• fpizlo@apple.com's avatar
    Fold typedArray.length if typedArray is constant · ce995b22
    fpizlo@apple.com authored
    Reviewed by Sam Weinig.
    This was meant to be easy. The problem is that there was no good place for putting
    the folding of typedArray.length to a constant. You can't quite do it in the
    bytecode parser because at that point you don't yet know if typedArray is really
    a typed array. You can't do it as part of constant folding because the folder
    assumes that it can opportunistically forward-flow a constant value without changing
    the IR; this doesn't work since we need to first change the IR to register a
    desired watchpoint and only after that can we introduce that constant. We could have
    done it in Fixup but that would have been awkward since Fixup's code for turning a
    GetById of "length" into GetArrayLength is already somewhat complex. We could have
    done it in CSE but CSE is already fairly gnarly and will probably get rewritten.
    So I introduced a new phase, called StrengthReduction. This phase should have any
    transformations that don't requite CFA or CSE and that it would be weird to put into
    those other phases.
    I also took the opportunity to refactor some of the other folding code.
    This also adds a test, but the test couldn't quite be a LayoutTests/js/regress so I
    introduced the notion of JavaScriptCore/tests/stress.
    The goal of this patch isn't really to improve performance or anything like that.
    It adds an optimization for completeness, and in doing so it unlocks a bunch of new
    possibilities. The one that I'm most excited about is revealing array length checks
    in DFG IR, which will allow for array bounds check hoisting and elimination.
    * CMakeLists.txt:
    * GNUmakefile.list.am:
    * JavaScriptCore.vcxproj/JavaScriptCore.vcxproj:
    * JavaScriptCore.xcodeproj/project.pbxproj:
    * dfg/DFGAbstractInterpreterInlines.h:
    * dfg/DFGClobberize.h:
    * dfg/DFGFixupPhase.cpp:
    * dfg/DFGGraph.cpp:
    * dfg/DFGGraph.h:
    * dfg/DFGNode.h:
    * dfg/DFGNodeType.h:
    * dfg/DFGPlan.cpp:
    * dfg/DFGPredictionPropagationPhase.cpp:
    * dfg/DFGSafeToExecute.h:
    * dfg/DFGSpeculativeJIT.cpp:
    * dfg/DFGSpeculativeJIT32_64.cpp:
    * dfg/DFGSpeculativeJIT64.cpp:
    * dfg/DFGStrengthReductionPhase.cpp: Added.
    * dfg/DFGStrengthReductionPhase.h: Added.
    * dfg/DFGWatchpointCollectionPhase.cpp:
    * ftl/FTLCapabilities.cpp:
    * ftl/FTLLowerDFGToLLVM.cpp:
    * jsc.cpp:
    * runtime/ArrayBufferView.h:
    * tests/stress: Added.
    * tests/stress/fold-typed-array-properties.js: Added.
    Reviewed by Sam Weinig.
    Add Source/JavaScriptCore/tests/stress to the set of JS tests. This is where you
    should put tests that run just like JSRegress but don't run as part of LayoutTests.
    Currently I'm using it for tests that require some surgical support from jsc.cpp.
    * Scripts/run-javascriptcore-tests:
    git-svn-id: http://svn.webkit.org/repository/webkit/trunk@160292 268f45cc-cd09-0410-ab3c-d52691b4dbfc
ChangeLog 396 KB