v8/test/mjsunit/shift-for-integer-div.js
yangguo@chromium.org c70a0f9334 Improve integer division on IA32 and X64
If the divisor is a Power-of-2 constant, we could use shifts instead of the
expensive idiv instructions, which also loose the register constraints.

Review URL: https://chromiumcodereview.appspot.com/11478043
Patch from Yuqiang Xian <yuqiang.xian@intel.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13178 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2012-12-10 11:02:22 +00:00

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2.0 KiB
JavaScript

// 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
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
function divp4(x) {
return x / 4;
}
for (var i = 0; i < 10000; i+=4) {
assertEquals(i >> 2, divp4(i));
}
assertEquals(0.5, divp4(2));
function divn4(x) {
return x / (-4);
}
for (var i = 0; i < 10000; i+=4) {
assertEquals(-(i >> 2), divn4(i));
}
assertEquals(-0, divn4(0));
function divn1(x) {
return x / (-1);
}
for (var i = 0; i < 10000; i++) {
assertEquals(-i, divn1(i));
}
var min_int = -(0x7FFFFFFF)-1;
assertEquals(-min_int, divn1(min_int));