https://bugs.webkit.org/show_bug.cgi?id=95013

Reviewed by Oliver Hunt.

This uniformly breaks up all array accesses into up to three parts:
        
1) The type check, using a newly introduced CheckArray node, in addition to possibly
   a CheckStructure node. We were already inserting the CheckStructure prior to this
   patch. The CheckArray node will be automatically eliminated if the thing it was
   checking for had already been checked for, either intentionally (a CheckStructure
   inserted based on the array profile of this access) or accidentally (some checks,
   typically a CheckStructure, inserted for some unrelated operations). The
   CheckArray node may not be inserted if the array type is non-specific (Generic or
   ForceExit).
        
2) The storage load using GetIndexedPropertyStorage. Previously, this only worked for
   GetByVal. Now it works for all array accesses. The storage load may not be
   inserted if the mode of array access does not permit CSE of storage loads (like
   non-specific modes or Arguments).
        
3) The access itself: one of GetByVal, PutByVal, PutByValAlias, ArrayPush, ArrayPop,
   GetArrayLength, StringCharAt, or StringCharCodeAt.
        
This means that the type check can be subjected to CSE even if the CFA isn't smart
enough to reason about it (yet!). It also means that the storage load can always be
subjected to CSE; previously CSE on storage load only worked for array loads and not
other forms of access. Finally, it removes the bizarre behavior that
GetIndexedPropertyStorage previously had: previously, it was responsible for the type
check in some cases, but not others; this made reasoning about the CFA really
confusing.
        
This change also disables late refinement of array mode, since I decided that
supporting that feature is both confusing and likely unprofitable. The array modes are
now locked in in the first fixup run after prediction propagation. Of course,
refinements from Generic to something else would not have been a problem; we could
reenable those if we thought we really needed to.

* dfg/DFGAbstractState.cpp:
(JSC::DFG::AbstractState::execute):
* dfg/DFGArgumentsSimplificationPhase.cpp:
(JSC::DFG::ArgumentsSimplificationPhase::run):
* dfg/DFGArrayMode.cpp:
(JSC::DFG::fromStructure):
(DFG):
(JSC::DFG::refineArrayMode):
* dfg/DFGArrayMode.h:
(DFG):
(JSC::DFG::modeIsJSArray):
(JSC::DFG::lengthNeedsStorage):
(JSC::DFG::modeIsSpecific):
(JSC::DFG::modeSupportsLength):
* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::ByteCodeParser):
(JSC::DFG::ByteCodeParser::getArrayMode):
(ByteCodeParser):
(JSC::DFG::ByteCodeParser::getArrayModeAndEmitChecks):
(JSC::DFG::ByteCodeParser::handleIntrinsic):
(JSC::DFG::ByteCodeParser::parseBlock):
* dfg/DFGCFGSimplificationPhase.cpp:
(JSC::DFG::CFGSimplificationPhase::mergeBlocks):
* dfg/DFGCSEPhase.cpp:
(JSC::DFG::CSEPhase::CSEPhase):
(JSC::DFG::CSEPhase::checkStructureElimination):
(CSEPhase):
(JSC::DFG::CSEPhase::checkArrayElimination):
(JSC::DFG::CSEPhase::getIndexedPropertyStorageLoadElimination):
(JSC::DFG::CSEPhase::performNodeCSE):
(JSC::DFG::performCSE):
* dfg/DFGCSEPhase.h:
(DFG):
* dfg/DFGCommon.h:
* dfg/DFGConstantFoldingPhase.cpp:
(JSC::DFG::ConstantFoldingPhase::foldConstants):
* dfg/DFGDriver.cpp:
(JSC::DFG::compile):
* dfg/DFGFixupPhase.cpp:
(JSC::DFG::FixupPhase::fixupNode):
(JSC::DFG::FixupPhase::checkArray):
(FixupPhase):
(JSC::DFG::FixupPhase::blessArrayOperation):
* dfg/DFGGraph.cpp:
(JSC::DFG::Graph::Graph):
(DFG):
(JSC::DFG::Graph::dump):
(JSC::DFG::Graph::collectGarbage):
* dfg/DFGGraph.h:
(Graph):
(JSC::DFG::Graph::vote):
(JSC::DFG::Graph::substitute):
* dfg/DFGNode.h:
(JSC::DFG::Node::hasArrayMode):
(JSC::DFG::Node::setArrayMode):
* dfg/DFGNodeType.h:
(DFG):
* dfg/DFGOperations.cpp:
* dfg/DFGPhase.h:
(DFG):
* dfg/DFGPredictionPropagationPhase.cpp:
(JSC::DFG::PredictionPropagationPhase::propagate):
(JSC::DFG::PredictionPropagationPhase::mergeDefaultFlags):
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::checkArray):
(JSC::DFG::SpeculativeJIT::useChildren):
(JSC::DFG::SpeculativeJIT::compilePutByValForIntTypedArray):
(JSC::DFG::SpeculativeJIT::compilePutByValForFloatTypedArray):
(JSC::DFG::SpeculativeJIT::compileGetIndexedPropertyStorage):
(JSC::DFG::SpeculativeJIT::compileGetArrayLength):
* dfg/DFGSpeculativeJIT.h:
(SpeculativeJIT):
* dfg/DFGSpeculativeJIT32_64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* dfg/DFGSpeculativeJIT64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* dfg/DFGStructureCheckHoistingPhase.cpp:
(JSC::DFG::StructureCheckHoistingPhase::run):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@126715 268f45cc-cd09-0410-ab3c-d52691b4dbfc