[PATCH] D37177: [X86] Don't disable slow INC/DEC if optimizing for size

[Craig Topper via Phabricator via llvm-commits]

craig.topper updated this revision to Diff 112791.
craig.topper added a comment.

Use a simpler test case.

I'd also like to see less feature flags. Particularly the ones that encode the CPU name into a flag.

Is there anything in the CPU scheduler model that captures INC/DEC being slow. I think its only "slow" because it doesn't update the carry flag and creates false dependencies later.

I also think it should be disabled on earlier CPUs than Haswell. I don't think anything change in microarchitecture at Haswell that made it different. gcc disables INC/DEC at least back to "core2".


https://reviews.llvm.org/D37177

Files:
  lib/Target/X86/X86ISelLowering.cpp
  lib/Target/X86/X86InstrArithmetic.td
  lib/Target/X86/X86InstrCompiler.td
  lib/Target/X86/X86InstrInfo.td
  test/CodeGen/X86/slow-incdec.ll

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