[PATCH] D49499: [X86] Prefer unpckhpd over movhlps in isel for fake unary cases

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


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Comment at: lib/Target/X86/X86InstrSSE.td:831
                       Sched<[SchedWriteFShuffle.XMM]>;
   let isCommutable = 1 in
   def MOVHLPSrr : PSI<0x12, MRMSrcReg, (outs VR128:$dst),
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craig.topper wrote:
> RKSimon wrote:
> > Shouldn't it only be commutable if it has SSE2? Looking at X86InstrInfo::commuteInstructionImpl it asserts that SSE2 is available, it doesn't early out....
> It's checked in findCommutedOpIndices which should be called before commuteInstructionImpl.
Cheers - I wrote that code and had completely forgotten....


https://reviews.llvm.org/D49499