- added from gcc/

[packages/gcc4.git] / gcc4-pr19606.patch

--- gcc/c-typeck.c	(revision 110241)
+++ gcc/c-typeck.c	(working copy)
@@ -8101,12 +8101,35 @@ build_binary_op (enum tree_code code, tr
       if (shorten && none_complex)
 	{
 	  int unsigned0, unsigned1;
-	  tree arg0 = get_narrower (op0, &unsigned0);
-	  tree arg1 = get_narrower (op1, &unsigned1);
-	  /* UNS is 1 if the operation to be done is an unsigned one.  */
-	  int uns = TYPE_UNSIGNED (result_type);
+	  tree arg0, arg1;
+	  int uns;
 	  tree type;
 
+	  /* Cast OP0 and OP1 to RESULT_TYPE.  Doing so prevents
+	     excessive narrowing when we call get_narrower below.  For
+	     example, suppose that OP0 is of unsigned int extended
+	     from signed char and that RESULT_TYPE is long long int.
+	     If we explicitly cast OP0 to RESULT_TYPE, OP0 would look
+	     like
+
+	       (long long int) (unsigned int) signed_char
+
+	     which get_narrower would narrow down to
+
+	       (unsigned int) signed char
+
+	     If we do not cast OP0 first, get_narrower would return
+	     signed_char, which is inconsistent with the case of the
+	     explicit cast.  */
+	  op0 = convert (result_type, op0);
+	  op1 = convert (result_type, op1);
+
+	  arg0 = get_narrower (op0, &unsigned0);
+	  arg1 = get_narrower (op1, &unsigned1);
+
+	  /* UNS is 1 if the operation to be done is an unsigned one.  */
+	  uns = TYPE_UNSIGNED (result_type);
+
 	  final_type = result_type;
 
 	  /* Handle the case that OP0 (or OP1) does not *contain* a conversion
Index: testsuite/gcc.c-torture/execute/pr19606.c
===================================================================
--- /dev/null	2005-09-01 09:08:28.063949816 -0700
+++ gcc/testsuite/gcc.c-torture/execute/pr19606.c	2006-01-15 14:41:56.490361111 -0800
@@ -0,0 +1,33 @@
+/* PR c/19606
+   The C front end used to shorten the type of a division even when
+   the signedness changes.  Make sure that won't happen.  */
+
+signed char a = -4;
+
+int
+foo (void)
+{
+  return ((unsigned int) (signed int) a) / 2LL;
+}
+
+int
+bar (void)
+{
+  return ((unsigned int) (signed int) a) % 5LL;
+}
+
+int
+main (void)
+{
+  int r;
+
+  r = foo ();
+  if (r != ((unsigned int) (signed int) (signed char) -4) / 2LL)
+    abort ();
+
+  r = bar ();
+  if (r != ((unsigned int) (signed int) (signed char) -4) % 5LL)
+    abort ();
+
+  exit (0);
+}