[all-commits] [llvm/llvm-project] 38992d: [InstCombine] improve fold for icmp-ugt-ashr

[ZCBing via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 38992d2c5e1d671cf5d4f03c7331ce98b2cdda94
      https://github.com/llvm/llvm-project/commit/38992d2c5e1d671cf5d4f03c7331ce98b2cdda94
  Author: Chenbing Zheng <Chenbing.Zheng at streamcomputing.com>
  Date:   2022-06-09 (Thu, 09 Jun 2022)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/test/Transforms/InstCombine/icmp-shr.ll

  Log Message:
  -----------
  [InstCombine] improve fold for icmp-ugt-ashr

Existing condition for
fold icmp ugt (ashr X, ShAmtC), C --> icmp ugt X, ((C + 1) << ShAmtC) - 1
missed some boundary. It cause this fold don't work for some cases, and the
reason is due to signed number overflow.

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D127188