xref: /llvm-project/llvm/test/Transforms/InstCombine/fold-log2-ceil-idiom.ll (revision 095d49da76be09143582e07a807c86d3b4334dec)

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
; RUN: opt < %s -passes=instcombine -S | FileCheck %s

define i32 @log2_ceil_idiom(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[X]], -1
; CHECK-NEXT:    [[TMP2:%.*]] = call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[TMP1]], i1 false)
; CHECK-NEXT:    [[RET:%.*]] = sub nuw nsw i32 32, [[TMP2]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i5 @log2_ceil_idiom_trunc(i32 %x) {
; CHECK-LABEL: define i5 @log2_ceil_idiom_trunc(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[X]], -1
; CHECK-NEXT:    [[TMP2:%.*]] = call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[TMP1]], i1 false)
; CHECK-NEXT:    [[TMP3:%.*]] = sub nsw i32 0, [[TMP2]]
; CHECK-NEXT:    [[RET:%.*]] = trunc i32 [[TMP3]] to i5
; CHECK-NEXT:    ret i5 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %trunc = trunc i32 %ctlz to i5
  %xor = xor i5 %trunc, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i5
  %ret = add i5 %xor, %zext
  ret i5 %ret
}

define i64 @log2_ceil_idiom_zext(i32 %x) {
; CHECK-LABEL: define i64 @log2_ceil_idiom_zext(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[X]], -1
; CHECK-NEXT:    [[TMP2:%.*]] = call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[TMP1]], i1 false)
; CHECK-NEXT:    [[TMP3:%.*]] = sub nuw nsw i32 32, [[TMP2]]
; CHECK-NEXT:    [[RET:%.*]] = zext nneg i32 [[TMP3]] to i64
; CHECK-NEXT:    ret i64 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ext = zext nneg i32 %xor to i64
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i64
  %ret = add i64 %ext, %zext
  ret i64 %ret
}

define i32 @log2_ceil_idiom_power2_test2(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_power2_test2(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[X]], -1
; CHECK-NEXT:    [[TMP2:%.*]] = call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[TMP1]], i1 false)
; CHECK-NEXT:    [[RET:%.*]] = sub nuw nsw i32 32, [[TMP2]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ne i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i32 @log2_ceil_idiom_commuted(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_commuted(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[X]], -1
; CHECK-NEXT:    [[TMP2:%.*]] = call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[TMP1]], i1 false)
; CHECK-NEXT:    [[RET:%.*]] = sub nuw nsw i32 32, [[TMP2]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %zext, %xor
  ret i32 %ret
}

define i32 @log2_ceil_idiom_multiuse1(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_multiuse1(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    call void @use32(i32 [[CTPOP]])
; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[X]], -1
; CHECK-NEXT:    [[TMP2:%.*]] = call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[TMP1]], i1 false)
; CHECK-NEXT:    [[RET:%.*]] = sub nuw nsw i32 32, [[TMP2]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  call void @use32(i32 %ctpop)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

; Negative tests

define i32 @log2_ceil_idiom_x_may_be_zero(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_x_may_be_zero(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 false)
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[CTLZ]], 31
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
; CHECK-NEXT:    [[RET:%.*]] = add nuw nsw i32 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 false)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i4 @log2_ceil_idiom_trunc_too_short(i32 %x) {
; CHECK-LABEL: define i4 @log2_ceil_idiom_trunc_too_short(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[CTLZ]] to i4
; CHECK-NEXT:    [[XOR:%.*]] = xor i4 [[TRUNC]], -1
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i4
; CHECK-NEXT:    [[RET:%.*]] = add i4 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i4 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %trunc = trunc i32 %ctlz to i4
  %xor = xor i4 %trunc, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i4
  %ret = add i4 %xor, %zext
  ret i4 %ret
}

define i32 @log2_ceil_idiom_mismatched_operands(i32 %x, i32 %y) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_mismatched_operands(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[CTLZ]], 31
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[Y]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
; CHECK-NEXT:    [[RET:%.*]] = add nuw nsw i32 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %y)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i32 @log2_ceil_idiom_wrong_constant(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_wrong_constant(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[CTLZ]], 30
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
; CHECK-NEXT:    [[RET:%.*]] = add nuw nsw i32 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 30
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i32 @log2_ceil_idiom_not_a_power2_test1(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_not_a_power2_test1(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[CTLZ]], 31
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
; CHECK-NEXT:    [[RET:%.*]] = add nuw nsw i32 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp eq i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i32 @log2_ceil_idiom_not_a_power2_test2(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_not_a_power2_test2(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[CTLZ]], 31
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 2
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
; CHECK-NEXT:    [[RET:%.*]] = add nuw nsw i32 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 2
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i32 @log2_ceil_idiom_multiuse2(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_multiuse2(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    call void @use32(i32 [[CTLZ]])
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[CTLZ]], 31
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
; CHECK-NEXT:    [[RET:%.*]] = add nuw nsw i32 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  call void @use32(i32 %ctlz)
  %xor = xor i32 %ctlz, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i32 @log2_ceil_idiom_multiuse3(i32 %x) {
; CHECK-LABEL: define i32 @log2_ceil_idiom_multiuse3(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[CTLZ]], 31
; CHECK-NEXT:    call void @use32(i32 [[XOR]])
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i32
; CHECK-NEXT:    [[RET:%.*]] = add nuw nsw i32 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  call void @use32(i32 %xor)
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i32
  %ret = add i32 %xor, %zext
  ret i32 %ret
}

define i5 @log2_ceil_idiom_trunc_multiuse4(i32 %x) {
; CHECK-LABEL: define i5 @log2_ceil_idiom_trunc_multiuse4(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    [[TRUNC:%.*]] = trunc nuw i32 [[CTLZ]] to i5
; CHECK-NEXT:    call void @use5(i5 [[TRUNC]])
; CHECK-NEXT:    [[XOR:%.*]] = xor i5 [[TRUNC]], -1
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i5
; CHECK-NEXT:    [[RET:%.*]] = add i5 [[XOR]], [[ZEXT]]
; CHECK-NEXT:    ret i5 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %trunc = trunc i32 %ctlz to i5
  call void @use5(i5 %trunc)
  %xor = xor i5 %trunc, 31
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i5
  %ret = add i5 %xor, %zext
  ret i5 %ret
}

define i64 @log2_ceil_idiom_zext_multiuse5(i32 %x) {
; CHECK-LABEL: define i64 @log2_ceil_idiom_zext_multiuse5(
; CHECK-SAME: i32 [[X:%.*]]) {
; CHECK-NEXT:    [[CTLZ:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctlz.i32(i32 [[X]], i1 true)
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[CTLZ]], 31
; CHECK-NEXT:    [[EXT:%.*]] = zext nneg i32 [[XOR]] to i64
; CHECK-NEXT:    call void @use64(i64 [[EXT]])
; CHECK-NEXT:    [[CTPOP:%.*]] = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 [[X]])
; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ugt i32 [[CTPOP]], 1
; CHECK-NEXT:    [[ZEXT:%.*]] = zext i1 [[CMP]] to i64
; CHECK-NEXT:    [[RET:%.*]] = add nuw nsw i64 [[EXT]], [[ZEXT]]
; CHECK-NEXT:    ret i64 [[RET]]
;
  %ctlz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
  %xor = xor i32 %ctlz, 31
  %ext = zext nneg i32 %xor to i64
  call void @use64(i64 %ext)
  %ctpop = tail call i32 @llvm.ctpop.i32(i32 %x)
  %cmp = icmp ugt i32 %ctpop, 1
  %zext = zext i1 %cmp to i64
  %ret = add i64 %ext, %zext
  ret i64 %ret
}

declare void @use5(i5)
declare void @use32(i32)
declare void @use64(i64)

declare i32 @llvm.ctlz.i32(i32, i1)
declare i32 @llvm.ctpop.i32(i32)