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respectively. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97531 91177308-0d34-0410-b5e6-96231b3b80d8
696 lines
25 KiB
C++
696 lines
25 KiB
C++
//===- InstCombineMulDivRem.cpp -------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the visit functions for mul, fmul, sdiv, udiv, fdiv,
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// srem, urem, frem.
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//
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//===----------------------------------------------------------------------===//
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#include "InstCombine.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Support/PatternMatch.h"
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using namespace llvm;
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using namespace PatternMatch;
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/// SubOne - Subtract one from a ConstantInt.
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static Constant *SubOne(ConstantInt *C) {
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return ConstantInt::get(C->getContext(), C->getValue()-1);
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}
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/// MultiplyOverflows - True if the multiply can not be expressed in an int
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/// this size.
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static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
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uint32_t W = C1->getBitWidth();
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APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
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if (sign) {
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LHSExt.sext(W * 2);
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RHSExt.sext(W * 2);
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} else {
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LHSExt.zext(W * 2);
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RHSExt.zext(W * 2);
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}
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APInt MulExt = LHSExt * RHSExt;
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if (!sign)
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return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
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APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
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APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
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return MulExt.slt(Min) || MulExt.sgt(Max);
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}
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Instruction *InstCombiner::visitMul(BinaryOperator &I) {
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bool Changed = SimplifyCommutative(I);
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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if (isa<UndefValue>(Op1)) // undef * X -> 0
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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// Simplify mul instructions with a constant RHS.
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if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
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if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1C)) {
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// ((X << C1)*C2) == (X * (C2 << C1))
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if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
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if (SI->getOpcode() == Instruction::Shl)
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if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
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return BinaryOperator::CreateMul(SI->getOperand(0),
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ConstantExpr::getShl(CI, ShOp));
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if (CI->isZero())
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return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0
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if (CI->equalsInt(1)) // X * 1 == X
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return ReplaceInstUsesWith(I, Op0);
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if (CI->isAllOnesValue()) // X * -1 == 0 - X
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return BinaryOperator::CreateNeg(Op0, I.getName());
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const APInt& Val = cast<ConstantInt>(CI)->getValue();
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if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
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return BinaryOperator::CreateShl(Op0,
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ConstantInt::get(Op0->getType(), Val.logBase2()));
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}
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} else if (Op1C->getType()->isVectorTy()) {
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if (Op1C->isNullValue())
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return ReplaceInstUsesWith(I, Op1C);
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if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
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if (Op1V->isAllOnesValue()) // X * -1 == 0 - X
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return BinaryOperator::CreateNeg(Op0, I.getName());
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// As above, vector X*splat(1.0) -> X in all defined cases.
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if (Constant *Splat = Op1V->getSplatValue()) {
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if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat))
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if (CI->equalsInt(1))
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return ReplaceInstUsesWith(I, Op0);
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}
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}
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}
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if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
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if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
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isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1C)) {
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// Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
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Value *Add = Builder->CreateMul(Op0I->getOperand(0), Op1C, "tmp");
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Value *C1C2 = Builder->CreateMul(Op1C, Op0I->getOperand(1));
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return BinaryOperator::CreateAdd(Add, C1C2);
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}
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// Try to fold constant mul into select arguments.
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if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
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if (Instruction *R = FoldOpIntoSelect(I, SI))
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return R;
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if (isa<PHINode>(Op0))
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if (Instruction *NV = FoldOpIntoPhi(I))
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return NV;
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}
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if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
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if (Value *Op1v = dyn_castNegVal(Op1))
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return BinaryOperator::CreateMul(Op0v, Op1v);
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// (X / Y) * Y = X - (X % Y)
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// (X / Y) * -Y = (X % Y) - X
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{
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Value *Op1C = Op1;
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BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
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if (!BO ||
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(BO->getOpcode() != Instruction::UDiv &&
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BO->getOpcode() != Instruction::SDiv)) {
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Op1C = Op0;
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BO = dyn_cast<BinaryOperator>(Op1);
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}
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Value *Neg = dyn_castNegVal(Op1C);
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if (BO && BO->hasOneUse() &&
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(BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) &&
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(BO->getOpcode() == Instruction::UDiv ||
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BO->getOpcode() == Instruction::SDiv)) {
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Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
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// If the division is exact, X % Y is zero.
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if (SDivOperator *SDiv = dyn_cast<SDivOperator>(BO))
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if (SDiv->isExact()) {
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if (Op1BO == Op1C)
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return ReplaceInstUsesWith(I, Op0BO);
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return BinaryOperator::CreateNeg(Op0BO);
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}
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Value *Rem;
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if (BO->getOpcode() == Instruction::UDiv)
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Rem = Builder->CreateURem(Op0BO, Op1BO);
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else
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Rem = Builder->CreateSRem(Op0BO, Op1BO);
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Rem->takeName(BO);
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if (Op1BO == Op1C)
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return BinaryOperator::CreateSub(Op0BO, Rem);
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return BinaryOperator::CreateSub(Rem, Op0BO);
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}
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}
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/// i1 mul -> i1 and.
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if (I.getType()->isIntegerTy(1))
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return BinaryOperator::CreateAnd(Op0, Op1);
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// X*(1 << Y) --> X << Y
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// (1 << Y)*X --> X << Y
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{
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Value *Y;
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if (match(Op0, m_Shl(m_One(), m_Value(Y))))
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return BinaryOperator::CreateShl(Op1, Y);
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if (match(Op1, m_Shl(m_One(), m_Value(Y))))
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return BinaryOperator::CreateShl(Op0, Y);
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}
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// If one of the operands of the multiply is a cast from a boolean value, then
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// we know the bool is either zero or one, so this is a 'masking' multiply.
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// X * Y (where Y is 0 or 1) -> X & (0-Y)
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if (!I.getType()->isVectorTy()) {
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// -2 is "-1 << 1" so it is all bits set except the low one.
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APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
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Value *BoolCast = 0, *OtherOp = 0;
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if (MaskedValueIsZero(Op0, Negative2))
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BoolCast = Op0, OtherOp = Op1;
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else if (MaskedValueIsZero(Op1, Negative2))
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BoolCast = Op1, OtherOp = Op0;
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if (BoolCast) {
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Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()),
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BoolCast, "tmp");
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return BinaryOperator::CreateAnd(V, OtherOp);
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}
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}
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return Changed ? &I : 0;
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}
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Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
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bool Changed = SimplifyCommutative(I);
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// Simplify mul instructions with a constant RHS...
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if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
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if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1C)) {
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// "In IEEE floating point, x*1 is not equivalent to x for nans. However,
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// ANSI says we can drop signals, so we can do this anyway." (from GCC)
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if (Op1F->isExactlyValue(1.0))
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return ReplaceInstUsesWith(I, Op0); // Eliminate 'fmul double %X, 1.0'
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} else if (Op1C->getType()->isVectorTy()) {
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if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
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// As above, vector X*splat(1.0) -> X in all defined cases.
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if (Constant *Splat = Op1V->getSplatValue()) {
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if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
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if (F->isExactlyValue(1.0))
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return ReplaceInstUsesWith(I, Op0);
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}
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}
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}
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// Try to fold constant mul into select arguments.
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if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
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if (Instruction *R = FoldOpIntoSelect(I, SI))
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return R;
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if (isa<PHINode>(Op0))
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if (Instruction *NV = FoldOpIntoPhi(I))
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return NV;
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}
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if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y
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if (Value *Op1v = dyn_castFNegVal(Op1))
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return BinaryOperator::CreateFMul(Op0v, Op1v);
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return Changed ? &I : 0;
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}
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/// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
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/// instruction.
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bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
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SelectInst *SI = cast<SelectInst>(I.getOperand(1));
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// div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
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int NonNullOperand = -1;
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if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
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if (ST->isNullValue())
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NonNullOperand = 2;
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// div/rem X, (Cond ? Y : 0) -> div/rem X, Y
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if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
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if (ST->isNullValue())
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NonNullOperand = 1;
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if (NonNullOperand == -1)
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return false;
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Value *SelectCond = SI->getOperand(0);
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// Change the div/rem to use 'Y' instead of the select.
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I.setOperand(1, SI->getOperand(NonNullOperand));
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// Okay, we know we replace the operand of the div/rem with 'Y' with no
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// problem. However, the select, or the condition of the select may have
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// multiple uses. Based on our knowledge that the operand must be non-zero,
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// propagate the known value for the select into other uses of it, and
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// propagate a known value of the condition into its other users.
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// If the select and condition only have a single use, don't bother with this,
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// early exit.
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if (SI->use_empty() && SelectCond->hasOneUse())
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return true;
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// Scan the current block backward, looking for other uses of SI.
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BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
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while (BBI != BBFront) {
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--BBI;
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// If we found a call to a function, we can't assume it will return, so
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// information from below it cannot be propagated above it.
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if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
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break;
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// Replace uses of the select or its condition with the known values.
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for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
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I != E; ++I) {
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if (*I == SI) {
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*I = SI->getOperand(NonNullOperand);
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Worklist.Add(BBI);
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} else if (*I == SelectCond) {
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*I = NonNullOperand == 1 ? ConstantInt::getTrue(BBI->getContext()) :
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ConstantInt::getFalse(BBI->getContext());
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Worklist.Add(BBI);
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}
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}
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// If we past the instruction, quit looking for it.
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if (&*BBI == SI)
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SI = 0;
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if (&*BBI == SelectCond)
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SelectCond = 0;
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// If we ran out of things to eliminate, break out of the loop.
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if (SelectCond == 0 && SI == 0)
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break;
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}
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return true;
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}
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/// This function implements the transforms on div instructions that work
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/// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
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/// used by the visitors to those instructions.
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/// @brief Transforms common to all three div instructions
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Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// undef / X -> 0 for integer.
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// undef / X -> undef for FP (the undef could be a snan).
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if (isa<UndefValue>(Op0)) {
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if (Op0->getType()->isFPOrFPVectorTy())
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return ReplaceInstUsesWith(I, Op0);
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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}
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// X / undef -> undef
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if (isa<UndefValue>(Op1))
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return ReplaceInstUsesWith(I, Op1);
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return 0;
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}
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/// This function implements the transforms common to both integer division
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/// instructions (udiv and sdiv). It is called by the visitors to those integer
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/// division instructions.
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/// @brief Common integer divide transforms
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Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// (sdiv X, X) --> 1 (udiv X, X) --> 1
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if (Op0 == Op1) {
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if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) {
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Constant *CI = ConstantInt::get(Ty->getElementType(), 1);
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std::vector<Constant*> Elts(Ty->getNumElements(), CI);
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return ReplaceInstUsesWith(I, ConstantVector::get(Elts));
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}
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Constant *CI = ConstantInt::get(I.getType(), 1);
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return ReplaceInstUsesWith(I, CI);
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}
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if (Instruction *Common = commonDivTransforms(I))
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return Common;
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// Handle cases involving: [su]div X, (select Cond, Y, Z)
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// This does not apply for fdiv.
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if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
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return &I;
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if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
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// div X, 1 == X
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if (RHS->equalsInt(1))
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return ReplaceInstUsesWith(I, Op0);
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// (X / C1) / C2 -> X / (C1*C2)
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if (Instruction *LHS = dyn_cast<Instruction>(Op0))
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if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
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if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
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if (MultiplyOverflows(RHS, LHSRHS,
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I.getOpcode()==Instruction::SDiv))
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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else
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return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
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ConstantExpr::getMul(RHS, LHSRHS));
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}
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if (!RHS->isZero()) { // avoid X udiv 0
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if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
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if (Instruction *R = FoldOpIntoSelect(I, SI))
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return R;
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if (isa<PHINode>(Op0))
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if (Instruction *NV = FoldOpIntoPhi(I))
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return NV;
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}
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}
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// 0 / X == 0, we don't need to preserve faults!
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if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
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if (LHS->equalsInt(0))
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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// It can't be division by zero, hence it must be division by one.
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if (I.getType()->isIntegerTy(1))
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return ReplaceInstUsesWith(I, Op0);
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if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
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if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue()))
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// div X, 1 == X
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if (X->isOne())
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return ReplaceInstUsesWith(I, Op0);
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}
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return 0;
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}
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Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// Handle the integer div common cases
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if (Instruction *Common = commonIDivTransforms(I))
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return Common;
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if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
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// X udiv 2^C -> X >> C
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// Check to see if this is an unsigned division with an exact power of 2,
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// if so, convert to a right shift.
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if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
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return BinaryOperator::CreateLShr(Op0,
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ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
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// X udiv C, where C >= signbit
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if (C->getValue().isNegative()) {
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Value *IC = Builder->CreateICmpULT( Op0, C);
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return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
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ConstantInt::get(I.getType(), 1));
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}
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}
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// X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
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if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
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if (RHSI->getOpcode() == Instruction::Shl &&
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isa<ConstantInt>(RHSI->getOperand(0))) {
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const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
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if (C1.isPowerOf2()) {
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Value *N = RHSI->getOperand(1);
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const Type *NTy = N->getType();
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if (uint32_t C2 = C1.logBase2())
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N = Builder->CreateAdd(N, ConstantInt::get(NTy, C2), "tmp");
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return BinaryOperator::CreateLShr(Op0, N);
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}
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}
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}
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// udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
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// where C1&C2 are powers of two.
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if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
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if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
|
|
if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
|
|
const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
|
|
if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
|
|
// Compute the shift amounts
|
|
uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
|
|
// Construct the "on true" case of the select
|
|
Constant *TC = ConstantInt::get(Op0->getType(), TSA);
|
|
Value *TSI = Builder->CreateLShr(Op0, TC, SI->getName()+".t");
|
|
|
|
// Construct the "on false" case of the select
|
|
Constant *FC = ConstantInt::get(Op0->getType(), FSA);
|
|
Value *FSI = Builder->CreateLShr(Op0, FC, SI->getName()+".f");
|
|
|
|
// construct the select instruction and return it.
|
|
return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName());
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// Handle the integer div common cases
|
|
if (Instruction *Common = commonIDivTransforms(I))
|
|
return Common;
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// sdiv X, -1 == -X
|
|
if (RHS->isAllOnesValue())
|
|
return BinaryOperator::CreateNeg(Op0);
|
|
|
|
// sdiv X, C --> ashr X, log2(C)
|
|
if (cast<SDivOperator>(&I)->isExact() &&
|
|
RHS->getValue().isNonNegative() &&
|
|
RHS->getValue().isPowerOf2()) {
|
|
Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
|
|
RHS->getValue().exactLogBase2());
|
|
return BinaryOperator::CreateAShr(Op0, ShAmt, I.getName());
|
|
}
|
|
|
|
// -X/C --> X/-C provided the negation doesn't overflow.
|
|
if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
|
|
if (isa<Constant>(Sub->getOperand(0)) &&
|
|
cast<Constant>(Sub->getOperand(0))->isNullValue() &&
|
|
Sub->hasNoSignedWrap())
|
|
return BinaryOperator::CreateSDiv(Sub->getOperand(1),
|
|
ConstantExpr::getNeg(RHS));
|
|
}
|
|
|
|
// If the sign bits of both operands are zero (i.e. we can prove they are
|
|
// unsigned inputs), turn this into a udiv.
|
|
if (I.getType()->isIntegerTy()) {
|
|
APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
|
|
if (MaskedValueIsZero(Op0, Mask)) {
|
|
if (MaskedValueIsZero(Op1, Mask)) {
|
|
// X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
|
|
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
|
|
}
|
|
ConstantInt *ShiftedInt;
|
|
if (match(Op1, m_Shl(m_ConstantInt(ShiftedInt), m_Value())) &&
|
|
ShiftedInt->getValue().isPowerOf2()) {
|
|
// X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
|
|
// Safe because the only negative value (1 << Y) can take on is
|
|
// INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have
|
|
// the sign bit set.
|
|
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
|
|
return commonDivTransforms(I);
|
|
}
|
|
|
|
/// This function implements the transforms on rem instructions that work
|
|
/// regardless of the kind of rem instruction it is (urem, srem, or frem). It
|
|
/// is used by the visitors to those instructions.
|
|
/// @brief Transforms common to all three rem instructions
|
|
Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Op0)) { // undef % X -> 0
|
|
if (I.getType()->isFPOrFPVectorTy())
|
|
return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
if (isa<UndefValue>(Op1))
|
|
return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
|
|
|
|
// Handle cases involving: rem X, (select Cond, Y, Z)
|
|
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
|
|
return &I;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// This function implements the transforms common to both integer remainder
|
|
/// instructions (urem and srem). It is called by the visitors to those integer
|
|
/// remainder instructions.
|
|
/// @brief Common integer remainder transforms
|
|
Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Instruction *common = commonRemTransforms(I))
|
|
return common;
|
|
|
|
// 0 % X == 0 for integer, we don't need to preserve faults!
|
|
if (Constant *LHS = dyn_cast<Constant>(Op0))
|
|
if (LHS->isNullValue())
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// X % 0 == undef, we don't need to preserve faults!
|
|
if (RHS->equalsInt(0))
|
|
return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
|
|
|
|
if (RHS->equalsInt(1)) // X % 1 == 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI))
|
|
return R;
|
|
} else if (isa<PHINode>(Op0I)) {
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
|
|
// See if we can fold away this rem instruction.
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitURem(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Instruction *common = commonIRemTransforms(I))
|
|
return common;
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// X urem C^2 -> X and C
|
|
// Check to see if this is an unsigned remainder with an exact power of 2,
|
|
// if so, convert to a bitwise and.
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
|
|
if (C->getValue().isPowerOf2())
|
|
return BinaryOperator::CreateAnd(Op0, SubOne(C));
|
|
}
|
|
|
|
if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
|
|
// Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
|
|
if (RHSI->getOpcode() == Instruction::Shl &&
|
|
isa<ConstantInt>(RHSI->getOperand(0))) {
|
|
if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
|
|
Constant *N1 = Constant::getAllOnesValue(I.getType());
|
|
Value *Add = Builder->CreateAdd(RHSI, N1, "tmp");
|
|
return BinaryOperator::CreateAnd(Op0, Add);
|
|
}
|
|
}
|
|
}
|
|
|
|
// urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
|
|
// where C1&C2 are powers of two.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
|
|
if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
|
|
if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
|
|
// STO == 0 and SFO == 0 handled above.
|
|
if ((STO->getValue().isPowerOf2()) &&
|
|
(SFO->getValue().isPowerOf2())) {
|
|
Value *TrueAnd = Builder->CreateAnd(Op0, SubOne(STO),
|
|
SI->getName()+".t");
|
|
Value *FalseAnd = Builder->CreateAnd(Op0, SubOne(SFO),
|
|
SI->getName()+".f");
|
|
return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd);
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// Handle the integer rem common cases
|
|
if (Instruction *Common = commonIRemTransforms(I))
|
|
return Common;
|
|
|
|
if (Value *RHSNeg = dyn_castNegVal(Op1))
|
|
if (!isa<Constant>(RHSNeg) ||
|
|
(isa<ConstantInt>(RHSNeg) &&
|
|
cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
|
|
// X % -Y -> X % Y
|
|
Worklist.AddValue(I.getOperand(1));
|
|
I.setOperand(1, RHSNeg);
|
|
return &I;
|
|
}
|
|
|
|
// If the sign bits of both operands are zero (i.e. we can prove they are
|
|
// unsigned inputs), turn this into a urem.
|
|
if (I.getType()->isIntegerTy()) {
|
|
APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
|
|
if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
|
|
// X srem Y -> X urem Y, iff X and Y don't have sign bit set
|
|
return BinaryOperator::CreateURem(Op0, Op1, I.getName());
|
|
}
|
|
}
|
|
|
|
// If it's a constant vector, flip any negative values positive.
|
|
if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
|
|
unsigned VWidth = RHSV->getNumOperands();
|
|
|
|
bool hasNegative = false;
|
|
for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
|
|
if (RHS->getValue().isNegative())
|
|
hasNegative = true;
|
|
|
|
if (hasNegative) {
|
|
std::vector<Constant *> Elts(VWidth);
|
|
for (unsigned i = 0; i != VWidth; ++i) {
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
|
|
if (RHS->getValue().isNegative())
|
|
Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
|
|
else
|
|
Elts[i] = RHS;
|
|
}
|
|
}
|
|
|
|
Constant *NewRHSV = ConstantVector::get(Elts);
|
|
if (NewRHSV != RHSV) {
|
|
Worklist.AddValue(I.getOperand(1));
|
|
I.setOperand(1, NewRHSV);
|
|
return &I;
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
|
|
return commonRemTransforms(I);
|
|
}
|
|
|