// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
-//
-// This is the LLVM loop vectorizer. This pass modifies 'vectorizable' loops
-// and generates target-independent LLVM-IR. Legalization of the IR is done
-// in the codegen. However, the vectorizes uses (will use) the codegen
-// interfaces to generate IR that is likely to result in an optimal binary.
-//
-// The loop vectorizer combines consecutive loop iteration into a single
-// 'wide' iteration. After this transformation the index is incremented
-// by the SIMD vector width, and not by one.
-//
-// This pass has three parts:
-// 1. The main loop pass that drives the different parts.
-// 2. LoopVectorizationLegality - A unit that checks for the legality
-// of the vectorization.
-// 3. SingleBlockLoopVectorizer - A unit that performs the actual
-// widening of instructions.
-// 4. LoopVectorizationCostModel - A unit that checks for the profitability
-// of vectorization. It decides on the optimal vector width, which
-// can be one, if vectorization is not profitable.
-//===----------------------------------------------------------------------===//
-//
-// The reduction-variable vectorization is based on the paper:
-// D. Nuzman and R. Henderson. Multi-platform Auto-vectorization.
-//
-// Variable uniformity checks are inspired by:
-// Karrenberg, R. and Hack, S. Whole Function Vectorization.
-//
-// Other ideas/concepts are from:
-// A. Zaks and D. Nuzman. Autovectorization in GCC-two years later.
-//
-//===----------------------------------------------------------------------===//
-#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/Analysis/Verifier.h"
-#include "llvm/Module.h"
-#include "llvm/Type.h"
-#include "llvm/ADT/SmallVector.h"
+#include "LoopVectorize.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AliasSetTracker.h"
-#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/Dominators.h"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/LoopIterator.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/TargetTransformInfo.h"
+#include "llvm/Analysis/Verifier.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/Value.h"
+#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/DataLayout.h"
+#include "llvm/TargetTransformInfo.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
-#include <algorithm>
-using namespace llvm;
+#include "llvm/Transforms/Vectorize.h"
static cl::opt<unsigned>
VectorizationFactor("force-vector-width", cl::init(0), cl::Hidden,
- cl::desc("Set the default vectorization width. Zero is autoselect."));
-
-/// We don't vectorize loops with a known constant trip count below this number.
-const unsigned TinyTripCountThreshold = 16;
-
-namespace {
-
-// Forward declarations.
-class LoopVectorizationLegality;
-class LoopVectorizationCostModel;
-
-/// SingleBlockLoopVectorizer vectorizes loops which contain only one basic
-/// block to a specified vectorization factor (VF).
-/// This class performs the widening of scalars into vectors, or multiple
-/// scalars. This class also implements the following features:
-/// * It inserts an epilogue loop for handling loops that don't have iteration
-/// counts that are known to be a multiple of the vectorization factor.
-/// * It handles the code generation for reduction variables.
-/// * Scalarization (implementation using scalars) of un-vectorizable
-/// instructions.
-/// SingleBlockLoopVectorizer does not perform any vectorization-legality
-/// checks, and relies on the caller to check for the different legality
-/// aspects. The SingleBlockLoopVectorizer relies on the
-/// LoopVectorizationLegality class to provide information about the induction
-/// and reduction variables that were found to a given vectorization factor.
-class SingleBlockLoopVectorizer {
-public:
- /// Ctor.
- SingleBlockLoopVectorizer(Loop *Orig, ScalarEvolution *Se, LoopInfo *Li,
- DominatorTree *dt, LPPassManager *Lpm,
- unsigned VecWidth):
- OrigLoop(Orig), SE(Se), LI(Li), DT(dt), LPM(Lpm), VF(VecWidth),
- Builder(Se->getContext()), Induction(0), OldInduction(0) { }
-
- // Perform the actual loop widening (vectorization).
- void vectorize(LoopVectorizationLegality *Legal) {
- ///Create a new empty loop. Unlink the old loop and connect the new one.
- createEmptyLoop(Legal);
- /// Widen each instruction in the old loop to a new one in the new loop.
- /// Use the Legality module to find the induction and reduction variables.
- vectorizeLoop(Legal);
- // register the new loop.
- updateAnalysis();
- }
-
-private:
- /// Create an empty loop, based on the loop ranges of the old loop.
- void createEmptyLoop(LoopVectorizationLegality *Legal);
- /// Copy and widen the instructions from the old loop.
- void vectorizeLoop(LoopVectorizationLegality *Legal);
- /// Insert the new loop to the loop hierarchy and pass manager.
- void updateAnalysis();
-
- /// 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);
-
- /// 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);
-
- /// Get a uniform vector of constant integers. We use this to get
- /// vectors of ones and zeros for the reduction code.
- Constant* getUniformVector(unsigned Val, Type* ScalarTy);
-
- typedef DenseMap<Value*, Value*> ValueMap;
-
- /// The original loop.
- Loop *OrigLoop;
- // Scev analysis to use.
- ScalarEvolution *SE;
- // Loop Info.
- LoopInfo *LI;
- // Dominator Tree.
- DominatorTree *DT;
- // Loop Pass Manager;
- LPPassManager *LPM;
- // The vectorization factor to use.
- unsigned VF;
-
- // The builder that we use
- IRBuilder<> Builder;
-
- // --- Vectorization state ---
-
- /// The vector-loop preheader.
- BasicBlock *LoopVectorPreHeader;
- /// The scalar-loop preheader.
- BasicBlock *LoopScalarPreHeader;
- /// Middle Block between the vector and the scalar.
- BasicBlock *LoopMiddleBlock;
- ///The ExitBlock of the scalar loop.
- BasicBlock *LoopExitBlock;
- ///The vector loop body.
- BasicBlock *LoopVectorBody;
- ///The scalar loop body.
- BasicBlock *LoopScalarBody;
- ///The first bypass block.
- BasicBlock *LoopBypassBlock;
-
- /// The new Induction variable which was added to the new block.
- PHINode *Induction;
- /// The induction variable of the old basic block.
- PHINode *OldInduction;
- // Maps scalars to widened vectors.
- ValueMap WidenMap;
-};
-
-/// LoopVectorizationLegality checks if it is legal to vectorize a loop, and
-/// to what vectorization factor.
-/// This class does not look at the profitability of vectorization, only the
-/// legality. This class has two main kinds of checks:
-/// * Memory checks - The code in canVectorizeMemory checks if vectorization
-/// will change the order of memory accesses in a way that will change the
-/// correctness of the program.
-/// * Scalars checks - The code in canVectorizeBlock checks for a number
-/// of different conditions, such as the availability of a single induction
-/// variable, that all types are supported and vectorize-able, etc.
-/// This code reflects the capabilities of SingleBlockLoopVectorizer.
-/// This class is also used by SingleBlockLoopVectorizer for identifying
-/// induction variable and the different reduction variables.
-class LoopVectorizationLegality {
-public:
- LoopVectorizationLegality(Loop *Lp, ScalarEvolution *Se, DataLayout *Dl):
- TheLoop(Lp), SE(Se), DL(Dl), Induction(0) { }
-
- /// This represents the kinds of reductions that we support.
- enum ReductionKind {
- NoReduction, /// Not a reduction.
- IntegerAdd, /// Sum of numbers.
- IntegerMult, /// Product of numbers.
- IntegerOr, /// Bitwise or logical OR of numbers.
- IntegerAnd, /// Bitwise or logical AND of numbers.
- IntegerXor /// Bitwise or logical XOR of numbers.
- };
-
- /// This POD struct holds information about reduction variables.
- struct ReductionDescriptor {
- // Default C'tor
- ReductionDescriptor():
- StartValue(0), LoopExitInstr(0), Kind(NoReduction) {}
-
- // C'tor.
- ReductionDescriptor(Value *Start, Instruction *Exit, ReductionKind K):
- StartValue(Start), LoopExitInstr(Exit), Kind(K) {}
-
- // The starting value of the reduction.
- // It does not have to be zero!
- Value *StartValue;
- // The instruction who's value is used outside the loop.
- Instruction *LoopExitInstr;
- // The kind of the reduction.
- ReductionKind Kind;
- };
-
- /// ReductionList contains the reduction descriptors for all
- /// of the reductions that were found in the loop.
- typedef DenseMap<PHINode*, ReductionDescriptor> ReductionList;
-
- /// Returns true if it is legal to vectorize this loop.
- /// This does not mean that it is profitable to vectorize this
- /// loop, only that it is legal to do so.
- bool canVectorize();
-
- /// Returns the Induction variable.
- PHINode *getInduction() {return Induction;}
-
- /// Returns the reduction variables found in the loop.
- ReductionList *getReductionVars() { return &Reductions; }
-
- /// Check if the pointer returned by this GEP is consecutive
- /// when the index is vectorized. This happens when the last
- /// index of the GEP is consecutive, like the induction variable.
- /// This check allows us to vectorize A[idx] into a wide load/store.
- bool isConsecutiveGep(Value *Ptr);
-
- /// Returns true if this instruction will remain scalar after vectorization.
- bool isUniformAfterVectorization(Instruction* I) {return Uniforms.count(I);}
-
-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);
-
- /// When we vectorize loops we may change the order in which
- /// we read and write from memory. This method checks if it is
- /// legal to vectorize the code, considering only memory constrains.
- /// Returns true if BB is vectorizable
- bool canVectorizeMemory(BasicBlock &BB);
-
- /// Returns True, if 'Phi' is the kind of reduction variable for type
- /// 'Kind'. If this is a reduction variable, it adds it to ReductionList.
- bool AddReductionVar(PHINode *Phi, ReductionKind Kind);
- /// Returns true if the instruction I can be a reduction variable of type
- /// 'Kind'.
- bool isReductionInstr(Instruction *I, ReductionKind Kind);
- /// Returns True, if 'Phi' is an induction variable.
- bool isInductionVariable(PHINode *Phi);
-
- /// The loop that we evaluate.
- Loop *TheLoop;
- /// Scev analysis.
- ScalarEvolution *SE;
- /// DataLayout analysis.
- DataLayout *DL;
+ cl::desc("Sets the SIMD width. Zero is autoselect."));
- // --- vectorization state --- //
-
- /// Holds the induction variable.
- PHINode *Induction;
- /// Holds the reduction variables.
- ReductionList Reductions;
- /// Allowed outside users. This holds the reduction
- /// vars which can be accessed from outside the loop.
- SmallPtrSet<Value*, 4> AllowedExit;
- /// This set holds the variables which are known to be uniform after
- /// vectorization.
- SmallPtrSet<Instruction*, 4> Uniforms;
-};
+static cl::opt<unsigned>
+VectorizationUnroll("force-vector-unroll", cl::init(0), cl::Hidden,
+ cl::desc("Sets the vectorization unroll count. "
+ "Zero is autoselect."));
-/// LoopVectorizationCostModel - estimates the expected speedups due to
-/// vectorization.
-/// In many cases vectorization is not profitable. This can happen because
-/// of a number of reasons. In this class we mainly attempt to predict
-/// the expected speedup/slowdowns due to the supported instruction set.
-/// We use the VectorTargetTransformInfo to query the different backends
-/// for the cost of different operations.
-class LoopVectorizationCostModel {
-public:
- /// C'tor.
- LoopVectorizationCostModel(Loop *Lp, ScalarEvolution *Se,
- LoopVectorizationLegality *Leg,
- const VectorTargetTransformInfo *Vtti):
- TheLoop(Lp), SE(Se), Legal(Leg), VTTI(Vtti) { }
-
- /// Returns the most profitable vectorization factor for the loop that is
- /// smaller or equal to the VF argument. This method checks every power
- /// of two up to VF.
- unsigned findBestVectorizationFactor(unsigned VF = 8);
-
-private:
- /// Returns the expected execution cost. The unit of the cost does
- /// not matter because we use the 'cost' units to compare different
- /// vector widths. The cost that is returned is *not* normalized by
- /// the factor width.
- unsigned expectedCost(unsigned VF);
-
- /// Returns the execution time cost of an instruction for a given vector
- /// width. Vector width of one means scalar.
- unsigned getInstructionCost(Instruction *I, unsigned VF);
-
- /// A helper function for converting Scalar types to vector types.
- /// If the incoming type is void, we return void. If the VF is 1, we return
- /// the scalar type.
- static Type* ToVectorTy(Type *Scalar, unsigned VF);
-
- /// The loop that we evaluate.
- Loop *TheLoop;
- /// Scev analysis.
- ScalarEvolution *SE;
+static cl::opt<bool>
+EnableIfConversion("enable-if-conversion", cl::init(true), cl::Hidden,
+ cl::desc("Enable if-conversion during vectorization."));
- /// Vectorization legality.
- LoopVectorizationLegality *Legal;
- /// Vector target information.
- const VectorTargetTransformInfo *VTTI;
-};
+namespace {
+/// The LoopVectorize Pass.
struct LoopVectorize : public LoopPass {
- static char ID; // Pass identification, replacement for typeid
+ /// Pass identification, replacement for typeid
+ static char ID;
- LoopVectorize() : LoopPass(ID) {
+ explicit LoopVectorize() : LoopPass(ID) {
initializeLoopVectorizePass(*PassRegistry::getPassRegistry());
}
L->getHeader()->getParent()->getName() << "\"\n");
// Check if it is legal to vectorize the loop.
- LoopVectorizationLegality LVL(L, SE, DL);
+ LoopVectorizationLegality LVL(L, SE, DL, DT);
if (!LVL.canVectorize()) {
DEBUG(dbgs() << "LV: Not vectorizing.\n");
return false;
}
// Select the preffered vectorization factor.
- unsigned VF = 1;
- if (VectorizationFactor == 0) {
- const VectorTargetTransformInfo *VTTI = 0;
- if (TTI)
- VTTI = TTI->getVectorTargetTransformInfo();
- // Use the cost model.
- LoopVectorizationCostModel CM(L, SE, &LVL, VTTI);
- VF = CM.findBestVectorizationFactor();
-
- if (VF == 1) {
- DEBUG(dbgs() << "LV: Vectorization is possible but not beneficial.\n");
- return false;
- }
+ const VectorTargetTransformInfo *VTTI = 0;
+ if (TTI)
+ VTTI = TTI->getVectorTargetTransformInfo();
+ // Use the cost model.
+ LoopVectorizationCostModel CM(L, SE, LI, &LVL, VTTI);
+
+ // Check the function attribues to find out if this function should be
+ // optimized for size.
+ Function *F = L->getHeader()->getParent();
+ Attribute::AttrKind SzAttr = Attribute::OptimizeForSize;
+ Attribute::AttrKind FlAttr = Attribute::NoImplicitFloat;
+ unsigned FnIndex = AttributeSet::FunctionIndex;
+ bool OptForSize = F->getAttributes().hasAttribute(FnIndex, SzAttr);
+ bool NoFloat = F->getAttributes().hasAttribute(FnIndex, FlAttr);
+
+ if (NoFloat) {
+ DEBUG(dbgs() << "LV: Can't vectorize when the NoImplicitFloat"
+ "attribute is used.\n");
+ return false;
+ }
- } else {
- // Use the user command flag.
- VF = VectorizationFactor;
+ unsigned VF = CM.selectVectorizationFactor(OptForSize, VectorizationFactor);
+ unsigned UF = CM.selectUnrollFactor(OptForSize, VectorizationUnroll);
+
+ if (VF == 1) {
+ DEBUG(dbgs() << "LV: Vectorization is possible but not beneficial.\n");
+ return false;
}
DEBUG(dbgs() << "LV: Found a vectorizable loop ("<< VF << ") in "<<
- L->getHeader()->getParent()->getParent()->getModuleIdentifier()<<
- "\n");
+ F->getParent()->getModuleIdentifier()<<"\n");
+ DEBUG(dbgs() << "LV: Unroll Factor is " << UF << "\n");
// If we decided that it is *legal* to vectorizer the loop then do it.
- SingleBlockLoopVectorizer LB(L, SE, LI, DT, &LPM, VF);
+ InnerLoopVectorizer LB(L, SE, LI, DT, DL, VF, UF);
LB.vectorize(&LVL);
DEBUG(verifyFunction(*L->getHeader()->getParent()));
};
-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);
+}// namespace
+
+//===----------------------------------------------------------------------===//
+// Implementation of LoopVectorizationLegality, InnerLoopVectorizer and
+// LoopVectorizationCostModel.
+//===----------------------------------------------------------------------===//
+
+void
+LoopVectorizationLegality::RuntimePointerCheck::insert(ScalarEvolution *SE,
+ Loop *Lp, Value *Ptr) {
+ const SCEV *Sc = SE->getSCEV(Ptr);
+ const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Sc);
+ assert(AR && "Invalid addrec expression");
+ const SCEV *Ex = SE->getExitCount(Lp, Lp->getLoopLatch());
+ const SCEV *ScEnd = AR->evaluateAtIteration(Ex, *SE);
+ Pointers.push_back(Ptr);
+ Starts.push_back(AR->getStart());
+ Ends.push_back(ScEnd);
+}
+
+Value *InnerLoopVectorizer::getBroadcastInstrs(Value *V) {
+ // Save the current insertion location.
+ Instruction *Loc = Builder.GetInsertPoint();
+
+ // We need to place the broadcast of invariant variables outside the loop.
+ Instruction *Instr = dyn_cast<Instruction>(V);
+ bool NewInstr = (Instr && Instr->getParent() == LoopVectorBody);
+ bool Invariant = OrigLoop->isLoopInvariant(V) && !NewInstr;
+
+ // Place the code for broadcasting invariant variables in the new preheader.
+ if (Invariant)
+ Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator());
+
// 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);
+ Value *Shuf = Builder.CreateVectorSplat(VF, V, "broadcast");
+
+ // Restore the builder insertion point.
+ if (Invariant)
+ Builder.SetInsertPoint(Loc);
+
return Shuf;
}
-Value *SingleBlockLoopVectorizer::getConsecutiveVector(Value* Val) {
+Value *InnerLoopVectorizer::getConsecutiveVector(Value* Val, unsigned StartIdx,
+ bool Negate) {
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();
+ int 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));
+ for (int i = 0; i < VLen; ++i) {
+ int Idx = Negate ? (-i): i;
+ Indices.push_back(ConstantInt::get(ITy, StartIdx + Idx));
+ }
// Add the consecutive indices to the vector value.
Constant *Cv = ConstantVector::get(Indices);
return Builder.CreateAdd(Val, Cv, "induction");
}
-bool LoopVectorizationLegality::isConsecutiveGep(Value *Ptr) {
+int LoopVectorizationLegality::isConsecutivePtr(Value *Ptr) {
+ assert(Ptr->getType()->isPointerTy() && "Unexpected non ptr");
+
+ // If this value is a pointer induction variable we know it is consecutive.
+ PHINode *Phi = dyn_cast_or_null<PHINode>(Ptr);
+ if (Phi && Inductions.count(Phi)) {
+ InductionInfo II = Inductions[Phi];
+ if (PtrInduction == II.IK)
+ return 1;
+ }
+
GetElementPtrInst *Gep = dyn_cast_or_null<GetElementPtrInst>(Ptr);
if (!Gep)
- return false;
+ return 0;
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)), TheLoop))
- return false;
+ return 0;
- // We can emit wide load/stores only of the last index is the induction
+ // We can emit wide load/stores only if the last index is the induction
// variable.
const SCEV *Last = SE->getSCEV(LastIndex);
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Last)) {
// The memory is consecutive because the last index is consecutive
// and all other indices are loop invariant.
if (Step->isOne())
- return true;
+ return 1;
+ if (Step->isAllOnesValue())
+ return -1;
}
- return false;
+ return 0;
+}
+
+bool LoopVectorizationLegality::isUniform(Value *V) {
+ return (SE->isLoopInvariant(SE->getSCEV(V), TheLoop));
}
-Value *SingleBlockLoopVectorizer::getVectorValue(Value *V) {
+InnerLoopVectorizer::VectorParts&
+InnerLoopVectorizer::getVectorValue(Value *V) {
+ assert(V != Induction && "The new induction variable should not be used.");
assert(!V->getType()->isVectorTy() && "Can't widen a vector");
- // If we saved a vectorized copy of V, use it.
- Value *&MapEntry = WidenMap[V];
- if (MapEntry)
- return MapEntry;
- // Broadcast V and save the value for future uses.
+ // If we have this scalar in the map, return it.
+ if (WidenMap.has(V))
+ return WidenMap.get(V);
+
+ // If this scalar is unknown, assume that it is a constant or that it is
+ // loop invariant. Broadcast V and save the value for future uses.
Value *B = getBroadcastInstrs(V);
- MapEntry = B;
- return B;
+ WidenMap.splat(V, B);
+ return WidenMap.get(V);
}
Constant*
-SingleBlockLoopVectorizer::getUniformVector(unsigned Val, Type* ScalarTy) {
- SmallVector<Constant*, 8> Indices;
- // Create a vector of consecutive numbers from zero to VF.
+InnerLoopVectorizer::getUniformVector(unsigned Val, Type* ScalarTy) {
+ return ConstantVector::getSplat(VF, ConstantInt::get(ScalarTy, Val, true));
+}
+
+Value *InnerLoopVectorizer::reverseVector(Value *Vec) {
+ assert(Vec->getType()->isVectorTy() && "Invalid type");
+ SmallVector<Constant*, 8> ShuffleMask;
for (unsigned i = 0; i < VF; ++i)
- Indices.push_back(ConstantInt::get(ScalarTy, Val, true));
+ ShuffleMask.push_back(Builder.getInt32(VF - i - 1));
- // Add the consecutive indices to the vector value.
- return ConstantVector::get(Indices);
+ return Builder.CreateShuffleVector(Vec, UndefValue::get(Vec->getType()),
+ ConstantVector::get(ShuffleMask),
+ "reverse");
}
-void SingleBlockLoopVectorizer::scalarizeInstruction(Instruction *Instr) {
+void InnerLoopVectorizer::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;
+ SmallVector<VectorParts, 4> Params;
// Find all of the vectorized parameters.
for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) {
// If we are accessing the old induction variable, use the new one.
if (SrcOp == OldInduction) {
- Params.push_back(getBroadcastInstrs(Induction));
+ Params.push_back(getVectorValue(SrcOp));
continue;
}
// 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");
+ if (SrcInst && OrigLoop->contains(SrcInst)) {
+ assert(WidenMap.has(SrcInst) && "Source operand is unavailable");
// The parameter is a vector value from earlier.
- Params.push_back(WidenMap[SrcInst]);
+ Params.push_back(WidenMap.get(SrcInst));
} else {
// The parameter is a scalar from outside the loop. Maybe even a constant.
- Params.push_back(SrcOp);
+ VectorParts Scalars;
+ Scalars.append(UF, SrcOp);
+ Params.push_back(Scalars);
}
}
// 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));
+ Value *UndefVec = IsVoidRetTy ? 0 :
+ UndefValue::get(VectorType::get(Instr->getType(), VF));
+ // Create a new entry in the WidenMap and initialize it to Undef or Null.
+ VectorParts &VecResults = WidenMap.splat(Instr, UndefVec);
// 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);
+ for (unsigned Width = 0; Width < VF; ++Width) {
+ // For each vector unroll 'part':
+ for (unsigned Part = 0; Part < UF; ++Part) {
+ 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][Part];
+ // Param is a vector. Need to extract the right lane.
+ if (Op->getType()->isVectorTy())
+ Op = Builder.CreateExtractElement(Op, Builder.getInt32(Width));
+ Cloned->setOperand(op, Op);
+ }
+
+ // Place the cloned 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[Part] = Builder.CreateInsertElement(VecResults[Part], Cloned,
+ Builder.getInt32(Width));
+ }
+ }
+}
+
+Value*
+InnerLoopVectorizer::addRuntimeCheck(LoopVectorizationLegality *Legal,
+ Instruction *Loc) {
+ LoopVectorizationLegality::RuntimePointerCheck *PtrRtCheck =
+ Legal->getRuntimePointerCheck();
+
+ if (!PtrRtCheck->Need)
+ return NULL;
+
+ Value *MemoryRuntimeCheck = 0;
+ unsigned NumPointers = PtrRtCheck->Pointers.size();
+ SmallVector<Value* , 2> Starts;
+ SmallVector<Value* , 2> Ends;
+
+ SCEVExpander Exp(*SE, "induction");
+
+ // Use this type for pointer arithmetic.
+ Type* PtrArithTy = Type::getInt8PtrTy(Loc->getContext(), 0);
+
+ for (unsigned i = 0; i < NumPointers; ++i) {
+ Value *Ptr = PtrRtCheck->Pointers[i];
+ const SCEV *Sc = SE->getSCEV(Ptr);
+
+ if (SE->isLoopInvariant(Sc, OrigLoop)) {
+ DEBUG(dbgs() << "LV: Adding RT check for a loop invariant ptr:" <<
+ *Ptr <<"\n");
+ Starts.push_back(Ptr);
+ Ends.push_back(Ptr);
+ } else {
+ DEBUG(dbgs() << "LV: Adding RT check for range:" << *Ptr <<"\n");
+
+ Value *Start = Exp.expandCodeFor(PtrRtCheck->Starts[i], PtrArithTy, Loc);
+ Value *End = Exp.expandCodeFor(PtrRtCheck->Ends[i], PtrArithTy, Loc);
+ Starts.push_back(Start);
+ Ends.push_back(End);
}
+ }
- // Place the cloned scalar in the new loop.
- Builder.Insert(Cloned);
+ for (unsigned i = 0; i < NumPointers; ++i) {
+ for (unsigned j = i+1; j < NumPointers; ++j) {
+ Instruction::CastOps Op = Instruction::BitCast;
+ Value *Start0 = CastInst::Create(Op, Starts[i], PtrArithTy, "bc", Loc);
+ Value *Start1 = CastInst::Create(Op, Starts[j], PtrArithTy, "bc", Loc);
+ Value *End0 = CastInst::Create(Op, Ends[i], PtrArithTy, "bc", Loc);
+ Value *End1 = CastInst::Create(Op, Ends[j], PtrArithTy, "bc", Loc);
+
+ Value *Cmp0 = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_ULE,
+ Start0, End1, "bound0", Loc);
+ Value *Cmp1 = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_ULE,
+ Start1, End0, "bound1", Loc);
+ Value *IsConflict = BinaryOperator::Create(Instruction::And, Cmp0, Cmp1,
+ "found.conflict", Loc);
+ if (MemoryRuntimeCheck)
+ MemoryRuntimeCheck = BinaryOperator::Create(Instruction::Or,
+ MemoryRuntimeCheck,
+ IsConflict,
+ "conflict.rdx", Loc);
+ else
+ MemoryRuntimeCheck = IsConflict;
- // 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;
+ return MemoryRuntimeCheck;
}
void
-SingleBlockLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
+InnerLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
/*
In this function we generate a new loop. The new loop will contain
the vectorized instructions while the old loop will continue to run the
scalar remainder.
- [ ] <-- vector loop bypass.
- / |
- / v
-| [ ] <-- vector pre header.
-| |
-| v
-| [ ] \
-| [ ]_| <-- vector loop.
-| |
- \ v
- >[ ] <--- middle-block.
- / |
- / v
-| [ ] <--- new preheader.
-| |
-| v
-| [ ] \
-| [ ]_| <-- old scalar loop to handle remainder.
- \ |
- \ v
- >[ ] <-- exit block.
+ [ ] <-- vector loop bypass.
+ / |
+ / v
+ | [ ] <-- vector pre header.
+ | |
+ | v
+ | [ ] \
+ | [ ]_| <-- vector loop.
+ | |
+ \ v
+ >[ ] <--- middle-block.
+ / |
+ / v
+ | [ ] <--- new preheader.
+ | |
+ | v
+ | [ ] \
+ | [ ]_| <-- old scalar loop to handle remainder.
+ \ |
+ \ v
+ >[ ] <-- exit block.
...
*/
- // This is the original scalar-loop preheader.
+ BasicBlock *OldBasicBlock = OrigLoop->getHeader();
BasicBlock *BypassBlock = OrigLoop->getLoopPreheader();
BasicBlock *ExitBlock = OrigLoop->getExitBlock();
assert(ExitBlock && "Must have an exit block");
- // The loop index does not have to start at Zero. It starts with this value.
+ // Some loops have a single integer induction variable, while other loops
+ // don't. One example is c++ iterators that often have multiple pointer
+ // induction variables. In the code below we also support a case where we
+ // don't have a single induction variable.
OldInduction = Legal->getInduction();
- Value *StartIdx = OldInduction->getIncomingValueForBlock(BypassBlock);
-
- assert(OrigLoop->getNumBlocks() == 1 && "Invalid loop");
- assert(BypassBlock && "Invalid loop structure");
-
- BasicBlock *VectorPH =
- BypassBlock->splitBasicBlock(BypassBlock->getTerminator(), "vector.ph");
- BasicBlock *VecBody = VectorPH->splitBasicBlock(VectorPH->getTerminator(),
- "vector.body");
-
- BasicBlock *MiddleBlock = VecBody->splitBasicBlock(VecBody->getTerminator(),
- "middle.block");
- BasicBlock *ScalarPH =
- MiddleBlock->splitBasicBlock(MiddleBlock->getTerminator(),
- "scalar.preheader");
- // Find the induction variable.
- BasicBlock *OldBasicBlock = OrigLoop->getHeader();
- assert(OldInduction && "We must have a single phi node.");
- Type *IdxTy = OldInduction->getType();
-
- // Use this IR builder to create the loop instructions (Phi, Br, Cmp)
- // inside the loop.
- Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
-
- // Generate the induction variable.
- Induction = Builder.CreatePHI(IdxTy, 2, "index");
- Constant *Step = ConstantInt::get(IdxTy, VF);
+ Type *IdxTy = OldInduction ? OldInduction->getType() :
+ DL->getIntPtrType(SE->getContext());
// Find the loop boundaries.
- const SCEV *ExitCount = SE->getExitCount(OrigLoop, OrigLoop->getHeader());
+ const SCEV *ExitCount = SE->getExitCount(OrigLoop, OrigLoop->getLoopLatch());
assert(ExitCount != SE->getCouldNotCompute() && "Invalid loop count");
// Get the total trip count from the count by adding 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");
+
+ // Count holds the overall loop count (N).
+ Value *Count = Exp.expandCodeFor(ExitCount, ExitCount->getType(),
+ BypassBlock->getTerminator());
+
+ // The loop index does not have to start at Zero. Find the original start
+ // value from the induction PHI node. If we don't have an induction variable
+ // then we know that it starts at zero.
+ Value *StartIdx = OldInduction ?
+ OldInduction->getIncomingValueForBlock(BypassBlock):
+ ConstantInt::get(IdxTy, 0);
+
+ assert(BypassBlock && "Invalid loop structure");
+
+ // Generate the code that checks in runtime if arrays overlap.
+ Value *MemoryRuntimeCheck = addRuntimeCheck(Legal,
+ BypassBlock->getTerminator());
+
+ // Split the single block loop into the two loop structure described above.
+ BasicBlock *VectorPH =
+ BypassBlock->splitBasicBlock(BypassBlock->getTerminator(), "vector.ph");
+ BasicBlock *VecBody =
+ VectorPH->splitBasicBlock(VectorPH->getTerminator(), "vector.body");
+ BasicBlock *MiddleBlock =
+ VecBody->splitBasicBlock(VecBody->getTerminator(), "middle.block");
+ BasicBlock *ScalarPH =
+ MiddleBlock->splitBasicBlock(MiddleBlock->getTerminator(), "scalar.ph");
+
+ // This is the location in which we add all of the logic for bypassing
+ // the new vector loop.
Instruction *Loc = BypassBlock->getTerminator();
+ // Use this IR builder to create the loop instructions (Phi, Br, Cmp)
+ // inside the loop.
+ Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
+
+ // Generate the induction variable.
+ Induction = Builder.CreatePHI(IdxTy, 2, "index");
+ // The loop step is equal to the vectorization factor (num of SIMD elements)
+ // times the unroll factor (num of SIMD instructions).
+ Constant *Step = ConstantInt::get(IdxTy, VF * UF);
+
// We may need to extend the index in case there is a type mismatch.
// We know that the count starts at zero and does not overflow.
- // We are using Zext because it should be less expensive.
- if (ExitCount->getType() != Induction->getType())
- ExitCount = SE->getZeroExtendExpr(ExitCount, IdxTy);
-
- // Count holds the overall loop count (N).
- Value *Count = Exp.expandCodeFor(ExitCount, Induction->getType(), Loc);
+ if (Count->getType() != IdxTy) {
+ // The exit count can be of pointer type. Convert it to the correct
+ // integer type.
+ if (ExitCount->getType()->isPointerTy())
+ Count = CastInst::CreatePointerCast(Count, IdxTy, "ptrcnt.to.int", Loc);
+ else
+ Count = CastInst::CreateZExtOrBitCast(Count, IdxTy, "zext.cnt", Loc);
+ }
// Add the start index to the loop count to get the new end index.
Value *IdxEnd = BinaryOperator::CreateAdd(Count, StartIdx, "end.idx", Loc);
// Now we need to generate the expression for N - (N % VF), which is
// the part that the vectorized body will execute.
- Constant *CIVF = ConstantInt::get(IdxTy, VF);
- Value *R = BinaryOperator::CreateURem(Count, CIVF, "n.mod.vf", Loc);
+ Value *R = BinaryOperator::CreateURem(Count, Step, "n.mod.vf", Loc);
Value *CountRoundDown = BinaryOperator::CreateSub(Count, R, "n.vec", Loc);
Value *IdxEndRoundDown = BinaryOperator::CreateAdd(CountRoundDown, StartIdx,
"end.idx.rnd.down", Loc);
- // Now, compare the new count to zero. If it is zero, jump to the scalar part.
+ // Now, compare the new count to zero. If it is zero skip the vector loop and
+ // jump to the scalar loop.
Value *Cmp = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ,
IdxEndRoundDown,
StartIdx,
"cmp.zero", Loc);
+
+ // If we are using memory runtime checks, include them in.
+ if (MemoryRuntimeCheck)
+ Cmp = BinaryOperator::Create(Instruction::Or, Cmp, MemoryRuntimeCheck,
+ "CntOrMem", Loc);
+
BranchInst::Create(MiddleBlock, VectorPH, Cmp, Loc);
// Remove the old terminator.
Loc->eraseFromParent();
+ // We are going to resume the execution of the scalar loop.
+ // Go over all of the induction variables that we found and fix the
+ // PHIs that are left in the scalar version of the loop.
+ // The starting values of PHI nodes depend on the counter of the last
+ // iteration in the vectorized loop.
+ // If we come from a bypass edge then we need to start from the original
+ // start value.
+
+ // This variable saves the new starting index for the scalar loop.
+ PHINode *ResumeIndex = 0;
+ LoopVectorizationLegality::InductionList::iterator I, E;
+ LoopVectorizationLegality::InductionList *List = Legal->getInductionVars();
+ for (I = List->begin(), E = List->end(); I != E; ++I) {
+ PHINode *OrigPhi = I->first;
+ LoopVectorizationLegality::InductionInfo II = I->second;
+ PHINode *ResumeVal = PHINode::Create(OrigPhi->getType(), 2, "resume.val",
+ MiddleBlock->getTerminator());
+ Value *EndValue = 0;
+ switch (II.IK) {
+ case LoopVectorizationLegality::NoInduction:
+ llvm_unreachable("Unknown induction");
+ case LoopVectorizationLegality::IntInduction: {
+ // Handle the integer induction counter:
+ assert(OrigPhi->getType()->isIntegerTy() && "Invalid type");
+ assert(OrigPhi == OldInduction && "Unknown integer PHI");
+ // We know what the end value is.
+ EndValue = IdxEndRoundDown;
+ // We also know which PHI node holds it.
+ ResumeIndex = ResumeVal;
+ break;
+ }
+ case LoopVectorizationLegality::ReverseIntInduction: {
+ // Convert the CountRoundDown variable to the PHI size.
+ unsigned CRDSize = CountRoundDown->getType()->getScalarSizeInBits();
+ unsigned IISize = II.StartValue->getType()->getScalarSizeInBits();
+ Value *CRD = CountRoundDown;
+ if (CRDSize > IISize)
+ CRD = CastInst::Create(Instruction::Trunc, CountRoundDown,
+ II.StartValue->getType(),
+ "tr.crd", BypassBlock->getTerminator());
+ else if (CRDSize < IISize)
+ CRD = CastInst::Create(Instruction::SExt, CountRoundDown,
+ II.StartValue->getType(),
+ "sext.crd", BypassBlock->getTerminator());
+ // Handle reverse integer induction counter:
+ EndValue = BinaryOperator::CreateSub(II.StartValue, CRD, "rev.ind.end",
+ BypassBlock->getTerminator());
+ break;
+ }
+ case LoopVectorizationLegality::PtrInduction: {
+ // For pointer induction variables, calculate the offset using
+ // the end index.
+ EndValue = GetElementPtrInst::Create(II.StartValue, CountRoundDown,
+ "ptr.ind.end",
+ BypassBlock->getTerminator());
+ break;
+ }
+ }// end of case
+
+ // The new PHI merges the original incoming value, in case of a bypass,
+ // or the value at the end of the vectorized loop.
+ ResumeVal->addIncoming(II.StartValue, BypassBlock);
+ ResumeVal->addIncoming(EndValue, VecBody);
+
+ // Fix the scalar body counter (PHI node).
+ unsigned BlockIdx = OrigPhi->getBasicBlockIndex(ScalarPH);
+ OrigPhi->setIncomingValue(BlockIdx, ResumeVal);
+ }
+
+ // If we are generating a new induction variable then we also need to
+ // generate the code that calculates the exit value. This value is not
+ // simply the end of the counter because we may skip the vectorized body
+ // in case of a runtime check.
+ if (!OldInduction){
+ assert(!ResumeIndex && "Unexpected resume value found");
+ ResumeIndex = PHINode::Create(IdxTy, 2, "new.indc.resume.val",
+ MiddleBlock->getTerminator());
+ ResumeIndex->addIncoming(StartIdx, BypassBlock);
+ ResumeIndex->addIncoming(IdxEndRoundDown, VecBody);
+ }
+
+ // Make sure that we found the index where scalar loop needs to continue.
+ assert(ResumeIndex && ResumeIndex->getType()->isIntegerTy() &&
+ "Invalid resume Index");
+
// Add a check in the middle block to see if we have completed
// all of the iterations in the first vector loop.
// If (N - N%VF) == N, then we *don't* need to run the remainder.
Value *CmpN = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ, IdxEnd,
- IdxEndRoundDown, "cmp.n",
+ ResumeIndex, "cmp.n",
MiddleBlock->getTerminator());
BranchInst::Create(ExitBlock, ScalarPH, CmpN, MiddleBlock->getTerminator());
// Now we have two terminators. Remove the old one from the block.
VecBody->getTerminator()->eraseFromParent();
- // Fix the scalar body iteration count.
- unsigned BlockIdx = OldInduction->getBasicBlockIndex(ScalarPH);
- OldInduction->setIncomingValue(BlockIdx, IdxEndRoundDown);
-
// Get ready to start creating new instructions into the vectorized body.
Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
- // Register the new loop.
+ // Create and register the new vector loop.
Loop* Lp = new Loop();
- LPM->insertLoop(Lp, OrigLoop->getParentLoop());
-
- Lp->addBasicBlockToLoop(VecBody, LI->getBase());
-
Loop *ParentLoop = OrigLoop->getParentLoop();
+
+ // Insert the new loop into the loop nest and register the new basic blocks.
if (ParentLoop) {
+ ParentLoop->addChildLoop(Lp);
ParentLoop->addBasicBlockToLoop(ScalarPH, LI->getBase());
ParentLoop->addBasicBlockToLoop(VectorPH, LI->getBase());
ParentLoop->addBasicBlockToLoop(MiddleBlock, LI->getBase());
+ } else {
+ LI->addTopLevelLoop(Lp);
}
+ Lp->addBasicBlockToLoop(VecBody, LI->getBase());
+
// Save the state.
LoopVectorPreHeader = VectorPH;
LoopScalarPreHeader = ScalarPH;
}
}
+static bool
+isTriviallyVectorizableIntrinsic(Instruction *Inst) {
+ IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst);
+ if (!II)
+ return false;
+ switch (II->getIntrinsicID()) {
+ case Intrinsic::sqrt:
+ case Intrinsic::sin:
+ case Intrinsic::cos:
+ case Intrinsic::exp:
+ case Intrinsic::exp2:
+ case Intrinsic::log:
+ case Intrinsic::log10:
+ case Intrinsic::log2:
+ case Intrinsic::fabs:
+ case Intrinsic::floor:
+ case Intrinsic::ceil:
+ case Intrinsic::trunc:
+ case Intrinsic::rint:
+ case Intrinsic::nearbyint:
+ case Intrinsic::pow:
+ case Intrinsic::fma:
+ case Intrinsic::fmuladd:
+ return true;
+ default:
+ return false;
+ }
+ return false;
+}
+
void
-SingleBlockLoopVectorizer::vectorizeLoop(LoopVectorizationLegality *Legal) {
+InnerLoopVectorizer::vectorizeLoop(LoopVectorizationLegality *Legal) {
//===------------------------------------------------===//
//
// Notice: any optimization or new instruction that go
// the cost-model.
//
//===------------------------------------------------===//
- typedef SmallVector<PHINode*, 4> PhiVector;
BasicBlock &BB = *OrigLoop->getHeader();
- Constant *Zero = ConstantInt::get(
- IntegerType::getInt32Ty(BB.getContext()), 0);
+ Constant *Zero =
+ ConstantInt::get(IntegerType::getInt32Ty(BB.getContext()), 0);
// In order to support reduction variables we need to be able to vectorize
// Phi nodes. Phi nodes have cycles, so we need to vectorize them in two
- // steages. First, we create a new vector PHI node with no incoming edges.
+ // stages. First, we create a new vector PHI node with no incoming edges.
// We use this value when we vectorize all of the instructions that use the
// PHI. Next, after all of the instructions in the block are complete we
// add the new incoming edges to the PHI. At this point all of the
// instructions in the basic block are vectorized, so we can use them to
// construct the PHI.
- PhiVector PHIsToFix;
-
- // 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::Br:
- // Nothing to do for PHIs and BR, since we already took care of the
- // loop control flow instructions.
- continue;
- case Instruction::PHI:{
- PHINode* P = cast<PHINode>(Inst);
- // Special handling for the induction var.
- if (OldInduction == Inst)
- continue;
- // This is phase one of vectorizing PHIs.
- // This has to be a reduction variable.
- assert(Legal->getReductionVars()->count(P) && "Not a Reduction");
- Type *VecTy = VectorType::get(Inst->getType(), VF);
- WidenMap[Inst] = Builder.CreatePHI(VecTy, 2, "vec.phi");
- PHIsToFix.push_back(P);
- 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.
- Value *V = Builder.CreateBinOp(BinOp->getOpcode(), A, B);
- WidenMap[Inst] = V;
-
- // Update the NSW, NUW and Exact flags.
- BinaryOperator *VecOp = cast<BinaryOperator>(V);
- if (isa<OverflowingBinaryOperator>(BinOp)) {
- VecOp->setHasNoSignedWrap(BinOp->hasNoSignedWrap());
- VecOp->setHasNoUnsignedWrap(BinOp->hasNoUnsignedWrap());
- }
- if (isa<PossiblyExactOperator>(VecOp))
- VecOp->setIsExact(BinOp->isExact());
- break;
- }
- case Instruction::Select: {
- // Widen selects.
- // If the selector is loop invariant we can create a select
- // instruction with a scalar condition. Otherwise, use vector-select.
- Value *Cond = Inst->getOperand(0);
- bool InvariantCond = SE->isLoopInvariant(SE->getSCEV(Cond), OrigLoop);
-
- // The condition can be loop invariant but still defined inside the
- // loop. This means that we can't just use the original 'cond' value.
- // We have to take the 'vectorized' value and pick the first lane.
- // Instcombine will make this a no-op.
- Cond = getVectorValue(Cond);
- if (InvariantCond)
- Cond = Builder.CreateExtractElement(Cond, Builder.getInt32(0));
-
- Value *Op0 = getVectorValue(Inst->getOperand(1));
- Value *Op1 = getVectorValue(Inst->getOperand(2));
- WidenMap[Inst] = Builder.CreateSelect(Cond, Op0, Op1);
- 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 (!Legal->isConsecutiveGep(Gep)) {
- scalarizeInstruction(Inst);
- break;
- }
-
- // The last index does not have to be the induction. It can be
- // consecutive and be a function of the index. For example A[I+1];
- unsigned NumOperands = Gep->getNumOperands();
- Value *LastIndex = getVectorValue(Gep->getOperand(NumOperands - 1));
- LastIndex = Builder.CreateExtractElement(LastIndex, Zero);
-
- // Create the new GEP with the new induction variable.
- GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
- Gep2->setOperand(NumOperands - 1, LastIndex);
- 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 (!Legal->isConsecutiveGep(Gep)) {
- scalarizeInstruction(Inst);
- break;
- }
-
- // The last index does not have to be the induction. It can be
- // consecutive and be a function of the index. For example A[I+1];
- unsigned NumOperands = Gep->getNumOperands();
- Value *LastIndex = getVectorValue(Gep->getOperand(NumOperands -1));
- LastIndex = Builder.CreateExtractElement(LastIndex, Zero);
+ PhiVector RdxPHIsToFix;
- // Create the new GEP with the new induction variable.
- GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
- Gep2->setOperand(NumOperands - 1, LastIndex);
- 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;
- }
+ // Scan the loop in a topological order to ensure that defs are vectorized
+ // before users.
+ LoopBlocksDFS DFS(OrigLoop);
+ DFS.perform(LI);
- default:
- /// All other instructions are unsupported. Scalarize them.
- scalarizeInstruction(Inst);
- break;
- }// end of switch.
- }// end of for_each instr.
+ // Vectorize all of the blocks in the original loop.
+ for (LoopBlocksDFS::RPOIterator bb = DFS.beginRPO(),
+ be = DFS.endRPO(); bb != be; ++bb)
+ vectorizeBlockInLoop(Legal, *bb, &RdxPHIsToFix);
- // At this point every instruction in the original loop is widended to
+ // At this point every instruction in the original loop is widened 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
// 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();
+ for (PhiVector::iterator it = RdxPHIsToFix.begin(), e = RdxPHIsToFix.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 descriptor.
assert(Legal->getReductionVars()->count(RdxPhi) &&
"Unable to find the reduction variable");
LoopVectorizationLegality::ReductionDescriptor RdxDesc =
- (*Legal->getReductionVars())[RdxPhi];
+ (*Legal->getReductionVars())[RdxPhi];
// We need to generate a reduction vector from the incoming scalar.
// To do so, we need to generate the 'identity' vector and overide
Builder.SetInsertPoint(LoopBypassBlock->getTerminator());
// This is the vector-clone of the value that leaves the loop.
- Value *VectorExit = getVectorValue(RdxDesc.LoopExitInstr);
- Type *VecTy = VectorExit->getType();
+ VectorParts &VectorExit = getVectorValue(RdxDesc.LoopExitInstr);
+ Type *VecTy = VectorExit[0]->getType();
// Find the reduction identity variable. Zero for addition, or, xor,
// one for multiplication, -1 for And.
// This vector is the Identity vector where the first element is the
// incoming scalar reduction.
Value *VectorStart = Builder.CreateInsertElement(Identity,
- RdxDesc.StartValue, Zero);
-
+ RdxDesc.StartValue, Zero);
// Fix the vector-loop phi.
// We created the induction variable so we know that the
// Reductions do not have to start at zero. They can start with
// any loop invariant values.
- VecRdxPhi->addIncoming(VectorStart, VecPreheader);
- unsigned SelfEdgeIdx = (RdxPhi)->getBasicBlockIndex(LoopScalarBody);
- Value *Val = getVectorValue(RdxPhi->getIncomingValue(SelfEdgeIdx));
- VecRdxPhi->addIncoming(Val, LoopVectorBody);
+ VectorParts &VecRdxPhi = WidenMap.get(RdxPhi);
+ BasicBlock *Latch = OrigLoop->getLoopLatch();
+ Value *LoopVal = RdxPhi->getIncomingValueForBlock(Latch);
+ VectorParts &Val = getVectorValue(LoopVal);
+ for (unsigned part = 0; part < UF; ++part) {
+ // Make sure to add the reduction stat value only to the
+ // first unroll part.
+ Value *StartVal = (part == 0) ? VectorStart : Identity;
+ cast<PHINode>(VecRdxPhi[part])->addIncoming(StartVal, VecPreheader);
+ cast<PHINode>(VecRdxPhi[part])->addIncoming(Val[part], LoopVectorBody);
+ }
// Before each round, move the insertion point right between
// the PHIs and the values we are going to write.
// instructions.
Builder.SetInsertPoint(LoopMiddleBlock->getFirstInsertionPt());
- // This PHINode contains the vectorized reduction variable, or
- // the initial value vector, if we bypass the vector loop.
- PHINode *NewPhi = Builder.CreatePHI(VecTy, 2, "rdx.vec.exit.phi");
- NewPhi->addIncoming(VectorStart, LoopBypassBlock);
- NewPhi->addIncoming(getVectorValue(RdxDesc.LoopExitInstr), LoopVectorBody);
-
- // Extract the first scalar.
- Value *Scalar0 =
- Builder.CreateExtractElement(NewPhi, Builder.getInt32(0));
- // Extract and reduce the remaining vector elements.
- for (unsigned i=1; i < VF; ++i) {
- Value *Scalar1 =
- Builder.CreateExtractElement(NewPhi, Builder.getInt32(i));
+ VectorParts RdxParts;
+ for (unsigned part = 0; part < UF; ++part) {
+ // This PHINode contains the vectorized reduction variable, or
+ // the initial value vector, if we bypass the vector loop.
+ VectorParts &RdxExitVal = getVectorValue(RdxDesc.LoopExitInstr);
+ PHINode *NewPhi = Builder.CreatePHI(VecTy, 2, "rdx.vec.exit.phi");
+ Value *StartVal = (part == 0) ? VectorStart : Identity;
+ NewPhi->addIncoming(StartVal, LoopBypassBlock);
+ NewPhi->addIncoming(RdxExitVal[part], LoopVectorBody);
+ RdxParts.push_back(NewPhi);
+ }
+
+ // Reduce all of the unrolled parts into a single vector.
+ Value *ReducedPartRdx = RdxParts[0];
+ for (unsigned part = 1; part < UF; ++part) {
+ switch (RdxDesc.Kind) {
+ case LoopVectorizationLegality::IntegerAdd:
+ ReducedPartRdx =
+ Builder.CreateAdd(RdxParts[part], ReducedPartRdx, "add.rdx");
+ break;
+ case LoopVectorizationLegality::IntegerMult:
+ ReducedPartRdx =
+ Builder.CreateMul(RdxParts[part], ReducedPartRdx, "mul.rdx");
+ break;
+ case LoopVectorizationLegality::IntegerOr:
+ ReducedPartRdx =
+ Builder.CreateOr(RdxParts[part], ReducedPartRdx, "or.rdx");
+ break;
+ case LoopVectorizationLegality::IntegerAnd:
+ ReducedPartRdx =
+ Builder.CreateAnd(RdxParts[part], ReducedPartRdx, "and.rdx");
+ break;
+ case LoopVectorizationLegality::IntegerXor:
+ ReducedPartRdx =
+ Builder.CreateXor(RdxParts[part], ReducedPartRdx, "xor.rdx");
+ break;
+ default:
+ llvm_unreachable("Unknown reduction operation");
+ }
+ }
+
+
+ // VF is a power of 2 so we can emit the reduction using log2(VF) shuffles
+ // and vector ops, reducing the set of values being computed by half each
+ // round.
+ assert(isPowerOf2_32(VF) &&
+ "Reduction emission only supported for pow2 vectors!");
+ Value *TmpVec = ReducedPartRdx;
+ SmallVector<Constant*, 32> ShuffleMask(VF, 0);
+ for (unsigned i = VF; i != 1; i >>= 1) {
+ // Move the upper half of the vector to the lower half.
+ for (unsigned j = 0; j != i/2; ++j)
+ ShuffleMask[j] = Builder.getInt32(i/2 + j);
+
+ // Fill the rest of the mask with undef.
+ std::fill(&ShuffleMask[i/2], ShuffleMask.end(),
+ UndefValue::get(Builder.getInt32Ty()));
+
+ Value *Shuf =
+ Builder.CreateShuffleVector(TmpVec,
+ UndefValue::get(TmpVec->getType()),
+ ConstantVector::get(ShuffleMask),
+ "rdx.shuf");
+
+ // Emit the operation on the shuffled value.
switch (RdxDesc.Kind) {
- case LoopVectorizationLegality::IntegerAdd:
- Scalar0 = Builder.CreateAdd(Scalar0, Scalar1);
- break;
- case LoopVectorizationLegality::IntegerMult:
- Scalar0 = Builder.CreateMul(Scalar0, Scalar1);
- break;
- case LoopVectorizationLegality::IntegerOr:
- Scalar0 = Builder.CreateOr(Scalar0, Scalar1);
- break;
- case LoopVectorizationLegality::IntegerAnd:
- Scalar0 = Builder.CreateAnd(Scalar0, Scalar1);
- break;
- case LoopVectorizationLegality::IntegerXor:
- Scalar0 = Builder.CreateXor(Scalar0, Scalar1);
- break;
- default:
- llvm_unreachable("Unknown reduction operation");
+ case LoopVectorizationLegality::IntegerAdd:
+ TmpVec = Builder.CreateAdd(TmpVec, Shuf, "add.rdx");
+ break;
+ case LoopVectorizationLegality::IntegerMult:
+ TmpVec = Builder.CreateMul(TmpVec, Shuf, "mul.rdx");
+ break;
+ case LoopVectorizationLegality::IntegerOr:
+ TmpVec = Builder.CreateOr(TmpVec, Shuf, "or.rdx");
+ break;
+ case LoopVectorizationLegality::IntegerAnd:
+ TmpVec = Builder.CreateAnd(TmpVec, Shuf, "and.rdx");
+ break;
+ case LoopVectorizationLegality::IntegerXor:
+ TmpVec = Builder.CreateXor(TmpVec, Shuf, "xor.rdx");
+ break;
+ default:
+ llvm_unreachable("Unknown reduction operation");
}
}
+ // The result is in the first element of the vector.
+ Value *Scalar0 = Builder.CreateExtractElement(TmpVec, Builder.getInt32(0));
+
// 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
// 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.
+ int IncomingEdgeBlockIdx =
+ (RdxPhi)->getBasicBlockIndex(OrigLoop->getLoopLatch());
+ assert(IncomingEdgeBlockIdx >= 0 && "Invalid block index");
+ // Pick the other block.
+ int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1);
(RdxPhi)->setIncomingValue(SelfEdgeBlockIdx, Scalar0);
(RdxPhi)->setIncomingValue(IncomingEdgeBlockIdx, RdxDesc.LoopExitInstr);
}// end of for each redux variable.
+
+ // The Loop exit block may have single value PHI nodes where the incoming
+ // value is 'undef'. While vectorizing we only handled real values that
+ // were defined inside the loop. Here we handle the 'undef case'.
+ // See PR14725.
+ for (BasicBlock::iterator LEI = LoopExitBlock->begin(),
+ LEE = LoopExitBlock->end(); LEI != LEE; ++LEI) {
+ PHINode *LCSSAPhi = dyn_cast<PHINode>(LEI);
+ if (!LCSSAPhi) continue;
+ if (LCSSAPhi->getNumIncomingValues() == 1)
+ LCSSAPhi->addIncoming(UndefValue::get(LCSSAPhi->getType()),
+ LoopMiddleBlock);
+ }
}
-void SingleBlockLoopVectorizer::updateAnalysis() {
- // The original basic block.
- SE->forgetLoop(OrigLoop);
+InnerLoopVectorizer::VectorParts
+InnerLoopVectorizer::createEdgeMask(BasicBlock *Src, BasicBlock *Dst) {
+ assert(std::find(pred_begin(Dst), pred_end(Dst), Src) != pred_end(Dst) &&
+ "Invalid edge");
- // Update the dominator tree information.
- assert(DT->properlyDominates(LoopBypassBlock, LoopExitBlock) &&
- "Entry does not dominate exit.");
+ VectorParts SrcMask = createBlockInMask(Src);
- DT->addNewBlock(LoopVectorPreHeader, LoopBypassBlock);
- DT->addNewBlock(LoopVectorBody, LoopVectorPreHeader);
- DT->addNewBlock(LoopMiddleBlock, LoopBypassBlock);
- DT->addNewBlock(LoopScalarPreHeader, LoopMiddleBlock);
- DT->changeImmediateDominator(LoopScalarBody, LoopScalarPreHeader);
- DT->changeImmediateDominator(LoopExitBlock, LoopMiddleBlock);
+ // The terminator has to be a branch inst!
+ BranchInst *BI = dyn_cast<BranchInst>(Src->getTerminator());
+ assert(BI && "Unexpected terminator found");
- DEBUG(DT->verifyAnalysis());
-}
+ if (BI->isConditional()) {
+ VectorParts EdgeMask = getVectorValue(BI->getCondition());
-bool LoopVectorizationLegality::canVectorize() {
- if (!TheLoop->getLoopPreheader()) {
- assert(false && "No preheader!!");
- DEBUG(dbgs() << "LV: Loop not normalized." << "\n");
- return false;
+ if (BI->getSuccessor(0) != Dst)
+ for (unsigned part = 0; part < UF; ++part)
+ EdgeMask[part] = Builder.CreateNot(EdgeMask[part]);
+
+ for (unsigned part = 0; part < UF; ++part)
+ EdgeMask[part] = Builder.CreateAnd(EdgeMask[part], SrcMask[part]);
+ return EdgeMask;
}
- // We can only vectorize single basic block loops.
- unsigned NumBlocks = TheLoop->getNumBlocks();
- if (NumBlocks != 1) {
- DEBUG(dbgs() << "LV: Too many blocks:" << NumBlocks << "\n");
+ return SrcMask;
+}
+
+InnerLoopVectorizer::VectorParts
+InnerLoopVectorizer::createBlockInMask(BasicBlock *BB) {
+ assert(OrigLoop->contains(BB) && "Block is not a part of a loop");
+
+ // Loop incoming mask is all-one.
+ if (OrigLoop->getHeader() == BB) {
+ Value *C = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 1);
+ return getVectorValue(C);
+ }
+
+ // This is the block mask. We OR all incoming edges, and with zero.
+ Value *Zero = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 0);
+ VectorParts BlockMask = getVectorValue(Zero);
+
+ // For each pred:
+ for (pred_iterator it = pred_begin(BB), e = pred_end(BB); it != e; ++it) {
+ VectorParts EM = createEdgeMask(*it, BB);
+ for (unsigned part = 0; part < UF; ++part)
+ BlockMask[part] = Builder.CreateOr(BlockMask[part], EM[part]);
+ }
+
+ return BlockMask;
+}
+
+void
+InnerLoopVectorizer::vectorizeBlockInLoop(LoopVectorizationLegality *Legal,
+ BasicBlock *BB, PhiVector *PV) {
+ Constant *Zero = Builder.getInt32(0);
+
+ // For each instruction in the old loop.
+ for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
+ VectorParts &Entry = WidenMap.get(it);
+ switch (it->getOpcode()) {
+ case Instruction::Br:
+ // Nothing to do for PHIs and BR, since we already took care of the
+ // loop control flow instructions.
+ continue;
+ case Instruction::PHI:{
+ PHINode* P = cast<PHINode>(it);
+ // Handle reduction variables:
+ if (Legal->getReductionVars()->count(P)) {
+ for (unsigned part = 0; part < UF; ++part) {
+ // This is phase one of vectorizing PHIs.
+ Type *VecTy = VectorType::get(it->getType(), VF);
+ Entry[part] = PHINode::Create(VecTy, 2, "vec.phi",
+ LoopVectorBody-> getFirstInsertionPt());
+ }
+ PV->push_back(P);
+ continue;
+ }
+
+ // Check for PHI nodes that are lowered to vector selects.
+ if (P->getParent() != OrigLoop->getHeader()) {
+ // We know that all PHIs in non header blocks are converted into
+ // selects, so we don't have to worry about the insertion order and we
+ // can just use the builder.
+
+ // At this point we generate the predication tree. There may be
+ // duplications since this is a simple recursive scan, but future
+ // optimizations will clean it up.
+ VectorParts Cond = createEdgeMask(P->getIncomingBlock(0),
+ P->getParent());
+
+ for (unsigned part = 0; part < UF; ++part) {
+ VectorParts &In0 = getVectorValue(P->getIncomingValue(0));
+ VectorParts &In1 = getVectorValue(P->getIncomingValue(1));
+ Entry[part] = Builder.CreateSelect(Cond[part], In0[part], In1[part],
+ "predphi");
+ }
+ continue;
+ }
+
+ // This PHINode must be an induction variable.
+ // Make sure that we know about it.
+ assert(Legal->getInductionVars()->count(P) &&
+ "Not an induction variable");
+
+ LoopVectorizationLegality::InductionInfo II =
+ Legal->getInductionVars()->lookup(P);
+
+ switch (II.IK) {
+ case LoopVectorizationLegality::NoInduction:
+ llvm_unreachable("Unknown induction");
+ case LoopVectorizationLegality::IntInduction: {
+ assert(P == OldInduction && "Unexpected PHI");
+ Value *Broadcasted = getBroadcastInstrs(Induction);
+ // After broadcasting the induction variable we need to make the
+ // vector consecutive by adding 0, 1, 2 ...
+ for (unsigned part = 0; part < UF; ++part)
+ Entry[part] = getConsecutiveVector(Broadcasted, VF * part, false);
+ continue;
+ }
+ case LoopVectorizationLegality::ReverseIntInduction:
+ case LoopVectorizationLegality::PtrInduction:
+ // Handle reverse integer and pointer inductions.
+ Value *StartIdx = 0;
+ // If we have a single integer induction variable then use it.
+ // Otherwise, start counting at zero.
+ if (OldInduction) {
+ LoopVectorizationLegality::InductionInfo OldII =
+ Legal->getInductionVars()->lookup(OldInduction);
+ StartIdx = OldII.StartValue;
+ } else {
+ StartIdx = ConstantInt::get(Induction->getType(), 0);
+ }
+ // This is the normalized GEP that starts counting at zero.
+ Value *NormalizedIdx = Builder.CreateSub(Induction, StartIdx,
+ "normalized.idx");
+
+ // Handle the reverse integer induction variable case.
+ if (LoopVectorizationLegality::ReverseIntInduction == II.IK) {
+ IntegerType *DstTy = cast<IntegerType>(II.StartValue->getType());
+ Value *CNI = Builder.CreateSExtOrTrunc(NormalizedIdx, DstTy,
+ "resize.norm.idx");
+ Value *ReverseInd = Builder.CreateSub(II.StartValue, CNI,
+ "reverse.idx");
+
+ // This is a new value so do not hoist it out.
+ Value *Broadcasted = getBroadcastInstrs(ReverseInd);
+ // After broadcasting the induction variable we need to make the
+ // vector consecutive by adding ... -3, -2, -1, 0.
+ for (unsigned part = 0; part < UF; ++part)
+ Entry[part] = getConsecutiveVector(Broadcasted, -VF * part, true);
+ continue;
+ }
+
+ // Handle the pointer induction variable case.
+ assert(P->getType()->isPointerTy() && "Unexpected type.");
+
+ // This is the vector of results. Notice that we don't generate
+ // vector geps because scalar geps result in better code.
+ for (unsigned part = 0; part < UF; ++part) {
+ Value *VecVal = UndefValue::get(VectorType::get(P->getType(), VF));
+ for (unsigned int i = 0; i < VF; ++i) {
+ Constant *Idx = ConstantInt::get(Induction->getType(),
+ i + part * VF);
+ Value *GlobalIdx = Builder.CreateAdd(NormalizedIdx, Idx,
+ "gep.idx");
+ Value *SclrGep = Builder.CreateGEP(II.StartValue, GlobalIdx,
+ "next.gep");
+ VecVal = Builder.CreateInsertElement(VecVal, SclrGep,
+ Builder.getInt32(i),
+ "insert.gep");
+ }
+ Entry[part] = VecVal;
+ }
+ continue;
+ }
+
+ }// End of PHI.
+
+ 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>(it);
+ VectorParts &A = getVectorValue(it->getOperand(0));
+ VectorParts &B = getVectorValue(it->getOperand(1));
+
+ // Use this vector value for all users of the original instruction.
+ for (unsigned Part = 0; Part < UF; ++Part) {
+ Value *V = Builder.CreateBinOp(BinOp->getOpcode(), A[Part], B[Part]);
+
+ // Update the NSW, NUW and Exact flags.
+ BinaryOperator *VecOp = cast<BinaryOperator>(V);
+ if (isa<OverflowingBinaryOperator>(BinOp)) {
+ VecOp->setHasNoSignedWrap(BinOp->hasNoSignedWrap());
+ VecOp->setHasNoUnsignedWrap(BinOp->hasNoUnsignedWrap());
+ }
+ if (isa<PossiblyExactOperator>(VecOp))
+ VecOp->setIsExact(BinOp->isExact());
+
+ Entry[Part] = V;
+ }
+ break;
+ }
+ case Instruction::Select: {
+ // Widen selects.
+ // If the selector is loop invariant we can create a select
+ // instruction with a scalar condition. Otherwise, use vector-select.
+ bool InvariantCond = SE->isLoopInvariant(SE->getSCEV(it->getOperand(0)),
+ OrigLoop);
+
+ // The condition can be loop invariant but still defined inside the
+ // loop. This means that we can't just use the original 'cond' value.
+ // We have to take the 'vectorized' value and pick the first lane.
+ // Instcombine will make this a no-op.
+ VectorParts &Cond = getVectorValue(it->getOperand(0));
+ VectorParts &Op0 = getVectorValue(it->getOperand(1));
+ VectorParts &Op1 = getVectorValue(it->getOperand(2));
+ Value *ScalarCond = Builder.CreateExtractElement(Cond[0],
+ Builder.getInt32(0));
+ for (unsigned Part = 0; Part < UF; ++Part) {
+ Entry[Part] = Builder.CreateSelect(
+ InvariantCond ? ScalarCond : Cond[Part],
+ Op0[Part],
+ Op1[Part]);
+ }
+ break;
+ }
+
+ case Instruction::ICmp:
+ case Instruction::FCmp: {
+ // Widen compares. Generate vector compares.
+ bool FCmp = (it->getOpcode() == Instruction::FCmp);
+ CmpInst *Cmp = dyn_cast<CmpInst>(it);
+ VectorParts &A = getVectorValue(it->getOperand(0));
+ VectorParts &B = getVectorValue(it->getOperand(1));
+ for (unsigned Part = 0; Part < UF; ++Part) {
+ Value *C = 0;
+ if (FCmp)
+ C = Builder.CreateFCmp(Cmp->getPredicate(), A[Part], B[Part]);
+ else
+ C = Builder.CreateICmp(Cmp->getPredicate(), A[Part], B[Part]);
+ Entry[Part] = C;
+ }
+ break;
+ }
+
+ case Instruction::Store: {
+ // Attempt to issue a wide store.
+ StoreInst *SI = dyn_cast<StoreInst>(it);
+ Type *StTy = VectorType::get(SI->getValueOperand()->getType(), VF);
+ Value *Ptr = SI->getPointerOperand();
+ unsigned Alignment = SI->getAlignment();
+
+ assert(!Legal->isUniform(Ptr) &&
+ "We do not allow storing to uniform addresses");
+
+
+ int Stride = Legal->isConsecutivePtr(Ptr);
+ bool Reverse = Stride < 0;
+ if (Stride == 0) {
+ scalarizeInstruction(it);
+ break;
+ }
+
+ // Handle consecutive stores.
+
+ GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr);
+ if (Gep) {
+ // The last index does not have to be the induction. It can be
+ // consecutive and be a function of the index. For example A[I+1];
+ unsigned NumOperands = Gep->getNumOperands();
+
+ Value *LastGepOperand = Gep->getOperand(NumOperands - 1);
+ VectorParts &GEPParts = getVectorValue(LastGepOperand);
+ Value *LastIndex = GEPParts[0];
+ LastIndex = Builder.CreateExtractElement(LastIndex, Zero);
+
+ // Create the new GEP with the new induction variable.
+ GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
+ Gep2->setOperand(NumOperands - 1, LastIndex);
+ Ptr = Builder.Insert(Gep2);
+ } else {
+ // Use the induction element ptr.
+ assert(isa<PHINode>(Ptr) && "Invalid induction ptr");
+ VectorParts &PtrVal = getVectorValue(Ptr);
+ Ptr = Builder.CreateExtractElement(PtrVal[0], Zero);
+ }
+
+ VectorParts &StoredVal = getVectorValue(SI->getValueOperand());
+ for (unsigned Part = 0; Part < UF; ++Part) {
+ // Calculate the pointer for the specific unroll-part.
+ Value *PartPtr = Builder.CreateGEP(Ptr, Builder.getInt32(Part * VF));
+
+ if (Reverse) {
+ // If we store to reverse consecutive memory locations then we need
+ // to reverse the order of elements in the stored value.
+ StoredVal[Part] = reverseVector(StoredVal[Part]);
+ // If the address is consecutive but reversed, then the
+ // wide store needs to start at the last vector element.
+ PartPtr = Builder.CreateGEP(Ptr, Builder.getInt32(-Part * VF));
+ PartPtr = Builder.CreateGEP(PartPtr, Builder.getInt32(1 - VF));
+ }
+
+ Value *VecPtr = Builder.CreateBitCast(PartPtr, StTy->getPointerTo());
+ Builder.CreateStore(StoredVal[Part], VecPtr)->setAlignment(Alignment);
+ }
+ break;
+ }
+ case Instruction::Load: {
+ // Attempt to issue a wide load.
+ LoadInst *LI = dyn_cast<LoadInst>(it);
+ Type *RetTy = VectorType::get(LI->getType(), VF);
+ Value *Ptr = LI->getPointerOperand();
+ unsigned Alignment = LI->getAlignment();
+
+ // If the pointer is loop invariant or if it is non consecutive,
+ // scalarize the load.
+ int Stride = Legal->isConsecutivePtr(Ptr);
+ bool Reverse = Stride < 0;
+ if (Legal->isUniform(Ptr) || Stride == 0) {
+ scalarizeInstruction(it);
+ break;
+ }
+
+ GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr);
+ if (Gep) {
+ // The last index does not have to be the induction. It can be
+ // consecutive and be a function of the index. For example A[I+1];
+ unsigned NumOperands = Gep->getNumOperands();
+
+ Value *LastGepOperand = Gep->getOperand(NumOperands - 1);
+ VectorParts &GEPParts = getVectorValue(LastGepOperand);
+ Value *LastIndex = GEPParts[0];
+ LastIndex = Builder.CreateExtractElement(LastIndex, Zero);
+
+ // Create the new GEP with the new induction variable.
+ GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
+ Gep2->setOperand(NumOperands - 1, LastIndex);
+ Ptr = Builder.Insert(Gep2);
+ } else {
+ // Use the induction element ptr.
+ assert(isa<PHINode>(Ptr) && "Invalid induction ptr");
+ VectorParts &PtrVal = getVectorValue(Ptr);
+ Ptr = Builder.CreateExtractElement(PtrVal[0], Zero);
+ }
+
+ for (unsigned Part = 0; Part < UF; ++Part) {
+ // Calculate the pointer for the specific unroll-part.
+ Value *PartPtr = Builder.CreateGEP(Ptr, Builder.getInt32(Part * VF));
+
+ if (Reverse) {
+ // If the address is consecutive but reversed, then the
+ // wide store needs to start at the last vector element.
+ PartPtr = Builder.CreateGEP(Ptr, Builder.getInt32(-Part * VF));
+ PartPtr = Builder.CreateGEP(PartPtr, Builder.getInt32(1 - VF));
+ }
+
+ Value *VecPtr = Builder.CreateBitCast(PartPtr, RetTy->getPointerTo());
+ Value *LI = Builder.CreateLoad(VecPtr, "wide.load");
+ cast<LoadInst>(LI)->setAlignment(Alignment);
+ Entry[Part] = Reverse ? reverseVector(LI) : 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: {
+ CastInst *CI = dyn_cast<CastInst>(it);
+ /// Optimize the special case where the source is the induction
+ /// variable. Notice that we can only optimize the 'trunc' case
+ /// because: a. FP conversions lose precision, b. sext/zext may wrap,
+ /// c. other casts depend on pointer size.
+ if (CI->getOperand(0) == OldInduction &&
+ it->getOpcode() == Instruction::Trunc) {
+ Value *ScalarCast = Builder.CreateCast(CI->getOpcode(), Induction,
+ CI->getType());
+ Value *Broadcasted = getBroadcastInstrs(ScalarCast);
+ for (unsigned Part = 0; Part < UF; ++Part)
+ Entry[Part] = getConsecutiveVector(Broadcasted, VF * Part, false);
+ break;
+ }
+ /// Vectorize casts.
+ Type *DestTy = VectorType::get(CI->getType()->getScalarType(), VF);
+
+ VectorParts &A = getVectorValue(it->getOperand(0));
+ for (unsigned Part = 0; Part < UF; ++Part)
+ Entry[Part] = Builder.CreateCast(CI->getOpcode(), A[Part], DestTy);
+ break;
+ }
+
+ case Instruction::Call: {
+ assert(isTriviallyVectorizableIntrinsic(it));
+ Module *M = BB->getParent()->getParent();
+ IntrinsicInst *II = cast<IntrinsicInst>(it);
+ Intrinsic::ID ID = II->getIntrinsicID();
+ for (unsigned Part = 0; Part < UF; ++Part) {
+ SmallVector<Value*, 4> Args;
+ for (unsigned i = 0, ie = II->getNumArgOperands(); i != ie; ++i) {
+ VectorParts &Arg = getVectorValue(II->getArgOperand(i));
+ Args.push_back(Arg[Part]);
+ }
+ Type *Tys[] = { VectorType::get(II->getType()->getScalarType(), VF) };
+ Function *F = Intrinsic::getDeclaration(M, ID, Tys);
+ Entry[Part] = Builder.CreateCall(F, Args);
+ }
+ break;
+ }
+
+ default:
+ // All other instructions are unsupported. Scalarize them.
+ scalarizeInstruction(it);
+ break;
+ }// end of switch.
+ }// end of for_each instr.
+}
+
+void InnerLoopVectorizer::updateAnalysis() {
+ // Forget the original basic block.
+ SE->forgetLoop(OrigLoop);
+
+ // Update the dominator tree information.
+ assert(DT->properlyDominates(LoopBypassBlock, LoopExitBlock) &&
+ "Entry does not dominate exit.");
+
+ DT->addNewBlock(LoopVectorPreHeader, LoopBypassBlock);
+ DT->addNewBlock(LoopVectorBody, LoopVectorPreHeader);
+ DT->addNewBlock(LoopMiddleBlock, LoopBypassBlock);
+ DT->addNewBlock(LoopScalarPreHeader, LoopMiddleBlock);
+ DT->changeImmediateDominator(LoopScalarBody, LoopScalarPreHeader);
+ DT->changeImmediateDominator(LoopExitBlock, LoopMiddleBlock);
+
+ DEBUG(DT->verifyAnalysis());
+}
+
+bool LoopVectorizationLegality::canVectorizeWithIfConvert() {
+ if (!EnableIfConversion)
return false;
+
+ assert(TheLoop->getNumBlocks() > 1 && "Single block loops are vectorizable");
+ std::vector<BasicBlock*> &LoopBlocks = TheLoop->getBlocksVector();
+
+ // Collect the blocks that need predication.
+ for (unsigned i = 0, e = LoopBlocks.size(); i < e; ++i) {
+ BasicBlock *BB = LoopBlocks[i];
+
+ // We don't support switch statements inside loops.
+ if (!isa<BranchInst>(BB->getTerminator()))
+ return false;
+
+ // We must have at most two predecessors because we need to convert
+ // all PHIs to selects.
+ unsigned Preds = std::distance(pred_begin(BB), pred_end(BB));
+ if (Preds > 2)
+ return false;
+
+ // We must be able to predicate all blocks that need to be predicated.
+ if (blockNeedsPredication(BB) && !blockCanBePredicated(BB))
+ return false;
}
- // We need to have a loop header.
- BasicBlock *BB = TheLoop->getHeader();
- DEBUG(dbgs() << "LV: Found a loop: " << BB->getName() << "\n");
+ // We can if-convert this loop.
+ return true;
+}
- // Go over each instruction and look at memory deps.
- if (!canVectorizeBlock(*BB)) {
- DEBUG(dbgs() << "LV: Can't vectorize this loop header\n");
+bool LoopVectorizationLegality::canVectorize() {
+ assert(TheLoop->getLoopPreheader() && "No preheader!!");
+
+ // We can only vectorize innermost loops.
+ if (TheLoop->getSubLoopsVector().size())
+ return false;
+
+ // We must have a single backedge.
+ if (TheLoop->getNumBackEdges() != 1)
+ return false;
+
+ // We must have a single exiting block.
+ if (!TheLoop->getExitingBlock())
+ return false;
+
+ unsigned NumBlocks = TheLoop->getNumBlocks();
+
+ // Check if we can if-convert non single-bb loops.
+ if (NumBlocks != 1 && !canVectorizeWithIfConvert()) {
+ DEBUG(dbgs() << "LV: Can't if-convert the loop.\n");
return false;
}
+ // We need to have a loop header.
+ BasicBlock *Latch = TheLoop->getLoopLatch();
+ DEBUG(dbgs() << "LV: Found a loop: " <<
+ TheLoop->getHeader()->getName() << "\n");
+
// ScalarEvolution needs to be able to find the exit count.
- const SCEV *ExitCount = SE->getExitCount(TheLoop, BB);
+ const SCEV *ExitCount = SE->getExitCount(TheLoop, Latch);
if (ExitCount == SE->getCouldNotCompute()) {
DEBUG(dbgs() << "LV: SCEV could not compute the loop exit count.\n");
return false;
}
// Do not loop-vectorize loops with a tiny trip count.
- unsigned TC = SE->getSmallConstantTripCount(TheLoop, BB);
+ unsigned TC = SE->getSmallConstantTripCount(TheLoop, Latch);
if (TC > 0u && TC < TinyTripCountThreshold) {
DEBUG(dbgs() << "LV: Found a loop with a very small trip count. " <<
"This loop is not worth vectorizing.\n");
return false;
}
- DEBUG(dbgs() << "LV: We can vectorize this loop!\n");
+ // Check if we can vectorize the instructions and CFG in this loop.
+ if (!canVectorizeInstrs()) {
+ DEBUG(dbgs() << "LV: Can't vectorize the instructions or CFG\n");
+ return false;
+ }
+
+ // Go over each instruction and look at memory deps.
+ if (!canVectorizeMemory()) {
+ DEBUG(dbgs() << "LV: Can't vectorize due to memory conflicts\n");
+ return false;
+ }
+
+ // Collect all of the variables that remain uniform after vectorization.
+ collectLoopUniforms();
+
+ DEBUG(dbgs() << "LV: We can vectorize this loop" <<
+ (PtrRtCheck.Need ? " (with a runtime bound check)" : "")
+ <<"!\n");
// Okay! We can vectorize. At this point we don't have any other mem analysis
// which may limit our maximum vectorization factor, so just return true with
return true;
}
-bool LoopVectorizationLegality::canVectorizeBlock(BasicBlock &BB) {
- // Scan the instructions in the block and look for hazards.
- for (BasicBlock::iterator it = BB.begin(), e = BB.end(); it != e; ++it) {
- Instruction *I = it;
+bool LoopVectorizationLegality::canVectorizeInstrs() {
+ BasicBlock *PreHeader = TheLoop->getLoopPreheader();
+ BasicBlock *Header = TheLoop->getHeader();
- PHINode *Phi = dyn_cast<PHINode>(I);
- if (Phi) {
- // 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;
- }
+ // For each block in the loop.
+ for (Loop::block_iterator bb = TheLoop->block_begin(),
+ be = TheLoop->block_end(); bb != be; ++bb) {
+
+ // Scan the instructions in the block and look for hazards.
+ for (BasicBlock::iterator it = (*bb)->begin(), e = (*bb)->end(); it != e;
+ ++it) {
- if (isInductionVariable(Phi)) {
- if (Induction) {
- DEBUG(dbgs() << "LV: Found too many inductions."<< *Phi <<"\n");
+ if (PHINode *Phi = dyn_cast<PHINode>(it)) {
+ // This should not happen because the loop should be normalized.
+ if (Phi->getNumIncomingValues() != 2) {
+ DEBUG(dbgs() << "LV: Found an invalid PHI.\n");
return false;
}
- DEBUG(dbgs() << "LV: Found the induction PHI."<< *Phi <<"\n");
- Induction = Phi;
- continue;
- }
- if (AddReductionVar(Phi, IntegerAdd)) {
- DEBUG(dbgs() << "LV: Found an ADD reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, IntegerMult)) {
- DEBUG(dbgs() << "LV: Found a MUL reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, IntegerOr)) {
- DEBUG(dbgs() << "LV: Found an OR reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, IntegerAnd)) {
- DEBUG(dbgs() << "LV: Found an AND reduction PHI."<< *Phi <<"\n");
- continue;
- }
- if (AddReductionVar(Phi, IntegerXor)) {
- DEBUG(dbgs() << "LV: Found a XOR reduction PHI."<< *Phi <<"\n");
- continue;
- }
- DEBUG(dbgs() << "LV: Found an unidentified PHI."<< *Phi <<"\n");
- return false;
- }// end of PHI handling
+ // Check that this PHI type is allowed.
+ if (!Phi->getType()->isIntegerTy() &&
+ !Phi->getType()->isPointerTy()) {
+ DEBUG(dbgs() << "LV: Found an non-int non-pointer PHI.\n");
+ return false;
+ }
- // We still don't handle functions.
- CallInst *CI = dyn_cast<CallInst>(I);
- if (CI) {
- DEBUG(dbgs() << "LV: Found a call site.\n");
- return false;
- }
+ // If this PHINode is not in the header block, then we know that we
+ // can convert it to select during if-conversion. No need to check if
+ // the PHIs in this block are induction or reduction variables.
+ if (*bb != Header)
+ continue;
- // We do not re-vectorize vectors.
- if (!VectorType::isValidElementType(I->getType()) &&
- !I->getType()->isVoidTy()) {
- DEBUG(dbgs() << "LV: Found unvectorizable type." << "\n");
- return false;
- }
+ // This is the value coming from the preheader.
+ Value *StartValue = Phi->getIncomingValueForBlock(PreHeader);
+ // Check if this is an induction variable.
+ InductionKind IK = isInductionVariable(Phi);
+
+ if (NoInduction != IK) {
+ // Int inductions are special because we only allow one IV.
+ if (IK == IntInduction) {
+ if (Induction) {
+ DEBUG(dbgs() << "LV: Found too many inductions."<< *Phi <<"\n");
+ return false;
+ }
+ Induction = Phi;
+ }
+
+ DEBUG(dbgs() << "LV: Found an induction variable.\n");
+ Inductions[Phi] = InductionInfo(StartValue, IK);
+ continue;
+ }
+
+ if (AddReductionVar(Phi, IntegerAdd)) {
+ DEBUG(dbgs() << "LV: Found an ADD reduction PHI."<< *Phi <<"\n");
+ continue;
+ }
+ if (AddReductionVar(Phi, IntegerMult)) {
+ DEBUG(dbgs() << "LV: Found a MUL reduction PHI."<< *Phi <<"\n");
+ continue;
+ }
+ if (AddReductionVar(Phi, IntegerOr)) {
+ DEBUG(dbgs() << "LV: Found an OR reduction PHI."<< *Phi <<"\n");
+ continue;
+ }
+ if (AddReductionVar(Phi, IntegerAnd)) {
+ DEBUG(dbgs() << "LV: Found an AND reduction PHI."<< *Phi <<"\n");
+ continue;
+ }
+ if (AddReductionVar(Phi, IntegerXor)) {
+ DEBUG(dbgs() << "LV: Found a XOR reduction PHI."<< *Phi <<"\n");
+ continue;
+ }
- // 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");
+ DEBUG(dbgs() << "LV: Found an unidentified PHI."<< *Phi <<"\n");
+ return false;
+ }// end of PHI handling
+
+ // We still don't handle functions.
+ CallInst *CI = dyn_cast<CallInst>(it);
+ if (CI && !isTriviallyVectorizableIntrinsic(it)) {
+ DEBUG(dbgs() << "LV: Found a call site.\n");
+ return false;
+ }
+
+ // Check that the instruction return type is vectorizable.
+ if (!VectorType::isValidElementType(it->getType()) &&
+ !it->getType()->isVoidTy()) {
+ DEBUG(dbgs() << "LV: Found unvectorizable type." << "\n");
+ return false;
+ }
+
+ // Check that the stored type is vectorizable.
+ if (StoreInst *ST = dyn_cast<StoreInst>(it)) {
+ Type *T = ST->getValueOperand()->getType();
+ if (!VectorType::isValidElementType(T))
return false;
+ }
+
+ // Reduction instructions are allowed to have exit users.
+ // All other instructions must not have external users.
+ if (!AllowedExit.count(it))
+ //Check that all of the users of the loop are inside the BB.
+ for (Value::use_iterator I = it->use_begin(), E = it->use_end();
+ I != E; ++I) {
+ Instruction *U = cast<Instruction>(*I);
+ // This user may be a reduction exit value.
+ if (!TheLoop->contains(U)) {
+ DEBUG(dbgs() << "LV: Found an outside user for : "<< *U << "\n");
+ return false;
+ }
}
- }
- } // next instr.
+ } // next instr.
+
+ }
if (!Induction) {
- DEBUG(dbgs() << "LV: Did not find an induction var.\n");
- return false;
+ DEBUG(dbgs() << "LV: Did not find one integer induction var.\n");
+ assert(getInductionVars()->size() && "No induction variables");
}
- // Don't vectorize if the memory dependencies do not allow vectorization.
- if (!canVectorizeMemory(BB))
- return false;
+ return true;
+}
+void LoopVectorizationLegality::collectLoopUniforms() {
// We now know that the loop is vectorizable!
// Collect variables that will remain uniform after vectorization.
std::vector<Value*> Worklist;
+ BasicBlock *Latch = TheLoop->getLoopLatch();
// Start with the conditional branch and walk up the block.
- Worklist.push_back(BB.getTerminator()->getOperand(0));
+ Worklist.push_back(Latch->getTerminator()->getOperand(0));
while (Worklist.size()) {
Instruction *I = dyn_cast<Instruction>(Worklist.back());
Worklist.pop_back();
- // Look at instructions inside this block.
- if (!I) continue;
- if (I->getParent() != &BB) continue;
+ // Look at instructions inside this loop.
// Stop when reaching PHI nodes.
- if (isa<PHINode>(I)) {
- assert(I == Induction && "Found a uniform PHI that is not the induction");
- break;
- }
+ // TODO: we need to follow values all over the loop, not only in this block.
+ if (!I || !TheLoop->contains(I) || isa<PHINode>(I))
+ continue;
// This is a known uniform.
Uniforms.insert(I);
// Insert all operands.
- for (int i=0, Op = I->getNumOperands(); i < Op; ++i) {
+ for (int i = 0, Op = I->getNumOperands(); i < Op; ++i) {
Worklist.push_back(I->getOperand(i));
}
}
-
- return true;
}
-bool LoopVectorizationLegality::canVectorizeMemory(BasicBlock &BB) {
+bool LoopVectorizationLegality::canVectorizeMemory() {
typedef SmallVector<Value*, 16> ValueVector;
typedef SmallPtrSet<Value*, 16> ValueSet;
// Holds the Load and Store *instructions*.
ValueVector Loads;
ValueVector Stores;
-
- // Scan the BB and collect legal loads and stores.
- for (BasicBlock::iterator it = BB.begin(), e = BB.end(); it != e; ++it) {
- Instruction *I = it;
-
- // If this is a load, save it. If this instruction can read from memory
- // but is not a load, then we quit. 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;
+ PtrRtCheck.Pointers.clear();
+ PtrRtCheck.Need = false;
+
+ // For each block.
+ for (Loop::block_iterator bb = TheLoop->block_begin(),
+ be = TheLoop->block_end(); bb != be; ++bb) {
+
+ // Scan the BB and collect legal loads and stores.
+ for (BasicBlock::iterator it = (*bb)->begin(), e = (*bb)->end(); it != e;
+ ++it) {
+
+ // If this is a load, save it. If this instruction can read from memory
+ // but is not a load, then we quit. Notice that we don't handle function
+ // calls that read or write.
+ if (it->mayReadFromMemory()) {
+ LoadInst *Ld = dyn_cast<LoadInst>(it);
+ if (!Ld) return false;
+ if (!Ld->isSimple()) {
+ DEBUG(dbgs() << "LV: Found a non-simple load.\n");
+ return false;
+ }
+ Loads.push_back(Ld);
+ continue;
}
- Loads.push_back(Ld);
- continue;
- }
- // Save store instructions. Abort if other instructions 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;
+ // Save 'store' instructions. Abort if other instructions write to memory.
+ if (it->mayWriteToMemory()) {
+ StoreInst *St = dyn_cast<StoreInst>(it);
+ if (!St) return false;
+ if (!St->isSimple()) {
+ DEBUG(dbgs() << "LV: Found a non-simple store.\n");
+ return false;
+ }
+ Stores.push_back(St);
}
- Stores.push_back(St);
- }
- } // next instr.
+ } // next instr.
+ } // next block.
// Now we have two lists that hold the loads and the stores.
// Next, we find the pointers that they use.
// Check if we see any stores. If there are no stores, then we don't
// care if the pointers are *restrict*.
if (!Stores.size()) {
- DEBUG(dbgs() << "LV: Found a read-only loop!\n");
- return true;
+ DEBUG(dbgs() << "LV: Found a read-only loop!\n");
+ return true;
}
// Holds the read and read-write *pointers* that we find.
ValueVector::iterator I, IE;
for (I = Stores.begin(), IE = Stores.end(); I != IE; ++I) {
- StoreInst *ST = dyn_cast<StoreInst>(*I);
- assert(ST && "Bad StoreInst");
+ StoreInst *ST = cast<StoreInst>(*I);
Value* Ptr = ST->getPointerOperand();
+
+ if (isUniform(Ptr)) {
+ DEBUG(dbgs() << "LV: We don't allow storing to uniform addresses\n");
+ return false;
+ }
+
// If we did *not* see this pointer before, insert it to
// the read-write list. At this phase it is only a 'write' list.
if (Seen.insert(Ptr))
}
for (I = Loads.begin(), IE = Loads.end(); I != IE; ++I) {
- LoadInst *LD = dyn_cast<LoadInst>(*I);
- assert(LD && "Bad LoadInst");
+ LoadInst *LD = cast<LoadInst>(*I);
Value* Ptr = LD->getPointerOperand();
// If we did *not* see this pointer before, insert it to the
// read list. If we *did* see it before, then it is already in
// If the address of i is unknown (for example A[B[i]]) then we may
// read a few words, modify, and write a few words, and some of the
// words may be written to the same address.
- if (Seen.insert(Ptr) || !isConsecutiveGep(Ptr))
+ if (Seen.insert(Ptr) || 0 == isConsecutivePtr(Ptr))
Reads.push_back(Ptr);
}
return true;
}
+ // Find pointers with computable bounds. We are going to use this information
+ // to place a runtime bound check.
+ bool CanDoRT = true;
+ for (I = ReadWrites.begin(), IE = ReadWrites.end(); I != IE; ++I)
+ if (hasComputableBounds(*I)) {
+ PtrRtCheck.insert(SE, TheLoop, *I);
+ DEBUG(dbgs() << "LV: Found a runtime check ptr:" << **I <<"\n");
+ } else {
+ CanDoRT = false;
+ break;
+ }
+ for (I = Reads.begin(), IE = Reads.end(); I != IE; ++I)
+ if (hasComputableBounds(*I)) {
+ PtrRtCheck.insert(SE, TheLoop, *I);
+ DEBUG(dbgs() << "LV: Found a runtime check ptr:" << **I <<"\n");
+ } else {
+ CanDoRT = false;
+ break;
+ }
+
+ // Check that we did not collect too many pointers or found a
+ // unsizeable pointer.
+ if (!CanDoRT || PtrRtCheck.Pointers.size() > RuntimeMemoryCheckThreshold) {
+ PtrRtCheck.reset();
+ CanDoRT = false;
+ }
+
+ if (CanDoRT) {
+ DEBUG(dbgs() << "LV: We can perform a memory runtime check if needed.\n");
+ }
+
+ bool NeedRTCheck = false;
+
// Now that the pointers are in two lists (Reads and ReadWrites), we
// can check that there are no conflicts between each of the writes and
// between the writes to the reads.
// Check that the read-writes do not conflict with other read-write
// pointers.
+ bool AllWritesIdentified = true;
for (I = ReadWrites.begin(), IE = ReadWrites.end(); I != IE; ++I) {
GetUnderlyingObjects(*I, TempObjects, DL);
for (ValueVector::iterator it=TempObjects.begin(), e=TempObjects.end();
it != e; ++it) {
if (!isIdentifiedObject(*it)) {
DEBUG(dbgs() << "LV: Found an unidentified write ptr:"<< **it <<"\n");
- return false;
+ NeedRTCheck = true;
+ AllWritesIdentified = false;
}
if (!WriteObjects.insert(*it)) {
DEBUG(dbgs() << "LV: Found a possible write-write reorder:"
GetUnderlyingObjects(*I, TempObjects, DL);
for (ValueVector::iterator it=TempObjects.begin(), e=TempObjects.end();
it != e; ++it) {
- if (!isIdentifiedObject(*it)) {
+ // If all of the writes are identified then we don't care if the read
+ // pointer is identified or not.
+ if (!AllWritesIdentified && !isIdentifiedObject(*it)) {
DEBUG(dbgs() << "LV: Found an unidentified read ptr:"<< **it <<"\n");
- return false;
+ NeedRTCheck = true;
}
if (WriteObjects.count(*it)) {
DEBUG(dbgs() << "LV: Found a possible read/write reorder:"
TempObjects.clear();
}
- // All is okay.
+ PtrRtCheck.Need = NeedRTCheck;
+ if (NeedRTCheck && !CanDoRT) {
+ DEBUG(dbgs() << "LV: We can't vectorize because we can't find " <<
+ "the array bounds.\n");
+ PtrRtCheck.reset();
+ return false;
+ }
+
+ DEBUG(dbgs() << "LV: We "<< (NeedRTCheck ? "" : "don't") <<
+ " need a runtime memory check.\n");
return true;
}
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);
+ // Reduction variables are only found in the loop header block.
+ if (Phi->getParent() != TheLoop->getHeader())
+ return false;
+
+ // Obtain the reduction start value from the value that comes from the loop
+ // preheader.
+ Value *RdxStart = Phi->getIncomingValueForBlock(TheLoop->getLoopPreheader());
// 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.
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
+ // users of this instruction. All users must be instructions that 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.
+ // out-of-block user. The cycle must end with the original PHI.
Instruction *Iter = Phi;
while (true) {
+ // If the instruction has no users then this is a broken
+ // chain and can't be a reduction variable.
+ if (Iter->use_empty())
+ return false;
+
// 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 ?
+ // Did we find a user inside this loop already ?
bool FoundInBlockUser = false;
- // Did we reach the initial PHI node ?
+ // Did we reach the initial PHI node already ?
bool FoundStartPHI = false;
- // If the instruction has no users then this is a broken
- // chain and can't be a reduction variable.
- if (Iter->use_empty())
- return false;
-
// For each of the *users* of iter.
for (Value::use_iterator it = Iter->use_begin(), e = Iter->use_end();
it != e; ++it) {
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 (!TheLoop->contains(Parent)) {
+ // Exit if you find multiple outside users.
if (ExitInstruction != 0)
return false;
ExitInstruction = Iter;
}
+
+ // We allow in-loop PHINodes which are not the original reduction PHI
+ // node. If this PHI is the only user of Iter (happens in IF w/ no ELSE
+ // structure) then don't skip this PHI.
+ if (isa<PHINode>(Iter) && isa<PHINode>(U) &&
+ U->getParent() != TheLoop->getHeader() &&
+ TheLoop->contains(U) &&
+ Iter->getNumUses() > 1)
+ continue;
+
// We can't have multiple inside users.
if (FoundInBlockUser)
return false;
// 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);
-
- // Save the description of this reduction variable.
- ReductionDescriptor RD(RdxStart, ExitInstruction, Kind);
- Reductions[Phi] = RD;
- return true;
- }
+ if (FoundStartPHI && ExitInstruction) {
+ // This instruction is allowed to have out-of-loop users.
+ AllowedExit.insert(ExitInstruction);
+
+ // Save the description of this reduction variable.
+ ReductionDescriptor RD(RdxStart, ExitInstruction, Kind);
+ Reductions[Phi] = RD;
+ return true;
+ }
+
+ // If we've reached the start PHI but did not find an outside user then
+ // this is dead code. Abort.
+ if (FoundStartPHI)
+ 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;
- case Instruction::And:
- return Kind == IntegerAnd;
- case Instruction::Or:
- return Kind == IntegerOr;
- case Instruction::Xor:
- return Kind == IntegerXor;
- }
+ switch (I->getOpcode()) {
+ default:
+ return false;
+ case Instruction::PHI:
+ // possibly.
+ return true;
+ case Instruction::Add:
+ case Instruction::Sub:
+ return Kind == IntegerAdd;
+ case Instruction::Mul:
+ return Kind == IntegerMult;
+ case Instruction::And:
+ return Kind == IntegerAnd;
+ case Instruction::Or:
+ return Kind == IntegerOr;
+ case Instruction::Xor:
+ return Kind == IntegerXor;
+ }
}
-bool LoopVectorizationLegality::isInductionVariable(PHINode *Phi) {
+LoopVectorizationLegality::InductionKind
+LoopVectorizationLegality::isInductionVariable(PHINode *Phi) {
+ Type *PhiTy = Phi->getType();
+ // We only handle integer and pointer inductions variables.
+ if (!PhiTy->isIntegerTy() && !PhiTy->isPointerTy())
+ return NoInduction;
+
// 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;
+ return NoInduction;
}
const SCEV *Step = AR->getStepRecurrence(*SE);
- if (!Step->isOne()) {
- DEBUG(dbgs() << "LV: PHI stride does not equal one.\n");
+ // Integer inductions need to have a stride of one.
+ if (PhiTy->isIntegerTy()) {
+ if (Step->isOne())
+ return IntInduction;
+ if (Step->isAllOnesValue())
+ return ReverseIntInduction;
+ return NoInduction;
+ }
+
+ // Calculate the pointer stride and check if it is consecutive.
+ const SCEVConstant *C = dyn_cast<SCEVConstant>(Step);
+ if (!C)
+ return NoInduction;
+
+ assert(PhiTy->isPointerTy() && "The PHI must be a pointer");
+ uint64_t Size = DL->getTypeAllocSize(PhiTy->getPointerElementType());
+ if (C->getValue()->equalsInt(Size))
+ return PtrInduction;
+
+ return NoInduction;
+}
+
+bool LoopVectorizationLegality::isInductionVariable(const Value *V) {
+ Value *In0 = const_cast<Value*>(V);
+ PHINode *PN = dyn_cast_or_null<PHINode>(In0);
+ if (!PN)
return false;
+
+ return Inductions.count(PN);
+}
+
+bool LoopVectorizationLegality::blockNeedsPredication(BasicBlock *BB) {
+ assert(TheLoop->contains(BB) && "Unknown block used");
+
+ // Blocks that do not dominate the latch need predication.
+ BasicBlock* Latch = TheLoop->getLoopLatch();
+ return !DT->dominates(BB, Latch);
+}
+
+bool LoopVectorizationLegality::blockCanBePredicated(BasicBlock *BB) {
+ for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
+ // We don't predicate loads/stores at the moment.
+ if (it->mayReadFromMemory() || it->mayWriteToMemory() || it->mayThrow())
+ return false;
+
+ // The instructions below can trap.
+ switch (it->getOpcode()) {
+ default: continue;
+ case Instruction::UDiv:
+ case Instruction::SDiv:
+ case Instruction::URem:
+ case Instruction::SRem:
+ return false;
+ }
}
+
return true;
}
+bool LoopVectorizationLegality::hasComputableBounds(Value *Ptr) {
+ const SCEV *PhiScev = SE->getSCEV(Ptr);
+ const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PhiScev);
+ if (!AR)
+ return false;
+
+ return AR->isAffine();
+}
+
unsigned
-LoopVectorizationCostModel::findBestVectorizationFactor(unsigned VF) {
+LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize,
+ unsigned UserVF) {
+ if (OptForSize && Legal->getRuntimePointerCheck()->Need) {
+ DEBUG(dbgs() << "LV: Aborting. Runtime ptr check is required in Os.\n");
+ return 1;
+ }
+
+ // Find the trip count.
+ unsigned TC = SE->getSmallConstantTripCount(TheLoop, TheLoop->getLoopLatch());
+ DEBUG(dbgs() << "LV: Found trip count:"<<TC<<"\n");
+
+ unsigned VF = MaxVectorSize;
+
+ // If we optimize the program for size, avoid creating the tail loop.
+ if (OptForSize) {
+ // If we are unable to calculate the trip count then don't try to vectorize.
+ if (TC < 2) {
+ DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n");
+ return 1;
+ }
+
+ // Find the maximum SIMD width that can fit within the trip count.
+ VF = TC % MaxVectorSize;
+
+ if (VF == 0)
+ VF = MaxVectorSize;
+
+ // If the trip count that we found modulo the vectorization factor is not
+ // zero then we require a tail.
+ if (VF < 2) {
+ DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n");
+ return 1;
+ }
+ }
+
+ if (UserVF != 0) {
+ assert(isPowerOf2_32(UserVF) && "VF needs to be a power of two");
+ DEBUG(dbgs() << "LV: Using user VF "<<UserVF<<".\n");
+
+ return UserVF;
+ }
+
if (!VTTI) {
DEBUG(dbgs() << "LV: No vector target information. Not vectorizing. \n");
return 1;
return Width;
}
-unsigned LoopVectorizationCostModel::expectedCost(unsigned VF) {
- // We can only estimate the cost of single basic block loops.
- assert(1 == TheLoop->getNumBlocks() && "Too many blocks in loop");
+unsigned
+LoopVectorizationCostModel::selectUnrollFactor(bool OptForSize,
+ unsigned UserUF) {
+ // Use the user preference, unless 'auto' is selected.
+ if (UserUF != 0)
+ return UserUF;
+
+ // When we optimize for size we don't unroll.
+ if (OptForSize)
+ return 1;
+
+ unsigned TargetVectorRegisters = VTTI->getNumberOfRegisters(true);
+ DEBUG(dbgs() << "LV: The target has " << TargetVectorRegisters <<
+ " vector registers\n");
+
+ LoopVectorizationCostModel::RegisterUsage R = calculateRegisterUsage();
+ // We divide by these constants so assume that we have at least one
+ // instruction that uses at least one register.
+ R.MaxLocalUsers = std::max(R.MaxLocalUsers, 1U);
+ R.NumInstructions = std::max(R.NumInstructions, 1U);
+
+ // We calculate the unroll factor using the following formula.
+ // Subtract the number of loop invariants from the number of available
+ // registers. These registers are used by all of the unrolled instances.
+ // Next, divide the remaining registers by the number of registers that is
+ // required by the loop, in order to estimate how many parallel instances
+ // fit without causing spills.
+ unsigned UF = (TargetVectorRegisters - R.LoopInvariantRegs) / R.MaxLocalUsers;
+
+ // We don't want to unroll the loops to the point where they do not fit into
+ // the decoded cache. Assume that we only allow 32 IR instructions.
+ UF = std::min(UF, (32 / R.NumInstructions));
+
+ // Clamp the unroll factor ranges to reasonable factors.
+ if (UF > MaxUnrollSize)
+ UF = MaxUnrollSize;
+ else if (UF < 1)
+ UF = 1;
+
+ return UF;
+}
+
+LoopVectorizationCostModel::RegisterUsage
+LoopVectorizationCostModel::calculateRegisterUsage() {
+ // This function calculates the register usage by measuring the highest number
+ // of values that are alive at a single location. Obviously, this is a very
+ // rough estimation. We scan the loop in a topological order in order and
+ // assign a number to each instruction. We use RPO to ensure that defs are
+ // met before their users. We assume that each instruction that has in-loop
+ // users starts an interval. We record every time that an in-loop value is
+ // used, so we have a list of the first and last occurrences of each
+ // instruction. Next, we transpose this data structure into a multi map that
+ // holds the list of intervals that *end* at a specific location. This multi
+ // map allows us to perform a linear search. We scan the instructions linearly
+ // and record each time that a new interval starts, by placing it in a set.
+ // If we find this value in the multi-map then we remove it from the set.
+ // The max register usage is the maximum size of the set.
+ // We also search for instructions that are defined outside the loop, but are
+ // used inside the loop. We need this number separately from the max-interval
+ // usage number because when we unroll, loop-invariant values do not take
+ // more register.
+ LoopBlocksDFS DFS(TheLoop);
+ DFS.perform(LI);
+
+ RegisterUsage R;
+ R.NumInstructions = 0;
+
+ // Each 'key' in the map opens a new interval. The values
+ // of the map are the index of the 'last seen' usage of the
+ // instruction that is the key.
+ typedef DenseMap<Instruction*, unsigned> IntervalMap;
+ // Maps instruction to its index.
+ DenseMap<unsigned, Instruction*> IdxToInstr;
+ // Marks the end of each interval.
+ IntervalMap EndPoint;
+ // Saves the list of instruction indices that are used in the loop.
+ SmallSet<Instruction*, 8> Ends;
+ // Saves the list of values that are used in the loop but are
+ // defined outside the loop, such as arguments and constants.
+ SmallPtrSet<Value*, 8> LoopInvariants;
+
+ unsigned Index = 0;
+ for (LoopBlocksDFS::RPOIterator bb = DFS.beginRPO(),
+ be = DFS.endRPO(); bb != be; ++bb) {
+ R.NumInstructions += (*bb)->size();
+ for (BasicBlock::iterator it = (*bb)->begin(), e = (*bb)->end(); it != e;
+ ++it) {
+ Instruction *I = it;
+ IdxToInstr[Index++] = I;
+
+ // Save the end location of each USE.
+ for (unsigned i = 0; i < I->getNumOperands(); ++i) {
+ Value *U = I->getOperand(i);
+ Instruction *Instr = dyn_cast<Instruction>(U);
+
+ // Ignore non-instruction values such as arguments, constants, etc.
+ if (!Instr) continue;
+
+ // If this instruction is outside the loop then record it and continue.
+ if (!TheLoop->contains(Instr)) {
+ LoopInvariants.insert(Instr);
+ continue;
+ }
+
+ // Overwrite previous end points.
+ EndPoint[Instr] = Index;
+ Ends.insert(Instr);
+ }
+ }
+ }
+
+ // Saves the list of intervals that end with the index in 'key'.
+ typedef SmallVector<Instruction*, 2> InstrList;
+ DenseMap<unsigned, InstrList> TransposeEnds;
- BasicBlock *BB = TheLoop->getHeader();
+ // Transpose the EndPoints to a list of values that end at each index.
+ for (IntervalMap::iterator it = EndPoint.begin(), e = EndPoint.end();
+ it != e; ++it)
+ TransposeEnds[it->second].push_back(it->first);
+
+ SmallSet<Instruction*, 8> OpenIntervals;
+ unsigned MaxUsage = 0;
+
+
+ DEBUG(dbgs() << "LV(REG): Calculating max register usage:\n");
+ for (unsigned int i = 0; i < Index; ++i) {
+ Instruction *I = IdxToInstr[i];
+ // Ignore instructions that are never used within the loop.
+ if (!Ends.count(I)) continue;
+
+ // Remove all of the instructions that end at this location.
+ InstrList &List = TransposeEnds[i];
+ for (unsigned int i=0, e = List.size(); i < e; ++i)
+ OpenIntervals.erase(List[i]);
+
+ // Count the number of live interals.
+ MaxUsage = std::max(MaxUsage, OpenIntervals.size());
+
+ DEBUG(dbgs() << "LV(REG): At #" << i << " Interval # " <<
+ OpenIntervals.size() <<"\n");
+
+ // Add the current instruction to the list of open intervals.
+ OpenIntervals.insert(I);
+ }
+
+ unsigned Invariant = LoopInvariants.size();
+ DEBUG(dbgs() << "LV(REG): Found max usage: " << MaxUsage << " \n");
+ DEBUG(dbgs() << "LV(REG): Found invariant usage: " << Invariant << " \n");
+ DEBUG(dbgs() << "LV(REG): LoopSize: " << R.NumInstructions << " \n");
+
+ R.LoopInvariantRegs = Invariant;
+ R.MaxLocalUsers = MaxUsage;
+ return R;
+}
+
+unsigned LoopVectorizationCostModel::expectedCost(unsigned VF) {
unsigned Cost = 0;
- // For each instruction in the old loop.
- for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
- Instruction *Inst = it;
- unsigned C = getInstructionCost(Inst, VF);
- Cost += C;
- DEBUG(dbgs() << "LV: Found an estimated cost of "<< C <<" for VF "<< VF <<
- " For instruction: "<< *Inst << "\n");
+ // For each block.
+ for (Loop::block_iterator bb = TheLoop->block_begin(),
+ be = TheLoop->block_end(); bb != be; ++bb) {
+ unsigned BlockCost = 0;
+ BasicBlock *BB = *bb;
+
+ // For each instruction in the old loop.
+ for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
+ unsigned C = getInstructionCost(it, VF);
+ Cost += C;
+ DEBUG(dbgs() << "LV: Found an estimated cost of "<< C <<" for VF " <<
+ VF << " For instruction: "<< *it << "\n");
+ }
+
+ // We assume that if-converted blocks have a 50% chance of being executed.
+ // When the code is scalar then some of the blocks are avoided due to CF.
+ // When the code is vectorized we execute all code paths.
+ if (Legal->blockNeedsPredication(*bb) && VF == 1)
+ BlockCost /= 2;
+
+ Cost += BlockCost;
}
return Cost;
Type *RetTy = I->getType();
Type *VectorTy = ToVectorTy(RetTy, VF);
-
// TODO: We need to estimate the cost of intrinsic calls.
switch (I->getOpcode()) {
- case Instruction::GetElementPtr:
- // We mark this instruction as zero-cost because scalar GEPs are usually
- // lowered to the intruction addressing mode. At the moment we don't
- // generate vector geps.
- return 0;
- case Instruction::Br: {
- return VTTI->getCFInstrCost(I->getOpcode());
- }
- case Instruction::PHI:
- return 0;
- 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: {
- return VTTI->getArithmeticInstrCost(I->getOpcode(), VectorTy);
- }
- case Instruction::Select: {
- SelectInst *SI = cast<SelectInst>(I);
- const SCEV *CondSCEV = SE->getSCEV(SI->getCondition());
- bool ScalarCond = (SE->isLoopInvariant(CondSCEV, TheLoop));
- Type *CondTy = SI->getCondition()->getType();
- if (ScalarCond)
- CondTy = VectorType::get(CondTy, VF);
-
- return VTTI->getCmpSelInstrCost(I->getOpcode(), VectorTy, CondTy);
- }
- case Instruction::ICmp:
- case Instruction::FCmp: {
- Type *ValTy = I->getOperand(0)->getType();
- VectorTy = ToVectorTy(ValTy, VF);
- return VTTI->getCmpSelInstrCost(I->getOpcode(), VectorTy);
- }
- case Instruction::Store: {
- StoreInst *SI = cast<StoreInst>(I);
- Type *ValTy = SI->getValueOperand()->getType();
- VectorTy = ToVectorTy(ValTy, VF);
-
- if (VF == 1)
- return VTTI->getMemoryOpCost(I->getOpcode(), ValTy,
- SI->getAlignment(), SI->getPointerAddressSpace());
-
- // Scalarized stores.
- if (!Legal->isConsecutiveGep(SI->getPointerOperand())) {
- unsigned Cost = 0;
- unsigned ExtCost = VTTI->getInstrCost(Instruction::ExtractElement,
- ValTy);
- // The cost of extracting from the value vector.
- Cost += VF * (ExtCost);
- // The cost of the scalar stores.
- Cost += VF * VTTI->getMemoryOpCost(I->getOpcode(),
- ValTy->getScalarType(),
- SI->getAlignment(),
- SI->getPointerAddressSpace());
- return Cost;
- }
-
- // Wide stores.
- return VTTI->getMemoryOpCost(I->getOpcode(), VectorTy, SI->getAlignment(),
+ case Instruction::GetElementPtr:
+ // We mark this instruction as zero-cost because scalar GEPs are usually
+ // lowered to the intruction addressing mode. At the moment we don't
+ // generate vector geps.
+ return 0;
+ case Instruction::Br: {
+ return VTTI->getCFInstrCost(I->getOpcode());
+ }
+ case Instruction::PHI:
+ //TODO: IF-converted IFs become selects.
+ return 0;
+ 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:
+ return VTTI->getArithmeticInstrCost(I->getOpcode(), VectorTy);
+ case Instruction::Select: {
+ SelectInst *SI = cast<SelectInst>(I);
+ const SCEV *CondSCEV = SE->getSCEV(SI->getCondition());
+ bool ScalarCond = (SE->isLoopInvariant(CondSCEV, TheLoop));
+ Type *CondTy = SI->getCondition()->getType();
+ if (ScalarCond)
+ CondTy = VectorType::get(CondTy, VF);
+
+ return VTTI->getCmpSelInstrCost(I->getOpcode(), VectorTy, CondTy);
+ }
+ case Instruction::ICmp:
+ case Instruction::FCmp: {
+ Type *ValTy = I->getOperand(0)->getType();
+ VectorTy = ToVectorTy(ValTy, VF);
+ return VTTI->getCmpSelInstrCost(I->getOpcode(), VectorTy);
+ }
+ case Instruction::Store: {
+ StoreInst *SI = cast<StoreInst>(I);
+ Type *ValTy = SI->getValueOperand()->getType();
+ VectorTy = ToVectorTy(ValTy, VF);
+
+ if (VF == 1)
+ return VTTI->getMemoryOpCost(I->getOpcode(), VectorTy,
+ SI->getAlignment(),
SI->getPointerAddressSpace());
- }
- case Instruction::Load: {
- LoadInst *LI = cast<LoadInst>(I);
-
- if (VF == 1)
- return VTTI->getMemoryOpCost(I->getOpcode(), RetTy,
- LI->getAlignment(),
- LI->getPointerAddressSpace());
-
- // Scalarized loads.
- if (!Legal->isConsecutiveGep(LI->getPointerOperand())) {
- unsigned Cost = 0;
- unsigned InCost = VTTI->getInstrCost(Instruction::InsertElement, RetTy);
- // The cost of inserting the loaded value into the result vector.
- Cost += VF * (InCost);
- // The cost of the scalar stores.
- Cost += VF * VTTI->getMemoryOpCost(I->getOpcode(),
- RetTy->getScalarType(),
- LI->getAlignment(),
- LI->getPointerAddressSpace());
- return Cost;
+
+ // Scalarized stores.
+ int Stride = Legal->isConsecutivePtr(SI->getPointerOperand());
+ bool Reverse = Stride < 0;
+ if (0 == Stride) {
+ unsigned Cost = 0;
+
+ // The cost of extracting from the value vector and pointer vector.
+ Type *PtrTy = ToVectorTy(I->getOperand(0)->getType(), VF);
+ for (unsigned i = 0; i < VF; ++i) {
+ Cost += VTTI->getVectorInstrCost(Instruction::ExtractElement,
+ VectorTy, i);
+ Cost += VTTI->getVectorInstrCost(Instruction::ExtractElement,
+ PtrTy, i);
}
- // Wide loads.
- return VTTI->getMemoryOpCost(I->getOpcode(), VectorTy, LI->getAlignment(),
- LI->getPointerAddressSpace());
- }
- 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: {
- Type *SrcVecTy = ToVectorTy(I->getOperand(0)->getType(), VF);
- return VTTI->getCastInstrCost(I->getOpcode(), VectorTy, SrcVecTy);
+ // The cost of the scalar stores.
+ Cost += VF * VTTI->getMemoryOpCost(I->getOpcode(),
+ ValTy->getScalarType(),
+ SI->getAlignment(),
+ SI->getPointerAddressSpace());
+ return Cost;
}
- default: {
- // We are scalarizing the instruction. Return the cost of the scalar
- // instruction, plus the cost of insert and extract into vector
- // elements, times the vector width.
- unsigned Cost = 0;
- bool IsVoid = RetTy->isVoidTy();
+ // Wide stores.
+ unsigned Cost = VTTI->getMemoryOpCost(I->getOpcode(), VectorTy,
+ SI->getAlignment(),
+ SI->getPointerAddressSpace());
+ if (Reverse)
+ Cost += VTTI->getShuffleCost(VectorTargetTransformInfo::Reverse,
+ VectorTy, 0);
+ return Cost;
+ }
+ case Instruction::Load: {
+ LoadInst *LI = cast<LoadInst>(I);
- unsigned InsCost = (IsVoid ? 0 :
- VTTI->getInstrCost(Instruction::InsertElement,
- VectorTy));
+ if (VF == 1)
+ return VTTI->getMemoryOpCost(I->getOpcode(), VectorTy,
+ LI->getAlignment(),
+ LI->getPointerAddressSpace());
- unsigned ExtCost = VTTI->getInstrCost(Instruction::ExtractElement,
- VectorTy);
+ // Scalarized loads.
+ int Stride = Legal->isConsecutivePtr(LI->getPointerOperand());
+ bool Reverse = Stride < 0;
+ if (0 == Stride) {
+ unsigned Cost = 0;
+ Type *PtrTy = ToVectorTy(I->getOperand(0)->getType(), VF);
+
+ // The cost of extracting from the pointer vector.
+ for (unsigned i = 0; i < VF; ++i)
+ Cost += VTTI->getVectorInstrCost(Instruction::ExtractElement,
+ PtrTy, i);
+
+ // The cost of inserting data to the result vector.
+ for (unsigned i = 0; i < VF; ++i)
+ Cost += VTTI->getVectorInstrCost(Instruction::InsertElement,
+ VectorTy, i);
+
+ // The cost of the scalar stores.
+ Cost += VF * VTTI->getMemoryOpCost(I->getOpcode(),
+ RetTy->getScalarType(),
+ LI->getAlignment(),
+ LI->getPointerAddressSpace());
+ return Cost;
+ }
+
+ // Wide loads.
+ unsigned Cost = VTTI->getMemoryOpCost(I->getOpcode(), VectorTy,
+ LI->getAlignment(),
+ LI->getPointerAddressSpace());
+ if (Reverse)
+ Cost += VTTI->getShuffleCost(VectorTargetTransformInfo::Reverse,
+ VectorTy, 0);
+ return Cost;
+ }
+ 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: {
+ // We optimize the truncation of induction variable.
+ // The cost of these is the same as the scalar operation.
+ if (I->getOpcode() == Instruction::Trunc &&
+ Legal->isInductionVariable(I->getOperand(0)))
+ return VTTI->getCastInstrCost(I->getOpcode(), I->getType(),
+ I->getOperand(0)->getType());
+
+ Type *SrcVecTy = ToVectorTy(I->getOperand(0)->getType(), VF);
+ return VTTI->getCastInstrCost(I->getOpcode(), VectorTy, SrcVecTy);
+ }
+ case Instruction::Call: {
+ assert(isTriviallyVectorizableIntrinsic(I));
+ IntrinsicInst *II = cast<IntrinsicInst>(I);
+ Type *RetTy = ToVectorTy(II->getType(), VF);
+ SmallVector<Type*, 4> Tys;
+ for (unsigned i = 0, ie = II->getNumArgOperands(); i != ie; ++i)
+ Tys.push_back(ToVectorTy(II->getArgOperand(i)->getType(), VF));
+ return VTTI->getIntrinsicInstrCost(II->getIntrinsicID(), RetTy, Tys);
+ }
+ default: {
+ // We are scalarizing the instruction. Return the cost of the scalar
+ // instruction, plus the cost of insert and extract into vector
+ // elements, times the vector width.
+ unsigned Cost = 0;
+
+ if (!RetTy->isVoidTy() && VF != 1) {
+ unsigned InsCost = VTTI->getVectorInstrCost(Instruction::InsertElement,
+ VectorTy);
+ unsigned ExtCost = VTTI->getVectorInstrCost(Instruction::ExtractElement,
+ VectorTy);
// The cost of inserting the results plus extracting each one of the
// operands.
Cost += VF * (InsCost + ExtCost * I->getNumOperands());
-
- // The cost of executing VF copies of the scalar instruction.
- Cost += VF * VTTI->getInstrCost(I->getOpcode(), RetTy);
- return Cost;
}
+
+ // The cost of executing VF copies of the scalar instruction. This opcode
+ // is unknown. Assume that it is the same as 'mul'.
+ Cost += VF * VTTI->getArithmeticInstrCost(Instruction::Mul, VectorTy);
+ return Cost;
+ }
}// end of switch.
}
return VectorType::get(Scalar, VF);
}
-} // namespace
-
char LoopVectorize::ID = 0;
static const char lv_name[] = "Loop Vectorization";
INITIALIZE_PASS_BEGIN(LoopVectorize, LV_NAME, lv_name, false, false)
}
}
+
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