forked from OSchip/llvm-project
Vectorizer: Add support for loop reductions.
For example: for (i=0; i<n; i++) sum += A[i] + B[i] + i; llvm-svn: 166351
This commit is contained in:
Nadav Rotem
parent
1479fcdef1
commit
4f7f72702b
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@ -10,6 +10,8 @@
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// This is a simple loop vectorizer. We currently only support single block
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// loops. We have a very simple and restrictive legality check: we need to read
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// and write from disjoint memory locations. We still don't have a cost model.
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// We do support integer reductions.
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//
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// This pass has three parts:
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// 1. The main loop pass that drives the different parts.
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// 2. LoopVectorizationLegality - A helper class that checks for the legality
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@ -54,9 +56,11 @@ static cl::opt<unsigned>
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DefaultVectorizationFactor("default-loop-vectorize-width",
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cl::init(4), cl::Hidden,
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cl::desc("Set the default loop vectorization width"));
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namespace {
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// Forward declaration.
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class LoopVectorizationLegality;
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/// Vectorize a simple loop. This class performs the widening of simple single
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/// basic block loops into vectors. It does not perform any
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/// vectorization-legality checks, and just does it. It widens the vectors
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@ -67,23 +71,28 @@ public:
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SingleBlockLoopVectorizer(Loop *OrigLoop, ScalarEvolution *Se, LoopInfo *Li,
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LPPassManager *Lpm, unsigned VecWidth):
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Orig(OrigLoop), SE(Se), LI(Li), LPM(Lpm), VF(VecWidth),
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Builder(Se->getContext()), Induction(0), OldInduction(0) { }
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Builder(0), Induction(0), OldInduction(0) { }
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~SingleBlockLoopVectorizer() {
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delete Builder;
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}
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// Perform the actual loop widening (vectorization).
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void vectorize() {
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void vectorize(LoopVectorizationLegality *Legal) {
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///Create a new empty loop. Unlink the old loop and connect the new one.
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createEmptyLoop();
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/// Widen each instruction in the old loop to a new one in the new loop.
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vectorizeLoop();
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/// Use the Legality module to find the induction and reduction variables.
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vectorizeLoop(Legal);
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// register the new loop.
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cleanup();
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}
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}
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private:
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/// Create an empty loop, based on the loop ranges of the old loop.
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void createEmptyLoop();
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/// Copy and widen the instructions from the old loop.
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void vectorizeLoop();
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void vectorizeLoop(LoopVectorizationLegality *Legal);
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/// Insert the new loop to the loop hierarchy and pass manager.
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void cleanup();
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@ -113,6 +122,10 @@ private:
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/// broadcast them into a vector.
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Value *getVectorValue(Value *V);
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/// Get a uniform vector of constant integers. We use this to get
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/// vectors of ones and zeros for the reduction code.
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Constant* getUniformVector(unsigned Val, Type* ScalarTy);
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typedef DenseMap<Value*, Value*> ValueMap;
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/// The original loop.
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@ -127,10 +140,21 @@ private:
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unsigned VF;
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// The builder that we use
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IRBuilder<> Builder;
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IRBuilder<> *Builder;
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// --- Vectorization state ---
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/// Middle Block between the vector and the scalar.
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BasicBlock *LoopMiddleBlock;
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///The ExitBlock of the scalar loop.
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BasicBlock *LoopExitBlock;
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///The vector loop body.
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BasicBlock *LoopVectorBody;
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///The scalar loop body.
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BasicBlock *LoopScalarBody;
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///The first bypass block.
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BasicBlock *LoopBypassBlock;
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/// The new Induction variable which was added to the new block.
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PHINode *Induction;
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/// The induction variable of the old basic block.
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@ -146,7 +170,23 @@ private:
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class LoopVectorizationLegality {
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public:
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LoopVectorizationLegality(Loop *Lp, ScalarEvolution *Se, DataLayout *Dl):
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TheLoop(Lp), SE(Se), DL(Dl) { }
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TheLoop(Lp), SE(Se), DL(Dl), Induction(0) { }
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/// This represents the kinds of reductions that we support.
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enum ReductionKind {
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IntegerAdd, /// Sum of numbers.
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IntegerMult, /// Product of numbers.
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NoReduction /// Not a reduction.
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};
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// Holds a pairing of reduction instruction and the reduction kind.
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typedef std::pair<Instruction*, ReductionKind> ReductionPair;
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/// ReductionList contains the reduction variables
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/// as well as a single EXIT (from the block) value and the kind of
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/// reduction variable..
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/// Notice that the EXIT instruction can also be the PHI itself.
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typedef DenseMap<PHINode*, ReductionPair> ReductionList;
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/// Returns the maximum vectorization factor that we *can* use to vectorize
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/// this loop. This does not mean that it is profitable to vectorize this
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@ -154,6 +194,12 @@ public:
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/// can vectorize to any SIMD width below this number.
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unsigned getLoopMaxVF();
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/// Returns the Induction variable.
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PHINode *getInduction() {return Induction;}
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/// Returns the reduction variables found in the loop.
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ReductionList *getReductionVars() { return &Reductions; }
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private:
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/// Check if a single basic block loop is vectorizable.
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/// At this point we know that this is a loop with a constant trip count
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@ -164,12 +210,32 @@ private:
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// Example: Alloca, Global, NoAlias.
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bool isIdentifiedSafeObject(Value* Val);
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/// Returns True, if 'Phi' is the kind of reduction variable for type
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/// 'Kind'. If this is a reduction variable, it adds it to ReductionList.
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bool AddReductionVar(PHINode *Phi, ReductionKind Kind);
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/// Checks if a constant matches the reduction kind.
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/// Sums starts with zero. Products start at one.
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bool isReductionConstant(Value *V, ReductionKind Kind);
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/// Returns true if the instruction I can be a reduction variable of type
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/// 'Kind'.
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bool isReductionInstr(Instruction *I, ReductionKind Kind);
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/// The loop that we evaluate.
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Loop *TheLoop;
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/// Scev analysis.
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ScalarEvolution *SE;
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/// DataLayout analysis.
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DataLayout *DL;
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// --- vectorization state --- //
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/// Holds the induction variable.
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PHINode *Induction;
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/// Holds the reduction variables.
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ReductionList Reductions;
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/// Allowed outside users. This holds the reduction
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/// vars which can be accessed from outside the loop.
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SmallPtrSet<Value*, 4> AllowedExit;
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};
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struct LoopVectorize : public LoopPass {
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@ -184,6 +250,7 @@ struct LoopVectorize : public LoopPass {
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LoopInfo *LI;
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virtual bool runOnLoop(Loop *L, LPPassManager &LPM) {
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// Only vectorize innermost loops.
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if (!L->empty())
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return false;
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@ -209,7 +276,7 @@ struct LoopVectorize : public LoopPass {
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// If we decided that is is *legal* to vectorizer the loop. Do it.
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SingleBlockLoopVectorizer LB(L, SE, LI, &LPM, DefaultVectorizationFactor);
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LB.vectorize();
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LB.vectorize(&LVL);
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DEBUG(verifyFunction(*L->getHeader()->getParent()));
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return true;
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@ -218,6 +285,7 @@ struct LoopVectorize : public LoopPass {
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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LoopPass::getAnalysisUsage(AU);
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AU.addRequiredID(LoopSimplifyID);
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AU.addRequiredID(LCSSAID);
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AU.addRequired<LoopInfo>();
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AU.addRequired<ScalarEvolution>();
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}
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@ -237,10 +305,10 @@ Value *SingleBlockLoopVectorizer::getBroadcastInstrs(Value *V) {
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Value *Zeros = ConstantAggregateZero::get(VectorType::get(I32, VF));
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Value *UndefVal = UndefValue::get(VTy);
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// Insert the value into a new vector.
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Value *SingleElem = Builder.CreateInsertElement(UndefVal, V, Zero);
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Value *SingleElem = Builder->CreateInsertElement(UndefVal, V, Zero);
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// Broadcast the scalar into all locations in the vector.
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Value *Shuf = Builder.CreateShuffleVector(SingleElem, UndefVal, Zeros,
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"broadcast");
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Value *Shuf = Builder->CreateShuffleVector(SingleElem, UndefVal, Zeros,
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"broadcast");
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// We are accessing the induction variable. Make sure to promote the
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// index for each consecutive SIMD lane. This adds 0,1,2 ... to all lanes.
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if (V == Induction)
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@ -265,7 +333,7 @@ Value *SingleBlockLoopVectorizer::getConsecutiveVector(Value* Val) {
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// Add the consecutive indices to the vector value.
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Constant *Cv = ConstantVector::get(Indices);
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assert(Cv->getType() == Val->getType() && "Invalid consecutive vec");
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return Builder.CreateAdd(Val, Cv, "induction");
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return Builder->CreateAdd(Val, Cv, "induction");
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}
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@ -297,10 +365,11 @@ bool SingleBlockLoopVectorizer::isConsecutiveGep(GetElementPtrInst *Gep) {
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}
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Value *SingleBlockLoopVectorizer::getVectorValue(Value *V) {
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assert(!V->getType()->isVectorTy() && "Can't widen a vector");
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// If we saved a vectorized copy of V, use it.
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ValueMap::iterator it = WidenMap.find(V);
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if (it != WidenMap.end())
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return it->second;
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return it->second;
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// Broadcast V and save the value for future uses.
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Value *B = getBroadcastInstrs(V);
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@ -308,6 +377,17 @@ Value *SingleBlockLoopVectorizer::getVectorValue(Value *V) {
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return B;
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}
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Constant*
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SingleBlockLoopVectorizer::getUniformVector(unsigned Val, Type* ScalarTy) {
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SmallVector<Constant*, 8> Indices;
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// Create a vector of consecutive numbers from zero to VF.
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for (unsigned i = 0; i < VF; ++i)
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Indices.push_back(ConstantInt::get(ScalarTy, Val));
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// Add the consecutive indices to the vector value.
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return ConstantVector::get(Indices);
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}
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void SingleBlockLoopVectorizer::scalarizeInstruction(Instruction *Instr) {
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assert(!Instr->getType()->isAggregateType() && "Can't handle vectors");
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// Holds vector parameters or scalars, in case of uniform vals.
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@ -360,18 +440,18 @@ void SingleBlockLoopVectorizer::scalarizeInstruction(Instruction *Instr) {
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Value *Op = Params[op];
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// Param is a vector. Need to extract the right lane.
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if (Op->getType()->isVectorTy())
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Op = Builder.CreateExtractElement(Op, Builder.getInt32(i));
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Op = Builder->CreateExtractElement(Op, Builder->getInt32(i));
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Cloned->setOperand(op, Op);
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}
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// Place the cloned scalar in the new loop.
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Builder.Insert(Cloned);
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Builder->Insert(Cloned);
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// If the original scalar returns a value we need to place it in a vector
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// so that future users will be able to use it.
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if (!IsVoidRetTy)
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VecResults = Builder.CreateInsertElement(VecResults, Cloned,
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Builder.getInt32(i));
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VecResults = Builder->CreateInsertElement(VecResults, Cloned,
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Builder->getInt32(i));
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}
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if (!IsVoidRetTy)
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@ -417,16 +497,15 @@ void SingleBlockLoopVectorizer::createEmptyLoop() {
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assert(BypassBlock && "Invalid loop structure");
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BasicBlock *VectorPH =
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BypassBlock->splitBasicBlock(BypassBlock->getTerminator(), "vector.ph");
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BypassBlock->splitBasicBlock(BypassBlock->getTerminator(), "vector.ph");
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BasicBlock *VecBody = VectorPH->splitBasicBlock(VectorPH->getTerminator(),
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"vector.body");
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"vector.body");
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BasicBlock *MiddleBlock = VecBody->splitBasicBlock(VecBody->getTerminator(),
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"middle.block");
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"middle.block");
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BasicBlock *ScalarPH =
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MiddleBlock->splitBasicBlock(MiddleBlock->getTerminator(),
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"scalar.preheader");
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MiddleBlock->splitBasicBlock(MiddleBlock->getTerminator(),
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"scalar.preheader");
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// Find the induction variable.
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BasicBlock *OldBasicBlock = Orig->getHeader();
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OldInduction = dyn_cast<PHINode>(OldBasicBlock->begin());
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@ -435,10 +514,11 @@ void SingleBlockLoopVectorizer::createEmptyLoop() {
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// Use this IR builder to create the loop instructions (Phi, Br, Cmp)
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// inside the loop.
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Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
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Builder = new IRBuilder<>(VecBody);
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Builder->SetInsertPoint(VecBody->getFirstInsertionPt());
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// Generate the induction variable.
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Induction = Builder.CreatePHI(IdxTy, 2, "index");
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Induction = Builder->CreatePHI(IdxTy, 2, "index");
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Constant *Zero = ConstantInt::get(IdxTy, 0);
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Constant *Step = ConstantInt::get(IdxTy, VF);
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@ -489,12 +569,12 @@ void SingleBlockLoopVectorizer::createEmptyLoop() {
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MiddleBlock->getTerminator()->eraseFromParent();
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// Create i+1 and fill the PHINode.
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Value *NextIdx = Builder.CreateAdd(Induction, Step, "index.next");
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Value *NextIdx = Builder->CreateAdd(Induction, Step, "index.next");
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Induction->addIncoming(Zero, VectorPH);
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Induction->addIncoming(NextIdx, VecBody);
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// Create the compare.
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Value *ICmp = Builder.CreateICmpEQ(NextIdx, CountRoundDown);
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Builder.CreateCondBr(ICmp, MiddleBlock, VecBody);
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Value *ICmp = Builder->CreateICmpEQ(NextIdx, CountRoundDown);
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Builder->CreateCondBr(ICmp, MiddleBlock, VecBody);
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// Now we have two terminators. Remove the old one from the block.
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VecBody->getTerminator()->eraseFromParent();
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@ -504,7 +584,7 @@ void SingleBlockLoopVectorizer::createEmptyLoop() {
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OldInduction->setIncomingValue(BlockIdx, CountRoundDown);
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// Get ready to start creating new instructions into the vectorized body.
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Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
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Builder->SetInsertPoint(VecBody->getFirstInsertionPt());
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// Register the new loop.
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Loop* Lp = new Loop();
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@ -518,22 +598,52 @@ void SingleBlockLoopVectorizer::createEmptyLoop() {
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ParentLoop->addBasicBlockToLoop(VectorPH, LI->getBase());
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ParentLoop->addBasicBlockToLoop(MiddleBlock, LI->getBase());
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}
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// Save the state.
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LoopMiddleBlock = MiddleBlock;
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LoopExitBlock = ExitBlock;
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LoopVectorBody = VecBody;
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LoopScalarBody = OldBasicBlock;
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LoopBypassBlock = BypassBlock;
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}
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void SingleBlockLoopVectorizer::vectorizeLoop() {
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void
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SingleBlockLoopVectorizer::vectorizeLoop(LoopVectorizationLegality *Legal) {
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typedef SmallVector<PHINode*, 4> PhiVector;
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BasicBlock &BB = *Orig->getHeader();
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// In order to support reduction variables we need to be able to vectorize
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// Phi nodes. Phi nodes have cycles, so we need to vectorize them in two
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// steages. First, we create a new vector PHI node with no incoming edges.
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// We use this value when we vectorize all of the instructions that use the
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// PHI. Next, after all of the instructions in the block are complete we
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// add the new incoming edges to the PHI. At this point all of the
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// instructions in the basic block are vectorized, so we can use them to
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// construct the PHI.
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PhiVector PHIsToFix;
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// For each instruction in the old loop.
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for (BasicBlock::iterator it = BB.begin(), e = BB.end(); it != e; ++it) {
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Instruction *Inst = it;
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switch (Inst->getOpcode()) {
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case Instruction::PHI:
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case Instruction::Br:
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// Nothing to do for PHIs and BR, since we already took care of the
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// loop control flow instructions.
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continue;
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case Instruction::PHI:{
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PHINode* P = cast<PHINode>(Inst);
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// Special handling for the induction var.
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if (OldInduction == Inst)
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continue;
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// This is phase I of vectorizing PHIs.
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// This has to be a reduction variable.
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assert(Legal->getReductionVars()->count(P) && "Not a Reduction");
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Type *VecTy = VectorType::get(Inst->getType(), VF);
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WidenMap[Inst] = Builder->CreatePHI(VecTy, 2, "vec.phi");
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PHIsToFix.push_back(P);
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continue;
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}
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case Instruction::Add:
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case Instruction::FAdd:
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case Instruction::Sub:
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@ -557,15 +667,17 @@ void SingleBlockLoopVectorizer::vectorizeLoop() {
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Value *A = getVectorValue(Inst->getOperand(0));
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Value *B = getVectorValue(Inst->getOperand(1));
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// Use this vector value for all users of the original instruction.
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WidenMap[Inst] = Builder.CreateBinOp(BinOp->getOpcode(), A, B);
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WidenMap[Inst] = Builder->CreateBinOp(BinOp->getOpcode(), A, B);
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break;
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}
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case Instruction::Select: {
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// Widen selects.
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// TODO: If the selector is loop invariant we can issue a select
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// instruction with a scalar condition.
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Value *A = getVectorValue(Inst->getOperand(0));
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Value *B = getVectorValue(Inst->getOperand(1));
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Value *C = getVectorValue(Inst->getOperand(2));
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WidenMap[Inst] = Builder.CreateSelect(A, B, C);
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WidenMap[Inst] = Builder->CreateSelect(A, B, C);
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break;
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}
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@ -577,9 +689,9 @@ void SingleBlockLoopVectorizer::vectorizeLoop() {
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Value *A = getVectorValue(Inst->getOperand(0));
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Value *B = getVectorValue(Inst->getOperand(1));
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if (FCmp)
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WidenMap[Inst] = Builder.CreateFCmp(Cmp->getPredicate(), A, B);
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WidenMap[Inst] = Builder->CreateFCmp(Cmp->getPredicate(), A, B);
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else
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WidenMap[Inst] = Builder.CreateICmp(Cmp->getPredicate(), A, B);
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WidenMap[Inst] = Builder->CreateICmp(Cmp->getPredicate(), A, B);
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break;
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}
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@ -600,10 +712,10 @@ void SingleBlockLoopVectorizer::vectorizeLoop() {
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GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
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unsigned NumOperands = Gep->getNumOperands();
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Gep2->setOperand(NumOperands - 1, Induction);
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Ptr = Builder.Insert(Gep2);
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Ptr = Builder.CreateBitCast(Ptr, StTy->getPointerTo());
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Ptr = Builder->Insert(Gep2);
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Ptr = Builder->CreateBitCast(Ptr, StTy->getPointerTo());
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Value *Val = getVectorValue(SI->getValueOperand());
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Builder.CreateStore(Val, Ptr)->setAlignment(Alignment);
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Builder->CreateStore(Val, Ptr)->setAlignment(Alignment);
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||||
break;
|
||||
}
|
||||
case Instruction::Load: {
|
||||
|
|
@ -624,9 +736,9 @@ void SingleBlockLoopVectorizer::vectorizeLoop() {
|
|||
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);
|
||||
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;
|
||||
|
|
@ -648,7 +760,7 @@ void SingleBlockLoopVectorizer::vectorizeLoop() {
|
|||
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);
|
||||
WidenMap[Inst] = Builder->CreateCast(CI->getOpcode(), A, DestTy);
|
||||
break;
|
||||
}
|
||||
|
||||
|
|
@ -658,6 +770,102 @@ void SingleBlockLoopVectorizer::vectorizeLoop() {
|
|||
break;
|
||||
}// end of switch.
|
||||
}// end of for_each instr.
|
||||
|
||||
// At this point every instruction in the original loop is widended to
|
||||
// a vector form. We are almost done. Now, we need to fix the PHI nodes
|
||||
// that we vectorized. The PHI nodes are currently empty because we did
|
||||
// not want to introduce cycles. Notice that the remaining PHI nodes
|
||||
// that we need to fix are reduction variables.
|
||||
|
||||
// Create the 'reduced' values for each of the induction vars.
|
||||
// The reduced values are the vector values that we scalarize and combine
|
||||
// after the loop is finished.
|
||||
for (PhiVector::iterator it = PHIsToFix.begin(), e = PHIsToFix.end();
|
||||
it != e; ++it) {
|
||||
PHINode *RdxPhi = *it;
|
||||
PHINode *VecRdxPhi = dyn_cast<PHINode>(WidenMap[RdxPhi]);
|
||||
assert(RdxPhi && "Unable to recover vectorized PHI");
|
||||
|
||||
// Find the reduction variable.
|
||||
assert(Legal->getReductionVars()->count(RdxPhi) &&
|
||||
"Unable to find the reduction variable");
|
||||
LoopVectorizationLegality::ReductionPair ReductionVar =
|
||||
(*Legal->getReductionVars())[RdxPhi];
|
||||
|
||||
// This is the vector-clone of the value that leaves the loop.
|
||||
Value *VectorExit = getVectorValue(ReductionVar.first);
|
||||
Type *VecTy = VectorExit->getType();
|
||||
|
||||
// This is the kind of reduction.
|
||||
LoopVectorizationLegality::ReductionKind RdxKind = ReductionVar.second;
|
||||
// Find the reduction identity variable.
|
||||
// Zero for addition. One for Multiplication.
|
||||
unsigned IdentitySclr =
|
||||
(RdxKind == LoopVectorizationLegality::IntegerAdd ? 0 : 1);
|
||||
Constant *Identity = getUniformVector(IdentitySclr, VecTy->getScalarType());
|
||||
|
||||
// Fix the vector-loop phi.
|
||||
// We created the induction variable so we know that the
|
||||
// preheader is the first entry.
|
||||
BasicBlock *VecPreheader = Induction->getIncomingBlock(0);
|
||||
VecRdxPhi->addIncoming(Identity, VecPreheader);
|
||||
unsigned SelfEdgeIdx = (RdxPhi)->getBasicBlockIndex(LoopScalarBody);
|
||||
Value *Val = getVectorValue(RdxPhi->getIncomingValue(SelfEdgeIdx));
|
||||
VecRdxPhi->addIncoming(Val, LoopVectorBody);
|
||||
|
||||
// Before each round, move the insertion point right between
|
||||
// the PHIs and the values we are going to write.
|
||||
// This allows us to write both PHINodes and the extractelement
|
||||
// instructions.
|
||||
Builder->SetInsertPoint(LoopMiddleBlock->getFirstInsertionPt());
|
||||
|
||||
// This PHINode contains the vectorized reduction variable, or
|
||||
// the identity vector, if we bypass the vector loop.
|
||||
PHINode *NewPhi = Builder->CreatePHI(VecTy, 2, "rdx.vec.exit.phi");
|
||||
NewPhi->addIncoming(Identity, LoopBypassBlock);
|
||||
NewPhi->addIncoming(getVectorValue(ReductionVar.first), LoopVectorBody);
|
||||
|
||||
// Extract the first scalar.
|
||||
Value *Scalar0 =
|
||||
Builder->CreateExtractElement(NewPhi, Builder->getInt32(0));
|
||||
// Extract and sum the remaining vector elements.
|
||||
for (unsigned i=1; i < VF; ++i) {
|
||||
Value *Scalar1 =
|
||||
Builder->CreateExtractElement(NewPhi, Builder->getInt32(i));
|
||||
if (RdxKind == LoopVectorizationLegality::IntegerAdd) {
|
||||
Scalar0 = Builder->CreateAdd(Scalar0, Scalar1);
|
||||
} else {
|
||||
Scalar0 = Builder->CreateMul(Scalar0, Scalar1);
|
||||
}
|
||||
}
|
||||
|
||||
// Now, we need to fix the users of the reduction variable
|
||||
// inside and outside of the scalar remainder loop.
|
||||
// We know that the loop is in LCSSA form. We need to update the
|
||||
// PHI nodes in the exit blocks.
|
||||
for (BasicBlock::iterator LEI = LoopExitBlock->begin(),
|
||||
LEE = LoopExitBlock->end(); LEI != LEE; ++LEI) {
|
||||
PHINode *LCSSAPhi = dyn_cast<PHINode>(LEI);
|
||||
if (!LCSSAPhi) continue;
|
||||
|
||||
// All PHINodes need to have a single entry edge, or two if we already fixed them.
|
||||
assert(LCSSAPhi->getNumIncomingValues() < 3 && "Invalid LCSSA PHI");
|
||||
|
||||
// We found our reduction value exit-PHI. Update it with the incoming bypass edge.
|
||||
if (LCSSAPhi->getIncomingValue(0) == ReductionVar.first) {
|
||||
// Add an edge coming from the bypass.
|
||||
LCSSAPhi->addIncoming(Scalar0, LoopMiddleBlock);
|
||||
break;
|
||||
}
|
||||
}// end of the LCSSA phi scan.
|
||||
|
||||
// Fix the scalar loop reduction variable with the incoming reduction sum
|
||||
// from the vector body and from the backedge value.
|
||||
int IncomingEdgeBlockIdx = (RdxPhi)->getBasicBlockIndex(LoopScalarBody);
|
||||
int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1); // The other block.
|
||||
(RdxPhi)->setIncomingValue(SelfEdgeBlockIdx, Scalar0);
|
||||
(RdxPhi)->setIncomingValue(IncomingEdgeBlockIdx, ReductionVar.first);
|
||||
}// end of for each redux variable.
|
||||
}
|
||||
|
||||
void SingleBlockLoopVectorizer::cleanup() {
|
||||
|
|
@ -710,31 +918,35 @@ bool LoopVectorizationLegality::canVectorizeBlock(BasicBlock &BB) {
|
|||
ValueVector Reads;
|
||||
ValueVector Writes;
|
||||
|
||||
SmallPtrSet<Value*, 16> AnalyzedPtrs;
|
||||
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;
|
||||
}
|
||||
// We only look at integer phi nodes.
|
||||
if (!Phi->getType()->isIntegerTy()) {
|
||||
DEBUG(dbgs() << "LV: Found an non-int PHI.\n");
|
||||
return false;
|
||||
}
|
||||
if (AddReductionVar(Phi, IntegerAdd)) {
|
||||
DEBUG(dbgs() << "LV: Found an ADD reduction PHI."<< *Phi <<"\n");
|
||||
continue;
|
||||
}
|
||||
if (AddReductionVar(Phi, IntegerMult)) {
|
||||
DEBUG(dbgs() << "LV: Found an Mult reduction PHI."<< *Phi <<"\n");
|
||||
continue;
|
||||
}
|
||||
if (Induction) {
|
||||
DEBUG(dbgs() << "LV: Found too many PHIs.\n");
|
||||
return false;
|
||||
}
|
||||
// Found the induction variable.
|
||||
Induction = Phi;
|
||||
|
||||
// Check that the PHI is consecutive and starts at zero.
|
||||
const SCEV *PhiScev = SE->getSCEV(Phi);
|
||||
|
|
@ -751,7 +963,7 @@ bool LoopVectorizationLegality::canVectorizeBlock(BasicBlock &BB) {
|
|||
DEBUG(dbgs() << "LV: PHI does not start at zero or steps by one.\n");
|
||||
return false;
|
||||
}
|
||||
}
|
||||
}// end of PHI handling
|
||||
|
||||
// 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.
|
||||
|
|
@ -764,8 +976,7 @@ bool LoopVectorizationLegality::canVectorizeBlock(BasicBlock &BB) {
|
|||
}
|
||||
|
||||
Value* Ptr = Ld->getPointerOperand();
|
||||
if (AnalyzedPtrs.insert(Ptr))
|
||||
GetUnderlyingObjects(Ptr, Reads, DL);
|
||||
GetUnderlyingObjects(Ptr, Reads, DL);
|
||||
}
|
||||
|
||||
// Record store pointers. Abort on all other instructions that write to
|
||||
|
|
@ -779,8 +990,7 @@ bool LoopVectorizationLegality::canVectorizeBlock(BasicBlock &BB) {
|
|||
}
|
||||
|
||||
Value* Ptr = St->getPointerOperand();
|
||||
if (AnalyzedPtrs.insert(Ptr))
|
||||
GetUnderlyingObjects(St->getPointerOperand(), Writes, DL);
|
||||
GetUnderlyingObjects(Ptr, Writes, DL);
|
||||
}
|
||||
|
||||
// We still don't handle functions.
|
||||
|
|
@ -797,21 +1007,26 @@ bool LoopVectorizationLegality::canVectorizeBlock(BasicBlock &BB) {
|
|||
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;
|
||||
}
|
||||
|
||||
// Reduction instructions are allowed to have exit users.
|
||||
// All other instructions must not have external users.
|
||||
if (!AllowedExit.count(I))
|
||||
//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);
|
||||
// This user may be a reduction exit value.
|
||||
BasicBlock *Parent = U->getParent();
|
||||
if (Parent != &BB) {
|
||||
DEBUG(dbgs() << "LV: Found an outside user for : "<< *U << "\n");
|
||||
return false;
|
||||
}
|
||||
}
|
||||
} // next instr.
|
||||
|
||||
if (NumPhis != 1) {
|
||||
DEBUG(dbgs() << "LV: Did not find a Phi node.\n");
|
||||
return false;
|
||||
if (!Induction) {
|
||||
DEBUG(dbgs() << "LV: Did not find an induction var.\n");
|
||||
return false;
|
||||
}
|
||||
|
||||
// Check that the underlying objects of the reads and writes are either
|
||||
|
|
@ -866,6 +1081,110 @@ bool LoopVectorizationLegality::isIdentifiedSafeObject(Value* Val) {
|
|||
return A->hasNoAliasAttr();
|
||||
}
|
||||
|
||||
bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
|
||||
ReductionKind Kind) {
|
||||
if (Phi->getNumIncomingValues() != 2)
|
||||
return false;
|
||||
|
||||
// Find the possible incoming reduction variable.
|
||||
BasicBlock *BB = Phi->getParent();
|
||||
int SelfEdgeIdx = Phi->getBasicBlockIndex(BB);
|
||||
int InEdgeBlockIdx = (SelfEdgeIdx ? 0 : 1); // The other entry.
|
||||
Value *RdxStart = Phi->getIncomingValue(InEdgeBlockIdx);
|
||||
|
||||
// We must have a constant that starts the reduction.
|
||||
if (!isReductionConstant(RdxStart, Kind))
|
||||
return false;
|
||||
|
||||
// ExitInstruction is the single value which is used outside the loop.
|
||||
// We only allow for a single reduction value to be used outside the loop.
|
||||
// This includes users of the reduction, variables (which form a cycle
|
||||
// which ends in the phi node).
|
||||
Instruction *ExitInstruction = 0;
|
||||
|
||||
// Iter is our iterator. We start with the PHI node and scan for all of the
|
||||
// users of this instruction. All users must be instructions which can be
|
||||
// used as reduction variables (such as ADD). We may have a single
|
||||
// out-of-block user. They cycle must end with the original PHI.
|
||||
// Also, we can't have multiple block-local users.
|
||||
Instruction *Iter = Phi;
|
||||
while (true) {
|
||||
// Any reduction instr must be of one of the allowed kinds.
|
||||
if (!isReductionInstr(Iter, Kind))
|
||||
return false;
|
||||
|
||||
// Did we found a user inside this block ?
|
||||
bool FoundInBlockUser = false;
|
||||
// Did we reach the initial PHI node ?
|
||||
bool FoundStartPHI = false;
|
||||
// For each of the *users* of iter.
|
||||
for (Value::use_iterator it = Iter->use_begin(), e = Iter->use_end();
|
||||
it != e; ++it) {
|
||||
Instruction *U = cast<Instruction>(*it);
|
||||
// We already know that the PHI is a user.
|
||||
if (U == Phi) {
|
||||
FoundStartPHI = true;
|
||||
continue;
|
||||
}
|
||||
// Check if we found the exit user.
|
||||
BasicBlock *Parent = U->getParent();
|
||||
if (Parent != BB) {
|
||||
// We must have a single exit instruction.
|
||||
if (ExitInstruction != 0)
|
||||
return false;
|
||||
ExitInstruction = Iter;
|
||||
}
|
||||
// We can't have multiple inside users.
|
||||
if (FoundInBlockUser)
|
||||
return false;
|
||||
FoundInBlockUser = true;
|
||||
Iter = U;
|
||||
}
|
||||
|
||||
// We found a reduction var if we have reached the original
|
||||
// phi node and we only have a single instruction with out-of-loop
|
||||
// users.
|
||||
if (FoundStartPHI && ExitInstruction) {
|
||||
// This instruction is allowed to have out-of-loop users.
|
||||
AllowedExit.insert(ExitInstruction);
|
||||
// Mark this as a reduction var.
|
||||
Reductions[Phi] = std::make_pair(ExitInstruction, Kind);
|
||||
return true;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
bool
|
||||
LoopVectorizationLegality::isReductionConstant(Value *V, ReductionKind Kind) {
|
||||
ConstantInt *CI = dyn_cast<ConstantInt>(V);
|
||||
if (!CI)
|
||||
return false;
|
||||
if (Kind == IntegerMult && CI->isOne())
|
||||
return true;
|
||||
if (Kind == IntegerAdd && CI->isZero())
|
||||
return true;
|
||||
return false;
|
||||
}
|
||||
|
||||
bool
|
||||
LoopVectorizationLegality::isReductionInstr(Instruction *I,
|
||||
ReductionKind Kind) {
|
||||
switch (I->getOpcode()) {
|
||||
default:
|
||||
return false;
|
||||
case Instruction::PHI:
|
||||
// possibly.
|
||||
return true;
|
||||
case Instruction::Add:
|
||||
case Instruction::Sub:
|
||||
return Kind == IntegerAdd;
|
||||
case Instruction::Mul:
|
||||
case Instruction::UDiv:
|
||||
case Instruction::SDiv:
|
||||
return Kind == IntegerMult;
|
||||
}
|
||||
}
|
||||
|
||||
} // namespace
|
||||
|
||||
char LoopVectorize::ID = 0;
|
||||
|
|
@ -880,6 +1199,5 @@ namespace llvm {
|
|||
Pass *createLoopVectorizePass() {
|
||||
return new LoopVectorize();
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -202,9 +202,8 @@ define void @example8(i32 %x) nounwind uwtable ssp {
|
|||
ret void
|
||||
}
|
||||
|
||||
; We can't vectorize because it has a reduction variable.
|
||||
;CHECK: @example9
|
||||
;CHECK-NOT: <4 x i32>
|
||||
;CHECK: phi <4 x i32>
|
||||
;CHECK: ret i32
|
||||
define i32 @example9() nounwind uwtable readonly ssp {
|
||||
br label %1
|
||||
|
|
|
|||
|
|
@ -1,35 +0,0 @@
|
|||
; RUN: opt < %s -loop-vectorize -dce -instcombine -licm -S | FileCheck %s
|
||||
|
||||
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
|
||||
target triple = "x86_64-apple-macosx10.8.0"
|
||||
|
||||
@a = common global [2048 x i32] zeroinitializer, align 16
|
||||
|
||||
; This is the loop.
|
||||
; for (i=0; i<n; i++){
|
||||
; a[i] += i;
|
||||
; }
|
||||
;CHECK: @inc
|
||||
;CHECK: load <4 x i32>
|
||||
;CHECK: add <4 x i32>
|
||||
;CHECK: store <4 x i32>
|
||||
;CHECK: ret void
|
||||
define void @inc(i32 %n) nounwind uwtable noinline ssp {
|
||||
%1 = icmp sgt i32 %n, 0
|
||||
br i1 %1, label %.lr.ph, label %._crit_edge
|
||||
|
||||
.lr.ph: ; preds = %0, %.lr.ph
|
||||
%indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
|
||||
%2 = getelementptr inbounds [2048 x i32]* @a, i64 0, i64 %indvars.iv
|
||||
%3 = load i32* %2, align 4
|
||||
%4 = trunc i64 %indvars.iv to i32
|
||||
%5 = add nsw i32 %3, %4
|
||||
store i32 %5, i32* %2, align 4
|
||||
%indvars.iv.next = add i64 %indvars.iv, 1
|
||||
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
|
||||
%exitcond = icmp eq i32 %lftr.wideiv, %n
|
||||
br i1 %exitcond, label %._crit_edge, label %.lr.ph
|
||||
|
||||
._crit_edge: ; preds = %.lr.ph, %0
|
||||
ret void
|
||||
}
|
||||
|
|
@ -0,0 +1,122 @@
|
|||
; RUN: opt < %s -loop-vectorize -dce -instcombine -licm -S | FileCheck %s
|
||||
|
||||
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
|
||||
target triple = "x86_64-apple-macosx10.8.0"
|
||||
|
||||
;CHECK: @reduction_sum
|
||||
;CHECK: phi <4 x i32>
|
||||
;CHECK: load <4 x i32>
|
||||
;CHECK: add <4 x i32>
|
||||
;CHECK: ret i32
|
||||
define i32 @reduction_sum(i32 %n, i32* noalias nocapture %A, i32* noalias nocapture %B) nounwind uwtable readonly noinline ssp {
|
||||
%1 = icmp sgt i32 %n, 0
|
||||
br i1 %1, label %.lr.ph, label %._crit_edge
|
||||
|
||||
.lr.ph: ; preds = %0, %.lr.ph
|
||||
%indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
|
||||
%sum.02 = phi i32 [ %9, %.lr.ph ], [ 0, %0 ]
|
||||
%2 = getelementptr inbounds i32* %A, i64 %indvars.iv
|
||||
%3 = load i32* %2, align 4
|
||||
%4 = getelementptr inbounds i32* %B, i64 %indvars.iv
|
||||
%5 = load i32* %4, align 4
|
||||
%6 = trunc i64 %indvars.iv to i32
|
||||
%7 = add i32 %sum.02, %6
|
||||
%8 = add i32 %7, %3
|
||||
%9 = add i32 %8, %5
|
||||
%indvars.iv.next = add i64 %indvars.iv, 1
|
||||
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
|
||||
%exitcond = icmp eq i32 %lftr.wideiv, %n
|
||||
br i1 %exitcond, label %._crit_edge, label %.lr.ph
|
||||
|
||||
._crit_edge: ; preds = %.lr.ph, %0
|
||||
%sum.0.lcssa = phi i32 [ 0, %0 ], [ %9, %.lr.ph ]
|
||||
ret i32 %sum.0.lcssa
|
||||
}
|
||||
|
||||
;CHECK: @reduction_prod
|
||||
;CHECK: phi <4 x i32>
|
||||
;CHECK: load <4 x i32>
|
||||
;CHECK: mul <4 x i32>
|
||||
;CHECK: ret i32
|
||||
define i32 @reduction_prod(i32 %n, i32* noalias nocapture %A, i32* noalias nocapture %B) nounwind uwtable readonly noinline ssp {
|
||||
%1 = icmp sgt i32 %n, 0
|
||||
br i1 %1, label %.lr.ph, label %._crit_edge
|
||||
|
||||
.lr.ph: ; preds = %0, %.lr.ph
|
||||
%indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
|
||||
%prod.02 = phi i32 [ %9, %.lr.ph ], [ 1, %0 ]
|
||||
%2 = getelementptr inbounds i32* %A, i64 %indvars.iv
|
||||
%3 = load i32* %2, align 4
|
||||
%4 = getelementptr inbounds i32* %B, i64 %indvars.iv
|
||||
%5 = load i32* %4, align 4
|
||||
%6 = trunc i64 %indvars.iv to i32
|
||||
%7 = mul i32 %prod.02, %6
|
||||
%8 = mul i32 %7, %3
|
||||
%9 = mul i32 %8, %5
|
||||
%indvars.iv.next = add i64 %indvars.iv, 1
|
||||
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
|
||||
%exitcond = icmp eq i32 %lftr.wideiv, %n
|
||||
br i1 %exitcond, label %._crit_edge, label %.lr.ph
|
||||
|
||||
._crit_edge: ; preds = %.lr.ph, %0
|
||||
%prod.0.lcssa = phi i32 [ 1, %0 ], [ %9, %.lr.ph ]
|
||||
ret i32 %prod.0.lcssa
|
||||
}
|
||||
|
||||
;CHECK: @reduction_mix
|
||||
;CHECK: phi <4 x i32>
|
||||
;CHECK: load <4 x i32>
|
||||
;CHECK: mul <4 x i32>
|
||||
;CHECK: ret i32
|
||||
define i32 @reduction_mix(i32 %n, i32* noalias nocapture %A, i32* noalias nocapture %B) nounwind uwtable readonly noinline ssp {
|
||||
%1 = icmp sgt i32 %n, 0
|
||||
br i1 %1, label %.lr.ph, label %._crit_edge
|
||||
|
||||
.lr.ph: ; preds = %0, %.lr.ph
|
||||
%indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
|
||||
%sum.02 = phi i32 [ %9, %.lr.ph ], [ 0, %0 ]
|
||||
%2 = getelementptr inbounds i32* %A, i64 %indvars.iv
|
||||
%3 = load i32* %2, align 4
|
||||
%4 = getelementptr inbounds i32* %B, i64 %indvars.iv
|
||||
%5 = load i32* %4, align 4
|
||||
%6 = mul nsw i32 %5, %3
|
||||
%7 = trunc i64 %indvars.iv to i32
|
||||
%8 = add i32 %sum.02, %7
|
||||
%9 = add i32 %8, %6
|
||||
%indvars.iv.next = add i64 %indvars.iv, 1
|
||||
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
|
||||
%exitcond = icmp eq i32 %lftr.wideiv, %n
|
||||
br i1 %exitcond, label %._crit_edge, label %.lr.ph
|
||||
|
||||
._crit_edge: ; preds = %.lr.ph, %0
|
||||
%sum.0.lcssa = phi i32 [ 0, %0 ], [ %9, %.lr.ph ]
|
||||
ret i32 %sum.0.lcssa
|
||||
}
|
||||
|
||||
;CHECK: @reduction_bad
|
||||
;CHECK-NOT: <4 x i32>
|
||||
;CHECK: ret i32
|
||||
define i32 @reduction_bad(i32 %n, i32* noalias nocapture %A, i32* noalias nocapture %B) nounwind uwtable readonly noinline ssp {
|
||||
%1 = icmp sgt i32 %n, 0
|
||||
br i1 %1, label %.lr.ph, label %._crit_edge
|
||||
|
||||
.lr.ph: ; preds = %0, %.lr.ph
|
||||
%indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
|
||||
%sum.02 = phi i32 [ %9, %.lr.ph ], [ 0, %0 ]
|
||||
%2 = getelementptr inbounds i32* %A, i64 %indvars.iv
|
||||
%3 = load i32* %2, align 4
|
||||
%4 = getelementptr inbounds i32* %B, i64 %indvars.iv
|
||||
%5 = load i32* %4, align 4
|
||||
%6 = trunc i64 %indvars.iv to i32
|
||||
%7 = add i32 %3, %6
|
||||
%8 = add i32 %7, %5
|
||||
%9 = mul i32 %8, %sum.02
|
||||
%indvars.iv.next = add i64 %indvars.iv, 1
|
||||
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
|
||||
%exitcond = icmp eq i32 %lftr.wideiv, %n
|
||||
br i1 %exitcond, label %._crit_edge, label %.lr.ph
|
||||
|
||||
._crit_edge: ; preds = %.lr.ph, %0
|
||||
%sum.0.lcssa = phi i32 [ 0, %0 ], [ %9, %.lr.ph ]
|
||||
ret i32 %sum.0.lcssa
|
||||
}
|
||||
Loading…
Reference in New Issue