[PATCH] D101074: [X86] Canonicalize SGT/UGT compares with constants to use SGE/UGE to reduce the number of EFLAGs reads. (PR48760)

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:23472
   if (Op0.getSimpleValueType().isInteger()) {
+    // Attempt to canonicalize SGT/UGT -> SGE/UGE compares with constant which
+    // reduces the number of EFLAGs reads. The equivalent for SLE/ULE -> SLT/ULT
----------------
RKSimon wrote:
> RKSimon wrote:
> > craig.topper wrote:
> > > Should this be inside emitFlagsForSetcc? That way setcc+brcond works. LowerBRCOND doesn't call LowerSETCC.
> > Yes, I was hoping to move it inside TranslateX86CC later (see TODO) - as it felt like this caused far too many diffs as an initial patch - I'll can try again now that the SLT/ULT handling has been dropped.
> Yes there's a huge amount of test case churn that I'd prefer to do as a follow up patch for review - and just stick with the TODO while we handle the select/cmov cases first.
Ok.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D101074/new/

https://reviews.llvm.org/D101074