Hi,
as discussed on IRC today, after all this patch should be correct. I
have re-tested it with x86_64-linux in the following variant which also
moves load of ptrtype1 that is unnecesarily early.
Bootstrapped/regtested x86_64-linux, OK?
* tree-ssa-alias.c (indirect_ref_may_alias_decl_p): Also give up
TBAA path when base2_alias_set is 0.
Index: tree-ssa-alias.c
===================================================================
--- tree-ssa-alias.c (revision 272614)
+++ tree-ssa-alias.c (working copy)
@@ -1458,10 +1466,8 @@ indirect_ref_may_alias_decl_p (tree ref1
if (!flag_strict_aliasing || !tbaa_p)
return true;
- ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
-
/* If the alias set for a pointer access is zero all bets are off. */
- if (base1_alias_set == 0)
+ if (base1_alias_set == 0 || base2_alias_set == 0)
return true;
/* When we are trying to disambiguate an access with a pointer dereference
@@ -1479,6 +1485,9 @@ indirect_ref_may_alias_decl_p (tree ref1
if (base1_alias_set != base2_alias_set
&& !alias_sets_conflict_p (base1_alias_set, base2_alias_set))
return false;
+
+ ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
+
/* If the size of the access relevant for TBAA through the pointer
is bigger than the size of the decl we can't possibly access the
decl via that pointer. */
