https://bugs.webkit.org/show_bug.cgi?id=125523

Reviewed by Mark Hahnenberg.
        
Adds the ability to DCE more things. It's now the case that if a node is completely
pure, we clear NodeMustGenerate and the node becomes a DCE candidate.

* dfg/DFGAbstractInterpreterInlines.h:
(JSC::DFG::AbstractInterpreter<AbstractStateType>::executeEffects):
* dfg/DFGCSEPhase.cpp:
(JSC::DFG::CSEPhase::performNodeCSE):
* dfg/DFGClobberize.h:
(JSC::DFG::clobberize):
* dfg/DFGDCEPhase.cpp:
(JSC::DFG::DCEPhase::cleanVariables):
* dfg/DFGFixupPhase.cpp:
(JSC::DFG::FixupPhase::fixupNode):
* dfg/DFGGraph.h:
(JSC::DFG::Graph::clobbersWorld):
* dfg/DFGNodeType.h:
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileAdd):
* dfg/DFGSpeculativeJIT.h:
* dfg/DFGSpeculativeJIT32_64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* dfg/DFGSpeculativeJIT64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* ftl/FTLLowerDFGToLLVM.cpp:
(JSC::FTL::LowerDFGToLLVM::compileNode):
(JSC::FTL::LowerDFGToLLVM::compileValueAdd):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@161218 268f45cc-cd09-0410-ab3c-d52691b4dbfc