[PATCH] D28719: [NVPTX] Improve lowering of llvm.ctlz.

[Justin Lebar via Phabricator via llvm-commits]

jlebar created this revision.
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- Disable "ctlz speculation", which inserts a branch on every ctlz(x) which has defined behavior on x == 0 to check whether x is, in fact zero.

- Add DAG patterns that avoid re-truncating or re-expanding the result of the 16- and 64-bit ctz instructions.


https://reviews.llvm.org/D28719

Files:
  llvm/lib/Target/NVPTX/NVPTXISelLowering.h
  llvm/lib/Target/NVPTX/NVPTXInstrInfo.td
  llvm/test/CodeGen/NVPTX/ctlz.ll

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