| | 1 | /* |
| | 2 | * Copyright (C) 2012, 2013 Apple Inc. All rights reserved. |
| | 3 | * |
| | 4 | * Redistribution and use in source and binary forms, with or without |
| | 5 | * modification, are permitted provided that the following conditions |
| | 6 | * are met: |
| | 7 | * 1. Redistributions of source code must retain the above copyright |
| | 8 | * notice, this list of conditions and the following disclaimer. |
| | 9 | * 2. Redistributions in binary form must reproduce the above copyright |
| | 10 | * notice, this list of conditions and the following disclaimer in the |
| | 11 | * documentation and/or other materials provided with the distribution. |
| | 12 | * |
| | 13 | * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY |
| | 14 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| | 15 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| | 16 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR |
| | 17 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| | 18 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| | 19 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| | 20 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY |
| | 21 | * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| | 22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| | 23 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| | 24 | */ |
| | 25 | |
| | 26 | #include "config.h" |
| | 27 | #include "ArrayAllocationProfile.h" |
| | 28 | |
| | 29 | #include "JSCInlines.h" |
| | 30 | |
| | 31 | namespace JSC { |
| | 32 | |
| | 33 | void ArrayAllocationProfile::updateIndexingType() |
| | 34 | { |
| | 35 | // This is awkwardly racy but totally sound even when executed concurrently. The |
| | 36 | // worst cases go something like this: |
| | 37 | // |
| | 38 | // - Two threads race to execute this code; one of them succeeds in updating the |
| | 39 | // m_currentIndexingType and the other either updates it again, or sees a null |
| | 40 | // m_lastArray; if it updates it again then at worst it will cause the profile |
| | 41 | // to "forget" some array. That's still sound, since we don't promise that |
| | 42 | // this profile is a reflection of any kind of truth. |
| | 43 | // |
| | 44 | // - A concurrent thread reads m_lastArray, but that array is now dead. While |
| | 45 | // it's possible for that array to no longer be reachable, it cannot actually |
| | 46 | // be freed, since we require the GC to wait until all concurrent JITing |
| | 47 | // finishes. |
| | 48 | |
| | 49 | JSArray* lastArray = m_lastArray; |
| | 50 | if (!lastArray) |
| | 51 | return; |
| | 52 | m_currentIndexingType = leastUpperBoundOfIndexingTypes(m_currentIndexingType, lastArray->indexingType()); |
| | 53 | m_lastArray = 0; |
| | 54 | } |
| | 55 | |
| | 56 | } // namespace JSC |
| | 57 | |
projects / apple / javascriptcore.git / blame_incremental