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1df9859c40
and T->isPointerTy(). Convert most instances of the first form to the second form. Requested by Chris. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96344 91177308-0d34-0410-b5e6-96231b3b80d8
562 lines
22 KiB
C++
562 lines
22 KiB
C++
//===- InstCombineVectorOps.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 instcombine for ExtractElement, InsertElement and
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// ShuffleVector.
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//
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//===----------------------------------------------------------------------===//
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#include "InstCombine.h"
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using namespace llvm;
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/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
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/// is to leave as a vector operation.
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static bool CheapToScalarize(Value *V, bool isConstant) {
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if (isa<ConstantAggregateZero>(V))
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return true;
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if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
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if (isConstant) return true;
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// If all elts are the same, we can extract.
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Constant *Op0 = C->getOperand(0);
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for (unsigned i = 1; i < C->getNumOperands(); ++i)
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if (C->getOperand(i) != Op0)
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return false;
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return true;
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}
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Instruction *I = dyn_cast<Instruction>(V);
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if (!I) return false;
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// Insert element gets simplified to the inserted element or is deleted if
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// this is constant idx extract element and its a constant idx insertelt.
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if (I->getOpcode() == Instruction::InsertElement && isConstant &&
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isa<ConstantInt>(I->getOperand(2)))
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return true;
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if (I->getOpcode() == Instruction::Load && I->hasOneUse())
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return true;
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if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
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if (BO->hasOneUse() &&
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(CheapToScalarize(BO->getOperand(0), isConstant) ||
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CheapToScalarize(BO->getOperand(1), isConstant)))
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return true;
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if (CmpInst *CI = dyn_cast<CmpInst>(I))
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if (CI->hasOneUse() &&
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(CheapToScalarize(CI->getOperand(0), isConstant) ||
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CheapToScalarize(CI->getOperand(1), isConstant)))
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return true;
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return false;
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}
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/// Read and decode a shufflevector mask.
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///
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/// It turns undef elements into values that are larger than the number of
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/// elements in the input.
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static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
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unsigned NElts = SVI->getType()->getNumElements();
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if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
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return std::vector<unsigned>(NElts, 0);
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if (isa<UndefValue>(SVI->getOperand(2)))
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return std::vector<unsigned>(NElts, 2*NElts);
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std::vector<unsigned> Result;
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const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
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for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
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if (isa<UndefValue>(*i))
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Result.push_back(NElts*2); // undef -> 8
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else
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Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
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return Result;
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}
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/// FindScalarElement - Given a vector and an element number, see if the scalar
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/// value is already around as a register, for example if it were inserted then
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/// extracted from the vector.
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static Value *FindScalarElement(Value *V, unsigned EltNo) {
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assert(V->getType()->isVectorTy() && "Not looking at a vector?");
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const VectorType *PTy = cast<VectorType>(V->getType());
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unsigned Width = PTy->getNumElements();
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if (EltNo >= Width) // Out of range access.
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return UndefValue::get(PTy->getElementType());
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if (isa<UndefValue>(V))
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return UndefValue::get(PTy->getElementType());
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if (isa<ConstantAggregateZero>(V))
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return Constant::getNullValue(PTy->getElementType());
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if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
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return CP->getOperand(EltNo);
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if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
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// If this is an insert to a variable element, we don't know what it is.
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if (!isa<ConstantInt>(III->getOperand(2)))
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return 0;
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unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
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// If this is an insert to the element we are looking for, return the
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// inserted value.
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if (EltNo == IIElt)
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return III->getOperand(1);
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// Otherwise, the insertelement doesn't modify the value, recurse on its
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// vector input.
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return FindScalarElement(III->getOperand(0), EltNo);
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}
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if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
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unsigned LHSWidth =
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cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
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unsigned InEl = getShuffleMask(SVI)[EltNo];
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if (InEl < LHSWidth)
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return FindScalarElement(SVI->getOperand(0), InEl);
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else if (InEl < LHSWidth*2)
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return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
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else
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return UndefValue::get(PTy->getElementType());
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}
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// Otherwise, we don't know.
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return 0;
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}
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Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
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// If vector val is undef, replace extract with scalar undef.
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if (isa<UndefValue>(EI.getOperand(0)))
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return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
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// If vector val is constant 0, replace extract with scalar 0.
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if (isa<ConstantAggregateZero>(EI.getOperand(0)))
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return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
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if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
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// If vector val is constant with all elements the same, replace EI with
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// that element. When the elements are not identical, we cannot replace yet
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// (we do that below, but only when the index is constant).
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Constant *op0 = C->getOperand(0);
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for (unsigned i = 1; i != C->getNumOperands(); ++i)
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if (C->getOperand(i) != op0) {
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op0 = 0;
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break;
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}
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if (op0)
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return ReplaceInstUsesWith(EI, op0);
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}
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// If extracting a specified index from the vector, see if we can recursively
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// find a previously computed scalar that was inserted into the vector.
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if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
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unsigned IndexVal = IdxC->getZExtValue();
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unsigned VectorWidth = EI.getVectorOperandType()->getNumElements();
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// If this is extracting an invalid index, turn this into undef, to avoid
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// crashing the code below.
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if (IndexVal >= VectorWidth)
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return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
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// This instruction only demands the single element from the input vector.
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// If the input vector has a single use, simplify it based on this use
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// property.
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if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
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APInt UndefElts(VectorWidth, 0);
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APInt DemandedMask(VectorWidth, 0);
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DemandedMask.set(IndexVal);
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if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
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DemandedMask, UndefElts)) {
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EI.setOperand(0, V);
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return &EI;
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}
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}
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if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
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return ReplaceInstUsesWith(EI, Elt);
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// If the this extractelement is directly using a bitcast from a vector of
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// the same number of elements, see if we can find the source element from
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// it. In this case, we will end up needing to bitcast the scalars.
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if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
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if (const VectorType *VT =
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dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
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if (VT->getNumElements() == VectorWidth)
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if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
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return new BitCastInst(Elt, EI.getType());
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}
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}
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if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
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// Push extractelement into predecessor operation if legal and
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// profitable to do so
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if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
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if (I->hasOneUse() &&
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CheapToScalarize(BO, isa<ConstantInt>(EI.getOperand(1)))) {
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Value *newEI0 =
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Builder->CreateExtractElement(BO->getOperand(0), EI.getOperand(1),
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EI.getName()+".lhs");
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Value *newEI1 =
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Builder->CreateExtractElement(BO->getOperand(1), EI.getOperand(1),
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EI.getName()+".rhs");
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return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
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}
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} else if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
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// Extracting the inserted element?
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if (IE->getOperand(2) == EI.getOperand(1))
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return ReplaceInstUsesWith(EI, IE->getOperand(1));
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// If the inserted and extracted elements are constants, they must not
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// be the same value, extract from the pre-inserted value instead.
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if (isa<Constant>(IE->getOperand(2)) && isa<Constant>(EI.getOperand(1))) {
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Worklist.AddValue(EI.getOperand(0));
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EI.setOperand(0, IE->getOperand(0));
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return &EI;
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}
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} else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
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// If this is extracting an element from a shufflevector, figure out where
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// it came from and extract from the appropriate input element instead.
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if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
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unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
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Value *Src;
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unsigned LHSWidth =
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cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
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if (SrcIdx < LHSWidth)
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Src = SVI->getOperand(0);
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else if (SrcIdx < LHSWidth*2) {
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SrcIdx -= LHSWidth;
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Src = SVI->getOperand(1);
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} else {
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return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
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}
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return ExtractElementInst::Create(Src,
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ConstantInt::get(Type::getInt32Ty(EI.getContext()),
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SrcIdx, false));
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}
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}
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// FIXME: Canonicalize extractelement(bitcast) -> bitcast(extractelement)
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}
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return 0;
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}
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/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
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/// elements from either LHS or RHS, return the shuffle mask and true.
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/// Otherwise, return false.
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static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
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std::vector<Constant*> &Mask) {
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assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
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"Invalid CollectSingleShuffleElements");
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unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
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if (isa<UndefValue>(V)) {
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Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
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return true;
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}
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if (V == LHS) {
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for (unsigned i = 0; i != NumElts; ++i)
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Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
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return true;
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}
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if (V == RHS) {
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for (unsigned i = 0; i != NumElts; ++i)
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Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()),
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i+NumElts));
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return true;
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}
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if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
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// If this is an insert of an extract from some other vector, include it.
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Value *VecOp = IEI->getOperand(0);
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Value *ScalarOp = IEI->getOperand(1);
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Value *IdxOp = IEI->getOperand(2);
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if (!isa<ConstantInt>(IdxOp))
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return false;
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unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
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if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
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// Okay, we can handle this if the vector we are insertinting into is
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// transitively ok.
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if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
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// If so, update the mask to reflect the inserted undef.
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Mask[InsertedIdx] = UndefValue::get(Type::getInt32Ty(V->getContext()));
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return true;
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}
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} else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
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if (isa<ConstantInt>(EI->getOperand(1)) &&
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EI->getOperand(0)->getType() == V->getType()) {
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unsigned ExtractedIdx =
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cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
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// This must be extracting from either LHS or RHS.
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if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
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// Okay, we can handle this if the vector we are insertinting into is
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// transitively ok.
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if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
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// If so, update the mask to reflect the inserted value.
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if (EI->getOperand(0) == LHS) {
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Mask[InsertedIdx % NumElts] =
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ConstantInt::get(Type::getInt32Ty(V->getContext()),
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ExtractedIdx);
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} else {
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assert(EI->getOperand(0) == RHS);
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Mask[InsertedIdx % NumElts] =
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ConstantInt::get(Type::getInt32Ty(V->getContext()),
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ExtractedIdx+NumElts);
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}
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return true;
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}
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}
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}
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}
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}
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// TODO: Handle shufflevector here!
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return false;
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}
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/// CollectShuffleElements - We are building a shuffle of V, using RHS as the
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/// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
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/// that computes V and the LHS value of the shuffle.
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static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
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Value *&RHS) {
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assert(V->getType()->isVectorTy() &&
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(RHS == 0 || V->getType() == RHS->getType()) &&
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"Invalid shuffle!");
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unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
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if (isa<UndefValue>(V)) {
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Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
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return V;
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} else if (isa<ConstantAggregateZero>(V)) {
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Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(V->getContext()),0));
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return V;
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} else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
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// If this is an insert of an extract from some other vector, include it.
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Value *VecOp = IEI->getOperand(0);
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Value *ScalarOp = IEI->getOperand(1);
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Value *IdxOp = IEI->getOperand(2);
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if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
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if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
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EI->getOperand(0)->getType() == V->getType()) {
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unsigned ExtractedIdx =
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cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
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unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
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// Either the extracted from or inserted into vector must be RHSVec,
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// otherwise we'd end up with a shuffle of three inputs.
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if (EI->getOperand(0) == RHS || RHS == 0) {
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RHS = EI->getOperand(0);
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Value *V = CollectShuffleElements(VecOp, Mask, RHS);
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Mask[InsertedIdx % NumElts] =
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ConstantInt::get(Type::getInt32Ty(V->getContext()),
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NumElts+ExtractedIdx);
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return V;
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}
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if (VecOp == RHS) {
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Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
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// Everything but the extracted element is replaced with the RHS.
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for (unsigned i = 0; i != NumElts; ++i) {
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if (i != InsertedIdx)
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Mask[i] = ConstantInt::get(Type::getInt32Ty(V->getContext()),
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NumElts+i);
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}
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return V;
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}
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// If this insertelement is a chain that comes from exactly these two
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// vectors, return the vector and the effective shuffle.
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if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
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return EI->getOperand(0);
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}
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}
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}
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// TODO: Handle shufflevector here!
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// Otherwise, can't do anything fancy. Return an identity vector.
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for (unsigned i = 0; i != NumElts; ++i)
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Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
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return V;
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}
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Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
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Value *VecOp = IE.getOperand(0);
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Value *ScalarOp = IE.getOperand(1);
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Value *IdxOp = IE.getOperand(2);
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// Inserting an undef or into an undefined place, remove this.
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if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
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ReplaceInstUsesWith(IE, VecOp);
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// If the inserted element was extracted from some other vector, and if the
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// indexes are constant, try to turn this into a shufflevector operation.
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if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
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if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
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EI->getOperand(0)->getType() == IE.getType()) {
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unsigned NumVectorElts = IE.getType()->getNumElements();
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unsigned ExtractedIdx =
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cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
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unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
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if (ExtractedIdx >= NumVectorElts) // Out of range extract.
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return ReplaceInstUsesWith(IE, VecOp);
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if (InsertedIdx >= NumVectorElts) // Out of range insert.
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return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
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// If we are extracting a value from a vector, then inserting it right
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// back into the same place, just use the input vector.
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if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
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return ReplaceInstUsesWith(IE, VecOp);
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// If this insertelement isn't used by some other insertelement, turn it
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// (and any insertelements it points to), into one big shuffle.
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if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
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std::vector<Constant*> Mask;
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Value *RHS = 0;
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Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
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if (RHS == 0) RHS = UndefValue::get(LHS->getType());
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// We now have a shuffle of LHS, RHS, Mask.
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return new ShuffleVectorInst(LHS, RHS,
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ConstantVector::get(Mask));
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}
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}
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}
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|
|
|
unsigned VWidth = cast<VectorType>(VecOp->getType())->getNumElements();
|
|
APInt UndefElts(VWidth, 0);
|
|
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
|
|
if (SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts))
|
|
return &IE;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
|
|
Value *LHS = SVI.getOperand(0);
|
|
Value *RHS = SVI.getOperand(1);
|
|
std::vector<unsigned> Mask = getShuffleMask(&SVI);
|
|
|
|
bool MadeChange = false;
|
|
|
|
// Undefined shuffle mask -> undefined value.
|
|
if (isa<UndefValue>(SVI.getOperand(2)))
|
|
return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
|
|
|
|
unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
|
|
|
|
if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
|
|
return 0;
|
|
|
|
APInt UndefElts(VWidth, 0);
|
|
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
|
|
if (SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
|
|
LHS = SVI.getOperand(0);
|
|
RHS = SVI.getOperand(1);
|
|
MadeChange = true;
|
|
}
|
|
|
|
// Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
|
|
// Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
|
|
if (LHS == RHS || isa<UndefValue>(LHS)) {
|
|
if (isa<UndefValue>(LHS) && LHS == RHS) {
|
|
// shuffle(undef,undef,mask) -> undef.
|
|
return ReplaceInstUsesWith(SVI, LHS);
|
|
}
|
|
|
|
// Remap any references to RHS to use LHS.
|
|
std::vector<Constant*> Elts;
|
|
for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
|
|
if (Mask[i] >= 2*e)
|
|
Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
|
|
else {
|
|
if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
|
|
(Mask[i] < e && isa<UndefValue>(LHS))) {
|
|
Mask[i] = 2*e; // Turn into undef.
|
|
Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
|
|
} else {
|
|
Mask[i] = Mask[i] % e; // Force to LHS.
|
|
Elts.push_back(ConstantInt::get(Type::getInt32Ty(SVI.getContext()),
|
|
Mask[i]));
|
|
}
|
|
}
|
|
}
|
|
SVI.setOperand(0, SVI.getOperand(1));
|
|
SVI.setOperand(1, UndefValue::get(RHS->getType()));
|
|
SVI.setOperand(2, ConstantVector::get(Elts));
|
|
LHS = SVI.getOperand(0);
|
|
RHS = SVI.getOperand(1);
|
|
MadeChange = true;
|
|
}
|
|
|
|
// Analyze the shuffle, are the LHS or RHS and identity shuffles?
|
|
bool isLHSID = true, isRHSID = true;
|
|
|
|
for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
|
|
if (Mask[i] >= e*2) continue; // Ignore undef values.
|
|
// Is this an identity shuffle of the LHS value?
|
|
isLHSID &= (Mask[i] == i);
|
|
|
|
// Is this an identity shuffle of the RHS value?
|
|
isRHSID &= (Mask[i]-e == i);
|
|
}
|
|
|
|
// Eliminate identity shuffles.
|
|
if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
|
|
if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
|
|
|
|
// If the LHS is a shufflevector itself, see if we can combine it with this
|
|
// one without producing an unusual shuffle. Here we are really conservative:
|
|
// we are absolutely afraid of producing a shuffle mask not in the input
|
|
// program, because the code gen may not be smart enough to turn a merged
|
|
// shuffle into two specific shuffles: it may produce worse code. As such,
|
|
// we only merge two shuffles if the result is one of the two input shuffle
|
|
// masks. In this case, merging the shuffles just removes one instruction,
|
|
// which we know is safe. This is good for things like turning:
|
|
// (splat(splat)) -> splat.
|
|
if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
|
|
if (isa<UndefValue>(RHS)) {
|
|
std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
|
|
|
|
if (LHSMask.size() == Mask.size()) {
|
|
std::vector<unsigned> NewMask;
|
|
for (unsigned i = 0, e = Mask.size(); i != e; ++i)
|
|
if (Mask[i] >= e)
|
|
NewMask.push_back(2*e);
|
|
else
|
|
NewMask.push_back(LHSMask[Mask[i]]);
|
|
|
|
// If the result mask is equal to the src shuffle or this
|
|
// shuffle mask, do the replacement.
|
|
if (NewMask == LHSMask || NewMask == Mask) {
|
|
unsigned LHSInNElts =
|
|
cast<VectorType>(LHSSVI->getOperand(0)->getType())->
|
|
getNumElements();
|
|
std::vector<Constant*> Elts;
|
|
for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
|
|
if (NewMask[i] >= LHSInNElts*2) {
|
|
Elts.push_back(UndefValue::get(
|
|
Type::getInt32Ty(SVI.getContext())));
|
|
} else {
|
|
Elts.push_back(ConstantInt::get(
|
|
Type::getInt32Ty(SVI.getContext()),
|
|
NewMask[i]));
|
|
}
|
|
}
|
|
return new ShuffleVectorInst(LHSSVI->getOperand(0),
|
|
LHSSVI->getOperand(1),
|
|
ConstantVector::get(Elts));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return MadeChange ? &SVI : 0;
|
|
}
|
|
|