//===-- IntegerDivision.cpp - Expand integer division ---------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file contains an implementation of 32bit and 64bit scalar integer // division for targets that don't have native support. It's largely derived // from compiler-rt's implementations of __udivsi3 and __udivmoddi4, // but hand-tuned for targets that prefer less control flow. // //===----------------------------------------------------------------------===// #include "llvm/Transforms/Utils/IntegerDivision.h" #include "llvm/IR/Function.h" #include "llvm/IR/IRBuilder.h" #include "llvm/IR/Instructions.h" #include "llvm/IR/Intrinsics.h" #include <utility> using namespace llvm; #define DEBUG_TYPE "integer-division" /// Generate code to compute the remainder of two signed integers. Returns the /// remainder, which will have the sign of the dividend. Builder's insert point /// should be pointing where the caller wants code generated, e.g. at the srem /// instruction. This will generate a urem in the process, and Builder's insert /// point will be pointing at the uren (if present, i.e. not folded), ready to /// be expanded if the user wishes static Value *generateSignedRemainderCode(Value *Dividend, Value *Divisor, IRBuilder<> &Builder) { unsigned BitWidth = Dividend->getType()->getIntegerBitWidth(); ConstantInt *Shift; if (BitWidth == 64) { Shift = Builder.getInt64(63); } else { assert(BitWidth == 32 && "Unexpected bit width"); Shift = Builder.getInt32(31); } // Following instructions are generated for both i32 (shift 31) and // i64 (shift 63). // ; %dividend_sgn = ashr i32 %dividend, 31 // ; %divisor_sgn = ashr i32 %divisor, 31 // ; %dvd_xor = xor i32 %dividend, %dividend_sgn // ; %dvs_xor = xor i32 %divisor, %divisor_sgn // ; %u_dividend = sub i32 %dvd_xor, %dividend_sgn // ; %u_divisor = sub i32 %dvs_xor, %divisor_sgn // ; %urem = urem i32 %dividend, %divisor // ; %xored = xor i32 %urem, %dividend_sgn // ; %srem = sub i32 %xored, %dividend_sgn Value *DividendSign = Builder.CreateAShr(Dividend, Shift); Value *DivisorSign = Builder.CreateAShr(Divisor, Shift); Value *DvdXor = Builder.CreateXor(Dividend, DividendSign); Value *DvsXor = Builder.CreateXor(Divisor, DivisorSign); Value *UDividend = Builder.CreateSub(DvdXor, DividendSign); Value *UDivisor = Builder.CreateSub(DvsXor, DivisorSign); Value *URem = Builder.CreateURem(UDividend, UDivisor); Value *Xored = Builder.CreateXor(URem, DividendSign); Value *SRem = Builder.CreateSub(Xored, DividendSign); if (Instruction *URemInst = dyn_cast<Instruction>(URem)) Builder.SetInsertPoint(URemInst); return SRem; } /// Generate code to compute the remainder of two unsigned integers. Returns the /// remainder. Builder's insert point should be pointing where the caller wants /// code generated, e.g. at the urem instruction. This will generate a udiv in /// the process, and Builder's insert point will be pointing at the udiv (if /// present, i.e. not folded), ready to be expanded if the user wishes static Value *generatedUnsignedRemainderCode(Value *Dividend, Value *Divisor, IRBuilder<> &Builder) { // Remainder = Dividend - Quotient*Divisor // Following instructions are generated for both i32 and i64 // ; %quotient = udiv i32 %dividend, %divisor // ; %product = mul i32 %divisor, %quotient // ; %remainder = sub i32 %dividend, %product Value *Quotient = Builder.CreateUDiv(Dividend, Divisor); Value *Product = Builder.CreateMul(Divisor, Quotient); Value *Remainder = Builder.CreateSub(Dividend, Product); if (Instruction *UDiv = dyn_cast<Instruction>(Quotient)) Builder.SetInsertPoint(UDiv); return Remainder; } /// Generate code to divide two signed integers. Returns the quotient, rounded /// towards 0. Builder's insert point should be pointing where the caller wants /// code generated, e.g. at the sdiv instruction. This will generate a udiv in /// the process, and Builder's insert point will be pointing at the udiv (if /// present, i.e. not folded), ready to be expanded if the user wishes. static Value *generateSignedDivisionCode(Value *Dividend, Value *Divisor, IRBuilder<> &Builder) { // Implementation taken from compiler-rt's __divsi3 and __divdi3 unsigned BitWidth = Dividend->getType()->getIntegerBitWidth(); ConstantInt *Shift; if (BitWidth == 64) { Shift = Builder.getInt64(63); } else { assert(BitWidth == 32 && "Unexpected bit width"); Shift = Builder.getInt32(31); } // Following instructions are generated for both i32 (shift 31) and // i64 (shift 63). // ; %tmp = ashr i32 %dividend, 31 // ; %tmp1 = ashr i32 %divisor, 31 // ; %tmp2 = xor i32 %tmp, %dividend // ; %u_dvnd = sub nsw i32 %tmp2, %tmp // ; %tmp3 = xor i32 %tmp1, %divisor // ; %u_dvsr = sub nsw i32 %tmp3, %tmp1 // ; %q_sgn = xor i32 %tmp1, %tmp // ; %q_mag = udiv i32 %u_dvnd, %u_dvsr // ; %tmp4 = xor i32 %q_mag, %q_sgn // ; %q = sub i32 %tmp4, %q_sgn Value *Tmp = Builder.CreateAShr(Dividend, Shift); Value *Tmp1 = Builder.CreateAShr(Divisor, Shift); Value *Tmp2 = Builder.CreateXor(Tmp, Dividend); Value *U_Dvnd = Builder.CreateSub(Tmp2, Tmp); Value *Tmp3 = Builder.CreateXor(Tmp1, Divisor); Value *U_Dvsr = Builder.CreateSub(Tmp3, Tmp1); Value *Q_Sgn = Builder.CreateXor(Tmp1, Tmp); Value *Q_Mag = Builder.CreateUDiv(U_Dvnd, U_Dvsr); Value *Tmp4 = Builder.CreateXor(Q_Mag, Q_Sgn); Value *Q = Builder.CreateSub(Tmp4, Q_Sgn); if (Instruction *UDiv = dyn_cast<Instruction>(Q_Mag)) Builder.SetInsertPoint(UDiv); return Q; } /// Generates code to divide two unsigned scalar 32-bit or 64-bit integers. /// Returns the quotient, rounded towards 0. Builder's insert point should /// point where the caller wants code generated, e.g. at the udiv instruction. static Value *generateUnsignedDivisionCode(Value *Dividend, Value *Divisor, IRBuilder<> &Builder) { // The basic algorithm can be found in the compiler-rt project's // implementation of __udivsi3.c. Here, we do a lower-level IR based approach // that's been hand-tuned to lessen the amount of control flow involved. // Some helper values IntegerType *DivTy = cast<IntegerType>(Dividend->getType()); unsigned BitWidth = DivTy->getBitWidth(); ConstantInt *Zero; ConstantInt *One; ConstantInt *NegOne; ConstantInt *MSB; if (BitWidth == 64) { Zero = Builder.getInt64(0); One = Builder.getInt64(1); NegOne = ConstantInt::getSigned(DivTy, -1); MSB = Builder.getInt64(63); } else { assert(BitWidth == 32 && "Unexpected bit width"); Zero = Builder.getInt32(0); One = Builder.getInt32(1); NegOne = ConstantInt::getSigned(DivTy, -1); MSB = Builder.getInt32(31); } ConstantInt *True = Builder.getTrue(); BasicBlock *IBB = Builder.GetInsertBlock(); Function *F = IBB->getParent(); Function *CTLZ = Intrinsic::getDeclaration(F->getParent(), Intrinsic::ctlz, DivTy); // Our CFG is going to look like: // +---------------------+ // | special-cases | // | ... | // +---------------------+ // | | // | +----------+ // | | bb1 | // | | ... | // | +----------+ // | | | // | | +------------+ // | | | preheader | // | | | ... | // | | +------------+ // | | | // | | | +---+ // | | | | | // | | +------------+ | // | | | do-while | | // | | | ... | | // | | +------------+ | // | | | | | // | +-----------+ +---+ // | | loop-exit | // | | ... | // | +-----------+ // | | // +-------+ // | ... | // | end | // +-------+ BasicBlock *SpecialCases = Builder.GetInsertBlock(); SpecialCases->setName(Twine(SpecialCases->getName(), "_udiv-special-cases")); BasicBlock *End = SpecialCases->splitBasicBlock(Builder.GetInsertPoint(), "udiv-end"); BasicBlock *LoopExit = BasicBlock::Create(Builder.getContext(), "udiv-loop-exit", F, End); BasicBlock *DoWhile = BasicBlock::Create(Builder.getContext(), "udiv-do-while", F, End); BasicBlock *Preheader = BasicBlock::Create(Builder.getContext(), "udiv-preheader", F, End); BasicBlock *BB1 = BasicBlock::Create(Builder.getContext(), "udiv-bb1", F, End); // We'll be overwriting the terminator to insert our extra blocks SpecialCases->getTerminator()->eraseFromParent(); // Same instructions are generated for both i32 (msb 31) and i64 (msb 63). // First off, check for special cases: dividend or divisor is zero, divisor // is greater than dividend, and divisor is 1. // ; special-cases: // ; %ret0_1 = icmp eq i32 %divisor, 0 // ; %ret0_2 = icmp eq i32 %dividend, 0 // ; %ret0_3 = or i1 %ret0_1, %ret0_2 // ; %tmp0 = tail call i32 @llvm.ctlz.i32(i32 %divisor, i1 true) // ; %tmp1 = tail call i32 @llvm.ctlz.i32(i32 %dividend, i1 true) // ; %sr = sub nsw i32 %tmp0, %tmp1 // ; %ret0_4 = icmp ugt i32 %sr, 31 // ; %ret0 = or i1 %ret0_3, %ret0_4 // ; %retDividend = icmp eq i32 %sr, 31 // ; %retVal = select i1 %ret0, i32 0, i32 %dividend // ; %earlyRet = or i1 %ret0, %retDividend // ; br i1 %earlyRet, label %end, label %bb1 Builder.SetInsertPoint(SpecialCases); Value *Ret0_1 = Builder.CreateICmpEQ(Divisor, Zero); Value *Ret0_2 = Builder.CreateICmpEQ(Dividend, Zero); Value *Ret0_3 = Builder.CreateOr(Ret0_1, Ret0_2); Value *Tmp0 = Builder.CreateCall2(CTLZ, Divisor, True); Value *Tmp1 = Builder.CreateCall2(CTLZ, Dividend, True); Value *SR = Builder.CreateSub(Tmp0, Tmp1); Value *Ret0_4 = Builder.CreateICmpUGT(SR, MSB); Value *Ret0 = Builder.CreateOr(Ret0_3, Ret0_4); Value *RetDividend = Builder.CreateICmpEQ(SR, MSB); Value *RetVal = Builder.CreateSelect(Ret0, Zero, Dividend); Value *EarlyRet = Builder.CreateOr(Ret0, RetDividend); Builder.CreateCondBr(EarlyRet, End, BB1); // ; bb1: ; preds = %special-cases // ; %sr_1 = add i32 %sr, 1 // ; %tmp2 = sub i32 31, %sr // ; %q = shl i32 %dividend, %tmp2 // ; %skipLoop = icmp eq i32 %sr_1, 0 // ; br i1 %skipLoop, label %loop-exit, label %preheader Builder.SetInsertPoint(BB1); Value *SR_1 = Builder.CreateAdd(SR, One); Value *Tmp2 = Builder.CreateSub(MSB, SR); Value *Q = Builder.CreateShl(Dividend, Tmp2); Value *SkipLoop = Builder.CreateICmpEQ(SR_1, Zero); Builder.CreateCondBr(SkipLoop, LoopExit, Preheader); // ; preheader: ; preds = %bb1 // ; %tmp3 = lshr i32 %dividend, %sr_1 // ; %tmp4 = add i32 %divisor, -1 // ; br label %do-while Builder.SetInsertPoint(Preheader); Value *Tmp3 = Builder.CreateLShr(Dividend, SR_1); Value *Tmp4 = Builder.CreateAdd(Divisor, NegOne); Builder.CreateBr(DoWhile); // ; do-while: ; preds = %do-while, %preheader // ; %carry_1 = phi i32 [ 0, %preheader ], [ %carry, %do-while ] // ; %sr_3 = phi i32 [ %sr_1, %preheader ], [ %sr_2, %do-while ] // ; %r_1 = phi i32 [ %tmp3, %preheader ], [ %r, %do-while ] // ; %q_2 = phi i32 [ %q, %preheader ], [ %q_1, %do-while ] // ; %tmp5 = shl i32 %r_1, 1 // ; %tmp6 = lshr i32 %q_2, 31 // ; %tmp7 = or i32 %tmp5, %tmp6 // ; %tmp8 = shl i32 %q_2, 1 // ; %q_1 = or i32 %carry_1, %tmp8 // ; %tmp9 = sub i32 %tmp4, %tmp7 // ; %tmp10 = ashr i32 %tmp9, 31 // ; %carry = and i32 %tmp10, 1 // ; %tmp11 = and i32 %tmp10, %divisor // ; %r = sub i32 %tmp7, %tmp11 // ; %sr_2 = add i32 %sr_3, -1 // ; %tmp12 = icmp eq i32 %sr_2, 0 // ; br i1 %tmp12, label %loop-exit, label %do-while Builder.SetInsertPoint(DoWhile); PHINode *Carry_1 = Builder.CreatePHI(DivTy, 2); PHINode *SR_3 = Builder.CreatePHI(DivTy, 2); PHINode *R_1 = Builder.CreatePHI(DivTy, 2); PHINode *Q_2 = Builder.CreatePHI(DivTy, 2); Value *Tmp5 = Builder.CreateShl(R_1, One); Value *Tmp6 = Builder.CreateLShr(Q_2, MSB); Value *Tmp7 = Builder.CreateOr(Tmp5, Tmp6); Value *Tmp8 = Builder.CreateShl(Q_2, One); Value *Q_1 = Builder.CreateOr(Carry_1, Tmp8); Value *Tmp9 = Builder.CreateSub(Tmp4, Tmp7); Value *Tmp10 = Builder.CreateAShr(Tmp9, MSB); Value *Carry = Builder.CreateAnd(Tmp10, One); Value *Tmp11 = Builder.CreateAnd(Tmp10, Divisor); Value *R = Builder.CreateSub(Tmp7, Tmp11); Value *SR_2 = Builder.CreateAdd(SR_3, NegOne); Value *Tmp12 = Builder.CreateICmpEQ(SR_2, Zero); Builder.CreateCondBr(Tmp12, LoopExit, DoWhile); // ; loop-exit: ; preds = %do-while, %bb1 // ; %carry_2 = phi i32 [ 0, %bb1 ], [ %carry, %do-while ] // ; %q_3 = phi i32 [ %q, %bb1 ], [ %q_1, %do-while ] // ; %tmp13 = shl i32 %q_3, 1 // ; %q_4 = or i32 %carry_2, %tmp13 // ; br label %end Builder.SetInsertPoint(LoopExit); PHINode *Carry_2 = Builder.CreatePHI(DivTy, 2); PHINode *Q_3 = Builder.CreatePHI(DivTy, 2); Value *Tmp13 = Builder.CreateShl(Q_3, One); Value *Q_4 = Builder.CreateOr(Carry_2, Tmp13); Builder.CreateBr(End); // ; end: ; preds = %loop-exit, %special-cases // ; %q_5 = phi i32 [ %q_4, %loop-exit ], [ %retVal, %special-cases ] // ; ret i32 %q_5 Builder.SetInsertPoint(End, End->begin()); PHINode *Q_5 = Builder.CreatePHI(DivTy, 2); // Populate the Phis, since all values have now been created. Our Phis were: // ; %carry_1 = phi i32 [ 0, %preheader ], [ %carry, %do-while ] Carry_1->addIncoming(Zero, Preheader); Carry_1->addIncoming(Carry, DoWhile); // ; %sr_3 = phi i32 [ %sr_1, %preheader ], [ %sr_2, %do-while ] SR_3->addIncoming(SR_1, Preheader); SR_3->addIncoming(SR_2, DoWhile); // ; %r_1 = phi i32 [ %tmp3, %preheader ], [ %r, %do-while ] R_1->addIncoming(Tmp3, Preheader); R_1->addIncoming(R, DoWhile); // ; %q_2 = phi i32 [ %q, %preheader ], [ %q_1, %do-while ] Q_2->addIncoming(Q, Preheader); Q_2->addIncoming(Q_1, DoWhile); // ; %carry_2 = phi i32 [ 0, %bb1 ], [ %carry, %do-while ] Carry_2->addIncoming(Zero, BB1); Carry_2->addIncoming(Carry, DoWhile); // ; %q_3 = phi i32 [ %q, %bb1 ], [ %q_1, %do-while ] Q_3->addIncoming(Q, BB1); Q_3->addIncoming(Q_1, DoWhile); // ; %q_5 = phi i32 [ %q_4, %loop-exit ], [ %retVal, %special-cases ] Q_5->addIncoming(Q_4, LoopExit); Q_5->addIncoming(RetVal, SpecialCases); return Q_5; } /// Generate code to calculate the remainder of two integers, replacing Rem with /// the generated code. This currently generates code using the udiv expansion, /// but future work includes generating more specialized code, e.g. when more /// information about the operands are known. Implements both 32bit and 64bit /// scalar division. /// /// @brief Replace Rem with generated code. bool llvm::expandRemainder(BinaryOperator *Rem) { assert((Rem->getOpcode() == Instruction::SRem || Rem->getOpcode() == Instruction::URem) && "Trying to expand remainder from a non-remainder function"); IRBuilder<> Builder(Rem); Type *RemTy = Rem->getType(); if (RemTy->isVectorTy()) llvm_unreachable("Div over vectors not supported"); unsigned RemTyBitWidth = RemTy->getIntegerBitWidth(); if (RemTyBitWidth != 32 && RemTyBitWidth != 64) llvm_unreachable("Div of bitwidth other than 32 or 64 not supported"); // First prepare the sign if it's a signed remainder if (Rem->getOpcode() == Instruction::SRem) { Value *Remainder = generateSignedRemainderCode(Rem->getOperand(0), Rem->getOperand(1), Builder); Rem->replaceAllUsesWith(Remainder); Rem->dropAllReferences(); Rem->eraseFromParent(); // If we didn't actually generate a udiv instruction, we're done BinaryOperator *BO = dyn_cast<BinaryOperator>(Builder.GetInsertPoint()); if (!BO || BO->getOpcode() != Instruction::URem) return true; Rem = BO; } Value *Remainder = generatedUnsignedRemainderCode(Rem->getOperand(0), Rem->getOperand(1), Builder); Rem->replaceAllUsesWith(Remainder); Rem->dropAllReferences(); Rem->eraseFromParent(); // Expand the udiv if (BinaryOperator *UDiv = dyn_cast<BinaryOperator>(Builder.GetInsertPoint())) { assert(UDiv->getOpcode() == Instruction::UDiv && "Non-udiv in expansion?"); expandDivision(UDiv); } return true; } /// Generate code to divide two integers, replacing Div with the generated /// code. This currently generates code similarly to compiler-rt's /// implementations, but future work includes generating more specialized code /// when more information about the operands are known. Implements both /// 32bit and 64bit scalar division. /// /// @brief Replace Div with generated code. bool llvm::expandDivision(BinaryOperator *Div) { assert((Div->getOpcode() == Instruction::SDiv || Div->getOpcode() == Instruction::UDiv) && "Trying to expand division from a non-division function"); IRBuilder<> Builder(Div); Type *DivTy = Div->getType(); if (DivTy->isVectorTy()) llvm_unreachable("Div over vectors not supported"); unsigned DivTyBitWidth = DivTy->getIntegerBitWidth(); if (DivTyBitWidth != 32 && DivTyBitWidth != 64) llvm_unreachable("Div of bitwidth other than 32 or 64 not supported"); // First prepare the sign if it's a signed division if (Div->getOpcode() == Instruction::SDiv) { // Lower the code to unsigned division, and reset Div to point to the udiv. Value *Quotient = generateSignedDivisionCode(Div->getOperand(0), Div->getOperand(1), Builder); Div->replaceAllUsesWith(Quotient); Div->dropAllReferences(); Div->eraseFromParent(); // If we didn't actually generate a udiv instruction, we're done BinaryOperator *BO = dyn_cast<BinaryOperator>(Builder.GetInsertPoint()); if (!BO || BO->getOpcode() != Instruction::UDiv) return true; Div = BO; } // Insert the unsigned division code Value *Quotient = generateUnsignedDivisionCode(Div->getOperand(0), Div->getOperand(1), Builder); Div->replaceAllUsesWith(Quotient); Div->dropAllReferences(); Div->eraseFromParent(); return true; } /// Generate code to compute the remainder of two integers of bitwidth up to /// 32 bits. Uses the above routines and extends the inputs/truncates the /// outputs to operate in 32 bits; that is, these routines are good for targets /// that have no or very little suppport for smaller than 32 bit integer /// arithmetic. /// /// @brief Replace Rem with emulation code. bool llvm::expandRemainderUpTo32Bits(BinaryOperator *Rem) { assert((Rem->getOpcode() == Instruction::SRem || Rem->getOpcode() == Instruction::URem) && "Trying to expand remainder from a non-remainder function"); Type *RemTy = Rem->getType(); if (RemTy->isVectorTy()) llvm_unreachable("Div over vectors not supported"); unsigned RemTyBitWidth = RemTy->getIntegerBitWidth(); if (RemTyBitWidth > 32) llvm_unreachable("Div of bitwidth greater than 32 not supported"); if (RemTyBitWidth == 32) return expandRemainder(Rem); // If bitwidth smaller than 32 extend inputs, extend output and proceed // with 32 bit division. IRBuilder<> Builder(Rem); Value *ExtDividend; Value *ExtDivisor; Value *ExtRem; Value *Trunc; Type *Int32Ty = Builder.getInt32Ty(); if (Rem->getOpcode() == Instruction::SRem) { ExtDividend = Builder.CreateSExt(Rem->getOperand(0), Int32Ty); ExtDivisor = Builder.CreateSExt(Rem->getOperand(1), Int32Ty); ExtRem = Builder.CreateSRem(ExtDividend, ExtDivisor); } else { ExtDividend = Builder.CreateZExt(Rem->getOperand(0), Int32Ty); ExtDivisor = Builder.CreateZExt(Rem->getOperand(1), Int32Ty); ExtRem = Builder.CreateURem(ExtDividend, ExtDivisor); } Trunc = Builder.CreateTrunc(ExtRem, RemTy); Rem->replaceAllUsesWith(Trunc); Rem->dropAllReferences(); Rem->eraseFromParent(); return expandRemainder(cast<BinaryOperator>(ExtRem)); } /// Generate code to compute the remainder of two integers of bitwidth up to /// 64 bits. Uses the above routines and extends the inputs/truncates the /// outputs to operate in 64 bits. /// /// @brief Replace Rem with emulation code. bool llvm::expandRemainderUpTo64Bits(BinaryOperator *Rem) { assert((Rem->getOpcode() == Instruction::SRem || Rem->getOpcode() == Instruction::URem) && "Trying to expand remainder from a non-remainder function"); Type *RemTy = Rem->getType(); if (RemTy->isVectorTy()) llvm_unreachable("Div over vectors not supported"); unsigned RemTyBitWidth = RemTy->getIntegerBitWidth(); if (RemTyBitWidth > 64) llvm_unreachable("Div of bitwidth greater than 64 not supported"); if (RemTyBitWidth == 64) return expandRemainder(Rem); // If bitwidth smaller than 64 extend inputs, extend output and proceed // with 64 bit division. IRBuilder<> Builder(Rem); Value *ExtDividend; Value *ExtDivisor; Value *ExtRem; Value *Trunc; Type *Int64Ty = Builder.getInt64Ty(); if (Rem->getOpcode() == Instruction::SRem) { ExtDividend = Builder.CreateSExt(Rem->getOperand(0), Int64Ty); ExtDivisor = Builder.CreateSExt(Rem->getOperand(1), Int64Ty); ExtRem = Builder.CreateSRem(ExtDividend, ExtDivisor); } else { ExtDividend = Builder.CreateZExt(Rem->getOperand(0), Int64Ty); ExtDivisor = Builder.CreateZExt(Rem->getOperand(1), Int64Ty); ExtRem = Builder.CreateURem(ExtDividend, ExtDivisor); } Trunc = Builder.CreateTrunc(ExtRem, RemTy); Rem->replaceAllUsesWith(Trunc); Rem->dropAllReferences(); Rem->eraseFromParent(); return expandRemainder(cast<BinaryOperator>(ExtRem)); } /// Generate code to divide two integers of bitwidth up to 32 bits. Uses the /// above routines and extends the inputs/truncates the outputs to operate /// in 32 bits; that is, these routines are good for targets that have no /// or very little support for smaller than 32 bit integer arithmetic. /// /// @brief Replace Div with emulation code. bool llvm::expandDivisionUpTo32Bits(BinaryOperator *Div) { assert((Div->getOpcode() == Instruction::SDiv || Div->getOpcode() == Instruction::UDiv) && "Trying to expand division from a non-division function"); Type *DivTy = Div->getType(); if (DivTy->isVectorTy()) llvm_unreachable("Div over vectors not supported"); unsigned DivTyBitWidth = DivTy->getIntegerBitWidth(); if (DivTyBitWidth > 32) llvm_unreachable("Div of bitwidth greater than 32 not supported"); if (DivTyBitWidth == 32) return expandDivision(Div); // If bitwidth smaller than 32 extend inputs, extend output and proceed // with 32 bit division. IRBuilder<> Builder(Div); Value *ExtDividend; Value *ExtDivisor; Value *ExtDiv; Value *Trunc; Type *Int32Ty = Builder.getInt32Ty(); if (Div->getOpcode() == Instruction::SDiv) { ExtDividend = Builder.CreateSExt(Div->getOperand(0), Int32Ty); ExtDivisor = Builder.CreateSExt(Div->getOperand(1), Int32Ty); ExtDiv = Builder.CreateSDiv(ExtDividend, ExtDivisor); } else { ExtDividend = Builder.CreateZExt(Div->getOperand(0), Int32Ty); ExtDivisor = Builder.CreateZExt(Div->getOperand(1), Int32Ty); ExtDiv = Builder.CreateUDiv(ExtDividend, ExtDivisor); } Trunc = Builder.CreateTrunc(ExtDiv, DivTy); Div->replaceAllUsesWith(Trunc); Div->dropAllReferences(); Div->eraseFromParent(); return expandDivision(cast<BinaryOperator>(ExtDiv)); } /// Generate code to divide two integers of bitwidth up to 64 bits. Uses the /// above routines and extends the inputs/truncates the outputs to operate /// in 64 bits. /// /// @brief Replace Div with emulation code. bool llvm::expandDivisionUpTo64Bits(BinaryOperator *Div) { assert((Div->getOpcode() == Instruction::SDiv || Div->getOpcode() == Instruction::UDiv) && "Trying to expand division from a non-division function"); Type *DivTy = Div->getType(); if (DivTy->isVectorTy()) llvm_unreachable("Div over vectors not supported"); unsigned DivTyBitWidth = DivTy->getIntegerBitWidth(); if (DivTyBitWidth > 64) llvm_unreachable("Div of bitwidth greater than 64 not supported"); if (DivTyBitWidth == 64) return expandDivision(Div); // If bitwidth smaller than 64 extend inputs, extend output and proceed // with 64 bit division. IRBuilder<> Builder(Div); Value *ExtDividend; Value *ExtDivisor; Value *ExtDiv; Value *Trunc; Type *Int64Ty = Builder.getInt64Ty(); if (Div->getOpcode() == Instruction::SDiv) { ExtDividend = Builder.CreateSExt(Div->getOperand(0), Int64Ty); ExtDivisor = Builder.CreateSExt(Div->getOperand(1), Int64Ty); ExtDiv = Builder.CreateSDiv(ExtDividend, ExtDivisor); } else { ExtDividend = Builder.CreateZExt(Div->getOperand(0), Int64Ty); ExtDivisor = Builder.CreateZExt(Div->getOperand(1), Int64Ty); ExtDiv = Builder.CreateUDiv(ExtDividend, ExtDivisor); } Trunc = Builder.CreateTrunc(ExtDiv, DivTy); Div->replaceAllUsesWith(Trunc); Div->dropAllReferences(); Div->eraseFromParent(); return expandDivision(cast<BinaryOperator>(ExtDiv)); }