emit-rtl.c (set_mem_attributes_minus_bitpos): Set MEM_READONLY_P for static const strings.

2011-10-13  Tom de Vries  <tom@codesourcery.com>

	* emit-rtl.c (set_mem_attributes_minus_bitpos): Set MEM_READONLY_P
	for static const strings.
	* varasm.c (build_constant_desc): Generate the memory location of the
	constant using gen_const_mem.

From-SVN: r179896

gcc/ChangeLog

+2011-10-13  Tom de Vries  <tom@codesourcery.com>
+
+	* emit-rtl.c (set_mem_attributes_minus_bitpos): Set MEM_READONLY_P
+	for static const strings.
+	* varasm.c (build_constant_desc): Generate the memory location of the
+	constant using gen_const_mem.
+
 2011-10-13  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/50698

gcc/emit-rtl.c

@@ -1696,6 +1696,12 @@ set_mem_attributes_minus_bitpos (rtx ref, tree t, int objectp,
 	  && !TREE_THIS_VOLATILE (base))
 	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))

gcc/varasm.c

@@ -3119,7 +3119,7 @@ build_constant_desc (tree exp)
   SET_SYMBOL_REF_DECL (symbol, decl);
   TREE_CONSTANT_POOL_ADDRESS_P (symbol) = 1;
 
-  rtl = gen_rtx_MEM (TYPE_MODE (TREE_TYPE (exp)), symbol);
+  rtl = gen_const_mem (TYPE_MODE (TREE_TYPE (exp)), symbol);
   set_mem_attributes (rtl, exp, 1);
   set_mem_alias_set (rtl, 0);
   set_mem_alias_set (rtl, const_alias_set);