Changeset 240796 in webkit for trunk/Source/JavaScriptCore/runtime/VM.cpp

Timestamp:

Jan 31, 2019, 11:13:20 AM (6 years ago)

Author:

[email protected]

Message:

[JSC] Do not use InferredValue in non-JIT configuration
​https://bugs.webkit.org/show_bug.cgi?id=194084

Reviewed by Saam Barati.

InferredValue is not meaningful if our VM is non-JIT configuration. InferredValue is used to watch the instantiation of the FunctionExecutable's
JSFunction and SymbolTable's JSScope to explore the chance of folding them into constants in DFG and FTL. If it is instantiated only once, we can
put a watchpoint and fold it into this constant. But if JIT is disabled, we do not need to care it.
Even in non-JIT configuration, we still use InferredValue for FunctionExecutable to determine whether the given FunctionExecutable is preferable
target for poly proto. If JSFunction for the FunctionExecutable is used as a constructor and instantiated more than once, poly proto Structure
seems appropriate for objects created by this JSFunction. But at that time, only thing we would like to know is that whether JSFunction for this
FunctionExecutable is instantiated multiple times. This does not require the full feature of InferredValue, WatchpointState is enough.
To summarize, since nobody uses InferredValue feature in non-JIT configuration, we should not create it.

• bytecode/ObjectAllocationProfileInlines.h:

(JSC::ObjectAllocationProfile::initializeProfile):

• runtime/FunctionExecutable.cpp:

(JSC::FunctionExecutable::finishCreation):
(JSC::FunctionExecutable::visitChildren):

• runtime/FunctionExecutable.h:
• runtime/InferredValue.cpp:

(JSC::InferredValue::create):

• runtime/JSAsyncFunction.cpp:

(JSC::JSAsyncFunction::create):

• runtime/JSAsyncGeneratorFunction.cpp:

(JSC::JSAsyncGeneratorFunction::create):

• runtime/JSFunction.cpp:

(JSC::JSFunction::create):

• runtime/JSFunctionInlines.h:

(JSC::JSFunction::createWithInvalidatedReallocationWatchpoint):

• runtime/JSGeneratorFunction.cpp:

(JSC::JSGeneratorFunction::create):

• runtime/JSSymbolTableObject.h:

(JSC::JSSymbolTableObject::setSymbolTable):

• runtime/SymbolTable.cpp:

(JSC::SymbolTable::finishCreation):

• runtime/VM.cpp:

(JSC::VM::VM):

File:

• trunk/Source/JavaScriptCore/runtime/VM.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/runtime/VM.cpp

@@ -410 +410 @@
     unlinkedModuleProgramCodeBlockStructure.set(*this, UnlinkedModuleProgramCodeBlock::createStructure(*this, 0, jsNull()));
     propertyTableStructure.set(*this, PropertyTable::createStructure(*this, 0, jsNull()));
-    inferredValueStructure.set(*this, InferredValue::createStructure(*this, 0, jsNull()));
+    if (VM::canUseJIT())
+        inferredValueStructure.set(*this, InferredValue::createStructure(*this, 0, jsNull()));
     functionRareDataStructure.set(*this, FunctionRareData::createStructure(*this, 0, jsNull()));
     exceptionStructure.set(*this, Exception::createStructure(*this, 0, jsNull()));