diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6ef99e6e1705..e080d10b4e8c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-02-10  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43017
+	* tree-vrp.c (vrp_int_const_binop): Trust int_const_binop
+	for wrapping signed arithmetic.
+
 2010-02-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/43010
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b3b5d770da4c..d599f15a07cc 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-02-10  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43017
+	* gcc.dg/torture/pr43017.c: New testcase.
+
 2010-02-10  Tobias Burnus <burnus@net-b.de>
 
 	PR fortran/40823
diff --git a/gcc/testsuite/gcc.dg/torture/pr43017.c b/gcc/testsuite/gcc.dg/torture/pr43017.c
new file mode 100644
index 000000000000..257945290e11
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr43017.c
@@ -0,0 +1,99 @@
+/* { dg-do run } */
+/* { dg-options "-fwrapv" } */
+
+signed char foo(unsigned char c2)
+{
+  signed char c2_22;
+
+  if (c2 <= 63 || c2 == 127)
+    goto bb43;
+  else
+    goto bb20;
+
+bb20:
+  if (c2 > 252)
+    goto bb43;
+  else
+    goto bb21;
+
+bb21:
+  /*...*/;
+
+bb24:
+  c2_22 = (signed char)c2;
+  if (c2_22 >= 0)
+    goto bb25;
+  else
+    goto bb26;
+
+bb25:
+  c2 = (unsigned char)(c2_22 - 64);
+  goto bb27;
+
+bb26:
+  c2 = (unsigned char)(c2_22 - 65);
+
+bb27:
+  if (c2 <= 93)
+    goto bb28;
+  else
+    goto bb29;
+
+bb28:
+  c2 = c2 + 33;
+  goto bb30;
+
+bb29:
+  c2 = (unsigned char)((signed char)c2 - 61);
+
+bb30:
+  return c2;
+
+bb43:
+  return -1;
+}
+extern void abort (void);
+int main()
+{
+  signed char res[256] = {
+      -1, -1, -1, -1, -1, -1, -1, -1, 
+      -1, -1, -1, -1, -1, -1, -1, -1, 
+      -1, -1, -1, -1, -1, -1, -1, -1, 
+      -1, -1, -1, -1, -1, -1, -1, -1, 
+      -1, -1, -1, -1, -1, -1, -1, -1, 
+      -1, -1, -1, -1, -1, -1, -1, -1, 
+      -1, -1, -1, -1, -1, -1, -1, -1, 
+      -1, -1, -1, -1, -1, -1, -1, -1, 
+      33, 34, 35, 36, 37, 38, 39, 40, 
+      41, 42, 43, 44, 45, 46, 47, 48, 
+      49, 50, 51, 52, 53, 54, 55, 56, 
+      57, 58, 59, 60, 61, 62, 63, 64, 
+      65, 66, 67, 68, 69, 70, 71, 72, 
+      73, 74, 75, 76, 77, 78, 79, 80, 
+      81, 82, 83, 84, 85, 86, 87, 88, 
+      89, 90, 91, 92, 93, 94, 95, -1, 
+      96, 97, 98, 99, 100, 101, 102, 103, 
+      104, 105, 106, 107, 108, 109, 110, 111, 
+      112, 113, 114, 115, 116, 117, 118, 119, 
+      120, 121, 122, 123, 124, 125, 126, 33, 
+      34, 35, 36, 37, 38, 39, 40, 41, 
+      42, 43, 44, 45, 46, 47, 48, 49, 
+      50, 51, 52, 53, 54, 55, 56, 57, 
+      58, 59, 60, 61, 62, 63, 64, 65, 
+      66, 67, 68, 69, 70, 71, 72, 73, 
+      74, 75, 76, 77, 78, 79, 80, 81, 
+      82, 83, 84, 85, 86, 87, 88, 89, 
+      90, 91, 92, 93, 94, 95, 96, 97, 
+      98, 99, 100, 101, 102, 103, 104, 105, 
+      106, 107, 108, 109, 110, 111, 112, 113, 
+      114, 115, 116, 117, 118, 119, 120, 121, 
+      122, 123, 124, 125, 126, -1, -1, -1
+  };
+  unsigned int c;
+  for (c = 0; c <= 255; ++c)
+    {
+      if (foo (c) != res[c])
+	abort ();
+    }
+  return 0;
+}
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 73dcf23a5584..81645485f8b2 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -1937,6 +1937,10 @@ vrp_int_const_binop (enum tree_code code, tree val1, tree val2)
 	}
 
     }
+  else if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1)))
+    /* If the singed operation wraps then int_const_binop has done
+       everything we want.  */
+    ;
   else if ((TREE_OVERFLOW (res)
 	    && !TREE_OVERFLOW (val1)
 	    && !TREE_OVERFLOW (val2))