llvm-project/llvm/test/Transforms/Reassociate/subtest.ll

; RUN: opt < %s -reassociate -instcombine -S | FileCheck %s

; With sub reassociation, constant folding can eliminate the 12 and -12 constants.
define i32 @test1(i32 %A, i32 %B) {
; CHECK-LABEL: @test1
; CHECK-NEXT: %Z = sub i32 %A, %B
; CHECK-NEXT: ret i32 %Z
  %X = add i32 -12, %A
  %Y = sub i32 %X, %B
  %Z = add i32 %Y, 12
  ret i32 %Z
}

; PR2047
; With sub reassociation, constant folding can eliminate the uses of %a.
define i32 @test2(i32 %a, i32 %b, i32 %c) nounwind  {
; CHECK-LABEL: @test2
; CHECK-NEXT: %sum = add i32 %c, %b
; CHECK-NEXT: %tmp7 = sub i32 0, %sum
; CHECK-NEXT: ret i32 %tmp7

  %tmp3 = sub i32 %a, %b
  %tmp5 = sub i32 %tmp3, %c
  %tmp7 = sub i32 %tmp5, %a
  ret i32 %tmp7
}