2009-05-03 Richard Guenther <rguenther@suse.de>

	PR middle-end/23329
	* tree-ssa.c (useless_type_conversion_p_1): Use get_deref_alias_set.
	Do not lose casts from array types with unknown extent to array
	types with known extent.
	* tree-ssa-copy.c (may_propagate_copy): Remove hack checking for
	alias set compatibility.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@147082 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 0 insertions, 49 deletions

diff --git a/gcc/tree-ssa-copy.c b/gcc/tree-ssa-copy.c
index f582ed0f996..9dad1cdc940 100644
--- a/gcc/tree-ssa-copy.c
+++ b/gcc/tree-ssa-copy.c
@@ -78,55 +78,6 @@ may_propagate_copy (tree dest, tree orig)
   if (!useless_type_conversion_p (type_d, type_o))
     return false;
 
-  /* FIXME.  GIMPLE is allowing pointer assignments and comparisons of
-     pointers that have different alias sets.  This means that these
-     pointers will have different memory tags associated to them.
-
-     If we allow copy propagation in these cases, statements de-referencing
-     the new pointer will now have a reference to a different memory tag
-     with potentially incorrect SSA information.
-
-     This was showing up in libjava/java/util/zip/ZipFile.java with code
-     like:
-
-     	struct java.io.BufferedInputStream *T.660;
-	struct java.io.BufferedInputStream *T.647;
-	struct java.io.InputStream *is;
-	struct java.io.InputStream *is.662;
-	[ ... ]
-	T.660 = T.647;
-	is = T.660;	<-- This ought to be type-casted
-	is.662 = is;
-
-     Also, f/name.c exposed a similar problem with a COND_EXPR predicate
-     that was causing DOM to generate and equivalence with two pointers of
-     alias-incompatible types:
-
-     	struct _ffename_space *n;
-	struct _ffename *ns;
-	[ ... ]
-	if (n == ns)
-	  goto lab;
-	...
-	lab:
-	return n;
-
-     I think that GIMPLE should emit the appropriate type-casts.  For the
-     time being, blocking copy-propagation in these cases is the safe thing
-     to do.  */
-  if (TREE_CODE (dest) == SSA_NAME
-      && TREE_CODE (orig) == SSA_NAME
-      && POINTER_TYPE_P (type_d)
-      && POINTER_TYPE_P (type_o))
-    {
-      if (get_alias_set (TREE_TYPE (type_d))
-	  != get_alias_set (TREE_TYPE (type_o)))
-	return false;
-      else if (DECL_NO_TBAA_P (SSA_NAME_VAR (dest))
-	       != DECL_NO_TBAA_P (SSA_NAME_VAR (orig)))
-	return false;
-    }
-
   /* Propagating virtual operands is always ok.  */
   if (TREE_CODE (dest) == SSA_NAME && !is_gimple_reg (dest))
     {