[PATCH] D123512: [MachineCombiner]: Avoid including transient instructions in latency calculation

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

Are you sure this code is doing what it is intended to be doing? If it is adding the latencies (depths) between operands of inserted instructions and their defs, and we say that the latency of transient instructions are ignored, that what adds the latency between the last instruction and whatever will end up using it?

The scheduling info this is using on it's own doesn't suggest this should be changing `mul;sub` to `neg;mla`: https://godbolt.org/z/G1WTW5P9x


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D123512/new/

https://reviews.llvm.org/D123512