tree 0663f0d96561ae17d70b2957f712805ced6b4e34
parent b02f9bf7ff0f3743530b30f0ef28697f2c73d896
author ysuzuki@apple.com <ysuzuki@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1571441524 +0000
committer ysuzuki@apple.com <ysuzuki@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1571441524 +0000

[JSC] Make ConcurrentJSLock Lock even if ENABLE_CONCURRENT_JS=OFF
https://bugs.webkit.org/show_bug.cgi?id=202892

Reviewed by Mark Lam.

Source/JavaScriptCore:

We are using ConcurrentJSLock to guard data structure against concurrent compilers.
But these data structures should be guarded by GC concurrent collector, so we are using this ConcurrentJSLock
to guard them against concurrent collector too.
The problem is that ENABLE(CONCURRENT_JS) relies on ENABLE(DFG_JIT). If we configure JSC with the options like,

    ENABLE_DFG_JIT 0
    ENABLE_FTL_JIT 0

Then, the built JSC becomes

    ENABLE_CONCURRENT_JS 0
    But, Concurrent GC is enabled.

This is wrong due to several reasons.

    1. Baseline JIT can produce JIT related data structures that are traced by concurrent collector. In the above options,
       these data structures are not guarded by lock.
    2. Baseline JIT also has concurrent JIT compiler. But ENABLE_CONCURRENT_JS does not reflect this.

In this patch, we fix two things.

1. We should make ConcurrentJSLock always Lock. In 64bit environment we are supporting actively (including watchOS ARM64_32),
   we are enabling ENABLE(JIT) regardless of we are actually using JIT. So, anyway, this is already a Lock. Flipping these
   bits does not matter in 32bit architectures since they do not have concurrent compilers anyway. This makes things simpler:
   it is always a Lock. And concurrent collector can use it.
2. We should make `ENABLE(CONCURRENT_JS)` ON when `ENABLE(JIT)` is true, to reflect the fact that Baseline JIT has concurrent compiler.

* runtime/ConcurrentJSLock.h:
(JSC::ConcurrentJSLocker::ConcurrentJSLocker):

Source/WTF:

BaselineJIT also has concurrent compiler. ENABLE(CONCURRENT_JS) should not rely on ENABLE(DFG_JIT).
It should rely on ENABLE(JIT) instead.

* wtf/Platform.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@251307 268f45cc-cd09-0410-ab3c-d52691b4dbfc