heap, shared_lookup_references);
3399 XDELETEVEC (rpo_numbers);
3401 for (i = 0; i < num_ssa_names; i++)
3403 tree name = ssa_name (i);
3405 && VN_INFO (name)->needs_insertion)
3406 release_ssa_name (name);
3408 obstack_free (&vn_ssa_aux_obstack, NULL);
3409 VEC_free (vn_ssa_aux_t, heap, vn_ssa_aux_table);
3411 VEC_free (tree, heap, sccstack);
3412 free_vn_table (valid_info);
3413 XDELETE (valid_info);
3414 free_vn_table (optimistic_info);
3415 XDELETE (optimistic_info);
3418 /* Set *ID if we computed something useful in RESULT. */
3421 set_value_id_for_result (tree result, unsigned int *id)
3425 if (TREE_CODE (result) == SSA_NAME)
3426 *id = VN_INFO (result)->value_id;
3427 else if (is_gimple_min_invariant (result))
3428 *id = get_or_alloc_constant_value_id (result);
3432 /* Set the value ids in the valid hash tables. */
3435 set_hashtable_value_ids (void)
3442 /* Now set the value ids of the things we had put in the hash
3445 FOR_EACH_HTAB_ELEMENT (valid_info->nary,
3446 vno, vn_nary_op_t, hi)
3447 set_value_id_for_result (vno->result, &vno->value_id);
3449 FOR_EACH_HTAB_ELEMENT (valid_info->phis,
3451 set_value_id_for_result (vp->result, &vp->value_id);
3453 FOR_EACH_HTAB_ELEMENT (valid_info->references,
3454 vr, vn_reference_t, hi)
3455 set_value_id_for_result (vr->result, &vr->value_id);
3458 /* Do SCCVN. Returns true if it finished, false if we bailed out
3459 due to resource constraints. */
3466 bool changed = true;
3469 current_info = valid_info;
3471 for (param = DECL_ARGUMENTS (current_function_decl);
3473 param = DECL_CHAIN (param))
3475 if (gimple_default_def (cfun, param) != NULL)
3477 tree def = gimple_default_def (cfun, param);
3478 VN_INFO (def)->valnum = def;
3482 for (i = 1; i < num_ssa_names; ++i)
3484 tree name = ssa_name (i);
3486 && VN_INFO (name)->visited == false
3487 && !has_zero_uses (name))
3495 /* Initialize the value ids. */
3497 for (i = 1; i < num_ssa_names; ++i)
3499 tree name = ssa_name (i);
3503 info = VN_INFO (name);
3504 if (info->valnum == name
3505 || info->valnum == VN_TOP)
3506 info->value_id = get_next_value_id ();
3507 else if (is_gimple_min_invariant (info->valnum))
3508 info->value_id = get_or_alloc_constant_value_id (info->valnum);
3511 /* Propagate until they stop changing. */
3515 for (i = 1; i < num_ssa_names; ++i)
3517 tree name = ssa_name (i);
3521 info = VN_INFO (name);
3522 if (TREE_CODE (info->valnum) == SSA_NAME
3523 && info->valnum != name
3524 && info->value_id != VN_INFO (info->valnum)->value_id)
3527 info->value_id = VN_INFO (info->valnum)->value_id;
3532 set_hashtable_value_ids ();
3534 if (dump_file && (dump_flags & TDF_DETAILS))
3536 fprintf (dump_file, "Value numbers:\n");
3537 for (i = 0; i < num_ssa_names; i++)
3539 tree name = ssa_name (i);
3541 && VN_INFO (name)->visited
3542 && SSA_VAL (name) != name)
3544 print_generic_expr (dump_file, name, 0);
3545 fprintf (dump_file, " = ");
3546 print_generic_expr (dump_file, SSA_VAL (name), 0);
3547 fprintf (dump_file, "\n");
3555 /* Return the maximum value id we have ever seen. */
3558 get_max_value_id (void)
3560 return next_value_id;
3563 /* Return the next unique value id. */
3566 get_next_value_id (void)
3568 return next_value_id++;
3572 /* Compare two expressions E1 and E2 and return true if they are equal. */
3575 expressions_equal_p (tree e1, tree e2)
3577 /* The obvious case. */
3581 /* If only one of them is null, they cannot be equal. */
3585 /* Now perform the actual comparison. */
3586 if (TREE_CODE (e1) == TREE_CODE (e2)
3587 && operand_equal_p (e1, e2, OEP_PURE_SAME))
3594 /* Return true if the nary operation NARY may trap. This is a copy
3595 of stmt_could_throw_1_p adjusted to the SCCVN IL. */
3598 vn_nary_may_trap (vn_nary_op_t nary)
3601 tree rhs2 = NULL_TREE;
3602 bool honor_nans = false;
3603 bool honor_snans = false;
3604 bool fp_operation = false;
3605 bool honor_trapv = false;
3609 if (TREE_CODE_CLASS (nary->opcode) == tcc_comparison
3610 || TREE_CODE_CLASS (nary->opcode) == tcc_unary
3611 || TREE_CODE_CLASS (nary->opcode) == tcc_binary)
3614 fp_operation = FLOAT_TYPE_P (type);
3617 honor_nans = flag_trapping_math && !flag_finite_math_only;
3618 honor_snans = flag_signaling_nans != 0;
3620 else if (INTEGRAL_TYPE_P (type)
3621 && TYPE_OVERFLOW_TRAPS (type))
3624 if (nary->length >= 2)
3626 ret = operation_could_trap_helper_p (nary->opcode, fp_operation,
3628 honor_nans, honor_snans, rhs2,
3634 for (i = 0; i < nary->length; ++i)
3635 if (tree_could_trap_p (nary->op[i]))