[all-commits] [llvm/llvm-project] 918982: [LVI] Handle icmp of ashr. (#68010)

[Amara Emerson via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9189822f2c2eca55f6e7adcd26e3f15d65797b76
      https://github.com/llvm/llvm-project/commit/9189822f2c2eca55f6e7adcd26e3f15d65797b76
  Author: Amara Emerson <amara at apple.com>
  Date:   2023-10-20 (Fri, 20 Oct 2023)

  Changed paths:
    M llvm/lib/Analysis/LazyValueInfo.cpp
    M llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll

  Log Message:
  -----------
  [LVI] Handle icmp of ashr. (#68010)

This handles the case where this combine:
icmp sgt (ashr X, ShAmtC), C --> icmp sgt X, ((C + 1) << ShAmtC) - 1

wasn't performed by instcombine.

Proof of the original combine: https://alive2.llvm.org/ce/z/SfpsvX

This is a port of the review in https://reviews.llvm.org/D151911 to
GitHub.