Fix x64 MathMinMax for negative untagged int32 arguments.

An untagged int32 has zeros in the upper half even if it is negative.
Using cmpq to compare such numbers will incorrectly ignore the sign.

BUG=164442
R=mvstanton@chromium.org

Review URL: https://chromiumcodereview.appspot.com/11665007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13273 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/lithium-codegen-x64.cc

@@ -1642,17 +1642,17 @@ void LCodeGen::DoMathMinMax(LMathMinMax* instr) {
     if (right->IsConstantOperand()) {
       Immediate right_imm =
           Immediate(ToInteger32(LConstantOperand::cast(right)));
-      __ cmpq(left_reg, right_imm);
+      __ cmpl(left_reg, right_imm);
       __ j(condition, &return_left, Label::kNear);
       __ movq(left_reg, right_imm);
     } else if (right->IsRegister()) {
       Register right_reg = ToRegister(right);
-      __ cmpq(left_reg, right_reg);
+      __ cmpl(left_reg, right_reg);
       __ j(condition, &return_left, Label::kNear);
       __ movq(left_reg, right_reg);
     } else {
       Operand right_op = ToOperand(right);
-      __ cmpq(left_reg, right_op);
+      __ cmpl(left_reg, right_op);
       __ j(condition, &return_left, Label::kNear);
       __ movq(left_reg, right_op);
     }

test/mjsunit/regress/regress-164442.js

+// Copyright 2012 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.
+
+// Flags: --allow-natives-syntax
+
+// Should not take a very long time (n^2 algorithms are bad)
+
+
+function ensureNotNegative(x) {
+  return Math.max(0, x | 0);
+}
+
+
+ensureNotNegative(1);
+ensureNotNegative(2);
+
+%OptimizeFunctionOnNextCall(ensureNotNegative);
+
+var r = ensureNotNegative(-1);
+
+assertEquals(0, r);