X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FInstCombine%2FInstCombineMulDivRem.cpp;h=bbd4b2edc1b5b9e58b6b8c3aa6477af65e07f24d;hb=cd9f6b870ef0660ad4023d34a32c21c0d66516e6;hp=b95da85a7f33c983f498f8e01eec3c09133acc2c;hpb=dbaa2376f7b3c027e895ff4bee3ae08351f3ea88;p=oota-llvm.git diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index b95da85a7f3..bbd4b2edc1b 100644 --- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -14,11 +14,13 @@ #include "InstCombine.h" #include "llvm/Analysis/InstructionSimplify.h" -#include "llvm/IntrinsicInst.h" -#include "llvm/Support/PatternMatch.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/PatternMatch.h" using namespace llvm; using namespace PatternMatch; +#define DEBUG_TYPE "instcombine" + /// simplifyValueKnownNonZero - The specific integer value is used in a context /// where it is known to be non-zero. If this allows us to simplify the @@ -28,7 +30,7 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) { // if this is safe. For example, the use could be in dynamically unreached // code. if (!V->hasOneUse()) return 0; - + bool MadeChange = false; // ((1 << A) >>u B) --> (1 << (A-B)) @@ -41,7 +43,7 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) { A = IC.Builder->CreateSub(A, B); return IC.Builder->CreateShl(PowerOf2, A); } - + // (PowerOfTwo >>u B) --> isExact since shifting out the result would make it // inexact. Similarly for <<. if (BinaryOperator *I = dyn_cast(V)) @@ -52,12 +54,12 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) { I->setOperand(0, V2); MadeChange = true; } - + if (I->getOpcode() == Instruction::LShr && !I->isExact()) { I->setIsExact(); MadeChange = true; } - + if (I->getOpcode() == Instruction::Shl && !I->hasNoUnsignedWrap()) { I->setHasNoUnsignedWrap(); MadeChange = true; @@ -67,7 +69,7 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) { // TODO: Lots more we could do here: // If V is a phi node, we can call this on each of its operands. // "select cond, X, 0" can simplify to "X". - + return MadeChange ? V : 0; } @@ -84,22 +86,41 @@ static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) { LHSExt = LHSExt.zext(W * 2); RHSExt = RHSExt.zext(W * 2); } - + APInt MulExt = LHSExt * RHSExt; - + if (!sign) return MulExt.ugt(APInt::getLowBitsSet(W * 2, W)); - + APInt Min = APInt::getSignedMinValue(W).sext(W * 2); APInt Max = APInt::getSignedMaxValue(W).sext(W * 2); return MulExt.slt(Min) || MulExt.sgt(Max); } +/// \brief A helper routine of InstCombiner::visitMul(). +/// +/// If C is a vector of known powers of 2, then this function returns +/// a new vector obtained from C replacing each element with its logBase2. +/// Return a null pointer otherwise. +static Constant *getLogBase2Vector(ConstantDataVector *CV) { + const APInt *IVal; + SmallVector Elts; + + for (unsigned I = 0, E = CV->getNumElements(); I != E; ++I) { + Constant *Elt = CV->getElementAsConstant(I); + if (!match(Elt, m_APInt(IVal)) || !IVal->isPowerOf2()) + return 0; + Elts.push_back(ConstantInt::get(Elt->getType(), IVal->logBase2())); + } + + return ConstantVector::get(Elts); +} + Instruction *InstCombiner::visitMul(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = SimplifyMulInst(Op0, Op1, TD)) + if (Value *V = SimplifyMulInst(Op0, Op1, DL)) return ReplaceInstUsesWith(I, V); if (Value *V = SimplifyUsingDistributiveLaws(I)) @@ -107,34 +128,38 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { if (match(Op1, m_AllOnes())) // X * -1 == 0 - X return BinaryOperator::CreateNeg(Op0, I.getName()); - - if (ConstantInt *CI = dyn_cast(Op1)) { - - // ((X << C1)*C2) == (X * (C2 << C1)) - if (BinaryOperator *SI = dyn_cast(Op0)) - if (SI->getOpcode() == Instruction::Shl) - if (Constant *ShOp = dyn_cast(SI->getOperand(1))) - return BinaryOperator::CreateMul(SI->getOperand(0), - ConstantExpr::getShl(CI, ShOp)); - - const APInt &Val = CI->getValue(); - if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C - Constant *NewCst = ConstantInt::get(Op0->getType(), Val.logBase2()); - BinaryOperator *Shl = BinaryOperator::CreateShl(Op0, NewCst); - if (I.hasNoSignedWrap()) Shl->setHasNoSignedWrap(); - if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap(); - return Shl; - } - - // Canonicalize (X+C1)*CI -> X*CI+C1*CI. - { Value *X; ConstantInt *C1; - if (Op0->hasOneUse() && - match(Op0, m_Add(m_Value(X), m_ConstantInt(C1)))) { - Value *Add = Builder->CreateMul(X, CI); - return BinaryOperator::CreateAdd(Add, Builder->CreateMul(C1, CI)); + + // Also allow combining multiply instructions on vectors. + { + Value *NewOp; + Constant *C1, *C2; + const APInt *IVal; + if (match(&I, m_Mul(m_Shl(m_Value(NewOp), m_Constant(C2)), + m_Constant(C1))) && + match(C1, m_APInt(IVal))) + // ((X << C1)*C2) == (X * (C2 << C1)) + return BinaryOperator::CreateMul(NewOp, ConstantExpr::getShl(C1, C2)); + + if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) { + Constant *NewCst = 0; + if (match(C1, m_APInt(IVal)) && IVal->isPowerOf2()) + // Replace X*(2^C) with X << C, where C is either a scalar or a splat. + NewCst = ConstantInt::get(NewOp->getType(), IVal->logBase2()); + else if (ConstantDataVector *CV = dyn_cast(C1)) + // Replace X*(2^C) with X << C, where C is a vector of known + // constant powers of 2. + NewCst = getLogBase2Vector(CV); + + if (NewCst) { + BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst); + if (I.hasNoSignedWrap()) Shl->setHasNoSignedWrap(); + if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap(); + return Shl; } } + } + if (ConstantInt *CI = dyn_cast(Op1)) { // (Y - X) * (-(2**n)) -> (X - Y) * (2**n), for positive nonzero n // (Y + const) * (-(2**n)) -> (-constY) * (2**n), for positive nonzero n // The "* (2**n)" thus becomes a potential shifting opportunity. @@ -158,9 +183,9 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { } } } - + // Simplify mul instructions with a constant RHS. - if (isa(Op1)) { + if (isa(Op1)) { // Try to fold constant mul into select arguments. if (SelectInst *SI = dyn_cast(Op0)) if (Instruction *R = FoldOpIntoSelect(I, SI)) @@ -169,6 +194,16 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { if (isa(Op0)) if (Instruction *NV = FoldOpIntoPhi(I)) return NV; + + // Canonicalize (X+C1)*CI -> X*CI+C1*CI. + { + Value *X; + Constant *C1; + if (match(Op0, m_OneUse(m_Add(m_Value(X), m_Constant(C1))))) { + Value *Add = Builder->CreateMul(X, Op1); + return BinaryOperator::CreateAdd(Add, Builder->CreateMul(C1, Op1)); + } + } } if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y @@ -181,7 +216,7 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { Value *Op1C = Op1; BinaryOperator *BO = dyn_cast(Op0); if (!BO || - (BO->getOpcode() != Instruction::UDiv && + (BO->getOpcode() != Instruction::UDiv && BO->getOpcode() != Instruction::SDiv)) { Op1C = Op0; BO = dyn_cast(Op1); @@ -215,7 +250,7 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { } /// i1 mul -> i1 and. - if (I.getType()->isIntegerTy(1)) + if (I.getType()->getScalarType()->isIntegerTy(1)) return BinaryOperator::CreateAnd(Op0, Op1); // X*(1 << Y) --> X << Y @@ -227,14 +262,14 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { if (match(Op1, m_Shl(m_One(), m_Value(Y)))) return BinaryOperator::CreateShl(Op0, Y); } - + // If one of the operands of the multiply is a cast from a boolean value, then // we know the bool is either zero or one, so this is a 'masking' multiply. // X * Y (where Y is 0 or 1) -> X & (0-Y) if (!I.getType()->isVectorTy()) { // -2 is "-1 << 1" so it is all bits set except the low one. APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true); - + Value *BoolCast = 0, *OtherOp = 0; if (MaskedValueIsZero(Op0, Negative2)) BoolCast = Op0, OtherOp = Op1; @@ -280,24 +315,127 @@ static void detectLog2OfHalf(Value *&Op, Value *&Y, IntrinsicInst *&Log2) { return; if (I->getOpcode() != Instruction::FMul || !I->hasUnsafeAlgebra()) return; - - ConstantFP *CFP = dyn_cast(I->getOperand(0)); - if (CFP && CFP->isExactlyValue(0.5)) { + + if (match(I->getOperand(0), m_SpecificFP(0.5))) Y = I->getOperand(1); - return; - } - CFP = dyn_cast(I->getOperand(1)); - if (CFP && CFP->isExactlyValue(0.5)) + else if (match(I->getOperand(1), m_SpecificFP(0.5))) Y = I->getOperand(0); -} +} + +static bool isFiniteNonZeroFp(Constant *C) { + if (C->getType()->isVectorTy()) { + for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; + ++I) { + ConstantFP *CFP = dyn_cast(C->getAggregateElement(I)); + if (!CFP || !CFP->getValueAPF().isFiniteNonZero()) + return false; + } + return true; + } + + return isa(C) && + cast(C)->getValueAPF().isFiniteNonZero(); +} + +static bool isNormalFp(Constant *C) { + if (C->getType()->isVectorTy()) { + for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; + ++I) { + ConstantFP *CFP = dyn_cast(C->getAggregateElement(I)); + if (!CFP || !CFP->getValueAPF().isNormal()) + return false; + } + return true; + } + + return isa(C) && cast(C)->getValueAPF().isNormal(); +} + +/// Helper function of InstCombiner::visitFMul(BinaryOperator(). It returns +/// true iff the given value is FMul or FDiv with one and only one operand +/// being a normal constant (i.e. not Zero/NaN/Infinity). +static bool isFMulOrFDivWithConstant(Value *V) { + Instruction *I = dyn_cast(V); + if (!I || (I->getOpcode() != Instruction::FMul && + I->getOpcode() != Instruction::FDiv)) + return false; + + Constant *C0 = dyn_cast(I->getOperand(0)); + Constant *C1 = dyn_cast(I->getOperand(1)); + + if (C0 && C1) + return false; + + return (C0 && isFiniteNonZeroFp(C0)) || (C1 && isFiniteNonZeroFp(C1)); +} + +/// foldFMulConst() is a helper routine of InstCombiner::visitFMul(). +/// The input \p FMulOrDiv is a FMul/FDiv with one and only one operand +/// being a constant (i.e. isFMulOrFDivWithConstant(FMulOrDiv) == true). +/// This function is to simplify "FMulOrDiv * C" and returns the +/// resulting expression. Note that this function could return NULL in +/// case the constants cannot be folded into a normal floating-point. +/// +Value *InstCombiner::foldFMulConst(Instruction *FMulOrDiv, Constant *C, + Instruction *InsertBefore) { + assert(isFMulOrFDivWithConstant(FMulOrDiv) && "V is invalid"); + + Value *Opnd0 = FMulOrDiv->getOperand(0); + Value *Opnd1 = FMulOrDiv->getOperand(1); + + Constant *C0 = dyn_cast(Opnd0); + Constant *C1 = dyn_cast(Opnd1); + + BinaryOperator *R = 0; + + // (X * C0) * C => X * (C0*C) + if (FMulOrDiv->getOpcode() == Instruction::FMul) { + Constant *F = ConstantExpr::getFMul(C1 ? C1 : C0, C); + if (isNormalFp(F)) + R = BinaryOperator::CreateFMul(C1 ? Opnd0 : Opnd1, F); + } else { + if (C0) { + // (C0 / X) * C => (C0 * C) / X + if (FMulOrDiv->hasOneUse()) { + // It would otherwise introduce another div. + Constant *F = ConstantExpr::getFMul(C0, C); + if (isNormalFp(F)) + R = BinaryOperator::CreateFDiv(F, Opnd1); + } + } else { + // (X / C1) * C => X * (C/C1) if C/C1 is not a denormal + Constant *F = ConstantExpr::getFDiv(C, C1); + if (isNormalFp(F)) { + R = BinaryOperator::CreateFMul(Opnd0, F); + } else { + // (X / C1) * C => X / (C1/C) + Constant *F = ConstantExpr::getFDiv(C1, C); + if (isNormalFp(F)) + R = BinaryOperator::CreateFDiv(Opnd0, F); + } + } + } + + if (R) { + R->setHasUnsafeAlgebra(true); + InsertNewInstWith(R, *InsertBefore); + } + + return R; +} Instruction *InstCombiner::visitFMul(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = SimplifyFMulInst(Op0, Op1, I.getFastMathFlags(), TD)) + if (isa(Op0)) + std::swap(Op0, Op1); + + if (Value *V = SimplifyFMulInst(Op0, Op1, I.getFastMathFlags(), DL)) return ReplaceInstUsesWith(I, V); + bool AllowReassociate = I.hasUnsafeAlgebra(); + // Simplify mul instructions with a constant RHS. if (isa(Op1)) { // Try to fold constant mul into select arguments. @@ -308,11 +446,61 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) { if (isa(Op0)) if (Instruction *NV = FoldOpIntoPhi(I)) return NV; + + // (fmul X, -1.0) --> (fsub -0.0, X) + if (match(Op1, m_SpecificFP(-1.0))) { + Constant *NegZero = ConstantFP::getNegativeZero(Op1->getType()); + Instruction *RI = BinaryOperator::CreateFSub(NegZero, Op0); + RI->copyFastMathFlags(&I); + return RI; + } + + Constant *C = cast(Op1); + if (AllowReassociate && isFiniteNonZeroFp(C)) { + // Let MDC denote an expression in one of these forms: + // X * C, C/X, X/C, where C is a constant. + // + // Try to simplify "MDC * Constant" + if (isFMulOrFDivWithConstant(Op0)) + if (Value *V = foldFMulConst(cast(Op0), C, &I)) + return ReplaceInstUsesWith(I, V); + + // (MDC +/- C1) * C => (MDC * C) +/- (C1 * C) + Instruction *FAddSub = dyn_cast(Op0); + if (FAddSub && + (FAddSub->getOpcode() == Instruction::FAdd || + FAddSub->getOpcode() == Instruction::FSub)) { + Value *Opnd0 = FAddSub->getOperand(0); + Value *Opnd1 = FAddSub->getOperand(1); + Constant *C0 = dyn_cast(Opnd0); + Constant *C1 = dyn_cast(Opnd1); + bool Swap = false; + if (C0) { + std::swap(C0, C1); + std::swap(Opnd0, Opnd1); + Swap = true; + } + + if (C1 && isFiniteNonZeroFp(C1) && isFMulOrFDivWithConstant(Opnd0)) { + Value *M1 = ConstantExpr::getFMul(C1, C); + Value *M0 = isNormalFp(cast(M1)) ? + foldFMulConst(cast(Opnd0), C, &I) : + 0; + if (M0 && M1) { + if (Swap && FAddSub->getOpcode() == Instruction::FSub) + std::swap(M0, M1); + + Instruction *RI = (FAddSub->getOpcode() == Instruction::FAdd) + ? BinaryOperator::CreateFAdd(M0, M1) + : BinaryOperator::CreateFSub(M0, M1); + RI->copyFastMathFlags(&I); + return RI; + } + } + } + } } - if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y - if (Value *Op1v = dyn_castFNegVal(Op1)) - return BinaryOperator::CreateFMul(Op0v, Op1v); // Under unsafe algebra do: // X * log2(0.5*Y) = X*log2(Y) - X @@ -331,16 +519,110 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) { } // if pattern detected emit alternate sequence if (OpX && OpY) { + BuilderTy::FastMathFlagGuard Guard(*Builder); + Builder->SetFastMathFlags(Log2->getFastMathFlags()); Log2->setArgOperand(0, OpY); Value *FMulVal = Builder->CreateFMul(OpX, Log2); - Instruction *FMul = cast(FMulVal); - FMul->copyFastMathFlags(Log2); - Instruction *FSub = BinaryOperator::CreateFSub(FMulVal, OpX); - FSub->copyFastMathFlags(Log2); - return FSub; + Value *FSub = Builder->CreateFSub(FMulVal, OpX); + FSub->takeName(&I); + return ReplaceInstUsesWith(I, FSub); } } + // Handle symmetric situation in a 2-iteration loop + Value *Opnd0 = Op0; + Value *Opnd1 = Op1; + for (int i = 0; i < 2; i++) { + bool IgnoreZeroSign = I.hasNoSignedZeros(); + if (BinaryOperator::isFNeg(Opnd0, IgnoreZeroSign)) { + BuilderTy::FastMathFlagGuard Guard(*Builder); + Builder->SetFastMathFlags(I.getFastMathFlags()); + + Value *N0 = dyn_castFNegVal(Opnd0, IgnoreZeroSign); + Value *N1 = dyn_castFNegVal(Opnd1, IgnoreZeroSign); + + // -X * -Y => X*Y + if (N1) { + Value *FMul = Builder->CreateFMul(N0, N1); + FMul->takeName(&I); + return ReplaceInstUsesWith(I, FMul); + } + + if (Opnd0->hasOneUse()) { + // -X * Y => -(X*Y) (Promote negation as high as possible) + Value *T = Builder->CreateFMul(N0, Opnd1); + Value *Neg = Builder->CreateFNeg(T); + Neg->takeName(&I); + return ReplaceInstUsesWith(I, Neg); + } + } + + // (X*Y) * X => (X*X) * Y where Y != X + // The purpose is two-fold: + // 1) to form a power expression (of X). + // 2) potentially shorten the critical path: After transformation, the + // latency of the instruction Y is amortized by the expression of X*X, + // and therefore Y is in a "less critical" position compared to what it + // was before the transformation. + // + if (AllowReassociate) { + Value *Opnd0_0, *Opnd0_1; + if (Opnd0->hasOneUse() && + match(Opnd0, m_FMul(m_Value(Opnd0_0), m_Value(Opnd0_1)))) { + Value *Y = 0; + if (Opnd0_0 == Opnd1 && Opnd0_1 != Opnd1) + Y = Opnd0_1; + else if (Opnd0_1 == Opnd1 && Opnd0_0 != Opnd1) + Y = Opnd0_0; + + if (Y) { + BuilderTy::FastMathFlagGuard Guard(*Builder); + Builder->SetFastMathFlags(I.getFastMathFlags()); + Value *T = Builder->CreateFMul(Opnd1, Opnd1); + + Value *R = Builder->CreateFMul(T, Y); + R->takeName(&I); + return ReplaceInstUsesWith(I, R); + } + } + } + + // B * (uitofp i1 C) -> select C, B, 0 + if (I.hasNoNaNs() && I.hasNoInfs() && I.hasNoSignedZeros()) { + Value *LHS = Op0, *RHS = Op1; + Value *B, *C; + if (!match(RHS, m_UIToFP(m_Value(C)))) + std::swap(LHS, RHS); + + if (match(RHS, m_UIToFP(m_Value(C))) && + C->getType()->getScalarType()->isIntegerTy(1)) { + B = LHS; + Value *Zero = ConstantFP::getNegativeZero(B->getType()); + return SelectInst::Create(C, B, Zero); + } + } + + // A * (1 - uitofp i1 C) -> select C, 0, A + if (I.hasNoNaNs() && I.hasNoInfs() && I.hasNoSignedZeros()) { + Value *LHS = Op0, *RHS = Op1; + Value *A, *C; + if (!match(RHS, m_FSub(m_FPOne(), m_UIToFP(m_Value(C))))) + std::swap(LHS, RHS); + + if (match(RHS, m_FSub(m_FPOne(), m_UIToFP(m_Value(C)))) && + C->getType()->getScalarType()->isIntegerTy(1)) { + A = LHS; + Value *Zero = ConstantFP::getNegativeZero(A->getType()); + return SelectInst::Create(C, Zero, A); + } + } + + if (!isa(Op1)) + std::swap(Opnd0, Opnd1); + else + break; + } + return Changed ? &I : 0; } @@ -348,7 +630,7 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) { /// instruction. bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) { SelectInst *SI = cast(I.getOperand(1)); - + // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y int NonNullOperand = -1; if (Constant *ST = dyn_cast(SI->getOperand(1))) @@ -358,36 +640,36 @@ bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) { if (Constant *ST = dyn_cast(SI->getOperand(2))) if (ST->isNullValue()) NonNullOperand = 1; - + if (NonNullOperand == -1) return false; - + Value *SelectCond = SI->getOperand(0); - + // Change the div/rem to use 'Y' instead of the select. I.setOperand(1, SI->getOperand(NonNullOperand)); - + // Okay, we know we replace the operand of the div/rem with 'Y' with no // problem. However, the select, or the condition of the select may have // multiple uses. Based on our knowledge that the operand must be non-zero, // propagate the known value for the select into other uses of it, and // propagate a known value of the condition into its other users. - + // If the select and condition only have a single use, don't bother with this, // early exit. if (SI->use_empty() && SelectCond->hasOneUse()) return true; - + // Scan the current block backward, looking for other uses of SI. BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin(); - + while (BBI != BBFront) { --BBI; // If we found a call to a function, we can't assume it will return, so // information from below it cannot be propagated above it. if (isa(BBI) && !isa(BBI)) break; - + // Replace uses of the select or its condition with the known values. for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end(); I != E; ++I) { @@ -395,22 +677,21 @@ bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) { *I = SI->getOperand(NonNullOperand); Worklist.Add(BBI); } else if (*I == SelectCond) { - *I = NonNullOperand == 1 ? ConstantInt::getTrue(BBI->getContext()) : - ConstantInt::getFalse(BBI->getContext()); + *I = Builder->getInt1(NonNullOperand == 1); Worklist.Add(BBI); } } - + // If we past the instruction, quit looking for it. if (&*BBI == SI) SI = 0; if (&*BBI == SelectCond) SelectCond = 0; - + // If we ran out of things to eliminate, break out of the loop. if (SelectCond == 0 && SI == 0) break; - + } return true; } @@ -428,7 +709,7 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) { I.setOperand(1, V); return &I; } - + // Handle cases involving: [su]div X, (select Cond, Y, Z) // This does not apply for fdiv. if (isa(Op1) && SimplifyDivRemOfSelect(I)) @@ -485,80 +766,130 @@ static Value *dyn_castZExtVal(Value *V, Type *Ty) { return 0; } +namespace { +const unsigned MaxDepth = 6; +typedef Instruction *(*FoldUDivOperandCb)(Value *Op0, Value *Op1, + const BinaryOperator &I, + InstCombiner &IC); + +/// \brief Used to maintain state for visitUDivOperand(). +struct UDivFoldAction { + FoldUDivOperandCb FoldAction; ///< Informs visitUDiv() how to fold this + ///< operand. This can be zero if this action + ///< joins two actions together. + + Value *OperandToFold; ///< Which operand to fold. + union { + Instruction *FoldResult; ///< The instruction returned when FoldAction is + ///< invoked. + + size_t SelectLHSIdx; ///< Stores the LHS action index if this action + ///< joins two actions together. + }; + + UDivFoldAction(FoldUDivOperandCb FA, Value *InputOperand) + : FoldAction(FA), OperandToFold(InputOperand), FoldResult(0) {} + UDivFoldAction(FoldUDivOperandCb FA, Value *InputOperand, size_t SLHS) + : FoldAction(FA), OperandToFold(InputOperand), SelectLHSIdx(SLHS) {} +}; +} + +// X udiv 2^C -> X >> C +static Instruction *foldUDivPow2Cst(Value *Op0, Value *Op1, + const BinaryOperator &I, InstCombiner &IC) { + const APInt &C = cast(Op1)->getUniqueInteger(); + BinaryOperator *LShr = BinaryOperator::CreateLShr( + Op0, ConstantInt::get(Op0->getType(), C.logBase2())); + if (I.isExact()) LShr->setIsExact(); + return LShr; +} + +// X udiv C, where C >= signbit +static Instruction *foldUDivNegCst(Value *Op0, Value *Op1, + const BinaryOperator &I, InstCombiner &IC) { + Value *ICI = IC.Builder->CreateICmpULT(Op0, cast(Op1)); + + return SelectInst::Create(ICI, Constant::getNullValue(I.getType()), + ConstantInt::get(I.getType(), 1)); +} + +// X udiv (C1 << N), where C1 is "1< X >> (N+C2) +static Instruction *foldUDivShl(Value *Op0, Value *Op1, const BinaryOperator &I, + InstCombiner &IC) { + Instruction *ShiftLeft = cast(Op1); + if (isa(ShiftLeft)) + ShiftLeft = cast(ShiftLeft->getOperand(0)); + + const APInt &CI = + cast(ShiftLeft->getOperand(0))->getUniqueInteger(); + Value *N = ShiftLeft->getOperand(1); + if (CI != 1) + N = IC.Builder->CreateAdd(N, ConstantInt::get(N->getType(), CI.logBase2())); + if (ZExtInst *Z = dyn_cast(Op1)) + N = IC.Builder->CreateZExt(N, Z->getDestTy()); + BinaryOperator *LShr = BinaryOperator::CreateLShr(Op0, N); + if (I.isExact()) LShr->setIsExact(); + return LShr; +} + +// \brief Recursively visits the possible right hand operands of a udiv +// instruction, seeing through select instructions, to determine if we can +// replace the udiv with something simpler. If we find that an operand is not +// able to simplify the udiv, we abort the entire transformation. +static size_t visitUDivOperand(Value *Op0, Value *Op1, const BinaryOperator &I, + SmallVectorImpl &Actions, + unsigned Depth = 0) { + // Check to see if this is an unsigned division with an exact power of 2, + // if so, convert to a right shift. + if (match(Op1, m_Power2())) { + Actions.push_back(UDivFoldAction(foldUDivPow2Cst, Op1)); + return Actions.size(); + } + + if (ConstantInt *C = dyn_cast(Op1)) + // X udiv C, where C >= signbit + if (C->getValue().isNegative()) { + Actions.push_back(UDivFoldAction(foldUDivNegCst, C)); + return Actions.size(); + } + + // X udiv (C1 << N), where C1 is "1< X >> (N+C2) + if (match(Op1, m_Shl(m_Power2(), m_Value())) || + match(Op1, m_ZExt(m_Shl(m_Power2(), m_Value())))) { + Actions.push_back(UDivFoldAction(foldUDivShl, Op1)); + return Actions.size(); + } + + // The remaining tests are all recursive, so bail out if we hit the limit. + if (Depth++ == MaxDepth) + return 0; + + if (SelectInst *SI = dyn_cast(Op1)) + if (size_t LHSIdx = visitUDivOperand(Op0, SI->getOperand(1), I, Actions)) + if (visitUDivOperand(Op0, SI->getOperand(2), I, Actions)) { + Actions.push_back(UDivFoldAction((FoldUDivOperandCb)0, Op1, LHSIdx-1)); + return Actions.size(); + } + + return 0; +} + Instruction *InstCombiner::visitUDiv(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = SimplifyUDivInst(Op0, Op1, TD)) + if (Value *V = SimplifyUDivInst(Op0, Op1, DL)) return ReplaceInstUsesWith(I, V); // Handle the integer div common cases if (Instruction *Common = commonIDivTransforms(I)) return Common; - - { - // X udiv 2^C -> X >> C - // Check to see if this is an unsigned division with an exact power of 2, - // if so, convert to a right shift. - const APInt *C; - if (match(Op1, m_Power2(C))) { - BinaryOperator *LShr = - BinaryOperator::CreateLShr(Op0, - ConstantInt::get(Op0->getType(), - C->logBase2())); - if (I.isExact()) LShr->setIsExact(); - return LShr; - } - } - - if (ConstantInt *C = dyn_cast(Op1)) { - // X udiv C, where C >= signbit - if (C->getValue().isNegative()) { - Value *IC = Builder->CreateICmpULT(Op0, C); - return SelectInst::Create(IC, Constant::getNullValue(I.getType()), - ConstantInt::get(I.getType(), 1)); - } - } // (x lshr C1) udiv C2 --> x udiv (C2 << C1) - if (ConstantInt *C2 = dyn_cast(Op1)) { + if (Constant *C2 = dyn_cast(Op1)) { Value *X; - ConstantInt *C1; - if (match(Op0, m_LShr(m_Value(X), m_ConstantInt(C1)))) { - APInt NC = C2->getValue().shl(C1->getLimitedValue(C1->getBitWidth()-1)); - return BinaryOperator::CreateUDiv(X, Builder->getInt(NC)); - } - } - - // X udiv (C1 << N), where C1 is "1< X >> (N+C2) - { const APInt *CI; Value *N; - if (match(Op1, m_Shl(m_Power2(CI), m_Value(N))) || - match(Op1, m_ZExt(m_Shl(m_Power2(CI), m_Value(N))))) { - if (*CI != 1) - N = Builder->CreateAdd(N, - ConstantInt::get(N->getType(), CI->logBase2())); - if (ZExtInst *Z = dyn_cast(Op1)) - N = Builder->CreateZExt(N, Z->getDestTy()); - if (I.isExact()) - return BinaryOperator::CreateExactLShr(Op0, N); - return BinaryOperator::CreateLShr(Op0, N); - } - } - - // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2) - // where C1&C2 are powers of two. - { Value *Cond; const APInt *C1, *C2; - if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) { - // Construct the "on true" case of the select - Value *TSI = Builder->CreateLShr(Op0, C1->logBase2(), Op1->getName()+".t", - I.isExact()); - - // Construct the "on false" case of the select - Value *FSI = Builder->CreateLShr(Op0, C2->logBase2(), Op1->getName()+".f", - I.isExact()); - - // construct the select instruction and return it. - return SelectInst::Create(Cond, TSI, FSI); - } + Constant *C1; + if (match(Op0, m_LShr(m_Value(X), m_Constant(C1)))) + return BinaryOperator::CreateUDiv(X, ConstantExpr::getShl(C2, C1)); } // (zext A) udiv (zext B) --> zext (A udiv B) @@ -568,24 +899,55 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) { I.isExact()), I.getType()); + // (LHS udiv (select (select (...)))) -> (LHS >> (select (select (...)))) + SmallVector UDivActions; + if (visitUDivOperand(Op0, Op1, I, UDivActions)) + for (unsigned i = 0, e = UDivActions.size(); i != e; ++i) { + FoldUDivOperandCb Action = UDivActions[i].FoldAction; + Value *ActionOp1 = UDivActions[i].OperandToFold; + Instruction *Inst; + if (Action) + Inst = Action(Op0, ActionOp1, I, *this); + else { + // This action joins two actions together. The RHS of this action is + // simply the last action we processed, we saved the LHS action index in + // the joining action. + size_t SelectRHSIdx = i - 1; + Value *SelectRHS = UDivActions[SelectRHSIdx].FoldResult; + size_t SelectLHSIdx = UDivActions[i].SelectLHSIdx; + Value *SelectLHS = UDivActions[SelectLHSIdx].FoldResult; + Inst = SelectInst::Create(cast(ActionOp1)->getCondition(), + SelectLHS, SelectRHS); + } + + // If this is the last action to process, return it to the InstCombiner. + // Otherwise, we insert it before the UDiv and record it so that we may + // use it as part of a joining action (i.e., a SelectInst). + if (e - i != 1) { + Inst->insertBefore(&I); + UDivActions[i].FoldResult = Inst; + } else + return Inst; + } + return 0; } Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = SimplifySDivInst(Op0, Op1, TD)) + if (Value *V = SimplifySDivInst(Op0, Op1, DL)) return ReplaceInstUsesWith(I, V); // Handle the integer div common cases if (Instruction *Common = commonIDivTransforms(I)) return Common; - if (ConstantInt *RHS = dyn_cast(Op1)) { - // sdiv X, -1 == -X - if (RHS->isAllOnesValue()) - return BinaryOperator::CreateNeg(Op0); + // sdiv X, -1 == -X + if (match(Op1, m_AllOnes())) + return BinaryOperator::CreateNeg(Op0); + if (ConstantInt *RHS = dyn_cast(Op1)) { // sdiv X, C --> ashr exact X, log2(C) if (I.isExact() && RHS->getValue().isNonNegative() && RHS->getValue().isPowerOf2()) { @@ -593,7 +955,9 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { RHS->getValue().exactLogBase2()); return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName()); } + } + if (Constant *RHS = dyn_cast(Op1)) { // -X/C --> X/-C provided the negation doesn't overflow. if (SubOperator *Sub = dyn_cast(Op0)) if (match(Sub->getOperand(0), m_Zero()) && Sub->hasNoSignedWrap()) @@ -610,7 +974,7 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set return BinaryOperator::CreateUDiv(Op0, Op1, I.getName()); } - + if (match(Op1, m_Shl(m_Power2(), m_Value()))) { // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y) // Safe because the only negative value (1 << Y) can take on is @@ -620,25 +984,161 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { } } } - + return 0; } +/// CvtFDivConstToReciprocal tries to convert X/C into X*1/C if C not a special +/// FP value and: +/// 1) 1/C is exact, or +/// 2) reciprocal is allowed. +/// If the conversion was successful, the simplified expression "X * 1/C" is +/// returned; otherwise, NULL is returned. +/// +static Instruction *CvtFDivConstToReciprocal(Value *Dividend, + Constant *Divisor, + bool AllowReciprocal) { + if (!isa(Divisor)) // TODO: handle vectors. + return 0; + + const APFloat &FpVal = cast(Divisor)->getValueAPF(); + APFloat Reciprocal(FpVal.getSemantics()); + bool Cvt = FpVal.getExactInverse(&Reciprocal); + + if (!Cvt && AllowReciprocal && FpVal.isFiniteNonZero()) { + Reciprocal = APFloat(FpVal.getSemantics(), 1.0f); + (void)Reciprocal.divide(FpVal, APFloat::rmNearestTiesToEven); + Cvt = !Reciprocal.isDenormal(); + } + + if (!Cvt) + return 0; + + ConstantFP *R; + R = ConstantFP::get(Dividend->getType()->getContext(), Reciprocal); + return BinaryOperator::CreateFMul(Dividend, R); +} + Instruction *InstCombiner::visitFDiv(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = SimplifyFDivInst(Op0, Op1, TD)) + if (Value *V = SimplifyFDivInst(Op0, Op1, DL)) return ReplaceInstUsesWith(I, V); - if (ConstantFP *Op1C = dyn_cast(Op1)) { - const APFloat &Op1F = Op1C->getValueAPF(); + if (isa(Op0)) + if (SelectInst *SI = dyn_cast(Op1)) + if (Instruction *R = FoldOpIntoSelect(I, SI)) + return R; + + bool AllowReassociate = I.hasUnsafeAlgebra(); + bool AllowReciprocal = I.hasAllowReciprocal(); + + if (Constant *Op1C = dyn_cast(Op1)) { + if (SelectInst *SI = dyn_cast(Op0)) + if (Instruction *R = FoldOpIntoSelect(I, SI)) + return R; + + if (AllowReassociate) { + Constant *C1 = 0; + Constant *C2 = Op1C; + Value *X; + Instruction *Res = 0; + + if (match(Op0, m_FMul(m_Value(X), m_Constant(C1)))) { + // (X*C1)/C2 => X * (C1/C2) + // + Constant *C = ConstantExpr::getFDiv(C1, C2); + if (isNormalFp(C)) + Res = BinaryOperator::CreateFMul(X, C); + } else if (match(Op0, m_FDiv(m_Value(X), m_Constant(C1)))) { + // (X/C1)/C2 => X /(C2*C1) [=> X * 1/(C2*C1) if reciprocal is allowed] + // + Constant *C = ConstantExpr::getFMul(C1, C2); + if (isNormalFp(C)) { + Res = CvtFDivConstToReciprocal(X, C, AllowReciprocal); + if (!Res) + Res = BinaryOperator::CreateFDiv(X, C); + } + } + + if (Res) { + Res->setFastMathFlags(I.getFastMathFlags()); + return Res; + } + } + + // X / C => X * 1/C + if (Instruction *T = CvtFDivConstToReciprocal(Op0, Op1C, AllowReciprocal)) { + T->copyFastMathFlags(&I); + return T; + } + + return 0; + } + + if (AllowReassociate && isa(Op0)) { + Constant *C1 = cast(Op0), *C2; + Constant *Fold = 0; + Value *X; + bool CreateDiv = true; + + // C1 / (X*C2) => (C1/C2) / X + if (match(Op1, m_FMul(m_Value(X), m_Constant(C2)))) + Fold = ConstantExpr::getFDiv(C1, C2); + else if (match(Op1, m_FDiv(m_Value(X), m_Constant(C2)))) { + // C1 / (X/C2) => (C1*C2) / X + Fold = ConstantExpr::getFMul(C1, C2); + } else if (match(Op1, m_FDiv(m_Constant(C2), m_Value(X)))) { + // C1 / (C2/X) => (C1/C2) * X + Fold = ConstantExpr::getFDiv(C1, C2); + CreateDiv = false; + } + + if (Fold && isNormalFp(Fold)) { + Instruction *R = CreateDiv ? BinaryOperator::CreateFDiv(Fold, X) + : BinaryOperator::CreateFMul(X, Fold); + R->setFastMathFlags(I.getFastMathFlags()); + return R; + } + return 0; + } + + if (AllowReassociate) { + Value *X, *Y; + Value *NewInst = 0; + Instruction *SimpR = 0; + + if (Op0->hasOneUse() && match(Op0, m_FDiv(m_Value(X), m_Value(Y)))) { + // (X/Y) / Z => X / (Y*Z) + // + if (!isa(Y) || !isa(Op1)) { + NewInst = Builder->CreateFMul(Y, Op1); + if (Instruction *RI = dyn_cast(NewInst)) { + FastMathFlags Flags = I.getFastMathFlags(); + Flags &= cast(Op0)->getFastMathFlags(); + RI->setFastMathFlags(Flags); + } + SimpR = BinaryOperator::CreateFDiv(X, NewInst); + } + } else if (Op1->hasOneUse() && match(Op1, m_FDiv(m_Value(X), m_Value(Y)))) { + // Z / (X/Y) => Z*Y / X + // + if (!isa(Y) || !isa(Op0)) { + NewInst = Builder->CreateFMul(Op0, Y); + if (Instruction *RI = dyn_cast(NewInst)) { + FastMathFlags Flags = I.getFastMathFlags(); + Flags &= cast(Op1)->getFastMathFlags(); + RI->setFastMathFlags(Flags); + } + SimpR = BinaryOperator::CreateFDiv(NewInst, X); + } + } - // If the divisor has an exact multiplicative inverse we can turn the fdiv - // into a cheaper fmul. - APFloat Reciprocal(Op1F.getSemantics()); - if (Op1F.getExactInverse(&Reciprocal)) { - ConstantFP *RFP = ConstantFP::get(Builder->getContext(), Reciprocal); - return BinaryOperator::CreateFMul(Op0, RFP); + if (NewInst) { + if (Instruction *T = dyn_cast(NewInst)) + T->setDebugLoc(I.getDebugLoc()); + SimpR->setFastMathFlags(I.getFastMathFlags()); + return SimpR; } } @@ -662,7 +1162,7 @@ Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) { if (isa(Op1) && SimplifyDivRemOfSelect(I)) return &I; - if (isa(Op1)) { + if (isa(Op1)) { if (Instruction *Op0I = dyn_cast(Op0)) { if (SelectInst *SI = dyn_cast(Op0I)) { if (Instruction *R = FoldOpIntoSelect(I, SI)) @@ -684,56 +1184,45 @@ Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) { Instruction *InstCombiner::visitURem(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = SimplifyURemInst(Op0, Op1, TD)) + if (Value *V = SimplifyURemInst(Op0, Op1, DL)) return ReplaceInstUsesWith(I, V); if (Instruction *common = commonIRemTransforms(I)) return common; - - // X urem C^2 -> X and C-1 - { const APInt *C; - if (match(Op1, m_Power2(C))) - return BinaryOperator::CreateAnd(Op0, - ConstantInt::get(I.getType(), *C-1)); - } - // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) - if (match(Op1, m_Shl(m_Power2(), m_Value()))) { + // (zext A) urem (zext B) --> zext (A urem B) + if (ZExtInst *ZOp0 = dyn_cast(Op0)) + if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy())) + return new ZExtInst(Builder->CreateURem(ZOp0->getOperand(0), ZOp1), + I.getType()); + + // X urem Y -> X and Y-1, where Y is a power of 2, + if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/true)) { Constant *N1 = Constant::getAllOnesValue(I.getType()); Value *Add = Builder->CreateAdd(Op1, N1); return BinaryOperator::CreateAnd(Op0, Add); } - // urem X, (select Cond, 2^C1, 2^C2) --> - // select Cond, (and X, C1-1), (and X, C2-1) - // when C1&C2 are powers of two. - { Value *Cond; const APInt *C1, *C2; - if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) { - Value *TrueAnd = Builder->CreateAnd(Op0, *C1-1, Op1->getName()+".t"); - Value *FalseAnd = Builder->CreateAnd(Op0, *C2-1, Op1->getName()+".f"); - return SelectInst::Create(Cond, TrueAnd, FalseAnd); - } + // 1 urem X -> zext(X != 1) + if (match(Op0, m_One())) { + Value *Cmp = Builder->CreateICmpNE(Op1, Op0); + Value *Ext = Builder->CreateZExt(Cmp, I.getType()); + return ReplaceInstUsesWith(I, Ext); } - // (zext A) urem (zext B) --> zext (A urem B) - if (ZExtInst *ZOp0 = dyn_cast(Op0)) - if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy())) - return new ZExtInst(Builder->CreateURem(ZOp0->getOperand(0), ZOp1), - I.getType()); - return 0; } Instruction *InstCombiner::visitSRem(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = SimplifySRemInst(Op0, Op1, TD)) + if (Value *V = SimplifySRemInst(Op0, Op1, DL)) return ReplaceInstUsesWith(I, V); // Handle the integer rem common cases if (Instruction *Common = commonIRemTransforms(I)) return Common; - + if (Value *RHSNeg = dyn_castNegVal(Op1)) if (!isa(RHSNeg) || (isa(RHSNeg) && @@ -798,7 +1287,7 @@ Instruction *InstCombiner::visitSRem(BinaryOperator &I) { Instruction *InstCombiner::visitFRem(BinaryOperator &I) { Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - if (Value *V = SimplifyFRemInst(Op0, Op1, TD)) + if (Value *V = SimplifyFRemInst(Op0, Op1, DL)) return ReplaceInstUsesWith(I, V); // Handle cases involving: rem X, (select Cond, Y, Z)