CodeBlock should be a GC object
authorggaren@apple.com <ggaren@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Fri, 2 Oct 2015 03:45:53 +0000 (03:45 +0000)
committerggaren@apple.com <ggaren@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Fri, 2 Oct 2015 03:45:53 +0000 (03:45 +0000)
commit92676df0e46fe1a2588f3115656bfb2e8f78228f
treed62fbb282cd7792750615e3c7e67793452c99c6b
parent18529f17e4398947b613ee63ffa4df809469a2cd
CodeBlock should be a GC object
https://bugs.webkit.org/show_bug.cgi?id=149727

Reviewed by Filip Pizlo.

We want CodeBlock to be a GC object:

(1) Sane write barriers. Because CodeBlock wasn't a GC object, we couldn't
execute a write barrier on it. This caused us to do weird things that
were hard to reason about, like executing a barrier on a related executable
(even though the executable might stop pointing to the CodeBlock before
the next GC), or pretending that an object had written to itself. Now,
when we write to a CodeBlock, we barrier the CodeBlock, and that's that.

(2) Simpler marking and destruction logic. There's no need to have a
custom remembered set or a destruction fixpoint if we just obey normal
GC rules.

* bytecode/CodeBlock.cpp:
(JSC::FunctionCodeBlock::destroy):
(JSC::WebAssemblyCodeBlock::destroy):
(JSC::ProgramCodeBlock::destroy):
(JSC::ModuleProgramCodeBlock::destroy):
(JSC::EvalCodeBlock::destroy): Add ClassInfo and destroy functions
because our GC object model requires them.

Note that we do not set the needsDestruction flag. Since CodeBlock needs
eager destruction, it runs its destructors through CodeBlockSet,
and not through normal object sweeping.

(JSC::CodeBlock::finishCreation): Factor out finishCreation from the
constructor because our GC object model requires it. Change write
barriers to note the CodeBlock as the owner.

(JSC::CodeBlock::~CodeBlock): Refactor to use the shared
unlinkIncomingCalls() function instead of rolling a copy by hand.

(JSC::CodeBlock::visitWeakly): New helper function for owner executables
to do weak marking that might jettison a CodeBlock. Our new GC logic
says that a CodeBlock pointer is a strong reference by default, and
clients need to opt in if they want to allow a CodeBlock to jettison.
This is easier to get right because it means that only those
specific owners that want jettison behavior need to worry about it,
while all other pointers are valid by default.

(JSC::CodeBlock::visitChildren): The default visit function keeps
everything alive.

(JSC::CodeBlock::shouldVisitStrongly):
(JSC::CodeBlock::isKnownToBeLiveDuringGC): No need to keep special state
anymore. If we're marked, we're live -- just like any other object.

(JSC::timeToLive): Move this code into CodeBlock.cpp so you can mess
with it without recompiling, and also because it's really a CodeBlock
policy.

(JSC::CodeBlock::WeakReferenceHarvester::visitWeakReferences):
(JSC::CodeBlock::UnconditionalFinalizer::finalizeUnconditionally): Use
internal objects for virtual callbacks because GC objects can't have
vtables.

(JSC::CodeBlock::unlinkIncomingCalls): Remove a fast path check that does
not exist in the copy of this code in ~CodeBlock because it is not
actually an optimization.

(JSC::CodeBlock::replacement):
(JSC::CodeBlock::computeCapabilityLevel): Make these functions generic
instead of virtual because GC objects can't have vtables.

(JSC::CodeBlock::visitStrongly): Deleted.
(JSC::CodeBlock::visitAggregate): Deleted.
(JSC::CodeBlock::visitWeakReferences): Deleted.
(JSC::CodeBlock::finalizeUnconditionally): Deleted.
(JSC::ProgramCodeBlock::replacement): Deleted.
(JSC::ModuleProgramCodeBlock::replacement): Deleted.
(JSC::EvalCodeBlock::replacement): Deleted.
(JSC::FunctionCodeBlock::replacement): Deleted.
(JSC::ProgramCodeBlock::capabilityLevelInternal): Deleted.
(JSC::ModuleProgramCodeBlock::capabilityLevelInternal): Deleted.
(JSC::EvalCodeBlock::capabilityLevelInternal): Deleted.
(JSC::FunctionCodeBlock::capabilityLevelInternal): Deleted.
(JSC::WebAssemblyCodeBlock::replacement): Deleted.
(JSC::WebAssemblyCodeBlock::capabilityLevelInternal): Deleted.

* bytecode/CodeBlock.h:
(JSC::CodeBlock::unlinkedCodeBlock):
(JSC::CodeBlock::addressOfNumParameters):
(JSC::CodeBlock::offsetOfNumParameters):
(JSC::CodeBlock::alternative):
(JSC::CodeBlock::forEachRelatedCodeBlock):
(JSC::CodeBlock::specializationKind):
(JSC::CodeBlock::instructionCount):
(JSC::CodeBlock::setJITCode):
(JSC::CodeBlock::hasBaselineJITProfiling):
(JSC::CodeBlock::capabilityLevelState):
(JSC::CodeBlock::addConstant):
(JSC::CodeBlock::appendExceptionHandler):
(JSC::CodeBlock::setConstantRegisters):
(JSC::CodeBlock::replaceConstant):
(JSC::GlobalCodeBlock::GlobalCodeBlock):
(JSC::ProgramCodeBlock::create):
(JSC::ProgramCodeBlock::createStructure):
(JSC::ProgramCodeBlock::ProgramCodeBlock):
(JSC::ModuleProgramCodeBlock::create):
(JSC::ModuleProgramCodeBlock::createStructure):
(JSC::ModuleProgramCodeBlock::ModuleProgramCodeBlock):
(JSC::EvalCodeBlock::create):
(JSC::EvalCodeBlock::createStructure):
(JSC::EvalCodeBlock::variable):
(JSC::EvalCodeBlock::numVariables):
(JSC::EvalCodeBlock::EvalCodeBlock):
(JSC::EvalCodeBlock::unlinkedEvalCodeBlock):
(JSC::FunctionCodeBlock::create):
(JSC::FunctionCodeBlock::createStructure):
(JSC::FunctionCodeBlock::FunctionCodeBlock):
(JSC::WebAssemblyCodeBlock::create):
(JSC::WebAssemblyCodeBlock::createStructure):
(JSC::WebAssemblyCodeBlock::WebAssemblyCodeBlock):
(JSC::ExecState::uncheckedR):
(JSC::CodeBlock::clearVisitWeaklyHasBeenCalled):
(JSC::CodeBlockSet::mark):
(JSC::ScriptExecutable::forEachCodeBlock):
(JSC::CodeBlock::setAlternative): Deleted.
(JSC::CodeBlock::clearMarks): Deleted. Lots of mechanical changes to
match the logic changes above.

* bytecode/DeferredCompilationCallback.cpp:
(JSC::DeferredCompilationCallback::DeferredCompilationCallback):
(JSC::DeferredCompilationCallback::~DeferredCompilationCallback):
(JSC::DeferredCompilationCallback::compilationDidComplete):
* bytecode/DeferredCompilationCallback.h: Provide a profiledDFGCodeBlock
to all compilation callbacks instead of requiring the callback to
store the profiledDFGCodeBlock. This is how the rest of compilation
around the callback works anyway, and it is easier to do things this
way than to think about how a non-GC malloc'd object should keep its
CodeBlock alive.

* bytecode/EvalCodeCache.h:
(JSC::EvalCodeCache::tryGet):
(JSC::EvalCodeCache::getSlow):
* bytecode/PolymorphicAccess.cpp:
(JSC::AccessCase::generate):
(JSC::PolymorphicAccess::regenerate):
* bytecode/StructureStubInfo.cpp:
(JSC::StructureStubInfo::addAccessCase): Change the owner for write
barrier purposes to CodeBlock.

* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::parse):
* dfg/DFGDesiredTransitions.cpp:
(JSC::DFG::DesiredTransition::reallyAdd):
* dfg/DFGDesiredWeakReferences.cpp:
(JSC::DFG::DesiredWeakReferences::reallyAdd):
* dfg/DFGDriver.cpp:
(JSC::DFG::compile):
* dfg/DFGGraph.cpp:
(JSC::DFG::Graph::Graph): Ditto.

* dfg/DFGJITCode.h:
(JSC::DFG::JITCode::osrEntryBlock):
(JSC::DFG::JITCode::setOSREntryBlock):
(JSC::DFG::JITCode::clearOSREntryBlock): Use helper functions for
accessing osrEntryBlock to help with write barrier stuff.

* dfg/DFGJITFinalizer.cpp:
(JSC::DFG::JITFinalizer::finalize):
(JSC::DFG::JITFinalizer::finalizeFunction):
(JSC::DFG::JITFinalizer::finalizeCommon):
* dfg/DFGOSRExitCompilerCommon.cpp:
(JSC::DFG::adjustAndJumpToTarget): Use CodeBlock as owner instead of
executable.

* dfg/DFGOperations.cpp:
* dfg/DFGPlan.cpp:
(JSC::DFG::Plan::Plan):
(JSC::DFG::Plan::reallyAdd):
(JSC::DFG::Plan::notifyReady):
(JSC::DFG::Plan::finalizeWithoutNotifyingCallback):
(JSC::DFG::Plan::finalizeAndNotifyCallback):
(JSC::DFG::Plan::key):
(JSC::DFG::Plan::rememberCodeBlocks):
(JSC::DFG::Plan::checkLivenessAndVisitChildren):
(JSC::DFG::Plan::clearCodeBlockMarks): Deleted.
* dfg/DFGPlan.h: Use normal GC write barrier concepts to model the fact
that the compiler writes to CodeBlocks.

* dfg/DFGToFTLDeferredCompilationCallback.cpp:
(JSC::DFG::ToFTLDeferredCompilationCallback::ToFTLDeferredCompilationCallback):
(JSC::DFG::ToFTLDeferredCompilationCallback::~ToFTLDeferredCompilationCallback):
(JSC::DFG::ToFTLDeferredCompilationCallback::create):
(JSC::DFG::ToFTLDeferredCompilationCallback::compilationDidBecomeReadyAsynchronously):
(JSC::DFG::ToFTLDeferredCompilationCallback::compilationDidComplete):
* dfg/DFGToFTLDeferredCompilationCallback.h:
* dfg/DFGToFTLForOSREntryDeferredCompilationCallback.cpp:
(JSC::DFG::ToFTLForOSREntryDeferredCompilationCallback::ToFTLForOSREntryDeferredCompilationCallback):
(JSC::DFG::ToFTLForOSREntryDeferredCompilationCallback::~ToFTLForOSREntryDeferredCompilationCallback):
(JSC::DFG::Ref<ToFTLForOSREntryDeferredCompilationCallback>ToFTLForOSREntryDeferredCompilationCallback::create):
(JSC::DFG::ToFTLForOSREntryDeferredCompilationCallback::compilationDidBecomeReadyAsynchronously):
(JSC::DFG::ToFTLForOSREntryDeferredCompilationCallback::compilationDidComplete):
* dfg/DFGToFTLForOSREntryDeferredCompilationCallback.h: We always have
a profiledDFGCodeBlock passed to use -- see above.

* dfg/DFGWorklist.cpp:
(JSC::DFG::Worklist::completeAllPlansForVM):
(JSC::DFG::Worklist::rememberCodeBlocks):
(JSC::DFG::completeAllPlansForVM):
(JSC::DFG::rememberCodeBlocks):
(JSC::DFG::Worklist::clearCodeBlockMarks): Deleted.
(JSC::DFG::clearCodeBlockMarks): Deleted.
* dfg/DFGWorklist.h:
(JSC::DFG::worklistForIndexOrNull): Renamed to use remembered set terminology.

* ftl/FTLJITFinalizer.cpp:
(JSC::FTL::JITFinalizer::finalizeFunction):

* heap/CodeBlockSet.cpp:
(JSC::CodeBlockSet::~CodeBlockSet):
(JSC::CodeBlockSet::add):
(JSC::CodeBlockSet::clearMarksForFullCollection):
(JSC::CodeBlockSet::deleteUnmarkedAndUnreferenced): No need for a fixpoint
anymore since the GC can tell us if we are live.

(JSC::CodeBlockSet::remove):
(JSC::CodeBlockSet::rememberCurrentlyExecutingCodeBlocks):
(JSC::CodeBlockSet::dump):
(JSC::CodeBlockSet::clearMarksForEdenCollection): Deleted. No need for
this logic anymore since the GC will clear our mark bit.

(JSC::CodeBlockSet::traceMarked): Deleted. No need for this marking
fixpoint anymore either.

* heap/CodeBlockSet.h:

* heap/Heap.cpp:
(JSC::Heap::markRoots): Moved some of this logic around to make the
algorithm clearer.

(JSC::Heap::deleteAllCodeBlocks): Deleting CodeBlocks can only clear
pointers immediately; they won't fully delete until the next GC and sweep.

* interpreter/Interpreter.cpp:
(JSC::eval):
* jit/GCAwareJITStubRoutine.h: CodeBlock is owner now.

* jit/JITCode.h:
(JSC::JITCode::isJIT):
(JSC::JITCode::isLowerTier):
(JSC::JITCode::timeToLive): Deleted.

* jit/JITOpcodes.cpp:
(JSC::JIT::emit_op_enter): CodeBlock is owner now.

* jit/JITOperations.cpp:
* jit/JITToDFGDeferredCompilationCallback.cpp:
(JSC::JITToDFGDeferredCompilationCallback::create):
(JSC::JITToDFGDeferredCompilationCallback::compilationDidBecomeReadyAsynchronously):
(JSC::JITToDFGDeferredCompilationCallback::compilationDidComplete):
* jit/JITToDFGDeferredCompilationCallback.h:

* jit/Repatch.cpp:
(JSC::tryCacheGetByID):
(JSC::tryCachePutByID):
(JSC::tryRepatchIn):
(JSC::linkFor):
(JSC::linkPolymorphicCall):
* llint/LLIntSlowPaths.cpp:
(JSC::LLInt::LLINT_SLOW_PATH_DECL):
(JSC::LLInt::setUpCall):
* runtime/CommonSlowPaths.cpp:
(JSC::SLOW_PATH_DECL):
* runtime/CommonSlowPaths.h:
(JSC::CommonSlowPaths::tryCachePutToScopeGlobal):
(JSC::CommonSlowPaths::tryCacheGetFromScopeGlobal): CodeBlock is owner now.

* runtime/Executable.cpp:
(JSC::ExecutableBase::clearCode): Provide a generic clearCode() so that
it can be used on any Executable. This fixes a very subtle bug where
deleteAllCode() does not remove CodeBlocks from non-function executables
that have been saved in stack traces.

(JSC::ScriptExecutable::installCode): WriteBarrier requires special
handling for pointers that may be null.

(JSC::ScriptExecutable::newCodeBlockFor):
(JSC::ScriptExecutable::newReplacementCodeBlockFor):
(JSC::ScriptExecutable::prepareForExecutionImpl): Update for interface
changes.

(JSC::EvalExecutable::visitChildren):
(JSC::ProgramExecutable::visitChildren):
(JSC::ModuleProgramExecutable::visitChildren):
(JSC::FunctionExecutable::visitChildren):
(JSC::WebAssemblyExecutable::visitChildren): Visit weakly because we want
to participate in jettisoning.

(JSC::WebAssemblyExecutable::prepareForExecution):
(JSC::EvalExecutable::clearCode): Deleted.
(JSC::ProgramExecutable::clearCode): Deleted.
(JSC::ModuleProgramExecutable::clearCode): Deleted.
(JSC::FunctionExecutable::clearCode): Deleted.
(JSC::WebAssemblyExecutable::clearCode): Deleted.

* runtime/Executable.h:
(JSC::ExecutableBase::generatedJITCodeForCall):
(JSC::ScriptExecutable::prepareForExecution):
(JSC::ExecutableBase::clearCodeVirtual): Deleted.

* runtime/VM.cpp:
(JSC::VM::VM):
* runtime/VM.h: Provide structures because our GC requires it.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@190450 268f45cc-cd09-0410-ab3c-d52691b4dbfc
44 files changed:
Source/JavaScriptCore/ChangeLog
Source/JavaScriptCore/bytecode/CodeBlock.cpp
Source/JavaScriptCore/bytecode/CodeBlock.h
Source/JavaScriptCore/bytecode/DeferredCompilationCallback.cpp
Source/JavaScriptCore/bytecode/DeferredCompilationCallback.h
Source/JavaScriptCore/bytecode/EvalCodeCache.h
Source/JavaScriptCore/bytecode/PolymorphicAccess.cpp
Source/JavaScriptCore/bytecode/StructureStubInfo.cpp
Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp
Source/JavaScriptCore/dfg/DFGDesiredTransitions.cpp
Source/JavaScriptCore/dfg/DFGDesiredWeakReferences.cpp
Source/JavaScriptCore/dfg/DFGDriver.cpp
Source/JavaScriptCore/dfg/DFGGraph.cpp
Source/JavaScriptCore/dfg/DFGJITCode.h
Source/JavaScriptCore/dfg/DFGJITFinalizer.cpp
Source/JavaScriptCore/dfg/DFGOSRExitCompilerCommon.cpp
Source/JavaScriptCore/dfg/DFGOperations.cpp
Source/JavaScriptCore/dfg/DFGPlan.cpp
Source/JavaScriptCore/dfg/DFGPlan.h
Source/JavaScriptCore/dfg/DFGToFTLDeferredCompilationCallback.cpp
Source/JavaScriptCore/dfg/DFGToFTLDeferredCompilationCallback.h
Source/JavaScriptCore/dfg/DFGToFTLForOSREntryDeferredCompilationCallback.cpp
Source/JavaScriptCore/dfg/DFGToFTLForOSREntryDeferredCompilationCallback.h
Source/JavaScriptCore/dfg/DFGWorklist.cpp
Source/JavaScriptCore/dfg/DFGWorklist.h
Source/JavaScriptCore/ftl/FTLJITFinalizer.cpp
Source/JavaScriptCore/heap/CodeBlockSet.cpp
Source/JavaScriptCore/heap/CodeBlockSet.h
Source/JavaScriptCore/heap/Heap.cpp
Source/JavaScriptCore/interpreter/Interpreter.cpp
Source/JavaScriptCore/jit/GCAwareJITStubRoutine.h
Source/JavaScriptCore/jit/JITCode.h
Source/JavaScriptCore/jit/JITOpcodes.cpp
Source/JavaScriptCore/jit/JITOperations.cpp
Source/JavaScriptCore/jit/JITToDFGDeferredCompilationCallback.cpp
Source/JavaScriptCore/jit/JITToDFGDeferredCompilationCallback.h
Source/JavaScriptCore/jit/Repatch.cpp
Source/JavaScriptCore/llint/LLIntSlowPaths.cpp
Source/JavaScriptCore/runtime/CommonSlowPaths.cpp
Source/JavaScriptCore/runtime/CommonSlowPaths.h
Source/JavaScriptCore/runtime/Executable.cpp
Source/JavaScriptCore/runtime/Executable.h
Source/JavaScriptCore/runtime/VM.cpp
Source/JavaScriptCore/runtime/VM.h