Patchwork Fix PR48978

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Submitter Richard Guenther
Date May 13, 2011, 11 a.m.
Message ID <alpine.LNX.2.00.1105131258080.810@zhemvz.fhfr.qr>
Download mbox | patch
Permalink /patch/95460/
State New
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Comments

Richard Guenther - May 13, 2011, 11 a.m.
The change to pointer and function type hashing has made hashing
a lot weaker (contrary to what I expected) because if either type
resides in a SCC then we do _not_ take the hash of the visited
target types into account (I'm currently trying to think about
a way around that), so we are effectively weakening the hashes
by not hasing the target aggregate name.

Committed to trunk.

Richard.

2011-05-13  Richard Guenther  <rguenther@suse.de>

	PR lto/48978
	* gimple.c (iterative_hash_gimple_type): Revert change in
	pointer target and function result and argument hashing.

Patch

Index: gcc/gimple.c
===================================================================
--- gcc/gimple.c	(revision 173725)
+++ gcc/gimple.c	(working copy)
@@ -4110,10 +4110,20 @@  iterative_hash_gimple_type (tree type, h
     }
 
   /* For pointer and reference types, fold in information about the type
-     pointed to.  */
+     pointed to but do not recurse into possibly incomplete types to
+     avoid hash differences for complete vs. incomplete types.  */
   if (POINTER_TYPE_P (type))
-    v = visit (TREE_TYPE (type), state, v,
-	       sccstack, sccstate, sccstate_obstack);
+    {
+      if (RECORD_OR_UNION_TYPE_P (TREE_TYPE (type)))
+	{
+	  v = iterative_hash_hashval_t (TREE_CODE (TREE_TYPE (type)), v);
+	  v = iterative_hash_name
+		(TYPE_NAME (TYPE_MAIN_VARIANT (TREE_TYPE (type))), v);
+	}
+      else
+	v = visit (TREE_TYPE (type), state, v,
+		   sccstack, sccstate, sccstate_obstack);
+    }
 
   /* For integer types hash the types min/max values and the string flag.  */
   if (TREE_CODE (type) == INTEGER_TYPE)
@@ -4154,13 +4164,29 @@  iterative_hash_gimple_type (tree type, h
 	v = visit (TYPE_METHOD_BASETYPE (type), state, v,
 		   sccstack, sccstate, sccstate_obstack);
 
-      /* Check result and argument types.  */
-      v = visit (TREE_TYPE (type), state, v,
-		 sccstack, sccstate, sccstate_obstack);
+      /* For result types allow mismatch in completeness.  */
+      if (RECORD_OR_UNION_TYPE_P (TREE_TYPE (type)))
+	{
+	  v = iterative_hash_hashval_t (TREE_CODE (TREE_TYPE (type)), v);
+	  v = iterative_hash_name
+		(TYPE_NAME (TYPE_MAIN_VARIANT (TREE_TYPE (type))), v);
+	}
+      else
+	v = visit (TREE_TYPE (type), state, v,
+		   sccstack, sccstate, sccstate_obstack);
+
       for (p = TYPE_ARG_TYPES (type), na = 0; p; p = TREE_CHAIN (p))
 	{
-	  v = visit (TREE_VALUE (p), state, v,
-		     sccstack, sccstate, sccstate_obstack);
+	  /* For argument types allow mismatch in completeness.  */
+	  if (RECORD_OR_UNION_TYPE_P (TREE_VALUE (p)))
+	    {
+	      v = iterative_hash_hashval_t (TREE_CODE (TREE_VALUE (p)), v);
+	      v = iterative_hash_name
+		    (TYPE_NAME (TYPE_MAIN_VARIANT (TREE_VALUE (p))), v);
+	    }
+	  else
+	    v = visit (TREE_VALUE (p), state, v,
+		       sccstack, sccstate, sccstate_obstack);
 	  na++;
 	}