Revision: 17432
Author: [email protected]
Date: Wed Oct 30 10:22:52 2013 UTC
Log: Do not remove HAdd with zero if the other operand is a double.
The other operand might be minus zero, and -0 + 0 = +0
[email protected]
BUG=
Review URL: https://codereview.chromium.org/52173003
http://code.google.com/p/v8/source/detail?r=17432
Added:
/branches/bleeding_edge/test/mjsunit/regress/regress-add-minus-zero.js
Modified:
/branches/bleeding_edge/src/hydrogen-instructions.cc
=======================================
--- /dev/null
+++ /branches/bleeding_edge/test/mjsunit/regress/regress-add-minus-zero.js
Wed Oct 30 10:22:52 2013 UTC
@@ -0,0 +1,38 @@
+// Copyright 2013 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
+
+var o = { a: 0 };
+
+function f(x) { return -o.a + 0; };
+
+assertEquals("Infinity", String(1/f()));
+assertEquals("Infinity", String(1/f()));
+%OptimizeFunctionOnNextCall(f);
+assertEquals("Infinity", String(1/f()));
+
=======================================
--- /branches/bleeding_edge/src/hydrogen-instructions.cc Wed Oct 23
12:30:38 2013 UTC
+++ /branches/bleeding_edge/src/hydrogen-instructions.cc Wed Oct 30
10:22:52 2013 UTC
@@ -1255,8 +1255,15 @@
HValue* HAdd::Canonicalize() {
- if (IsIdentityOperation(left(), right(), 0)) return left();
- if (IsIdentityOperation(right(), left(), 0)) return right();
+ // Adding 0 is an identity operation except in case of -0: -0 + 0 = +0
+ if (IsIdentityOperation(left(), right(), 0) &&
+ !left()->representation().IsDouble()) { // Left could be -0.
+ return left();
+ }
+ if (IsIdentityOperation(right(), left(), 0) &&
+ !left()->representation().IsDouble()) { // Right could be -0.
+ return right();
+ }
return this;
}
--
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