tree-optimization/105971 - less surprising refs_may_alias_p_2
When DSE asks whether __real a is using __imag a it gets a surprising
result when a is a FUNCTION_DECL. The following makes sure this case
is less surprising to callers but keeping the bail-out for the
non-decl case where it is true that PTA doesn't track aliases to code
correctly.
2022-06-15 Richard Biener <rguenther@suse.de>
PR tree-optimization/105971
* tree-ssa-alias.cc (refs_may_alias_p_2): Put bail-out for
FUNCTION_DECL and LABEL_DECL refs after decl-decl disambiguation
to leak less surprising alias results.
* gcc.dg/torture/pr106971.c: New testcase.
(cherry picked from commit 8c2733e16e
)
This commit is contained in:
parent
4f34a9e8d5
commit
8dd1c404ec
|
@ -0,0 +1,12 @@
|
|||
/* { dg-do compile } */
|
||||
|
||||
void a()
|
||||
{
|
||||
int b;
|
||||
int c;
|
||||
int d = (__INTPTR_TYPE__)a;
|
||||
_Complex float *e = (_Complex float *)a;
|
||||
for (;;) {
|
||||
(*e += d) / b ?: 0;
|
||||
}
|
||||
}
|
|
@ -2397,15 +2397,6 @@ refs_may_alias_p_2 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
|
|||
|| CONSTANT_CLASS_P (base2))
|
||||
return false;
|
||||
|
||||
/* We can end up referring to code via function and label decls.
|
||||
As we likely do not properly track code aliases conservatively
|
||||
bail out. */
|
||||
if (TREE_CODE (base1) == FUNCTION_DECL
|
||||
|| TREE_CODE (base1) == LABEL_DECL
|
||||
|| TREE_CODE (base2) == FUNCTION_DECL
|
||||
|| TREE_CODE (base2) == LABEL_DECL)
|
||||
return true;
|
||||
|
||||
/* Two volatile accesses always conflict. */
|
||||
if (ref1->volatile_p
|
||||
&& ref2->volatile_p)
|
||||
|
@ -2432,6 +2423,15 @@ refs_may_alias_p_2 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
|
|||
ref2ref, base2, offset2, max_size2,
|
||||
ref2->size);
|
||||
|
||||
/* We can end up referring to code via function and label decls.
|
||||
As we likely do not properly track code aliases conservatively
|
||||
bail out. */
|
||||
if (TREE_CODE (base1) == FUNCTION_DECL
|
||||
|| TREE_CODE (base1) == LABEL_DECL
|
||||
|| TREE_CODE (base2) == FUNCTION_DECL
|
||||
|| TREE_CODE (base2) == LABEL_DECL)
|
||||
return true;
|
||||
|
||||
/* Handle restrict based accesses.
|
||||
??? ao_ref_base strips inner MEM_REF [&decl], recover from that
|
||||
here. */
|
||||
|
|
Loading…
Reference in New Issue