[PATCH] D110739: [CostModel] Update default cost model for sadd/ssub overflow to match TargetLowering

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: spatel, rogfer01, RKSimon.
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The expansion for these was updated in https://reviews.llvm.org/D47927 but the cost model was not adjusted.

I believe the cost model was also incorrect for the old expansion. The expansion prior to D47927 <https://reviews.llvm.org/D47927> used 3 icmps using LHS, RHS, and Result to calculate theirs signs. Then 2 icmps to compare the signs. Followed by an And. The previous cost model was using 3 icmps and 2 selects. Digging back through git blame, those 2 selects used to be 2 icmps, but were changed in https://reviews.llvm.org/D90681


https://reviews.llvm.org/D110739

Files:
  llvm/include/llvm/CodeGen/BasicTTIImpl.h
  llvm/test/Analysis/CostModel/AArch64/arith-ssat.ll
  llvm/test/Analysis/CostModel/ARM/arith-overflow.ll
  llvm/test/Analysis/CostModel/ARM/arith-ssat.ll
  llvm/test/Analysis/CostModel/X86/arith-overflow.ll
  llvm/test/Analysis/CostModel/X86/arith-ssat.ll
  llvm/test/Transforms/LoopVectorize/AArch64/intrinsiccost.ll
  llvm/test/Transforms/LoopVectorize/ARM/mve-saddsatcost.ll

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