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tree-optimization/101293 - further enhance LIMs ref canonicalization

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This makes sure to handle MEM[p + 4] and MEM[p].j with j at offset 4
as the same ref in store motion.  For hashing we need to be
more restrictive in what we handle since there's no poly-int
handlers for inchash.  For comparison we can compare poly_offsets directly.

2021-07-02  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/101293
	* tree-ssa-loop-im.c (mem_ref_hasher::equal): Compare MEM_REF bases
	with combined offsets.
	(gather_mem_refs_stmt): Hash MEM_REFs as if their offset were
	combined with the rest of the offset.

	* gcc.dg/tree-ssa/ssa-lim-15.c: New testcase.
This commit is contained in:
Richard Biener 2021-07-02 12:57:06 +02:00
parent bc8f0ed704
commit 4546f423ec
2 changed files with 41 additions and 4 deletions
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18
gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-15.c Normal file
View File

@ -0,0 +1,18 @@
/* PR/101293 */
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-lim2-details" } */
struct X { int i; int j; };
void foo(struct X *x, int n)
{
for (int i = 0; i < n; ++i)
{
int *p = &x->j;
int tem = *p;
x->j += tem * i;
}
}
/* Make sure LIM can handle unifying MEM[x, 4] and MEM[x].j */
/* { dg-final { scan-tree-dump "Executing store motion" "lim2" } } */

27
gcc/tree-ssa-loop-im.c
View File

@ -194,8 +194,14 @@ mem_ref_hasher::equal (const im_mem_ref *mem1, const ao_ref *obj2)
{
if (obj2->max_size_known_p ())
return (mem1->ref_decomposed
&& operand_equal_p (mem1->mem.base, obj2->base, 0)
&& known_eq (mem1->mem.offset, obj2->offset)
&& ((TREE_CODE (mem1->mem.base) == MEM_REF
&& TREE_CODE (obj2->base) == MEM_REF
&& operand_equal_p (TREE_OPERAND (mem1->mem.base, 0),
TREE_OPERAND (obj2->base, 0), 0)
&& known_eq (mem_ref_offset (mem1->mem.base) * BITS_PER_UNIT + mem1->mem.offset,
mem_ref_offset (obj2->base) * BITS_PER_UNIT + obj2->offset))
|| (operand_equal_p (mem1->mem.base, obj2->base, 0)
&& known_eq (mem1->mem.offset, obj2->offset)))
&& known_eq (mem1->mem.size, obj2->size)
&& known_eq (mem1->mem.max_size, obj2->max_size)
&& mem1->mem.volatile_p == obj2->volatile_p
@ -1500,8 +1506,21 @@ gather_mem_refs_stmt (class loop *loop, gimple *stmt)
&& (mem_base = get_addr_base_and_unit_offset (aor.ref, &mem_off)))
{
ref_decomposed = true;
hash = iterative_hash_expr (ao_ref_base (&aor), 0);
hash = iterative_hash_host_wide_int (offset, hash);
tree base = ao_ref_base (&aor);
poly_int64 moffset;
HOST_WIDE_INT mcoffset;
if (TREE_CODE (base) == MEM_REF
&& (mem_ref_offset (base) * BITS_PER_UNIT + offset).to_shwi (&moffset)
&& moffset.is_constant (&mcoffset))
{
hash = iterative_hash_expr (TREE_OPERAND (base, 0), 0);
hash = iterative_hash_host_wide_int (mcoffset, hash);
}
else
{
hash = iterative_hash_expr (base, 0);
hash = iterative_hash_host_wide_int (offset, hash);
}
hash = iterative_hash_host_wide_int (size, hash);
}
else