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tree-optimization/115701 - fix maybe_duplicate_ssa_info_at_copy

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The following restricts copying of points-to info from defs that
might be in regions invoking UB and are never executed.

	PR tree-optimization/115701
	* tree-ssanames.cc (maybe_duplicate_ssa_info_at_copy):
	Only copy info from within the same BB.

	* gcc.dg/torture/pr115701.c: New testcase.

(cherry picked from commit b77f17c5feec9614568bf2dee7f7d811465ee4a5)
This commit is contained in:
Richard Biener 2024-06-30 11:34:43 +02:00 • committed by Richard Biener
parent 6f74a5f5dc
commit e01012c459
2 changed files with 30 additions and 14 deletions
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22
gcc/testsuite/gcc.dg/torture/pr115701.c Normal file
View file

@ -0,0 +1,22 @@
/* { dg-do run } */
/* IPA PTA disables local PTA recompute after IPA. */
/* { dg-additional-options "-fipa-pta" } */
int a, c, d;
static int b;
int main()
{
int *e = &a, **f = &e;
while (1) {
int **g, ***h = &f;
if (c)
*g = e;
else if (!b)
break;
*e = **g;
e = &d;
}
if (e != &a)
__builtin_abort();
return 0;
}

22
gcc/tree-ssanames.cc
View file

@ -763,25 +763,19 @@ duplicate_ssa_name_range_info (tree name, tree src)
void
maybe_duplicate_ssa_info_at_copy (tree dest, tree src)
{
/* While points-to info is flow-insensitive we have to avoid copying
info from not executed regions invoking UB to dominating defs. */
if (gimple_bb (SSA_NAME_DEF_STMT (src))
!= gimple_bb (SSA_NAME_DEF_STMT (dest)))
return;
if (POINTER_TYPE_P (TREE_TYPE (dest))
&& SSA_NAME_PTR_INFO (dest)
&& ! SSA_NAME_PTR_INFO (src))
{
duplicate_ssa_name_ptr_info (src, SSA_NAME_PTR_INFO (dest));
/* Points-to information is cfg insensitive,
but VRP might record context sensitive alignment
info, non-nullness, etc. So reset context sensitive
info if the two SSA_NAMEs aren't defined in the same
basic block. */
if (gimple_bb (SSA_NAME_DEF_STMT (src))
!= gimple_bb (SSA_NAME_DEF_STMT (dest)))
reset_flow_sensitive_info (src);
}
duplicate_ssa_name_ptr_info (src, SSA_NAME_PTR_INFO (dest));
else if (INTEGRAL_TYPE_P (TREE_TYPE (dest))
&& SSA_NAME_RANGE_INFO (dest)
&& ! SSA_NAME_RANGE_INFO (src)
&& (gimple_bb (SSA_NAME_DEF_STMT (src))
== gimple_bb (SSA_NAME_DEF_STMT (dest))))
&& ! SSA_NAME_RANGE_INFO (src))
duplicate_ssa_name_range_info (src, dest);
}