re PR tree-optimization/31136 (FRE ignores bit-field truncation (C and C++…

re PR tree-optimization/31136 (FRE ignores bit-field truncation (C and C++ front-end don't produce bit-field truncation)

2007-04-21  Richard Guenther  <rguenther@suse.de>

	PR middle-end/31136
	* fold-const.c (fold_unary): Call fold_convert_const on the
	original tree.

	* gcc.c-torture/execute/pr31136.c: New testcase.

From-SVN: r124020

gcc/ChangeLog

+2007-04-21  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/31136
+	* fold-const.c (fold_unary): Call fold_convert_const on the
+	original tree.
+
 2007-04-21  Alexandre Oliva  <aoliva@redhat.com>
 
 	* gcse.c (store_killed_in_insn): Handle PARALLELs.

gcc/fold-const.c

@@ -7857,7 +7857,7 @@ fold_unary (enum tree_code code, tree type, tree op0)
 	    return fold_build1 (BIT_NOT_EXPR, type, fold_convert (type, tem));
 	}
 
-      tem = fold_convert_const (code, type, arg0);
+      tem = fold_convert_const (code, type, op0);
       return tem ? tem : NULL_TREE;
 
     case VIEW_CONVERT_EXPR:

gcc/testsuite/ChangeLog

+2007-04-21  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/31136
+	* gcc.c-torture/execute/pr31136.c: New testcase.
+
 2007-04-21  Alexandre Oliva  <aoliva@redhat.com>
 
 	* gcc.target/i386/movsi-sm-1.c: New.

gcc/testsuite/gcc.c-torture/execute/pr31136.c

+extern void abort (void);
+
+struct S {
+  unsigned b4:4;
+  unsigned b6:6;
+} s;
+
+int main()
+{
+  s.b6 = 31;
+  s.b4 = s.b6;
+  s.b6 = s.b4;
+  if (s.b6 != 15)
+    abort ();
+  return 0;
+}
+