[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: http://svn.webkit.org/repository/webkit/trunk@188624 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/dfg/DFGAbstractInterpreterInlines.h b/Source/JavaScriptCore/dfg/DFGAbstractInterpreterInlines.h
index 1bd8f69..5e2a60b 100644
--- a/Source/JavaScriptCore/dfg/DFGAbstractInterpreterInlines.h
+++ b/Source/JavaScriptCore/dfg/DFGAbstractInterpreterInlines.h
@@ -1139,8 +1139,7 @@
case CompareLessEq:
case CompareGreater:
case CompareGreaterEq:
- case CompareEq:
- case CompareEqConstant: {
+ case CompareEq: {
JSValue leftConst = forNode(node->child1()).value();
JSValue rightConst = forNode(node->child2()).value();
if (leftConst && rightConst) {
@@ -1180,13 +1179,40 @@
}
}
- if (node->op() == CompareEqConstant || node->op() == CompareEq) {
+ if (node->op() == CompareEq) {
SpeculatedType leftType = forNode(node->child1()).m_type;
SpeculatedType rightType = forNode(node->child2()).m_type;
if (!valuesCouldBeEqual(leftType, rightType)) {
setConstant(node, jsBoolean(false));
break;
}
+
+ if (leftType == SpecOther)
+ std::swap(leftType, rightType);
+ if (rightType == SpecOther) {
+ // Undefined and Null are always equal when compared to eachother.
+ if (!(leftType & ~SpecOther)) {
+ setConstant(node, jsBoolean(true));
+ break;
+ }
+
+ // Any other type compared to Null or Undefined is always false
+ // as long as the MasqueradesAsUndefined watchpoint is valid.
+ //
+ // MasqueradesAsUndefined only matters for SpecObjectOther, other
+ // cases are always "false".
+ if (!(leftType & (SpecObjectOther | SpecOther))) {
+ setConstant(node, jsBoolean(false));
+ break;
+ }
+
+ if (!(leftType & SpecOther) && m_graph.masqueradesAsUndefinedWatchpointIsStillValid(node->origin.semantic)) {
+ JSGlobalObject* globalObject = m_graph.globalObjectFor(node->origin.semantic);
+ m_graph.watchpoints().addLazily(globalObject->masqueradesAsUndefinedWatchpoint());
+ setConstant(node, jsBoolean(false));
+ break;
+ }
+ }
}
if (node->child1() == node->child2()) {
@@ -1206,7 +1232,6 @@
case CompareLessEq:
case CompareGreaterEq:
case CompareEq:
- case CompareEqConstant:
setConstant(node, jsBoolean(true));
break;
default:
