re PR middle-end/21595 (__builtin_constant_p(&"Hello"[0]) is true for C but not for...

2005-05-17  Richard Guenther  <rguenth@gcc.gnu.org>

	PR middle-end/21595
	* builtins.c (fold_builtin_constant_p): Handle
	&"string cst"[0] as constant.

	* g++.dg/tree-ssa/builtin1.C: New testcase.

From-SVN: r99825

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 82233e9ee9bba1a77c0b6dd2b67fd850e0050af5..449a1b49c257a5c4304c6936c3f94b598636c039 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2005-05-17  Richard Guenther  <rguenth@gcc.gnu.org>
+
+       PR middle-end/21595
+       * builtins.c (fold_builtin_constant_p): Handle
+       &"string cst"[0] as constant.
+
 2005-05-17  Richard Henderson  <rth@redhat.com>
 
        * config/i386/sse.md (mulv16qi3, mulv2di3): New.

diff --git a/gcc/builtins.c b/gcc/builtins.c
index 8d4fc3379fd8d5c92497375347e75c3362ced0cf..cdc5cebcbc6dea3bcc5c076ebbde0bd488fb803b 100644 (file)
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -6338,10 +6338,17 @@ fold_builtin_constant_p (tree arglist)
   /* If we know this is a constant, emit the constant of one.  */
   if (CONSTANT_CLASS_P (arglist)
       || (TREE_CODE (arglist) == CONSTRUCTOR
-         && TREE_CONSTANT (arglist))
-      || (TREE_CODE (arglist) == ADDR_EXPR
-         && TREE_CODE (TREE_OPERAND (arglist, 0)) == STRING_CST))
+         && TREE_CONSTANT (arglist)))
     return integer_one_node;
+  if (TREE_CODE (arglist) == ADDR_EXPR)
+    {
+       tree op = TREE_OPERAND (arglist, 0);
+       if (TREE_CODE (op) == STRING_CST
+          || (TREE_CODE (op) == ARRAY_REF
+              && integer_zerop (TREE_OPERAND (op, 1))
+              && TREE_CODE (TREE_OPERAND (op, 0)) == STRING_CST))
+        return integer_one_node;
+    }
 
   /* If this expression has side effects, show we don't know it to be a
      constant.  Likewise if it's a pointer or aggregate type since in

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 367947b929bb34ced3cd614dcbb54c46ccfa3b42..b6ce026b19719e2bf06aff0b60909314a6385e2b 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2005-05-17  Richard Guenther  <rguenth@gcc.gnu.org>
+
+       PR middle-end/21595
+       * g++.dg/tree-ssa/builtin1.C: New testcase.
+
 2005-05-17  Jakub Jelinek  <jakub@redhat.com>
 
        PR c++/21454

diff --git a/gcc/testsuite/g++.dg/tree-ssa/builtin1.C b/gcc/testsuite/g++.dg/tree-ssa/builtin1.C
new file mode 100644 (file)
index 0000000..76813cb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/builtin1.C
@@ -0,0 +1,10 @@
+// { dg-do link }
+
+extern void link_error();
+
+int main()
+{
+       if (! __builtin_constant_p (&"Hello"[0]))
+               link_error();
+       return 0;
+}