Bug Summary

File:lib/Transforms/Vectorize/LoopVectorize.cpp
Warning:line 6201, column 11
Called C++ object pointer is null

Annotated Source Code

1//===- LoopVectorize.cpp - A Loop Vectorizer ------------------------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This is the LLVM loop vectorizer. This pass modifies 'vectorizable' loops
11// and generates target-independent LLVM-IR.
12// The vectorizer uses the TargetTransformInfo analysis to estimate the costs
13// of instructions in order to estimate the profitability of vectorization.
14//
15// The loop vectorizer combines consecutive loop iterations into a single
16// 'wide' iteration. After this transformation the index is incremented
17// by the SIMD vector width, and not by one.
18//
19// This pass has three parts:
20// 1. The main loop pass that drives the different parts.
21// 2. LoopVectorizationLegality - A unit that checks for the legality
22// of the vectorization.
23// 3. InnerLoopVectorizer - A unit that performs the actual
24// widening of instructions.
25// 4. LoopVectorizationCostModel - A unit that checks for the profitability
26// of vectorization. It decides on the optimal vector width, which
27// can be one, if vectorization is not profitable.
28//
29//===----------------------------------------------------------------------===//
30//
31// The reduction-variable vectorization is based on the paper:
32// D. Nuzman and R. Henderson. Multi-platform Auto-vectorization.
33//
34// Variable uniformity checks are inspired by:
35// Karrenberg, R. and Hack, S. Whole Function Vectorization.
36//
37// The interleaved access vectorization is based on the paper:
38// Dorit Nuzman, Ira Rosen and Ayal Zaks. Auto-Vectorization of Interleaved
39// Data for SIMD
40//
41// Other ideas/concepts are from:
42// A. Zaks and D. Nuzman. Autovectorization in GCC-two years later.
43//
44// S. Maleki, Y. Gao, M. Garzaran, T. Wong and D. Padua. An Evaluation of
45// Vectorizing Compilers.
46//
47//===----------------------------------------------------------------------===//
48
49#include "llvm/Transforms/Vectorize/LoopVectorize.h"
50#include "llvm/ADT/DenseMap.h"
51#include "llvm/ADT/Hashing.h"
52#include "llvm/ADT/MapVector.h"
53#include "llvm/ADT/Optional.h"
54#include "llvm/ADT/SCCIterator.h"
55#include "llvm/ADT/SetVector.h"
56#include "llvm/ADT/SmallPtrSet.h"
57#include "llvm/ADT/SmallSet.h"
58#include "llvm/ADT/SmallVector.h"
59#include "llvm/ADT/Statistic.h"
60#include "llvm/ADT/StringExtras.h"
61#include "llvm/Analysis/CodeMetrics.h"
62#include "llvm/Analysis/GlobalsModRef.h"
63#include "llvm/Analysis/LoopInfo.h"
64#include "llvm/Analysis/LoopIterator.h"
65#include "llvm/Analysis/LoopPass.h"
66#include "llvm/Analysis/ScalarEvolutionExpander.h"
67#include "llvm/Analysis/ScalarEvolutionExpressions.h"
68#include "llvm/Analysis/ValueTracking.h"
69#include "llvm/Analysis/VectorUtils.h"
70#include "llvm/IR/Constants.h"
71#include "llvm/IR/DataLayout.h"
72#include "llvm/IR/DebugInfo.h"
73#include "llvm/IR/DerivedTypes.h"
74#include "llvm/IR/DiagnosticInfo.h"
75#include "llvm/IR/Dominators.h"
76#include "llvm/IR/Function.h"
77#include "llvm/IR/IRBuilder.h"
78#include "llvm/IR/Instructions.h"
79#include "llvm/IR/IntrinsicInst.h"
80#include "llvm/IR/LLVMContext.h"
81#include "llvm/IR/Module.h"
82#include "llvm/IR/PatternMatch.h"
83#include "llvm/IR/Type.h"
84#include "llvm/IR/User.h"
85#include "llvm/IR/Value.h"
86#include "llvm/IR/ValueHandle.h"
87#include "llvm/IR/Verifier.h"
88#include "llvm/Pass.h"
89#include "llvm/Support/BranchProbability.h"
90#include "llvm/Support/CommandLine.h"
91#include "llvm/Support/Debug.h"
92#include "llvm/Support/raw_ostream.h"
93#include "llvm/Transforms/Scalar.h"
94#include "llvm/Transforms/Utils/BasicBlockUtils.h"
95#include "llvm/Transforms/Utils/Local.h"
96#include "llvm/Transforms/Utils/LoopSimplify.h"
97#include "llvm/Transforms/Utils/LoopUtils.h"
98#include "llvm/Transforms/Utils/LoopVersioning.h"
99#include "llvm/Transforms/Vectorize.h"
100#include <algorithm>
101#include <map>
102#include <tuple>
103
104using namespace llvm;
105using namespace llvm::PatternMatch;
106
107#define LV_NAME"loop-vectorize" "loop-vectorize"
108#define DEBUG_TYPE"loop-vectorize" LV_NAME"loop-vectorize"
109
110STATISTIC(LoopsVectorized, "Number of loops vectorized")static llvm::Statistic LoopsVectorized = {"loop-vectorize", "LoopsVectorized"
, "Number of loops vectorized", {0}, false}
;
111STATISTIC(LoopsAnalyzed, "Number of loops analyzed for vectorization")static llvm::Statistic LoopsAnalyzed = {"loop-vectorize", "LoopsAnalyzed"
, "Number of loops analyzed for vectorization", {0}, false}
;
112
113static cl::opt<bool>
114 EnableIfConversion("enable-if-conversion", cl::init(true), cl::Hidden,
115 cl::desc("Enable if-conversion during vectorization."));
116
117/// We don't vectorize loops with a known constant trip count below this number.
118static cl::opt<unsigned> TinyTripCountVectorThreshold(
119 "vectorizer-min-trip-count", cl::init(16), cl::Hidden,
120 cl::desc("Don't vectorize loops with a constant "
121 "trip count that is smaller than this "
122 "value."));
123
124static cl::opt<bool> MaximizeBandwidth(
125 "vectorizer-maximize-bandwidth", cl::init(false), cl::Hidden,
126 cl::desc("Maximize bandwidth when selecting vectorization factor which "
127 "will be determined by the smallest type in loop."));
128
129static cl::opt<bool> EnableInterleavedMemAccesses(
130 "enable-interleaved-mem-accesses", cl::init(false), cl::Hidden,
131 cl::desc("Enable vectorization on interleaved memory accesses in a loop"));
132
133/// Maximum factor for an interleaved memory access.
134static cl::opt<unsigned> MaxInterleaveGroupFactor(
135 "max-interleave-group-factor", cl::Hidden,
136 cl::desc("Maximum factor for an interleaved access group (default = 8)"),
137 cl::init(8));
138
139/// We don't interleave loops with a known constant trip count below this
140/// number.
141static const unsigned TinyTripCountInterleaveThreshold = 128;
142
143static cl::opt<unsigned> ForceTargetNumScalarRegs(
144 "force-target-num-scalar-regs", cl::init(0), cl::Hidden,
145 cl::desc("A flag that overrides the target's number of scalar registers."));
146
147static cl::opt<unsigned> ForceTargetNumVectorRegs(
148 "force-target-num-vector-regs", cl::init(0), cl::Hidden,
149 cl::desc("A flag that overrides the target's number of vector registers."));
150
151/// Maximum vectorization interleave count.
152static const unsigned MaxInterleaveFactor = 16;
153
154static cl::opt<unsigned> ForceTargetMaxScalarInterleaveFactor(
155 "force-target-max-scalar-interleave", cl::init(0), cl::Hidden,
156 cl::desc("A flag that overrides the target's max interleave factor for "
157 "scalar loops."));
158
159static cl::opt<unsigned> ForceTargetMaxVectorInterleaveFactor(
160 "force-target-max-vector-interleave", cl::init(0), cl::Hidden,
161 cl::desc("A flag that overrides the target's max interleave factor for "
162 "vectorized loops."));
163
164static cl::opt<unsigned> ForceTargetInstructionCost(
165 "force-target-instruction-cost", cl::init(0), cl::Hidden,
166 cl::desc("A flag that overrides the target's expected cost for "
167 "an instruction to a single constant value. Mostly "
168 "useful for getting consistent testing."));
169
170static cl::opt<unsigned> SmallLoopCost(
171 "small-loop-cost", cl::init(20), cl::Hidden,
172 cl::desc(
173 "The cost of a loop that is considered 'small' by the interleaver."));
174
175static cl::opt<bool> LoopVectorizeWithBlockFrequency(
176 "loop-vectorize-with-block-frequency", cl::init(false), cl::Hidden,
177 cl::desc("Enable the use of the block frequency analysis to access PGO "
178 "heuristics minimizing code growth in cold regions and being more "
179 "aggressive in hot regions."));
180
181// Runtime interleave loops for load/store throughput.
182static cl::opt<bool> EnableLoadStoreRuntimeInterleave(
183 "enable-loadstore-runtime-interleave", cl::init(true), cl::Hidden,
184 cl::desc(
185 "Enable runtime interleaving until load/store ports are saturated"));
186
187/// The number of stores in a loop that are allowed to need predication.
188static cl::opt<unsigned> NumberOfStoresToPredicate(
189 "vectorize-num-stores-pred", cl::init(1), cl::Hidden,
190 cl::desc("Max number of stores to be predicated behind an if."));
191
192static cl::opt<bool> EnableIndVarRegisterHeur(
193 "enable-ind-var-reg-heur", cl::init(true), cl::Hidden,
194 cl::desc("Count the induction variable only once when interleaving"));
195
196static cl::opt<bool> EnableCondStoresVectorization(
197 "enable-cond-stores-vec", cl::init(true), cl::Hidden,
198 cl::desc("Enable if predication of stores during vectorization."));
199
200static cl::opt<unsigned> MaxNestedScalarReductionIC(
201 "max-nested-scalar-reduction-interleave", cl::init(2), cl::Hidden,
202 cl::desc("The maximum interleave count to use when interleaving a scalar "
203 "reduction in a nested loop."));
204
205static cl::opt<unsigned> PragmaVectorizeMemoryCheckThreshold(
206 "pragma-vectorize-memory-check-threshold", cl::init(128), cl::Hidden,
207 cl::desc("The maximum allowed number of runtime memory checks with a "
208 "vectorize(enable) pragma."));
209
210static cl::opt<unsigned> VectorizeSCEVCheckThreshold(
211 "vectorize-scev-check-threshold", cl::init(16), cl::Hidden,
212 cl::desc("The maximum number of SCEV checks allowed."));
213
214static cl::opt<unsigned> PragmaVectorizeSCEVCheckThreshold(
215 "pragma-vectorize-scev-check-threshold", cl::init(128), cl::Hidden,
216 cl::desc("The maximum number of SCEV checks allowed with a "
217 "vectorize(enable) pragma"));
218
219/// Create an analysis remark that explains why vectorization failed
220///
221/// \p PassName is the name of the pass (e.g. can be AlwaysPrint). \p
222/// RemarkName is the identifier for the remark. If \p I is passed it is an
223/// instruction that prevents vectorization. Otherwise \p TheLoop is used for
224/// the location of the remark. \return the remark object that can be
225/// streamed to.
226static OptimizationRemarkAnalysis
227createMissedAnalysis(const char *PassName, StringRef RemarkName, Loop *TheLoop,
228 Instruction *I = nullptr) {
229 Value *CodeRegion = TheLoop->getHeader();
230 DebugLoc DL = TheLoop->getStartLoc();
231
232 if (I) {
233 CodeRegion = I->getParent();
234 // If there is no debug location attached to the instruction, revert back to
235 // using the loop's.
236 if (I->getDebugLoc())
237 DL = I->getDebugLoc();
238 }
239
240 OptimizationRemarkAnalysis R(PassName, RemarkName, DL, CodeRegion);
241 R << "loop not vectorized: ";
242 return R;
243}
244
245namespace {
246
247// Forward declarations.
248class LoopVectorizeHints;
249class LoopVectorizationLegality;
250class LoopVectorizationCostModel;
251class LoopVectorizationRequirements;
252
253/// Returns true if the given loop body has a cycle, excluding the loop
254/// itself.
255static bool hasCyclesInLoopBody(const Loop &L) {
256 if (!L.empty())
257 return true;
258
259 for (const auto &SCC :
260 make_range(scc_iterator<Loop, LoopBodyTraits>::begin(L),
261 scc_iterator<Loop, LoopBodyTraits>::end(L))) {
262 if (SCC.size() > 1) {
263 DEBUG(dbgs() << "LVL: Detected a cycle in the loop body:\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LVL: Detected a cycle in the loop body:\n"
; } } while (false)
;
264 DEBUG(L.dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { L.dump(); } } while (false)
;
265 return true;
266 }
267 }
268 return false;
269}
270
271/// A helper function for converting Scalar types to vector types.
272/// If the incoming type is void, we return void. If the VF is 1, we return
273/// the scalar type.
274static Type *ToVectorTy(Type *Scalar, unsigned VF) {
275 if (Scalar->isVoidTy() || VF == 1)
276 return Scalar;
277 return VectorType::get(Scalar, VF);
278}
279
280// FIXME: The following helper functions have multiple implementations
281// in the project. They can be effectively organized in a common Load/Store
282// utilities unit.
283
284/// A helper function that returns the pointer operand of a load or store
285/// instruction.
286static Value *getPointerOperand(Value *I) {
287 if (auto *LI = dyn_cast<LoadInst>(I))
288 return LI->getPointerOperand();
289 if (auto *SI = dyn_cast<StoreInst>(I))
290 return SI->getPointerOperand();
291 return nullptr;
292}
293
294/// A helper function that returns the type of loaded or stored value.
295static Type *getMemInstValueType(Value *I) {
296 assert((isa<LoadInst>(I) || isa<StoreInst>(I)) &&(((isa<LoadInst>(I) || isa<StoreInst>(I)) &&
"Expected Load or Store instruction") ? static_cast<void>
(0) : __assert_fail ("(isa<LoadInst>(I) || isa<StoreInst>(I)) && \"Expected Load or Store instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 297, __PRETTY_FUNCTION__))
297 "Expected Load or Store instruction")(((isa<LoadInst>(I) || isa<StoreInst>(I)) &&
"Expected Load or Store instruction") ? static_cast<void>
(0) : __assert_fail ("(isa<LoadInst>(I) || isa<StoreInst>(I)) && \"Expected Load or Store instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 297, __PRETTY_FUNCTION__))
;
298 if (auto *LI = dyn_cast<LoadInst>(I))
299 return LI->getType();
300 return cast<StoreInst>(I)->getValueOperand()->getType();
301}
302
303/// A helper function that returns the alignment of load or store instruction.
304static unsigned getMemInstAlignment(Value *I) {
305 assert((isa<LoadInst>(I) || isa<StoreInst>(I)) &&(((isa<LoadInst>(I) || isa<StoreInst>(I)) &&
"Expected Load or Store instruction") ? static_cast<void>
(0) : __assert_fail ("(isa<LoadInst>(I) || isa<StoreInst>(I)) && \"Expected Load or Store instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 306, __PRETTY_FUNCTION__))
306 "Expected Load or Store instruction")(((isa<LoadInst>(I) || isa<StoreInst>(I)) &&
"Expected Load or Store instruction") ? static_cast<void>
(0) : __assert_fail ("(isa<LoadInst>(I) || isa<StoreInst>(I)) && \"Expected Load or Store instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 306, __PRETTY_FUNCTION__))
;
307 if (auto *LI = dyn_cast<LoadInst>(I))
308 return LI->getAlignment();
309 return cast<StoreInst>(I)->getAlignment();
310}
311
312/// A helper function that returns the address space of the pointer operand of
313/// load or store instruction.
314static unsigned getMemInstAddressSpace(Value *I) {
315 assert((isa<LoadInst>(I) || isa<StoreInst>(I)) &&(((isa<LoadInst>(I) || isa<StoreInst>(I)) &&
"Expected Load or Store instruction") ? static_cast<void>
(0) : __assert_fail ("(isa<LoadInst>(I) || isa<StoreInst>(I)) && \"Expected Load or Store instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 316, __PRETTY_FUNCTION__))
316 "Expected Load or Store instruction")(((isa<LoadInst>(I) || isa<StoreInst>(I)) &&
"Expected Load or Store instruction") ? static_cast<void>
(0) : __assert_fail ("(isa<LoadInst>(I) || isa<StoreInst>(I)) && \"Expected Load or Store instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 316, __PRETTY_FUNCTION__))
;
317 if (auto *LI = dyn_cast<LoadInst>(I))
318 return LI->getPointerAddressSpace();
319 return cast<StoreInst>(I)->getPointerAddressSpace();
320}
321
322/// A helper function that returns true if the given type is irregular. The
323/// type is irregular if its allocated size doesn't equal the store size of an
324/// element of the corresponding vector type at the given vectorization factor.
325static bool hasIrregularType(Type *Ty, const DataLayout &DL, unsigned VF) {
326
327 // Determine if an array of VF elements of type Ty is "bitcast compatible"
328 // with a <VF x Ty> vector.
329 if (VF > 1) {
330 auto *VectorTy = VectorType::get(Ty, VF);
331 return VF * DL.getTypeAllocSize(Ty) != DL.getTypeStoreSize(VectorTy);
332 }
333
334 // If the vectorization factor is one, we just check if an array of type Ty
335 // requires padding between elements.
336 return DL.getTypeAllocSizeInBits(Ty) != DL.getTypeSizeInBits(Ty);
337}
338
339/// A helper function that returns the reciprocal of the block probability of
340/// predicated blocks. If we return X, we are assuming the predicated block
341/// will execute once for for every X iterations of the loop header.
342///
343/// TODO: We should use actual block probability here, if available. Currently,
344/// we always assume predicated blocks have a 50% chance of executing.
345static unsigned getReciprocalPredBlockProb() { return 2; }
346
347/// A helper function that adds a 'fast' flag to floating-point operations.
348static Value *addFastMathFlag(Value *V) {
349 if (isa<FPMathOperator>(V)) {
350 FastMathFlags Flags;
351 Flags.setUnsafeAlgebra();
352 cast<Instruction>(V)->setFastMathFlags(Flags);
353 }
354 return V;
355}
356
357/// A helper function that returns an integer or floating-point constant with
358/// value C.
359static Constant *getSignedIntOrFpConstant(Type *Ty, int64_t C) {
360 return Ty->isIntegerTy() ? ConstantInt::getSigned(Ty, C)
361 : ConstantFP::get(Ty, C);
362}
363
364/// InnerLoopVectorizer vectorizes loops which contain only one basic
365/// block to a specified vectorization factor (VF).
366/// This class performs the widening of scalars into vectors, or multiple
367/// scalars. This class also implements the following features:
368/// * It inserts an epilogue loop for handling loops that don't have iteration
369/// counts that are known to be a multiple of the vectorization factor.
370/// * It handles the code generation for reduction variables.
371/// * Scalarization (implementation using scalars) of un-vectorizable
372/// instructions.
373/// InnerLoopVectorizer does not perform any vectorization-legality
374/// checks, and relies on the caller to check for the different legality
375/// aspects. The InnerLoopVectorizer relies on the
376/// LoopVectorizationLegality class to provide information about the induction
377/// and reduction variables that were found to a given vectorization factor.
378class InnerLoopVectorizer {
379public:
380 InnerLoopVectorizer(Loop *OrigLoop, PredicatedScalarEvolution &PSE,
381 LoopInfo *LI, DominatorTree *DT,
382 const TargetLibraryInfo *TLI,
383 const TargetTransformInfo *TTI, AssumptionCache *AC,
384 OptimizationRemarkEmitter *ORE, unsigned VecWidth,
385 unsigned UnrollFactor, LoopVectorizationLegality *LVL,
386 LoopVectorizationCostModel *CM)
387 : OrigLoop(OrigLoop), PSE(PSE), LI(LI), DT(DT), TLI(TLI), TTI(TTI),
388 AC(AC), ORE(ORE), VF(VecWidth), UF(UnrollFactor),
389 Builder(PSE.getSE()->getContext()), Induction(nullptr),
390 OldInduction(nullptr), VectorLoopValueMap(UnrollFactor, VecWidth),
391 TripCount(nullptr), VectorTripCount(nullptr), Legal(LVL), Cost(CM),
392 AddedSafetyChecks(false) {}
393
394 /// Create a new empty loop. Unlink the old loop and connect the new one.
395 void createVectorizedLoopSkeleton();
396
397 /// Vectorize a single instruction within the innermost loop.
398 void vectorizeInstruction(Instruction &I);
399
400 /// Fix the vectorized code, taking care of header phi's, live-outs, and more.
401 void fixVectorizedLoop();
402
403 // Return true if any runtime check is added.
404 bool areSafetyChecksAdded() { return AddedSafetyChecks; }
405
406 virtual ~InnerLoopVectorizer() {}
407
408protected:
409 /// A small list of PHINodes.
410 typedef SmallVector<PHINode *, 4> PhiVector;
411
412 /// A type for vectorized values in the new loop. Each value from the
413 /// original loop, when vectorized, is represented by UF vector values in the
414 /// new unrolled loop, where UF is the unroll factor.
415 typedef SmallVector<Value *, 2> VectorParts;
416
417 /// A type for scalarized values in the new loop. Each value from the
418 /// original loop, when scalarized, is represented by UF x VF scalar values
419 /// in the new unrolled loop, where UF is the unroll factor and VF is the
420 /// vectorization factor.
421 typedef SmallVector<SmallVector<Value *, 4>, 2> ScalarParts;
422
423 // When we if-convert we need to create edge masks. We have to cache values
424 // so that we don't end up with exponential recursion/IR.
425 typedef DenseMap<std::pair<BasicBlock *, BasicBlock *>, VectorParts>
426 EdgeMaskCacheTy;
427 typedef DenseMap<BasicBlock *, VectorParts> BlockMaskCacheTy;
428
429 /// Set up the values of the IVs correctly when exiting the vector loop.
430 void fixupIVUsers(PHINode *OrigPhi, const InductionDescriptor &II,
431 Value *CountRoundDown, Value *EndValue,
432 BasicBlock *MiddleBlock);
433
434 /// Create a new induction variable inside L.
435 PHINode *createInductionVariable(Loop *L, Value *Start, Value *End,
436 Value *Step, Instruction *DL);
437
438 /// Handle all cross-iteration phis in the header.
439 void fixCrossIterationPHIs();
440
441 /// Fix a first-order recurrence. This is the second phase of vectorizing
442 /// this phi node.
443 void fixFirstOrderRecurrence(PHINode *Phi);
444
445 /// Fix a reduction cross-iteration phi. This is the second phase of
446 /// vectorizing this phi node.
447 void fixReduction(PHINode *Phi);
448
449 /// \brief The Loop exit block may have single value PHI nodes with some
450 /// incoming value. While vectorizing we only handled real values
451 /// that were defined inside the loop and we should have one value for
452 /// each predecessor of its parent basic block. See PR14725.
453 void fixLCSSAPHIs();
454
455 /// Iteratively sink the scalarized operands of a predicated instruction into
456 /// the block that was created for it.
457 void sinkScalarOperands(Instruction *PredInst);
458
459 /// Predicate conditional instructions that require predication on their
460 /// respective conditions.
461 void predicateInstructions();
462
463 /// Shrinks vector element sizes to the smallest bitwidth they can be legally
464 /// represented as.
465 void truncateToMinimalBitwidths();
466
467 /// A helper function that computes the predicate of the block BB, assuming
468 /// that the header block of the loop is set to True. It returns the *entry*
469 /// mask for the block BB.
470 VectorParts createBlockInMask(BasicBlock *BB);
471 /// A helper function that computes the predicate of the edge between SRC
472 /// and DST.
473 VectorParts createEdgeMask(BasicBlock *Src, BasicBlock *Dst);
474
475 /// Vectorize a single PHINode in a block. This method handles the induction
476 /// variable canonicalization. It supports both VF = 1 for unrolled loops and
477 /// arbitrary length vectors.
478 void widenPHIInstruction(Instruction *PN, unsigned UF, unsigned VF);
479
480 /// Insert the new loop to the loop hierarchy and pass manager
481 /// and update the analysis passes.
482 void updateAnalysis();
483
484 /// This instruction is un-vectorizable. Implement it as a sequence
485 /// of scalars. If \p IfPredicateInstr is true we need to 'hide' each
486 /// scalarized instruction behind an if block predicated on the control
487 /// dependence of the instruction.
488 void scalarizeInstruction(Instruction *Instr, bool IfPredicateInstr = false);
489
490 /// Vectorize Load and Store instructions,
491 virtual void vectorizeMemoryInstruction(Instruction *Instr);
492
493 /// Create a broadcast instruction. This method generates a broadcast
494 /// instruction (shuffle) for loop invariant values and for the induction
495 /// value. If this is the induction variable then we extend it to N, N+1, ...
496 /// this is needed because each iteration in the loop corresponds to a SIMD
497 /// element.
498 virtual Value *getBroadcastInstrs(Value *V);
499
500 /// This function adds (StartIdx, StartIdx + Step, StartIdx + 2*Step, ...)
501 /// to each vector element of Val. The sequence starts at StartIndex.
502 /// \p Opcode is relevant for FP induction variable.
503 virtual Value *getStepVector(Value *Val, int StartIdx, Value *Step,
504 Instruction::BinaryOps Opcode =
505 Instruction::BinaryOpsEnd);
506
507 /// Compute scalar induction steps. \p ScalarIV is the scalar induction
508 /// variable on which to base the steps, \p Step is the size of the step, and
509 /// \p EntryVal is the value from the original loop that maps to the steps.
510 /// Note that \p EntryVal doesn't have to be an induction variable (e.g., it
511 /// can be a truncate instruction).
512 void buildScalarSteps(Value *ScalarIV, Value *Step, Value *EntryVal,
513 const InductionDescriptor &ID);
514
515 /// Create a vector induction phi node based on an existing scalar one. \p
516 /// EntryVal is the value from the original loop that maps to the vector phi
517 /// node, and \p Step is the loop-invariant step. If \p EntryVal is a
518 /// truncate instruction, instead of widening the original IV, we widen a
519 /// version of the IV truncated to \p EntryVal's type.
520 void createVectorIntOrFpInductionPHI(const InductionDescriptor &II,
521 Value *Step, Instruction *EntryVal);
522
523 /// Widen an integer or floating-point induction variable \p IV. If \p Trunc
524 /// is provided, the integer induction variable will first be truncated to
525 /// the corresponding type.
526 void widenIntOrFpInduction(PHINode *IV, TruncInst *Trunc = nullptr);
527
528 /// Returns true if an instruction \p I should be scalarized instead of
529 /// vectorized for the chosen vectorization factor.
530 bool shouldScalarizeInstruction(Instruction *I) const;
531
532 /// Returns true if we should generate a scalar version of \p IV.
533 bool needsScalarInduction(Instruction *IV) const;
534
535 /// getOrCreateVectorValue and getOrCreateScalarValue coordinate to generate a
536 /// vector or scalar value on-demand if one is not yet available. When
537 /// vectorizing a loop, we visit the definition of an instruction before its
538 /// uses. When visiting the definition, we either vectorize or scalarize the
539 /// instruction, creating an entry for it in the corresponding map. (In some
540 /// cases, such as induction variables, we will create both vector and scalar
541 /// entries.) Then, as we encounter uses of the definition, we derive values
542 /// for each scalar or vector use unless such a value is already available.
543 /// For example, if we scalarize a definition and one of its uses is vector,
544 /// we build the required vector on-demand with an insertelement sequence
545 /// when visiting the use. Otherwise, if the use is scalar, we can use the
546 /// existing scalar definition.
547 ///
548 /// Return a value in the new loop corresponding to \p V from the original
549 /// loop at unroll index \p Part. If the value has already been vectorized,
550 /// the corresponding vector entry in VectorLoopValueMap is returned. If,
551 /// however, the value has a scalar entry in VectorLoopValueMap, we construct
552 /// a new vector value on-demand by inserting the scalar values into a vector
553 /// with an insertelement sequence. If the value has been neither vectorized
554 /// nor scalarized, it must be loop invariant, so we simply broadcast the
555 /// value into a vector.
556 Value *getOrCreateVectorValue(Value *V, unsigned Part);
557
558 /// Return a value in the new loop corresponding to \p V from the original
559 /// loop at unroll index \p Part and vector index \p Lane. If the value has
560 /// been vectorized but not scalarized, the necessary extractelement
561 /// instruction will be generated.
562 Value *getOrCreateScalarValue(Value *V, unsigned Part, unsigned Lane);
563
564 /// Try to vectorize the interleaved access group that \p Instr belongs to.
565 void vectorizeInterleaveGroup(Instruction *Instr);
566
567 /// Generate a shuffle sequence that will reverse the vector Vec.
568 virtual Value *reverseVector(Value *Vec);
569
570 /// Returns (and creates if needed) the original loop trip count.
571 Value *getOrCreateTripCount(Loop *NewLoop);
572
573 /// Returns (and creates if needed) the trip count of the widened loop.
574 Value *getOrCreateVectorTripCount(Loop *NewLoop);
575
576 /// Emit a bypass check to see if the trip count would overflow, or we
577 /// wouldn't have enough iterations to execute one vector loop.
578 void emitMinimumIterationCountCheck(Loop *L, BasicBlock *Bypass);
579 /// Emit a bypass check to see if the vector trip count is nonzero.
580 void emitVectorLoopEnteredCheck(Loop *L, BasicBlock *Bypass);
581 /// Emit a bypass check to see if all of the SCEV assumptions we've
582 /// had to make are correct.
583 void emitSCEVChecks(Loop *L, BasicBlock *Bypass);
584 /// Emit bypass checks to check any memory assumptions we may have made.
585 void emitMemRuntimeChecks(Loop *L, BasicBlock *Bypass);
586
587 /// Add additional metadata to \p To that was not present on \p Orig.
588 ///
589 /// Currently this is used to add the noalias annotations based on the
590 /// inserted memchecks. Use this for instructions that are *cloned* into the
591 /// vector loop.
592 void addNewMetadata(Instruction *To, const Instruction *Orig);
593
594 /// Add metadata from one instruction to another.
595 ///
596 /// This includes both the original MDs from \p From and additional ones (\see
597 /// addNewMetadata). Use this for *newly created* instructions in the vector
598 /// loop.
599 void addMetadata(Instruction *To, Instruction *From);
600
601 /// \brief Similar to the previous function but it adds the metadata to a
602 /// vector of instructions.
603 void addMetadata(ArrayRef<Value *> To, Instruction *From);
604
605 /// \brief Set the debug location in the builder using the debug location in
606 /// the instruction.
607 void setDebugLocFromInst(IRBuilder<> &B, const Value *Ptr);
608
609 /// This is a helper class for maintaining vectorization state. It's used for
610 /// mapping values from the original loop to their corresponding values in
611 /// the new loop. Two mappings are maintained: one for vectorized values and
612 /// one for scalarized values. Vectorized values are represented with UF
613 /// vector values in the new loop, and scalarized values are represented with
614 /// UF x VF scalar values in the new loop. UF and VF are the unroll and
615 /// vectorization factors, respectively.
616 ///
617 /// Entries can be added to either map with setVectorValue and setScalarValue,
618 /// which assert that an entry was not already added before. If an entry is to
619 /// replace an existing one, call resetVectorValue. This is currently needed
620 /// to modify the mapped values during "fix-up" operations that occur once the
621 /// first phase of widening is complete. These operations include type
622 /// truncation and the second phase of recurrence widening.
623 ///
624 /// Entries from either map can be retrieved using the getVectorValue and
625 /// getScalarValue functions, which assert that the desired value exists.
626
627 struct ValueMap {
628
629 /// Construct an empty map with the given unroll and vectorization factors.
630 ValueMap(unsigned UF, unsigned VF) : UF(UF), VF(VF) {}
631
632 /// \return True if the map has any vector entry for \p Key.
633 bool hasAnyVectorValue(Value *Key) const {
634 return VectorMapStorage.count(Key);
635 }
636
637 /// \return True if the map has a vector entry for \p Key and \p Part.
638 bool hasVectorValue(Value *Key, unsigned Part) const {
639 assert(Part < UF && "Queried Vector Part is too large.")((Part < UF && "Queried Vector Part is too large."
) ? static_cast<void> (0) : __assert_fail ("Part < UF && \"Queried Vector Part is too large.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 639, __PRETTY_FUNCTION__))
;
640 if (!hasAnyVectorValue(Key))
641 return false;
642 const VectorParts &Entry = VectorMapStorage.find(Key)->second;
643 assert(Entry.size() == UF && "VectorParts has wrong dimensions.")((Entry.size() == UF && "VectorParts has wrong dimensions."
) ? static_cast<void> (0) : __assert_fail ("Entry.size() == UF && \"VectorParts has wrong dimensions.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 643, __PRETTY_FUNCTION__))
;
644 return Entry[Part] != nullptr;
645 }
646
647 /// \return True if the map has any scalar entry for \p Key.
648 bool hasAnyScalarValue(Value *Key) const {
649 return ScalarMapStorage.count(Key);
650 }
651
652 /// \return True if the map has a scalar entry for \p Key, \p Part and
653 /// \p Part.
654 bool hasScalarValue(Value *Key, unsigned Part, unsigned Lane) const {
655 assert(Part < UF && "Queried Scalar Part is too large.")((Part < UF && "Queried Scalar Part is too large."
) ? static_cast<void> (0) : __assert_fail ("Part < UF && \"Queried Scalar Part is too large.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 655, __PRETTY_FUNCTION__))
;
656 assert(Lane < VF && "Queried Scalar Lane is too large.")((Lane < VF && "Queried Scalar Lane is too large."
) ? static_cast<void> (0) : __assert_fail ("Lane < VF && \"Queried Scalar Lane is too large.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 656, __PRETTY_FUNCTION__))
;
657 if (!hasAnyScalarValue(Key))
658 return false;
659 const ScalarParts &Entry = ScalarMapStorage.find(Key)->second;
660 assert(Entry.size() == UF && "ScalarParts has wrong dimensions.")((Entry.size() == UF && "ScalarParts has wrong dimensions."
) ? static_cast<void> (0) : __assert_fail ("Entry.size() == UF && \"ScalarParts has wrong dimensions.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 660, __PRETTY_FUNCTION__))
;
661 assert(Entry[Part].size() == VF && "ScalarParts has wrong dimensions.")((Entry[Part].size() == VF && "ScalarParts has wrong dimensions."
) ? static_cast<void> (0) : __assert_fail ("Entry[Part].size() == VF && \"ScalarParts has wrong dimensions.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 661, __PRETTY_FUNCTION__))
;
662 return Entry[Part][Lane] != nullptr;
663 }
664
665 /// Retrieve the existing vector value that corresponds to \p Key and
666 /// \p Part.
667 Value *getVectorValue(Value *Key, unsigned Part) {
668 assert(hasVectorValue(Key, Part) && "Getting non-existent value.")((hasVectorValue(Key, Part) && "Getting non-existent value."
) ? static_cast<void> (0) : __assert_fail ("hasVectorValue(Key, Part) && \"Getting non-existent value.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 668, __PRETTY_FUNCTION__))
;
669 return VectorMapStorage[Key][Part];
670 }
671
672 /// Retrieve the existing scalar value that corresponds to \p Key, \p Part
673 /// and \p Lane.
674 Value *getScalarValue(Value *Key, unsigned Part, unsigned Lane) {
675 assert(hasScalarValue(Key, Part, Lane) && "Getting non-existent value.")((hasScalarValue(Key, Part, Lane) && "Getting non-existent value."
) ? static_cast<void> (0) : __assert_fail ("hasScalarValue(Key, Part, Lane) && \"Getting non-existent value.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 675, __PRETTY_FUNCTION__))
;
676 return ScalarMapStorage[Key][Part][Lane];
677 }
678
679 /// Set a vector value associated with \p Key and \p Part. Assumes such a
680 /// value is not already set. If it is, use resetVectorValue() instead.
681 void setVectorValue(Value *Key, unsigned Part, Value *Vector) {
682 assert(!hasVectorValue(Key, Part) && "Vector value already set for part")((!hasVectorValue(Key, Part) && "Vector value already set for part"
) ? static_cast<void> (0) : __assert_fail ("!hasVectorValue(Key, Part) && \"Vector value already set for part\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 682, __PRETTY_FUNCTION__))
;
683 if (!VectorMapStorage.count(Key)) {
684 VectorParts Entry(UF);
685 VectorMapStorage[Key] = Entry;
686 }
687 VectorMapStorage[Key][Part] = Vector;
688 }
689
690 /// Set a scalar value associated with \p Key for \p Part and \p Lane.
691 /// Assumes such a value is not already set.
692 void setScalarValue(Value *Key, unsigned Part, unsigned Lane,
693 Value *Scalar) {
694 assert(!hasScalarValue(Key, Part, Lane) && "Scalar value already set")((!hasScalarValue(Key, Part, Lane) && "Scalar value already set"
) ? static_cast<void> (0) : __assert_fail ("!hasScalarValue(Key, Part, Lane) && \"Scalar value already set\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 694, __PRETTY_FUNCTION__))
;
695 if (!ScalarMapStorage.count(Key)) {
696 ScalarParts Entry(UF);
697 for (unsigned Part = 0; Part < UF; ++Part)
698 Entry[Part].resize(VF, nullptr);
699 // TODO: Consider storing uniform values only per-part, as they occupy
700 // lane 0 only, keeping the other VF-1 redundant entries null.
701 ScalarMapStorage[Key] = Entry;
702 }
703 ScalarMapStorage[Key][Part][Lane] = Scalar;
704 }
705
706 /// Reset the vector value associated with \p Key for the given \p Part.
707 /// This function can be used to update values that have already been
708 /// vectorized. This is the case for "fix-up" operations including type
709 /// truncation and the second phase of recurrence vectorization.
710 void resetVectorValue(Value *Key, unsigned Part, Value *Vector) {
711 assert(hasVectorValue(Key, Part) && "Vector value not set for part")((hasVectorValue(Key, Part) && "Vector value not set for part"
) ? static_cast<void> (0) : __assert_fail ("hasVectorValue(Key, Part) && \"Vector value not set for part\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 711, __PRETTY_FUNCTION__))
;
712 VectorMapStorage[Key][Part] = Vector;
713 }
714
715 private:
716 /// The unroll factor. Each entry in the vector map contains UF vector
717 /// values.
718 unsigned UF;
719
720 /// The vectorization factor. Each entry in the scalar map contains UF x VF
721 /// scalar values.
722 unsigned VF;
723
724 /// The vector and scalar map storage. We use std::map and not DenseMap
725 /// because insertions to DenseMap invalidate its iterators.
726 std::map<Value *, VectorParts> VectorMapStorage;
727 std::map<Value *, ScalarParts> ScalarMapStorage;
728 };
729
730 /// The original loop.
731 Loop *OrigLoop;
732 /// A wrapper around ScalarEvolution used to add runtime SCEV checks. Applies
733 /// dynamic knowledge to simplify SCEV expressions and converts them to a
734 /// more usable form.
735 PredicatedScalarEvolution &PSE;
736 /// Loop Info.
737 LoopInfo *LI;
738 /// Dominator Tree.
739 DominatorTree *DT;
740 /// Alias Analysis.
741 AliasAnalysis *AA;
742 /// Target Library Info.
743 const TargetLibraryInfo *TLI;
744 /// Target Transform Info.
745 const TargetTransformInfo *TTI;
746 /// Assumption Cache.
747 AssumptionCache *AC;
748 /// Interface to emit optimization remarks.
749 OptimizationRemarkEmitter *ORE;
750
751 /// \brief LoopVersioning. It's only set up (non-null) if memchecks were
752 /// used.
753 ///
754 /// This is currently only used to add no-alias metadata based on the
755 /// memchecks. The actually versioning is performed manually.
756 std::unique_ptr<LoopVersioning> LVer;
757
758 /// The vectorization SIMD factor to use. Each vector will have this many
759 /// vector elements.
760 unsigned VF;
761
762protected:
763 /// The vectorization unroll factor to use. Each scalar is vectorized to this
764 /// many different vector instructions.
765 unsigned UF;
766
767 /// The builder that we use
768 IRBuilder<> Builder;
769
770 // --- Vectorization state ---
771
772 /// The vector-loop preheader.
773 BasicBlock *LoopVectorPreHeader;
774 /// The scalar-loop preheader.
775 BasicBlock *LoopScalarPreHeader;
776 /// Middle Block between the vector and the scalar.
777 BasicBlock *LoopMiddleBlock;
778 /// The ExitBlock of the scalar loop.
779 BasicBlock *LoopExitBlock;
780 /// The vector loop body.
781 BasicBlock *LoopVectorBody;
782 /// The scalar loop body.
783 BasicBlock *LoopScalarBody;
784 /// A list of all bypass blocks. The first block is the entry of the loop.
785 SmallVector<BasicBlock *, 4> LoopBypassBlocks;
786
787 /// The new Induction variable which was added to the new block.
788 PHINode *Induction;
789 /// The induction variable of the old basic block.
790 PHINode *OldInduction;
791
792 /// Maps values from the original loop to their corresponding values in the
793 /// vectorized loop. A key value can map to either vector values, scalar
794 /// values or both kinds of values, depending on whether the key was
795 /// vectorized and scalarized.
796 ValueMap VectorLoopValueMap;
797
798 /// Store instructions that should be predicated, as a pair
799 /// <StoreInst, Predicate>
800 SmallVector<std::pair<Instruction *, Value *>, 4> PredicatedInstructions;
801 EdgeMaskCacheTy EdgeMaskCache;
802 BlockMaskCacheTy BlockMaskCache;
803 /// Trip count of the original loop.
804 Value *TripCount;
805 /// Trip count of the widened loop (TripCount - TripCount % (VF*UF))
806 Value *VectorTripCount;
807
808 /// The legality analysis.
809 LoopVectorizationLegality *Legal;
810
811 /// The profitablity analysis.
812 LoopVectorizationCostModel *Cost;
813
814 // Record whether runtime checks are added.
815 bool AddedSafetyChecks;
816
817 // Holds the end values for each induction variable. We save the end values
818 // so we can later fix-up the external users of the induction variables.
819 DenseMap<PHINode *, Value *> IVEndValues;
820};
821
822class InnerLoopUnroller : public InnerLoopVectorizer {
823public:
824 InnerLoopUnroller(Loop *OrigLoop, PredicatedScalarEvolution &PSE,
825 LoopInfo *LI, DominatorTree *DT,
826 const TargetLibraryInfo *TLI,
827 const TargetTransformInfo *TTI, AssumptionCache *AC,
828 OptimizationRemarkEmitter *ORE, unsigned UnrollFactor,
829 LoopVectorizationLegality *LVL,
830 LoopVectorizationCostModel *CM)
831 : InnerLoopVectorizer(OrigLoop, PSE, LI, DT, TLI, TTI, AC, ORE, 1,
832 UnrollFactor, LVL, CM) {}
833
834private:
835 void vectorizeMemoryInstruction(Instruction *Instr) override;
836 Value *getBroadcastInstrs(Value *V) override;
837 Value *getStepVector(Value *Val, int StartIdx, Value *Step,
838 Instruction::BinaryOps Opcode =
839 Instruction::BinaryOpsEnd) override;
840 Value *reverseVector(Value *Vec) override;
841};
842
843/// \brief Look for a meaningful debug location on the instruction or it's
844/// operands.
845static Instruction *getDebugLocFromInstOrOperands(Instruction *I) {
846 if (!I)
847 return I;
848
849 DebugLoc Empty;
850 if (I->getDebugLoc() != Empty)
851 return I;
852
853 for (User::op_iterator OI = I->op_begin(), OE = I->op_end(); OI != OE; ++OI) {
854 if (Instruction *OpInst = dyn_cast<Instruction>(*OI))
855 if (OpInst->getDebugLoc() != Empty)
856 return OpInst;
857 }
858
859 return I;
860}
861
862void InnerLoopVectorizer::setDebugLocFromInst(IRBuilder<> &B, const Value *Ptr) {
863 if (const Instruction *Inst = dyn_cast_or_null<Instruction>(Ptr)) {
864 const DILocation *DIL = Inst->getDebugLoc();
865 if (DIL && Inst->getFunction()->isDebugInfoForProfiling())
866 B.SetCurrentDebugLocation(DIL->cloneWithDuplicationFactor(UF * VF));
867 else
868 B.SetCurrentDebugLocation(DIL);
869 } else
870 B.SetCurrentDebugLocation(DebugLoc());
871}
872
873#ifndef NDEBUG
874/// \return string containing a file name and a line # for the given loop.
875static std::string getDebugLocString(const Loop *L) {
876 std::string Result;
877 if (L) {
878 raw_string_ostream OS(Result);
879 if (const DebugLoc LoopDbgLoc = L->getStartLoc())
880 LoopDbgLoc.print(OS);
881 else
882 // Just print the module name.
883 OS << L->getHeader()->getParent()->getParent()->getModuleIdentifier();
884 OS.flush();
885 }
886 return Result;
887}
888#endif
889
890void InnerLoopVectorizer::addNewMetadata(Instruction *To,
891 const Instruction *Orig) {
892 // If the loop was versioned with memchecks, add the corresponding no-alias
893 // metadata.
894 if (LVer && (isa<LoadInst>(Orig) || isa<StoreInst>(Orig)))
895 LVer->annotateInstWithNoAlias(To, Orig);
896}
897
898void InnerLoopVectorizer::addMetadata(Instruction *To,
899 Instruction *From) {
900 propagateMetadata(To, From);
901 addNewMetadata(To, From);
902}
903
904void InnerLoopVectorizer::addMetadata(ArrayRef<Value *> To,
905 Instruction *From) {
906 for (Value *V : To) {
907 if (Instruction *I = dyn_cast<Instruction>(V))
908 addMetadata(I, From);
909 }
910}
911
912/// \brief The group of interleaved loads/stores sharing the same stride and
913/// close to each other.
914///
915/// Each member in this group has an index starting from 0, and the largest
916/// index should be less than interleaved factor, which is equal to the absolute
917/// value of the access's stride.
918///
919/// E.g. An interleaved load group of factor 4:
920/// for (unsigned i = 0; i < 1024; i+=4) {
921/// a = A[i]; // Member of index 0
922/// b = A[i+1]; // Member of index 1
923/// d = A[i+3]; // Member of index 3
924/// ...
925/// }
926///
927/// An interleaved store group of factor 4:
928/// for (unsigned i = 0; i < 1024; i+=4) {
929/// ...
930/// A[i] = a; // Member of index 0
931/// A[i+1] = b; // Member of index 1
932/// A[i+2] = c; // Member of index 2
933/// A[i+3] = d; // Member of index 3
934/// }
935///
936/// Note: the interleaved load group could have gaps (missing members), but
937/// the interleaved store group doesn't allow gaps.
938class InterleaveGroup {
939public:
940 InterleaveGroup(Instruction *Instr, int Stride, unsigned Align)
941 : Align(Align), SmallestKey(0), LargestKey(0), InsertPos(Instr) {
942 assert(Align && "The alignment should be non-zero")((Align && "The alignment should be non-zero") ? static_cast
<void> (0) : __assert_fail ("Align && \"The alignment should be non-zero\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 942, __PRETTY_FUNCTION__))
;
943
944 Factor = std::abs(Stride);
945 assert(Factor > 1 && "Invalid interleave factor")((Factor > 1 && "Invalid interleave factor") ? static_cast
<void> (0) : __assert_fail ("Factor > 1 && \"Invalid interleave factor\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 945, __PRETTY_FUNCTION__))
;
946
947 Reverse = Stride < 0;
948 Members[0] = Instr;
949 }
950
951 bool isReverse() const { return Reverse; }
952 unsigned getFactor() const { return Factor; }
953 unsigned getAlignment() const { return Align; }
954 unsigned getNumMembers() const { return Members.size(); }
955
956 /// \brief Try to insert a new member \p Instr with index \p Index and
957 /// alignment \p NewAlign. The index is related to the leader and it could be
958 /// negative if it is the new leader.
959 ///
960 /// \returns false if the instruction doesn't belong to the group.
961 bool insertMember(Instruction *Instr, int Index, unsigned NewAlign) {
962 assert(NewAlign && "The new member's alignment should be non-zero")((NewAlign && "The new member's alignment should be non-zero"
) ? static_cast<void> (0) : __assert_fail ("NewAlign && \"The new member's alignment should be non-zero\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 962, __PRETTY_FUNCTION__))
;
963
964 int Key = Index + SmallestKey;
965
966 // Skip if there is already a member with the same index.
967 if (Members.count(Key))
968 return false;
969
970 if (Key > LargestKey) {
971 // The largest index is always less than the interleave factor.
972 if (Index >= static_cast<int>(Factor))
973 return false;
974
975 LargestKey = Key;
976 } else if (Key < SmallestKey) {
977 // The largest index is always less than the interleave factor.
978 if (LargestKey - Key >= static_cast<int>(Factor))
979 return false;
980
981 SmallestKey = Key;
982 }
983
984 // It's always safe to select the minimum alignment.
985 Align = std::min(Align, NewAlign);
986 Members[Key] = Instr;
987 return true;
988 }
989
990 /// \brief Get the member with the given index \p Index
991 ///
992 /// \returns nullptr if contains no such member.
993 Instruction *getMember(unsigned Index) const {
994 int Key = SmallestKey + Index;
995 if (!Members.count(Key))
996 return nullptr;
997
998 return Members.find(Key)->second;
999 }
1000
1001 /// \brief Get the index for the given member. Unlike the key in the member
1002 /// map, the index starts from 0.
1003 unsigned getIndex(Instruction *Instr) const {
1004 for (auto I : Members)
1005 if (I.second == Instr)
1006 return I.first - SmallestKey;
1007
1008 llvm_unreachable("InterleaveGroup contains no such member")::llvm::llvm_unreachable_internal("InterleaveGroup contains no such member"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1008)
;
1009 }
1010
1011 Instruction *getInsertPos() const { return InsertPos; }
1012 void setInsertPos(Instruction *Inst) { InsertPos = Inst; }
1013
1014private:
1015 unsigned Factor; // Interleave Factor.
1016 bool Reverse;
1017 unsigned Align;
1018 DenseMap<int, Instruction *> Members;
1019 int SmallestKey;
1020 int LargestKey;
1021
1022 // To avoid breaking dependences, vectorized instructions of an interleave
1023 // group should be inserted at either the first load or the last store in
1024 // program order.
1025 //
1026 // E.g. %even = load i32 // Insert Position
1027 // %add = add i32 %even // Use of %even
1028 // %odd = load i32
1029 //
1030 // store i32 %even
1031 // %odd = add i32 // Def of %odd
1032 // store i32 %odd // Insert Position
1033 Instruction *InsertPos;
1034};
1035
1036/// \brief Drive the analysis of interleaved memory accesses in the loop.
1037///
1038/// Use this class to analyze interleaved accesses only when we can vectorize
1039/// a loop. Otherwise it's meaningless to do analysis as the vectorization
1040/// on interleaved accesses is unsafe.
1041///
1042/// The analysis collects interleave groups and records the relationships
1043/// between the member and the group in a map.
1044class InterleavedAccessInfo {
1045public:
1046 InterleavedAccessInfo(PredicatedScalarEvolution &PSE, Loop *L,
1047 DominatorTree *DT, LoopInfo *LI)
1048 : PSE(PSE), TheLoop(L), DT(DT), LI(LI), LAI(nullptr),
1049 RequiresScalarEpilogue(false) {}
1050
1051 ~InterleavedAccessInfo() {
1052 SmallSet<InterleaveGroup *, 4> DelSet;
1053 // Avoid releasing a pointer twice.
1054 for (auto &I : InterleaveGroupMap)
1055 DelSet.insert(I.second);
1056 for (auto *Ptr : DelSet)
1057 delete Ptr;
1058 }
1059
1060 /// \brief Analyze the interleaved accesses and collect them in interleave
1061 /// groups. Substitute symbolic strides using \p Strides.
1062 void analyzeInterleaving(const ValueToValueMap &Strides);
1063
1064 /// \brief Check if \p Instr belongs to any interleave group.
1065 bool isInterleaved(Instruction *Instr) const {
1066 return InterleaveGroupMap.count(Instr);
1067 }
1068
1069 /// \brief Return the maximum interleave factor of all interleaved groups.
1070 unsigned getMaxInterleaveFactor() const {
1071 unsigned MaxFactor = 1;
1072 for (auto &Entry : InterleaveGroupMap)
1073 MaxFactor = std::max(MaxFactor, Entry.second->getFactor());
1074 return MaxFactor;
1075 }
1076
1077 /// \brief Get the interleave group that \p Instr belongs to.
1078 ///
1079 /// \returns nullptr if doesn't have such group.
1080 InterleaveGroup *getInterleaveGroup(Instruction *Instr) const {
1081 if (InterleaveGroupMap.count(Instr))
1082 return InterleaveGroupMap.find(Instr)->second;
1083 return nullptr;
1084 }
1085
1086 /// \brief Returns true if an interleaved group that may access memory
1087 /// out-of-bounds requires a scalar epilogue iteration for correctness.
1088 bool requiresScalarEpilogue() const { return RequiresScalarEpilogue; }
1089
1090 /// \brief Initialize the LoopAccessInfo used for dependence checking.
1091 void setLAI(const LoopAccessInfo *Info) { LAI = Info; }
1092
1093private:
1094 /// A wrapper around ScalarEvolution, used to add runtime SCEV checks.
1095 /// Simplifies SCEV expressions in the context of existing SCEV assumptions.
1096 /// The interleaved access analysis can also add new predicates (for example
1097 /// by versioning strides of pointers).
1098 PredicatedScalarEvolution &PSE;
1099 Loop *TheLoop;
1100 DominatorTree *DT;
1101 LoopInfo *LI;
1102 const LoopAccessInfo *LAI;
1103
1104 /// True if the loop may contain non-reversed interleaved groups with
1105 /// out-of-bounds accesses. We ensure we don't speculatively access memory
1106 /// out-of-bounds by executing at least one scalar epilogue iteration.
1107 bool RequiresScalarEpilogue;
1108
1109 /// Holds the relationships between the members and the interleave group.
1110 DenseMap<Instruction *, InterleaveGroup *> InterleaveGroupMap;
1111
1112 /// Holds dependences among the memory accesses in the loop. It maps a source
1113 /// access to a set of dependent sink accesses.
1114 DenseMap<Instruction *, SmallPtrSet<Instruction *, 2>> Dependences;
1115
1116 /// \brief The descriptor for a strided memory access.
1117 struct StrideDescriptor {
1118 StrideDescriptor(int64_t Stride, const SCEV *Scev, uint64_t Size,
1119 unsigned Align)
1120 : Stride(Stride), Scev(Scev), Size(Size), Align(Align) {}
1121
1122 StrideDescriptor() = default;
1123
1124 // The access's stride. It is negative for a reverse access.
1125 int64_t Stride = 0;
1126 const SCEV *Scev = nullptr; // The scalar expression of this access
1127 uint64_t Size = 0; // The size of the memory object.
1128 unsigned Align = 0; // The alignment of this access.
1129 };
1130
1131 /// \brief A type for holding instructions and their stride descriptors.
1132 typedef std::pair<Instruction *, StrideDescriptor> StrideEntry;
1133
1134 /// \brief Create a new interleave group with the given instruction \p Instr,
1135 /// stride \p Stride and alignment \p Align.
1136 ///
1137 /// \returns the newly created interleave group.
1138 InterleaveGroup *createInterleaveGroup(Instruction *Instr, int Stride,
1139 unsigned Align) {
1140 assert(!InterleaveGroupMap.count(Instr) &&((!InterleaveGroupMap.count(Instr) && "Already in an interleaved access group"
) ? static_cast<void> (0) : __assert_fail ("!InterleaveGroupMap.count(Instr) && \"Already in an interleaved access group\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1141, __PRETTY_FUNCTION__))
1141 "Already in an interleaved access group")((!InterleaveGroupMap.count(Instr) && "Already in an interleaved access group"
) ? static_cast<void> (0) : __assert_fail ("!InterleaveGroupMap.count(Instr) && \"Already in an interleaved access group\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1141, __PRETTY_FUNCTION__))
;
1142 InterleaveGroupMap[Instr] = new InterleaveGroup(Instr, Stride, Align);
1143 return InterleaveGroupMap[Instr];
1144 }
1145
1146 /// \brief Release the group and remove all the relationships.
1147 void releaseGroup(InterleaveGroup *Group) {
1148 for (unsigned i = 0; i < Group->getFactor(); i++)
1149 if (Instruction *Member = Group->getMember(i))
1150 InterleaveGroupMap.erase(Member);
1151
1152 delete Group;
1153 }
1154
1155 /// \brief Collect all the accesses with a constant stride in program order.
1156 void collectConstStrideAccesses(
1157 MapVector<Instruction *, StrideDescriptor> &AccessStrideInfo,
1158 const ValueToValueMap &Strides);
1159
1160 /// \brief Returns true if \p Stride is allowed in an interleaved group.
1161 static bool isStrided(int Stride) {
1162 unsigned Factor = std::abs(Stride);
1163 return Factor >= 2 && Factor <= MaxInterleaveGroupFactor;
1164 }
1165
1166 /// \brief Returns true if \p BB is a predicated block.
1167 bool isPredicated(BasicBlock *BB) const {
1168 return LoopAccessInfo::blockNeedsPredication(BB, TheLoop, DT);
1169 }
1170
1171 /// \brief Returns true if LoopAccessInfo can be used for dependence queries.
1172 bool areDependencesValid() const {
1173 return LAI && LAI->getDepChecker().getDependences();
1174 }
1175
1176 /// \brief Returns true if memory accesses \p A and \p B can be reordered, if
1177 /// necessary, when constructing interleaved groups.
1178 ///
1179 /// \p A must precede \p B in program order. We return false if reordering is
1180 /// not necessary or is prevented because \p A and \p B may be dependent.
1181 bool canReorderMemAccessesForInterleavedGroups(StrideEntry *A,
1182 StrideEntry *B) const {
1183
1184 // Code motion for interleaved accesses can potentially hoist strided loads
1185 // and sink strided stores. The code below checks the legality of the
1186 // following two conditions:
1187 //
1188 // 1. Potentially moving a strided load (B) before any store (A) that
1189 // precedes B, or
1190 //
1191 // 2. Potentially moving a strided store (A) after any load or store (B)
1192 // that A precedes.
1193 //
1194 // It's legal to reorder A and B if we know there isn't a dependence from A
1195 // to B. Note that this determination is conservative since some
1196 // dependences could potentially be reordered safely.
1197
1198 // A is potentially the source of a dependence.
1199 auto *Src = A->first;
1200 auto SrcDes = A->second;
1201
1202 // B is potentially the sink of a dependence.
1203 auto *Sink = B->first;
1204 auto SinkDes = B->second;
1205
1206 // Code motion for interleaved accesses can't violate WAR dependences.
1207 // Thus, reordering is legal if the source isn't a write.
1208 if (!Src->mayWriteToMemory())
1209 return true;
1210
1211 // At least one of the accesses must be strided.
1212 if (!isStrided(SrcDes.Stride) && !isStrided(SinkDes.Stride))
1213 return true;
1214
1215 // If dependence information is not available from LoopAccessInfo,
1216 // conservatively assume the instructions can't be reordered.
1217 if (!areDependencesValid())
1218 return false;
1219
1220 // If we know there is a dependence from source to sink, assume the
1221 // instructions can't be reordered. Otherwise, reordering is legal.
1222 return !Dependences.count(Src) || !Dependences.lookup(Src).count(Sink);
1223 }
1224
1225 /// \brief Collect the dependences from LoopAccessInfo.
1226 ///
1227 /// We process the dependences once during the interleaved access analysis to
1228 /// enable constant-time dependence queries.
1229 void collectDependences() {
1230 if (!areDependencesValid())
1231 return;
1232 auto *Deps = LAI->getDepChecker().getDependences();
1233 for (auto Dep : *Deps)
1234 Dependences[Dep.getSource(*LAI)].insert(Dep.getDestination(*LAI));
1235 }
1236};
1237
1238/// Utility class for getting and setting loop vectorizer hints in the form
1239/// of loop metadata.
1240/// This class keeps a number of loop annotations locally (as member variables)
1241/// and can, upon request, write them back as metadata on the loop. It will
1242/// initially scan the loop for existing metadata, and will update the local
1243/// values based on information in the loop.
1244/// We cannot write all values to metadata, as the mere presence of some info,
1245/// for example 'force', means a decision has been made. So, we need to be
1246/// careful NOT to add them if the user hasn't specifically asked so.
1247class LoopVectorizeHints {
1248 enum HintKind { HK_WIDTH, HK_UNROLL, HK_FORCE };
1249
1250 /// Hint - associates name and validation with the hint value.
1251 struct Hint {
1252 const char *Name;
1253 unsigned Value; // This may have to change for non-numeric values.
1254 HintKind Kind;
1255
1256 Hint(const char *Name, unsigned Value, HintKind Kind)
1257 : Name(Name), Value(Value), Kind(Kind) {}
1258
1259 bool validate(unsigned Val) {
1260 switch (Kind) {
1261 case HK_WIDTH:
1262 return isPowerOf2_32(Val) && Val <= VectorizerParams::MaxVectorWidth;
1263 case HK_UNROLL:
1264 return isPowerOf2_32(Val) && Val <= MaxInterleaveFactor;
1265 case HK_FORCE:
1266 return (Val <= 1);
1267 }
1268 return false;
1269 }
1270 };
1271
1272 /// Vectorization width.
1273 Hint Width;
1274 /// Vectorization interleave factor.
1275 Hint Interleave;
1276 /// Vectorization forced
1277 Hint Force;
1278
1279 /// Return the loop metadata prefix.
1280 static StringRef Prefix() { return "llvm.loop."; }
1281
1282 /// True if there is any unsafe math in the loop.
1283 bool PotentiallyUnsafe;
1284
1285public:
1286 enum ForceKind {
1287 FK_Undefined = -1, ///< Not selected.
1288 FK_Disabled = 0, ///< Forcing disabled.
1289 FK_Enabled = 1, ///< Forcing enabled.
1290 };
1291
1292 LoopVectorizeHints(const Loop *L, bool DisableInterleaving,
1293 OptimizationRemarkEmitter &ORE)
1294 : Width("vectorize.width", VectorizerParams::VectorizationFactor,
1295 HK_WIDTH),
1296 Interleave("interleave.count", DisableInterleaving, HK_UNROLL),
1297 Force("vectorize.enable", FK_Undefined, HK_FORCE),
1298 PotentiallyUnsafe(false), TheLoop(L), ORE(ORE) {
1299 // Populate values with existing loop metadata.
1300 getHintsFromMetadata();
1301
1302 // force-vector-interleave overrides DisableInterleaving.
1303 if (VectorizerParams::isInterleaveForced())
1304 Interleave.Value = VectorizerParams::VectorizationInterleave;
1305
1306 DEBUG(if (DisableInterleaving && Interleave.Value == 1) dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { if (DisableInterleaving && Interleave
.Value == 1) dbgs() << "LV: Interleaving disabled by the pass manager\n"
; } } while (false)
1307 << "LV: Interleaving disabled by the pass manager\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { if (DisableInterleaving && Interleave
.Value == 1) dbgs() << "LV: Interleaving disabled by the pass manager\n"
; } } while (false)
;
1308 }
1309
1310 /// Mark the loop L as already vectorized by setting the width to 1.
1311 void setAlreadyVectorized() {
1312 Width.Value = Interleave.Value = 1;
1313 Hint Hints[] = {Width, Interleave};
1314 writeHintsToMetadata(Hints);
1315 }
1316
1317 bool allowVectorization(Function *F, Loop *L, bool AlwaysVectorize) const {
1318 if (getForce() == LoopVectorizeHints::FK_Disabled) {
1319 DEBUG(dbgs() << "LV: Not vectorizing: #pragma vectorize disable.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not vectorizing: #pragma vectorize disable.\n"
; } } while (false)
;
1320 emitRemarkWithHints();
1321 return false;
1322 }
1323
1324 if (!AlwaysVectorize && getForce() != LoopVectorizeHints::FK_Enabled) {
1325 DEBUG(dbgs() << "LV: Not vectorizing: No #pragma vectorize enable.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not vectorizing: No #pragma vectorize enable.\n"
; } } while (false)
;
1326 emitRemarkWithHints();
1327 return false;
1328 }
1329
1330 if (getWidth() == 1 && getInterleave() == 1) {
1331 // FIXME: Add a separate metadata to indicate when the loop has already
1332 // been vectorized instead of setting width and count to 1.
1333 DEBUG(dbgs() << "LV: Not vectorizing: Disabled/already vectorized.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not vectorizing: Disabled/already vectorized.\n"
; } } while (false)
;
1334 // FIXME: Add interleave.disable metadata. This will allow
1335 // vectorize.disable to be used without disabling the pass and errors
1336 // to differentiate between disabled vectorization and a width of 1.
1337 ORE.emit(OptimizationRemarkAnalysis(vectorizeAnalysisPassName(),
1338 "AllDisabled", L->getStartLoc(),
1339 L->getHeader())
1340 << "loop not vectorized: vectorization and interleaving are "
1341 "explicitly disabled, or vectorize width and interleave "
1342 "count are both set to 1");
1343 return false;
1344 }
1345
1346 return true;
1347 }
1348
1349 /// Dumps all the hint information.
1350 void emitRemarkWithHints() const {
1351 using namespace ore;
1352 if (Force.Value == LoopVectorizeHints::FK_Disabled)
1353 ORE.emit(OptimizationRemarkMissed(LV_NAME"loop-vectorize", "MissedExplicitlyDisabled",
1354 TheLoop->getStartLoc(),
1355 TheLoop->getHeader())
1356 << "loop not vectorized: vectorization is explicitly disabled");
1357 else {
1358 OptimizationRemarkMissed R(LV_NAME"loop-vectorize", "MissedDetails",
1359 TheLoop->getStartLoc(), TheLoop->getHeader());
1360 R << "loop not vectorized";
1361 if (Force.Value == LoopVectorizeHints::FK_Enabled) {
1362 R << " (Force=" << NV("Force", true);
1363 if (Width.Value != 0)
1364 R << ", Vector Width=" << NV("VectorWidth", Width.Value);
1365 if (Interleave.Value != 0)
1366 R << ", Interleave Count=" << NV("InterleaveCount", Interleave.Value);
1367 R << ")";
1368 }
1369 ORE.emit(R);
1370 }
1371 }
1372
1373 unsigned getWidth() const { return Width.Value; }
1374 unsigned getInterleave() const { return Interleave.Value; }
1375 enum ForceKind getForce() const { return (ForceKind)Force.Value; }
1376
1377 /// \brief If hints are provided that force vectorization, use the AlwaysPrint
1378 /// pass name to force the frontend to print the diagnostic.
1379 const char *vectorizeAnalysisPassName() const {
1380 if (getWidth() == 1)
1381 return LV_NAME"loop-vectorize";
1382 if (getForce() == LoopVectorizeHints::FK_Disabled)
1383 return LV_NAME"loop-vectorize";
1384 if (getForce() == LoopVectorizeHints::FK_Undefined && getWidth() == 0)
1385 return LV_NAME"loop-vectorize";
1386 return OptimizationRemarkAnalysis::AlwaysPrint;
1387 }
1388
1389 bool allowReordering() const {
1390 // When enabling loop hints are provided we allow the vectorizer to change
1391 // the order of operations that is given by the scalar loop. This is not
1392 // enabled by default because can be unsafe or inefficient. For example,
1393 // reordering floating-point operations will change the way round-off
1394 // error accumulates in the loop.
1395 return getForce() == LoopVectorizeHints::FK_Enabled || getWidth() > 1;
1396 }
1397
1398 bool isPotentiallyUnsafe() const {
1399 // Avoid FP vectorization if the target is unsure about proper support.
1400 // This may be related to the SIMD unit in the target not handling
1401 // IEEE 754 FP ops properly, or bad single-to-double promotions.
1402 // Otherwise, a sequence of vectorized loops, even without reduction,
1403 // could lead to different end results on the destination vectors.
1404 return getForce() != LoopVectorizeHints::FK_Enabled && PotentiallyUnsafe;
1405 }
1406
1407 void setPotentiallyUnsafe() { PotentiallyUnsafe = true; }
1408
1409private:
1410 /// Find hints specified in the loop metadata and update local values.
1411 void getHintsFromMetadata() {
1412 MDNode *LoopID = TheLoop->getLoopID();
1413 if (!LoopID)
1414 return;
1415
1416 // First operand should refer to the loop id itself.
1417 assert(LoopID->getNumOperands() > 0 && "requires at least one operand")((LoopID->getNumOperands() > 0 && "requires at least one operand"
) ? static_cast<void> (0) : __assert_fail ("LoopID->getNumOperands() > 0 && \"requires at least one operand\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1417, __PRETTY_FUNCTION__))
;
1418 assert(LoopID->getOperand(0) == LoopID && "invalid loop id")((LoopID->getOperand(0) == LoopID && "invalid loop id"
) ? static_cast<void> (0) : __assert_fail ("LoopID->getOperand(0) == LoopID && \"invalid loop id\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1418, __PRETTY_FUNCTION__))
;
1419
1420 for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
1421 const MDString *S = nullptr;
1422 SmallVector<Metadata *, 4> Args;
1423
1424 // The expected hint is either a MDString or a MDNode with the first
1425 // operand a MDString.
1426 if (const MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i))) {
1427 if (!MD || MD->getNumOperands() == 0)
1428 continue;
1429 S = dyn_cast<MDString>(MD->getOperand(0));
1430 for (unsigned i = 1, ie = MD->getNumOperands(); i < ie; ++i)
1431 Args.push_back(MD->getOperand(i));
1432 } else {
1433 S = dyn_cast<MDString>(LoopID->getOperand(i));
1434 assert(Args.size() == 0 && "too many arguments for MDString")((Args.size() == 0 && "too many arguments for MDString"
) ? static_cast<void> (0) : __assert_fail ("Args.size() == 0 && \"too many arguments for MDString\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1434, __PRETTY_FUNCTION__))
;
1435 }
1436
1437 if (!S)
1438 continue;
1439
1440 // Check if the hint starts with the loop metadata prefix.
1441 StringRef Name = S->getString();
1442 if (Args.size() == 1)
1443 setHint(Name, Args[0]);
1444 }
1445 }
1446
1447 /// Checks string hint with one operand and set value if valid.
1448 void setHint(StringRef Name, Metadata *Arg) {
1449 if (!Name.startswith(Prefix()))
1450 return;
1451 Name = Name.substr(Prefix().size(), StringRef::npos);
1452
1453 const ConstantInt *C = mdconst::dyn_extract<ConstantInt>(Arg);
1454 if (!C)
1455 return;
1456 unsigned Val = C->getZExtValue();
1457
1458 Hint *Hints[] = {&Width, &Interleave, &Force};
1459 for (auto H : Hints) {
1460 if (Name == H->Name) {
1461 if (H->validate(Val))
1462 H->Value = Val;
1463 else
1464 DEBUG(dbgs() << "LV: ignoring invalid hint '" << Name << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: ignoring invalid hint '"
<< Name << "'\n"; } } while (false)
;
1465 break;
1466 }
1467 }
1468 }
1469
1470 /// Create a new hint from name / value pair.
1471 MDNode *createHintMetadata(StringRef Name, unsigned V) const {
1472 LLVMContext &Context = TheLoop->getHeader()->getContext();
1473 Metadata *MDs[] = {MDString::get(Context, Name),
1474 ConstantAsMetadata::get(
1475 ConstantInt::get(Type::getInt32Ty(Context), V))};
1476 return MDNode::get(Context, MDs);
1477 }
1478
1479 /// Matches metadata with hint name.
1480 bool matchesHintMetadataName(MDNode *Node, ArrayRef<Hint> HintTypes) {
1481 MDString *Name = dyn_cast<MDString>(Node->getOperand(0));
1482 if (!Name)
1483 return false;
1484
1485 for (auto H : HintTypes)
1486 if (Name->getString().endswith(H.Name))
1487 return true;
1488 return false;
1489 }
1490
1491 /// Sets current hints into loop metadata, keeping other values intact.
1492 void writeHintsToMetadata(ArrayRef<Hint> HintTypes) {
1493 if (HintTypes.size() == 0)
1494 return;
1495
1496 // Reserve the first element to LoopID (see below).
1497 SmallVector<Metadata *, 4> MDs(1);
1498 // If the loop already has metadata, then ignore the existing operands.
1499 MDNode *LoopID = TheLoop->getLoopID();
1500 if (LoopID) {
1501 for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
1502 MDNode *Node = cast<MDNode>(LoopID->getOperand(i));
1503 // If node in update list, ignore old value.
1504 if (!matchesHintMetadataName(Node, HintTypes))
1505 MDs.push_back(Node);
1506 }
1507 }
1508
1509 // Now, add the missing hints.
1510 for (auto H : HintTypes)
1511 MDs.push_back(createHintMetadata(Twine(Prefix(), H.Name).str(), H.Value));
1512
1513 // Replace current metadata node with new one.
1514 LLVMContext &Context = TheLoop->getHeader()->getContext();
1515 MDNode *NewLoopID = MDNode::get(Context, MDs);
1516 // Set operand 0 to refer to the loop id itself.
1517 NewLoopID->replaceOperandWith(0, NewLoopID);
1518
1519 TheLoop->setLoopID(NewLoopID);
1520 }
1521
1522 /// The loop these hints belong to.
1523 const Loop *TheLoop;
1524
1525 /// Interface to emit optimization remarks.
1526 OptimizationRemarkEmitter &ORE;
1527};
1528
1529static void emitMissedWarning(Function *F, Loop *L,
1530 const LoopVectorizeHints &LH,
1531 OptimizationRemarkEmitter *ORE) {
1532 LH.emitRemarkWithHints();
1533
1534 if (LH.getForce() == LoopVectorizeHints::FK_Enabled) {
1535 if (LH.getWidth() != 1)
1536 ORE->emit(DiagnosticInfoOptimizationFailure(
1537 DEBUG_TYPE"loop-vectorize", "FailedRequestedVectorization",
1538 L->getStartLoc(), L->getHeader())
1539 << "loop not vectorized: "
1540 << "failed explicitly specified loop vectorization");
1541 else if (LH.getInterleave() != 1)
1542 ORE->emit(DiagnosticInfoOptimizationFailure(
1543 DEBUG_TYPE"loop-vectorize", "FailedRequestedInterleaving", L->getStartLoc(),
1544 L->getHeader())
1545 << "loop not interleaved: "
1546 << "failed explicitly specified loop interleaving");
1547 }
1548}
1549
1550/// LoopVectorizationLegality checks if it is legal to vectorize a loop, and
1551/// to what vectorization factor.
1552/// This class does not look at the profitability of vectorization, only the
1553/// legality. This class has two main kinds of checks:
1554/// * Memory checks - The code in canVectorizeMemory checks if vectorization
1555/// will change the order of memory accesses in a way that will change the
1556/// correctness of the program.
1557/// * Scalars checks - The code in canVectorizeInstrs and canVectorizeMemory
1558/// checks for a number of different conditions, such as the availability of a
1559/// single induction variable, that all types are supported and vectorize-able,
1560/// etc. This code reflects the capabilities of InnerLoopVectorizer.
1561/// This class is also used by InnerLoopVectorizer for identifying
1562/// induction variable and the different reduction variables.
1563class LoopVectorizationLegality {
1564public:
1565 LoopVectorizationLegality(
1566 Loop *L, PredicatedScalarEvolution &PSE, DominatorTree *DT,
1567 TargetLibraryInfo *TLI, AliasAnalysis *AA, Function *F,
1568 const TargetTransformInfo *TTI,
1569 std::function<const LoopAccessInfo &(Loop &)> *GetLAA, LoopInfo *LI,
1570 OptimizationRemarkEmitter *ORE, LoopVectorizationRequirements *R,
1571 LoopVectorizeHints *H)
1572 : NumPredStores(0), TheLoop(L), PSE(PSE), TLI(TLI), TTI(TTI), DT(DT),
1573 GetLAA(GetLAA), LAI(nullptr), ORE(ORE), InterleaveInfo(PSE, L, DT, LI),
1574 PrimaryInduction(nullptr), WidestIndTy(nullptr), HasFunNoNaNAttr(false),
1575 Requirements(R), Hints(H) {}
1576
1577 /// ReductionList contains the reduction descriptors for all
1578 /// of the reductions that were found in the loop.
1579 typedef DenseMap<PHINode *, RecurrenceDescriptor> ReductionList;
1580
1581 /// InductionList saves induction variables and maps them to the
1582 /// induction descriptor.
1583 typedef MapVector<PHINode *, InductionDescriptor> InductionList;
1584
1585 /// RecurrenceSet contains the phi nodes that are recurrences other than
1586 /// inductions and reductions.
1587 typedef SmallPtrSet<const PHINode *, 8> RecurrenceSet;
1588
1589 /// Returns true if it is legal to vectorize this loop.
1590 /// This does not mean that it is profitable to vectorize this
1591 /// loop, only that it is legal to do so.
1592 bool canVectorize();
1593
1594 /// Returns the primary induction variable.
1595 PHINode *getPrimaryInduction() { return PrimaryInduction; }
1596
1597 /// Returns the reduction variables found in the loop.
1598 ReductionList *getReductionVars() { return &Reductions; }
1599
1600 /// Returns the induction variables found in the loop.
1601 InductionList *getInductionVars() { return &Inductions; }
1602
1603 /// Return the first-order recurrences found in the loop.
1604 RecurrenceSet *getFirstOrderRecurrences() { return &FirstOrderRecurrences; }
1605
1606 /// Returns the widest induction type.
1607 Type *getWidestInductionType() { return WidestIndTy; }
1608
1609 /// Returns True if V is an induction variable in this loop.
1610 bool isInductionVariable(const Value *V);
1611
1612 /// Returns True if PN is a reduction variable in this loop.
1613 bool isReductionVariable(PHINode *PN) { return Reductions.count(PN); }
1614
1615 /// Returns True if Phi is a first-order recurrence in this loop.
1616 bool isFirstOrderRecurrence(const PHINode *Phi);
1617
1618 /// Return true if the block BB needs to be predicated in order for the loop
1619 /// to be vectorized.
1620 bool blockNeedsPredication(BasicBlock *BB);
1621
1622 /// Check if this pointer is consecutive when vectorizing. This happens
1623 /// when the last index of the GEP is the induction variable, or that the
1624 /// pointer itself is an induction variable.
1625 /// This check allows us to vectorize A[idx] into a wide load/store.
1626 /// Returns:
1627 /// 0 - Stride is unknown or non-consecutive.
1628 /// 1 - Address is consecutive.
1629 /// -1 - Address is consecutive, and decreasing.
1630 int isConsecutivePtr(Value *Ptr);
1631
1632 /// Returns true if the value V is uniform within the loop.
1633 bool isUniform(Value *V);
1634
1635 /// Returns the information that we collected about runtime memory check.
1636 const RuntimePointerChecking *getRuntimePointerChecking() const {
1637 return LAI->getRuntimePointerChecking();
1638 }
1639
1640 const LoopAccessInfo *getLAI() const { return LAI; }
1641
1642 /// \brief Check if \p Instr belongs to any interleaved access group.
1643 bool isAccessInterleaved(Instruction *Instr) {
1644 return InterleaveInfo.isInterleaved(Instr);
1645 }
1646
1647 /// \brief Return the maximum interleave factor of all interleaved groups.
1648 unsigned getMaxInterleaveFactor() const {
1649 return InterleaveInfo.getMaxInterleaveFactor();
1650 }
1651
1652 /// \brief Get the interleaved access group that \p Instr belongs to.
1653 const InterleaveGroup *getInterleavedAccessGroup(Instruction *Instr) {
1654 return InterleaveInfo.getInterleaveGroup(Instr);
1655 }
1656
1657 /// \brief Returns true if an interleaved group requires a scalar iteration
1658 /// to handle accesses with gaps.
1659 bool requiresScalarEpilogue() const {
1660 return InterleaveInfo.requiresScalarEpilogue();
1661 }
1662
1663 unsigned getMaxSafeDepDistBytes() { return LAI->getMaxSafeDepDistBytes(); }
1664
1665 bool hasStride(Value *V) { return LAI->hasStride(V); }
1666
1667 /// Returns true if the target machine supports masked store operation
1668 /// for the given \p DataType and kind of access to \p Ptr.
1669 bool isLegalMaskedStore(Type *DataType, Value *Ptr) {
1670 return isConsecutivePtr(Ptr) && TTI->isLegalMaskedStore(DataType);
1671 }
1672 /// Returns true if the target machine supports masked load operation
1673 /// for the given \p DataType and kind of access to \p Ptr.
1674 bool isLegalMaskedLoad(Type *DataType, Value *Ptr) {
1675 return isConsecutivePtr(Ptr) && TTI->isLegalMaskedLoad(DataType);
1676 }
1677 /// Returns true if the target machine supports masked scatter operation
1678 /// for the given \p DataType.
1679 bool isLegalMaskedScatter(Type *DataType) {
1680 return TTI->isLegalMaskedScatter(DataType);
1681 }
1682 /// Returns true if the target machine supports masked gather operation
1683 /// for the given \p DataType.
1684 bool isLegalMaskedGather(Type *DataType) {
1685 return TTI->isLegalMaskedGather(DataType);
1686 }
1687 /// Returns true if the target machine can represent \p V as a masked gather
1688 /// or scatter operation.
1689 bool isLegalGatherOrScatter(Value *V) {
1690 auto *LI = dyn_cast<LoadInst>(V);
1691 auto *SI = dyn_cast<StoreInst>(V);
1692 if (!LI && !SI)
1693 return false;
1694 auto *Ptr = getPointerOperand(V);
1695 auto *Ty = cast<PointerType>(Ptr->getType())->getElementType();
1696 return (LI && isLegalMaskedGather(Ty)) || (SI && isLegalMaskedScatter(Ty));
1697 }
1698
1699 /// Returns true if vector representation of the instruction \p I
1700 /// requires mask.
1701 bool isMaskRequired(const Instruction *I) { return (MaskedOp.count(I) != 0); }
1702 unsigned getNumStores() const { return LAI->getNumStores(); }
1703 unsigned getNumLoads() const { return LAI->getNumLoads(); }
1704 unsigned getNumPredStores() const { return NumPredStores; }
1705
1706 /// Returns true if \p I is an instruction that will be scalarized with
1707 /// predication. Such instructions include conditional stores and
1708 /// instructions that may divide by zero.
1709 bool isScalarWithPredication(Instruction *I);
1710
1711 /// Returns true if \p I is a memory instruction with consecutive memory
1712 /// access that can be widened.
1713 bool memoryInstructionCanBeWidened(Instruction *I, unsigned VF = 1);
1714
1715 // Returns true if the NoNaN attribute is set on the function.
1716 bool hasFunNoNaNAttr() const { return HasFunNoNaNAttr; }
1717
1718private:
1719 /// Check if a single basic block loop is vectorizable.
1720 /// At this point we know that this is a loop with a constant trip count
1721 /// and we only need to check individual instructions.
1722 bool canVectorizeInstrs();
1723
1724 /// When we vectorize loops we may change the order in which
1725 /// we read and write from memory. This method checks if it is
1726 /// legal to vectorize the code, considering only memory constrains.
1727 /// Returns true if the loop is vectorizable
1728 bool canVectorizeMemory();
1729
1730 /// Return true if we can vectorize this loop using the IF-conversion
1731 /// transformation.
1732 bool canVectorizeWithIfConvert();
1733
1734 /// Return true if all of the instructions in the block can be speculatively
1735 /// executed. \p SafePtrs is a list of addresses that are known to be legal
1736 /// and we know that we can read from them without segfault.
1737 bool blockCanBePredicated(BasicBlock *BB, SmallPtrSetImpl<Value *> &SafePtrs);
1738
1739 /// Updates the vectorization state by adding \p Phi to the inductions list.
1740 /// This can set \p Phi as the main induction of the loop if \p Phi is a
1741 /// better choice for the main induction than the existing one.
1742 void addInductionPhi(PHINode *Phi, const InductionDescriptor &ID,
1743 SmallPtrSetImpl<Value *> &AllowedExit);
1744
1745 /// Create an analysis remark that explains why vectorization failed
1746 ///
1747 /// \p RemarkName is the identifier for the remark. If \p I is passed it is
1748 /// an instruction that prevents vectorization. Otherwise the loop is used
1749 /// for the location of the remark. \return the remark object that can be
1750 /// streamed to.
1751 OptimizationRemarkAnalysis
1752 createMissedAnalysis(StringRef RemarkName, Instruction *I = nullptr) const {
1753 return ::createMissedAnalysis(Hints->vectorizeAnalysisPassName(),
1754 RemarkName, TheLoop, I);
1755 }
1756
1757 /// \brief If an access has a symbolic strides, this maps the pointer value to
1758 /// the stride symbol.
1759 const ValueToValueMap *getSymbolicStrides() {
1760 // FIXME: Currently, the set of symbolic strides is sometimes queried before
1761 // it's collected. This happens from canVectorizeWithIfConvert, when the
1762 // pointer is checked to reference consecutive elements suitable for a
1763 // masked access.
1764 return LAI ? &LAI->getSymbolicStrides() : nullptr;
1765 }
1766
1767 unsigned NumPredStores;
1768
1769 /// The loop that we evaluate.
1770 Loop *TheLoop;
1771 /// A wrapper around ScalarEvolution used to add runtime SCEV checks.
1772 /// Applies dynamic knowledge to simplify SCEV expressions in the context
1773 /// of existing SCEV assumptions. The analysis will also add a minimal set
1774 /// of new predicates if this is required to enable vectorization and
1775 /// unrolling.
1776 PredicatedScalarEvolution &PSE;
1777 /// Target Library Info.
1778 TargetLibraryInfo *TLI;
1779 /// Target Transform Info
1780 const TargetTransformInfo *TTI;
1781 /// Dominator Tree.
1782 DominatorTree *DT;
1783 // LoopAccess analysis.
1784 std::function<const LoopAccessInfo &(Loop &)> *GetLAA;
1785 // And the loop-accesses info corresponding to this loop. This pointer is
1786 // null until canVectorizeMemory sets it up.
1787 const LoopAccessInfo *LAI;
1788 /// Interface to emit optimization remarks.
1789 OptimizationRemarkEmitter *ORE;
1790
1791 /// The interleave access information contains groups of interleaved accesses
1792 /// with the same stride and close to each other.
1793 InterleavedAccessInfo InterleaveInfo;
1794
1795 // --- vectorization state --- //
1796
1797 /// Holds the primary induction variable. This is the counter of the
1798 /// loop.
1799 PHINode *PrimaryInduction;
1800 /// Holds the reduction variables.
1801 ReductionList Reductions;
1802 /// Holds all of the induction variables that we found in the loop.
1803 /// Notice that inductions don't need to start at zero and that induction
1804 /// variables can be pointers.
1805 InductionList Inductions;
1806 /// Holds the phi nodes that are first-order recurrences.
1807 RecurrenceSet FirstOrderRecurrences;
1808 /// Holds the widest induction type encountered.
1809 Type *WidestIndTy;
1810
1811 /// Allowed outside users. This holds the induction and reduction
1812 /// vars which can be accessed from outside the loop.
1813 SmallPtrSet<Value *, 4> AllowedExit;
1814
1815 /// Can we assume the absence of NaNs.
1816 bool HasFunNoNaNAttr;
1817
1818 /// Vectorization requirements that will go through late-evaluation.
1819 LoopVectorizationRequirements *Requirements;
1820
1821 /// Used to emit an analysis of any legality issues.
1822 LoopVectorizeHints *Hints;
1823
1824 /// While vectorizing these instructions we have to generate a
1825 /// call to the appropriate masked intrinsic
1826 SmallPtrSet<const Instruction *, 8> MaskedOp;
1827};
1828
1829/// LoopVectorizationCostModel - estimates the expected speedups due to
1830/// vectorization.
1831/// In many cases vectorization is not profitable. This can happen because of
1832/// a number of reasons. In this class we mainly attempt to predict the
1833/// expected speedup/slowdowns due to the supported instruction set. We use the
1834/// TargetTransformInfo to query the different backends for the cost of
1835/// different operations.
1836class LoopVectorizationCostModel {
1837public:
1838 LoopVectorizationCostModel(Loop *L, PredicatedScalarEvolution &PSE,
1839 LoopInfo *LI, LoopVectorizationLegality *Legal,
1840 const TargetTransformInfo &TTI,
1841 const TargetLibraryInfo *TLI, DemandedBits *DB,
1842 AssumptionCache *AC,
1843 OptimizationRemarkEmitter *ORE, const Function *F,
1844 const LoopVectorizeHints *Hints)
1845 : TheLoop(L), PSE(PSE), LI(LI), Legal(Legal), TTI(TTI), TLI(TLI), DB(DB),
1846 AC(AC), ORE(ORE), TheFunction(F), Hints(Hints) {}
1847
1848 /// \return An upper bound for the vectorization factor, or None if
1849 /// vectorization should be avoided up front.
1850 Optional<unsigned> computeMaxVF(bool OptForSize);
1851
1852 /// Information about vectorization costs
1853 struct VectorizationFactor {
1854 unsigned Width; // Vector width with best cost
1855 unsigned Cost; // Cost of the loop with that width
1856 };
1857 /// \return The most profitable vectorization factor and the cost of that VF.
1858 /// This method checks every power of two up to MaxVF. If UserVF is not ZERO
1859 /// then this vectorization factor will be selected if vectorization is
1860 /// possible.
1861 VectorizationFactor selectVectorizationFactor(unsigned MaxVF);
1862
1863 /// Setup cost-based decisions for user vectorization factor.
1864 void selectUserVectorizationFactor(unsigned UserVF) {
1865 collectUniformsAndScalars(UserVF);
1866 collectInstsToScalarize(UserVF);
1867 }
1868
1869 /// \return The size (in bits) of the smallest and widest types in the code
1870 /// that needs to be vectorized. We ignore values that remain scalar such as
1871 /// 64 bit loop indices.
1872 std::pair<unsigned, unsigned> getSmallestAndWidestTypes();
1873
1874 /// \return The desired interleave count.
1875 /// If interleave count has been specified by metadata it will be returned.
1876 /// Otherwise, the interleave count is computed and returned. VF and LoopCost
1877 /// are the selected vectorization factor and the cost of the selected VF.
1878 unsigned selectInterleaveCount(bool OptForSize, unsigned VF,
1879 unsigned LoopCost);
1880
1881 /// Memory access instruction may be vectorized in more than one way.
1882 /// Form of instruction after vectorization depends on cost.
1883 /// This function takes cost-based decisions for Load/Store instructions
1884 /// and collects them in a map. This decisions map is used for building
1885 /// the lists of loop-uniform and loop-scalar instructions.
1886 /// The calculated cost is saved with widening decision in order to
1887 /// avoid redundant calculations.
1888 void setCostBasedWideningDecision(unsigned VF);
1889
1890 /// \brief A struct that represents some properties of the register usage
1891 /// of a loop.
1892 struct RegisterUsage {
1893 /// Holds the number of loop invariant values that are used in the loop.
1894 unsigned LoopInvariantRegs;
1895 /// Holds the maximum number of concurrent live intervals in the loop.
1896 unsigned MaxLocalUsers;
1897 /// Holds the number of instructions in the loop.
1898 unsigned NumInstructions;
1899 };
1900
1901 /// \return Returns information about the register usages of the loop for the
1902 /// given vectorization factors.
1903 SmallVector<RegisterUsage, 8> calculateRegisterUsage(ArrayRef<unsigned> VFs);
1904
1905 /// Collect values we want to ignore in the cost model.
1906 void collectValuesToIgnore();
1907
1908 /// \returns The smallest bitwidth each instruction can be represented with.
1909 /// The vector equivalents of these instructions should be truncated to this
1910 /// type.
1911 const MapVector<Instruction *, uint64_t> &getMinimalBitwidths() const {
1912 return MinBWs;
1913 }
1914
1915 /// \returns True if it is more profitable to scalarize instruction \p I for
1916 /// vectorization factor \p VF.
1917 bool isProfitableToScalarize(Instruction *I, unsigned VF) const {
1918 auto Scalars = InstsToScalarize.find(VF);
1919 assert(Scalars != InstsToScalarize.end() &&((Scalars != InstsToScalarize.end() && "VF not yet analyzed for scalarization profitability"
) ? static_cast<void> (0) : __assert_fail ("Scalars != InstsToScalarize.end() && \"VF not yet analyzed for scalarization profitability\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1920, __PRETTY_FUNCTION__))
1920 "VF not yet analyzed for scalarization profitability")((Scalars != InstsToScalarize.end() && "VF not yet analyzed for scalarization profitability"
) ? static_cast<void> (0) : __assert_fail ("Scalars != InstsToScalarize.end() && \"VF not yet analyzed for scalarization profitability\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1920, __PRETTY_FUNCTION__))
;
1921 return Scalars->second.count(I);
1922 }
1923
1924 /// Returns true if \p I is known to be uniform after vectorization.
1925 bool isUniformAfterVectorization(Instruction *I, unsigned VF) const {
1926 if (VF == 1)
1927 return true;
1928 assert(Uniforms.count(VF) && "VF not yet analyzed for uniformity")((Uniforms.count(VF) && "VF not yet analyzed for uniformity"
) ? static_cast<void> (0) : __assert_fail ("Uniforms.count(VF) && \"VF not yet analyzed for uniformity\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1928, __PRETTY_FUNCTION__))
;
1929 auto UniformsPerVF = Uniforms.find(VF);
1930 return UniformsPerVF->second.count(I);
1931 }
1932
1933 /// Returns true if \p I is known to be scalar after vectorization.
1934 bool isScalarAfterVectorization(Instruction *I, unsigned VF) const {
1935 if (VF == 1)
1936 return true;
1937 assert(Scalars.count(VF) && "Scalar values are not calculated for VF")((Scalars.count(VF) && "Scalar values are not calculated for VF"
) ? static_cast<void> (0) : __assert_fail ("Scalars.count(VF) && \"Scalar values are not calculated for VF\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1937, __PRETTY_FUNCTION__))
;
1938 auto ScalarsPerVF = Scalars.find(VF);
1939 return ScalarsPerVF->second.count(I);
1940 }
1941
1942 /// \returns True if instruction \p I can be truncated to a smaller bitwidth
1943 /// for vectorization factor \p VF.
1944 bool canTruncateToMinimalBitwidth(Instruction *I, unsigned VF) const {
1945 return VF > 1 && MinBWs.count(I) && !isProfitableToScalarize(I, VF) &&
1946 !isScalarAfterVectorization(I, VF);
1947 }
1948
1949 /// Decision that was taken during cost calculation for memory instruction.
1950 enum InstWidening {
1951 CM_Unknown,
1952 CM_Widen,
1953 CM_Interleave,
1954 CM_GatherScatter,
1955 CM_Scalarize
1956 };
1957
1958 /// Save vectorization decision \p W and \p Cost taken by the cost model for
1959 /// instruction \p I and vector width \p VF.
1960 void setWideningDecision(Instruction *I, unsigned VF, InstWidening W,
1961 unsigned Cost) {
1962 assert(VF >= 2 && "Expected VF >=2")((VF >= 2 && "Expected VF >=2") ? static_cast<
void> (0) : __assert_fail ("VF >= 2 && \"Expected VF >=2\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1962, __PRETTY_FUNCTION__))
;
1963 WideningDecisions[std::make_pair(I, VF)] = std::make_pair(W, Cost);
1964 }
1965
1966 /// Save vectorization decision \p W and \p Cost taken by the cost model for
1967 /// interleaving group \p Grp and vector width \p VF.
1968 void setWideningDecision(const InterleaveGroup *Grp, unsigned VF,
1969 InstWidening W, unsigned Cost) {
1970 assert(VF >= 2 && "Expected VF >=2")((VF >= 2 && "Expected VF >=2") ? static_cast<
void> (0) : __assert_fail ("VF >= 2 && \"Expected VF >=2\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1970, __PRETTY_FUNCTION__))
;
1971 /// Broadcast this decicion to all instructions inside the group.
1972 /// But the cost will be assigned to one instruction only.
1973 for (unsigned i = 0; i < Grp->getFactor(); ++i) {
1974 if (auto *I = Grp->getMember(i)) {
1975 if (Grp->getInsertPos() == I)
1976 WideningDecisions[std::make_pair(I, VF)] = std::make_pair(W, Cost);
1977 else
1978 WideningDecisions[std::make_pair(I, VF)] = std::make_pair(W, 0);
1979 }
1980 }
1981 }
1982
1983 /// Return the cost model decision for the given instruction \p I and vector
1984 /// width \p VF. Return CM_Unknown if this instruction did not pass
1985 /// through the cost modeling.
1986 InstWidening getWideningDecision(Instruction *I, unsigned VF) {
1987 assert(VF >= 2 && "Expected VF >=2")((VF >= 2 && "Expected VF >=2") ? static_cast<
void> (0) : __assert_fail ("VF >= 2 && \"Expected VF >=2\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1987, __PRETTY_FUNCTION__))
;
1988 std::pair<Instruction *, unsigned> InstOnVF = std::make_pair(I, VF);
1989 auto Itr = WideningDecisions.find(InstOnVF);
1990 if (Itr == WideningDecisions.end())
1991 return CM_Unknown;
1992 return Itr->second.first;
1993 }
1994
1995 /// Return the vectorization cost for the given instruction \p I and vector
1996 /// width \p VF.
1997 unsigned getWideningCost(Instruction *I, unsigned VF) {
1998 assert(VF >= 2 && "Expected VF >=2")((VF >= 2 && "Expected VF >=2") ? static_cast<
void> (0) : __assert_fail ("VF >= 2 && \"Expected VF >=2\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1998, __PRETTY_FUNCTION__))
;
1999 std::pair<Instruction *, unsigned> InstOnVF = std::make_pair(I, VF);
2000 assert(WideningDecisions.count(InstOnVF) && "The cost is not calculated")((WideningDecisions.count(InstOnVF) && "The cost is not calculated"
) ? static_cast<void> (0) : __assert_fail ("WideningDecisions.count(InstOnVF) && \"The cost is not calculated\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2000, __PRETTY_FUNCTION__))
;
2001 return WideningDecisions[InstOnVF].second;
2002 }
2003
2004 /// Return True if instruction \p I is an optimizable truncate whose operand
2005 /// is an induction variable. Such a truncate will be removed by adding a new
2006 /// induction variable with the destination type.
2007 bool isOptimizableIVTruncate(Instruction *I, unsigned VF) {
2008
2009 // If the instruction is not a truncate, return false.
2010 auto *Trunc = dyn_cast<TruncInst>(I);
2011 if (!Trunc)
2012 return false;
2013
2014 // Get the source and destination types of the truncate.
2015 Type *SrcTy = ToVectorTy(cast<CastInst>(I)->getSrcTy(), VF);
2016 Type *DestTy = ToVectorTy(cast<CastInst>(I)->getDestTy(), VF);
2017
2018 // If the truncate is free for the given types, return false. Replacing a
2019 // free truncate with an induction variable would add an induction variable
2020 // update instruction to each iteration of the loop. We exclude from this
2021 // check the primary induction variable since it will need an update
2022 // instruction regardless.
2023 Value *Op = Trunc->getOperand(0);
2024 if (Op != Legal->getPrimaryInduction() && TTI.isTruncateFree(SrcTy, DestTy))
2025 return false;
2026
2027 // If the truncated value is not an induction variable, return false.
2028 return Legal->isInductionVariable(Op);
2029 }
2030
2031private:
2032 /// \return An upper bound for the vectorization factor, larger than zero.
2033 /// One is returned if vectorization should best be avoided due to cost.
2034 unsigned computeFeasibleMaxVF(bool OptForSize);
2035
2036 /// The vectorization cost is a combination of the cost itself and a boolean
2037 /// indicating whether any of the contributing operations will actually
2038 /// operate on
2039 /// vector values after type legalization in the backend. If this latter value
2040 /// is
2041 /// false, then all operations will be scalarized (i.e. no vectorization has
2042 /// actually taken place).
2043 typedef std::pair<unsigned, bool> VectorizationCostTy;
2044
2045 /// Returns the expected execution cost. The unit of the cost does
2046 /// not matter because we use the 'cost' units to compare different
2047 /// vector widths. The cost that is returned is *not* normalized by
2048 /// the factor width.
2049 VectorizationCostTy expectedCost(unsigned VF);
2050
2051 /// Returns the execution time cost of an instruction for a given vector
2052 /// width. Vector width of one means scalar.
2053 VectorizationCostTy getInstructionCost(Instruction *I, unsigned VF);
2054
2055 /// The cost-computation logic from getInstructionCost which provides
2056 /// the vector type as an output parameter.
2057 unsigned getInstructionCost(Instruction *I, unsigned VF, Type *&VectorTy);
2058
2059 /// Calculate vectorization cost of memory instruction \p I.
2060 unsigned getMemoryInstructionCost(Instruction *I, unsigned VF);
2061
2062 /// The cost computation for scalarized memory instruction.
2063 unsigned getMemInstScalarizationCost(Instruction *I, unsigned VF);
2064
2065 /// The cost computation for interleaving group of memory instructions.
2066 unsigned getInterleaveGroupCost(Instruction *I, unsigned VF);
2067
2068 /// The cost computation for Gather/Scatter instruction.
2069 unsigned getGatherScatterCost(Instruction *I, unsigned VF);
2070
2071 /// The cost computation for widening instruction \p I with consecutive
2072 /// memory access.
2073 unsigned getConsecutiveMemOpCost(Instruction *I, unsigned VF);
2074
2075 /// The cost calculation for Load instruction \p I with uniform pointer -
2076 /// scalar load + broadcast.
2077 unsigned getUniformMemOpCost(Instruction *I, unsigned VF);
2078
2079 /// Returns whether the instruction is a load or store and will be a emitted
2080 /// as a vector operation.
2081 bool isConsecutiveLoadOrStore(Instruction *I);
2082
2083 /// Create an analysis remark that explains why vectorization failed
2084 ///
2085 /// \p RemarkName is the identifier for the remark. \return the remark object
2086 /// that can be streamed to.
2087 OptimizationRemarkAnalysis createMissedAnalysis(StringRef RemarkName) {
2088 return ::createMissedAnalysis(Hints->vectorizeAnalysisPassName(),
2089 RemarkName, TheLoop);
2090 }
2091
2092 /// Map of scalar integer values to the smallest bitwidth they can be legally
2093 /// represented as. The vector equivalents of these values should be truncated
2094 /// to this type.
2095 MapVector<Instruction *, uint64_t> MinBWs;
2096
2097 /// A type representing the costs for instructions if they were to be
2098 /// scalarized rather than vectorized. The entries are Instruction-Cost
2099 /// pairs.
2100 typedef DenseMap<Instruction *, unsigned> ScalarCostsTy;
2101
2102 /// A set containing all BasicBlocks that are known to present after
2103 /// vectorization as a predicated block.
2104 SmallPtrSet<BasicBlock *, 4> PredicatedBBsAfterVectorization;
2105
2106 /// A map holding scalar costs for different vectorization factors. The
2107 /// presence of a cost for an instruction in the mapping indicates that the
2108 /// instruction will be scalarized when vectorizing with the associated
2109 /// vectorization factor. The entries are VF-ScalarCostTy pairs.
2110 DenseMap<unsigned, ScalarCostsTy> InstsToScalarize;
2111
2112 /// Holds the instructions known to be uniform after vectorization.
2113 /// The data is collected per VF.
2114 DenseMap<unsigned, SmallPtrSet<Instruction *, 4>> Uniforms;
2115
2116 /// Holds the instructions known to be scalar after vectorization.
2117 /// The data is collected per VF.
2118 DenseMap<unsigned, SmallPtrSet<Instruction *, 4>> Scalars;
2119
2120 /// Holds the instructions (address computations) that are forced to be
2121 /// scalarized.
2122 DenseMap<unsigned, SmallPtrSet<Instruction *, 4>> ForcedScalars;
2123
2124 /// Returns the expected difference in cost from scalarizing the expression
2125 /// feeding a predicated instruction \p PredInst. The instructions to
2126 /// scalarize and their scalar costs are collected in \p ScalarCosts. A
2127 /// non-negative return value implies the expression will be scalarized.
2128 /// Currently, only single-use chains are considered for scalarization.
2129 int computePredInstDiscount(Instruction *PredInst, ScalarCostsTy &ScalarCosts,
2130 unsigned VF);
2131
2132 /// Collects the instructions to scalarize for each predicated instruction in
2133 /// the loop.
2134 void collectInstsToScalarize(unsigned VF);
2135
2136 /// Collect the instructions that are uniform after vectorization. An
2137 /// instruction is uniform if we represent it with a single scalar value in
2138 /// the vectorized loop corresponding to each vector iteration. Examples of
2139 /// uniform instructions include pointer operands of consecutive or
2140 /// interleaved memory accesses. Note that although uniformity implies an
2141 /// instruction will be scalar, the reverse is not true. In general, a
2142 /// scalarized instruction will be represented by VF scalar values in the
2143 /// vectorized loop, each corresponding to an iteration of the original
2144 /// scalar loop.
2145 void collectLoopUniforms(unsigned VF);
2146
2147 /// Collect the instructions that are scalar after vectorization. An
2148 /// instruction is scalar if it is known to be uniform or will be scalarized
2149 /// during vectorization. Non-uniform scalarized instructions will be
2150 /// represented by VF values in the vectorized loop, each corresponding to an
2151 /// iteration of the original scalar loop.
2152 void collectLoopScalars(unsigned VF);
2153
2154 /// Collect Uniform and Scalar values for the given \p VF.
2155 /// The sets depend on CM decision for Load/Store instructions
2156 /// that may be vectorized as interleave, gather-scatter or scalarized.
2157 void collectUniformsAndScalars(unsigned VF) {
2158 // Do the analysis once.
2159 if (VF == 1 || Uniforms.count(VF))
2160 return;
2161 setCostBasedWideningDecision(VF);
2162 collectLoopUniforms(VF);
2163 collectLoopScalars(VF);
2164 }
2165
2166 /// Keeps cost model vectorization decision and cost for instructions.
2167 /// Right now it is used for memory instructions only.
2168 typedef DenseMap<std::pair<Instruction *, unsigned>,
2169 std::pair<InstWidening, unsigned>>
2170 DecisionList;
2171
2172 DecisionList WideningDecisions;
2173
2174public:
2175 /// The loop that we evaluate.
2176 Loop *TheLoop;
2177 /// Predicated scalar evolution analysis.
2178 PredicatedScalarEvolution &PSE;
2179 /// Loop Info analysis.
2180 LoopInfo *LI;
2181 /// Vectorization legality.
2182 LoopVectorizationLegality *Legal;
2183 /// Vector target information.
2184 const TargetTransformInfo &TTI;
2185 /// Target Library Info.
2186 const TargetLibraryInfo *TLI;
2187 /// Demanded bits analysis.
2188 DemandedBits *DB;
2189 /// Assumption cache.
2190 AssumptionCache *AC;
2191 /// Interface to emit optimization remarks.
2192 OptimizationRemarkEmitter *ORE;
2193
2194 const Function *TheFunction;
2195 /// Loop Vectorize Hint.
2196 const LoopVectorizeHints *Hints;
2197 /// Values to ignore in the cost model.
2198 SmallPtrSet<const Value *, 16> ValuesToIgnore;
2199 /// Values to ignore in the cost model when VF > 1.
2200 SmallPtrSet<const Value *, 16> VecValuesToIgnore;
2201};
2202
2203/// LoopVectorizationPlanner - drives the vectorization process after having
2204/// passed Legality checks.
2205class LoopVectorizationPlanner {
2206public:
2207 LoopVectorizationPlanner(Loop *OrigLoop, LoopInfo *LI,
2208 LoopVectorizationLegality *Legal,
2209 LoopVectorizationCostModel &CM)
2210 : OrigLoop(OrigLoop), LI(LI), Legal(Legal), CM(CM) {}
2211
2212 ~LoopVectorizationPlanner() {}
2213
2214 /// Plan how to best vectorize, return the best VF and its cost.
2215 LoopVectorizationCostModel::VectorizationFactor plan(bool OptForSize,
2216 unsigned UserVF);
2217
2218 /// Generate the IR code for the vectorized loop.
2219 void executePlan(InnerLoopVectorizer &ILV);
2220
2221protected:
2222 /// Collect the instructions from the original loop that would be trivially
2223 /// dead in the vectorized loop if generated.
2224 void collectTriviallyDeadInstructions(
2225 SmallPtrSetImpl<Instruction *> &DeadInstructions);
2226
2227private:
2228 /// The loop that we evaluate.
2229 Loop *OrigLoop;
2230
2231 /// Loop Info analysis.
2232 LoopInfo *LI;
2233
2234 /// The legality analysis.
2235 LoopVectorizationLegality *Legal;
2236
2237 /// The profitablity analysis.
2238 LoopVectorizationCostModel &CM;
2239};
2240
2241/// \brief This holds vectorization requirements that must be verified late in
2242/// the process. The requirements are set by legalize and costmodel. Once
2243/// vectorization has been determined to be possible and profitable the
2244/// requirements can be verified by looking for metadata or compiler options.
2245/// For example, some loops require FP commutativity which is only allowed if
2246/// vectorization is explicitly specified or if the fast-math compiler option
2247/// has been provided.
2248/// Late evaluation of these requirements allows helpful diagnostics to be
2249/// composed that tells the user what need to be done to vectorize the loop. For
2250/// example, by specifying #pragma clang loop vectorize or -ffast-math. Late
2251/// evaluation should be used only when diagnostics can generated that can be
2252/// followed by a non-expert user.
2253class LoopVectorizationRequirements {
2254public:
2255 LoopVectorizationRequirements(OptimizationRemarkEmitter &ORE)
2256 : NumRuntimePointerChecks(0), UnsafeAlgebraInst(nullptr), ORE(ORE) {}
2257
2258 void addUnsafeAlgebraInst(Instruction *I) {
2259 // First unsafe algebra instruction.
2260 if (!UnsafeAlgebraInst)
2261 UnsafeAlgebraInst = I;
2262 }
2263
2264 void addRuntimePointerChecks(unsigned Num) { NumRuntimePointerChecks = Num; }
2265
2266 bool doesNotMeet(Function *F, Loop *L, const LoopVectorizeHints &Hints) {
2267 const char *PassName = Hints.vectorizeAnalysisPassName();
2268 bool Failed = false;
2269 if (UnsafeAlgebraInst && !Hints.allowReordering()) {
2270 ORE.emit(
2271 OptimizationRemarkAnalysisFPCommute(PassName, "CantReorderFPOps",
2272 UnsafeAlgebraInst->getDebugLoc(),
2273 UnsafeAlgebraInst->getParent())
2274 << "loop not vectorized: cannot prove it is safe to reorder "
2275 "floating-point operations");
2276 Failed = true;
2277 }
2278
2279 // Test if runtime memcheck thresholds are exceeded.
2280 bool PragmaThresholdReached =
2281 NumRuntimePointerChecks > PragmaVectorizeMemoryCheckThreshold;
2282 bool ThresholdReached =
2283 NumRuntimePointerChecks > VectorizerParams::RuntimeMemoryCheckThreshold;
2284 if ((ThresholdReached && !Hints.allowReordering()) ||
2285 PragmaThresholdReached) {
2286 ORE.emit(OptimizationRemarkAnalysisAliasing(PassName, "CantReorderMemOps",
2287 L->getStartLoc(),
2288 L->getHeader())
2289 << "loop not vectorized: cannot prove it is safe to reorder "
2290 "memory operations");
2291 DEBUG(dbgs() << "LV: Too many memory checks needed.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Too many memory checks needed.\n"
; } } while (false)
;
2292 Failed = true;
2293 }
2294
2295 return Failed;
2296 }
2297
2298private:
2299 unsigned NumRuntimePointerChecks;
2300 Instruction *UnsafeAlgebraInst;
2301
2302 /// Interface to emit optimization remarks.
2303 OptimizationRemarkEmitter &ORE;
2304};
2305
2306static void addAcyclicInnerLoop(Loop &L, SmallVectorImpl<Loop *> &V) {
2307 if (L.empty()) {
2308 if (!hasCyclesInLoopBody(L))
2309 V.push_back(&L);
2310 return;
2311 }
2312 for (Loop *InnerL : L)
2313 addAcyclicInnerLoop(*InnerL, V);
2314}
2315
2316/// The LoopVectorize Pass.
2317struct LoopVectorize : public FunctionPass {
2318 /// Pass identification, replacement for typeid
2319 static char ID;
2320
2321 explicit LoopVectorize(bool NoUnrolling = false, bool AlwaysVectorize = true)
2322 : FunctionPass(ID) {
2323 Impl.DisableUnrolling = NoUnrolling;
2324 Impl.AlwaysVectorize = AlwaysVectorize;
2325 initializeLoopVectorizePass(*PassRegistry::getPassRegistry());
2326 }
2327
2328 LoopVectorizePass Impl;
2329
2330 bool runOnFunction(Function &F) override {
2331 if (skipFunction(F))
2332 return false;
2333
2334 auto *SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
2335 auto *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
2336 auto *TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
2337 auto *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2338 auto *BFI = &getAnalysis<BlockFrequencyInfoWrapperPass>().getBFI();
2339 auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
2340 auto *TLI = TLIP ? &TLIP->getTLI() : nullptr;
2341 auto *AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
2342 auto *AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
2343 auto *LAA = &getAnalysis<LoopAccessLegacyAnalysis>();
2344 auto *DB = &getAnalysis<DemandedBitsWrapperPass>().getDemandedBits();
2345 auto *ORE = &getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
2346
2347 std::function<const LoopAccessInfo &(Loop &)> GetLAA =
2348 [&](Loop &L) -> const LoopAccessInfo & { return LAA->getInfo(&L); };
2349
2350 return Impl.runImpl(F, *SE, *LI, *TTI, *DT, *BFI, TLI, *DB, *AA, *AC,
2351 GetLAA, *ORE);
2352 }
2353
2354 void getAnalysisUsage(AnalysisUsage &AU) const override {
2355 AU.addRequired<AssumptionCacheTracker>();
2356 AU.addRequired<BlockFrequencyInfoWrapperPass>();
2357 AU.addRequired<DominatorTreeWrapperPass>();
2358 AU.addRequired<LoopInfoWrapperPass>();
2359 AU.addRequired<ScalarEvolutionWrapperPass>();
2360 AU.addRequired<TargetTransformInfoWrapperPass>();
2361 AU.addRequired<AAResultsWrapperPass>();
2362 AU.addRequired<LoopAccessLegacyAnalysis>();
2363 AU.addRequired<DemandedBitsWrapperPass>();
2364 AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
2365 AU.addPreserved<LoopInfoWrapperPass>();
2366 AU.addPreserved<DominatorTreeWrapperPass>();
2367 AU.addPreserved<BasicAAWrapperPass>();
2368 AU.addPreserved<GlobalsAAWrapperPass>();
2369 }
2370};
2371
2372} // end anonymous namespace
2373
2374//===----------------------------------------------------------------------===//
2375// Implementation of LoopVectorizationLegality, InnerLoopVectorizer and
2376// LoopVectorizationCostModel and LoopVectorizationPlanner.
2377//===----------------------------------------------------------------------===//
2378
2379Value *InnerLoopVectorizer::getBroadcastInstrs(Value *V) {
2380 // We need to place the broadcast of invariant variables outside the loop.
2381 Instruction *Instr = dyn_cast<Instruction>(V);
2382 bool NewInstr = (Instr && Instr->getParent() == LoopVectorBody);
2383 bool Invariant = OrigLoop->isLoopInvariant(V) && !NewInstr;
2384
2385 // Place the code for broadcasting invariant variables in the new preheader.
2386 IRBuilder<>::InsertPointGuard Guard(Builder);
2387 if (Invariant)
2388 Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator());
2389
2390 // Broadcast the scalar into all locations in the vector.
2391 Value *Shuf = Builder.CreateVectorSplat(VF, V, "broadcast");
2392
2393 return Shuf;
2394}
2395
2396void InnerLoopVectorizer::createVectorIntOrFpInductionPHI(
2397 const InductionDescriptor &II, Value *Step, Instruction *EntryVal) {
2398 Value *Start = II.getStartValue();
2399
2400 // Construct the initial value of the vector IV in the vector loop preheader
2401 auto CurrIP = Builder.saveIP();
2402 Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator());
2403 if (isa<TruncInst>(EntryVal)) {
2404 assert(Start->getType()->isIntegerTy() &&((Start->getType()->isIntegerTy() && "Truncation requires an integer type"
) ? static_cast<void> (0) : __assert_fail ("Start->getType()->isIntegerTy() && \"Truncation requires an integer type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2405, __PRETTY_FUNCTION__))
2405 "Truncation requires an integer type")((Start->getType()->isIntegerTy() && "Truncation requires an integer type"
) ? static_cast<void> (0) : __assert_fail ("Start->getType()->isIntegerTy() && \"Truncation requires an integer type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2405, __PRETTY_FUNCTION__))
;
2406 auto *TruncType = cast<IntegerType>(EntryVal->getType());
2407 Step = Builder.CreateTrunc(Step, TruncType);
2408 Start = Builder.CreateCast(Instruction::Trunc, Start, TruncType);
2409 }
2410 Value *SplatStart = Builder.CreateVectorSplat(VF, Start);
2411 Value *SteppedStart =
2412 getStepVector(SplatStart, 0, Step, II.getInductionOpcode());
2413
2414 // We create vector phi nodes for both integer and floating-point induction
2415 // variables. Here, we determine the kind of arithmetic we will perform.
2416 Instruction::BinaryOps AddOp;
2417 Instruction::BinaryOps MulOp;
2418 if (Step->getType()->isIntegerTy()) {
2419 AddOp = Instruction::Add;
2420 MulOp = Instruction::Mul;
2421 } else {
2422 AddOp = II.getInductionOpcode();
2423 MulOp = Instruction::FMul;
2424 }
2425
2426 // Multiply the vectorization factor by the step using integer or
2427 // floating-point arithmetic as appropriate.
2428 Value *ConstVF = getSignedIntOrFpConstant(Step->getType(), VF);
2429 Value *Mul = addFastMathFlag(Builder.CreateBinOp(MulOp, Step, ConstVF));
2430
2431 // Create a vector splat to use in the induction update.
2432 //
2433 // FIXME: If the step is non-constant, we create the vector splat with
2434 // IRBuilder. IRBuilder can constant-fold the multiply, but it doesn't
2435 // handle a constant vector splat.
2436 Value *SplatVF = isa<Constant>(Mul)
2437 ? ConstantVector::getSplat(VF, cast<Constant>(Mul))
2438 : Builder.CreateVectorSplat(VF, Mul);
2439 Builder.restoreIP(CurrIP);
2440
2441 // We may need to add the step a number of times, depending on the unroll
2442 // factor. The last of those goes into the PHI.
2443 PHINode *VecInd = PHINode::Create(SteppedStart->getType(), 2, "vec.ind",
2444 &*LoopVectorBody->getFirstInsertionPt());
2445 Instruction *LastInduction = VecInd;
2446 for (unsigned Part = 0; Part < UF; ++Part) {
2447 VectorLoopValueMap.setVectorValue(EntryVal, Part, LastInduction);
2448 if (isa<TruncInst>(EntryVal))
2449 addMetadata(LastInduction, EntryVal);
2450 LastInduction = cast<Instruction>(addFastMathFlag(
2451 Builder.CreateBinOp(AddOp, LastInduction, SplatVF, "step.add")));
2452 }
2453
2454 // Move the last step to the end of the latch block. This ensures consistent
2455 // placement of all induction updates.
2456 auto *LoopVectorLatch = LI->getLoopFor(LoopVectorBody)->getLoopLatch();
2457 auto *Br = cast<BranchInst>(LoopVectorLatch->getTerminator());
2458 auto *ICmp = cast<Instruction>(Br->getCondition());
2459 LastInduction->moveBefore(ICmp);
2460 LastInduction->setName("vec.ind.next");
2461
2462 VecInd->addIncoming(SteppedStart, LoopVectorPreHeader);
2463 VecInd->addIncoming(LastInduction, LoopVectorLatch);
2464}
2465
2466bool InnerLoopVectorizer::shouldScalarizeInstruction(Instruction *I) const {
2467 return Cost->isScalarAfterVectorization(I, VF) ||
2468 Cost->isProfitableToScalarize(I, VF);
2469}
2470
2471bool InnerLoopVectorizer::needsScalarInduction(Instruction *IV) const {
2472 if (shouldScalarizeInstruction(IV))
2473 return true;
2474 auto isScalarInst = [&](User *U) -> bool {
2475 auto *I = cast<Instruction>(U);
2476 return (OrigLoop->contains(I) && shouldScalarizeInstruction(I));
2477 };
2478 return any_of(IV->users(), isScalarInst);
2479}
2480
2481void InnerLoopVectorizer::widenIntOrFpInduction(PHINode *IV, TruncInst *Trunc) {
2482
2483 assert((IV->getType()->isIntegerTy() || IV != OldInduction) &&(((IV->getType()->isIntegerTy() || IV != OldInduction) &&
"Primary induction variable must have an integer type") ? static_cast
<void> (0) : __assert_fail ("(IV->getType()->isIntegerTy() || IV != OldInduction) && \"Primary induction variable must have an integer type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2484, __PRETTY_FUNCTION__))
2484 "Primary induction variable must have an integer type")(((IV->getType()->isIntegerTy() || IV != OldInduction) &&
"Primary induction variable must have an integer type") ? static_cast
<void> (0) : __assert_fail ("(IV->getType()->isIntegerTy() || IV != OldInduction) && \"Primary induction variable must have an integer type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2484, __PRETTY_FUNCTION__))
;
2485
2486 auto II = Legal->getInductionVars()->find(IV);
2487 assert(II != Legal->getInductionVars()->end() && "IV is not an induction")((II != Legal->getInductionVars()->end() && "IV is not an induction"
) ? static_cast<void> (0) : __assert_fail ("II != Legal->getInductionVars()->end() && \"IV is not an induction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2487, __PRETTY_FUNCTION__))
;
2488
2489 auto ID = II->second;
2490 assert(IV->getType() == ID.getStartValue()->getType() && "Types must match")((IV->getType() == ID.getStartValue()->getType() &&
"Types must match") ? static_cast<void> (0) : __assert_fail
("IV->getType() == ID.getStartValue()->getType() && \"Types must match\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2490, __PRETTY_FUNCTION__))
;
2491
2492 // The scalar value to broadcast. This will be derived from the canonical
2493 // induction variable.
2494 Value *ScalarIV = nullptr;
2495
2496 // The value from the original loop to which we are mapping the new induction
2497 // variable.
2498 Instruction *EntryVal = Trunc ? cast<Instruction>(Trunc) : IV;
2499
2500 // True if we have vectorized the induction variable.
2501 auto VectorizedIV = false;
2502
2503 // Determine if we want a scalar version of the induction variable. This is
2504 // true if the induction variable itself is not widened, or if it has at
2505 // least one user in the loop that is not widened.
2506 auto NeedsScalarIV = VF > 1 && needsScalarInduction(EntryVal);
2507
2508 // Generate code for the induction step. Note that induction steps are
2509 // required to be loop-invariant
2510 assert(PSE.getSE()->isLoopInvariant(ID.getStep(), OrigLoop) &&((PSE.getSE()->isLoopInvariant(ID.getStep(), OrigLoop) &&
"Induction step should be loop invariant") ? static_cast<
void> (0) : __assert_fail ("PSE.getSE()->isLoopInvariant(ID.getStep(), OrigLoop) && \"Induction step should be loop invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2511, __PRETTY_FUNCTION__))
2511 "Induction step should be loop invariant")((PSE.getSE()->isLoopInvariant(ID.getStep(), OrigLoop) &&
"Induction step should be loop invariant") ? static_cast<
void> (0) : __assert_fail ("PSE.getSE()->isLoopInvariant(ID.getStep(), OrigLoop) && \"Induction step should be loop invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2511, __PRETTY_FUNCTION__))
;
2512 auto &DL = OrigLoop->getHeader()->getModule()->getDataLayout();
2513 Value *Step = nullptr;
2514 if (PSE.getSE()->isSCEVable(IV->getType())) {
2515 SCEVExpander Exp(*PSE.getSE(), DL, "induction");
2516 Step = Exp.expandCodeFor(ID.getStep(), ID.getStep()->getType(),
2517 LoopVectorPreHeader->getTerminator());
2518 } else {
2519 Step = cast<SCEVUnknown>(ID.getStep())->getValue();
2520 }
2521
2522 // Try to create a new independent vector induction variable. If we can't
2523 // create the phi node, we will splat the scalar induction variable in each
2524 // loop iteration.
2525 if (VF > 1 && !shouldScalarizeInstruction(EntryVal)) {
2526 createVectorIntOrFpInductionPHI(ID, Step, EntryVal);
2527 VectorizedIV = true;
2528 }
2529
2530 // If we haven't yet vectorized the induction variable, or if we will create
2531 // a scalar one, we need to define the scalar induction variable and step
2532 // values. If we were given a truncation type, truncate the canonical
2533 // induction variable and step. Otherwise, derive these values from the
2534 // induction descriptor.
2535 if (!VectorizedIV || NeedsScalarIV) {
2536 ScalarIV = Induction;
2537 if (IV != OldInduction) {
2538 ScalarIV = IV->getType()->isIntegerTy()
2539 ? Builder.CreateSExtOrTrunc(Induction, IV->getType())
2540 : Builder.CreateCast(Instruction::SIToFP, Induction,
2541 IV->getType());
2542 ScalarIV = ID.transform(Builder, ScalarIV, PSE.getSE(), DL);
2543 ScalarIV->setName("offset.idx");
2544 }
2545 if (Trunc) {
2546 auto *TruncType = cast<IntegerType>(Trunc->getType());
2547 assert(Step->getType()->isIntegerTy() &&((Step->getType()->isIntegerTy() && "Truncation requires an integer step"
) ? static_cast<void> (0) : __assert_fail ("Step->getType()->isIntegerTy() && \"Truncation requires an integer step\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2548, __PRETTY_FUNCTION__))
2548 "Truncation requires an integer step")((Step->getType()->isIntegerTy() && "Truncation requires an integer step"
) ? static_cast<void> (0) : __assert_fail ("Step->getType()->isIntegerTy() && \"Truncation requires an integer step\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2548, __PRETTY_FUNCTION__))
;
2549 ScalarIV = Builder.CreateTrunc(ScalarIV, TruncType);
2550 Step = Builder.CreateTrunc(Step, TruncType);
2551 }
2552 }
2553
2554 // If we haven't yet vectorized the induction variable, splat the scalar
2555 // induction variable, and build the necessary step vectors.
2556 if (!VectorizedIV) {
2557 Value *Broadcasted = getBroadcastInstrs(ScalarIV);
2558 for (unsigned Part = 0; Part < UF; ++Part) {
2559 Value *EntryPart =
2560 getStepVector(Broadcasted, VF * Part, Step, ID.getInductionOpcode());
2561 VectorLoopValueMap.setVectorValue(EntryVal, Part, EntryPart);
2562 if (Trunc)
2563 addMetadata(EntryPart, Trunc);
2564 }
2565 }
2566
2567 // If an induction variable is only used for counting loop iterations or
2568 // calculating addresses, it doesn't need to be widened. Create scalar steps
2569 // that can be used by instructions we will later scalarize. Note that the
2570 // addition of the scalar steps will not increase the number of instructions
2571 // in the loop in the common case prior to InstCombine. We will be trading
2572 // one vector extract for each scalar step.
2573 if (NeedsScalarIV)
2574 buildScalarSteps(ScalarIV, Step, EntryVal, ID);
2575}
2576
2577Value *InnerLoopVectorizer::getStepVector(Value *Val, int StartIdx, Value *Step,
2578 Instruction::BinaryOps BinOp) {
2579 // Create and check the types.
2580 assert(Val->getType()->isVectorTy() && "Must be a vector")((Val->getType()->isVectorTy() && "Must be a vector"
) ? static_cast<void> (0) : __assert_fail ("Val->getType()->isVectorTy() && \"Must be a vector\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2580, __PRETTY_FUNCTION__))
;
2581 int VLen = Val->getType()->getVectorNumElements();
2582
2583 Type *STy = Val->getType()->getScalarType();
2584 assert((STy->isIntegerTy() || STy->isFloatingPointTy()) &&(((STy->isIntegerTy() || STy->isFloatingPointTy()) &&
"Induction Step must be an integer or FP") ? static_cast<
void> (0) : __assert_fail ("(STy->isIntegerTy() || STy->isFloatingPointTy()) && \"Induction Step must be an integer or FP\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2585, __PRETTY_FUNCTION__))
2585 "Induction Step must be an integer or FP")(((STy->isIntegerTy() || STy->isFloatingPointTy()) &&
"Induction Step must be an integer or FP") ? static_cast<
void> (0) : __assert_fail ("(STy->isIntegerTy() || STy->isFloatingPointTy()) && \"Induction Step must be an integer or FP\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2585, __PRETTY_FUNCTION__))
;
2586 assert(Step->getType() == STy && "Step has wrong type")((Step->getType() == STy && "Step has wrong type")
? static_cast<void> (0) : __assert_fail ("Step->getType() == STy && \"Step has wrong type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2586, __PRETTY_FUNCTION__))
;
2587
2588 SmallVector<Constant *, 8> Indices;
2589
2590 if (STy->isIntegerTy()) {
2591 // Create a vector of consecutive numbers from zero to VF.
2592 for (int i = 0; i < VLen; ++i)
2593 Indices.push_back(ConstantInt::get(STy, StartIdx + i));
2594
2595 // Add the consecutive indices to the vector value.
2596 Constant *Cv = ConstantVector::get(Indices);
2597 assert(Cv->getType() == Val->getType() && "Invalid consecutive vec")((Cv->getType() == Val->getType() && "Invalid consecutive vec"
) ? static_cast<void> (0) : __assert_fail ("Cv->getType() == Val->getType() && \"Invalid consecutive vec\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2597, __PRETTY_FUNCTION__))
;
2598 Step = Builder.CreateVectorSplat(VLen, Step);
2599 assert(Step->getType() == Val->getType() && "Invalid step vec")((Step->getType() == Val->getType() && "Invalid step vec"
) ? static_cast<void> (0) : __assert_fail ("Step->getType() == Val->getType() && \"Invalid step vec\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2599, __PRETTY_FUNCTION__))
;
2600 // FIXME: The newly created binary instructions should contain nsw/nuw flags,
2601 // which can be found from the original scalar operations.
2602 Step = Builder.CreateMul(Cv, Step);
2603 return Builder.CreateAdd(Val, Step, "induction");
2604 }
2605
2606 // Floating point induction.
2607 assert((BinOp == Instruction::FAdd || BinOp == Instruction::FSub) &&(((BinOp == Instruction::FAdd || BinOp == Instruction::FSub) &&
"Binary Opcode should be specified for FP induction") ? static_cast
<void> (0) : __assert_fail ("(BinOp == Instruction::FAdd || BinOp == Instruction::FSub) && \"Binary Opcode should be specified for FP induction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2608, __PRETTY_FUNCTION__))
2608 "Binary Opcode should be specified for FP induction")(((BinOp == Instruction::FAdd || BinOp == Instruction::FSub) &&
"Binary Opcode should be specified for FP induction") ? static_cast
<void> (0) : __assert_fail ("(BinOp == Instruction::FAdd || BinOp == Instruction::FSub) && \"Binary Opcode should be specified for FP induction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2608, __PRETTY_FUNCTION__))
;
2609 // Create a vector of consecutive numbers from zero to VF.
2610 for (int i = 0; i < VLen; ++i)
2611 Indices.push_back(ConstantFP::get(STy, (double)(StartIdx + i)));
2612
2613 // Add the consecutive indices to the vector value.
2614 Constant *Cv = ConstantVector::get(Indices);
2615
2616 Step = Builder.CreateVectorSplat(VLen, Step);
2617
2618 // Floating point operations had to be 'fast' to enable the induction.
2619 FastMathFlags Flags;
2620 Flags.setUnsafeAlgebra();
2621
2622 Value *MulOp = Builder.CreateFMul(Cv, Step);
2623 if (isa<Instruction>(MulOp))
2624 // Have to check, MulOp may be a constant
2625 cast<Instruction>(MulOp)->setFastMathFlags(Flags);
2626
2627 Value *BOp = Builder.CreateBinOp(BinOp, Val, MulOp, "induction");
2628 if (isa<Instruction>(BOp))
2629 cast<Instruction>(BOp)->setFastMathFlags(Flags);
2630 return BOp;
2631}
2632
2633void InnerLoopVectorizer::buildScalarSteps(Value *ScalarIV, Value *Step,
2634 Value *EntryVal,
2635 const InductionDescriptor &ID) {
2636
2637 // We shouldn't have to build scalar steps if we aren't vectorizing.
2638 assert(VF > 1 && "VF should be greater than one")((VF > 1 && "VF should be greater than one") ? static_cast
<void> (0) : __assert_fail ("VF > 1 && \"VF should be greater than one\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2638, __PRETTY_FUNCTION__))
;
2639
2640 // Get the value type and ensure it and the step have the same integer type.
2641 Type *ScalarIVTy = ScalarIV->getType()->getScalarType();
2642 assert(ScalarIVTy == Step->getType() &&((ScalarIVTy == Step->getType() && "Val and Step should have the same type"
) ? static_cast<void> (0) : __assert_fail ("ScalarIVTy == Step->getType() && \"Val and Step should have the same type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2643, __PRETTY_FUNCTION__))
2643 "Val and Step should have the same type")((ScalarIVTy == Step->getType() && "Val and Step should have the same type"
) ? static_cast<void> (0) : __assert_fail ("ScalarIVTy == Step->getType() && \"Val and Step should have the same type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2643, __PRETTY_FUNCTION__))
;
2644
2645 // We build scalar steps for both integer and floating-point induction
2646 // variables. Here, we determine the kind of arithmetic we will perform.
2647 Instruction::BinaryOps AddOp;
2648 Instruction::BinaryOps MulOp;
2649 if (ScalarIVTy->isIntegerTy()) {
2650 AddOp = Instruction::Add;
2651 MulOp = Instruction::Mul;
2652 } else {
2653 AddOp = ID.getInductionOpcode();
2654 MulOp = Instruction::FMul;
2655 }
2656
2657 // Determine the number of scalars we need to generate for each unroll
2658 // iteration. If EntryVal is uniform, we only need to generate the first
2659 // lane. Otherwise, we generate all VF values.
2660 unsigned Lanes =
2661 Cost->isUniformAfterVectorization(cast<Instruction>(EntryVal), VF) ? 1 : VF;
2662
2663 // Compute the scalar steps and save the results in VectorLoopValueMap.
2664 for (unsigned Part = 0; Part < UF; ++Part) {
2665 for (unsigned Lane = 0; Lane < Lanes; ++Lane) {
2666 auto *StartIdx = getSignedIntOrFpConstant(ScalarIVTy, VF * Part + Lane);
2667 auto *Mul = addFastMathFlag(Builder.CreateBinOp(MulOp, StartIdx, Step));
2668 auto *Add = addFastMathFlag(Builder.CreateBinOp(AddOp, ScalarIV, Mul));
2669 VectorLoopValueMap.setScalarValue(EntryVal, Part, Lane, Add);
2670 }
2671 }
2672}
2673
2674int LoopVectorizationLegality::isConsecutivePtr(Value *Ptr) {
2675
2676 const ValueToValueMap &Strides = getSymbolicStrides() ? *getSymbolicStrides() :
2677 ValueToValueMap();
2678
2679 int Stride = getPtrStride(PSE, Ptr, TheLoop, Strides, true, false);
2680 if (Stride == 1 || Stride == -1)
2681 return Stride;
2682 return 0;
2683}
2684
2685bool LoopVectorizationLegality::isUniform(Value *V) {
2686 return LAI->isUniform(V);
2687}
2688
2689Value *InnerLoopVectorizer::getOrCreateVectorValue(Value *V, unsigned Part) {
2690 assert(V != Induction && "The new induction variable should not be used.")((V != Induction && "The new induction variable should not be used."
) ? static_cast<void> (0) : __assert_fail ("V != Induction && \"The new induction variable should not be used.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2690, __PRETTY_FUNCTION__))
;
2691 assert(!V->getType()->isVectorTy() && "Can't widen a vector")((!V->getType()->isVectorTy() && "Can't widen a vector"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isVectorTy() && \"Can't widen a vector\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2691, __PRETTY_FUNCTION__))
;
2692 assert(!V->getType()->isVoidTy() && "Type does not produce a value")((!V->getType()->isVoidTy() && "Type does not produce a value"
) ? static_cast<void> (0) : __assert_fail ("!V->getType()->isVoidTy() && \"Type does not produce a value\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2692, __PRETTY_FUNCTION__))
;
2693
2694 // If we have a stride that is replaced by one, do it here.
2695 if (Legal->hasStride(V))
2696 V = ConstantInt::get(V->getType(), 1);
2697
2698 // If we have a vector mapped to this value, return it.
2699 if (VectorLoopValueMap.hasVectorValue(V, Part))
2700 return VectorLoopValueMap.getVectorValue(V, Part);
2701
2702 // If the value has not been vectorized, check if it has been scalarized
2703 // instead. If it has been scalarized, and we actually need the value in
2704 // vector form, we will construct the vector values on demand.
2705 if (VectorLoopValueMap.hasAnyScalarValue(V)) {
2706
2707 Value *ScalarValue = VectorLoopValueMap.getScalarValue(V, Part, 0);
2708
2709 // If we've scalarized a value, that value should be an instruction.
2710 auto *I = cast<Instruction>(V);
2711
2712 // If we aren't vectorizing, we can just copy the scalar map values over to
2713 // the vector map.
2714 if (VF == 1) {
2715 VectorLoopValueMap.setVectorValue(V, Part, ScalarValue);
2716 return ScalarValue;
2717 }
2718
2719 // Get the last scalar instruction we generated for V. If the value is
2720 // known to be uniform after vectorization, this corresponds to lane zero
2721 // of the last unroll iteration. Otherwise, the last instruction is the one
2722 // we created for the last vector lane of the last unroll iteration.
2723 unsigned LastLane = Cost->isUniformAfterVectorization(I, VF) ? 0 : VF - 1;
2724 auto *LastInst =
2725 cast<Instruction>(getOrCreateScalarValue(V, UF - 1, LastLane));
2726
2727 // Set the insert point after the last scalarized instruction. This ensures
2728 // the insertelement sequence will directly follow the scalar definitions.
2729 auto OldIP = Builder.saveIP();
2730 auto NewIP = std::next(BasicBlock::iterator(LastInst));
2731 Builder.SetInsertPoint(&*NewIP);
2732
2733 // However, if we are vectorizing, we need to construct the vector values.
2734 // If the value is known to be uniform after vectorization, we can just
2735 // broadcast the scalar value corresponding to lane zero for each unroll
2736 // iteration. Otherwise, we construct the vector values using insertelement
2737 // instructions. Since the resulting vectors are stored in
2738 // VectorLoopValueMap, we will only generate the insertelements once.
2739 Value *VectorValue = nullptr;
2740 if (Cost->isUniformAfterVectorization(I, VF)) {
2741 VectorValue = getBroadcastInstrs(ScalarValue);
2742 } else {
2743 VectorValue = UndefValue::get(VectorType::get(V->getType(), VF));
2744 for (unsigned Lane = 0; Lane < VF; ++Lane)
2745 VectorValue = Builder.CreateInsertElement(
2746 VectorValue, getOrCreateScalarValue(V, Part, Lane),
2747 Builder.getInt32(Lane));
2748 }
2749 VectorLoopValueMap.setVectorValue(V, Part, VectorValue);
2750 Builder.restoreIP(OldIP);
2751 return VectorValue;
2752 }
2753
2754 // If this scalar is unknown, assume that it is a constant or that it is
2755 // loop invariant. Broadcast V and save the value for future uses.
2756 Value *B = getBroadcastInstrs(V);
2757 VectorLoopValueMap.setVectorValue(V, Part, B);
2758 return B;
2759}
2760
2761Value *InnerLoopVectorizer::getOrCreateScalarValue(Value *V, unsigned Part,
2762 unsigned Lane) {
2763
2764 // If the value is not an instruction contained in the loop, it should
2765 // already be scalar.
2766 if (OrigLoop->isLoopInvariant(V))
2767 return V;
2768
2769 assert(Lane > 0 ? !Cost->isUniformAfterVectorization(cast<Instruction>(V), VF)((Lane > 0 ? !Cost->isUniformAfterVectorization(cast<
Instruction>(V), VF) : true && "Uniform values only have lane zero"
) ? static_cast<void> (0) : __assert_fail ("Lane > 0 ? !Cost->isUniformAfterVectorization(cast<Instruction>(V), VF) : true && \"Uniform values only have lane zero\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2770, __PRETTY_FUNCTION__))
2770 : true && "Uniform values only have lane zero")((Lane > 0 ? !Cost->isUniformAfterVectorization(cast<
Instruction>(V), VF) : true && "Uniform values only have lane zero"
) ? static_cast<void> (0) : __assert_fail ("Lane > 0 ? !Cost->isUniformAfterVectorization(cast<Instruction>(V), VF) : true && \"Uniform values only have lane zero\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2770, __PRETTY_FUNCTION__))
;
2771
2772 // If the value from the original loop has not been vectorized, it is
2773 // represented by UF x VF scalar values in the new loop. Return the requested
2774 // scalar value.
2775 if (VectorLoopValueMap.hasScalarValue(V, Part, Lane))
2776 return VectorLoopValueMap.getScalarValue(V, Part, Lane);
2777
2778 // If the value has not been scalarized, get its entry in VectorLoopValueMap
2779 // for the given unroll part. If this entry is not a vector type (i.e., the
2780 // vectorization factor is one), there is no need to generate an
2781 // extractelement instruction.
2782 auto *U = getOrCreateVectorValue(V, Part);
2783 if (!U->getType()->isVectorTy()) {
2784 assert(VF == 1 && "Value not scalarized has non-vector type")((VF == 1 && "Value not scalarized has non-vector type"
) ? static_cast<void> (0) : __assert_fail ("VF == 1 && \"Value not scalarized has non-vector type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2784, __PRETTY_FUNCTION__))
;
2785 return U;
2786 }
2787
2788 // Otherwise, the value from the original loop has been vectorized and is
2789 // represented by UF vector values. Extract and return the requested scalar
2790 // value from the appropriate vector lane.
2791 return Builder.CreateExtractElement(U, Builder.getInt32(Lane));
2792}
2793
2794Value *InnerLoopVectorizer::reverseVector(Value *Vec) {
2795 assert(Vec->getType()->isVectorTy() && "Invalid type")((Vec->getType()->isVectorTy() && "Invalid type"
) ? static_cast<void> (0) : __assert_fail ("Vec->getType()->isVectorTy() && \"Invalid type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2795, __PRETTY_FUNCTION__))
;
2796 SmallVector<Constant *, 8> ShuffleMask;
2797 for (unsigned i = 0; i < VF; ++i)
2798 ShuffleMask.push_back(Builder.getInt32(VF - i - 1));
2799
2800 return Builder.CreateShuffleVector(Vec, UndefValue::get(Vec->getType()),
2801 ConstantVector::get(ShuffleMask),
2802 "reverse");
2803}
2804
2805// Try to vectorize the interleave group that \p Instr belongs to.
2806//
2807// E.g. Translate following interleaved load group (factor = 3):
2808// for (i = 0; i < N; i+=3) {
2809// R = Pic[i]; // Member of index 0
2810// G = Pic[i+1]; // Member of index 1
2811// B = Pic[i+2]; // Member of index 2
2812// ... // do something to R, G, B
2813// }
2814// To:
2815// %wide.vec = load <12 x i32> ; Read 4 tuples of R,G,B
2816// %R.vec = shuffle %wide.vec, undef, <0, 3, 6, 9> ; R elements
2817// %G.vec = shuffle %wide.vec, undef, <1, 4, 7, 10> ; G elements
2818// %B.vec = shuffle %wide.vec, undef, <2, 5, 8, 11> ; B elements
2819//
2820// Or translate following interleaved store group (factor = 3):
2821// for (i = 0; i < N; i+=3) {
2822// ... do something to R, G, B
2823// Pic[i] = R; // Member of index 0
2824// Pic[i+1] = G; // Member of index 1
2825// Pic[i+2] = B; // Member of index 2
2826// }
2827// To:
2828// %R_G.vec = shuffle %R.vec, %G.vec, <0, 1, 2, ..., 7>
2829// %B_U.vec = shuffle %B.vec, undef, <0, 1, 2, 3, u, u, u, u>
2830// %interleaved.vec = shuffle %R_G.vec, %B_U.vec,
2831// <0, 4, 8, 1, 5, 9, 2, 6, 10, 3, 7, 11> ; Interleave R,G,B elements
2832// store <12 x i32> %interleaved.vec ; Write 4 tuples of R,G,B
2833void InnerLoopVectorizer::vectorizeInterleaveGroup(Instruction *Instr) {
2834 const InterleaveGroup *Group = Legal->getInterleavedAccessGroup(Instr);
2835 assert(Group && "Fail to get an interleaved access group.")((Group && "Fail to get an interleaved access group."
) ? static_cast<void> (0) : __assert_fail ("Group && \"Fail to get an interleaved access group.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2835, __PRETTY_FUNCTION__))
;
2836
2837 // Skip if current instruction is not the insert position.
2838 if (Instr != Group->getInsertPos())
2839 return;
2840
2841 Value *Ptr = getPointerOperand(Instr);
2842
2843 // Prepare for the vector type of the interleaved load/store.
2844 Type *ScalarTy = getMemInstValueType(Instr);
2845 unsigned InterleaveFactor = Group->getFactor();
2846 Type *VecTy = VectorType::get(ScalarTy, InterleaveFactor * VF);
2847 Type *PtrTy = VecTy->getPointerTo(getMemInstAddressSpace(Instr));
2848
2849 // Prepare for the new pointers.
2850 setDebugLocFromInst(Builder, Ptr);
2851 SmallVector<Value *, 2> NewPtrs;
2852 unsigned Index = Group->getIndex(Instr);
2853
2854 // If the group is reverse, adjust the index to refer to the last vector lane
2855 // instead of the first. We adjust the index from the first vector lane,
2856 // rather than directly getting the pointer for lane VF - 1, because the
2857 // pointer operand of the interleaved access is supposed to be uniform. For
2858 // uniform instructions, we're only required to generate a value for the
2859 // first vector lane in each unroll iteration.
2860 if (Group->isReverse())
2861 Index += (VF - 1) * Group->getFactor();
2862
2863 for (unsigned Part = 0; Part < UF; Part++) {
2864 Value *NewPtr = getOrCreateScalarValue(Ptr, Part, 0);
2865
2866 // Notice current instruction could be any index. Need to adjust the address
2867 // to the member of index 0.
2868 //
2869 // E.g. a = A[i+1]; // Member of index 1 (Current instruction)
2870 // b = A[i]; // Member of index 0
2871 // Current pointer is pointed to A[i+1], adjust it to A[i].
2872 //
2873 // E.g. A[i+1] = a; // Member of index 1
2874 // A[i] = b; // Member of index 0
2875 // A[i+2] = c; // Member of index 2 (Current instruction)
2876 // Current pointer is pointed to A[i+2], adjust it to A[i].
2877 NewPtr = Builder.CreateGEP(NewPtr, Builder.getInt32(-Index));
2878
2879 // Cast to the vector pointer type.
2880 NewPtrs.push_back(Builder.CreateBitCast(NewPtr, PtrTy));
2881 }
2882
2883 setDebugLocFromInst(Builder, Instr);
2884 Value *UndefVec = UndefValue::get(VecTy);
2885
2886 // Vectorize the interleaved load group.
2887 if (isa<LoadInst>(Instr)) {
2888
2889 // For each unroll part, create a wide load for the group.
2890 SmallVector<Value *, 2> NewLoads;
2891 for (unsigned Part = 0; Part < UF; Part++) {
2892 auto *NewLoad = Builder.CreateAlignedLoad(
2893 NewPtrs[Part], Group->getAlignment(), "wide.vec");
2894 addMetadata(NewLoad, Instr);
2895 NewLoads.push_back(NewLoad);
2896 }
2897
2898 // For each member in the group, shuffle out the appropriate data from the
2899 // wide loads.
2900 for (unsigned I = 0; I < InterleaveFactor; ++I) {
2901 Instruction *Member = Group->getMember(I);
2902
2903 // Skip the gaps in the group.
2904 if (!Member)
2905 continue;
2906
2907 Constant *StrideMask = createStrideMask(Builder, I, InterleaveFactor, VF);
2908 for (unsigned Part = 0; Part < UF; Part++) {
2909 Value *StridedVec = Builder.CreateShuffleVector(
2910 NewLoads[Part], UndefVec, StrideMask, "strided.vec");
2911
2912 // If this member has different type, cast the result type.
2913 if (Member->getType() != ScalarTy) {
2914 VectorType *OtherVTy = VectorType::get(Member->getType(), VF);
2915 StridedVec = Builder.CreateBitOrPointerCast(StridedVec, OtherVTy);
2916 }
2917
2918 if (Group->isReverse())
2919 StridedVec = reverseVector(StridedVec);
2920
2921 VectorLoopValueMap.setVectorValue(Member, Part, StridedVec);
2922 }
2923 }
2924 return;
2925 }
2926
2927 // The sub vector type for current instruction.
2928 VectorType *SubVT = VectorType::get(ScalarTy, VF);
2929
2930 // Vectorize the interleaved store group.
2931 for (unsigned Part = 0; Part < UF; Part++) {
2932 // Collect the stored vector from each member.
2933 SmallVector<Value *, 4> StoredVecs;
2934 for (unsigned i = 0; i < InterleaveFactor; i++) {
2935 // Interleaved store group doesn't allow a gap, so each index has a member
2936 Instruction *Member = Group->getMember(i);
2937 assert(Member && "Fail to get a member from an interleaved store group")((Member && "Fail to get a member from an interleaved store group"
) ? static_cast<void> (0) : __assert_fail ("Member && \"Fail to get a member from an interleaved store group\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2937, __PRETTY_FUNCTION__))
;
2938
2939 Value *StoredVec = getOrCreateVectorValue(
2940 cast<StoreInst>(Member)->getValueOperand(), Part);
2941 if (Group->isReverse())
2942 StoredVec = reverseVector(StoredVec);
2943
2944 // If this member has different type, cast it to an unified type.
2945 if (StoredVec->getType() != SubVT)
2946 StoredVec = Builder.CreateBitOrPointerCast(StoredVec, SubVT);
2947
2948 StoredVecs.push_back(StoredVec);
2949 }
2950
2951 // Concatenate all vectors into a wide vector.
2952 Value *WideVec = concatenateVectors(Builder, StoredVecs);
2953
2954 // Interleave the elements in the wide vector.
2955 Constant *IMask = createInterleaveMask(Builder, VF, InterleaveFactor);
2956 Value *IVec = Builder.CreateShuffleVector(WideVec, UndefVec, IMask,
2957 "interleaved.vec");
2958
2959 Instruction *NewStoreInstr =
2960 Builder.CreateAlignedStore(IVec, NewPtrs[Part], Group->getAlignment());
2961 addMetadata(NewStoreInstr, Instr);
2962 }
2963}
2964
2965void InnerLoopVectorizer::vectorizeMemoryInstruction(Instruction *Instr) {
2966 // Attempt to issue a wide load.
2967 LoadInst *LI = dyn_cast<LoadInst>(Instr);
2968 StoreInst *SI = dyn_cast<StoreInst>(Instr);
2969
2970 assert((LI || SI) && "Invalid Load/Store instruction")(((LI || SI) && "Invalid Load/Store instruction") ? static_cast
<void> (0) : __assert_fail ("(LI || SI) && \"Invalid Load/Store instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2970, __PRETTY_FUNCTION__))
;
2971
2972 LoopVectorizationCostModel::InstWidening Decision =
2973 Cost->getWideningDecision(Instr, VF);
2974 assert(Decision != LoopVectorizationCostModel::CM_Unknown &&((Decision != LoopVectorizationCostModel::CM_Unknown &&
"CM decision should be taken at this point") ? static_cast<
void> (0) : __assert_fail ("Decision != LoopVectorizationCostModel::CM_Unknown && \"CM decision should be taken at this point\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2975, __PRETTY_FUNCTION__))
2975 "CM decision should be taken at this point")((Decision != LoopVectorizationCostModel::CM_Unknown &&
"CM decision should be taken at this point") ? static_cast<
void> (0) : __assert_fail ("Decision != LoopVectorizationCostModel::CM_Unknown && \"CM decision should be taken at this point\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2975, __PRETTY_FUNCTION__))
;
2976 if (Decision == LoopVectorizationCostModel::CM_Interleave)
2977 return vectorizeInterleaveGroup(Instr);
2978
2979 Type *ScalarDataTy = getMemInstValueType(Instr);
2980 Type *DataTy = VectorType::get(ScalarDataTy, VF);
2981 Value *Ptr = getPointerOperand(Instr);
2982 unsigned Alignment = getMemInstAlignment(Instr);
2983 // An alignment of 0 means target abi alignment. We need to use the scalar's
2984 // target abi alignment in such a case.
2985 const DataLayout &DL = Instr->getModule()->getDataLayout();
2986 if (!Alignment)
2987 Alignment = DL.getABITypeAlignment(ScalarDataTy);
2988 unsigned AddressSpace = getMemInstAddressSpace(Instr);
2989
2990 // Scalarize the memory instruction if necessary.
2991 if (Decision == LoopVectorizationCostModel::CM_Scalarize)
2992 return scalarizeInstruction(Instr, Legal->isScalarWithPredication(Instr));
2993
2994 // Determine if the pointer operand of the access is either consecutive or
2995 // reverse consecutive.
2996 int ConsecutiveStride = Legal->isConsecutivePtr(Ptr);
2997 bool Reverse = ConsecutiveStride < 0;
2998 bool CreateGatherScatter =
2999 (Decision == LoopVectorizationCostModel::CM_GatherScatter);
3000
3001 // Either Ptr feeds a vector load/store, or a vector GEP should feed a vector
3002 // gather/scatter. Otherwise Decision should have been to Scalarize.
3003 assert((ConsecutiveStride || CreateGatherScatter) &&(((ConsecutiveStride || CreateGatherScatter) && "The instruction should be scalarized"
) ? static_cast<void> (0) : __assert_fail ("(ConsecutiveStride || CreateGatherScatter) && \"The instruction should be scalarized\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3004, __PRETTY_FUNCTION__))
3004 "The instruction should be scalarized")(((ConsecutiveStride || CreateGatherScatter) && "The instruction should be scalarized"
) ? static_cast<void> (0) : __assert_fail ("(ConsecutiveStride || CreateGatherScatter) && \"The instruction should be scalarized\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3004, __PRETTY_FUNCTION__))
;
3005
3006 // Handle consecutive loads/stores.
3007 if (ConsecutiveStride)
3008 Ptr = getOrCreateScalarValue(Ptr, 0, 0);
3009
3010 VectorParts Mask = createBlockInMask(Instr->getParent());
3011 // Handle Stores:
3012 if (SI) {
3013 assert(!Legal->isUniform(SI->getPointerOperand()) &&((!Legal->isUniform(SI->getPointerOperand()) &&
"We do not allow storing to uniform addresses") ? static_cast
<void> (0) : __assert_fail ("!Legal->isUniform(SI->getPointerOperand()) && \"We do not allow storing to uniform addresses\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3014, __PRETTY_FUNCTION__))
3014 "We do not allow storing to uniform addresses")((!Legal->isUniform(SI->getPointerOperand()) &&
"We do not allow storing to uniform addresses") ? static_cast
<void> (0) : __assert_fail ("!Legal->isUniform(SI->getPointerOperand()) && \"We do not allow storing to uniform addresses\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3014, __PRETTY_FUNCTION__))
;
3015 setDebugLocFromInst(Builder, SI);
3016
3017 for (unsigned Part = 0; Part < UF; ++Part) {
3018 Instruction *NewSI = nullptr;
3019 Value *StoredVal = getOrCreateVectorValue(SI->getValueOperand(), Part);
3020 if (CreateGatherScatter) {
3021 Value *MaskPart = Legal->isMaskRequired(SI) ? Mask[Part] : nullptr;
3022 Value *VectorGep = getOrCreateVectorValue(Ptr, Part);
3023 NewSI = Builder.CreateMaskedScatter(StoredVal, VectorGep, Alignment,
3024 MaskPart);
3025 } else {
3026 // Calculate the pointer for the specific unroll-part.
3027 Value *PartPtr =
3028 Builder.CreateGEP(nullptr, Ptr, Builder.getInt32(Part * VF));
3029
3030 if (Reverse) {
3031 // If we store to reverse consecutive memory locations, then we need
3032 // to reverse the order of elements in the stored value.
3033 StoredVal = reverseVector(StoredVal);
3034 // We don't want to update the value in the map as it might be used in
3035 // another expression. So don't call resetVectorValue(StoredVal).
3036
3037 // If the address is consecutive but reversed, then the
3038 // wide store needs to start at the last vector element.
3039 PartPtr =
3040 Builder.CreateGEP(nullptr, Ptr, Builder.getInt32(-Part * VF));
3041 PartPtr =
3042 Builder.CreateGEP(nullptr, PartPtr, Builder.getInt32(1 - VF));
3043 Mask[Part] = reverseVector(Mask[Part]);
3044 }
3045
3046 Value *VecPtr =
3047 Builder.CreateBitCast(PartPtr, DataTy->getPointerTo(AddressSpace));
3048
3049 if (Legal->isMaskRequired(SI))
3050 NewSI = Builder.CreateMaskedStore(StoredVal, VecPtr, Alignment,
3051 Mask[Part]);
3052 else
3053 NewSI = Builder.CreateAlignedStore(StoredVal, VecPtr, Alignment);
3054 }
3055 addMetadata(NewSI, SI);
3056 }
3057 return;
3058 }
3059
3060 // Handle loads.
3061 assert(LI && "Must have a load instruction")((LI && "Must have a load instruction") ? static_cast
<void> (0) : __assert_fail ("LI && \"Must have a load instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3061, __PRETTY_FUNCTION__))
;
3062 setDebugLocFromInst(Builder, LI);
3063 for (unsigned Part = 0; Part < UF; ++Part) {
3064 Value *NewLI;
3065 if (CreateGatherScatter) {
3066 Value *MaskPart = Legal->isMaskRequired(LI) ? Mask[Part] : nullptr;
3067 Value *VectorGep = getOrCreateVectorValue(Ptr, Part);
3068 NewLI = Builder.CreateMaskedGather(VectorGep, Alignment, MaskPart,
3069 nullptr, "wide.masked.gather");
3070 addMetadata(NewLI, LI);
3071 } else {
3072 // Calculate the pointer for the specific unroll-part.
3073 Value *PartPtr =
3074 Builder.CreateGEP(nullptr, Ptr, Builder.getInt32(Part * VF));
3075
3076 if (Reverse) {
3077 // If the address is consecutive but reversed, then the
3078 // wide load needs to start at the last vector element.
3079 PartPtr = Builder.CreateGEP(nullptr, Ptr, Builder.getInt32(-Part * VF));
3080 PartPtr = Builder.CreateGEP(nullptr, PartPtr, Builder.getInt32(1 - VF));
3081 Mask[Part] = reverseVector(Mask[Part]);
3082 }
3083
3084 Value *VecPtr =
3085 Builder.CreateBitCast(PartPtr, DataTy->getPointerTo(AddressSpace));
3086 if (Legal->isMaskRequired(LI))
3087 NewLI = Builder.CreateMaskedLoad(VecPtr, Alignment, Mask[Part],
3088 UndefValue::get(DataTy),
3089 "wide.masked.load");
3090 else
3091 NewLI = Builder.CreateAlignedLoad(VecPtr, Alignment, "wide.load");
3092
3093 // Add metadata to the load, but setVectorValue to the reverse shuffle.
3094 addMetadata(NewLI, LI);
3095 if (Reverse)
3096 NewLI = reverseVector(NewLI);
3097 }
3098 VectorLoopValueMap.setVectorValue(Instr, Part, NewLI);
3099 }
3100}
3101
3102void InnerLoopVectorizer::scalarizeInstruction(Instruction *Instr,
3103 bool IfPredicateInstr) {
3104 assert(!Instr->getType()->isAggregateType() && "Can't handle vectors")((!Instr->getType()->isAggregateType() && "Can't handle vectors"
) ? static_cast<void> (0) : __assert_fail ("!Instr->getType()->isAggregateType() && \"Can't handle vectors\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3104, __PRETTY_FUNCTION__))
;
3105 DEBUG(dbgs() << "LV: Scalarizing"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Scalarizing" <<
(IfPredicateInstr ? " and predicating:" : ":") << *Instr
<< '\n'; } } while (false)
3106 << (IfPredicateInstr ? " and predicating:" : ":") << *Instrdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Scalarizing" <<
(IfPredicateInstr ? " and predicating:" : ":") << *Instr
<< '\n'; } } while (false)
3107 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Scalarizing" <<
(IfPredicateInstr ? " and predicating:" : ":") << *Instr
<< '\n'; } } while (false)
;
3108 // Holds vector parameters or scalars, in case of uniform vals.
3109 SmallVector<VectorParts, 4> Params;
3110
3111 setDebugLocFromInst(Builder, Instr);
3112
3113 // Does this instruction return a value ?
3114 bool IsVoidRetTy = Instr->getType()->isVoidTy();
3115
3116 VectorParts Cond;
3117 if (IfPredicateInstr)
3118 Cond = createBlockInMask(Instr->getParent());
3119
3120 // Determine the number of scalars we need to generate for each unroll
3121 // iteration. If the instruction is uniform, we only need to generate the
3122 // first lane. Otherwise, we generate all VF values.
3123 unsigned Lanes = Cost->isUniformAfterVectorization(Instr, VF) ? 1 : VF;
3124
3125 // For each vector unroll 'part':
3126 for (unsigned Part = 0; Part < UF; ++Part) {
3127 // For each scalar that we create:
3128 for (unsigned Lane = 0; Lane < Lanes; ++Lane) {
3129
3130 // Start if-block.
3131 Value *Cmp = nullptr;
3132 if (IfPredicateInstr) {
3133 Cmp = Cond[Part];
3134 if (Cmp->getType()->isVectorTy())
3135 Cmp = Builder.CreateExtractElement(Cmp, Builder.getInt32(Lane));
3136 Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Cmp,
3137 ConstantInt::get(Cmp->getType(), 1));
3138 }
3139
3140 Instruction *Cloned = Instr->clone();
3141 if (!IsVoidRetTy)
3142 Cloned->setName(Instr->getName() + ".cloned");
3143
3144 // Replace the operands of the cloned instructions with their scalar
3145 // equivalents in the new loop.
3146 for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) {
3147 auto *NewOp = getOrCreateScalarValue(Instr->getOperand(op), Part, Lane);
3148 Cloned->setOperand(op, NewOp);
3149 }
3150 addNewMetadata(Cloned, Instr);
3151
3152 // Place the cloned scalar in the new loop.
3153 Builder.Insert(Cloned);
3154
3155 // Add the cloned scalar to the scalar map entry.
3156 VectorLoopValueMap.setScalarValue(Instr, Part, Lane, Cloned);
3157
3158 // If we just cloned a new assumption, add it the assumption cache.
3159 if (auto *II = dyn_cast<IntrinsicInst>(Cloned))
3160 if (II->getIntrinsicID() == Intrinsic::assume)
3161 AC->registerAssumption(II);
3162
3163 // End if-block.
3164 if (IfPredicateInstr)
3165 PredicatedInstructions.push_back(std::make_pair(Cloned, Cmp));
3166 }
3167 }
3168}
3169
3170PHINode *InnerLoopVectorizer::createInductionVariable(Loop *L, Value *Start,
3171 Value *End, Value *Step,
3172 Instruction *DL) {
3173 BasicBlock *Header = L->getHeader();
3174 BasicBlock *Latch = L->getLoopLatch();
3175 // As we're just creating this loop, it's possible no latch exists
3176 // yet. If so, use the header as this will be a single block loop.
3177 if (!Latch)
3178 Latch = Header;
3179
3180 IRBuilder<> Builder(&*Header->getFirstInsertionPt());
3181 Instruction *OldInst = getDebugLocFromInstOrOperands(OldInduction);
3182 setDebugLocFromInst(Builder, OldInst);
3183 auto *Induction = Builder.CreatePHI(Start->getType(), 2, "index");
3184
3185 Builder.SetInsertPoint(Latch->getTerminator());
3186 setDebugLocFromInst(Builder, OldInst);
3187
3188 // Create i+1 and fill the PHINode.
3189 Value *Next = Builder.CreateAdd(Induction, Step, "index.next");
3190 Induction->addIncoming(Start, L->getLoopPreheader());
3191 Induction->addIncoming(Next, Latch);
3192 // Create the compare.
3193 Value *ICmp = Builder.CreateICmpEQ(Next, End);
3194 Builder.CreateCondBr(ICmp, L->getExitBlock(), Header);
3195
3196 // Now we have two terminators. Remove the old one from the block.
3197 Latch->getTerminator()->eraseFromParent();
3198
3199 return Induction;
3200}
3201
3202Value *InnerLoopVectorizer::getOrCreateTripCount(Loop *L) {
3203 if (TripCount)
3204 return TripCount;
3205
3206 IRBuilder<> Builder(L->getLoopPreheader()->getTerminator());
3207 // Find the loop boundaries.
3208 ScalarEvolution *SE = PSE.getSE();
3209 const SCEV *BackedgeTakenCount = PSE.getBackedgeTakenCount();
3210 assert(BackedgeTakenCount != SE->getCouldNotCompute() &&((BackedgeTakenCount != SE->getCouldNotCompute() &&
"Invalid loop count") ? static_cast<void> (0) : __assert_fail
("BackedgeTakenCount != SE->getCouldNotCompute() && \"Invalid loop count\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3211, __PRETTY_FUNCTION__))
3211 "Invalid loop count")((BackedgeTakenCount != SE->getCouldNotCompute() &&
"Invalid loop count") ? static_cast<void> (0) : __assert_fail
("BackedgeTakenCount != SE->getCouldNotCompute() && \"Invalid loop count\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3211, __PRETTY_FUNCTION__))
;
3212
3213 Type *IdxTy = Legal->getWidestInductionType();
3214
3215 // The exit count might have the type of i64 while the phi is i32. This can
3216 // happen if we have an induction variable that is sign extended before the
3217 // compare. The only way that we get a backedge taken count is that the
3218 // induction variable was signed and as such will not overflow. In such a case
3219 // truncation is legal.
3220 if (BackedgeTakenCount->getType()->getPrimitiveSizeInBits() >
3221 IdxTy->getPrimitiveSizeInBits())
3222 BackedgeTakenCount = SE->getTruncateOrNoop(BackedgeTakenCount, IdxTy);
3223 BackedgeTakenCount = SE->getNoopOrZeroExtend(BackedgeTakenCount, IdxTy);
3224
3225 // Get the total trip count from the count by adding 1.
3226 const SCEV *ExitCount = SE->getAddExpr(
3227 BackedgeTakenCount, SE->getOne(BackedgeTakenCount->getType()));
3228
3229 const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
3230
3231 // Expand the trip count and place the new instructions in the preheader.
3232 // Notice that the pre-header does not change, only the loop body.
3233 SCEVExpander Exp(*SE, DL, "induction");
3234
3235 // Count holds the overall loop count (N).
3236 TripCount = Exp.expandCodeFor(ExitCount, ExitCount->getType(),
3237 L->getLoopPreheader()->getTerminator());
3238
3239 if (TripCount->getType()->isPointerTy())
3240 TripCount =
3241 CastInst::CreatePointerCast(TripCount, IdxTy, "exitcount.ptrcnt.to.int",
3242 L->getLoopPreheader()->getTerminator());
3243
3244 return TripCount;
3245}
3246
3247Value *InnerLoopVectorizer::getOrCreateVectorTripCount(Loop *L) {
3248 if (VectorTripCount)
3249 return VectorTripCount;
3250
3251 Value *TC = getOrCreateTripCount(L);
3252 IRBuilder<> Builder(L->getLoopPreheader()->getTerminator());
3253
3254 // Now we need to generate the expression for the part of the loop that the
3255 // vectorized body will execute. This is equal to N - (N % Step) if scalar
3256 // iterations are not required for correctness, or N - Step, otherwise. Step
3257 // is equal to the vectorization factor (number of SIMD elements) times the
3258 // unroll factor (number of SIMD instructions).
3259 Constant *Step = ConstantInt::get(TC->getType(), VF * UF);
3260 Value *R = Builder.CreateURem(TC, Step, "n.mod.vf");
3261
3262 // If there is a non-reversed interleaved group that may speculatively access
3263 // memory out-of-bounds, we need to ensure that there will be at least one
3264 // iteration of the scalar epilogue loop. Thus, if the step evenly divides
3265 // the trip count, we set the remainder to be equal to the step. If the step
3266 // does not evenly divide the trip count, no adjustment is necessary since
3267 // there will already be scalar iterations. Note that the minimum iterations
3268 // check ensures that N >= Step.
3269 if (VF > 1 && Legal->requiresScalarEpilogue()) {
3270 auto *IsZero = Builder.CreateICmpEQ(R, ConstantInt::get(R->getType(), 0));
3271 R = Builder.CreateSelect(IsZero, Step, R);
3272 }
3273
3274 VectorTripCount = Builder.CreateSub(TC, R, "n.vec");
3275
3276 return VectorTripCount;
3277}
3278
3279void InnerLoopVectorizer::emitMinimumIterationCountCheck(Loop *L,
3280 BasicBlock *Bypass) {
3281 Value *Count = getOrCreateTripCount(L);
3282 BasicBlock *BB = L->getLoopPreheader();
3283 IRBuilder<> Builder(BB->getTerminator());
3284
3285 // Generate code to check that the loop's trip count that we computed by
3286 // adding one to the backedge-taken count will not overflow.
3287 Value *CheckMinIters = Builder.CreateICmpULT(
3288 Count, ConstantInt::get(Count->getType(), VF * UF), "min.iters.check");
3289
3290 BasicBlock *NewBB =
3291 BB->splitBasicBlock(BB->getTerminator(), "min.iters.checked");
3292 // Update dominator tree immediately if the generated block is a
3293 // LoopBypassBlock because SCEV expansions to generate loop bypass
3294 // checks may query it before the current function is finished.
3295 DT->addNewBlock(NewBB, BB);
3296 if (L->getParentLoop())
3297 L->getParentLoop()->addBasicBlockToLoop(NewBB, *LI);
3298 ReplaceInstWithInst(BB->getTerminator(),
3299 BranchInst::Create(Bypass, NewBB, CheckMinIters));
3300 LoopBypassBlocks.push_back(BB);
3301}
3302
3303void InnerLoopVectorizer::emitVectorLoopEnteredCheck(Loop *L,
3304 BasicBlock *Bypass) {
3305 Value *TC = getOrCreateVectorTripCount(L);
3306 BasicBlock *BB = L->getLoopPreheader();
3307 IRBuilder<> Builder(BB->getTerminator());
3308
3309 // Now, compare the new count to zero. If it is zero skip the vector loop and
3310 // jump to the scalar loop.
3311 Value *Cmp = Builder.CreateICmpEQ(TC, Constant::getNullValue(TC->getType()),
3312 "cmp.zero");
3313
3314 // Generate code to check that the loop's trip count that we computed by
3315 // adding one to the backedge-taken count will not overflow.
3316 BasicBlock *NewBB = BB->splitBasicBlock(BB->getTerminator(), "vector.ph");
3317 // Update dominator tree immediately if the generated block is a
3318 // LoopBypassBlock because SCEV expansions to generate loop bypass
3319 // checks may query it before the current function is finished.
3320 DT->addNewBlock(NewBB, BB);
3321 if (L->getParentLoop())
3322 L->getParentLoop()->addBasicBlockToLoop(NewBB, *LI);
3323 ReplaceInstWithInst(BB->getTerminator(),
3324 BranchInst::Create(Bypass, NewBB, Cmp));
3325 LoopBypassBlocks.push_back(BB);
3326}
3327
3328void InnerLoopVectorizer::emitSCEVChecks(Loop *L, BasicBlock *Bypass) {
3329 BasicBlock *BB = L->getLoopPreheader();
3330
3331 // Generate the code to check that the SCEV assumptions that we made.
3332 // We want the new basic block to start at the first instruction in a
3333 // sequence of instructions that form a check.
3334 SCEVExpander Exp(*PSE.getSE(), Bypass->getModule()->getDataLayout(),
3335 "scev.check");
3336 Value *SCEVCheck =
3337 Exp.expandCodeForPredicate(&PSE.getUnionPredicate(), BB->getTerminator());
3338
3339 if (auto *C = dyn_cast<ConstantInt>(SCEVCheck))
3340 if (C->isZero())
3341 return;
3342
3343 // Create a new block containing the stride check.
3344 BB->setName("vector.scevcheck");
3345 auto *NewBB = BB->splitBasicBlock(BB->getTerminator(), "vector.ph");
3346 // Update dominator tree immediately if the generated block is a
3347 // LoopBypassBlock because SCEV expansions to generate loop bypass
3348 // checks may query it before the current function is finished.
3349 DT->addNewBlock(NewBB, BB);
3350 if (L->getParentLoop())
3351 L->getParentLoop()->addBasicBlockToLoop(NewBB, *LI);
3352 ReplaceInstWithInst(BB->getTerminator(),
3353 BranchInst::Create(Bypass, NewBB, SCEVCheck));
3354 LoopBypassBlocks.push_back(BB);
3355 AddedSafetyChecks = true;
3356}
3357
3358void InnerLoopVectorizer::emitMemRuntimeChecks(Loop *L, BasicBlock *Bypass) {
3359 BasicBlock *BB = L->getLoopPreheader();
3360
3361 // Generate the code that checks in runtime if arrays overlap. We put the
3362 // checks into a separate block to make the more common case of few elements
3363 // faster.
3364 Instruction *FirstCheckInst;
3365 Instruction *MemRuntimeCheck;
3366 std::tie(FirstCheckInst, MemRuntimeCheck) =
3367 Legal->getLAI()->addRuntimeChecks(BB->getTerminator());
3368 if (!MemRuntimeCheck)
3369 return;
3370
3371 // Create a new block containing the memory check.
3372 BB->setName("vector.memcheck");
3373 auto *NewBB = BB->splitBasicBlock(BB->getTerminator(), "vector.ph");
3374 // Update dominator tree immediately if the generated block is a
3375 // LoopBypassBlock because SCEV expansions to generate loop bypass
3376 // checks may query it before the current function is finished.
3377 DT->addNewBlock(NewBB, BB);
3378 if (L->getParentLoop())
3379 L->getParentLoop()->addBasicBlockToLoop(NewBB, *LI);
3380 ReplaceInstWithInst(BB->getTerminator(),
3381 BranchInst::Create(Bypass, NewBB, MemRuntimeCheck));
3382 LoopBypassBlocks.push_back(BB);
3383 AddedSafetyChecks = true;
3384
3385 // We currently don't use LoopVersioning for the actual loop cloning but we
3386 // still use it to add the noalias metadata.
3387 LVer = llvm::make_unique<LoopVersioning>(*Legal->getLAI(), OrigLoop, LI, DT,
3388 PSE.getSE());
3389 LVer->prepareNoAliasMetadata();
3390}
3391
3392void InnerLoopVectorizer::createVectorizedLoopSkeleton() {
3393 /*
3394 In this function we generate a new loop. The new loop will contain
3395 the vectorized instructions while the old loop will continue to run the
3396 scalar remainder.
3397
3398 [ ] <-- loop iteration number check.
3399 / |
3400 / v
3401 | [ ] <-- vector loop bypass (may consist of multiple blocks).
3402 | / |
3403 | / v
3404 || [ ] <-- vector pre header.
3405 |/ |
3406 | v
3407 | [ ] \
3408 | [ ]_| <-- vector loop.
3409 | |
3410 | v
3411 | -[ ] <--- middle-block.
3412 | / |
3413 | / v
3414 -|- >[ ] <--- new preheader.
3415 | |
3416 | v
3417 | [ ] \
3418 | [ ]_| <-- old scalar loop to handle remainder.
3419 \ |
3420 \ v
3421 >[ ] <-- exit block.
3422 ...
3423 */
3424
3425 BasicBlock *OldBasicBlock = OrigLoop->getHeader();
3426 BasicBlock *VectorPH = OrigLoop->getLoopPreheader();
3427 BasicBlock *ExitBlock = OrigLoop->getExitBlock();
3428 assert(VectorPH && "Invalid loop structure")((VectorPH && "Invalid loop structure") ? static_cast
<void> (0) : __assert_fail ("VectorPH && \"Invalid loop structure\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3428, __PRETTY_FUNCTION__))
;
3429 assert(ExitBlock && "Must have an exit block")((ExitBlock && "Must have an exit block") ? static_cast
<void> (0) : __assert_fail ("ExitBlock && \"Must have an exit block\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3429, __PRETTY_FUNCTION__))
;
3430
3431 // Some loops have a single integer induction variable, while other loops
3432 // don't. One example is c++ iterators that often have multiple pointer
3433 // induction variables. In the code below we also support a case where we
3434 // don't have a single induction variable.
3435 //
3436 // We try to obtain an induction variable from the original loop as hard
3437 // as possible. However if we don't find one that:
3438 // - is an integer
3439 // - counts from zero, stepping by one
3440 // - is the size of the widest induction variable type
3441 // then we create a new one.
3442 OldInduction = Legal->getPrimaryInduction();
3443 Type *IdxTy = Legal->getWidestInductionType();
3444
3445 // Split the single block loop into the two loop structure described above.
3446 BasicBlock *VecBody =
3447 VectorPH->splitBasicBlock(VectorPH->getTerminator(), "vector.body");
3448 BasicBlock *MiddleBlock =
3449 VecBody->splitBasicBlock(VecBody->getTerminator(), "middle.block");
3450 BasicBlock *ScalarPH =
3451 MiddleBlock->splitBasicBlock(MiddleBlock->getTerminator(), "scalar.ph");
3452
3453 // Create and register the new vector loop.
3454 Loop *Lp = new Loop();
3455 Loop *ParentLoop = OrigLoop->getParentLoop();
3456
3457 // Insert the new loop into the loop nest and register the new basic blocks
3458 // before calling any utilities such as SCEV that require valid LoopInfo.
3459 if (ParentLoop) {
3460 ParentLoop->addChildLoop(Lp);
3461 ParentLoop->addBasicBlockToLoop(ScalarPH, *LI);
3462 ParentLoop->addBasicBlockToLoop(MiddleBlock, *LI);
3463 } else {
3464 LI->addTopLevelLoop(Lp);
3465 }
3466 Lp->addBasicBlockToLoop(VecBody, *LI);
3467
3468 // Find the loop boundaries.
3469 Value *Count = getOrCreateTripCount(Lp);
3470
3471 Value *StartIdx = ConstantInt::get(IdxTy, 0);
3472
3473 // We need to test whether the backedge-taken count is uint##_max. Adding one
3474 // to it will cause overflow and an incorrect loop trip count in the vector
3475 // body. In case of overflow we want to directly jump to the scalar remainder
3476 // loop.
3477 emitMinimumIterationCountCheck(Lp, ScalarPH);
3478 // Now, compare the new count to zero. If it is zero skip the vector loop and
3479 // jump to the scalar loop.
3480 emitVectorLoopEnteredCheck(Lp, ScalarPH);
3481 // Generate the code to check any assumptions that we've made for SCEV
3482 // expressions.
3483 emitSCEVChecks(Lp, ScalarPH);
3484
3485 // Generate the code that checks in runtime if arrays overlap. We put the
3486 // checks into a separate block to make the more common case of few elements
3487 // faster.
3488 emitMemRuntimeChecks(Lp, ScalarPH);
3489
3490 // Generate the induction variable.
3491 // The loop step is equal to the vectorization factor (num of SIMD elements)
3492 // times the unroll factor (num of SIMD instructions).
3493 Value *CountRoundDown = getOrCreateVectorTripCount(Lp);
3494 Constant *Step = ConstantInt::get(IdxTy, VF * UF);
3495 Induction =
3496 createInductionVariable(Lp, StartIdx, CountRoundDown, Step,
3497 getDebugLocFromInstOrOperands(OldInduction));
3498
3499 // We are going to resume the execution of the scalar loop.
3500 // Go over all of the induction variables that we found and fix the
3501 // PHIs that are left in the scalar version of the loop.
3502 // The starting values of PHI nodes depend on the counter of the last
3503 // iteration in the vectorized loop.
3504 // If we come from a bypass edge then we need to start from the original
3505 // start value.
3506
3507 // This variable saves the new starting index for the scalar loop. It is used
3508 // to test if there are any tail iterations left once the vector loop has
3509 // completed.
3510 LoopVectorizationLegality::InductionList *List = Legal->getInductionVars();
3511 for (auto &InductionEntry : *List) {
3512 PHINode *OrigPhi = InductionEntry.first;
3513 InductionDescriptor II = InductionEntry.second;
3514
3515 // Create phi nodes to merge from the backedge-taken check block.
3516 PHINode *BCResumeVal = PHINode::Create(
3517 OrigPhi->getType(), 3, "bc.resume.val", ScalarPH->getTerminator());
3518 Value *&EndValue = IVEndValues[OrigPhi];
3519 if (OrigPhi == OldInduction) {
3520 // We know what the end value is.
3521 EndValue = CountRoundDown;
3522 } else {
3523 IRBuilder<> B(LoopBypassBlocks.back()->getTerminator());
3524 Type *StepType = II.getStep()->getType();
3525 Instruction::CastOps CastOp =
3526 CastInst::getCastOpcode(CountRoundDown, true, StepType, true);
3527 Value *CRD = B.CreateCast(CastOp, CountRoundDown, StepType, "cast.crd");
3528 const DataLayout &DL = OrigLoop->getHeader()->getModule()->getDataLayout();
3529 EndValue = II.transform(B, CRD, PSE.getSE(), DL);
3530 EndValue->setName("ind.end");
3531 }
3532
3533 // The new PHI merges the original incoming value, in case of a bypass,
3534 // or the value at the end of the vectorized loop.
3535 BCResumeVal->addIncoming(EndValue, MiddleBlock);
3536
3537 // Fix the scalar body counter (PHI node).
3538 unsigned BlockIdx = OrigPhi->getBasicBlockIndex(ScalarPH);
3539
3540 // The old induction's phi node in the scalar body needs the truncated
3541 // value.
3542 for (BasicBlock *BB : LoopBypassBlocks)
3543 BCResumeVal->addIncoming(II.getStartValue(), BB);
3544 OrigPhi->setIncomingValue(BlockIdx, BCResumeVal);
3545 }
3546
3547 // Add a check in the middle block to see if we have completed
3548 // all of the iterations in the first vector loop.
3549 // If (N - N%VF) == N, then we *don't* need to run the remainder.
3550 Value *CmpN =
3551 CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ, Count,
3552 CountRoundDown, "cmp.n", MiddleBlock->getTerminator());
3553 ReplaceInstWithInst(MiddleBlock->getTerminator(),
3554 BranchInst::Create(ExitBlock, ScalarPH, CmpN));
3555
3556 // Get ready to start creating new instructions into the vectorized body.
3557 Builder.SetInsertPoint(&*VecBody->getFirstInsertionPt());
3558
3559 // Save the state.
3560 LoopVectorPreHeader = Lp->getLoopPreheader();
3561 LoopScalarPreHeader = ScalarPH;
3562 LoopMiddleBlock = MiddleBlock;
3563 LoopExitBlock = ExitBlock;
3564 LoopVectorBody = VecBody;
3565 LoopScalarBody = OldBasicBlock;
3566
3567 // Keep all loop hints from the original loop on the vector loop (we'll
3568 // replace the vectorizer-specific hints below).
3569 if (MDNode *LID = OrigLoop->getLoopID())
3570 Lp->setLoopID(LID);
3571
3572 LoopVectorizeHints Hints(Lp, true, *ORE);
3573 Hints.setAlreadyVectorized();
3574}
3575
3576// Fix up external users of the induction variable. At this point, we are
3577// in LCSSA form, with all external PHIs that use the IV having one input value,
3578// coming from the remainder loop. We need those PHIs to also have a correct
3579// value for the IV when arriving directly from the middle block.
3580void InnerLoopVectorizer::fixupIVUsers(PHINode *OrigPhi,
3581 const InductionDescriptor &II,
3582 Value *CountRoundDown, Value *EndValue,
3583 BasicBlock *MiddleBlock) {
3584 // There are two kinds of external IV usages - those that use the value
3585 // computed in the last iteration (the PHI) and those that use the penultimate
3586 // value (the value that feeds into the phi from the loop latch).
3587 // We allow both, but they, obviously, have different values.
3588
3589 assert(OrigLoop->getExitBlock() && "Expected a single exit block")((OrigLoop->getExitBlock() && "Expected a single exit block"
) ? static_cast<void> (0) : __assert_fail ("OrigLoop->getExitBlock() && \"Expected a single exit block\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3589, __PRETTY_FUNCTION__))
;
3590
3591 DenseMap<Value *, Value *> MissingVals;
3592
3593 // An external user of the last iteration's value should see the value that
3594 // the remainder loop uses to initialize its own IV.
3595 Value *PostInc = OrigPhi->getIncomingValueForBlock(OrigLoop->getLoopLatch());
3596 for (User *U : PostInc->users()) {
3597 Instruction *UI = cast<Instruction>(U);
3598 if (!OrigLoop->contains(UI)) {
3599 assert(isa<PHINode>(UI) && "Expected LCSSA form")((isa<PHINode>(UI) && "Expected LCSSA form") ? static_cast
<void> (0) : __assert_fail ("isa<PHINode>(UI) && \"Expected LCSSA form\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3599, __PRETTY_FUNCTION__))
;
3600 MissingVals[UI] = EndValue;
3601 }
3602 }
3603
3604 // An external user of the penultimate value need to see EndValue - Step.
3605 // The simplest way to get this is to recompute it from the constituent SCEVs,
3606 // that is Start + (Step * (CRD - 1)).
3607 for (User *U : OrigPhi->users()) {
3608 auto *UI = cast<Instruction>(U);
3609 if (!OrigLoop->contains(UI)) {
3610 const DataLayout &DL =
3611 OrigLoop->getHeader()->getModule()->getDataLayout();
3612 assert(isa<PHINode>(UI) && "Expected LCSSA form")((isa<PHINode>(UI) && "Expected LCSSA form") ? static_cast
<void> (0) : __assert_fail ("isa<PHINode>(UI) && \"Expected LCSSA form\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3612, __PRETTY_FUNCTION__))
;
3613
3614 IRBuilder<> B(MiddleBlock->getTerminator());
3615 Value *CountMinusOne = B.CreateSub(
3616 CountRoundDown, ConstantInt::get(CountRoundDown->getType(), 1));
3617 Value *CMO =
3618 !II.getStep()->getType()->isIntegerTy()
3619 ? B.CreateCast(Instruction::SIToFP, CountMinusOne,
3620 II.getStep()->getType())
3621 : B.CreateSExtOrTrunc(CountMinusOne, II.getStep()->getType());
3622 CMO->setName("cast.cmo");
3623 Value *Escape = II.transform(B, CMO, PSE.getSE(), DL);
3624 Escape->setName("ind.escape");
3625 MissingVals[UI] = Escape;
3626 }
3627 }
3628
3629 for (auto &I : MissingVals) {
3630 PHINode *PHI = cast<PHINode>(I.first);
3631 // One corner case we have to handle is two IVs "chasing" each-other,
3632 // that is %IV2 = phi [...], [ %IV1, %latch ]
3633 // In this case, if IV1 has an external use, we need to avoid adding both
3634 // "last value of IV1" and "penultimate value of IV2". So, verify that we
3635 // don't already have an incoming value for the middle block.
3636 if (PHI->getBasicBlockIndex(MiddleBlock) == -1)
3637 PHI->addIncoming(I.second, MiddleBlock);
3638 }
3639}
3640
3641namespace {
3642struct CSEDenseMapInfo {
3643 static bool canHandle(const Instruction *I) {
3644 return isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||
3645 isa<ShuffleVectorInst>(I) || isa<GetElementPtrInst>(I);
3646 }
3647 static inline Instruction *getEmptyKey() {
3648 return DenseMapInfo<Instruction *>::getEmptyKey();
3649 }
3650 static inline Instruction *getTombstoneKey() {
3651 return DenseMapInfo<Instruction *>::getTombstoneKey();
3652 }
3653 static unsigned getHashValue(const Instruction *I) {
3654 assert(canHandle(I) && "Unknown instruction!")((canHandle(I) && "Unknown instruction!") ? static_cast
<void> (0) : __assert_fail ("canHandle(I) && \"Unknown instruction!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3654, __PRETTY_FUNCTION__))
;
3655 return hash_combine(I->getOpcode(), hash_combine_range(I->value_op_begin(),
3656 I->value_op_end()));
3657 }
3658 static bool isEqual(const Instruction *LHS, const Instruction *RHS) {
3659 if (LHS == getEmptyKey() || RHS == getEmptyKey() ||
3660 LHS == getTombstoneKey() || RHS == getTombstoneKey())
3661 return LHS == RHS;
3662 return LHS->isIdenticalTo(RHS);
3663 }
3664};
3665}
3666
3667///\brief Perform cse of induction variable instructions.
3668static void cse(BasicBlock *BB) {
3669 // Perform simple cse.
3670 SmallDenseMap<Instruction *, Instruction *, 4, CSEDenseMapInfo> CSEMap;
3671 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
3672 Instruction *In = &*I++;
3673
3674 if (!CSEDenseMapInfo::canHandle(In))
3675 continue;
3676
3677 // Check if we can replace this instruction with any of the
3678 // visited instructions.
3679 if (Instruction *V = CSEMap.lookup(In)) {
3680 In->replaceAllUsesWith(V);
3681 In->eraseFromParent();
3682 continue;
3683 }
3684
3685 CSEMap[In] = In;
3686 }
3687}
3688
3689/// \brief Estimate the overhead of scalarizing an instruction. This is a
3690/// convenience wrapper for the type-based getScalarizationOverhead API.
3691static unsigned getScalarizationOverhead(Instruction *I, unsigned VF,
3692 const TargetTransformInfo &TTI) {
3693 if (VF == 1)
3694 return 0;
3695
3696 unsigned Cost = 0;
3697 Type *RetTy = ToVectorTy(I->getType(), VF);
3698 if (!RetTy->isVoidTy() &&
3699 (!isa<LoadInst>(I) ||
3700 !TTI.supportsEfficientVectorElementLoadStore()))
3701 Cost += TTI.getScalarizationOverhead(RetTy, true, false);
3702
3703 if (CallInst *CI = dyn_cast<CallInst>(I)) {
3704 SmallVector<const Value *, 4> Operands(CI->arg_operands());
3705 Cost += TTI.getOperandsScalarizationOverhead(Operands, VF);
3706 }
3707 else if (!isa<StoreInst>(I) ||
3708 !TTI.supportsEfficientVectorElementLoadStore()) {
3709 SmallVector<const Value *, 4> Operands(I->operand_values());
3710 Cost += TTI.getOperandsScalarizationOverhead(Operands, VF);
3711 }
3712
3713 return Cost;
3714}
3715
3716// Estimate cost of a call instruction CI if it were vectorized with factor VF.
3717// Return the cost of the instruction, including scalarization overhead if it's
3718// needed. The flag NeedToScalarize shows if the call needs to be scalarized -
3719// i.e. either vector version isn't available, or is too expensive.
3720static unsigned getVectorCallCost(CallInst *CI, unsigned VF,
3721 const TargetTransformInfo &TTI,
3722 const TargetLibraryInfo *TLI,
3723 bool &NeedToScalarize) {
3724 Function *F = CI->getCalledFunction();
3725 StringRef FnName = CI->getCalledFunction()->getName();
3726 Type *ScalarRetTy = CI->getType();
3727 SmallVector<Type *, 4> Tys, ScalarTys;
3728 for (auto &ArgOp : CI->arg_operands())
3729 ScalarTys.push_back(ArgOp->getType());
3730
3731 // Estimate cost of scalarized vector call. The source operands are assumed
3732 // to be vectors, so we need to extract individual elements from there,
3733 // execute VF scalar calls, and then gather the result into the vector return
3734 // value.
3735 unsigned ScalarCallCost = TTI.getCallInstrCost(F, ScalarRetTy, ScalarTys);
3736 if (VF == 1)
3737 return ScalarCallCost;
3738
3739 // Compute corresponding vector type for return value and arguments.
3740 Type *RetTy = ToVectorTy(ScalarRetTy, VF);
3741 for (Type *ScalarTy : ScalarTys)
3742 Tys.push_back(ToVectorTy(ScalarTy, VF));
3743
3744 // Compute costs of unpacking argument values for the scalar calls and
3745 // packing the return values to a vector.
3746 unsigned ScalarizationCost = getScalarizationOverhead(CI, VF, TTI);
3747
3748 unsigned Cost = ScalarCallCost * VF + ScalarizationCost;
3749
3750 // If we can't emit a vector call for this function, then the currently found
3751 // cost is the cost we need to return.
3752 NeedToScalarize = true;
3753 if (!TLI || !TLI->isFunctionVectorizable(FnName, VF) || CI->isNoBuiltin())
3754 return Cost;
3755
3756 // If the corresponding vector cost is cheaper, return its cost.
3757 unsigned VectorCallCost = TTI.getCallInstrCost(nullptr, RetTy, Tys);
3758 if (VectorCallCost < Cost) {
3759 NeedToScalarize = false;
3760 return VectorCallCost;
3761 }
3762 return Cost;
3763}
3764
3765// Estimate cost of an intrinsic call instruction CI if it were vectorized with
3766// factor VF. Return the cost of the instruction, including scalarization
3767// overhead if it's needed.
3768static unsigned getVectorIntrinsicCost(CallInst *CI, unsigned VF,
3769 const TargetTransformInfo &TTI,
3770 const TargetLibraryInfo *TLI) {
3771 Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
3772 assert(ID && "Expected intrinsic call!")((ID && "Expected intrinsic call!") ? static_cast<
void> (0) : __assert_fail ("ID && \"Expected intrinsic call!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3772, __PRETTY_FUNCTION__))
;
3773
3774 FastMathFlags FMF;
3775 if (auto *FPMO = dyn_cast<FPMathOperator>(CI))
3776 FMF = FPMO->getFastMathFlags();
3777
3778 SmallVector<Value *, 4> Operands(CI->arg_operands());
3779 return TTI.getIntrinsicInstrCost(ID, CI->getType(), Operands, FMF, VF);
3780}
3781
3782static Type *smallestIntegerVectorType(Type *T1, Type *T2) {
3783 auto *I1 = cast<IntegerType>(T1->getVectorElementType());
3784 auto *I2 = cast<IntegerType>(T2->getVectorElementType());
3785 return I1->getBitWidth() < I2->getBitWidth() ? T1 : T2;
3786}
3787static Type *largestIntegerVectorType(Type *T1, Type *T2) {
3788 auto *I1 = cast<IntegerType>(T1->getVectorElementType());
3789 auto *I2 = cast<IntegerType>(T2->getVectorElementType());
3790 return I1->getBitWidth() > I2->getBitWidth() ? T1 : T2;
3791}
3792
3793void InnerLoopVectorizer::truncateToMinimalBitwidths() {
3794 // For every instruction `I` in MinBWs, truncate the operands, create a
3795 // truncated version of `I` and reextend its result. InstCombine runs
3796 // later and will remove any ext/trunc pairs.
3797 //
3798 SmallPtrSet<Value *, 4> Erased;
3799 for (const auto &KV : Cost->getMinimalBitwidths()) {
3800 // If the value wasn't vectorized, we must maintain the original scalar
3801 // type. The absence of the value from VectorLoopValueMap indicates that it
3802 // wasn't vectorized.
3803 if (!VectorLoopValueMap.hasAnyVectorValue(KV.first))
3804 continue;
3805 for (unsigned Part = 0; Part < UF; ++Part) {
3806 Value *I = getOrCreateVectorValue(KV.first, Part);
3807 if (Erased.count(I) || I->use_empty() || !isa<Instruction>(I))
3808 continue;
3809 Type *OriginalTy = I->getType();
3810 Type *ScalarTruncatedTy =
3811 IntegerType::get(OriginalTy->getContext(), KV.second);
3812 Type *TruncatedTy = VectorType::get(ScalarTruncatedTy,
3813 OriginalTy->getVectorNumElements());
3814 if (TruncatedTy == OriginalTy)
3815 continue;
3816
3817 IRBuilder<> B(cast<Instruction>(I));
3818 auto ShrinkOperand = [&](Value *V) -> Value * {
3819 if (auto *ZI = dyn_cast<ZExtInst>(V))
3820 if (ZI->getSrcTy() == TruncatedTy)
3821 return ZI->getOperand(0);
3822 return B.CreateZExtOrTrunc(V, TruncatedTy);
3823 };
3824
3825 // The actual instruction modification depends on the instruction type,
3826 // unfortunately.
3827 Value *NewI = nullptr;
3828 if (auto *BO = dyn_cast<BinaryOperator>(I)) {
3829 NewI = B.CreateBinOp(BO->getOpcode(), ShrinkOperand(BO->getOperand(0)),
3830 ShrinkOperand(BO->getOperand(1)));
3831
3832 // Any wrapping introduced by shrinking this operation shouldn't be
3833 // considered undefined behavior. So, we can't unconditionally copy
3834 // arithmetic wrapping flags to NewI.
3835 cast<BinaryOperator>(NewI)->copyIRFlags(I, /*IncludeWrapFlags=*/false);
3836 } else if (auto *CI = dyn_cast<ICmpInst>(I)) {
3837 NewI =
3838 B.CreateICmp(CI->getPredicate(), ShrinkOperand(CI->getOperand(0)),
3839 ShrinkOperand(CI->getOperand(1)));
3840 } else if (auto *SI = dyn_cast<SelectInst>(I)) {
3841 NewI = B.CreateSelect(SI->getCondition(),
3842 ShrinkOperand(SI->getTrueValue()),
3843 ShrinkOperand(SI->getFalseValue()));
3844 } else if (auto *CI = dyn_cast<CastInst>(I)) {
3845 switch (CI->getOpcode()) {
3846 default:
3847 llvm_unreachable("Unhandled cast!")::llvm::llvm_unreachable_internal("Unhandled cast!", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3847)
;
3848 case Instruction::Trunc:
3849 NewI = ShrinkOperand(CI->getOperand(0));
3850 break;
3851 case Instruction::SExt:
3852 NewI = B.CreateSExtOrTrunc(
3853 CI->getOperand(0),
3854 smallestIntegerVectorType(OriginalTy, TruncatedTy));
3855 break;
3856 case Instruction::ZExt:
3857 NewI = B.CreateZExtOrTrunc(
3858 CI->getOperand(0),
3859 smallestIntegerVectorType(OriginalTy, TruncatedTy));
3860 break;
3861 }
3862 } else if (auto *SI = dyn_cast<ShuffleVectorInst>(I)) {
3863 auto Elements0 = SI->getOperand(0)->getType()->getVectorNumElements();
3864 auto *O0 = B.CreateZExtOrTrunc(
3865 SI->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements0));
3866 auto Elements1 = SI->getOperand(1)->getType()->getVectorNumElements();
3867 auto *O1 = B.CreateZExtOrTrunc(
3868 SI->getOperand(1), VectorType::get(ScalarTruncatedTy, Elements1));
3869
3870 NewI = B.CreateShuffleVector(O0, O1, SI->getMask());
3871 } else if (isa<LoadInst>(I)) {
3872 // Don't do anything with the operands, just extend the result.
3873 continue;
3874 } else if (auto *IE = dyn_cast<InsertElementInst>(I)) {
3875 auto Elements = IE->getOperand(0)->getType()->getVectorNumElements();
3876 auto *O0 = B.CreateZExtOrTrunc(
3877 IE->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements));
3878 auto *O1 = B.CreateZExtOrTrunc(IE->getOperand(1), ScalarTruncatedTy);
3879 NewI = B.CreateInsertElement(O0, O1, IE->getOperand(2));
3880 } else if (auto *EE = dyn_cast<ExtractElementInst>(I)) {
3881 auto Elements = EE->getOperand(0)->getType()->getVectorNumElements();
3882 auto *O0 = B.CreateZExtOrTrunc(
3883 EE->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements));
3884 NewI = B.CreateExtractElement(O0, EE->getOperand(2));
3885 } else {
3886 llvm_unreachable("Unhandled instruction type!")::llvm::llvm_unreachable_internal("Unhandled instruction type!"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3886)
;
3887 }
3888
3889 // Lastly, extend the result.
3890 NewI->takeName(cast<Instruction>(I));
3891 Value *Res = B.CreateZExtOrTrunc(NewI, OriginalTy);
3892 I->replaceAllUsesWith(Res);
3893 cast<Instruction>(I)->eraseFromParent();
3894 Erased.insert(I);
3895 VectorLoopValueMap.resetVectorValue(KV.first, Part, Res);
3896 }
3897 }
3898
3899 // We'll have created a bunch of ZExts that are now parentless. Clean up.
3900 for (const auto &KV : Cost->getMinimalBitwidths()) {
3901 // If the value wasn't vectorized, we must maintain the original scalar
3902 // type. The absence of the value from VectorLoopValueMap indicates that it
3903 // wasn't vectorized.
3904 if (!VectorLoopValueMap.hasAnyVectorValue(KV.first))
3905 continue;
3906 for (unsigned Part = 0; Part < UF; ++Part) {
3907 Value *I = getOrCreateVectorValue(KV.first, Part);
3908 ZExtInst *Inst = dyn_cast<ZExtInst>(I);
3909 if (Inst && Inst->use_empty()) {
3910 Value *NewI = Inst->getOperand(0);
3911 Inst->eraseFromParent();
3912 VectorLoopValueMap.resetVectorValue(KV.first, Part, NewI);
3913 }
3914 }
3915 }
3916}
3917
3918void InnerLoopVectorizer::fixVectorizedLoop() {
3919 // Insert truncates and extends for any truncated instructions as hints to
3920 // InstCombine.
3921 if (VF > 1)
3922 truncateToMinimalBitwidths();
3923
3924 // At this point every instruction in the original loop is widened to a
3925 // vector form. Now we need to fix the recurrences in the loop. These PHI
3926 // nodes are currently empty because we did not want to introduce cycles.
3927 // This is the second stage of vectorizing recurrences.
3928 fixCrossIterationPHIs();
3929
3930 // Update the dominator tree.
3931 //
3932 // FIXME: After creating the structure of the new loop, the dominator tree is
3933 // no longer up-to-date, and it remains that way until we update it
3934 // here. An out-of-date dominator tree is problematic for SCEV,
3935 // because SCEVExpander uses it to guide code generation. The
3936 // vectorizer use SCEVExpanders in several places. Instead, we should
3937 // keep the dominator tree up-to-date as we go.
3938 updateAnalysis();
3939
3940 // Fix-up external users of the induction variables.
3941 for (auto &Entry : *Legal->getInductionVars())
3942 fixupIVUsers(Entry.first, Entry.second,
3943 getOrCreateVectorTripCount(LI->getLoopFor(LoopVectorBody)),
3944 IVEndValues[Entry.first], LoopMiddleBlock);
3945
3946 fixLCSSAPHIs();
3947 predicateInstructions();
3948
3949 // Remove redundant induction instructions.
3950 cse(LoopVectorBody);
3951}
3952
3953void InnerLoopVectorizer::fixCrossIterationPHIs() {
3954 // In order to support recurrences we need to be able to vectorize Phi nodes.
3955 // Phi nodes have cycles, so we need to vectorize them in two stages. This is
3956 // stage #2: We now need to fix the recurrences by adding incoming edges to
3957 // the currently empty PHI nodes. At this point every instruction in the
3958 // original loop is widened to a vector form so we can use them to construct
3959 // the incoming edges.
3960 for (Instruction &I : *OrigLoop->getHeader()) {
3961 PHINode *Phi = dyn_cast<PHINode>(&I);
3962 if (!Phi)
3963 break;
3964 // Handle first-order recurrences and reductions that need to be fixed.
3965 if (Legal->isFirstOrderRecurrence(Phi))
3966 fixFirstOrderRecurrence(Phi);
3967 else if (Legal->isReductionVariable(Phi))
3968 fixReduction(Phi);
3969 }
3970}
3971
3972void InnerLoopVectorizer::fixFirstOrderRecurrence(PHINode *Phi) {
3973
3974 // This is the second phase of vectorizing first-order recurrences. An
3975 // overview of the transformation is described below. Suppose we have the
3976 // following loop.
3977 //
3978 // for (int i = 0; i < n; ++i)
3979 // b[i] = a[i] - a[i - 1];
3980 //
3981 // There is a first-order recurrence on "a". For this loop, the shorthand
3982 // scalar IR looks like:
3983 //
3984 // scalar.ph:
3985 // s_init = a[-1]
3986 // br scalar.body
3987 //
3988 // scalar.body:
3989 // i = phi [0, scalar.ph], [i+1, scalar.body]
3990 // s1 = phi [s_init, scalar.ph], [s2, scalar.body]
3991 // s2 = a[i]
3992 // b[i] = s2 - s1
3993 // br cond, scalar.body, ...
3994 //
3995 // In this example, s1 is a recurrence because it's value depends on the
3996 // previous iteration. In the first phase of vectorization, we created a
3997 // temporary value for s1. We now complete the vectorization and produce the
3998 // shorthand vector IR shown below (for VF = 4, UF = 1).
3999 //
4000 // vector.ph:
4001 // v_init = vector(..., ..., ..., a[-1])
4002 // br vector.body
4003 //
4004 // vector.body
4005 // i = phi [0, vector.ph], [i+4, vector.body]
4006 // v1 = phi [v_init, vector.ph], [v2, vector.body]
4007 // v2 = a[i, i+1, i+2, i+3];
4008 // v3 = vector(v1(3), v2(0, 1, 2))
4009 // b[i, i+1, i+2, i+3] = v2 - v3
4010 // br cond, vector.body, middle.block
4011 //
4012 // middle.block:
4013 // x = v2(3)
4014 // br scalar.ph
4015 //
4016 // scalar.ph:
4017 // s_init = phi [x, middle.block], [a[-1], otherwise]
4018 // br scalar.body
4019 //
4020 // After execution completes the vector loop, we extract the next value of
4021 // the recurrence (x) to use as the initial value in the scalar loop.
4022
4023 // Get the original loop preheader and single loop latch.
4024 auto *Preheader = OrigLoop->getLoopPreheader();
4025 auto *Latch = OrigLoop->getLoopLatch();
4026
4027 // Get the initial and previous values of the scalar recurrence.
4028 auto *ScalarInit = Phi->getIncomingValueForBlock(Preheader);
4029 auto *Previous = Phi->getIncomingValueForBlock(Latch);
4030
4031 // Create a vector from the initial value.
4032 auto *VectorInit = ScalarInit;
4033 if (VF > 1) {
4034 Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator());
4035 VectorInit = Builder.CreateInsertElement(
4036 UndefValue::get(VectorType::get(VectorInit->getType(), VF)), VectorInit,
4037 Builder.getInt32(VF - 1), "vector.recur.init");
4038 }
4039
4040 // We constructed a temporary phi node in the first phase of vectorization.
4041 // This phi node will eventually be deleted.
4042 Builder.SetInsertPoint(
4043 cast<Instruction>(VectorLoopValueMap.getVectorValue(Phi, 0)));
4044
4045 // Create a phi node for the new recurrence. The current value will either be
4046 // the initial value inserted into a vector or loop-varying vector value.
4047 auto *VecPhi = Builder.CreatePHI(VectorInit->getType(), 2, "vector.recur");
4048 VecPhi->addIncoming(VectorInit, LoopVectorPreHeader);
4049
4050 // Get the vectorized previous value.
4051 Value *PreviousLastPart = getOrCreateVectorValue(Previous, UF - 1);
4052
4053 // Set the insertion point after the previous value if it is an instruction.
4054 // Note that the previous value may have been constant-folded so it is not
4055 // guaranteed to be an instruction in the vector loop. Also, if the previous
4056 // value is a phi node, we should insert after all the phi nodes to avoid
4057 // breaking basic block verification.
4058 if (LI->getLoopFor(LoopVectorBody)->isLoopInvariant(PreviousLastPart) ||
4059 isa<PHINode>(PreviousLastPart))
4060 Builder.SetInsertPoint(&*LoopVectorBody->getFirstInsertionPt());
4061 else
4062 Builder.SetInsertPoint(
4063 &*++BasicBlock::iterator(cast<Instruction>(PreviousLastPart)));
4064
4065 // We will construct a vector for the recurrence by combining the values for
4066 // the current and previous iterations. This is the required shuffle mask.
4067 SmallVector<Constant *, 8> ShuffleMask(VF);
4068 ShuffleMask[0] = Builder.getInt32(VF - 1);
4069 for (unsigned I = 1; I < VF; ++I)
4070 ShuffleMask[I] = Builder.getInt32(I + VF - 1);
4071
4072 // The vector from which to take the initial value for the current iteration
4073 // (actual or unrolled). Initially, this is the vector phi node.
4074 Value *Incoming = VecPhi;
4075
4076 // Shuffle the current and previous vector and update the vector parts.
4077 for (unsigned Part = 0; Part < UF; ++Part) {
4078 Value *PreviousPart = getOrCreateVectorValue(Previous, Part);
4079 Value *PhiPart = VectorLoopValueMap.getVectorValue(Phi, Part);
4080 auto *Shuffle =
4081 VF > 1 ? Builder.CreateShuffleVector(Incoming, PreviousPart,
4082 ConstantVector::get(ShuffleMask))
4083 : Incoming;
4084 PhiPart->replaceAllUsesWith(Shuffle);
4085 cast<Instruction>(PhiPart)->eraseFromParent();
4086 VectorLoopValueMap.resetVectorValue(Phi, Part, Shuffle);
4087 Incoming = PreviousPart;
4088 }
4089
4090 // Fix the latch value of the new recurrence in the vector loop.
4091 VecPhi->addIncoming(Incoming, LI->getLoopFor(LoopVectorBody)->getLoopLatch());
4092
4093 // Extract the last vector element in the middle block. This will be the
4094 // initial value for the recurrence when jumping to the scalar loop.
4095 auto *ExtractForScalar = Incoming;
4096 if (VF > 1) {
4097 Builder.SetInsertPoint(LoopMiddleBlock->getTerminator());
4098 ExtractForScalar = Builder.CreateExtractElement(
4099 ExtractForScalar, Builder.getInt32(VF - 1), "vector.recur.extract");
4100 }
4101 // Extract the second last element in the middle block if the
4102 // Phi is used outside the loop. We need to extract the phi itself
4103 // and not the last element (the phi update in the current iteration). This
4104 // will be the value when jumping to the exit block from the LoopMiddleBlock,
4105 // when the scalar loop is not run at all.
4106 Value *ExtractForPhiUsedOutsideLoop = nullptr;
4107 if (VF > 1)
4108 ExtractForPhiUsedOutsideLoop = Builder.CreateExtractElement(
4109 Incoming, Builder.getInt32(VF - 2), "vector.recur.extract.for.phi");
4110 // When loop is unrolled without vectorizing, initialize
4111 // ExtractForPhiUsedOutsideLoop with the value just prior to unrolled value of
4112 // `Incoming`. This is analogous to the vectorized case above: extracting the
4113 // second last element when VF > 1.
4114 else if (UF > 1)
4115 ExtractForPhiUsedOutsideLoop = getOrCreateVectorValue(Previous, UF - 2);
4116
4117 // Fix the initial value of the original recurrence in the scalar loop.
4118 Builder.SetInsertPoint(&*LoopScalarPreHeader->begin());
4119 auto *Start = Builder.CreatePHI(Phi->getType(), 2, "scalar.recur.init");
4120 for (auto *BB : predecessors(LoopScalarPreHeader)) {
4121 auto *Incoming = BB == LoopMiddleBlock ? ExtractForScalar : ScalarInit;
4122 Start->addIncoming(Incoming, BB);
4123 }
4124
4125 Phi->setIncomingValue(Phi->getBasicBlockIndex(LoopScalarPreHeader), Start);
4126 Phi->setName("scalar.recur");
4127
4128 // Finally, fix users of the recurrence outside the loop. The users will need
4129 // either the last value of the scalar recurrence or the last value of the
4130 // vector recurrence we extracted in the middle block. Since the loop is in
4131 // LCSSA form, we just need to find the phi node for the original scalar
4132 // recurrence in the exit block, and then add an edge for the middle block.
4133 for (auto &I : *LoopExitBlock) {
4134 auto *LCSSAPhi = dyn_cast<PHINode>(&I);
4135 if (!LCSSAPhi)
4136 break;
4137 if (LCSSAPhi->getIncomingValue(0) == Phi) {
4138 LCSSAPhi->addIncoming(ExtractForPhiUsedOutsideLoop, LoopMiddleBlock);
4139 break;
4140 }
4141 }
4142}
4143
4144void InnerLoopVectorizer::fixReduction(PHINode *Phi) {
4145 Constant *Zero = Builder.getInt32(0);
4146
4147 // Get it's reduction variable descriptor.
4148 assert(Legal->isReductionVariable(Phi) &&((Legal->isReductionVariable(Phi) && "Unable to find the reduction variable"
) ? static_cast<void> (0) : __assert_fail ("Legal->isReductionVariable(Phi) && \"Unable to find the reduction variable\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4149, __PRETTY_FUNCTION__))
4149 "Unable to find the reduction variable")((Legal->isReductionVariable(Phi) && "Unable to find the reduction variable"
) ? static_cast<void> (0) : __assert_fail ("Legal->isReductionVariable(Phi) && \"Unable to find the reduction variable\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4149, __PRETTY_FUNCTION__))
;
4150 RecurrenceDescriptor RdxDesc = (*Legal->getReductionVars())[Phi];
4151
4152 RecurrenceDescriptor::RecurrenceKind RK = RdxDesc.getRecurrenceKind();
4153 TrackingVH<Value> ReductionStartValue = RdxDesc.getRecurrenceStartValue();
4154 Instruction *LoopExitInst = RdxDesc.getLoopExitInstr();
4155 RecurrenceDescriptor::MinMaxRecurrenceKind MinMaxKind =
4156 RdxDesc.getMinMaxRecurrenceKind();
4157 setDebugLocFromInst(Builder, ReductionStartValue);
4158
4159 // We need to generate a reduction vector from the incoming scalar.
4160 // To do so, we need to generate the 'identity' vector and override
4161 // one of the elements with the incoming scalar reduction. We need
4162 // to do it in the vector-loop preheader.
4163 Builder.SetInsertPoint(LoopBypassBlocks[1]->getTerminator());
4164
4165 // This is the vector-clone of the value that leaves the loop.
4166 Type *VecTy = getOrCreateVectorValue(LoopExitInst, 0)->getType();
4167
4168 // Find the reduction identity variable. Zero for addition, or, xor,
4169 // one for multiplication, -1 for And.
4170 Value *Identity;
4171 Value *VectorStart;
4172 if (RK == RecurrenceDescriptor::RK_IntegerMinMax ||
4173 RK == RecurrenceDescriptor::RK_FloatMinMax) {
4174 // MinMax reduction have the start value as their identify.
4175 if (VF == 1) {
4176 VectorStart = Identity = ReductionStartValue;
4177 } else {
4178 VectorStart = Identity =
4179 Builder.CreateVectorSplat(VF, ReductionStartValue, "minmax.ident");
4180 }
4181 } else {
4182 // Handle other reduction kinds:
4183 Constant *Iden = RecurrenceDescriptor::getRecurrenceIdentity(
4184 RK, VecTy->getScalarType());
4185 if (VF == 1) {
4186 Identity = Iden;
4187 // This vector is the Identity vector where the first element is the
4188 // incoming scalar reduction.
4189 VectorStart = ReductionStartValue;
4190 } else {
4191 Identity = ConstantVector::getSplat(VF, Iden);
4192
4193 // This vector is the Identity vector where the first element is the
4194 // incoming scalar reduction.
4195 VectorStart =
4196 Builder.CreateInsertElement(Identity, ReductionStartValue, Zero);
4197 }
4198 }
4199
4200 // Fix the vector-loop phi.
4201
4202 // Reductions do not have to start at zero. They can start with
4203 // any loop invariant values.
4204 BasicBlock *Latch = OrigLoop->getLoopLatch();
4205 Value *LoopVal = Phi->getIncomingValueForBlock(Latch);
4206 for (unsigned Part = 0; Part < UF; ++Part) {
4207 Value *VecRdxPhi = getOrCreateVectorValue(Phi, Part);
4208 Value *Val = getOrCreateVectorValue(LoopVal, Part);
4209 // Make sure to add the reduction stat value only to the
4210 // first unroll part.
4211 Value *StartVal = (Part == 0) ? VectorStart : Identity;
4212 cast<PHINode>(VecRdxPhi)->addIncoming(StartVal, LoopVectorPreHeader);
4213 cast<PHINode>(VecRdxPhi)
4214 ->addIncoming(Val, LI->getLoopFor(LoopVectorBody)->getLoopLatch());
4215 }
4216
4217 // Before each round, move the insertion point right between
4218 // the PHIs and the values we are going to write.
4219 // This allows us to write both PHINodes and the extractelement
4220 // instructions.
4221 Builder.SetInsertPoint(&*LoopMiddleBlock->getFirstInsertionPt());
4222
4223 setDebugLocFromInst(Builder, LoopExitInst);
4224
4225 // If the vector reduction can be performed in a smaller type, we truncate
4226 // then extend the loop exit value to enable InstCombine to evaluate the
4227 // entire expression in the smaller type.
4228 if (VF > 1 && Phi->getType() != RdxDesc.getRecurrenceType()) {
4229 Type *RdxVecTy = VectorType::get(RdxDesc.getRecurrenceType(), VF);
4230 Builder.SetInsertPoint(LoopVectorBody->getTerminator());
4231 VectorParts RdxParts(UF);
4232 for (unsigned Part = 0; Part < UF; ++Part) {
4233 RdxParts[Part] = VectorLoopValueMap.getVectorValue(LoopExitInst, Part);
4234 Value *Trunc = Builder.CreateTrunc(RdxParts[Part], RdxVecTy);
4235 Value *Extnd = RdxDesc.isSigned() ? Builder.CreateSExt(Trunc, VecTy)
4236 : Builder.CreateZExt(Trunc, VecTy);
4237 for (Value::user_iterator UI = RdxParts[Part]->user_begin();
4238 UI != RdxParts[Part]->user_end();)
4239 if (*UI != Trunc) {
4240 (*UI++)->replaceUsesOfWith(RdxParts[Part], Extnd);
4241 RdxParts[Part] = Extnd;
4242 } else {
4243 ++UI;
4244 }
4245 }
4246 Builder.SetInsertPoint(&*LoopMiddleBlock->getFirstInsertionPt());
4247 for (unsigned Part = 0; Part < UF; ++Part) {
4248 RdxParts[Part] = Builder.CreateTrunc(RdxParts[Part], RdxVecTy);
4249 VectorLoopValueMap.resetVectorValue(LoopExitInst, Part, RdxParts[Part]);
4250 }
4251 }
4252
4253 // Reduce all of the unrolled parts into a single vector.
4254 Value *ReducedPartRdx = VectorLoopValueMap.getVectorValue(LoopExitInst, 0);
4255 unsigned Op = RecurrenceDescriptor::getRecurrenceBinOp(RK);
4256 setDebugLocFromInst(Builder, ReducedPartRdx);
4257 for (unsigned Part = 1; Part < UF; ++Part) {
4258 Value *RdxPart = VectorLoopValueMap.getVectorValue(LoopExitInst, Part);
4259 if (Op != Instruction::ICmp && Op != Instruction::FCmp)
4260 // Floating point operations had to be 'fast' to enable the reduction.
4261 ReducedPartRdx = addFastMathFlag(
4262 Builder.CreateBinOp((Instruction::BinaryOps)Op, RdxPart,
4263 ReducedPartRdx, "bin.rdx"));
4264 else
4265 ReducedPartRdx = RecurrenceDescriptor::createMinMaxOp(
4266 Builder, MinMaxKind, ReducedPartRdx, RdxPart);
4267 }
4268
4269 if (VF > 1) {
4270 bool NoNaN = Legal->hasFunNoNaNAttr();
4271 ReducedPartRdx =
4272 createTargetReduction(Builder, TTI, RdxDesc, ReducedPartRdx, NoNaN);
4273 // If the reduction can be performed in a smaller type, we need to extend
4274 // the reduction to the wider type before we branch to the original loop.
4275 if (Phi->getType() != RdxDesc.getRecurrenceType())
4276 ReducedPartRdx =
4277 RdxDesc.isSigned()
4278 ? Builder.CreateSExt(ReducedPartRdx, Phi->getType())
4279 : Builder.CreateZExt(ReducedPartRdx, Phi->getType());
4280 }
4281
4282 // Create a phi node that merges control-flow from the backedge-taken check
4283 // block and the middle block.
4284 PHINode *BCBlockPhi = PHINode::Create(Phi->getType(), 2, "bc.merge.rdx",
4285 LoopScalarPreHeader->getTerminator());
4286 for (unsigned I = 0, E = LoopBypassBlocks.size(); I != E; ++I)
4287 BCBlockPhi->addIncoming(ReductionStartValue, LoopBypassBlocks[I]);
4288 BCBlockPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock);
4289
4290 // Now, we need to fix the users of the reduction variable
4291 // inside and outside of the scalar remainder loop.
4292 // We know that the loop is in LCSSA form. We need to update the
4293 // PHI nodes in the exit blocks.
4294 for (BasicBlock::iterator LEI = LoopExitBlock->begin(),
4295 LEE = LoopExitBlock->end();
4296 LEI != LEE; ++LEI) {
4297 PHINode *LCSSAPhi = dyn_cast<PHINode>(LEI);
4298 if (!LCSSAPhi)
4299 break;
4300
4301 // All PHINodes need to have a single entry edge, or two if
4302 // we already fixed them.
4303 assert(LCSSAPhi->getNumIncomingValues() < 3 && "Invalid LCSSA PHI")((LCSSAPhi->getNumIncomingValues() < 3 && "Invalid LCSSA PHI"
) ? static_cast<void> (0) : __assert_fail ("LCSSAPhi->getNumIncomingValues() < 3 && \"Invalid LCSSA PHI\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4303, __PRETTY_FUNCTION__))
;
4304
4305 // We found a reduction value exit-PHI. Update it with the
4306 // incoming bypass edge.
4307 if (LCSSAPhi->getIncomingValue(0) == LoopExitInst)
4308 LCSSAPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock);
4309 } // end of the LCSSA phi scan.
4310
4311 // Fix the scalar loop reduction variable with the incoming reduction sum
4312 // from the vector body and from the backedge value.
4313 int IncomingEdgeBlockIdx =
4314 Phi->getBasicBlockIndex(OrigLoop->getLoopLatch());
4315 assert(IncomingEdgeBlockIdx >= 0 && "Invalid block index")((IncomingEdgeBlockIdx >= 0 && "Invalid block index"
) ? static_cast<void> (0) : __assert_fail ("IncomingEdgeBlockIdx >= 0 && \"Invalid block index\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4315, __PRETTY_FUNCTION__))
;
4316 // Pick the other block.
4317 int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1);
4318 Phi->setIncomingValue(SelfEdgeBlockIdx, BCBlockPhi);
4319 Phi->setIncomingValue(IncomingEdgeBlockIdx, LoopExitInst);
4320}
4321
4322void InnerLoopVectorizer::fixLCSSAPHIs() {
4323 for (Instruction &LEI : *LoopExitBlock) {
4324 auto *LCSSAPhi = dyn_cast<PHINode>(&LEI);
4325 if (!LCSSAPhi)
4326 break;
4327 if (LCSSAPhi->getNumIncomingValues() == 1) {
4328 assert(OrigLoop->isLoopInvariant(LCSSAPhi->getIncomingValue(0)) &&((OrigLoop->isLoopInvariant(LCSSAPhi->getIncomingValue(
0)) && "Incoming value isn't loop invariant") ? static_cast
<void> (0) : __assert_fail ("OrigLoop->isLoopInvariant(LCSSAPhi->getIncomingValue(0)) && \"Incoming value isn't loop invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4329, __PRETTY_FUNCTION__))
4329 "Incoming value isn't loop invariant")((OrigLoop->isLoopInvariant(LCSSAPhi->getIncomingValue(
0)) && "Incoming value isn't loop invariant") ? static_cast
<void> (0) : __assert_fail ("OrigLoop->isLoopInvariant(LCSSAPhi->getIncomingValue(0)) && \"Incoming value isn't loop invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4329, __PRETTY_FUNCTION__))
;
4330 LCSSAPhi->addIncoming(LCSSAPhi->getIncomingValue(0), LoopMiddleBlock);
4331 }
4332 }
4333}
4334
4335void InnerLoopVectorizer::sinkScalarOperands(Instruction *PredInst) {
4336
4337 // The basic block and loop containing the predicated instruction.
4338 auto *PredBB = PredInst->getParent();
4339 auto *VectorLoop = LI->getLoopFor(PredBB);
4340
4341 // Initialize a worklist with the operands of the predicated instruction.
4342 SetVector<Value *> Worklist(PredInst->op_begin(), PredInst->op_end());
4343
4344 // Holds instructions that we need to analyze again. An instruction may be
4345 // reanalyzed if we don't yet know if we can sink it or not.
4346 SmallVector<Instruction *, 8> InstsToReanalyze;
4347
4348 // Returns true if a given use occurs in the predicated block. Phi nodes use
4349 // their operands in their corresponding predecessor blocks.
4350 auto isBlockOfUsePredicated = [&](Use &U) -> bool {
4351 auto *I = cast<Instruction>(U.getUser());
4352 BasicBlock *BB = I->getParent();
4353 if (auto *Phi = dyn_cast<PHINode>(I))
4354 BB = Phi->getIncomingBlock(
4355 PHINode::getIncomingValueNumForOperand(U.getOperandNo()));
4356 return BB == PredBB;
4357 };
4358
4359 // Iteratively sink the scalarized operands of the predicated instruction
4360 // into the block we created for it. When an instruction is sunk, it's
4361 // operands are then added to the worklist. The algorithm ends after one pass
4362 // through the worklist doesn't sink a single instruction.
4363 bool Changed;
4364 do {
4365
4366 // Add the instructions that need to be reanalyzed to the worklist, and
4367 // reset the changed indicator.
4368 Worklist.insert(InstsToReanalyze.begin(), InstsToReanalyze.end());
4369 InstsToReanalyze.clear();
4370 Changed = false;
4371
4372 while (!Worklist.empty()) {
4373 auto *I = dyn_cast<Instruction>(Worklist.pop_back_val());
4374
4375 // We can't sink an instruction if it is a phi node, is already in the
4376 // predicated block, is not in the loop, or may have side effects.
4377 if (!I || isa<PHINode>(I) || I->getParent() == PredBB ||
4378 !VectorLoop->contains(I) || I->mayHaveSideEffects())
4379 continue;
4380
4381 // It's legal to sink the instruction if all its uses occur in the
4382 // predicated block. Otherwise, there's nothing to do yet, and we may
4383 // need to reanalyze the instruction.
4384 if (!all_of(I->uses(), isBlockOfUsePredicated)) {
4385 InstsToReanalyze.push_back(I);
4386 continue;
4387 }
4388
4389 // Move the instruction to the beginning of the predicated block, and add
4390 // it's operands to the worklist.
4391 I->moveBefore(&*PredBB->getFirstInsertionPt());
4392 Worklist.insert(I->op_begin(), I->op_end());
4393
4394 // The sinking may have enabled other instructions to be sunk, so we will
4395 // need to iterate.
4396 Changed = true;
4397 }
4398 } while (Changed);
4399}
4400
4401void InnerLoopVectorizer::predicateInstructions() {
4402
4403 // For each instruction I marked for predication on value C, split I into its
4404 // own basic block to form an if-then construct over C. Since I may be fed by
4405 // an extractelement instruction or other scalar operand, we try to
4406 // iteratively sink its scalar operands into the predicated block. If I feeds
4407 // an insertelement instruction, we try to move this instruction into the
4408 // predicated block as well. For non-void types, a phi node will be created
4409 // for the resulting value (either vector or scalar).
4410 //
4411 // So for some predicated instruction, e.g. the conditional sdiv in:
4412 //
4413 // for.body:
4414 // ...
4415 // %add = add nsw i32 %mul, %0
4416 // %cmp5 = icmp sgt i32 %2, 7
4417 // br i1 %cmp5, label %if.then, label %if.end
4418 //
4419 // if.then:
4420 // %div = sdiv i32 %0, %1
4421 // br label %if.end
4422 //
4423 // if.end:
4424 // %x.0 = phi i32 [ %div, %if.then ], [ %add, %for.body ]
4425 //
4426 // the sdiv at this point is scalarized and if-converted using a select.
4427 // The inactive elements in the vector are not used, but the predicated
4428 // instruction is still executed for all vector elements, essentially:
4429 //
4430 // vector.body:
4431 // ...
4432 // %17 = add nsw <2 x i32> %16, %wide.load
4433 // %29 = extractelement <2 x i32> %wide.load, i32 0
4434 // %30 = extractelement <2 x i32> %wide.load51, i32 0
4435 // %31 = sdiv i32 %29, %30
4436 // %32 = insertelement <2 x i32> undef, i32 %31, i32 0
4437 // %35 = extractelement <2 x i32> %wide.load, i32 1
4438 // %36 = extractelement <2 x i32> %wide.load51, i32 1
4439 // %37 = sdiv i32 %35, %36
4440 // %38 = insertelement <2 x i32> %32, i32 %37, i32 1
4441 // %predphi = select <2 x i1> %26, <2 x i32> %38, <2 x i32> %17
4442 //
4443 // Predication will now re-introduce the original control flow to avoid false
4444 // side-effects by the sdiv instructions on the inactive elements, yielding
4445 // (after cleanup):
4446 //
4447 // vector.body:
4448 // ...
4449 // %5 = add nsw <2 x i32> %4, %wide.load
4450 // %8 = icmp sgt <2 x i32> %wide.load52, <i32 7, i32 7>
4451 // %9 = extractelement <2 x i1> %8, i32 0
4452 // br i1 %9, label %pred.sdiv.if, label %pred.sdiv.continue
4453 //
4454 // pred.sdiv.if:
4455 // %10 = extractelement <2 x i32> %wide.load, i32 0
4456 // %11 = extractelement <2 x i32> %wide.load51, i32 0
4457 // %12 = sdiv i32 %10, %11
4458 // %13 = insertelement <2 x i32> undef, i32 %12, i32 0
4459 // br label %pred.sdiv.continue
4460 //
4461 // pred.sdiv.continue:
4462 // %14 = phi <2 x i32> [ undef, %vector.body ], [ %13, %pred.sdiv.if ]
4463 // %15 = extractelement <2 x i1> %8, i32 1
4464 // br i1 %15, label %pred.sdiv.if54, label %pred.sdiv.continue55
4465 //
4466 // pred.sdiv.if54:
4467 // %16 = extractelement <2 x i32> %wide.load, i32 1
4468 // %17 = extractelement <2 x i32> %wide.load51, i32 1
4469 // %18 = sdiv i32 %16, %17
4470 // %19 = insertelement <2 x i32> %14, i32 %18, i32 1
4471 // br label %pred.sdiv.continue55
4472 //
4473 // pred.sdiv.continue55:
4474 // %20 = phi <2 x i32> [ %14, %pred.sdiv.continue ], [ %19, %pred.sdiv.if54 ]
4475 // %predphi = select <2 x i1> %8, <2 x i32> %20, <2 x i32> %5
4476
4477 for (auto KV : PredicatedInstructions) {
4478 BasicBlock::iterator I(KV.first);
4479 BasicBlock *Head = I->getParent();
4480 auto *T = SplitBlockAndInsertIfThen(KV.second, &*I, /*Unreachable=*/false,
4481 /*BranchWeights=*/nullptr, DT, LI);
4482 I->moveBefore(T);
4483 sinkScalarOperands(&*I);
4484
4485 BasicBlock *PredicatedBlock = I->getParent();
4486 Twine BBNamePrefix = Twine("pred.") + I->getOpcodeName();
4487 PredicatedBlock->setName(BBNamePrefix + ".if");
4488 PredicatedBlock->getSingleSuccessor()->setName(BBNamePrefix + ".continue");
4489
4490 // If the instruction is non-void create a Phi node at reconvergence point.
4491 if (!I->getType()->isVoidTy()) {
4492 Value *IncomingTrue = nullptr;
4493 Value *IncomingFalse = nullptr;
4494
4495 if (I->hasOneUse() && isa<InsertElementInst>(*I->user_begin())) {
4496 // If the predicated instruction is feeding an insert-element, move it
4497 // into the Then block; Phi node will be created for the vector.
4498 InsertElementInst *IEI = cast<InsertElementInst>(*I->user_begin());
4499 IEI->moveBefore(T);
4500 IncomingTrue = IEI; // the new vector with the inserted element.
4501 IncomingFalse = IEI->getOperand(0); // the unmodified vector
4502 } else {
4503 // Phi node will be created for the scalar predicated instruction.
4504 IncomingTrue = &*I;
4505 IncomingFalse = UndefValue::get(I->getType());
4506 }
4507
4508 BasicBlock *PostDom = I->getParent()->getSingleSuccessor();
4509 assert(PostDom && "Then block has multiple successors")((PostDom && "Then block has multiple successors") ? static_cast
<void> (0) : __assert_fail ("PostDom && \"Then block has multiple successors\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4509, __PRETTY_FUNCTION__))
;
4510 PHINode *Phi =
4511 PHINode::Create(IncomingTrue->getType(), 2, "", &PostDom->front());
4512 IncomingTrue->replaceAllUsesWith(Phi);
4513 Phi->addIncoming(IncomingFalse, Head);
4514 Phi->addIncoming(IncomingTrue, I->getParent());
4515 }
4516 }
4517
4518 DEBUG(DT->verifyDomTree())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { DT->verifyDomTree(); } } while (false
)
;
4519}
4520
4521InnerLoopVectorizer::VectorParts
4522InnerLoopVectorizer::createEdgeMask(BasicBlock *Src, BasicBlock *Dst) {
4523 assert(is_contained(predecessors(Dst), Src) && "Invalid edge")((is_contained(predecessors(Dst), Src) && "Invalid edge"
) ? static_cast<void> (0) : __assert_fail ("is_contained(predecessors(Dst), Src) && \"Invalid edge\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4523, __PRETTY_FUNCTION__))
;
4524
4525 // Look for cached value.
4526 std::pair<BasicBlock *, BasicBlock *> Edge(Src, Dst);
4527 EdgeMaskCacheTy::iterator ECEntryIt = EdgeMaskCache.find(Edge);
4528 if (ECEntryIt != EdgeMaskCache.end())
4529 return ECEntryIt->second;
4530
4531 VectorParts SrcMask = createBlockInMask(Src);
4532
4533 // The terminator has to be a branch inst!
4534 BranchInst *BI = dyn_cast<BranchInst>(Src->getTerminator());
4535 assert(BI && "Unexpected terminator found")((BI && "Unexpected terminator found") ? static_cast<
void> (0) : __assert_fail ("BI && \"Unexpected terminator found\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4535, __PRETTY_FUNCTION__))
;
4536
4537 if (BI->isConditional()) {
4538
4539 VectorParts EdgeMask(UF);
4540 for (unsigned Part = 0; Part < UF; ++Part) {
4541 auto *EdgeMaskPart = getOrCreateVectorValue(BI->getCondition(), Part);
4542 if (BI->getSuccessor(0) != Dst)
4543 EdgeMaskPart = Builder.CreateNot(EdgeMaskPart);
4544
4545 EdgeMaskPart = Builder.CreateAnd(EdgeMaskPart, SrcMask[Part]);
4546 EdgeMask[Part] = EdgeMaskPart;
4547 }
4548
4549 EdgeMaskCache[Edge] = EdgeMask;
4550 return EdgeMask;
4551 }
4552
4553 EdgeMaskCache[Edge] = SrcMask;
4554 return SrcMask;
4555}
4556
4557InnerLoopVectorizer::VectorParts
4558InnerLoopVectorizer::createBlockInMask(BasicBlock *BB) {
4559 assert(OrigLoop->contains(BB) && "Block is not a part of a loop")((OrigLoop->contains(BB) && "Block is not a part of a loop"
) ? static_cast<void> (0) : __assert_fail ("OrigLoop->contains(BB) && \"Block is not a part of a loop\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4559, __PRETTY_FUNCTION__))
;
4560
4561 // Look for cached value.
4562 BlockMaskCacheTy::iterator BCEntryIt = BlockMaskCache.find(BB);
4563 if (BCEntryIt != BlockMaskCache.end())
4564 return BCEntryIt->second;
4565
4566 VectorParts BlockMask(UF);
4567
4568 // Loop incoming mask is all-one.
4569 if (OrigLoop->getHeader() == BB) {
4570 Value *C = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 1);
4571 for (unsigned Part = 0; Part < UF; ++Part)
4572 BlockMask[Part] = getOrCreateVectorValue(C, Part);
4573 BlockMaskCache[BB] = BlockMask;
4574 return BlockMask;
4575 }
4576
4577 // This is the block mask. We OR all incoming edges, and with zero.
4578 Value *Zero = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 0);
4579 for (unsigned Part = 0; Part < UF; ++Part)
4580 BlockMask[Part] = getOrCreateVectorValue(Zero, Part);
4581
4582 // For each pred:
4583 for (pred_iterator It = pred_begin(BB), E = pred_end(BB); It != E; ++It) {
4584 VectorParts EM = createEdgeMask(*It, BB);
4585 for (unsigned Part = 0; Part < UF; ++Part)
4586 BlockMask[Part] = Builder.CreateOr(BlockMask[Part], EM[Part]);
4587 }
4588
4589 BlockMaskCache[BB] = BlockMask;
4590 return BlockMask;
4591}
4592
4593void InnerLoopVectorizer::widenPHIInstruction(Instruction *PN, unsigned UF,
4594 unsigned VF) {
4595 PHINode *P = cast<PHINode>(PN);
4596 // In order to support recurrences we need to be able to vectorize Phi nodes.
4597 // Phi nodes have cycles, so we need to vectorize them in two stages. This is
4598 // stage #1: We create a new vector PHI node with no incoming edges. We'll use
4599 // this value when we vectorize all of the instructions that use the PHI.
4600 if (Legal->isReductionVariable(P) || Legal->isFirstOrderRecurrence(P)) {
4601 for (unsigned Part = 0; Part < UF; ++Part) {
4602 // This is phase one of vectorizing PHIs.
4603 Type *VecTy =
4604 (VF == 1) ? PN->getType() : VectorType::get(PN->getType(), VF);
4605 Value *EntryPart = PHINode::Create(
4606 VecTy, 2, "vec.phi", &*LoopVectorBody->getFirstInsertionPt());
4607 VectorLoopValueMap.setVectorValue(P, Part, EntryPart);
4608 }
4609 return;
4610 }
4611
4612 setDebugLocFromInst(Builder, P);
4613 // Check for PHI nodes that are lowered to vector selects.
4614 if (P->getParent() != OrigLoop->getHeader()) {
4615 // We know that all PHIs in non-header blocks are converted into
4616 // selects, so we don't have to worry about the insertion order and we
4617 // can just use the builder.
4618 // At this point we generate the predication tree. There may be
4619 // duplications since this is a simple recursive scan, but future
4620 // optimizations will clean it up.
4621
4622 unsigned NumIncoming = P->getNumIncomingValues();
4623
4624 // Generate a sequence of selects of the form:
4625 // SELECT(Mask3, In3,
4626 // SELECT(Mask2, In2,
4627 // ( ...)))
4628 VectorParts Entry(UF);
4629 for (unsigned In = 0; In < NumIncoming; In++) {
4630 VectorParts Cond =
4631 createEdgeMask(P->getIncomingBlock(In), P->getParent());
4632
4633 for (unsigned Part = 0; Part < UF; ++Part) {
4634 Value *In0 = getOrCreateVectorValue(P->getIncomingValue(In), Part);
4635 // We might have single edge PHIs (blocks) - use an identity
4636 // 'select' for the first PHI operand.
4637 if (In == 0)
4638 Entry[Part] = Builder.CreateSelect(Cond[Part], In0, In0);
4639 else
4640 // Select between the current value and the previous incoming edge
4641 // based on the incoming mask.
4642 Entry[Part] = Builder.CreateSelect(Cond[Part], In0, Entry[Part],
4643 "predphi");
4644 }
4645 }
4646 for (unsigned Part = 0; Part < UF; ++Part)
4647 VectorLoopValueMap.setVectorValue(P, Part, Entry[Part]);
4648 return;
4649 }
4650
4651 // This PHINode must be an induction variable.
4652 // Make sure that we know about it.
4653 assert(Legal->getInductionVars()->count(P) && "Not an induction variable")((Legal->getInductionVars()->count(P) && "Not an induction variable"
) ? static_cast<void> (0) : __assert_fail ("Legal->getInductionVars()->count(P) && \"Not an induction variable\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4653, __PRETTY_FUNCTION__))
;
4654
4655 InductionDescriptor II = Legal->getInductionVars()->lookup(P);
4656 const DataLayout &DL = OrigLoop->getHeader()->getModule()->getDataLayout();
4657
4658 // FIXME: The newly created binary instructions should contain nsw/nuw flags,
4659 // which can be found from the original scalar operations.
4660 switch (II.getKind()) {
4661 case InductionDescriptor::IK_NoInduction:
4662 llvm_unreachable("Unknown induction")::llvm::llvm_unreachable_internal("Unknown induction", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4662)
;
4663 case InductionDescriptor::IK_IntInduction:
4664 case InductionDescriptor::IK_FpInduction:
4665 return widenIntOrFpInduction(P);
4666 case InductionDescriptor::IK_PtrInduction: {
4667 // Handle the pointer induction variable case.
4668 assert(P->getType()->isPointerTy() && "Unexpected type.")((P->getType()->isPointerTy() && "Unexpected type."
) ? static_cast<void> (0) : __assert_fail ("P->getType()->isPointerTy() && \"Unexpected type.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4668, __PRETTY_FUNCTION__))
;
4669 // This is the normalized GEP that starts counting at zero.
4670 Value *PtrInd = Induction;
4671 PtrInd = Builder.CreateSExtOrTrunc(PtrInd, II.getStep()->getType());
4672 // Determine the number of scalars we need to generate for each unroll
4673 // iteration. If the instruction is uniform, we only need to generate the
4674 // first lane. Otherwise, we generate all VF values.
4675 unsigned Lanes = Cost->isUniformAfterVectorization(P, VF) ? 1 : VF;
4676 // These are the scalar results. Notice that we don't generate vector GEPs
4677 // because scalar GEPs result in better code.
4678 for (unsigned Part = 0; Part < UF; ++Part) {
4679 for (unsigned Lane = 0; Lane < Lanes; ++Lane) {
4680 Constant *Idx = ConstantInt::get(PtrInd->getType(), Lane + Part * VF);
4681 Value *GlobalIdx = Builder.CreateAdd(PtrInd, Idx);
4682 Value *SclrGep = II.transform(Builder, GlobalIdx, PSE.getSE(), DL);
4683 SclrGep->setName("next.gep");
4684 VectorLoopValueMap.setScalarValue(P, Part, Lane, SclrGep);
4685 }
4686 }
4687 return;
4688 }
4689 }
4690}
4691
4692/// A helper function for checking whether an integer division-related
4693/// instruction may divide by zero (in which case it must be predicated if
4694/// executed conditionally in the scalar code).
4695/// TODO: It may be worthwhile to generalize and check isKnownNonZero().
4696/// Non-zero divisors that are non compile-time constants will not be
4697/// converted into multiplication, so we will still end up scalarizing
4698/// the division, but can do so w/o predication.
4699static bool mayDivideByZero(Instruction &I) {
4700 assert((I.getOpcode() == Instruction::UDiv ||(((I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction
::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode()
== Instruction::SRem) && "Unexpected instruction") ?
static_cast<void> (0) : __assert_fail ("(I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode() == Instruction::SRem) && \"Unexpected instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4704, __PRETTY_FUNCTION__))
4701 I.getOpcode() == Instruction::SDiv ||(((I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction
::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode()
== Instruction::SRem) && "Unexpected instruction") ?
static_cast<void> (0) : __assert_fail ("(I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode() == Instruction::SRem) && \"Unexpected instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4704, __PRETTY_FUNCTION__))
4702 I.getOpcode() == Instruction::URem ||(((I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction
::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode()
== Instruction::SRem) && "Unexpected instruction") ?
static_cast<void> (0) : __assert_fail ("(I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode() == Instruction::SRem) && \"Unexpected instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4704, __PRETTY_FUNCTION__))
4703 I.getOpcode() == Instruction::SRem) &&(((I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction
::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode()
== Instruction::SRem) && "Unexpected instruction") ?
static_cast<void> (0) : __assert_fail ("(I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode() == Instruction::SRem) && \"Unexpected instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4704, __PRETTY_FUNCTION__))
4704 "Unexpected instruction")(((I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction
::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode()
== Instruction::SRem) && "Unexpected instruction") ?
static_cast<void> (0) : __assert_fail ("(I.getOpcode() == Instruction::UDiv || I.getOpcode() == Instruction::SDiv || I.getOpcode() == Instruction::URem || I.getOpcode() == Instruction::SRem) && \"Unexpected instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4704, __PRETTY_FUNCTION__))
;
4705 Value *Divisor = I.getOperand(1);
4706 auto *CInt = dyn_cast<ConstantInt>(Divisor);
4707 return !CInt || CInt->isZero();
4708}
4709
4710void InnerLoopVectorizer::vectorizeInstruction(Instruction &I) {
4711 // Scalarize instructions that should remain scalar after vectorization.
4712 if (VF > 1 &&
4713 !(isa<BranchInst>(&I) || isa<PHINode>(&I) || isa<DbgInfoIntrinsic>(&I)) &&
4714 shouldScalarizeInstruction(&I)) {
4715 scalarizeInstruction(&I, Legal->isScalarWithPredication(&I));
4716 return;
4717 }
4718
4719 switch (I.getOpcode()) {
4720 case Instruction::Br:
4721 // Nothing to do for PHIs and BR, since we already took care of the
4722 // loop control flow instructions.
4723 break;
4724 case Instruction::PHI: {
4725 // Vectorize PHINodes.
4726 widenPHIInstruction(&I, UF, VF);
4727 break;
4728 } // End of PHI.
4729 case Instruction::GetElementPtr: {
4730 // Construct a vector GEP by widening the operands of the scalar GEP as
4731 // necessary. We mark the vector GEP 'inbounds' if appropriate. A GEP
4732 // results in a vector of pointers when at least one operand of the GEP
4733 // is vector-typed. Thus, to keep the representation compact, we only use
4734 // vector-typed operands for loop-varying values.
4735 auto *GEP = cast<GetElementPtrInst>(&I);
4736
4737 if (VF > 1 && OrigLoop->hasLoopInvariantOperands(GEP)) {
4738 // If we are vectorizing, but the GEP has only loop-invariant operands,
4739 // the GEP we build (by only using vector-typed operands for
4740 // loop-varying values) would be a scalar pointer. Thus, to ensure we
4741 // produce a vector of pointers, we need to either arbitrarily pick an
4742 // operand to broadcast, or broadcast a clone of the original GEP.
4743 // Here, we broadcast a clone of the original.
4744 //
4745 // TODO: If at some point we decide to scalarize instructions having
4746 // loop-invariant operands, this special case will no longer be
4747 // required. We would add the scalarization decision to
4748 // collectLoopScalars() and teach getVectorValue() to broadcast
4749 // the lane-zero scalar value.
4750 auto *Clone = Builder.Insert(GEP->clone());
4751 for (unsigned Part = 0; Part < UF; ++Part) {
4752 Value *EntryPart = Builder.CreateVectorSplat(VF, Clone);
4753 VectorLoopValueMap.setVectorValue(&I, Part, EntryPart);
4754 addMetadata(EntryPart, GEP);
4755 }
4756 } else {
4757 // If the GEP has at least one loop-varying operand, we are sure to
4758 // produce a vector of pointers. But if we are only unrolling, we want
4759 // to produce a scalar GEP for each unroll part. Thus, the GEP we
4760 // produce with the code below will be scalar (if VF == 1) or vector
4761 // (otherwise). Note that for the unroll-only case, we still maintain
4762 // values in the vector mapping with initVector, as we do for other
4763 // instructions.
4764 for (unsigned Part = 0; Part < UF; ++Part) {
4765
4766 // The pointer operand of the new GEP. If it's loop-invariant, we
4767 // won't broadcast it.
4768 auto *Ptr =
4769 OrigLoop->isLoopInvariant(GEP->getPointerOperand())
4770 ? GEP->getPointerOperand()
4771 : getOrCreateVectorValue(GEP->getPointerOperand(), Part);
4772
4773 // Collect all the indices for the new GEP. If any index is
4774 // loop-invariant, we won't broadcast it.
4775 SmallVector<Value *, 4> Indices;
4776 for (auto &U : make_range(GEP->idx_begin(), GEP->idx_end())) {
4777 if (OrigLoop->isLoopInvariant(U.get()))
4778 Indices.push_back(U.get());
4779 else
4780 Indices.push_back(getOrCreateVectorValue(U.get(), Part));
4781 }
4782
4783 // Create the new GEP. Note that this GEP may be a scalar if VF == 1,
4784 // but it should be a vector, otherwise.
4785 auto *NewGEP = GEP->isInBounds()
4786 ? Builder.CreateInBoundsGEP(Ptr, Indices)
4787 : Builder.CreateGEP(Ptr, Indices);
4788 assert((VF == 1 || NewGEP->getType()->isVectorTy()) &&(((VF == 1 || NewGEP->getType()->isVectorTy()) &&
"NewGEP is not a pointer vector") ? static_cast<void> (
0) : __assert_fail ("(VF == 1 || NewGEP->getType()->isVectorTy()) && \"NewGEP is not a pointer vector\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4789, __PRETTY_FUNCTION__))
4789 "NewGEP is not a pointer vector")(((VF == 1 || NewGEP->getType()->isVectorTy()) &&
"NewGEP is not a pointer vector") ? static_cast<void> (
0) : __assert_fail ("(VF == 1 || NewGEP->getType()->isVectorTy()) && \"NewGEP is not a pointer vector\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4789, __PRETTY_FUNCTION__))
;
4790 VectorLoopValueMap.setVectorValue(&I, Part, NewGEP);
4791 addMetadata(NewGEP, GEP);
4792 }
4793 }
4794
4795 break;
4796 }
4797 case Instruction::UDiv:
4798 case Instruction::SDiv:
4799 case Instruction::SRem:
4800 case Instruction::URem:
4801 // Scalarize with predication if this instruction may divide by zero and
4802 // block execution is conditional, otherwise fallthrough.
4803 if (Legal->isScalarWithPredication(&I)) {
4804 scalarizeInstruction(&I, true);
4805 break;
4806 }
4807 LLVM_FALLTHROUGH[[clang::fallthrough]];
4808 case Instruction::Add:
4809 case Instruction::FAdd:
4810 case Instruction::Sub:
4811 case Instruction::FSub:
4812 case Instruction::Mul:
4813 case Instruction::FMul:
4814 case Instruction::FDiv:
4815 case Instruction::FRem:
4816 case Instruction::Shl:
4817 case Instruction::LShr:
4818 case Instruction::AShr:
4819 case Instruction::And:
4820 case Instruction::Or:
4821 case Instruction::Xor: {
4822 // Just widen binops.
4823 auto *BinOp = cast<BinaryOperator>(&I);
4824 setDebugLocFromInst(Builder, BinOp);
4825
4826 for (unsigned Part = 0; Part < UF; ++Part) {
4827 Value *A = getOrCreateVectorValue(BinOp->getOperand(0), Part);
4828 Value *B = getOrCreateVectorValue(BinOp->getOperand(1), Part);
4829 Value *V = Builder.CreateBinOp(BinOp->getOpcode(), A, B);
4830
4831 if (BinaryOperator *VecOp = dyn_cast<BinaryOperator>(V))
4832 VecOp->copyIRFlags(BinOp);
4833
4834 // Use this vector value for all users of the original instruction.
4835 VectorLoopValueMap.setVectorValue(&I, Part, V);
4836 addMetadata(V, BinOp);
4837 }
4838
4839 break;
4840 }
4841 case Instruction::Select: {
4842 // Widen selects.
4843 // If the selector is loop invariant we can create a select
4844 // instruction with a scalar condition. Otherwise, use vector-select.
4845 auto *SE = PSE.getSE();
4846 bool InvariantCond =
4847 SE->isLoopInvariant(PSE.getSCEV(I.getOperand(0)), OrigLoop);
4848 setDebugLocFromInst(Builder, &I);
4849
4850 // The condition can be loop invariant but still defined inside the
4851 // loop. This means that we can't just use the original 'cond' value.
4852 // We have to take the 'vectorized' value and pick the first lane.
4853 // Instcombine will make this a no-op.
4854
4855 auto *ScalarCond = getOrCreateScalarValue(I.getOperand(0), 0, 0);
4856
4857 for (unsigned Part = 0; Part < UF; ++Part) {
4858 Value *Cond = getOrCreateVectorValue(I.getOperand(0), Part);
4859 Value *Op0 = getOrCreateVectorValue(I.getOperand(1), Part);
4860 Value *Op1 = getOrCreateVectorValue(I.getOperand(2), Part);
4861 Value *Sel =
4862 Builder.CreateSelect(InvariantCond ? ScalarCond : Cond, Op0, Op1);
4863 VectorLoopValueMap.setVectorValue(&I, Part, Sel);
4864 addMetadata(Sel, &I);
4865 }
4866
4867 break;
4868 }
4869
4870 case Instruction::ICmp:
4871 case Instruction::FCmp: {
4872 // Widen compares. Generate vector compares.
4873 bool FCmp = (I.getOpcode() == Instruction::FCmp);
4874 auto *Cmp = dyn_cast<CmpInst>(&I);
4875 setDebugLocFromInst(Builder, Cmp);
4876 for (unsigned Part = 0; Part < UF; ++Part) {
4877 Value *A = getOrCreateVectorValue(Cmp->getOperand(0), Part);
4878 Value *B = getOrCreateVectorValue(Cmp->getOperand(1), Part);
4879 Value *C = nullptr;
4880 if (FCmp) {
4881 C = Builder.CreateFCmp(Cmp->getPredicate(), A, B);
4882 cast<FCmpInst>(C)->copyFastMathFlags(Cmp);
4883 } else {
4884 C = Builder.CreateICmp(Cmp->getPredicate(), A, B);
4885 }
4886 VectorLoopValueMap.setVectorValue(&I, Part, C);
4887 addMetadata(C, &I);
4888 }
4889
4890 break;
4891 }
4892
4893 case Instruction::Store:
4894 case Instruction::Load:
4895 vectorizeMemoryInstruction(&I);
4896 break;
4897 case Instruction::ZExt:
4898 case Instruction::SExt:
4899 case Instruction::FPToUI:
4900 case Instruction::FPToSI:
4901 case Instruction::FPExt:
4902 case Instruction::PtrToInt:
4903 case Instruction::IntToPtr:
4904 case Instruction::SIToFP:
4905 case Instruction::UIToFP:
4906 case Instruction::Trunc:
4907 case Instruction::FPTrunc:
4908 case Instruction::BitCast: {
4909 auto *CI = dyn_cast<CastInst>(&I);
4910 setDebugLocFromInst(Builder, CI);
4911
4912 // Optimize the special case where the source is a constant integer
4913 // induction variable. Notice that we can only optimize the 'trunc' case
4914 // because (a) FP conversions lose precision, (b) sext/zext may wrap, and
4915 // (c) other casts depend on pointer size.
4916 if (Cost->isOptimizableIVTruncate(CI, VF)) {
4917 widenIntOrFpInduction(cast<PHINode>(CI->getOperand(0)),
4918 cast<TruncInst>(CI));
4919 break;
4920 }
4921
4922 /// Vectorize casts.
4923 Type *DestTy =
4924 (VF == 1) ? CI->getType() : VectorType::get(CI->getType(), VF);
4925
4926 for (unsigned Part = 0; Part < UF; ++Part) {
4927 Value *A = getOrCreateVectorValue(CI->getOperand(0), Part);
4928 Value *Cast = Builder.CreateCast(CI->getOpcode(), A, DestTy);
4929 VectorLoopValueMap.setVectorValue(&I, Part, Cast);
4930 addMetadata(Cast, &I);
4931 }
4932 break;
4933 }
4934
4935 case Instruction::Call: {
4936 // Ignore dbg intrinsics.
4937 if (isa<DbgInfoIntrinsic>(I))
4938 break;
4939 setDebugLocFromInst(Builder, &I);
4940
4941 Module *M = I.getParent()->getParent()->getParent();
4942 auto *CI = cast<CallInst>(&I);
4943
4944 StringRef FnName = CI->getCalledFunction()->getName();
4945 Function *F = CI->getCalledFunction();
4946 Type *RetTy = ToVectorTy(CI->getType(), VF);
4947 SmallVector<Type *, 4> Tys;
4948 for (Value *ArgOperand : CI->arg_operands())
4949 Tys.push_back(ToVectorTy(ArgOperand->getType(), VF));
4950
4951 Intrinsic::ID ID = getVectorIntrinsicIDForCall(CI, TLI);
4952 if (ID && (ID == Intrinsic::assume || ID == Intrinsic::lifetime_end ||
4953 ID == Intrinsic::lifetime_start)) {
4954 scalarizeInstruction(&I);
4955 break;
4956 }
4957 // The flag shows whether we use Intrinsic or a usual Call for vectorized
4958 // version of the instruction.
4959 // Is it beneficial to perform intrinsic call compared to lib call?
4960 bool NeedToScalarize;
4961 unsigned CallCost = getVectorCallCost(CI, VF, *TTI, TLI, NeedToScalarize);
4962 bool UseVectorIntrinsic =
4963 ID && getVectorIntrinsicCost(CI, VF, *TTI, TLI) <= CallCost;
4964 if (!UseVectorIntrinsic && NeedToScalarize) {
4965 scalarizeInstruction(&I);
4966 break;
4967 }
4968
4969 for (unsigned Part = 0; Part < UF; ++Part) {
4970 SmallVector<Value *, 4> Args;
4971 for (unsigned i = 0, ie = CI->getNumArgOperands(); i != ie; ++i) {
4972 Value *Arg = CI->getArgOperand(i);
4973 // Some intrinsics have a scalar argument - don't replace it with a
4974 // vector.
4975 if (!UseVectorIntrinsic || !hasVectorInstrinsicScalarOpd(ID, i))
4976 Arg = getOrCreateVectorValue(CI->getArgOperand(i), Part);
4977 Args.push_back(Arg);
4978 }
4979
4980 Function *VectorF;
4981 if (UseVectorIntrinsic) {
4982 // Use vector version of the intrinsic.
4983 Type *TysForDecl[] = {CI->getType()};
4984 if (VF > 1)
4985 TysForDecl[0] = VectorType::get(CI->getType()->getScalarType(), VF);
4986 VectorF = Intrinsic::getDeclaration(M, ID, TysForDecl);
4987 } else {
4988 // Use vector version of the library call.
4989 StringRef VFnName = TLI->getVectorizedFunction(FnName, VF);
4990 assert(!VFnName.empty() && "Vector function name is empty.")((!VFnName.empty() && "Vector function name is empty."
) ? static_cast<void> (0) : __assert_fail ("!VFnName.empty() && \"Vector function name is empty.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4990, __PRETTY_FUNCTION__))
;
4991 VectorF = M->getFunction(VFnName);
4992 if (!VectorF) {
4993 // Generate a declaration
4994 FunctionType *FTy = FunctionType::get(RetTy, Tys, false);
4995 VectorF =
4996 Function::Create(FTy, Function::ExternalLinkage, VFnName, M);
4997 VectorF->copyAttributesFrom(F);
4998 }
4999 }
5000 assert(VectorF && "Can't create vector function.")((VectorF && "Can't create vector function.") ? static_cast
<void> (0) : __assert_fail ("VectorF && \"Can't create vector function.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5000, __PRETTY_FUNCTION__))
;
5001
5002 SmallVector<OperandBundleDef, 1> OpBundles;
5003 CI->getOperandBundlesAsDefs(OpBundles);
5004 CallInst *V = Builder.CreateCall(VectorF, Args, OpBundles);
5005
5006 if (isa<FPMathOperator>(V))
5007 V->copyFastMathFlags(CI);
5008
5009 VectorLoopValueMap.setVectorValue(&I, Part, V);
5010 addMetadata(V, &I);
5011 }
5012
5013 break;
5014 }
5015
5016 default:
5017 // All other instructions are unsupported. Scalarize them.
5018 scalarizeInstruction(&I);
5019 break;
5020 } // end of switch.
5021}
5022
5023void InnerLoopVectorizer::updateAnalysis() {
5024 // Forget the original basic block.
5025 PSE.getSE()->forgetLoop(OrigLoop);
5026
5027 // Update the dominator tree information.
5028 assert(DT->properlyDominates(LoopBypassBlocks.front(), LoopExitBlock) &&((DT->properlyDominates(LoopBypassBlocks.front(), LoopExitBlock
) && "Entry does not dominate exit.") ? static_cast<
void> (0) : __assert_fail ("DT->properlyDominates(LoopBypassBlocks.front(), LoopExitBlock) && \"Entry does not dominate exit.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5029, __PRETTY_FUNCTION__))
5029 "Entry does not dominate exit.")((DT->properlyDominates(LoopBypassBlocks.front(), LoopExitBlock
) && "Entry does not dominate exit.") ? static_cast<
void> (0) : __assert_fail ("DT->properlyDominates(LoopBypassBlocks.front(), LoopExitBlock) && \"Entry does not dominate exit.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5029, __PRETTY_FUNCTION__))
;
5030
5031 DT->addNewBlock(LI->getLoopFor(LoopVectorBody)->getHeader(),
5032 LoopVectorPreHeader);
5033 DT->addNewBlock(LoopMiddleBlock,
5034 LI->getLoopFor(LoopVectorBody)->getLoopLatch());
5035 DT->addNewBlock(LoopScalarPreHeader, LoopBypassBlocks[0]);
5036 DT->changeImmediateDominator(LoopScalarBody, LoopScalarPreHeader);
5037 DT->changeImmediateDominator(LoopExitBlock, LoopBypassBlocks[0]);
5038
5039 DEBUG(DT->verifyDomTree())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { DT->verifyDomTree(); } } while (false
)
;
5040}
5041
5042/// \brief Check whether it is safe to if-convert this phi node.
5043///
5044/// Phi nodes with constant expressions that can trap are not safe to if
5045/// convert.
5046static bool canIfConvertPHINodes(BasicBlock *BB) {
5047 for (Instruction &I : *BB) {
5048 auto *Phi = dyn_cast<PHINode>(&I);
5049 if (!Phi)
5050 return true;
5051 for (Value *V : Phi->incoming_values())
5052 if (auto *C = dyn_cast<Constant>(V))
5053 if (C->canTrap())
5054 return false;
5055 }
5056 return true;
5057}
5058
5059bool LoopVectorizationLegality::canVectorizeWithIfConvert() {
5060 if (!EnableIfConversion) {
5061 ORE->emit(createMissedAnalysis("IfConversionDisabled")
5062 << "if-conversion is disabled");
5063 return false;
5064 }
5065
5066 assert(TheLoop->getNumBlocks() > 1 && "Single block loops are vectorizable")((TheLoop->getNumBlocks() > 1 && "Single block loops are vectorizable"
) ? static_cast<void> (0) : __assert_fail ("TheLoop->getNumBlocks() > 1 && \"Single block loops are vectorizable\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5066, __PRETTY_FUNCTION__))
;
5067
5068 // A list of pointers that we can safely read and write to.
5069 SmallPtrSet<Value *, 8> SafePointes;
5070
5071 // Collect safe addresses.
5072 for (BasicBlock *BB : TheLoop->blocks()) {
5073 if (blockNeedsPredication(BB))
5074 continue;
5075
5076 for (Instruction &I : *BB)
5077 if (auto *Ptr = getPointerOperand(&I))
5078 SafePointes.insert(Ptr);
5079 }
5080
5081 // Collect the blocks that need predication.
5082 BasicBlock *Header = TheLoop->getHeader();
5083 for (BasicBlock *BB : TheLoop->blocks()) {
5084 // We don't support switch statements inside loops.
5085 if (!isa<BranchInst>(BB->getTerminator())) {
5086 ORE->emit(createMissedAnalysis("LoopContainsSwitch", BB->getTerminator())
5087 << "loop contains a switch statement");
5088 return false;
5089 }
5090
5091 // We must be able to predicate all blocks that need to be predicated.
5092 if (blockNeedsPredication(BB)) {
5093 if (!blockCanBePredicated(BB, SafePointes)) {
5094 ORE->emit(createMissedAnalysis("NoCFGForSelect", BB->getTerminator())
5095 << "control flow cannot be substituted for a select");
5096 return false;
5097 }
5098 } else if (BB != Header && !canIfConvertPHINodes(BB)) {
5099 ORE->emit(createMissedAnalysis("NoCFGForSelect", BB->getTerminator())
5100 << "control flow cannot be substituted for a select");
5101 return false;
5102 }
5103 }
5104
5105 // We can if-convert this loop.
5106 return true;
5107}
5108
5109bool LoopVectorizationLegality::canVectorize() {
5110 // Store the result and return it at the end instead of exiting early, in case
5111 // allowExtraAnalysis is used to report multiple reasons for not vectorizing.
5112 bool Result = true;
5113 // We must have a loop in canonical form. Loops with indirectbr in them cannot
5114 // be canonicalized.
5115 if (!TheLoop->getLoopPreheader()) {
5116 ORE->emit(createMissedAnalysis("CFGNotUnderstood")
5117 << "loop control flow is not understood by vectorizer");
5118 if (ORE->allowExtraAnalysis())
5119 Result = false;
5120 else
5121 return false;
5122 }
5123
5124 // FIXME: The code is currently dead, since the loop gets sent to
5125 // LoopVectorizationLegality is already an innermost loop.
5126 //
5127 // We can only vectorize innermost loops.
5128 if (!TheLoop->empty()) {
5129 ORE->emit(createMissedAnalysis("NotInnermostLoop")
5130 << "loop is not the innermost loop");
5131 if (ORE->allowExtraAnalysis())
5132 Result = false;
5133 else
5134 return false;
5135 }
5136
5137 // We must have a single backedge.
5138 if (TheLoop->getNumBackEdges() != 1) {
5139 ORE->emit(createMissedAnalysis("CFGNotUnderstood")
5140 << "loop control flow is not understood by vectorizer");
5141 if (ORE->allowExtraAnalysis())
5142 Result = false;
5143 else
5144 return false;
5145 }
5146
5147 // We must have a single exiting block.
5148 if (!TheLoop->getExitingBlock()) {
5149 ORE->emit(createMissedAnalysis("CFGNotUnderstood")
5150 << "loop control flow is not understood by vectorizer");
5151 if (ORE->allowExtraAnalysis())
5152 Result = false;
5153 else
5154 return false;
5155 }
5156
5157 // We only handle bottom-tested loops, i.e. loop in which the condition is
5158 // checked at the end of each iteration. With that we can assume that all
5159 // instructions in the loop are executed the same number of times.
5160 if (TheLoop->getExitingBlock() != TheLoop->getLoopLatch()) {
5161 ORE->emit(createMissedAnalysis("CFGNotUnderstood")
5162 << "loop control flow is not understood by vectorizer");
5163 if (ORE->allowExtraAnalysis())
5164 Result = false;
5165 else
5166 return false;
5167 }
5168
5169 // We need to have a loop header.
5170 DEBUG(dbgs() << "LV: Found a loop: " << TheLoop->getHeader()->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a loop: " <<
TheLoop->getHeader()->getName() << '\n'; } } while
(false)
5171 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a loop: " <<
TheLoop->getHeader()->getName() << '\n'; } } while
(false)
;
5172
5173 // Check if we can if-convert non-single-bb loops.
5174 unsigned NumBlocks = TheLoop->getNumBlocks();
5175 if (NumBlocks != 1 && !canVectorizeWithIfConvert()) {
5176 DEBUG(dbgs() << "LV: Can't if-convert the loop.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Can't if-convert the loop.\n"
; } } while (false)
;
5177 if (ORE->allowExtraAnalysis())
5178 Result = false;
5179 else
5180 return false;
5181 }
5182
5183 // Check if we can vectorize the instructions and CFG in this loop.
5184 if (!canVectorizeInstrs()) {
5185 DEBUG(dbgs() << "LV: Can't vectorize the instructions or CFG\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Can't vectorize the instructions or CFG\n"
; } } while (false)
;
5186 if (ORE->allowExtraAnalysis())
5187 Result = false;
5188 else
5189 return false;
5190 }
5191
5192 // Go over each instruction and look at memory deps.
5193 if (!canVectorizeMemory()) {
5194 DEBUG(dbgs() << "LV: Can't vectorize due to memory conflicts\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Can't vectorize due to memory conflicts\n"
; } } while (false)
;
5195 if (ORE->allowExtraAnalysis())
5196 Result = false;
5197 else
5198 return false;
5199 }
5200
5201 DEBUG(dbgs() << "LV: We can vectorize this loop"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can vectorize this loop"
<< (LAI->getRuntimePointerChecking()->Need ? " (with a runtime bound check)"
: "") << "!\n"; } } while (false)
5202 << (LAI->getRuntimePointerChecking()->Needdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can vectorize this loop"
<< (LAI->getRuntimePointerChecking()->Need ? " (with a runtime bound check)"
: "") << "!\n"; } } while (false)
5203 ? " (with a runtime bound check)"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can vectorize this loop"
<< (LAI->getRuntimePointerChecking()->Need ? " (with a runtime bound check)"
: "") << "!\n"; } } while (false)
5204 : "")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can vectorize this loop"
<< (LAI->getRuntimePointerChecking()->Need ? " (with a runtime bound check)"
: "") << "!\n"; } } while (false)
5205 << "!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can vectorize this loop"
<< (LAI->getRuntimePointerChecking()->Need ? " (with a runtime bound check)"
: "") << "!\n"; } } while (false)
;
5206
5207 bool UseInterleaved = TTI->enableInterleavedAccessVectorization();
5208
5209 // If an override option has been passed in for interleaved accesses, use it.
5210 if (EnableInterleavedMemAccesses.getNumOccurrences() > 0)
5211 UseInterleaved = EnableInterleavedMemAccesses;
5212
5213 // Analyze interleaved memory accesses.
5214 if (UseInterleaved)
5215 InterleaveInfo.analyzeInterleaving(*getSymbolicStrides());
5216
5217 unsigned SCEVThreshold = VectorizeSCEVCheckThreshold;
5218 if (Hints->getForce() == LoopVectorizeHints::FK_Enabled)
5219 SCEVThreshold = PragmaVectorizeSCEVCheckThreshold;
5220
5221 if (PSE.getUnionPredicate().getComplexity() > SCEVThreshold) {
5222 ORE->emit(createMissedAnalysis("TooManySCEVRunTimeChecks")
5223 << "Too many SCEV assumptions need to be made and checked "
5224 << "at runtime");
5225 DEBUG(dbgs() << "LV: Too many SCEV checks needed.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Too many SCEV checks needed.\n"
; } } while (false)
;
5226 if (ORE->allowExtraAnalysis())
5227 Result = false;
5228 else
5229 return false;
5230 }
5231
5232 // Okay! We've done all the tests. If any have failed, return false. Otherwise
5233 // we can vectorize, and at this point we don't have any other mem analysis
5234 // which may limit our maximum vectorization factor, so just return true with
5235 // no restrictions.
5236 return Result;
5237}
5238
5239static Type *convertPointerToIntegerType(const DataLayout &DL, Type *Ty) {
5240 if (Ty->isPointerTy())
5241 return DL.getIntPtrType(Ty);
5242
5243 // It is possible that char's or short's overflow when we ask for the loop's
5244 // trip count, work around this by changing the type size.
5245 if (Ty->getScalarSizeInBits() < 32)
5246 return Type::getInt32Ty(Ty->getContext());
5247
5248 return Ty;
5249}
5250
5251static Type *getWiderType(const DataLayout &DL, Type *Ty0, Type *Ty1) {
5252 Ty0 = convertPointerToIntegerType(DL, Ty0);
5253 Ty1 = convertPointerToIntegerType(DL, Ty1);
5254 if (Ty0->getScalarSizeInBits() > Ty1->getScalarSizeInBits())
5255 return Ty0;
5256 return Ty1;
5257}
5258
5259/// \brief Check that the instruction has outside loop users and is not an
5260/// identified reduction variable.
5261static bool hasOutsideLoopUser(const Loop *TheLoop, Instruction *Inst,
5262 SmallPtrSetImpl<Value *> &AllowedExit) {
5263 // Reduction and Induction instructions are allowed to have exit users. All
5264 // other instructions must not have external users.
5265 if (!AllowedExit.count(Inst))
5266 // Check that all of the users of the loop are inside the BB.
5267 for (User *U : Inst->users()) {
5268 Instruction *UI = cast<Instruction>(U);
5269 // This user may be a reduction exit value.
5270 if (!TheLoop->contains(UI)) {
5271 DEBUG(dbgs() << "LV: Found an outside user for : " << *UI << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an outside user for : "
<< *UI << '\n'; } } while (false)
;
5272 return true;
5273 }
5274 }
5275 return false;
5276}
5277
5278void LoopVectorizationLegality::addInductionPhi(
5279 PHINode *Phi, const InductionDescriptor &ID,
5280 SmallPtrSetImpl<Value *> &AllowedExit) {
5281 Inductions[Phi] = ID;
5282 Type *PhiTy = Phi->getType();
5283 const DataLayout &DL = Phi->getModule()->getDataLayout();
5284
5285 // Get the widest type.
5286 if (!PhiTy->isFloatingPointTy()) {
5287 if (!WidestIndTy)
5288 WidestIndTy = convertPointerToIntegerType(DL, PhiTy);
5289 else
5290 WidestIndTy = getWiderType(DL, PhiTy, WidestIndTy);
5291 }
5292
5293 // Int inductions are special because we only allow one IV.
5294 if (ID.getKind() == InductionDescriptor::IK_IntInduction &&
5295 ID.getConstIntStepValue() &&
5296 ID.getConstIntStepValue()->isOne() &&
5297 isa<Constant>(ID.getStartValue()) &&
5298 cast<Constant>(ID.getStartValue())->isNullValue()) {
5299
5300 // Use the phi node with the widest type as induction. Use the last
5301 // one if there are multiple (no good reason for doing this other
5302 // than it is expedient). We've checked that it begins at zero and
5303 // steps by one, so this is a canonical induction variable.
5304 if (!PrimaryInduction || PhiTy == WidestIndTy)
5305 PrimaryInduction = Phi;
5306 }
5307
5308 // Both the PHI node itself, and the "post-increment" value feeding
5309 // back into the PHI node may have external users.
5310 AllowedExit.insert(Phi);
5311 AllowedExit.insert(Phi->getIncomingValueForBlock(TheLoop->getLoopLatch()));
5312
5313 DEBUG(dbgs() << "LV: Found an induction variable.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an induction variable.\n"
; } } while (false)
;
5314 return;
5315}
5316
5317bool LoopVectorizationLegality::canVectorizeInstrs() {
5318 BasicBlock *Header = TheLoop->getHeader();
5319
5320 // Look for the attribute signaling the absence of NaNs.
5321 Function &F = *Header->getParent();
5322 HasFunNoNaNAttr =
5323 F.getFnAttribute("no-nans-fp-math").getValueAsString() == "true";
5324
5325 // For each block in the loop.
5326 for (BasicBlock *BB : TheLoop->blocks()) {
5327 // Scan the instructions in the block and look for hazards.
5328 for (Instruction &I : *BB) {
5329 if (auto *Phi = dyn_cast<PHINode>(&I)) {
5330 Type *PhiTy = Phi->getType();
5331 // Check that this PHI type is allowed.
5332 if (!PhiTy->isIntegerTy() && !PhiTy->isFloatingPointTy() &&
5333 !PhiTy->isPointerTy()) {
5334 ORE->emit(createMissedAnalysis("CFGNotUnderstood", Phi)
5335 << "loop control flow is not understood by vectorizer");
5336 DEBUG(dbgs() << "LV: Found an non-int non-pointer PHI.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an non-int non-pointer PHI.\n"
; } } while (false)
;
5337 return false;
5338 }
5339
5340 // If this PHINode is not in the header block, then we know that we
5341 // can convert it to select during if-conversion. No need to check if
5342 // the PHIs in this block are induction or reduction variables.
5343 if (BB != Header) {
5344 // Check that this instruction has no outside users or is an
5345 // identified reduction value with an outside user.
5346 if (!hasOutsideLoopUser(TheLoop, Phi, AllowedExit))
5347 continue;
5348 ORE->emit(createMissedAnalysis("NeitherInductionNorReduction", Phi)
5349 << "value could not be identified as "
5350 "an induction or reduction variable");
5351 return false;
5352 }
5353
5354 // We only allow if-converted PHIs with exactly two incoming values.
5355 if (Phi->getNumIncomingValues() != 2) {
5356 ORE->emit(createMissedAnalysis("CFGNotUnderstood", Phi)
5357 << "control flow not understood by vectorizer");
5358 DEBUG(dbgs() << "LV: Found an invalid PHI.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an invalid PHI.\n"
; } } while (false)
;
5359 return false;
5360 }
5361
5362 RecurrenceDescriptor RedDes;
5363 if (RecurrenceDescriptor::isReductionPHI(Phi, TheLoop, RedDes)) {
5364 if (RedDes.hasUnsafeAlgebra())
5365 Requirements->addUnsafeAlgebraInst(RedDes.getUnsafeAlgebraInst());
5366 AllowedExit.insert(RedDes.getLoopExitInstr());
5367 Reductions[Phi] = RedDes;
5368 continue;
5369 }
5370
5371 InductionDescriptor ID;
5372 if (InductionDescriptor::isInductionPHI(Phi, TheLoop, PSE, ID)) {
5373 addInductionPhi(Phi, ID, AllowedExit);
5374 if (ID.hasUnsafeAlgebra() && !HasFunNoNaNAttr)
5375 Requirements->addUnsafeAlgebraInst(ID.getUnsafeAlgebraInst());
5376 continue;
5377 }
5378
5379 if (RecurrenceDescriptor::isFirstOrderRecurrence(Phi, TheLoop, DT)) {
5380 FirstOrderRecurrences.insert(Phi);
5381 continue;
5382 }
5383
5384 // As a last resort, coerce the PHI to a AddRec expression
5385 // and re-try classifying it a an induction PHI.
5386 if (InductionDescriptor::isInductionPHI(Phi, TheLoop, PSE, ID, true)) {
5387 addInductionPhi(Phi, ID, AllowedExit);
5388 continue;
5389 }
5390
5391 ORE->emit(createMissedAnalysis("NonReductionValueUsedOutsideLoop", Phi)
5392 << "value that could not be identified as "
5393 "reduction is used outside the loop");
5394 DEBUG(dbgs() << "LV: Found an unidentified PHI." << *Phi << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an unidentified PHI."
<< *Phi << "\n"; } } while (false)
;
5395 return false;
5396 } // end of PHI handling
5397
5398 // We handle calls that:
5399 // * Are debug info intrinsics.
5400 // * Have a mapping to an IR intrinsic.
5401 // * Have a vector version available.
5402 auto *CI = dyn_cast<CallInst>(&I);
5403 if (CI && !getVectorIntrinsicIDForCall(CI, TLI) &&
5404 !isa<DbgInfoIntrinsic>(CI) &&
5405 !(CI->getCalledFunction() && TLI &&
5406 TLI->isFunctionVectorizable(CI->getCalledFunction()->getName()))) {
5407 ORE->emit(createMissedAnalysis("CantVectorizeCall", CI)
5408 << "call instruction cannot be vectorized");
5409 DEBUG(dbgs() << "LV: Found a non-intrinsic, non-libfunc callsite.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a non-intrinsic, non-libfunc callsite.\n"
; } } while (false)
;
5410 return false;
5411 }
5412
5413 // Intrinsics such as powi,cttz and ctlz are legal to vectorize if the
5414 // second argument is the same (i.e. loop invariant)
5415 if (CI && hasVectorInstrinsicScalarOpd(
5416 getVectorIntrinsicIDForCall(CI, TLI), 1)) {
5417 auto *SE = PSE.getSE();
5418 if (!SE->isLoopInvariant(PSE.getSCEV(CI->getOperand(1)), TheLoop)) {
5419 ORE->emit(createMissedAnalysis("CantVectorizeIntrinsic", CI)
5420 << "intrinsic instruction cannot be vectorized");
5421 DEBUG(dbgs() << "LV: Found unvectorizable intrinsic " << *CI << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found unvectorizable intrinsic "
<< *CI << "\n"; } } while (false)
;
5422 return false;
5423 }
5424 }
5425
5426 // Check that the instruction return type is vectorizable.
5427 // Also, we can't vectorize extractelement instructions.
5428 if ((!VectorType::isValidElementType(I.getType()) &&
5429 !I.getType()->isVoidTy()) ||
5430 isa<ExtractElementInst>(I)) {
5431 ORE->emit(createMissedAnalysis("CantVectorizeInstructionReturnType", &I)
5432 << "instruction return type cannot be vectorized");
5433 DEBUG(dbgs() << "LV: Found unvectorizable type.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found unvectorizable type.\n"
; } } while (false)
;
5434 return false;
5435 }
5436
5437 // Check that the stored type is vectorizable.
5438 if (auto *ST = dyn_cast<StoreInst>(&I)) {
5439 Type *T = ST->getValueOperand()->getType();
5440 if (!VectorType::isValidElementType(T)) {
5441 ORE->emit(createMissedAnalysis("CantVectorizeStore", ST)
5442 << "store instruction cannot be vectorized");
5443 return false;
5444 }
5445
5446 // FP instructions can allow unsafe algebra, thus vectorizable by
5447 // non-IEEE-754 compliant SIMD units.
5448 // This applies to floating-point math operations and calls, not memory
5449 // operations, shuffles, or casts, as they don't change precision or
5450 // semantics.
5451 } else if (I.getType()->isFloatingPointTy() && (CI || I.isBinaryOp()) &&
5452 !I.hasUnsafeAlgebra()) {
5453 DEBUG(dbgs() << "LV: Found FP op with unsafe algebra.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found FP op with unsafe algebra.\n"
; } } while (false)
;
5454 Hints->setPotentiallyUnsafe();
5455 }
5456
5457 // Reduction instructions are allowed to have exit users.
5458 // All other instructions must not have external users.
5459 if (hasOutsideLoopUser(TheLoop, &I, AllowedExit)) {
5460 ORE->emit(createMissedAnalysis("ValueUsedOutsideLoop", &I)
5461 << "value cannot be used outside the loop");
5462 return false;
5463 }
5464
5465 } // next instr.
5466 }
5467
5468 if (!PrimaryInduction) {
5469 DEBUG(dbgs() << "LV: Did not find one integer induction var.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Did not find one integer induction var.\n"
; } } while (false)
;
5470 if (Inductions.empty()) {
5471 ORE->emit(createMissedAnalysis("NoInductionVariable")
5472 << "loop induction variable could not be identified");
5473 return false;
5474 }
5475 }
5476
5477 // Now we know the widest induction type, check if our found induction
5478 // is the same size. If it's not, unset it here and InnerLoopVectorizer
5479 // will create another.
5480 if (PrimaryInduction && WidestIndTy != PrimaryInduction->getType())
5481 PrimaryInduction = nullptr;
5482
5483 return true;
5484}
5485
5486void LoopVectorizationCostModel::collectLoopScalars(unsigned VF) {
5487
5488 // We should not collect Scalars more than once per VF. Right now, this
5489 // function is called from collectUniformsAndScalars(), which already does
5490 // this check. Collecting Scalars for VF=1 does not make any sense.
5491 assert(VF >= 2 && !Scalars.count(VF) &&((VF >= 2 && !Scalars.count(VF) && "This function should not be visited twice for the same VF"
) ? static_cast<void> (0) : __assert_fail ("VF >= 2 && !Scalars.count(VF) && \"This function should not be visited twice for the same VF\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5492, __PRETTY_FUNCTION__))
5492 "This function should not be visited twice for the same VF")((VF >= 2 && !Scalars.count(VF) && "This function should not be visited twice for the same VF"
) ? static_cast<void> (0) : __assert_fail ("VF >= 2 && !Scalars.count(VF) && \"This function should not be visited twice for the same VF\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5492, __PRETTY_FUNCTION__))
;
5493
5494 SmallSetVector<Instruction *, 8> Worklist;
5495
5496 // These sets are used to seed the analysis with pointers used by memory
5497 // accesses that will remain scalar.
5498 SmallSetVector<Instruction *, 8> ScalarPtrs;
5499 SmallPtrSet<Instruction *, 8> PossibleNonScalarPtrs;
5500
5501 // A helper that returns true if the use of Ptr by MemAccess will be scalar.
5502 // The pointer operands of loads and stores will be scalar as long as the
5503 // memory access is not a gather or scatter operation. The value operand of a
5504 // store will remain scalar if the store is scalarized.
5505 auto isScalarUse = [&](Instruction *MemAccess, Value *Ptr) {
5506 InstWidening WideningDecision = getWideningDecision(MemAccess, VF);
5507 assert(WideningDecision != CM_Unknown &&((WideningDecision != CM_Unknown && "Widening decision should be ready at this moment"
) ? static_cast<void> (0) : __assert_fail ("WideningDecision != CM_Unknown && \"Widening decision should be ready at this moment\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5508, __PRETTY_FUNCTION__))
5508 "Widening decision should be ready at this moment")((WideningDecision != CM_Unknown && "Widening decision should be ready at this moment"
) ? static_cast<void> (0) : __assert_fail ("WideningDecision != CM_Unknown && \"Widening decision should be ready at this moment\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5508, __PRETTY_FUNCTION__))
;
5509 if (auto *Store = dyn_cast<StoreInst>(MemAccess))
5510 if (Ptr == Store->getValueOperand())
5511 return WideningDecision == CM_Scalarize;
5512 assert(Ptr == getPointerOperand(MemAccess) &&((Ptr == getPointerOperand(MemAccess) && "Ptr is neither a value or pointer operand"
) ? static_cast<void> (0) : __assert_fail ("Ptr == getPointerOperand(MemAccess) && \"Ptr is neither a value or pointer operand\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5513, __PRETTY_FUNCTION__))
5513 "Ptr is neither a value or pointer operand")((Ptr == getPointerOperand(MemAccess) && "Ptr is neither a value or pointer operand"
) ? static_cast<void> (0) : __assert_fail ("Ptr == getPointerOperand(MemAccess) && \"Ptr is neither a value or pointer operand\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5513, __PRETTY_FUNCTION__))
;
5514 return WideningDecision != CM_GatherScatter;
5515 };
5516
5517 // A helper that returns true if the given value is a bitcast or
5518 // getelementptr instruction contained in the loop.
5519 auto isLoopVaryingBitCastOrGEP = [&](Value *V) {
5520 return ((isa<BitCastInst>(V) && V->getType()->isPointerTy()) ||
5521 isa<GetElementPtrInst>(V)) &&
5522 !TheLoop->isLoopInvariant(V);
5523 };
5524
5525 // A helper that evaluates a memory access's use of a pointer. If the use
5526 // will be a scalar use, and the pointer is only used by memory accesses, we
5527 // place the pointer in ScalarPtrs. Otherwise, the pointer is placed in
5528 // PossibleNonScalarPtrs.
5529 auto evaluatePtrUse = [&](Instruction *MemAccess, Value *Ptr) {
5530
5531 // We only care about bitcast and getelementptr instructions contained in
5532 // the loop.
5533 if (!isLoopVaryingBitCastOrGEP(Ptr))
5534 return;
5535
5536 // If the pointer has already been identified as scalar (e.g., if it was
5537 // also identified as uniform), there's nothing to do.
5538 auto *I = cast<Instruction>(Ptr);
5539 if (Worklist.count(I))
5540 return;
5541
5542 // If the use of the pointer will be a scalar use, and all users of the
5543 // pointer are memory accesses, place the pointer in ScalarPtrs. Otherwise,
5544 // place the pointer in PossibleNonScalarPtrs.
5545 if (isScalarUse(MemAccess, Ptr) && all_of(I->users(), [&](User *U) {
5546 return isa<LoadInst>(U) || isa<StoreInst>(U);
5547 }))
5548 ScalarPtrs.insert(I);
5549 else
5550 PossibleNonScalarPtrs.insert(I);
5551 };
5552
5553 // We seed the scalars analysis with three classes of instructions: (1)
5554 // instructions marked uniform-after-vectorization, (2) bitcast and
5555 // getelementptr instructions used by memory accesses requiring a scalar use,
5556 // and (3) pointer induction variables and their update instructions (we
5557 // currently only scalarize these).
5558 //
5559 // (1) Add to the worklist all instructions that have been identified as
5560 // uniform-after-vectorization.
5561 Worklist.insert(Uniforms[VF].begin(), Uniforms[VF].end());
5562
5563 // (2) Add to the worklist all bitcast and getelementptr instructions used by
5564 // memory accesses requiring a scalar use. The pointer operands of loads and
5565 // stores will be scalar as long as the memory accesses is not a gather or
5566 // scatter operation. The value operand of a store will remain scalar if the
5567 // store is scalarized.
5568 for (auto *BB : TheLoop->blocks())
5569 for (auto &I : *BB) {
5570 if (auto *Load = dyn_cast<LoadInst>(&I)) {
5571 evaluatePtrUse(Load, Load->getPointerOperand());
5572 } else if (auto *Store = dyn_cast<StoreInst>(&I)) {
5573 evaluatePtrUse(Store, Store->getPointerOperand());
5574 evaluatePtrUse(Store, Store->getValueOperand());
5575 }
5576 }
5577 for (auto *I : ScalarPtrs)
5578 if (!PossibleNonScalarPtrs.count(I)) {
5579 DEBUG(dbgs() << "LV: Found scalar instruction: " << *I << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found scalar instruction: "
<< *I << "\n"; } } while (false)
;
5580 Worklist.insert(I);
5581 }
5582
5583 // (3) Add to the worklist all pointer induction variables and their update
5584 // instructions.
5585 //
5586 // TODO: Once we are able to vectorize pointer induction variables we should
5587 // no longer insert them into the worklist here.
5588 auto *Latch = TheLoop->getLoopLatch();
5589 for (auto &Induction : *Legal->getInductionVars()) {
5590 auto *Ind = Induction.first;
5591 auto *IndUpdate = cast<Instruction>(Ind->getIncomingValueForBlock(Latch));
5592 if (Induction.second.getKind() != InductionDescriptor::IK_PtrInduction)
5593 continue;
5594 Worklist.insert(Ind);
5595 Worklist.insert(IndUpdate);
5596 DEBUG(dbgs() << "LV: Found scalar instruction: " << *Ind << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found scalar instruction: "
<< *Ind << "\n"; } } while (false)
;
5597 DEBUG(dbgs() << "LV: Found scalar instruction: " << *IndUpdate << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found scalar instruction: "
<< *IndUpdate << "\n"; } } while (false)
;
5598 }
5599
5600 // Insert the forced scalars.
5601 // FIXME: Currently widenPHIInstruction() often creates a dead vector
5602 // induction variable when the PHI user is scalarized.
5603 if (ForcedScalars.count(VF))
5604 for (auto *I : ForcedScalars.find(VF)->second)
5605 Worklist.insert(I);
5606
5607 // Expand the worklist by looking through any bitcasts and getelementptr
5608 // instructions we've already identified as scalar. This is similar to the
5609 // expansion step in collectLoopUniforms(); however, here we're only
5610 // expanding to include additional bitcasts and getelementptr instructions.
5611 unsigned Idx = 0;
5612 while (Idx != Worklist.size()) {
5613 Instruction *Dst = Worklist[Idx++];
5614 if (!isLoopVaryingBitCastOrGEP(Dst->getOperand(0)))
5615 continue;
5616 auto *Src = cast<Instruction>(Dst->getOperand(0));
5617 if (all_of(Src->users(), [&](User *U) -> bool {
5618 auto *J = cast<Instruction>(U);
5619 return !TheLoop->contains(J) || Worklist.count(J) ||
5620 ((isa<LoadInst>(J) || isa<StoreInst>(J)) &&
5621 isScalarUse(J, Src));
5622 })) {
5623 Worklist.insert(Src);
5624 DEBUG(dbgs() << "LV: Found scalar instruction: " << *Src << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found scalar instruction: "
<< *Src << "\n"; } } while (false)
;
5625 }
5626 }
5627
5628 // An induction variable will remain scalar if all users of the induction
5629 // variable and induction variable update remain scalar.
5630 for (auto &Induction : *Legal->getInductionVars()) {
5631 auto *Ind = Induction.first;
5632 auto *IndUpdate = cast<Instruction>(Ind->getIncomingValueForBlock(Latch));
5633
5634 // We already considered pointer induction variables, so there's no reason
5635 // to look at their users again.
5636 //
5637 // TODO: Once we are able to vectorize pointer induction variables we
5638 // should no longer skip over them here.
5639 if (Induction.second.getKind() == InductionDescriptor::IK_PtrInduction)
5640 continue;
5641
5642 // Determine if all users of the induction variable are scalar after
5643 // vectorization.
5644 auto ScalarInd = all_of(Ind->users(), [&](User *U) -> bool {
5645 auto *I = cast<Instruction>(U);
5646 return I == IndUpdate || !TheLoop->contains(I) || Worklist.count(I);
5647 });
5648 if (!ScalarInd)
5649 continue;
5650
5651 // Determine if all users of the induction variable update instruction are
5652 // scalar after vectorization.
5653 auto ScalarIndUpdate = all_of(IndUpdate->users(), [&](User *U) -> bool {
5654 auto *I = cast<Instruction>(U);
5655 return I == Ind || !TheLoop->contains(I) || Worklist.count(I);
5656 });
5657 if (!ScalarIndUpdate)
5658 continue;
5659
5660 // The induction variable and its update instruction will remain scalar.
5661 Worklist.insert(Ind);
5662 Worklist.insert(IndUpdate);
5663 DEBUG(dbgs() << "LV: Found scalar instruction: " << *Ind << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found scalar instruction: "
<< *Ind << "\n"; } } while (false)
;
5664 DEBUG(dbgs() << "LV: Found scalar instruction: " << *IndUpdate << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found scalar instruction: "
<< *IndUpdate << "\n"; } } while (false)
;
5665 }
5666
5667 Scalars[VF].insert(Worklist.begin(), Worklist.end());
5668}
5669
5670bool LoopVectorizationLegality::isScalarWithPredication(Instruction *I) {
5671 if (!blockNeedsPredication(I->getParent()))
5672 return false;
5673 switch(I->getOpcode()) {
5674 default:
5675 break;
5676 case Instruction::Store:
5677 return !isMaskRequired(I);
5678 case Instruction::UDiv:
5679 case Instruction::SDiv:
5680 case Instruction::SRem:
5681 case Instruction::URem:
5682 return mayDivideByZero(*I);
5683 }
5684 return false;
5685}
5686
5687bool LoopVectorizationLegality::memoryInstructionCanBeWidened(Instruction *I,
5688 unsigned VF) {
5689 // Get and ensure we have a valid memory instruction.
5690 LoadInst *LI = dyn_cast<LoadInst>(I);
5691 StoreInst *SI = dyn_cast<StoreInst>(I);
5692 assert((LI || SI) && "Invalid memory instruction")(((LI || SI) && "Invalid memory instruction") ? static_cast
<void> (0) : __assert_fail ("(LI || SI) && \"Invalid memory instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5692, __PRETTY_FUNCTION__))
;
5693
5694 auto *Ptr = getPointerOperand(I);
5695
5696 // In order to be widened, the pointer should be consecutive, first of all.
5697 if (!isConsecutivePtr(Ptr))
5698 return false;
5699
5700 // If the instruction is a store located in a predicated block, it will be
5701 // scalarized.
5702 if (isScalarWithPredication(I))
5703 return false;
5704
5705 // If the instruction's allocated size doesn't equal it's type size, it
5706 // requires padding and will be scalarized.
5707 auto &DL = I->getModule()->getDataLayout();
5708 auto *ScalarTy = LI ? LI->getType() : SI->getValueOperand()->getType();
5709 if (hasIrregularType(ScalarTy, DL, VF))
5710 return false;
5711
5712 return true;
5713}
5714
5715void LoopVectorizationCostModel::collectLoopUniforms(unsigned VF) {
5716
5717 // We should not collect Uniforms more than once per VF. Right now,
5718 // this function is called from collectUniformsAndScalars(), which
5719 // already does this check. Collecting Uniforms for VF=1 does not make any
5720 // sense.
5721
5722 assert(VF >= 2 && !Uniforms.count(VF) &&((VF >= 2 && !Uniforms.count(VF) && "This function should not be visited twice for the same VF"
) ? static_cast<void> (0) : __assert_fail ("VF >= 2 && !Uniforms.count(VF) && \"This function should not be visited twice for the same VF\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5723, __PRETTY_FUNCTION__))
5723 "This function should not be visited twice for the same VF")((VF >= 2 && !Uniforms.count(VF) && "This function should not be visited twice for the same VF"
) ? static_cast<void> (0) : __assert_fail ("VF >= 2 && !Uniforms.count(VF) && \"This function should not be visited twice for the same VF\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5723, __PRETTY_FUNCTION__))
;
5724
5725 // Visit the list of Uniforms. If we'll not find any uniform value, we'll
5726 // not analyze again. Uniforms.count(VF) will return 1.
5727 Uniforms[VF].clear();
5728
5729 // We now know that the loop is vectorizable!
5730 // Collect instructions inside the loop that will remain uniform after
5731 // vectorization.
5732
5733 // Global values, params and instructions outside of current loop are out of
5734 // scope.
5735 auto isOutOfScope = [&](Value *V) -> bool {
5736 Instruction *I = dyn_cast<Instruction>(V);
5737 return (!I || !TheLoop->contains(I));
5738 };
5739
5740 SetVector<Instruction *> Worklist;
5741 BasicBlock *Latch = TheLoop->getLoopLatch();
5742
5743 // Start with the conditional branch. If the branch condition is an
5744 // instruction contained in the loop that is only used by the branch, it is
5745 // uniform.
5746 auto *Cmp = dyn_cast<Instruction>(Latch->getTerminator()->getOperand(0));
5747 if (Cmp && TheLoop->contains(Cmp) && Cmp->hasOneUse()) {
5748 Worklist.insert(Cmp);
5749 DEBUG(dbgs() << "LV: Found uniform instruction: " << *Cmp << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found uniform instruction: "
<< *Cmp << "\n"; } } while (false)
;
5750 }
5751
5752 // Holds consecutive and consecutive-like pointers. Consecutive-like pointers
5753 // are pointers that are treated like consecutive pointers during
5754 // vectorization. The pointer operands of interleaved accesses are an
5755 // example.
5756 SmallSetVector<Instruction *, 8> ConsecutiveLikePtrs;
5757
5758 // Holds pointer operands of instructions that are possibly non-uniform.
5759 SmallPtrSet<Instruction *, 8> PossibleNonUniformPtrs;
5760
5761 auto isUniformDecision = [&](Instruction *I, unsigned VF) {
5762 InstWidening WideningDecision = getWideningDecision(I, VF);
5763 assert(WideningDecision != CM_Unknown &&((WideningDecision != CM_Unknown && "Widening decision should be ready at this moment"
) ? static_cast<void> (0) : __assert_fail ("WideningDecision != CM_Unknown && \"Widening decision should be ready at this moment\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5764, __PRETTY_FUNCTION__))
5764 "Widening decision should be ready at this moment")((WideningDecision != CM_Unknown && "Widening decision should be ready at this moment"
) ? static_cast<void> (0) : __assert_fail ("WideningDecision != CM_Unknown && \"Widening decision should be ready at this moment\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5764, __PRETTY_FUNCTION__))
;
5765
5766 return (WideningDecision == CM_Widen ||
5767 WideningDecision == CM_Interleave);
5768 };
5769 // Iterate over the instructions in the loop, and collect all
5770 // consecutive-like pointer operands in ConsecutiveLikePtrs. If it's possible
5771 // that a consecutive-like pointer operand will be scalarized, we collect it
5772 // in PossibleNonUniformPtrs instead. We use two sets here because a single
5773 // getelementptr instruction can be used by both vectorized and scalarized
5774 // memory instructions. For example, if a loop loads and stores from the same
5775 // location, but the store is conditional, the store will be scalarized, and
5776 // the getelementptr won't remain uniform.
5777 for (auto *BB : TheLoop->blocks())
5778 for (auto &I : *BB) {
5779
5780 // If there's no pointer operand, there's nothing to do.
5781 auto *Ptr = dyn_cast_or_null<Instruction>(getPointerOperand(&I));
5782 if (!Ptr)
5783 continue;
5784
5785 // True if all users of Ptr are memory accesses that have Ptr as their
5786 // pointer operand.
5787 auto UsersAreMemAccesses = all_of(Ptr->users(), [&](User *U) -> bool {
5788 return getPointerOperand(U) == Ptr;
5789 });
5790
5791 // Ensure the memory instruction will not be scalarized or used by
5792 // gather/scatter, making its pointer operand non-uniform. If the pointer
5793 // operand is used by any instruction other than a memory access, we
5794 // conservatively assume the pointer operand may be non-uniform.
5795 if (!UsersAreMemAccesses || !isUniformDecision(&I, VF))
5796 PossibleNonUniformPtrs.insert(Ptr);
5797
5798 // If the memory instruction will be vectorized and its pointer operand
5799 // is consecutive-like, or interleaving - the pointer operand should
5800 // remain uniform.
5801 else
5802 ConsecutiveLikePtrs.insert(Ptr);
5803 }
5804
5805 // Add to the Worklist all consecutive and consecutive-like pointers that
5806 // aren't also identified as possibly non-uniform.
5807 for (auto *V : ConsecutiveLikePtrs)
5808 if (!PossibleNonUniformPtrs.count(V)) {
5809 DEBUG(dbgs() << "LV: Found uniform instruction: " << *V << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found uniform instruction: "
<< *V << "\n"; } } while (false)
;
5810 Worklist.insert(V);
5811 }
5812
5813 // Expand Worklist in topological order: whenever a new instruction
5814 // is added , its users should be either already inside Worklist, or
5815 // out of scope. It ensures a uniform instruction will only be used
5816 // by uniform instructions or out of scope instructions.
5817 unsigned idx = 0;
5818 while (idx != Worklist.size()) {
5819 Instruction *I = Worklist[idx++];
5820
5821 for (auto OV : I->operand_values()) {
5822 if (isOutOfScope(OV))
5823 continue;
5824 auto *OI = cast<Instruction>(OV);
5825 if (all_of(OI->users(), [&](User *U) -> bool {
5826 auto *J = cast<Instruction>(U);
5827 return !TheLoop->contains(J) || Worklist.count(J) ||
5828 (OI == getPointerOperand(J) && isUniformDecision(J, VF));
5829 })) {
5830 Worklist.insert(OI);
5831 DEBUG(dbgs() << "LV: Found uniform instruction: " << *OI << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found uniform instruction: "
<< *OI << "\n"; } } while (false)
;
5832 }
5833 }
5834 }
5835
5836 // Returns true if Ptr is the pointer operand of a memory access instruction
5837 // I, and I is known to not require scalarization.
5838 auto isVectorizedMemAccessUse = [&](Instruction *I, Value *Ptr) -> bool {
5839 return getPointerOperand(I) == Ptr && isUniformDecision(I, VF);
5840 };
5841
5842 // For an instruction to be added into Worklist above, all its users inside
5843 // the loop should also be in Worklist. However, this condition cannot be
5844 // true for phi nodes that form a cyclic dependence. We must process phi
5845 // nodes separately. An induction variable will remain uniform if all users
5846 // of the induction variable and induction variable update remain uniform.
5847 // The code below handles both pointer and non-pointer induction variables.
5848 for (auto &Induction : *Legal->getInductionVars()) {
5849 auto *Ind = Induction.first;
5850 auto *IndUpdate = cast<Instruction>(Ind->getIncomingValueForBlock(Latch));
5851
5852 // Determine if all users of the induction variable are uniform after
5853 // vectorization.
5854 auto UniformInd = all_of(Ind->users(), [&](User *U) -> bool {
5855 auto *I = cast<Instruction>(U);
5856 return I == IndUpdate || !TheLoop->contains(I) || Worklist.count(I) ||
5857 isVectorizedMemAccessUse(I, Ind);
5858 });
5859 if (!UniformInd)
5860 continue;
5861
5862 // Determine if all users of the induction variable update instruction are
5863 // uniform after vectorization.
5864 auto UniformIndUpdate = all_of(IndUpdate->users(), [&](User *U) -> bool {
5865 auto *I = cast<Instruction>(U);
5866 return I == Ind || !TheLoop->contains(I) || Worklist.count(I) ||
5867 isVectorizedMemAccessUse(I, IndUpdate);
5868 });
5869 if (!UniformIndUpdate)
5870 continue;
5871
5872 // The induction variable and its update instruction will remain uniform.
5873 Worklist.insert(Ind);
5874 Worklist.insert(IndUpdate);
5875 DEBUG(dbgs() << "LV: Found uniform instruction: " << *Ind << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found uniform instruction: "
<< *Ind << "\n"; } } while (false)
;
5876 DEBUG(dbgs() << "LV: Found uniform instruction: " << *IndUpdate << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found uniform instruction: "
<< *IndUpdate << "\n"; } } while (false)
;
5877 }
5878
5879 Uniforms[VF].insert(Worklist.begin(), Worklist.end());
5880}
5881
5882bool LoopVectorizationLegality::canVectorizeMemory() {
5883 LAI = &(*GetLAA)(*TheLoop);
5884 InterleaveInfo.setLAI(LAI);
5885 const OptimizationRemarkAnalysis *LAR = LAI->getReport();
5886 if (LAR) {
5887 OptimizationRemarkAnalysis VR(Hints->vectorizeAnalysisPassName(),
5888 "loop not vectorized: ", *LAR);
5889 ORE->emit(VR);
5890 }
5891 if (!LAI->canVectorizeMemory())
5892 return false;
5893
5894 if (LAI->hasStoreToLoopInvariantAddress()) {
5895 ORE->emit(createMissedAnalysis("CantVectorizeStoreToLoopInvariantAddress")
5896 << "write to a loop invariant address could not be vectorized");
5897 DEBUG(dbgs() << "LV: We don't allow storing to uniform addresses\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We don't allow storing to uniform addresses\n"
; } } while (false)
;
5898 return false;
5899 }
5900
5901 Requirements->addRuntimePointerChecks(LAI->getNumRuntimePointerChecks());
5902 PSE.addPredicate(LAI->getPSE().getUnionPredicate());
5903
5904 return true;
5905}
5906
5907bool LoopVectorizationLegality::isInductionVariable(const Value *V) {
5908 Value *In0 = const_cast<Value *>(V);
5909 PHINode *PN = dyn_cast_or_null<PHINode>(In0);
5910 if (!PN)
5911 return false;
5912
5913 return Inductions.count(PN);
5914}
5915
5916bool LoopVectorizationLegality::isFirstOrderRecurrence(const PHINode *Phi) {
5917 return FirstOrderRecurrences.count(Phi);
5918}
5919
5920bool LoopVectorizationLegality::blockNeedsPredication(BasicBlock *BB) {
5921 return LoopAccessInfo::blockNeedsPredication(BB, TheLoop, DT);
5922}
5923
5924bool LoopVectorizationLegality::blockCanBePredicated(
5925 BasicBlock *BB, SmallPtrSetImpl<Value *> &SafePtrs) {
5926 const bool IsAnnotatedParallel = TheLoop->isAnnotatedParallel();
5927
5928 for (Instruction &I : *BB) {
5929 // Check that we don't have a constant expression that can trap as operand.
5930 for (Value *Operand : I.operands()) {
5931 if (auto *C = dyn_cast<Constant>(Operand))
5932 if (C->canTrap())
5933 return false;
5934 }
5935 // We might be able to hoist the load.
5936 if (I.mayReadFromMemory()) {
5937 auto *LI = dyn_cast<LoadInst>(&I);
5938 if (!LI)
5939 return false;
5940 if (!SafePtrs.count(LI->getPointerOperand())) {
5941 if (isLegalMaskedLoad(LI->getType(), LI->getPointerOperand()) ||
5942 isLegalMaskedGather(LI->getType())) {
5943 MaskedOp.insert(LI);
5944 continue;
5945 }
5946 // !llvm.mem.parallel_loop_access implies if-conversion safety.
5947 if (IsAnnotatedParallel)
5948 continue;
5949 return false;
5950 }
5951 }
5952
5953 if (I.mayWriteToMemory()) {
5954 auto *SI = dyn_cast<StoreInst>(&I);
5955 // We only support predication of stores in basic blocks with one
5956 // predecessor.
5957 if (!SI)
5958 return false;
5959
5960 // Build a masked store if it is legal for the target.
5961 if (isLegalMaskedStore(SI->getValueOperand()->getType(),
5962 SI->getPointerOperand()) ||
5963 isLegalMaskedScatter(SI->getValueOperand()->getType())) {
5964 MaskedOp.insert(SI);
5965 continue;
5966 }
5967
5968 bool isSafePtr = (SafePtrs.count(SI->getPointerOperand()) != 0);
5969 bool isSinglePredecessor = SI->getParent()->getSinglePredecessor();
5970
5971 if (++NumPredStores > NumberOfStoresToPredicate || !isSafePtr ||
5972 !isSinglePredecessor)
5973 return false;
5974 }
5975 if (I.mayThrow())
5976 return false;
5977 }
5978
5979 return true;
5980}
5981
5982void InterleavedAccessInfo::collectConstStrideAccesses(
5983 MapVector<Instruction *, StrideDescriptor> &AccessStrideInfo,
5984 const ValueToValueMap &Strides) {
5985
5986 auto &DL = TheLoop->getHeader()->getModule()->getDataLayout();
5987
5988 // Since it's desired that the load/store instructions be maintained in
5989 // "program order" for the interleaved access analysis, we have to visit the
5990 // blocks in the loop in reverse postorder (i.e., in a topological order).
5991 // Such an ordering will ensure that any load/store that may be executed
5992 // before a second load/store will precede the second load/store in
5993 // AccessStrideInfo.
5994 LoopBlocksDFS DFS(TheLoop);
5995 DFS.perform(LI);
5996 for (BasicBlock *BB : make_range(DFS.beginRPO(), DFS.endRPO()))
5997 for (auto &I : *BB) {
5998 auto *LI = dyn_cast<LoadInst>(&I);
5999 auto *SI = dyn_cast<StoreInst>(&I);
6000 if (!LI && !SI)
6001 continue;
6002
6003 Value *Ptr = getPointerOperand(&I);
6004 // We don't check wrapping here because we don't know yet if Ptr will be
6005 // part of a full group or a group with gaps. Checking wrapping for all
6006 // pointers (even those that end up in groups with no gaps) will be overly
6007 // conservative. For full groups, wrapping should be ok since if we would
6008 // wrap around the address space we would do a memory access at nullptr
6009 // even without the transformation. The wrapping checks are therefore
6010 // deferred until after we've formed the interleaved groups.
6011 int64_t Stride = getPtrStride(PSE, Ptr, TheLoop, Strides,
6012 /*Assume=*/true, /*ShouldCheckWrap=*/false);
6013
6014 const SCEV *Scev = replaceSymbolicStrideSCEV(PSE, Strides, Ptr);
6015 PointerType *PtrTy = dyn_cast<PointerType>(Ptr->getType());
6016 uint64_t Size = DL.getTypeAllocSize(PtrTy->getElementType());
6017
6018 // An alignment of 0 means target ABI alignment.
6019 unsigned Align = getMemInstAlignment(&I);
6020 if (!Align)
6021 Align = DL.getABITypeAlignment(PtrTy->getElementType());
6022
6023 AccessStrideInfo[&I] = StrideDescriptor(Stride, Scev, Size, Align);
6024 }
6025}
6026
6027// Analyze interleaved accesses and collect them into interleaved load and
6028// store groups.
6029//
6030// When generating code for an interleaved load group, we effectively hoist all
6031// loads in the group to the location of the first load in program order. When
6032// generating code for an interleaved store group, we sink all stores to the
6033// location of the last store. This code motion can change the order of load
6034// and store instructions and may break dependences.
6035//
6036// The code generation strategy mentioned above ensures that we won't violate
6037// any write-after-read (WAR) dependences.
6038//
6039// E.g., for the WAR dependence: a = A[i]; // (1)
6040// A[i] = b; // (2)
6041//
6042// The store group of (2) is always inserted at or below (2), and the load
6043// group of (1) is always inserted at or above (1). Thus, the instructions will
6044// never be reordered. All other dependences are checked to ensure the
6045// correctness of the instruction reordering.
6046//
6047// The algorithm visits all memory accesses in the loop in bottom-up program
6048// order. Program order is established by traversing the blocks in the loop in
6049// reverse postorder when collecting the accesses.
6050//
6051// We visit the memory accesses in bottom-up order because it can simplify the
6052// construction of store groups in the presence of write-after-write (WAW)
6053// dependences.
6054//
6055// E.g., for the WAW dependence: A[i] = a; // (1)
6056// A[i] = b; // (2)
6057// A[i + 1] = c; // (3)
6058//
6059// We will first create a store group with (3) and (2). (1) can't be added to
6060// this group because it and (2) are dependent. However, (1) can be grouped
6061// with other accesses that may precede it in program order. Note that a
6062// bottom-up order does not imply that WAW dependences should not be checked.
6063void InterleavedAccessInfo::analyzeInterleaving(
6064 const ValueToValueMap &Strides) {
6065 DEBUG(dbgs() << "LV: Analyzing interleaved accesses...\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Analyzing interleaved accesses...\n"
; } } while (false)
;
6066
6067 // Holds all accesses with a constant stride.
6068 MapVector<Instruction *, StrideDescriptor> AccessStrideInfo;
6069 collectConstStrideAccesses(AccessStrideInfo, Strides);
6070
6071 if (AccessStrideInfo.empty())
1
Assuming the condition is false
2
Taking false branch
6072 return;
6073
6074 // Collect the dependences in the loop.
6075 collectDependences();
6076
6077 // Holds all interleaved store groups temporarily.
6078 SmallSetVector<InterleaveGroup *, 4> StoreGroups;
6079 // Holds all interleaved load groups temporarily.
6080 SmallSetVector<InterleaveGroup *, 4> LoadGroups;
6081
6082 // Search in bottom-up program order for pairs of accesses (A and B) that can
6083 // form interleaved load or store groups. In the algorithm below, access A
6084 // precedes access B in program order. We initialize a group for B in the
6085 // outer loop of the algorithm, and then in the inner loop, we attempt to
6086 // insert each A into B's group if:
6087 //
6088 // 1. A and B have the same stride,
6089 // 2. A and B have the same memory object size, and
6090 // 3. A belongs in B's group according to its distance from B.
6091 //
6092 // Special care is taken to ensure group formation will not break any
6093 // dependences.
6094 for (auto BI = AccessStrideInfo.rbegin(), E = AccessStrideInfo.rend();
3
Loop condition is true. Entering loop body
6095 BI != E; ++BI) {
6096 Instruction *B = BI->first;
6097 StrideDescriptor DesB = BI->second;
6098
6099 // Initialize a group for B if it has an allowable stride. Even if we don't
6100 // create a group for B, we continue with the bottom-up algorithm to ensure
6101 // we don't break any of B's dependences.
6102 InterleaveGroup *Group = nullptr;
4
'Group' initialized to a null pointer value
6103 if (isStrided(DesB.Stride)) {
5
Taking false branch
6104 Group = getInterleaveGroup(B);
6105 if (!Group) {
6106 DEBUG(dbgs() << "LV: Creating an interleave group with:" << *B << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Creating an interleave group with:"
<< *B << '\n'; } } while (false)
;
6107 Group = createInterleaveGroup(B, DesB.Stride, DesB.Align);
6108 }
6109 if (B->mayWriteToMemory())
6110 StoreGroups.insert(Group);
6111 else
6112 LoadGroups.insert(Group);
6113 }
6114
6115 for (auto AI = std::next(BI); AI != E; ++AI) {
6
Loop condition is true. Entering loop body
9
Loop condition is true. Entering loop body
12
Loop condition is true. Entering loop body
15
Loop condition is true. Entering loop body
6116 Instruction *A = AI->first;
6117 StrideDescriptor DesA = AI->second;
6118
6119 // Our code motion strategy implies that we can't have dependences
6120 // between accesses in an interleaved group and other accesses located
6121 // between the first and last member of the group. Note that this also
6122 // means that a group can't have more than one member at a given offset.
6123 // The accesses in a group can have dependences with other accesses, but
6124 // we must ensure we don't extend the boundaries of the group such that
6125 // we encompass those dependent accesses.
6126 //
6127 // For example, assume we have the sequence of accesses shown below in a
6128 // stride-2 loop:
6129 //
6130 // (1, 2) is a group | A[i] = a; // (1)
6131 // | A[i-1] = b; // (2) |
6132 // A[i-3] = c; // (3)
6133 // A[i] = d; // (4) | (2, 4) is not a group
6134 //
6135 // Because accesses (2) and (3) are dependent, we can group (2) with (1)
6136 // but not with (4). If we did, the dependent access (3) would be within
6137 // the boundaries of the (2, 4) group.
6138 if (!canReorderMemAccessesForInterleavedGroups(&*AI, &*BI)) {
7
Taking false branch
10
Taking false branch
13
Taking false branch
16
Taking false branch
6139
6140 // If a dependence exists and A is already in a group, we know that A
6141 // must be a store since A precedes B and WAR dependences are allowed.
6142 // Thus, A would be sunk below B. We release A's group to prevent this
6143 // illegal code motion. A will then be free to form another group with
6144 // instructions that precede it.
6145 if (isInterleaved(A)) {
6146 InterleaveGroup *StoreGroup = getInterleaveGroup(A);
6147 StoreGroups.remove(StoreGroup);
6148 releaseGroup(StoreGroup);
6149 }
6150
6151 // If a dependence exists and A is not already in a group (or it was
6152 // and we just released it), B might be hoisted above A (if B is a
6153 // load) or another store might be sunk below A (if B is a store). In
6154 // either case, we can't add additional instructions to B's group. B
6155 // will only form a group with instructions that it precedes.
6156 break;
6157 }
6158
6159 // At this point, we've checked for illegal code motion. If either A or B
6160 // isn't strided, there's nothing left to do.
6161 if (!isStrided(DesA.Stride) || !isStrided(DesB.Stride))
17
Taking false branch
6162 continue;
8
Execution continues on line 6115
11
Execution continues on line 6115
14
Execution continues on line 6115
6163
6164 // Ignore A if it's already in a group or isn't the same kind of memory
6165 // operation as B.
6166 if (isInterleaved(A) || A->mayReadFromMemory() != B->mayReadFromMemory())
18
Assuming the condition is false
19
Taking false branch
6167 continue;
6168
6169 // Check rules 1 and 2. Ignore A if its stride or size is different from
6170 // that of B.
6171 if (DesA.Stride != DesB.Stride || DesA.Size != DesB.Size)
20
Taking false branch
6172 continue;
6173
6174 // Ignore A if the memory object of A and B don't belong to the same
6175 // address space
6176 if (getMemInstAddressSpace(A) != getMemInstAddressSpace(B))
21
Taking false branch
6177 continue;
6178
6179 // Calculate the distance from A to B.
6180 const SCEVConstant *DistToB = dyn_cast<SCEVConstant>(
6181 PSE.getSE()->getMinusSCEV(DesA.Scev, DesB.Scev));
6182 if (!DistToB)
22
Assuming 'DistToB' is non-null
23
Taking false branch
6183 continue;
6184 int64_t DistanceToB = DistToB->getAPInt().getSExtValue();
6185
6186 // Check rule 3. Ignore A if its distance to B is not a multiple of the
6187 // size.
6188 if (DistanceToB % static_cast<int64_t>(DesB.Size))
24
Taking false branch
6189 continue;
6190
6191 // Ignore A if either A or B is in a predicated block. Although we
6192 // currently prevent group formation for predicated accesses, we may be
6193 // able to relax this limitation in the future once we handle more
6194 // complicated blocks.
6195 if (isPredicated(A->getParent()) || isPredicated(B->getParent()))
25
Assuming the condition is false
26
Assuming the condition is false
27
Taking false branch
6196 continue;
6197
6198 // The index of A is the index of B plus A's distance to B in multiples
6199 // of the size.
6200 int IndexA =
6201 Group->getIndex(B) + DistanceToB / static_cast<int64_t>(DesB.Size);
28
Called C++ object pointer is null
6202
6203 // Try to insert A into B's group.
6204 if (Group->insertMember(A, IndexA, DesA.Align)) {
6205 DEBUG(dbgs() << "LV: Inserted:" << *A << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Inserted:" <<
*A << '\n' << " into the interleave group with"
<< *B << '\n'; } } while (false)
6206 << " into the interleave group with" << *B << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Inserted:" <<
*A << '\n' << " into the interleave group with"
<< *B << '\n'; } } while (false)
;
6207 InterleaveGroupMap[A] = Group;
6208
6209 // Set the first load in program order as the insert position.
6210 if (A->mayReadFromMemory())
6211 Group->setInsertPos(A);
6212 }
6213 } // Iteration over A accesses.
6214 } // Iteration over B accesses.
6215
6216 // Remove interleaved store groups with gaps.
6217 for (InterleaveGroup *Group : StoreGroups)
6218 if (Group->getNumMembers() != Group->getFactor())
6219 releaseGroup(Group);
6220
6221 // Remove interleaved groups with gaps (currently only loads) whose memory
6222 // accesses may wrap around. We have to revisit the getPtrStride analysis,
6223 // this time with ShouldCheckWrap=true, since collectConstStrideAccesses does
6224 // not check wrapping (see documentation there).
6225 // FORNOW we use Assume=false;
6226 // TODO: Change to Assume=true but making sure we don't exceed the threshold
6227 // of runtime SCEV assumptions checks (thereby potentially failing to
6228 // vectorize altogether).
6229 // Additional optional optimizations:
6230 // TODO: If we are peeling the loop and we know that the first pointer doesn't
6231 // wrap then we can deduce that all pointers in the group don't wrap.
6232 // This means that we can forcefully peel the loop in order to only have to
6233 // check the first pointer for no-wrap. When we'll change to use Assume=true
6234 // we'll only need at most one runtime check per interleaved group.
6235 //
6236 for (InterleaveGroup *Group : LoadGroups) {
6237
6238 // Case 1: A full group. Can Skip the checks; For full groups, if the wide
6239 // load would wrap around the address space we would do a memory access at
6240 // nullptr even without the transformation.
6241 if (Group->getNumMembers() == Group->getFactor())
6242 continue;
6243
6244 // Case 2: If first and last members of the group don't wrap this implies
6245 // that all the pointers in the group don't wrap.
6246 // So we check only group member 0 (which is always guaranteed to exist),
6247 // and group member Factor - 1; If the latter doesn't exist we rely on
6248 // peeling (if it is a non-reveresed accsess -- see Case 3).
6249 Value *FirstMemberPtr = getPointerOperand(Group->getMember(0));
6250 if (!getPtrStride(PSE, FirstMemberPtr, TheLoop, Strides, /*Assume=*/false,
6251 /*ShouldCheckWrap=*/true)) {
6252 DEBUG(dbgs() << "LV: Invalidate candidate interleaved group due to "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Invalidate candidate interleaved group due to "
"first group member potentially pointer-wrapping.\n"; } } while
(false)
6253 "first group member potentially pointer-wrapping.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Invalidate candidate interleaved group due to "
"first group member potentially pointer-wrapping.\n"; } } while
(false)
;
6254 releaseGroup(Group);
6255 continue;
6256 }
6257 Instruction *LastMember = Group->getMember(Group->getFactor() - 1);
6258 if (LastMember) {
6259 Value *LastMemberPtr = getPointerOperand(LastMember);
6260 if (!getPtrStride(PSE, LastMemberPtr, TheLoop, Strides, /*Assume=*/false,
6261 /*ShouldCheckWrap=*/true)) {
6262 DEBUG(dbgs() << "LV: Invalidate candidate interleaved group due to "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Invalidate candidate interleaved group due to "
"last group member potentially pointer-wrapping.\n"; } } while
(false)
6263 "last group member potentially pointer-wrapping.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Invalidate candidate interleaved group due to "
"last group member potentially pointer-wrapping.\n"; } } while
(false)
;
6264 releaseGroup(Group);
6265 }
6266 } else {
6267 // Case 3: A non-reversed interleaved load group with gaps: We need
6268 // to execute at least one scalar epilogue iteration. This will ensure
6269 // we don't speculatively access memory out-of-bounds. We only need
6270 // to look for a member at index factor - 1, since every group must have
6271 // a member at index zero.
6272 if (Group->isReverse()) {
6273 releaseGroup(Group);
6274 continue;
6275 }
6276 DEBUG(dbgs() << "LV: Interleaved group requires epilogue iteration.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Interleaved group requires epilogue iteration.\n"
; } } while (false)
;
6277 RequiresScalarEpilogue = true;
6278 }
6279 }
6280}
6281
6282Optional<unsigned> LoopVectorizationCostModel::computeMaxVF(bool OptForSize) {
6283 if (!EnableCondStoresVectorization && Legal->getNumPredStores()) {
6284 ORE->emit(createMissedAnalysis("ConditionalStore")
6285 << "store that is conditionally executed prevents vectorization");
6286 DEBUG(dbgs() << "LV: No vectorization. There are conditional stores.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: No vectorization. There are conditional stores.\n"
; } } while (false)
;
6287 return None;
6288 }
6289
6290 if (!OptForSize) // Remaining checks deal with scalar loop when OptForSize.
6291 return computeFeasibleMaxVF(OptForSize);
6292
6293 if (Legal->getRuntimePointerChecking()->Need) {
6294 ORE->emit(createMissedAnalysis("CantVersionLoopWithOptForSize")
6295 << "runtime pointer checks needed. Enable vectorization of this "
6296 "loop with '#pragma clang loop vectorize(enable)' when "
6297 "compiling with -Os/-Oz");
6298 DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Aborting. Runtime ptr check is required with -Os/-Oz.\n"
; } } while (false)
6299 << "LV: Aborting. Runtime ptr check is required with -Os/-Oz.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Aborting. Runtime ptr check is required with -Os/-Oz.\n"
; } } while (false)
;
6300 return None;
6301 }
6302
6303 // If we optimize the program for size, avoid creating the tail loop.
6304 unsigned TC = PSE.getSE()->getSmallConstantTripCount(TheLoop);
6305 DEBUG(dbgs() << "LV: Found trip count: " << TC << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found trip count: "
<< TC << '\n'; } } while (false)
;
6306
6307 // If we don't know the precise trip count, don't try to vectorize.
6308 if (TC < 2) {
6309 ORE->emit(
6310 createMissedAnalysis("UnknownLoopCountComplexCFG")
6311 << "unable to calculate the loop count due to complex control flow");
6312 DEBUG(dbgs() << "LV: Aborting. A tail loop is required with -Os/-Oz.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Aborting. A tail loop is required with -Os/-Oz.\n"
; } } while (false)
;
6313 return None;
6314 }
6315
6316 unsigned MaxVF = computeFeasibleMaxVF(OptForSize);
6317
6318 if (TC % MaxVF != 0) {
6319 // If the trip count that we found modulo the vectorization factor is not
6320 // zero then we require a tail.
6321 // FIXME: look for a smaller MaxVF that does divide TC rather than give up.
6322 // FIXME: return None if loop requiresScalarEpilog(<MaxVF>), or look for a
6323 // smaller MaxVF that does not require a scalar epilog.
6324
6325 ORE->emit(createMissedAnalysis("NoTailLoopWithOptForSize")
6326 << "cannot optimize for size and vectorize at the "
6327 "same time. Enable vectorization of this loop "
6328 "with '#pragma clang loop vectorize(enable)' "
6329 "when compiling with -Os/-Oz");
6330 DEBUG(dbgs() << "LV: Aborting. A tail loop is required with -Os/-Oz.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Aborting. A tail loop is required with -Os/-Oz.\n"
; } } while (false)
;
6331 return None;
6332 }
6333
6334 return MaxVF;
6335}
6336
6337unsigned LoopVectorizationCostModel::computeFeasibleMaxVF(bool OptForSize) {
6338 MinBWs = computeMinimumValueSizes(TheLoop->getBlocks(), *DB, &TTI);
6339 unsigned SmallestType, WidestType;
6340 std::tie(SmallestType, WidestType) = getSmallestAndWidestTypes();
6341 unsigned WidestRegister = TTI.getRegisterBitWidth(true);
6342 unsigned MaxSafeDepDist = -1U;
6343
6344 // Get the maximum safe dependence distance in bits computed by LAA. If the
6345 // loop contains any interleaved accesses, we divide the dependence distance
6346 // by the maximum interleave factor of all interleaved groups. Note that
6347 // although the division ensures correctness, this is a fairly conservative
6348 // computation because the maximum distance computed by LAA may not involve
6349 // any of the interleaved accesses.
6350 if (Legal->getMaxSafeDepDistBytes() != -1U)
6351 MaxSafeDepDist =
6352 Legal->getMaxSafeDepDistBytes() * 8 / Legal->getMaxInterleaveFactor();
6353
6354 WidestRegister =
6355 ((WidestRegister < MaxSafeDepDist) ? WidestRegister : MaxSafeDepDist);
6356 unsigned MaxVectorSize = WidestRegister / WidestType;
6357
6358 DEBUG(dbgs() << "LV: The Smallest and Widest types: " << SmallestType << " / "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The Smallest and Widest types: "
<< SmallestType << " / " << WidestType <<
" bits.\n"; } } while (false)
6359 << WidestType << " bits.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The Smallest and Widest types: "
<< SmallestType << " / " << WidestType <<
" bits.\n"; } } while (false)
;
6360 DEBUG(dbgs() << "LV: The Widest register is: " << WidestRegisterdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The Widest register is: "
<< WidestRegister << " bits.\n"; } } while (false
)
6361 << " bits.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The Widest register is: "
<< WidestRegister << " bits.\n"; } } while (false
)
;
6362
6363 if (MaxVectorSize == 0) {
6364 DEBUG(dbgs() << "LV: The target has no vector registers.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The target has no vector registers.\n"
; } } while (false)
;
6365 MaxVectorSize = 1;
6366 }
6367
6368 assert(MaxVectorSize <= 64 && "Did not expect to pack so many elements"((MaxVectorSize <= 64 && "Did not expect to pack so many elements"
" into one vector!") ? static_cast<void> (0) : __assert_fail
("MaxVectorSize <= 64 && \"Did not expect to pack so many elements\" \" into one vector!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6369, __PRETTY_FUNCTION__))
6369 " into one vector!")((MaxVectorSize <= 64 && "Did not expect to pack so many elements"
" into one vector!") ? static_cast<void> (0) : __assert_fail
("MaxVectorSize <= 64 && \"Did not expect to pack so many elements\" \" into one vector!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6369, __PRETTY_FUNCTION__))
;
6370
6371 unsigned MaxVF = MaxVectorSize;
6372 if (MaximizeBandwidth && !OptForSize) {
6373 // Collect all viable vectorization factors.
6374 SmallVector<unsigned, 8> VFs;
6375 unsigned NewMaxVectorSize = WidestRegister / SmallestType;
6376 for (unsigned VS = MaxVectorSize; VS <= NewMaxVectorSize; VS *= 2)
6377 VFs.push_back(VS);
6378
6379 // For each VF calculate its register usage.
6380 auto RUs = calculateRegisterUsage(VFs);
6381
6382 // Select the largest VF which doesn't require more registers than existing
6383 // ones.
6384 unsigned TargetNumRegisters = TTI.getNumberOfRegisters(true);
6385 for (int i = RUs.size() - 1; i >= 0; --i) {
6386 if (RUs[i].MaxLocalUsers <= TargetNumRegisters) {
6387 MaxVF = VFs[i];
6388 break;
6389 }
6390 }
6391 }
6392 return MaxVF;
6393}
6394
6395LoopVectorizationCostModel::VectorizationFactor
6396LoopVectorizationCostModel::selectVectorizationFactor(unsigned MaxVF) {
6397 float Cost = expectedCost(1).first;
6398#ifndef NDEBUG
6399 const float ScalarCost = Cost;
6400#endif /* NDEBUG */
6401 unsigned Width = 1;
6402 DEBUG(dbgs() << "LV: Scalar loop costs: " << (int)ScalarCost << ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Scalar loop costs: "
<< (int)ScalarCost << ".\n"; } } while (false)
;
6403
6404 bool ForceVectorization = Hints->getForce() == LoopVectorizeHints::FK_Enabled;
6405 // Ignore scalar width, because the user explicitly wants vectorization.
6406 if (ForceVectorization && MaxVF > 1) {
6407 Width = 2;
6408 Cost = expectedCost(Width).first / (float)Width;
6409 }
6410
6411 for (unsigned i = 2; i <= MaxVF; i *= 2) {
6412 // Notice that the vector loop needs to be executed less times, so
6413 // we need to divide the cost of the vector loops by the width of
6414 // the vector elements.
6415 VectorizationCostTy C = expectedCost(i);
6416 float VectorCost = C.first / (float)i;
6417 DEBUG(dbgs() << "LV: Vector loop of width " << ido { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Vector loop of width "
<< i << " costs: " << (int)VectorCost <<
".\n"; } } while (false)
6418 << " costs: " << (int)VectorCost << ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Vector loop of width "
<< i << " costs: " << (int)VectorCost <<
".\n"; } } while (false)
;
6419 if (!C.second && !ForceVectorization) {
6420 DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not considering vector loop of width "
<< i << " because it will not generate any vector instructions.\n"
; } } while (false)
6421 dbgs() << "LV: Not considering vector loop of width " << ido { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not considering vector loop of width "
<< i << " because it will not generate any vector instructions.\n"
; } } while (false)
6422 << " because it will not generate any vector instructions.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not considering vector loop of width "
<< i << " because it will not generate any vector instructions.\n"
; } } while (false)
;
6423 continue;
6424 }
6425 if (VectorCost < Cost) {
6426 Cost = VectorCost;
6427 Width = i;
6428 }
6429 }
6430
6431 DEBUG(if (ForceVectorization && Width > 1 && Cost >= ScalarCost) dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { if (ForceVectorization && Width
> 1 && Cost >= ScalarCost) dbgs() << "LV: Vectorization seems to be not beneficial, "
<< "but was forced by a user.\n"; } } while (false)
6432 << "LV: Vectorization seems to be not beneficial, "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { if (ForceVectorization && Width
> 1 && Cost >= ScalarCost) dbgs() << "LV: Vectorization seems to be not beneficial, "
<< "but was forced by a user.\n"; } } while (false)
6433 << "but was forced by a user.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { if (ForceVectorization && Width
> 1 && Cost >= ScalarCost) dbgs() << "LV: Vectorization seems to be not beneficial, "
<< "but was forced by a user.\n"; } } while (false)
;
6434 DEBUG(dbgs() << "LV: Selecting VF: " << Width << ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Selecting VF: " <<
Width << ".\n"; } } while (false)
;
6435 VectorizationFactor Factor = {Width, (unsigned)(Width * Cost)};
6436 return Factor;
6437}
6438
6439std::pair<unsigned, unsigned>
6440LoopVectorizationCostModel::getSmallestAndWidestTypes() {
6441 unsigned MinWidth = -1U;
6442 unsigned MaxWidth = 8;
6443 const DataLayout &DL = TheFunction->getParent()->getDataLayout();
6444
6445 // For each block.
6446 for (BasicBlock *BB : TheLoop->blocks()) {
6447 // For each instruction in the loop.
6448 for (Instruction &I : *BB) {
6449 Type *T = I.getType();
6450
6451 // Skip ignored values.
6452 if (ValuesToIgnore.count(&I))
6453 continue;
6454
6455 // Only examine Loads, Stores and PHINodes.
6456 if (!isa<LoadInst>(I) && !isa<StoreInst>(I) && !isa<PHINode>(I))
6457 continue;
6458
6459 // Examine PHI nodes that are reduction variables. Update the type to
6460 // account for the recurrence type.
6461 if (auto *PN = dyn_cast<PHINode>(&I)) {
6462 if (!Legal->isReductionVariable(PN))
6463 continue;
6464 RecurrenceDescriptor RdxDesc = (*Legal->getReductionVars())[PN];
6465 T = RdxDesc.getRecurrenceType();
6466 }
6467
6468 // Examine the stored values.
6469 if (auto *ST = dyn_cast<StoreInst>(&I))
6470 T = ST->getValueOperand()->getType();
6471
6472 // Ignore loaded pointer types and stored pointer types that are not
6473 // vectorizable.
6474 //
6475 // FIXME: The check here attempts to predict whether a load or store will
6476 // be vectorized. We only know this for certain after a VF has
6477 // been selected. Here, we assume that if an access can be
6478 // vectorized, it will be. We should also look at extending this
6479 // optimization to non-pointer types.
6480 //
6481 if (T->isPointerTy() && !isConsecutiveLoadOrStore(&I) &&
6482 !Legal->isAccessInterleaved(&I) && !Legal->isLegalGatherOrScatter(&I))
6483 continue;
6484
6485 MinWidth = std::min(MinWidth,
6486 (unsigned)DL.getTypeSizeInBits(T->getScalarType()));
6487 MaxWidth = std::max(MaxWidth,
6488 (unsigned)DL.getTypeSizeInBits(T->getScalarType()));
6489 }
6490 }
6491
6492 return {MinWidth, MaxWidth};
6493}
6494
6495unsigned LoopVectorizationCostModel::selectInterleaveCount(bool OptForSize,
6496 unsigned VF,
6497 unsigned LoopCost) {
6498
6499 // -- The interleave heuristics --
6500 // We interleave the loop in order to expose ILP and reduce the loop overhead.
6501 // There are many micro-architectural considerations that we can't predict
6502 // at this level. For example, frontend pressure (on decode or fetch) due to
6503 // code size, or the number and capabilities of the execution ports.
6504 //
6505 // We use the following heuristics to select the interleave count:
6506 // 1. If the code has reductions, then we interleave to break the cross
6507 // iteration dependency.
6508 // 2. If the loop is really small, then we interleave to reduce the loop
6509 // overhead.
6510 // 3. We don't interleave if we think that we will spill registers to memory
6511 // due to the increased register pressure.
6512
6513 // When we optimize for size, we don't interleave.
6514 if (OptForSize)
6515 return 1;
6516
6517 // We used the distance for the interleave count.
6518 if (Legal->getMaxSafeDepDistBytes() != -1U)
6519 return 1;
6520
6521 // Do not interleave loops with a relatively small trip count.
6522 unsigned TC = PSE.getSE()->getSmallConstantTripCount(TheLoop);
6523 if (TC > 1 && TC < TinyTripCountInterleaveThreshold)
6524 return 1;
6525
6526 unsigned TargetNumRegisters = TTI.getNumberOfRegisters(VF > 1);
6527 DEBUG(dbgs() << "LV: The target has " << TargetNumRegistersdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The target has " <<
TargetNumRegisters << " registers\n"; } } while (false
)
6528 << " registers\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The target has " <<
TargetNumRegisters << " registers\n"; } } while (false
)
;
6529
6530 if (VF == 1) {
6531 if (ForceTargetNumScalarRegs.getNumOccurrences() > 0)
6532 TargetNumRegisters = ForceTargetNumScalarRegs;
6533 } else {
6534 if (ForceTargetNumVectorRegs.getNumOccurrences() > 0)
6535 TargetNumRegisters = ForceTargetNumVectorRegs;
6536 }
6537
6538 RegisterUsage R = calculateRegisterUsage({VF})[0];
6539 // We divide by these constants so assume that we have at least one
6540 // instruction that uses at least one register.
6541 R.MaxLocalUsers = std::max(R.MaxLocalUsers, 1U);
6542 R.NumInstructions = std::max(R.NumInstructions, 1U);
6543
6544 // We calculate the interleave count using the following formula.
6545 // Subtract the number of loop invariants from the number of available
6546 // registers. These registers are used by all of the interleaved instances.
6547 // Next, divide the remaining registers by the number of registers that is
6548 // required by the loop, in order to estimate how many parallel instances
6549 // fit without causing spills. All of this is rounded down if necessary to be
6550 // a power of two. We want power of two interleave count to simplify any
6551 // addressing operations or alignment considerations.
6552 unsigned IC = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs) /
6553 R.MaxLocalUsers);
6554
6555 // Don't count the induction variable as interleaved.
6556 if (EnableIndVarRegisterHeur)
6557 IC = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs - 1) /
6558 std::max(1U, (R.MaxLocalUsers - 1)));
6559
6560 // Clamp the interleave ranges to reasonable counts.
6561 unsigned MaxInterleaveCount = TTI.getMaxInterleaveFactor(VF);
6562
6563 // Check if the user has overridden the max.
6564 if (VF == 1) {
6565 if (ForceTargetMaxScalarInterleaveFactor.getNumOccurrences() > 0)
6566 MaxInterleaveCount = ForceTargetMaxScalarInterleaveFactor;
6567 } else {
6568 if (ForceTargetMaxVectorInterleaveFactor.getNumOccurrences() > 0)
6569 MaxInterleaveCount = ForceTargetMaxVectorInterleaveFactor;
6570 }
6571
6572 // If we did not calculate the cost for VF (because the user selected the VF)
6573 // then we calculate the cost of VF here.
6574 if (LoopCost == 0)
6575 LoopCost = expectedCost(VF).first;
6576
6577 // Clamp the calculated IC to be between the 1 and the max interleave count
6578 // that the target allows.
6579 if (IC > MaxInterleaveCount)
6580 IC = MaxInterleaveCount;
6581 else if (IC < 1)
6582 IC = 1;
6583
6584 // Interleave if we vectorized this loop and there is a reduction that could
6585 // benefit from interleaving.
6586 if (VF > 1 && Legal->getReductionVars()->size()) {
6587 DEBUG(dbgs() << "LV: Interleaving because of reductions.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Interleaving because of reductions.\n"
; } } while (false)
;
6588 return IC;
6589 }
6590
6591 // Note that if we've already vectorized the loop we will have done the
6592 // runtime check and so interleaving won't require further checks.
6593 bool InterleavingRequiresRuntimePointerCheck =
6594 (VF == 1 && Legal->getRuntimePointerChecking()->Need);
6595
6596 // We want to interleave small loops in order to reduce the loop overhead and
6597 // potentially expose ILP opportunities.
6598 DEBUG(dbgs() << "LV: Loop cost is " << LoopCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop cost is " <<
LoopCost << '\n'; } } while (false)
;
6599 if (!InterleavingRequiresRuntimePointerCheck && LoopCost < SmallLoopCost) {
6600 // We assume that the cost overhead is 1 and we use the cost model
6601 // to estimate the cost of the loop and interleave until the cost of the
6602 // loop overhead is about 5% of the cost of the loop.
6603 unsigned SmallIC =
6604 std::min(IC, (unsigned)PowerOf2Floor(SmallLoopCost / LoopCost));
6605
6606 // Interleave until store/load ports (estimated by max interleave count) are
6607 // saturated.
6608 unsigned NumStores = Legal->getNumStores();
6609 unsigned NumLoads = Legal->getNumLoads();
6610 unsigned StoresIC = IC / (NumStores ? NumStores : 1);
6611 unsigned LoadsIC = IC / (NumLoads ? NumLoads : 1);
6612
6613 // If we have a scalar reduction (vector reductions are already dealt with
6614 // by this point), we can increase the critical path length if the loop
6615 // we're interleaving is inside another loop. Limit, by default to 2, so the
6616 // critical path only gets increased by one reduction operation.
6617 if (Legal->getReductionVars()->size() && TheLoop->getLoopDepth() > 1) {
6618 unsigned F = static_cast<unsigned>(MaxNestedScalarReductionIC);
6619 SmallIC = std::min(SmallIC, F);
6620 StoresIC = std::min(StoresIC, F);
6621 LoadsIC = std::min(LoadsIC, F);
6622 }
6623
6624 if (EnableLoadStoreRuntimeInterleave &&
6625 std::max(StoresIC, LoadsIC) > SmallIC) {
6626 DEBUG(dbgs() << "LV: Interleaving to saturate store or load ports.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Interleaving to saturate store or load ports.\n"
; } } while (false)
;
6627 return std::max(StoresIC, LoadsIC);
6628 }
6629
6630 DEBUG(dbgs() << "LV: Interleaving to reduce branch cost.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Interleaving to reduce branch cost.\n"
; } } while (false)
;
6631 return SmallIC;
6632 }
6633
6634 // Interleave if this is a large loop (small loops are already dealt with by
6635 // this point) that could benefit from interleaving.
6636 bool HasReductions = (Legal->getReductionVars()->size() > 0);
6637 if (TTI.enableAggressiveInterleaving(HasReductions)) {
6638 DEBUG(dbgs() << "LV: Interleaving to expose ILP.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Interleaving to expose ILP.\n"
; } } while (false)
;
6639 return IC;
6640 }
6641
6642 DEBUG(dbgs() << "LV: Not Interleaving.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not Interleaving.\n"
; } } while (false)
;
6643 return 1;
6644}
6645
6646SmallVector<LoopVectorizationCostModel::RegisterUsage, 8>
6647LoopVectorizationCostModel::calculateRegisterUsage(ArrayRef<unsigned> VFs) {
6648 // This function calculates the register usage by measuring the highest number
6649 // of values that are alive at a single location. Obviously, this is a very
6650 // rough estimation. We scan the loop in a topological order in order and
6651 // assign a number to each instruction. We use RPO to ensure that defs are
6652 // met before their users. We assume that each instruction that has in-loop
6653 // users starts an interval. We record every time that an in-loop value is
6654 // used, so we have a list of the first and last occurrences of each
6655 // instruction. Next, we transpose this data structure into a multi map that
6656 // holds the list of intervals that *end* at a specific location. This multi
6657 // map allows us to perform a linear search. We scan the instructions linearly
6658 // and record each time that a new interval starts, by placing it in a set.
6659 // If we find this value in the multi-map then we remove it from the set.
6660 // The max register usage is the maximum size of the set.
6661 // We also search for instructions that are defined outside the loop, but are
6662 // used inside the loop. We need this number separately from the max-interval
6663 // usage number because when we unroll, loop-invariant values do not take
6664 // more register.
6665 LoopBlocksDFS DFS(TheLoop);
6666 DFS.perform(LI);
6667
6668 RegisterUsage RU;
6669 RU.NumInstructions = 0;
6670
6671 // Each 'key' in the map opens a new interval. The values
6672 // of the map are the index of the 'last seen' usage of the
6673 // instruction that is the key.
6674 typedef DenseMap<Instruction *, unsigned> IntervalMap;
6675 // Maps instruction to its index.
6676 DenseMap<unsigned, Instruction *> IdxToInstr;
6677 // Marks the end of each interval.
6678 IntervalMap EndPoint;
6679 // Saves the list of instruction indices that are used in the loop.
6680 SmallSet<Instruction *, 8> Ends;
6681 // Saves the list of values that are used in the loop but are
6682 // defined outside the loop, such as arguments and constants.
6683 SmallPtrSet<Value *, 8> LoopInvariants;
6684
6685 unsigned Index = 0;
6686 for (BasicBlock *BB : make_range(DFS.beginRPO(), DFS.endRPO())) {
6687 RU.NumInstructions += BB->size();
6688 for (Instruction &I : *BB) {
6689 IdxToInstr[Index++] = &I;
6690
6691 // Save the end location of each USE.
6692 for (Value *U : I.operands()) {
6693 auto *Instr = dyn_cast<Instruction>(U);
6694
6695 // Ignore non-instruction values such as arguments, constants, etc.
6696 if (!Instr)
6697 continue;
6698
6699 // If this instruction is outside the loop then record it and continue.
6700 if (!TheLoop->contains(Instr)) {
6701 LoopInvariants.insert(Instr);
6702 continue;
6703 }
6704
6705 // Overwrite previous end points.
6706 EndPoint[Instr] = Index;
6707 Ends.insert(Instr);
6708 }
6709 }
6710 }
6711
6712 // Saves the list of intervals that end with the index in 'key'.
6713 typedef SmallVector<Instruction *, 2> InstrList;
6714 DenseMap<unsigned, InstrList> TransposeEnds;
6715
6716 // Transpose the EndPoints to a list of values that end at each index.
6717 for (auto &Interval : EndPoint)
6718 TransposeEnds[Interval.second].push_back(Interval.first);
6719
6720 SmallSet<Instruction *, 8> OpenIntervals;
6721
6722 // Get the size of the widest register.
6723 unsigned MaxSafeDepDist = -1U;
6724 if (Legal->getMaxSafeDepDistBytes() != -1U)
6725 MaxSafeDepDist = Legal->getMaxSafeDepDistBytes() * 8;
6726 unsigned WidestRegister =
6727 std::min(TTI.getRegisterBitWidth(true), MaxSafeDepDist);
6728 const DataLayout &DL = TheFunction->getParent()->getDataLayout();
6729
6730 SmallVector<RegisterUsage, 8> RUs(VFs.size());
6731 SmallVector<unsigned, 8> MaxUsages(VFs.size(), 0);
6732
6733 DEBUG(dbgs() << "LV(REG): Calculating max register usage:\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): Calculating max register usage:\n"
; } } while (false)
;
6734
6735 // A lambda that gets the register usage for the given type and VF.
6736 auto GetRegUsage = [&DL, WidestRegister](Type *Ty, unsigned VF) {
6737 if (Ty->isTokenTy())
6738 return 0U;
6739 unsigned TypeSize = DL.getTypeSizeInBits(Ty->getScalarType());
6740 return std::max<unsigned>(1, VF * TypeSize / WidestRegister);
6741 };
6742
6743 for (unsigned int i = 0; i < Index; ++i) {
6744 Instruction *I = IdxToInstr[i];
6745
6746 // Remove all of the instructions that end at this location.
6747 InstrList &List = TransposeEnds[i];
6748 for (Instruction *ToRemove : List)
6749 OpenIntervals.erase(ToRemove);
6750
6751 // Ignore instructions that are never used within the loop.
6752 if (!Ends.count(I))
6753 continue;
6754
6755 // Skip ignored values.
6756 if (ValuesToIgnore.count(I))
6757 continue;
6758
6759 // For each VF find the maximum usage of registers.
6760 for (unsigned j = 0, e = VFs.size(); j < e; ++j) {
6761 if (VFs[j] == 1) {
6762 MaxUsages[j] = std::max(MaxUsages[j], OpenIntervals.size());
6763 continue;
6764 }
6765 collectUniformsAndScalars(VFs[j]);
6766 // Count the number of live intervals.
6767 unsigned RegUsage = 0;
6768 for (auto Inst : OpenIntervals) {
6769 // Skip ignored values for VF > 1.
6770 if (VecValuesToIgnore.count(Inst) ||
6771 isScalarAfterVectorization(Inst, VFs[j]))
6772 continue;
6773 RegUsage += GetRegUsage(Inst->getType(), VFs[j]);
6774 }
6775 MaxUsages[j] = std::max(MaxUsages[j], RegUsage);
6776 }
6777
6778 DEBUG(dbgs() << "LV(REG): At #" << i << " Interval # "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): At #" <<
i << " Interval # " << OpenIntervals.size() <<
'\n'; } } while (false)
6779 << OpenIntervals.size() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): At #" <<
i << " Interval # " << OpenIntervals.size() <<
'\n'; } } while (false)
;
6780
6781 // Add the current instruction to the list of open intervals.
6782 OpenIntervals.insert(I);
6783 }
6784
6785 for (unsigned i = 0, e = VFs.size(); i < e; ++i) {
6786 unsigned Invariant = 0;
6787 if (VFs[i] == 1)
6788 Invariant = LoopInvariants.size();
6789 else {
6790 for (auto Inst : LoopInvariants)
6791 Invariant += GetRegUsage(Inst->getType(), VFs[i]);
6792 }
6793
6794 DEBUG(dbgs() << "LV(REG): VF = " << VFs[i] << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): VF = " <<
VFs[i] << '\n'; } } while (false)
;
6795 DEBUG(dbgs() << "LV(REG): Found max usage: " << MaxUsages[i] << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): Found max usage: "
<< MaxUsages[i] << '\n'; } } while (false)
;
6796 DEBUG(dbgs() << "LV(REG): Found invariant usage: " << Invariant << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): Found invariant usage: "
<< Invariant << '\n'; } } while (false)
;
6797 DEBUG(dbgs() << "LV(REG): LoopSize: " << RU.NumInstructions << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): LoopSize: " <<
RU.NumInstructions << '\n'; } } while (false)
;
6798
6799 RU.LoopInvariantRegs = Invariant;
6800 RU.MaxLocalUsers = MaxUsages[i];
6801 RUs[i] = RU;
6802 }
6803
6804 return RUs;
6805}
6806
6807void LoopVectorizationCostModel::collectInstsToScalarize(unsigned VF) {
6808
6809 // If we aren't vectorizing the loop, or if we've already collected the
6810 // instructions to scalarize, there's nothing to do. Collection may already
6811 // have occurred if we have a user-selected VF and are now computing the
6812 // expected cost for interleaving.
6813 if (VF < 2 || InstsToScalarize.count(VF))
6814 return;
6815
6816 // Initialize a mapping for VF in InstsToScalalarize. If we find that it's
6817 // not profitable to scalarize any instructions, the presence of VF in the
6818 // map will indicate that we've analyzed it already.
6819 ScalarCostsTy &ScalarCostsVF = InstsToScalarize[VF];
6820
6821 // Find all the instructions that are scalar with predication in the loop and
6822 // determine if it would be better to not if-convert the blocks they are in.
6823 // If so, we also record the instructions to scalarize.
6824 for (BasicBlock *BB : TheLoop->blocks()) {
6825 if (!Legal->blockNeedsPredication(BB))
6826 continue;
6827 for (Instruction &I : *BB)
6828 if (Legal->isScalarWithPredication(&I)) {
6829 ScalarCostsTy ScalarCosts;
6830 if (computePredInstDiscount(&I, ScalarCosts, VF) >= 0)
6831 ScalarCostsVF.insert(ScalarCosts.begin(), ScalarCosts.end());
6832
6833 // Remember that BB will remain after vectorization.
6834 PredicatedBBsAfterVectorization.insert(BB);
6835 }
6836 }
6837}
6838
6839int LoopVectorizationCostModel::computePredInstDiscount(
6840 Instruction *PredInst, DenseMap<Instruction *, unsigned> &ScalarCosts,
6841 unsigned VF) {
6842
6843 assert(!isUniformAfterVectorization(PredInst, VF) &&((!isUniformAfterVectorization(PredInst, VF) && "Instruction marked uniform-after-vectorization will be predicated"
) ? static_cast<void> (0) : __assert_fail ("!isUniformAfterVectorization(PredInst, VF) && \"Instruction marked uniform-after-vectorization will be predicated\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6844, __PRETTY_FUNCTION__))
6844 "Instruction marked uniform-after-vectorization will be predicated")((!isUniformAfterVectorization(PredInst, VF) && "Instruction marked uniform-after-vectorization will be predicated"
) ? static_cast<void> (0) : __assert_fail ("!isUniformAfterVectorization(PredInst, VF) && \"Instruction marked uniform-after-vectorization will be predicated\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6844, __PRETTY_FUNCTION__))
;
6845
6846 // Initialize the discount to zero, meaning that the scalar version and the
6847 // vector version cost the same.
6848 int Discount = 0;
6849
6850 // Holds instructions to analyze. The instructions we visit are mapped in
6851 // ScalarCosts. Those instructions are the ones that would be scalarized if
6852 // we find that the scalar version costs less.
6853 SmallVector<Instruction *, 8> Worklist;
6854
6855 // Returns true if the given instruction can be scalarized.
6856 auto canBeScalarized = [&](Instruction *I) -> bool {
6857
6858 // We only attempt to scalarize instructions forming a single-use chain
6859 // from the original predicated block that would otherwise be vectorized.
6860 // Although not strictly necessary, we give up on instructions we know will
6861 // already be scalar to avoid traversing chains that are unlikely to be
6862 // beneficial.
6863 if (!I->hasOneUse() || PredInst->getParent() != I->getParent() ||
6864 isScalarAfterVectorization(I, VF))
6865 return false;
6866
6867 // If the instruction is scalar with predication, it will be analyzed
6868 // separately. We ignore it within the context of PredInst.
6869 if (Legal->isScalarWithPredication(I))
6870 return false;
6871
6872 // If any of the instruction's operands are uniform after vectorization,
6873 // the instruction cannot be scalarized. This prevents, for example, a
6874 // masked load from being scalarized.
6875 //
6876 // We assume we will only emit a value for lane zero of an instruction
6877 // marked uniform after vectorization, rather than VF identical values.
6878 // Thus, if we scalarize an instruction that uses a uniform, we would
6879 // create uses of values corresponding to the lanes we aren't emitting code
6880 // for. This behavior can be changed by allowing getScalarValue to clone
6881 // the lane zero values for uniforms rather than asserting.
6882 for (Use &U : I->operands())
6883 if (auto *J = dyn_cast<Instruction>(U.get()))
6884 if (isUniformAfterVectorization(J, VF))
6885 return false;
6886
6887 // Otherwise, we can scalarize the instruction.
6888 return true;
6889 };
6890
6891 // Returns true if an operand that cannot be scalarized must be extracted
6892 // from a vector. We will account for this scalarization overhead below. Note
6893 // that the non-void predicated instructions are placed in their own blocks,
6894 // and their return values are inserted into vectors. Thus, an extract would
6895 // still be required.
6896 auto needsExtract = [&](Instruction *I) -> bool {
6897 return TheLoop->contains(I) && !isScalarAfterVectorization(I, VF);
6898 };
6899
6900 // Compute the expected cost discount from scalarizing the entire expression
6901 // feeding the predicated instruction. We currently only consider expressions
6902 // that are single-use instruction chains.
6903 Worklist.push_back(PredInst);
6904 while (!Worklist.empty()) {
6905 Instruction *I = Worklist.pop_back_val();
6906
6907 // If we've already analyzed the instruction, there's nothing to do.
6908 if (ScalarCosts.count(I))
6909 continue;
6910
6911 // Compute the cost of the vector instruction. Note that this cost already
6912 // includes the scalarization overhead of the predicated instruction.
6913 unsigned VectorCost = getInstructionCost(I, VF).first;
6914
6915 // Compute the cost of the scalarized instruction. This cost is the cost of
6916 // the instruction as if it wasn't if-converted and instead remained in the
6917 // predicated block. We will scale this cost by block probability after
6918 // computing the scalarization overhead.
6919 unsigned ScalarCost = VF * getInstructionCost(I, 1).first;
6920
6921 // Compute the scalarization overhead of needed insertelement instructions
6922 // and phi nodes.
6923 if (Legal->isScalarWithPredication(I) && !I->getType()->isVoidTy()) {
6924 ScalarCost += TTI.getScalarizationOverhead(ToVectorTy(I->getType(), VF),
6925 true, false);
6926 ScalarCost += VF * TTI.getCFInstrCost(Instruction::PHI);
6927 }
6928
6929 // Compute the scalarization overhead of needed extractelement
6930 // instructions. For each of the instruction's operands, if the operand can
6931 // be scalarized, add it to the worklist; otherwise, account for the
6932 // overhead.
6933 for (Use &U : I->operands())
6934 if (auto *J = dyn_cast<Instruction>(U.get())) {
6935 assert(VectorType::isValidElementType(J->getType()) &&((VectorType::isValidElementType(J->getType()) && "Instruction has non-scalar type"
) ? static_cast<void> (0) : __assert_fail ("VectorType::isValidElementType(J->getType()) && \"Instruction has non-scalar type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6936, __PRETTY_FUNCTION__))
6936 "Instruction has non-scalar type")((VectorType::isValidElementType(J->getType()) && "Instruction has non-scalar type"
) ? static_cast<void> (0) : __assert_fail ("VectorType::isValidElementType(J->getType()) && \"Instruction has non-scalar type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6936, __PRETTY_FUNCTION__))
;
6937 if (canBeScalarized(J))
6938 Worklist.push_back(J);
6939 else if (needsExtract(J))
6940 ScalarCost += TTI.getScalarizationOverhead(
6941 ToVectorTy(J->getType(),VF), false, true);
6942 }
6943
6944 // Scale the total scalar cost by block probability.
6945 ScalarCost /= getReciprocalPredBlockProb();
6946
6947 // Compute the discount. A non-negative discount means the vector version
6948 // of the instruction costs more, and scalarizing would be beneficial.
6949 Discount += VectorCost - ScalarCost;
6950 ScalarCosts[I] = ScalarCost;
6951 }
6952
6953 return Discount;
6954}
6955
6956LoopVectorizationCostModel::VectorizationCostTy
6957LoopVectorizationCostModel::expectedCost(unsigned VF) {
6958 VectorizationCostTy Cost;
6959
6960 // Collect Uniform and Scalar instructions after vectorization with VF.
6961 collectUniformsAndScalars(VF);
6962
6963 // Collect the instructions (and their associated costs) that will be more
6964 // profitable to scalarize.
6965 collectInstsToScalarize(VF);
6966
6967 // For each block.
6968 for (BasicBlock *BB : TheLoop->blocks()) {
6969 VectorizationCostTy BlockCost;
6970
6971 // For each instruction in the old loop.
6972 for (Instruction &I : *BB) {
6973 // Skip dbg intrinsics.
6974 if (isa<DbgInfoIntrinsic>(I))
6975 continue;
6976
6977 // Skip ignored values.
6978 if (ValuesToIgnore.count(&I))
6979 continue;
6980
6981 VectorizationCostTy C = getInstructionCost(&I, VF);
6982
6983 // Check if we should override the cost.
6984 if (ForceTargetInstructionCost.getNumOccurrences() > 0)
6985 C.first = ForceTargetInstructionCost;
6986
6987 BlockCost.first += C.first;
6988 BlockCost.second |= C.second;
6989 DEBUG(dbgs() << "LV: Found an estimated cost of " << C.first << " for VF "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an estimated cost of "
<< C.first << " for VF " << VF << " For instruction: "
<< I << '\n'; } } while (false)
6990 << VF << " For instruction: " << I << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an estimated cost of "
<< C.first << " for VF " << VF << " For instruction: "
<< I << '\n'; } } while (false)
;
6991 }
6992
6993 // If we are vectorizing a predicated block, it will have been
6994 // if-converted. This means that the block's instructions (aside from
6995 // stores and instructions that may divide by zero) will now be
6996 // unconditionally executed. For the scalar case, we may not always execute
6997 // the predicated block. Thus, scale the block's cost by the probability of
6998 // executing it.
6999 if (VF == 1 && Legal->blockNeedsPredication(BB))
7000 BlockCost.first /= getReciprocalPredBlockProb();
7001
7002 Cost.first += BlockCost.first;
7003 Cost.second |= BlockCost.second;
7004 }
7005
7006 return Cost;
7007}
7008
7009/// \brief Gets Address Access SCEV after verifying that the access pattern
7010/// is loop invariant except the induction variable dependence.
7011///
7012/// This SCEV can be sent to the Target in order to estimate the address
7013/// calculation cost.
7014static const SCEV *getAddressAccessSCEV(
7015 Value *Ptr,
7016 LoopVectorizationLegality *Legal,
7017 ScalarEvolution *SE,
7018 const Loop *TheLoop) {
7019 auto *Gep = dyn_cast<GetElementPtrInst>(Ptr);
7020 if (!Gep)
7021 return nullptr;
7022
7023 // We are looking for a gep with all loop invariant indices except for one
7024 // which should be an induction variable.
7025 unsigned NumOperands = Gep->getNumOperands();
7026 for (unsigned i = 1; i < NumOperands; ++i) {
7027 Value *Opd = Gep->getOperand(i);
7028 if (!SE->isLoopInvariant(SE->getSCEV(Opd), TheLoop) &&
7029 !Legal->isInductionVariable(Opd))
7030 return nullptr;
7031 }
7032
7033 // Now we know we have a GEP ptr, %inv, %ind, %inv. return the Ptr SCEV.
7034 return SE->getSCEV(Ptr);
7035}
7036
7037static bool isStrideMul(Instruction *I, LoopVectorizationLegality *Legal) {
7038 return Legal->hasStride(I->getOperand(0)) ||
7039 Legal->hasStride(I->getOperand(1));
7040}
7041
7042unsigned LoopVectorizationCostModel::getMemInstScalarizationCost(Instruction *I,
7043 unsigned VF) {
7044 Type *ValTy = getMemInstValueType(I);
7045 auto SE = PSE.getSE();
7046
7047 unsigned Alignment = getMemInstAlignment(I);
7048 unsigned AS = getMemInstAddressSpace(I);
7049 Value *Ptr = getPointerOperand(I);
7050 Type *PtrTy = ToVectorTy(Ptr->getType(), VF);
7051
7052 // Figure out whether the access is strided and get the stride value
7053 // if it's known in compile time
7054 const SCEV *PtrSCEV = getAddressAccessSCEV(Ptr, Legal, SE, TheLoop);
7055
7056 // Get the cost of the scalar memory instruction and address computation.
7057 unsigned Cost = VF * TTI.getAddressComputationCost(PtrTy, SE, PtrSCEV);
7058
7059 Cost += VF *
7060 TTI.getMemoryOpCost(I->getOpcode(), ValTy->getScalarType(), Alignment,
7061 AS, I);
7062
7063 // Get the overhead of the extractelement and insertelement instructions
7064 // we might create due to scalarization.
7065 Cost += getScalarizationOverhead(I, VF, TTI);
7066
7067 // If we have a predicated store, it may not be executed for each vector
7068 // lane. Scale the cost by the probability of executing the predicated
7069 // block.
7070 if (Legal->isScalarWithPredication(I))
7071 Cost /= getReciprocalPredBlockProb();
7072
7073 return Cost;
7074}
7075
7076unsigned LoopVectorizationCostModel::getConsecutiveMemOpCost(Instruction *I,
7077 unsigned VF) {
7078 Type *ValTy = getMemInstValueType(I);
7079 Type *VectorTy = ToVectorTy(ValTy, VF);
7080 unsigned Alignment = getMemInstAlignment(I);
7081 Value *Ptr = getPointerOperand(I);
7082 unsigned AS = getMemInstAddressSpace(I);
7083 int ConsecutiveStride = Legal->isConsecutivePtr(Ptr);
7084
7085 assert((ConsecutiveStride == 1 || ConsecutiveStride == -1) &&(((ConsecutiveStride == 1 || ConsecutiveStride == -1) &&
"Stride should be 1 or -1 for consecutive memory access") ? static_cast
<void> (0) : __assert_fail ("(ConsecutiveStride == 1 || ConsecutiveStride == -1) && \"Stride should be 1 or -1 for consecutive memory access\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 7086, __PRETTY_FUNCTION__))
7086 "Stride should be 1 or -1 for consecutive memory access")(((ConsecutiveStride == 1 || ConsecutiveStride == -1) &&
"Stride should be 1 or -1 for consecutive memory access") ? static_cast
<void> (0) : __assert_fail ("(ConsecutiveStride == 1 || ConsecutiveStride == -1) && \"Stride should be 1 or -1 for consecutive memory access\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 7086, __PRETTY_FUNCTION__))
;
7087 unsigned Cost = 0;
7088 if (Legal->isMaskRequired(I))
7089 Cost += TTI.getMaskedMemoryOpCost(I->getOpcode(), VectorTy, Alignment, AS);
7090 else
7091 Cost += TTI.getMemoryOpCost(I->getOpcode(), VectorTy, Alignment, AS, I);
7092
7093 bool Reverse = ConsecutiveStride < 0;
7094 if (Reverse)
7095 Cost += TTI.getShuffleCost(TargetTransformInfo::SK_Reverse, VectorTy, 0);
7096 return Cost;
7097}
7098
7099unsigned LoopVectorizationCostModel::getUniformMemOpCost(Instruction *I,
7100 unsigned VF) {
7101 LoadInst *LI = cast<LoadInst>(I);
7102 Type *ValTy = LI->getType();
7103 Type *VectorTy = ToVectorTy(ValTy, VF);
7104 unsigned Alignment = LI->getAlignment();
7105 unsigned AS = LI->getPointerAddressSpace();
7106
7107 return TTI.getAddressComputationCost(ValTy) +
7108 TTI.getMemoryOpCost(Instruction::Load, ValTy, Alignment, AS) +
7109 TTI.getShuffleCost(TargetTransformInfo::SK_Broadcast, VectorTy);
7110}
7111
7112unsigned LoopVectorizationCostModel::getGatherScatterCost(Instruction *I,
7113 unsigned VF) {
7114 Type *ValTy = getMemInstValueType(I);
7115 Type *VectorTy = ToVectorTy(ValTy, VF);
7116 unsigned Alignment = getMemInstAlignment(I);
7117 Value *Ptr = getPointerOperand(I);
7118
7119 return TTI.getAddressComputationCost(VectorTy) +
7120 TTI.getGatherScatterOpCost(I->getOpcode(), VectorTy, Ptr,
7121 Legal->isMaskRequired(I), Alignment);
7122}
7123
7124unsigned LoopVectorizationCostModel::getInterleaveGroupCost(Instruction *I,
7125 unsigned VF) {
7126 Type *ValTy = getMemInstValueType(I);
7127 Type *VectorTy = ToVectorTy(ValTy, VF);
7128 unsigned AS = getMemInstAddressSpace(I);
7129
7130 auto Group = Legal->getInterleavedAccessGroup(I);
7131 assert(Group && "Fail to get an interleaved access group.")((Group && "Fail to get an interleaved access group."
) ? static_cast<void> (0) : __assert_fail ("Group && \"Fail to get an interleaved access group.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 7131, __PRETTY_FUNCTION__))
;
7132
7133 unsigned InterleaveFactor = Group->getFactor();
7134 Type *WideVecTy = VectorType::get(ValTy, VF * InterleaveFactor);
7135
7136 // Holds the indices of existing members in an interleaved load group.
7137 // An interleaved store group doesn't need this as it doesn't allow gaps.
7138 SmallVector<unsigned, 4> Indices;
7139 if (isa<LoadInst>(I)) {
7140 for (unsigned i = 0; i < InterleaveFactor; i++)
7141 if (Group->getMember(i))
7142 Indices.push_back(i);
7143 }
7144
7145 // Calculate the cost of the whole interleaved group.
7146 unsigned Cost = TTI.getInterleavedMemoryOpCost(I->getOpcode(), WideVecTy,
7147 Group->getFactor(), Indices,
7148 Group->getAlignment(), AS);
7149
7150 if (Group->isReverse())
7151 Cost += Group->getNumMembers() *
7152 TTI.getShuffleCost(TargetTransformInfo::SK_Reverse, VectorTy, 0);
7153 return Cost;
7154}
7155
7156unsigned LoopVectorizationCostModel::getMemoryInstructionCost(Instruction *I,
7157 unsigned VF) {
7158
7159 // Calculate scalar cost only. Vectorization cost should be ready at this
7160 // moment.
7161 if (VF == 1) {
7162 Type *ValTy = getMemInstValueType(I);
7163 unsigned Alignment = getMemInstAlignment(I);
7164 unsigned AS = getMemInstAddressSpace(I);
7165
7166 return TTI.getAddressComputationCost(ValTy) +
7167 TTI.getMemoryOpCost(I->getOpcode(), ValTy, Alignment, AS, I);
7168 }
7169 return getWideningCost(I, VF);
7170}
7171
7172LoopVectorizationCostModel::VectorizationCostTy
7173LoopVectorizationCostModel::getInstructionCost(Instruction *I, unsigned VF) {
7174 // If we know that this instruction will remain uniform, check the cost of
7175 // the scalar version.
7176 if (isUniformAfterVectorization(I, VF))
7177 VF = 1;
7178
7179 if (VF > 1 && isProfitableToScalarize(I, VF))
7180 return VectorizationCostTy(InstsToScalarize[VF][I], false);
7181
7182 // Forced scalars do not have any scalarization overhead.
7183 if (VF > 1 && ForcedScalars.count(VF) &&
7184 ForcedScalars.find(VF)->second.count(I))
7185 return VectorizationCostTy((getInstructionCost(I, 1).first * VF), false);
7186
7187 Type *VectorTy;
7188 unsigned C = getInstructionCost(I, VF, VectorTy);
7189
7190 bool TypeNotScalarized =
7191 VF > 1 && VectorTy->isVectorTy() && TTI.getNumberOfParts(VectorTy) < VF;
7192 return VectorizationCostTy(C, TypeNotScalarized);
7193}
7194
7195void LoopVectorizationCostModel::setCostBasedWideningDecision(unsigned VF) {
7196 if (VF == 1)
7197 return;
7198 for (BasicBlock *BB : TheLoop->blocks()) {
7199 // For each instruction in the old loop.
7200 for (Instruction &I : *BB) {
7201 Value *Ptr = getPointerOperand(&I);
7202 if (!Ptr)
7203 continue;
7204
7205 if (isa<LoadInst>(&I) && Legal->isUniform(Ptr)) {
7206 // Scalar load + broadcast
7207 unsigned Cost = getUniformMemOpCost(&I, VF);
7208 setWideningDecision(&I, VF, CM_Scalarize, Cost);
7209 continue;
7210 }
7211
7212 // We assume that widening is the best solution when possible.
7213 if (Legal->memoryInstructionCanBeWidened(&I, VF)) {
7214 unsigned Cost = getConsecutiveMemOpCost(&I, VF);
7215 setWideningDecision(&I, VF, CM_Widen, Cost);
7216 continue;
7217 }
7218
7219 // Choose between Interleaving, Gather/Scatter or Scalarization.
7220 unsigned InterleaveCost = UINT_MAX(2147483647 *2U +1U);
7221 unsigned NumAccesses = 1;
7222 if (Legal->isAccessInterleaved(&I)) {
7223 auto Group = Legal->getInterleavedAccessGroup(&I);
7224 assert(Group && "Fail to get an interleaved access group.")((Group && "Fail to get an interleaved access group."
) ? static_cast<void> (0) : __assert_fail ("Group && \"Fail to get an interleaved access group.\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 7224, __PRETTY_FUNCTION__))
;
7225
7226 // Make one decision for the whole group.
7227 if (getWideningDecision(&I, VF) != CM_Unknown)
7228 continue;
7229
7230 NumAccesses = Group->getNumMembers();
7231 InterleaveCost = getInterleaveGroupCost(&I, VF);
7232 }
7233
7234 unsigned GatherScatterCost =
7235 Legal->isLegalGatherOrScatter(&I)
7236 ? getGatherScatterCost(&I, VF) * NumAccesses
7237 : UINT_MAX(2147483647 *2U +1U);
7238
7239 unsigned ScalarizationCost =
7240 getMemInstScalarizationCost(&I, VF) * NumAccesses;
7241
7242 // Choose better solution for the current VF,
7243 // write down this decision and use it during vectorization.
7244 unsigned Cost;
7245 InstWidening Decision;
7246 if (InterleaveCost <= GatherScatterCost &&
7247 InterleaveCost < ScalarizationCost) {
7248 Decision = CM_Interleave;
7249 Cost = InterleaveCost;
7250 } else if (GatherScatterCost < ScalarizationCost) {
7251 Decision = CM_GatherScatter;
7252 Cost = GatherScatterCost;
7253 } else {
7254 Decision = CM_Scalarize;
7255 Cost = ScalarizationCost;
7256 }
7257 // If the instructions belongs to an interleave group, the whole group
7258 // receives the same decision. The whole group receives the cost, but
7259 // the cost will actually be assigned to one instruction.
7260 if (auto Group = Legal->getInterleavedAccessGroup(&I))
7261 setWideningDecision(Group, VF, Decision, Cost);
7262 else
7263 setWideningDecision(&I, VF, Decision, Cost);
7264 }
7265 }
7266
7267 // Make sure that any load of address and any other address computation
7268 // remains scalar unless there is gather/scatter support. This avoids
7269 // inevitable extracts into address registers, and also has the benefit of
7270 // activating LSR more, since that pass can't optimize vectorized
7271 // addresses.
7272 if (TTI.prefersVectorizedAddressing())
7273 return;
7274
7275 // Start with all scalar pointer uses.
7276 SmallPtrSet<Instruction *, 8> AddrDefs;
7277 for (BasicBlock *BB : TheLoop->blocks())
7278 for (Instruction &I : *BB) {
7279 Instruction *PtrDef =
7280 dyn_cast_or_null<Instruction>(getPointerOperand(&I));
7281 if (PtrDef && TheLoop->contains(PtrDef) &&
7282 getWideningDecision(&I, VF) != CM_GatherScatter)
7283 AddrDefs.insert(PtrDef);
7284 }
7285
7286 // Add all instructions used to generate the addresses.
7287 SmallVector<Instruction *, 4> Worklist;
7288 for (auto *I : AddrDefs)
7289 Worklist.push_back(I);
7290 while (!Worklist.empty()) {
7291 Instruction *I = Worklist.pop_back_val();
7292 for (auto &Op : I->operands())
7293 if (auto *InstOp = dyn_cast<Instruction>(Op))
7294 if ((InstOp->getParent() == I->getParent()) && !isa<PHINode>(InstOp) &&
7295 AddrDefs.insert(InstOp).second == true)
7296</