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* [gcc r14-1715] Fix disambiguation against .MASK_STORE
@ 2023-06-12 13:19 Richard Biener
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From: Richard Biener @ 2023-06-12 13:19 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:8d3eb3ad5388d2f523e4a6f886c4b3364f77f51f
commit r14-1715-g8d3eb3ad5388d2f523e4a6f886c4b3364f77f51f
Author: Richard Biener <rguenther@suse.de>
Date: Mon Jun 12 14:09:45 2023 +0200
Fix disambiguation against .MASK_STORE
Alias analysis was treating .MASK_STORE as storing a full vector
which means we disambiguate against decls of smaller than vector size.
That's of course wrong and a similar issue was fixed for DSE already.
The following makes sure we set the size of the access to unknown
and only constrain max_size.
This fixes runtime execution FAILs of gfortran.dg/matmul_2.f90,
gfortran.dg/matmul_6.f90 and gfortran.dg/pr91577.f90 when using
AVX512 with full masked loop vectorization on Zen4.
* tree-ssa-alias.cc (call_may_clobber_ref_p_1): For
.MASK_STORE and friend set the size of the access to
unknown.
Diff:
---
gcc/tree-ssa-alias.cc | 3 +++
1 file changed, 3 insertions(+)
diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc
index 79ed956e300..b5476e8b41e 100644
--- a/gcc/tree-ssa-alias.cc
+++ b/gcc/tree-ssa-alias.cc
@@ -3072,6 +3072,9 @@ call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref, bool tbaa_p)
ao_ref lhs_ref;
ao_ref_init_from_ptr_and_size (&lhs_ref, gimple_call_arg (call, 0),
TYPE_SIZE_UNIT (TREE_TYPE (rhs)));
+ /* We cannot make this a known-size access since otherwise
+ we disambiguate against stores to decls that are smaller. */
+ lhs_ref.size = -1;
lhs_ref.ref_alias_set = lhs_ref.base_alias_set
= tbaa_p ? get_deref_alias_set
(TREE_TYPE (gimple_call_arg (call, 1))) : 0;
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