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//===- LoopVectorizationPlanner.h - Planner for LoopVectorization ---------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \file
/// This file provides a LoopVectorizationPlanner class.
/// InnerLoopVectorizer vectorizes loops which contain only one basic
/// LoopVectorizationPlanner - drives the vectorization process after having
/// passed Legality checks.
/// The planner builds and optimizes the Vectorization Plans which record the
/// decisions how to vectorize the given loop. In particular, represent the
/// control-flow of the vectorized version, the replication of instructions that
/// are to be scalarized, and interleave access groups.
/// Also provides a VPlan-based builder utility analogous to IRBuilder.
/// It provides an instruction-level API for generating VPInstructions while
/// abstracting away the Recipe manipulation details.
#include "VPlan.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
namespace llvm {
class LoopVectorizationLegality;
class LoopVectorizationCostModel;
class PredicatedScalarEvolution;
class VPRecipeBuilder;
/// VPlan-based builder utility analogous to IRBuilder.
class VPBuilder {
VPBasicBlock *BB = nullptr;
VPBasicBlock::iterator InsertPt = VPBasicBlock::iterator();
VPInstruction *createInstruction(unsigned Opcode,
ArrayRef<VPValue *> Operands) {
VPInstruction *Instr = new VPInstruction(Opcode, Operands);
if (BB)
BB->insert(Instr, InsertPt);
return Instr;
VPInstruction *createInstruction(unsigned Opcode,
std::initializer_list<VPValue *> Operands) {
return createInstruction(Opcode, ArrayRef<VPValue *>(Operands));
VPBuilder() {}
/// Clear the insertion point: created instructions will not be inserted into
/// a block.
void clearInsertionPoint() {
BB = nullptr;
InsertPt = VPBasicBlock::iterator();
VPBasicBlock *getInsertBlock() const { return BB; }
VPBasicBlock::iterator getInsertPoint() const { return InsertPt; }
/// InsertPoint - A saved insertion point.
class VPInsertPoint {
VPBasicBlock *Block = nullptr;
VPBasicBlock::iterator Point;
/// Creates a new insertion point which doesn't point to anything.
VPInsertPoint() = default;
/// Creates a new insertion point at the given location.
VPInsertPoint(VPBasicBlock *InsertBlock, VPBasicBlock::iterator InsertPoint)
: Block(InsertBlock), Point(InsertPoint) {}
/// Returns true if this insert point is set.
bool isSet() const { return Block != nullptr; }
VPBasicBlock *getBlock() const { return Block; }
VPBasicBlock::iterator getPoint() const { return Point; }
/// Sets the current insert point to a previously-saved location.
void restoreIP(VPInsertPoint IP) {
if (IP.isSet())
setInsertPoint(IP.getBlock(), IP.getPoint());
/// This specifies that created VPInstructions should be appended to the end
/// of the specified block.
void setInsertPoint(VPBasicBlock *TheBB) {
assert(TheBB && "Attempting to set a null insert point");
BB = TheBB;
InsertPt = BB->end();
/// This specifies that created instructions should be inserted at the
/// specified point.
void setInsertPoint(VPBasicBlock *TheBB, VPBasicBlock::iterator IP) {
BB = TheBB;
InsertPt = IP;
/// Insert and return the specified instruction.
VPInstruction *insert(VPInstruction *I) const {
BB->insert(I, InsertPt);
return I;
/// Create an N-ary operation with \p Opcode, \p Operands and set \p Inst as
/// its underlying Instruction.
VPValue *createNaryOp(unsigned Opcode, ArrayRef<VPValue *> Operands,
Instruction *Inst = nullptr) {
VPInstruction *NewVPInst = createInstruction(Opcode, Operands);
return NewVPInst;
VPValue *createNaryOp(unsigned Opcode,
std::initializer_list<VPValue *> Operands,
Instruction *Inst = nullptr) {
return createNaryOp(Opcode, ArrayRef<VPValue *>(Operands), Inst);
VPValue *createNot(VPValue *Operand) {
return createInstruction(VPInstruction::Not, {Operand});
VPValue *createAnd(VPValue *LHS, VPValue *RHS) {
return createInstruction(Instruction::BinaryOps::And, {LHS, RHS});
VPValue *createOr(VPValue *LHS, VPValue *RHS) {
return createInstruction(Instruction::BinaryOps::Or, {LHS, RHS});
VPValue *createSelect(VPValue *Cond, VPValue *TrueVal, VPValue *FalseVal) {
return createNaryOp(Instruction::Select, {Cond, TrueVal, FalseVal});
// RAII helpers.
/// RAII object that stores the current insertion point and restores it when
/// the object is destroyed.
class InsertPointGuard {
VPBuilder &Builder;
VPBasicBlock *Block;
VPBasicBlock::iterator Point;
InsertPointGuard(VPBuilder &B)
: Builder(B), Block(B.getInsertBlock()), Point(B.getInsertPoint()) {}
InsertPointGuard(const InsertPointGuard &) = delete;
InsertPointGuard &operator=(const InsertPointGuard &) = delete;
~InsertPointGuard() { Builder.restoreIP(VPInsertPoint(Block, Point)); }
/// TODO: The following VectorizationFactor was pulled out of
/// LoopVectorizationCostModel class. LV also deals with
/// VectorizerParams::VectorizationFactor and VectorizationCostTy.
/// We need to streamline them.
/// Information about vectorization costs
struct VectorizationFactor {
// Vector width with best cost
ElementCount Width;
// Cost of the loop with that width
unsigned Cost;
// Width 1 means no vectorization, cost 0 means uncomputed cost.
static VectorizationFactor Disabled() {
return {ElementCount::getFixed(1), 0};
bool operator==(const VectorizationFactor &rhs) const {
return Width == rhs.Width && Cost == rhs.Cost;
bool operator!=(const VectorizationFactor &rhs) const {
return !(*this == rhs);
/// Planner drives the vectorization process after having passed
/// Legality checks.
class LoopVectorizationPlanner {
/// The loop that we evaluate.
Loop *OrigLoop;
/// Loop Info analysis.
LoopInfo *LI;
/// Target Library Info.
const TargetLibraryInfo *TLI;
/// Target Transform Info.
const TargetTransformInfo *TTI;
/// The legality analysis.
LoopVectorizationLegality *Legal;
/// The profitability analysis.
LoopVectorizationCostModel &CM;
/// The interleaved access analysis.
InterleavedAccessInfo &IAI;
PredicatedScalarEvolution &PSE;
SmallVector<VPlanPtr, 4> VPlans;
/// A builder used to construct the current plan.
VPBuilder Builder;
/// The best number of elements of the vector types used in the
/// transformed loop. BestVF = None means that vectorization is
/// disabled.
Optional<ElementCount> BestVF = None;
unsigned BestUF = 0;
LoopVectorizationPlanner(Loop *L, LoopInfo *LI, const TargetLibraryInfo *TLI,
const TargetTransformInfo *TTI,
LoopVectorizationLegality *Legal,
LoopVectorizationCostModel &CM,
InterleavedAccessInfo &IAI,
PredicatedScalarEvolution &PSE)
: OrigLoop(L), LI(LI), TLI(TLI), TTI(TTI), Legal(Legal), CM(CM), IAI(IAI),
/// Plan how to best vectorize, return the best VF and its cost, or None if
/// vectorization and interleaving should be avoided up front.
Optional<VectorizationFactor> plan(ElementCount UserVF, unsigned UserIC);
/// Use the VPlan-native path to plan how to best vectorize, return the best
/// VF and its cost.
VectorizationFactor planInVPlanNativePath(ElementCount UserVF);
/// Finalize the best decision and dispose of all other VPlans.
void setBestPlan(ElementCount VF, unsigned UF);
/// Generate the IR code for the body of the vectorized loop according to the
/// best selected VPlan.
void executePlan(InnerLoopVectorizer &LB, DominatorTree *DT);
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void printPlans(raw_ostream &O);
/// Look through the existing plans and return true if we have one with all
/// the vectorization factors in question.
bool hasPlanWithVFs(const ArrayRef<ElementCount> VFs) const {
return any_of(VPlans, [&](const VPlanPtr &Plan) {
return all_of(VFs, [&](const ElementCount &VF) {
return Plan->hasVF(VF);
/// Test a \p Predicate on a \p Range of VF's. Return the value of applying
/// \p Predicate on Range.Start, possibly decreasing Range.End such that the
/// returned value holds for the entire \p Range.
static bool
getDecisionAndClampRange(const std::function<bool(ElementCount)> &Predicate,
VFRange &Range);
/// Collect the instructions from the original loop that would be trivially
/// dead in the vectorized loop if generated.
void collectTriviallyDeadInstructions(
SmallPtrSetImpl<Instruction *> &DeadInstructions);
/// Build VPlans for power-of-2 VF's between \p MinVF and \p MaxVF inclusive,
/// according to the information gathered by Legal when it checked if it is
/// legal to vectorize the loop.
void buildVPlans(ElementCount MinVF, ElementCount MaxVF);
/// Build a VPlan according to the information gathered by Legal. \return a
/// VPlan for vectorization factors \p Range.Start and up to \p Range.End
/// exclusive, possibly decreasing \p Range.End.
VPlanPtr buildVPlan(VFRange &Range);
/// Build a VPlan using VPRecipes according to the information gather by
/// Legal. This method is only used for the legacy inner loop vectorizer.
VPlanPtr buildVPlanWithVPRecipes(
VFRange &Range, SmallPtrSetImpl<Instruction *> &DeadInstructions,
const DenseMap<Instruction *, Instruction *> &SinkAfter);
/// Build VPlans for power-of-2 VF's between \p MinVF and \p MaxVF inclusive,
/// according to the information gathered by Legal when it checked if it is
/// legal to vectorize the loop. This method creates VPlans using VPRecipes.
void buildVPlansWithVPRecipes(ElementCount MinVF, ElementCount MaxVF);
/// Adjust the recipes for any inloop reductions. The chain of instructions
/// leading from the loop exit instr to the phi need to be converted to
/// reductions, with one operand being vector and the other being the scalar
/// reduction chain.
void adjustRecipesForInLoopReductions(VPlanPtr &Plan,
VPRecipeBuilder &RecipeBuilder);
} // namespace llvm