Changeset 95523 in webkit for trunk/Source/JavaScriptCore/wtf/StdLibExtras.h

Timestamp:

Sep 20, 2011, 2:41:16 AM (14 years ago)

Author:

[email protected]

Message:

DFG JIT does not speculate aggressively enough on GetById
​https://bugs.webkit.org/show_bug.cgi?id=68320

Reviewed by Oliver Hunt.

This adds the ability to access properties directly, by offset.
This optimization kicks in when at the time of DFG compilation,
it appears that the given get_by_id is self-cached by the old JIT.
Two new opcodes get introduced: CheckStructure and GetByOffset.
CheckStructure performs a speculation check on the object's
structure, and returns the storage pointer. GetByOffset performs
a direct read of the field from the storage pointer. Both
CheckStructure and GetByOffset can be CSE'd, so that we can
eliminate redundant structure checks, and redundant reads of the
same field.

This is a 4% speed-up on V8, a 2% slow-down on Kraken, and
neutral on SunSpider.

• bytecode/PredictedType.cpp:

(JSC::predictionFromClassInfo):
(JSC::predictionFromStructure):
(JSC::predictionFromCell):

• bytecode/PredictedType.h:
• dfg/DFGByteCodeParser.cpp:

(JSC::DFG::ByteCodeParser::parseBlock):

• dfg/DFGGenerationInfo.h:

(JSC::DFG::dataFormatToString):
(JSC::DFG::needDataFormatConversion):
(JSC::DFG::GenerationInfo::initStorage):
(JSC::DFG::GenerationInfo::spill):
(JSC::DFG::GenerationInfo::fillStorage):

• dfg/DFGGraph.h:

(JSC::DFG::Graph::predict):
(JSC::DFG::Graph::getPrediction):

• dfg/DFGJITCodeGenerator.cpp:

(JSC::DFG::JITCodeGenerator::fillInteger):
(JSC::DFG::JITCodeGenerator::fillDouble):
(JSC::DFG::JITCodeGenerator::fillJSValue):
(JSC::DFG::JITCodeGenerator::fillStorage):
(JSC::DFG::GPRTemporary::GPRTemporary):

• dfg/DFGJITCodeGenerator.h:

(JSC::DFG::JITCodeGenerator::silentSpillGPR):
(JSC::DFG::JITCodeGenerator::silentFillGPR):
(JSC::DFG::JITCodeGenerator::spill):
(JSC::DFG::JITCodeGenerator::storageResult):
(JSC::DFG::StorageOperand::StorageOperand):
(JSC::DFG::StorageOperand::~StorageOperand):
(JSC::DFG::StorageOperand::index):
(JSC::DFG::StorageOperand::gpr):
(JSC::DFG::StorageOperand::use):

• dfg/DFGNode.h:

(JSC::DFG::OpInfo::OpInfo):
(JSC::DFG::Node::Node):
(JSC::DFG::Node::hasPrediction):
(JSC::DFG::Node::hasStructure):
(JSC::DFG::Node::structure):
(JSC::DFG::Node::hasStorageAccessData):
(JSC::DFG::Node::storageAccessDataIndex):

• dfg/DFGPropagator.cpp:

(JSC::DFG::Propagator::propagateNode):
(JSC::DFG::Propagator::globalVarLoadElimination):
(JSC::DFG::Propagator::getMethodLoadElimination):
(JSC::DFG::Propagator::checkStructureLoadElimination):
(JSC::DFG::Propagator::getByOffsetLoadElimination):
(JSC::DFG::Propagator::performNodeCSE):

• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::SpeculativeJIT::fillSpeculateIntInternal):
(JSC::DFG::SpeculativeJIT::fillSpeculateDouble):
(JSC::DFG::SpeculativeJIT::fillSpeculateCell):
(JSC::DFG::SpeculativeJIT::fillSpeculateBoolean):
(JSC::DFG::SpeculativeJIT::compile):

• wtf/StdLibExtras.h:

(WTF::safeCast):

File:

• trunk/Source/JavaScriptCore/wtf/StdLibExtras.h (modified) (3 diffs)

trunk/Source/JavaScriptCore/wtf/StdLibExtras.h

@@ -27 +27 @@
 #define WTF_StdLibExtras_h
 
-#include <wtf/Assertions.h>
+#include "CheckedArithmetic.h"
+#include "Assertions.h"
 
 // Use these to declare and define a static local variable (static T;) so that
@@ -101 +102 @@
     u.from = from;
     return u.to;
+}
+
+template<typename To, typename From>
+inline To safeCast(From value)
+{
+    ASSERT(isInBounds<To>(value));
+    return static_cast<To>(value);
 }
 
@@ -210 +218 @@
 using WTF::binarySearch;
 using WTF::bitwise_cast;
+using WTF::safeCast;
 
 #endif // WTF_StdLibExtras_h