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llvm-mirror/lib/Transforms/Utils/IntegerDivision.cpp
Craig Topper d426e33014 [Transforms] Use asserts instead of ifs around llvm_unreachable. NFC 
llvm-svn: 256405
2015-12-25 02:04:17 +00:00

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//===-- 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.CreateCall(CTLZ, {Divisor, True});
Value *Tmp1 = Builder.CreateCall(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);
assert(!Rem->getType()->isVectorTy() && "Div over vectors not supported");
assert((Rem->getType()->getIntegerBitWidth() == 32 ||
Rem->getType()->getIntegerBitWidth() == 64) &&
"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 an urem instruction, we're done
// This happens for example if the input were constant. In this case the
// Builder insertion point was unchanged
if (Rem == Builder.GetInsertPoint().getNodePtrUnchecked())
return true;
BinaryOperator *BO = dyn_cast<BinaryOperator>(Builder.GetInsertPoint());
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);
assert(!Div->getType()->isVectorTy() && "Div over vectors not supported");
assert((Div->getType()->getIntegerBitWidth() == 32 ||
Div->getType()->getIntegerBitWidth() == 64) &&
"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 an udiv instruction, we're done
// This happens for example if the input were constant. In this case the
// Builder insertion point was unchanged
if (Div == Builder.GetInsertPoint().getNodePtrUnchecked())
return true;
BinaryOperator *BO = dyn_cast<BinaryOperator>(Builder.GetInsertPoint());
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();
assert(!RemTy->isVectorTy() && "Div over vectors not supported");
unsigned RemTyBitWidth = RemTy->getIntegerBitWidth();
assert(RemTyBitWidth <= 32 &&
"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();
assert(!RemTy->isVectorTy() && "Div over vectors not supported");
unsigned RemTyBitWidth = RemTy->getIntegerBitWidth();
assert(RemTyBitWidth <= 64 && "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();
assert(!DivTy->isVectorTy() && "Div over vectors not supported");
unsigned DivTyBitWidth = DivTy->getIntegerBitWidth();
assert(DivTyBitWidth <= 32 && "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();
assert(!DivTy->isVectorTy() && "Div over vectors not supported");
unsigned DivTyBitWidth = DivTy->getIntegerBitWidth();
assert(DivTyBitWidth <= 64 &&
"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));
}
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