1493 lines
59 KiB
C++
1493 lines
59 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 "InstCombineInternal.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Analysis/VectorUtils.h"
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#include "llvm/IR/PatternMatch.h"
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using namespace llvm;
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using namespace PatternMatch;
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#define DEBUG_TYPE "instcombine"
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/// Return true if the value is cheaper to scalarize than it is to leave as a
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/// vector operation. isConstant indicates whether we're extracting one known
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/// element. If false we're extracting a variable index.
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static bool cheapToScalarize(Value *V, bool isConstant) {
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if (Constant *C = dyn_cast<Constant>(V)) {
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if (isConstant) return true;
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// If all elts are the same, we can extract it and use any of the values.
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if (Constant *Op0 = C->getAggregateElement(0U)) {
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for (unsigned i = 1, e = V->getType()->getVectorNumElements(); i != e;
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++i)
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if (C->getAggregateElement(i) != Op0)
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return false;
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return true;
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}
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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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// If we have a PHI node with a vector type that is only used to feed
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// itself and be an operand of extractelement at a constant location,
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// try to replace the PHI of the vector type with a PHI of a scalar type.
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Instruction *InstCombiner::scalarizePHI(ExtractElementInst &EI, PHINode *PN) {
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SmallVector<Instruction *, 2> Extracts;
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// The users we want the PHI to have are:
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// 1) The EI ExtractElement (we already know this)
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// 2) Possibly more ExtractElements with the same index.
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// 3) Another operand, which will feed back into the PHI.
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Instruction *PHIUser = nullptr;
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for (auto U : PN->users()) {
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if (ExtractElementInst *EU = dyn_cast<ExtractElementInst>(U)) {
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if (EI.getIndexOperand() == EU->getIndexOperand())
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Extracts.push_back(EU);
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else
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return nullptr;
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} else if (!PHIUser) {
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PHIUser = cast<Instruction>(U);
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} else {
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return nullptr;
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}
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}
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if (!PHIUser)
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return nullptr;
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// Verify that this PHI user has one use, which is the PHI itself,
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// and that it is a binary operation which is cheap to scalarize.
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// otherwise return NULL.
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if (!PHIUser->hasOneUse() || !(PHIUser->user_back() == PN) ||
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!(isa<BinaryOperator>(PHIUser)) || !cheapToScalarize(PHIUser, true))
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return nullptr;
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// Create a scalar PHI node that will replace the vector PHI node
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// just before the current PHI node.
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PHINode *scalarPHI = cast<PHINode>(InsertNewInstWith(
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PHINode::Create(EI.getType(), PN->getNumIncomingValues(), ""), *PN));
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// Scalarize each PHI operand.
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for (unsigned i = 0; i < PN->getNumIncomingValues(); i++) {
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Value *PHIInVal = PN->getIncomingValue(i);
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BasicBlock *inBB = PN->getIncomingBlock(i);
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Value *Elt = EI.getIndexOperand();
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// If the operand is the PHI induction variable:
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if (PHIInVal == PHIUser) {
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// Scalarize the binary operation. Its first operand is the
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// scalar PHI, and the second operand is extracted from the other
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// vector operand.
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BinaryOperator *B0 = cast<BinaryOperator>(PHIUser);
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unsigned opId = (B0->getOperand(0) == PN) ? 1 : 0;
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Value *Op = InsertNewInstWith(
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ExtractElementInst::Create(B0->getOperand(opId), Elt,
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B0->getOperand(opId)->getName() + ".Elt"),
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*B0);
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Value *newPHIUser = InsertNewInstWith(
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BinaryOperator::CreateWithCopiedFlags(B0->getOpcode(),
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scalarPHI, Op, B0), *B0);
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scalarPHI->addIncoming(newPHIUser, inBB);
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} else {
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// Scalarize PHI input:
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Instruction *newEI = ExtractElementInst::Create(PHIInVal, Elt, "");
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// Insert the new instruction into the predecessor basic block.
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Instruction *pos = dyn_cast<Instruction>(PHIInVal);
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BasicBlock::iterator InsertPos;
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if (pos && !isa<PHINode>(pos)) {
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InsertPos = ++pos->getIterator();
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} else {
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InsertPos = inBB->getFirstInsertionPt();
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}
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InsertNewInstWith(newEI, *InsertPos);
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scalarPHI->addIncoming(newEI, inBB);
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}
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}
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for (auto E : Extracts)
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replaceInstUsesWith(*E, scalarPHI);
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return &EI;
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}
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Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
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if (Value *V = SimplifyExtractElementInst(EI.getVectorOperand(),
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EI.getIndexOperand(),
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SQ.getWithInstruction(&EI)))
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return replaceInstUsesWith(EI, V);
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// If vector val is constant with all elements the same, replace EI with
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// that element. We handle a known element # below.
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if (Constant *C = dyn_cast<Constant>(EI.getOperand(0)))
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if (cheapToScalarize(C, false))
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return replaceInstUsesWith(EI, C->getAggregateElement(0U));
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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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// InstSimplify handles cases where the index is invalid.
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assert(IndexVal < VectorWidth);
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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.setBit(IndexVal);
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if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0), DemandedMask,
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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 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 (VectorType *VT = 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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// If there's a vector PHI feeding a scalar use through this extractelement
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// instruction, try to scalarize the PHI.
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if (PHINode *PN = dyn_cast<PHINode>(EI.getOperand(0))) {
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Instruction *scalarPHI = scalarizePHI(EI, PN);
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if (scalarPHI)
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return scalarPHI;
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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::CreateWithCopiedFlags(BO->getOpcode(),
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newEI0, newEI1, BO);
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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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int SrcIdx = SVI->getMaskValue(Elt->getZExtValue());
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Value *Src;
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unsigned LHSWidth =
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SVI->getOperand(0)->getType()->getVectorNumElements();
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if (SrcIdx < 0)
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return replaceInstUsesWith(EI, UndefValue::get(EI.getType()));
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if (SrcIdx < (int)LHSWidth)
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Src = SVI->getOperand(0);
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else {
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SrcIdx -= LHSWidth;
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Src = SVI->getOperand(1);
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}
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Type *Int32Ty = Type::getInt32Ty(EI.getContext());
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return ExtractElementInst::Create(Src,
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ConstantInt::get(Int32Ty,
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SrcIdx, false));
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}
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} else if (CastInst *CI = dyn_cast<CastInst>(I)) {
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// Canonicalize extractelement(cast) -> cast(extractelement).
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// Bitcasts can change the number of vector elements, and they cost
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// nothing.
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if (CI->hasOneUse() && (CI->getOpcode() != Instruction::BitCast)) {
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Value *EE = Builder.CreateExtractElement(CI->getOperand(0),
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EI.getIndexOperand());
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Worklist.AddValue(EE);
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return CastInst::Create(CI->getOpcode(), EE, EI.getType());
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}
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} else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
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if (SI->hasOneUse()) {
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// TODO: For a select on vectors, it might be useful to do this if it
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// has multiple extractelement uses. For vector select, that seems to
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// fight the vectorizer.
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// If we are extracting an element from a vector select or a select on
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// vectors, create a select on the scalars extracted from the vector
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// arguments.
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Value *TrueVal = SI->getTrueValue();
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Value *FalseVal = SI->getFalseValue();
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Value *Cond = SI->getCondition();
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if (Cond->getType()->isVectorTy()) {
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Cond = Builder.CreateExtractElement(Cond,
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EI.getIndexOperand(),
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Cond->getName() + ".elt");
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}
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Value *V1Elem
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= Builder.CreateExtractElement(TrueVal,
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EI.getIndexOperand(),
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TrueVal->getName() + ".elt");
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Value *V2Elem
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= Builder.CreateExtractElement(FalseVal,
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EI.getIndexOperand(),
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FalseVal->getName() + ".elt");
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return SelectInst::Create(Cond,
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V1Elem,
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V2Elem,
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SI->getName() + ".elt");
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}
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}
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}
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return nullptr;
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}
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/// If V is a shuffle of values that ONLY returns elements from either LHS or
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/// RHS, return the shuffle mask and true. Otherwise, return false.
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static bool collectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
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SmallVectorImpl<Constant*> &Mask) {
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assert(LHS->getType() == RHS->getType() &&
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"Invalid CollectSingleShuffleElements");
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unsigned NumElts = V->getType()->getVectorNumElements();
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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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// We can handle this if the vector we are inserting 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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unsigned ExtractedIdx =
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cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
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unsigned NumLHSElts = LHS->getType()->getVectorNumElements();
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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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// We can handle this if the vector we are inserting 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 + NumLHSElts);
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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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return false;
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}
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/// If we have insertion into a vector that is wider than the vector that we
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/// are extracting from, try to widen the source vector to allow a single
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/// shufflevector to replace one or more insert/extract pairs.
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static void replaceExtractElements(InsertElementInst *InsElt,
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ExtractElementInst *ExtElt,
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InstCombiner &IC) {
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VectorType *InsVecType = InsElt->getType();
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VectorType *ExtVecType = ExtElt->getVectorOperandType();
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unsigned NumInsElts = InsVecType->getVectorNumElements();
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unsigned NumExtElts = ExtVecType->getVectorNumElements();
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// The inserted-to vector must be wider than the extracted-from vector.
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if (InsVecType->getElementType() != ExtVecType->getElementType() ||
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NumExtElts >= NumInsElts)
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return;
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// Create a shuffle mask to widen the extended-from vector using undefined
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// values. The mask selects all of the values of the original vector followed
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// by as many undefined values as needed to create a vector of the same length
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// as the inserted-to vector.
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SmallVector<Constant *, 16> ExtendMask;
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IntegerType *IntType = Type::getInt32Ty(InsElt->getContext());
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for (unsigned i = 0; i < NumExtElts; ++i)
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ExtendMask.push_back(ConstantInt::get(IntType, i));
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for (unsigned i = NumExtElts; i < NumInsElts; ++i)
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ExtendMask.push_back(UndefValue::get(IntType));
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Value *ExtVecOp = ExtElt->getVectorOperand();
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auto *ExtVecOpInst = dyn_cast<Instruction>(ExtVecOp);
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BasicBlock *InsertionBlock = (ExtVecOpInst && !isa<PHINode>(ExtVecOpInst))
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? ExtVecOpInst->getParent()
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: ExtElt->getParent();
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// TODO: This restriction matches the basic block check below when creating
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// new extractelement instructions. If that limitation is removed, this one
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// could also be removed. But for now, we just bail out to ensure that we
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// will replace the extractelement instruction that is feeding our
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// insertelement instruction. This allows the insertelement to then be
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// replaced by a shufflevector. If the insertelement is not replaced, we can
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// induce infinite looping because there's an optimization for extractelement
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// that will delete our widening shuffle. This would trigger another attempt
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// here to create that shuffle, and we spin forever.
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if (InsertionBlock != InsElt->getParent())
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return;
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// TODO: This restriction matches the check in visitInsertElementInst() and
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// prevents an infinite loop caused by not turning the extract/insert pair
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// into a shuffle. We really should not need either check, but we're lacking
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// folds for shufflevectors because we're afraid to generate shuffle masks
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// that the backend can't handle.
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if (InsElt->hasOneUse() && isa<InsertElementInst>(InsElt->user_back()))
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return;
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auto *WideVec = new ShuffleVectorInst(ExtVecOp, UndefValue::get(ExtVecType),
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ConstantVector::get(ExtendMask));
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// Insert the new shuffle after the vector operand of the extract is defined
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// (as long as it's not a PHI) or at the start of the basic block of the
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// extract, so any subsequent extracts in the same basic block can use it.
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// TODO: Insert before the earliest ExtractElementInst that is replaced.
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if (ExtVecOpInst && !isa<PHINode>(ExtVecOpInst))
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WideVec->insertAfter(ExtVecOpInst);
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else
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IC.InsertNewInstWith(WideVec, *ExtElt->getParent()->getFirstInsertionPt());
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// Replace extracts from the original narrow vector with extracts from the new
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// wide vector.
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for (User *U : ExtVecOp->users()) {
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ExtractElementInst *OldExt = dyn_cast<ExtractElementInst>(U);
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if (!OldExt || OldExt->getParent() != WideVec->getParent())
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continue;
|
|
auto *NewExt = ExtractElementInst::Create(WideVec, OldExt->getOperand(1));
|
|
NewExt->insertAfter(OldExt);
|
|
IC.replaceInstUsesWith(*OldExt, NewExt);
|
|
}
|
|
}
|
|
|
|
/// We are building a shuffle to create V, which is a sequence of insertelement,
|
|
/// extractelement pairs. If PermittedRHS is set, then we must either use it or
|
|
/// not rely on the second vector source. Return a std::pair containing the
|
|
/// left and right vectors of the proposed shuffle (or 0), and set the Mask
|
|
/// parameter as required.
|
|
///
|
|
/// Note: we intentionally don't try to fold earlier shuffles since they have
|
|
/// often been chosen carefully to be efficiently implementable on the target.
|
|
typedef std::pair<Value *, Value *> ShuffleOps;
|
|
|
|
static ShuffleOps collectShuffleElements(Value *V,
|
|
SmallVectorImpl<Constant *> &Mask,
|
|
Value *PermittedRHS,
|
|
InstCombiner &IC) {
|
|
assert(V->getType()->isVectorTy() && "Invalid shuffle!");
|
|
unsigned NumElts = V->getType()->getVectorNumElements();
|
|
|
|
if (isa<UndefValue>(V)) {
|
|
Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
|
|
return std::make_pair(
|
|
PermittedRHS ? UndefValue::get(PermittedRHS->getType()) : V, nullptr);
|
|
}
|
|
|
|
if (isa<ConstantAggregateZero>(V)) {
|
|
Mask.assign(NumElts, ConstantInt::get(Type::getInt32Ty(V->getContext()),0));
|
|
return std::make_pair(V, nullptr);
|
|
}
|
|
|
|
if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
|
|
// If this is an insert of an extract from some other vector, include it.
|
|
Value *VecOp = IEI->getOperand(0);
|
|
Value *ScalarOp = IEI->getOperand(1);
|
|
Value *IdxOp = IEI->getOperand(2);
|
|
|
|
if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
|
|
if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp)) {
|
|
unsigned ExtractedIdx =
|
|
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
|
|
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
|
|
|
|
// Either the extracted from or inserted into vector must be RHSVec,
|
|
// otherwise we'd end up with a shuffle of three inputs.
|
|
if (EI->getOperand(0) == PermittedRHS || PermittedRHS == nullptr) {
|
|
Value *RHS = EI->getOperand(0);
|
|
ShuffleOps LR = collectShuffleElements(VecOp, Mask, RHS, IC);
|
|
assert(LR.second == nullptr || LR.second == RHS);
|
|
|
|
if (LR.first->getType() != RHS->getType()) {
|
|
// Although we are giving up for now, see if we can create extracts
|
|
// that match the inserts for another round of combining.
|
|
replaceExtractElements(IEI, EI, IC);
|
|
|
|
// We tried our best, but we can't find anything compatible with RHS
|
|
// further up the chain. Return a trivial shuffle.
|
|
for (unsigned i = 0; i < NumElts; ++i)
|
|
Mask[i] = ConstantInt::get(Type::getInt32Ty(V->getContext()), i);
|
|
return std::make_pair(V, nullptr);
|
|
}
|
|
|
|
unsigned NumLHSElts = RHS->getType()->getVectorNumElements();
|
|
Mask[InsertedIdx % NumElts] =
|
|
ConstantInt::get(Type::getInt32Ty(V->getContext()),
|
|
NumLHSElts+ExtractedIdx);
|
|
return std::make_pair(LR.first, RHS);
|
|
}
|
|
|
|
if (VecOp == PermittedRHS) {
|
|
// We've gone as far as we can: anything on the other side of the
|
|
// extractelement will already have been converted into a shuffle.
|
|
unsigned NumLHSElts =
|
|
EI->getOperand(0)->getType()->getVectorNumElements();
|
|
for (unsigned i = 0; i != NumElts; ++i)
|
|
Mask.push_back(ConstantInt::get(
|
|
Type::getInt32Ty(V->getContext()),
|
|
i == InsertedIdx ? ExtractedIdx : NumLHSElts + i));
|
|
return std::make_pair(EI->getOperand(0), PermittedRHS);
|
|
}
|
|
|
|
// If this insertelement is a chain that comes from exactly these two
|
|
// vectors, return the vector and the effective shuffle.
|
|
if (EI->getOperand(0)->getType() == PermittedRHS->getType() &&
|
|
collectSingleShuffleElements(IEI, EI->getOperand(0), PermittedRHS,
|
|
Mask))
|
|
return std::make_pair(EI->getOperand(0), PermittedRHS);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Otherwise, we can't do anything fancy. Return an identity vector.
|
|
for (unsigned i = 0; i != NumElts; ++i)
|
|
Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
|
|
return std::make_pair(V, nullptr);
|
|
}
|
|
|
|
/// Try to find redundant insertvalue instructions, like the following ones:
|
|
/// %0 = insertvalue { i8, i32 } undef, i8 %x, 0
|
|
/// %1 = insertvalue { i8, i32 } %0, i8 %y, 0
|
|
/// Here the second instruction inserts values at the same indices, as the
|
|
/// first one, making the first one redundant.
|
|
/// It should be transformed to:
|
|
/// %0 = insertvalue { i8, i32 } undef, i8 %y, 0
|
|
Instruction *InstCombiner::visitInsertValueInst(InsertValueInst &I) {
|
|
bool IsRedundant = false;
|
|
ArrayRef<unsigned int> FirstIndices = I.getIndices();
|
|
|
|
// If there is a chain of insertvalue instructions (each of them except the
|
|
// last one has only one use and it's another insertvalue insn from this
|
|
// chain), check if any of the 'children' uses the same indices as the first
|
|
// instruction. In this case, the first one is redundant.
|
|
Value *V = &I;
|
|
unsigned Depth = 0;
|
|
while (V->hasOneUse() && Depth < 10) {
|
|
User *U = V->user_back();
|
|
auto UserInsInst = dyn_cast<InsertValueInst>(U);
|
|
if (!UserInsInst || U->getOperand(0) != V)
|
|
break;
|
|
if (UserInsInst->getIndices() == FirstIndices) {
|
|
IsRedundant = true;
|
|
break;
|
|
}
|
|
V = UserInsInst;
|
|
Depth++;
|
|
}
|
|
|
|
if (IsRedundant)
|
|
return replaceInstUsesWith(I, I.getOperand(0));
|
|
return nullptr;
|
|
}
|
|
|
|
static bool isShuffleEquivalentToSelect(ShuffleVectorInst &Shuf) {
|
|
int MaskSize = Shuf.getMask()->getType()->getVectorNumElements();
|
|
int VecSize = Shuf.getOperand(0)->getType()->getVectorNumElements();
|
|
|
|
// A vector select does not change the size of the operands.
|
|
if (MaskSize != VecSize)
|
|
return false;
|
|
|
|
// Each mask element must be undefined or choose a vector element from one of
|
|
// the source operands without crossing vector lanes.
|
|
for (int i = 0; i != MaskSize; ++i) {
|
|
int Elt = Shuf.getMaskValue(i);
|
|
if (Elt != -1 && Elt != i && Elt != i + VecSize)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
// Turn a chain of inserts that splats a value into a canonical insert + shuffle
|
|
// splat. That is:
|
|
// insertelt(insertelt(insertelt(insertelt X, %k, 0), %k, 1), %k, 2) ... ->
|
|
// shufflevector(insertelt(X, %k, 0), undef, zero)
|
|
static Instruction *foldInsSequenceIntoBroadcast(InsertElementInst &InsElt) {
|
|
// We are interested in the last insert in a chain. So, if this insert
|
|
// has a single user, and that user is an insert, bail.
|
|
if (InsElt.hasOneUse() && isa<InsertElementInst>(InsElt.user_back()))
|
|
return nullptr;
|
|
|
|
VectorType *VT = cast<VectorType>(InsElt.getType());
|
|
int NumElements = VT->getNumElements();
|
|
|
|
// Do not try to do this for a one-element vector, since that's a nop,
|
|
// and will cause an inf-loop.
|
|
if (NumElements == 1)
|
|
return nullptr;
|
|
|
|
Value *SplatVal = InsElt.getOperand(1);
|
|
InsertElementInst *CurrIE = &InsElt;
|
|
SmallVector<bool, 16> ElementPresent(NumElements, false);
|
|
|
|
// Walk the chain backwards, keeping track of which indices we inserted into,
|
|
// until we hit something that isn't an insert of the splatted value.
|
|
while (CurrIE) {
|
|
ConstantInt *Idx = dyn_cast<ConstantInt>(CurrIE->getOperand(2));
|
|
if (!Idx || CurrIE->getOperand(1) != SplatVal)
|
|
return nullptr;
|
|
|
|
// Check none of the intermediate steps have any additional uses.
|
|
if ((CurrIE != &InsElt) && !CurrIE->hasOneUse())
|
|
return nullptr;
|
|
|
|
ElementPresent[Idx->getZExtValue()] = true;
|
|
CurrIE = dyn_cast<InsertElementInst>(CurrIE->getOperand(0));
|
|
}
|
|
|
|
// Make sure we've seen an insert into every element.
|
|
if (llvm::any_of(ElementPresent, [](bool Present) { return !Present; }))
|
|
return nullptr;
|
|
|
|
// All right, create the insert + shuffle.
|
|
Instruction *InsertFirst = InsertElementInst::Create(
|
|
UndefValue::get(VT), SplatVal,
|
|
ConstantInt::get(Type::getInt32Ty(InsElt.getContext()), 0), "", &InsElt);
|
|
|
|
Constant *ZeroMask = ConstantAggregateZero::get(
|
|
VectorType::get(Type::getInt32Ty(InsElt.getContext()), NumElements));
|
|
|
|
return new ShuffleVectorInst(InsertFirst, UndefValue::get(VT), ZeroMask);
|
|
}
|
|
|
|
/// If we have an insertelement instruction feeding into another insertelement
|
|
/// and the 2nd is inserting a constant into the vector, canonicalize that
|
|
/// constant insertion before the insertion of a variable:
|
|
///
|
|
/// insertelement (insertelement X, Y, IdxC1), ScalarC, IdxC2 -->
|
|
/// insertelement (insertelement X, ScalarC, IdxC2), Y, IdxC1
|
|
///
|
|
/// This has the potential of eliminating the 2nd insertelement instruction
|
|
/// via constant folding of the scalar constant into a vector constant.
|
|
static Instruction *hoistInsEltConst(InsertElementInst &InsElt2,
|
|
InstCombiner::BuilderTy &Builder) {
|
|
auto *InsElt1 = dyn_cast<InsertElementInst>(InsElt2.getOperand(0));
|
|
if (!InsElt1 || !InsElt1->hasOneUse())
|
|
return nullptr;
|
|
|
|
Value *X, *Y;
|
|
Constant *ScalarC;
|
|
ConstantInt *IdxC1, *IdxC2;
|
|
if (match(InsElt1->getOperand(0), m_Value(X)) &&
|
|
match(InsElt1->getOperand(1), m_Value(Y)) && !isa<Constant>(Y) &&
|
|
match(InsElt1->getOperand(2), m_ConstantInt(IdxC1)) &&
|
|
match(InsElt2.getOperand(1), m_Constant(ScalarC)) &&
|
|
match(InsElt2.getOperand(2), m_ConstantInt(IdxC2)) && IdxC1 != IdxC2) {
|
|
Value *NewInsElt1 = Builder.CreateInsertElement(X, ScalarC, IdxC2);
|
|
return InsertElementInst::Create(NewInsElt1, Y, IdxC1);
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// insertelt (shufflevector X, CVec, Mask|insertelt X, C1, CIndex1), C, CIndex
|
|
/// --> shufflevector X, CVec', Mask'
|
|
static Instruction *foldConstantInsEltIntoShuffle(InsertElementInst &InsElt) {
|
|
auto *Inst = dyn_cast<Instruction>(InsElt.getOperand(0));
|
|
// Bail out if the parent has more than one use. In that case, we'd be
|
|
// replacing the insertelt with a shuffle, and that's not a clear win.
|
|
if (!Inst || !Inst->hasOneUse())
|
|
return nullptr;
|
|
if (auto *Shuf = dyn_cast<ShuffleVectorInst>(InsElt.getOperand(0))) {
|
|
// The shuffle must have a constant vector operand. The insertelt must have
|
|
// a constant scalar being inserted at a constant position in the vector.
|
|
Constant *ShufConstVec, *InsEltScalar;
|
|
uint64_t InsEltIndex;
|
|
if (!match(Shuf->getOperand(1), m_Constant(ShufConstVec)) ||
|
|
!match(InsElt.getOperand(1), m_Constant(InsEltScalar)) ||
|
|
!match(InsElt.getOperand(2), m_ConstantInt(InsEltIndex)))
|
|
return nullptr;
|
|
|
|
// Adding an element to an arbitrary shuffle could be expensive, but a
|
|
// shuffle that selects elements from vectors without crossing lanes is
|
|
// assumed cheap.
|
|
// If we're just adding a constant into that shuffle, it will still be
|
|
// cheap.
|
|
if (!isShuffleEquivalentToSelect(*Shuf))
|
|
return nullptr;
|
|
|
|
// From the above 'select' check, we know that the mask has the same number
|
|
// of elements as the vector input operands. We also know that each constant
|
|
// input element is used in its lane and can not be used more than once by
|
|
// the shuffle. Therefore, replace the constant in the shuffle's constant
|
|
// vector with the insertelt constant. Replace the constant in the shuffle's
|
|
// mask vector with the insertelt index plus the length of the vector
|
|
// (because the constant vector operand of a shuffle is always the 2nd
|
|
// operand).
|
|
Constant *Mask = Shuf->getMask();
|
|
unsigned NumElts = Mask->getType()->getVectorNumElements();
|
|
SmallVector<Constant *, 16> NewShufElts(NumElts);
|
|
SmallVector<Constant *, 16> NewMaskElts(NumElts);
|
|
for (unsigned I = 0; I != NumElts; ++I) {
|
|
if (I == InsEltIndex) {
|
|
NewShufElts[I] = InsEltScalar;
|
|
Type *Int32Ty = Type::getInt32Ty(Shuf->getContext());
|
|
NewMaskElts[I] = ConstantInt::get(Int32Ty, InsEltIndex + NumElts);
|
|
} else {
|
|
// Copy over the existing values.
|
|
NewShufElts[I] = ShufConstVec->getAggregateElement(I);
|
|
NewMaskElts[I] = Mask->getAggregateElement(I);
|
|
}
|
|
}
|
|
|
|
// Create new operands for a shuffle that includes the constant of the
|
|
// original insertelt. The old shuffle will be dead now.
|
|
return new ShuffleVectorInst(Shuf->getOperand(0),
|
|
ConstantVector::get(NewShufElts),
|
|
ConstantVector::get(NewMaskElts));
|
|
} else if (auto *IEI = dyn_cast<InsertElementInst>(Inst)) {
|
|
// Transform sequences of insertelements ops with constant data/indexes into
|
|
// a single shuffle op.
|
|
unsigned NumElts = InsElt.getType()->getNumElements();
|
|
|
|
uint64_t InsertIdx[2];
|
|
Constant *Val[2];
|
|
if (!match(InsElt.getOperand(2), m_ConstantInt(InsertIdx[0])) ||
|
|
!match(InsElt.getOperand(1), m_Constant(Val[0])) ||
|
|
!match(IEI->getOperand(2), m_ConstantInt(InsertIdx[1])) ||
|
|
!match(IEI->getOperand(1), m_Constant(Val[1])))
|
|
return nullptr;
|
|
SmallVector<Constant *, 16> Values(NumElts);
|
|
SmallVector<Constant *, 16> Mask(NumElts);
|
|
auto ValI = std::begin(Val);
|
|
// Generate new constant vector and mask.
|
|
// We have 2 values/masks from the insertelements instructions. Insert them
|
|
// into new value/mask vectors.
|
|
for (uint64_t I : InsertIdx) {
|
|
if (!Values[I]) {
|
|
assert(!Mask[I]);
|
|
Values[I] = *ValI;
|
|
Mask[I] = ConstantInt::get(Type::getInt32Ty(InsElt.getContext()),
|
|
NumElts + I);
|
|
}
|
|
++ValI;
|
|
}
|
|
// Remaining values are filled with 'undef' values.
|
|
for (unsigned I = 0; I < NumElts; ++I) {
|
|
if (!Values[I]) {
|
|
assert(!Mask[I]);
|
|
Values[I] = UndefValue::get(InsElt.getType()->getElementType());
|
|
Mask[I] = ConstantInt::get(Type::getInt32Ty(InsElt.getContext()), I);
|
|
}
|
|
}
|
|
// Create new operands for a shuffle that includes the constant of the
|
|
// original insertelt.
|
|
return new ShuffleVectorInst(IEI->getOperand(0),
|
|
ConstantVector::get(Values),
|
|
ConstantVector::get(Mask));
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
|
|
Value *VecOp = IE.getOperand(0);
|
|
Value *ScalarOp = IE.getOperand(1);
|
|
Value *IdxOp = IE.getOperand(2);
|
|
|
|
// Inserting an undef or into an undefined place, remove this.
|
|
if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
|
|
replaceInstUsesWith(IE, VecOp);
|
|
|
|
// If the inserted element was extracted from some other vector, and if the
|
|
// indexes are constant, try to turn this into a shufflevector operation.
|
|
if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
|
|
if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp)) {
|
|
unsigned NumInsertVectorElts = IE.getType()->getNumElements();
|
|
unsigned NumExtractVectorElts =
|
|
EI->getOperand(0)->getType()->getVectorNumElements();
|
|
unsigned ExtractedIdx =
|
|
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
|
|
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
|
|
|
|
if (ExtractedIdx >= NumExtractVectorElts) // Out of range extract.
|
|
return replaceInstUsesWith(IE, VecOp);
|
|
|
|
if (InsertedIdx >= NumInsertVectorElts) // Out of range insert.
|
|
return replaceInstUsesWith(IE, UndefValue::get(IE.getType()));
|
|
|
|
// If we are extracting a value from a vector, then inserting it right
|
|
// back into the same place, just use the input vector.
|
|
if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
|
|
return replaceInstUsesWith(IE, VecOp);
|
|
|
|
// If this insertelement isn't used by some other insertelement, turn it
|
|
// (and any insertelements it points to), into one big shuffle.
|
|
if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.user_back())) {
|
|
SmallVector<Constant*, 16> Mask;
|
|
ShuffleOps LR = collectShuffleElements(&IE, Mask, nullptr, *this);
|
|
|
|
// The proposed shuffle may be trivial, in which case we shouldn't
|
|
// perform the combine.
|
|
if (LR.first != &IE && LR.second != &IE) {
|
|
// We now have a shuffle of LHS, RHS, Mask.
|
|
if (LR.second == nullptr)
|
|
LR.second = UndefValue::get(LR.first->getType());
|
|
return new ShuffleVectorInst(LR.first, LR.second,
|
|
ConstantVector::get(Mask));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
unsigned VWidth = VecOp->getType()->getVectorNumElements();
|
|
APInt UndefElts(VWidth, 0);
|
|
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
|
|
if (Value *V = SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts)) {
|
|
if (V != &IE)
|
|
return replaceInstUsesWith(IE, V);
|
|
return &IE;
|
|
}
|
|
|
|
if (Instruction *Shuf = foldConstantInsEltIntoShuffle(IE))
|
|
return Shuf;
|
|
|
|
if (Instruction *NewInsElt = hoistInsEltConst(IE, Builder))
|
|
return NewInsElt;
|
|
|
|
// Turn a sequence of inserts that broadcasts a scalar into a single
|
|
// insert + shufflevector.
|
|
if (Instruction *Broadcast = foldInsSequenceIntoBroadcast(IE))
|
|
return Broadcast;
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// Return true if we can evaluate the specified expression tree if the vector
|
|
/// elements were shuffled in a different order.
|
|
static bool CanEvaluateShuffled(Value *V, ArrayRef<int> Mask,
|
|
unsigned Depth = 5) {
|
|
// We can always reorder the elements of a constant.
|
|
if (isa<Constant>(V))
|
|
return true;
|
|
|
|
// We won't reorder vector arguments. No IPO here.
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I) return false;
|
|
|
|
// Two users may expect different orders of the elements. Don't try it.
|
|
if (!I->hasOneUse())
|
|
return false;
|
|
|
|
if (Depth == 0) return false;
|
|
|
|
switch (I->getOpcode()) {
|
|
case Instruction::Add:
|
|
case Instruction::FAdd:
|
|
case Instruction::Sub:
|
|
case Instruction::FSub:
|
|
case Instruction::Mul:
|
|
case Instruction::FMul:
|
|
case Instruction::UDiv:
|
|
case Instruction::SDiv:
|
|
case Instruction::FDiv:
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
case Instruction::FRem:
|
|
case Instruction::Shl:
|
|
case Instruction::LShr:
|
|
case Instruction::AShr:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
case Instruction::ICmp:
|
|
case Instruction::FCmp:
|
|
case Instruction::Trunc:
|
|
case Instruction::ZExt:
|
|
case Instruction::SExt:
|
|
case Instruction::FPToUI:
|
|
case Instruction::FPToSI:
|
|
case Instruction::UIToFP:
|
|
case Instruction::SIToFP:
|
|
case Instruction::FPTrunc:
|
|
case Instruction::FPExt:
|
|
case Instruction::GetElementPtr: {
|
|
for (Value *Operand : I->operands()) {
|
|
if (!CanEvaluateShuffled(Operand, Mask, Depth-1))
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
case Instruction::InsertElement: {
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(2));
|
|
if (!CI) return false;
|
|
int ElementNumber = CI->getLimitedValue();
|
|
|
|
// Verify that 'CI' does not occur twice in Mask. A single 'insertelement'
|
|
// can't put an element into multiple indices.
|
|
bool SeenOnce = false;
|
|
for (int i = 0, e = Mask.size(); i != e; ++i) {
|
|
if (Mask[i] == ElementNumber) {
|
|
if (SeenOnce)
|
|
return false;
|
|
SeenOnce = true;
|
|
}
|
|
}
|
|
return CanEvaluateShuffled(I->getOperand(0), Mask, Depth-1);
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// Rebuild a new instruction just like 'I' but with the new operands given.
|
|
/// In the event of type mismatch, the type of the operands is correct.
|
|
static Value *buildNew(Instruction *I, ArrayRef<Value*> NewOps) {
|
|
// We don't want to use the IRBuilder here because we want the replacement
|
|
// instructions to appear next to 'I', not the builder's insertion point.
|
|
switch (I->getOpcode()) {
|
|
case Instruction::Add:
|
|
case Instruction::FAdd:
|
|
case Instruction::Sub:
|
|
case Instruction::FSub:
|
|
case Instruction::Mul:
|
|
case Instruction::FMul:
|
|
case Instruction::UDiv:
|
|
case Instruction::SDiv:
|
|
case Instruction::FDiv:
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
case Instruction::FRem:
|
|
case Instruction::Shl:
|
|
case Instruction::LShr:
|
|
case Instruction::AShr:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor: {
|
|
BinaryOperator *BO = cast<BinaryOperator>(I);
|
|
assert(NewOps.size() == 2 && "binary operator with #ops != 2");
|
|
BinaryOperator *New =
|
|
BinaryOperator::Create(cast<BinaryOperator>(I)->getOpcode(),
|
|
NewOps[0], NewOps[1], "", BO);
|
|
if (isa<OverflowingBinaryOperator>(BO)) {
|
|
New->setHasNoUnsignedWrap(BO->hasNoUnsignedWrap());
|
|
New->setHasNoSignedWrap(BO->hasNoSignedWrap());
|
|
}
|
|
if (isa<PossiblyExactOperator>(BO)) {
|
|
New->setIsExact(BO->isExact());
|
|
}
|
|
if (isa<FPMathOperator>(BO))
|
|
New->copyFastMathFlags(I);
|
|
return New;
|
|
}
|
|
case Instruction::ICmp:
|
|
assert(NewOps.size() == 2 && "icmp with #ops != 2");
|
|
return new ICmpInst(I, cast<ICmpInst>(I)->getPredicate(),
|
|
NewOps[0], NewOps[1]);
|
|
case Instruction::FCmp:
|
|
assert(NewOps.size() == 2 && "fcmp with #ops != 2");
|
|
return new FCmpInst(I, cast<FCmpInst>(I)->getPredicate(),
|
|
NewOps[0], NewOps[1]);
|
|
case Instruction::Trunc:
|
|
case Instruction::ZExt:
|
|
case Instruction::SExt:
|
|
case Instruction::FPToUI:
|
|
case Instruction::FPToSI:
|
|
case Instruction::UIToFP:
|
|
case Instruction::SIToFP:
|
|
case Instruction::FPTrunc:
|
|
case Instruction::FPExt: {
|
|
// It's possible that the mask has a different number of elements from
|
|
// the original cast. We recompute the destination type to match the mask.
|
|
Type *DestTy =
|
|
VectorType::get(I->getType()->getScalarType(),
|
|
NewOps[0]->getType()->getVectorNumElements());
|
|
assert(NewOps.size() == 1 && "cast with #ops != 1");
|
|
return CastInst::Create(cast<CastInst>(I)->getOpcode(), NewOps[0], DestTy,
|
|
"", I);
|
|
}
|
|
case Instruction::GetElementPtr: {
|
|
Value *Ptr = NewOps[0];
|
|
ArrayRef<Value*> Idx = NewOps.slice(1);
|
|
GetElementPtrInst *GEP = GetElementPtrInst::Create(
|
|
cast<GetElementPtrInst>(I)->getSourceElementType(), Ptr, Idx, "", I);
|
|
GEP->setIsInBounds(cast<GetElementPtrInst>(I)->isInBounds());
|
|
return GEP;
|
|
}
|
|
}
|
|
llvm_unreachable("failed to rebuild vector instructions");
|
|
}
|
|
|
|
Value *
|
|
InstCombiner::EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask) {
|
|
// Mask.size() does not need to be equal to the number of vector elements.
|
|
|
|
assert(V->getType()->isVectorTy() && "can't reorder non-vector elements");
|
|
if (isa<UndefValue>(V)) {
|
|
return UndefValue::get(VectorType::get(V->getType()->getScalarType(),
|
|
Mask.size()));
|
|
}
|
|
if (isa<ConstantAggregateZero>(V)) {
|
|
return ConstantAggregateZero::get(
|
|
VectorType::get(V->getType()->getScalarType(),
|
|
Mask.size()));
|
|
}
|
|
if (Constant *C = dyn_cast<Constant>(V)) {
|
|
SmallVector<Constant *, 16> MaskValues;
|
|
for (int i = 0, e = Mask.size(); i != e; ++i) {
|
|
if (Mask[i] == -1)
|
|
MaskValues.push_back(UndefValue::get(Builder.getInt32Ty()));
|
|
else
|
|
MaskValues.push_back(Builder.getInt32(Mask[i]));
|
|
}
|
|
return ConstantExpr::getShuffleVector(C, UndefValue::get(C->getType()),
|
|
ConstantVector::get(MaskValues));
|
|
}
|
|
|
|
Instruction *I = cast<Instruction>(V);
|
|
switch (I->getOpcode()) {
|
|
case Instruction::Add:
|
|
case Instruction::FAdd:
|
|
case Instruction::Sub:
|
|
case Instruction::FSub:
|
|
case Instruction::Mul:
|
|
case Instruction::FMul:
|
|
case Instruction::UDiv:
|
|
case Instruction::SDiv:
|
|
case Instruction::FDiv:
|
|
case Instruction::URem:
|
|
case Instruction::SRem:
|
|
case Instruction::FRem:
|
|
case Instruction::Shl:
|
|
case Instruction::LShr:
|
|
case Instruction::AShr:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
case Instruction::ICmp:
|
|
case Instruction::FCmp:
|
|
case Instruction::Trunc:
|
|
case Instruction::ZExt:
|
|
case Instruction::SExt:
|
|
case Instruction::FPToUI:
|
|
case Instruction::FPToSI:
|
|
case Instruction::UIToFP:
|
|
case Instruction::SIToFP:
|
|
case Instruction::FPTrunc:
|
|
case Instruction::FPExt:
|
|
case Instruction::Select:
|
|
case Instruction::GetElementPtr: {
|
|
SmallVector<Value*, 8> NewOps;
|
|
bool NeedsRebuild = (Mask.size() != I->getType()->getVectorNumElements());
|
|
for (int i = 0, e = I->getNumOperands(); i != e; ++i) {
|
|
Value *V = EvaluateInDifferentElementOrder(I->getOperand(i), Mask);
|
|
NewOps.push_back(V);
|
|
NeedsRebuild |= (V != I->getOperand(i));
|
|
}
|
|
if (NeedsRebuild) {
|
|
return buildNew(I, NewOps);
|
|
}
|
|
return I;
|
|
}
|
|
case Instruction::InsertElement: {
|
|
int Element = cast<ConstantInt>(I->getOperand(2))->getLimitedValue();
|
|
|
|
// The insertelement was inserting at Element. Figure out which element
|
|
// that becomes after shuffling. The answer is guaranteed to be unique
|
|
// by CanEvaluateShuffled.
|
|
bool Found = false;
|
|
int Index = 0;
|
|
for (int e = Mask.size(); Index != e; ++Index) {
|
|
if (Mask[Index] == Element) {
|
|
Found = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If element is not in Mask, no need to handle the operand 1 (element to
|
|
// be inserted). Just evaluate values in operand 0 according to Mask.
|
|
if (!Found)
|
|
return EvaluateInDifferentElementOrder(I->getOperand(0), Mask);
|
|
|
|
Value *V = EvaluateInDifferentElementOrder(I->getOperand(0), Mask);
|
|
return InsertElementInst::Create(V, I->getOperand(1),
|
|
Builder.getInt32(Index), "", I);
|
|
}
|
|
}
|
|
llvm_unreachable("failed to reorder elements of vector instruction!");
|
|
}
|
|
|
|
static void recognizeIdentityMask(const SmallVectorImpl<int> &Mask,
|
|
bool &isLHSID, bool &isRHSID) {
|
|
isLHSID = isRHSID = true;
|
|
|
|
for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
|
|
if (Mask[i] < 0) continue; // Ignore undef values.
|
|
// Is this an identity shuffle of the LHS value?
|
|
isLHSID &= (Mask[i] == (int)i);
|
|
|
|
// Is this an identity shuffle of the RHS value?
|
|
isRHSID &= (Mask[i]-e == i);
|
|
}
|
|
}
|
|
|
|
// Returns true if the shuffle is extracting a contiguous range of values from
|
|
// LHS, for example:
|
|
// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|
|
// Input: |AA|BB|CC|DD|EE|FF|GG|HH|II|JJ|KK|LL|MM|NN|OO|PP|
|
|
// Shuffles to: |EE|FF|GG|HH|
|
|
// +--+--+--+--+
|
|
static bool isShuffleExtractingFromLHS(ShuffleVectorInst &SVI,
|
|
SmallVector<int, 16> &Mask) {
|
|
unsigned LHSElems = SVI.getOperand(0)->getType()->getVectorNumElements();
|
|
unsigned MaskElems = Mask.size();
|
|
unsigned BegIdx = Mask.front();
|
|
unsigned EndIdx = Mask.back();
|
|
if (BegIdx > EndIdx || EndIdx >= LHSElems || EndIdx - BegIdx != MaskElems - 1)
|
|
return false;
|
|
for (unsigned I = 0; I != MaskElems; ++I)
|
|
if (static_cast<unsigned>(Mask[I]) != BegIdx + I)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
|
|
Value *LHS = SVI.getOperand(0);
|
|
Value *RHS = SVI.getOperand(1);
|
|
SmallVector<int, 16> Mask = SVI.getShuffleMask();
|
|
Type *Int32Ty = Type::getInt32Ty(SVI.getContext());
|
|
|
|
if (auto *V = SimplifyShuffleVectorInst(
|
|
LHS, RHS, SVI.getMask(), SVI.getType(), SQ.getWithInstruction(&SVI)))
|
|
return replaceInstUsesWith(SVI, V);
|
|
|
|
bool MadeChange = false;
|
|
unsigned VWidth = SVI.getType()->getVectorNumElements();
|
|
|
|
APInt UndefElts(VWidth, 0);
|
|
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
|
|
if (Value *V = SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
|
|
if (V != &SVI)
|
|
return replaceInstUsesWith(SVI, V);
|
|
LHS = SVI.getOperand(0);
|
|
RHS = SVI.getOperand(1);
|
|
MadeChange = true;
|
|
}
|
|
|
|
unsigned LHSWidth = LHS->getType()->getVectorNumElements();
|
|
|
|
// 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.
|
|
Value *Result = (VWidth == LHSWidth)
|
|
? LHS : UndefValue::get(SVI.getType());
|
|
return replaceInstUsesWith(SVI, Result);
|
|
}
|
|
|
|
// Remap any references to RHS to use LHS.
|
|
SmallVector<Constant*, 16> Elts;
|
|
for (unsigned i = 0, e = LHSWidth; i != VWidth; ++i) {
|
|
if (Mask[i] < 0) {
|
|
Elts.push_back(UndefValue::get(Int32Ty));
|
|
continue;
|
|
}
|
|
|
|
if ((Mask[i] >= (int)e && isa<UndefValue>(RHS)) ||
|
|
(Mask[i] < (int)e && isa<UndefValue>(LHS))) {
|
|
Mask[i] = -1; // Turn into undef.
|
|
Elts.push_back(UndefValue::get(Int32Ty));
|
|
} else {
|
|
Mask[i] = Mask[i] % e; // Force to LHS.
|
|
Elts.push_back(ConstantInt::get(Int32Ty, 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;
|
|
}
|
|
|
|
if (VWidth == LHSWidth) {
|
|
// Analyze the shuffle, are the LHS or RHS and identity shuffles?
|
|
bool isLHSID, isRHSID;
|
|
recognizeIdentityMask(Mask, isLHSID, isRHSID);
|
|
|
|
// Eliminate identity shuffles.
|
|
if (isLHSID) return replaceInstUsesWith(SVI, LHS);
|
|
if (isRHSID) return replaceInstUsesWith(SVI, RHS);
|
|
}
|
|
|
|
if (isa<UndefValue>(RHS) && CanEvaluateShuffled(LHS, Mask)) {
|
|
Value *V = EvaluateInDifferentElementOrder(LHS, Mask);
|
|
return replaceInstUsesWith(SVI, V);
|
|
}
|
|
|
|
// SROA generates shuffle+bitcast when the extracted sub-vector is bitcast to
|
|
// a non-vector type. We can instead bitcast the original vector followed by
|
|
// an extract of the desired element:
|
|
//
|
|
// %sroa = shufflevector <16 x i8> %in, <16 x i8> undef,
|
|
// <4 x i32> <i32 0, i32 1, i32 2, i32 3>
|
|
// %1 = bitcast <4 x i8> %sroa to i32
|
|
// Becomes:
|
|
// %bc = bitcast <16 x i8> %in to <4 x i32>
|
|
// %ext = extractelement <4 x i32> %bc, i32 0
|
|
//
|
|
// If the shuffle is extracting a contiguous range of values from the input
|
|
// vector then each use which is a bitcast of the extracted size can be
|
|
// replaced. This will work if the vector types are compatible, and the begin
|
|
// index is aligned to a value in the casted vector type. If the begin index
|
|
// isn't aligned then we can shuffle the original vector (keeping the same
|
|
// vector type) before extracting.
|
|
//
|
|
// This code will bail out if the target type is fundamentally incompatible
|
|
// with vectors of the source type.
|
|
//
|
|
// Example of <16 x i8>, target type i32:
|
|
// Index range [4,8): v-----------v Will work.
|
|
// +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|
|
// <16 x i8>: | | | | | | | | | | | | | | | | |
|
|
// <4 x i32>: | | | | |
|
|
// +-----------+-----------+-----------+-----------+
|
|
// Index range [6,10): ^-----------^ Needs an extra shuffle.
|
|
// Target type i40: ^--------------^ Won't work, bail.
|
|
if (isShuffleExtractingFromLHS(SVI, Mask)) {
|
|
Value *V = LHS;
|
|
unsigned MaskElems = Mask.size();
|
|
VectorType *SrcTy = cast<VectorType>(V->getType());
|
|
unsigned VecBitWidth = SrcTy->getBitWidth();
|
|
unsigned SrcElemBitWidth = DL.getTypeSizeInBits(SrcTy->getElementType());
|
|
assert(SrcElemBitWidth && "vector elements must have a bitwidth");
|
|
unsigned SrcNumElems = SrcTy->getNumElements();
|
|
SmallVector<BitCastInst *, 8> BCs;
|
|
DenseMap<Type *, Value *> NewBCs;
|
|
for (User *U : SVI.users())
|
|
if (BitCastInst *BC = dyn_cast<BitCastInst>(U))
|
|
if (!BC->use_empty())
|
|
// Only visit bitcasts that weren't previously handled.
|
|
BCs.push_back(BC);
|
|
for (BitCastInst *BC : BCs) {
|
|
unsigned BegIdx = Mask.front();
|
|
Type *TgtTy = BC->getDestTy();
|
|
unsigned TgtElemBitWidth = DL.getTypeSizeInBits(TgtTy);
|
|
if (!TgtElemBitWidth)
|
|
continue;
|
|
unsigned TgtNumElems = VecBitWidth / TgtElemBitWidth;
|
|
bool VecBitWidthsEqual = VecBitWidth == TgtNumElems * TgtElemBitWidth;
|
|
bool BegIsAligned = 0 == ((SrcElemBitWidth * BegIdx) % TgtElemBitWidth);
|
|
if (!VecBitWidthsEqual)
|
|
continue;
|
|
if (!VectorType::isValidElementType(TgtTy))
|
|
continue;
|
|
VectorType *CastSrcTy = VectorType::get(TgtTy, TgtNumElems);
|
|
if (!BegIsAligned) {
|
|
// Shuffle the input so [0,NumElements) contains the output, and
|
|
// [NumElems,SrcNumElems) is undef.
|
|
SmallVector<Constant *, 16> ShuffleMask(SrcNumElems,
|
|
UndefValue::get(Int32Ty));
|
|
for (unsigned I = 0, E = MaskElems, Idx = BegIdx; I != E; ++Idx, ++I)
|
|
ShuffleMask[I] = ConstantInt::get(Int32Ty, Idx);
|
|
V = Builder.CreateShuffleVector(V, UndefValue::get(V->getType()),
|
|
ConstantVector::get(ShuffleMask),
|
|
SVI.getName() + ".extract");
|
|
BegIdx = 0;
|
|
}
|
|
unsigned SrcElemsPerTgtElem = TgtElemBitWidth / SrcElemBitWidth;
|
|
assert(SrcElemsPerTgtElem);
|
|
BegIdx /= SrcElemsPerTgtElem;
|
|
bool BCAlreadyExists = NewBCs.find(CastSrcTy) != NewBCs.end();
|
|
auto *NewBC =
|
|
BCAlreadyExists
|
|
? NewBCs[CastSrcTy]
|
|
: Builder.CreateBitCast(V, CastSrcTy, SVI.getName() + ".bc");
|
|
if (!BCAlreadyExists)
|
|
NewBCs[CastSrcTy] = NewBC;
|
|
auto *Ext = Builder.CreateExtractElement(
|
|
NewBC, ConstantInt::get(Int32Ty, BegIdx), SVI.getName() + ".extract");
|
|
// The shufflevector isn't being replaced: the bitcast that used it
|
|
// is. InstCombine will visit the newly-created instructions.
|
|
replaceInstUsesWith(*BC, Ext);
|
|
MadeChange = true;
|
|
}
|
|
}
|
|
|
|
// If the LHS is a shufflevector itself, see if we can combine it with this
|
|
// one without producing an unusual shuffle.
|
|
// Cases that might be simplified:
|
|
// 1.
|
|
// x1=shuffle(v1,v2,mask1)
|
|
// x=shuffle(x1,undef,mask)
|
|
// ==>
|
|
// x=shuffle(v1,undef,newMask)
|
|
// newMask[i] = (mask[i] < x1.size()) ? mask1[mask[i]] : -1
|
|
// 2.
|
|
// x1=shuffle(v1,undef,mask1)
|
|
// x=shuffle(x1,x2,mask)
|
|
// where v1.size() == mask1.size()
|
|
// ==>
|
|
// x=shuffle(v1,x2,newMask)
|
|
// newMask[i] = (mask[i] < x1.size()) ? mask1[mask[i]] : mask[i]
|
|
// 3.
|
|
// x2=shuffle(v2,undef,mask2)
|
|
// x=shuffle(x1,x2,mask)
|
|
// where v2.size() == mask2.size()
|
|
// ==>
|
|
// x=shuffle(x1,v2,newMask)
|
|
// newMask[i] = (mask[i] < x1.size())
|
|
// ? mask[i] : mask2[mask[i]-x1.size()]+x1.size()
|
|
// 4.
|
|
// x1=shuffle(v1,undef,mask1)
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// x2=shuffle(v2,undef,mask2)
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// x=shuffle(x1,x2,mask)
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// where v1.size() == v2.size()
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// ==>
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// x=shuffle(v1,v2,newMask)
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// newMask[i] = (mask[i] < x1.size())
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// ? mask1[mask[i]] : mask2[mask[i]-x1.size()]+v1.size()
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//
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// Here we are really conservative:
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// we are absolutely afraid of producing a shuffle mask not in the input
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// program, because the code gen may not be smart enough to turn a merged
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// shuffle into two specific shuffles: it may produce worse code. As such,
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// we only merge two shuffles if the result is either a splat or one of the
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// input shuffle masks. In this case, merging the shuffles just removes
|
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// one instruction, which we know is safe. This is good for things like
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// turning: (splat(splat)) -> splat, or
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// merge(V[0..n], V[n+1..2n]) -> V[0..2n]
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ShuffleVectorInst* LHSShuffle = dyn_cast<ShuffleVectorInst>(LHS);
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ShuffleVectorInst* RHSShuffle = dyn_cast<ShuffleVectorInst>(RHS);
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if (LHSShuffle)
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if (!isa<UndefValue>(LHSShuffle->getOperand(1)) && !isa<UndefValue>(RHS))
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|
LHSShuffle = nullptr;
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|
if (RHSShuffle)
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|
if (!isa<UndefValue>(RHSShuffle->getOperand(1)))
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|
RHSShuffle = nullptr;
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if (!LHSShuffle && !RHSShuffle)
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return MadeChange ? &SVI : nullptr;
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|
|
|
Value* LHSOp0 = nullptr;
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Value* LHSOp1 = nullptr;
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Value* RHSOp0 = nullptr;
|
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unsigned LHSOp0Width = 0;
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unsigned RHSOp0Width = 0;
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if (LHSShuffle) {
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|
LHSOp0 = LHSShuffle->getOperand(0);
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LHSOp1 = LHSShuffle->getOperand(1);
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|
LHSOp0Width = LHSOp0->getType()->getVectorNumElements();
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|
}
|
|
if (RHSShuffle) {
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|
RHSOp0 = RHSShuffle->getOperand(0);
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|
RHSOp0Width = RHSOp0->getType()->getVectorNumElements();
|
|
}
|
|
Value* newLHS = LHS;
|
|
Value* newRHS = RHS;
|
|
if (LHSShuffle) {
|
|
// case 1
|
|
if (isa<UndefValue>(RHS)) {
|
|
newLHS = LHSOp0;
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|
newRHS = LHSOp1;
|
|
}
|
|
// case 2 or 4
|
|
else if (LHSOp0Width == LHSWidth) {
|
|
newLHS = LHSOp0;
|
|
}
|
|
}
|
|
// case 3 or 4
|
|
if (RHSShuffle && RHSOp0Width == LHSWidth) {
|
|
newRHS = RHSOp0;
|
|
}
|
|
// case 4
|
|
if (LHSOp0 == RHSOp0) {
|
|
newLHS = LHSOp0;
|
|
newRHS = nullptr;
|
|
}
|
|
|
|
if (newLHS == LHS && newRHS == RHS)
|
|
return MadeChange ? &SVI : nullptr;
|
|
|
|
SmallVector<int, 16> LHSMask;
|
|
SmallVector<int, 16> RHSMask;
|
|
if (newLHS != LHS)
|
|
LHSMask = LHSShuffle->getShuffleMask();
|
|
if (RHSShuffle && newRHS != RHS)
|
|
RHSMask = RHSShuffle->getShuffleMask();
|
|
|
|
unsigned newLHSWidth = (newLHS != LHS) ? LHSOp0Width : LHSWidth;
|
|
SmallVector<int, 16> newMask;
|
|
bool isSplat = true;
|
|
int SplatElt = -1;
|
|
// Create a new mask for the new ShuffleVectorInst so that the new
|
|
// ShuffleVectorInst is equivalent to the original one.
|
|
for (unsigned i = 0; i < VWidth; ++i) {
|
|
int eltMask;
|
|
if (Mask[i] < 0) {
|
|
// This element is an undef value.
|
|
eltMask = -1;
|
|
} else if (Mask[i] < (int)LHSWidth) {
|
|
// This element is from left hand side vector operand.
|
|
//
|
|
// If LHS is going to be replaced (case 1, 2, or 4), calculate the
|
|
// new mask value for the element.
|
|
if (newLHS != LHS) {
|
|
eltMask = LHSMask[Mask[i]];
|
|
// If the value selected is an undef value, explicitly specify it
|
|
// with a -1 mask value.
|
|
if (eltMask >= (int)LHSOp0Width && isa<UndefValue>(LHSOp1))
|
|
eltMask = -1;
|
|
} else
|
|
eltMask = Mask[i];
|
|
} else {
|
|
// This element is from right hand side vector operand
|
|
//
|
|
// If the value selected is an undef value, explicitly specify it
|
|
// with a -1 mask value. (case 1)
|
|
if (isa<UndefValue>(RHS))
|
|
eltMask = -1;
|
|
// If RHS is going to be replaced (case 3 or 4), calculate the
|
|
// new mask value for the element.
|
|
else if (newRHS != RHS) {
|
|
eltMask = RHSMask[Mask[i]-LHSWidth];
|
|
// If the value selected is an undef value, explicitly specify it
|
|
// with a -1 mask value.
|
|
if (eltMask >= (int)RHSOp0Width) {
|
|
assert(isa<UndefValue>(RHSShuffle->getOperand(1))
|
|
&& "should have been check above");
|
|
eltMask = -1;
|
|
}
|
|
} else
|
|
eltMask = Mask[i]-LHSWidth;
|
|
|
|
// If LHS's width is changed, shift the mask value accordingly.
|
|
// If newRHS == NULL, i.e. LHSOp0 == RHSOp0, we want to remap any
|
|
// references from RHSOp0 to LHSOp0, so we don't need to shift the mask.
|
|
// If newRHS == newLHS, we want to remap any references from newRHS to
|
|
// newLHS so that we can properly identify splats that may occur due to
|
|
// obfuscation across the two vectors.
|
|
if (eltMask >= 0 && newRHS != nullptr && newLHS != newRHS)
|
|
eltMask += newLHSWidth;
|
|
}
|
|
|
|
// Check if this could still be a splat.
|
|
if (eltMask >= 0) {
|
|
if (SplatElt >= 0 && SplatElt != eltMask)
|
|
isSplat = false;
|
|
SplatElt = eltMask;
|
|
}
|
|
|
|
newMask.push_back(eltMask);
|
|
}
|
|
|
|
// If the result mask is equal to one of the original shuffle masks,
|
|
// or is a splat, do the replacement.
|
|
if (isSplat || newMask == LHSMask || newMask == RHSMask || newMask == Mask) {
|
|
SmallVector<Constant*, 16> Elts;
|
|
for (unsigned i = 0, e = newMask.size(); i != e; ++i) {
|
|
if (newMask[i] < 0) {
|
|
Elts.push_back(UndefValue::get(Int32Ty));
|
|
} else {
|
|
Elts.push_back(ConstantInt::get(Int32Ty, newMask[i]));
|
|
}
|
|
}
|
|
if (!newRHS)
|
|
newRHS = UndefValue::get(newLHS->getType());
|
|
return new ShuffleVectorInst(newLHS, newRHS, ConstantVector::get(Elts));
|
|
}
|
|
|
|
// If the result mask is an identity, replace uses of this instruction with
|
|
// corresponding argument.
|
|
bool isLHSID, isRHSID;
|
|
recognizeIdentityMask(newMask, isLHSID, isRHSID);
|
|
if (isLHSID && VWidth == LHSOp0Width) return replaceInstUsesWith(SVI, newLHS);
|
|
if (isRHSID && VWidth == RHSOp0Width) return replaceInstUsesWith(SVI, newRHS);
|
|
|
|
return MadeChange ? &SVI : nullptr;
|
|
}
|