[all-commits] [llvm/llvm-project] b89ae1: [InstSimplify] fold fcmp using isKnownNeverInfinit...

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  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: b89ae102e6f5ed3760f1ae5788bd76ef8e9d9490
      https://github.com/llvm/llvm-project/commit/b89ae102e6f5ed3760f1ae5788bd76ef8e9d9490
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2020-07-26 (Sun, 26 Jul 2020)

  Changed paths:
    M llvm/lib/Analysis/InstructionSimplify.cpp
    M llvm/test/Transforms/InstSimplify/floating-point-compare.ll

  Log Message:
  -----------
  [InstSimplify] fold fcmp using isKnownNeverInfinity + isKnownNeverNaN

Follow-up to D84035 / rG7393d7574c09.
This sidesteps a question of FMF/poison on fcmp raised in PR46077:
http://bugs.llvm.org/PR46077

https://alive2.llvm.org/ce/z/TCsyzD
  define i1 @src(float %x) {
  %0:
    %x42 = fadd nnan ninf float %x, 42.000000
    %r = fcmp ueq float %x42, inf
    ret i1 %r
  }
  =>
  define i1 @tgt(float %x) {
  %0:
    ret i1 0
  }
  Transformation seems to be correct!

https://alive2.llvm.org/ce/z/FQaH7a
  define i1 @src(i8 %x) {
  %0:
    %cast = uitofp i8 %x to float
    %r = fcmp one float inf, %cast
    ret i1 %r
  }
  =>
  define i1 @tgt(i8 %x) {
  %0:
    ret i1 1
  }
  Transformation seems to be correct!