Changeset 199073 in webkit for trunk/Source/JavaScriptCore/builtins

Timestamp:

Apr 5, 2016, 2:36:25 PM (9 years ago)

Author:

[email protected]

Message:

We should support the ability to do a non-effectful getById
​https://bugs.webkit.org/show_bug.cgi?id=156116

Reviewed by Benjamin Poulain.

Currently, there is no way in JS to do a non-effectful getById. A non-effectful getById is
useful because it enables us to take different code paths based on values that we would
otherwise not be able to have knowledge of. This patch adds this new feature called
try_get_by_id that will attempt to do as much of a get_by_id as possible without performing
an effectful behavior. Thus, try_get_by_id will return the value if the slot is a value, the
GetterSetter object if the slot is a normal accessor (not a CustomGetterSetter) and
undefined if the slot is unset. If the slot is proxied or any other cases then the result
is null. In theory, if we ever wanted to check for null we could add a sentinal object to
the global object that indicates we could not get the result.

In order to implement this feature we add a new enum GetByIdKind that indicates what to do
for accessor properties in PolymorphicAccess. If the GetByIdKind is pure then we treat the
get_by_id the same way we would for load and return the value at the appropriate offset.
Additionally, in order to make sure the we can properly compare the GetterSetter object
with === GetterSetters are now JSObjects. This comes at the cost of eight extra bytes on the
GetterSetter object but it vastly simplifies the patch. Additionally, the extra bytes are
likely to have little to no impact on memory usage as normal accessors are generally rare.

• JavaScriptCore.xcodeproj/project.pbxproj:
• builtins/BuiltinExecutables.cpp:

(JSC::BuiltinExecutables::createDefaultConstructor):
(JSC::BuiltinExecutables::createBuiltinExecutable):
(JSC::createBuiltinExecutable):
(JSC::BuiltinExecutables::createExecutable):
(JSC::createExecutableInternal): Deleted.

• builtins/BuiltinExecutables.h:
• bytecode/BytecodeIntrinsicRegistry.h:
• bytecode/BytecodeList.json:
• bytecode/BytecodeUseDef.h:

(JSC::computeUsesForBytecodeOffset):
(JSC::computeDefsForBytecodeOffset):

• bytecode/CodeBlock.cpp:

(JSC::CodeBlock::dumpBytecode):

• bytecode/PolymorphicAccess.cpp:

(JSC::AccessCase::tryGet):
(JSC::AccessCase::generate):
(WTF::printInternal):

• bytecode/PolymorphicAccess.h:

(JSC::AccessCase::isGet): Deleted.
(JSC::AccessCase::isPut): Deleted.
(JSC::AccessCase::isIn): Deleted.

• bytecode/StructureStubInfo.cpp:

(JSC::StructureStubInfo::reset):

• bytecode/StructureStubInfo.h:
• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::emitTryGetById):

• bytecompiler/BytecodeGenerator.h:
• bytecompiler/NodesCodegen.cpp:

(JSC::BytecodeIntrinsicNode::emit_intrinsic_tryGetById):

• dfg/DFGSpeculativeJIT32_64.cpp:

(JSC::DFG::SpeculativeJIT::cachedGetById):

• dfg/DFGSpeculativeJIT64.cpp:

(JSC::DFG::SpeculativeJIT::cachedGetById):

• ftl/FTLLowerDFGToB3.cpp:

(JSC::FTL::DFG::LowerDFGToB3::getById):

• jit/JIT.cpp:

(JSC::JIT::privateCompileMainPass):
(JSC::JIT::privateCompileSlowCases):

• jit/JIT.h:
• jit/JITInlineCacheGenerator.cpp:

(JSC::JITGetByIdGenerator::JITGetByIdGenerator):

• jit/JITInlineCacheGenerator.h:
• jit/JITInlines.h:

(JSC::JIT::callOperation):

• jit/JITOperations.cpp:
• jit/JITOperations.h:
• jit/JITPropertyAccess.cpp:

(JSC::JIT::emitGetByValWithCachedId):
(JSC::JIT::emit_op_try_get_by_id):
(JSC::JIT::emitSlow_op_try_get_by_id):
(JSC::JIT::emit_op_get_by_id):

• jit/JITPropertyAccess32_64.cpp:

(JSC::JIT::emitGetByValWithCachedId):
(JSC::JIT::emit_op_try_get_by_id):
(JSC::JIT::emitSlow_op_try_get_by_id):
(JSC::JIT::emit_op_get_by_id):

• jit/Repatch.cpp:

(JSC::repatchByIdSelfAccess):
(JSC::appropriateOptimizingGetByIdFunction):
(JSC::appropriateGenericGetByIdFunction):
(JSC::tryCacheGetByID):
(JSC::repatchGetByID):
(JSC::resetGetByID):

• jit/Repatch.h:
• jsc.cpp:

(GlobalObject::finishCreation):
(functionGetGetterSetter):
(functionCreateBuiltin):

• llint/LLIntData.cpp:

(JSC::LLInt::Data::performAssertions):

• llint/LLIntSlowPaths.cpp:

(JSC::LLInt::LLINT_SLOW_PATH_DECL):

• llint/LLIntSlowPaths.h:
• llint/LowLevelInterpreter.asm:
• runtime/GetterSetter.cpp:
• runtime/GetterSetter.h:
• runtime/JSType.h:
• runtime/PropertySlot.cpp:

(JSC::PropertySlot::getPureResult):

• runtime/PropertySlot.h:
• runtime/ProxyObject.cpp:

(JSC::ProxyObject::getOwnPropertySlotCommon):

• tests/stress/try-get-by-id.js: Added.

(tryGetByIdText):
(getCaller.obj.1.throw.new.Error.let.func):
(getCaller.obj.1.throw.new.Error):
(throw.new.Error.get let):
(throw.new.Error.):
(throw.new.Error.let.get createBuiltin):
(get let):
(let.get createBuiltin):
(let.func):
(get let.func):
(get throw):

Location:

trunk/Source/JavaScriptCore/builtins

Files:

• BuiltinExecutables.cpp (modified) (3 diffs)
• BuiltinExecutables.h (modified) (1 diff)

trunk/Source/JavaScriptCore/builtins/BuiltinExecutables.cpp

@@ -36 +36 @@
 namespace JSC {
 
-static UnlinkedFunctionExecutable* createExecutableInternal(VM&, const SourceCode&, const Identifier&, ConstructorKind, ConstructAbility);
-
 BuiltinExecutables::BuiltinExecutables(VM& vm)
     : m_vm(vm)
@@ -55 +53 @@
         break;
     case ConstructorKind::Base:
-        return createExecutableInternal(m_vm, makeSource(baseConstructorCode), name, constructorKind, ConstructAbility::CanConstruct);
+        return createExecutable(m_vm, makeSource(baseConstructorCode), name, constructorKind, ConstructAbility::CanConstruct);
     case ConstructorKind::Derived:
-        return createExecutableInternal(m_vm, makeSource(derivedConstructorCode), name, constructorKind, ConstructAbility::CanConstruct);
+        return createExecutable(m_vm, makeSource(derivedConstructorCode), name, constructorKind, ConstructAbility::CanConstruct);
     }
     ASSERT_NOT_REACHED();
@@ -65 +63 @@
 UnlinkedFunctionExecutable* BuiltinExecutables::createBuiltinExecutable(const SourceCode& code, const Identifier& name, ConstructAbility constructAbility)
 {
-    return createExecutableInternal(m_vm, code, name, ConstructorKind::None, constructAbility);
+    return createExecutable(m_vm, code, name, ConstructorKind::None, constructAbility);
 }
 
 UnlinkedFunctionExecutable* createBuiltinExecutable(VM& vm, const SourceCode& code, const Identifier& name, ConstructAbility constructAbility)
 {
-    return createExecutableInternal(vm, code, name, ConstructorKind::None, constructAbility);
+    return BuiltinExecutables::createExecutable(vm, code, name, ConstructorKind::None, constructAbility);
 }
 
-UnlinkedFunctionExecutable* createExecutableInternal(VM& vm, const SourceCode& source, const Identifier& name, ConstructorKind constructorKind, ConstructAbility constructAbility)
+UnlinkedFunctionExecutable* BuiltinExecutables::createExecutable(VM& vm, const SourceCode& source, const Identifier& name, ConstructorKind constructorKind, ConstructAbility constructAbility)
 {
     JSTextPosition positionBeforeLastNewline;

trunk/Source/JavaScriptCore/builtins/BuiltinExecutables.h

@@ -53 +53 @@
     UnlinkedFunctionExecutable* createDefaultConstructor(ConstructorKind, const Identifier& name);
 
+    JS_EXPORT_PRIVATE static UnlinkedFunctionExecutable* createExecutable(VM&, const SourceCode&, const Identifier&, ConstructorKind, ConstructAbility);
 private:
     void finalize(Handle<Unknown>, void* context) override;