[PATCH] D140852: [Patch 4/4]: Use cannoical patterns `(A > C1 && A < C2)` and `(A & B != C)` in `isKnownNonZero`

[Noah Goldstein via Phabricator via llvm-commits]

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Both patterns where missed because they go through a level of
indirection:

1. `A > C1 && A < C2` cannonicalizes to `ICMP_ULT (A + C3, C4)`
  - Try and match this pattern explicitly in `isKnownNonNullFromDominatingCondition`

2. `A & B != C`
  - Since `cmp ne (A & B, 0)` implies `cmp ne (A, 0)` just match that as an additional generic pattern in `isKnownNonNullFromDominatingCondition`. This was already done in the final worklist loop.

The rationale is C-code like:

  int foo(int A, int B) {
      if(A % 2 == 0) {
          // A is provably odd but `isKnownNonZero(A)` will not find any
          // cmp directly acting on A. The same applies for the ICMP_ULT
          // case.
          return !!(A * B);
      }
      ...
  }


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D140852

Files:
  llvm/include/llvm/IR/InstrTypes.h
  llvm/lib/Analysis/ValueTracking.cpp
  llvm/lib/IR/Instructions.cpp
  llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
  llvm/test/Transforms/InstCombine/icmp-binop.ll

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