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InstCombine: Fold is.fpclass for single infinity to fcmp
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llvm.is.fpclass(x, fcPosInf) -> fcmp oeq x, +inf
llvm.is.fpclass(x, fcNegInf) -> fcmp oeq x, -inf
llvm.is.fpclass(x, ~fcPosInf) -> fcmp one x, +inf
llvm.is.fpclass(x, ~fcNegInf) -> fcmp one x, -inf

llvm.is.fpclass(x, fcPosInf|fcNan) -> fcmp ueq x, +inf
llvm.is.fpclass(x, fcNegInf|fcNan) -> fcmp ueq, -inf
llvm.is.fpclass(x, ~fcPosInf & ~fcNan) -> fcmp one, x, +inf
llvm.is.fpclass(x, ~fcNegInf & ~fcNan) -> fcmp one, x, -inf

This regresses some of the logic of fcmp tests. These should be restored
in a future patch to better handle combining logic of fcmp and class.
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@arsenm
arsenm committed Mar 17, 2023
1 parent 9f93b71 commit ec2234a
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Showing 3 changed files with 109 additions and 56 deletions.
41 changes: 36 additions & 5 deletions llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View file
Expand Up @@ -846,6 +846,11 @@ Instruction *InstCombinerImpl::foldIntrinsicIsFPClass(IntrinsicInst &II) {
Value *Src1 = II.getArgOperand(1);
const ConstantInt *CMask = cast<ConstantInt>(Src1);
FPClassTest Mask = static_cast<FPClassTest>(CMask->getZExtValue());
const bool IsUnordered = (Mask & fcNan) == fcNan;
const bool IsOrdered = (Mask & fcNan) == fcNone;
const FPClassTest OrderedMask = Mask & ~fcNan;
const FPClassTest OrderedInvertedMask = ~OrderedMask & ~fcNan;

const bool IsStrict = II.isStrictFP();

Value *FNegSrc;
Expand All @@ -862,6 +867,37 @@ Instruction *InstCombinerImpl::foldIntrinsicIsFPClass(IntrinsicInst &II) {
return replaceOperand(II, 0, FAbsSrc);
}

// TODO: is.fpclass(x, fcInf) -> fabs(x) == inf

if ((OrderedMask == fcPosInf || OrderedMask == fcNegInf) &&
(IsOrdered || IsUnordered) && !IsStrict) {
// is.fpclass(x, fcPosInf) -> fcmp oeq x, +inf
// is.fpclass(x, fcNegInf) -> fcmp oeq x, -inf
// is.fpclass(x, fcPosInf|fcNan) -> fcmp ueq x, +inf
// is.fpclass(x, fcNegInf|fcNan) -> fcmp ueq x, -inf
Constant *Inf =
ConstantFP::getInfinity(Src0->getType(), OrderedMask == fcNegInf);
Value *EqInf = IsUnordered ? Builder.CreateFCmpUEQ(Src0, Inf)
: Builder.CreateFCmpOEQ(Src0, Inf);

EqInf->takeName(&II);
return replaceInstUsesWith(II, EqInf);
}

if ((OrderedInvertedMask == fcPosInf || OrderedInvertedMask == fcNegInf) &&
(IsOrdered || IsUnordered) && !IsStrict) {
// is.fpclass(x, ~fcPosInf) -> fcmp one x, +inf
// is.fpclass(x, ~fcNegInf) -> fcmp one x, -inf
// is.fpclass(x, ~fcPosInf|fcNan) -> fcmp une x, +inf
// is.fpclass(x, ~fcNegInf|fcNan) -> fcmp une x, -inf
Constant *Inf = ConstantFP::getInfinity(Src0->getType(),
OrderedInvertedMask == fcNegInf);
Value *NeInf = IsUnordered ? Builder.CreateFCmpUNE(Src0, Inf)
: Builder.CreateFCmpONE(Src0, Inf);
NeInf->takeName(&II);
return replaceInstUsesWith(II, NeInf);
}

if (Mask == fcNan && !IsStrict) {
// Equivalent of isnan. Replace with standard fcmp if we don't care about FP
// exceptions.
Expand All @@ -879,11 +915,6 @@ Instruction *InstCombinerImpl::foldIntrinsicIsFPClass(IntrinsicInst &II) {
return replaceInstUsesWith(II, FCmp);
}

const bool IsUnordered = (Mask & fcNan) == fcNan;
const bool IsOrdered = (Mask & fcNan) == fcNone;
const FPClassTest OrderedMask = Mask & ~fcNan;
const FPClassTest OrderedInvertedMask = ~OrderedMask & ~fcNan;

if (!IsStrict && (IsOrdered || IsUnordered) &&
fpclassTestIsFCmp0(OrderedMask, *II.getFunction(), Src0->getType())) {
Constant *Zero = ConstantFP::getZero(Src0->getType());
Expand Down
32 changes: 16 additions & 16 deletions llvm/test/Transforms/InstCombine/create-class-from-logic-fcmp.ll
View file
Expand Up @@ -918,7 +918,7 @@ define i1 @isnormalinf_and_inf(half %x) #0 {
; -> pinf
define i1 @posisnormalinf_and_posinf(half %x) #0 {
; CHECK-LABEL: @posisnormalinf_and_posinf(
; CHECK-NEXT: [[AND:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 512)
; CHECK-NEXT: [[AND:%.*]] = fcmp oeq half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[AND]]
;
%fabs = call half @llvm.fabs.f16(half %x)
Expand All @@ -931,7 +931,7 @@ define i1 @posisnormalinf_and_posinf(half %x) #0 {
; -> pinf
define i1 @isnormalinf_and_posinf(half %x) #0 {
; CHECK-LABEL: @isnormalinf_and_posinf(
; CHECK-NEXT: [[AND:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 512)
; CHECK-NEXT: [[AND:%.*]] = fcmp oeq half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[AND]]
;
%fabs = call half @llvm.fabs.f16(half %x)
Expand Down Expand Up @@ -1073,7 +1073,7 @@ define i1 @olt_smallest_normal_or_uno(half %x) #0 {

define i1 @olt_smallest_normal_or_finite(half %x) #0 {
; CHECK-LABEL: @olt_smallest_normal_or_finite(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 508)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp one half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%fabs = call half @llvm.fabs.f16(half %x)
Expand Down Expand Up @@ -1120,7 +1120,7 @@ define i1 @uge_smallest_normal_and_uno(half %x) #0 {
; -> true
define i1 @olt_infinity_or_finite(half %x) #0 {
; CHECK-LABEL: @olt_infinity_or_finite(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 508)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp one half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%lt.infinity = fcmp olt half %x, 0xH7C00
Expand Down Expand Up @@ -1156,7 +1156,7 @@ define i1 @olt_infinity_or_ord(half %x) #0 {
; -> ~posinf
define i1 @olt_infinity_or_uno(half %x) #0 {
; CHECK-LABEL: @olt_infinity_or_uno(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 511)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp une half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%lt.infinity = fcmp olt half %x, 0xH7C00
Expand All @@ -1167,7 +1167,7 @@ define i1 @olt_infinity_or_uno(half %x) #0 {

define i1 @olt_infinity_or_subnormal(half %x) #0 {
; CHECK-LABEL: @olt_infinity_or_subnormal(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 508)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp one half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%lt.infinity = fcmp olt half %x, 0xH7C00
Expand Down Expand Up @@ -1205,7 +1205,7 @@ define i1 @olt_infinity_and_not_subnormal(half %x) #0 {
; -> ninf
define i1 @olt_infinity_and_ueq_inf(half %x) #0 {
; CHECK-LABEL: @olt_infinity_and_ueq_inf(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 4)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp oeq half [[X:%.*]], 0xHFC00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%lt.infinity = fcmp olt half %x, 0xH7C00
Expand Down Expand Up @@ -1241,7 +1241,7 @@ define i1 @olt_smallest_normal_or_ueq_inf(half %x) #0 {
; -> ~pinf
define i1 @olt_smallest_normal_or_une_inf(half %x) #0 {
; CHECK-LABEL: @olt_smallest_normal_or_une_inf(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 511)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp une half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%lt.normal = fcmp olt half %x, 0xH0400
Expand Down Expand Up @@ -1302,7 +1302,7 @@ define i1 @oge_fabs_eq_inf_and_ord(half %x) #0 {

define i1 @oge_eq_inf_and_ord(half %x) #0 {
; CHECK-LABEL: @oge_eq_inf_and_ord(
; CHECK-NEXT: [[AND:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 512)
; CHECK-NEXT: [[AND:%.*]] = fcmp oeq half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[AND]]
;
%oge.fabs.inf = fcmp oge half %x, 0xH7C00
Expand All @@ -1325,7 +1325,7 @@ define i1 @oge_fabs_eq_inf_or_uno(half %x) #0 {

define i1 @oge_eq_inf_or_uno(half %x) #0 {
; CHECK-LABEL: @oge_eq_inf_or_uno(
; CHECK-NEXT: [[OR:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 515)
; CHECK-NEXT: [[OR:%.*]] = fcmp ueq half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[OR]]
;
%oge.fabs.inf = fcmp oge half %x, 0xH7C00
Expand Down Expand Up @@ -1372,7 +1372,7 @@ define i1 @ult_fabs_eq_inf_or_uno(half %x) #0 {

define i1 @ult_eq_inf_or_uno(half %x) #0 {
; CHECK-LABEL: @ult_eq_inf_or_uno(
; CHECK-NEXT: [[OR:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 511)
; CHECK-NEXT: [[OR:%.*]] = fcmp une half [[X:%.*]], 0xH7C00
; CHECK-NEXT: ret i1 [[OR]]
;
%ult.fabs.inf = fcmp ult half %x, 0xH7C00
Expand Down Expand Up @@ -1411,7 +1411,7 @@ define i1 @oeq_neginfinity_or_olt_smallest_normal(half %x) #0 {
; -> ninf
define i1 @oeq_neginfinity_and_olt_smallest_normal(half %x) #0 {
; CHECK-LABEL: @oeq_neginfinity_and_olt_smallest_normal(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 4)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp oeq half [[X:%.*]], 0xHFC00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%oeq.neg.infinity = fcmp oeq half %x, 0xHFC00
Expand Down Expand Up @@ -1458,7 +1458,7 @@ define i1 @oeq_neginfinity_or_ord(half %x) #0 {
; -> ninf
define i1 @oeq_neginfinity_and_ord(half %x) #0 {
; CHECK-LABEL: @oeq_neginfinity_and_ord(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 4)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp oeq half [[X:%.*]], 0xHFC00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%oeq.neg.infinity = fcmp oeq half %x, 0xHFC00
Expand Down Expand Up @@ -1531,7 +1531,7 @@ define i1 @one_neginfinity_and_olt_smallest_normal(half %x) #0 {
; -> ~ninf
define i1 @one_neginfinity_or_uno(half %x) #0 {
; CHECK-LABEL: @one_neginfinity_or_uno(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 1019)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp une half [[X:%.*]], 0xHFC00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%one.neg.infinity = fcmp one half %x, 0xHFC00
Expand Down Expand Up @@ -1578,7 +1578,7 @@ define i1 @ueq_neginfinity_or_olt_smallest_normal(half %x) #0 {
; -> ninf
define i1 @ueq_neginfinity_and_olt_smallest_normal(half %x) #0 {
; CHECK-LABEL: @ueq_neginfinity_and_olt_smallest_normal(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 4)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp oeq half [[X:%.*]], 0xHFC00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%ueq.neg.infinity = fcmp ueq half %x, 0xHFC00
Expand All @@ -1590,7 +1590,7 @@ define i1 @ueq_neginfinity_and_olt_smallest_normal(half %x) #0 {
; -> nan|ninf
define i1 @ueq_neginfinity_or_uno(half %x) #0 {
; CHECK-LABEL: @ueq_neginfinity_or_uno(
; CHECK-NEXT: [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 7)
; CHECK-NEXT: [[CLASS:%.*]] = fcmp ueq half [[X:%.*]], 0xHFC00
; CHECK-NEXT: ret i1 [[CLASS]]
;
%ueq.neg.infinity = fcmp ueq half %x, 0xHFC00
Expand Down

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