re PR c/21419 (Accepts writting to const via asm)

gcc:
2005-09-29  Paolo Bonzini  <bonzini@gnu.org>

	PR c/21419
	* gimplify.c (gimplify_asm_expr): Raise an error if an output is
	read-only.

testsuite:
2005-09-29  Paolo Bonzini  <bonzini@gnu.org>

        PR c/21419
        * gcc.dg/pr21419.c: New test.

From-SVN: r104774

gcc/ChangeLog

+2005-09-29  Paolo Bonzini  <bonzini@gnu.org>
+
+	PR c/21419
+	* gimplify.c (gimplify_asm_expr): Raise an error if an output is
+	read-only.
+
 2005-09-29  Steven Bosscher  <stevenb@suse.de>
 
 	PR tree-optimization/23911

gcc/gimplify.c

@@ -3544,6 +3544,12 @@ gimplify_asm_expr (tree *expr_p, tree *pre_p, tree *post_p)
       parse_output_constraint (&constraint, i, 0, 0,
 			       &allows_mem, &allows_reg, &is_inout);
 
+      if (TYPE_READONLY (TREE_TYPE (TREE_VALUE (link))))
+	{
+	  error ("invalid lvalue in asm output %d", i);
+	  ret = GS_ERROR;
+	}
+
       if (!allows_reg && allows_mem)
 	lang_hooks.mark_addressable (TREE_VALUE (link));
 

gcc/testsuite/ChangeLog

+2005-09-29  Paolo Bonzini  <bonzini@gnu.org>
+
+        PR c/21419
+        * gcc.dg/pr21419.c: New test.
+
 2005-09-29  Steven Bosscher  <stevenb@suse.de>
 
 	* gcc.dg/pr23911.c: New test.

gcc/testsuite/gcc.dg/pr21419.c

+/* { dg-do compile } */
+const int i = 0;
+
+void f(void)
+{
+  __asm__ __volatile__ ("" : "=m" (i)); /* { dg-error "invalid lvalue in asm output" } */
+
+}
+
+void g(const int set)
+{
+  __asm__ __volatile__ ("" : "=r" (set)); /* { dg-error "invalid lvalue in asm output" } */
+}
+
+