Fix bug in the count operation where we statically know the input is a smi.

test/mjsunit/compiler/loopcount.js

Index: test/mjsunit/compiler/loopcount.js
===================================================================
--- test/mjsunit/compiler/loopcount.js	(revision 0)
+++ test/mjsunit/compiler/loopcount.js	(revision 0)
@@ -0,0 +1,55 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Test postfix count operations with smis.
+
+function f1() { var x = 0x3fffffff; x++; return x; }
+assertEquals(0x40000000, f1());
+
+
+function f2() { var x = -0x40000000; x--; return x; }
+assertEquals(-0x40000001, f2());
+
+
+function f3(x) { x = x & 0x3fffffff; x++; return x; }
+assertEquals(0x40000000, f3(0x3fffffff));
+
+
+function f4() {
+  var i;
+  for (i = 0x3ffffffe; i <= 0x3fffffff; i++) {}
+  return i;
+}
+assertEquals(0x40000000, f4());
+
+
+function f5() {
+  var i;
+  for (i = -0x3fffffff; i >= -0x40000000; i--) {}
+  return i;
+}
+assertEquals(-0x40000001, f5());