Changeset 223523 in webkit for trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp

Timestamp:

Oct 17, 2017, 5:02:01 AM (8 years ago)

Author:

Yusuke Suzuki

Message:

[JSC] proto getter should be fast
​https://bugs.webkit.org/show_bug.cgi?id=178067

Reviewed by Saam Barati.

JSTests:

• stress/dfg-object-proto-accessor.js: Added.

(shouldBe):
(shouldThrow):
(target):

• stress/dfg-object-proto-getter.js: Added.

(shouldBe):
(shouldThrow):
(target):

• stress/dfg-object-prototype-of.js: Added.

(shouldBe):
(shouldThrow):
(target):

• stress/dfg-reflect-get-prototype-of.js: Added.

(shouldBe):
(shouldThrow):
(target):

• stress/object-get-prototype-of-filtered.js: Added.

(shouldBe):
(shouldThrow):
(target):
(i.Cocoa):

• stress/object-get-prototype-of-mono-proto.js: Added.

(shouldBe):
(makePolyProtoObject.foo.C):
(makePolyProtoObject.foo):
(makePolyProtoObject):
(target):

• stress/object-get-prototype-of-poly-mono-proto.js: Added.

(shouldBe):
(makePolyProtoObject.foo.C):
(makePolyProtoObject.foo):
(makePolyProtoObject):
(target):

• stress/object-get-prototype-of-poly-proto.js: Added.

(shouldBe):
(makePolyProtoObject.foo.C):
(makePolyProtoObject.foo):
(makePolyProtoObject):
(target):

• stress/object-proto-getter-filtered.js: Added.

(shouldBe):
(shouldThrow):
(target):
(i.Cocoa):

• stress/object-proto-getter-poly-mono-proto.js: Added.

(shouldBe):
(makePolyProtoObject.foo.C):
(makePolyProtoObject.foo):
(makePolyProtoObject):
(target):

• stress/object-proto-getter-poly-proto.js: Added.

(shouldBe):
(makePolyProtoObject.foo.C):
(makePolyProtoObject.foo):
(makePolyProtoObject):
(target):

• stress/object-prototype-proto-accessors-should-throw-on-undefined-this.js:
• stress/string-proto.js: Added.

(shouldBe):
(target):

Source/JavaScriptCore:

In our ES6 class implementation, we access proto field to retrieve super constructor.
Currently, it is handled as an usual getter call to a generic function. And DFG just emits
Call node for this. It is inefficient since typically we know the prototype of the given
object when accessing object.__proto__ since we emit CheckStructure for this object.
If Structure has mono proto, we can immediately fold it to constant value. If it is poly proto,
we can still change this to efficient access to poly proto slot.

This patch implements GetPrototypeOf DFG node. This node efficiently accesses to prototype of
the given object. And in AI and ByteCodeParser phase, we attempt to fold it to constant.
ByteCodeParser's folding is a bit important since we have callee.__proto__ code to get super
constructor. If we can change this to constant, we can reify CallLinkInfo with this constant.
This paves the way to optimizing ArrayConstructor super calls[1], which is particularly important
for ARES-6 ML.

And we also optimize Reflect.getPrototypeOf and Object.getPrototypeOf with this GetPrototypeOf node.

Currently, proto access for poly proto object is not handled well in IC. But we add code handling
poly proto in GetPrototypeOf since Reflect.getPrototypeOf and Object.getPrototypeOf can use it.
Once IC starts handling poly proto & intrinsic getter well, this code will be used for that too.

This patch improves SixSpeed super.es6 by 3.42x.

baseline patched

super.es6 123.6666+-3.9917 ^{36.1684+-1.0351} definitely 3.4192x faster

[1]: ​https://bugs.webkit.org/show_bug.cgi?id=178064

• dfg/DFGAbstractInterpreterInlines.h:

(JSC::DFG::AbstractInterpreter<AbstractStateType>::executeEffects):

• dfg/DFGByteCodeParser.cpp:

(JSC::DFG::ByteCodeParser::handleIntrinsicCall):
(JSC::DFG::ByteCodeParser::handleIntrinsicGetter):
(JSC::DFG::ByteCodeParser::handleGetById):

• dfg/DFGClobberize.h:

(JSC::DFG::clobberize):

• dfg/DFGDoesGC.cpp:

(JSC::DFG::doesGC):

• dfg/DFGFixupPhase.cpp:

(JSC::DFG::FixupPhase::fixupNode):
(JSC::DFG::FixupPhase::fixupGetPrototypeOf):

• dfg/DFGHeapLocation.cpp:

(WTF::printInternal):

• dfg/DFGHeapLocation.h:
• dfg/DFGNode.h:

(JSC::DFG::Node::hasHeapPrediction):
(JSC::DFG::Node::shouldSpeculateFunction):

• dfg/DFGNodeType.h:
• dfg/DFGOperations.cpp:
• dfg/DFGOperations.h:
• dfg/DFGPredictionPropagationPhase.cpp:
• dfg/DFGSafeToExecute.h:

(JSC::DFG::safeToExecute):

• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::SpeculativeJIT::speculateFunction):
(JSC::DFG::SpeculativeJIT::speculateFinalObject):
(JSC::DFG::SpeculativeJIT::compileGetPrototypeOf):

• dfg/DFGSpeculativeJIT.h:
• dfg/DFGSpeculativeJIT32_64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• dfg/DFGSpeculativeJIT64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• ftl/FTLCapabilities.cpp:

(JSC::FTL::canCompile):

• ftl/FTLLowerDFGToB3.cpp:

(JSC::FTL::DFG::LowerDFGToB3::compileNode):
(JSC::FTL::DFG::LowerDFGToB3::compileGetPrototypeOf):
(JSC::FTL::DFG::LowerDFGToB3::compileInstanceOf):

• jit/IntrinsicEmitter.cpp:

(JSC::IntrinsicGetterAccessCase::canEmitIntrinsicGetter):
(JSC::IntrinsicGetterAccessCase::emitIntrinsicGetter):

• runtime/Intrinsic.cpp:

(JSC::intrinsicName):

• runtime/Intrinsic.h:
• runtime/JSGlobalObject.cpp:

(JSC::JSGlobalObject::init):

• runtime/JSGlobalObjectFunctions.cpp:

(JSC::globalFuncProtoGetter):

• runtime/JSGlobalObjectFunctions.h:
• runtime/ObjectConstructor.cpp:
• runtime/ReflectObject.cpp:

LayoutTests:

• js/object-literal-shorthand-construction-expected.txt:
• js/script-tests/object-literal-shorthand-construction.js:

(set 2):
(get 1):

• js/script-tests/sloppy-getter-setter-global-object.js:
• js/sloppy-getter-setter-global-object-expected.txt:

File:

• trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp (modified) (5 diffs)

trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp

@@ -239 +239 @@
     bool handleDOMJITCall(Node* callee, int resultOperand, const DOMJIT::Signature*, int registerOffset, int argumentCountIncludingThis, SpeculatedType prediction, const ChecksFunctor& insertChecks);
     template<typename ChecksFunctor>
-    bool handleIntrinsicGetter(int resultOperand, const GetByIdVariant& intrinsicVariant, Node* thisNode, const ChecksFunctor& insertChecks);
+    bool handleIntrinsicGetter(int resultOperand, SpeculatedType prediction, const GetByIdVariant& intrinsicVariant, Node* thisNode, const ChecksFunctor& insertChecks);
     template<typename ChecksFunctor>
     bool handleTypedArrayConstructor(int resultOperand, InternalFunction*, int registerOffset, int argumentCountIncludingThis, TypedArrayType, const ChecksFunctor& insertChecks);
@@ -2600 +2600 @@
     }
 
+    case ObjectGetPrototypeOfIntrinsic: {
+        if (argumentCountIncludingThis != 2)
+            return false;
+
+        insertChecks();
+        set(VirtualRegister(resultOperand), addToGraph(GetPrototypeOf, OpInfo(0), OpInfo(prediction), get(virtualRegisterForArgument(1, registerOffset))));
+        return true;
+    }
+
+    case ReflectGetPrototypeOfIntrinsic: {
+        if (argumentCountIncludingThis != 2)
+            return false;
+
+        insertChecks();
+        set(VirtualRegister(resultOperand), addToGraph(GetPrototypeOf, OpInfo(0), OpInfo(prediction), Edge(get(virtualRegisterForArgument(1, registerOffset)), ObjectUse)));
+        return true;
+    }
+
     case IsTypedArrayViewIntrinsic: {
         ASSERT(argumentCountIncludingThis == 2);
@@ -2947 +2965 @@
 
 template<typename ChecksFunctor>
-bool ByteCodeParser::handleIntrinsicGetter(int resultOperand, const GetByIdVariant& variant, Node* thisNode, const ChecksFunctor& insertChecks)
+bool ByteCodeParser::handleIntrinsicGetter(int resultOperand, SpeculatedType prediction, const GetByIdVariant& variant, Node* thisNode, const ChecksFunctor& insertChecks)
 {
     switch (variant.intrinsic()) {
@@ -3011 +3029 @@
         set(VirtualRegister(resultOperand), addToGraph(GetTypedArrayByteOffset, OpInfo(ArrayMode(arrayType).asWord()), thisNode));
 
+        return true;
+    }
+
+    case UnderscoreProtoIntrinsic: {
+        insertChecks();
+
+        bool canFold = !variant.structureSet().isEmpty();
+        JSValue prototype;
+        variant.structureSet().forEach([&] (Structure* structure) {
+            auto getPrototypeMethod = structure->classInfo()->methodTable.getPrototype;
+            MethodTable::GetPrototypeFunctionPtr defaultGetPrototype = JSObject::getPrototype;
+            if (getPrototypeMethod != defaultGetPrototype) {
+                canFold = false;
+                return;
+            }
+
+            if (structure->hasPolyProto()) {
+                canFold = false;
+                return;
+            }
+            if (!prototype)
+                prototype = structure->storedPrototype();
+            else if (prototype != structure->storedPrototype())
+                canFold = false;
+        });
+
+        // OK, only one prototype is found. We perform constant folding here.
+        // This information is important for super's constructor call to get new.target constant.
+        if (prototype && canFold) {
+            set(VirtualRegister(resultOperand), weakJSConstant(prototype));
+            return true;
+        }
+
+        set(VirtualRegister(resultOperand), addToGraph(GetPrototypeOf, OpInfo(0), OpInfo(prediction), thisNode));
         return true;
     }
@@ -3797 +3849 @@
     Node* getter = addToGraph(GetGetter, loadedValue);
 
-    if (handleIntrinsicGetter(destinationOperand, variant, base,
+    if (handleIntrinsicGetter(destinationOperand, prediction, variant, base,
             [&] () {
                 addToGraph(CheckCell, OpInfo(m_graph.freeze(variant.intrinsicFunction())), getter);