mirror of https://github.com/lukechilds/node.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
59 lines
3.2 KiB
59 lines
3.2 KiB
12 years ago
|
// Copyright 2013 the V8 project authors. All rights reserved.
|
||
|
|
// Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
|
||
|
|
//
|
||
|
|
// Redistribution and use in source and binary forms, with or without
|
||
|
|
// modification, are permitted provided that the following conditions
|
||
|
|
// are met:
|
||
|
|
// 1. Redistributions of source code must retain the above copyright
|
||
|
|
// notice, this list of conditions and the following disclaimer.
|
||
|
|
// 2. 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.
|
||
|
|
//
|
||
|
|
// THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS 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 APPLE INC. OR ITS 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.
|
||
|
|
|
||
|
|
description(
|
||
|
|
"This tests that a constant folding on a node that has obviously mispredicted type doesn't send the compiler into an infinite loop."
|
||
|
|
);
|
||
|
|
|
||
|
|
// A function with an argument correctly predicted double.
|
||
|
|
function foo(x) {
|
||
|
|
// Two variables holding constants such that the bytecode generation constant folder
|
||
|
|
// will not constant fold the division below, but the DFG constant folder will.
|
||
|
|
var a = 1;
|
||
|
|
var b = 4000;
|
||
|
|
// A division that is going to be predicted integer on the first compilation. The
|
||
|
|
// compilation will be triggered from the loop below so the slow case counter of the
|
||
|
|
// division will be 1, which is too low for the division to be predicted double.
|
||
|
|
// If we constant fold this division, we'll have a constant node that is predicted
|
||
|
|
// integer but that contains a double. The subsequent addition to x, which is
|
||
|
|
// predicted double, will lead the Fixup phase to inject an Int32ToDouble node on
|
||
|
|
// the constant-that-was-a-division; subsequent fases in the fixpoint will constant
|
||
|
|
// fold that Int32ToDouble. And hence we will have an infinite loop. The correct fix
|
||
|
|
// is to disable constant folding of mispredicted nodes; that allows the normal
|
||
|
|
// process of correcting predictions (OSR exit profiling, exiting to profiled code,
|
||
|
|
// and recompilation with exponential backoff) to take effect so that the next
|
||
|
|
// compilation does not make this same mistake.
|
||
|
|
var c = (a / b) + x;
|
||
|
|
// A pointless loop to force the first compilation to occur before the division got
|
||
|
|
// hot. If this loop was not here then the division would be known to produce doubles
|
||
|
|
// on the first compilation.
|
||
|
|
var d = 0;
|
||
|
|
for (var i = 0; i < 1000; ++i)
|
||
|
|
d++;
|
||
|
|
return c + d;
|
||
|
|
}
|
||
|
|
|
||
|
|
// Call foo() enough times to make totally sure that we optimize.
|
||
|
|
for (var i = 0; i < 5; ++i)
|
||
|
|
shouldBe("foo(0.5)", "1000.50025");
|