Another problem with "Recommit r265547, and r265610, r265639, r265657"
Wei Mi via llvm-commits
llvm-commits at lists.llvm.org
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.
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).
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
%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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