[PATCH] D99203: [RISCV] Add TTI support for cpop with Zbb

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


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Comment at: llvm/test/Transforms/LoopIdiom/RISCV/popcnt.ll:29
+; CPOP-NEXT:    br i1 [[TMP2]], label [[WHILE_END:%.*]], label [[WHILE_BODY_PREHEADER:%.*]]
+; CPOP:       while.body.preheader:
+; CPOP-NEXT:    br label [[WHILE_BODY:%.*]]
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frasercrmck wrote:
> Maybe it's late in the day but I expected there not to be a loop here. Am I missing something?
LoopIdiomRecognize requires other passes to do the cleanup. The main goal of LoopIdiomRecognize is to rewrite the loop  into countable form. It does this by putting the ctpop outside the loop and decrement it each iteration. Other passes will need to determine that the loop doesn't do anything else and remove it.


Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99203/new/

https://reviews.llvm.org/D99203