diff options
Diffstat (limited to 'llvm/lib')
5 files changed, 170 insertions, 45 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index eaf79a74fcb..ace60fa9828 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -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) { - 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; + // 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: 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); } diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index e31ba326d09..805e68ff11e 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -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; diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp index 48ab0eb2c1b..72f0c1fc6a7 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp @@ -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), diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp index f51442a9f36..2df6193d512 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -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; diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp index 80628b23f11..142e071fa21 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp @@ -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, |
