Bug Summary

File:lib/Transforms/Vectorize/LoopVectorize.cpp
Location:line 5604, column 75
Description:Division by zero

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// Other ideas/concepts are from:
38// A. Zaks and D. Nuzman. Autovectorization in GCC-two years later.
39//
40// S. Maleki, Y. Gao, M. Garzaran, T. Wong and D. Padua. An Evaluation of
41// Vectorizing Compilers.
42//
43//===----------------------------------------------------------------------===//
44
45#include "llvm/Transforms/Vectorize.h"
46#include "llvm/ADT/DenseMap.h"
47#include "llvm/ADT/EquivalenceClasses.h"
48#include "llvm/ADT/Hashing.h"
49#include "llvm/ADT/MapVector.h"
50#include "llvm/ADT/SetVector.h"
51#include "llvm/ADT/SmallPtrSet.h"
52#include "llvm/ADT/SmallSet.h"
53#include "llvm/ADT/SmallVector.h"
54#include "llvm/ADT/Statistic.h"
55#include "llvm/ADT/StringExtras.h"
56#include "llvm/Analysis/AliasAnalysis.h"
57#include "llvm/Analysis/AliasSetTracker.h"
58#include "llvm/Analysis/BlockFrequencyInfo.h"
59#include "llvm/Analysis/LoopInfo.h"
60#include "llvm/Analysis/LoopIterator.h"
61#include "llvm/Analysis/LoopPass.h"
62#include "llvm/Analysis/ScalarEvolution.h"
63#include "llvm/Analysis/ScalarEvolutionExpander.h"
64#include "llvm/Analysis/ScalarEvolutionExpressions.h"
65#include "llvm/Analysis/TargetTransformInfo.h"
66#include "llvm/Analysis/ValueTracking.h"
67#include "llvm/IR/Constants.h"
68#include "llvm/IR/DataLayout.h"
69#include "llvm/IR/DebugInfo.h"
70#include "llvm/IR/DerivedTypes.h"
71#include "llvm/IR/DiagnosticInfo.h"
72#include "llvm/IR/Dominators.h"
73#include "llvm/IR/Function.h"
74#include "llvm/IR/IRBuilder.h"
75#include "llvm/IR/Instructions.h"
76#include "llvm/IR/IntrinsicInst.h"
77#include "llvm/IR/LLVMContext.h"
78#include "llvm/IR/Module.h"
79#include "llvm/IR/PatternMatch.h"
80#include "llvm/IR/Type.h"
81#include "llvm/IR/Value.h"
82#include "llvm/IR/ValueHandle.h"
83#include "llvm/IR/Verifier.h"
84#include "llvm/Pass.h"
85#include "llvm/Support/BranchProbability.h"
86#include "llvm/Support/CommandLine.h"
87#include "llvm/Support/Debug.h"
88#include "llvm/Support/raw_ostream.h"
89#include "llvm/Transforms/Scalar.h"
90#include "llvm/Transforms/Utils/BasicBlockUtils.h"
91#include "llvm/Transforms/Utils/Local.h"
92#include "llvm/Transforms/Utils/VectorUtils.h"
93#include <algorithm>
94#include <map>
95#include <tuple>
96
97using namespace llvm;
98using namespace llvm::PatternMatch;
99
100#define LV_NAME"loop-vectorize" "loop-vectorize"
101#define DEBUG_TYPE"loop-vectorize" LV_NAME"loop-vectorize"
102
103STATISTIC(LoopsVectorized, "Number of loops vectorized")static llvm::Statistic LoopsVectorized = { "loop-vectorize", "Number of loops vectorized"
, 0, 0 }
;
104STATISTIC(LoopsAnalyzed, "Number of loops analyzed for vectorization")static llvm::Statistic LoopsAnalyzed = { "loop-vectorize", "Number of loops analyzed for vectorization"
, 0, 0 }
;
105
106static cl::opt<unsigned>
107VectorizationFactor("force-vector-width", cl::init(0), cl::Hidden,
108 cl::desc("Sets the SIMD width. Zero is autoselect."));
109
110static cl::opt<unsigned>
111VectorizationInterleave("force-vector-interleave", cl::init(0), cl::Hidden,
112 cl::desc("Sets the vectorization interleave count. "
113 "Zero is autoselect."));
114
115static cl::opt<bool>
116EnableIfConversion("enable-if-conversion", cl::init(true), cl::Hidden,
117 cl::desc("Enable if-conversion during vectorization."));
118
119/// We don't vectorize loops with a known constant trip count below this number.
120static cl::opt<unsigned>
121TinyTripCountVectorThreshold("vectorizer-min-trip-count", cl::init(16),
122 cl::Hidden,
123 cl::desc("Don't vectorize loops with a constant "
124 "trip count that is smaller than this "
125 "value."));
126
127/// This enables versioning on the strides of symbolically striding memory
128/// accesses in code like the following.
129/// for (i = 0; i < N; ++i)
130/// A[i * Stride1] += B[i * Stride2] ...
131///
132/// Will be roughly translated to
133/// if (Stride1 == 1 && Stride2 == 1) {
134/// for (i = 0; i < N; i+=4)
135/// A[i:i+3] += ...
136/// } else
137/// ...
138static cl::opt<bool> EnableMemAccessVersioning(
139 "enable-mem-access-versioning", cl::init(true), cl::Hidden,
140 cl::desc("Enable symblic stride memory access versioning"));
141
142/// We don't unroll loops with a known constant trip count below this number.
143static const unsigned TinyTripCountUnrollThreshold = 128;
144
145/// When performing memory disambiguation checks at runtime do not make more
146/// than this number of comparisons.
147static const unsigned RuntimeMemoryCheckThreshold = 8;
148
149/// Maximum simd width.
150static const unsigned MaxVectorWidth = 64;
151
152static cl::opt<unsigned> ForceTargetNumScalarRegs(
153 "force-target-num-scalar-regs", cl::init(0), cl::Hidden,
154 cl::desc("A flag that overrides the target's number of scalar registers."));
155
156static cl::opt<unsigned> ForceTargetNumVectorRegs(
157 "force-target-num-vector-regs", cl::init(0), cl::Hidden,
158 cl::desc("A flag that overrides the target's number of vector registers."));
159
160/// Maximum vectorization interleave count.
161static const unsigned MaxInterleaveFactor = 16;
162
163static cl::opt<unsigned> ForceTargetMaxScalarInterleaveFactor(
164 "force-target-max-scalar-interleave", cl::init(0), cl::Hidden,
165 cl::desc("A flag that overrides the target's max interleave factor for "
166 "scalar loops."));
167
168static cl::opt<unsigned> ForceTargetMaxVectorInterleaveFactor(
169 "force-target-max-vector-interleave", cl::init(0), cl::Hidden,
170 cl::desc("A flag that overrides the target's max interleave factor for "
171 "vectorized loops."));
172
173static cl::opt<unsigned> ForceTargetInstructionCost(
174 "force-target-instruction-cost", cl::init(0), cl::Hidden,
175 cl::desc("A flag that overrides the target's expected cost for "
176 "an instruction to a single constant value. Mostly "
177 "useful for getting consistent testing."));
178
179static cl::opt<unsigned> SmallLoopCost(
180 "small-loop-cost", cl::init(20), cl::Hidden,
181 cl::desc("The cost of a loop that is considered 'small' by the unroller."));
182
183static cl::opt<bool> LoopVectorizeWithBlockFrequency(
184 "loop-vectorize-with-block-frequency", cl::init(false), cl::Hidden,
185 cl::desc("Enable the use of the block frequency analysis to access PGO "
186 "heuristics minimizing code growth in cold regions and being more "
187 "aggressive in hot regions."));
188
189// Runtime unroll loops for load/store throughput.
190static cl::opt<bool> EnableLoadStoreRuntimeUnroll(
191 "enable-loadstore-runtime-unroll", cl::init(true), cl::Hidden,
192 cl::desc("Enable runtime unrolling until load/store ports are saturated"));
193
194/// The number of stores in a loop that are allowed to need predication.
195static cl::opt<unsigned> NumberOfStoresToPredicate(
196 "vectorize-num-stores-pred", cl::init(1), cl::Hidden,
197 cl::desc("Max number of stores to be predicated behind an if."));
198
199static cl::opt<bool> EnableIndVarRegisterHeur(
200 "enable-ind-var-reg-heur", cl::init(true), cl::Hidden,
201 cl::desc("Count the induction variable only once when unrolling"));
202
203static cl::opt<bool> EnableCondStoresVectorization(
204 "enable-cond-stores-vec", cl::init(false), cl::Hidden,
205 cl::desc("Enable if predication of stores during vectorization."));
206
207static cl::opt<unsigned> MaxNestedScalarReductionUF(
208 "max-nested-scalar-reduction-unroll", cl::init(2), cl::Hidden,
209 cl::desc("The maximum unroll factor to use when unrolling a scalar "
210 "reduction in a nested loop."));
211
212namespace {
213
214// Forward declarations.
215class LoopVectorizationLegality;
216class LoopVectorizationCostModel;
217class LoopVectorizeHints;
218
219/// Optimization analysis message produced during vectorization. Messages inform
220/// the user why vectorization did not occur.
221class Report {
222 std::string Message;
223 raw_string_ostream Out;
224 Instruction *Instr;
225
226public:
227 Report(Instruction *I = nullptr) : Out(Message), Instr(I) {
228 Out << "loop not vectorized: ";
229 }
230
231 template <typename A> Report &operator<<(const A &Value) {
232 Out << Value;
233 return *this;
234 }
235
236 Instruction *getInstr() { return Instr; }
237
238 std::string &str() { return Out.str(); }
239 operator Twine() { return Out.str(); }
240};
241
242/// InnerLoopVectorizer vectorizes loops which contain only one basic
243/// block to a specified vectorization factor (VF).
244/// This class performs the widening of scalars into vectors, or multiple
245/// scalars. This class also implements the following features:
246/// * It inserts an epilogue loop for handling loops that don't have iteration
247/// counts that are known to be a multiple of the vectorization factor.
248/// * It handles the code generation for reduction variables.
249/// * Scalarization (implementation using scalars) of un-vectorizable
250/// instructions.
251/// InnerLoopVectorizer does not perform any vectorization-legality
252/// checks, and relies on the caller to check for the different legality
253/// aspects. The InnerLoopVectorizer relies on the
254/// LoopVectorizationLegality class to provide information about the induction
255/// and reduction variables that were found to a given vectorization factor.
256class InnerLoopVectorizer {
257public:
258 InnerLoopVectorizer(Loop *OrigLoop, ScalarEvolution *SE, LoopInfo *LI,
259 DominatorTree *DT, const DataLayout *DL,
260 const TargetLibraryInfo *TLI, unsigned VecWidth,
261 unsigned UnrollFactor)
262 : OrigLoop(OrigLoop), SE(SE), LI(LI), DT(DT), DL(DL), TLI(TLI),
263 VF(VecWidth), UF(UnrollFactor), Builder(SE->getContext()),
264 Induction(nullptr), OldInduction(nullptr), WidenMap(UnrollFactor),
265 Legal(nullptr) {}
266
267 // Perform the actual loop widening (vectorization).
268 void vectorize(LoopVectorizationLegality *L) {
269 Legal = L;
270 // Create a new empty loop. Unlink the old loop and connect the new one.
271 createEmptyLoop();
272 // Widen each instruction in the old loop to a new one in the new loop.
273 // Use the Legality module to find the induction and reduction variables.
274 vectorizeLoop();
275 // Register the new loop and update the analysis passes.
276 updateAnalysis();
277 }
278
279 virtual ~InnerLoopVectorizer() {}
280
281protected:
282 /// A small list of PHINodes.
283 typedef SmallVector<PHINode*, 4> PhiVector;
284 /// When we unroll loops we have multiple vector values for each scalar.
285 /// This data structure holds the unrolled and vectorized values that
286 /// originated from one scalar instruction.
287 typedef SmallVector<Value*, 2> VectorParts;
288
289 // When we if-convert we need create edge masks. We have to cache values so
290 // that we don't end up with exponential recursion/IR.
291 typedef DenseMap<std::pair<BasicBlock*, BasicBlock*>,
292 VectorParts> EdgeMaskCache;
293
294 /// \brief Add code that checks at runtime if the accessed arrays overlap.
295 ///
296 /// Returns a pair of instructions where the first element is the first
297 /// instruction generated in possibly a sequence of instructions and the
298 /// second value is the final comparator value or NULL if no check is needed.
299 std::pair<Instruction *, Instruction *> addRuntimeCheck(Instruction *Loc);
300
301 /// \brief Add checks for strides that where assumed to be 1.
302 ///
303 /// Returns the last check instruction and the first check instruction in the
304 /// pair as (first, last).
305 std::pair<Instruction *, Instruction *> addStrideCheck(Instruction *Loc);
306
307 /// Create an empty loop, based on the loop ranges of the old loop.
308 void createEmptyLoop();
309 /// Copy and widen the instructions from the old loop.
310 virtual void vectorizeLoop();
311
312 /// \brief The Loop exit block may have single value PHI nodes where the
313 /// incoming value is 'Undef'. While vectorizing we only handled real values
314 /// that were defined inside the loop. Here we fix the 'undef case'.
315 /// See PR14725.
316 void fixLCSSAPHIs();
317
318 /// A helper function that computes the predicate of the block BB, assuming
319 /// that the header block of the loop is set to True. It returns the *entry*
320 /// mask for the block BB.
321 VectorParts createBlockInMask(BasicBlock *BB);
322 /// A helper function that computes the predicate of the edge between SRC
323 /// and DST.
324 VectorParts createEdgeMask(BasicBlock *Src, BasicBlock *Dst);
325
326 /// A helper function to vectorize a single BB within the innermost loop.
327 void vectorizeBlockInLoop(BasicBlock *BB, PhiVector *PV);
328
329 /// Vectorize a single PHINode in a block. This method handles the induction
330 /// variable canonicalization. It supports both VF = 1 for unrolled loops and
331 /// arbitrary length vectors.
332 void widenPHIInstruction(Instruction *PN, VectorParts &Entry,
333 unsigned UF, unsigned VF, PhiVector *PV);
334
335 /// Insert the new loop to the loop hierarchy and pass manager
336 /// and update the analysis passes.
337 void updateAnalysis();
338
339 /// This instruction is un-vectorizable. Implement it as a sequence
340 /// of scalars. If \p IfPredicateStore is true we need to 'hide' each
341 /// scalarized instruction behind an if block predicated on the control
342 /// dependence of the instruction.
343 virtual void scalarizeInstruction(Instruction *Instr,
344 bool IfPredicateStore=false);
345
346 /// Vectorize Load and Store instructions,
347 virtual void vectorizeMemoryInstruction(Instruction *Instr);
348
349 /// Create a broadcast instruction. This method generates a broadcast
350 /// instruction (shuffle) for loop invariant values and for the induction
351 /// value. If this is the induction variable then we extend it to N, N+1, ...
352 /// this is needed because each iteration in the loop corresponds to a SIMD
353 /// element.
354 virtual Value *getBroadcastInstrs(Value *V);
355
356 /// This function adds 0, 1, 2 ... to each vector element, starting at zero.
357 /// If Negate is set then negative numbers are added e.g. (0, -1, -2, ...).
358 /// The sequence starts at StartIndex.
359 virtual Value *getConsecutiveVector(Value* Val, int StartIdx, bool Negate);
360
361 /// When we go over instructions in the basic block we rely on previous
362 /// values within the current basic block or on loop invariant values.
363 /// When we widen (vectorize) values we place them in the map. If the values
364 /// are not within the map, they have to be loop invariant, so we simply
365 /// broadcast them into a vector.
366 VectorParts &getVectorValue(Value *V);
367
368 /// Generate a shuffle sequence that will reverse the vector Vec.
369 virtual Value *reverseVector(Value *Vec);
370
371 /// This is a helper class that holds the vectorizer state. It maps scalar
372 /// instructions to vector instructions. When the code is 'unrolled' then
373 /// then a single scalar value is mapped to multiple vector parts. The parts
374 /// are stored in the VectorPart type.
375 struct ValueMap {
376 /// C'tor. UnrollFactor controls the number of vectors ('parts') that
377 /// are mapped.
378 ValueMap(unsigned UnrollFactor) : UF(UnrollFactor) {}
379
380 /// \return True if 'Key' is saved in the Value Map.
381 bool has(Value *Key) const { return MapStorage.count(Key); }
382
383 /// Initializes a new entry in the map. Sets all of the vector parts to the
384 /// save value in 'Val'.
385 /// \return A reference to a vector with splat values.
386 VectorParts &splat(Value *Key, Value *Val) {
387 VectorParts &Entry = MapStorage[Key];
388 Entry.assign(UF, Val);
389 return Entry;
390 }
391
392 ///\return A reference to the value that is stored at 'Key'.
393 VectorParts &get(Value *Key) {
394 VectorParts &Entry = MapStorage[Key];
395 if (Entry.empty())
396 Entry.resize(UF);
397 assert(Entry.size() == UF)((Entry.size() == UF) ? static_cast<void> (0) : __assert_fail
("Entry.size() == UF", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 397, __PRETTY_FUNCTION__))
;
398 return Entry;
399 }
400
401 private:
402 /// The unroll factor. Each entry in the map stores this number of vector
403 /// elements.
404 unsigned UF;
405
406 /// Map storage. We use std::map and not DenseMap because insertions to a
407 /// dense map invalidates its iterators.
408 std::map<Value *, VectorParts> MapStorage;
409 };
410
411 /// The original loop.
412 Loop *OrigLoop;
413 /// Scev analysis to use.
414 ScalarEvolution *SE;
415 /// Loop Info.
416 LoopInfo *LI;
417 /// Dominator Tree.
418 DominatorTree *DT;
419 /// Alias Analysis.
420 AliasAnalysis *AA;
421 /// Data Layout.
422 const DataLayout *DL;
423 /// Target Library Info.
424 const TargetLibraryInfo *TLI;
425
426 /// The vectorization SIMD factor to use. Each vector will have this many
427 /// vector elements.
428 unsigned VF;
429
430protected:
431 /// The vectorization unroll factor to use. Each scalar is vectorized to this
432 /// many different vector instructions.
433 unsigned UF;
434
435 /// The builder that we use
436 IRBuilder<> Builder;
437
438 // --- Vectorization state ---
439
440 /// The vector-loop preheader.
441 BasicBlock *LoopVectorPreHeader;
442 /// The scalar-loop preheader.
443 BasicBlock *LoopScalarPreHeader;
444 /// Middle Block between the vector and the scalar.
445 BasicBlock *LoopMiddleBlock;
446 ///The ExitBlock of the scalar loop.
447 BasicBlock *LoopExitBlock;
448 ///The vector loop body.
449 SmallVector<BasicBlock *, 4> LoopVectorBody;
450 ///The scalar loop body.
451 BasicBlock *LoopScalarBody;
452 /// A list of all bypass blocks. The first block is the entry of the loop.
453 SmallVector<BasicBlock *, 4> LoopBypassBlocks;
454
455 /// The new Induction variable which was added to the new block.
456 PHINode *Induction;
457 /// The induction variable of the old basic block.
458 PHINode *OldInduction;
459 /// Holds the extended (to the widest induction type) start index.
460 Value *ExtendedIdx;
461 /// Maps scalars to widened vectors.
462 ValueMap WidenMap;
463 EdgeMaskCache MaskCache;
464
465 LoopVectorizationLegality *Legal;
466};
467
468class InnerLoopUnroller : public InnerLoopVectorizer {
469public:
470 InnerLoopUnroller(Loop *OrigLoop, ScalarEvolution *SE, LoopInfo *LI,
471 DominatorTree *DT, const DataLayout *DL,
472 const TargetLibraryInfo *TLI, unsigned UnrollFactor) :
473 InnerLoopVectorizer(OrigLoop, SE, LI, DT, DL, TLI, 1, UnrollFactor) { }
474
475private:
476 void scalarizeInstruction(Instruction *Instr,
477 bool IfPredicateStore = false) override;
478 void vectorizeMemoryInstruction(Instruction *Instr) override;
479 Value *getBroadcastInstrs(Value *V) override;
480 Value *getConsecutiveVector(Value* Val, int StartIdx, bool Negate) override;
481 Value *reverseVector(Value *Vec) override;
482};
483
484/// \brief Look for a meaningful debug location on the instruction or it's
485/// operands.
486static Instruction *getDebugLocFromInstOrOperands(Instruction *I) {
487 if (!I)
488 return I;
489
490 DebugLoc Empty;
491 if (I->getDebugLoc() != Empty)
492 return I;
493
494 for (User::op_iterator OI = I->op_begin(), OE = I->op_end(); OI != OE; ++OI) {
495 if (Instruction *OpInst = dyn_cast<Instruction>(*OI))
496 if (OpInst->getDebugLoc() != Empty)
497 return OpInst;
498 }
499
500 return I;
501}
502
503/// \brief Set the debug location in the builder using the debug location in the
504/// instruction.
505static void setDebugLocFromInst(IRBuilder<> &B, const Value *Ptr) {
506 if (const Instruction *Inst = dyn_cast_or_null<Instruction>(Ptr))
507 B.SetCurrentDebugLocation(Inst->getDebugLoc());
508 else
509 B.SetCurrentDebugLocation(DebugLoc());
510}
511
512#ifndef NDEBUG
513/// \return string containing a file name and a line # for the given loop.
514static std::string getDebugLocString(const Loop *L) {
515 std::string Result;
516 if (L) {
517 raw_string_ostream OS(Result);
518 const DebugLoc LoopDbgLoc = L->getStartLoc();
519 if (!LoopDbgLoc.isUnknown())
520 LoopDbgLoc.print(L->getHeader()->getContext(), OS);
521 else
522 // Just print the module name.
523 OS << L->getHeader()->getParent()->getParent()->getModuleIdentifier();
524 OS.flush();
525 }
526 return Result;
527}
528#endif
529
530/// \brief Propagate known metadata from one instruction to another.
531static void propagateMetadata(Instruction *To, const Instruction *From) {
532 SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata;
533 From->getAllMetadataOtherThanDebugLoc(Metadata);
534
535 for (auto M : Metadata) {
536 unsigned Kind = M.first;
537
538 // These are safe to transfer (this is safe for TBAA, even when we
539 // if-convert, because should that metadata have had a control dependency
540 // on the condition, and thus actually aliased with some other
541 // non-speculated memory access when the condition was false, this would be
542 // caught by the runtime overlap checks).
543 if (Kind != LLVMContext::MD_tbaa &&
544 Kind != LLVMContext::MD_alias_scope &&
545 Kind != LLVMContext::MD_noalias &&
546 Kind != LLVMContext::MD_fpmath)
547 continue;
548
549 To->setMetadata(Kind, M.second);
550 }
551}
552
553/// \brief Propagate known metadata from one instruction to a vector of others.
554static void propagateMetadata(SmallVectorImpl<Value *> &To, const Instruction *From) {
555 for (Value *V : To)
556 if (Instruction *I = dyn_cast<Instruction>(V))
557 propagateMetadata(I, From);
558}
559
560/// LoopVectorizationLegality checks if it is legal to vectorize a loop, and
561/// to what vectorization factor.
562/// This class does not look at the profitability of vectorization, only the
563/// legality. This class has two main kinds of checks:
564/// * Memory checks - The code in canVectorizeMemory checks if vectorization
565/// will change the order of memory accesses in a way that will change the
566/// correctness of the program.
567/// * Scalars checks - The code in canVectorizeInstrs and canVectorizeMemory
568/// checks for a number of different conditions, such as the availability of a
569/// single induction variable, that all types are supported and vectorize-able,
570/// etc. This code reflects the capabilities of InnerLoopVectorizer.
571/// This class is also used by InnerLoopVectorizer for identifying
572/// induction variable and the different reduction variables.
573class LoopVectorizationLegality {
574public:
575 unsigned NumLoads;
576 unsigned NumStores;
577 unsigned NumPredStores;
578
579 LoopVectorizationLegality(Loop *L, ScalarEvolution *SE, const DataLayout *DL,
580 DominatorTree *DT, TargetLibraryInfo *TLI,
581 AliasAnalysis *AA, Function *F)
582 : NumLoads(0), NumStores(0), NumPredStores(0), TheLoop(L), SE(SE), DL(DL),
583 DT(DT), TLI(TLI), AA(AA), TheFunction(F), Induction(nullptr),
584 WidestIndTy(nullptr), HasFunNoNaNAttr(false), MaxSafeDepDistBytes(-1U) {
585 }
586
587 /// This enum represents the kinds of reductions that we support.
588 enum ReductionKind {
589 RK_NoReduction, ///< Not a reduction.
590 RK_IntegerAdd, ///< Sum of integers.
591 RK_IntegerMult, ///< Product of integers.
592 RK_IntegerOr, ///< Bitwise or logical OR of numbers.
593 RK_IntegerAnd, ///< Bitwise or logical AND of numbers.
594 RK_IntegerXor, ///< Bitwise or logical XOR of numbers.
595 RK_IntegerMinMax, ///< Min/max implemented in terms of select(cmp()).
596 RK_FloatAdd, ///< Sum of floats.
597 RK_FloatMult, ///< Product of floats.
598 RK_FloatMinMax ///< Min/max implemented in terms of select(cmp()).
599 };
600
601 /// This enum represents the kinds of inductions that we support.
602 enum InductionKind {
603 IK_NoInduction, ///< Not an induction variable.
604 IK_IntInduction, ///< Integer induction variable. Step = 1.
605 IK_ReverseIntInduction, ///< Reverse int induction variable. Step = -1.
606 IK_PtrInduction, ///< Pointer induction var. Step = sizeof(elem).
607 IK_ReversePtrInduction ///< Reverse ptr indvar. Step = - sizeof(elem).
608 };
609
610 // This enum represents the kind of minmax reduction.
611 enum MinMaxReductionKind {
612 MRK_Invalid,
613 MRK_UIntMin,
614 MRK_UIntMax,
615 MRK_SIntMin,
616 MRK_SIntMax,
617 MRK_FloatMin,
618 MRK_FloatMax
619 };
620
621 /// This struct holds information about reduction variables.
622 struct ReductionDescriptor {
623 ReductionDescriptor() : StartValue(nullptr), LoopExitInstr(nullptr),
624 Kind(RK_NoReduction), MinMaxKind(MRK_Invalid) {}
625
626 ReductionDescriptor(Value *Start, Instruction *Exit, ReductionKind K,
627 MinMaxReductionKind MK)
628 : StartValue(Start), LoopExitInstr(Exit), Kind(K), MinMaxKind(MK) {}
629
630 // The starting value of the reduction.
631 // It does not have to be zero!
632 TrackingVH<Value> StartValue;
633 // The instruction who's value is used outside the loop.
634 Instruction *LoopExitInstr;
635 // The kind of the reduction.
636 ReductionKind Kind;
637 // If this a min/max reduction the kind of reduction.
638 MinMaxReductionKind MinMaxKind;
639 };
640
641 /// This POD struct holds information about a potential reduction operation.
642 struct ReductionInstDesc {
643 ReductionInstDesc(bool IsRedux, Instruction *I) :
644 IsReduction(IsRedux), PatternLastInst(I), MinMaxKind(MRK_Invalid) {}
645
646 ReductionInstDesc(Instruction *I, MinMaxReductionKind K) :
647 IsReduction(true), PatternLastInst(I), MinMaxKind(K) {}
648
649 // Is this instruction a reduction candidate.
650 bool IsReduction;
651 // The last instruction in a min/max pattern (select of the select(icmp())
652 // pattern), or the current reduction instruction otherwise.
653 Instruction *PatternLastInst;
654 // If this is a min/max pattern the comparison predicate.
655 MinMaxReductionKind MinMaxKind;
656 };
657
658 /// This struct holds information about the memory runtime legality
659 /// check that a group of pointers do not overlap.
660 struct RuntimePointerCheck {
661 RuntimePointerCheck() : Need(false) {}
662
663 /// Reset the state of the pointer runtime information.
664 void reset() {
665 Need = false;
666 Pointers.clear();
667 Starts.clear();
668 Ends.clear();
669 IsWritePtr.clear();
670 DependencySetId.clear();
671 AliasSetId.clear();
672 }
673
674 /// Insert a pointer and calculate the start and end SCEVs.
675 void insert(ScalarEvolution *SE, Loop *Lp, Value *Ptr, bool WritePtr,
676 unsigned DepSetId, unsigned ASId, ValueToValueMap &Strides);
677
678 /// This flag indicates if we need to add the runtime check.
679 bool Need;
680 /// Holds the pointers that we need to check.
681 SmallVector<TrackingVH<Value>, 2> Pointers;
682 /// Holds the pointer value at the beginning of the loop.
683 SmallVector<const SCEV*, 2> Starts;
684 /// Holds the pointer value at the end of the loop.
685 SmallVector<const SCEV*, 2> Ends;
686 /// Holds the information if this pointer is used for writing to memory.
687 SmallVector<bool, 2> IsWritePtr;
688 /// Holds the id of the set of pointers that could be dependent because of a
689 /// shared underlying object.
690 SmallVector<unsigned, 2> DependencySetId;
691 /// Holds the id of the disjoint alias set to which this pointer belongs.
692 SmallVector<unsigned, 2> AliasSetId;
693 };
694
695 /// A struct for saving information about induction variables.
696 struct InductionInfo {
697 InductionInfo(Value *Start, InductionKind K) : StartValue(Start), IK(K) {}
698 InductionInfo() : StartValue(nullptr), IK(IK_NoInduction) {}
699 /// Start value.
700 TrackingVH<Value> StartValue;
701 /// Induction kind.
702 InductionKind IK;
703 };
704
705 /// ReductionList contains the reduction descriptors for all
706 /// of the reductions that were found in the loop.
707 typedef DenseMap<PHINode*, ReductionDescriptor> ReductionList;
708
709 /// InductionList saves induction variables and maps them to the
710 /// induction descriptor.
711 typedef MapVector<PHINode*, InductionInfo> InductionList;
712
713 /// Returns true if it is legal to vectorize this loop.
714 /// This does not mean that it is profitable to vectorize this
715 /// loop, only that it is legal to do so.
716 bool canVectorize();
717
718 /// Returns the Induction variable.
719 PHINode *getInduction() { return Induction; }
720
721 /// Returns the reduction variables found in the loop.
722 ReductionList *getReductionVars() { return &Reductions; }
723
724 /// Returns the induction variables found in the loop.
725 InductionList *getInductionVars() { return &Inductions; }
726
727 /// Returns the widest induction type.
728 Type *getWidestInductionType() { return WidestIndTy; }
729
730 /// Returns True if V is an induction variable in this loop.
731 bool isInductionVariable(const Value *V);
732
733 /// Return true if the block BB needs to be predicated in order for the loop
734 /// to be vectorized.
735 bool blockNeedsPredication(BasicBlock *BB);
736
737 /// Check if this pointer is consecutive when vectorizing. This happens
738 /// when the last index of the GEP is the induction variable, or that the
739 /// pointer itself is an induction variable.
740 /// This check allows us to vectorize A[idx] into a wide load/store.
741 /// Returns:
742 /// 0 - Stride is unknown or non-consecutive.
743 /// 1 - Address is consecutive.
744 /// -1 - Address is consecutive, and decreasing.
745 int isConsecutivePtr(Value *Ptr);
746
747 /// Returns true if the value V is uniform within the loop.
748 bool isUniform(Value *V);
749
750 /// Returns true if this instruction will remain scalar after vectorization.
751 bool isUniformAfterVectorization(Instruction* I) { return Uniforms.count(I); }
752
753 /// Returns the information that we collected about runtime memory check.
754 RuntimePointerCheck *getRuntimePointerCheck() { return &PtrRtCheck; }
755
756 /// This function returns the identity element (or neutral element) for
757 /// the operation K.
758 static Constant *getReductionIdentity(ReductionKind K, Type *Tp);
759
760 unsigned getMaxSafeDepDistBytes() { return MaxSafeDepDistBytes; }
761
762 bool hasStride(Value *V) { return StrideSet.count(V); }
763 bool mustCheckStrides() { return !StrideSet.empty(); }
764 SmallPtrSet<Value *, 8>::iterator strides_begin() {
765 return StrideSet.begin();
766 }
767 SmallPtrSet<Value *, 8>::iterator strides_end() { return StrideSet.end(); }
768
769private:
770 /// Check if a single basic block loop is vectorizable.
771 /// At this point we know that this is a loop with a constant trip count
772 /// and we only need to check individual instructions.
773 bool canVectorizeInstrs();
774
775 /// When we vectorize loops we may change the order in which
776 /// we read and write from memory. This method checks if it is
777 /// legal to vectorize the code, considering only memory constrains.
778 /// Returns true if the loop is vectorizable
779 bool canVectorizeMemory();
780
781 /// Return true if we can vectorize this loop using the IF-conversion
782 /// transformation.
783 bool canVectorizeWithIfConvert();
784
785 /// Collect the variables that need to stay uniform after vectorization.
786 void collectLoopUniforms();
787
788 /// Return true if all of the instructions in the block can be speculatively
789 /// executed. \p SafePtrs is a list of addresses that are known to be legal
790 /// and we know that we can read from them without segfault.
791 bool blockCanBePredicated(BasicBlock *BB, SmallPtrSetImpl<Value *> &SafePtrs);
792
793 /// Returns True, if 'Phi' is the kind of reduction variable for type
794 /// 'Kind'. If this is a reduction variable, it adds it to ReductionList.
795 bool AddReductionVar(PHINode *Phi, ReductionKind Kind);
796 /// Returns a struct describing if the instruction 'I' can be a reduction
797 /// variable of type 'Kind'. If the reduction is a min/max pattern of
798 /// select(icmp()) this function advances the instruction pointer 'I' from the
799 /// compare instruction to the select instruction and stores this pointer in
800 /// 'PatternLastInst' member of the returned struct.
801 ReductionInstDesc isReductionInstr(Instruction *I, ReductionKind Kind,
802 ReductionInstDesc &Desc);
803 /// Returns true if the instruction is a Select(ICmp(X, Y), X, Y) instruction
804 /// pattern corresponding to a min(X, Y) or max(X, Y).
805 static ReductionInstDesc isMinMaxSelectCmpPattern(Instruction *I,
806 ReductionInstDesc &Prev);
807 /// Returns the induction kind of Phi. This function may return NoInduction
808 /// if the PHI is not an induction variable.
809 InductionKind isInductionVariable(PHINode *Phi);
810
811 /// \brief Collect memory access with loop invariant strides.
812 ///
813 /// Looks for accesses like "a[i * StrideA]" where "StrideA" is loop
814 /// invariant.
815 void collectStridedAcccess(Value *LoadOrStoreInst);
816
817 /// Report an analysis message to assist the user in diagnosing loops that are
818 /// not vectorized.
819 void emitAnalysis(Report &Message) {
820 DebugLoc DL = TheLoop->getStartLoc();
821 if (Instruction *I = Message.getInstr())
822 DL = I->getDebugLoc();
823 emitOptimizationRemarkAnalysis(TheFunction->getContext(), DEBUG_TYPE"loop-vectorize",
824 *TheFunction, DL, Message.str());
825 }
826
827 /// The loop that we evaluate.
828 Loop *TheLoop;
829 /// Scev analysis.
830 ScalarEvolution *SE;
831 /// DataLayout analysis.
832 const DataLayout *DL;
833 /// Dominators.
834 DominatorTree *DT;
835 /// Target Library Info.
836 TargetLibraryInfo *TLI;
837 /// Alias analysis.
838 AliasAnalysis *AA;
839 /// Parent function
840 Function *TheFunction;
841
842 // --- vectorization state --- //
843
844 /// Holds the integer induction variable. This is the counter of the
845 /// loop.
846 PHINode *Induction;
847 /// Holds the reduction variables.
848 ReductionList Reductions;
849 /// Holds all of the induction variables that we found in the loop.
850 /// Notice that inductions don't need to start at zero and that induction
851 /// variables can be pointers.
852 InductionList Inductions;
853 /// Holds the widest induction type encountered.
854 Type *WidestIndTy;
855
856 /// Allowed outside users. This holds the reduction
857 /// vars which can be accessed from outside the loop.
858 SmallPtrSet<Value*, 4> AllowedExit;
859 /// This set holds the variables which are known to be uniform after
860 /// vectorization.
861 SmallPtrSet<Instruction*, 4> Uniforms;
862 /// We need to check that all of the pointers in this list are disjoint
863 /// at runtime.
864 RuntimePointerCheck PtrRtCheck;
865 /// Can we assume the absence of NaNs.
866 bool HasFunNoNaNAttr;
867
868 unsigned MaxSafeDepDistBytes;
869
870 ValueToValueMap Strides;
871 SmallPtrSet<Value *, 8> StrideSet;
872};
873
874/// LoopVectorizationCostModel - estimates the expected speedups due to
875/// vectorization.
876/// In many cases vectorization is not profitable. This can happen because of
877/// a number of reasons. In this class we mainly attempt to predict the
878/// expected speedup/slowdowns due to the supported instruction set. We use the
879/// TargetTransformInfo to query the different backends for the cost of
880/// different operations.
881class LoopVectorizationCostModel {
882public:
883 LoopVectorizationCostModel(Loop *L, ScalarEvolution *SE, LoopInfo *LI,
884 LoopVectorizationLegality *Legal,
885 const TargetTransformInfo &TTI,
886 const DataLayout *DL, const TargetLibraryInfo *TLI,
887 const Function *F, const LoopVectorizeHints *Hints)
888 : TheLoop(L), SE(SE), LI(LI), Legal(Legal), TTI(TTI), DL(DL), TLI(TLI), TheFunction(F), Hints(Hints) {}
889
890 /// Information about vectorization costs
891 struct VectorizationFactor {
892 unsigned Width; // Vector width with best cost
893 unsigned Cost; // Cost of the loop with that width
894 };
895 /// \return The most profitable vectorization factor and the cost of that VF.
896 /// This method checks every power of two up to VF. If UserVF is not ZERO
897 /// then this vectorization factor will be selected if vectorization is
898 /// possible.
899 VectorizationFactor selectVectorizationFactor(bool OptForSize);
900
901 /// \return The size (in bits) of the widest type in the code that
902 /// needs to be vectorized. We ignore values that remain scalar such as
903 /// 64 bit loop indices.
904 unsigned getWidestType();
905
906 /// \return The most profitable unroll factor.
907 /// If UserUF is non-zero then this method finds the best unroll-factor
908 /// based on register pressure and other parameters.
909 /// VF and LoopCost are the selected vectorization factor and the cost of the
910 /// selected VF.
911 unsigned selectUnrollFactor(bool OptForSize, unsigned VF, unsigned LoopCost);
912
913 /// \brief A struct that represents some properties of the register usage
914 /// of a loop.
915 struct RegisterUsage {
916 /// Holds the number of loop invariant values that are used in the loop.
917 unsigned LoopInvariantRegs;
918 /// Holds the maximum number of concurrent live intervals in the loop.
919 unsigned MaxLocalUsers;
920 /// Holds the number of instructions in the loop.
921 unsigned NumInstructions;
922 };
923
924 /// \return information about the register usage of the loop.
925 RegisterUsage calculateRegisterUsage();
926
927private:
928 /// Returns the expected execution cost. The unit of the cost does
929 /// not matter because we use the 'cost' units to compare different
930 /// vector widths. The cost that is returned is *not* normalized by
931 /// the factor width.
932 unsigned expectedCost(unsigned VF);
933
934 /// Returns the execution time cost of an instruction for a given vector
935 /// width. Vector width of one means scalar.
936 unsigned getInstructionCost(Instruction *I, unsigned VF);
937
938 /// A helper function for converting Scalar types to vector types.
939 /// If the incoming type is void, we return void. If the VF is 1, we return
940 /// the scalar type.
941 static Type* ToVectorTy(Type *Scalar, unsigned VF);
942
943 /// Returns whether the instruction is a load or store and will be a emitted
944 /// as a vector operation.
945 bool isConsecutiveLoadOrStore(Instruction *I);
946
947 /// Report an analysis message to assist the user in diagnosing loops that are
948 /// not vectorized.
949 void emitAnalysis(Report &Message) {
950 DebugLoc DL = TheLoop->getStartLoc();
951 if (Instruction *I = Message.getInstr())
952 DL = I->getDebugLoc();
953 emitOptimizationRemarkAnalysis(TheFunction->getContext(), DEBUG_TYPE"loop-vectorize",
954 *TheFunction, DL, Message.str());
955 }
956
957 /// The loop that we evaluate.
958 Loop *TheLoop;
959 /// Scev analysis.
960 ScalarEvolution *SE;
961 /// Loop Info analysis.
962 LoopInfo *LI;
963 /// Vectorization legality.
964 LoopVectorizationLegality *Legal;
965 /// Vector target information.
966 const TargetTransformInfo &TTI;
967 /// Target data layout information.
968 const DataLayout *DL;
969 /// Target Library Info.
970 const TargetLibraryInfo *TLI;
971 const Function *TheFunction;
972 // Loop Vectorize Hint.
973 const LoopVectorizeHints *Hints;
974};
975
976/// Utility class for getting and setting loop vectorizer hints in the form
977/// of loop metadata.
978/// This class keeps a number of loop annotations locally (as member variables)
979/// and can, upon request, write them back as metadata on the loop. It will
980/// initially scan the loop for existing metadata, and will update the local
981/// values based on information in the loop.
982/// We cannot write all values to metadata, as the mere presence of some info,
983/// for example 'force', means a decision has been made. So, we need to be
984/// careful NOT to add them if the user hasn't specifically asked so.
985class LoopVectorizeHints {
986 enum HintKind {
987 HK_WIDTH,
988 HK_UNROLL,
989 HK_FORCE
990 };
991
992 /// Hint - associates name and validation with the hint value.
993 struct Hint {
994 const char * Name;
995 unsigned Value; // This may have to change for non-numeric values.
996 HintKind Kind;
997
998 Hint(const char * Name, unsigned Value, HintKind Kind)
999 : Name(Name), Value(Value), Kind(Kind) { }
1000
1001 bool validate(unsigned Val) {
1002 switch (Kind) {
1003 case HK_WIDTH:
1004 return isPowerOf2_32(Val) && Val <= MaxVectorWidth;
1005 case HK_UNROLL:
1006 return isPowerOf2_32(Val) && Val <= MaxInterleaveFactor;
1007 case HK_FORCE:
1008 return (Val <= 1);
1009 }
1010 return false;
1011 }
1012 };
1013
1014 /// Vectorization width.
1015 Hint Width;
1016 /// Vectorization interleave factor.
1017 Hint Interleave;
1018 /// Vectorization forced
1019 Hint Force;
1020 /// Array to help iterating through all hints.
1021 Hint *Hints[3]; // avoiding initialisation due to MSVC2012
1022
1023 /// Return the loop metadata prefix.
1024 static StringRef Prefix() { return "llvm.loop."; }
1025
1026public:
1027 enum ForceKind {
1028 FK_Undefined = -1, ///< Not selected.
1029 FK_Disabled = 0, ///< Forcing disabled.
1030 FK_Enabled = 1, ///< Forcing enabled.
1031 };
1032
1033 LoopVectorizeHints(const Loop *L, bool DisableInterleaving)
1034 : Width("vectorize.width", VectorizationFactor, HK_WIDTH),
1035 Interleave("interleave.count", DisableInterleaving, HK_UNROLL),
1036 Force("vectorize.enable", FK_Undefined, HK_FORCE),
1037 TheLoop(L) {
1038 // FIXME: Move this up initialisation when MSVC requirement is 2013+
1039 Hints[0] = &Width;
1040 Hints[1] = &Interleave;
1041 Hints[2] = &Force;
1042
1043 // Populate values with existing loop metadata.
1044 getHintsFromMetadata();
1045
1046 // force-vector-interleave overrides DisableInterleaving.
1047 if (VectorizationInterleave.getNumOccurrences() > 0)
1048 Interleave.Value = VectorizationInterleave;
1049
1050 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 (0)
1051 << "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 (0)
;
1052 }
1053
1054 /// Mark the loop L as already vectorized by setting the width to 1.
1055 void setAlreadyVectorized() {
1056 Width.Value = Interleave.Value = 1;
1057 // FIXME: Change all lines below for this when we can use MSVC 2013+
1058 //writeHintsToMetadata({ Width, Unroll });
1059 std::vector<Hint> hints;
1060 hints.reserve(2);
1061 hints.emplace_back(Width);
1062 hints.emplace_back(Interleave);
1063 writeHintsToMetadata(std::move(hints));
1064 }
1065
1066 /// Dumps all the hint information.
1067 std::string emitRemark() const {
1068 Report R;
1069 if (Force.Value == LoopVectorizeHints::FK_Disabled)
1070 R << "vectorization is explicitly disabled";
1071 else {
1072 R << "use -Rpass-analysis=loop-vectorize for more info";
1073 if (Force.Value == LoopVectorizeHints::FK_Enabled) {
1074 R << " (Force=true";
1075 if (Width.Value != 0)
1076 R << ", Vector Width=" << Width.Value;
1077 if (Interleave.Value != 0)
1078 R << ", Interleave Count=" << Interleave.Value;
1079 R << ")";
1080 }
1081 }
1082
1083 return R.str();
1084 }
1085
1086 unsigned getWidth() const { return Width.Value; }
1087 unsigned getInterleave() const { return Interleave.Value; }
1088 enum ForceKind getForce() const { return (ForceKind)Force.Value; }
1089
1090private:
1091 /// Find hints specified in the loop metadata and update local values.
1092 void getHintsFromMetadata() {
1093 MDNode *LoopID = TheLoop->getLoopID();
1094 if (!LoopID)
1095 return;
1096
1097 // First operand should refer to the loop id itself.
1098 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1098, __PRETTY_FUNCTION__))
;
1099 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1099, __PRETTY_FUNCTION__))
;
1100
1101 for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
1102 const MDString *S = nullptr;
1103 SmallVector<Value*, 4> Args;
1104
1105 // The expected hint is either a MDString or a MDNode with the first
1106 // operand a MDString.
1107 if (const MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i))) {
1108 if (!MD || MD->getNumOperands() == 0)
1109 continue;
1110 S = dyn_cast<MDString>(MD->getOperand(0));
1111 for (unsigned i = 1, ie = MD->getNumOperands(); i < ie; ++i)
1112 Args.push_back(MD->getOperand(i));
1113 } else {
1114 S = dyn_cast<MDString>(LoopID->getOperand(i));
1115 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1115, __PRETTY_FUNCTION__))
;
1116 }
1117
1118 if (!S)
1119 continue;
1120
1121 // Check if the hint starts with the loop metadata prefix.
1122 StringRef Name = S->getString();
1123 if (Args.size() == 1)
1124 setHint(Name, Args[0]);
1125 }
1126 }
1127
1128 /// Checks string hint with one operand and set value if valid.
1129 void setHint(StringRef Name, Value *Arg) {
1130 if (!Name.startswith(Prefix()))
1131 return;
1132 Name = Name.substr(Prefix().size(), StringRef::npos);
1133
1134 const ConstantInt *C = dyn_cast<ConstantInt>(Arg);
1135 if (!C) return;
1136 unsigned Val = C->getZExtValue();
1137
1138 for (auto H : Hints) {
1139 if (Name == H->Name) {
1140 if (H->validate(Val))
1141 H->Value = Val;
1142 else
1143 DEBUG(dbgs() << "LV: ignoring invalid hint '" << Name << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: ignoring invalid hint '"
<< Name << "'\n"; } } while (0)
;
1144 break;
1145 }
1146 }
1147 }
1148
1149 /// Create a new hint from name / value pair.
1150 MDNode *createHintMetadata(StringRef Name, unsigned V) const {
1151 LLVMContext &Context = TheLoop->getHeader()->getContext();
1152 SmallVector<Value*, 2> Vals;
1153 Vals.push_back(MDString::get(Context, Name));
1154 Vals.push_back(ConstantInt::get(Type::getInt32Ty(Context), V));
1155 return MDNode::get(Context, Vals);
1156 }
1157
1158 /// Matches metadata with hint name.
1159 bool matchesHintMetadataName(MDNode *Node, std::vector<Hint> &HintTypes) {
1160 MDString* Name = dyn_cast<MDString>(Node->getOperand(0));
1161 if (!Name)
1162 return false;
1163
1164 for (auto H : HintTypes)
1165 if (Name->getName().endswith(H.Name))
1166 return true;
1167 return false;
1168 }
1169
1170 /// Sets current hints into loop metadata, keeping other values intact.
1171 void writeHintsToMetadata(std::vector<Hint> HintTypes) {
1172 if (HintTypes.size() == 0)
1173 return;
1174
1175 // Reserve the first element to LoopID (see below).
1176 SmallVector<Value*, 4> Vals(1);
1177 // If the loop already has metadata, then ignore the existing operands.
1178 MDNode *LoopID = TheLoop->getLoopID();
1179 if (LoopID) {
1180 for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
1181 MDNode *Node = cast<MDNode>(LoopID->getOperand(i));
1182 // If node in update list, ignore old value.
1183 if (!matchesHintMetadataName(Node, HintTypes))
1184 Vals.push_back(Node);
1185 }
1186 }
1187
1188 // Now, add the missing hints.
1189 for (auto H : HintTypes)
1190 Vals.push_back(
1191 createHintMetadata(Twine(Prefix(), H.Name).str(), H.Value));
1192
1193 // Replace current metadata node with new one.
1194 LLVMContext &Context = TheLoop->getHeader()->getContext();
1195 MDNode *NewLoopID = MDNode::get(Context, Vals);
1196 // Set operand 0 to refer to the loop id itself.
1197 NewLoopID->replaceOperandWith(0, NewLoopID);
1198
1199 TheLoop->setLoopID(NewLoopID);
1200 if (LoopID)
1201 LoopID->replaceAllUsesWith(NewLoopID);
1202 LoopID = NewLoopID;
1203 }
1204
1205 /// The loop these hints belong to.
1206 const Loop *TheLoop;
1207};
1208
1209static void emitMissedWarning(Function *F, Loop *L,
1210 const LoopVectorizeHints &LH) {
1211 emitOptimizationRemarkMissed(F->getContext(), DEBUG_TYPE"loop-vectorize", *F,
1212 L->getStartLoc(), LH.emitRemark());
1213
1214 if (LH.getForce() == LoopVectorizeHints::FK_Enabled) {
1215 if (LH.getWidth() != 1)
1216 emitLoopVectorizeWarning(
1217 F->getContext(), *F, L->getStartLoc(),
1218 "failed explicitly specified loop vectorization");
1219 else if (LH.getInterleave() != 1)
1220 emitLoopInterleaveWarning(
1221 F->getContext(), *F, L->getStartLoc(),
1222 "failed explicitly specified loop interleaving");
1223 }
1224}
1225
1226static void addInnerLoop(Loop &L, SmallVectorImpl<Loop *> &V) {
1227 if (L.empty())
1228 return V.push_back(&L);
1229
1230 for (Loop *InnerL : L)
1231 addInnerLoop(*InnerL, V);
1232}
1233
1234/// The LoopVectorize Pass.
1235struct LoopVectorize : public FunctionPass {
1236 /// Pass identification, replacement for typeid
1237 static char ID;
1238
1239 explicit LoopVectorize(bool NoUnrolling = false, bool AlwaysVectorize = true)
1240 : FunctionPass(ID),
1241 DisableUnrolling(NoUnrolling),
1242 AlwaysVectorize(AlwaysVectorize) {
1243 initializeLoopVectorizePass(*PassRegistry::getPassRegistry());
1244 }
1245
1246 ScalarEvolution *SE;
1247 const DataLayout *DL;
1248 LoopInfo *LI;
1249 TargetTransformInfo *TTI;
1250 DominatorTree *DT;
1251 BlockFrequencyInfo *BFI;
1252 TargetLibraryInfo *TLI;
1253 AliasAnalysis *AA;
1254 bool DisableUnrolling;
1255 bool AlwaysVectorize;
1256
1257 BlockFrequency ColdEntryFreq;
1258
1259 bool runOnFunction(Function &F) override {
1260 SE = &getAnalysis<ScalarEvolution>();
1261 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1262 DL = DLP ? &DLP->getDataLayout() : nullptr;
1263 LI = &getAnalysis<LoopInfo>();
1264 TTI = &getAnalysis<TargetTransformInfo>();
1265 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1266 BFI = &getAnalysis<BlockFrequencyInfo>();
1267 TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
1268 AA = &getAnalysis<AliasAnalysis>();
1269
1270 // Compute some weights outside of the loop over the loops. Compute this
1271 // using a BranchProbability to re-use its scaling math.
1272 const BranchProbability ColdProb(1, 5); // 20%
1273 ColdEntryFreq = BlockFrequency(BFI->getEntryFreq()) * ColdProb;
1274
1275 // If the target claims to have no vector registers don't attempt
1276 // vectorization.
1277 if (!TTI->getNumberOfRegisters(true))
1278 return false;
1279
1280 if (!DL) {
1281 DEBUG(dbgs() << "\nLV: Not vectorizing " << F.getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "\nLV: Not vectorizing "
<< F.getName() << ": Missing data layout\n"; } }
while (0)
1282 << ": Missing data layout\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "\nLV: Not vectorizing "
<< F.getName() << ": Missing data layout\n"; } }
while (0)
;
1283 return false;
1284 }
1285
1286 // Build up a worklist of inner-loops to vectorize. This is necessary as
1287 // the act of vectorizing or partially unrolling a loop creates new loops
1288 // and can invalidate iterators across the loops.
1289 SmallVector<Loop *, 8> Worklist;
1290
1291 for (Loop *L : *LI)
1292 addInnerLoop(*L, Worklist);
1293
1294 LoopsAnalyzed += Worklist.size();
1295
1296 // Now walk the identified inner loops.
1297 bool Changed = false;
1298 while (!Worklist.empty())
1299 Changed |= processLoop(Worklist.pop_back_val());
1300
1301 // Process each loop nest in the function.
1302 return Changed;
1303 }
1304
1305 bool processLoop(Loop *L) {
1306 assert(L->empty() && "Only process inner loops.")((L->empty() && "Only process inner loops.") ? static_cast
<void> (0) : __assert_fail ("L->empty() && \"Only process inner loops.\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1306, __PRETTY_FUNCTION__))
;
1307
1308#ifndef NDEBUG
1309 const std::string DebugLocStr = getDebugLocString(L);
1310#endif /* NDEBUG */
1311
1312 DEBUG(dbgs() << "\nLV: Checking a loop in \""do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "\nLV: Checking a loop in \""
<< L->getHeader()->getParent()->getName() <<
"\" from " << DebugLocStr << "\n"; } } while (0)
1313 << L->getHeader()->getParent()->getName() << "\" from "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "\nLV: Checking a loop in \""
<< L->getHeader()->getParent()->getName() <<
"\" from " << DebugLocStr << "\n"; } } while (0)
1314 << DebugLocStr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "\nLV: Checking a loop in \""
<< L->getHeader()->getParent()->getName() <<
"\" from " << DebugLocStr << "\n"; } } while (0)
;
1315
1316 LoopVectorizeHints Hints(L, DisableUnrolling);
1317
1318 DEBUG(dbgs() << "LV: Loop hints:"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop hints:" <<
" force=" << (Hints.getForce() == LoopVectorizeHints::
FK_Disabled ? "disabled" : (Hints.getForce() == LoopVectorizeHints
::FK_Enabled ? "enabled" : "?")) << " width=" << Hints
.getWidth() << " unroll=" << Hints.getInterleave(
) << "\n"; } } while (0)
1319 << " force="do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop hints:" <<
" force=" << (Hints.getForce() == LoopVectorizeHints::
FK_Disabled ? "disabled" : (Hints.getForce() == LoopVectorizeHints
::FK_Enabled ? "enabled" : "?")) << " width=" << Hints
.getWidth() << " unroll=" << Hints.getInterleave(
) << "\n"; } } while (0)
1320 << (Hints.getForce() == LoopVectorizeHints::FK_Disableddo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop hints:" <<
" force=" << (Hints.getForce() == LoopVectorizeHints::
FK_Disabled ? "disabled" : (Hints.getForce() == LoopVectorizeHints
::FK_Enabled ? "enabled" : "?")) << " width=" << Hints
.getWidth() << " unroll=" << Hints.getInterleave(
) << "\n"; } } while (0)
1321 ? "disabled"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop hints:" <<
" force=" << (Hints.getForce() == LoopVectorizeHints::
FK_Disabled ? "disabled" : (Hints.getForce() == LoopVectorizeHints
::FK_Enabled ? "enabled" : "?")) << " width=" << Hints
.getWidth() << " unroll=" << Hints.getInterleave(
) << "\n"; } } while (0)
1322 : (Hints.getForce() == LoopVectorizeHints::FK_Enableddo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop hints:" <<
" force=" << (Hints.getForce() == LoopVectorizeHints::
FK_Disabled ? "disabled" : (Hints.getForce() == LoopVectorizeHints
::FK_Enabled ? "enabled" : "?")) << " width=" << Hints
.getWidth() << " unroll=" << Hints.getInterleave(
) << "\n"; } } while (0)
1323 ? "enabled"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop hints:" <<
" force=" << (Hints.getForce() == LoopVectorizeHints::
FK_Disabled ? "disabled" : (Hints.getForce() == LoopVectorizeHints
::FK_Enabled ? "enabled" : "?")) << " width=" << Hints
.getWidth() << " unroll=" << Hints.getInterleave(
) << "\n"; } } while (0)
1324 : "?")) << " width=" << Hints.getWidth()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop hints:" <<
" force=" << (Hints.getForce() == LoopVectorizeHints::
FK_Disabled ? "disabled" : (Hints.getForce() == LoopVectorizeHints
::FK_Enabled ? "enabled" : "?")) << " width=" << Hints
.getWidth() << " unroll=" << Hints.getInterleave(
) << "\n"; } } while (0)
1325 << " unroll=" << Hints.getInterleave() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop hints:" <<
" force=" << (Hints.getForce() == LoopVectorizeHints::
FK_Disabled ? "disabled" : (Hints.getForce() == LoopVectorizeHints
::FK_Enabled ? "enabled" : "?")) << " width=" << Hints
.getWidth() << " unroll=" << Hints.getInterleave(
) << "\n"; } } while (0)
;
1326
1327 // Function containing loop
1328 Function *F = L->getHeader()->getParent();
1329
1330 // Looking at the diagnostic output is the only way to determine if a loop
1331 // was vectorized (other than looking at the IR or machine code), so it
1332 // is important to generate an optimization remark for each loop. Most of
1333 // these messages are generated by emitOptimizationRemarkAnalysis. Remarks
1334 // generated by emitOptimizationRemark and emitOptimizationRemarkMissed are
1335 // less verbose reporting vectorized loops and unvectorized loops that may
1336 // benefit from vectorization, respectively.
1337
1338 if (Hints.getForce() == LoopVectorizeHints::FK_Disabled) {
1339 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 (0)
;
1340 emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE"loop-vectorize", *F,
1341 L->getStartLoc(), Hints.emitRemark());
1342 return false;
1343 }
1344
1345 if (!AlwaysVectorize && Hints.getForce() != LoopVectorizeHints::FK_Enabled) {
1346 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 (0)
;
1347 emitOptimizationRemarkAnalysis(F->getContext(), DEBUG_TYPE"loop-vectorize", *F,
1348 L->getStartLoc(), Hints.emitRemark());
1349 return false;
1350 }
1351
1352 if (Hints.getWidth() == 1 && Hints.getInterleave() == 1) {
1353 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 (0)
;
1354 emitOptimizationRemarkAnalysis(
1355 F->getContext(), DEBUG_TYPE"loop-vectorize", *F, L->getStartLoc(),
1356 "loop not vectorized: vector width and interleave count are "
1357 "explicitly set to 1");
1358 return false;
1359 }
1360
1361 // Check the loop for a trip count threshold:
1362 // do not vectorize loops with a tiny trip count.
1363 BasicBlock *Latch = L->getLoopLatch();
1364 const unsigned TC = SE->getSmallConstantTripCount(L, Latch);
1365 if (TC > 0u && TC < TinyTripCountVectorThreshold) {
1366 DEBUG(dbgs() << "LV: Found a loop with a very small trip count. "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a loop with a very small trip count. "
<< "This loop is not worth vectorizing."; } } while (0
)
1367 << "This loop is not worth vectorizing.")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a loop with a very small trip count. "
<< "This loop is not worth vectorizing."; } } while (0
)
;
1368 if (Hints.getForce() == LoopVectorizeHints::FK_Enabled)
1369 DEBUG(dbgs() << " But vectorizing was explicitly forced.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << " But vectorizing was explicitly forced.\n"
; } } while (0)
;
1370 else {
1371 DEBUG(dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "\n"; } } while (0)
;
1372 emitOptimizationRemarkAnalysis(
1373 F->getContext(), DEBUG_TYPE"loop-vectorize", *F, L->getStartLoc(),
1374 "vectorization is not beneficial and is not explicitly forced");
1375 return false;
1376 }
1377 }
1378
1379 // Check if it is legal to vectorize the loop.
1380 LoopVectorizationLegality LVL(L, SE, DL, DT, TLI, AA, F);
1381 if (!LVL.canVectorize()) {
1382 DEBUG(dbgs() << "LV: Not vectorizing: Cannot prove legality.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not vectorizing: Cannot prove legality.\n"
; } } while (0)
;
1383 emitMissedWarning(F, L, Hints);
1384 return false;
1385 }
1386
1387 // Use the cost model.
1388 LoopVectorizationCostModel CM(L, SE, LI, &LVL, *TTI, DL, TLI, F, &Hints);
1389
1390 // Check the function attributes to find out if this function should be
1391 // optimized for size.
1392 bool OptForSize = Hints.getForce() != LoopVectorizeHints::FK_Enabled &&
1393 F->hasFnAttribute(Attribute::OptimizeForSize);
1394
1395 // Compute the weighted frequency of this loop being executed and see if it
1396 // is less than 20% of the function entry baseline frequency. Note that we
1397 // always have a canonical loop here because we think we *can* vectoriez.
1398 // FIXME: This is hidden behind a flag due to pervasive problems with
1399 // exactly what block frequency models.
1400 if (LoopVectorizeWithBlockFrequency) {
1401 BlockFrequency LoopEntryFreq = BFI->getBlockFreq(L->getLoopPreheader());
1402 if (Hints.getForce() != LoopVectorizeHints::FK_Enabled &&
1403 LoopEntryFreq < ColdEntryFreq)
1404 OptForSize = true;
1405 }
1406
1407 // Check the function attributes to see if implicit floats are allowed.a
1408 // FIXME: This check doesn't seem possibly correct -- what if the loop is
1409 // an integer loop and the vector instructions selected are purely integer
1410 // vector instructions?
1411 if (F->hasFnAttribute(Attribute::NoImplicitFloat)) {
1412 DEBUG(dbgs() << "LV: Can't vectorize when the NoImplicitFloat"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Can't vectorize when the NoImplicitFloat"
"attribute is used.\n"; } } while (0)
1413 "attribute is used.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Can't vectorize when the NoImplicitFloat"
"attribute is used.\n"; } } while (0)
;
1414 emitOptimizationRemarkAnalysis(
1415 F->getContext(), DEBUG_TYPE"loop-vectorize", *F, L->getStartLoc(),
1416 "loop not vectorized due to NoImplicitFloat attribute");
1417 emitMissedWarning(F, L, Hints);
1418 return false;
1419 }
1420
1421 // Select the optimal vectorization factor.
1422 const LoopVectorizationCostModel::VectorizationFactor VF =
1423 CM.selectVectorizationFactor(OptForSize);
1424
1425 // Select the unroll factor.
1426 const unsigned UF =
1427 CM.selectUnrollFactor(OptForSize, VF.Width, VF.Cost);
1428
1429 DEBUG(dbgs() << "LV: Found a vectorizable loop (" << VF.Width << ") in "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a vectorizable loop ("
<< VF.Width << ") in " << DebugLocStr <<
'\n'; } } while (0)
1430 << DebugLocStr << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a vectorizable loop ("
<< VF.Width << ") in " << DebugLocStr <<
'\n'; } } while (0)
;
1431 DEBUG(dbgs() << "LV: Unroll Factor is " << UF << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Unroll Factor is "
<< UF << '\n'; } } while (0)
;
1432
1433 if (VF.Width == 1) {
1434 DEBUG(dbgs() << "LV: Vectorization is possible but not beneficial\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Vectorization is possible but not beneficial\n"
; } } while (0)
;
1435
1436 if (UF == 1) {
1437 emitOptimizationRemarkAnalysis(
1438 F->getContext(), DEBUG_TYPE"loop-vectorize", *F, L->getStartLoc(),
1439 "not beneficial to vectorize and user disabled interleaving");
1440 return false;
1441 }
1442 DEBUG(dbgs() << "LV: Trying to at least unroll the loops.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Trying to at least unroll the loops.\n"
; } } while (0)
;
1443
1444 // Report the unrolling decision.
1445 emitOptimizationRemark(F->getContext(), DEBUG_TYPE"loop-vectorize", *F, L->getStartLoc(),
1446 Twine("unrolled with interleaving factor " +
1447 Twine(UF) +
1448 " (vectorization not beneficial)"));
1449
1450 // We decided not to vectorize, but we may want to unroll.
1451
1452 InnerLoopUnroller Unroller(L, SE, LI, DT, DL, TLI, UF);
1453 Unroller.vectorize(&LVL);
1454 } else {
1455 // If we decided that it is *legal* to vectorize the loop then do it.
1456 InnerLoopVectorizer LB(L, SE, LI, DT, DL, TLI, VF.Width, UF);
1457 LB.vectorize(&LVL);
1458 ++LoopsVectorized;
1459
1460 // Report the vectorization decision.
1461 emitOptimizationRemark(
1462 F->getContext(), DEBUG_TYPE"loop-vectorize", *F, L->getStartLoc(),
1463 Twine("vectorized loop (vectorization factor: ") + Twine(VF.Width) +
1464 ", unrolling interleave factor: " + Twine(UF) + ")");
1465 }
1466
1467 // Mark the loop as already vectorized to avoid vectorizing again.
1468 Hints.setAlreadyVectorized();
1469
1470 DEBUG(verifyFunction(*L->getHeader()->getParent()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { verifyFunction(*L->getHeader()->getParent
()); } } while (0)
;
1471 return true;
1472 }
1473
1474 void getAnalysisUsage(AnalysisUsage &AU) const override {
1475 AU.addRequiredID(LoopSimplifyID);
1476 AU.addRequiredID(LCSSAID);
1477 AU.addRequired<BlockFrequencyInfo>();
1478 AU.addRequired<DominatorTreeWrapperPass>();
1479 AU.addRequired<LoopInfo>();
1480 AU.addRequired<ScalarEvolution>();
1481 AU.addRequired<TargetTransformInfo>();
1482 AU.addRequired<AliasAnalysis>();
1483 AU.addPreserved<LoopInfo>();
1484 AU.addPreserved<DominatorTreeWrapperPass>();
1485 AU.addPreserved<AliasAnalysis>();
1486 }
1487
1488};
1489
1490} // end anonymous namespace
1491
1492//===----------------------------------------------------------------------===//
1493// Implementation of LoopVectorizationLegality, InnerLoopVectorizer and
1494// LoopVectorizationCostModel.
1495//===----------------------------------------------------------------------===//
1496
1497static Value *stripIntegerCast(Value *V) {
1498 if (CastInst *CI = dyn_cast<CastInst>(V))
1499 if (CI->getOperand(0)->getType()->isIntegerTy())
1500 return CI->getOperand(0);
1501 return V;
1502}
1503
1504///\brief Replaces the symbolic stride in a pointer SCEV expression by one.
1505///
1506/// If \p OrigPtr is not null, use it to look up the stride value instead of
1507/// \p Ptr.
1508static const SCEV *replaceSymbolicStrideSCEV(ScalarEvolution *SE,
1509 ValueToValueMap &PtrToStride,
1510 Value *Ptr, Value *OrigPtr = nullptr) {
1511
1512 const SCEV *OrigSCEV = SE->getSCEV(Ptr);
1513
1514 // If there is an entry in the map return the SCEV of the pointer with the
1515 // symbolic stride replaced by one.
1516 ValueToValueMap::iterator SI = PtrToStride.find(OrigPtr ? OrigPtr : Ptr);
1517 if (SI != PtrToStride.end()) {
1518 Value *StrideVal = SI->second;
1519
1520 // Strip casts.
1521 StrideVal = stripIntegerCast(StrideVal);
1522
1523 // Replace symbolic stride by one.
1524 Value *One = ConstantInt::get(StrideVal->getType(), 1);
1525 ValueToValueMap RewriteMap;
1526 RewriteMap[StrideVal] = One;
1527
1528 const SCEV *ByOne =
1529 SCEVParameterRewriter::rewrite(OrigSCEV, *SE, RewriteMap, true);
1530 DEBUG(dbgs() << "LV: Replacing SCEV: " << *OrigSCEV << " by: " << *ByOnedo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Replacing SCEV: " <<
*OrigSCEV << " by: " << *ByOne << "\n"; } }
while (0)
1531 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Replacing SCEV: " <<
*OrigSCEV << " by: " << *ByOne << "\n"; } }
while (0)
;
1532 return ByOne;
1533 }
1534
1535 // Otherwise, just return the SCEV of the original pointer.
1536 return SE->getSCEV(Ptr);
1537}
1538
1539void LoopVectorizationLegality::RuntimePointerCheck::insert(
1540 ScalarEvolution *SE, Loop *Lp, Value *Ptr, bool WritePtr, unsigned DepSetId,
1541 unsigned ASId, ValueToValueMap &Strides) {
1542 // Get the stride replaced scev.
1543 const SCEV *Sc = replaceSymbolicStrideSCEV(SE, Strides, Ptr);
1544 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Sc);
1545 assert(AR && "Invalid addrec expression")((AR && "Invalid addrec expression") ? static_cast<
void> (0) : __assert_fail ("AR && \"Invalid addrec expression\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1545, __PRETTY_FUNCTION__))
;
1546 const SCEV *Ex = SE->getBackedgeTakenCount(Lp);
1547 const SCEV *ScEnd = AR->evaluateAtIteration(Ex, *SE);
1548 Pointers.push_back(Ptr);
1549 Starts.push_back(AR->getStart());
1550 Ends.push_back(ScEnd);
1551 IsWritePtr.push_back(WritePtr);
1552 DependencySetId.push_back(DepSetId);
1553 AliasSetId.push_back(ASId);
1554}
1555
1556Value *InnerLoopVectorizer::getBroadcastInstrs(Value *V) {
1557 // We need to place the broadcast of invariant variables outside the loop.
1558 Instruction *Instr = dyn_cast<Instruction>(V);
1559 bool NewInstr =
1560 (Instr && std::find(LoopVectorBody.begin(), LoopVectorBody.end(),
1561 Instr->getParent()) != LoopVectorBody.end());
1562 bool Invariant = OrigLoop->isLoopInvariant(V) && !NewInstr;
1563
1564 // Place the code for broadcasting invariant variables in the new preheader.
1565 IRBuilder<>::InsertPointGuard Guard(Builder);
1566 if (Invariant)
1567 Builder.SetInsertPoint(LoopVectorPreHeader->getTerminator());
1568
1569 // Broadcast the scalar into all locations in the vector.
1570 Value *Shuf = Builder.CreateVectorSplat(VF, V, "broadcast");
1571
1572 return Shuf;
1573}
1574
1575Value *InnerLoopVectorizer::getConsecutiveVector(Value* Val, int StartIdx,
1576 bool Negate) {
1577 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1577, __PRETTY_FUNCTION__))
;
1578 assert(Val->getType()->getScalarType()->isIntegerTy() &&((Val->getType()->getScalarType()->isIntegerTy() &&
"Elem must be an integer") ? static_cast<void> (0) : __assert_fail
("Val->getType()->getScalarType()->isIntegerTy() && \"Elem must be an integer\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1579, __PRETTY_FUNCTION__))
1579 "Elem must be an integer")((Val->getType()->getScalarType()->isIntegerTy() &&
"Elem must be an integer") ? static_cast<void> (0) : __assert_fail
("Val->getType()->getScalarType()->isIntegerTy() && \"Elem must be an integer\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1579, __PRETTY_FUNCTION__))
;
1580 // Create the types.
1581 Type *ITy = Val->getType()->getScalarType();
1582 VectorType *Ty = cast<VectorType>(Val->getType());
1583 int VLen = Ty->getNumElements();
1584 SmallVector<Constant*, 8> Indices;
1585
1586 // Create a vector of consecutive numbers from zero to VF.
1587 for (int i = 0; i < VLen; ++i) {
1588 int64_t Idx = Negate ? (-i) : i;
1589 Indices.push_back(ConstantInt::get(ITy, StartIdx + Idx, Negate));
1590 }
1591
1592 // Add the consecutive indices to the vector value.
1593 Constant *Cv = ConstantVector::get(Indices);
1594 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1594, __PRETTY_FUNCTION__))
;
1595 return Builder.CreateAdd(Val, Cv, "induction");
1596}
1597
1598/// \brief Find the operand of the GEP that should be checked for consecutive
1599/// stores. This ignores trailing indices that have no effect on the final
1600/// pointer.
1601static unsigned getGEPInductionOperand(const DataLayout *DL,
1602 const GetElementPtrInst *Gep) {
1603 unsigned LastOperand = Gep->getNumOperands() - 1;
1604 unsigned GEPAllocSize = DL->getTypeAllocSize(
1605 cast<PointerType>(Gep->getType()->getScalarType())->getElementType());
1606
1607 // Walk backwards and try to peel off zeros.
1608 while (LastOperand > 1 && match(Gep->getOperand(LastOperand), m_Zero())) {
1609 // Find the type we're currently indexing into.
1610 gep_type_iterator GEPTI = gep_type_begin(Gep);
1611 std::advance(GEPTI, LastOperand - 1);
1612
1613 // If it's a type with the same allocation size as the result of the GEP we
1614 // can peel off the zero index.
1615 if (DL->getTypeAllocSize(*GEPTI) != GEPAllocSize)
1616 break;
1617 --LastOperand;
1618 }
1619
1620 return LastOperand;
1621}
1622
1623int LoopVectorizationLegality::isConsecutivePtr(Value *Ptr) {
1624 assert(Ptr->getType()->isPointerTy() && "Unexpected non-ptr")((Ptr->getType()->isPointerTy() && "Unexpected non-ptr"
) ? static_cast<void> (0) : __assert_fail ("Ptr->getType()->isPointerTy() && \"Unexpected non-ptr\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1624, __PRETTY_FUNCTION__))
;
1625 // Make sure that the pointer does not point to structs.
1626 if (Ptr->getType()->getPointerElementType()->isAggregateType())
1627 return 0;
1628
1629 // If this value is a pointer induction variable we know it is consecutive.
1630 PHINode *Phi = dyn_cast_or_null<PHINode>(Ptr);
1631 if (Phi && Inductions.count(Phi)) {
1632 InductionInfo II = Inductions[Phi];
1633 if (IK_PtrInduction == II.IK)
1634 return 1;
1635 else if (IK_ReversePtrInduction == II.IK)
1636 return -1;
1637 }
1638
1639 GetElementPtrInst *Gep = dyn_cast_or_null<GetElementPtrInst>(Ptr);
1640 if (!Gep)
1641 return 0;
1642
1643 unsigned NumOperands = Gep->getNumOperands();
1644 Value *GpPtr = Gep->getPointerOperand();
1645 // If this GEP value is a consecutive pointer induction variable and all of
1646 // the indices are constant then we know it is consecutive. We can
1647 Phi = dyn_cast<PHINode>(GpPtr);
1648 if (Phi && Inductions.count(Phi)) {
1649
1650 // Make sure that the pointer does not point to structs.
1651 PointerType *GepPtrType = cast<PointerType>(GpPtr->getType());
1652 if (GepPtrType->getElementType()->isAggregateType())
1653 return 0;
1654
1655 // Make sure that all of the index operands are loop invariant.
1656 for (unsigned i = 1; i < NumOperands; ++i)
1657 if (!SE->isLoopInvariant(SE->getSCEV(Gep->getOperand(i)), TheLoop))
1658 return 0;
1659
1660 InductionInfo II = Inductions[Phi];
1661 if (IK_PtrInduction == II.IK)
1662 return 1;
1663 else if (IK_ReversePtrInduction == II.IK)
1664 return -1;
1665 }
1666
1667 unsigned InductionOperand = getGEPInductionOperand(DL, Gep);
1668
1669 // Check that all of the gep indices are uniform except for our induction
1670 // operand.
1671 for (unsigned i = 0; i != NumOperands; ++i)
1672 if (i != InductionOperand &&
1673 !SE->isLoopInvariant(SE->getSCEV(Gep->getOperand(i)), TheLoop))
1674 return 0;
1675
1676 // We can emit wide load/stores only if the last non-zero index is the
1677 // induction variable.
1678 const SCEV *Last = nullptr;
1679 if (!Strides.count(Gep))
1680 Last = SE->getSCEV(Gep->getOperand(InductionOperand));
1681 else {
1682 // Because of the multiplication by a stride we can have a s/zext cast.
1683 // We are going to replace this stride by 1 so the cast is safe to ignore.
1684 //
1685 // %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
1686 // %0 = trunc i64 %indvars.iv to i32
1687 // %mul = mul i32 %0, %Stride1
1688 // %idxprom = zext i32 %mul to i64 << Safe cast.
1689 // %arrayidx = getelementptr inbounds i32* %B, i64 %idxprom
1690 //
1691 Last = replaceSymbolicStrideSCEV(SE, Strides,
1692 Gep->getOperand(InductionOperand), Gep);
1693 if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(Last))
1694 Last =
1695 (C->getSCEVType() == scSignExtend || C->getSCEVType() == scZeroExtend)
1696 ? C->getOperand()
1697 : Last;
1698 }
1699 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Last)) {
1700 const SCEV *Step = AR->getStepRecurrence(*SE);
1701
1702 // The memory is consecutive because the last index is consecutive
1703 // and all other indices are loop invariant.
1704 if (Step->isOne())
1705 return 1;
1706 if (Step->isAllOnesValue())
1707 return -1;
1708 }
1709
1710 return 0;
1711}
1712
1713bool LoopVectorizationLegality::isUniform(Value *V) {
1714 return (SE->isLoopInvariant(SE->getSCEV(V), TheLoop));
1715}
1716
1717InnerLoopVectorizer::VectorParts&
1718InnerLoopVectorizer::getVectorValue(Value *V) {
1719 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1719, __PRETTY_FUNCTION__))
;
1720 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1720, __PRETTY_FUNCTION__))
;
1721
1722 // If we have a stride that is replaced by one, do it here.
1723 if (Legal->hasStride(V))
1724 V = ConstantInt::get(V->getType(), 1);
1725
1726 // If we have this scalar in the map, return it.
1727 if (WidenMap.has(V))
1728 return WidenMap.get(V);
1729
1730 // If this scalar is unknown, assume that it is a constant or that it is
1731 // loop invariant. Broadcast V and save the value for future uses.
1732 Value *B = getBroadcastInstrs(V);
1733 return WidenMap.splat(V, B);
1734}
1735
1736Value *InnerLoopVectorizer::reverseVector(Value *Vec) {
1737 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1737, __PRETTY_FUNCTION__))
;
1738 SmallVector<Constant*, 8> ShuffleMask;
1739 for (unsigned i = 0; i < VF; ++i)
1740 ShuffleMask.push_back(Builder.getInt32(VF - i - 1));
1741
1742 return Builder.CreateShuffleVector(Vec, UndefValue::get(Vec->getType()),
1743 ConstantVector::get(ShuffleMask),
1744 "reverse");
1745}
1746
1747void InnerLoopVectorizer::vectorizeMemoryInstruction(Instruction *Instr) {
1748 // Attempt to issue a wide load.
1749 LoadInst *LI = dyn_cast<LoadInst>(Instr);
1750 StoreInst *SI = dyn_cast<StoreInst>(Instr);
1751
1752 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1752, __PRETTY_FUNCTION__))
;
1753
1754 Type *ScalarDataTy = LI ? LI->getType() : SI->getValueOperand()->getType();
1755 Type *DataTy = VectorType::get(ScalarDataTy, VF);
1756 Value *Ptr = LI ? LI->getPointerOperand() : SI->getPointerOperand();
1757 unsigned Alignment = LI ? LI->getAlignment() : SI->getAlignment();
1758 // An alignment of 0 means target abi alignment. We need to use the scalar's
1759 // target abi alignment in such a case.
1760 if (!Alignment)
1761 Alignment = DL->getABITypeAlignment(ScalarDataTy);
1762 unsigned AddressSpace = Ptr->getType()->getPointerAddressSpace();
1763 unsigned ScalarAllocatedSize = DL->getTypeAllocSize(ScalarDataTy);
1764 unsigned VectorElementSize = DL->getTypeStoreSize(DataTy)/VF;
1765
1766 if (SI && Legal->blockNeedsPredication(SI->getParent()))
1767 return scalarizeInstruction(Instr, true);
1768
1769 if (ScalarAllocatedSize != VectorElementSize)
1770 return scalarizeInstruction(Instr);
1771
1772 // If the pointer is loop invariant or if it is non-consecutive,
1773 // scalarize the load.
1774 int ConsecutiveStride = Legal->isConsecutivePtr(Ptr);
1775 bool Reverse = ConsecutiveStride < 0;
1776 bool UniformLoad = LI && Legal->isUniform(Ptr);
1777 if (!ConsecutiveStride || UniformLoad)
1778 return scalarizeInstruction(Instr);
1779
1780 Constant *Zero = Builder.getInt32(0);
1781 VectorParts &Entry = WidenMap.get(Instr);
1782
1783 // Handle consecutive loads/stores.
1784 GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr);
1785 if (Gep && Legal->isInductionVariable(Gep->getPointerOperand())) {
1786 setDebugLocFromInst(Builder, Gep);
1787 Value *PtrOperand = Gep->getPointerOperand();
1788 Value *FirstBasePtr = getVectorValue(PtrOperand)[0];
1789 FirstBasePtr = Builder.CreateExtractElement(FirstBasePtr, Zero);
1790
1791 // Create the new GEP with the new induction variable.
1792 GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
1793 Gep2->setOperand(0, FirstBasePtr);
1794 Gep2->setName("gep.indvar.base");
1795 Ptr = Builder.Insert(Gep2);
1796 } else if (Gep) {
1797 setDebugLocFromInst(Builder, Gep);
1798 assert(SE->isLoopInvariant(SE->getSCEV(Gep->getPointerOperand()),((SE->isLoopInvariant(SE->getSCEV(Gep->getPointerOperand
()), OrigLoop) && "Base ptr must be invariant") ? static_cast
<void> (0) : __assert_fail ("SE->isLoopInvariant(SE->getSCEV(Gep->getPointerOperand()), OrigLoop) && \"Base ptr must be invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1799, __PRETTY_FUNCTION__))
1799 OrigLoop) && "Base ptr must be invariant")((SE->isLoopInvariant(SE->getSCEV(Gep->getPointerOperand
()), OrigLoop) && "Base ptr must be invariant") ? static_cast
<void> (0) : __assert_fail ("SE->isLoopInvariant(SE->getSCEV(Gep->getPointerOperand()), OrigLoop) && \"Base ptr must be invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1799, __PRETTY_FUNCTION__))
;
1800
1801 // The last index does not have to be the induction. It can be
1802 // consecutive and be a function of the index. For example A[I+1];
1803 unsigned NumOperands = Gep->getNumOperands();
1804 unsigned InductionOperand = getGEPInductionOperand(DL, Gep);
1805 // Create the new GEP with the new induction variable.
1806 GetElementPtrInst *Gep2 = cast<GetElementPtrInst>(Gep->clone());
1807
1808 for (unsigned i = 0; i < NumOperands; ++i) {
1809 Value *GepOperand = Gep->getOperand(i);
1810 Instruction *GepOperandInst = dyn_cast<Instruction>(GepOperand);
1811
1812 // Update last index or loop invariant instruction anchored in loop.
1813 if (i == InductionOperand ||
1814 (GepOperandInst && OrigLoop->contains(GepOperandInst))) {
1815 assert((i == InductionOperand ||(((i == InductionOperand || SE->isLoopInvariant(SE->getSCEV
(GepOperandInst), OrigLoop)) && "Must be last index or loop invariant"
) ? static_cast<void> (0) : __assert_fail ("(i == InductionOperand || SE->isLoopInvariant(SE->getSCEV(GepOperandInst), OrigLoop)) && \"Must be last index or loop invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1817, __PRETTY_FUNCTION__))
1816 SE->isLoopInvariant(SE->getSCEV(GepOperandInst), OrigLoop)) &&(((i == InductionOperand || SE->isLoopInvariant(SE->getSCEV
(GepOperandInst), OrigLoop)) && "Must be last index or loop invariant"
) ? static_cast<void> (0) : __assert_fail ("(i == InductionOperand || SE->isLoopInvariant(SE->getSCEV(GepOperandInst), OrigLoop)) && \"Must be last index or loop invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1817, __PRETTY_FUNCTION__))
1817 "Must be last index or loop invariant")(((i == InductionOperand || SE->isLoopInvariant(SE->getSCEV
(GepOperandInst), OrigLoop)) && "Must be last index or loop invariant"
) ? static_cast<void> (0) : __assert_fail ("(i == InductionOperand || SE->isLoopInvariant(SE->getSCEV(GepOperandInst), OrigLoop)) && \"Must be last index or loop invariant\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1817, __PRETTY_FUNCTION__))
;
1818
1819 VectorParts &GEPParts = getVectorValue(GepOperand);
1820 Value *Index = GEPParts[0];
1821 Index = Builder.CreateExtractElement(Index, Zero);
1822 Gep2->setOperand(i, Index);
1823 Gep2->setName("gep.indvar.idx");
1824 }
1825 }
1826 Ptr = Builder.Insert(Gep2);
1827 } else {
1828 // Use the induction element ptr.
1829 assert(isa<PHINode>(Ptr) && "Invalid induction ptr")((isa<PHINode>(Ptr) && "Invalid induction ptr")
? static_cast<void> (0) : __assert_fail ("isa<PHINode>(Ptr) && \"Invalid induction ptr\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1829, __PRETTY_FUNCTION__))
;
1830 setDebugLocFromInst(Builder, Ptr);
1831 VectorParts &PtrVal = getVectorValue(Ptr);
1832 Ptr = Builder.CreateExtractElement(PtrVal[0], Zero);
1833 }
1834
1835 // Handle Stores:
1836 if (SI) {
1837 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1838, __PRETTY_FUNCTION__))
1838 "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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1838, __PRETTY_FUNCTION__))
;
1839 setDebugLocFromInst(Builder, SI);
1840 // We don't want to update the value in the map as it might be used in
1841 // another expression. So don't use a reference type for "StoredVal".
1842 VectorParts StoredVal = getVectorValue(SI->getValueOperand());
1843
1844 for (unsigned Part = 0; Part < UF; ++Part) {
1845 // Calculate the pointer for the specific unroll-part.
1846 Value *PartPtr = Builder.CreateGEP(Ptr, Builder.getInt32(Part * VF));
1847
1848 if (Reverse) {
1849 // If we store to reverse consecutive memory locations then we need
1850 // to reverse the order of elements in the stored value.
1851 StoredVal[Part] = reverseVector(StoredVal[Part]);
1852 // If the address is consecutive but reversed, then the
1853 // wide store needs to start at the last vector element.
1854 PartPtr = Builder.CreateGEP(Ptr, Builder.getInt32(-Part * VF));
1855 PartPtr = Builder.CreateGEP(PartPtr, Builder.getInt32(1 - VF));
1856 }
1857
1858 Value *VecPtr = Builder.CreateBitCast(PartPtr,
1859 DataTy->getPointerTo(AddressSpace));
1860 StoreInst *NewSI =
1861 Builder.CreateAlignedStore(StoredVal[Part], VecPtr, Alignment);
1862 propagateMetadata(NewSI, SI);
1863 }
1864 return;
1865 }
1866
1867 // Handle loads.
1868 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1868, __PRETTY_FUNCTION__))
;
1869 setDebugLocFromInst(Builder, LI);
1870 for (unsigned Part = 0; Part < UF; ++Part) {
1871 // Calculate the pointer for the specific unroll-part.
1872 Value *PartPtr = Builder.CreateGEP(Ptr, Builder.getInt32(Part * VF));
1873
1874 if (Reverse) {
1875 // If the address is consecutive but reversed, then the
1876 // wide store needs to start at the last vector element.
1877 PartPtr = Builder.CreateGEP(Ptr, Builder.getInt32(-Part * VF));
1878 PartPtr = Builder.CreateGEP(PartPtr, Builder.getInt32(1 - VF));
1879 }
1880
1881 Value *VecPtr = Builder.CreateBitCast(PartPtr,
1882 DataTy->getPointerTo(AddressSpace));
1883 LoadInst *NewLI = Builder.CreateAlignedLoad(VecPtr, Alignment, "wide.load");
1884 propagateMetadata(NewLI, LI);
1885 Entry[Part] = Reverse ? reverseVector(NewLI) : NewLI;
1886 }
1887}
1888
1889void InnerLoopVectorizer::scalarizeInstruction(Instruction *Instr, bool IfPredicateStore) {
1890 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1890, __PRETTY_FUNCTION__))
;
1891 // Holds vector parameters or scalars, in case of uniform vals.
1892 SmallVector<VectorParts, 4> Params;
1893
1894 setDebugLocFromInst(Builder, Instr);
1895
1896 // Find all of the vectorized parameters.
1897 for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) {
1898 Value *SrcOp = Instr->getOperand(op);
1899
1900 // If we are accessing the old induction variable, use the new one.
1901 if (SrcOp == OldInduction) {
1902 Params.push_back(getVectorValue(SrcOp));
1903 continue;
1904 }
1905
1906 // Try using previously calculated values.
1907 Instruction *SrcInst = dyn_cast<Instruction>(SrcOp);
1908
1909 // If the src is an instruction that appeared earlier in the basic block
1910 // then it should already be vectorized.
1911 if (SrcInst && OrigLoop->contains(SrcInst)) {
1912 assert(WidenMap.has(SrcInst) && "Source operand is unavailable")((WidenMap.has(SrcInst) && "Source operand is unavailable"
) ? static_cast<void> (0) : __assert_fail ("WidenMap.has(SrcInst) && \"Source operand is unavailable\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1912, __PRETTY_FUNCTION__))
;
1913 // The parameter is a vector value from earlier.
1914 Params.push_back(WidenMap.get(SrcInst));
1915 } else {
1916 // The parameter is a scalar from outside the loop. Maybe even a constant.
1917 VectorParts Scalars;
1918 Scalars.append(UF, SrcOp);
1919 Params.push_back(Scalars);
1920 }
1921 }
1922
1923 assert(Params.size() == Instr->getNumOperands() &&((Params.size() == Instr->getNumOperands() && "Invalid number of operands"
) ? static_cast<void> (0) : __assert_fail ("Params.size() == Instr->getNumOperands() && \"Invalid number of operands\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1924, __PRETTY_FUNCTION__))
1924 "Invalid number of operands")((Params.size() == Instr->getNumOperands() && "Invalid number of operands"
) ? static_cast<void> (0) : __assert_fail ("Params.size() == Instr->getNumOperands() && \"Invalid number of operands\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1924, __PRETTY_FUNCTION__))
;
1925
1926 // Does this instruction return a value ?
1927 bool IsVoidRetTy = Instr->getType()->isVoidTy();
1928
1929 Value *UndefVec = IsVoidRetTy ? nullptr :
1930 UndefValue::get(VectorType::get(Instr->getType(), VF));
1931 // Create a new entry in the WidenMap and initialize it to Undef or Null.
1932 VectorParts &VecResults = WidenMap.splat(Instr, UndefVec);
1933
1934 Instruction *InsertPt = Builder.GetInsertPoint();
1935 BasicBlock *IfBlock = Builder.GetInsertBlock();
1936 BasicBlock *CondBlock = nullptr;
1937
1938 VectorParts Cond;
1939 Loop *VectorLp = nullptr;
1940 if (IfPredicateStore) {
1941 assert(Instr->getParent()->getSinglePredecessor() &&((Instr->getParent()->getSinglePredecessor() &&
"Only support single predecessor blocks") ? static_cast<void
> (0) : __assert_fail ("Instr->getParent()->getSinglePredecessor() && \"Only support single predecessor blocks\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1942, __PRETTY_FUNCTION__))
1942 "Only support single predecessor blocks")((Instr->getParent()->getSinglePredecessor() &&
"Only support single predecessor blocks") ? static_cast<void
> (0) : __assert_fail ("Instr->getParent()->getSinglePredecessor() && \"Only support single predecessor blocks\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1942, __PRETTY_FUNCTION__))
;
1943 Cond = createEdgeMask(Instr->getParent()->getSinglePredecessor(),
1944 Instr->getParent());
1945 VectorLp = LI->getLoopFor(IfBlock);
1946 assert(VectorLp && "Must have a loop for this block")((VectorLp && "Must have a loop for this block") ? static_cast
<void> (0) : __assert_fail ("VectorLp && \"Must have a loop for this block\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 1946, __PRETTY_FUNCTION__))
;
1947 }
1948
1949 // For each vector unroll 'part':
1950 for (unsigned Part = 0; Part < UF; ++Part) {
1951 // For each scalar that we create:
1952 for (unsigned Width = 0; Width < VF; ++Width) {
1953
1954 // Start if-block.
1955 Value *Cmp = nullptr;
1956 if (IfPredicateStore) {
1957 Cmp = Builder.CreateExtractElement(Cond[Part], Builder.getInt32(Width));
1958 Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Cmp, ConstantInt::get(Cmp->getType(), 1));
1959 CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
1960 LoopVectorBody.push_back(CondBlock);
1961 VectorLp->addBasicBlockToLoop(CondBlock, LI->getBase());
1962 // Update Builder with newly created basic block.
1963 Builder.SetInsertPoint(InsertPt);
1964 }
1965
1966 Instruction *Cloned = Instr->clone();
1967 if (!IsVoidRetTy)
1968 Cloned->setName(Instr->getName() + ".cloned");
1969 // Replace the operands of the cloned instructions with extracted scalars.
1970 for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) {
1971 Value *Op = Params[op][Part];
1972 // Param is a vector. Need to extract the right lane.
1973 if (Op->getType()->isVectorTy())
1974 Op = Builder.CreateExtractElement(Op, Builder.getInt32(Width));
1975 Cloned->setOperand(op, Op);
1976 }
1977
1978 // Place the cloned scalar in the new loop.
1979 Builder.Insert(Cloned);
1980
1981 // If the original scalar returns a value we need to place it in a vector
1982 // so that future users will be able to use it.
1983 if (!IsVoidRetTy)
1984 VecResults[Part] = Builder.CreateInsertElement(VecResults[Part], Cloned,
1985 Builder.getInt32(Width));
1986 // End if-block.
1987 if (IfPredicateStore) {
1988 BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
1989 LoopVectorBody.push_back(NewIfBlock);
1990 VectorLp->addBasicBlockToLoop(NewIfBlock, LI->getBase());
1991 Builder.SetInsertPoint(InsertPt);
1992 Instruction *OldBr = IfBlock->getTerminator();
1993 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
1994 OldBr->eraseFromParent();
1995 IfBlock = NewIfBlock;
1996 }
1997 }
1998 }
1999}
2000
2001static Instruction *getFirstInst(Instruction *FirstInst, Value *V,
2002 Instruction *Loc) {
2003 if (FirstInst)
2004 return FirstInst;
2005 if (Instruction *I = dyn_cast<Instruction>(V))
2006 return I->getParent() == Loc->getParent() ? I : nullptr;
2007 return nullptr;
2008}
2009
2010std::pair<Instruction *, Instruction *>
2011InnerLoopVectorizer::addStrideCheck(Instruction *Loc) {
2012 Instruction *tnullptr = nullptr;
2013 if (!Legal->mustCheckStrides())
2014 return std::pair<Instruction *, Instruction *>(tnullptr, tnullptr);
2015
2016 IRBuilder<> ChkBuilder(Loc);
2017
2018 // Emit checks.
2019 Value *Check = nullptr;
2020 Instruction *FirstInst = nullptr;
2021 for (SmallPtrSet<Value *, 8>::iterator SI = Legal->strides_begin(),
2022 SE = Legal->strides_end();
2023 SI != SE; ++SI) {
2024 Value *Ptr = stripIntegerCast(*SI);
2025 Value *C = ChkBuilder.CreateICmpNE(Ptr, ConstantInt::get(Ptr->getType(), 1),
2026 "stride.chk");
2027 // Store the first instruction we create.
2028 FirstInst = getFirstInst(FirstInst, C, Loc);
2029 if (Check)
2030 Check = ChkBuilder.CreateOr(Check, C);
2031 else
2032 Check = C;
2033 }
2034
2035 // We have to do this trickery because the IRBuilder might fold the check to a
2036 // constant expression in which case there is no Instruction anchored in a
2037 // the block.
2038 LLVMContext &Ctx = Loc->getContext();
2039 Instruction *TheCheck =
2040 BinaryOperator::CreateAnd(Check, ConstantInt::getTrue(Ctx));
2041 ChkBuilder.Insert(TheCheck, "stride.not.one");
2042 FirstInst = getFirstInst(FirstInst, TheCheck, Loc);
2043
2044 return std::make_pair(FirstInst, TheCheck);
2045}
2046
2047std::pair<Instruction *, Instruction *>
2048InnerLoopVectorizer::addRuntimeCheck(Instruction *Loc) {
2049 LoopVectorizationLegality::RuntimePointerCheck *PtrRtCheck =
2050 Legal->getRuntimePointerCheck();
2051
2052 Instruction *tnullptr = nullptr;
2053 if (!PtrRtCheck->Need)
2054 return std::pair<Instruction *, Instruction *>(tnullptr, tnullptr);
2055
2056 unsigned NumPointers = PtrRtCheck->Pointers.size();
2057 SmallVector<TrackingVH<Value> , 2> Starts;
2058 SmallVector<TrackingVH<Value> , 2> Ends;
2059
2060 LLVMContext &Ctx = Loc->getContext();
2061 SCEVExpander Exp(*SE, "induction");
2062 Instruction *FirstInst = nullptr;
2063
2064 for (unsigned i = 0; i < NumPointers; ++i) {
2065 Value *Ptr = PtrRtCheck->Pointers[i];
2066 const SCEV *Sc = SE->getSCEV(Ptr);
2067
2068 if (SE->isLoopInvariant(Sc, OrigLoop)) {
2069 DEBUG(dbgs() << "LV: Adding RT check for a loop invariant ptr:" <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Adding RT check for a loop invariant ptr:"
<< *Ptr <<"\n"; } } while (0)
2070 *Ptr <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Adding RT check for a loop invariant ptr:"
<< *Ptr <<"\n"; } } while (0)
;
2071 Starts.push_back(Ptr);
2072 Ends.push_back(Ptr);
2073 } else {
2074 DEBUG(dbgs() << "LV: Adding RT check for range:" << *Ptr << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Adding RT check for range:"
<< *Ptr << '\n'; } } while (0)
;
2075 unsigned AS = Ptr->getType()->getPointerAddressSpace();
2076
2077 // Use this type for pointer arithmetic.
2078 Type *PtrArithTy = Type::getInt8PtrTy(Ctx, AS);
2079
2080 Value *Start = Exp.expandCodeFor(PtrRtCheck->Starts[i], PtrArithTy, Loc);
2081 Value *End = Exp.expandCodeFor(PtrRtCheck->Ends[i], PtrArithTy, Loc);
2082 Starts.push_back(Start);
2083 Ends.push_back(End);
2084 }
2085 }
2086
2087 IRBuilder<> ChkBuilder(Loc);
2088 // Our instructions might fold to a constant.
2089 Value *MemoryRuntimeCheck = nullptr;
2090 for (unsigned i = 0; i < NumPointers; ++i) {
2091 for (unsigned j = i+1; j < NumPointers; ++j) {
2092 // No need to check if two readonly pointers intersect.
2093 if (!PtrRtCheck->IsWritePtr[i] && !PtrRtCheck->IsWritePtr[j])
2094 continue;
2095
2096 // Only need to check pointers between two different dependency sets.
2097 if (PtrRtCheck->DependencySetId[i] == PtrRtCheck->DependencySetId[j])
2098 continue;
2099 // Only need to check pointers in the same alias set.
2100 if (PtrRtCheck->AliasSetId[i] != PtrRtCheck->AliasSetId[j])
2101 continue;
2102
2103 unsigned AS0 = Starts[i]->getType()->getPointerAddressSpace();
2104 unsigned AS1 = Starts[j]->getType()->getPointerAddressSpace();
2105
2106 assert((AS0 == Ends[j]->getType()->getPointerAddressSpace()) &&(((AS0 == Ends[j]->getType()->getPointerAddressSpace())
&& (AS1 == Ends[i]->getType()->getPointerAddressSpace
()) && "Trying to bounds check pointers with different address spaces"
) ? static_cast<void> (0) : __assert_fail ("(AS0 == Ends[j]->getType()->getPointerAddressSpace()) && (AS1 == Ends[i]->getType()->getPointerAddressSpace()) && \"Trying to bounds check pointers with different address spaces\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2108, __PRETTY_FUNCTION__))
2107 (AS1 == Ends[i]->getType()->getPointerAddressSpace()) &&(((AS0 == Ends[j]->getType()->getPointerAddressSpace())
&& (AS1 == Ends[i]->getType()->getPointerAddressSpace
()) && "Trying to bounds check pointers with different address spaces"
) ? static_cast<void> (0) : __assert_fail ("(AS0 == Ends[j]->getType()->getPointerAddressSpace()) && (AS1 == Ends[i]->getType()->getPointerAddressSpace()) && \"Trying to bounds check pointers with different address spaces\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2108, __PRETTY_FUNCTION__))
2108 "Trying to bounds check pointers with different address spaces")(((AS0 == Ends[j]->getType()->getPointerAddressSpace())
&& (AS1 == Ends[i]->getType()->getPointerAddressSpace
()) && "Trying to bounds check pointers with different address spaces"
) ? static_cast<void> (0) : __assert_fail ("(AS0 == Ends[j]->getType()->getPointerAddressSpace()) && (AS1 == Ends[i]->getType()->getPointerAddressSpace()) && \"Trying to bounds check pointers with different address spaces\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2108, __PRETTY_FUNCTION__))
;
2109
2110 Type *PtrArithTy0 = Type::getInt8PtrTy(Ctx, AS0);
2111 Type *PtrArithTy1 = Type::getInt8PtrTy(Ctx, AS1);
2112
2113 Value *Start0 = ChkBuilder.CreateBitCast(Starts[i], PtrArithTy0, "bc");
2114 Value *Start1 = ChkBuilder.CreateBitCast(Starts[j], PtrArithTy1, "bc");
2115 Value *End0 = ChkBuilder.CreateBitCast(Ends[i], PtrArithTy1, "bc");
2116 Value *End1 = ChkBuilder.CreateBitCast(Ends[j], PtrArithTy0, "bc");
2117
2118 Value *Cmp0 = ChkBuilder.CreateICmpULE(Start0, End1, "bound0");
2119 FirstInst = getFirstInst(FirstInst, Cmp0, Loc);
2120 Value *Cmp1 = ChkBuilder.CreateICmpULE(Start1, End0, "bound1");
2121 FirstInst = getFirstInst(FirstInst, Cmp1, Loc);
2122 Value *IsConflict = ChkBuilder.CreateAnd(Cmp0, Cmp1, "found.conflict");
2123 FirstInst = getFirstInst(FirstInst, IsConflict, Loc);
2124 if (MemoryRuntimeCheck) {
2125 IsConflict = ChkBuilder.CreateOr(MemoryRuntimeCheck, IsConflict,
2126 "conflict.rdx");
2127 FirstInst = getFirstInst(FirstInst, IsConflict, Loc);
2128 }
2129 MemoryRuntimeCheck = IsConflict;
2130 }
2131 }
2132
2133 // We have to do this trickery because the IRBuilder might fold the check to a
2134 // constant expression in which case there is no Instruction anchored in a
2135 // the block.
2136 Instruction *Check = BinaryOperator::CreateAnd(MemoryRuntimeCheck,
2137 ConstantInt::getTrue(Ctx));
2138 ChkBuilder.Insert(Check, "memcheck.conflict");
2139 FirstInst = getFirstInst(FirstInst, Check, Loc);
2140 return std::make_pair(FirstInst, Check);
2141}
2142
2143void InnerLoopVectorizer::createEmptyLoop() {
2144 /*
2145 In this function we generate a new loop. The new loop will contain
2146 the vectorized instructions while the old loop will continue to run the
2147 scalar remainder.
2148
2149 [ ] <-- Back-edge taken count overflow check.
2150 / |
2151 / v
2152 | [ ] <-- vector loop bypass (may consist of multiple blocks).
2153 | / |
2154 | / v
2155 || [ ] <-- vector pre header.
2156 || |
2157 || v
2158 || [ ] \
2159 || [ ]_| <-- vector loop.
2160 || |
2161 | \ v
2162 | >[ ] <--- middle-block.
2163 | / |
2164 | / v
2165 -|- >[ ] <--- new preheader.
2166 | |
2167 | v
2168 | [ ] \
2169 | [ ]_| <-- old scalar loop to handle remainder.
2170 \ |
2171 \ v
2172 >[ ] <-- exit block.
2173 ...
2174 */
2175
2176 BasicBlock *OldBasicBlock = OrigLoop->getHeader();
2177 BasicBlock *BypassBlock = OrigLoop->getLoopPreheader();
2178 BasicBlock *ExitBlock = OrigLoop->getExitBlock();
2179 assert(BypassBlock && "Invalid loop structure")((BypassBlock && "Invalid loop structure") ? static_cast
<void> (0) : __assert_fail ("BypassBlock && \"Invalid loop structure\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2179, __PRETTY_FUNCTION__))
;
2180 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2180, __PRETTY_FUNCTION__))
;
2181
2182 // Some loops have a single integer induction variable, while other loops
2183 // don't. One example is c++ iterators that often have multiple pointer
2184 // induction variables. In the code below we also support a case where we
2185 // don't have a single induction variable.
2186 OldInduction = Legal->getInduction();
2187 Type *IdxTy = Legal->getWidestInductionType();
2188
2189 // Find the loop boundaries.
2190 const SCEV *ExitCount = SE->getBackedgeTakenCount(OrigLoop);
2191 assert(ExitCount != SE->getCouldNotCompute() && "Invalid loop count")((ExitCount != SE->getCouldNotCompute() && "Invalid loop count"
) ? static_cast<void> (0) : __assert_fail ("ExitCount != SE->getCouldNotCompute() && \"Invalid loop count\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2191, __PRETTY_FUNCTION__))
;
2192
2193 // The exit count might have the type of i64 while the phi is i32. This can
2194 // happen if we have an induction variable that is sign extended before the
2195 // compare. The only way that we get a backedge taken count is that the
2196 // induction variable was signed and as such will not overflow. In such a case
2197 // truncation is legal.
2198 if (ExitCount->getType()->getPrimitiveSizeInBits() >
2199 IdxTy->getPrimitiveSizeInBits())
2200 ExitCount = SE->getTruncateOrNoop(ExitCount, IdxTy);
2201
2202 const SCEV *BackedgeTakeCount = SE->getNoopOrZeroExtend(ExitCount, IdxTy);
2203 // Get the total trip count from the count by adding 1.
2204 ExitCount = SE->getAddExpr(BackedgeTakeCount,
2205 SE->getConstant(BackedgeTakeCount->getType(), 1));
2206
2207 // Expand the trip count and place the new instructions in the preheader.
2208 // Notice that the pre-header does not change, only the loop body.
2209 SCEVExpander Exp(*SE, "induction");
2210
2211 // We need to test whether the backedge-taken count is uint##_max. Adding one
2212 // to it will cause overflow and an incorrect loop trip count in the vector
2213 // body. In case of overflow we want to directly jump to the scalar remainder
2214 // loop.
2215 Value *BackedgeCount =
2216 Exp.expandCodeFor(BackedgeTakeCount, BackedgeTakeCount->getType(),
2217 BypassBlock->getTerminator());
2218 if (BackedgeCount->getType()->isPointerTy())
2219 BackedgeCount = CastInst::CreatePointerCast(BackedgeCount, IdxTy,
2220 "backedge.ptrcnt.to.int",
2221 BypassBlock->getTerminator());
2222 Instruction *CheckBCOverflow =
2223 CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ, BackedgeCount,
2224 Constant::getAllOnesValue(BackedgeCount->getType()),
2225 "backedge.overflow", BypassBlock->getTerminator());
2226
2227 // The loop index does not have to start at Zero. Find the original start
2228 // value from the induction PHI node. If we don't have an induction variable
2229 // then we know that it starts at zero.
2230 Builder.SetInsertPoint(BypassBlock->getTerminator());
2231 Value *StartIdx = ExtendedIdx = OldInduction ?
2232 Builder.CreateZExt(OldInduction->getIncomingValueForBlock(BypassBlock),
2233 IdxTy):
2234 ConstantInt::get(IdxTy, 0);
2235
2236 // We need an instruction to anchor the overflow check on. StartIdx needs to
2237 // be defined before the overflow check branch. Because the scalar preheader
2238 // is going to merge the start index and so the overflow branch block needs to
2239 // contain a definition of the start index.
2240 Instruction *OverflowCheckAnchor = BinaryOperator::CreateAdd(
2241 StartIdx, ConstantInt::get(IdxTy, 0), "overflow.check.anchor",
2242 BypassBlock->getTerminator());
2243
2244 // Count holds the overall loop count (N).
2245 Value *Count = Exp.expandCodeFor(ExitCount, ExitCount->getType(),
2246 BypassBlock->getTerminator());
2247
2248 LoopBypassBlocks.push_back(BypassBlock);
2249
2250 // Split the single block loop into the two loop structure described above.
2251 BasicBlock *VectorPH =
2252 BypassBlock->splitBasicBlock(BypassBlock->getTerminator(), "vector.ph");
2253 BasicBlock *VecBody =
2254 VectorPH->splitBasicBlock(VectorPH->getTerminator(), "vector.body");
2255 BasicBlock *MiddleBlock =
2256 VecBody->splitBasicBlock(VecBody->getTerminator(), "middle.block");
2257 BasicBlock *ScalarPH =
2258 MiddleBlock->splitBasicBlock(MiddleBlock->getTerminator(), "scalar.ph");
2259
2260 // Create and register the new vector loop.
2261 Loop* Lp = new Loop();
2262 Loop *ParentLoop = OrigLoop->getParentLoop();
2263
2264 // Insert the new loop into the loop nest and register the new basic blocks
2265 // before calling any utilities such as SCEV that require valid LoopInfo.
2266 if (ParentLoop) {
2267 ParentLoop->addChildLoop(Lp);
2268 ParentLoop->addBasicBlockToLoop(ScalarPH, LI->getBase());
2269 ParentLoop->addBasicBlockToLoop(VectorPH, LI->getBase());
2270 ParentLoop->addBasicBlockToLoop(MiddleBlock, LI->getBase());
2271 } else {
2272 LI->addTopLevelLoop(Lp);
2273 }
2274 Lp->addBasicBlockToLoop(VecBody, LI->getBase());
2275
2276 // Use this IR builder to create the loop instructions (Phi, Br, Cmp)
2277 // inside the loop.
2278 Builder.SetInsertPoint(VecBody->getFirstNonPHI());
2279
2280 // Generate the induction variable.
2281 setDebugLocFromInst(Builder, getDebugLocFromInstOrOperands(OldInduction));
2282 Induction = Builder.CreatePHI(IdxTy, 2, "index");
2283 // The loop step is equal to the vectorization factor (num of SIMD elements)
2284 // times the unroll factor (num of SIMD instructions).
2285 Constant *Step = ConstantInt::get(IdxTy, VF * UF);
2286
2287 // This is the IR builder that we use to add all of the logic for bypassing
2288 // the new vector loop.
2289 IRBuilder<> BypassBuilder(BypassBlock->getTerminator());
2290 setDebugLocFromInst(BypassBuilder,
2291 getDebugLocFromInstOrOperands(OldInduction));
2292
2293 // We may need to extend the index in case there is a type mismatch.
2294 // We know that the count starts at zero and does not overflow.
2295 if (Count->getType() != IdxTy) {
2296 // The exit count can be of pointer type. Convert it to the correct
2297 // integer type.
2298 if (ExitCount->getType()->isPointerTy())
2299 Count = BypassBuilder.CreatePointerCast(Count, IdxTy, "ptrcnt.to.int");
2300 else
2301 Count = BypassBuilder.CreateZExtOrTrunc(Count, IdxTy, "cnt.cast");
2302 }
2303
2304 // Add the start index to the loop count to get the new end index.
2305 Value *IdxEnd = BypassBuilder.CreateAdd(Count, StartIdx, "end.idx");
2306
2307 // Now we need to generate the expression for N - (N % VF), which is
2308 // the part that the vectorized body will execute.
2309 Value *R = BypassBuilder.CreateURem(Count, Step, "n.mod.vf");
2310 Value *CountRoundDown = BypassBuilder.CreateSub(Count, R, "n.vec");
2311 Value *IdxEndRoundDown = BypassBuilder.CreateAdd(CountRoundDown, StartIdx,
2312 "end.idx.rnd.down");
2313
2314 // Now, compare the new count to zero. If it is zero skip the vector loop and
2315 // jump to the scalar loop.
2316 Value *Cmp =
2317 BypassBuilder.CreateICmpEQ(IdxEndRoundDown, StartIdx, "cmp.zero");
2318
2319 BasicBlock *LastBypassBlock = BypassBlock;
2320
2321 // Generate code to check that the loops trip count that we computed by adding
2322 // one to the backedge-taken count will not overflow.
2323 {
2324 auto PastOverflowCheck =
2325 std::next(BasicBlock::iterator(OverflowCheckAnchor));
2326 BasicBlock *CheckBlock =
2327 LastBypassBlock->splitBasicBlock(PastOverflowCheck, "overflow.checked");
2328 if (ParentLoop)
2329 ParentLoop->addBasicBlockToLoop(CheckBlock, LI->getBase());
2330 LoopBypassBlocks.push_back(CheckBlock);
2331 Instruction *OldTerm = LastBypassBlock->getTerminator();
2332 BranchInst::Create(ScalarPH, CheckBlock, CheckBCOverflow, OldTerm);
2333 OldTerm->eraseFromParent();
2334 LastBypassBlock = CheckBlock;
2335 }
2336
2337 // Generate the code to check that the strides we assumed to be one are really
2338 // one. We want the new basic block to start at the first instruction in a
2339 // sequence of instructions that form a check.
2340 Instruction *StrideCheck;
2341 Instruction *FirstCheckInst;
2342 std::tie(FirstCheckInst, StrideCheck) =
2343 addStrideCheck(LastBypassBlock->getTerminator());
2344 if (StrideCheck) {
2345 // Create a new block containing the stride check.
2346 BasicBlock *CheckBlock =
2347 LastBypassBlock->splitBasicBlock(FirstCheckInst, "vector.stridecheck");
2348 if (ParentLoop)
2349 ParentLoop->addBasicBlockToLoop(CheckBlock, LI->getBase());
2350 LoopBypassBlocks.push_back(CheckBlock);
2351
2352 // Replace the branch into the memory check block with a conditional branch
2353 // for the "few elements case".
2354 Instruction *OldTerm = LastBypassBlock->getTerminator();
2355 BranchInst::Create(MiddleBlock, CheckBlock, Cmp, OldTerm);
2356 OldTerm->eraseFromParent();
2357
2358 Cmp = StrideCheck;
2359 LastBypassBlock = CheckBlock;
2360 }
2361
2362 // Generate the code that checks in runtime if arrays overlap. We put the
2363 // checks into a separate block to make the more common case of few elements
2364 // faster.
2365 Instruction *MemRuntimeCheck;
2366 std::tie(FirstCheckInst, MemRuntimeCheck) =
2367 addRuntimeCheck(LastBypassBlock->getTerminator());
2368 if (MemRuntimeCheck) {
2369 // Create a new block containing the memory check.
2370 BasicBlock *CheckBlock =
2371 LastBypassBlock->splitBasicBlock(MemRuntimeCheck, "vector.memcheck");
2372 if (ParentLoop)
2373 ParentLoop->addBasicBlockToLoop(CheckBlock, LI->getBase());
2374 LoopBypassBlocks.push_back(CheckBlock);
2375
2376 // Replace the branch into the memory check block with a conditional branch
2377 // for the "few elements case".
2378 Instruction *OldTerm = LastBypassBlock->getTerminator();
2379 BranchInst::Create(MiddleBlock, CheckBlock, Cmp, OldTerm);
2380 OldTerm->eraseFromParent();
2381
2382 Cmp = MemRuntimeCheck;
2383 LastBypassBlock = CheckBlock;
2384 }
2385
2386 LastBypassBlock->getTerminator()->eraseFromParent();
2387 BranchInst::Create(MiddleBlock, VectorPH, Cmp,
2388 LastBypassBlock);
2389
2390 // We are going to resume the execution of the scalar loop.
2391 // Go over all of the induction variables that we found and fix the
2392 // PHIs that are left in the scalar version of the loop.
2393 // The starting values of PHI nodes depend on the counter of the last
2394 // iteration in the vectorized loop.
2395 // If we come from a bypass edge then we need to start from the original
2396 // start value.
2397
2398 // This variable saves the new starting index for the scalar loop.
2399 PHINode *ResumeIndex = nullptr;
2400 LoopVectorizationLegality::InductionList::iterator I, E;
2401 LoopVectorizationLegality::InductionList *List = Legal->getInductionVars();
2402 // Set builder to point to last bypass block.
2403 BypassBuilder.SetInsertPoint(LoopBypassBlocks.back()->getTerminator());
2404 for (I = List->begin(), E = List->end(); I != E; ++I) {
2405 PHINode *OrigPhi = I->first;
2406 LoopVectorizationLegality::InductionInfo II = I->second;
2407
2408 Type *ResumeValTy = (OrigPhi == OldInduction) ? IdxTy : OrigPhi->getType();
2409 PHINode *ResumeVal = PHINode::Create(ResumeValTy, 2, "resume.val",
2410 MiddleBlock->getTerminator());
2411 // We might have extended the type of the induction variable but we need a
2412 // truncated version for the scalar loop.
2413 PHINode *TruncResumeVal = (OrigPhi == OldInduction) ?
2414 PHINode::Create(OrigPhi->getType(), 2, "trunc.resume.val",
2415 MiddleBlock->getTerminator()) : nullptr;
2416
2417 // Create phi nodes to merge from the backedge-taken check block.
2418 PHINode *BCResumeVal = PHINode::Create(ResumeValTy, 3, "bc.resume.val",
2419 ScalarPH->getTerminator());
2420 BCResumeVal->addIncoming(ResumeVal, MiddleBlock);
2421
2422 PHINode *BCTruncResumeVal = nullptr;
2423 if (OrigPhi == OldInduction) {
2424 BCTruncResumeVal =
2425 PHINode::Create(OrigPhi->getType(), 2, "bc.trunc.resume.val",
2426 ScalarPH->getTerminator());
2427 BCTruncResumeVal->addIncoming(TruncResumeVal, MiddleBlock);
2428 }
2429
2430 Value *EndValue = nullptr;
2431 switch (II.IK) {
2432 case LoopVectorizationLegality::IK_NoInduction:
2433 llvm_unreachable("Unknown induction")::llvm::llvm_unreachable_internal("Unknown induction", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2433)
;
2434 case LoopVectorizationLegality::IK_IntInduction: {
2435 // Handle the integer induction counter.
2436 assert(OrigPhi->getType()->isIntegerTy() && "Invalid type")((OrigPhi->getType()->isIntegerTy() && "Invalid type"
) ? static_cast<void> (0) : __assert_fail ("OrigPhi->getType()->isIntegerTy() && \"Invalid type\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2436, __PRETTY_FUNCTION__))
;
2437
2438 // We have the canonical induction variable.
2439 if (OrigPhi == OldInduction) {
2440 // Create a truncated version of the resume value for the scalar loop,
2441 // we might have promoted the type to a larger width.
2442 EndValue =
2443 BypassBuilder.CreateTrunc(IdxEndRoundDown, OrigPhi->getType());
2444 // The new PHI merges the original incoming value, in case of a bypass,
2445 // or the value at the end of the vectorized loop.
2446 for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I)
2447 TruncResumeVal->addIncoming(II.StartValue, LoopBypassBlocks[I]);
2448 TruncResumeVal->addIncoming(EndValue, VecBody);
2449
2450 BCTruncResumeVal->addIncoming(II.StartValue, LoopBypassBlocks[0]);
2451
2452 // We know what the end value is.
2453 EndValue = IdxEndRoundDown;
2454 // We also know which PHI node holds it.
2455 ResumeIndex = ResumeVal;
2456 break;
2457 }
2458
2459 // Not the canonical induction variable - add the vector loop count to the
2460 // start value.
2461 Value *CRD = BypassBuilder.CreateSExtOrTrunc(CountRoundDown,
2462 II.StartValue->getType(),
2463 "cast.crd");
2464 EndValue = BypassBuilder.CreateAdd(CRD, II.StartValue , "ind.end");
2465 break;
2466 }
2467 case LoopVectorizationLegality::IK_ReverseIntInduction: {
2468 // Convert the CountRoundDown variable to the PHI size.
2469 Value *CRD = BypassBuilder.CreateSExtOrTrunc(CountRoundDown,
2470 II.StartValue->getType(),
2471 "cast.crd");
2472 // Handle reverse integer induction counter.
2473 EndValue = BypassBuilder.CreateSub(II.StartValue, CRD, "rev.ind.end");
2474 break;
2475 }
2476 case LoopVectorizationLegality::IK_PtrInduction: {
2477 // For pointer induction variables, calculate the offset using
2478 // the end index.
2479 EndValue = BypassBuilder.CreateGEP(II.StartValue, CountRoundDown,
2480 "ptr.ind.end");
2481 break;
2482 }
2483 case LoopVectorizationLegality::IK_ReversePtrInduction: {
2484 // The value at the end of the loop for the reverse pointer is calculated
2485 // by creating a GEP with a negative index starting from the start value.
2486 Value *Zero = ConstantInt::get(CountRoundDown->getType(), 0);
2487 Value *NegIdx = BypassBuilder.CreateSub(Zero, CountRoundDown,
2488 "rev.ind.end");
2489 EndValue = BypassBuilder.CreateGEP(II.StartValue, NegIdx,
2490 "rev.ptr.ind.end");
2491 break;
2492 }
2493 }// end of case
2494
2495 // The new PHI merges the original incoming value, in case of a bypass,
2496 // or the value at the end of the vectorized loop.
2497 for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I) {
2498 if (OrigPhi == OldInduction)
2499 ResumeVal->addIncoming(StartIdx, LoopBypassBlocks[I]);
2500 else
2501 ResumeVal->addIncoming(II.StartValue, LoopBypassBlocks[I]);
2502 }
2503 ResumeVal->addIncoming(EndValue, VecBody);
2504
2505 // Fix the scalar body counter (PHI node).
2506 unsigned BlockIdx = OrigPhi->getBasicBlockIndex(ScalarPH);
2507
2508 // The old induction's phi node in the scalar body needs the truncated
2509 // value.
2510 if (OrigPhi == OldInduction) {
2511 BCResumeVal->addIncoming(StartIdx, LoopBypassBlocks[0]);
2512 OrigPhi->setIncomingValue(BlockIdx, BCTruncResumeVal);
2513 } else {
2514 BCResumeVal->addIncoming(II.StartValue, LoopBypassBlocks[0]);
2515 OrigPhi->setIncomingValue(BlockIdx, BCResumeVal);
2516 }
2517 }
2518
2519 // If we are generating a new induction variable then we also need to
2520 // generate the code that calculates the exit value. This value is not
2521 // simply the end of the counter because we may skip the vectorized body
2522 // in case of a runtime check.
2523 if (!OldInduction){
2524 assert(!ResumeIndex && "Unexpected resume value found")((!ResumeIndex && "Unexpected resume value found") ? static_cast
<void> (0) : __assert_fail ("!ResumeIndex && \"Unexpected resume value found\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2524, __PRETTY_FUNCTION__))
;
2525 ResumeIndex = PHINode::Create(IdxTy, 2, "new.indc.resume.val",
2526 MiddleBlock->getTerminator());
2527 for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I)
2528 ResumeIndex->addIncoming(StartIdx, LoopBypassBlocks[I]);
2529 ResumeIndex->addIncoming(IdxEndRoundDown, VecBody);
2530 }
2531
2532 // Make sure that we found the index where scalar loop needs to continue.
2533 assert(ResumeIndex && ResumeIndex->getType()->isIntegerTy() &&((ResumeIndex && ResumeIndex->getType()->isIntegerTy
() && "Invalid resume Index") ? static_cast<void>
(0) : __assert_fail ("ResumeIndex && ResumeIndex->getType()->isIntegerTy() && \"Invalid resume Index\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2534, __PRETTY_FUNCTION__))
2534 "Invalid resume Index")((ResumeIndex && ResumeIndex->getType()->isIntegerTy
() && "Invalid resume Index") ? static_cast<void>
(0) : __assert_fail ("ResumeIndex && ResumeIndex->getType()->isIntegerTy() && \"Invalid resume Index\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2534, __PRETTY_FUNCTION__))
;
2535
2536 // Add a check in the middle block to see if we have completed
2537 // all of the iterations in the first vector loop.
2538 // If (N - N%VF) == N, then we *don't* need to run the remainder.
2539 Value *CmpN = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ, IdxEnd,
2540 ResumeIndex, "cmp.n",
2541 MiddleBlock->getTerminator());
2542
2543 BranchInst::Create(ExitBlock, ScalarPH, CmpN, MiddleBlock->getTerminator());
2544 // Remove the old terminator.
2545 MiddleBlock->getTerminator()->eraseFromParent();
2546
2547 // Create i+1 and fill the PHINode.
2548 Value *NextIdx = Builder.CreateAdd(Induction, Step, "index.next");
2549 Induction->addIncoming(StartIdx, VectorPH);
2550 Induction->addIncoming(NextIdx, VecBody);
2551 // Create the compare.
2552 Value *ICmp = Builder.CreateICmpEQ(NextIdx, IdxEndRoundDown);
2553 Builder.CreateCondBr(ICmp, MiddleBlock, VecBody);
2554
2555 // Now we have two terminators. Remove the old one from the block.
2556 VecBody->getTerminator()->eraseFromParent();
2557
2558 // Get ready to start creating new instructions into the vectorized body.
2559 Builder.SetInsertPoint(VecBody->getFirstInsertionPt());
2560
2561 // Save the state.
2562 LoopVectorPreHeader = VectorPH;
2563 LoopScalarPreHeader = ScalarPH;
2564 LoopMiddleBlock = MiddleBlock;
2565 LoopExitBlock = ExitBlock;
2566 LoopVectorBody.push_back(VecBody);
2567 LoopScalarBody = OldBasicBlock;
2568
2569 LoopVectorizeHints Hints(Lp, true);
2570 Hints.setAlreadyVectorized();
2571}
2572
2573/// This function returns the identity element (or neutral element) for
2574/// the operation K.
2575Constant*
2576LoopVectorizationLegality::getReductionIdentity(ReductionKind K, Type *Tp) {
2577 switch (K) {
2578 case RK_IntegerXor:
2579 case RK_IntegerAdd:
2580 case RK_IntegerOr:
2581 // Adding, Xoring, Oring zero to a number does not change it.
2582 return ConstantInt::get(Tp, 0);
2583 case RK_IntegerMult:
2584 // Multiplying a number by 1 does not change it.
2585 return ConstantInt::get(Tp, 1);
2586 case RK_IntegerAnd:
2587 // AND-ing a number with an all-1 value does not change it.
2588 return ConstantInt::get(Tp, -1, true);
2589 case RK_FloatMult:
2590 // Multiplying a number by 1 does not change it.
2591 return ConstantFP::get(Tp, 1.0L);
2592 case RK_FloatAdd:
2593 // Adding zero to a number does not change it.
2594 return ConstantFP::get(Tp, 0.0L);
2595 default:
2596 llvm_unreachable("Unknown reduction kind")::llvm::llvm_unreachable_internal("Unknown reduction kind", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2596)
;
2597 }
2598}
2599
2600/// This function translates the reduction kind to an LLVM binary operator.
2601static unsigned
2602getReductionBinOp(LoopVectorizationLegality::ReductionKind Kind) {
2603 switch (Kind) {
2604 case LoopVectorizationLegality::RK_IntegerAdd:
2605 return Instruction::Add;
2606 case LoopVectorizationLegality::RK_IntegerMult:
2607 return Instruction::Mul;
2608 case LoopVectorizationLegality::RK_IntegerOr:
2609 return Instruction::Or;
2610 case LoopVectorizationLegality::RK_IntegerAnd:
2611 return Instruction::And;
2612 case LoopVectorizationLegality::RK_IntegerXor:
2613 return Instruction::Xor;
2614 case LoopVectorizationLegality::RK_FloatMult:
2615 return Instruction::FMul;
2616 case LoopVectorizationLegality::RK_FloatAdd:
2617 return Instruction::FAdd;
2618 case LoopVectorizationLegality::RK_IntegerMinMax:
2619 return Instruction::ICmp;
2620 case LoopVectorizationLegality::RK_FloatMinMax:
2621 return Instruction::FCmp;
2622 default:
2623 llvm_unreachable("Unknown reduction operation")::llvm::llvm_unreachable_internal("Unknown reduction operation"
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2623)
;
2624 }
2625}
2626
2627Value *createMinMaxOp(IRBuilder<> &Builder,
2628 LoopVectorizationLegality::MinMaxReductionKind RK,
2629 Value *Left,
2630 Value *Right) {
2631 CmpInst::Predicate P = CmpInst::ICMP_NE;
2632 switch (RK) {
2633 default:
2634 llvm_unreachable("Unknown min/max reduction kind")::llvm::llvm_unreachable_internal("Unknown min/max reduction kind"
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2634)
;
2635 case LoopVectorizationLegality::MRK_UIntMin:
2636 P = CmpInst::ICMP_ULT;
2637 break;
2638 case LoopVectorizationLegality::MRK_UIntMax:
2639 P = CmpInst::ICMP_UGT;
2640 break;
2641 case LoopVectorizationLegality::MRK_SIntMin:
2642 P = CmpInst::ICMP_SLT;
2643 break;
2644 case LoopVectorizationLegality::MRK_SIntMax:
2645 P = CmpInst::ICMP_SGT;
2646 break;
2647 case LoopVectorizationLegality::MRK_FloatMin:
2648 P = CmpInst::FCMP_OLT;
2649 break;
2650 case LoopVectorizationLegality::MRK_FloatMax:
2651 P = CmpInst::FCMP_OGT;
2652 break;
2653 }
2654
2655 Value *Cmp;
2656 if (RK == LoopVectorizationLegality::MRK_FloatMin ||
2657 RK == LoopVectorizationLegality::MRK_FloatMax)
2658 Cmp = Builder.CreateFCmp(P, Left, Right, "rdx.minmax.cmp");
2659 else
2660 Cmp = Builder.CreateICmp(P, Left, Right, "rdx.minmax.cmp");
2661
2662 Value *Select = Builder.CreateSelect(Cmp, Left, Right, "rdx.minmax.select");
2663 return Select;
2664}
2665
2666namespace {
2667struct CSEDenseMapInfo {
2668 static bool canHandle(Instruction *I) {
2669 return isa<InsertElementInst>(I) || isa<ExtractElementInst>(I) ||
2670 isa<ShuffleVectorInst>(I) || isa<GetElementPtrInst>(I);
2671 }
2672 static inline Instruction *getEmptyKey() {
2673 return DenseMapInfo<Instruction *>::getEmptyKey();
2674 }
2675 static inline Instruction *getTombstoneKey() {
2676 return DenseMapInfo<Instruction *>::getTombstoneKey();
2677 }
2678 static unsigned getHashValue(Instruction *I) {
2679 assert(canHandle(I) && "Unknown instruction!")((canHandle(I) && "Unknown instruction!") ? static_cast
<void> (0) : __assert_fail ("canHandle(I) && \"Unknown instruction!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2679, __PRETTY_FUNCTION__))
;
2680 return hash_combine(I->getOpcode(), hash_combine_range(I->value_op_begin(),
2681 I->value_op_end()));
2682 }
2683 static bool isEqual(Instruction *LHS, Instruction *RHS) {
2684 if (LHS == getEmptyKey() || RHS == getEmptyKey() ||
2685 LHS == getTombstoneKey() || RHS == getTombstoneKey())
2686 return LHS == RHS;
2687 return LHS->isIdenticalTo(RHS);
2688 }
2689};
2690}
2691
2692/// \brief Check whether this block is a predicated block.
2693/// Due to if predication of stores we might create a sequence of "if(pred) a[i]
2694/// = ...; " blocks. We start with one vectorized basic block. For every
2695/// conditional block we split this vectorized block. Therefore, every second
2696/// block will be a predicated one.
2697static bool isPredicatedBlock(unsigned BlockNum) {
2698 return BlockNum % 2;
2699}
2700
2701///\brief Perform cse of induction variable instructions.
2702static void cse(SmallVector<BasicBlock *, 4> &BBs) {
2703 // Perform simple cse.
2704 SmallDenseMap<Instruction *, Instruction *, 4, CSEDenseMapInfo> CSEMap;
2705 for (unsigned i = 0, e = BBs.size(); i != e; ++i) {
2706 BasicBlock *BB = BBs[i];
2707 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
2708 Instruction *In = I++;
2709
2710 if (!CSEDenseMapInfo::canHandle(In))
2711 continue;
2712
2713 // Check if we can replace this instruction with any of the
2714 // visited instructions.
2715 if (Instruction *V = CSEMap.lookup(In)) {
2716 In->replaceAllUsesWith(V);
2717 In->eraseFromParent();
2718 continue;
2719 }
2720 // Ignore instructions in conditional blocks. We create "if (pred) a[i] =
2721 // ...;" blocks for predicated stores. Every second block is a predicated
2722 // block.
2723 if (isPredicatedBlock(i))
2724 continue;
2725
2726 CSEMap[In] = In;
2727 }
2728 }
2729}
2730
2731/// \brief Adds a 'fast' flag to floating point operations.
2732static Value *addFastMathFlag(Value *V) {
2733 if (isa<FPMathOperator>(V)){
2734 FastMathFlags Flags;
2735 Flags.setUnsafeAlgebra();
2736 cast<Instruction>(V)->setFastMathFlags(Flags);
2737 }
2738 return V;
2739}
2740
2741void InnerLoopVectorizer::vectorizeLoop() {
2742 //===------------------------------------------------===//
2743 //
2744 // Notice: any optimization or new instruction that go
2745 // into the code below should be also be implemented in
2746 // the cost-model.
2747 //
2748 //===------------------------------------------------===//
2749 Constant *Zero = Builder.getInt32(0);
2750
2751 // In order to support reduction variables we need to be able to vectorize
2752 // Phi nodes. Phi nodes have cycles, so we need to vectorize them in two
2753 // stages. First, we create a new vector PHI node with no incoming edges.
2754 // We use this value when we vectorize all of the instructions that use the
2755 // PHI. Next, after all of the instructions in the block are complete we
2756 // add the new incoming edges to the PHI. At this point all of the
2757 // instructions in the basic block are vectorized, so we can use them to
2758 // construct the PHI.
2759 PhiVector RdxPHIsToFix;
2760
2761 // Scan the loop in a topological order to ensure that defs are vectorized
2762 // before users.
2763 LoopBlocksDFS DFS(OrigLoop);
2764 DFS.perform(LI);
2765
2766 // Vectorize all of the blocks in the original loop.
2767 for (LoopBlocksDFS::RPOIterator bb = DFS.beginRPO(),
2768 be = DFS.endRPO(); bb != be; ++bb)
2769 vectorizeBlockInLoop(*bb, &RdxPHIsToFix);
2770
2771 // At this point every instruction in the original loop is widened to
2772 // a vector form. We are almost done. Now, we need to fix the PHI nodes
2773 // that we vectorized. The PHI nodes are currently empty because we did
2774 // not want to introduce cycles. Notice that the remaining PHI nodes
2775 // that we need to fix are reduction variables.
2776
2777 // Create the 'reduced' values for each of the induction vars.
2778 // The reduced values are the vector values that we scalarize and combine
2779 // after the loop is finished.
2780 for (PhiVector::iterator it = RdxPHIsToFix.begin(), e = RdxPHIsToFix.end();
2781 it != e; ++it) {
2782 PHINode *RdxPhi = *it;
2783 assert(RdxPhi && "Unable to recover vectorized PHI")((RdxPhi && "Unable to recover vectorized PHI") ? static_cast
<void> (0) : __assert_fail ("RdxPhi && \"Unable to recover vectorized PHI\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2783, __PRETTY_FUNCTION__))
;
2784
2785 // Find the reduction variable descriptor.
2786 assert(Legal->getReductionVars()->count(RdxPhi) &&((Legal->getReductionVars()->count(RdxPhi) && "Unable to find the reduction variable"
) ? static_cast<void> (0) : __assert_fail ("Legal->getReductionVars()->count(RdxPhi) && \"Unable to find the reduction variable\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2787, __PRETTY_FUNCTION__))
2787 "Unable to find the reduction variable")((Legal->getReductionVars()->count(RdxPhi) && "Unable to find the reduction variable"
) ? static_cast<void> (0) : __assert_fail ("Legal->getReductionVars()->count(RdxPhi) && \"Unable to find the reduction variable\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2787, __PRETTY_FUNCTION__))
;
2788 LoopVectorizationLegality::ReductionDescriptor RdxDesc =
2789 (*Legal->getReductionVars())[RdxPhi];
2790
2791 setDebugLocFromInst(Builder, RdxDesc.StartValue);
2792
2793 // We need to generate a reduction vector from the incoming scalar.
2794 // To do so, we need to generate the 'identity' vector and override
2795 // one of the elements with the incoming scalar reduction. We need
2796 // to do it in the vector-loop preheader.
2797 Builder.SetInsertPoint(LoopBypassBlocks[1]->getTerminator());
2798
2799 // This is the vector-clone of the value that leaves the loop.
2800 VectorParts &VectorExit = getVectorValue(RdxDesc.LoopExitInstr);
2801 Type *VecTy = VectorExit[0]->getType();
2802
2803 // Find the reduction identity variable. Zero for addition, or, xor,
2804 // one for multiplication, -1 for And.
2805 Value *Identity;
2806 Value *VectorStart;
2807 if (RdxDesc.Kind == LoopVectorizationLegality::RK_IntegerMinMax ||
2808 RdxDesc.Kind == LoopVectorizationLegality::RK_FloatMinMax) {
2809 // MinMax reduction have the start value as their identify.
2810 if (VF == 1) {
2811 VectorStart = Identity = RdxDesc.StartValue;
2812 } else {
2813 VectorStart = Identity = Builder.CreateVectorSplat(VF,
2814 RdxDesc.StartValue,
2815 "minmax.ident");
2816 }
2817 } else {
2818 // Handle other reduction kinds:
2819 Constant *Iden =
2820 LoopVectorizationLegality::getReductionIdentity(RdxDesc.Kind,
2821 VecTy->getScalarType());
2822 if (VF == 1) {
2823 Identity = Iden;
2824 // This vector is the Identity vector where the first element is the
2825 // incoming scalar reduction.
2826 VectorStart = RdxDesc.StartValue;
2827 } else {
2828 Identity = ConstantVector::getSplat(VF, Iden);
2829
2830 // This vector is the Identity vector where the first element is the
2831 // incoming scalar reduction.
2832 VectorStart = Builder.CreateInsertElement(Identity,
2833 RdxDesc.StartValue, Zero);
2834 }
2835 }
2836
2837 // Fix the vector-loop phi.
2838 // We created the induction variable so we know that the
2839 // preheader is the first entry.
2840 BasicBlock *VecPreheader = Induction->getIncomingBlock(0);
2841
2842 // Reductions do not have to start at zero. They can start with
2843 // any loop invariant values.
2844 VectorParts &VecRdxPhi = WidenMap.get(RdxPhi);
2845 BasicBlock *Latch = OrigLoop->getLoopLatch();
2846 Value *LoopVal = RdxPhi->getIncomingValueForBlock(Latch);
2847 VectorParts &Val = getVectorValue(LoopVal);
2848 for (unsigned part = 0; part < UF; ++part) {
2849 // Make sure to add the reduction stat value only to the
2850 // first unroll part.
2851 Value *StartVal = (part == 0) ? VectorStart : Identity;
2852 cast<PHINode>(VecRdxPhi[part])->addIncoming(StartVal, VecPreheader);
2853 cast<PHINode>(VecRdxPhi[part])->addIncoming(Val[part],
2854 LoopVectorBody.back());
2855 }
2856
2857 // Before each round, move the insertion point right between
2858 // the PHIs and the values we are going to write.
2859 // This allows us to write both PHINodes and the extractelement
2860 // instructions.
2861 Builder.SetInsertPoint(LoopMiddleBlock->getFirstInsertionPt());
2862
2863 VectorParts RdxParts;
2864 setDebugLocFromInst(Builder, RdxDesc.LoopExitInstr);
2865 for (unsigned part = 0; part < UF; ++part) {
2866 // This PHINode contains the vectorized reduction variable, or
2867 // the initial value vector, if we bypass the vector loop.
2868 VectorParts &RdxExitVal = getVectorValue(RdxDesc.LoopExitInstr);
2869 PHINode *NewPhi = Builder.CreatePHI(VecTy, 2, "rdx.vec.exit.phi");
2870 Value *StartVal = (part == 0) ? VectorStart : Identity;
2871 for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I)
2872 NewPhi->addIncoming(StartVal, LoopBypassBlocks[I]);
2873 NewPhi->addIncoming(RdxExitVal[part],
2874 LoopVectorBody.back());
2875 RdxParts.push_back(NewPhi);
2876 }
2877
2878 // Reduce all of the unrolled parts into a single vector.
2879 Value *ReducedPartRdx = RdxParts[0];
2880 unsigned Op = getReductionBinOp(RdxDesc.Kind);
2881 setDebugLocFromInst(Builder, ReducedPartRdx);
2882 for (unsigned part = 1; part < UF; ++part) {
2883 if (Op != Instruction::ICmp && Op != Instruction::FCmp)
2884 // Floating point operations had to be 'fast' to enable the reduction.
2885 ReducedPartRdx = addFastMathFlag(
2886 Builder.CreateBinOp((Instruction::BinaryOps)Op, RdxParts[part],
2887 ReducedPartRdx, "bin.rdx"));
2888 else
2889 ReducedPartRdx = createMinMaxOp(Builder, RdxDesc.MinMaxKind,
2890 ReducedPartRdx, RdxParts[part]);
2891 }
2892
2893 if (VF > 1) {
2894 // VF is a power of 2 so we can emit the reduction using log2(VF) shuffles
2895 // and vector ops, reducing the set of values being computed by half each
2896 // round.
2897 assert(isPowerOf2_32(VF) &&((isPowerOf2_32(VF) && "Reduction emission only supported for pow2 vectors!"
) ? static_cast<void> (0) : __assert_fail ("isPowerOf2_32(VF) && \"Reduction emission only supported for pow2 vectors!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2898, __PRETTY_FUNCTION__))
2898 "Reduction emission only supported for pow2 vectors!")((isPowerOf2_32(VF) && "Reduction emission only supported for pow2 vectors!"
) ? static_cast<void> (0) : __assert_fail ("isPowerOf2_32(VF) && \"Reduction emission only supported for pow2 vectors!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2898, __PRETTY_FUNCTION__))
;
2899 Value *TmpVec = ReducedPartRdx;
2900 SmallVector<Constant*, 32> ShuffleMask(VF, nullptr);
2901 for (unsigned i = VF; i != 1; i >>= 1) {
2902 // Move the upper half of the vector to the lower half.
2903 for (unsigned j = 0; j != i/2; ++j)
2904 ShuffleMask[j] = Builder.getInt32(i/2 + j);
2905
2906 // Fill the rest of the mask with undef.
2907 std::fill(&ShuffleMask[i/2], ShuffleMask.end(),
2908 UndefValue::get(Builder.getInt32Ty()));
2909
2910 Value *Shuf =
2911 Builder.CreateShuffleVector(TmpVec,
2912 UndefValue::get(TmpVec->getType()),
2913 ConstantVector::get(ShuffleMask),
2914 "rdx.shuf");
2915
2916 if (Op != Instruction::ICmp && Op != Instruction::FCmp)
2917 // Floating point operations had to be 'fast' to enable the reduction.
2918 TmpVec = addFastMathFlag(Builder.CreateBinOp(
2919 (Instruction::BinaryOps)Op, TmpVec, Shuf, "bin.rdx"));
2920 else
2921 TmpVec = createMinMaxOp(Builder, RdxDesc.MinMaxKind, TmpVec, Shuf);
2922 }
2923
2924 // The result is in the first element of the vector.
2925 ReducedPartRdx = Builder.CreateExtractElement(TmpVec,
2926 Builder.getInt32(0));
2927 }
2928
2929 // Create a phi node that merges control-flow from the backedge-taken check
2930 // block and the middle block.
2931 PHINode *BCBlockPhi = PHINode::Create(RdxPhi->getType(), 2, "bc.merge.rdx",
2932 LoopScalarPreHeader->getTerminator());
2933 BCBlockPhi->addIncoming(RdxDesc.StartValue, LoopBypassBlocks[0]);
2934 BCBlockPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock);
2935
2936 // Now, we need to fix the users of the reduction variable
2937 // inside and outside of the scalar remainder loop.
2938 // We know that the loop is in LCSSA form. We need to update the
2939 // PHI nodes in the exit blocks.
2940 for (BasicBlock::iterator LEI = LoopExitBlock->begin(),
2941 LEE = LoopExitBlock->end(); LEI != LEE; ++LEI) {
2942 PHINode *LCSSAPhi = dyn_cast<PHINode>(LEI);
2943 if (!LCSSAPhi) break;
2944
2945 // All PHINodes need to have a single entry edge, or two if
2946 // we already fixed them.
2947 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2947, __PRETTY_FUNCTION__))
;
2948
2949 // We found our reduction value exit-PHI. Update it with the
2950 // incoming bypass edge.
2951 if (LCSSAPhi->getIncomingValue(0) == RdxDesc.LoopExitInstr) {
2952 // Add an edge coming from the bypass.
2953 LCSSAPhi->addIncoming(ReducedPartRdx, LoopMiddleBlock);
2954 break;
2955 }
2956 }// end of the LCSSA phi scan.
2957
2958 // Fix the scalar loop reduction variable with the incoming reduction sum
2959 // from the vector body and from the backedge value.
2960 int IncomingEdgeBlockIdx =
2961 (RdxPhi)->getBasicBlockIndex(OrigLoop->getLoopLatch());
2962 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2962, __PRETTY_FUNCTION__))
;
2963 // Pick the other block.
2964 int SelfEdgeBlockIdx = (IncomingEdgeBlockIdx ? 0 : 1);
2965 (RdxPhi)->setIncomingValue(SelfEdgeBlockIdx, BCBlockPhi);
2966 (RdxPhi)->setIncomingValue(IncomingEdgeBlockIdx, RdxDesc.LoopExitInstr);
2967 }// end of for each redux variable.
2968
2969 fixLCSSAPHIs();
2970
2971 // Remove redundant induction instructions.
2972 cse(LoopVectorBody);
2973}
2974
2975void InnerLoopVectorizer::fixLCSSAPHIs() {
2976 for (BasicBlock::iterator LEI = LoopExitBlock->begin(),
2977 LEE = LoopExitBlock->end(); LEI != LEE; ++LEI) {
2978 PHINode *LCSSAPhi = dyn_cast<PHINode>(LEI);
2979 if (!LCSSAPhi) break;
2980 if (LCSSAPhi->getNumIncomingValues() == 1)
2981 LCSSAPhi->addIncoming(UndefValue::get(LCSSAPhi->getType()),
2982 LoopMiddleBlock);
2983 }
2984}
2985
2986InnerLoopVectorizer::VectorParts
2987InnerLoopVectorizer::createEdgeMask(BasicBlock *Src, BasicBlock *Dst) {
2988 assert(std::find(pred_begin(Dst), pred_end(Dst), Src) != pred_end(Dst) &&((std::find(pred_begin(Dst), pred_end(Dst), Src) != pred_end(
Dst) && "Invalid edge") ? static_cast<void> (0)
: __assert_fail ("std::find(pred_begin(Dst), pred_end(Dst), Src) != pred_end(Dst) && \"Invalid edge\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2989, __PRETTY_FUNCTION__))
2989 "Invalid edge")((std::find(pred_begin(Dst), pred_end(Dst), Src) != pred_end(
Dst) && "Invalid edge") ? static_cast<void> (0)
: __assert_fail ("std::find(pred_begin(Dst), pred_end(Dst), Src) != pred_end(Dst) && \"Invalid edge\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 2989, __PRETTY_FUNCTION__))
;
2990
2991 // Look for cached value.
2992 std::pair<BasicBlock*, BasicBlock*> Edge(Src, Dst);
2993 EdgeMaskCache::iterator ECEntryIt = MaskCache.find(Edge);
2994 if (ECEntryIt != MaskCache.end())
2995 return ECEntryIt->second;
2996
2997 VectorParts SrcMask = createBlockInMask(Src);
2998
2999 // The terminator has to be a branch inst!
3000 BranchInst *BI = dyn_cast<BranchInst>(Src->getTerminator());
3001 assert(BI && "Unexpected terminator found")((BI && "Unexpected terminator found") ? static_cast<
void> (0) : __assert_fail ("BI && \"Unexpected terminator found\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3001, __PRETTY_FUNCTION__))
;
3002
3003 if (BI->isConditional()) {
3004 VectorParts EdgeMask = getVectorValue(BI->getCondition());
3005
3006 if (BI->getSuccessor(0) != Dst)
3007 for (unsigned part = 0; part < UF; ++part)
3008 EdgeMask[part] = Builder.CreateNot(EdgeMask[part]);
3009
3010 for (unsigned part = 0; part < UF; ++part)
3011 EdgeMask[part] = Builder.CreateAnd(EdgeMask[part], SrcMask[part]);
3012
3013 MaskCache[Edge] = EdgeMask;
3014 return EdgeMask;
3015 }
3016
3017 MaskCache[Edge] = SrcMask;
3018 return SrcMask;
3019}
3020
3021InnerLoopVectorizer::VectorParts
3022InnerLoopVectorizer::createBlockInMask(BasicBlock *BB) {
3023 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3023, __PRETTY_FUNCTION__))
;
3024
3025 // Loop incoming mask is all-one.
3026 if (OrigLoop->getHeader() == BB) {
3027 Value *C = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 1);
3028 return getVectorValue(C);
3029 }
3030
3031 // This is the block mask. We OR all incoming edges, and with zero.
3032 Value *Zero = ConstantInt::get(IntegerType::getInt1Ty(BB->getContext()), 0);
3033 VectorParts BlockMask = getVectorValue(Zero);
3034
3035 // For each pred:
3036 for (pred_iterator it = pred_begin(BB), e = pred_end(BB); it != e; ++it) {
3037 VectorParts EM = createEdgeMask(*it, BB);
3038 for (unsigned part = 0; part < UF; ++part)
3039 BlockMask[part] = Builder.CreateOr(BlockMask[part], EM[part]);
3040 }
3041
3042 return BlockMask;
3043}
3044
3045void InnerLoopVectorizer::widenPHIInstruction(Instruction *PN,
3046 InnerLoopVectorizer::VectorParts &Entry,
3047 unsigned UF, unsigned VF, PhiVector *PV) {
3048 PHINode* P = cast<PHINode>(PN);
3049 // Handle reduction variables:
3050 if (Legal->getReductionVars()->count(P)) {
3051 for (unsigned part = 0; part < UF; ++part) {
3052 // This is phase one of vectorizing PHIs.
3053 Type *VecTy = (VF == 1) ? PN->getType() :
3054 VectorType::get(PN->getType(), VF);
3055 Entry[part] = PHINode::Create(VecTy, 2, "vec.phi",
3056 LoopVectorBody.back()-> getFirstInsertionPt());
3057 }
3058 PV->push_back(P);
3059 return;
3060 }
3061
3062 setDebugLocFromInst(Builder, P);
3063 // Check for PHI nodes that are lowered to vector selects.
3064 if (P->getParent() != OrigLoop->getHeader()) {
3065 // We know that all PHIs in non-header blocks are converted into
3066 // selects, so we don't have to worry about the insertion order and we
3067 // can just use the builder.
3068 // At this point we generate the predication tree. There may be
3069 // duplications since this is a simple recursive scan, but future
3070 // optimizations will clean it up.
3071
3072 unsigned NumIncoming = P->getNumIncomingValues();
3073
3074 // Generate a sequence of selects of the form:
3075 // SELECT(Mask3, In3,
3076 // SELECT(Mask2, In2,
3077 // ( ...)))
3078 for (unsigned In = 0; In < NumIncoming; In++) {
3079 VectorParts Cond = createEdgeMask(P->getIncomingBlock(In),
3080 P->getParent());
3081 VectorParts &In0 = getVectorValue(P->getIncomingValue(In));
3082
3083 for (unsigned part = 0; part < UF; ++part) {
3084 // We might have single edge PHIs (blocks) - use an identity
3085 // 'select' for the first PHI operand.
3086 if (In == 0)
3087 Entry[part] = Builder.CreateSelect(Cond[part], In0[part],
3088 In0[part]);
3089 else
3090 // Select between the current value and the previous incoming edge
3091 // based on the incoming mask.
3092 Entry[part] = Builder.CreateSelect(Cond[part], In0[part],
3093 Entry[part], "predphi");
3094 }
3095 }
3096 return;
3097 }
3098
3099 // This PHINode must be an induction variable.
3100 // Make sure that we know about it.
3101 assert(Legal->getInductionVars()->count(P) &&((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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3102, __PRETTY_FUNCTION__))
3102 "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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3102, __PRETTY_FUNCTION__))
;
3103
3104 LoopVectorizationLegality::InductionInfo II =
3105 Legal->getInductionVars()->lookup(P);
3106
3107 switch (II.IK) {
3108 case LoopVectorizationLegality::IK_NoInduction:
3109 llvm_unreachable("Unknown induction")::llvm::llvm_unreachable_internal("Unknown induction", "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3109)
;
3110 case LoopVectorizationLegality::IK_IntInduction: {
3111 assert(P->getType() == II.StartValue->getType() && "Types must match")((P->getType() == II.StartValue->getType() && "Types must match"
) ? static_cast<void> (0) : __assert_fail ("P->getType() == II.StartValue->getType() && \"Types must match\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3111, __PRETTY_FUNCTION__))
;
3112 Type *PhiTy = P->getType();
3113 Value *Broadcasted;
3114 if (P == OldInduction) {
3115 // Handle the canonical induction variable. We might have had to
3116 // extend the type.
3117 Broadcasted = Builder.CreateTrunc(Induction, PhiTy);
3118 } else {
3119 // Handle other induction variables that are now based on the
3120 // canonical one.
3121 Value *NormalizedIdx = Builder.CreateSub(Induction, ExtendedIdx,
3122 "normalized.idx");
3123 NormalizedIdx = Builder.CreateSExtOrTrunc(NormalizedIdx, PhiTy);
3124 Broadcasted = Builder.CreateAdd(II.StartValue, NormalizedIdx,
3125 "offset.idx");
3126 }
3127 Broadcasted = getBroadcastInstrs(Broadcasted);
3128 // After broadcasting the induction variable we need to make the vector
3129 // consecutive by adding 0, 1, 2, etc.
3130 for (unsigned part = 0; part < UF; ++part)
3131 Entry[part] = getConsecutiveVector(Broadcasted, VF * part, false);
3132 return;
3133 }
3134 case LoopVectorizationLegality::IK_ReverseIntInduction:
3135 case LoopVectorizationLegality::IK_PtrInduction:
3136 case LoopVectorizationLegality::IK_ReversePtrInduction:
3137 // Handle reverse integer and pointer inductions.
3138 Value *StartIdx = ExtendedIdx;
3139 // This is the normalized GEP that starts counting at zero.
3140 Value *NormalizedIdx = Builder.CreateSub(Induction, StartIdx,
3141 "normalized.idx");
3142
3143 // Handle the reverse integer induction variable case.
3144 if (LoopVectorizationLegality::IK_ReverseIntInduction == II.IK) {
3145 IntegerType *DstTy = cast<IntegerType>(II.StartValue->getType());
3146 Value *CNI = Builder.CreateSExtOrTrunc(NormalizedIdx, DstTy,
3147 "resize.norm.idx");
3148 Value *ReverseInd = Builder.CreateSub(II.StartValue, CNI,
3149 "reverse.idx");
3150
3151 // This is a new value so do not hoist it out.
3152 Value *Broadcasted = getBroadcastInstrs(ReverseInd);
3153 // After broadcasting the induction variable we need to make the
3154 // vector consecutive by adding ... -3, -2, -1, 0.
3155 for (unsigned part = 0; part < UF; ++part)
3156 Entry[part] = getConsecutiveVector(Broadcasted, -(int)VF * part,
3157 true);
3158 return;
3159 }
3160
3161 // Handle the pointer induction variable case.
3162 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3162, __PRETTY_FUNCTION__))
;
3163
3164 // Is this a reverse induction ptr or a consecutive induction ptr.
3165 bool Reverse = (LoopVectorizationLegality::IK_ReversePtrInduction ==
3166 II.IK);
3167
3168 // This is the vector of results. Notice that we don't generate
3169 // vector geps because scalar geps result in better code.
3170 for (unsigned part = 0; part < UF; ++part) {
3171 if (VF == 1) {
3172 int EltIndex = (part) * (Reverse ? -1 : 1);
3173 Constant *Idx = ConstantInt::get(Induction->getType(), EltIndex);
3174 Value *GlobalIdx;
3175 if (Reverse)
3176 GlobalIdx = Builder.CreateSub(Idx, NormalizedIdx, "gep.ridx");
3177 else
3178 GlobalIdx = Builder.CreateAdd(NormalizedIdx, Idx, "gep.idx");
3179
3180 Value *SclrGep = Builder.CreateGEP(II.StartValue, GlobalIdx,
3181 "next.gep");
3182 Entry[part] = SclrGep;
3183 continue;
3184 }
3185
3186 Value *VecVal = UndefValue::get(VectorType::get(P->getType(), VF));
3187 for (unsigned int i = 0; i < VF; ++i) {
3188 int EltIndex = (i + part * VF) * (Reverse ? -1 : 1);
3189 Constant *Idx = ConstantInt::get(Induction->getType(), EltIndex);
3190 Value *GlobalIdx;
3191 if (!Reverse)
3192 GlobalIdx = Builder.CreateAdd(NormalizedIdx, Idx, "gep.idx");
3193 else
3194 GlobalIdx = Builder.CreateSub(Idx, NormalizedIdx, "gep.ridx");
3195
3196 Value *SclrGep = Builder.CreateGEP(II.StartValue, GlobalIdx,
3197 "next.gep");
3198 VecVal = Builder.CreateInsertElement(VecVal, SclrGep,
3199 Builder.getInt32(i),
3200 "insert.gep");
3201 }
3202 Entry[part] = VecVal;
3203 }
3204 return;
3205 }
3206}
3207
3208void InnerLoopVectorizer::vectorizeBlockInLoop(BasicBlock *BB, PhiVector *PV) {
3209 // For each instruction in the old loop.
3210 for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
3211 VectorParts &Entry = WidenMap.get(it);
3212 switch (it->getOpcode()) {
3213 case Instruction::Br:
3214 // Nothing to do for PHIs and BR, since we already took care of the
3215 // loop control flow instructions.
3216 continue;
3217 case Instruction::PHI:{
3218 // Vectorize PHINodes.
3219 widenPHIInstruction(it, Entry, UF, VF, PV);
3220 continue;
3221 }// End of PHI.
3222
3223 case Instruction::Add:
3224 case Instruction::FAdd:
3225 case Instruction::Sub:
3226 case Instruction::FSub:
3227 case Instruction::Mul:
3228 case Instruction::FMul:
3229 case Instruction::UDiv:
3230 case Instruction::SDiv:
3231 case Instruction::FDiv:
3232 case Instruction::URem:
3233 case Instruction::SRem:
3234 case Instruction::FRem:
3235 case Instruction::Shl:
3236 case Instruction::LShr:
3237 case Instruction::AShr:
3238 case Instruction::And:
3239 case Instruction::Or:
3240 case Instruction::Xor: {
3241 // Just widen binops.
3242 BinaryOperator *BinOp = dyn_cast<BinaryOperator>(it);
3243 setDebugLocFromInst(Builder, BinOp);
3244 VectorParts &A = getVectorValue(it->getOperand(0));
3245 VectorParts &B = getVectorValue(it->getOperand(1));
3246
3247 // Use this vector value for all users of the original instruction.
3248 for (unsigned Part = 0; Part < UF; ++Part) {
3249 Value *V = Builder.CreateBinOp(BinOp->getOpcode(), A[Part], B[Part]);
3250
3251 if (BinaryOperator *VecOp = dyn_cast<BinaryOperator>(V))
3252 VecOp->copyIRFlags(BinOp);
3253
3254 Entry[Part] = V;
3255 }
3256
3257 propagateMetadata(Entry, it);
3258 break;
3259 }
3260 case Instruction::Select: {
3261 // Widen selects.
3262 // If the selector is loop invariant we can create a select
3263 // instruction with a scalar condition. Otherwise, use vector-select.
3264 bool InvariantCond = SE->isLoopInvariant(SE->getSCEV(it->getOperand(0)),
3265 OrigLoop);
3266 setDebugLocFromInst(Builder, it);
3267
3268 // The condition can be loop invariant but still defined inside the
3269 // loop. This means that we can't just use the original 'cond' value.
3270 // We have to take the 'vectorized' value and pick the first lane.
3271 // Instcombine will make this a no-op.
3272 VectorParts &Cond = getVectorValue(it->getOperand(0));
3273 VectorParts &Op0 = getVectorValue(it->getOperand(1));
3274 VectorParts &Op1 = getVectorValue(it->getOperand(2));
3275
3276 Value *ScalarCond = (VF == 1) ? Cond[0] :
3277 Builder.CreateExtractElement(Cond[0], Builder.getInt32(0));
3278
3279 for (unsigned Part = 0; Part < UF; ++Part) {
3280 Entry[Part] = Builder.CreateSelect(
3281 InvariantCond ? ScalarCond : Cond[Part],
3282 Op0[Part],
3283 Op1[Part]);
3284 }
3285
3286 propagateMetadata(Entry, it);
3287 break;
3288 }
3289
3290 case Instruction::ICmp:
3291 case Instruction::FCmp: {
3292 // Widen compares. Generate vector compares.
3293 bool FCmp = (it->getOpcode() == Instruction::FCmp);
3294 CmpInst *Cmp = dyn_cast<CmpInst>(it);
3295 setDebugLocFromInst(Builder, it);
3296 VectorParts &A = getVectorValue(it->getOperand(0));
3297 VectorParts &B = getVectorValue(it->getOperand(1));
3298 for (unsigned Part = 0; Part < UF; ++Part) {
3299 Value *C = nullptr;
3300 if (FCmp)
3301 C = Builder.CreateFCmp(Cmp->getPredicate(), A[Part], B[Part]);
3302 else
3303 C = Builder.CreateICmp(Cmp->getPredicate(), A[Part], B[Part]);
3304 Entry[Part] = C;
3305 }
3306
3307 propagateMetadata(Entry, it);
3308 break;
3309 }
3310
3311 case Instruction::Store:
3312 case Instruction::Load:
3313 vectorizeMemoryInstruction(it);
3314 break;
3315 case Instruction::ZExt:
3316 case Instruction::SExt:
3317 case Instruction::FPToUI:
3318 case Instruction::FPToSI:
3319 case Instruction::FPExt:
3320 case Instruction::PtrToInt:
3321 case Instruction::IntToPtr:
3322 case Instruction::SIToFP:
3323 case Instruction::UIToFP:
3324 case Instruction::Trunc:
3325 case Instruction::FPTrunc:
3326 case Instruction::BitCast: {
3327 CastInst *CI = dyn_cast<CastInst>(it);
3328 setDebugLocFromInst(Builder, it);
3329 /// Optimize the special case where the source is the induction
3330 /// variable. Notice that we can only optimize the 'trunc' case
3331 /// because: a. FP conversions lose precision, b. sext/zext may wrap,
3332 /// c. other casts depend on pointer size.
3333 if (CI->getOperand(0) == OldInduction &&
3334 it->getOpcode() == Instruction::Trunc) {
3335 Value *ScalarCast = Builder.CreateCast(CI->getOpcode(), Induction,
3336 CI->getType());
3337 Value *Broadcasted = getBroadcastInstrs(ScalarCast);
3338 for (unsigned Part = 0; Part < UF; ++Part)
3339 Entry[Part] = getConsecutiveVector(Broadcasted, VF * Part, false);
3340 propagateMetadata(Entry, it);
3341 break;
3342 }
3343 /// Vectorize casts.
3344 Type *DestTy = (VF == 1) ? CI->getType() :
3345 VectorType::get(CI->getType(), VF);
3346
3347 VectorParts &A = getVectorValue(it->getOperand(0));
3348 for (unsigned Part = 0; Part < UF; ++Part)
3349 Entry[Part] = Builder.CreateCast(CI->getOpcode(), A[Part], DestTy);
3350 propagateMetadata(Entry, it);
3351 break;
3352 }
3353
3354 case Instruction::Call: {
3355 // Ignore dbg intrinsics.
3356 if (isa<DbgInfoIntrinsic>(it))
3357 break;
3358 setDebugLocFromInst(Builder, it);
3359
3360 Module *M = BB->getParent()->getParent();
3361 CallInst *CI = cast<CallInst>(it);
3362 Intrinsic::ID ID = getIntrinsicIDForCall(CI, TLI);
3363 assert(ID && "Not an intrinsic call!")((ID && "Not an intrinsic call!") ? static_cast<void
> (0) : __assert_fail ("ID && \"Not an intrinsic call!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3363, __PRETTY_FUNCTION__))
;
3364 switch (ID) {
3365 case Intrinsic::lifetime_end:
3366 case Intrinsic::lifetime_start:
3367 scalarizeInstruction(it);
3368 break;
3369 default:
3370 bool HasScalarOpd = hasVectorInstrinsicScalarOpd(ID, 1);
3371 for (unsigned Part = 0; Part < UF; ++Part) {
3372 SmallVector<Value *, 4> Args;
3373 for (unsigned i = 0, ie = CI->getNumArgOperands(); i != ie; ++i) {
3374 if (HasScalarOpd && i == 1) {
3375 Args.push_back(CI->getArgOperand(i));
3376 continue;
3377 }
3378 VectorParts &Arg = getVectorValue(CI->getArgOperand(i));
3379 Args.push_back(Arg[Part]);
3380 }
3381 Type *Tys[] = {CI->getType()};
3382 if (VF > 1)
3383 Tys[0] = VectorType::get(CI->getType()->getScalarType(), VF);
3384
3385 Function *F = Intrinsic::getDeclaration(M, ID, Tys);
3386 Entry[Part] = Builder.CreateCall(F, Args);
3387 }
3388
3389 propagateMetadata(Entry, it);
3390 break;
3391 }
3392 break;
3393 }
3394
3395 default:
3396 // All other instructions are unsupported. Scalarize them.
3397 scalarizeInstruction(it);
3398 break;
3399 }// end of switch.
3400 }// end of for_each instr.
3401}
3402
3403void InnerLoopVectorizer::updateAnalysis() {
3404 // Forget the original basic block.
3405 SE->forgetLoop(OrigLoop);
3406
3407 // Update the dominator tree information.
3408 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3409, __PRETTY_FUNCTION__))
3409 "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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3409, __PRETTY_FUNCTION__))
;
3410
3411 for (unsigned I = 1, E = LoopBypassBlocks.size(); I != E; ++I)
3412 DT->addNewBlock(LoopBypassBlocks[I], LoopBypassBlocks[I-1]);
3413 DT->addNewBlock(LoopVectorPreHeader, LoopBypassBlocks.back());
3414
3415 // Due to if predication of stores we might create a sequence of "if(pred)
3416 // a[i] = ...; " blocks.
3417 for (unsigned i = 0, e = LoopVectorBody.size(); i != e; ++i) {
3418 if (i == 0)
3419 DT->addNewBlock(LoopVectorBody[0], LoopVectorPreHeader);
3420 else if (isPredicatedBlock(i)) {
3421 DT->addNewBlock(LoopVectorBody[i], LoopVectorBody[i-1]);
3422 } else {
3423 DT->addNewBlock(LoopVectorBody[i], LoopVectorBody[i-2]);
3424 }
3425 }
3426
3427 DT->addNewBlock(LoopMiddleBlock, LoopBypassBlocks[1]);
3428 DT->addNewBlock(LoopScalarPreHeader, LoopBypassBlocks[0]);
3429 DT->changeImmediateDominator(LoopScalarBody, LoopScalarPreHeader);
3430 DT->changeImmediateDominator(LoopExitBlock, LoopMiddleBlock);
3431
3432 DEBUG(DT->verifyDomTree())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { DT->verifyDomTree(); } } while (0)
;
3433}
3434
3435/// \brief Check whether it is safe to if-convert this phi node.
3436///
3437/// Phi nodes with constant expressions that can trap are not safe to if
3438/// convert.
3439static bool canIfConvertPHINodes(BasicBlock *BB) {
3440 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
3441 PHINode *Phi = dyn_cast<PHINode>(I);
3442 if (!Phi)
3443 return true;
3444 for (unsigned p = 0, e = Phi->getNumIncomingValues(); p != e; ++p)
3445 if (Constant *C = dyn_cast<Constant>(Phi->getIncomingValue(p)))
3446 if (C->canTrap())
3447 return false;
3448 }
3449 return true;
3450}
3451
3452bool LoopVectorizationLegality::canVectorizeWithIfConvert() {
3453 if (!EnableIfConversion) {
3454 emitAnalysis(Report() << "if-conversion is disabled");
3455 return false;
3456 }
3457
3458 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 3458, __PRETTY_FUNCTION__))
;
3459
3460 // A list of pointers that we can safely read and write to.
3461 SmallPtrSet<Value *, 8> SafePointes;
3462
3463 // Collect safe addresses.
3464 for (Loop::block_iterator BI = TheLoop->block_begin(),
3465 BE = TheLoop->block_end(); BI != BE; ++BI) {
3466 BasicBlock *BB = *BI;
3467
3468 if (blockNeedsPredication(BB))
3469 continue;
3470
3471 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
3472 if (LoadInst *LI = dyn_cast<LoadInst>(I))
3473 SafePointes.insert(LI->getPointerOperand());
3474 else if (StoreInst *SI = dyn_cast<StoreInst>(I))
3475 SafePointes.insert(SI->getPointerOperand());
3476 }
3477 }
3478
3479 // Collect the blocks that need predication.
3480 BasicBlock *Header = TheLoop->getHeader();
3481 for (Loop::block_iterator BI = TheLoop->block_begin(),
3482 BE = TheLoop->block_end(); BI != BE; ++BI) {
3483 BasicBlock *BB = *BI;
3484
3485 // We don't support switch statements inside loops.
3486 if (!isa<BranchInst>(BB->getTerminator())) {
3487 emitAnalysis(Report(BB->getTerminator())
3488 << "loop contains a switch statement");
3489 return false;
3490 }
3491
3492 // We must be able to predicate all blocks that need to be predicated.
3493 if (blockNeedsPredication(BB)) {
3494 if (!blockCanBePredicated(BB, SafePointes)) {
3495 emitAnalysis(Report(BB->getTerminator())
3496 << "control flow cannot be substituted for a select");
3497 return false;
3498 }
3499 } else if (BB != Header && !canIfConvertPHINodes(BB)) {
3500 emitAnalysis(Report(BB->getTerminator())
3501 << "control flow cannot be substituted for a select");
3502 return false;
3503 }
3504 }
3505
3506 // We can if-convert this loop.
3507 return true;
3508}
3509
3510bool LoopVectorizationLegality::canVectorize() {
3511 // We must have a loop in canonical form. Loops with indirectbr in them cannot
3512 // be canonicalized.
3513 if (!TheLoop->getLoopPreheader()) {
3514 emitAnalysis(
3515 Report() << "loop control flow is not understood by vectorizer");
3516 return false;
3517 }
3518
3519 // We can only vectorize innermost loops.
3520 if (TheLoop->getSubLoopsVector().size()) {
3521 emitAnalysis(Report() << "loop is not the innermost loop");
3522 return false;
3523 }
3524
3525 // We must have a single backedge.
3526 if (TheLoop->getNumBackEdges() != 1) {
3527 emitAnalysis(
3528 Report() << "loop control flow is not understood by vectorizer");
3529 return false;
3530 }
3531
3532 // We must have a single exiting block.
3533 if (!TheLoop->getExitingBlock()) {
3534 emitAnalysis(
3535 Report() << "loop control flow is not understood by vectorizer");
3536 return false;
3537 }
3538
3539 // We need to have a loop header.
3540 DEBUG(dbgs() << "LV: Found a loop: " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a loop: " <<
TheLoop->getHeader()->getName() << '\n'; } } while
(0)
3541 TheLoop->getHeader()->getName() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a loop: " <<
TheLoop->getHeader()->getName() << '\n'; } } while
(0)
;
3542
3543 // Check if we can if-convert non-single-bb loops.
3544 unsigned NumBlocks = TheLoop->getNumBlocks();
3545 if (NumBlocks != 1 && !canVectorizeWithIfConvert()) {
3546 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 (0)
;
3547 return false;
3548 }
3549
3550 // ScalarEvolution needs to be able to find the exit count.
3551 const SCEV *ExitCount = SE->getBackedgeTakenCount(TheLoop);
3552 if (ExitCount == SE->getCouldNotCompute()) {
3553 emitAnalysis(Report() << "could not determine number of loop iterations");
3554 DEBUG(dbgs() << "LV: SCEV could not compute the loop exit count.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: SCEV could not compute the loop exit count.\n"
; } } while (0)
;
3555 return false;
3556 }
3557
3558 // Check if we can vectorize the instructions and CFG in this loop.
3559 if (!canVectorizeInstrs()) {
3560 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 (0)
;
3561 return false;
3562 }
3563
3564 // Go over each instruction and look at memory deps.
3565 if (!canVectorizeMemory()) {
3566 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 (0)
;
3567 return false;
3568 }
3569
3570 // Collect all of the variables that remain uniform after vectorization.
3571 collectLoopUniforms();
3572
3573 DEBUG(dbgs() << "LV: We can vectorize this loop" <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can vectorize this loop"
<< (PtrRtCheck.Need ? " (with a runtime bound check)" :
"") <<"!\n"; } } while (0)
3574 (PtrRtCheck.Need ? " (with a runtime bound check)" : "")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can vectorize this loop"
<< (PtrRtCheck.Need ? " (with a runtime bound check)" :
"") <<"!\n"; } } while (0)
3575 <<"!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can vectorize this loop"
<< (PtrRtCheck.Need ? " (with a runtime bound check)" :
"") <<"!\n"; } } while (0)
;
3576
3577 // Okay! We can vectorize. At this point we don't have any other mem analysis
3578 // which may limit our maximum vectorization factor, so just return true with
3579 // no restrictions.
3580 return true;
3581}
3582
3583static Type *convertPointerToIntegerType(const DataLayout &DL, Type *Ty) {
3584 if (Ty->isPointerTy())
3585 return DL.getIntPtrType(Ty);
3586
3587 // It is possible that char's or short's overflow when we ask for the loop's
3588 // trip count, work around this by changing the type size.
3589 if (Ty->getScalarSizeInBits() < 32)
3590 return Type::getInt32Ty(Ty->getContext());
3591
3592 return Ty;
3593}
3594
3595static Type* getWiderType(const DataLayout &DL, Type *Ty0, Type *Ty1) {
3596 Ty0 = convertPointerToIntegerType(DL, Ty0);
3597 Ty1 = convertPointerToIntegerType(DL, Ty1);
3598 if (Ty0->getScalarSizeInBits() > Ty1->getScalarSizeInBits())
3599 return Ty0;
3600 return Ty1;
3601}
3602
3603/// \brief Check that the instruction has outside loop users and is not an
3604/// identified reduction variable.
3605static bool hasOutsideLoopUser(const Loop *TheLoop, Instruction *Inst,
3606 SmallPtrSetImpl<Value *> &Reductions) {
3607 // Reduction instructions are allowed to have exit users. All other
3608 // instructions must not have external users.
3609 if (!Reductions.count(Inst))
3610 //Check that all of the users of the loop are inside the BB.
3611 for (User *U : Inst->users()) {
3612 Instruction *UI = cast<Instruction>(U);
3613 // This user may be a reduction exit value.
3614 if (!TheLoop->contains(UI)) {
3615 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 (0)
;
3616 return true;
3617 }
3618 }
3619 return false;
3620}
3621
3622bool LoopVectorizationLegality::canVectorizeInstrs() {
3623 BasicBlock *PreHeader = TheLoop->getLoopPreheader();
3624 BasicBlock *Header = TheLoop->getHeader();
3625
3626 // Look for the attribute signaling the absence of NaNs.
3627 Function &F = *Header->getParent();
3628 if (F.hasFnAttribute("no-nans-fp-math"))
3629 HasFunNoNaNAttr = F.getAttributes().getAttribute(
3630 AttributeSet::FunctionIndex,
3631 "no-nans-fp-math").getValueAsString() == "true";
3632
3633 // For each block in the loop.
3634 for (Loop::block_iterator bb = TheLoop->block_begin(),
3635 be = TheLoop->block_end(); bb != be; ++bb) {
3636
3637 // Scan the instructions in the block and look for hazards.
3638 for (BasicBlock::iterator it = (*bb)->begin(), e = (*bb)->end(); it != e;
3639 ++it) {
3640
3641 if (PHINode *Phi = dyn_cast<PHINode>(it)) {
3642 Type *PhiTy = Phi->getType();
3643 // Check that this PHI type is allowed.
3644 if (!PhiTy->isIntegerTy() &&
3645 !PhiTy->isFloatingPointTy() &&
3646 !PhiTy->isPointerTy()) {
3647 emitAnalysis(Report(it)
3648 << "loop control flow is not understood by vectorizer");
3649 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 (0)
;
3650 return false;
3651 }
3652
3653 // If this PHINode is not in the header block, then we know that we
3654 // can convert it to select during if-conversion. No need to check if
3655 // the PHIs in this block are induction or reduction variables.
3656 if (*bb != Header) {
3657 // Check that this instruction has no outside users or is an
3658 // identified reduction value with an outside user.
3659 if (!hasOutsideLoopUser(TheLoop, it, AllowedExit))
3660 continue;
3661 emitAnalysis(Report(it) << "value could not be identified as "
3662 "an induction or reduction variable");
3663 return false;
3664 }
3665
3666 // We only allow if-converted PHIs with more than two incoming values.
3667 if (Phi->getNumIncomingValues() != 2) {
3668 emitAnalysis(Report(it)
3669 << "control flow not understood by vectorizer");
3670 DEBUG(dbgs() << "LV: Found an invalid PHI.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an invalid PHI.\n"
; } } while (0)
;
3671 return false;
3672 }
3673
3674 // This is the value coming from the preheader.
3675 Value *StartValue = Phi->getIncomingValueForBlock(PreHeader);
3676 // Check if this is an induction variable.
3677 InductionKind IK = isInductionVariable(Phi);
3678
3679 if (IK_NoInduction != IK) {
3680 // Get the widest type.
3681 if (!WidestIndTy)
3682 WidestIndTy = convertPointerToIntegerType(*DL, PhiTy);
3683 else
3684 WidestIndTy = getWiderType(*DL, PhiTy, WidestIndTy);
3685
3686 // Int inductions are special because we only allow one IV.
3687 if (IK == IK_IntInduction) {
3688 // Use the phi node with the widest type as induction. Use the last
3689 // one if there are multiple (no good reason for doing this other
3690 // than it is expedient).
3691 if (!Induction || PhiTy == WidestIndTy)
3692 Induction = Phi;
3693 }
3694
3695 DEBUG(dbgs() << "LV: Found an induction variable.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an induction variable.\n"
; } } while (0)
;
3696 Inductions[Phi] = InductionInfo(StartValue, IK);
3697
3698 // Until we explicitly handle the case of an induction variable with
3699 // an outside loop user we have to give up vectorizing this loop.
3700 if (hasOutsideLoopUser(TheLoop, it, AllowedExit)) {
3701 emitAnalysis(Report(it) << "use of induction value outside of the "
3702 "loop is not handled by vectorizer");
3703 return false;
3704 }
3705
3706 continue;
3707 }
3708
3709 if (AddReductionVar(Phi, RK_IntegerAdd)) {
3710 DEBUG(dbgs() << "LV: Found an ADD reduction PHI."<< *Phi <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an ADD reduction PHI."
<< *Phi <<"\n"; } } while (0)
;
3711 continue;
3712 }
3713 if (AddReductionVar(Phi, RK_IntegerMult)) {
3714 DEBUG(dbgs() << "LV: Found a MUL reduction PHI."<< *Phi <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a MUL reduction PHI."
<< *Phi <<"\n"; } } while (0)
;
3715 continue;
3716 }
3717 if (AddReductionVar(Phi, RK_IntegerOr)) {
3718 DEBUG(dbgs() << "LV: Found an OR reduction PHI."<< *Phi <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an OR reduction PHI."
<< *Phi <<"\n"; } } while (0)
;
3719 continue;
3720 }
3721 if (AddReductionVar(Phi, RK_IntegerAnd)) {
3722 DEBUG(dbgs() << "LV: Found an AND reduction PHI."<< *Phi <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an AND reduction PHI."
<< *Phi <<"\n"; } } while (0)
;
3723 continue;
3724 }
3725 if (AddReductionVar(Phi, RK_IntegerXor)) {
3726 DEBUG(dbgs() << "LV: Found a XOR reduction PHI."<< *Phi <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a XOR reduction PHI."
<< *Phi <<"\n"; } } while (0)
;
3727 continue;
3728 }
3729 if (AddReductionVar(Phi, RK_IntegerMinMax)) {
3730 DEBUG(dbgs() << "LV: Found a MINMAX reduction PHI."<< *Phi <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a MINMAX reduction PHI."
<< *Phi <<"\n"; } } while (0)
;
3731 continue;
3732 }
3733 if (AddReductionVar(Phi, RK_FloatMult)) {
3734 DEBUG(dbgs() << "LV: Found an FMult reduction PHI."<< *Phi <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an FMult reduction PHI."
<< *Phi <<"\n"; } } while (0)
;
3735 continue;
3736 }
3737 if (AddReductionVar(Phi, RK_FloatAdd)) {
3738 DEBUG(dbgs() << "LV: Found an FAdd reduction PHI."<< *Phi <<"\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an FAdd reduction PHI."
<< *Phi <<"\n"; } } while (0)
;
3739 continue;
3740 }
3741 if (AddReductionVar(Phi, RK_FloatMinMax)) {
3742 DEBUG(dbgs() << "LV: Found an float MINMAX reduction PHI."<< *Phi <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an float MINMAX reduction PHI."
<< *Phi << "\n"; } } while (0)
3743 "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an float MINMAX reduction PHI."
<< *Phi << "\n"; } } while (0)
;
3744 continue;
3745 }
3746
3747 emitAnalysis(Report(it) << "value that could not be identified as "
3748 "reduction is used outside the loop");
3749 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 (0)
;
3750 return false;
3751 }// end of PHI handling
3752
3753 // We still don't handle functions. However, we can ignore dbg intrinsic
3754 // calls and we do handle certain intrinsic and libm functions.
3755 CallInst *CI = dyn_cast<CallInst>(it);
3756 if (CI && !getIntrinsicIDForCall(CI, TLI) && !isa<DbgInfoIntrinsic>(CI)) {
3757 emitAnalysis(Report(it) << "call instruction cannot be vectorized");
3758 DEBUG(dbgs() << "LV: Found a call site.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a call site.\n"
; } } while (0)
;
3759 return false;
3760 }
3761
3762 // Intrinsics such as powi,cttz and ctlz are legal to vectorize if the
3763 // second argument is the same (i.e. loop invariant)
3764 if (CI &&
3765 hasVectorInstrinsicScalarOpd(getIntrinsicIDForCall(CI, TLI), 1)) {
3766 if (!SE->isLoopInvariant(SE->getSCEV(CI->getOperand(1)), TheLoop)) {
3767 emitAnalysis(Report(it)
3768 << "intrinsic instruction cannot be vectorized");
3769 DEBUG(dbgs() << "LV: Found unvectorizable intrinsic " << *CI << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found unvectorizable intrinsic "
<< *CI << "\n"; } } while (0)
;
3770 return false;
3771 }
3772 }
3773
3774 // Check that the instruction return type is vectorizable.
3775 // Also, we can't vectorize extractelement instructions.
3776 if ((!VectorType::isValidElementType(it->getType()) &&
3777 !it->getType()->isVoidTy()) || isa<ExtractElementInst>(it)) {
3778 emitAnalysis(Report(it)
3779 << "instruction return type cannot be vectorized");
3780 DEBUG(dbgs() << "LV: Found unvectorizable type.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found unvectorizable type.\n"
; } } while (0)
;
3781 return false;
3782 }
3783
3784 // Check that the stored type is vectorizable.
3785 if (StoreInst *ST = dyn_cast<StoreInst>(it)) {
3786 Type *T = ST->getValueOperand()->getType();
3787 if (!VectorType::isValidElementType(T)) {
3788 emitAnalysis(Report(ST) << "store instruction cannot be vectorized");
3789 return false;
3790 }
3791 if (EnableMemAccessVersioning)
3792 collectStridedAcccess(ST);
3793 }
3794
3795 if (EnableMemAccessVersioning)
3796 if (LoadInst *LI = dyn_cast<LoadInst>(it))
3797 collectStridedAcccess(LI);
3798
3799 // Reduction instructions are allowed to have exit users.
3800 // All other instructions must not have external users.
3801 if (hasOutsideLoopUser(TheLoop, it, AllowedExit)) {
3802 emitAnalysis(Report(it) << "value cannot be used outside the loop");
3803 return false;
3804 }
3805
3806 } // next instr.
3807
3808 }
3809
3810 if (!Induction) {
3811 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 (0)
;
3812 if (Inductions.empty()) {
3813 emitAnalysis(Report()
3814 << "loop induction variable could not be identified");
3815 return false;
3816 }
3817 }
3818
3819 return true;
3820}
3821
3822///\brief Remove GEPs whose indices but the last one are loop invariant and
3823/// return the induction operand of the gep pointer.
3824static Value *stripGetElementPtr(Value *Ptr, ScalarEvolution *SE,
3825 const DataLayout *DL, Loop *Lp) {
3826 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr);
3827 if (!GEP)
3828 return Ptr;
3829
3830 unsigned InductionOperand = getGEPInductionOperand(DL, GEP);
3831
3832 // Check that all of the gep indices are uniform except for our induction
3833 // operand.
3834 for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i)
3835 if (i != InductionOperand &&
3836 !SE->isLoopInvariant(SE->getSCEV(GEP->getOperand(i)), Lp))
3837 return Ptr;
3838 return GEP->getOperand(InductionOperand);
3839}
3840
3841///\brief Look for a cast use of the passed value.
3842static Value *getUniqueCastUse(Value *Ptr, Loop *Lp, Type *Ty) {
3843 Value *UniqueCast = nullptr;
3844 for (User *U : Ptr->users()) {
3845 CastInst *CI = dyn_cast<CastInst>(U);
3846 if (CI && CI->getType() == Ty) {
3847 if (!UniqueCast)
3848 UniqueCast = CI;
3849 else
3850 return nullptr;
3851 }
3852 }
3853 return UniqueCast;
3854}
3855
3856///\brief Get the stride of a pointer access in a loop.
3857/// Looks for symbolic strides "a[i*stride]". Returns the symbolic stride as a
3858/// pointer to the Value, or null otherwise.
3859static Value *getStrideFromPointer(Value *Ptr, ScalarEvolution *SE,
3860 const DataLayout *DL, Loop *Lp) {
3861 const PointerType *PtrTy = dyn_cast<PointerType>(Ptr->getType());
3862 if (!PtrTy || PtrTy->isAggregateType())
3863 return nullptr;
3864
3865 // Try to remove a gep instruction to make the pointer (actually index at this
3866 // point) easier analyzable. If OrigPtr is equal to Ptr we are analzying the
3867 // pointer, otherwise, we are analyzing the index.
3868 Value *OrigPtr = Ptr;
3869
3870 // The size of the pointer access.
3871 int64_t PtrAccessSize = 1;
3872
3873 Ptr = stripGetElementPtr(Ptr, SE, DL, Lp);
3874 const SCEV *V = SE->getSCEV(Ptr);
3875
3876 if (Ptr != OrigPtr)
3877 // Strip off casts.
3878 while (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V))
3879 V = C->getOperand();
3880
3881 const SCEVAddRecExpr *S = dyn_cast<SCEVAddRecExpr>(V);
3882 if (!S)
3883 return nullptr;
3884
3885 V = S->getStepRecurrence(*SE);
3886 if (!V)
3887 return nullptr;
3888
3889 // Strip off the size of access multiplication if we are still analyzing the
3890 // pointer.
3891 if (OrigPtr == Ptr) {
3892 DL->getTypeAllocSize(PtrTy->getElementType());
3893 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(V)) {
3894 if (M->getOperand(0)->getSCEVType() != scConstant)
3895 return nullptr;
3896
3897 const APInt &APStepVal =
3898 cast<SCEVConstant>(M->getOperand(0))->getValue()->getValue();
3899
3900 // Huge step value - give up.
3901 if (APStepVal.getBitWidth() > 64)
3902 return nullptr;
3903
3904 int64_t StepVal = APStepVal.getSExtValue();
3905 if (PtrAccessSize != StepVal)
3906 return nullptr;
3907 V = M->getOperand(1);
3908 }
3909 }
3910
3911 // Strip off casts.
3912 Type *StripedOffRecurrenceCast = nullptr;
3913 if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V)) {
3914 StripedOffRecurrenceCast = C->getType();
3915 V = C->getOperand();
3916 }
3917
3918 // Look for the loop invariant symbolic value.
3919 const SCEVUnknown *U = dyn_cast<SCEVUnknown>(V);
3920 if (!U)
3921 return nullptr;
3922
3923 Value *Stride = U->getValue();
3924 if (!Lp->isLoopInvariant(Stride))
3925 return nullptr;
3926
3927 // If we have stripped off the recurrence cast we have to make sure that we
3928 // return the value that is used in this loop so that we can replace it later.
3929 if (StripedOffRecurrenceCast)
3930 Stride = getUniqueCastUse(Stride, Lp, StripedOffRecurrenceCast);
3931
3932 return Stride;
3933}
3934
3935void LoopVectorizationLegality::collectStridedAcccess(Value *MemAccess) {
3936 Value *Ptr = nullptr;
3937 if (LoadInst *LI = dyn_cast<LoadInst>(MemAccess))
3938 Ptr = LI->getPointerOperand();
3939 else if (StoreInst *SI = dyn_cast<StoreInst>(MemAccess))
3940 Ptr = SI->getPointerOperand();
3941 else
3942 return;
3943
3944 Value *Stride = getStrideFromPointer(Ptr, SE, DL, TheLoop);
3945 if (!Stride)
3946 return;
3947
3948 DEBUG(dbgs() << "LV: Found a strided access that we can version")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a strided access that we can version"
; } } while (0)
;
3949 DEBUG(dbgs() << " Ptr: " << *Ptr << " Stride: " << *Stride << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << " Ptr: " << *Ptr
<< " Stride: " << *Stride << "\n"; } } while
(0)
;
3950 Strides[Ptr] = Stride;
3951 StrideSet.insert(Stride);
3952}
3953
3954void LoopVectorizationLegality::collectLoopUniforms() {
3955 // We now know that the loop is vectorizable!
3956 // Collect variables that will remain uniform after vectorization.
3957 std::vector<Value*> Worklist;
3958 BasicBlock *Latch = TheLoop->getLoopLatch();
3959
3960 // Start with the conditional branch and walk up the block.
3961 Worklist.push_back(Latch->getTerminator()->getOperand(0));
3962
3963 // Also add all consecutive pointer values; these values will be uniform
3964 // after vectorization (and subsequent cleanup) and, until revectorization is
3965 // supported, all dependencies must also be uniform.
3966 for (Loop::block_iterator B = TheLoop->block_begin(),
3967 BE = TheLoop->block_end(); B != BE; ++B)
3968 for (BasicBlock::iterator I = (*B)->begin(), IE = (*B)->end();
3969 I != IE; ++I)
3970 if (I->getType()->isPointerTy() && isConsecutivePtr(I))
3971 Worklist.insert(Worklist.end(), I->op_begin(), I->op_end());
3972
3973 while (Worklist.size()) {
3974 Instruction *I = dyn_cast<Instruction>(Worklist.back());
3975 Worklist.pop_back();
3976
3977 // Look at instructions inside this loop.
3978 // Stop when reaching PHI nodes.
3979 // TODO: we need to follow values all over the loop, not only in this block.
3980 if (!I || !TheLoop->contains(I) || isa<PHINode>(I))
3981 continue;
3982
3983 // This is a known uniform.
3984 Uniforms.insert(I);
3985
3986 // Insert all operands.
3987 Worklist.insert(Worklist.end(), I->op_begin(), I->op_end());
3988 }
3989}
3990
3991namespace {
3992/// \brief Analyses memory accesses in a loop.
3993///
3994/// Checks whether run time pointer checks are needed and builds sets for data
3995/// dependence checking.
3996class AccessAnalysis {
3997public:
3998 /// \brief Read or write access location.
3999 typedef PointerIntPair<Value *, 1, bool> MemAccessInfo;
4000 typedef SmallPtrSet<MemAccessInfo, 8> MemAccessInfoSet;
4001
4002 /// \brief Set of potential dependent memory accesses.
4003 typedef EquivalenceClasses<MemAccessInfo> DepCandidates;
4004
4005 AccessAnalysis(const DataLayout *Dl, AliasAnalysis *AA, DepCandidates &DA) :
4006 DL(Dl), AST(*AA), DepCands(DA), IsRTCheckNeeded(false) {}
4007
4008 /// \brief Register a load and whether it is only read from.
4009 void addLoad(AliasAnalysis::Location &Loc, bool IsReadOnly) {
4010 Value *Ptr = const_cast<Value*>(Loc.Ptr);
4011 AST.add(Ptr, AliasAnalysis::UnknownSize, Loc.AATags);
4012 Accesses.insert(MemAccessInfo(Ptr, false));
4013 if (IsReadOnly)
4014 ReadOnlyPtr.insert(Ptr);
4015 }
4016
4017 /// \brief Register a store.
4018 void addStore(AliasAnalysis::Location &Loc) {
4019 Value *Ptr = const_cast<Value*>(Loc.Ptr);
4020 AST.add(Ptr, AliasAnalysis::UnknownSize, Loc.AATags);
4021 Accesses.insert(MemAccessInfo(Ptr, true));
4022 }
4023
4024 /// \brief Check whether we can check the pointers at runtime for
4025 /// non-intersection.
4026 bool canCheckPtrAtRT(LoopVectorizationLegality::RuntimePointerCheck &RtCheck,
4027 unsigned &NumComparisons, ScalarEvolution *SE,
4028 Loop *TheLoop, ValueToValueMap &Strides,
4029 bool ShouldCheckStride = false);
4030
4031 /// \brief Goes over all memory accesses, checks whether a RT check is needed
4032 /// and builds sets of dependent accesses.
4033 void buildDependenceSets() {
4034 processMemAccesses();
4035 }
4036
4037 bool isRTCheckNeeded() { return IsRTCheckNeeded; }
4038
4039 bool isDependencyCheckNeeded() { return !CheckDeps.empty(); }
4040 void resetDepChecks() { CheckDeps.clear(); }
4041
4042 MemAccessInfoSet &getDependenciesToCheck() { return CheckDeps; }
4043
4044private:
4045 typedef SetVector<MemAccessInfo> PtrAccessSet;
4046
4047 /// \brief Go over all memory access and check whether runtime pointer checks
4048 /// are needed /// and build sets of dependency check candidates.
4049 void processMemAccesses();
4050
4051 /// Set of all accesses.
4052 PtrAccessSet Accesses;
4053
4054 /// Set of accesses that need a further dependence check.
4055 MemAccessInfoSet CheckDeps;
4056
4057 /// Set of pointers that are read only.
4058 SmallPtrSet<Value*, 16> ReadOnlyPtr;
4059
4060 const DataLayout *DL;
4061
4062 /// An alias set tracker to partition the access set by underlying object and
4063 //intrinsic property (such as TBAA metadata).
4064 AliasSetTracker AST;
4065
4066 /// Sets of potentially dependent accesses - members of one set share an
4067 /// underlying pointer. The set "CheckDeps" identfies which sets really need a
4068 /// dependence check.
4069 DepCandidates &DepCands;
4070
4071 bool IsRTCheckNeeded;
4072};
4073
4074} // end anonymous namespace
4075
4076/// \brief Check whether a pointer can participate in a runtime bounds check.
4077static bool hasComputableBounds(ScalarEvolution *SE, ValueToValueMap &Strides,
4078 Value *Ptr) {
4079 const SCEV *PtrScev = replaceSymbolicStrideSCEV(SE, Strides, Ptr);
4080 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PtrScev);
4081 if (!AR)
4082 return false;
4083
4084 return AR->isAffine();
4085}
4086
4087/// \brief Check the stride of the pointer and ensure that it does not wrap in
4088/// the address space.
4089static int isStridedPtr(ScalarEvolution *SE, const DataLayout *DL, Value *Ptr,
4090 const Loop *Lp, ValueToValueMap &StridesMap);
4091
4092bool AccessAnalysis::canCheckPtrAtRT(
4093 LoopVectorizationLegality::RuntimePointerCheck &RtCheck,
4094 unsigned &NumComparisons, ScalarEvolution *SE, Loop *TheLoop,
4095 ValueToValueMap &StridesMap, bool ShouldCheckStride) {
4096 // Find pointers with computable bounds. We are going to use this information
4097 // to place a runtime bound check.
4098 bool CanDoRT = true;
4099
4100 bool IsDepCheckNeeded = isDependencyCheckNeeded();
4101 NumComparisons = 0;
4102
4103 // We assign a consecutive id to access from different alias sets.
4104 // Accesses between different groups doesn't need to be checked.
4105 unsigned ASId = 1;
4106 for (auto &AS : AST) {
4107 unsigned NumReadPtrChecks = 0;
4108 unsigned NumWritePtrChecks = 0;
4109
4110 // We assign consecutive id to access from different dependence sets.
4111 // Accesses within the same set don't need a runtime check.
4112 unsigned RunningDepId = 1;
4113 DenseMap<Value *, unsigned> DepSetId;
4114
4115 for (auto A : AS) {
4116 Value *Ptr = A.getValue();
4117 bool IsWrite = Accesses.count(MemAccessInfo(Ptr, true));
4118 MemAccessInfo Access(Ptr, IsWrite);
4119
4120 if (IsWrite)
4121 ++NumWritePtrChecks;
4122 else
4123 ++NumReadPtrChecks;
4124
4125 if (hasComputableBounds(SE, StridesMap, Ptr) &&
4126 // When we run after a failing dependency check we have to make sure we
4127 // don't have wrapping pointers.
4128 (!ShouldCheckStride ||
4129 isStridedPtr(SE, DL, Ptr, TheLoop, StridesMap) == 1)) {
4130 // The id of the dependence set.
4131 unsigned DepId;
4132
4133 if (IsDepCheckNeeded) {
4134 Value *Leader = DepCands.getLeaderValue(Access).getPointer();
4135 unsigned &LeaderId = DepSetId[Leader];
4136 if (!LeaderId)
4137 LeaderId = RunningDepId++;
4138 DepId = LeaderId;
4139 } else
4140 // Each access has its own dependence set.
4141 DepId = RunningDepId++;
4142
4143 RtCheck.insert(SE, TheLoop, Ptr, IsWrite, DepId, ASId, StridesMap);
4144
4145 DEBUG(dbgs() << "LV: Found a runtime check ptr:" << *Ptr << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a runtime check ptr:"
<< *Ptr << '\n'; } } while (0)
;
4146 } else {
4147 CanDoRT = false;
4148 }
4149 }
4150
4151 if (IsDepCheckNeeded && CanDoRT && RunningDepId == 2)
4152 NumComparisons += 0; // Only one dependence set.
4153 else {
4154 NumComparisons += (NumWritePtrChecks * (NumReadPtrChecks +
4155 NumWritePtrChecks - 1));
4156 }
4157
4158 ++ASId;
4159 }
4160
4161 // If the pointers that we would use for the bounds comparison have different
4162 // address spaces, assume the values aren't directly comparable, so we can't
4163 // use them for the runtime check. We also have to assume they could
4164 // overlap. In the future there should be metadata for whether address spaces
4165 // are disjoint.
4166 unsigned NumPointers = RtCheck.Pointers.size();
4167 for (unsigned i = 0; i < NumPointers; ++i) {
4168 for (unsigned j = i + 1; j < NumPointers; ++j) {
4169 // Only need to check pointers between two different dependency sets.
4170 if (RtCheck.DependencySetId[i] == RtCheck.DependencySetId[j])
4171 continue;
4172 // Only need to check pointers in the same alias set.
4173 if (RtCheck.AliasSetId[i] != RtCheck.AliasSetId[j])
4174 continue;
4175
4176 Value *PtrI = RtCheck.Pointers[i];
4177 Value *PtrJ = RtCheck.Pointers[j];
4178
4179 unsigned ASi = PtrI->getType()->getPointerAddressSpace();
4180 unsigned ASj = PtrJ->getType()->getPointerAddressSpace();
4181 if (ASi != ASj) {
4182 DEBUG(dbgs() << "LV: Runtime check would require comparison between"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Runtime check would require comparison between"
" different address spaces\n"; } } while (0)
4183 " different address spaces\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Runtime check would require comparison between"
" different address spaces\n"; } } while (0)
;
4184 return false;
4185 }
4186 }
4187 }
4188
4189 return CanDoRT;
4190}
4191
4192void AccessAnalysis::processMemAccesses() {
4193 // We process the set twice: first we process read-write pointers, last we
4194 // process read-only pointers. This allows us to skip dependence tests for
4195 // read-only pointers.
4196
4197 DEBUG(dbgs() << "LV: Processing memory accesses...\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Processing memory accesses...\n"
; } } while (0)
;
4198 DEBUG(dbgs() << " AST: "; AST.dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << " AST: "; AST.dump(); }
} while (0)
;
4199 DEBUG(dbgs() << "LV: Accesses:\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Accesses:\n"; } }
while (0)
;
4200 DEBUG({do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { { for (auto A : Accesses) dbgs() <<
"\t" << *A.getPointer() << " (" << (A.getInt
() ? "write" : (ReadOnlyPtr.count(A.getPointer()) ? "read-only"
: "read")) << ")\n"; }; } } while (0)
4201 for (auto A : Accesses)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { { for (auto A : Accesses) dbgs() <<
"\t" << *A.getPointer() << " (" << (A.getInt
() ? "write" : (ReadOnlyPtr.count(A.getPointer()) ? "read-only"
: "read")) << ")\n"; }; } } while (0)
4202 dbgs() << "\t" << *A.getPointer() << " (" <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { { for (auto A : Accesses) dbgs() <<
"\t" << *A.getPointer() << " (" << (A.getInt
() ? "write" : (ReadOnlyPtr.count(A.getPointer()) ? "read-only"
: "read")) << ")\n"; }; } } while (0)
4203 (A.getInt() ? "write" : (ReadOnlyPtr.count(A.getPointer()) ?do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { { for (auto A : Accesses) dbgs() <<
"\t" << *A.getPointer() << " (" << (A.getInt
() ? "write" : (ReadOnlyPtr.count(A.getPointer()) ? "read-only"
: "read")) << ")\n"; }; } } while (0)
4204 "read-only" : "read")) << ")\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { { for (auto A : Accesses) dbgs() <<
"\t" << *A.getPointer() << " (" << (A.getInt
() ? "write" : (ReadOnlyPtr.count(A.getPointer()) ? "read-only"
: "read")) << ")\n"; }; } } while (0)
4205 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { { for (auto A : Accesses) dbgs() <<
"\t" << *A.getPointer() << " (" << (A.getInt
() ? "write" : (ReadOnlyPtr.count(A.getPointer()) ? "read-only"
: "read")) << ")\n"; }; } } while (0)
;
4206
4207 // The AliasSetTracker has nicely partitioned our pointers by metadata
4208 // compatibility and potential for underlying-object overlap. As a result, we
4209 // only need to check for potential pointer dependencies within each alias
4210 // set.
4211 for (auto &AS : AST) {
4212 // Note that both the alias-set tracker and the alias sets themselves used
4213 // linked lists internally and so the iteration order here is deterministic
4214 // (matching the original instruction order within each set).
4215
4216 bool SetHasWrite = false;
4217
4218 // Map of pointers to last access encountered.
4219 typedef DenseMap<Value*, MemAccessInfo> UnderlyingObjToAccessMap;
4220 UnderlyingObjToAccessMap ObjToLastAccess;
4221
4222 // Set of access to check after all writes have been processed.
4223 PtrAccessSet DeferredAccesses;
4224
4225 // Iterate over each alias set twice, once to process read/write pointers,
4226 // and then to process read-only pointers.
4227 for (int SetIteration = 0; SetIteration < 2; ++SetIteration) {
4228 bool UseDeferred = SetIteration > 0;
4229 PtrAccessSet &S = UseDeferred ? DeferredAccesses : Accesses;
4230
4231 for (auto A : AS) {
4232 Value *Ptr = A.getValue();
4233 bool IsWrite = S.count(MemAccessInfo(Ptr, true));
4234
4235 // If we're using the deferred access set, then it contains only reads.
4236 bool IsReadOnlyPtr = ReadOnlyPtr.count(Ptr) && !IsWrite;
4237 if (UseDeferred && !IsReadOnlyPtr)
4238 continue;
4239 // Otherwise, the pointer must be in the PtrAccessSet, either as a read
4240 // or a write.
4241 assert(((IsReadOnlyPtr && UseDeferred) || IsWrite ||((((IsReadOnlyPtr && UseDeferred) || IsWrite || S.count
(MemAccessInfo(Ptr, false))) && "Alias-set pointer not in the access set?"
) ? static_cast<void> (0) : __assert_fail ("((IsReadOnlyPtr && UseDeferred) || IsWrite || S.count(MemAccessInfo(Ptr, false))) && \"Alias-set pointer not in the access set?\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4243, __PRETTY_FUNCTION__))
4242 S.count(MemAccessInfo(Ptr, false))) &&((((IsReadOnlyPtr && UseDeferred) || IsWrite || S.count
(MemAccessInfo(Ptr, false))) && "Alias-set pointer not in the access set?"
) ? static_cast<void> (0) : __assert_fail ("((IsReadOnlyPtr && UseDeferred) || IsWrite || S.count(MemAccessInfo(Ptr, false))) && \"Alias-set pointer not in the access set?\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4243, __PRETTY_FUNCTION__))
4243 "Alias-set pointer not in the access set?")((((IsReadOnlyPtr && UseDeferred) || IsWrite || S.count
(MemAccessInfo(Ptr, false))) && "Alias-set pointer not in the access set?"
) ? static_cast<void> (0) : __assert_fail ("((IsReadOnlyPtr && UseDeferred) || IsWrite || S.count(MemAccessInfo(Ptr, false))) && \"Alias-set pointer not in the access set?\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4243, __PRETTY_FUNCTION__))
;
4244
4245 MemAccessInfo Access(Ptr, IsWrite);
4246 DepCands.insert(Access);
4247
4248 // Memorize read-only pointers for later processing and skip them in the
4249 // first round (they need to be checked after we have seen all write
4250 // pointers). Note: we also mark pointer that are not consecutive as
4251 // "read-only" pointers (so that we check "a[b[i]] +="). Hence, we need
4252 // the second check for "!IsWrite".
4253 if (!UseDeferred && IsReadOnlyPtr) {
4254 DeferredAccesses.insert(Access);
4255 continue;
4256 }
4257
4258 // If this is a write - check other reads and writes for conflicts. If
4259 // this is a read only check other writes for conflicts (but only if
4260 // there is no other write to the ptr - this is an optimization to
4261 // catch "a[i] = a[i] + " without having to do a dependence check).
4262 if ((IsWrite || IsReadOnlyPtr) && SetHasWrite) {
4263 CheckDeps.insert(Access);
4264 IsRTCheckNeeded = true;
4265 }
4266
4267 if (IsWrite)
4268 SetHasWrite = true;
4269
4270 // Create sets of pointers connected by a shared alias set and
4271 // underlying object.
4272 typedef SmallVector<Value*, 16> ValueVector;
4273 ValueVector TempObjects;
4274 GetUnderlyingObjects(Ptr, TempObjects, DL);
4275 for (Value *UnderlyingObj : TempObjects) {
4276 UnderlyingObjToAccessMap::iterator Prev =
4277 ObjToLastAccess.find(UnderlyingObj);
4278 if (Prev != ObjToLastAccess.end())
4279 DepCands.unionSets(Access, Prev->second);
4280
4281 ObjToLastAccess[UnderlyingObj] = Access;
4282 }
4283 }
4284 }
4285 }
4286}
4287
4288namespace {
4289/// \brief Checks memory dependences among accesses to the same underlying
4290/// object to determine whether there vectorization is legal or not (and at
4291/// which vectorization factor).
4292///
4293/// This class works under the assumption that we already checked that memory
4294/// locations with different underlying pointers are "must-not alias".
4295/// We use the ScalarEvolution framework to symbolically evalutate access
4296/// functions pairs. Since we currently don't restructure the loop we can rely
4297/// on the program order of memory accesses to determine their safety.
4298/// At the moment we will only deem accesses as safe for:
4299/// * A negative constant distance assuming program order.
4300///
4301/// Safe: tmp = a[i + 1]; OR a[i + 1] = x;
4302/// a[i] = tmp; y = a[i];
4303///
4304/// The latter case is safe because later checks guarantuee that there can't
4305/// be a cycle through a phi node (that is, we check that "x" and "y" is not
4306/// the same variable: a header phi can only be an induction or a reduction, a
4307/// reduction can't have a memory sink, an induction can't have a memory
4308/// source). This is important and must not be violated (or we have to
4309/// resort to checking for cycles through memory).
4310///
4311/// * A positive constant distance assuming program order that is bigger
4312/// than the biggest memory access.
4313///
4314/// tmp = a[i] OR b[i] = x
4315/// a[i+2] = tmp y = b[i+2];
4316///
4317/// Safe distance: 2 x sizeof(a[0]), and 2 x sizeof(b[0]), respectively.
4318///
4319/// * Zero distances and all accesses have the same size.
4320///
4321class MemoryDepChecker {
4322public:
4323 typedef PointerIntPair<Value *, 1, bool> MemAccessInfo;
4324 typedef SmallPtrSet<MemAccessInfo, 8> MemAccessInfoSet;
4325
4326 MemoryDepChecker(ScalarEvolution *Se, const DataLayout *Dl, const Loop *L)
4327 : SE(Se), DL(Dl), InnermostLoop(L), AccessIdx(0),
4328 ShouldRetryWithRuntimeCheck(false) {}
4329
4330 /// \brief Register the location (instructions are given increasing numbers)
4331 /// of a write access.
4332 void addAccess(StoreInst *SI) {
4333 Value *Ptr = SI->getPointerOperand();
4334 Accesses[MemAccessInfo(Ptr, true)].push_back(AccessIdx);
4335 InstMap.push_back(SI);
4336 ++AccessIdx;
4337 }
4338
4339 /// \brief Register the location (instructions are given increasing numbers)
4340 /// of a write access.
4341 void addAccess(LoadInst *LI) {
4342 Value *Ptr = LI->getPointerOperand();
4343 Accesses[MemAccessInfo(Ptr, false)].push_back(AccessIdx);
4344 InstMap.push_back(LI);
4345 ++AccessIdx;
4346 }
4347
4348 /// \brief Check whether the dependencies between the accesses are safe.
4349 ///
4350 /// Only checks sets with elements in \p CheckDeps.
4351 bool areDepsSafe(AccessAnalysis::DepCandidates &AccessSets,
4352 MemAccessInfoSet &CheckDeps, ValueToValueMap &Strides);
4353
4354 /// \brief The maximum number of bytes of a vector register we can vectorize
4355 /// the accesses safely with.
4356 unsigned getMaxSafeDepDistBytes() { return MaxSafeDepDistBytes; }
4357
4358 /// \brief In same cases when the dependency check fails we can still
4359 /// vectorize the loop with a dynamic array access check.
4360 bool shouldRetryWithRuntimeCheck() { return ShouldRetryWithRuntimeCheck; }
4361
4362private:
4363 ScalarEvolution *SE;
4364 const DataLayout *DL;
4365 const Loop *InnermostLoop;
4366
4367 /// \brief Maps access locations (ptr, read/write) to program order.
4368 DenseMap<MemAccessInfo, std::vector<unsigned> > Accesses;
4369
4370 /// \brief Memory access instructions in program order.
4371 SmallVector<Instruction *, 16> InstMap;
4372
4373 /// \brief The program order index to be used for the next instruction.
4374 unsigned AccessIdx;
4375
4376 // We can access this many bytes in parallel safely.
4377 unsigned MaxSafeDepDistBytes;
4378
4379 /// \brief If we see a non-constant dependence distance we can still try to
4380 /// vectorize this loop with runtime checks.
4381 bool ShouldRetryWithRuntimeCheck;
4382
4383 /// \brief Check whether there is a plausible dependence between the two
4384 /// accesses.
4385 ///
4386 /// Access \p A must happen before \p B in program order. The two indices
4387 /// identify the index into the program order map.
4388 ///
4389 /// This function checks whether there is a plausible dependence (or the
4390 /// absence of such can't be proved) between the two accesses. If there is a
4391 /// plausible dependence but the dependence distance is bigger than one
4392 /// element access it records this distance in \p MaxSafeDepDistBytes (if this
4393 /// distance is smaller than any other distance encountered so far).
4394 /// Otherwise, this function returns true signaling a possible dependence.
4395 bool isDependent(const MemAccessInfo &A, unsigned AIdx,
4396 const MemAccessInfo &B, unsigned BIdx,
4397 ValueToValueMap &Strides);
4398
4399 /// \brief Check whether the data dependence could prevent store-load
4400 /// forwarding.
4401 bool couldPreventStoreLoadForward(unsigned Distance, unsigned TypeByteSize);
4402};
4403
4404} // end anonymous namespace
4405
4406static bool isInBoundsGep(Value *Ptr) {
4407 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
4408 return GEP->isInBounds();
4409 return false;
4410}
4411
4412/// \brief Check whether the access through \p Ptr has a constant stride.
4413static int isStridedPtr(ScalarEvolution *SE, const DataLayout *DL, Value *Ptr,
4414 const Loop *Lp, ValueToValueMap &StridesMap) {
4415 const Type *Ty = Ptr->getType();
4416 assert(Ty->isPointerTy() && "Unexpected non-ptr")((Ty->isPointerTy() && "Unexpected non-ptr") ? static_cast
<void> (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-ptr\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4416, __PRETTY_FUNCTION__))
;
4417
4418 // Make sure that the pointer does not point to aggregate types.
4419 const PointerType *PtrTy = cast<PointerType>(Ty);
4420 if (PtrTy->getElementType()->isAggregateType()) {
4421 DEBUG(dbgs() << "LV: Bad stride - Not a pointer to a scalar type" << *Ptr <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Not a pointer to a scalar type"
<< *Ptr << "\n"; } } while (0)
4422 "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Not a pointer to a scalar type"
<< *Ptr << "\n"; } } while (0)
;
4423 return 0;
4424 }
4425
4426 const SCEV *PtrScev = replaceSymbolicStrideSCEV(SE, StridesMap, Ptr);
4427
4428 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PtrScev);
4429 if (!AR) {
4430 DEBUG(dbgs() << "LV: Bad stride - Not an AddRecExpr pointer "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Not an AddRecExpr pointer "
<< *Ptr << " SCEV: " << *PtrScev << "\n"
; } } while (0)
4431 << *Ptr << " SCEV: " << *PtrScev << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Not an AddRecExpr pointer "
<< *Ptr << " SCEV: " << *PtrScev << "\n"
; } } while (0)
;
4432 return 0;
4433 }
4434
4435 // The accesss function must stride over the innermost loop.
4436 if (Lp != AR->getLoop()) {
4437 DEBUG(dbgs() << "LV: Bad stride - Not striding over innermost loop " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Not striding over innermost loop "
<< *Ptr << " SCEV: " << *PtrScev << "\n"
; } } while (0)
4438 *Ptr << " SCEV: " << *PtrScev << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Not striding over innermost loop "
<< *Ptr << " SCEV: " << *PtrScev << "\n"
; } } while (0)
;
4439 }
4440
4441 // The address calculation must not wrap. Otherwise, a dependence could be
4442 // inverted.
4443 // An inbounds getelementptr that is a AddRec with a unit stride
4444 // cannot wrap per definition. The unit stride requirement is checked later.
4445 // An getelementptr without an inbounds attribute and unit stride would have
4446 // to access the pointer value "0" which is undefined behavior in address
4447 // space 0, therefore we can also vectorize this case.
4448 bool IsInBoundsGEP = isInBoundsGep(Ptr);
4449 bool IsNoWrapAddRec = AR->getNoWrapFlags(SCEV::NoWrapMask);
4450 bool IsInAddressSpaceZero = PtrTy->getAddressSpace() == 0;
4451 if (!IsNoWrapAddRec && !IsInBoundsGEP && !IsInAddressSpaceZero) {
4452 DEBUG(dbgs() << "LV: Bad stride - Pointer may wrap in the address space "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Pointer may wrap in the address space "
<< *Ptr << " SCEV: " << *PtrScev << "\n"
; } } while (0)
4453 << *Ptr << " SCEV: " << *PtrScev << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Pointer may wrap in the address space "
<< *Ptr << " SCEV: " << *PtrScev << "\n"
; } } while (0)
;
4454 return 0;
4455 }
4456
4457 // Check the step is constant.
4458 const SCEV *Step = AR->getStepRecurrence(*SE);
4459
4460 // Calculate the pointer stride and check if it is consecutive.
4461 const SCEVConstant *C = dyn_cast<SCEVConstant>(Step);
4462 if (!C) {
4463 DEBUG(dbgs() << "LV: Bad stride - Not a constant strided " << *Ptr <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Not a constant strided "
<< *Ptr << " SCEV: " << *PtrScev << "\n"
; } } while (0)
4464 " SCEV: " << *PtrScev << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Bad stride - Not a constant strided "
<< *Ptr << " SCEV: " << *PtrScev << "\n"
; } } while (0)
;
4465 return 0;
4466 }
4467
4468 int64_t Size = DL->getTypeAllocSize(PtrTy->getElementType());
4469 const APInt &APStepVal = C->getValue()->getValue();
4470
4471 // Huge step value - give up.
4472 if (APStepVal.getBitWidth() > 64)
4473 return 0;
4474
4475 int64_t StepVal = APStepVal.getSExtValue();
4476
4477 // Strided access.
4478 int64_t Stride = StepVal / Size;
4479 int64_t Rem = StepVal % Size;
4480 if (Rem)
4481 return 0;
4482
4483 // If the SCEV could wrap but we have an inbounds gep with a unit stride we
4484 // know we can't "wrap around the address space". In case of address space
4485 // zero we know that this won't happen without triggering undefined behavior.
4486 if (!IsNoWrapAddRec && (IsInBoundsGEP || IsInAddressSpaceZero) &&
4487 Stride != 1 && Stride != -1)
4488 return 0;
4489
4490 return Stride;
4491}
4492
4493bool MemoryDepChecker::couldPreventStoreLoadForward(unsigned Distance,
4494 unsigned TypeByteSize) {
4495 // If loads occur at a distance that is not a multiple of a feasible vector
4496 // factor store-load forwarding does not take place.
4497 // Positive dependences might cause troubles because vectorizing them might
4498 // prevent store-load forwarding making vectorized code run a lot slower.
4499 // a[i] = a[i-3] ^ a[i-8];
4500 // The stores to a[i:i+1] don't align with the stores to a[i-3:i-2] and
4501 // hence on your typical architecture store-load forwarding does not take
4502 // place. Vectorizing in such cases does not make sense.
4503 // Store-load forwarding distance.
4504 const unsigned NumCyclesForStoreLoadThroughMemory = 8*TypeByteSize;
4505 // Maximum vector factor.
4506 unsigned MaxVFWithoutSLForwardIssues = MaxVectorWidth*TypeByteSize;
4507 if(MaxSafeDepDistBytes < MaxVFWithoutSLForwardIssues)
4508 MaxVFWithoutSLForwardIssues = MaxSafeDepDistBytes;
4509
4510 for (unsigned vf = 2*TypeByteSize; vf <= MaxVFWithoutSLForwardIssues;
4511 vf *= 2) {
4512 if (Distance % vf && Distance / vf < NumCyclesForStoreLoadThroughMemory) {
4513 MaxVFWithoutSLForwardIssues = (vf >>=1);
4514 break;
4515 }
4516 }
4517
4518 if (MaxVFWithoutSLForwardIssues< 2*TypeByteSize) {
4519 DEBUG(dbgs() << "LV: Distance " << Distance <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Distance " <<
Distance << " that could cause a store-load forwarding conflict\n"
; } } while (0)
4520 " that could cause a store-load forwarding conflict\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Distance " <<
Distance << " that could cause a store-load forwarding conflict\n"
; } } while (0)
;
4521 return true;
4522 }
4523
4524 if (MaxVFWithoutSLForwardIssues < MaxSafeDepDistBytes &&
4525 MaxVFWithoutSLForwardIssues != MaxVectorWidth*TypeByteSize)
4526 MaxSafeDepDistBytes = MaxVFWithoutSLForwardIssues;
4527 return false;
4528}
4529
4530bool MemoryDepChecker::isDependent(const MemAccessInfo &A, unsigned AIdx,
4531 const MemAccessInfo &B, unsigned BIdx,
4532 ValueToValueMap &Strides) {
4533 assert (AIdx < BIdx && "Must pass arguments in program order")((AIdx < BIdx && "Must pass arguments in program order"
) ? static_cast<void> (0) : __assert_fail ("AIdx < BIdx && \"Must pass arguments in program order\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4533, __PRETTY_FUNCTION__))
;
4534
4535 Value *APtr = A.getPointer();
4536 Value *BPtr = B.getPointer();
4537 bool AIsWrite = A.getInt();
4538 bool BIsWrite = B.getInt();
4539
4540 // Two reads are independent.
4541 if (!AIsWrite && !BIsWrite)
4542 return false;
4543
4544 // We cannot check pointers in different address spaces.
4545 if (APtr->getType()->getPointerAddressSpace() !=
4546 BPtr->getType()->getPointerAddressSpace())
4547 return true;
4548
4549 const SCEV *AScev = replaceSymbolicStrideSCEV(SE, Strides, APtr);
4550 const SCEV *BScev = replaceSymbolicStrideSCEV(SE, Strides, BPtr);
4551
4552 int StrideAPtr = isStridedPtr(SE, DL, APtr, InnermostLoop, Strides);
4553 int StrideBPtr = isStridedPtr(SE, DL, BPtr, InnermostLoop, Strides);
4554
4555 const SCEV *Src = AScev;
4556 const SCEV *Sink = BScev;
4557
4558 // If the induction step is negative we have to invert source and sink of the
4559 // dependence.
4560 if (StrideAPtr < 0) {
4561 //Src = BScev;
4562 //Sink = AScev;
4563 std::swap(APtr, BPtr);
4564 std::swap(Src, Sink);
4565 std::swap(AIsWrite, BIsWrite);
4566 std::swap(AIdx, BIdx);
4567 std::swap(StrideAPtr, StrideBPtr);
4568 }
4569
4570 const SCEV *Dist = SE->getMinusSCEV(Sink, Src);
4571
4572 DEBUG(dbgs() << "LV: Src Scev: " << *Src << "Sink Scev: " << *Sinkdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Src Scev: " <<
*Src << "Sink Scev: " << *Sink << "(Induction step: "
<< StrideAPtr << ")\n"; } } while (0)
4573 << "(Induction step: " << StrideAPtr << ")\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Src Scev: " <<
*Src << "Sink Scev: " << *Sink << "(Induction step: "
<< StrideAPtr << ")\n"; } } while (0)
;
4574 DEBUG(dbgs() << "LV: Distance for " << *InstMap[AIdx] << " to "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Distance for " <<
*InstMap[AIdx] << " to " << *InstMap[BIdx] <<
": " << *Dist << "\n"; } } while (0)
4575 << *InstMap[BIdx] << ": " << *Dist << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Distance for " <<
*InstMap[AIdx] << " to " << *InstMap[BIdx] <<
": " << *Dist << "\n"; } } while (0)
;
4576
4577 // Need consecutive accesses. We don't want to vectorize
4578 // "A[B[i]] += ..." and similar code or pointer arithmetic that could wrap in
4579 // the address space.
4580 if (!StrideAPtr || !StrideBPtr || StrideAPtr != StrideBPtr){
4581 DEBUG(dbgs() << "Non-consecutive pointer access\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "Non-consecutive pointer access\n"
; } } while (0)
;
4582 return true;
4583 }
4584
4585 const SCEVConstant *C = dyn_cast<SCEVConstant>(Dist);
4586 if (!C) {
4587 DEBUG(dbgs() << "LV: Dependence because of non-constant distance\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Dependence because of non-constant distance\n"
; } } while (0)
;
4588 ShouldRetryWithRuntimeCheck = true;
4589 return true;
4590 }
4591
4592 Type *ATy = APtr->getType()->getPointerElementType();
4593 Type *BTy = BPtr->getType()->getPointerElementType();
4594 unsigned TypeByteSize = DL->getTypeAllocSize(ATy);
4595
4596 // Negative distances are not plausible dependencies.
4597 const APInt &Val = C->getValue()->getValue();
4598 if (Val.isNegative()) {
4599 bool IsTrueDataDependence = (AIsWrite && !BIsWrite);
4600 if (IsTrueDataDependence &&
4601 (couldPreventStoreLoadForward(Val.abs().getZExtValue(), TypeByteSize) ||
4602 ATy != BTy))
4603 return true;
4604
4605 DEBUG(dbgs() << "LV: Dependence is negative: NoDep\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Dependence is negative: NoDep\n"
; } } while (0)
;
4606 return false;
4607 }
4608
4609 // Write to the same location with the same size.
4610 // Could be improved to assert type sizes are the same (i32 == float, etc).
4611 if (Val == 0) {
4612 if (ATy == BTy)
4613 return false;
4614 DEBUG(dbgs() << "LV: Zero dependence difference but different types\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Zero dependence difference but different types\n"
; } } while (0)
;
4615 return true;
4616 }
4617
4618 assert(Val.isStrictlyPositive() && "Expect a positive value")((Val.isStrictlyPositive() && "Expect a positive value"
) ? static_cast<void> (0) : __assert_fail ("Val.isStrictlyPositive() && \"Expect a positive value\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 4618, __PRETTY_FUNCTION__))
;
4619
4620 // Positive distance bigger than max vectorization factor.
4621 if (ATy != BTy) {
4622 DEBUG(dbgs() <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: ReadWrite-Write positive dependency with different types\n"
; } } while (0)
4623 "LV: ReadWrite-Write positive dependency with different types\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: ReadWrite-Write positive dependency with different types\n"
; } } while (0)
;
4624 return false;
4625 }
4626
4627 unsigned Distance = (unsigned) Val.getZExtValue();
4628
4629 // Bail out early if passed-in parameters make vectorization not feasible.
4630 unsigned ForcedFactor = VectorizationFactor ? VectorizationFactor : 1;
4631 unsigned ForcedUnroll = VectorizationInterleave ? VectorizationInterleave : 1;
4632
4633 // The distance must be bigger than the size needed for a vectorized version
4634 // of the operation and the size of the vectorized operation must not be
4635 // bigger than the currrent maximum size.
4636 if (Distance < 2*TypeByteSize ||
4637 2*TypeByteSize > MaxSafeDepDistBytes ||
4638 Distance < TypeByteSize * ForcedUnroll * ForcedFactor) {
4639 DEBUG(dbgs() << "LV: Failure because of Positive distance "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Failure because of Positive distance "
<< Val.getSExtValue() << '\n'; } } while (0)
4640 << Val.getSExtValue() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Failure because of Positive distance "
<< Val.getSExtValue() << '\n'; } } while (0)
;
4641 return true;
4642 }
4643
4644 MaxSafeDepDistBytes = Distance < MaxSafeDepDistBytes ?
4645 Distance : MaxSafeDepDistBytes;
4646
4647 bool IsTrueDataDependence = (!AIsWrite && BIsWrite);
4648 if (IsTrueDataDependence &&
4649 couldPreventStoreLoadForward(Distance, TypeByteSize))
4650 return true;
4651
4652 DEBUG(dbgs() << "LV: Positive distance " << Val.getSExtValue() <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Positive distance "
<< Val.getSExtValue() << " with max VF = " <<
MaxSafeDepDistBytes / TypeByteSize << '\n'; } } while (
0)
4653 " with max VF = " << MaxSafeDepDistBytes / TypeByteSize << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Positive distance "
<< Val.getSExtValue() << " with max VF = " <<
MaxSafeDepDistBytes / TypeByteSize << '\n'; } } while (
0)
;
4654
4655 return false;
4656}
4657
4658bool MemoryDepChecker::areDepsSafe(AccessAnalysis::DepCandidates &AccessSets,
4659 MemAccessInfoSet &CheckDeps,
4660 ValueToValueMap &Strides) {
4661
4662 MaxSafeDepDistBytes = -1U;
4663 while (!CheckDeps.empty()) {
4664 MemAccessInfo CurAccess = *CheckDeps.begin();
4665
4666 // Get the relevant memory access set.
4667 EquivalenceClasses<MemAccessInfo>::iterator I =
4668 AccessSets.findValue(AccessSets.getLeaderValue(CurAccess));
4669
4670 // Check accesses within this set.
4671 EquivalenceClasses<MemAccessInfo>::member_iterator AI, AE;
4672 AI = AccessSets.member_begin(I), AE = AccessSets.member_end();
4673
4674 // Check every access pair.
4675 while (AI != AE) {
4676 CheckDeps.erase(*AI);
4677 EquivalenceClasses<MemAccessInfo>::member_iterator OI = std::next(AI);
4678 while (OI != AE) {
4679 // Check every accessing instruction pair in program order.
4680 for (std::vector<unsigned>::iterator I1 = Accesses[*AI].begin(),
4681 I1E = Accesses[*AI].end(); I1 != I1E; ++I1)
4682 for (std::vector<unsigned>::iterator I2 = Accesses[*OI].begin(),
4683 I2E = Accesses[*OI].end(); I2 != I2E; ++I2) {
4684 if (*I1 < *I2 && isDependent(*AI, *I1, *OI, *I2, Strides))
4685 return false;
4686 if (*I2 < *I1 && isDependent(*OI, *I2, *AI, *I1, Strides))
4687 return false;
4688 }
4689 ++OI;
4690 }
4691 AI++;
4692 }
4693 }
4694 return true;
4695}
4696
4697bool LoopVectorizationLegality::canVectorizeMemory() {
4698
4699 typedef SmallVector<Value*, 16> ValueVector;
4700 typedef SmallPtrSet<Value*, 16> ValueSet;
4701
4702 // Holds the Load and Store *instructions*.
4703 ValueVector Loads;
4704 ValueVector Stores;
4705
4706 // Holds all the different accesses in the loop.
4707 unsigned NumReads = 0;
4708 unsigned NumReadWrites = 0;
4709
4710 PtrRtCheck.Pointers.clear();
4711 PtrRtCheck.Need = false;
4712
4713 const bool IsAnnotatedParallel = TheLoop->isAnnotatedParallel();
4714 MemoryDepChecker DepChecker(SE, DL, TheLoop);
4715
4716 // For each block.
4717 for (Loop::block_iterator bb = TheLoop->block_begin(),
4718 be = TheLoop->block_end(); bb != be; ++bb) {
4719
4720 // Scan the BB and collect legal loads and stores.
4721 for (BasicBlock::iterator it = (*bb)->begin(), e = (*bb)->end(); it != e;
4722 ++it) {
4723
4724 // If this is a load, save it. If this instruction can read from memory
4725 // but is not a load, then we quit. Notice that we don't handle function
4726 // calls that read or write.
4727 if (it->mayReadFromMemory()) {
4728 // Many math library functions read the rounding mode. We will only
4729 // vectorize a loop if it contains known function calls that don't set
4730 // the flag. Therefore, it is safe to ignore this read from memory.
4731 CallInst *Call = dyn_cast<CallInst>(it);
4732 if (Call && getIntrinsicIDForCall(Call, TLI))
4733 continue;
4734
4735 LoadInst *Ld = dyn_cast<LoadInst>(it);
4736 if (!Ld || (!Ld->isSimple() && !IsAnnotatedParallel)) {
4737 emitAnalysis(Report(Ld)
4738 << "read with atomic ordering or volatile read");
4739 DEBUG(dbgs() << "LV: Found a non-simple load.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a non-simple load.\n"
; } } while (0)
;
4740 return false;
4741 }
4742 NumLoads++;
4743 Loads.push_back(Ld);
4744 DepChecker.addAccess(Ld);
4745 continue;
4746 }
4747
4748 // Save 'store' instructions. Abort if other instructions write to memory.
4749 if (it->mayWriteToMemory()) {
4750 StoreInst *St = dyn_cast<StoreInst>(it);
4751 if (!St) {
4752 emitAnalysis(Report(it) << "instruction cannot be vectorized");
4753 return false;
4754 }
4755 if (!St->isSimple() && !IsAnnotatedParallel) {
4756 emitAnalysis(Report(St)
4757 << "write with atomic ordering or volatile write");
4758 DEBUG(dbgs() << "LV: Found a non-simple store.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a non-simple store.\n"
; } } while (0)
;
4759 return false;
4760 }
4761 NumStores++;
4762 Stores.push_back(St);
4763 DepChecker.addAccess(St);
4764 }
4765 } // Next instr.
4766 } // Next block.
4767
4768 // Now we have two lists that hold the loads and the stores.
4769 // Next, we find the pointers that they use.
4770
4771 // Check if we see any stores. If there are no stores, then we don't
4772 // care if the pointers are *restrict*.
4773 if (!Stores.size()) {
4774 DEBUG(dbgs() << "LV: Found a read-only loop!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a read-only loop!\n"
; } } while (0)
;
4775 return true;
4776 }
4777
4778 AccessAnalysis::DepCandidates DependentAccesses;
4779 AccessAnalysis Accesses(DL, AA, DependentAccesses);
4780
4781 // Holds the analyzed pointers. We don't want to call GetUnderlyingObjects
4782 // multiple times on the same object. If the ptr is accessed twice, once
4783 // for read and once for write, it will only appear once (on the write
4784 // list). This is okay, since we are going to check for conflicts between
4785 // writes and between reads and writes, but not between reads and reads.
4786 ValueSet Seen;
4787
4788 ValueVector::iterator I, IE;
4789 for (I = Stores.begin(), IE = Stores.end(); I != IE; ++I) {
4790 StoreInst *ST = cast<StoreInst>(*I);
4791 Value* Ptr = ST->getPointerOperand();
4792
4793 if (isUniform(Ptr)) {
4794 emitAnalysis(
4795 Report(ST)
4796 << "write to a loop invariant address could not be vectorized");
4797 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 (0)
;
4798 return false;
4799 }
4800
4801 // If we did *not* see this pointer before, insert it to the read-write
4802 // list. At this phase it is only a 'write' list.
4803 if (Seen.insert(Ptr)) {
4804 ++NumReadWrites;
4805
4806 AliasAnalysis::Location Loc = AA->getLocation(ST);
4807 // The TBAA metadata could have a control dependency on the predication
4808 // condition, so we cannot rely on it when determining whether or not we
4809 // need runtime pointer checks.
4810 if (blockNeedsPredication(ST->getParent()))
4811 Loc.AATags.TBAA = nullptr;
4812
4813 Accesses.addStore(Loc);
4814 }
4815 }
4816
4817 if (IsAnnotatedParallel) {
4818 DEBUG(dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: A loop annotated parallel, ignore memory dependency "
<< "checks.\n"; } } while (0)
4819 << "LV: A loop annotated parallel, ignore memory dependency "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: A loop annotated parallel, ignore memory dependency "
<< "checks.\n"; } } while (0)
4820 << "checks.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: A loop annotated parallel, ignore memory dependency "
<< "checks.\n"; } } while (0)
;
4821 return true;
4822 }
4823
4824 for (I = Loads.begin(), IE = Loads.end(); I != IE; ++I) {
4825 LoadInst *LD = cast<LoadInst>(*I);
4826 Value* Ptr = LD->getPointerOperand();
4827 // If we did *not* see this pointer before, insert it to the
4828 // read list. If we *did* see it before, then it is already in
4829 // the read-write list. This allows us to vectorize expressions
4830 // such as A[i] += x; Because the address of A[i] is a read-write
4831 // pointer. This only works if the index of A[i] is consecutive.
4832 // If the address of i is unknown (for example A[B[i]]) then we may
4833 // read a few words, modify, and write a few words, and some of the
4834 // words may be written to the same address.
4835 bool IsReadOnlyPtr = false;
4836 if (Seen.insert(Ptr) || !isStridedPtr(SE, DL, Ptr, TheLoop, Strides)) {
4837 ++NumReads;
4838 IsReadOnlyPtr = true;
4839 }
4840
4841 AliasAnalysis::Location Loc = AA->getLocation(LD);
4842 // The TBAA metadata could have a control dependency on the predication
4843 // condition, so we cannot rely on it when determining whether or not we
4844 // need runtime pointer checks.
4845 if (blockNeedsPredication(LD->getParent()))
4846 Loc.AATags.TBAA = nullptr;
4847
4848 Accesses.addLoad(Loc, IsReadOnlyPtr);
4849 }
4850
4851 // If we write (or read-write) to a single destination and there are no
4852 // other reads in this loop then is it safe to vectorize.
4853 if (NumReadWrites == 1 && NumReads == 0) {
4854 DEBUG(dbgs() << "LV: Found a write-only loop!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found a write-only loop!\n"
; } } while (0)
;
4855 return true;
4856 }
4857
4858 // Build dependence sets and check whether we need a runtime pointer bounds
4859 // check.
4860 Accesses.buildDependenceSets();
4861 bool NeedRTCheck = Accesses.isRTCheckNeeded();
4862
4863 // Find pointers with computable bounds. We are going to use this information
4864 // to place a runtime bound check.
4865 unsigned NumComparisons = 0;
4866 bool CanDoRT = false;
4867 if (NeedRTCheck)
4868 CanDoRT = Accesses.canCheckPtrAtRT(PtrRtCheck, NumComparisons, SE, TheLoop,
4869 Strides);
4870
4871 DEBUG(dbgs() << "LV: We need to do " << NumComparisons <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We need to do " <<
NumComparisons << " pointer comparisons.\n"; } } while
(0)
4872 " pointer comparisons.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We need to do " <<
NumComparisons << " pointer comparisons.\n"; } } while
(0)
;
4873
4874 // If we only have one set of dependences to check pointers among we don't
4875 // need a runtime check.
4876 if (NumComparisons == 0 && NeedRTCheck)
4877 NeedRTCheck = false;
4878
4879 // Check that we did not collect too many pointers or found an unsizeable
4880 // pointer.
4881 if (!CanDoRT || NumComparisons > RuntimeMemoryCheckThreshold) {
4882 PtrRtCheck.reset();
4883 CanDoRT = false;
4884 }
4885
4886 if (CanDoRT) {
4887 DEBUG(dbgs() << "LV: We can perform a memory runtime check if needed.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can perform a memory runtime check if needed.\n"
; } } while (0)
;
4888 }
4889
4890 if (NeedRTCheck && !CanDoRT) {
4891 emitAnalysis(Report() << "cannot identify array bounds");
4892 DEBUG(dbgs() << "LV: We can't vectorize because we can't find " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can't vectorize because we can't find "
<< "the array bounds.\n"; } } while (0)
4893 "the array bounds.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We can't vectorize because we can't find "
<< "the array bounds.\n"; } } while (0)
;
4894 PtrRtCheck.reset();
4895 return false;
4896 }
4897
4898 PtrRtCheck.Need = NeedRTCheck;
4899
4900 bool CanVecMem = true;
4901 if (Accesses.isDependencyCheckNeeded()) {
4902 DEBUG(dbgs() << "LV: Checking memory dependencies\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Checking memory dependencies\n"
; } } while (0)
;
4903 CanVecMem = DepChecker.areDepsSafe(
4904 DependentAccesses, Accesses.getDependenciesToCheck(), Strides);
4905 MaxSafeDepDistBytes = DepChecker.getMaxSafeDepDistBytes();
4906
4907 if (!CanVecMem && DepChecker.shouldRetryWithRuntimeCheck()) {
4908 DEBUG(dbgs() << "LV: Retrying with memory checks\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Retrying with memory checks\n"
; } } while (0)
;
4909 NeedRTCheck = true;
4910
4911 // Clear the dependency checks. We assume they are not needed.
4912 Accesses.resetDepChecks();
4913
4914 PtrRtCheck.reset();
4915 PtrRtCheck.Need = true;
4916
4917 CanDoRT = Accesses.canCheckPtrAtRT(PtrRtCheck, NumComparisons, SE,
4918 TheLoop, Strides, true);
4919 // Check that we did not collect too many pointers or found an unsizeable
4920 // pointer.
4921 if (!CanDoRT || NumComparisons > RuntimeMemoryCheckThreshold) {
4922 if (!CanDoRT && NumComparisons > 0)
4923 emitAnalysis(Report()
4924 << "cannot check memory dependencies at runtime");
4925 else
4926 emitAnalysis(Report()
4927 << NumComparisons << " exceeds limit of "
4928 << RuntimeMemoryCheckThreshold
4929 << " dependent memory operations checked at runtime");
4930 DEBUG(dbgs() << "LV: Can't vectorize with memory checks\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Can't vectorize with memory checks\n"
; } } while (0)
;
4931 PtrRtCheck.reset();
4932 return false;
4933 }
4934
4935 CanVecMem = true;
4936 }
4937 }
4938
4939 if (!CanVecMem)
4940 emitAnalysis(Report() << "unsafe dependent memory operations in loop");
4941
4942 DEBUG(dbgs() << "LV: We" << (NeedRTCheck ? "" : " don't") <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We" << (NeedRTCheck
? "" : " don't") << " need a runtime memory check.\n";
} } while (0)
4943 " need a runtime memory check.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: We" << (NeedRTCheck
? "" : " don't") << " need a runtime memory check.\n";
} } while (0)
;
4944
4945 return CanVecMem;
4946}
4947
4948static bool hasMultipleUsesOf(Instruction *I,
4949 SmallPtrSetImpl<Instruction *> &Insts) {
4950 unsigned NumUses = 0;
4951 for(User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E; ++Use) {
4952 if (Insts.count(dyn_cast<Instruction>(*Use)))
4953 ++NumUses;
4954 if (NumUses > 1)
4955 return true;
4956 }
4957
4958 return false;
4959}
4960
4961static bool areAllUsesIn(Instruction *I, SmallPtrSetImpl<Instruction *> &Set) {
4962 for(User::op_iterator Use = I->op_begin(), E = I->op_end(); Use != E; ++Use)
4963 if (!Set.count(dyn_cast<Instruction>(*Use)))
4964 return false;
4965 return true;
4966}
4967
4968bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
4969 ReductionKind Kind) {
4970 if (Phi->getNumIncomingValues() != 2)
4971 return false;
4972
4973 // Reduction variables are only found in the loop header block.
4974 if (Phi->getParent() != TheLoop->getHeader())
4975 return false;
4976
4977 // Obtain the reduction start value from the value that comes from the loop
4978 // preheader.
4979 Value *RdxStart = Phi->getIncomingValueForBlock(TheLoop->getLoopPreheader());
4980
4981 // ExitInstruction is the single value which is used outside the loop.
4982 // We only allow for a single reduction value to be used outside the loop.
4983 // This includes users of the reduction, variables (which form a cycle
4984 // which ends in the phi node).
4985 Instruction *ExitInstruction = nullptr;
4986 // Indicates that we found a reduction operation in our scan.
4987 bool FoundReduxOp = false;
4988
4989 // We start with the PHI node and scan for all of the users of this
4990 // instruction. All users must be instructions that can be used as reduction
4991 // variables (such as ADD). We must have a single out-of-block user. The cycle
4992 // must include the original PHI.
4993 bool FoundStartPHI = false;
4994
4995 // To recognize min/max patterns formed by a icmp select sequence, we store
4996 // the number of instruction we saw from the recognized min/max pattern,
4997 // to make sure we only see exactly the two instructions.
4998 unsigned NumCmpSelectPatternInst = 0;
4999 ReductionInstDesc ReduxDesc(false, nullptr);
5000
5001 SmallPtrSet<Instruction *, 8> VisitedInsts;
5002 SmallVector<Instruction *, 8> Worklist;
5003 Worklist.push_back(Phi);
5004 VisitedInsts.insert(Phi);
5005
5006 // A value in the reduction can be used:
5007 // - By the reduction:
5008 // - Reduction operation:
5009 // - One use of reduction value (safe).
5010 // - Multiple use of reduction value (not safe).
5011 // - PHI:
5012 // - All uses of the PHI must be the reduction (safe).
5013 // - Otherwise, not safe.
5014 // - By one instruction outside of the loop (safe).
5015 // - By further instructions outside of the loop (not safe).
5016 // - By an instruction that is not part of the reduction (not safe).
5017 // This is either:
5018 // * An instruction type other than PHI or the reduction operation.
5019 // * A PHI in the header other than the initial PHI.
5020 while (!Worklist.empty()) {
5021 Instruction *Cur = Worklist.back();
5022 Worklist.pop_back();
5023
5024 // No Users.
5025 // If the instruction has no users then this is a broken chain and can't be
5026 // a reduction variable.
5027 if (Cur->use_empty())
5028 return false;
5029
5030 bool IsAPhi = isa<PHINode>(Cur);
5031
5032 // A header PHI use other than the original PHI.
5033 if (Cur != Phi && IsAPhi && Cur->getParent() == Phi->getParent())
5034 return false;
5035
5036 // Reductions of instructions such as Div, and Sub is only possible if the
5037 // LHS is the reduction variable.
5038 if (!Cur->isCommutative() && !IsAPhi && !isa<SelectInst>(Cur) &&
5039 !isa<ICmpInst>(Cur) && !isa<FCmpInst>(Cur) &&
5040 !VisitedInsts.count(dyn_cast<Instruction>(Cur->getOperand(0))))
5041 return false;
5042
5043 // Any reduction instruction must be of one of the allowed kinds.
5044 ReduxDesc = isReductionInstr(Cur, Kind, ReduxDesc);
5045 if (!ReduxDesc.IsReduction)
5046 return false;
5047
5048 // A reduction operation must only have one use of the reduction value.
5049 if (!IsAPhi && Kind != RK_IntegerMinMax && Kind != RK_FloatMinMax &&
5050 hasMultipleUsesOf(Cur, VisitedInsts))
5051 return false;
5052
5053 // All inputs to a PHI node must be a reduction value.
5054 if(IsAPhi && Cur != Phi && !areAllUsesIn(Cur, VisitedInsts))
5055 return false;
5056
5057 if (Kind == RK_IntegerMinMax && (isa<ICmpInst>(Cur) ||
5058 isa<SelectInst>(Cur)))
5059 ++NumCmpSelectPatternInst;
5060 if (Kind == RK_FloatMinMax && (isa<FCmpInst>(Cur) ||
5061 isa<SelectInst>(Cur)))
5062 ++NumCmpSelectPatternInst;
5063
5064 // Check whether we found a reduction operator.
5065 FoundReduxOp |= !IsAPhi;
5066
5067 // Process users of current instruction. Push non-PHI nodes after PHI nodes
5068 // onto the stack. This way we are going to have seen all inputs to PHI
5069 // nodes once we get to them.
5070 SmallVector<Instruction *, 8> NonPHIs;
5071 SmallVector<Instruction *, 8> PHIs;
5072 for (User *U : Cur->users()) {
5073 Instruction *UI = cast<Instruction>(U);
5074
5075 // Check if we found the exit user.
5076 BasicBlock *Parent = UI->getParent();
5077 if (!TheLoop->contains(Parent)) {
5078 // Exit if you find multiple outside users or if the header phi node is
5079 // being used. In this case the user uses the value of the previous
5080 // iteration, in which case we would loose "VF-1" iterations of the
5081 // reduction operation if we vectorize.
5082 if (ExitInstruction != nullptr || Cur == Phi)
5083 return false;
5084
5085 // The instruction used by an outside user must be the last instruction
5086 // before we feed back to the reduction phi. Otherwise, we loose VF-1
5087 // operations on the value.
5088 if (std::find(Phi->op_begin(), Phi->op_end(), Cur) == Phi->op_end())
5089 return false;
5090
5091 ExitInstruction = Cur;
5092 continue;
5093 }
5094
5095 // Process instructions only once (termination). Each reduction cycle
5096 // value must only be used once, except by phi nodes and min/max
5097 // reductions which are represented as a cmp followed by a select.
5098 ReductionInstDesc IgnoredVal(false, nullptr);
5099 if (VisitedInsts.insert(UI)) {
5100 if (isa<PHINode>(UI))
5101 PHIs.push_back(UI);
5102 else
5103 NonPHIs.push_back(UI);
5104 } else if (!isa<PHINode>(UI) &&
5105 ((!isa<FCmpInst>(UI) &&
5106 !isa<ICmpInst>(UI) &&
5107 !isa<SelectInst>(UI)) ||
5108 !isMinMaxSelectCmpPattern(UI, IgnoredVal).IsReduction))
5109 return false;
5110
5111 // Remember that we completed the cycle.
5112 if (UI == Phi)
5113 FoundStartPHI = true;
5114 }
5115 Worklist.append(PHIs.begin(), PHIs.end());
5116 Worklist.append(NonPHIs.begin(), NonPHIs.end());
5117 }
5118
5119 // This means we have seen one but not the other instruction of the
5120 // pattern or more than just a select and cmp.
5121 if ((Kind == RK_IntegerMinMax || Kind == RK_FloatMinMax) &&
5122 NumCmpSelectPatternInst != 2)
5123 return false;
5124
5125 if (!FoundStartPHI || !FoundReduxOp || !ExitInstruction)
5126 return false;
5127
5128 // We found a reduction var if we have reached the original phi node and we
5129 // only have a single instruction with out-of-loop users.
5130
5131 // This instruction is allowed to have out-of-loop users.
5132 AllowedExit.insert(ExitInstruction);
5133
5134 // Save the description of this reduction variable.
5135 ReductionDescriptor RD(RdxStart, ExitInstruction, Kind,
5136 ReduxDesc.MinMaxKind);
5137 Reductions[Phi] = RD;
5138 // We've ended the cycle. This is a reduction variable if we have an
5139 // outside user and it has a binary op.
5140
5141 return true;
5142}
5143
5144/// Returns true if the instruction is a Select(ICmp(X, Y), X, Y) instruction
5145/// pattern corresponding to a min(X, Y) or max(X, Y).
5146LoopVectorizationLegality::ReductionInstDesc
5147LoopVectorizationLegality::isMinMaxSelectCmpPattern(Instruction *I,
5148 ReductionInstDesc &Prev) {
5149
5150 assert((isa<ICmpInst>(I) || isa<FCmpInst>(I) || isa<SelectInst>(I)) &&(((isa<ICmpInst>(I) || isa<FCmpInst>(I) || isa<
SelectInst>(I)) && "Expect a select instruction") ?
static_cast<void> (0) : __assert_fail ("(isa<ICmpInst>(I) || isa<FCmpInst>(I) || isa<SelectInst>(I)) && \"Expect a select instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5151, __PRETTY_FUNCTION__))
5151 "Expect a select instruction")(((isa<ICmpInst>(I) || isa<FCmpInst>(I) || isa<
SelectInst>(I)) && "Expect a select instruction") ?
static_cast<void> (0) : __assert_fail ("(isa<ICmpInst>(I) || isa<FCmpInst>(I) || isa<SelectInst>(I)) && \"Expect a select instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5151, __PRETTY_FUNCTION__))
;
5152 Instruction *Cmp = nullptr;
5153 SelectInst *Select = nullptr;
5154
5155 // We must handle the select(cmp()) as a single instruction. Advance to the
5156 // select.
5157 if ((Cmp = dyn_cast<ICmpInst>(I)) || (Cmp = dyn_cast<FCmpInst>(I))) {
5158 if (!Cmp->hasOneUse() || !(Select = dyn_cast<SelectInst>(*I->user_begin())))
5159 return ReductionInstDesc(false, I);
5160 return ReductionInstDesc(Select, Prev.MinMaxKind);
5161 }
5162
5163 // Only handle single use cases for now.
5164 if (!(Select = dyn_cast<SelectInst>(I)))
5165 return ReductionInstDesc(false, I);
5166 if (!(Cmp = dyn_cast<ICmpInst>(I->getOperand(0))) &&
5167 !(Cmp = dyn_cast<FCmpInst>(I->getOperand(0))))
5168 return ReductionInstDesc(false, I);
5169 if (!Cmp->hasOneUse())
5170 return ReductionInstDesc(false, I);
5171
5172 Value *CmpLeft;
5173 Value *CmpRight;
5174
5175 // Look for a min/max pattern.
5176 if (m_UMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
5177 return ReductionInstDesc(Select, MRK_UIntMin);
5178 else if (m_UMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
5179 return ReductionInstDesc(Select, MRK_UIntMax);
5180 else if (m_SMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
5181 return ReductionInstDesc(Select, MRK_SIntMax);
5182 else if (m_SMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
5183 return ReductionInstDesc(Select, MRK_SIntMin);
5184 else if (m_OrdFMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
5185 return ReductionInstDesc(Select, MRK_FloatMin);
5186 else if (m_OrdFMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
5187 return ReductionInstDesc(Select, MRK_FloatMax);
5188 else if (m_UnordFMin(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
5189 return ReductionInstDesc(Select, MRK_FloatMin);
5190 else if (m_UnordFMax(m_Value(CmpLeft), m_Value(CmpRight)).match(Select))
5191 return ReductionInstDesc(Select, MRK_FloatMax);
5192
5193 return ReductionInstDesc(false, I);
5194}
5195
5196LoopVectorizationLegality::ReductionInstDesc
5197LoopVectorizationLegality::isReductionInstr(Instruction *I,
5198 ReductionKind Kind,
5199 ReductionInstDesc &Prev) {
5200 bool FP = I->getType()->isFloatingPointTy();
5201 bool FastMath = FP && I->hasUnsafeAlgebra();
5202 switch (I->getOpcode()) {
5203 default:
5204 return ReductionInstDesc(false, I);
5205 case Instruction::PHI:
5206 if (FP && (Kind != RK_FloatMult && Kind != RK_FloatAdd &&
5207 Kind != RK_FloatMinMax))
5208 return ReductionInstDesc(false, I);
5209 return ReductionInstDesc(I, Prev.MinMaxKind);
5210 case Instruction::Sub:
5211 case Instruction::Add:
5212 return ReductionInstDesc(Kind == RK_IntegerAdd, I);
5213 case Instruction::Mul:
5214 return ReductionInstDesc(Kind == RK_IntegerMult, I);
5215 case Instruction::And:
5216 return ReductionInstDesc(Kind == RK_IntegerAnd, I);
5217 case Instruction::Or:
5218 return ReductionInstDesc(Kind == RK_IntegerOr, I);
5219 case Instruction::Xor:
5220 return ReductionInstDesc(Kind == RK_IntegerXor, I);
5221 case Instruction::FMul:
5222 return ReductionInstDesc(Kind == RK_FloatMult && FastMath, I);
5223 case Instruction::FSub:
5224 case Instruction::FAdd:
5225 return ReductionInstDesc(Kind == RK_FloatAdd && FastMath, I);
5226 case Instruction::FCmp:
5227 case Instruction::ICmp:
5228 case Instruction::Select:
5229 if (Kind != RK_IntegerMinMax &&
5230 (!HasFunNoNaNAttr || Kind != RK_FloatMinMax))
5231 return ReductionInstDesc(false, I);
5232 return isMinMaxSelectCmpPattern(I, Prev);
5233 }
5234}
5235
5236LoopVectorizationLegality::InductionKind
5237LoopVectorizationLegality::isInductionVariable(PHINode *Phi) {
5238 Type *PhiTy = Phi->getType();
5239 // We only handle integer and pointer inductions variables.
5240 if (!PhiTy->isIntegerTy() && !PhiTy->isPointerTy())
5241 return IK_NoInduction;
5242
5243 // Check that the PHI is consecutive.
5244 const SCEV *PhiScev = SE->getSCEV(Phi);
5245 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PhiScev);
5246 if (!AR) {
5247 DEBUG(dbgs() << "LV: PHI is not a poly recurrence.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: PHI is not a poly recurrence.\n"
; } } while (0)
;
5248 return IK_NoInduction;
5249 }
5250 const SCEV *Step = AR->getStepRecurrence(*SE);
5251
5252 // Integer inductions need to have a stride of one.
5253 if (PhiTy->isIntegerTy()) {
5254 if (Step->isOne())
5255 return IK_IntInduction;
5256 if (Step->isAllOnesValue())
5257 return IK_ReverseIntInduction;
5258 return IK_NoInduction;
5259 }
5260
5261 // Calculate the pointer stride and check if it is consecutive.
5262 const SCEVConstant *C = dyn_cast<SCEVConstant>(Step);
5263 if (!C)
5264 return IK_NoInduction;
5265
5266 assert(PhiTy->isPointerTy() && "The PHI must be a pointer")((PhiTy->isPointerTy() && "The PHI must be a pointer"
) ? static_cast<void> (0) : __assert_fail ("PhiTy->isPointerTy() && \"The PHI must be a pointer\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5266, __PRETTY_FUNCTION__))
;
5267 uint64_t Size = DL->getTypeAllocSize(PhiTy->getPointerElementType());
5268 if (C->getValue()->equalsInt(Size))
5269 return IK_PtrInduction;
5270 else if (C->getValue()->equalsInt(0 - Size))
5271 return IK_ReversePtrInduction;
5272
5273 return IK_NoInduction;
5274}
5275
5276bool LoopVectorizationLegality::isInductionVariable(const Value *V) {
5277 Value *In0 = const_cast<Value*>(V);
5278 PHINode *PN = dyn_cast_or_null<PHINode>(In0);
5279 if (!PN)
5280 return false;
5281
5282 return Inductions.count(PN);
5283}
5284
5285bool LoopVectorizationLegality::blockNeedsPredication(BasicBlock *BB) {
5286 assert(TheLoop->contains(BB) && "Unknown block used")((TheLoop->contains(BB) && "Unknown block used") ?
static_cast<void> (0) : __assert_fail ("TheLoop->contains(BB) && \"Unknown block used\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5286, __PRETTY_FUNCTION__))
;
5287
5288 // Blocks that do not dominate the latch need predication.
5289 BasicBlock* Latch = TheLoop->getLoopLatch();
5290 return !DT->dominates(BB, Latch);
5291}
5292
5293bool LoopVectorizationLegality::blockCanBePredicated(BasicBlock *BB,
5294 SmallPtrSetImpl<Value *> &SafePtrs) {
5295 for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
5296 // We might be able to hoist the load.
5297 if (it->mayReadFromMemory()) {
5298 LoadInst *LI = dyn_cast<LoadInst>(it);
5299 if (!LI || !SafePtrs.count(LI->getPointerOperand()))
5300 return false;
5301 }
5302
5303 // We don't predicate stores at the moment.
5304 if (it->mayWriteToMemory()) {
5305 StoreInst *SI = dyn_cast<StoreInst>(it);
5306 // We only support predication of stores in basic blocks with one
5307 // predecessor.
5308 if (!SI || ++NumPredStores > NumberOfStoresToPredicate ||
5309 !SafePtrs.count(SI->getPointerOperand()) ||
5310 !SI->getParent()->getSinglePredecessor())
5311 return false;
5312 }
5313 if (it->mayThrow())
5314 return false;
5315
5316 // Check that we don't have a constant expression that can trap as operand.
5317 for (Instruction::op_iterator OI = it->op_begin(), OE = it->op_end();
5318 OI != OE; ++OI) {
5319 if (Constant *C = dyn_cast<Constant>(*OI))
5320 if (C->canTrap())
5321 return false;
5322 }
5323
5324 // The instructions below can trap.
5325 switch (it->getOpcode()) {
5326 default: continue;
5327 case Instruction::UDiv:
5328 case Instruction::SDiv:
5329 case Instruction::URem:
5330 case Instruction::SRem:
5331 return false;
5332 }
5333 }
5334
5335 return true;
5336}
5337
5338LoopVectorizationCostModel::VectorizationFactor
5339LoopVectorizationCostModel::selectVectorizationFactor(bool OptForSize) {
5340 // Width 1 means no vectorize
5341 VectorizationFactor Factor = { 1U, 0U };
5342 if (OptForSize && Legal->getRuntimePointerCheck()->Need) {
5343 emitAnalysis(Report() << "runtime pointer checks needed. Enable vectorization of this loop with '#pragma clang loop vectorize(enable)' when compiling with -Os");
5344 DEBUG(dbgs() << "LV: Aborting. Runtime ptr check is required in Os.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Aborting. Runtime ptr check is required in Os.\n"
; } } while (0)
;
5345 return Factor;
5346 }
5347
5348 if (!EnableCondStoresVectorization && Legal->NumPredStores) {
5349 emitAnalysis(Report() << "store that is conditionally executed prevents vectorization");
5350 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 (0)
;
5351 return Factor;
5352 }
5353
5354 // Find the trip count.
5355 unsigned TC = SE->getSmallConstantTripCount(TheLoop, TheLoop->getLoopLatch());
5356 DEBUG(dbgs() << "LV: Found trip count: " << TC << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found trip count: "
<< TC << '\n'; } } while (0)
;
5357
5358 unsigned WidestType = getWidestType();
5359 unsigned WidestRegister = TTI.getRegisterBitWidth(true);
5360 unsigned MaxSafeDepDist = -1U;
5361 if (Legal->getMaxSafeDepDistBytes() != -1U)
5362 MaxSafeDepDist = Legal->getMaxSafeDepDistBytes() * 8;
5363 WidestRegister = ((WidestRegister < MaxSafeDepDist) ?
5364 WidestRegister : MaxSafeDepDist);
5365 unsigned MaxVectorSize = WidestRegister / WidestType;
5366 DEBUG(dbgs() << "LV: The Widest type: " << WidestType << " bits.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The Widest type: "
<< WidestType << " bits.\n"; } } while (0)
;
5367 DEBUG(dbgs() << "LV: The Widest register is: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The Widest register is: "
<< WidestRegister << " bits.\n"; } } while (0)
5368 << WidestRegister << " bits.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The Widest register is: "
<< WidestRegister << " bits.\n"; } } while (0)
;
5369
5370 if (MaxVectorSize == 0) {
5371 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 (0)
;
5372 MaxVectorSize = 1;
5373 }
5374
5375 assert(MaxVectorSize <= 32 && "Did not expect to pack so many elements"((MaxVectorSize <= 32 && "Did not expect to pack so many elements"
" into one vector!") ? static_cast<void> (0) : __assert_fail
("MaxVectorSize <= 32 && \"Did not expect to pack so many elements\" \" into one vector!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5376, __PRETTY_FUNCTION__))
5376 " into one vector!")((MaxVectorSize <= 32 && "Did not expect to pack so many elements"
" into one vector!") ? static_cast<void> (0) : __assert_fail
("MaxVectorSize <= 32 && \"Did not expect to pack so many elements\" \" into one vector!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5376, __PRETTY_FUNCTION__))
;
5377
5378 unsigned VF = MaxVectorSize;
5379
5380 // If we optimize the program for size, avoid creating the tail loop.
5381 if (OptForSize) {
5382 // If we are unable to calculate the trip count then don't try to vectorize.
5383 if (TC < 2) {
5384 emitAnalysis(Report() << "unable to calculate the loop count due to complex control flow");
5385 DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Aborting. A tail loop is required in Os.\n"
; } } while (0)
;
5386 return Factor;
5387 }
5388
5389 // Find the maximum SIMD width that can fit within the trip count.
5390 VF = TC % MaxVectorSize;
5391
5392 if (VF == 0)
5393 VF = MaxVectorSize;
5394
5395 // If the trip count that we found modulo the vectorization factor is not
5396 // zero then we require a tail.
5397 if (VF < 2) {
5398 emitAnalysis(Report() << "cannot optimize for size and vectorize at the same time. Enable vectorization of this loop with '#pragma clang loop vectorize(enable)' when compiling with -Os");
5399 DEBUG(dbgs() << "LV: Aborting. A tail loop is required in Os.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Aborting. A tail loop is required in Os.\n"
; } } while (0)
;
5400 return Factor;
5401 }
5402 }
5403
5404 int UserVF = Hints->getWidth();
5405 if (UserVF != 0) {
5406 assert(isPowerOf2_32(UserVF) && "VF needs to be a power of two")((isPowerOf2_32(UserVF) && "VF needs to be a power of two"
) ? static_cast<void> (0) : __assert_fail ("isPowerOf2_32(UserVF) && \"VF needs to be a power of two\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 5406, __PRETTY_FUNCTION__))
;
5407 DEBUG(dbgs() << "LV: Using user VF " << UserVF << ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Using user VF " <<
UserVF << ".\n"; } } while (0)
;
5408
5409 Factor.Width = UserVF;
5410 return Factor;
5411 }
5412
5413 float Cost = expectedCost(1);
5414#ifndef NDEBUG
5415 const float ScalarCost = Cost;
5416#endif /* NDEBUG */
5417 unsigned Width = 1;
5418 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 (0)
;
5419
5420 bool ForceVectorization = Hints->getForce() == LoopVectorizeHints::FK_Enabled;
5421 // Ignore scalar width, because the user explicitly wants vectorization.
5422 if (ForceVectorization && VF > 1) {
5423 Width = 2;
5424 Cost = expectedCost(Width) / (float)Width;
5425 }
5426
5427 for (unsigned i=2; i <= VF; i*=2) {
5428 // Notice that the vector loop needs to be executed less times, so
5429 // we need to divide the cost of the vector loops by the width of
5430 // the vector elements.
5431 float VectorCost = expectedCost(i) / (float)i;
5432 DEBUG(dbgs() << "LV: Vector loop of width " << i << " costs: " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Vector loop of width "
<< i << " costs: " << (int)VectorCost <<
".\n"; } } while (0)
5433 (int)VectorCost << ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Vector loop of width "
<< i << " costs: " << (int)VectorCost <<
".\n"; } } while (0)
;
5434 if (VectorCost < Cost) {
5435 Cost = VectorCost;
5436 Width = i;
5437 }
5438 }
5439
5440 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 (0)
5441 << "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 (0)
5442 << "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 (0)
;
5443 DEBUG(dbgs() << "LV: Selecting VF: "<< Width << ".\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Selecting VF: "<<
Width << ".\n"; } } while (0)
;
5444 Factor.Width = Width;
5445 Factor.Cost = Width * Cost;
5446 return Factor;
5447}
5448
5449unsigned LoopVectorizationCostModel::getWidestType() {
5450 unsigned MaxWidth = 8;
5451
5452 // For each block.
5453 for (Loop::block_iterator bb = TheLoop->block_begin(),
5454 be = TheLoop->block_end(); bb != be; ++bb) {
5455 BasicBlock *BB = *bb;
5456
5457 // For each instruction in the loop.
5458 for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
5459 Type *T = it->getType();
5460
5461 // Only examine Loads, Stores and PHINodes.
5462 if (!isa<LoadInst>(it) && !isa<StoreInst>(it) && !isa<PHINode>(it))
5463 continue;
5464
5465 // Examine PHI nodes that are reduction variables.
5466 if (PHINode *PN = dyn_cast<PHINode>(it))
5467 if (!Legal->getReductionVars()->count(PN))
5468 continue;
5469
5470 // Examine the stored values.
5471 if (StoreInst *ST = dyn_cast<StoreInst>(it))
5472 T = ST->getValueOperand()->getType();
5473
5474 // Ignore loaded pointer types and stored pointer types that are not
5475 // consecutive. However, we do want to take consecutive stores/loads of
5476 // pointer vectors into account.
5477 if (T->isPointerTy() && !isConsecutiveLoadOrStore(it))
5478 continue;
5479
5480 MaxWidth = std::max(MaxWidth,
5481 (unsigned)DL->getTypeSizeInBits(T->getScalarType()));
5482 }
5483 }
5484
5485 return MaxWidth;
5486}
5487
5488unsigned
5489LoopVectorizationCostModel::selectUnrollFactor(bool OptForSize,
5490 unsigned VF,
5491 unsigned LoopCost) {
5492
5493 // -- The unroll heuristics --
5494 // We unroll the loop in order to expose ILP and reduce the loop overhead.
5495 // There are many micro-architectural considerations that we can't predict
5496 // at this level. For example, frontend pressure (on decode or fetch) due to
5497 // code size, or the number and capabilities of the execution ports.
5498 //
5499 // We use the following heuristics to select the unroll factor:
5500 // 1. If the code has reductions, then we unroll in order to break the cross
5501 // iteration dependency.
5502 // 2. If the loop is really small, then we unroll in order to reduce the loop
5503 // overhead.
5504 // 3. We don't unroll if we think that we will spill registers to memory due
5505 // to the increased register pressure.
5506
5507 // Use the user preference, unless 'auto' is selected.
5508 int UserUF = Hints->getInterleave();
5509 if (UserUF != 0)
1
Assuming 'UserUF' is equal to 0
2
Taking false branch
5510 return UserUF;
5511
5512 // When we optimize for size, we don't unroll.
5513 if (OptForSize)
3
Assuming 'OptForSize' is 0
4
Taking false branch
5514 return 1;
5515
5516 // We used the distance for the unroll factor.
5517 if (Legal->getMaxSafeDepDistBytes() != -1U)
5
Taking false branch
5518 return 1;
5519
5520 // Do not unroll loops with a relatively small trip count.
5521 unsigned TC = SE->getSmallConstantTripCount(TheLoop,
5522 TheLoop->getLoopLatch());
5523 if (TC > 1 && TC < TinyTripCountUnrollThreshold)
6
Assuming 'TC' is <= 1
5524 return 1;
5525
5526 unsigned TargetNumRegisters = TTI.getNumberOfRegisters(VF > 1);
7
Assuming 'VF' is <= 1
5527 DEBUG(dbgs() << "LV: The target has " << TargetNumRegisters <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The target has " <<
TargetNumRegisters << " registers\n"; } } while (0)
5528 " registers\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: The target has " <<
TargetNumRegisters << " registers\n"; } } while (0)
;
5529
5530 if (VF == 1) {
8
Assuming 'VF' is not equal to 1
9
Taking false branch
5531 if (ForceTargetNumScalarRegs.getNumOccurrences() > 0)
5532 TargetNumRegisters = ForceTargetNumScalarRegs;
5533 } else {
5534 if (ForceTargetNumVectorRegs.getNumOccurrences() > 0)
10
Taking false branch
5535 TargetNumRegisters = ForceTargetNumVectorRegs;
5536 }
5537
5538 LoopVectorizationCostModel::RegisterUsage R = calculateRegisterUsage();
5539 // We divide by these constants so assume that we have at least one
5540 // instruction that uses at least one register.
5541 R.MaxLocalUsers = std::max(R.MaxLocalUsers, 1U);
5542 R.NumInstructions = std::max(R.NumInstructions, 1U);
5543
5544 // We calculate the unroll factor using the following formula.
5545 // Subtract the number of loop invariants from the number of available
5546 // registers. These registers are used by all of the unrolled instances.
5547 // Next, divide the remaining registers by the number of registers that is
5548 // required by the loop, in order to estimate how many parallel instances
5549 // fit without causing spills. All of this is rounded down if necessary to be
5550 // a power of two. We want power of two unroll factors to simplify any
5551 // addressing operations or alignment considerations.
5552 unsigned UF = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs) /
5553 R.MaxLocalUsers);
5554
5555 // Don't count the induction variable as unrolled.
5556 if (EnableIndVarRegisterHeur)
11
Taking false branch
5557 UF = PowerOf2Floor((TargetNumRegisters - R.LoopInvariantRegs - 1) /
5558 std::max(1U, (R.MaxLocalUsers - 1)));
5559
5560 // Clamp the unroll factor ranges to reasonable factors.
5561 unsigned MaxInterleaveSize = TTI.getMaxInterleaveFactor();
5562
5563 // Check if the user has overridden the unroll max.
5564 if (VF == 1) {
12
Taking false branch
5565 if (ForceTargetMaxScalarInterleaveFactor.getNumOccurrences() > 0)
5566 MaxInterleaveSize = ForceTargetMaxScalarInterleaveFactor;
5567 } else {
5568 if (ForceTargetMaxVectorInterleaveFactor.getNumOccurrences() > 0)
13
Taking false branch
5569 MaxInterleaveSize = ForceTargetMaxVectorInterleaveFactor;
5570 }
5571
5572 // If we did not calculate the cost for VF (because the user selected the VF)
5573 // then we calculate the cost of VF here.
5574 if (LoopCost == 0)
14
Assuming 'LoopCost' is equal to 0
15
Taking true branch
5575 LoopCost = expectedCost(VF);
16
Calling 'LoopVectorizationCostModel::expectedCost'
22
Returning from 'LoopVectorizationCostModel::expectedCost'
23
The value 0 is assigned to 'LoopCost'
5576
5577 // Clamp the calculated UF to be between the 1 and the max unroll factor
5578 // that the target allows.
5579 if (UF > MaxInterleaveSize)
24
Taking false branch
5580 UF = MaxInterleaveSize;
5581 else if (UF < 1)
25
Assuming 'UF' is >= 1
26
Taking false branch
5582 UF = 1;
5583
5584 // Unroll if we vectorized this loop and there is a reduction that could
5585 // benefit from unrolling.
5586 if (VF > 1 && Legal->getReductionVars()->size()) {
5587 DEBUG(dbgs() << "LV: Unrolling because of reductions.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Unrolling because of reductions.\n"
; } } while (0)
;
5588 return UF;
5589 }
5590
5591 // Note that if we've already vectorized the loop we will have done the
5592 // runtime check and so unrolling won't require further checks.
5593 bool UnrollingRequiresRuntimePointerCheck =
5594 (VF == 1 && Legal->getRuntimePointerCheck()->Need);
5595
5596 // We want to unroll small loops in order to reduce the loop overhead and
5597 // potentially expose ILP opportunities.
5598 DEBUG(dbgs() << "LV: Loop cost is " << LoopCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Loop cost is " <<
LoopCost << '\n'; } } while (0)
;
5599 if (!UnrollingRequiresRuntimePointerCheck &&
27
Taking true branch
5600 LoopCost < SmallLoopCost) {
5601 // We assume that the cost overhead is 1 and we use the cost model
5602 // to estimate the cost of the loop and unroll until the cost of the
5603 // loop overhead is about 5% of the cost of the loop.
5604 unsigned SmallUF = std::min(UF, (unsigned)PowerOf2Floor(SmallLoopCost / LoopCost));
28
Division by zero
5605
5606 // Unroll until store/load ports (estimated by max unroll factor) are
5607 // saturated.
5608 unsigned StoresUF = UF / (Legal->NumStores ? Legal->NumStores : 1);
5609 unsigned LoadsUF = UF / (Legal->NumLoads ? Legal->NumLoads : 1);
5610
5611 // If we have a scalar reduction (vector reductions are already dealt with
5612 // by this point), we can increase the critical path length if the loop
5613 // we're unrolling is inside another loop. Limit, by default to 2, so the
5614 // critical path only gets increased by one reduction operation.
5615 if (Legal->getReductionVars()->size() &&
5616 TheLoop->getLoopDepth() > 1) {
5617 unsigned F = static_cast<unsigned>(MaxNestedScalarReductionUF);
5618 SmallUF = std::min(SmallUF, F);
5619 StoresUF = std::min(StoresUF, F);
5620 LoadsUF = std::min(LoadsUF, F);
5621 }
5622
5623 if (EnableLoadStoreRuntimeUnroll && std::max(StoresUF, LoadsUF) > SmallUF) {
5624 DEBUG(dbgs() << "LV: Unrolling to saturate store or load ports.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Unrolling to saturate store or load ports.\n"
; } } while (0)
;
5625 return std::max(StoresUF, LoadsUF);
5626 }
5627
5628 DEBUG(dbgs() << "LV: Unrolling to reduce branch cost.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Unrolling to reduce branch cost.\n"
; } } while (0)
;
5629 return SmallUF;
5630 }
5631
5632 DEBUG(dbgs() << "LV: Not Unrolling.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Not Unrolling.\n";
} } while (0)
;
5633 return 1;
5634}
5635
5636LoopVectorizationCostModel::RegisterUsage
5637LoopVectorizationCostModel::calculateRegisterUsage() {
5638 // This function calculates the register usage by measuring the highest number
5639 // of values that are alive at a single location. Obviously, this is a very
5640 // rough estimation. We scan the loop in a topological order in order and
5641 // assign a number to each instruction. We use RPO to ensure that defs are
5642 // met before their users. We assume that each instruction that has in-loop
5643 // users starts an interval. We record every time that an in-loop value is
5644 // used, so we have a list of the first and last occurrences of each
5645 // instruction. Next, we transpose this data structure into a multi map that
5646 // holds the list of intervals that *end* at a specific location. This multi
5647 // map allows us to perform a linear search. We scan the instructions linearly
5648 // and record each time that a new interval starts, by placing it in a set.
5649 // If we find this value in the multi-map then we remove it from the set.
5650 // The max register usage is the maximum size of the set.
5651 // We also search for instructions that are defined outside the loop, but are
5652 // used inside the loop. We need this number separately from the max-interval
5653 // usage number because when we unroll, loop-invariant values do not take
5654 // more register.
5655 LoopBlocksDFS DFS(TheLoop);
5656 DFS.perform(LI);
5657
5658 RegisterUsage R;
5659 R.NumInstructions = 0;
5660
5661 // Each 'key' in the map opens a new interval. The values
5662 // of the map are the index of the 'last seen' usage of the
5663 // instruction that is the key.
5664 typedef DenseMap<Instruction*, unsigned> IntervalMap;
5665 // Maps instruction to its index.
5666 DenseMap<unsigned, Instruction*> IdxToInstr;
5667 // Marks the end of each interval.
5668 IntervalMap EndPoint;
5669 // Saves the list of instruction indices that are used in the loop.
5670 SmallSet<Instruction*, 8> Ends;
5671 // Saves the list of values that are used in the loop but are
5672 // defined outside the loop, such as arguments and constants.
5673 SmallPtrSet<Value*, 8> LoopInvariants;
5674
5675 unsigned Index = 0;
5676 for (LoopBlocksDFS::RPOIterator bb = DFS.beginRPO(),
5677 be = DFS.endRPO(); bb != be; ++bb) {
5678 R.NumInstructions += (*bb)->size();
5679 for (BasicBlock::iterator it = (*bb)->begin(), e = (*bb)->end(); it != e;
5680 ++it) {
5681 Instruction *I = it;
5682 IdxToInstr[Index++] = I;
5683
5684 // Save the end location of each USE.
5685 for (unsigned i = 0; i < I->getNumOperands(); ++i) {
5686 Value *U = I->getOperand(i);
5687 Instruction *Instr = dyn_cast<Instruction>(U);
5688
5689 // Ignore non-instruction values such as arguments, constants, etc.
5690 if (!Instr) continue;
5691
5692 // If this instruction is outside the loop then record it and continue.
5693 if (!TheLoop->contains(Instr)) {
5694 LoopInvariants.insert(Instr);
5695 continue;
5696 }
5697
5698 // Overwrite previous end points.
5699 EndPoint[Instr] = Index;
5700 Ends.insert(Instr);
5701 }
5702 }
5703 }
5704
5705 // Saves the list of intervals that end with the index in 'key'.
5706 typedef SmallVector<Instruction*, 2> InstrList;
5707 DenseMap<unsigned, InstrList> TransposeEnds;
5708
5709 // Transpose the EndPoints to a list of values that end at each index.
5710 for (IntervalMap::iterator it = EndPoint.begin(), e = EndPoint.end();
5711 it != e; ++it)
5712 TransposeEnds[it->second].push_back(it->first);
5713
5714 SmallSet<Instruction*, 8> OpenIntervals;
5715 unsigned MaxUsage = 0;
5716
5717
5718 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 (0)
;
5719 for (unsigned int i = 0; i < Index; ++i) {
5720 Instruction *I = IdxToInstr[i];
5721 // Ignore instructions that are never used within the loop.
5722 if (!Ends.count(I)) continue;
5723
5724 // Remove all of the instructions that end at this location.
5725 InstrList &List = TransposeEnds[i];
5726 for (unsigned int j=0, e = List.size(); j < e; ++j)
5727 OpenIntervals.erase(List[j]);
5728
5729 // Count the number of live interals.
5730 MaxUsage = std::max(MaxUsage, OpenIntervals.size());
5731
5732 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 (0)
5733 OpenIntervals.size() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): At #" <<
i << " Interval # " << OpenIntervals.size() <<
'\n'; } } while (0)
;
5734
5735 // Add the current instruction to the list of open intervals.
5736 OpenIntervals.insert(I);
5737 }
5738
5739 unsigned Invariant = LoopInvariants.size();
5740 DEBUG(dbgs() << "LV(REG): Found max usage: " << MaxUsage << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): Found max usage: "
<< MaxUsage << '\n'; } } while (0)
;
5741 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 (0)
;
5742 DEBUG(dbgs() << "LV(REG): LoopSize: " << R.NumInstructions << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV(REG): LoopSize: " <<
R.NumInstructions << '\n'; } } while (0)
;
5743
5744 R.LoopInvariantRegs = Invariant;
5745 R.MaxLocalUsers = MaxUsage;
5746 return R;
5747}
5748
5749unsigned LoopVectorizationCostModel::expectedCost(unsigned VF) {
5750 unsigned Cost = 0;
17
'Cost' initialized to 0
5751
5752 // For each block.
5753 for (Loop::block_iterator bb = TheLoop->block_begin(),
20
Loop condition is false. Execution continues on line 5784
5754 be = TheLoop->block_end(); bb != be; ++bb) {
18
Calling 'operator!='
19
Returning from 'operator!='
5755 unsigned BlockCost = 0;
5756 BasicBlock *BB = *bb;
5757
5758 // For each instruction in the old loop.
5759 for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
5760 // Skip dbg intrinsics.
5761 if (isa<DbgInfoIntrinsic>(it))
5762 continue;
5763
5764 unsigned C = getInstructionCost(it, VF);
5765
5766 // Check if we should override the cost.
5767 if (ForceTargetInstructionCost.getNumOccurrences() > 0)
5768 C = ForceTargetInstructionCost;
5769
5770 BlockCost += C;
5771 DEBUG(dbgs() << "LV: Found an estimated cost of " << C << " for VF " <<do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an estimated cost of "
<< C << " for VF " << VF << " For instruction: "
<< *it << '\n'; } } while (0)
5772 VF << " For instruction: " << *it << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-vectorize")) { dbgs() << "LV: Found an estimated cost of "
<< C << " for VF " << VF << " For instruction: "
<< *it << '\n'; } } while (0)
;
5773 }
5774
5775 // We assume that if-converted blocks have a 50% chance of being executed.
5776 // When the code is scalar then some of the blocks are avoided due to CF.
5777 // When the code is vectorized we execute all code paths.
5778 if (VF == 1 && Legal->blockNeedsPredication(*bb))
5779 BlockCost /= 2;
5780
5781 Cost += BlockCost;
5782 }
5783
5784 return Cost;
21
Returning zero (loaded from 'Cost')
5785}
5786
5787/// \brief Check whether the address computation for a non-consecutive memory
5788/// access looks like an unlikely candidate for being merged into the indexing
5789/// mode.
5790///
5791/// We look for a GEP which has one index that is an induction variable and all
5792/// other indices are loop invariant. If the stride of this access is also
5793/// within a small bound we decide that this address computation can likely be
5794/// merged into the addressing mode.
5795/// In all other cases, we identify the address computation as complex.
5796static bool isLikelyComplexAddressComputation(Value *Ptr,
5797 LoopVectorizationLegality *Legal,
5798 ScalarEvolution *SE,
5799 const Loop *TheLoop) {
5800 GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(Ptr);
5801 if (!Gep)
5802 return true;
5803
5804 // We are looking for a gep with all loop invariant indices except for one
5805 // which should be an induction variable.
5806 unsigned NumOperands = Gep->getNumOperands();
5807 for (unsigned i = 1; i < NumOperands; ++i) {
5808 Value *Opd = Gep->getOperand(i);
5809 if (!SE->isLoopInvariant(SE->getSCEV(Opd), TheLoop) &&
5810 !Legal->isInductionVariable(Opd))
5811 return true;
5812 }
5813
5814 // Now we know we have a GEP ptr, %inv, %ind, %inv. Make sure that the step
5815 // can likely be merged into the address computation.
5816 unsigned MaxMergeDistance = 64;
5817
5818 const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Ptr));
5819 if (!AddRec)
5820 return true;
5821
5822 // Check the step is constant.
5823 const SCEV *Step = AddRec->getStepRecurrence(*SE);
5824 // Calculate the pointer stride and check if it is consecutive.
5825 const SCEVConstant *C = dyn_cast<SCEVConstant>(Step);
5826 if (!C)
5827 return true;
5828
5829 const APInt &APStepVal = C->getValue()->getValue();
5830
5831 // Huge step value - give up.
5832 if (APStepVal.getBitWidth() > 64)
5833 return true;
5834
5835 int64_t StepVal = APStepVal.getSExtValue();
5836
5837 return StepVal > MaxMergeDistance;
5838}
5839
5840static bool isStrideMul(Instruction *I, LoopVectorizationLegality *Legal) {
5841 if (Legal->hasStride(I->getOperand(0)) || Legal->hasStride(I->getOperand(1)))
5842 return true;
5843 return false;
5844}
5845
5846unsigned
5847LoopVectorizationCostModel::getInstructionCost(Instruction *I, unsigned VF) {
5848 // If we know that this instruction will remain uniform, check the cost of
5849 // the scalar version.
5850 if (Legal->isUniformAfterVectorization(I))
5851 VF = 1;
5852
5853 Type *RetTy = I->getType();
5854 Type *VectorTy = ToVectorTy(RetTy, VF);
5855
5856 // TODO: We need to estimate the cost of intrinsic calls.
5857 switch (I->getOpcode()) {
5858 case Instruction::GetElementPtr:
5859 // We mark this instruction as zero-cost because the cost of GEPs in
5860 // vectorized code depends on whether the corresponding memory instruction
5861 // is scalarized or not. Therefore, we handle GEPs with the memory
5862 // instruction cost.
5863 return 0;
5864 case Instruction::Br: {
5865 return TTI.getCFInstrCost(I->getOpcode());
5866 }
5867 case Instruction::PHI:
5868 //TODO: IF-converted IFs become selects.
5869 return 0;
5870 case Instruction::Add:
5871 case Instruction::FAdd:
5872 case Instruction::Sub:
5873 case Instruction::FSub:
5874 case Instruction::Mul:
5875 case Instruction::FMul:
5876 case Instruction::UDiv:
5877 case Instruction::SDiv:
5878 case Instruction::FDiv:
5879 case Instruction::URem:
5880 case Instruction::SRem:
5881 case Instruction::FRem:
5882 case Instruction::Shl:
5883 case Instruction::LShr:
5884 case Instruction::AShr:
5885 case Instruction::And:
5886 case Instruction::Or:
5887 case Instruction::Xor: {
5888 // Since we will replace the stride by 1 the multiplication should go away.
5889 if (I->getOpcode() == Instruction::Mul && isStrideMul(I, Legal))
5890 return 0;
5891 // Certain instructions can be cheaper to vectorize if they have a constant
5892 // second vector operand. One example of this are shifts on x86.
5893 TargetTransformInfo::OperandValueKind Op1VK =
5894 TargetTransformInfo::OK_AnyValue;
5895 TargetTransformInfo::OperandValueKind Op2VK =
5896 TargetTransformInfo::OK_AnyValue;
5897 TargetTransformInfo::OperandValueProperties Op1VP =
5898 TargetTransformInfo::OP_None;
5899 TargetTransformInfo::OperandValueProperties Op2VP =
5900 TargetTransformInfo::OP_None;
5901 Value *Op2 = I->getOperand(1);
5902
5903 // Check for a splat of a constant or for a non uniform vector of constants.
5904 if (isa<ConstantInt>(Op2)) {
5905 ConstantInt *CInt = cast<ConstantInt>(Op2);
5906 if (CInt && CInt->getValue().isPowerOf2())
5907 Op2VP = TargetTransformInfo::OP_PowerOf2;
5908 Op2VK = TargetTransformInfo::OK_UniformConstantValue;
5909 } else if (isa<ConstantVector>(Op2) || isa<ConstantDataVector>(Op2)) {
5910 Op2VK = TargetTransformInfo::OK_NonUniformConstantValue;
5911 Constant *SplatValue = cast<Constant>(Op2)->getSplatValue();
5912 if (SplatValue) {
5913 ConstantInt *CInt = dyn_cast<ConstantInt>(SplatValue);
5914 if (CInt && CInt->getValue().isPowerOf2())
5915 Op2VP = TargetTransformInfo::OP_PowerOf2;
5916 Op2VK = TargetTransformInfo::OK_UniformConstantValue;
5917 }
5918 }
5919
5920 return TTI.getArithmeticInstrCost(I->getOpcode(), VectorTy, Op1VK, Op2VK,
5921 Op1VP, Op2VP);
5922 }
5923 case Instruction::Select: {
5924 SelectInst *SI = cast<SelectInst>(I);
5925 const SCEV *CondSCEV = SE->getSCEV(SI->getCondition());
5926 bool ScalarCond = (SE->isLoopInvariant(CondSCEV, TheLoop));
5927 Type *CondTy = SI->getCondition()->getType();
5928 if (!ScalarCond)
5929 CondTy = VectorType::get(CondTy, VF);
5930
5931 return TTI.getCmpSelInstrCost(I->getOpcode(), VectorTy, CondTy);
5932 }
5933 case Instruction::ICmp:
5934 case Instruction::FCmp: {
5935 Type *ValTy = I->getOperand(0)->getType();
5936 VectorTy = ToVectorTy(ValTy, VF);
5937 return TTI.getCmpSelInstrCost(I->getOpcode(), VectorTy);
5938 }
5939 case Instruction::Store:
5940 case Instruction::Load: {
5941 StoreInst *SI = dyn_cast<StoreInst>(I);
5942 LoadInst *LI = dyn_cast<LoadInst>(I);
5943 Type *ValTy = (SI ? SI->getValueOperand()->getType() :
5944 LI->getType());
5945 VectorTy = ToVectorTy(ValTy, VF);
5946
5947 unsigned Alignment = SI ? SI->getAlignment() : LI->getAlignment();
5948 unsigned AS = SI ? SI->getPointerAddressSpace() :
5949 LI->getPointerAddressSpace();
5950 Value *Ptr = SI ? SI->getPointerOperand() : LI->getPointerOperand();
5951 // We add the cost of address computation here instead of with the gep
5952 // instruction because only here we know whether the operation is
5953 // scalarized.
5954 if (VF == 1)
5955 return TTI.getAddressComputationCost(VectorTy) +
5956 TTI.getMemoryOpCost(I->getOpcode(), VectorTy, Alignment, AS);
5957
5958 // Scalarized loads/stores.
5959 int ConsecutiveStride = Legal->isConsecutivePtr(Ptr);
5960 bool Reverse = ConsecutiveStride < 0;
5961 unsigned ScalarAllocatedSize = DL->getTypeAllocSize(ValTy);
5962 unsigned VectorElementSize = DL->getTypeStoreSize(VectorTy)/VF;
5963 if (!ConsecutiveStride || ScalarAllocatedSize != VectorElementSize) {
5964 bool IsComplexComputation =
5965 isLikelyComplexAddressComputation(Ptr, Legal, SE, TheLoop);
5966 unsigned Cost = 0;
5967 // The cost of extracting from the value vector and pointer vector.
5968 Type *PtrTy = ToVectorTy(Ptr->getType(), VF);
5969 for (unsigned i = 0; i < VF; ++i) {
5970 // The cost of extracting the pointer operand.
5971 Cost += TTI.getVectorInstrCost(Instruction::ExtractElement, PtrTy, i);
5972 // In case of STORE, the cost of ExtractElement from the vector.
5973 // In case of LOAD, the cost of InsertElement into the returned
5974 // vector.
5975 Cost += TTI.getVectorInstrCost(SI ? Instruction::ExtractElement :
5976 Instruction::InsertElement,
5977 VectorTy, i);
5978 }
5979
5980 // The cost of the scalar loads/stores.
5981 Cost += VF * TTI.getAddressComputationCost(PtrTy, IsComplexComputation);
5982 Cost += VF * TTI.getMemoryOpCost(I->getOpcode(), ValTy->getScalarType(),
5983 Alignment, AS);
5984 return Cost;
5985 }
5986
5987 // Wide load/stores.
5988 unsigned Cost = TTI.getAddressComputationCost(VectorTy);
5989 Cost += TTI.getMemoryOpCost(I->getOpcode(), VectorTy, Alignment, AS);
5990
5991 if (Reverse)
5992 Cost += TTI.getShuffleCost(TargetTransformInfo::SK_Reverse,
5993 VectorTy, 0);
5994 return Cost;
5995 }
5996 case Instruction::ZExt:
5997 case Instruction::SExt:
5998 case Instruction::FPToUI:
5999 case Instruction::FPToSI:
6000 case Instruction::FPExt:
6001 case Instruction::PtrToInt:
6002 case Instruction::IntToPtr:
6003 case Instruction::SIToFP:
6004 case Instruction::UIToFP:
6005 case Instruction::Trunc:
6006 case Instruction::FPTrunc:
6007 case Instruction::BitCast: {
6008 // We optimize the truncation of induction variable.
6009 // The cost of these is the same as the scalar operation.
6010 if (I->getOpcode() == Instruction::Trunc &&
6011 Legal->isInductionVariable(I->getOperand(0)))
6012 return TTI.getCastInstrCost(I->getOpcode(), I->getType(),
6013 I->getOperand(0)->getType());
6014
6015 Type *SrcVecTy = ToVectorTy(I->getOperand(0)->getType(), VF);
6016 return TTI.getCastInstrCost(I->getOpcode(), VectorTy, SrcVecTy);
6017 }
6018 case Instruction::Call: {
6019 CallInst *CI = cast<CallInst>(I);
6020 Intrinsic::ID ID = getIntrinsicIDForCall(CI, TLI);
6021 assert(ID && "Not an intrinsic call!")((ID && "Not an intrinsic call!") ? static_cast<void
> (0) : __assert_fail ("ID && \"Not an intrinsic call!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6021, __PRETTY_FUNCTION__))
;
6022 Type *RetTy = ToVectorTy(CI->getType(), VF);
6023 SmallVector<Type*, 4> Tys;
6024 for (unsigned i = 0, ie = CI->getNumArgOperands(); i != ie; ++i)
6025 Tys.push_back(ToVectorTy(CI->getArgOperand(i)->getType(), VF));
6026 return TTI.getIntrinsicInstrCost(ID, RetTy, Tys);
6027 }
6028 default: {
6029 // We are scalarizing the instruction. Return the cost of the scalar
6030 // instruction, plus the cost of insert and extract into vector
6031 // elements, times the vector width.
6032 unsigned Cost = 0;
6033
6034 if (!RetTy->isVoidTy() && VF != 1) {
6035 unsigned InsCost = TTI.getVectorInstrCost(Instruction::InsertElement,
6036 VectorTy);
6037 unsigned ExtCost = TTI.getVectorInstrCost(Instruction::ExtractElement,
6038 VectorTy);
6039
6040 // The cost of inserting the results plus extracting each one of the
6041 // operands.
6042 Cost += VF * (InsCost + ExtCost * I->getNumOperands());
6043 }
6044
6045 // The cost of executing VF copies of the scalar instruction. This opcode
6046 // is unknown. Assume that it is the same as 'mul'.
6047 Cost += VF * TTI.getArithmeticInstrCost(Instruction::Mul, VectorTy);
6048 return Cost;
6049 }
6050 }// end of switch.
6051}
6052
6053Type* LoopVectorizationCostModel::ToVectorTy(Type *Scalar, unsigned VF) {
6054 if (Scalar->isVoidTy() || VF == 1)
6055 return Scalar;
6056 return VectorType::get(Scalar, VF);
6057}
6058
6059char LoopVectorize::ID = 0;
6060static const char lv_name[] = "Loop Vectorization";
6061INITIALIZE_PASS_BEGIN(LoopVectorize, LV_NAME, lv_name, false, false)static void* initializeLoopVectorizePassOnce(PassRegistry &
Registry) {
6062INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)initializeTargetTransformInfoAnalysisGroup(Registry);
6063INITIALIZE_AG_DEPENDENCY(AliasAnalysis)initializeAliasAnalysisAnalysisGroup(Registry);
6064INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfo)initializeBlockFrequencyInfoPass(Registry);
6065INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
6066INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)initializeScalarEvolutionPass(Registry);
6067INITIALIZE_PASS_DEPENDENCY(LCSSA)initializeLCSSAPass(Registry);
6068INITIALIZE_PASS_DEPENDENCY(LoopInfo)initializeLoopInfoPass(Registry);
6069INITIALIZE_PASS_DEPENDENCY(LoopSimplify)initializeLoopSimplifyPass(Registry);
6070INITIALIZE_PASS_END(LoopVectorize, LV_NAME, lv_name, false, false)PassInfo *PI = new PassInfo(lv_name, "loop-vectorize", & LoopVectorize
::ID, PassInfo::NormalCtor_t(callDefaultCtor< LoopVectorize
>), false, false); Registry.registerPass(*PI, true); return
PI; } void llvm::initializeLoopVectorizePass(PassRegistry &
Registry) { static volatile sys::cas_flag initialized = 0; sys
::cas_flag old_val = sys::CompareAndSwap(&initialized, 1,
0); if (old_val == 0) { initializeLoopVectorizePassOnce(Registry
); sys::MemoryFence(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6070); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6070, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6070); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6070, &initialized); }
6071
6072namespace llvm {
6073 Pass *createLoopVectorizePass(bool NoUnrolling, bool AlwaysVectorize) {
6074 return new LoopVectorize(NoUnrolling, AlwaysVectorize);
6075 }
6076}
6077
6078bool LoopVectorizationCostModel::isConsecutiveLoadOrStore(Instruction *Inst) {
6079 // Check for a store.
6080 if (StoreInst *ST = dyn_cast<StoreInst>(Inst))
6081 return Legal->isConsecutivePtr(ST->getPointerOperand()) != 0;
6082
6083 // Check for a load.
6084 if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
6085 return Legal->isConsecutivePtr(LI->getPointerOperand()) != 0;
6086
6087 return false;
6088}
6089
6090
6091void InnerLoopUnroller::scalarizeInstruction(Instruction *Instr,
6092 bool IfPredicateStore) {
6093 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-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6093, __PRETTY_FUNCTION__))
;
6094 // Holds vector parameters or scalars, in case of uniform vals.
6095 SmallVector<VectorParts, 4> Params;
6096
6097 setDebugLocFromInst(Builder, Instr);
6098
6099 // Find all of the vectorized parameters.
6100 for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) {
6101 Value *SrcOp = Instr->getOperand(op);
6102
6103 // If we are accessing the old induction variable, use the new one.
6104 if (SrcOp == OldInduction) {
6105 Params.push_back(getVectorValue(SrcOp));
6106 continue;
6107 }
6108
6109 // Try using previously calculated values.
6110 Instruction *SrcInst = dyn_cast<Instruction>(SrcOp);
6111
6112 // If the src is an instruction that appeared earlier in the basic block
6113 // then it should already be vectorized.
6114 if (SrcInst && OrigLoop->contains(SrcInst)) {
6115 assert(WidenMap.has(SrcInst) && "Source operand is unavailable")((WidenMap.has(SrcInst) && "Source operand is unavailable"
) ? static_cast<void> (0) : __assert_fail ("WidenMap.has(SrcInst) && \"Source operand is unavailable\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6115, __PRETTY_FUNCTION__))
;
6116 // The parameter is a vector value from earlier.
6117 Params.push_back(WidenMap.get(SrcInst));
6118 } else {
6119 // The parameter is a scalar from outside the loop. Maybe even a constant.
6120 VectorParts Scalars;
6121 Scalars.append(UF, SrcOp);
6122 Params.push_back(Scalars);
6123 }
6124 }
6125
6126 assert(Params.size() == Instr->getNumOperands() &&((Params.size() == Instr->getNumOperands() && "Invalid number of operands"
) ? static_cast<void> (0) : __assert_fail ("Params.size() == Instr->getNumOperands() && \"Invalid number of operands\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6127, __PRETTY_FUNCTION__))
6127 "Invalid number of operands")((Params.size() == Instr->getNumOperands() && "Invalid number of operands"
) ? static_cast<void> (0) : __assert_fail ("Params.size() == Instr->getNumOperands() && \"Invalid number of operands\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6127, __PRETTY_FUNCTION__))
;
6128
6129 // Does this instruction return a value ?
6130 bool IsVoidRetTy = Instr->getType()->isVoidTy();
6131
6132 Value *UndefVec = IsVoidRetTy ? nullptr :
6133 UndefValue::get(Instr->getType());
6134 // Create a new entry in the WidenMap and initialize it to Undef or Null.
6135 VectorParts &VecResults = WidenMap.splat(Instr, UndefVec);
6136
6137 Instruction *InsertPt = Builder.GetInsertPoint();
6138 BasicBlock *IfBlock = Builder.GetInsertBlock();
6139 BasicBlock *CondBlock = nullptr;
6140
6141 VectorParts Cond;
6142 Loop *VectorLp = nullptr;
6143 if (IfPredicateStore) {
6144 assert(Instr->getParent()->getSinglePredecessor() &&((Instr->getParent()->getSinglePredecessor() &&
"Only support single predecessor blocks") ? static_cast<void
> (0) : __assert_fail ("Instr->getParent()->getSinglePredecessor() && \"Only support single predecessor blocks\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6145, __PRETTY_FUNCTION__))
6145 "Only support single predecessor blocks")((Instr->getParent()->getSinglePredecessor() &&
"Only support single predecessor blocks") ? static_cast<void
> (0) : __assert_fail ("Instr->getParent()->getSinglePredecessor() && \"Only support single predecessor blocks\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6145, __PRETTY_FUNCTION__))
;
6146 Cond = createEdgeMask(Instr->getParent()->getSinglePredecessor(),
6147 Instr->getParent());
6148 VectorLp = LI->getLoopFor(IfBlock);
6149 assert(VectorLp && "Must have a loop for this block")((VectorLp && "Must have a loop for this block") ? static_cast
<void> (0) : __assert_fail ("VectorLp && \"Must have a loop for this block\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6149, __PRETTY_FUNCTION__))
;
6150 }
6151
6152 // For each vector unroll 'part':
6153 for (unsigned Part = 0; Part < UF; ++Part) {
6154 // For each scalar that we create:
6155
6156 // Start an "if (pred) a[i] = ..." block.
6157 Value *Cmp = nullptr;
6158 if (IfPredicateStore) {
6159 if (Cond[Part]->getType()->isVectorTy())
6160 Cond[Part] =
6161 Builder.CreateExtractElement(Cond[Part], Builder.getInt32(0));
6162 Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, Cond[Part],
6163 ConstantInt::get(Cond[Part]->getType(), 1));
6164 CondBlock = IfBlock->splitBasicBlock(InsertPt, "cond.store");
6165 LoopVectorBody.push_back(CondBlock);
6166 VectorLp->addBasicBlockToLoop(CondBlock, LI->getBase());
6167 // Update Builder with newly created basic block.
6168 Builder.SetInsertPoint(InsertPt);
6169 }
6170
6171 Instruction *Cloned = Instr->clone();
6172 if (!IsVoidRetTy)
6173 Cloned->setName(Instr->getName() + ".cloned");
6174 // Replace the operands of the cloned instructions with extracted scalars.
6175 for (unsigned op = 0, e = Instr->getNumOperands(); op != e; ++op) {
6176 Value *Op = Params[op][Part];
6177 Cloned->setOperand(op, Op);
6178 }
6179
6180 // Place the cloned scalar in the new loop.
6181 Builder.Insert(Cloned);
6182
6183 // If the original scalar returns a value we need to place it in a vector
6184 // so that future users will be able to use it.
6185 if (!IsVoidRetTy)
6186 VecResults[Part] = Cloned;
6187
6188 // End if-block.
6189 if (IfPredicateStore) {
6190 BasicBlock *NewIfBlock = CondBlock->splitBasicBlock(InsertPt, "else");
6191 LoopVectorBody.push_back(NewIfBlock);
6192 VectorLp->addBasicBlockToLoop(NewIfBlock, LI->getBase());
6193 Builder.SetInsertPoint(InsertPt);
6194 Instruction *OldBr = IfBlock->getTerminator();
6195 BranchInst::Create(CondBlock, NewIfBlock, Cmp, OldBr);
6196 OldBr->eraseFromParent();
6197 IfBlock = NewIfBlock;
6198 }
6199 }
6200}
6201
6202void InnerLoopUnroller::vectorizeMemoryInstruction(Instruction *Instr) {
6203 StoreInst *SI = dyn_cast<StoreInst>(Instr);
6204 bool IfPredicateStore = (SI && Legal->blockNeedsPredication(SI->getParent()));
6205
6206 return scalarizeInstruction(Instr, IfPredicateStore);
6207}
6208
6209Value *InnerLoopUnroller::reverseVector(Value *Vec) {
6210 return Vec;
6211}
6212
6213Value *InnerLoopUnroller::getBroadcastInstrs(Value *V) {
6214 return V;
6215}
6216
6217Value *InnerLoopUnroller::getConsecutiveVector(Value* Val, int StartIdx,
6218 bool Negate) {
6219 // When unrolling and the VF is 1, we only need to add a simple scalar.
6220 Type *ITy = Val->getType();
6221 assert(!ITy->isVectorTy() && "Val must be a scalar")((!ITy->isVectorTy() && "Val must be a scalar") ? static_cast
<void> (0) : __assert_fail ("!ITy->isVectorTy() && \"Val must be a scalar\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.6~svn219049/lib/Transforms/Vectorize/LoopVectorize.cpp"
, 6221, __PRETTY_FUNCTION__))
;
6222 Constant *C = ConstantInt::get(ITy, StartIdx, Negate);
6223 return Builder.CreateAdd(Val, C, "induction");
6224}