Changeset 223523 in webkit for trunk/Source/JavaScriptCore/dfg/DFGOperations.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/DFGOperations.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/dfg/DFGOperations.cpp

@@ -53 +53 @@
 #include "JSFixedArray.h"
 #include "JSGenericTypedArrayViewConstructorInlines.h"
+#include "JSGlobalObjectFunctions.h"
 #include "JSLexicalEnvironment.h"
 #include "JSMap.h"
@@ -2519 +2520 @@
 }
 
+EncodedJSValue JIT_OPERATION operationGetPrototypeOfObject(ExecState* exec, JSObject* thisObject)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    return JSValue::encode(thisObject->getPrototype(vm, exec));
+}
+
+EncodedJSValue JIT_OPERATION operationGetPrototypeOf(ExecState* exec, EncodedJSValue encodedValue)
+{
+    VM& vm = exec->vm();
+    NativeCallFrameTracer tracer(&vm, exec);
+    auto scope = DECLARE_THROW_SCOPE(vm);
+
+    JSValue thisValue = JSValue::decode(encodedValue).toThis(exec, StrictMode);
+    if (thisValue.isUndefinedOrNull())
+        return throwVMError(exec, scope, createNotAnObjectError(exec, thisValue));
+
+    JSObject* thisObject = jsDynamicCast<JSObject*>(vm, thisValue);
+    if (!thisObject) {
+        JSObject* prototype = thisValue.synthesizePrototype(exec);
+        EXCEPTION_ASSERT(!!scope.exception() == !prototype);
+        if (UNLIKELY(!prototype))
+            return JSValue::encode(JSValue());
+        return JSValue::encode(prototype);
+    }
+
+    scope.release();
+    return JSValue::encode(thisObject->getPrototype(vm, exec));
+}
+
 void JIT_OPERATION operationThrowDFG(ExecState* exec, EncodedJSValue valueToThrow)
 {