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tree-optimization/89317 - another pattern for &p->x != p + 4

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As seen in the original testcase for PR89317 we are missing
comparison simplification patterns for &p->x != p + 4.  Fixed
by making an existing one apply.  To make the pattern apply
during CCP we need to simplify ccp_fold to not use GENERIC
folding of conditions but also use GIMPLE folding.

	PR tree-optimization/89317
	* tree-ssa-ccp.cc (ccp_fold): Handle GIMPLE_COND via
	gimple_fold_stmt_to_constant_1.
	* match.pd (&a != &a + c): Apply to pointer_plus with non-ADDR_EXPR
	base as well.

	* gcc.dg/tree-ssa/pr89317.c: Amend.
This commit is contained in:
Richard Biener 2022-12-12 08:13:33 +01:00
parent 324e995340
commit 2dc5d6b1e7
3 changed files with 19 additions and 11 deletions
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2
gcc/match.pd
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@ -2263,7 +2263,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* (&a + b) !=/== (&a[1] + c) -> (&a[0] - &a[1]) + b !=/== c */
(for neeq (ne eq)
(simplify
(neeq:c ADDR_EXPR@0 (pointer_plus ADDR_EXPR@2 @3))
(neeq:c ADDR_EXPR@0 (pointer_plus @2 @3))
(with { poly_int64 diff; tree inner_type = TREE_TYPE (@3);}
(if (ptr_difference_const (@0, @2, &diff))
(neeq { build_int_cst_type (inner_type, diff); } @3))))

17
gcc/testsuite/gcc.dg/tree-ssa/pr89317.c
View File

@ -10,4 +10,21 @@ int foo (struct b *x)
return b - a;
}
int bar (struct b *x)
{
int *a = x->data;
int *b = ((int*)x) + 4;
if (a != b)
return 1;
return 0;
}
int baz (struct b *x)
{
int *a = x->data;
int *b = ((int*)x) + 4;
return (a != b);
}
/* { dg-final { scan-tree-dump "return 4;" "ccp1" } } */
/* { dg-final { scan-tree-dump-times "return 1;" 2 "ccp1" } } */

11
gcc/tree-ssa-ccp.cc
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@ -1271,24 +1271,15 @@ valueize_op_1 (tree op)
static tree
ccp_fold (gimple *stmt)
{
location_t loc = gimple_location (stmt);
switch (gimple_code (stmt))
{
case GIMPLE_COND:
{
/* Handle comparison operators that can appear in GIMPLE form. */
tree op0 = valueize_op (gimple_cond_lhs (stmt));
tree op1 = valueize_op (gimple_cond_rhs (stmt));
enum tree_code code = gimple_cond_code (stmt);
return fold_binary_loc (loc, code, boolean_type_node, op0, op1);
}
case GIMPLE_SWITCH:
{
/* Return the constant switch index. */
return valueize_op (gimple_switch_index (as_a <gswitch *> (stmt)));
}
case GIMPLE_COND:
case GIMPLE_ASSIGN:
case GIMPLE_CALL:
return gimple_fold_stmt_to_constant_1 (stmt,