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.

diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc
index b5476e8b41ee3d638790bbe246009a18539ae2d6..e1bc04b82ba398e9916abeb456d5a69e565c5ca8 100644 (file)
--- 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