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Add support for floating-point minnum and maxnum 

The select pattern recognition in ValueTracking (as used by InstCombine
and SelectionDAGBuilder) only knew about integer patterns. This teaches
it about minimum and maximum operations.

matchSelectPattern() has been extended to return a struct containing the
existing Flavor and a new enum defining the pattern's behavior when
given one NaN operand.

C minnum() is defined to return the non-NaN operand in this case, but
the idiomatic C "a < b ? a : b" would return the NaN operand.

ARM and AArch64 at least have different instructions for these different cases.

llvm-svn: 244580
This commit is contained in:
James Molloy 2015-08-11 09:12:57 +00:00
parent 1c78ca6a09
commit 134bec2722
9 changed files with 502 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
llvm/include/llvm/Analysis/ValueTracking.h
View File

@ -349,12 +349,32 @@ namespace llvm {
/// \brief Specific patterns of select instructions we can match.
enum SelectPatternFlavor {
SPF_UNKNOWN = 0,
SPF_SMIN, // Signed minimum
SPF_UMIN, // Unsigned minimum
SPF_SMAX, // Signed maximum
SPF_UMAX, // Unsigned maximum
SPF_ABS, // Absolute value
SPF_NABS // Negated absolute value
SPF_SMIN, /// Signed minimum
SPF_UMIN, /// Unsigned minimum
SPF_SMAX, /// Signed maximum
SPF_UMAX, /// Unsigned maximum
SPF_FMINNUM, /// Floating point minnum
SPF_FMAXNUM, /// Floating point maxnum
SPF_ABS, /// Absolute value
SPF_NABS /// Negated absolute value
};
/// \brief Behavior when a floating point min/max is given one NaN and one
/// non-NaN as input.
enum SelectPatternNaNBehavior {
SPNB_NA = 0, /// NaN behavior not applicable.
SPNB_RETURNS_NAN, /// Given one NaN input, returns the NaN.
SPNB_RETURNS_OTHER, /// Given one NaN input, returns the non-NaN.
SPNB_RETURNS_ANY /// Given one NaN input, can return either (or
/// it has been determined that no operands can
/// be NaN).
};
struct SelectPatternResult {
SelectPatternFlavor Flavor;
SelectPatternNaNBehavior NaNBehavior; /// Only applicable if Flavor is
/// SPF_FMINNUM or SPF_FMAXNUM.
bool Ordered; /// When implementing this min/max pattern as
/// fcmp; select, does the fcmp have to be
/// ordered?
};
/// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind
/// and providing the out parameter results if we successfully match.
@ -371,7 +391,7 @@ namespace llvm {
///
/// -> LHS = %a, RHS = i32 4, *CastOp = Instruction::SExt
///
SelectPatternFlavor matchSelectPattern(Value *V, Value *&LHS, Value *&RHS,
SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS,
Instruction::CastOps *CastOp = nullptr);
} // end namespace llvm

161
llvm/lib/Analysis/ValueTracking.cpp
View File

@ -3487,40 +3487,116 @@ bool llvm::isKnownNotFullPoison(const Instruction *PoisonI) {
return false;
}
static SelectPatternFlavor matchSelectPattern(ICmpInst::Predicate Pred,
static bool isKnownNonNaN(Value *V, FastMathFlags FMF) {
if (FMF.noNaNs())
return true;
if (auto *C = dyn_cast<ConstantFP>(V))
return !C->isNaN();
return false;
}
static bool isKnownNonZero(Value *V) {
if (auto *C = dyn_cast<ConstantFP>(V))
return !C->isZero();
return false;
}
static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred,
FastMathFlags FMF,
Value *CmpLHS, Value *CmpRHS,
Value *TrueVal, Value *FalseVal,
Value *&LHS, Value *&RHS) {
LHS = CmpLHS;
RHS = CmpRHS;
// (icmp X, Y) ? X : Y
if (TrueVal == CmpLHS && FalseVal == CmpRHS) {
// If the predicate is an "or-equal" (FP) predicate, then signed zeroes may
// return inconsistent results between implementations.
// (0.0 <= -0.0) ? 0.0 : -0.0 // Returns 0.0
// minNum(0.0, -0.0) // May return -0.0 or 0.0 (IEEE 754-2008 5.3.1)
// Therefore we behave conservatively and only proceed if at least one of the
// operands is known to not be zero, or if we don't care about signed zeroes.
switch (Pred) {
default: return SPF_UNKNOWN; // Equality.
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE: return SPF_UMAX;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE: return SPF_SMAX;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE: return SPF_UMIN;
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE: return SPF_SMIN;
default: break;
case CmpInst::FCMP_OGE: case CmpInst::FCMP_OLE:
case CmpInst::FCMP_UGE: case CmpInst::FCMP_ULE:
if (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) &&
!isKnownNonZero(CmpRHS))
return {SPF_UNKNOWN, SPNB_NA, false};
}
SelectPatternNaNBehavior NaNBehavior = SPNB_NA;
bool Ordered = false;
// When given one NaN and one non-NaN input:
// - maxnum/minnum (C99 fmaxf()/fminf()) return the non-NaN input.
// - A simple C99 (a < b ? a : b) construction will return 'b' (as the
// ordered comparison fails), which could be NaN or non-NaN.
// so here we discover exactly what NaN behavior is required/accepted.
if (CmpInst::isFPPredicate(Pred)) {
bool LHSSafe = isKnownNonNaN(CmpLHS, FMF);
bool RHSSafe = isKnownNonNaN(CmpRHS, FMF);
if (LHSSafe && RHSSafe) {
// Both operands are known non-NaN.
NaNBehavior = SPNB_RETURNS_ANY;
} else if (CmpInst::isOrdered(Pred)) {
// An ordered comparison will return false when given a NaN, so it
// returns the RHS.
Ordered = true;
if (LHSSafe)
// LHS is non-NaN, so RHS is NaN.
NaNBehavior = SPNB_RETURNS_NAN;
else if (RHSSafe)
NaNBehavior = SPNB_RETURNS_OTHER;
else
// Completely unsafe.
return {SPF_UNKNOWN, SPNB_NA, false};
} else {
Ordered = false;
// An unordered comparison will return true when given a NaN, so it
// returns the LHS.
if (LHSSafe)
// LHS is non-NaN.
NaNBehavior = SPNB_RETURNS_OTHER;
else if (RHSSafe)
NaNBehavior = SPNB_RETURNS_NAN;
else
// Completely unsafe.
return {SPF_UNKNOWN, SPNB_NA, false};
}
}
// (icmp X, Y) ? Y : X
if (TrueVal == CmpRHS && FalseVal == CmpLHS) {
std::swap(CmpLHS, CmpRHS);
Pred = CmpInst::getSwappedPredicate(Pred);
if (NaNBehavior == SPNB_RETURNS_NAN)
NaNBehavior = SPNB_RETURNS_OTHER;
else if (NaNBehavior == SPNB_RETURNS_OTHER)
NaNBehavior = SPNB_RETURNS_NAN;
Ordered = !Ordered;
}
// ([if]cmp X, Y) ? X : Y
if (TrueVal == CmpLHS && FalseVal == CmpRHS) {
switch (Pred) {
default: return SPF_UNKNOWN; // Equality.
default: return {SPF_UNKNOWN, SPNB_NA, false}; // Equality.
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE: return SPF_UMIN;
case ICmpInst::ICMP_UGE: return {SPF_UMAX, SPNB_NA, false};
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE: return SPF_SMIN;
case ICmpInst::ICMP_SGE: return {SPF_SMAX, SPNB_NA, false};
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE: return SPF_UMAX;
case ICmpInst::ICMP_ULE: return {SPF_UMIN, SPNB_NA, false};
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE: return SPF_SMAX;
case ICmpInst::ICMP_SLE: return {SPF_SMIN, SPNB_NA, false};
case FCmpInst::FCMP_UGT:
case FCmpInst::FCMP_UGE:
case FCmpInst::FCMP_OGT:
case FCmpInst::FCMP_OGE: return {SPF_FMAXNUM, NaNBehavior, Ordered};
case FCmpInst::FCMP_ULT:
case FCmpInst::FCMP_ULE:
case FCmpInst::FCMP_OLT:
case FCmpInst::FCMP_OLE: return {SPF_FMINNUM, NaNBehavior, Ordered};
}
}
@ -3531,13 +3607,13 @@ static SelectPatternFlavor matchSelectPattern(ICmpInst::Predicate Pred,
// ABS(X) ==> (X >s 0) ? X : -X and (X >s -1) ? X : -X
// NABS(X) ==> (X >s 0) ? -X : X and (X >s -1) ? -X : X
if (Pred == ICmpInst::ICMP_SGT && (C1->isZero() || C1->isMinusOne())) {
return (CmpLHS == TrueVal) ? SPF_ABS : SPF_NABS;
return {(CmpLHS == TrueVal) ? SPF_ABS : SPF_NABS, SPNB_NA, false};
}
// ABS(X) ==> (X <s 0) ? -X : X and (X <s 1) ? -X : X
// NABS(X) ==> (X <s 0) ? X : -X and (X <s 1) ? X : -X
if (Pred == ICmpInst::ICMP_SLT && (C1->isZero() || C1->isOne())) {
return (CmpLHS == FalseVal) ? SPF_ABS : SPF_NABS;
return {(CmpLHS == FalseVal) ? SPF_ABS : SPF_NABS, SPNB_NA, false};
}
}
@ -3548,17 +3624,17 @@ static SelectPatternFlavor matchSelectPattern(ICmpInst::Predicate Pred,
match(CmpLHS, m_Not(m_Specific(TrueVal))))) {
LHS = TrueVal;
RHS = FalseVal;
return SPF_SMIN;
return {SPF_SMIN, SPNB_NA, false};
}
}
}
// TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5)
return SPF_UNKNOWN;
return {SPF_UNKNOWN, SPNB_NA, false};
}
static Constant *lookThroughCast(ICmpInst *CmpI, Value *V1, Value *V2,
static Constant *lookThroughCast(CmpInst *CmpI, Value *V1, Value *V2,
Instruction::CastOps *CastOp) {
CastInst *CI = dyn_cast<CastInst>(V1);
Constant *C = dyn_cast<Constant>(V2);
@ -3580,39 +3656,60 @@ static Constant *lookThroughCast(ICmpInst *CmpI, Value *V1, Value *V2,
if (isa<TruncInst>(CI))
return ConstantExpr::getIntegerCast(C, CI->getSrcTy(), CmpI->isSigned());
if (isa<FPToUIInst>(CI))
return ConstantExpr::getUIToFP(C, CI->getSrcTy(), true);
if (isa<FPToSIInst>(CI))
return ConstantExpr::getSIToFP(C, CI->getSrcTy(), true);
if (isa<UIToFPInst>(CI))
return ConstantExpr::getFPToUI(C, CI->getSrcTy(), true);
if (isa<SIToFPInst>(CI))
return ConstantExpr::getFPToSI(C, CI->getSrcTy(), true);
if (isa<FPTruncInst>(CI))
return ConstantExpr::getFPExtend(C, CI->getSrcTy(), true);
if (isa<FPExtInst>(CI))
return ConstantExpr::getFPTrunc(C, CI->getSrcTy(), true);
return nullptr;
}
SelectPatternFlavor llvm::matchSelectPattern(Value *V,
SelectPatternResult llvm::matchSelectPattern(Value *V,
Value *&LHS, Value *&RHS,
Instruction::CastOps *CastOp) {
SelectInst *SI = dyn_cast<SelectInst>(V);
if (!SI) return SPF_UNKNOWN;
if (!SI) return {SPF_UNKNOWN, SPNB_NA, false};
ICmpInst *CmpI = dyn_cast<ICmpInst>(SI->getCondition());
if (!CmpI) return SPF_UNKNOWN;
CmpInst *CmpI = dyn_cast<CmpInst>(SI->getCondition());
if (!CmpI) return {SPF_UNKNOWN, SPNB_NA, false};
ICmpInst::Predicate Pred = CmpI->getPredicate();
CmpInst::Predicate Pred = CmpI->getPredicate();
Value *CmpLHS = CmpI->getOperand(0);
Value *CmpRHS = CmpI->getOperand(1);
Value *TrueVal = SI->getTrueValue();
Value *FalseVal = SI->getFalseValue();
FastMathFlags FMF;
if (isa<FPMathOperator>(CmpI))
FMF = CmpI->getFastMathFlags();
// Bail out early.
if (CmpI->isEquality())
return SPF_UNKNOWN;
return {SPF_UNKNOWN, SPNB_NA, false};
// Deal with type mismatches.
if (CastOp && CmpLHS->getType() != TrueVal->getType()) {
if (Constant *C = lookThroughCast(CmpI, TrueVal, FalseVal, CastOp))
return ::matchSelectPattern(Pred, CmpLHS, CmpRHS,
return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS,
cast<CastInst>(TrueVal)->getOperand(0), C,
LHS, RHS);
if (Constant *C = lookThroughCast(CmpI, FalseVal, TrueVal, CastOp))
return ::matchSelectPattern(Pred, CmpLHS, CmpRHS,
return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS,
C, cast<CastInst>(FalseVal)->getOperand(0),
LHS, RHS);
}
return ::matchSelectPattern(Pred, CmpLHS, CmpRHS, TrueVal, FalseVal,
return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, TrueVal, FalseVal,
LHS, RHS);
}

3
llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
View File

@ -2298,7 +2298,8 @@ void SelectionDAGBuilder::visitSelect(const User &I) {
// Min/max matching is only viable if all output VTs are the same.
if (std::equal(ValueVTs.begin(), ValueVTs.end(), ValueVTs.begin())) {
Value *LHS, *RHS;
SelectPatternFlavor SPF = matchSelectPattern(const_cast<User*>(&I), LHS, RHS);
SelectPatternFlavor SPF =
matchSelectPattern(const_cast<User*>(&I), LHS, RHS).Flavor;
ISD::NodeType Opc = ISD::DELETED_NODE;
switch (SPF) {
case SPF_UMAX: Opc = ISD::UMAX; break;

10
llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
View File

@ -441,7 +441,7 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
// min/max.
Value *LHS, *RHS;
if (SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0)))
if (matchSelectPattern(SI, LHS, RHS) != SPF_UNKNOWN)
if (matchSelectPattern(SI, LHS, RHS).Flavor != SPF_UNKNOWN)
return nullptr;
// See if we can simplify any instructions used by the input whose sole
@ -1307,10 +1307,16 @@ Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
// (fptrunc (select cond, R1, Cst)) -->
// (select cond, (fptrunc R1), (fptrunc Cst))
//
// - but only if this isn't part of a min/max operation, else we'll
// ruin min/max canonical form which is to have the select and
// compare's operands be of the same type with no casts to look through.
Value *LHS, *RHS;
SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0));
if (SI &&
(isa<ConstantFP>(SI->getOperand(1)) ||
isa<ConstantFP>(SI->getOperand(2)))) {
isa<ConstantFP>(SI->getOperand(2))) &&
matchSelectPattern(SI, LHS, RHS).Flavor == SPF_UNKNOWN) {
Value *LHSTrunc = Builder->CreateFPTrunc(SI->getOperand(1),
CI.getType());
Value *RHSTrunc = Builder->CreateFPTrunc(SI->getOperand(2),

37
llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
View File

@ -38,7 +38,8 @@ getInverseMinMaxSelectPattern(SelectPatternFlavor SPF) {
}
}
static CmpInst::Predicate getICmpPredicateForMinMax(SelectPatternFlavor SPF) {
static CmpInst::Predicate getCmpPredicateForMinMax(SelectPatternFlavor SPF,
bool Ordered=false) {
switch (SPF) {
default:
llvm_unreachable("unhandled!");
@ -51,13 +52,18 @@ static CmpInst::Predicate getICmpPredicateForMinMax(SelectPatternFlavor SPF) {
return ICmpInst::ICMP_SGT;
case SPF_UMAX:
return ICmpInst::ICMP_UGT;
case SPF_FMINNUM:
return Ordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT;
case SPF_FMAXNUM:
return Ordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT;
}
}
static Value *generateMinMaxSelectPattern(InstCombiner::BuilderTy *Builder,
SelectPatternFlavor SPF, Value *A,
Value *B) {
CmpInst::Predicate Pred = getICmpPredicateForMinMax(SPF);
CmpInst::Predicate Pred = getCmpPredicateForMinMax(SPF);
assert(CmpInst::isIntPredicate(Pred));
return Builder->CreateSelect(Builder->CreateICmp(Pred, A, B), A, B);
}
@ -926,6 +932,8 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
// (X ugt Y) ? X : Y -> (X ole Y) ? Y : X
if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
FCmpInst::Predicate InvPred = FCI->getInversePredicate();
IRBuilder<>::FastMathFlagGuard FMFG(*Builder);
Builder->SetFastMathFlags(FCI->getFastMathFlags());
Value *NewCond = Builder->CreateFCmp(InvPred, TrueVal, FalseVal,
FCI->getName() + ".inv");
@ -967,6 +975,8 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
// (X ugt Y) ? X : Y -> (X ole Y) ? X : Y
if (FCI->hasOneUse() && FCmpInst::isUnordered(FCI->getPredicate())) {
FCmpInst::Predicate InvPred = FCI->getInversePredicate();
IRBuilder<>::FastMathFlagGuard FMFG(*Builder);
Builder->SetFastMathFlags(FCI->getFastMathFlags());
Value *NewCond = Builder->CreateFCmp(InvPred, FalseVal, TrueVal,
FCI->getName() + ".inv");
@ -1054,20 +1064,31 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
}
// See if we can fold the select into one of our operands.
if (SI.getType()->isIntOrIntVectorTy()) {
if (SI.getType()->isIntOrIntVectorTy() || SI.getType()->isFPOrFPVectorTy()) {
if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
return FoldI;
Value *LHS, *RHS, *LHS2, *RHS2;
Instruction::CastOps CastOp;
SelectPatternFlavor SPF = matchSelectPattern(&SI, LHS, RHS, &CastOp);
SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp);
auto SPF = SPR.Flavor;
if (SPF) {
// Canonicalize so that type casts are outside select patterns.
if (LHS->getType()->getPrimitiveSizeInBits() !=
SI.getType()->getPrimitiveSizeInBits()) {
CmpInst::Predicate Pred = getICmpPredicateForMinMax(SPF);
Value *Cmp = Builder->CreateICmp(Pred, LHS, RHS);
CmpInst::Predicate Pred = getCmpPredicateForMinMax(SPF, SPR.Ordered);
Value *Cmp;
if (CmpInst::isIntPredicate(Pred)) {
Cmp = Builder->CreateICmp(Pred, LHS, RHS);
} else {
IRBuilder<>::FastMathFlagGuard FMFG(*Builder);
auto FMF = cast<FPMathOperator>(SI.getCondition())->getFastMathFlags();
Builder->SetFastMathFlags(FMF);
Cmp = Builder->CreateFCmp(Pred, LHS, RHS);
}
Value *NewSI = Builder->CreateCast(CastOp,
Builder->CreateSelect(Cmp, LHS, RHS),
SI.getType());
@ -1078,11 +1099,11 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
// MIN(MIN(a, b), a) -> MIN(a, b)
// MAX(MIN(a, b), a) -> a
// MIN(MAX(a, b), a) -> a
if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2))
if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor)
if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
SI, SPF, RHS))
return R;
if (SelectPatternFlavor SPF2 = matchSelectPattern(RHS, LHS2, RHS2))
if (SelectPatternFlavor SPF2 = matchSelectPattern(RHS, LHS2, RHS2).Flavor)
if (Instruction *R = FoldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2,
SI, SPF, LHS))
return R;

2
llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
View File

@ -410,7 +410,7 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
// If this is a select as part of a min/max pattern, don't simplify any
// further in case we break the structure.
Value *LHS, *RHS;
if (matchSelectPattern(I, LHS, RHS) != SPF_UNKNOWN)
if (matchSelectPattern(I, LHS, RHS).Flavor != SPF_UNKNOWN)
return nullptr;
if (SimplifyDemandedBits(I->getOperandUse(2), DemandedMask, RHSKnownZero,

156
llvm/test/Transforms/InstCombine/minmax-fp.ll Normal file
View File

@ -0,0 +1,156 @@
; RUN: opt -S -instcombine < %s | FileCheck %s
; CHECK-LABEL: @t1
; CHECK-NEXT: fcmp oge float %a, 5.000000e+00
; CHECK-NEXT: select i1 %.inv, float 5.000000e+00, float %a
; CHECK-NEXT: fpext float %1 to double
define double @t1(float %a) {
; This is the canonical form for a type-changing min/max.
%1 = fcmp ult float %a, 5.0
%2 = select i1 %1, float %a, float 5.0
%3 = fpext float %2 to double
ret double %3
}
; CHECK-LABEL: @t2
; CHECK-NEXT: fcmp oge float %a, 5.000000e+00
; CHECK-NEXT: select i1 %.inv, float 5.000000e+00, float %a
; CHECK-NEXT: fpext float %1 to double
define double @t2(float %a) {
; Check this is converted into canonical form, as above.
%1 = fcmp ult float %a, 5.0
%2 = fpext float %a to double
%3 = select i1 %1, double %2, double 5.0
ret double %3
}
; CHECK-LABEL: @t4
; CHECK-NEXT: fcmp oge double %a, 5.000000e+00
; CHECK-NEXT: select i1 %.inv, double 5.000000e+00, double %a
; CHECK-NEXT: fptrunc double %1 to float
define float @t4(double %a) {
; Same again, with trunc.
%1 = fcmp ult double %a, 5.0
%2 = fptrunc double %a to float
%3 = select i1 %1, float %2, float 5.0
ret float %3
}
; CHECK-LABEL: @t5
; CHECK-NEXT: fcmp ult float %a, 5.000000e+00
; CHECK-NEXT: fpext float %a to double
; CHECK-NEXT: select i1 %1, double %2, double 5.001
define double @t5(float %a) {
; different values, should not be converted.
%1 = fcmp ult float %a, 5.0
%2 = fpext float %a to double
%3 = select i1 %1, double %2, double 5.001
ret double %3
}
; CHECK-LABEL: @t6
; CHECK-NEXT: fcmp ult float %a, -0.0
; CHECK-NEXT: fpext float %a to double
; CHECK-NEXT: select i1 %1, double %2, double 0.0
define double @t6(float %a) {
; Signed zero, should not be converted
%1 = fcmp ult float %a, -0.0
%2 = fpext float %a to double
%3 = select i1 %1, double %2, double 0.0
ret double %3
}
; CHECK-LABEL: @t7
; CHECK-NEXT: fcmp ult float %a, 0.0
; CHECK-NEXT: fpext float %a to double
; CHECK-NEXT: select i1 %1, double %2, double -0.0
define double @t7(float %a) {
; Signed zero, should not be converted
%1 = fcmp ult float %a, 0.0
%2 = fpext float %a to double
%3 = select i1 %1, double %2, double -0.0
ret double %3
}
; CHECK-LABEL: @t8
; CHECK-NEXT: fcmp oge float %a, 5.000000e+00
; CHECK-NEXT: select i1 %.inv, float 5.000000e+00, float %a
; CHECK-NEXT: fptoui float %1 to i64
define i64 @t8(float %a) {
%1 = fcmp ult float %a, 5.0
%2 = fptoui float %a to i64
%3 = select i1 %1, i64 %2, i64 5
ret i64 %3
}
; CHECK-LABEL: @t9
; CHECK-NEXT: fcmp oge float %a, 0.000000e+00
; CHECK-NEXT: select i1 %.inv, float 0.000000e+00, float %a
; CHECK-NEXT: fptosi float %1 to i8
define i8 @t9(float %a) {
%1 = fcmp ult float %a, 0.0
%2 = fptosi float %a to i8
%3 = select i1 %1, i8 %2, i8 0
ret i8 %3
}
; CHECK-LABEL: @t11
; CHECK-NEXT: fcmp fast oge float %b, %a
; CHECK-NEXT: select i1 %.inv, float %a, float %b
; CHECK-NEXT: fptosi
define i8 @t11(float %a, float %b) {
; Either operand could be NaN, but fast modifier applied.
%1 = fcmp fast ult float %b, %a
%2 = fptosi float %a to i8
%3 = fptosi float %b to i8
%4 = select i1 %1, i8 %3, i8 %2
ret i8 %4
}
; CHECK-LABEL: @t12
; CHECK-NEXT: fcmp nnan oge float %b, %a
; CHECK-NEXT: select i1 %.inv, float %a, float %b
; CHECK-NEXT: fptosi float %.v to i8
define i8 @t12(float %a, float %b) {
; Either operand could be NaN, but nnan modifier applied.
%1 = fcmp nnan ult float %b, %a
%2 = fptosi float %a to i8
%3 = fptosi float %b to i8
%4 = select i1 %1, i8 %3, i8 %2
ret i8 %4
}
; CHECK-LABEL: @t13
; CHECK-NEXT: fcmp ult float %a, 1.500000e+00
; CHECK-NEXT: fptosi float %a to i8
; CHECK-NEXT: select i1 %1, i8 %2, i8 1
define i8 @t13(float %a) {
; Float and int values do not match.
%1 = fcmp ult float %a, 1.5
%2 = fptosi float %a to i8
%3 = select i1 %1, i8 %2, i8 1
ret i8 %3
}
; CHECK-LABEL: @t14
; CHECK-NEXT: fcmp ule float %a, 0.000000e+00
; CHECK-NEXT: fptosi float %a to i8
; CHECK-NEXT: select i1 %1, i8 %2, i8 0
define i8 @t14(float %a) {
; <= comparison, where %a could be -0.0. Not safe.
%1 = fcmp ule float %a, 0.0
%2 = fptosi float %a to i8
%3 = select i1 %1, i8 %2, i8 0
ret i8 %3
}
; CHECK-LABEL: @t15
; CHECK-NEXT: fcmp nsz oge float %a, 0.000000e+00
; CHECK-NEXT: select i1 %.inv, float 0.000000e+00, float %a
; CHECK-NEXT: fptosi float %1 to i8
define i8 @t15(float %a) {
%1 = fcmp nsz ule float %a, 0.0
%2 = fptosi float %a to i8
%3 = select i1 %1, i8 %2, i8 0
ret i8 %3
}

1
llvm/unittests/Analysis/CMakeLists.txt
View File

@ -13,4 +13,5 @@ add_llvm_unittest(AnalysisTests
LazyCallGraphTest.cpp
ScalarEvolutionTest.cpp
MixedTBAATest.cpp
ValueTrackingTest.cpp
)

148
llvm/unittests/Analysis/ValueTrackingTest.cpp Normal file
View File

@ -0,0 +1,148 @@
//===- ValueTrackingTest.cpp - ValueTracking tests ------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
using namespace llvm;
namespace {
class MatchSelectPatternTest : public testing::Test {
protected:
void parseAssembly(const char *Assembly) {
SMDiagnostic Error;
M = parseAssemblyString(Assembly, Error, getGlobalContext());
std::string errMsg;
raw_string_ostream os(errMsg);
Error.print("", os);
// A failure here means that the test itself is buggy.
if (!M)
report_fatal_error(os.str());
Function *F = M->getFunction("test");
if (F == nullptr)
report_fatal_error("Test must have a function named @test");
A = nullptr;
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
if (I->hasName()) {
if (I->getName() == "A")
A = &*I;
}
}
if (A == nullptr)
report_fatal_error("@test must have an instruction %A");
}
void expectPattern(const SelectPatternResult &P) {
Value *LHS, *RHS;
Instruction::CastOps CastOp;
SelectPatternResult R = matchSelectPattern(A, LHS, RHS, &CastOp);
EXPECT_EQ(P.Flavor, R.Flavor);
EXPECT_EQ(P.NaNBehavior, R.NaNBehavior);
EXPECT_EQ(P.Ordered, R.Ordered);
}
std::unique_ptr<Module> M;
Instruction *A, *B;
};
}
TEST_F(MatchSelectPatternTest, SimpleFMin) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ult float %a, 5.0\n"
" %A = select i1 %1, float %a, float 5.0\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMINNUM, SPNB_RETURNS_NAN, false});
}
TEST_F(MatchSelectPatternTest, SimpleFMax) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float %a, 5.0\n"
" %A = select i1 %1, float %a, float 5.0\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMAXNUM, SPNB_RETURNS_OTHER, true});
}
TEST_F(MatchSelectPatternTest, SwappedFMax) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float 5.0, %a\n"
" %A = select i1 %1, float %a, float 5.0\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMAXNUM, SPNB_RETURNS_OTHER, false});
}
TEST_F(MatchSelectPatternTest, SwappedFMax2) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float %a, 5.0\n"
" %A = select i1 %1, float 5.0, float %a\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMAXNUM, SPNB_RETURNS_NAN, false});
}
TEST_F(MatchSelectPatternTest, SwappedFMax3) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ult float %a, 5.0\n"
" %A = select i1 %1, float 5.0, float %a\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMAXNUM, SPNB_RETURNS_OTHER, true});
}
TEST_F(MatchSelectPatternTest, FastFMin) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp nnan olt float %a, 5.0\n"
" %A = select i1 %1, float %a, float 5.0\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMINNUM, SPNB_RETURNS_ANY, false});
}
TEST_F(MatchSelectPatternTest, FMinConstantZero) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ole float %a, 0.0\n"
" %A = select i1 %1, float %a, float 0.0\n"
" ret float %A\n"
"}\n");
// This shouldn't be matched, as %a could be -0.0.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinConstantZeroNsz) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp nsz ole float %a, 0.0\n"
" %A = select i1 %1, float %a, float 0.0\n"
" ret float %A\n"
"}\n");
// But this should be, because we've ignored signed zeroes.
expectPattern({SPF_FMINNUM, SPNB_RETURNS_OTHER, true});
}