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Turn old space cons strings into regular external strings (not short).

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R=hpayer@chromium.org

Review URL: https://codereview.chromium.org/368223002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22192 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
yangguo@chromium.org 2014-07-03 11:46:31 +00:00
parent bed0877111
commit 6574f33d2a
2 changed files with 29 additions and 18 deletions
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26
src/objects.cc
View File

@ -1067,18 +1067,13 @@ bool String::MakeExternal(v8::String::ExternalStringResource* resource) {
bool is_internalized = this->IsInternalizedString(); bool is_internalized = this->IsInternalizedString();
// Morph the string to an external string by replacing the map and // Morph the string to an external string by replacing the map and
// reinitializing the fields. This won't work if // reinitializing the fields. This won't work if the space the existing
// - the space the existing string occupies is too small for a regular // string occupies is too small for a regular external string.
// external string. // Instead, we resort to a short external string instead, omitting
// - the existing string is in old pointer space and the backing store of
// the external string is not aligned. The GC cannot deal with a field
// containing a possibly unaligned address to outside of V8's heap.
// In either case we resort to a short external string instead, omitting
// the field caching the address of the backing store. When we encounter // the field caching the address of the backing store. When we encounter
// short external strings in generated code, we need to bailout to runtime. // short external strings in generated code, we need to bailout to runtime.
Map* new_map; Map* new_map;
if (size < ExternalString::kSize || if (size < ExternalString::kSize) {
heap->old_pointer_space()->Contains(this)) {
new_map = is_internalized new_map = is_internalized
? (is_ascii ? (is_ascii
? heap-> ? heap->
@ -1139,18 +1134,13 @@ bool String::MakeExternal(v8::String::ExternalAsciiStringResource* resource) {
bool is_internalized = this->IsInternalizedString(); bool is_internalized = this->IsInternalizedString();
// Morph the string to an external string by replacing the map and // Morph the string to an external string by replacing the map and
// reinitializing the fields. This won't work if // reinitializing the fields. This won't work if the space the existing
// - the space the existing string occupies is too small for a regular // string occupies is too small for a regular external string.
// external string. // Instead, we resort to a short external string instead, omitting
// - the existing string is in old pointer space and the backing store of
// the external string is not aligned. The GC cannot deal with a field
// containing a possibly unaligned address to outside of V8's heap.
// In either case we resort to a short external string instead, omitting
// the field caching the address of the backing store. When we encounter // the field caching the address of the backing store. When we encounter
// short external strings in generated code, we need to bailout to runtime. // short external strings in generated code, we need to bailout to runtime.
Map* new_map; Map* new_map;
if (size < ExternalString::kSize || if (size < ExternalString::kSize) {
heap->old_pointer_space()->Contains(this)) {
new_map = is_internalized new_map = is_internalized
? heap->short_external_ascii_internalized_string_map() ? heap->short_external_ascii_internalized_string_map()
: heap->short_external_ascii_string_map(); : heap->short_external_ascii_string_map();

21
test/mjsunit/regress/regress-sliced-external-cons-regexp.js Normal file
View File

@ -0,0 +1,21 @@
// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Flags: --expose-externalize-string --expose-gc
var re = /(B)/;
var cons1 = "0123456789" + "ABCDEFGHIJ";
var cons2 = "0123456789\u1234" + "ABCDEFGHIJ";
gc();
gc(); // Promote cons.
try { externalizeString(cons1, false); } catch (e) { }
try { externalizeString(cons2, true); } catch (e) { }
var slice1 = cons1.slice(1,-1);
var slice2 = cons2.slice(1,-1);
for (var i = 0; i < 10; i++) {
assertEquals(["B", "B"], re.exec(slice1));
assertEquals(["B", "B"], re.exec(slice2));
}