300-pr15526.patch

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# DP: 2004-09-26  Roger Sayle  <[e-mail]>
# DP: 
# DP: 	PR other/15526
# DP: 	Backport from mainline
# DP: 	2004-05-20  Falk Hueffner  <[e-mail]>
# DP: 	* libgcc2.c (__mulvsi3): Fix overflow test.

diff -u -r1.170.6.1 -r1.170.6.2
--- gcc/gcc/libgcc2.c	2004/07/17 21:18:47	1.170.6.1
+++ gcc/gcc/libgcc2.c	2004/09/26 20:47:14	1.170.6.2
@@ -130,9 +130,7 @@
 {
   const DWtype w = (DWtype) a * (DWtype) b;
 
-  if (((a >= 0) == (b >= 0))
-      ? (UDWtype) w > (UDWtype) (((DWtype) 1 << (WORD_SIZE - 1)) - 1)
-      : (UDWtype) w < (UDWtype) ((DWtype) -1 << (WORD_SIZE - 1)))
+  if ((Wtype) (w >> WORD_SIZE) != (Wtype) w >> (WORD_SIZE - 1))
     abort ();
 
   return w;

/cvs/gcc/gcc/gcc/testsuite/gcc.dg/ftrapv-1.c,v  -->  standard output
revision 1.1.22.1
--- gcc/gcc/testsuite/gcc.dg/ftrapv-1.c
+++ /dev/null	2004-10-15 06:22:06.980596000 +0000
@@ -0,0 +1,25 @@
+/* Copyright (C) 2004 Free Software Foundation.
+
+   PR other/15526
+   Verify correct overflow checking with -ftrapv.
+
+   Written by Falk Hueffner, 20th May 2004.  */
+
+/* { dg-do run } */
+/* { dg-options "-ftrapv" } */
+
+__attribute__((noinline)) int
+mulv(int a, int b)
+{
+  return a * b;
+}
+
+int
+main()
+{
+  mulv( 0,  0);
+  mulv( 0, -1);
+  mulv(-1,  0);
+  mulv(-1, -1);
+  return 0;
+}