Add a loop vectorizer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166112 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/PassManagerBuilder.cpp b/lib/Transforms/IPO/PassManagerBuilder.cpp
index a286202..97698ca 100644
--- a/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -176,6 +176,12 @@
MPM.add(createIndVarSimplifyPass()); // Canonicalize indvars
MPM.add(createLoopIdiomPass()); // Recognize idioms like memset.
MPM.add(createLoopDeletionPass()); // Delete dead loops
+
+ if (Vectorize) {
+ MPM.add(createLoopVectorizePass());
+ MPM.add(createLICMPass());
+ }
+
if (!DisableUnrollLoops)
MPM.add(createLoopUnrollPass()); // Unroll small loops
addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
diff --git a/lib/Transforms/Vectorize/CMakeLists.txt b/lib/Transforms/Vectorize/CMakeLists.txt
index 06cf1e4..e64034a 100644
--- a/lib/Transforms/Vectorize/CMakeLists.txt
+++ b/lib/Transforms/Vectorize/CMakeLists.txt
@@ -1,6 +1,7 @@
add_llvm_library(LLVMVectorize
BBVectorize.cpp
Vectorize.cpp
+ LoopVectorize.cpp
)
add_dependencies(LLVMVectorize intrinsics_gen)
diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
new file mode 100644
index 0000000..60405e7
--- /dev/null
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -0,0 +1,801 @@
+//===- LoopVectorize.cpp - A Loop Vectorizer ------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This is a simple loop vectorizer. We currently only support single block
+// loops. We have a very simple and restrictive legality check: we need to read
+// and write from disjoint memory locations. We still don't have a cost model.
+// This pass has three parts:
+// 1. The main loop pass that drives the different parts.
+// 2. LoopVectorizationLegality - A helper class that checks for the legality
+// of the vectorization.
+// 3. SingleBlockLoopVectorizer - A helper class that performs the actual
+// widening of instructions.
+//
+//===----------------------------------------------------------------------===//
+#define LV_NAME "loop-vectorize"
+#define DEBUG_TYPE LV_NAME
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Pass.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Value.h"
+#include "llvm/Function.h"
+#include "llvm/Module.h"
+#include "llvm/Type.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/AliasSetTracker.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/DataLayout.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include <algorithm>
+using namespace llvm;
+
+static cl::opt<unsigned>
+DefaultVectorizationFactor("default-loop-vectorize-width",
+ cl::init(4), cl::Hidden,
+ cl::desc("Set the default loop vectorization width"));
+
+namespace {
+
+/// Vectorize a simple loop. This class performs the widening of simple single
+/// basic block loops into vectors. It does not perform any
+/// vectorization-legality checks, and just does it. It widens the vectors
+/// to a given vectorization factor (VF).
+class SingleBlockLoopVectorizer {
+public:
+
+ /// Ctor.
+ SingleBlockLoopVectorizer(Loop *OrigLoop, ScalarEvolution *Se, LoopInfo *Li,
+ unsigned VecWidth):
+ Orig(OrigLoop), SE(Se), LI(Li), VF(VecWidth),
+ Builder(0), Induction(0), OldInduction(0) { }
+
+ ~SingleBlockLoopVectorizer() {
+ delete Builder;
+ }
+
+ // Perform the actual loop widening (vectorization).
+ void vectorize() {
+ ///Create a new empty loop. Unlink the old loop and connect the new one.
+ copyEmptyLoop();
+ /// Widen each instruction in the old loop to a new one in the new loop.
+ vectorizeLoop();
+ // Delete the old loop.
+ deleteOldLoop();
+ }
+
+private:
+ /// Create an empty loop, based on the loop ranges of the old loop.
+ void copyEmptyLoop();
+ /// Copy and widen the instructions from the old loop.
+ void vectorizeLoop();
+ /// Delete the old loop.
+ void deleteOldLoop();
+
+ /// This instruction is un-vectorizable. Implement it as a sequence
+ /// of scalars.
+ void scalarizeInstruction(Instruction *Instr);
+
+ /// Create a broadcast instruction. This method generates a broadcast
+ /// instruction (shuffle) for loop invariant values and for the induction
+ /// value. If this is the induction variable then we extend it to N, N+1, ...
+ /// this is needed because each iteration in the loop corresponds to a SIMD
+ /// element.
+ Value *getBroadcastInstrs(Value *V);
+
+ /// This is a helper function used by getBroadcastInstrs. It adds 0, 1, 2 ..
+ /// for each element in the vector. Starting from zero.
+ Value *getConsecutiveVector(Value* Val);
+
+ /// Check that the GEP operands are all uniform except for the last index
+ /// which has to be the induction variable.
+ bool isConsecutiveGep(GetElementPtrInst *Gep);
+
+ /// When we go over instructions in the basic block we rely on previous
+ /// values within the current basic block or on loop invariant values.
+ /// When we widen (vectorize) values we place them in the map. If the values
+ /// are not within the map, they have to be loop invariant, so we simply
+ /// broadcast them into a vector.
+ Value *getVectorValue(Value *V);
+
+ /// The original loop.
+ Loop *Orig;
+ // Scev analysis to use.
+ ScalarEvolution *SE;
+ // Loop Info.
+ LoopInfo *LI;
+ // The vectorization factor to use.
+ unsigned VF;
+
+ // The builder that we use
+ IRBuilder<> *Builder;
+
+ // --- Vectorization state ---
+
+ /// The new Induction variable which was added to the new block.
+ Instruction *Induction;
+ /// The induction variable of the old basic block.
+ Instruction *OldInduction;
+ // Maps scalars to widened vectors.
+ DenseMap<Value*, Value*> WidenMap;
+};
+
+
+/// Perform the vectorization legality check. This class does not look at the
+/// profitability of vectorization, only the legality. At the moment the checks
+/// are very simple and focus on single basic block loops with a constant
+/// iteration count and no reductions.
+class LoopVectorizationLegality {
+public:
+ LoopVectorizationLegality(Loop *Lp, ScalarEvolution *Se, DataLayout *Dl):
+ TheLoop(Lp), SE(Se), DL(Dl) { }
+
+ /// Returns the maximum vectorization factor that we *can* use to vectorize
+ /// this loop. This does not mean that it is profitable to vectorize this
+ /// loop, only that it is legal to do so. This may be a large number. We
+ /// can vectorize to any SIMD width below this number.
+ unsigned getLoopMaxVF();
+
+private:
+ /// Check if a single basic block loop is vectorizable.
+ /// At this point we know that this is a loop with a constant trip count
+ /// and we only need to check individual instructions.
+ bool canVectorizeBlock(BasicBlock &BB);
+
+ // Check if a pointer value is known to be disjoint.
+ // Example: Alloca, Global, NoAlias.
+ bool isKnownDisjoint(Value* Val);
+
+ /// The loop that we evaluate.
+ Loop *TheLoop;
+ /// Scev analysis.
+ ScalarEvolution *SE;
+ /// DataLayout analysis.
+ DataLayout *DL;
+};
+
+struct LoopVectorize : public LoopPass {
+ static char ID; // Pass identification, replacement for typeid
+
+ LoopVectorize() : LoopPass(ID) {
+ initializeLoopVectorizePass(*PassRegistry::getPassRegistry());
+ }
+
+ AliasAnalysis *AA;
+ ScalarEvolution *SE;
+ DataLayout *DL;
+ LoopInfo *LI;
+
+ virtual bool runOnLoop(Loop *L, LPPassManager &LPM) {
+ // Only vectorize innermost loops.
+ if (!L->empty())
+ return false;
+
+ AA = &getAnalysis<AliasAnalysis>();
+ SE = &getAnalysis<ScalarEvolution>();
+ DL = getAnalysisIfAvailable<DataLayout>();
+ LI = &getAnalysis<LoopInfo>();
+
+ BasicBlock *Header = L->getHeader();
+ DEBUG(dbgs() << "LV: Checking a loop in \"" <<
+ Header->getParent()->getName() << "\"\n");
+
+ // Check if it is legal to vectorize the loop.
+ LoopVectorizationLegality LVL(L, SE, DL);
+ unsigned MaxVF = LVL.getLoopMaxVF();
+
+ // Check that we can vectorize using the chosen vectorization width.
+ if ((MaxVF < DefaultVectorizationFactor) ||
+ (MaxVF % DefaultVectorizationFactor)) {
+ DEBUG(dbgs() << "LV: non-vectorizable MaxVF ("<< MaxVF << ").\n");
+ return false;
+ }
+
+ DEBUG(dbgs() << "LV: Found a vectorizable loop ("<< MaxVF << ").\n");
+
+ // If we decided that is is *legal* to vectorizer the loop. Do it.
+ SingleBlockLoopVectorizer LB(L, SE, LI, DefaultVectorizationFactor);
+ LB.vectorize();
+
+ // The loop is now vectorized. Remove it from LMP.
+ LPM.deleteLoopFromQueue(L);
+ return true;
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ LoopPass::getAnalysisUsage(AU);
+ AU.addRequiredID(LoopSimplifyID);
+ AU.addRequired<AliasAnalysis>();
+ AU.addRequired<LoopInfo>();
+ AU.addRequired<ScalarEvolution>();
+ }
+
+};
+
+Value *SingleBlockLoopVectorizer::getBroadcastInstrs(Value *V) {
+ // Instructions that access the old induction variable
+ // actually want to get the new one.
+ if (V == OldInduction)
+ V = Induction;
+ // Create the types.
+ LLVMContext &C = V->getContext();
+ Type *VTy = VectorType::get(V->getType(), VF);
+ Type *I32 = IntegerType::getInt32Ty(C);
+ Constant *Zero = ConstantInt::get(I32, 0);
+ Value *Zeros = ConstantAggregateZero::get(VectorType::get(I32, VF));
+ Value *UndefVal = UndefValue::get(VTy);
+ // Insert the value into a new vector.
+ Value *SingleElem = Builder->CreateInsertElement(UndefVal, V, Zero);
+ // Broadcast the scalar into all locations in the vector.
+ Value *Shuf = Builder->CreateShuffleVector(SingleElem, UndefVal, Zeros,
+ "broadcast");
+ // We are accessing the induction variable. Make sure to promote the
+ // index for each consecutive SIMD lane. This adds 0,1,2 ... to all lanes.
+ if (V == Induction)
+ return getConsecutiveVector(Shuf);
+ return Shuf;
+}
+
+Value *SingleBlockLoopVectorizer::getConsecutiveVector(Value* Val) {
+ assert(Val->getType()->isVectorTy() && "Must be a vector");
+ assert(Val->getType()->getScalarType()->isIntegerTy() &&
+ "Elem must be an integer");
+ // Create the types.
+ Type *ITy = Val->getType()->getScalarType();
+ VectorType *Ty = cast<VectorType>(Val->getType());
+ unsigned VLen = Ty->getNumElements();
+ SmallVector<Constant*, 8> Indices;
+
+ // Create a vector of consecutive numbers from zero to VF.
+ for (unsigned i = 0; i < VLen; ++i)
+ Indices.push_back(ConstantInt::get(ITy, i));
+
+ // Add the consecutive indices to the vector value.
+ Constant *Cv = ConstantVector::get(Indices);
+ assert(Cv->getType() == Val->getType() && "Invalid consecutive vec");
+ return Builder->CreateAdd(Val, Cv, "induction");
+}
+
+
+bool SingleBlockLoopVectorizer::isConsecutiveGep(GetElementPtrInst *Gep) {
+ if (!Gep)
+ return false;
+
+ unsigned NumOperands = Gep->getNumOperands();
+ Value *LastIndex = Gep->getOperand(NumOperands - 1);
+
+ // Check that all of the gep indices are uniform except for the last.
+ for (unsigned i = 0; i < NumOperands - 1; ++i)
+ if (!SE->isLoopInvariant(SE->getSCEV(Gep->getOperand(i)), Orig))
+ return false;
+
+ // The last operand has to be the induction in order to emit
+ // a wide load/store.
+ const SCEV *Last = SE->getSCEV(LastIndex);
+ if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Last)) {
+ const SCEV *Step = AR->getStepRecurrence(*SE);
+
+ // The memory is consecutive because the last index is consecutive
+ // and all other indices are loop invariant.
+ if (Step->isOne())
+ return true;
+ }
+
+ return false;
+}
+
+Value *SingleBlockLoopVectorizer::getVectorValue(Value *V) {
+ if (WidenMap.count(V))
+ return WidenMap[V];
+ return getBroadcastInstrs(V);
+}
+
+void SingleBlockLoopVectorizer::scalarizeInstruction(Instruction *Instr) {
+ assert(!Instr->getType()->isAggregateType() && "Can't handle vectors");
+ // Holds vector parameters or scalars, in case of uniform vals.
+ SmallVector<Value*, 8> Params;
+
+ // Find all of the vectorized parameters.
+ for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) {
+ Value *SrcOp = Instr->getOperand(op);
+
+ // If we are accessing the old induction variable, use the new one.
+ if (SrcOp == OldInduction) {
+ Params.push_back(getBroadcastInstrs(Induction));
+ continue;
+ }
+
+ // Try using previously calculated values.
+ Instruction *SrcInst = dyn_cast<Instruction>(SrcOp);
+
+ // If the src is an instruction that appeared earlier in the basic block
+ // then it should already be vectorized.
+ if (SrcInst && SrcInst->getParent() == Instr->getParent()) {
+ assert(WidenMap.count(SrcInst) && "Source operand is unavailable");
+ // The parameter is a vector value from earlier.
+ Params.push_back(WidenMap[SrcInst]);
+ } else {
+ // The parameter is a scalar from outside the loop. Maybe even a constant.
+ Params.push_back(SrcOp);
+ }
+ }
+
+ assert(Params.size() == Instr->getNumOperands() &&
+ "Invalid number of operands");
+
+ // Does this instruction return a value ?
+ bool IsVoidRetTy = Instr->getType()->isVoidTy();
+ Value *VecResults = 0;
+
+ // If we have a return value, create an empty vector. We place the scalarized
+ // instructions in this vector.
+ if (!IsVoidRetTy)
+ VecResults = UndefValue::get(VectorType::get(Instr->getType(), VF));
+
+ // For each scalar that we create.
+ for (unsigned i = 0; i < VF; ++i) {
+ Instruction *Cloned = Instr->clone();
+ if (!IsVoidRetTy)
+ Cloned->setName(Instr->getName() + ".cloned");
+ // Replace the operands of the cloned instrucions with extracted scalars.
+ for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) {
+ Value *Op = Params[op];
+ // Param is a vector. Need to extract the right lane.
+ if (Op->getType()->isVectorTy())
+ Op = Builder->CreateExtractElement(Op, Builder->getInt32(i));
+ Cloned->setOperand(op, Op);
+ }
+
+ // Place the clonsed scalar in the new loop.
+ Builder->Insert(Cloned);
+
+ // If the original scalar returns a value we need to place it in a vector
+ // so that future users will be able to use it.
+ if (!IsVoidRetTy)
+ VecResults = Builder->CreateInsertElement(VecResults, Cloned,
+ Builder->getInt32(i));
+ }
+
+ if (!IsVoidRetTy)
+ WidenMap[Instr] = VecResults;
+}
+
+void SingleBlockLoopVectorizer::copyEmptyLoop() {
+ assert(Orig->getNumBlocks() == 1 && "Invalid loop");
+ BasicBlock *PH = Orig->getLoopPreheader();
+ BasicBlock *ExitBlock = Orig->getExitBlock();
+ assert(ExitBlock && "Invalid loop exit");
+
+ // Create a new single-basic block loop.
+ BasicBlock *BB = BasicBlock::Create(PH->getContext(), "vectorizedloop",
+ PH->getParent(), ExitBlock);
+
+ // Find the induction variable.
+ BasicBlock *OldBasicBlock = Orig->getHeader();
+ PHINode *OldInd = dyn_cast<PHINode>(OldBasicBlock->begin());
+ assert(OldInd && "We must have a single phi node.");
+ Type *IdxTy = OldInd->getType();
+
+ // Use this IR builder to create the loop instructions (Phi, Br, Cmp)
+ // inside the loop.
+ Builder = new IRBuilder<>(BB);
+ Builder->SetInsertPoint(BB);
+
+ // Generate the induction variable.
+ PHINode *Phi = Builder->CreatePHI(IdxTy, 2, "index");
+ Constant *Zero = ConstantInt::get(IdxTy, 0);
+ Constant *Step = ConstantInt::get(IdxTy, VF);
+
+ // Find the loop boundaries.
+ const SCEV *ExitCount = SE->getExitCount(Orig, Orig->getHeader());
+ assert(ExitCount != SE->getCouldNotCompute() && "Invalid loop count");
+
+ // Get the trip count from the count by adding 1.
+ ExitCount = SE->getAddExpr(ExitCount,
+ SE->getConstant(ExitCount->getType(), 1));
+
+ // Expand the trip count and place the new instructions in the preheader.
+ // Notice that the pre-header does not change, only the loop body.
+ SCEVExpander Exp(*SE, "induction");
+ Instruction *Loc = Orig->getLoopPreheader()->getTerminator();
+ if (ExitCount->getType() != Phi->getType())
+ ExitCount = SE->getSignExtendExpr(ExitCount, Phi->getType());
+ Value *Count = Exp.expandCodeFor(ExitCount, Phi->getType(), Loc);
+
+ // Create i+1 and fill the PHINode.
+ Value *Next = Builder->CreateAdd(Phi, Step, "index.next");
+ Phi->addIncoming(Zero, PH);
+ Phi->addIncoming(Next, BB);
+ // Create the compare.
+ Value *ICmp = Builder->CreateICmpEQ(Next, Count);
+ Builder->CreateCondBr(ICmp, ExitBlock, BB);
+ // Fix preheader.
+ PH->getTerminator()->setSuccessor(0, BB);
+ Builder->SetInsertPoint(BB->getFirstInsertionPt());
+
+ // Save the indiction variables.
+ Induction = Phi;
+ OldInduction = OldInd;
+}
+
+void SingleBlockLoopVectorizer::vectorizeLoop() {
+ BasicBlock &BB = *Orig->getHeader();
+
+ // For each instruction in the old loop.
+ for (BasicBlock::iterator it = BB.begin(), e = BB.end(); it != e; ++it) {
+ Instruction *Inst = it;
+
+ switch (Inst->getOpcode()) {
+ case Instruction::PHI:
+ case Instruction::Br:
+ // Nothing to do for PHIs and BR, since we already took care of the
+ // loop control flow instructions.
+ continue;
+
+ 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: {
+ // Just widen binops.
+ BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);
+ Value *A = getVectorValue(Inst->getOperand(0));
+ Value *B = getVectorValue(Inst->getOperand(1));
+ // Use this vector value for all users of the original instruction.
+ WidenMap[Inst] = Builder->CreateBinOp(BinOp->getOpcode(), A, B);
+ break;
+ }
+ case Instruction::Select: {
+ // Widen selects.
+ Value *A = getVectorValue(Inst->getOperand(0));
+ Value *B = getVectorValue(Inst->getOperand(1));
+ Value *C = getVectorValue(Inst->getOperand(2));
+ WidenMap[Inst] = Builder->CreateSelect(A, B, C);
+ break;
+ }
+
+ case Instruction::ICmp:
+ case Instruction::FCmp: {
+ // Widen compares. Generate vector compares.
+ bool FCmp = (Inst->getOpcode() == Instruction::FCmp);
+ CmpInst *Cmp = dyn_cast<CmpInst>(Inst);
+ Value *A = getVectorValue(Inst->getOperand(0));
+ Value *B = getVectorValue(Inst->getOperand(1));
+ if (FCmp)
+ WidenMap[Inst] = Builder->CreateFCmp(Cmp->getPredicate(), A, B);
+ else
+ WidenMap[Inst] = Builder->CreateICmp(Cmp->getPredicate(), A, B);
+ break;
+ }
+
+ case Instruction::Store: {
+ // Attempt to issue a wide store.
+ StoreInst *SI = dyn_cast<StoreInst>(Inst);
+ Type *StTy = VectorType::get(SI->getValueOperand()->getType(), VF);
+ Value *Ptr = SI->getPointerOperand();
+ unsigned Alignment = SI->getAlignment();
+ GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr);
+ // This store does not use GEPs.
+ if (!isConsecutiveGep(Gep)) {
+ scalarizeInstruction(Inst);
+ break;
+ }
+
+ // Create the new GEP with the new induction variable.
+ GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
+ unsigned NumOperands = Gep->getNumOperands();
+ Gep2->setOperand(NumOperands - 1, Induction);
+ Ptr = Builder->Insert(Gep2);
+ Ptr = Builder->CreateBitCast(Ptr, StTy->getPointerTo());
+ Value *Val = getVectorValue(SI->getValueOperand());
+ Builder->CreateStore(Val, Ptr)->setAlignment(Alignment);
+ break;
+ }
+ case Instruction::Load: {
+ // Attempt to issue a wide load.
+ LoadInst *LI = dyn_cast<LoadInst>(Inst);
+ Type *RetTy = VectorType::get(LI->getType(), VF);
+ Value *Ptr = LI->getPointerOperand();
+ unsigned Alignment = LI->getAlignment();
+ GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr);
+
+ // We don't have a gep. Scalarize the load.
+ if (!isConsecutiveGep(Gep)) {
+ scalarizeInstruction(Inst);
+ break;
+ }
+
+ // Create the new GEP with the new induction variable.
+ GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
+ unsigned NumOperands = Gep->getNumOperands();
+ Gep2->setOperand(NumOperands - 1, Induction);
+ Ptr = Builder->Insert(Gep2);
+ Ptr = Builder->CreateBitCast(Ptr, RetTy->getPointerTo());
+ LI = Builder->CreateLoad(Ptr);
+ LI->setAlignment(Alignment);
+ // Use this vector value for all users of the load.
+ WidenMap[Inst] = LI;
+ break;
+ }
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::FPExt:
+ case Instruction::PtrToInt:
+ case Instruction::IntToPtr:
+ case Instruction::SIToFP:
+ case Instruction::UIToFP:
+ case Instruction::Trunc:
+ case Instruction::FPTrunc:
+ case Instruction::BitCast: {
+ /// Vectorize bitcasts.
+ CastInst *CI = dyn_cast<CastInst>(Inst);
+ Value *A = getVectorValue(Inst->getOperand(0));
+ Type *DestTy = VectorType::get(CI->getType()->getScalarType(), VF);
+ WidenMap[Inst] = Builder->CreateCast(CI->getOpcode(), A, DestTy);
+ break;
+ }
+
+ default:
+ /// All other instructions are unsupported. Scalarize them.
+ scalarizeInstruction(Inst);
+ break;
+ }// end of switch.
+ }// end of for_each instr.
+}
+
+void SingleBlockLoopVectorizer::deleteOldLoop() {
+ // The original basic block.
+ BasicBlock *BB = Orig->getHeader();
+ SE->forgetLoop(Orig);
+
+ LI->removeBlock(BB);
+ Orig->addBasicBlockToLoop(Induction->getParent(), LI->getBase());
+
+ // Remove the old loop block.
+ DeleteDeadBlock(BB);
+}
+
+unsigned LoopVectorizationLegality::getLoopMaxVF() {
+ if (!TheLoop->getLoopPreheader()) {
+ assert(false && "No preheader!!");
+ DEBUG(dbgs() << "LV: Loop not normalized." << "\n");
+ return 1;
+ }
+
+ // We can only vectorize single basic block loops.
+ unsigned NumBlocks = TheLoop->getNumBlocks();
+ if (NumBlocks != 1) {
+ DEBUG(dbgs() << "LV: Too many blocks:" << NumBlocks << "\n");
+ return 1;
+ }
+
+ // We need to have a loop header.
+ BasicBlock *BB = TheLoop->getHeader();
+ DEBUG(dbgs() << "LV: Found a loop: " << BB->getName() << "\n");
+
+ // Find the max vectorization factor.
+ unsigned MaxVF = SE->getSmallConstantTripMultiple(TheLoop, BB);
+
+
+ // Perform an early check. Do not scan the block if we did not find a loop.
+ if (MaxVF < 2) {
+ DEBUG(dbgs() << "LV: Can't find a vectorizable loop structure\n");
+ return 1;
+ }
+
+ // Go over each instruction and look at memory deps.
+ if (!canVectorizeBlock(*BB)) {
+ DEBUG(dbgs() << "LV: Can't vectorize this loop header\n");
+ return 1;
+ }
+
+ DEBUG(dbgs() << "LV: We can vectorize this loop! VF="<<MaxVF<<"\n");
+
+ // Okay! We can vectorize. Return the max trip multiple.
+ return MaxVF;
+}
+
+bool LoopVectorizationLegality::canVectorizeBlock(BasicBlock &BB) {
+ // Holds the read and write pointers that we find.
+ typedef SmallVector<Value*, 10> ValueVector;
+ ValueVector Reads;
+ ValueVector Writes;
+
+ unsigned NumPhis = 0;
+ for (BasicBlock::iterator it = BB.begin(), e = BB.end(); it != e; ++it) {
+ Instruction *I = it;
+
+ PHINode *Phi = dyn_cast<PHINode>(I);
+ if (Phi) {
+ NumPhis++;
+ // We only look at integer phi nodes.
+ if (!Phi->getType()->isIntegerTy()) {
+ DEBUG(dbgs() << "LV: Found an non-int PHI.\n");
+ return false;
+ }
+
+ // If we found an induction variable.
+ if (NumPhis > 1) {
+ DEBUG(dbgs() << "LV: Found more than one PHI.\n");
+ return false;
+ }
+
+ // This should not happen because the loop should be normalized.
+ if (Phi->getNumIncomingValues() != 2) {
+ DEBUG(dbgs() << "LV: Found an invalid PHI.\n");
+ return false;
+ }
+
+ // Check that the PHI is consecutive and starts at zero.
+ const SCEV *PhiScev = SE->getSCEV(Phi);
+ const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PhiScev);
+ if (!AR) {
+ DEBUG(dbgs() << "LV: PHI is not a poly recurrence.\n");
+ return false;
+ }
+
+ const SCEV *Step = AR->getStepRecurrence(*SE);
+ const SCEV *Start = AR->getStart();
+
+ if (!Step->isOne() || !Start->isZero()) {
+ DEBUG(dbgs() << "LV: PHI does not start at zero or steps by one.\n");
+ return false;
+ }
+ }
+
+ // IF this is a load, record its pointer. If it is not a load, abort.
+ // Notice that we don't handle function calls that read or write.
+ if (I->mayReadFromMemory()) {
+ LoadInst *Ld = dyn_cast<LoadInst>(I);
+ if (!Ld) return false;
+ if (!Ld->isSimple()) {
+ DEBUG(dbgs() << "LV: Found a non-simple load.\n");
+ return false;
+ }
+ GetUnderlyingObjects(Ld->getPointerOperand(), Reads, DL);
+ }
+
+ // Record store pointers. Abort on all other instructions that write to
+ // memory.
+ if (I->mayWriteToMemory()) {
+ StoreInst *St = dyn_cast<StoreInst>(I);
+ if (!St) return false;
+ if (!St->isSimple()) {
+ DEBUG(dbgs() << "LV: Found a non-simple store.\n");
+ return false;
+ }
+ GetUnderlyingObjects(St->getPointerOperand(), Writes, DL);
+ }
+
+ // We still don't handle functions.
+ CallInst *CI = dyn_cast<CallInst>(I);
+ if (CI) {
+ DEBUG(dbgs() << "LV: Found a call site:"<<
+ CI->getCalledFunction()->getName() << "\n");
+ return false;
+ }
+
+ // We do not re-vectorize vectors.
+ if (!VectorType::isValidElementType(I->getType()) &&
+ !I->getType()->isVoidTy()) {
+ DEBUG(dbgs() << "LV: Found unvectorizable type." << "\n");
+ return false;
+ }
+ //Check that all of the users of the loop are inside the BB.
+ for (Value::use_iterator it = I->use_begin(), e = I->use_end();
+ it != e; ++it) {
+ Instruction *U = cast<Instruction>(*it);
+ BasicBlock *Parent = U->getParent();
+ if (Parent != &BB) {
+ DEBUG(dbgs() << "LV: Found an outside user for : "<< *U << "\n");
+ return false;
+ }
+ }
+ } // next instr.
+
+ // Check that the underlying objects of the reads and writes are either
+ // disjoint memory locations, or that they are no-alias arguments.
+ ValueVector::iterator r, re, w, we;
+ for (r = Reads.begin(), re = Reads.end(); r != re; ++r) {
+ if (!isKnownDisjoint(*r)) {
+ DEBUG(dbgs() << "LV: Found a bad read Ptr: "<< **r << "\n");
+ return false;
+ }
+ }
+
+ for (w = Writes.begin(), we = Writes.end(); w != we; ++w) {
+ if (!isKnownDisjoint(*w)) {
+ DEBUG(dbgs() << "LV: Found a bad write Ptr: "<< **w << "\n");
+ return false;
+ }
+ }
+
+ // Check that there are no multiple write locations to the same pointer.
+ SmallPtrSet<Value*, 8> BasePointers;
+ for (w = Writes.begin(), we = Writes.end(); w != we; ++w) {
+ if (BasePointers.count(*w)) {
+ DEBUG(dbgs() << "LV: Multiple writes to the same index :"<< **w << "\n");
+ return false;
+ }
+ BasePointers.insert(*w);
+ }
+
+ // Sort the writes vector so that we can use a binary search.
+ std::sort(Writes.begin(), Writes.end());
+ // Check that the reads and the writes are disjoint.
+ for (r = Reads.begin(), re = Reads.end(); r != re; ++r) {
+ if (std::binary_search(Writes.begin(), Writes.end(), *r)) {
+ DEBUG(dbgs() << "Vectorizer: Found a read/write ptr:"<< **r << "\n");
+ return false;
+ }
+ }
+
+ // All is okay.
+ return true;
+}
+
+/// Checks if the value is a Global variable or if it is an Arguments
+/// marked with the NoAlias attribute.
+bool LoopVectorizationLegality::isKnownDisjoint(Value* Val) {
+ assert(Val && "Invalid value");
+ if (dyn_cast<GlobalValue>(Val))
+ return true;
+ if (dyn_cast<AllocaInst>(Val))
+ return true;
+ Argument *A = dyn_cast<Argument>(Val);
+ if (!A)
+ return false;
+ return A->hasNoAliasAttr();
+}
+
+} // namespace
+
+char LoopVectorize::ID = 0;
+static const char lv_name[] = "Loop Vectorization";
+INITIALIZE_PASS_BEGIN(LoopVectorize, LV_NAME, lv_name, false, false)
+INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
+INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
+INITIALIZE_PASS_END(LoopVectorize, LV_NAME, lv_name, false, false)
+
+namespace llvm {
+ Pass *createLoopVectorizePass() {
+ return new LoopVectorize();
+ }
+
+}
+
diff --git a/lib/Transforms/Vectorize/Vectorize.cpp b/lib/Transforms/Vectorize/Vectorize.cpp
index 1ef6002..d26973a 100644
--- a/lib/Transforms/Vectorize/Vectorize.cpp
+++ b/lib/Transforms/Vectorize/Vectorize.cpp
@@ -7,7 +7,7 @@
//
//===----------------------------------------------------------------------===//
//
-// This file implements common infrastructure for libLLVMVectorizeOpts.a, which
+// This file implements common infrastructure for libLLVMVectorizeOpts.a, which
// implements several vectorization transformations over the LLVM intermediate
// representation, including the C bindings for that library.
//
@@ -23,10 +23,11 @@
using namespace llvm;
-/// initializeVectorizationPasses - Initialize all passes linked into the
+/// initializeVectorizationPasses - Initialize all passes linked into the
/// Vectorization library.
void llvm::initializeVectorization(PassRegistry &Registry) {
initializeBBVectorizePass(Registry);
+ initializeLoopVectorizePass(Registry);
}
void LLVMInitializeVectorization(LLVMPassRegistryRef R) {
@@ -37,3 +38,6 @@
unwrap(PM)->add(createBBVectorizePass());
}
+void LLVMAddLoopVectorizePass(LLVMPassManagerRef PM) {
+ unwrap(PM)->add(createLoopVectorizePass());
+}