[JSC] Optimize more cases of something-compared-to-null/undefined
authorbenjamin@webkit.org <benjamin@webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Wed, 19 Aug 2015 04:09:12 +0000 (04:09 +0000)
committerbenjamin@webkit.org <benjamin@webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Wed, 19 Aug 2015 04:09:12 +0000 (04:09 +0000)
commit8a8d255afc674b3c2284d59a061f593c97ca3716
treeec9b3394017594ee97f24dd6bd3aefddab3161c0
parent752d54e90c7995d0f2014280d94636a7c5dec36b
[JSC] Optimize more cases of something-compared-to-null/undefined
https://bugs.webkit.org/show_bug.cgi?id=148157

Patch by Benjamin Poulain <bpoulain@apple.com> on 2015-08-18
Reviewed by Geoffrey Garen and Filip Pizlo.

Source/JavaScriptCore:

CompareEq is fairly trivial if you assert one of the operands is either
null or undefined. Under those conditions, the only way to have "true"
is to have the other operand be null/undefined or have an object
that masquerades to undefined.

JSC already had a fast path in CompareEqConstant.
With this patch, I generalize this fast path to more cases and try
to eliminate the checks whenever possible.

CompareEq now does the job of CompareEqConstant. If any operand can
be proved to be undefined/other, its edge is set to OtherUse. Whenever
any edge is OtherUse, we generate the fast code we had for CompareEqConstant.

The AbstractInterpreter has additional checks to reduce the node to a constant
whenever possible.

There are two additional changes in this patch:
-The Fixup Phase tries to set edges to OtherUse early. This is done correctly
 in ConstantFoldingPhase but setting it up early helps the phases relying
 on Clobberize.
-The codegen for CompareEqConstant was improved. The reason is the comparison
 for ObjectOrOther could be faster just because the codegen was better.

* dfg/DFGAbstractInterpreterInlines.h:
(JSC::DFG::AbstractInterpreter<AbstractStateType>::executeEffects):
* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::parseBlock):
* dfg/DFGClobberize.h:
(JSC::DFG::clobberize): Deleted.
* dfg/DFGConstantFoldingPhase.cpp:
(JSC::DFG::ConstantFoldingPhase::foldConstants):
* dfg/DFGDoesGC.cpp:
(JSC::DFG::doesGC): Deleted.
* dfg/DFGFixupPhase.cpp:
(JSC::DFG::FixupPhase::fixupNode):
* dfg/DFGNode.h:
(JSC::DFG::Node::isUndefinedOrNullConstant):
* dfg/DFGNodeType.h:
* dfg/DFGPredictionPropagationPhase.cpp:
(JSC::DFG::PredictionPropagationPhase::propagate): Deleted.
* dfg/DFGSafeToExecute.h:
(JSC::DFG::safeToExecute): Deleted.
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compilePeepHoleBranch):
(JSC::DFG::SpeculativeJIT::compare):
* dfg/DFGSpeculativeJIT.h:
(JSC::DFG::SpeculativeJIT::isKnownNotOther):
* dfg/DFGSpeculativeJIT32_64.cpp:
(JSC::DFG::SpeculativeJIT::nonSpeculativeNonPeepholeCompareNullOrUndefined):
(JSC::DFG::SpeculativeJIT::nonSpeculativePeepholeBranchNullOrUndefined):
(JSC::DFG::SpeculativeJIT::nonSpeculativeNonPeepholeCompareNull): Deleted.
(JSC::DFG::SpeculativeJIT::nonSpeculativePeepholeBranchNull): Deleted.
(JSC::DFG::SpeculativeJIT::nonSpeculativeCompareNull): Deleted.
(JSC::DFG::SpeculativeJIT::compile): Deleted.
* dfg/DFGSpeculativeJIT64.cpp:
(JSC::DFG::SpeculativeJIT::nonSpeculativeNonPeepholeCompareNullOrUndefined):
(JSC::DFG::SpeculativeJIT::nonSpeculativePeepholeBranchNullOrUndefined):
(JSC::DFG::SpeculativeJIT::nonSpeculativeNonPeepholeCompareNull): Deleted.
(JSC::DFG::SpeculativeJIT::nonSpeculativePeepholeBranchNull): Deleted.
(JSC::DFG::SpeculativeJIT::nonSpeculativeCompareNull): Deleted.
(JSC::DFG::SpeculativeJIT::compile): Deleted.
* dfg/DFGValidate.cpp:
(JSC::DFG::Validate::validate): Deleted.
* dfg/DFGWatchpointCollectionPhase.cpp:
(JSC::DFG::WatchpointCollectionPhase::handle):
* ftl/FTLCapabilities.cpp:
(JSC::FTL::canCompile):
* ftl/FTLLowerDFGToLLVM.cpp:
(JSC::FTL::DFG::LowerDFGToLLVM::compileCompareEq):
(JSC::FTL::DFG::LowerDFGToLLVM::compileNode): Deleted.
(JSC::FTL::DFG::LowerDFGToLLVM::compileCompareEqConstant): Deleted.
* tests/stress/compare-eq-on-null-and-undefined-non-peephole.js: Added.
(string_appeared_here.useForMath):
(testUseForMath):
* tests/stress/compare-eq-on-null-and-undefined-optimized-in-constant-folding.js: Added.
(string_appeared_here.unreachableCodeTest):
(inlinedCompareToNull):
(inlinedComparedToUndefined):
(warmupInlineFunctions):
(testInlineFunctions):
* tests/stress/compare-eq-on-null-and-undefined.js: Added.
(string_appeared_here.compareConstants):
(opaqueNull):
(opaqueUndefined):
(compareConstantsAndDynamicValues):
(compareDynamicValues):
(compareDynamicValueToItself):
(arrayTesting):
(opaqueCompare1):
(testNullComparatorUpdate):
(opaqueCompare2):
(testUndefinedComparatorUpdate):
(opaqueCompare3):
(testNullAndUndefinedComparatorUpdate):

LayoutTests:

* js/dom/document-all-watchpoint-covers-eliminated-compare-eq-expected.txt: Added.
* js/dom/document-all-watchpoint-covers-eliminated-compare-eq.html: Added.
* js/dom/script-tests/document-all-watchpoint-covers-eliminated-compare-eq.js: Added.
(compareFunction):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@188624 268f45cc-cd09-0410-ab3c-d52691b4dbfc
26 files changed:
LayoutTests/ChangeLog
LayoutTests/js/dom/document-all-watchpoint-covers-eliminated-compare-eq-expected.txt [new file with mode: 0644]
LayoutTests/js/dom/document-all-watchpoint-covers-eliminated-compare-eq.html [new file with mode: 0644]
LayoutTests/js/dom/script-tests/document-all-watchpoint-covers-eliminated-compare-eq.js [new file with mode: 0644]
Source/JavaScriptCore/ChangeLog
Source/JavaScriptCore/dfg/DFGAbstractInterpreterInlines.h
Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp
Source/JavaScriptCore/dfg/DFGClobberize.h
Source/JavaScriptCore/dfg/DFGConstantFoldingPhase.cpp
Source/JavaScriptCore/dfg/DFGDoesGC.cpp
Source/JavaScriptCore/dfg/DFGFixupPhase.cpp
Source/JavaScriptCore/dfg/DFGNode.h
Source/JavaScriptCore/dfg/DFGNodeType.h
Source/JavaScriptCore/dfg/DFGPredictionPropagationPhase.cpp
Source/JavaScriptCore/dfg/DFGSafeToExecute.h
Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp
Source/JavaScriptCore/dfg/DFGSpeculativeJIT.h
Source/JavaScriptCore/dfg/DFGSpeculativeJIT32_64.cpp
Source/JavaScriptCore/dfg/DFGSpeculativeJIT64.cpp
Source/JavaScriptCore/dfg/DFGValidate.cpp
Source/JavaScriptCore/dfg/DFGWatchpointCollectionPhase.cpp
Source/JavaScriptCore/ftl/FTLCapabilities.cpp
Source/JavaScriptCore/ftl/FTLLowerDFGToLLVM.cpp
Source/JavaScriptCore/tests/stress/compare-eq-on-null-and-undefined-non-peephole.js [new file with mode: 0644]
Source/JavaScriptCore/tests/stress/compare-eq-on-null-and-undefined-optimized-in-constant-folding.js [new file with mode: 0644]
Source/JavaScriptCore/tests/stress/compare-eq-on-null-and-undefined.js [new file with mode: 0644]