llvm-project/llvm/test/Transforms/InstCombine/fsub.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instcombine -S | FileCheck %s

; PR4374

define float @test1(float %x, float %y) {
; CHECK-LABEL: @test1(
; CHECK-NEXT:    [[T1:%.*]] = fsub float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    [[T2:%.*]] = fsub float -0.000000e+00, [[T1]]
; CHECK-NEXT:    ret float [[T2]]
;
  %t1 = fsub float %x, %y
  %t2 = fsub float -0.0, %t1
  ret float %t2
}

; Can't do anything with the test above because -0.0 - 0.0 = -0.0, but if we have nsz:
; -(X - Y) --> Y - X

define float @neg_sub_nsz(float %x, float %y) {
; CHECK-LABEL: @neg_sub_nsz(
; CHECK-NEXT:    [[T2:%.*]] = fsub nsz float [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT:    ret float [[T2]]
;
  %t1 = fsub float %x, %y
  %t2 = fsub nsz float -0.0, %t1
  ret float %t2
}

declare void @use(float)

define float @neg_sub_nsz_extra_use(float %x, float %y) {
; CHECK-LABEL: @neg_sub_nsz_extra_use(
; CHECK-NEXT:    [[T1:%.*]] = fsub float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    [[T2:%.*]] = fsub nsz float [[Y]], [[X]]
; CHECK-NEXT:    call void @use(float [[T1]])
; CHECK-NEXT:    ret float [[T2]]
;
  %t1 = fsub float %x, %y
  %t2 = fsub nsz float -0.0, %t1
  call void @use(float %t1)
  ret float %t2
}

; With nsz: Z - (X - Y) --> Z + (Y - X)

define float @sub_sub_nsz(float %x, float %y, float %z) {
; CHECK-LABEL: @sub_sub_nsz(
; CHECK-NEXT:    [[TMP1:%.*]] = fsub nsz float [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT:    [[T2:%.*]] = fadd nsz float [[TMP1]], [[Z:%.*]]
; CHECK-NEXT:    ret float [[T2]]
;
  %t1 = fsub float %x, %y
  %t2 = fsub nsz float %z, %t1
  ret float %t2
}

; Same as above: if 'Z' is not -0.0, swap fsub operands and convert to fadd.

define float @sub_sub_known_not_negzero(float %x, float %y) {
; CHECK-LABEL: @sub_sub_known_not_negzero(
; CHECK-NEXT:    [[TMP1:%.*]] = fsub float [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT:    [[T2:%.*]] = fadd float [[TMP1]], 4.200000e+01
; CHECK-NEXT:    ret float [[T2]]
;
  %t1 = fsub float %x, %y
  %t2 = fsub float 42.0, %t1
  ret float %t2
}

; <rdar://problem/7530098>

define double @test2(double %x, double %y) {
; CHECK-LABEL: @test2(
; CHECK-NEXT:    [[T1:%.*]] = fadd double [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    [[T2:%.*]] = fsub double [[X]], [[T1]]
; CHECK-NEXT:    ret double [[T2]]
;
  %t1 = fadd double %x, %y
  %t2 = fsub double %x, %t1
  ret double %t2
}

; X - C --> X + (-C)

define float @constant_op1(float %x, float %y) {
; CHECK-LABEL: @constant_op1(
; CHECK-NEXT:    [[R:%.*]] = fadd float [[X:%.*]], -4.200000e+01
; CHECK-NEXT:    ret float [[R]]
;
  %r = fsub float %x, 42.0
  ret float %r
}

define <2 x float> @constant_op1_vec(<2 x float> %x, <2 x float> %y) {
; CHECK-LABEL: @constant_op1_vec(
; CHECK-NEXT:    [[R:%.*]] = fadd <2 x float> [[X:%.*]], <float -4.200000e+01, float 4.200000e+01>
; CHECK-NEXT:    ret <2 x float> [[R]]
;
  %r = fsub <2 x float> %x, <float 42.0, float -42.0>
  ret <2 x float> %r
}

define <2 x float> @constant_op1_vec_undef(<2 x float> %x, <2 x float> %y) {
; CHECK-LABEL: @constant_op1_vec_undef(
; CHECK-NEXT:    [[R:%.*]] = fadd <2 x float> [[X:%.*]], <float 0x7FF8000000000000, float 4.200000e+01>
; CHECK-NEXT:    ret <2 x float> [[R]]
;
  %r = fsub <2 x float> %x, <float undef, float -42.0>
  ret <2 x float> %r
}

; X - (-Y) --> X + Y

define float @neg_op1(float %x, float %y) {
; CHECK-LABEL: @neg_op1(
; CHECK-NEXT:    [[R:%.*]] = fadd float [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    ret float [[R]]
;
  %negy = fsub float -0.0, %y
  %r = fsub float %x, %negy
  ret float %r
}

define <2 x float> @neg_op1_vec(<2 x float> %x, <2 x float> %y) {
; CHECK-LABEL: @neg_op1_vec(
; CHECK-NEXT:    [[R:%.*]] = fadd <2 x float> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    ret <2 x float> [[R]]
;
  %negy = fsub <2 x float> <float -0.0, float -0.0>, %y
  %r = fsub <2 x float> %x, %negy
  ret <2 x float> %r
}

define <2 x float> @neg_op1_vec_undef(<2 x float> %x, <2 x float> %y) {
; CHECK-LABEL: @neg_op1_vec_undef(
; CHECK-NEXT:    [[R:%.*]] = fadd <2 x float> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    ret <2 x float> [[R]]
;
  %negy = fsub <2 x float> <float -0.0, float undef>, %y
  %r = fsub <2 x float> %x, %negy
  ret <2 x float> %r
}