ARM: Check for minus zero when converting binary operation result to smi

The result of an Int32 binary operation will be converted to a smi if it fits. However a minus zero check was missing.

BUG=v8:1278
TEST=test/mjsunit/regress/regress-1278.js

R=ager@chromium.org
Review URL: http://codereview.chromium.org/6755009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7399 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/code-stubs-arm.cc

@@ -3429,9 +3429,20 @@ void TypeRecordingBinaryOpStub::GenerateInt32Stub(MacroAssembler* masm) {
           __ add(scratch2, scratch1, Operand(0x40000000), SetCC);
           // If not try to return a heap number.
           __ b(mi, &return_heap_number);
+          // Check for minus zero. Return heap number for minus zero.
+          Label not_zero;
+          __ cmp(scratch1, Operand(0));
+          __ b(ne, &not_zero);
+          __ vmov(scratch2, d5.high());
+          __ tst(scratch2, Operand(HeapNumber::kSignMask));
+          __ b(ne, &return_heap_number);
+          __ bind(&not_zero);
+
           // Tag the result and return.
           __ SmiTag(r0, scratch1);
           __ Ret();
+        } else {
+          // DIV just falls through to allocating a heap number.
         }
 
         if (result_type_ >= (op_ == Token::DIV) ? TRBinaryOpIC::HEAP_NUMBER

test/mjsunit/regress/regress-1278.js

+// 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.
+
+// See: http://code.google.com/p/v8/issues/detail?id=1278
+
+// Test that that handling of 0/-0 is correct for binary operations when the
+// TypeRecordingBinaryOpStub transitions through different states.
+
+function add(x, y) {
+  return x + y;
+}
+
+function sub(x, y) {
+  return x - y;
+}
+
+function mul(x, y) {
+  return x * y;
+}
+
+function div(x, y) {
+  return x / y;
+}
+
+for (var i = 0; i < 10; i++) {
+  assertEquals(0, add(0, 0));
+  assertEquals(0, add(0, -0));
+  assertEquals(0, add(-0, 0));
+  assertEquals(-0, add(-0, -0));
+
+  assertEquals(0, sub(0, 0));
+  assertEquals(0, sub(0, -0));
+  assertEquals(-0, sub(-0, 0));
+  assertEquals(0, sub(-0, -0));
+
+  assertEquals(0, mul(0, 0));
+  assertEquals(-0, mul(0, -0));
+  assertEquals(-0, mul(-0, 0));
+  assertEquals(0, mul(-0, -0));
+
+  assertEquals(0, div(0, 1));
+  assertEquals(-0, div(0, -1));
+  assertEquals(-0, div(-0, 1));
+  assertEquals(0, div(-0, -1));
+}