LLVM 18.0.0git
LoopVectorizationPlanner.h
Go to the documentation of this file.
1//===- LoopVectorizationPlanner.h - Planner for LoopVectorization ---------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// This file provides a LoopVectorizationPlanner class.
11/// InnerLoopVectorizer vectorizes loops which contain only one basic
12/// LoopVectorizationPlanner - drives the vectorization process after having
13/// passed Legality checks.
14/// The planner builds and optimizes the Vectorization Plans which record the
15/// decisions how to vectorize the given loop. In particular, represent the
16/// control-flow of the vectorized version, the replication of instructions that
17/// are to be scalarized, and interleave access groups.
18///
19/// Also provides a VPlan-based builder utility analogous to IRBuilder.
20/// It provides an instruction-level API for generating VPInstructions while
21/// abstracting away the Recipe manipulation details.
22//===----------------------------------------------------------------------===//
23
24#ifndef LLVM_TRANSFORMS_VECTORIZE_LOOPVECTORIZATIONPLANNER_H
25#define LLVM_TRANSFORMS_VECTORIZE_LOOPVECTORIZATIONPLANNER_H
26
27#include "VPlan.h"
28#include "llvm/ADT/SmallSet.h"
30
31namespace llvm {
32
33class LoopInfo;
34class DominatorTree;
35class LoopVectorizationLegality;
36class LoopVectorizationCostModel;
37class PredicatedScalarEvolution;
38class LoopVectorizeHints;
39class OptimizationRemarkEmitter;
40class TargetTransformInfo;
41class TargetLibraryInfo;
42class VPRecipeBuilder;
43
44/// VPlan-based builder utility analogous to IRBuilder.
45class VPBuilder {
46 VPBasicBlock *BB = nullptr;
48
49 /// Insert \p VPI in BB at InsertPt if BB is set.
50 VPInstruction *tryInsertInstruction(VPInstruction *VPI) {
51 if (BB)
52 BB->insert(VPI, InsertPt);
53 return VPI;
54 }
55
56 VPInstruction *createInstruction(unsigned Opcode,
58 const Twine &Name = "") {
59 return tryInsertInstruction(new VPInstruction(Opcode, Operands, DL, Name));
60 }
61
62 VPInstruction *createInstruction(unsigned Opcode,
63 std::initializer_list<VPValue *> Operands,
64 DebugLoc DL, const Twine &Name = "") {
65 return createInstruction(Opcode, ArrayRef<VPValue *>(Operands), DL, Name);
66 }
67
68public:
69 VPBuilder() = default;
70 VPBuilder(VPBasicBlock *InsertBB) { setInsertPoint(InsertBB); }
71
72 /// Clear the insertion point: created instructions will not be inserted into
73 /// a block.
75 BB = nullptr;
76 InsertPt = VPBasicBlock::iterator();
77 }
78
79 VPBasicBlock *getInsertBlock() const { return BB; }
80 VPBasicBlock::iterator getInsertPoint() const { return InsertPt; }
81
82 /// InsertPoint - A saved insertion point.
84 VPBasicBlock *Block = nullptr;
86
87 public:
88 /// Creates a new insertion point which doesn't point to anything.
89 VPInsertPoint() = default;
90
91 /// Creates a new insertion point at the given location.
93 : Block(InsertBlock), Point(InsertPoint) {}
94
95 /// Returns true if this insert point is set.
96 bool isSet() const { return Block != nullptr; }
97
98 VPBasicBlock *getBlock() const { return Block; }
99 VPBasicBlock::iterator getPoint() const { return Point; }
100 };
101
102 /// Sets the current insert point to a previously-saved location.
104 if (IP.isSet())
105 setInsertPoint(IP.getBlock(), IP.getPoint());
106 else
108 }
109
110 /// This specifies that created VPInstructions should be appended to the end
111 /// of the specified block.
113 assert(TheBB && "Attempting to set a null insert point");
114 BB = TheBB;
115 InsertPt = BB->end();
116 }
117
118 /// This specifies that created instructions should be inserted at the
119 /// specified point.
121 BB = TheBB;
122 InsertPt = IP;
123 }
124
125 /// This specifies that created instructions should be inserted at the
126 /// specified point.
128 BB = IP->getParent();
129 InsertPt = IP->getIterator();
130 }
131
132 /// Create an N-ary operation with \p Opcode, \p Operands and set \p Inst as
133 /// its underlying Instruction.
135 Instruction *Inst = nullptr, const Twine &Name = "") {
136 DebugLoc DL;
137 if (Inst)
138 DL = Inst->getDebugLoc();
139 VPInstruction *NewVPInst = createInstruction(Opcode, Operands, DL, Name);
140 NewVPInst->setUnderlyingValue(Inst);
141 return NewVPInst;
142 }
144 DebugLoc DL, const Twine &Name = "") {
145 return createInstruction(Opcode, Operands, DL, Name);
146 }
147
149 std::initializer_list<VPValue *> Operands,
151 DebugLoc DL, const Twine &Name = "") {
152 return tryInsertInstruction(
153 new VPInstruction(Opcode, Operands, WrapFlags, DL, Name));
154 }
155 VPValue *createNot(VPValue *Operand, DebugLoc DL, const Twine &Name = "") {
156 return createInstruction(VPInstruction::Not, {Operand}, DL, Name);
157 }
158
160 const Twine &Name = "") {
161 return createInstruction(Instruction::BinaryOps::And, {LHS, RHS}, DL, Name);
162 }
163
165 const Twine &Name = "") {
166 return createInstruction(Instruction::BinaryOps::Or, {LHS, RHS}, DL, Name);
167 }
168
170 DebugLoc DL, const Twine &Name = "") {
171 return createNaryOp(Instruction::Select, {Cond, TrueVal, FalseVal}, DL,
172 Name);
173 }
174
175 /// Create a new ICmp VPInstruction with predicate \p Pred and operands \p A
176 /// and \p B.
177 /// TODO: add createFCmp when needed.
179 DebugLoc DL = {}, const Twine &Name = "");
180
181 //===--------------------------------------------------------------------===//
182 // RAII helpers.
183 //===--------------------------------------------------------------------===//
184
185 /// RAII object that stores the current insertion point and restores it when
186 /// the object is destroyed.
188 VPBuilder &Builder;
189 VPBasicBlock *Block;
191
192 public:
194 : Builder(B), Block(B.getInsertBlock()), Point(B.getInsertPoint()) {}
195
198
199 ~InsertPointGuard() { Builder.restoreIP(VPInsertPoint(Block, Point)); }
200 };
201};
202
203/// TODO: The following VectorizationFactor was pulled out of
204/// LoopVectorizationCostModel class. LV also deals with
205/// VectorizerParams::VectorizationFactor and VectorizationCostTy.
206/// We need to streamline them.
207
208/// Information about vectorization costs.
210 /// Vector width with best cost.
212
213 /// Cost of the loop with that width.
215
216 /// Cost of the scalar loop.
218
219 /// The minimum trip count required to make vectorization profitable, e.g. due
220 /// to runtime checks.
222
226
227 /// Width 1 means no vectorization, cost 0 means uncomputed cost.
229 return {ElementCount::getFixed(1), 0, 0};
230 }
231
232 bool operator==(const VectorizationFactor &rhs) const {
233 return Width == rhs.Width && Cost == rhs.Cost;
234 }
235
236 bool operator!=(const VectorizationFactor &rhs) const {
237 return !(*this == rhs);
238 }
239};
240
241/// ElementCountComparator creates a total ordering for ElementCount
242/// for the purposes of using it in a set structure.
244 bool operator()(const ElementCount &LHS, const ElementCount &RHS) const {
245 return std::make_tuple(LHS.isScalable(), LHS.getKnownMinValue()) <
246 std::make_tuple(RHS.isScalable(), RHS.getKnownMinValue());
247 }
248};
250
251/// A class that represents two vectorization factors (initialized with 0 by
252/// default). One for fixed-width vectorization and one for scalable
253/// vectorization. This can be used by the vectorizer to choose from a range of
254/// fixed and/or scalable VFs in order to find the most cost-effective VF to
255/// vectorize with.
259
261 : FixedVF(ElementCount::getFixed(0)),
262 ScalableVF(ElementCount::getScalable(0)) {}
264 *(Max.isScalable() ? &ScalableVF : &FixedVF) = Max;
265 }
270 "Invalid scalable properties");
271 }
272
274
275 /// \return true if either fixed- or scalable VF is non-zero.
276 explicit operator bool() const { return FixedVF || ScalableVF; }
277
278 /// \return true if either fixed- or scalable VF is a valid vector VF.
279 bool hasVector() const { return FixedVF.isVector() || ScalableVF.isVector(); }
280};
281
282/// Planner drives the vectorization process after having passed
283/// Legality checks.
285 /// The loop that we evaluate.
286 Loop *OrigLoop;
287
288 /// Loop Info analysis.
289 LoopInfo *LI;
290
291 /// The dominator tree.
292 DominatorTree *DT;
293
294 /// Target Library Info.
295 const TargetLibraryInfo *TLI;
296
297 /// Target Transform Info.
299
300 /// The legality analysis.
302
303 /// The profitability analysis.
305
306 /// The interleaved access analysis.
308
310
311 const LoopVectorizeHints &Hints;
312
314
316
317 /// Profitable vector factors.
319
320 /// A builder used to construct the current plan.
321 VPBuilder Builder;
322
323public:
325 Loop *L, LoopInfo *LI, DominatorTree *DT, const TargetLibraryInfo *TLI,
330 : OrigLoop(L), LI(LI), DT(DT), TLI(TLI), TTI(TTI), Legal(Legal), CM(CM),
331 IAI(IAI), PSE(PSE), Hints(Hints), ORE(ORE) {}
332
333 /// Plan how to best vectorize, return the best VF and its cost, or
334 /// std::nullopt if vectorization and interleaving should be avoided up front.
335 std::optional<VectorizationFactor> plan(ElementCount UserVF, unsigned UserIC);
336
337 /// Use the VPlan-native path to plan how to best vectorize, return the best
338 /// VF and its cost.
340
341 /// Return the best VPlan for \p VF.
343
344 /// Generate the IR code for the body of the vectorized loop according to the
345 /// best selected \p VF, \p UF and VPlan \p BestPlan.
346 /// TODO: \p IsEpilogueVectorization is needed to avoid issues due to epilogue
347 /// vectorization re-using plans for both the main and epilogue vector loops.
348 /// It should be removed once the re-use issue has been fixed.
349 /// \p ExpandedSCEVs is passed during execution of the plan for epilogue loop
350 /// to re-use expansion results generated during main plan execution. Returns
351 /// a mapping of SCEVs to their expanded IR values. Note that this is a
352 /// temporary workaround needed due to the current epilogue handling.
354 executePlan(ElementCount VF, unsigned UF, VPlan &BestPlan,
356 bool IsEpilogueVectorization,
357 const DenseMap<const SCEV *, Value *> *ExpandedSCEVs = nullptr);
358
359#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
360 void printPlans(raw_ostream &O);
361#endif
362
363 /// Look through the existing plans and return true if we have one with
364 /// vectorization factor \p VF.
366 return any_of(VPlans,
367 [&](const VPlanPtr &Plan) { return Plan->hasVF(VF); });
368 }
369
370 /// Test a \p Predicate on a \p Range of VF's. Return the value of applying
371 /// \p Predicate on Range.Start, possibly decreasing Range.End such that the
372 /// returned value holds for the entire \p Range.
373 static bool
374 getDecisionAndClampRange(const std::function<bool(ElementCount)> &Predicate,
375 VFRange &Range);
376
377 /// \return The most profitable vectorization factor and the cost of that VF
378 /// for vectorizing the epilogue. Returns VectorizationFactor::Disabled if
379 /// epilogue vectorization is not supported for the loop.
381 selectEpilogueVectorizationFactor(const ElementCount MaxVF, unsigned IC);
382
383protected:
384 /// Build VPlans for power-of-2 VF's between \p MinVF and \p MaxVF inclusive,
385 /// according to the information gathered by Legal when it checked if it is
386 /// legal to vectorize the loop.
387 void buildVPlans(ElementCount MinVF, ElementCount MaxVF);
388
389private:
390 /// Build a VPlan according to the information gathered by Legal. \return a
391 /// VPlan for vectorization factors \p Range.Start and up to \p Range.End
392 /// exclusive, possibly decreasing \p Range.End.
393 VPlanPtr buildVPlan(VFRange &Range);
394
395 /// Build a VPlan using VPRecipes according to the information gather by
396 /// Legal. This method is only used for the legacy inner loop vectorizer.
397 /// \p Range's largest included VF is restricted to the maximum VF the
398 /// returned VPlan is valid for. If no VPlan can be built for the input range,
399 /// set the largest included VF to the maximum VF for which no plan could be
400 /// built.
401 VPlanPtr tryToBuildVPlanWithVPRecipes(VFRange &Range);
402
403 /// Build VPlans for power-of-2 VF's between \p MinVF and \p MaxVF inclusive,
404 /// according to the information gathered by Legal when it checked if it is
405 /// legal to vectorize the loop. This method creates VPlans using VPRecipes.
406 void buildVPlansWithVPRecipes(ElementCount MinVF, ElementCount MaxVF);
407
408 // Adjust the recipes for reductions. For in-loop reductions the chain of
409 // instructions leading from the loop exit instr to the phi need to be
410 // converted to reductions, with one operand being vector and the other being
411 // the scalar reduction chain. For other reductions, a select is introduced
412 // between the phi and live-out recipes when folding the tail.
413 void adjustRecipesForReductions(VPBasicBlock *LatchVPBB, VPlanPtr &Plan,
414 VPRecipeBuilder &RecipeBuilder,
415 ElementCount MinVF);
416
417 /// \return The most profitable vectorization factor and the cost of that VF.
418 /// This method checks every VF in \p CandidateVFs.
420 selectVectorizationFactor(const ElementCountSet &CandidateVFs);
421
422 /// Returns true if the per-lane cost of VectorizationFactor A is lower than
423 /// that of B.
424 bool isMoreProfitable(const VectorizationFactor &A,
425 const VectorizationFactor &B) const;
426
427 /// Determines if we have the infrastructure to vectorize the loop and its
428 /// epilogue, assuming the main loop is vectorized by \p VF.
429 bool isCandidateForEpilogueVectorization(const ElementCount VF) const;
430};
431
432} // namespace llvm
433
434#endif // LLVM_TRANSFORMS_VECTORIZE_LOOPVECTORIZATIONPLANNER_H
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
std::string Name
This file defines an InstructionCost class that is used when calculating the cost of an instruction,...
mir Rename Register Operands
const SmallVectorImpl< MachineOperand > & Cond
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
This file defines the SmallSet class.
This file contains the declarations of the Vectorization Plan base classes:
Value * RHS
Value * LHS
static constexpr uint32_t Opcode
Definition: aarch32.h:200
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: ArrayRef.h:41
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:748
A debug info location.
Definition: DebugLoc.h:33
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree.
Definition: Dominators.h:165
constexpr bool isVector() const
One or more elements.
Definition: TypeSize.h:312
static constexpr ElementCount getFixed(ScalarTy MinVal)
Definition: TypeSize.h:297
InnerLoopVectorizer vectorizes loops which contain only one basic block to a specified vectorization ...
Drive the analysis of interleaved memory accesses in the loop.
Definition: VectorUtils.h:756
LoopVectorizationCostModel - estimates the expected speedups due to vectorization.
LoopVectorizationLegality checks if it is legal to vectorize a loop, and to what vectorization factor...
Planner drives the vectorization process after having passed Legality checks.
std::optional< VectorizationFactor > plan(ElementCount UserVF, unsigned UserIC)
Plan how to best vectorize, return the best VF and its cost, or std::nullopt if vectorization and int...
VectorizationFactor selectEpilogueVectorizationFactor(const ElementCount MaxVF, unsigned IC)
LoopVectorizationPlanner(Loop *L, LoopInfo *LI, DominatorTree *DT, const TargetLibraryInfo *TLI, const TargetTransformInfo &TTI, LoopVectorizationLegality *Legal, LoopVectorizationCostModel &CM, InterleavedAccessInfo &IAI, PredicatedScalarEvolution &PSE, const LoopVectorizeHints &Hints, OptimizationRemarkEmitter *ORE)
VectorizationFactor planInVPlanNativePath(ElementCount UserVF)
Use the VPlan-native path to plan how to best vectorize, return the best VF and its cost.
void buildVPlans(ElementCount MinVF, ElementCount MaxVF)
Build VPlans for power-of-2 VF's between MinVF and MaxVF inclusive, according to the information gath...
DenseMap< const SCEV *, Value * > executePlan(ElementCount VF, unsigned UF, VPlan &BestPlan, InnerLoopVectorizer &LB, DominatorTree *DT, bool IsEpilogueVectorization, const DenseMap< const SCEV *, Value * > *ExpandedSCEVs=nullptr)
Generate the IR code for the body of the vectorized loop according to the best selected VF,...
VPlan & getBestPlanFor(ElementCount VF) const
Return the best VPlan for VF.
static bool getDecisionAndClampRange(const std::function< bool(ElementCount)> &Predicate, VFRange &Range)
Test a Predicate on a Range of VF's.
void printPlans(raw_ostream &O)
bool hasPlanWithVF(ElementCount VF) const
Look through the existing plans and return true if we have one with vectorization factor VF.
Utility class for getting and setting loop vectorizer hints in the form of loop metadata.
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:44
The optimization diagnostic interface.
An interface layer with SCEV used to manage how we see SCEV expressions for values in the context of ...
SmallSet - This maintains a set of unique values, optimizing for the case when the set is small (less...
Definition: SmallSet.h:135
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1200
Provides information about what library functions are available for the current target.
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
VPBasicBlock serves as the leaf of the Hierarchical Control-Flow Graph.
Definition: VPlan.h:2260
RecipeListTy::iterator iterator
Instruction iterators...
Definition: VPlan.h:2281
iterator end()
Definition: VPlan.h:2291
void insert(VPRecipeBase *Recipe, iterator InsertPt)
Definition: VPlan.h:2319
RAII object that stores the current insertion point and restores it when the object is destroyed.
InsertPointGuard(const InsertPointGuard &)=delete
InsertPointGuard & operator=(const InsertPointGuard &)=delete
InsertPoint - A saved insertion point.
VPInsertPoint(VPBasicBlock *InsertBlock, VPBasicBlock::iterator InsertPoint)
Creates a new insertion point at the given location.
VPBasicBlock::iterator getPoint() const
VPInsertPoint()=default
Creates a new insertion point which doesn't point to anything.
bool isSet() const
Returns true if this insert point is set.
VPlan-based builder utility analogous to IRBuilder.
void setInsertPoint(VPBasicBlock *TheBB, VPBasicBlock::iterator IP)
This specifies that created instructions should be inserted at the specified point.
void setInsertPoint(VPRecipeBase *IP)
This specifies that created instructions should be inserted at the specified point.
void restoreIP(VPInsertPoint IP)
Sets the current insert point to a previously-saved location.
VPValue * createOr(VPValue *LHS, VPValue *RHS, DebugLoc DL, const Twine &Name="")
VPBasicBlock * getInsertBlock() const
VPBasicBlock::iterator getInsertPoint() const
VPInstruction * createOverflowingOp(unsigned Opcode, std::initializer_list< VPValue * > Operands, VPRecipeWithIRFlags::WrapFlagsTy WrapFlags, DebugLoc DL, const Twine &Name="")
VPBuilder(VPBasicBlock *InsertBB)
VPValue * createNot(VPValue *Operand, DebugLoc DL, const Twine &Name="")
VPValue * createNaryOp(unsigned Opcode, ArrayRef< VPValue * > Operands, Instruction *Inst=nullptr, const Twine &Name="")
Create an N-ary operation with Opcode, Operands and set Inst as its underlying Instruction.
VPValue * createICmp(CmpInst::Predicate Pred, VPValue *A, VPValue *B, DebugLoc DL={}, const Twine &Name="")
Create a new ICmp VPInstruction with predicate Pred and operands A and B.
VPValue * createNaryOp(unsigned Opcode, ArrayRef< VPValue * > Operands, DebugLoc DL, const Twine &Name="")
void clearInsertionPoint()
Clear the insertion point: created instructions will not be inserted into a block.
VPBuilder()=default
VPValue * createSelect(VPValue *Cond, VPValue *TrueVal, VPValue *FalseVal, DebugLoc DL, const Twine &Name="")
VPValue * createAnd(VPValue *LHS, VPValue *RHS, DebugLoc DL, const Twine &Name="")
void setInsertPoint(VPBasicBlock *TheBB)
This specifies that created VPInstructions should be appended to the end of the specified block.
This is a concrete Recipe that models a single VPlan-level instruction.
Definition: VPlan.h:1018
VPRecipeBase is a base class modeling a sequence of one or more output IR instructions.
Definition: VPlan.h:707
VPBasicBlock * getParent()
Definition: VPlan.h:729
Helper class to create VPRecipies from IR instructions.
void setUnderlyingValue(Value *Val)
Definition: VPlanValue.h:77
VPlan models a candidate for vectorization, encoding various decisions take to produce efficient outp...
Definition: VPlan.h:2481
constexpr bool isScalable() const
Returns whether the quantity is scaled by a runtime quantity (vscale).
Definition: TypeSize.h:172
self_iterator getIterator()
Definition: ilist_node.h:109
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:52
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
bool any_of(R &&range, UnaryPredicate P)
Provide wrappers to std::any_of which take ranges instead of having to pass begin/end explicitly.
Definition: STLExtras.h:1733
std::unique_ptr< VPlan > VPlanPtr
Definition: VPlan.h:132
ElementCountComparator creates a total ordering for ElementCount for the purposes of using it in a se...
bool operator()(const ElementCount &LHS, const ElementCount &RHS) const
A class that represents two vectorization factors (initialized with 0 by default).
FixedScalableVFPair(const ElementCount &FixedVF, const ElementCount &ScalableVF)
FixedScalableVFPair(const ElementCount &Max)
static FixedScalableVFPair getNone()
A range of powers-of-2 vectorization factors with fixed start and adjustable end.
Definition: VPlan.h:85
TODO: The following VectorizationFactor was pulled out of LoopVectorizationCostModel class.
InstructionCost Cost
Cost of the loop with that width.
ElementCount MinProfitableTripCount
The minimum trip count required to make vectorization profitable, e.g.
bool operator==(const VectorizationFactor &rhs) const
ElementCount Width
Vector width with best cost.
InstructionCost ScalarCost
Cost of the scalar loop.
bool operator!=(const VectorizationFactor &rhs) const
static VectorizationFactor Disabled()
Width 1 means no vectorization, cost 0 means uncomputed cost.
VectorizationFactor(ElementCount Width, InstructionCost Cost, InstructionCost ScalarCost)