test/Transforms/InstCombine/sdiv-exact-by-power-of-two.ll

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

; Fold
;   x s/EXACT (1 << y)
; to
;   x a>>EXACT y
; iff 1<<y is non-negative

define i8 @t0(i8 %x) {
; CHECK-LABEL: @t0(
; CHECK-NEXT:    [[DIV:%.*]] = ashr exact i8 [[X:%.*]], 5
; CHECK-NEXT:    ret i8 [[DIV]]
;
  %div = sdiv exact i8 %x, 32
  ret i8 %div
}

define i8 @n1(i8 %x) {
; CHECK-LABEL: @n1(
; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X:%.*]], 32
; CHECK-NEXT:    ret i8 [[DIV]]
;
  %div = sdiv i8 %x, 32 ; not exact
  ret i8 %div
}

define i8 @n2(i8 %x) {
; CHECK-LABEL: @n2(
; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i8 [[X:%.*]], -128
; CHECK-NEXT:    [[DIV:%.*]] = zext i1 [[TMP1]] to i8
; CHECK-NEXT:    ret i8 [[DIV]]
;
  %div = sdiv i8 %x, 128 ; negative divisor
  ret i8 %div
}

define <2 x i8> @t3_vec_splat(<2 x i8> %x) {
; CHECK-LABEL: @t3_vec_splat(
; CHECK-NEXT:    [[DIV:%.*]] = ashr exact <2 x i8> [[X:%.*]], <i8 5, i8 5>
; CHECK-NEXT:    ret <2 x i8> [[DIV]]
;
  %div = sdiv exact <2 x i8> %x, <i8 32, i8 32>
  ret <2 x i8> %div
}

define <2 x i8> @t4_vec(<2 x i8> %x) {
; CHECK-LABEL: @t4_vec(
; CHECK-NEXT:    [[DIV:%.*]] = ashr exact <2 x i8> [[X:%.*]], <i8 5, i8 4>
; CHECK-NEXT:    ret <2 x i8> [[DIV]]
;
  %div = sdiv exact <2 x i8> %x, <i8 32, i8 16>
  ret <2 x i8> %div
}

define <2 x i8> @n5_vec_undef(<2 x i8> %x) {
; CHECK-LABEL: @n5_vec_undef(
; CHECK-NEXT:    ret <2 x i8> poison
;
  %div = sdiv exact <2 x i8> %x, <i8 32, i8 undef>
  ret <2 x i8> %div
}

define <2 x i8> @n6_vec_negative(<2 x i8> %x) {
; CHECK-LABEL: @n6_vec_negative(
; CHECK-NEXT:    [[DIV:%.*]] = sdiv exact <2 x i8> [[X:%.*]], <i8 32, i8 -128>
; CHECK-NEXT:    ret <2 x i8> [[DIV]]
;
  %div = sdiv exact <2 x i8> %x, <i8 32, i8 128> ; non-non-negative divisor
  ret <2 x i8> %div
}

; sdiv exact X, (1<<ShAmt) --> ashr exact X, ShAmt (if shl is non-negative)

define i8 @shl1_nsw(i8 %x, i8 %y) {
; CHECK-LABEL: @shl1_nsw(
; CHECK-NEXT:    [[DIV:%.*]] = ashr exact i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    ret i8 [[DIV]]
;
  %shl = shl nsw i8 1, %y
  %div = sdiv exact i8 %x, %shl
  ret i8 %div
}

; negative test - must have nsw

define i8 @shl1_nuw(i8 %x, i8 %y) {
; CHECK-LABEL: @shl1_nuw(
; CHECK-NEXT:    [[SHL:%.*]] = shl nuw i8 1, [[Y:%.*]]
; CHECK-NEXT:    [[DIV:%.*]] = sdiv exact i8 [[X:%.*]], [[SHL]]
; CHECK-NEXT:    ret i8 [[DIV]]
;
  %shl = shl nuw i8 1, %y
  %div = sdiv exact i8 %x, %shl
  ret i8 %div
}

; negative test - must have exact

define i8 @shl1_nsw_not_exact(i8 %x, i8 %y) {
; CHECK-LABEL: @shl1_nsw_not_exact(
; CHECK-NEXT:    [[SHL:%.*]] = shl nuw nsw i8 1, [[Y:%.*]]
; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X:%.*]], [[SHL]]
; CHECK-NEXT:    ret i8 [[DIV]]
;
  %shl = shl nsw i8 1, %y
  %div = sdiv i8 %x, %shl
  ret i8 %div
}

define i8 @prove_exact_with_high_mask(i8 %x, i8 %y) {
; CHECK-LABEL: @prove_exact_with_high_mask(
; CHECK-NEXT:    [[A:%.*]] = ashr i8 [[X:%.*]], 2
; CHECK-NEXT:    [[D:%.*]] = and i8 [[A]], -2
; CHECK-NEXT:    ret i8 [[D]]
;
  %a = and i8 %x, -8
  %d = sdiv i8 %a, 4
  ret i8 %d
}

define i8 @prove_exact_with_high_mask_limit(i8 %x, i8 %y) {
; CHECK-LABEL: @prove_exact_with_high_mask_limit(
; CHECK-NEXT:    [[A:%.*]] = ashr i8 [[X:%.*]], 3
; CHECK-NEXT:    ret i8 [[A]]
;
  %a = and i8 %x, -8
  %d = sdiv i8 %a, 8
  ret i8 %d
}

; negative test - not enough low zeros in dividend

define i8 @not_prove_exact_with_high_mask(i8 %x, i8 %y) {
; CHECK-LABEL: @not_prove_exact_with_high_mask(
; CHECK-NEXT:    [[A:%.*]] = and i8 [[X:%.*]], -8
; CHECK-NEXT:    [[D:%.*]] = sdiv i8 [[A]], 16
; CHECK-NEXT:    ret i8 [[D]]
;
  %a = and i8 %x, -8
  %d = sdiv i8 %a, 16
  ret i8 %d
}

define <2 x i8> @prove_exact_with_high_mask_splat_vec(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @prove_exact_with_high_mask_splat_vec(
; CHECK-NEXT:    [[A:%.*]] = shl <2 x i8> [[X:%.*]], <i8 3, i8 3>
; CHECK-NEXT:    [[D:%.*]] = ashr exact <2 x i8> [[A]], <i8 3, i8 3>
; CHECK-NEXT:    ret <2 x i8> [[D]]
;
  %a = shl <2 x i8> %x, <i8 3, i8 3>
  %d = sdiv <2 x i8> %a, <i8 8, i8 8>
  ret <2 x i8> %d
}

; TODO: Needs knownbits to handle arbitrary vector constants.

define <2 x i8> @prove_exact_with_high_mask_vec(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @prove_exact_with_high_mask_vec(
; CHECK-NEXT:    [[A:%.*]] = shl <2 x i8> [[X:%.*]], <i8 3, i8 2>
; CHECK-NEXT:    [[D:%.*]] = sdiv <2 x i8> [[A]], <i8 8, i8 4>
; CHECK-NEXT:    ret <2 x i8> [[D]]
;
  %a = shl <2 x i8> %x, <i8 3, i8 2>
  %d = sdiv <2 x i8> %a, <i8 8, i8 4>
  ret <2 x i8> %d
}