Remove JITWriteBarrier.h
https://bugs.webkit.org/show_bug.cgi?id=163334
Reviewed by Mark Lam.
I guess that the idea of JITWriteBarrier was to make sure that if you slap some heap pointer
bits into machine code, then you better execute a barrier on the code block. But it's a
complicated piece of code, and I can never remember how it quite works. These days it looks
vestigial, particularly since only the CallLinkInfo patchable callee immediate uses it. It's
not really necessary to have something like this, since our convention is that any pointer
stored in machine code must always be shadowed in the GC heap. I think that convention has
won by overwhelming majority, so we should finally remove JITWriteBarrier.
A practical outcome of this change is that it makes it easier to implement DirectCall ICs,
which will have to store the callee in the CallLinkInfo but not in the machine code.
- JavaScriptCore.xcodeproj/project.pbxproj:
- assembler/AbstractMacroAssembler.h:
- bytecode/CallLinkInfo.cpp:
(JSC::CallLinkInfo::setCallee):
(JSC::CallLinkInfo::clearCallee):
(JSC::CallLinkInfo::setCallee): Deleted.
(JSC::CallLinkInfo::clearCallee): Deleted.
- heap/SlotVisitor.h:
- jit/JITWriteBarrier.h: Removed.
