diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a1e3c97f76f..9ba9e7a46d0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-04-02  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43629
+	* tree-ssa-ccp.c (likely_value): Reset all_undefined_operands
+	if we have seen a constant value.
+
 2010-04-02  Joseph Myers  <joseph@codesourcery.com>
 
 	* read-rtl.c (read_rtx_1): Give an error for EOF while looking for
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 16b901b8310..54ec0072334 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-04-02  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43629
+	* gcc.c-torture/execute/pr43629.c: New testcase.
+
 2010-04-01  Janne Blomqvist  <jb@gcc.gnu.org>
             Dominique d'Humieres  <dominiq@lps.ens.fr>
 
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr43629.c b/gcc/testsuite/gcc.c-torture/execute/pr43629.c
new file mode 100644
index 00000000000..10c0196c89b
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr43629.c
@@ -0,0 +1,13 @@
+int flag;
+extern void abort (void);
+int main()
+{
+  int x;
+  if (flag)
+    x = -1;
+  else 
+    x &= 0xff;
+  if (x & ~0xff)
+    abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 03c35001718..fcfdd18d1bf 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -1,6 +1,6 @@
 /* Conditional constant propagation pass for the GNU compiler.
-   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
-   Free Software Foundation, Inc.
+   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
+   2010 Free Software Foundation, Inc.
    Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
    Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com>
 
@@ -558,6 +558,9 @@ likely_value (gimple stmt)
 	has_constant_operand = true;
     }
 
+  if (has_constant_operand)
+    all_undefined_operands = false;
+
   /* If the operation combines operands like COMPLEX_EXPR make sure to
      not mark the result UNDEFINED if only one part of the result is
      undefined.  */