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tree-optimization/108821 - store motion and volatiles

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The following fixes store motion to not re-issue volatile stores
to preserve TBAA behavior since that will result in the number
of volatile accesses changing.

	PR tree-optimization/108821
	* tree-ssa-loop-im.cc (sm_seq_valid_bb): We can also not
	move volatile accesses.

	* gcc.dg/tree-ssa/ssa-lim-24.c: New testcase.
This commit is contained in:
Richard Biener 2023-02-17 12:36:44 +01:00
parent 417e95263c
commit 4c4f0f7acd
2 changed files with 28 additions and 1 deletions
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25
gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-24.c Normal file
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@ -0,0 +1,25 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-lim2-details -fdump-tree-optimized" } */
extern volatile int *x;
static int gCrc;
static int __attribute__((noinline)) crc16Add(int crc, int b)
{
return crc + b;
}
void f(int data, int dataSz)
{
int i;
for(i=0;i<dataSz;i++)
{
gCrc = crc16Add(gCrc, data);
*x = data;
}
}
/* { dg-final { scan-tree-dump "Executing store motion of gCrc" "lim2" } } */
/* { dg-final { scan-tree-dump-not "Re-issueing" "lim2" } } */
/* { dg-final { scan-tree-dump-times "\\*x" 1 "optimized" } } */

4
gcc/tree-ssa-loop-im.cc
View file

@ -2605,7 +2605,9 @@ sm_seq_valid_bb (class loop *loop, basic_block bb, tree vdef,
if (data->ref == UNANALYZABLE_MEM_ID)
return -1;
/* Stop at memory references which we can't move. */
else if (memory_accesses.refs_list[data->ref]->mem.ref == error_mark_node)
else if (memory_accesses.refs_list[data->ref]->mem.ref == error_mark_node
|| TREE_THIS_VOLATILE
(memory_accesses.refs_list[data->ref]->mem.ref))
{
/* Mark refs_not_in_seq as unsupported. */
bitmap_ior_into (refs_not_supported, refs_not_in_seq);