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gimple-ssa-strength-reduction.c (valid_mem_ref_cand_p): New function.

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* gimple-ssa-strength-reduction.c (valid_mem_ref_cand_p): New function.
	(replace_ref): Do not replace a chain of only two candidates which are
	valid memory references.

From-SVN: r275297
This commit is contained in:
Eric Botcazou 2019-09-02 08:14:47 +00:00 • committed by Eric Botcazou
parent c746efcab3
commit 0f605e4049
4 changed files with 54 additions and 0 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2019-09-02 Eric Botcazou <ebotcazou@adacore.com>
* gimple-ssa-strength-reduction.c (valid_mem_ref_cand_p): New function.
(replace_ref): Do not replace a chain of only two candidates which are
valid memory references.
2019-09-02 Martin Liska <mliska@suse.cz>
* tree-switch-conversion.c (jump_table_cluster::find_jump_tables):

27
gcc/gimple-ssa-strength-reduction.c
View file

@ -1999,6 +1999,23 @@ replace_ref (tree *expr, slsr_cand_t c)
update_stmt (c->cand_stmt);
}
/* Return true if CAND_REF candidate C is a valid memory reference. */
static bool
valid_mem_ref_cand_p (slsr_cand_t c)
{
if (TREE_CODE (TREE_OPERAND (c->stride, 1)) != INTEGER_CST)
return false;
struct mem_address addr
= { NULL_TREE, c->base_expr, TREE_OPERAND (c->stride, 0),
TREE_OPERAND (c->stride, 1), wide_int_to_tree (sizetype, c->index) };
return
valid_mem_ref_p (TYPE_MODE (c->cand_type), TYPE_ADDR_SPACE (c->cand_type),
&addr);
}
/* Replace CAND_REF candidate C, each sibling of candidate C, and each
dependent of candidate C with an equivalent strength-reduced data
reference. */
@ -2006,6 +2023,16 @@ replace_ref (tree *expr, slsr_cand_t c)
static void
replace_refs (slsr_cand_t c)
{
/* Replacing a chain of only 2 candidates which are valid memory references
is generally counter-productive because you cannot recoup the additional
calculation added in front of them. */
if (c->basis == 0
&& c->dependent
&& !lookup_cand (c->dependent)->dependent
&& valid_mem_ref_cand_p (c)
&& valid_mem_ref_cand_p (lookup_cand (c->dependent)))
return;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fputs ("Replacing reference: ", dump_file);

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
2019-09-02 Eric Botcazou <ebotcazou@adacore.com>
* gcc.dg/tree-ssa/slsr-42.c: New test.
2019-09-02 Martin Liska <mliska@suse.cz>
PR c++/91155

17
gcc/testsuite/gcc.dg/tree-ssa/slsr-42.c Normal file
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@ -0,0 +1,17 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-slsr-details" } */
struct x
{
int a[16];
int b[16];
};
void
set (struct x *p, unsigned int n, int i)
{
p->a[n] = i;
p->b[n] = i;
}
/* { dg-final { scan-tree-dump-not "Replacing reference: " "slsr" { target i?86-*-* x86_64-*-* } } } */