[gcc r13-7443] Fix disambiguation against .MASK_LOAD

[Richard Biener]

https://gcc.gnu.org/g:09c6f003aaad1e94f79e19c2680492e956cca36d

commit r13-7443-g09c6f003aaad1e94f79e19c2680492e956cca36d
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Jun 13 08:52:23 2023 +0200

    Fix disambiguation against .MASK_LOAD
    
    Alias analysis was treating .MASK_LOAD as storing a full vector
    which means we disambiguate against decls of smaller than vector size.
    This complements the previous patch handling .MASK_STORE and fixes
    runtime execution FAILs of gfortran.dg/matmul_3.f90 and
    gfortran.dg/inline_sum_2.f90 when using AVX512 with full masked loop
    vectorization on Zen4.
    
            * tree-ssa-alias.cc (ref_maybe_used_by_call_p_1): For
            .MASK_LOAD and friends set the size of the access to unknown.
    
    (cherry picked from commit 1c3661e224e3ddfc6f773b095740c0f5a7ddf5fc)

Diff:
---
 gcc/tree-ssa-alias.cc | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc
index 89d4f8372b4..f2dc1563ae9 100644
--- a/gcc/tree-ssa-alias.cc
+++ b/gcc/tree-ssa-alias.cc
@@ -2829,6 +2829,9 @@ ref_maybe_used_by_call_p_1 (gcall *call, ao_ref *ref, bool tbaa_p)
 	      ao_ref_init_from_ptr_and_size (&rhs_ref,
 					     gimple_call_arg (call, 0),
 					     TYPE_SIZE_UNIT (TREE_TYPE (lhs)));
+	      /* We cannot make this a known-size access since otherwise
+		 we disambiguate against refs to decls that are smaller.  */
+	      rhs_ref.size = -1;
 	      rhs_ref.ref_alias_set = rhs_ref.base_alias_set
 		= tbaa_p ? get_deref_alias_set (TREE_TYPE
 					(gimple_call_arg (call, 1))) : 0;
@@ -3073,7 +3076,7 @@ call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref, bool tbaa_p)
 	  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.  */
+	     we disambiguate against refs 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