ValueTracking: Identify implied fp classes by general fcmp #65983
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Previously we could recognize exact class tests performed by an fcmp with special values (0s, infs and smallest normal). Expand this to recognize the implied classes by a compare with a general constant. e.g. fcmp ogt x, 1 implies positive and non-0. The API should be better merged with fcmpToClassTest but that made the diff way bigger, will try to do that in a future patch.
arsenm
requested review from
jayfoad,
spavloff,
andykaylor,
kpneal and
jcranmer-intel
|
@llvm/pr-subscribers-llvm-analysis ChangesPreviously we could recognize exact class tests performed by an fcmp with special values (0s, infs and smallest normal). Expand this to recognize the implied classes by a compare with a general constant. e.g. fcmp ogt x, 1 implies positive and non-0. The API should be better merged with fcmpToClassTest but that made the diff way bigger, will try to do that in a future patch.Patch is 114.81 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/65983.diff 4 Files Affected:
diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index 695f2fecae885b7..6a2fac1961070e4 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -235,6 +235,27 @@ std::pair fcmpToClassTest(CmpInst::Predicate Pred,
const APFloat *ConstRHS,
bool LookThroughSrc = true);
+/// Compute the possible floating-point classes that \p LHS could be based on an
+/// fcmp returning true. Returns { TestedValue, ClassesIfTrue, ClassesIfFalse }
+///
+/// If the compare returns an exact class test, ClassesIfTrue == ~ClassesIfFalse
+///
+/// This is a less exact version of fcmpToClassTest (e.g. fcmpToClassTest will
+/// only succeed for a test of x > 0 implies positive, but not x > 1).
+///
+/// If \p LookThroughSrc is true, consider the input value when computing the
+/// mask. This may look through sign bit operations.
+///
+/// If \p LookThroughSrc is false, ignore the source value (i.e. the first pair
+/// element will always be LHS.
+///
+std::tuple
+fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ const APFloat *ConstRHS, bool LookThroughSrc = true);
+std::tuple
+fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ Value *RHS, bool LookThroughSrc = true);
+
struct KnownFPClass {
/// Floating-point classes the value could be one of.
FPClassTest KnownFPClasses = fcAllFlags;
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index c4153b824c37e0a..f7ae8af36199f80 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4217,6 +4217,140 @@ llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
return {Src, Mask};
}
+std::tuple
+llvm::fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ const APFloat *ConstRHS, bool LookThroughSrc) {
+ auto [Val, ClassMask] =
+ fcmpToClassTest(Pred, F, LHS, ConstRHS, LookThroughSrc);
+ if (Val)
+ return {Val, ClassMask, ~ClassMask};
+
+ FPClassTest RHSClass = ConstRHS->classify();
+ assert((RHSClass == fcPosNormal || RHSClass == fcNegNormal ||
+ RHSClass == fcPosSubnormal || RHSClass == fcNegSubnormal) &&
+ "should have been recognized as an exact class test");
+
+ const bool IsNegativeRHS = (RHSClass & fcNegative) == RHSClass;
+ const bool IsPositiveRHS = (RHSClass & fcPositive) == RHSClass;
+
+ assert(IsNegativeRHS == ConstRHS->isNegative());
+ assert(IsPositiveRHS == !ConstRHS->isNegative());
+
+ Value *Src = LHS;
+ const bool IsFabs = LookThroughSrc && match(LHS, m_FAbs(m_Value(Src)));
+
+ if (IsFabs)
+ RHSClass = llvm::fneg(RHSClass);
+
+ if (Pred == FCmpInst::FCMP_OEQ)
+ return {Src, RHSClass, fcAllFlags};
+
+ if (Pred == FCmpInst::FCMP_UEQ) {
+ FPClassTest Class = RHSClass | fcNan;
+ return {Src, Class, ~Class};
+ }
+
+ if (Pred == FCmpInst::FCMP_ONE)
+ return {Src, ~fcNan, RHSClass};
+
+ if (Pred == FCmpInst::FCMP_UNE)
+ return {Src, fcAllFlags, RHSClass | fcNan};
+
+ if (IsNegativeRHS) {
+ // TODO: Handle fneg(fabs)
+ if (IsFabs) {
+ // fabs(x) o> -k -> fcmp ord x, x
+ // fabs(x) u> -k -> true
+ // fabs(x) o< -k -> false
+ // fabs(x) u< -k -> fcmp uno x, x
+ switch (Pred) {
+ case FCmpInst::FCMP_OGT:
+ case FCmpInst::FCMP_OGE:
+ return {Src, ~fcNan, fcNan};
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_UGE:
+ return {Src, fcAllFlags, fcNone};
+ case FCmpInst::FCMP_OLT:
+ case FCmpInst::FCMP_OLE:
+ return {Src, fcNone, fcAllFlags};
+ case FCmpInst::FCMP_ULT:
+ case FCmpInst::FCMP_ULE:
+ return {Src, fcNan, ~fcNan};
+ default:
+ break;
+ }
+
+ return {nullptr, fcAllFlags, fcAllFlags};
+ }
+
+ FPClassTest ClassesLE = fcNegInf | fcNegNormal;
+ FPClassTest ClassesGE = fcPositive | fcNegZero | fcNegSubnormal;
+
+ if (ConstRHS->isDenormal())
+ ClassesLE |= fcNegSubnormal;
+ else
+ ClassesGE |= fcNegNormal;
+
+ switch (Pred) {
+ case FCmpInst::FCMP_OGT:
+ case FCmpInst::FCMP_OGE:
+ return {Src, ClassesGE, ~ClassesGE | RHSClass};
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_UGE:
+ return {Src, ClassesGE | fcNan, ~(ClassesGE | fcNan) | RHSClass};
+ case FCmpInst::FCMP_OLT:
+ case FCmpInst::FCMP_OLE:
+ return {Src, ClassesLE, ~ClassesLE | RHSClass};
+ case FCmpInst::FCMP_ULT:
+ case FCmpInst::FCMP_ULE:
+ return {Src, ClassesLE | fcNan, ~(ClassesLE | fcNan) | RHSClass};
+ default:
+ break;
+ }
+ } else if (IsPositiveRHS) {
+ FPClassTest ClassesGE = fcPosNormal | fcPosInf;
+ FPClassTest ClassesLE = fcNegative | fcPosZero | fcPosNormal;
+ if (ConstRHS->isDenormal())
+ ClassesGE |= fcPosNormal;
+ else
+ ClassesLE |= fcPosSubnormal;
+
+ FPClassTest FalseClasses = RHSClass;
+ if (IsFabs) {
+ ClassesGE = llvm::fabs(ClassesGE);
+ ClassesLE = llvm::fabs(ClassesLE);
+ }
+
+ switch (Pred) {
+ case FCmpInst::FCMP_OGT:
+ case FCmpInst::FCMP_OGE:
+ return {Src, ClassesGE, ~ClassesGE | FalseClasses};
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_UGE:
+ return {Src, ClassesGE | fcNan, ~(ClassesGE | fcNan) | FalseClasses};
+ case FCmpInst::FCMP_OLT:
+ case FCmpInst::FCMP_OLE:
+ return {Src, ClassesLE, ~ClassesLE | FalseClasses};
+ case FCmpInst::FCMP_ULT:
+ case FCmpInst::FCMP_ULE:
+ return {Src, ClassesLE | fcNan, ~(ClassesLE | fcNan) | FalseClasses};
+ default:
+ break;
+ }
+ }
+
+ return {nullptr, fcAllFlags, fcAllFlags};
+}
+
+std::tuple
+llvm::fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ Value *RHS, bool LookThroughSrc) {
+ const APFloat *ConstRHS;
+ if (!match(RHS, m_APFloatAllowUndef(ConstRHS)))
+ return {nullptr, fcAllFlags, fcNone};
+ return fcmpImpliesClass(Pred, F, LHS, ConstRHS, LookThroughSrc);
+}
+
static FPClassTest computeKnownFPClassFromAssumes(const Value *V,
const SimplifyQuery &Q) {
FPClassTest KnownFromAssume = fcAllFlags;
@@ -4241,18 +4375,21 @@ static FPClassTest computeKnownFPClassFromAssumes(const Value *V,
Value *LHS, *RHS;
uint64_t ClassVal = 0;
if (match(I->getArgOperand(0), m_FCmp(Pred, m_Value(LHS), m_Value(RHS)))) {
- auto [TestedValue, TestedMask] =
- fcmpToClassTest(Pred, *F, LHS, RHS, true);
- // First see if we can fold in fabs/fneg into the test.
- if (TestedValue == V)
- KnownFromAssume &= TestedMask;
- else {
- // Try again without the lookthrough if we found a different source
- // value.
- auto [TestedValue, TestedMask] =
- fcmpToClassTest(Pred, *F, LHS, RHS, false);
- if (TestedValue == V)
- KnownFromAssume &= TestedMask;
+ const APFloat *CRHS;
+ if (match(RHS, m_APFloat(CRHS))) {
+ // First see if we can fold in fabs/fneg into the test.
+ auto [CmpVal, MaskIfTrue, MaskIfFalse] =
+ fcmpImpliesClass(Pred, *F, LHS, CRHS, true);
+ if (CmpVal == V)
+ KnownFromAssume &= MaskIfTrue;
+ else {
+ // Try again without the lookthrough if we found a different source
+ // value.
+ auto [CmpVal, MaskIfTrue, MaskIfFalse] =
+ fcmpImpliesClass(Pred, *F, LHS, CRHS, false);
+ if (CmpVal == V)
+ KnownFromAssume &= MaskIfTrue;
+ }
}
} else if (match(I->getArgOperand(0),
m_Intrinsic(
@@ -4400,7 +4537,8 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
FPClassTest FilterRHS = fcAllFlags;
Value *TestedValue = nullptr;
- FPClassTest TestedMask = fcNone;
+ FPClassTest MaskIfTrue = fcAllFlags;
+ FPClassTest MaskIfFalse = fcAllFlags;
uint64_t ClassVal = 0;
const Function *F = cast(Op)->getFunction();
CmpInst::Predicate Pred;
@@ -4412,20 +4550,22 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
// TODO: In some degenerate cases we can infer something if we try again
// without looking through sign operations.
bool LookThroughFAbsFNeg = CmpLHS != LHS && CmpLHS != RHS;
- std::tie(TestedValue, TestedMask) =
- fcmpToClassTest(Pred, *F, CmpLHS, CmpRHS, LookThroughFAbsFNeg);
+ std::tie(TestedValue, MaskIfTrue, MaskIfFalse) =
+ fcmpImpliesClass(Pred, *F, CmpLHS, CmpRHS, LookThroughFAbsFNeg);
} else if (match(Cond,
m_Intrinsic(
m_Value(TestedValue), m_ConstantInt(ClassVal)))) {
- TestedMask = static_cast(ClassVal);
+ FPClassTest TestedMask = static_cast(ClassVal);
+ MaskIfTrue = TestedMask;
+ MaskIfFalse = ~TestedMask;
}
if (TestedValue == LHS) {
// match !isnan(x) ? x : y
- FilterLHS = TestedMask;
- } else if (TestedValue == RHS) {
+ FilterLHS = MaskIfTrue;
+ } else if (TestedValue == RHS) { // && IsExactClass
// match !isnan(x) ? y : x
- FilterRHS = ~TestedMask;
+ FilterRHS = MaskIfFalse;
}
KnownFPClass Known2;
diff --git a/llvm/test/Transforms/Attributor/nofpclass-implied-by-fcmp.ll b/llvm/test/Transforms/Attributor/nofpclass-implied-by-fcmp.ll
index 396b8c84fc898c9..b3dce48868d7dbf 100644
--- a/llvm/test/Transforms/Attributor/nofpclass-implied-by-fcmp.ll
+++ b/llvm/test/Transforms/Attributor/nofpclass-implied-by-fcmp.ll
@@ -11,7 +11,7 @@ declare void @llvm.assume(i1 noundef)
; can't be +inf
define float @clamp_is_ogt_1_to_1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ogt_1_to_1(
+; CHECK-LABEL: define nofpclass(pinf) float @clamp_is_ogt_1_to_1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2:[0-9]+]] {
; CHECK-NEXT: [[IS_OGT_1:%.*]] = fcmp ogt float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OGT_1]], float 1.000000e+00, float [[ARG]]
@@ -23,7 +23,7 @@ define float @clamp_is_ogt_1_to_1(float %arg) {
}
define float @clamp_is_ogt_1_to_1_commute(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ogt_1_to_1_commute(
+; CHECK-LABEL: define nofpclass(pinf) float @clamp_is_ogt_1_to_1_commute(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_ULE_1:%.*]] = fcmp ule float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_ULE_1]], float [[ARG]], float 1.000000e+00
@@ -36,7 +36,7 @@ define float @clamp_is_ogt_1_to_1_commute(float %arg) {
; can't be +inf or nan
define float @clamp_is_ugt_1_to_1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ugt_1_to_1(
+; CHECK-LABEL: define nofpclass(nan pinf) float @clamp_is_ugt_1_to_1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_UGT_1:%.*]] = fcmp ugt float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_UGT_1]], float 1.000000e+00, float [[ARG]]
@@ -49,7 +49,7 @@ define float @clamp_is_ugt_1_to_1(float %arg) {
; can't be +inf or nan
define float @clamp_is_ugt_1_to_1_commute(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ugt_1_to_1_commute(
+; CHECK-LABEL: define nofpclass(nan pinf) float @clamp_is_ugt_1_to_1_commute(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_OLE_1:%.*]] = fcmp ole float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OLE_1]], float [[ARG]], float 1.000000e+00
@@ -62,7 +62,7 @@ define float @clamp_is_ugt_1_to_1_commute(float %arg) {
; can't be +inf
define float @clamp_is_oge_1_to_1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_oge_1_to_1(
+; CHECK-LABEL: define nofpclass(pinf) float @clamp_is_oge_1_to_1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_OGE_1:%.*]] = fcmp oge float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OGE_1]], float 1.000000e+00, float [[ARG]]
@@ -74,7 +74,7 @@ define float @clamp_is_oge_1_to_1(float %arg) {
}
define float @clamp_is_oge_1_to_1_commute(float %arg) {
-; CHECK-LABEL: define float @clamp_is_oge_1_to_1_commute(
+; CHECK-LABEL: define nofpclass(pinf) float @clamp_is_oge_1_to_1_commute(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_ULT_1:%.*]] = fcmp ult float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_ULT_1]], float [[ARG]], float 1.000000e+00
@@ -87,7 +87,7 @@ define float @clamp_is_oge_1_to_1_commute(float %arg) {
; can't be +inf or nan
define float @clamp_is_uge_1_to_1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_uge_1_to_1(
+; CHECK-LABEL: define nofpclass(nan pinf) float @clamp_is_uge_1_to_1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_UGT_1:%.*]] = fcmp uge float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_UGT_1]], float 1.000000e+00, float [[ARG]]
@@ -100,7 +100,7 @@ define float @clamp_is_uge_1_to_1(float %arg) {
; can't be negative, zero, or denormal
define float @clamp_is_olt_1_to_1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_olt_1_to_1(
+; CHECK-LABEL: define nofpclass(ninf zero sub nnorm) float @clamp_is_olt_1_to_1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_OLT_1:%.*]] = fcmp olt float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OLT_1]], float 1.000000e+00, float [[ARG]]
@@ -113,7 +113,7 @@ define float @clamp_is_olt_1_to_1(float %arg) {
; can't be negative, zero, or denormal
define float @clamp_is_olt_1_to_1_commute(float %arg) {
-; CHECK-LABEL: define float @clamp_is_olt_1_to_1_commute(
+; CHECK-LABEL: define nofpclass(ninf zero sub nnorm) float @clamp_is_olt_1_to_1_commute(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_UGE_1:%.*]] = fcmp uge float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_UGE_1]], float [[ARG]], float 1.000000e+00
@@ -126,7 +126,7 @@ define float @clamp_is_olt_1_to_1_commute(float %arg) {
; can't be negative or zero, nan or denormal
define float @clamp_is_ult_1_to_1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ult_1_to_1(
+; CHECK-LABEL: define nofpclass(nan ninf zero sub nnorm) float @clamp_is_ult_1_to_1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_ULT_1:%.*]] = fcmp ult float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_ULT_1]], float 1.000000e+00, float [[ARG]]
@@ -139,7 +139,7 @@ define float @clamp_is_ult_1_to_1(float %arg) {
; can't be negative or zero, nan or denormal
define float @clamp_is_ult_1_to_1_commute(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ult_1_to_1_commute(
+; CHECK-LABEL: define nofpclass(nan ninf zero sub nnorm) float @clamp_is_ult_1_to_1_commute(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_OGE_1:%.*]] = fcmp oge float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OGE_1]], float [[ARG]], float 1.000000e+00
@@ -152,7 +152,7 @@ define float @clamp_is_ult_1_to_1_commute(float %arg) {
; can't be negative, zero or denormal
define float @clamp_is_ole_1_to_1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ole_1_to_1(
+; CHECK-LABEL: define nofpclass(ninf zero sub nnorm) float @clamp_is_ole_1_to_1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_OLE_1:%.*]] = fcmp ole float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OLE_1]], float 1.000000e+00, float [[ARG]]
@@ -165,7 +165,7 @@ define float @clamp_is_ole_1_to_1(float %arg) {
; can't be negative or zero, nan or denormal
define float @clamp_is_ule_1_to_1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ule_1_to_1(
+; CHECK-LABEL: define nofpclass(nan ninf zero sub nnorm) float @clamp_is_ule_1_to_1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_ULE_1:%.*]] = fcmp ule float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_ULE_1]], float 1.000000e+00, float [[ARG]]
@@ -178,7 +178,7 @@ define float @clamp_is_ule_1_to_1(float %arg) {
; can't be negative or denormal
define float @clamp_is_olt_1_to_0(float %arg) {
-; CHECK-LABEL: define float @clamp_is_olt_1_to_0(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @clamp_is_olt_1_to_0(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_OLT_1:%.*]] = fcmp olt float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OLT_1]], float 0.000000e+00, float [[ARG]]
@@ -191,7 +191,7 @@ define float @clamp_is_olt_1_to_0(float %arg) {
; can't be negative, nan or denormal
define float @clamp_is_ult_1_to_0(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ult_1_to_0(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @clamp_is_ult_1_to_0(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_ULT_1:%.*]] = fcmp olt float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_ULT_1]], float 0.000000e+00, float [[ARG]]
@@ -204,7 +204,7 @@ define float @clamp_is_ult_1_to_0(float %arg) {
; can't be negative or denormal
define float @clamp_is_ole_1_to_0(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ole_1_to_0(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @clamp_is_ole_1_to_0(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_OLE_1:%.*]] = fcmp ole float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OLE_1]], float 0.000000e+00, float [[ARG]]
@@ -217,7 +217,7 @@ define float @clamp_is_ole_1_to_0(float %arg) {
; can't be negative or denormal
define float @clamp_is_ole_1_to_0_commute(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ole_1_to_0_commute(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @clamp_is_ole_1_to_0_commute(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_UGT_1:%.*]] = fcmp ugt float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_UGT_1]], float [[ARG]], float 0.000000e+00
@@ -230,7 +230,7 @@ define float @clamp_is_ole_1_to_0_commute(float %arg) {
; can't be negative or denormal
define float @clamp_is_ule_1_to_0(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ule_1_to_0(
+; CHECK-LABEL: define nofpclass(ninf nzero sub nnorm) float @clamp_is_ule_1_to_0(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_ULE_1:%.*]] = fcmp ole float [[ARG]], 1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_ULE_1]], float 0.000000e+00, float [[ARG]]
@@ -243,7 +243,7 @@ define float @clamp_is_ule_1_to_0(float %arg) {
; can't be positive, zero or denormal
define float @clamp_is_ogt_neg1_to_neg1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ogt_neg1_to_neg1(
+; CHECK-LABEL: define nofpclass(pinf zero sub pnorm) float @clamp_is_ogt_neg1_to_neg1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_OGT_NEG1:%.*]] = fcmp ogt float [[ARG]], -1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_OGT_NEG1]], float -1.000000e+00, float [[ARG]]
@@ -256,7 +256,7 @@ define float @clamp_is_ogt_neg1_to_neg1(float %arg) {
; can't be positive, zero, nan or denormal
define float @clamp_is_ugt_neg1_to_neg1(float %arg) {
-; CHECK-LABEL: define float @clamp_is_ugt_neg1_to_neg1(
+; CHECK-LABEL: define nofpclass(nan pinf zero sub pnorm) float @clamp_is_ugt_neg1_to_neg1(
; CHECK-SAME: float [[ARG:%.*]]) #[[ATTR2]] {
; CHECK-NEXT: [[IS_UGT_NEG1:%.*]] = fcmp ugt float [[ARG]], -1.000000e+00
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[IS_UGT_NEG1]], float -1.000000e+00, float [[ARG]]
@@ -269,7 +269,7 @@ define float @clamp_is_ugt_neg1_to_neg1(float ...
|
|
@llvm/pr-subscribers-backend-amdgpu @llvm/pr-subscribers-llvm-transforms ChangesPreviously we could recognize exact class tests performed by an fcmp with special values (0s, infs and smallest normal). Expand this to recognize the implied classes by a compare with a general constant. e.g. fcmp ogt x, 1 implies positive and non-0.The API should be better merged with fcmpToClassTest but that made the diff way bigger, will try to do that in a future patch.Patch is 126.50 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/65983.diff 6 Files Affected:
diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index 695f2fecae885b7..bc571a702f717d4 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -235,6 +235,40 @@ std::pair<Value *, FPClassTest> fcmpToClassTest(CmpInst::Predicate Pred,
const APFloat *ConstRHS,
bool LookThroughSrc = true);
+/// Compute the possible floating-point classes that \p LHS could be based on
+/// fcmp \Pred \p LHS, \p RHS.
+///
+/// Returns { TestedValue, ClassesIfTrue, ClassesIfFalse }
+///
+/// If the compare returns an exact class test, ClassesIfTrue == ~ClassesIfFalse
+///
+/// This is a less exact version of fcmpToClassTest (e.g. fcmpToClassTest will
+/// only succeed for a test of x > 0 implies positive, but not x > 1).
+///
+/// If \p LookThroughSrc is true, consider the input value when computing the
+/// mask. This may look through sign bit operations.
+///
+/// If \p LookThroughSrc is false, ignore the source value (i.e. the first pair
+/// element will always be LHS.
+///
+std::tuple<Value *, FPClassTest, FPClassTest>
+fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ Value *RHS, bool LookThroughSrc = true);
+std::tuple<Value *, FPClassTest, FPClassTest>
+fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ FPClassTest RHS, bool LookThroughSrc = true);
+std::tuple<Value *, FPClassTest, FPClassTest>
+fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ const APFloat &RHS, bool LookThroughSrc = true);
+
+#if 0
+inline std::tuple<Value *, FPClassTest, FPClassTest>
+fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ const APFloat &RHS, bool LookThroughSrc = true) {
+ return fcmpImpliesClass(Pred, F, LHS, RHS.classify(), LookThroughSrc);
+}
+#endif
+
struct KnownFPClass {
/// Floating-point classes the value could be one of.
FPClassTest KnownFPClasses = fcAllFlags;
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index c4153b824c37e0a..ccacc75d50c67af 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4016,67 +4016,106 @@ std::pair<Value *, FPClassTest> llvm::fcmpToClassTest(FCmpInst::Predicate Pred,
std::pair<Value *, FPClassTest>
llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
const APFloat *ConstRHS, bool LookThroughSrc) {
+
+ auto [Src, ClassIfTrue, ClassIfFalse] = fcmpImpliesClass(Pred,
+ F,
+ LHS,
+ *ConstRHS, LookThroughSrc);
+ if (Src && ClassIfTrue == ~ClassIfFalse)
+ return {Src, ClassIfTrue};
+ return {nullptr, fcAllFlags};
+}
+
+/// Return the return value for fcmpImpliesClass for a compare that produces an
+/// exact class test.
+static std::tuple<Value *, FPClassTest, FPClassTest>
+exactClass(Value *V, FPClassTest M) {
+ return {V, M, ~M};
+}
+
+std::tuple<Value *, FPClassTest, FPClassTest>
+llvm::fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ FPClassTest RHSClass, bool LookThroughSrc) {
+ assert(RHSClass != fcNone);
+
+ FPClassTest OrigClass = RHSClass;
+
+ Value *Src = LHS;
+ const bool IsNegativeRHS = (RHSClass & fcNegative) == RHSClass;
+ const bool IsPositiveRHS = (RHSClass & fcPositive) == RHSClass;
+ const bool IsNaN = (RHSClass & ~fcNan) == fcNone;
+
+ if (IsNaN) {
+ // fcmp o__ x, nan -> false
+ // fcmp u__ x, nan -> true
+ return exactClass(Src, CmpInst::isOrdered(Pred) ? fcNone : fcAllFlags);
+ }
+
// fcmp ord x, zero|normal|subnormal|inf -> ~fcNan
- if (Pred == FCmpInst::FCMP_ORD && !ConstRHS->isNaN())
- return {LHS, ~fcNan};
+ if (Pred == FCmpInst::FCMP_ORD)
+ return {Src, ~fcNan, fcNan};
// fcmp uno x, zero|normal|subnormal|inf -> fcNan
- if (Pred == FCmpInst::FCMP_UNO && !ConstRHS->isNaN())
- return {LHS, fcNan};
+ if (Pred == FCmpInst::FCMP_UNO)
+ return {Src, fcNan, ~fcNan};
- if (ConstRHS->isZero()) {
+ const bool IsFabs = LookThroughSrc && match(LHS, m_FAbs(m_Value(Src)));
+ if (IsFabs)
+ RHSClass = llvm::fneg(RHSClass);
+
+ const bool IsZero = (RHSClass & fcZero) == RHSClass;
+ if (IsZero) {
// Compares with fcNone are only exactly equal to fcZero if input denormals
// are not flushed.
// TODO: Handle DAZ by expanding masks to cover subnormal cases.
if (Pred != FCmpInst::FCMP_ORD && Pred != FCmpInst::FCMP_UNO &&
!inputDenormalIsIEEE(F, LHS->getType()))
- return {nullptr, fcNone};
+ return {nullptr, fcAllFlags, fcAllFlags};
switch (Pred) {
case FCmpInst::FCMP_OEQ: // Match x == 0.0
- return {LHS, fcZero};
+ return exactClass(Src, fcZero);
case FCmpInst::FCMP_UEQ: // Match isnan(x) || (x == 0.0)
- return {LHS, fcZero | fcNan};
+ return exactClass(Src, fcZero | fcNan);
case FCmpInst::FCMP_UNE: // Match (x != 0.0)
- return {LHS, ~fcZero};
+ return exactClass(Src, ~fcZero);
case FCmpInst::FCMP_ONE: // Match !isnan(x) && x != 0.0
- return {LHS, ~fcNan & ~fcZero};
+ return exactClass(Src, ~fcNan & ~fcZero);
case FCmpInst::FCMP_ORD:
// Canonical form of ord/uno is with a zero. We could also handle
// non-canonical other non-NaN constants or LHS == RHS.
- return {LHS, ~fcNan};
+ return exactClass(Src, ~fcNan);
case FCmpInst::FCMP_UNO:
- return {LHS, fcNan};
+ return exactClass(Src, fcNan);
case FCmpInst::FCMP_OGT: // x > 0
- return {LHS, fcPosSubnormal | fcPosNormal | fcPosInf};
+ return exactClass(Src, fcPosSubnormal | fcPosNormal | fcPosInf);
case FCmpInst::FCMP_UGT: // isnan(x) || x > 0
- return {LHS, fcPosSubnormal | fcPosNormal | fcPosInf | fcNan};
+ return exactClass(Src, fcPosSubnormal | fcPosNormal | fcPosInf | fcNan);
case FCmpInst::FCMP_OGE: // x >= 0
- return {LHS, fcPositive | fcNegZero};
+ return exactClass(Src, fcPositive | fcNegZero);
case FCmpInst::FCMP_UGE: // isnan(x) || x >= 0
- return {LHS, fcPositive | fcNegZero | fcNan};
+ return exactClass(Src, fcPositive | fcNegZero | fcNan);
case FCmpInst::FCMP_OLT: // x < 0
- return {LHS, fcNegSubnormal | fcNegNormal | fcNegInf};
+ return exactClass(Src, fcNegSubnormal | fcNegNormal | fcNegInf);
case FCmpInst::FCMP_ULT: // isnan(x) || x < 0
- return {LHS, fcNegSubnormal | fcNegNormal | fcNegInf | fcNan};
+ return exactClass(Src, fcNegSubnormal | fcNegNormal | fcNegInf | fcNan);
case FCmpInst::FCMP_OLE: // x <= 0
- return {LHS, fcNegative | fcPosZero};
+ return exactClass(Src, fcNegative | fcPosZero);
case FCmpInst::FCMP_ULE: // isnan(x) || x <= 0
- return {LHS, fcNegative | fcPosZero | fcNan};
+ return exactClass(Src, fcNegative | fcPosZero | fcNan);
default:
break;
}
- return {nullptr, fcNone};
+ return {nullptr, fcAllFlags, fcAllFlags};
}
- Value *Src = LHS;
- const bool IsFabs = LookThroughSrc && match(LHS, m_FAbs(m_Value(Src)));
+ const bool IsDenormalRHS = (RHSClass & fcSubnormal) == RHSClass;
- // Compute the test mask that would return true for the ordered comparisons.
- FPClassTest Mask;
+ const bool IsInf = (RHSClass & fcInf) == RHSClass;
+ if (IsInf) {
+ FPClassTest Mask = fcAllFlags;
- if (ConstRHS->isInfinity()) {
switch (Pred) {
case FCmpInst::FCMP_OEQ:
case FCmpInst::FCMP_UNE: {
@@ -4091,8 +4130,7 @@ llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
// fcmp une fabs(x), +inf -> is_fpclass x, ~fcInf
// fcmp une x, -inf -> is_fpclass x, ~fcNegInf
// fcmp une fabs(x), -inf -> is_fpclass x, fcAllFlags -> true
-
- if (ConstRHS->isNegative()) {
+ if (IsNegativeRHS) {
Mask = fcNegInf;
if (IsFabs)
Mask = fcNone;
@@ -4101,7 +4139,6 @@ llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
if (IsFabs)
Mask |= fcNegInf;
}
-
break;
}
case FCmpInst::FCMP_ONE:
@@ -4116,7 +4153,7 @@ llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
// fcmp ueq (fabs x), +inf -> is_fpclass x, fcInf|fcNan
// fcmp ueq x, -inf -> is_fpclass x, fcNegInf|fcNan
// fcmp ueq fabs(x), -inf -> is_fpclass x, fcNan
- if (ConstRHS->isNegative()) {
+ if (IsNegativeRHS) {
Mask = ~fcNegInf & ~fcNan;
if (IsFabs)
Mask = ~fcNan;
@@ -4130,7 +4167,7 @@ llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
}
case FCmpInst::FCMP_OLT:
case FCmpInst::FCMP_UGE: {
- if (ConstRHS->isNegative()) {
+ if (IsNegativeRHS) {
// No value is ordered and less than negative infinity.
// All values are unordered with or at least negative infinity.
// fcmp olt x, -inf -> false
@@ -4150,8 +4187,8 @@ llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
}
case FCmpInst::FCMP_OGE:
case FCmpInst::FCMP_ULT: {
- if (ConstRHS->isNegative()) // TODO
- return {nullptr, fcNone};
+ if (IsNegativeRHS) // TODO
+ return {nullptr, fcAllFlags, fcAllFlags};
// fcmp oge fabs(x), +inf -> fcInf
// fcmp oge x, +inf -> fcPosInf
@@ -4164,17 +4201,138 @@ llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
}
case FCmpInst::FCMP_OGT:
case FCmpInst::FCMP_ULE: {
- if (ConstRHS->isNegative())
- return {nullptr, fcNone};
+ if (IsNegativeRHS)
+ return {nullptr, fcAllFlags, fcAllFlags};
// No value is ordered and greater than infinity.
Mask = fcNone;
break;
}
default:
- return {nullptr, fcNone};
+ return {nullptr, fcAllFlags, fcAllFlags};
+ }
+
+ // Invert the comparison for the unordered cases.
+ if (FCmpInst::isUnordered(Pred))
+ Mask = ~Mask;
+
+ return exactClass(Src, Mask);
+ }
+
+ if (Pred == FCmpInst::FCMP_OEQ) {
+ return {Src, RHSClass, fcAllFlags};
+
+ if (Pred == FCmpInst::FCMP_UEQ) {
+ FPClassTest Class = RHSClass | fcNan;
+ return {Src, Class, ~fcNan};
+ }
+
+ if (Pred == FCmpInst::FCMP_ONE)
+ return {Src, ~fcNan, RHSClass};
+
+ if (Pred == FCmpInst::FCMP_UNE)
+ return {Src, fcAllFlags, RHSClass};
+
+ assert((RHSClass == fcPosNormal || RHSClass == fcNegNormal || RHSClass == fcNormal ||
+ RHSClass == fcPosSubnormal || RHSClass == fcNegSubnormal || RHSClass == fcSubnormal) &&
+ "should have been recognized as an exact class test");
+
+ if (IsNegativeRHS) {
+ // TODO: Handle fneg(fabs)
+ if (IsFabs) {
+ // fabs(x) o> -k -> fcmp ord x, x
+ // fabs(x) u> -k -> true
+ // fabs(x) o< -k -> false
+ // fabs(x) u< -k -> fcmp uno x, x
+ switch (Pred) {
+ case FCmpInst::FCMP_OGT:
+ case FCmpInst::FCMP_OGE:
+ return {Src, ~fcNan, fcNan};
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_UGE:
+ return {Src, fcAllFlags, fcNone};
+ case FCmpInst::FCMP_OLT:
+ case FCmpInst::FCMP_OLE:
+ return {Src, fcNone, fcAllFlags};
+ case FCmpInst::FCMP_ULT:
+ case FCmpInst::FCMP_ULE:
+ return {Src, fcNan, ~fcNan};
+ default:
+ break;
+ }
+
+ return {nullptr, fcAllFlags, fcAllFlags};
+ }
+
+ FPClassTest ClassesLE = fcNegInf | fcNegNormal;
+ FPClassTest ClassesGE = fcPositive | fcNegZero | fcNegSubnormal;
+
+ if (IsDenormalRHS)
+ ClassesLE |= fcNegSubnormal;
+ else
+ ClassesGE |= fcNegNormal;
+
+ switch (Pred) {
+ case FCmpInst::FCMP_OGT:
+ case FCmpInst::FCMP_OGE:
+ return {Src, ClassesGE, ~ClassesGE | RHSClass};
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_UGE:
+ return {Src, ClassesGE | fcNan, ~(ClassesGE | fcNan) | RHSClass};
+ case FCmpInst::FCMP_OLT:
+ case FCmpInst::FCMP_OLE:
+ return {Src, ClassesLE, ~ClassesLE | RHSClass};
+ case FCmpInst::FCMP_ULT:
+ case FCmpInst::FCMP_ULE:
+ return {Src, ClassesLE | fcNan, ~(ClassesLE | fcNan) | RHSClass};
+ default:
+ break;
+ }
+ } else if (IsPositiveRHS) {
+ FPClassTest ClassesGE = fcPosNormal | fcPosInf;
+ FPClassTest ClassesLE = fcNegative | fcPosZero | fcPosNormal;
+ if (IsDenormalRHS)
+ ClassesGE |= fcPosNormal;
+ else
+ ClassesLE |= fcPosSubnormal;
+
+ FPClassTest FalseClasses = RHSClass;
+ if (IsFabs) {
+ ClassesGE = llvm::inverse_fabs(ClassesGE);
+ ClassesLE = llvm::inverse_fabs(ClassesLE);
+ }
+
+ switch (Pred) {
+ case FCmpInst::FCMP_OGT:
+ case FCmpInst::FCMP_OGE:
+ return {Src, ClassesGE, ~ClassesGE | FalseClasses};
+ case FCmpInst::FCMP_UGT:
+ case FCmpInst::FCMP_UGE:
+ return {Src, ClassesGE | fcNan, ~(ClassesGE | fcNan) | FalseClasses};
+ case FCmpInst::FCMP_OLT:
+ case FCmpInst::FCMP_OLE:
+ return {Src, ClassesLE, ~ClassesLE | FalseClasses};
+ case FCmpInst::FCMP_ULT:
+ case FCmpInst::FCMP_ULE:
+ return {Src, ClassesLE | fcNan, ~(ClassesLE | fcNan) | FalseClasses};
+ default:
+ break;
}
- } else if (ConstRHS->isSmallestNormalized() && !ConstRHS->isNegative()) {
+ }
+
+ return {nullptr, fcAllFlags, fcAllFlags};
+}
+
+std::tuple<Value *, FPClassTest, FPClassTest>
+llvm::fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ const APFloat &ConstRHS, bool LookThroughSrc) {
+ // We can refine checks against smallest normal / largest denormal to an
+ // exact class test.
+ if (!ConstRHS.isNegative() && ConstRHS.isSmallestNormalized()) {
+ Value *Src = LHS;
+ const bool IsFabs = LookThroughSrc && match(LHS, m_FAbs(m_Value(Src)));
+
+ FPClassTest Mask;
// Match pattern that's used in __builtin_isnormal.
switch (Pred) {
case FCmpInst::FCMP_OLT:
@@ -4201,20 +4359,28 @@ llvm::fcmpToClassTest(FCmpInst::Predicate Pred, const Function &F, Value *LHS,
break;
}
default:
- return {nullptr, fcNone};
+ // xxx - am i tested
+ return {nullptr, fcAllFlags, fcAllFlags};
+ return fcmpImpliesClass(Pred, F, LHS, ConstRHS.classify(), LookThroughSrc);
}
- } else if (ConstRHS->isNaN()) {
- // fcmp o__ x, nan -> false
- // fcmp u__ x, nan -> true
- Mask = fcNone;
- } else
- return {nullptr, fcNone};
- // Invert the comparison for the unordered cases.
- if (FCmpInst::isUnordered(Pred))
- Mask = ~Mask;
+ // Invert the comparison for the unordered cases.
+ if (FCmpInst::isUnordered(Pred))
+ Mask = ~Mask;
- return {Src, Mask};
+ return exactClass(Src, Mask);
+ }
+
+ return fcmpImpliesClass(Pred, F, LHS, ConstRHS.classify(), LookThroughSrc);
+}
+
+std::tuple<Value *, FPClassTest, FPClassTest>
+llvm::fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
+ Value *RHS, bool LookThroughSrc) {
+ const APFloat *ConstRHS;
+ if (!match(RHS, m_APFloatAllowUndef(ConstRHS)))
+ return {nullptr, fcAllFlags, fcNone};
+ return fcmpImpliesClass(Pred, F, LHS, *ConstRHS, LookThroughSrc);
}
static FPClassTest computeKnownFPClassFromAssumes(const Value *V,
@@ -4241,18 +4407,22 @@ static FPClassTest computeKnownFPClassFromAssumes(const Value *V,
Value *LHS, *RHS;
uint64_t ClassVal = 0;
if (match(I->getArgOperand(0), m_FCmp(Pred, m_Value(LHS), m_Value(RHS)))) {
- auto [TestedValue, TestedMask] =
- fcmpToClassTest(Pred, *F, LHS, RHS, true);
- // First see if we can fold in fabs/fneg into the test.
- if (TestedValue == V)
- KnownFromAssume &= TestedMask;
- else {
- // Try again without the lookthrough if we found a different source
- // value.
- auto [TestedValue, TestedMask] =
- fcmpToClassTest(Pred, *F, LHS, RHS, false);
- if (TestedValue == V)
- KnownFromAssume &= TestedMask;
+ const APFloat *CRHS;
+ if (match(RHS, m_APFloat(CRHS))) {
+ // First see if we can fold in fabs/fneg into the test.
+ auto [CmpVal, MaskIfTrue, MaskIfFalse] =
+ fcmpImpliesClass(Pred, *F, LHS, *CRHS, true);
+ if (CmpVal == V)
+ KnownFromAssume &= (MaskIfTrue & ~MaskIfFalse);
+
+ else {
+ // Try again without the lookthrough if we found a different source
+ // value.
+ auto [CmpVal, MaskIfTrue, MaskIfFalse] =
+ fcmpImpliesClass(Pred, *F, LHS, *CRHS, false);
+ if (CmpVal == V)
+ KnownFromAssume &= (MaskIfTrue & ~MaskIfFalse);
+ }
}
} else if (match(I->getArgOperand(0),
m_Intrinsic<Intrinsic::is_fpclass>(
@@ -4400,7 +4570,8 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
FPClassTest FilterRHS = fcAllFlags;
Value *TestedValue = nullptr;
- FPClassTest TestedMask = fcNone;
+ FPClassTest MaskIfTrue = fcAllFlags;
+ FPClassTest MaskIfFalse = fcAllFlags;
uint64_t ClassVal = 0;
const Function *F = cast<Instruction>(Op)->getFunction();
CmpInst::Predicate Pred;
@@ -4412,20 +4583,22 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
// TODO: In some degenerate cases we can infer something if we try again
// without looking through sign operations.
bool LookThroughFAbsFNeg = CmpLHS != LHS && CmpLHS != RHS;
- std::tie(TestedValue, TestedMask) =
- fcmpToClassTest(Pred, *F, CmpLHS, CmpRHS, LookThroughFAbsFNeg);
+ std::tie(TestedValue, MaskIfTrue, MaskIfFalse) =
+ fcmpImpliesClass(Pred, *F, CmpLHS, CmpRHS, LookThroughFAbsFNeg);
} else if (match(Cond,
m_Intrinsic<Intrinsic::is_fpclass>(
m_Value(TestedValue), m_ConstantInt(ClassVal)))) {
- TestedMask = static_cast<FPClassTest>(ClassVal);
+ FPClassTest TestedMask = static_cast<FPClassTest>(ClassVal);
+ MaskIfTrue = TestedMask;
+ MaskIfFalse = ~TestedMask;
}
if (TestedValue == LHS) {
// match !isnan(x) ? x : y
- FilterLHS = TestedMask;
- } else if (TestedValue == RHS) {
+ FilterLHS = MaskIfTrue;
+ } else if (TestedValue == RHS) { // && IsExactClass
// match !isnan(x) ? y : x
- FilterRHS = ~TestedMask;
+ FilterRHS = MaskIfFalse;
}
KnownFPClass Known2;
diff --git a/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp b/llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
index 421fc41ad3b62c3..e20f4adeab33dd2 ...
|
|
Broke this and needs rebase |
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Previously we could recognize exact class tests performed by an fcmp with special values (0s, infs and smallest normal). Expand this to recognize the implied classes by a compare with a general constant. e.g. fcmp ogt x, 1 implies positive and non-0.
The API should be better merged with fcmpToClassTest but that made the diff way bigger, will try to do that in a future patch.