[backport from gcc-4.7/trunk <mikpe@it.uu.se>]

gcc/

2011-05-23  Richard Guenther  <rguenther@suse.de>

	PR middle-end/15419
	* builtins.c (fold_builtin_memory_op): Be less restrictive about
	what pointer types we accept for folding.

gcc/testsuite/

2011-05-23  Richard Guenther  <rguenther@suse.de>

	PR middle-end/15419
	* gcc.dg/memcpy-3.c: New testcase.

--- gcc-4.6.0/gcc/builtins.c.~1~	2011-03-03 22:56:58.000000000 +0100
+++ gcc-4.6.0/gcc/builtins.c	2011-05-23 21:19:23.000000000 +0200
@@ -8542,6 +8542,9 @@ fold_builtin_memory_op (location_t loc, 
 	 Perhaps we ought to inherit type from non-VOID argument here?  */
       STRIP_NOPS (src);
       STRIP_NOPS (dest);
+      if (!POINTER_TYPE_P (TREE_TYPE (src))
+	  || !POINTER_TYPE_P (TREE_TYPE (dest)))
+	return NULL_TREE;
       /* As we fold (void *)(p + CST) to (void *)p + CST undo this here.  */
       if (TREE_CODE (src) == POINTER_PLUS_EXPR)
 	{
@@ -8558,8 +8561,7 @@ fold_builtin_memory_op (location_t loc, 
 	    dest = build1 (NOP_EXPR, TREE_TYPE (tem), dest);
 	}
       srctype = TREE_TYPE (TREE_TYPE (src));
-      if (srctype
-	  && TREE_CODE (srctype) == ARRAY_TYPE
+      if (TREE_CODE (srctype) == ARRAY_TYPE
 	  && !tree_int_cst_equal (TYPE_SIZE_UNIT (srctype), len))
 	{
 	  srctype = TREE_TYPE (srctype);
@@ -8567,21 +8569,15 @@ fold_builtin_memory_op (location_t loc, 
 	  src = build1 (NOP_EXPR, build_pointer_type (srctype), src);
 	}
       desttype = TREE_TYPE (TREE_TYPE (dest));
-      if (desttype
-	  && TREE_CODE (desttype) == ARRAY_TYPE
+      if (TREE_CODE (desttype) == ARRAY_TYPE
 	  && !tree_int_cst_equal (TYPE_SIZE_UNIT (desttype), len))
 	{
 	  desttype = TREE_TYPE (desttype);
 	  STRIP_NOPS (dest);
 	  dest = build1 (NOP_EXPR, build_pointer_type (desttype), dest);
 	}
-      if (!srctype || !desttype
-	  || TREE_ADDRESSABLE (srctype)
-	  || TREE_ADDRESSABLE (desttype)
-	  || !TYPE_SIZE_UNIT (srctype)
-	  || !TYPE_SIZE_UNIT (desttype)
-	  || TREE_CODE (TYPE_SIZE_UNIT (srctype)) != INTEGER_CST
-	  || TREE_CODE (TYPE_SIZE_UNIT (desttype)) != INTEGER_CST)
+      if (TREE_ADDRESSABLE (srctype)
+	  || TREE_ADDRESSABLE (desttype))
 	return NULL_TREE;
 
       src_align = get_pointer_alignment (src, BIGGEST_ALIGNMENT);
--- gcc-4.6.0/gcc/testsuite/gcc.dg/memcpy-3.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.6.0/gcc/testsuite/gcc.dg/memcpy-3.c	2011-05-23 21:19:23.000000000 +0200
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+int get_int(const void *p)
+{
+  int w;
+  __builtin_memcpy(&w, p, sizeof (int));
+  return w;
+}
+
+/* { dg-final { scan-tree-dump-not "memcpy" "optimized" } } */
+/* { dg-final { scan-tree-dump-times "MEM" 1 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */