Reviewers: William Hesse,

Description:
Merge x64 minus-zero fix (bleeding_edge r5631) to 2.4 branch.

[email protected]

Please review this at http://codereview.chromium.org/3844002/show

SVN Base: http://v8.googlecode.com/svn/branches/2.4/

Affected files:
  M     src/x64/code-stubs-x64.cc
  M     test/mjsunit/smi-negative-zero.js


Index: src/x64/code-stubs-x64.cc
===================================================================
--- src/x64/code-stubs-x64.cc   (revision 5631)
+++ src/x64/code-stubs-x64.cc   (working copy)
@@ -1413,20 +1413,8 @@
         __ j(equal, &done);
       }
       __ SmiNeg(rax, rax, &done);
+      __ jmp(&slow);  // zero, if not handled above, and Smi::kMinValue.

-      // Either zero or Smi::kMinValue, neither of which become a smi when
-      // negated. We handle negative zero here if required. We always enter
-      // the runtime system if we have Smi::kMinValue.
-      if (negative_zero_ == kStrictNegativeZero) {
-        __ SmiCompare(rax, Smi::FromInt(0));
-        __ j(not_equal, &slow);
-        __ Move(rax, Factory::minus_zero_value());
-        __ jmp(&done);
-      } else  {
-        __ SmiCompare(rax, Smi::FromInt(Smi::kMinValue));
-        __ j(equal, &slow);
-        __ jmp(&done);
-      }
       // Try floating point case.
       __ bind(&try_float);
     } else if (FLAG_debug_code) {
Index: test/mjsunit/smi-negative-zero.js
===================================================================
--- test/mjsunit/smi-negative-zero.js   (revision 5631)
+++ test/mjsunit/smi-negative-zero.js   (working copy)
@@ -98,3 +98,16 @@
 assertEquals(-Infinity, one / (-4 % -2), "fiskhest2");
 assertEquals(Infinity, one / (4 % 2), "fiskhest3");
 assertEquals(Infinity, one / (4 % -2), "fiskhest4");
+
+
+// This tests against a singleton -0.0 object being overwritten.gc
+x = 0;
+z = 3044;
+
+function foo(x) {
+  var y = -x + z;
+  return -x;
+}
+
+assertEquals(0, foo(x));
+assertEquals(0, foo(x));


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