[PATCH] D86346: [SimplifyCFG] Accumulate cost against budget

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


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Comment at: llvm/lib/Transforms/Utils/SimplifyCFG.cpp:2051
   int BudgetRemaining =
     PHINodeFoldingThreshold * TargetTransformInfo::TCC_Basic;
   for (PHINode &PN : EndBB->phis()) {
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Please add a new `cl::opt` for that.
I believe, the threshold should be the branch misprediction cost,
i.e. if it takes less cost (latency) to execute the branch
then to wrongly predict that it won't be executed,
but then rewind and execute it anyways, we should just execute it.

So i'd go with `20`.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D86346/new/

https://reviews.llvm.org/D86346