Another problem with "Recommit r265547, and r265610, r265639, r265657"

Wei Mi via llvm-commits llvm-commits at
Wed Apr 27 14:53:59 PDT 2016

>> And does it matter that %vreg29 isn't marked as dead? If so, who should do that marking?
> The liveness analysis is supposed to do that IIRC. The dead flags are supposed to be properly set otherwise it is considered a bug.
> Cheers,
> -Quentin

dead and kill flags are marked by LiveVariables analysis. However I
find the following paragraph of comment in Passes.cpp:

  // FIXME: Once TwoAddressInstruction pass no longer uses kill flags,
  // LiveVariables can be removed completely, and LiveIntervals can be directly
  // computed. (We still either need to regenerate kill flags after regalloc, or
  // preferably fix the scavenger to not depend on them).
  addPass(&LiveVariablesID, false);

That is why I don't see LiveVariables analysis required after phi
eliminatation pass. I guess following passes shouldn't depend on
dead/kill flags but depend on LiveIntervals analysis to get the
precise interval.

%vreg29 at 528B becomes dead after RegisterCoalescer pass but its live
interval is not updated accordingly, and RegisterCoalescer declares to
preserve LiveIntervals. So may be it is RegisterCoalescer to be


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