2010-09-08  Tom de Vries  <tom@codesourcery.com>

	gcc/
	* gcc/emit-rtl.c (set_mem_attributes_minus_bitpos): Set MEM_READONLY_P
	for static const strings.
	* gcc/testsuite/gcc.dg/memcpy-3.c: New test.

 2010-09-13  Andrew Stubbs  <ams@codesourcery.com>
 
 	gcc/

=== modified file 'gcc/emit-rtl.c'
--- old/gcc/emit-rtl.c	2009-11-27 12:00:28 +0000
+++ new/gcc/emit-rtl.c	2010-09-15 16:40:06 +0000
@@ -1648,6 +1648,11 @@
 	  MEM_READONLY_P (ref) = 1;
 	}
 
+      /* Mark static const strings readonly as well.  */
+      if (base && TREE_CODE (base) == STRING_CST && TREE_READONLY (base)
+	  && TREE_STATIC (base))
+	MEM_READONLY_P (ref) = 1;
+
       /* If this expression uses it's parent's alias set, mark it such
 	 that we won't change it.  */
       if (component_uses_parent_alias_set (t))

=== added file 'gcc/testsuite/gcc.dg/memcpy-3.c'
--- old/gcc/testsuite/gcc.dg/memcpy-3.c	1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.dg/memcpy-3.c	2010-09-15 16:40:06 +0000
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-rtl-expand" } */
+
+void
+f1 (char *p)
+{
+  __builtin_memcpy (p, "123", 3);
+}
+
+/* { dg-final { scan-rtl-dump-times "mem/s/u:" 3 "expand" { target mips*-*-* } } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */