[PATCH] D34220: [AArch64] Prefer B.cond to CBZ/CBNZ/TBZ/TBNZ when NZCV flags can be set for "free"

Chad Rosier via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Jun 16 06:54:30 PDT 2017


mcrosier added a comment.

In https://reviews.llvm.org/D34220#781653, @MatzeB wrote:

> I'm fine with coding style and transformation.
>
> I'm always a bit sad to see whole new passes for simple/local patterns. There is already other passes like MachineCombiner and MachinePeephole, DeadMachineInstructionElim that also just go through all instruction looking for a pattern and don't need any analysis upfront. Unfortunately none of them is extensible and they are at slightly different positions in the pipeline. I guess we do not need to solve/improve this situation with this patch. Though I reserve the right to ask for a revert and replanning if the bots measure slowdowns in CTMark after committing this.
>
> So LGTM.


Thanks, Matthias.


https://reviews.llvm.org/D34220





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