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    DFG fixup phase should be responsible for inserting ValueToInt32's as needed... · 027ed671
    fpizlo@apple.com authored
    DFG fixup phase should be responsible for inserting ValueToInt32's as needed and it should use Phantom to keep the original values alive in case of OSR exit
    Reviewed by Michael Saboff.
    This fixes an embarrassing OSR exit liveness bug. It also simplifies the code. We were
    already using FixupPhase as the place where conversion nodes get inserted. ValueToInt32
    was the only exception to that rule, and that was one of the reasons why we had this bug.
    Henceforth ValueToInt32 is only inserted by FixupPhase, and only when it is necessary:
    we have a BitOp that will want a ToInt32 conversion and the operand is not predicted to
    already be an int32. If FixupPhase inserts any ValueToInt32's then the BitOp will no
    longer appear to use the original operand, which will make OSR exit think that the
    original operand is dead. We work around this they way we always do: insert a Phantom on
    the original operands right after the BitOp. This ensures that any OSR exit in any of the
    ValueToInt32's or in the BitOp itself will have values for the original inputs.
    * dfg/DFGBackwardsPropagationPhase.cpp:
    * dfg/DFGByteCodeParser.cpp:
    * dfg/DFGFixupPhase.cpp:
    * dfg/DFGPredictionPropagationPhase.cpp:
    * tests/stress/bit-op-value-to-int32-input-liveness.js: Added.
    git-svn-id: http://svn.webkit.org/repository/webkit/trunk@161465 268f45cc-cd09-0410-ab3c-d52691b4dbfc
DFGByteCodeParser.cpp 162 KB