[llvm] [CodeGen] Avoid sinking vector comparisons during CodeGenPrepare (PR #113158)

[Paul Walker via llvm-commits]

https://github.com/paulwalker-arm commented:

Hi @david-arm, sorry for the late review but when looking at the tests I think I've misunderstood our original conversation.  While `hasMultipleConditionRegisters` seems like an overly specific question for the affected code, on reflection I'm not sure that matters.

Looking at `vector_loop_with_icmp` I can see that not sinking the compare improves the output, but isn't the original output only bad because the code generator is missing an obvious `extractelt (setcc X, C), IndexC => setcc (extractelt X, IndexC), C` combine? which would be better all-round.

https://github.com/llvm/llvm-project/pull/113158