e42e7fc800
This fixes String::MakeExternal() to bail out if the subject string doesn't fit a regular ExternalString, instead of creating a short external string. The observation here is that for short external strings the overhead of having to have the StringResource plus going to the runtime/C++ for each and every character access from JavaScript land is probably bigger than the anticipated benefits. If this turns out to be wrong and there's a real benefit, we should make use of ThinStrings instead of having a separate way to represent external strings. Bug: v8:6621, v8:7109, v8:7145 Change-Id: I4b75da08b82a72027c782a69de9c8eaf3cca1d4d Reviewed-on: https://chromium-review.googlesource.com/799750 Reviewed-by: Yang Guo <yangguo@chromium.org> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org> Cr-Commit-Position: refs/heads/master@{#49735}
106 lines
3.9 KiB
JavaScript
106 lines
3.9 KiB
JavaScript
// 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.
|
|
|
|
// Flags: --expose-externalize-string --expose-gc --allow-natives-syntax
|
|
|
|
var size = 1024;
|
|
|
|
function dont_inline() { return "AAAAAAA"; }
|
|
%NeverOptimizeFunction(dont_inline);
|
|
|
|
function dont_inline2() { return "\u1234"; }
|
|
%NeverOptimizeFunction(dont_inline2);
|
|
|
|
function test() {
|
|
var str = "";
|
|
|
|
// Build an ascii cons string.
|
|
for (var i = 0; i < size; i++) {
|
|
str += String.fromCharCode(i & 0x7f);
|
|
}
|
|
assertTrue(isOneByteString(str));
|
|
|
|
var twoByteExternalWithOneByteData =
|
|
"AA" + dont_inline();
|
|
externalizeString(twoByteExternalWithOneByteData, true /* force two-byte */);
|
|
assertFalse(isOneByteString(twoByteExternalWithOneByteData));
|
|
|
|
var realTwoByteExternalString =
|
|
"\u1234\u1234\u1234\u1234" + dont_inline2();
|
|
externalizeString(realTwoByteExternalString);
|
|
assertFalse(isOneByteString(realTwoByteExternalString));
|
|
|
|
assertTrue(isOneByteString(["a", twoByteExternalWithOneByteData].join("")));
|
|
|
|
// Appending a two-byte string that contains only ascii chars should
|
|
// still produce an ascii cons.
|
|
var str1 = str + twoByteExternalWithOneByteData;
|
|
assertTrue(isOneByteString(str1));
|
|
|
|
// Force flattening of the string.
|
|
var old_length = str1.length - twoByteExternalWithOneByteData.length;
|
|
for (var i = 0; i < old_length; i++) {
|
|
assertEquals(String.fromCharCode(i & 0x7f), str1[i]);
|
|
}
|
|
for (var i = old_length; i < str1.length; i++) {
|
|
assertEquals("A", str1[i]);
|
|
}
|
|
|
|
// Flattened string should still be ascii.
|
|
assertTrue(isOneByteString(str1));
|
|
|
|
// Lower-casing an ascii string should produce ascii.
|
|
assertTrue(isOneByteString(str1.toLowerCase()));
|
|
|
|
assertFalse(isOneByteString(["a", realTwoByteExternalString].join("")));
|
|
|
|
// Appending a real two-byte string should produce a two-byte cons.
|
|
var str2 = str + realTwoByteExternalString;
|
|
assertFalse(isOneByteString(str2));
|
|
|
|
// Force flattening of the string.
|
|
old_length = str2.length - realTwoByteExternalString.length;
|
|
for (var i = 0; i < old_length; i++) {
|
|
assertEquals(String.fromCharCode(i & 0x7f), str2[i]);
|
|
}
|
|
for (var i = old_length; i < str.length; i++) {
|
|
assertEquals("\u1234", str2[i]);
|
|
}
|
|
|
|
// Flattened string should still be two-byte.
|
|
assertFalse(isOneByteString(str2));
|
|
}
|
|
|
|
// Run the test many times to ensure IC-s don't break things.
|
|
for (var i = 0; i < 10; i++) {
|
|
test();
|
|
}
|
|
|
|
// Clean up string to make Valgrind happy.
|
|
gc();
|
|
gc();
|