Changeset 167897 in webkit for trunk/Source/JavaScriptCore/bytecode/CodeBlock.h

Timestamp:

Apr 28, 2014, 12:01:07 PM (11 years ago)

Author:

[email protected]

Message:

GC should be able to remove things from the DFG worklist and cancel on-going compilations if it knows that the compilation would already be invalidated
​https://bugs.webkit.org/show_bug.cgi?id=132166

Reviewed by Oliver Hunt and Mark Hahnenberg.

The GC can aid type inference by removing structures that are dead and jettisoning
code that relies on those structures. This can dramatically accelerate type inference
for some tricky programs.

Unfortunately, we previously pinned any structures that enqueued compilations depended
on. This means that if you're on a machine that only runs a single compilation thread
and where compilations are relatively slow, you have a high chance of large numbers of
structures being pinned during any GC since the compilation queue is likely to be full
of random stuff.

This comprehensively fixes this issue by allowing the GC to remove compilation plans
if the things they depend on are dead, and to even cancel safepointed compilations.

• bytecode/CodeBlock.cpp:

(JSC::CodeBlock::shouldImmediatelyAssumeLivenessDuringScan):
(JSC::CodeBlock::isKnownToBeLiveDuringGC):
(JSC::CodeBlock::finalizeUnconditionally):

• bytecode/CodeBlock.h:

(JSC::CodeBlock::shouldImmediatelyAssumeLivenessDuringScan): Deleted.

• dfg/DFGDesiredIdentifiers.cpp:

(JSC::DFG::DesiredIdentifiers::DesiredIdentifiers):

• dfg/DFGDesiredIdentifiers.h:
• dfg/DFGDesiredWatchpoints.h:
• dfg/DFGDesiredWeakReferences.cpp:

(JSC::DFG::DesiredWeakReferences::DesiredWeakReferences):

• dfg/DFGDesiredWeakReferences.h:
• dfg/DFGGraphSafepoint.cpp:

(JSC::DFG::GraphSafepoint::GraphSafepoint):

• dfg/DFGGraphSafepoint.h:
• dfg/DFGPlan.cpp:

(JSC::DFG::Plan::Plan):
(JSC::DFG::Plan::compileInThread):
(JSC::DFG::Plan::compileInThreadImpl):
(JSC::DFG::Plan::notifyCompiling):
(JSC::DFG::Plan::notifyCompiled):
(JSC::DFG::Plan::notifyReady):
(JSC::DFG::Plan::checkLivenessAndVisitChildren):
(JSC::DFG::Plan::isKnownToBeLiveDuringGC):
(JSC::DFG::Plan::cancel):
(JSC::DFG::Plan::visitChildren): Deleted.

• dfg/DFGPlan.h:
• dfg/DFGSafepoint.cpp:

(JSC::DFG::Safepoint::Result::~Result):
(JSC::DFG::Safepoint::Result::didGetCancelled):
(JSC::DFG::Safepoint::Safepoint):
(JSC::DFG::Safepoint::~Safepoint):
(JSC::DFG::Safepoint::checkLivenessAndVisitChildren):
(JSC::DFG::Safepoint::isKnownToBeLiveDuringGC):
(JSC::DFG::Safepoint::cancel):
(JSC::DFG::Safepoint::visitChildren): Deleted.

• dfg/DFGSafepoint.h:

(JSC::DFG::Safepoint::Result::Result):

• dfg/DFGWorklist.cpp:

(JSC::DFG::Worklist::compilationState):
(JSC::DFG::Worklist::waitUntilAllPlansForVMAreReady):
(JSC::DFG::Worklist::removeAllReadyPlansForVM):
(JSC::DFG::Worklist::completeAllReadyPlansForVM):
(JSC::DFG::Worklist::visitWeakReferences):
(JSC::DFG::Worklist::removeDeadPlans):
(JSC::DFG::Worklist::runThread):
(JSC::DFG::Worklist::visitChildren): Deleted.

• dfg/DFGWorklist.h:
• ftl/FTLCompile.cpp:

(JSC::FTL::compile):

• ftl/FTLCompile.h:
• heap/CodeBlockSet.cpp:

(JSC::CodeBlockSet::rememberCurrentlyExecutingCodeBlocks):

• heap/Heap.cpp:

(JSC::Heap::markRoots):
(JSC::Heap::visitCompilerWorklistWeakReferences):
(JSC::Heap::removeDeadCompilerWorklistEntries):
(JSC::Heap::visitWeakHandles):
(JSC::Heap::collect):
(JSC::Heap::visitCompilerWorklists): Deleted.

• heap/Heap.h:

File:

• trunk/Source/JavaScriptCore/bytecode/CodeBlock.h (modified) (2 diffs)

trunk/Source/JavaScriptCore/bytecode/CodeBlock.h

@@ -948 +948 @@
     NO_RETURN_DUE_TO_CRASH void endValidationDidFail();
 
+    bool isKnownToBeLiveDuringGC(); // Will only return valid results when called during GC. Assumes that you've already established that the owner executable is live.
+
 protected:
     virtual void visitWeakReferences(SlotVisitor&) override;
@@ -1002 +1004 @@
     void dumpRareCaseProfile(PrintStream&, const char* name, RareCaseProfile*, bool& hasPrintedProfiling);
         
-#if ENABLE(DFG_JIT)
-    bool shouldImmediatelyAssumeLivenessDuringScan()
-    {
-        // Interpreter and Baseline JIT CodeBlocks don't need to be jettisoned when
-        // their weak references go stale. So if a basline JIT CodeBlock gets
-        // scanned, we can assume that this means that it's live.
-        if (!JITCode::isOptimizingJIT(jitType()))
-            return true;
-
-        // For simplicity, we don't attempt to jettison code blocks during GC if
-        // they are executing. Instead we strongly mark their weak references to
-        // allow them to continue to execute soundly.
-        if (m_mayBeExecuting)
-            return true;
-
-        if (Options::forceDFGCodeBlockLiveness())
-            return true;
-
-        return false;
-    }
-#else
-    bool shouldImmediatelyAssumeLivenessDuringScan() { return true; }
-#endif
+    bool shouldImmediatelyAssumeLivenessDuringScan();
     
     void propagateTransitions(SlotVisitor&);