Bug Summary

File:lib/Transforms/Scalar/LoopStrengthReduce.cpp
Location:line 4691, column 22
Description:Called C++ object pointer is null

Annotated Source Code

1//===- LoopStrengthReduce.cpp - Strength Reduce IVs in Loops --------------===//
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 transformation analyzes and transforms the induction variables (and
11// computations derived from them) into forms suitable for efficient execution
12// on the target.
13//
14// This pass performs a strength reduction on array references inside loops that
15// have as one or more of their components the loop induction variable, it
16// rewrites expressions to take advantage of scaled-index addressing modes
17// available on the target, and it performs a variety of other optimizations
18// related to loop induction variables.
19//
20// Terminology note: this code has a lot of handling for "post-increment" or
21// "post-inc" users. This is not talking about post-increment addressing modes;
22// it is instead talking about code like this:
23//
24// %i = phi [ 0, %entry ], [ %i.next, %latch ]
25// ...
26// %i.next = add %i, 1
27// %c = icmp eq %i.next, %n
28//
29// The SCEV for %i is {0,+,1}<%L>. The SCEV for %i.next is {1,+,1}<%L>, however
30// it's useful to think about these as the same register, with some uses using
31// the value of the register before the add and some using it after. In this
32// example, the icmp is a post-increment user, since it uses %i.next, which is
33// the value of the induction variable after the increment. The other common
34// case of post-increment users is users outside the loop.
35//
36// TODO: More sophistication in the way Formulae are generated and filtered.
37//
38// TODO: Handle multiple loops at a time.
39//
40// TODO: Should the addressing mode BaseGV be changed to a ConstantExpr instead
41// of a GlobalValue?
42//
43// TODO: When truncation is free, truncate ICmp users' operands to make it a
44// smaller encoding (on x86 at least).
45//
46// TODO: When a negated register is used by an add (such as in a list of
47// multiple base registers, or as the increment expression in an addrec),
48// we may not actually need both reg and (-1 * reg) in registers; the
49// negation can be implemented by using a sub instead of an add. The
50// lack of support for taking this into consideration when making
51// register pressure decisions is partly worked around by the "Special"
52// use kind.
53//
54//===----------------------------------------------------------------------===//
55
56#include "llvm/Transforms/Scalar.h"
57#include "llvm/ADT/DenseSet.h"
58#include "llvm/ADT/Hashing.h"
59#include "llvm/ADT/STLExtras.h"
60#include "llvm/ADT/SetVector.h"
61#include "llvm/ADT/SmallBitVector.h"
62#include "llvm/Analysis/IVUsers.h"
63#include "llvm/Analysis/LoopPass.h"
64#include "llvm/Analysis/ScalarEvolutionExpander.h"
65#include "llvm/Analysis/TargetTransformInfo.h"
66#include "llvm/IR/Constants.h"
67#include "llvm/IR/DerivedTypes.h"
68#include "llvm/IR/Dominators.h"
69#include "llvm/IR/Instructions.h"
70#include "llvm/IR/IntrinsicInst.h"
71#include "llvm/IR/Module.h"
72#include "llvm/IR/ValueHandle.h"
73#include "llvm/Support/CommandLine.h"
74#include "llvm/Support/Debug.h"
75#include "llvm/Support/raw_ostream.h"
76#include "llvm/Transforms/Utils/BasicBlockUtils.h"
77#include "llvm/Transforms/Utils/Local.h"
78#include <algorithm>
79using namespace llvm;
80
81#define DEBUG_TYPE"loop-reduce" "loop-reduce"
82
83/// MaxIVUsers is an arbitrary threshold that provides an early opportunitiy for
84/// bail out. This threshold is far beyond the number of users that LSR can
85/// conceivably solve, so it should not affect generated code, but catches the
86/// worst cases before LSR burns too much compile time and stack space.
87static const unsigned MaxIVUsers = 200;
88
89// Temporary flag to cleanup congruent phis after LSR phi expansion.
90// It's currently disabled until we can determine whether it's truly useful or
91// not. The flag should be removed after the v3.0 release.
92// This is now needed for ivchains.
93static cl::opt<bool> EnablePhiElim(
94 "enable-lsr-phielim", cl::Hidden, cl::init(true),
95 cl::desc("Enable LSR phi elimination"));
96
97#ifndef NDEBUG
98// Stress test IV chain generation.
99static cl::opt<bool> StressIVChain(
100 "stress-ivchain", cl::Hidden, cl::init(false),
101 cl::desc("Stress test LSR IV chains"));
102#else
103static bool StressIVChain = false;
104#endif
105
106namespace {
107
108/// RegSortData - This class holds data which is used to order reuse candidates.
109class RegSortData {
110public:
111 /// UsedByIndices - This represents the set of LSRUse indices which reference
112 /// a particular register.
113 SmallBitVector UsedByIndices;
114
115 void print(raw_ostream &OS) const;
116 void dump() const;
117};
118
119}
120
121void RegSortData::print(raw_ostream &OS) const {
122 OS << "[NumUses=" << UsedByIndices.count() << ']';
123}
124
125#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
126void RegSortData::dump() const {
127 print(errs()); errs() << '\n';
128}
129#endif
130
131namespace {
132
133/// RegUseTracker - Map register candidates to information about how they are
134/// used.
135class RegUseTracker {
136 typedef DenseMap<const SCEV *, RegSortData> RegUsesTy;
137
138 RegUsesTy RegUsesMap;
139 SmallVector<const SCEV *, 16> RegSequence;
140
141public:
142 void CountRegister(const SCEV *Reg, size_t LUIdx);
143 void DropRegister(const SCEV *Reg, size_t LUIdx);
144 void SwapAndDropUse(size_t LUIdx, size_t LastLUIdx);
145
146 bool isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const;
147
148 const SmallBitVector &getUsedByIndices(const SCEV *Reg) const;
149
150 void clear();
151
152 typedef SmallVectorImpl<const SCEV *>::iterator iterator;
153 typedef SmallVectorImpl<const SCEV *>::const_iterator const_iterator;
154 iterator begin() { return RegSequence.begin(); }
155 iterator end() { return RegSequence.end(); }
156 const_iterator begin() const { return RegSequence.begin(); }
157 const_iterator end() const { return RegSequence.end(); }
158};
159
160}
161
162void
163RegUseTracker::CountRegister(const SCEV *Reg, size_t LUIdx) {
164 std::pair<RegUsesTy::iterator, bool> Pair =
165 RegUsesMap.insert(std::make_pair(Reg, RegSortData()));
166 RegSortData &RSD = Pair.first->second;
167 if (Pair.second)
168 RegSequence.push_back(Reg);
169 RSD.UsedByIndices.resize(std::max(RSD.UsedByIndices.size(), LUIdx + 1));
170 RSD.UsedByIndices.set(LUIdx);
171}
172
173void
174RegUseTracker::DropRegister(const SCEV *Reg, size_t LUIdx) {
175 RegUsesTy::iterator It = RegUsesMap.find(Reg);
176 assert(It != RegUsesMap.end())((It != RegUsesMap.end()) ? static_cast<void> (0) : __assert_fail
("It != RegUsesMap.end()", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 176, __PRETTY_FUNCTION__))
;
177 RegSortData &RSD = It->second;
178 assert(RSD.UsedByIndices.size() > LUIdx)((RSD.UsedByIndices.size() > LUIdx) ? static_cast<void>
(0) : __assert_fail ("RSD.UsedByIndices.size() > LUIdx", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 178, __PRETTY_FUNCTION__))
;
179 RSD.UsedByIndices.reset(LUIdx);
180}
181
182void
183RegUseTracker::SwapAndDropUse(size_t LUIdx, size_t LastLUIdx) {
184 assert(LUIdx <= LastLUIdx)((LUIdx <= LastLUIdx) ? static_cast<void> (0) : __assert_fail
("LUIdx <= LastLUIdx", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 184, __PRETTY_FUNCTION__))
;
185
186 // Update RegUses. The data structure is not optimized for this purpose;
187 // we must iterate through it and update each of the bit vectors.
188 for (auto &Pair : RegUsesMap) {
189 SmallBitVector &UsedByIndices = Pair.second.UsedByIndices;
190 if (LUIdx < UsedByIndices.size())
191 UsedByIndices[LUIdx] =
192 LastLUIdx < UsedByIndices.size() ? UsedByIndices[LastLUIdx] : 0;
193 UsedByIndices.resize(std::min(UsedByIndices.size(), LastLUIdx));
194 }
195}
196
197bool
198RegUseTracker::isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const {
199 RegUsesTy::const_iterator I = RegUsesMap.find(Reg);
200 if (I == RegUsesMap.end())
201 return false;
202 const SmallBitVector &UsedByIndices = I->second.UsedByIndices;
203 int i = UsedByIndices.find_first();
204 if (i == -1) return false;
205 if ((size_t)i != LUIdx) return true;
206 return UsedByIndices.find_next(i) != -1;
207}
208
209const SmallBitVector &RegUseTracker::getUsedByIndices(const SCEV *Reg) const {
210 RegUsesTy::const_iterator I = RegUsesMap.find(Reg);
211 assert(I != RegUsesMap.end() && "Unknown register!")((I != RegUsesMap.end() && "Unknown register!") ? static_cast
<void> (0) : __assert_fail ("I != RegUsesMap.end() && \"Unknown register!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 211, __PRETTY_FUNCTION__))
;
212 return I->second.UsedByIndices;
213}
214
215void RegUseTracker::clear() {
216 RegUsesMap.clear();
217 RegSequence.clear();
218}
219
220namespace {
221
222/// Formula - This class holds information that describes a formula for
223/// computing satisfying a use. It may include broken-out immediates and scaled
224/// registers.
225struct Formula {
226 /// Global base address used for complex addressing.
227 GlobalValue *BaseGV;
228
229 /// Base offset for complex addressing.
230 int64_t BaseOffset;
231
232 /// Whether any complex addressing has a base register.
233 bool HasBaseReg;
234
235 /// The scale of any complex addressing.
236 int64_t Scale;
237
238 /// BaseRegs - The list of "base" registers for this use. When this is
239 /// non-empty. The canonical representation of a formula is
240 /// 1. BaseRegs.size > 1 implies ScaledReg != NULL and
241 /// 2. ScaledReg != NULL implies Scale != 1 || !BaseRegs.empty().
242 /// #1 enforces that the scaled register is always used when at least two
243 /// registers are needed by the formula: e.g., reg1 + reg2 is reg1 + 1 * reg2.
244 /// #2 enforces that 1 * reg is reg.
245 /// This invariant can be temporarly broken while building a formula.
246 /// However, every formula inserted into the LSRInstance must be in canonical
247 /// form.
248 SmallVector<const SCEV *, 4> BaseRegs;
249
250 /// ScaledReg - The 'scaled' register for this use. This should be non-null
251 /// when Scale is not zero.
252 const SCEV *ScaledReg;
253
254 /// UnfoldedOffset - An additional constant offset which added near the
255 /// use. This requires a temporary register, but the offset itself can
256 /// live in an add immediate field rather than a register.
257 int64_t UnfoldedOffset;
258
259 Formula()
260 : BaseGV(nullptr), BaseOffset(0), HasBaseReg(false), Scale(0),
261 ScaledReg(nullptr), UnfoldedOffset(0) {}
262
263 void InitialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE);
264
265 bool isCanonical() const;
266
267 void Canonicalize();
268
269 bool Unscale();
270
271 size_t getNumRegs() const;
272 Type *getType() const;
273
274 void DeleteBaseReg(const SCEV *&S);
275
276 bool referencesReg(const SCEV *S) const;
277 bool hasRegsUsedByUsesOtherThan(size_t LUIdx,
278 const RegUseTracker &RegUses) const;
279
280 void print(raw_ostream &OS) const;
281 void dump() const;
282};
283
284}
285
286/// DoInitialMatch - Recursion helper for InitialMatch.
287static void DoInitialMatch(const SCEV *S, Loop *L,
288 SmallVectorImpl<const SCEV *> &Good,
289 SmallVectorImpl<const SCEV *> &Bad,
290 ScalarEvolution &SE) {
291 // Collect expressions which properly dominate the loop header.
292 if (SE.properlyDominates(S, L->getHeader())) {
293 Good.push_back(S);
294 return;
295 }
296
297 // Look at add operands.
298 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
299 for (const SCEV *S : Add->operands())
300 DoInitialMatch(S, L, Good, Bad, SE);
301 return;
302 }
303
304 // Look at addrec operands.
305 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
306 if (!AR->getStart()->isZero()) {
307 DoInitialMatch(AR->getStart(), L, Good, Bad, SE);
308 DoInitialMatch(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0),
309 AR->getStepRecurrence(SE),
310 // FIXME: AR->getNoWrapFlags()
311 AR->getLoop(), SCEV::FlagAnyWrap),
312 L, Good, Bad, SE);
313 return;
314 }
315
316 // Handle a multiplication by -1 (negation) if it didn't fold.
317 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S))
318 if (Mul->getOperand(0)->isAllOnesValue()) {
319 SmallVector<const SCEV *, 4> Ops(Mul->op_begin()+1, Mul->op_end());
320 const SCEV *NewMul = SE.getMulExpr(Ops);
321
322 SmallVector<const SCEV *, 4> MyGood;
323 SmallVector<const SCEV *, 4> MyBad;
324 DoInitialMatch(NewMul, L, MyGood, MyBad, SE);
325 const SCEV *NegOne = SE.getSCEV(ConstantInt::getAllOnesValue(
326 SE.getEffectiveSCEVType(NewMul->getType())));
327 for (const SCEV *S : MyGood)
328 Good.push_back(SE.getMulExpr(NegOne, S));
329 for (const SCEV *S : MyBad)
330 Bad.push_back(SE.getMulExpr(NegOne, S));
331 return;
332 }
333
334 // Ok, we can't do anything interesting. Just stuff the whole thing into a
335 // register and hope for the best.
336 Bad.push_back(S);
337}
338
339/// InitialMatch - Incorporate loop-variant parts of S into this Formula,
340/// attempting to keep all loop-invariant and loop-computable values in a
341/// single base register.
342void Formula::InitialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE) {
343 SmallVector<const SCEV *, 4> Good;
344 SmallVector<const SCEV *, 4> Bad;
345 DoInitialMatch(S, L, Good, Bad, SE);
346 if (!Good.empty()) {
347 const SCEV *Sum = SE.getAddExpr(Good);
348 if (!Sum->isZero())
349 BaseRegs.push_back(Sum);
350 HasBaseReg = true;
351 }
352 if (!Bad.empty()) {
353 const SCEV *Sum = SE.getAddExpr(Bad);
354 if (!Sum->isZero())
355 BaseRegs.push_back(Sum);
356 HasBaseReg = true;
357 }
358 Canonicalize();
359}
360
361/// \brief Check whether or not this formula statisfies the canonical
362/// representation.
363/// \see Formula::BaseRegs.
364bool Formula::isCanonical() const {
365 if (ScaledReg)
366 return Scale != 1 || !BaseRegs.empty();
367 return BaseRegs.size() <= 1;
368}
369
370/// \brief Helper method to morph a formula into its canonical representation.
371/// \see Formula::BaseRegs.
372/// Every formula having more than one base register, must use the ScaledReg
373/// field. Otherwise, we would have to do special cases everywhere in LSR
374/// to treat reg1 + reg2 + ... the same way as reg1 + 1*reg2 + ...
375/// On the other hand, 1*reg should be canonicalized into reg.
376void Formula::Canonicalize() {
377 if (isCanonical())
378 return;
379 // So far we did not need this case. This is easy to implement but it is
380 // useless to maintain dead code. Beside it could hurt compile time.
381 assert(!BaseRegs.empty() && "1*reg => reg, should not be needed.")((!BaseRegs.empty() && "1*reg => reg, should not be needed."
) ? static_cast<void> (0) : __assert_fail ("!BaseRegs.empty() && \"1*reg => reg, should not be needed.\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 381, __PRETTY_FUNCTION__))
;
382 // Keep the invariant sum in BaseRegs and one of the variant sum in ScaledReg.
383 ScaledReg = BaseRegs.back();
384 BaseRegs.pop_back();
385 Scale = 1;
386 size_t BaseRegsSize = BaseRegs.size();
387 size_t Try = 0;
388 // If ScaledReg is an invariant, try to find a variant expression.
389 while (Try < BaseRegsSize && !isa<SCEVAddRecExpr>(ScaledReg))
390 std::swap(ScaledReg, BaseRegs[Try++]);
391}
392
393/// \brief Get rid of the scale in the formula.
394/// In other words, this method morphes reg1 + 1*reg2 into reg1 + reg2.
395/// \return true if it was possible to get rid of the scale, false otherwise.
396/// \note After this operation the formula may not be in the canonical form.
397bool Formula::Unscale() {
398 if (Scale != 1)
399 return false;
400 Scale = 0;
401 BaseRegs.push_back(ScaledReg);
402 ScaledReg = nullptr;
403 return true;
404}
405
406/// getNumRegs - Return the total number of register operands used by this
407/// formula. This does not include register uses implied by non-constant
408/// addrec strides.
409size_t Formula::getNumRegs() const {
410 return !!ScaledReg + BaseRegs.size();
411}
412
413/// getType - Return the type of this formula, if it has one, or null
414/// otherwise. This type is meaningless except for the bit size.
415Type *Formula::getType() const {
416 return !BaseRegs.empty() ? BaseRegs.front()->getType() :
417 ScaledReg ? ScaledReg->getType() :
418 BaseGV ? BaseGV->getType() :
419 nullptr;
420}
421
422/// DeleteBaseReg - Delete the given base reg from the BaseRegs list.
423void Formula::DeleteBaseReg(const SCEV *&S) {
424 if (&S != &BaseRegs.back())
425 std::swap(S, BaseRegs.back());
426 BaseRegs.pop_back();
427}
428
429/// referencesReg - Test if this formula references the given register.
430bool Formula::referencesReg(const SCEV *S) const {
431 return S == ScaledReg ||
432 std::find(BaseRegs.begin(), BaseRegs.end(), S) != BaseRegs.end();
433}
434
435/// hasRegsUsedByUsesOtherThan - Test whether this formula uses registers
436/// which are used by uses other than the use with the given index.
437bool Formula::hasRegsUsedByUsesOtherThan(size_t LUIdx,
438 const RegUseTracker &RegUses) const {
439 if (ScaledReg)
440 if (RegUses.isRegUsedByUsesOtherThan(ScaledReg, LUIdx))
441 return true;
442 for (const SCEV *BaseReg : BaseRegs)
443 if (RegUses.isRegUsedByUsesOtherThan(BaseReg, LUIdx))
444 return true;
445 return false;
446}
447
448void Formula::print(raw_ostream &OS) const {
449 bool First = true;
450 if (BaseGV) {
451 if (!First) OS << " + "; else First = false;
452 BaseGV->printAsOperand(OS, /*PrintType=*/false);
453 }
454 if (BaseOffset != 0) {
455 if (!First) OS << " + "; else First = false;
456 OS << BaseOffset;
457 }
458 for (const SCEV *BaseReg : BaseRegs) {
459 if (!First) OS << " + "; else First = false;
460 OS << "reg(" << *BaseReg << ')';
461 }
462 if (HasBaseReg && BaseRegs.empty()) {
463 if (!First) OS << " + "; else First = false;
464 OS << "**error: HasBaseReg**";
465 } else if (!HasBaseReg && !BaseRegs.empty()) {
466 if (!First) OS << " + "; else First = false;
467 OS << "**error: !HasBaseReg**";
468 }
469 if (Scale != 0) {
470 if (!First) OS << " + "; else First = false;
471 OS << Scale << "*reg(";
472 if (ScaledReg)
473 OS << *ScaledReg;
474 else
475 OS << "<unknown>";
476 OS << ')';
477 }
478 if (UnfoldedOffset != 0) {
479 if (!First) OS << " + ";
480 OS << "imm(" << UnfoldedOffset << ')';
481 }
482}
483
484#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
485void Formula::dump() const {
486 print(errs()); errs() << '\n';
487}
488#endif
489
490/// isAddRecSExtable - Return true if the given addrec can be sign-extended
491/// without changing its value.
492static bool isAddRecSExtable(const SCEVAddRecExpr *AR, ScalarEvolution &SE) {
493 Type *WideTy =
494 IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(AR->getType()) + 1);
495 return isa<SCEVAddRecExpr>(SE.getSignExtendExpr(AR, WideTy));
496}
497
498/// isAddSExtable - Return true if the given add can be sign-extended
499/// without changing its value.
500static bool isAddSExtable(const SCEVAddExpr *A, ScalarEvolution &SE) {
501 Type *WideTy =
502 IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(A->getType()) + 1);
503 return isa<SCEVAddExpr>(SE.getSignExtendExpr(A, WideTy));
504}
505
506/// isMulSExtable - Return true if the given mul can be sign-extended
507/// without changing its value.
508static bool isMulSExtable(const SCEVMulExpr *M, ScalarEvolution &SE) {
509 Type *WideTy =
510 IntegerType::get(SE.getContext(),
511 SE.getTypeSizeInBits(M->getType()) * M->getNumOperands());
512 return isa<SCEVMulExpr>(SE.getSignExtendExpr(M, WideTy));
513}
514
515/// getExactSDiv - Return an expression for LHS /s RHS, if it can be determined
516/// and if the remainder is known to be zero, or null otherwise. If
517/// IgnoreSignificantBits is true, expressions like (X * Y) /s Y are simplified
518/// to Y, ignoring that the multiplication may overflow, which is useful when
519/// the result will be used in a context where the most significant bits are
520/// ignored.
521static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS,
522 ScalarEvolution &SE,
523 bool IgnoreSignificantBits = false) {
524 // Handle the trivial case, which works for any SCEV type.
525 if (LHS == RHS)
526 return SE.getConstant(LHS->getType(), 1);
527
528 // Handle a few RHS special cases.
529 const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS);
530 if (RC) {
531 const APInt &RA = RC->getValue()->getValue();
532 // Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do
533 // some folding.
534 if (RA.isAllOnesValue())
535 return SE.getMulExpr(LHS, RC);
536 // Handle x /s 1 as x.
537 if (RA == 1)
538 return LHS;
539 }
540
541 // Check for a division of a constant by a constant.
542 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(LHS)) {
543 if (!RC)
544 return nullptr;
545 const APInt &LA = C->getValue()->getValue();
546 const APInt &RA = RC->getValue()->getValue();
547 if (LA.srem(RA) != 0)
548 return nullptr;
549 return SE.getConstant(LA.sdiv(RA));
550 }
551
552 // Distribute the sdiv over addrec operands, if the addrec doesn't overflow.
553 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) {
554 if (IgnoreSignificantBits || isAddRecSExtable(AR, SE)) {
555 const SCEV *Step = getExactSDiv(AR->getStepRecurrence(SE), RHS, SE,
556 IgnoreSignificantBits);
557 if (!Step) return nullptr;
558 const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE,
559 IgnoreSignificantBits);
560 if (!Start) return nullptr;
561 // FlagNW is independent of the start value, step direction, and is
562 // preserved with smaller magnitude steps.
563 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
564 return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap);
565 }
566 return nullptr;
567 }
568
569 // Distribute the sdiv over add operands, if the add doesn't overflow.
570 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(LHS)) {
571 if (IgnoreSignificantBits || isAddSExtable(Add, SE)) {
572 SmallVector<const SCEV *, 8> Ops;
573 for (const SCEV *S : Add->operands()) {
574 const SCEV *Op = getExactSDiv(S, RHS, SE, IgnoreSignificantBits);
575 if (!Op) return nullptr;
576 Ops.push_back(Op);
577 }
578 return SE.getAddExpr(Ops);
579 }
580 return nullptr;
581 }
582
583 // Check for a multiply operand that we can pull RHS out of.
584 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS)) {
585 if (IgnoreSignificantBits || isMulSExtable(Mul, SE)) {
586 SmallVector<const SCEV *, 4> Ops;
587 bool Found = false;
588 for (const SCEV *S : Mul->operands()) {
589 if (!Found)
590 if (const SCEV *Q = getExactSDiv(S, RHS, SE,
591 IgnoreSignificantBits)) {
592 S = Q;
593 Found = true;
594 }
595 Ops.push_back(S);
596 }
597 return Found ? SE.getMulExpr(Ops) : nullptr;
598 }
599 return nullptr;
600 }
601
602 // Otherwise we don't know.
603 return nullptr;
604}
605
606/// ExtractImmediate - If S involves the addition of a constant integer value,
607/// return that integer value, and mutate S to point to a new SCEV with that
608/// value excluded.
609static int64_t ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) {
610 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
611 if (C->getValue()->getValue().getMinSignedBits() <= 64) {
612 S = SE.getConstant(C->getType(), 0);
613 return C->getValue()->getSExtValue();
614 }
615 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
616 SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
617 int64_t Result = ExtractImmediate(NewOps.front(), SE);
618 if (Result != 0)
619 S = SE.getAddExpr(NewOps);
620 return Result;
621 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
622 SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
623 int64_t Result = ExtractImmediate(NewOps.front(), SE);
624 if (Result != 0)
625 S = SE.getAddRecExpr(NewOps, AR->getLoop(),
626 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
627 SCEV::FlagAnyWrap);
628 return Result;
629 }
630 return 0;
631}
632
633/// ExtractSymbol - If S involves the addition of a GlobalValue address,
634/// return that symbol, and mutate S to point to a new SCEV with that
635/// value excluded.
636static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) {
637 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
638 if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) {
639 S = SE.getConstant(GV->getType(), 0);
640 return GV;
641 }
642 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
643 SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
644 GlobalValue *Result = ExtractSymbol(NewOps.back(), SE);
645 if (Result)
646 S = SE.getAddExpr(NewOps);
647 return Result;
648 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
649 SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
650 GlobalValue *Result = ExtractSymbol(NewOps.front(), SE);
651 if (Result)
652 S = SE.getAddRecExpr(NewOps, AR->getLoop(),
653 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
654 SCEV::FlagAnyWrap);
655 return Result;
656 }
657 return nullptr;
658}
659
660/// isAddressUse - Returns true if the specified instruction is using the
661/// specified value as an address.
662static bool isAddressUse(Instruction *Inst, Value *OperandVal) {
663 bool isAddress = isa<LoadInst>(Inst);
664 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
665 if (SI->getOperand(1) == OperandVal)
666 isAddress = true;
667 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
668 // Addressing modes can also be folded into prefetches and a variety
669 // of intrinsics.
670 switch (II->getIntrinsicID()) {
671 default: break;
672 case Intrinsic::prefetch:
673 case Intrinsic::x86_sse_storeu_ps:
674 case Intrinsic::x86_sse2_storeu_pd:
675 case Intrinsic::x86_sse2_storeu_dq:
676 case Intrinsic::x86_sse2_storel_dq:
677 if (II->getArgOperand(0) == OperandVal)
678 isAddress = true;
679 break;
680 }
681 }
682 return isAddress;
683}
684
685/// getAccessType - Return the type of the memory being accessed.
686static Type *getAccessType(const Instruction *Inst) {
687 Type *AccessTy = Inst->getType();
688 if (const StoreInst *SI = dyn_cast<StoreInst>(Inst))
689 AccessTy = SI->getOperand(0)->getType();
690 else if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
691 // Addressing modes can also be folded into prefetches and a variety
692 // of intrinsics.
693 switch (II->getIntrinsicID()) {
694 default: break;
695 case Intrinsic::x86_sse_storeu_ps:
696 case Intrinsic::x86_sse2_storeu_pd:
697 case Intrinsic::x86_sse2_storeu_dq:
698 case Intrinsic::x86_sse2_storel_dq:
699 AccessTy = II->getArgOperand(0)->getType();
700 break;
701 }
702 }
703
704 // All pointers have the same requirements, so canonicalize them to an
705 // arbitrary pointer type to minimize variation.
706 if (PointerType *PTy = dyn_cast<PointerType>(AccessTy))
707 AccessTy = PointerType::get(IntegerType::get(PTy->getContext(), 1),
708 PTy->getAddressSpace());
709
710 return AccessTy;
711}
712
713/// isExistingPhi - Return true if this AddRec is already a phi in its loop.
714static bool isExistingPhi(const SCEVAddRecExpr *AR, ScalarEvolution &SE) {
715 for (BasicBlock::iterator I = AR->getLoop()->getHeader()->begin();
716 PHINode *PN = dyn_cast<PHINode>(I); ++I) {
717 if (SE.isSCEVable(PN->getType()) &&
718 (SE.getEffectiveSCEVType(PN->getType()) ==
719 SE.getEffectiveSCEVType(AR->getType())) &&
720 SE.getSCEV(PN) == AR)
721 return true;
722 }
723 return false;
724}
725
726/// Check if expanding this expression is likely to incur significant cost. This
727/// is tricky because SCEV doesn't track which expressions are actually computed
728/// by the current IR.
729///
730/// We currently allow expansion of IV increments that involve adds,
731/// multiplication by constants, and AddRecs from existing phis.
732///
733/// TODO: Allow UDivExpr if we can find an existing IV increment that is an
734/// obvious multiple of the UDivExpr.
735static bool isHighCostExpansion(const SCEV *S,
736 SmallPtrSetImpl<const SCEV*> &Processed,
737 ScalarEvolution &SE) {
738 // Zero/One operand expressions
739 switch (S->getSCEVType()) {
740 case scUnknown:
741 case scConstant:
742 return false;
743 case scTruncate:
744 return isHighCostExpansion(cast<SCEVTruncateExpr>(S)->getOperand(),
745 Processed, SE);
746 case scZeroExtend:
747 return isHighCostExpansion(cast<SCEVZeroExtendExpr>(S)->getOperand(),
748 Processed, SE);
749 case scSignExtend:
750 return isHighCostExpansion(cast<SCEVSignExtendExpr>(S)->getOperand(),
751 Processed, SE);
752 }
753
754 if (!Processed.insert(S).second)
755 return false;
756
757 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
758 for (const SCEV *S : Add->operands()) {
759 if (isHighCostExpansion(S, Processed, SE))
760 return true;
761 }
762 return false;
763 }
764
765 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
766 if (Mul->getNumOperands() == 2) {
767 // Multiplication by a constant is ok
768 if (isa<SCEVConstant>(Mul->getOperand(0)))
769 return isHighCostExpansion(Mul->getOperand(1), Processed, SE);
770
771 // If we have the value of one operand, check if an existing
772 // multiplication already generates this expression.
773 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Mul->getOperand(1))) {
774 Value *UVal = U->getValue();
775 for (User *UR : UVal->users()) {
776 // If U is a constant, it may be used by a ConstantExpr.
777 Instruction *UI = dyn_cast<Instruction>(UR);
778 if (UI && UI->getOpcode() == Instruction::Mul &&
779 SE.isSCEVable(UI->getType())) {
780 return SE.getSCEV(UI) == Mul;
781 }
782 }
783 }
784 }
785 }
786
787 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
788 if (isExistingPhi(AR, SE))
789 return false;
790 }
791
792 // Fow now, consider any other type of expression (div/mul/min/max) high cost.
793 return true;
794}
795
796/// DeleteTriviallyDeadInstructions - If any of the instructions is the
797/// specified set are trivially dead, delete them and see if this makes any of
798/// their operands subsequently dead.
799static bool
800DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakVH> &DeadInsts) {
801 bool Changed = false;
802
803 while (!DeadInsts.empty()) {
804 Value *V = DeadInsts.pop_back_val();
805 Instruction *I = dyn_cast_or_null<Instruction>(V);
806
807 if (!I || !isInstructionTriviallyDead(I))
808 continue;
809
810 for (Use &O : I->operands())
811 if (Instruction *U = dyn_cast<Instruction>(O)) {
812 O = nullptr;
813 if (U->use_empty())
814 DeadInsts.emplace_back(U);
815 }
816
817 I->eraseFromParent();
818 Changed = true;
819 }
820
821 return Changed;
822}
823
824namespace {
825class LSRUse;
826}
827
828/// \brief Check if the addressing mode defined by \p F is completely
829/// folded in \p LU at isel time.
830/// This includes address-mode folding and special icmp tricks.
831/// This function returns true if \p LU can accommodate what \p F
832/// defines and up to 1 base + 1 scaled + offset.
833/// In other words, if \p F has several base registers, this function may
834/// still return true. Therefore, users still need to account for
835/// additional base registers and/or unfolded offsets to derive an
836/// accurate cost model.
837static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
838 const LSRUse &LU, const Formula &F);
839// Get the cost of the scaling factor used in F for LU.
840static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,
841 const LSRUse &LU, const Formula &F);
842
843namespace {
844
845/// Cost - This class is used to measure and compare candidate formulae.
846class Cost {
847 /// TODO: Some of these could be merged. Also, a lexical ordering
848 /// isn't always optimal.
849 unsigned NumRegs;
850 unsigned AddRecCost;
851 unsigned NumIVMuls;
852 unsigned NumBaseAdds;
853 unsigned ImmCost;
854 unsigned SetupCost;
855 unsigned ScaleCost;
856
857public:
858 Cost()
859 : NumRegs(0), AddRecCost(0), NumIVMuls(0), NumBaseAdds(0), ImmCost(0),
860 SetupCost(0), ScaleCost(0) {}
861
862 bool operator<(const Cost &Other) const;
863
864 void Lose();
865
866#ifndef NDEBUG
867 // Once any of the metrics loses, they must all remain losers.
868 bool isValid() {
869 return ((NumRegs | AddRecCost | NumIVMuls | NumBaseAdds
870 | ImmCost | SetupCost | ScaleCost) != ~0u)
871 || ((NumRegs & AddRecCost & NumIVMuls & NumBaseAdds
872 & ImmCost & SetupCost & ScaleCost) == ~0u);
873 }
874#endif
875
876 bool isLoser() {
877 assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 877, __PRETTY_FUNCTION__))
;
878 return NumRegs == ~0u;
879 }
880
881 void RateFormula(const TargetTransformInfo &TTI,
882 const Formula &F,
883 SmallPtrSetImpl<const SCEV *> &Regs,
884 const DenseSet<const SCEV *> &VisitedRegs,
885 const Loop *L,
886 const SmallVectorImpl<int64_t> &Offsets,
887 ScalarEvolution &SE, DominatorTree &DT,
888 const LSRUse &LU,
889 SmallPtrSetImpl<const SCEV *> *LoserRegs = nullptr);
890
891 void print(raw_ostream &OS) const;
892 void dump() const;
893
894private:
895 void RateRegister(const SCEV *Reg,
896 SmallPtrSetImpl<const SCEV *> &Regs,
897 const Loop *L,
898 ScalarEvolution &SE, DominatorTree &DT);
899 void RatePrimaryRegister(const SCEV *Reg,
900 SmallPtrSetImpl<const SCEV *> &Regs,
901 const Loop *L,
902 ScalarEvolution &SE, DominatorTree &DT,
903 SmallPtrSetImpl<const SCEV *> *LoserRegs);
904};
905
906}
907
908/// RateRegister - Tally up interesting quantities from the given register.
909void Cost::RateRegister(const SCEV *Reg,
910 SmallPtrSetImpl<const SCEV *> &Regs,
911 const Loop *L,
912 ScalarEvolution &SE, DominatorTree &DT) {
913 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg)) {
914 // If this is an addrec for another loop, don't second-guess its addrec phi
915 // nodes. LSR isn't currently smart enough to reason about more than one
916 // loop at a time. LSR has already run on inner loops, will not run on outer
917 // loops, and cannot be expected to change sibling loops.
918 if (AR->getLoop() != L) {
919 // If the AddRec exists, consider it's register free and leave it alone.
920 if (isExistingPhi(AR, SE))
921 return;
922
923 // Otherwise, do not consider this formula at all.
924 Lose();
925 return;
926 }
927 AddRecCost += 1; /// TODO: This should be a function of the stride.
928
929 // Add the step value register, if it needs one.
930 // TODO: The non-affine case isn't precisely modeled here.
931 if (!AR->isAffine() || !isa<SCEVConstant>(AR->getOperand(1))) {
932 if (!Regs.count(AR->getOperand(1))) {
933 RateRegister(AR->getOperand(1), Regs, L, SE, DT);
934 if (isLoser())
935 return;
936 }
937 }
938 }
939 ++NumRegs;
940
941 // Rough heuristic; favor registers which don't require extra setup
942 // instructions in the preheader.
943 if (!isa<SCEVUnknown>(Reg) &&
944 !isa<SCEVConstant>(Reg) &&
945 !(isa<SCEVAddRecExpr>(Reg) &&
946 (isa<SCEVUnknown>(cast<SCEVAddRecExpr>(Reg)->getStart()) ||
947 isa<SCEVConstant>(cast<SCEVAddRecExpr>(Reg)->getStart()))))
948 ++SetupCost;
949
950 NumIVMuls += isa<SCEVMulExpr>(Reg) &&
951 SE.hasComputableLoopEvolution(Reg, L);
952}
953
954/// RatePrimaryRegister - Record this register in the set. If we haven't seen it
955/// before, rate it. Optional LoserRegs provides a way to declare any formula
956/// that refers to one of those regs an instant loser.
957void Cost::RatePrimaryRegister(const SCEV *Reg,
958 SmallPtrSetImpl<const SCEV *> &Regs,
959 const Loop *L,
960 ScalarEvolution &SE, DominatorTree &DT,
961 SmallPtrSetImpl<const SCEV *> *LoserRegs) {
962 if (LoserRegs && LoserRegs->count(Reg)) {
963 Lose();
964 return;
965 }
966 if (Regs.insert(Reg).second) {
967 RateRegister(Reg, Regs, L, SE, DT);
968 if (LoserRegs && isLoser())
969 LoserRegs->insert(Reg);
970 }
971}
972
973void Cost::RateFormula(const TargetTransformInfo &TTI,
974 const Formula &F,
975 SmallPtrSetImpl<const SCEV *> &Regs,
976 const DenseSet<const SCEV *> &VisitedRegs,
977 const Loop *L,
978 const SmallVectorImpl<int64_t> &Offsets,
979 ScalarEvolution &SE, DominatorTree &DT,
980 const LSRUse &LU,
981 SmallPtrSetImpl<const SCEV *> *LoserRegs) {
982 assert(F.isCanonical() && "Cost is accurate only for canonical formula")((F.isCanonical() && "Cost is accurate only for canonical formula"
) ? static_cast<void> (0) : __assert_fail ("F.isCanonical() && \"Cost is accurate only for canonical formula\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 982, __PRETTY_FUNCTION__))
;
983 // Tally up the registers.
984 if (const SCEV *ScaledReg = F.ScaledReg) {
985 if (VisitedRegs.count(ScaledReg)) {
986 Lose();
987 return;
988 }
989 RatePrimaryRegister(ScaledReg, Regs, L, SE, DT, LoserRegs);
990 if (isLoser())
991 return;
992 }
993 for (const SCEV *BaseReg : F.BaseRegs) {
994 if (VisitedRegs.count(BaseReg)) {
995 Lose();
996 return;
997 }
998 RatePrimaryRegister(BaseReg, Regs, L, SE, DT, LoserRegs);
999 if (isLoser())
1000 return;
1001 }
1002
1003 // Determine how many (unfolded) adds we'll need inside the loop.
1004 size_t NumBaseParts = F.getNumRegs();
1005 if (NumBaseParts > 1)
1006 // Do not count the base and a possible second register if the target
1007 // allows to fold 2 registers.
1008 NumBaseAdds +=
1009 NumBaseParts - (1 + (F.Scale && isAMCompletelyFolded(TTI, LU, F)));
1010 NumBaseAdds += (F.UnfoldedOffset != 0);
1011
1012 // Accumulate non-free scaling amounts.
1013 ScaleCost += getScalingFactorCost(TTI, LU, F);
1014
1015 // Tally up the non-zero immediates.
1016 for (int64_t O : Offsets) {
1017 int64_t Offset = (uint64_t)O + F.BaseOffset;
1018 if (F.BaseGV)
1019 ImmCost += 64; // Handle symbolic values conservatively.
1020 // TODO: This should probably be the pointer size.
1021 else if (Offset != 0)
1022 ImmCost += APInt(64, Offset, true).getMinSignedBits();
1023 }
1024 assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1024, __PRETTY_FUNCTION__))
;
1025}
1026
1027/// Lose - Set this cost to a losing value.
1028void Cost::Lose() {
1029 NumRegs = ~0u;
1030 AddRecCost = ~0u;
1031 NumIVMuls = ~0u;
1032 NumBaseAdds = ~0u;
1033 ImmCost = ~0u;
1034 SetupCost = ~0u;
1035 ScaleCost = ~0u;
1036}
1037
1038/// operator< - Choose the lower cost.
1039bool Cost::operator<(const Cost &Other) const {
1040 return std::tie(NumRegs, AddRecCost, NumIVMuls, NumBaseAdds, ScaleCost,
1041 ImmCost, SetupCost) <
1042 std::tie(Other.NumRegs, Other.AddRecCost, Other.NumIVMuls,
1043 Other.NumBaseAdds, Other.ScaleCost, Other.ImmCost,
1044 Other.SetupCost);
1045}
1046
1047void Cost::print(raw_ostream &OS) const {
1048 OS << NumRegs << " reg" << (NumRegs == 1 ? "" : "s");
1049 if (AddRecCost != 0)
1050 OS << ", with addrec cost " << AddRecCost;
1051 if (NumIVMuls != 0)
1052 OS << ", plus " << NumIVMuls << " IV mul" << (NumIVMuls == 1 ? "" : "s");
1053 if (NumBaseAdds != 0)
1054 OS << ", plus " << NumBaseAdds << " base add"
1055 << (NumBaseAdds == 1 ? "" : "s");
1056 if (ScaleCost != 0)
1057 OS << ", plus " << ScaleCost << " scale cost";
1058 if (ImmCost != 0)
1059 OS << ", plus " << ImmCost << " imm cost";
1060 if (SetupCost != 0)
1061 OS << ", plus " << SetupCost << " setup cost";
1062}
1063
1064#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1065void Cost::dump() const {
1066 print(errs()); errs() << '\n';
1067}
1068#endif
1069
1070namespace {
1071
1072/// LSRFixup - An operand value in an instruction which is to be replaced
1073/// with some equivalent, possibly strength-reduced, replacement.
1074struct LSRFixup {
1075 /// UserInst - The instruction which will be updated.
1076 Instruction *UserInst;
1077
1078 /// OperandValToReplace - The operand of the instruction which will
1079 /// be replaced. The operand may be used more than once; every instance
1080 /// will be replaced.
1081 Value *OperandValToReplace;
1082
1083 /// PostIncLoops - If this user is to use the post-incremented value of an
1084 /// induction variable, this variable is non-null and holds the loop
1085 /// associated with the induction variable.
1086 PostIncLoopSet PostIncLoops;
1087
1088 /// LUIdx - The index of the LSRUse describing the expression which
1089 /// this fixup needs, minus an offset (below).
1090 size_t LUIdx;
1091
1092 /// Offset - A constant offset to be added to the LSRUse expression.
1093 /// This allows multiple fixups to share the same LSRUse with different
1094 /// offsets, for example in an unrolled loop.
1095 int64_t Offset;
1096
1097 bool isUseFullyOutsideLoop(const Loop *L) const;
1098
1099 LSRFixup();
1100
1101 void print(raw_ostream &OS) const;
1102 void dump() const;
1103};
1104
1105}
1106
1107LSRFixup::LSRFixup()
1108 : UserInst(nullptr), OperandValToReplace(nullptr), LUIdx(~size_t(0)),
1109 Offset(0) {}
1110
1111/// isUseFullyOutsideLoop - Test whether this fixup always uses its
1112/// value outside of the given loop.
1113bool LSRFixup::isUseFullyOutsideLoop(const Loop *L) const {
1114 // PHI nodes use their value in their incoming blocks.
1115 if (const PHINode *PN = dyn_cast<PHINode>(UserInst)) {
1116 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
1117 if (PN->getIncomingValue(i) == OperandValToReplace &&
1118 L->contains(PN->getIncomingBlock(i)))
1119 return false;
1120 return true;
1121 }
1122
1123 return !L->contains(UserInst);
1124}
1125
1126void LSRFixup::print(raw_ostream &OS) const {
1127 OS << "UserInst=";
1128 // Store is common and interesting enough to be worth special-casing.
1129 if (StoreInst *Store = dyn_cast<StoreInst>(UserInst)) {
1130 OS << "store ";
1131 Store->getOperand(0)->printAsOperand(OS, /*PrintType=*/false);
1132 } else if (UserInst->getType()->isVoidTy())
1133 OS << UserInst->getOpcodeName();
1134 else
1135 UserInst->printAsOperand(OS, /*PrintType=*/false);
1136
1137 OS << ", OperandValToReplace=";
1138 OperandValToReplace->printAsOperand(OS, /*PrintType=*/false);
1139
1140 for (const Loop *PIL : PostIncLoops) {
1141 OS << ", PostIncLoop=";
1142 PIL->getHeader()->printAsOperand(OS, /*PrintType=*/false);
1143 }
1144
1145 if (LUIdx != ~size_t(0))
1146 OS << ", LUIdx=" << LUIdx;
1147
1148 if (Offset != 0)
1149 OS << ", Offset=" << Offset;
1150}
1151
1152#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1153void LSRFixup::dump() const {
1154 print(errs()); errs() << '\n';
1155}
1156#endif
1157
1158namespace {
1159
1160/// UniquifierDenseMapInfo - A DenseMapInfo implementation for holding
1161/// DenseMaps and DenseSets of sorted SmallVectors of const SCEV*.
1162struct UniquifierDenseMapInfo {
1163 static SmallVector<const SCEV *, 4> getEmptyKey() {
1164 SmallVector<const SCEV *, 4> V;
1165 V.push_back(reinterpret_cast<const SCEV *>(-1));
1166 return V;
1167 }
1168
1169 static SmallVector<const SCEV *, 4> getTombstoneKey() {
1170 SmallVector<const SCEV *, 4> V;
1171 V.push_back(reinterpret_cast<const SCEV *>(-2));
1172 return V;
1173 }
1174
1175 static unsigned getHashValue(const SmallVector<const SCEV *, 4> &V) {
1176 return static_cast<unsigned>(hash_combine_range(V.begin(), V.end()));
1177 }
1178
1179 static bool isEqual(const SmallVector<const SCEV *, 4> &LHS,
1180 const SmallVector<const SCEV *, 4> &RHS) {
1181 return LHS == RHS;
1182 }
1183};
1184
1185/// LSRUse - This class holds the state that LSR keeps for each use in
1186/// IVUsers, as well as uses invented by LSR itself. It includes information
1187/// about what kinds of things can be folded into the user, information about
1188/// the user itself, and information about how the use may be satisfied.
1189/// TODO: Represent multiple users of the same expression in common?
1190class LSRUse {
1191 DenseSet<SmallVector<const SCEV *, 4>, UniquifierDenseMapInfo> Uniquifier;
1192
1193public:
1194 /// KindType - An enum for a kind of use, indicating what types of
1195 /// scaled and immediate operands it might support.
1196 enum KindType {
1197 Basic, ///< A normal use, with no folding.
1198 Special, ///< A special case of basic, allowing -1 scales.
1199 Address, ///< An address use; folding according to TargetLowering
1200 ICmpZero ///< An equality icmp with both operands folded into one.
1201 // TODO: Add a generic icmp too?
1202 };
1203
1204 typedef PointerIntPair<const SCEV *, 2, KindType> SCEVUseKindPair;
1205
1206 KindType Kind;
1207 Type *AccessTy;
1208
1209 SmallVector<int64_t, 8> Offsets;
1210 int64_t MinOffset;
1211 int64_t MaxOffset;
1212
1213 /// AllFixupsOutsideLoop - This records whether all of the fixups using this
1214 /// LSRUse are outside of the loop, in which case some special-case heuristics
1215 /// may be used.
1216 bool AllFixupsOutsideLoop;
1217
1218 /// RigidFormula is set to true to guarantee that this use will be associated
1219 /// with a single formula--the one that initially matched. Some SCEV
1220 /// expressions cannot be expanded. This allows LSR to consider the registers
1221 /// used by those expressions without the need to expand them later after
1222 /// changing the formula.
1223 bool RigidFormula;
1224
1225 /// WidestFixupType - This records the widest use type for any fixup using
1226 /// this LSRUse. FindUseWithSimilarFormula can't consider uses with different
1227 /// max fixup widths to be equivalent, because the narrower one may be relying
1228 /// on the implicit truncation to truncate away bogus bits.
1229 Type *WidestFixupType;
1230
1231 /// Formulae - A list of ways to build a value that can satisfy this user.
1232 /// After the list is populated, one of these is selected heuristically and
1233 /// used to formulate a replacement for OperandValToReplace in UserInst.
1234 SmallVector<Formula, 12> Formulae;
1235
1236 /// Regs - The set of register candidates used by all formulae in this LSRUse.
1237 SmallPtrSet<const SCEV *, 4> Regs;
1238
1239 LSRUse(KindType K, Type *T) : Kind(K), AccessTy(T),
1240 MinOffset(INT64_MAX(9223372036854775807L)),
1241 MaxOffset(INT64_MIN(-9223372036854775807L -1)),
1242 AllFixupsOutsideLoop(true),
1243 RigidFormula(false),
1244 WidestFixupType(nullptr) {}
1245
1246 bool HasFormulaWithSameRegs(const Formula &F) const;
1247 bool InsertFormula(const Formula &F);
1248 void DeleteFormula(Formula &F);
1249 void RecomputeRegs(size_t LUIdx, RegUseTracker &Reguses);
1250
1251 void print(raw_ostream &OS) const;
1252 void dump() const;
1253};
1254
1255}
1256
1257/// HasFormula - Test whether this use as a formula which has the same
1258/// registers as the given formula.
1259bool LSRUse::HasFormulaWithSameRegs(const Formula &F) const {
1260 SmallVector<const SCEV *, 4> Key = F.BaseRegs;
1261 if (F.ScaledReg) Key.push_back(F.ScaledReg);
1262 // Unstable sort by host order ok, because this is only used for uniquifying.
1263 std::sort(Key.begin(), Key.end());
1264 return Uniquifier.count(Key);
1265}
1266
1267/// InsertFormula - If the given formula has not yet been inserted, add it to
1268/// the list, and return true. Return false otherwise.
1269/// The formula must be in canonical form.
1270bool LSRUse::InsertFormula(const Formula &F) {
1271 assert(F.isCanonical() && "Invalid canonical representation")((F.isCanonical() && "Invalid canonical representation"
) ? static_cast<void> (0) : __assert_fail ("F.isCanonical() && \"Invalid canonical representation\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1271, __PRETTY_FUNCTION__))
;
1272
1273 if (!Formulae.empty() && RigidFormula)
1274 return false;
1275
1276 SmallVector<const SCEV *, 4> Key = F.BaseRegs;
1277 if (F.ScaledReg) Key.push_back(F.ScaledReg);
1278 // Unstable sort by host order ok, because this is only used for uniquifying.
1279 std::sort(Key.begin(), Key.end());
1280
1281 if (!Uniquifier.insert(Key).second)
1282 return false;
1283
1284 // Using a register to hold the value of 0 is not profitable.
1285 assert((!F.ScaledReg || !F.ScaledReg->isZero()) &&(((!F.ScaledReg || !F.ScaledReg->isZero()) && "Zero allocated in a scaled register!"
) ? static_cast<void> (0) : __assert_fail ("(!F.ScaledReg || !F.ScaledReg->isZero()) && \"Zero allocated in a scaled register!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1286, __PRETTY_FUNCTION__))
1286 "Zero allocated in a scaled register!")(((!F.ScaledReg || !F.ScaledReg->isZero()) && "Zero allocated in a scaled register!"
) ? static_cast<void> (0) : __assert_fail ("(!F.ScaledReg || !F.ScaledReg->isZero()) && \"Zero allocated in a scaled register!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1286, __PRETTY_FUNCTION__))
;
1287#ifndef NDEBUG
1288 for (const SCEV *BaseReg : F.BaseRegs)
1289 assert(!BaseReg->isZero() && "Zero allocated in a base register!")((!BaseReg->isZero() && "Zero allocated in a base register!"
) ? static_cast<void> (0) : __assert_fail ("!BaseReg->isZero() && \"Zero allocated in a base register!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1289, __PRETTY_FUNCTION__))
;
1290#endif
1291
1292 // Add the formula to the list.
1293 Formulae.push_back(F);
1294
1295 // Record registers now being used by this use.
1296 Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end());
1297 if (F.ScaledReg)
1298 Regs.insert(F.ScaledReg);
1299
1300 return true;
1301}
1302
1303/// DeleteFormula - Remove the given formula from this use's list.
1304void LSRUse::DeleteFormula(Formula &F) {
1305 if (&F != &Formulae.back())
1306 std::swap(F, Formulae.back());
1307 Formulae.pop_back();
1308}
1309
1310/// RecomputeRegs - Recompute the Regs field, and update RegUses.
1311void LSRUse::RecomputeRegs(size_t LUIdx, RegUseTracker &RegUses) {
1312 // Now that we've filtered out some formulae, recompute the Regs set.
1313 SmallPtrSet<const SCEV *, 4> OldRegs = std::move(Regs);
1314 Regs.clear();
1315 for (const Formula &F : Formulae) {
1316 if (F.ScaledReg) Regs.insert(F.ScaledReg);
1317 Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end());
1318 }
1319
1320 // Update the RegTracker.
1321 for (const SCEV *S : OldRegs)
1322 if (!Regs.count(S))
1323 RegUses.DropRegister(S, LUIdx);
1324}
1325
1326void LSRUse::print(raw_ostream &OS) const {
1327 OS << "LSR Use: Kind=";
1328 switch (Kind) {
1329 case Basic: OS << "Basic"; break;
1330 case Special: OS << "Special"; break;
1331 case ICmpZero: OS << "ICmpZero"; break;
1332 case Address:
1333 OS << "Address of ";
1334 if (AccessTy->isPointerTy())
1335 OS << "pointer"; // the full pointer type could be really verbose
1336 else
1337 OS << *AccessTy;
1338 }
1339
1340 OS << ", Offsets={";
1341 bool NeedComma = false;
1342 for (int64_t O : Offsets) {
1343 if (NeedComma) OS << ',';
1344 OS << O;
1345 NeedComma = true;
1346 }
1347 OS << '}';
1348
1349 if (AllFixupsOutsideLoop)
1350 OS << ", all-fixups-outside-loop";
1351
1352 if (WidestFixupType)
1353 OS << ", widest fixup type: " << *WidestFixupType;
1354}
1355
1356#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1357void LSRUse::dump() const {
1358 print(errs()); errs() << '\n';
1359}
1360#endif
1361
1362static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1363 LSRUse::KindType Kind, Type *AccessTy,
1364 GlobalValue *BaseGV, int64_t BaseOffset,
1365 bool HasBaseReg, int64_t Scale) {
1366 switch (Kind) {
1367 case LSRUse::Address:
1368 return TTI.isLegalAddressingMode(AccessTy, BaseGV, BaseOffset, HasBaseReg, Scale);
1369
1370 case LSRUse::ICmpZero:
1371 // There's not even a target hook for querying whether it would be legal to
1372 // fold a GV into an ICmp.
1373 if (BaseGV)
1374 return false;
1375
1376 // ICmp only has two operands; don't allow more than two non-trivial parts.
1377 if (Scale != 0 && HasBaseReg && BaseOffset != 0)
1378 return false;
1379
1380 // ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale by
1381 // putting the scaled register in the other operand of the icmp.
1382 if (Scale != 0 && Scale != -1)
1383 return false;
1384
1385 // If we have low-level target information, ask the target if it can fold an
1386 // integer immediate on an icmp.
1387 if (BaseOffset != 0) {
1388 // We have one of:
1389 // ICmpZero BaseReg + BaseOffset => ICmp BaseReg, -BaseOffset
1390 // ICmpZero -1*ScaleReg + BaseOffset => ICmp ScaleReg, BaseOffset
1391 // Offs is the ICmp immediate.
1392 if (Scale == 0)
1393 // The cast does the right thing with INT64_MIN.
1394 BaseOffset = -(uint64_t)BaseOffset;
1395 return TTI.isLegalICmpImmediate(BaseOffset);
1396 }
1397
1398 // ICmpZero BaseReg + -1*ScaleReg => ICmp BaseReg, ScaleReg
1399 return true;
1400
1401 case LSRUse::Basic:
1402 // Only handle single-register values.
1403 return !BaseGV && Scale == 0 && BaseOffset == 0;
1404
1405 case LSRUse::Special:
1406 // Special case Basic to handle -1 scales.
1407 return !BaseGV && (Scale == 0 || Scale == -1) && BaseOffset == 0;
1408 }
1409
1410 llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1410)
;
1411}
1412
1413static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1414 int64_t MinOffset, int64_t MaxOffset,
1415 LSRUse::KindType Kind, Type *AccessTy,
1416 GlobalValue *BaseGV, int64_t BaseOffset,
1417 bool HasBaseReg, int64_t Scale) {
1418 // Check for overflow.
1419 if (((int64_t)((uint64_t)BaseOffset + MinOffset) > BaseOffset) !=
1420 (MinOffset > 0))
1421 return false;
1422 MinOffset = (uint64_t)BaseOffset + MinOffset;
1423 if (((int64_t)((uint64_t)BaseOffset + MaxOffset) > BaseOffset) !=
1424 (MaxOffset > 0))
1425 return false;
1426 MaxOffset = (uint64_t)BaseOffset + MaxOffset;
1427
1428 return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MinOffset,
1429 HasBaseReg, Scale) &&
1430 isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MaxOffset,
1431 HasBaseReg, Scale);
1432}
1433
1434static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1435 int64_t MinOffset, int64_t MaxOffset,
1436 LSRUse::KindType Kind, Type *AccessTy,
1437 const Formula &F) {
1438 // For the purpose of isAMCompletelyFolded either having a canonical formula
1439 // or a scale not equal to zero is correct.
1440 // Problems may arise from non canonical formulae having a scale == 0.
1441 // Strictly speaking it would best to just rely on canonical formulae.
1442 // However, when we generate the scaled formulae, we first check that the
1443 // scaling factor is profitable before computing the actual ScaledReg for
1444 // compile time sake.
1445 assert((F.isCanonical() || F.Scale != 0))(((F.isCanonical() || F.Scale != 0)) ? static_cast<void>
(0) : __assert_fail ("(F.isCanonical() || F.Scale != 0)", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1445, __PRETTY_FUNCTION__))
;
1446 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy,
1447 F.BaseGV, F.BaseOffset, F.HasBaseReg, F.Scale);
1448}
1449
1450/// isLegalUse - Test whether we know how to expand the current formula.
1451static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset,
1452 int64_t MaxOffset, LSRUse::KindType Kind, Type *AccessTy,
1453 GlobalValue *BaseGV, int64_t BaseOffset, bool HasBaseReg,
1454 int64_t Scale) {
1455 // We know how to expand completely foldable formulae.
1456 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV,
1457 BaseOffset, HasBaseReg, Scale) ||
1458 // Or formulae that use a base register produced by a sum of base
1459 // registers.
1460 (Scale == 1 &&
1461 isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy,
1462 BaseGV, BaseOffset, true, 0));
1463}
1464
1465static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset,
1466 int64_t MaxOffset, LSRUse::KindType Kind, Type *AccessTy,
1467 const Formula &F) {
1468 return isLegalUse(TTI, MinOffset, MaxOffset, Kind, AccessTy, F.BaseGV,
1469 F.BaseOffset, F.HasBaseReg, F.Scale);
1470}
1471
1472static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1473 const LSRUse &LU, const Formula &F) {
1474 return isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,
1475 LU.AccessTy, F.BaseGV, F.BaseOffset, F.HasBaseReg,
1476 F.Scale);
1477}
1478
1479static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,
1480 const LSRUse &LU, const Formula &F) {
1481 if (!F.Scale)
1482 return 0;
1483
1484 // If the use is not completely folded in that instruction, we will have to
1485 // pay an extra cost only for scale != 1.
1486 if (!isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,
1487 LU.AccessTy, F))
1488 return F.Scale != 1;
1489
1490 switch (LU.Kind) {
1491 case LSRUse::Address: {
1492 // Check the scaling factor cost with both the min and max offsets.
1493 int ScaleCostMinOffset =
1494 TTI.getScalingFactorCost(LU.AccessTy, F.BaseGV,
1495 F.BaseOffset + LU.MinOffset,
1496 F.HasBaseReg, F.Scale);
1497 int ScaleCostMaxOffset =
1498 TTI.getScalingFactorCost(LU.AccessTy, F.BaseGV,
1499 F.BaseOffset + LU.MaxOffset,
1500 F.HasBaseReg, F.Scale);
1501
1502 assert(ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 &&((ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >=
0 && "Legal addressing mode has an illegal cost!") ?
static_cast<void> (0) : __assert_fail ("ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && \"Legal addressing mode has an illegal cost!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1503, __PRETTY_FUNCTION__))
1503 "Legal addressing mode has an illegal cost!")((ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >=
0 && "Legal addressing mode has an illegal cost!") ?
static_cast<void> (0) : __assert_fail ("ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && \"Legal addressing mode has an illegal cost!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1503, __PRETTY_FUNCTION__))
;
1504 return std::max(ScaleCostMinOffset, ScaleCostMaxOffset);
1505 }
1506 case LSRUse::ICmpZero:
1507 case LSRUse::Basic:
1508 case LSRUse::Special:
1509 // The use is completely folded, i.e., everything is folded into the
1510 // instruction.
1511 return 0;
1512 }
1513
1514 llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1514)
;
1515}
1516
1517static bool isAlwaysFoldable(const TargetTransformInfo &TTI,
1518 LSRUse::KindType Kind, Type *AccessTy,
1519 GlobalValue *BaseGV, int64_t BaseOffset,
1520 bool HasBaseReg) {
1521 // Fast-path: zero is always foldable.
1522 if (BaseOffset == 0 && !BaseGV) return true;
1523
1524 // Conservatively, create an address with an immediate and a
1525 // base and a scale.
1526 int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1;
1527
1528 // Canonicalize a scale of 1 to a base register if the formula doesn't
1529 // already have a base register.
1530 if (!HasBaseReg && Scale == 1) {
1531 Scale = 0;
1532 HasBaseReg = true;
1533 }
1534
1535 return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, BaseOffset,
1536 HasBaseReg, Scale);
1537}
1538
1539static bool isAlwaysFoldable(const TargetTransformInfo &TTI,
1540 ScalarEvolution &SE, int64_t MinOffset,
1541 int64_t MaxOffset, LSRUse::KindType Kind,
1542 Type *AccessTy, const SCEV *S, bool HasBaseReg) {
1543 // Fast-path: zero is always foldable.
1544 if (S->isZero()) return true;
1545
1546 // Conservatively, create an address with an immediate and a
1547 // base and a scale.
1548 int64_t BaseOffset = ExtractImmediate(S, SE);
1549 GlobalValue *BaseGV = ExtractSymbol(S, SE);
1550
1551 // If there's anything else involved, it's not foldable.
1552 if (!S->isZero()) return false;
1553
1554 // Fast-path: zero is always foldable.
1555 if (BaseOffset == 0 && !BaseGV) return true;
1556
1557 // Conservatively, create an address with an immediate and a
1558 // base and a scale.
1559 int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1;
1560
1561 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV,
1562 BaseOffset, HasBaseReg, Scale);
1563}
1564
1565namespace {
1566
1567/// IVInc - An individual increment in a Chain of IV increments.
1568/// Relate an IV user to an expression that computes the IV it uses from the IV
1569/// used by the previous link in the Chain.
1570///
1571/// For the head of a chain, IncExpr holds the absolute SCEV expression for the
1572/// original IVOperand. The head of the chain's IVOperand is only valid during
1573/// chain collection, before LSR replaces IV users. During chain generation,
1574/// IncExpr can be used to find the new IVOperand that computes the same
1575/// expression.
1576struct IVInc {
1577 Instruction *UserInst;
1578 Value* IVOperand;
1579 const SCEV *IncExpr;
1580
1581 IVInc(Instruction *U, Value *O, const SCEV *E):
1582 UserInst(U), IVOperand(O), IncExpr(E) {}
1583};
1584
1585// IVChain - The list of IV increments in program order.
1586// We typically add the head of a chain without finding subsequent links.
1587struct IVChain {
1588 SmallVector<IVInc,1> Incs;
1589 const SCEV *ExprBase;
1590
1591 IVChain() : ExprBase(nullptr) {}
1592
1593 IVChain(const IVInc &Head, const SCEV *Base)
1594 : Incs(1, Head), ExprBase(Base) {}
1595
1596 typedef SmallVectorImpl<IVInc>::const_iterator const_iterator;
1597
1598 // begin - return the first increment in the chain.
1599 const_iterator begin() const {
1600 assert(!Incs.empty())((!Incs.empty()) ? static_cast<void> (0) : __assert_fail
("!Incs.empty()", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1600, __PRETTY_FUNCTION__))
;
1601 return std::next(Incs.begin());
1602 }
1603 const_iterator end() const {
1604 return Incs.end();
1605 }
1606
1607 // hasIncs - Returns true if this chain contains any increments.
1608 bool hasIncs() const { return Incs.size() >= 2; }
1609
1610 // add - Add an IVInc to the end of this chain.
1611 void add(const IVInc &X) { Incs.push_back(X); }
1612
1613 // tailUserInst - Returns the last UserInst in the chain.
1614 Instruction *tailUserInst() const { return Incs.back().UserInst; }
1615
1616 // isProfitableIncrement - Returns true if IncExpr can be profitably added to
1617 // this chain.
1618 bool isProfitableIncrement(const SCEV *OperExpr,
1619 const SCEV *IncExpr,
1620 ScalarEvolution&);
1621};
1622
1623/// ChainUsers - Helper for CollectChains to track multiple IV increment uses.
1624/// Distinguish between FarUsers that definitely cross IV increments and
1625/// NearUsers that may be used between IV increments.
1626struct ChainUsers {
1627 SmallPtrSet<Instruction*, 4> FarUsers;
1628 SmallPtrSet<Instruction*, 4> NearUsers;
1629};
1630
1631/// LSRInstance - This class holds state for the main loop strength reduction
1632/// logic.
1633class LSRInstance {
1634 IVUsers &IU;
1635 ScalarEvolution &SE;
1636 DominatorTree &DT;
1637 LoopInfo &LI;
1638 const TargetTransformInfo &TTI;
1639 Loop *const L;
1640 bool Changed;
1641
1642 /// IVIncInsertPos - This is the insert position that the current loop's
1643 /// induction variable increment should be placed. In simple loops, this is
1644 /// the latch block's terminator. But in more complicated cases, this is a
1645 /// position which will dominate all the in-loop post-increment users.
1646 Instruction *IVIncInsertPos;
1647
1648 /// Factors - Interesting factors between use strides.
1649 SmallSetVector<int64_t, 8> Factors;
1650
1651 /// Types - Interesting use types, to facilitate truncation reuse.
1652 SmallSetVector<Type *, 4> Types;
1653
1654 /// Fixups - The list of operands which are to be replaced.
1655 SmallVector<LSRFixup, 16> Fixups;
1656
1657 /// Uses - The list of interesting uses.
1658 SmallVector<LSRUse, 16> Uses;
1659
1660 /// RegUses - Track which uses use which register candidates.
1661 RegUseTracker RegUses;
1662
1663 // Limit the number of chains to avoid quadratic behavior. We don't expect to
1664 // have more than a few IV increment chains in a loop. Missing a Chain falls
1665 // back to normal LSR behavior for those uses.
1666 static const unsigned MaxChains = 8;
1667
1668 /// IVChainVec - IV users can form a chain of IV increments.
1669 SmallVector<IVChain, MaxChains> IVChainVec;
1670
1671 /// IVIncSet - IV users that belong to profitable IVChains.
1672 SmallPtrSet<Use*, MaxChains> IVIncSet;
1673
1674 void OptimizeShadowIV();
1675 bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse);
1676 ICmpInst *OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse);
1677 void OptimizeLoopTermCond();
1678
1679 void ChainInstruction(Instruction *UserInst, Instruction *IVOper,
1680 SmallVectorImpl<ChainUsers> &ChainUsersVec);
1681 void FinalizeChain(IVChain &Chain);
1682 void CollectChains();
1683 void GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,
1684 SmallVectorImpl<WeakVH> &DeadInsts);
1685
1686 void CollectInterestingTypesAndFactors();
1687 void CollectFixupsAndInitialFormulae();
1688
1689 LSRFixup &getNewFixup() {
1690 Fixups.push_back(LSRFixup());
1691 return Fixups.back();
1692 }
1693
1694 // Support for sharing of LSRUses between LSRFixups.
1695 typedef DenseMap<LSRUse::SCEVUseKindPair, size_t> UseMapTy;
1696 UseMapTy UseMap;
1697
1698 bool reconcileNewOffset(LSRUse &LU, int64_t NewOffset, bool HasBaseReg,
1699 LSRUse::KindType Kind, Type *AccessTy);
1700
1701 std::pair<size_t, int64_t> getUse(const SCEV *&Expr,
1702 LSRUse::KindType Kind,
1703 Type *AccessTy);
1704
1705 void DeleteUse(LSRUse &LU, size_t LUIdx);
1706
1707 LSRUse *FindUseWithSimilarFormula(const Formula &F, const LSRUse &OrigLU);
1708
1709 void InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx);
1710 void InsertSupplementalFormula(const SCEV *S, LSRUse &LU, size_t LUIdx);
1711 void CountRegisters(const Formula &F, size_t LUIdx);
1712 bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F);
1713
1714 void CollectLoopInvariantFixupsAndFormulae();
1715
1716 void GenerateReassociations(LSRUse &LU, unsigned LUIdx, Formula Base,
1717 unsigned Depth = 0);
1718
1719 void GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,
1720 const Formula &Base, unsigned Depth,
1721 size_t Idx, bool IsScaledReg = false);
1722 void GenerateCombinations(LSRUse &LU, unsigned LUIdx, Formula Base);
1723 void GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,
1724 const Formula &Base, size_t Idx,
1725 bool IsScaledReg = false);
1726 void GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, Formula Base);
1727 void GenerateConstantOffsetsImpl(LSRUse &LU, unsigned LUIdx,
1728 const Formula &Base,
1729 const SmallVectorImpl<int64_t> &Worklist,
1730 size_t Idx, bool IsScaledReg = false);
1731 void GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, Formula Base);
1732 void GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, Formula Base);
1733 void GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base);
1734 void GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base);
1735 void GenerateCrossUseConstantOffsets();
1736 void GenerateAllReuseFormulae();
1737
1738 void FilterOutUndesirableDedicatedRegisters();
1739
1740 size_t EstimateSearchSpaceComplexity() const;
1741 void NarrowSearchSpaceByDetectingSupersets();
1742 void NarrowSearchSpaceByCollapsingUnrolledCode();
1743 void NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();
1744 void NarrowSearchSpaceByPickingWinnerRegs();
1745 void NarrowSearchSpaceUsingHeuristics();
1746
1747 void SolveRecurse(SmallVectorImpl<const Formula *> &Solution,
1748 Cost &SolutionCost,
1749 SmallVectorImpl<const Formula *> &Workspace,
1750 const Cost &CurCost,
1751 const SmallPtrSet<const SCEV *, 16> &CurRegs,
1752 DenseSet<const SCEV *> &VisitedRegs) const;
1753 void Solve(SmallVectorImpl<const Formula *> &Solution) const;
1754
1755 BasicBlock::iterator
1756 HoistInsertPosition(BasicBlock::iterator IP,
1757 const SmallVectorImpl<Instruction *> &Inputs) const;
1758 BasicBlock::iterator
1759 AdjustInsertPositionForExpand(BasicBlock::iterator IP,
1760 const LSRFixup &LF,
1761 const LSRUse &LU,
1762 SCEVExpander &Rewriter) const;
1763
1764 Value *Expand(const LSRFixup &LF,
1765 const Formula &F,
1766 BasicBlock::iterator IP,
1767 SCEVExpander &Rewriter,
1768 SmallVectorImpl<WeakVH> &DeadInsts) const;
1769 void RewriteForPHI(PHINode *PN, const LSRFixup &LF,
1770 const Formula &F,
1771 SCEVExpander &Rewriter,
1772 SmallVectorImpl<WeakVH> &DeadInsts,
1773 Pass *P) const;
1774 void Rewrite(const LSRFixup &LF,
1775 const Formula &F,
1776 SCEVExpander &Rewriter,
1777 SmallVectorImpl<WeakVH> &DeadInsts,
1778 Pass *P) const;
1779 void ImplementSolution(const SmallVectorImpl<const Formula *> &Solution,
1780 Pass *P);
1781
1782public:
1783 LSRInstance(Loop *L, Pass *P);
1784
1785 bool getChanged() const { return Changed; }
1786
1787 void print_factors_and_types(raw_ostream &OS) const;
1788 void print_fixups(raw_ostream &OS) const;
1789 void print_uses(raw_ostream &OS) const;
1790 void print(raw_ostream &OS) const;
1791 void dump() const;
1792};
1793
1794}
1795
1796/// OptimizeShadowIV - If IV is used in a int-to-float cast
1797/// inside the loop then try to eliminate the cast operation.
1798void LSRInstance::OptimizeShadowIV() {
1799 const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
1800 if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
1801 return;
1802
1803 for (IVUsers::const_iterator UI = IU.begin(), E = IU.end();
1804 UI != E; /* empty */) {
1805 IVUsers::const_iterator CandidateUI = UI;
1806 ++UI;
1807 Instruction *ShadowUse = CandidateUI->getUser();
1808 Type *DestTy = nullptr;
1809 bool IsSigned = false;
1810
1811 /* If shadow use is a int->float cast then insert a second IV
1812 to eliminate this cast.
1813
1814 for (unsigned i = 0; i < n; ++i)
1815 foo((double)i);
1816
1817 is transformed into
1818
1819 double d = 0.0;
1820 for (unsigned i = 0; i < n; ++i, ++d)
1821 foo(d);
1822 */
1823 if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser())) {
1824 IsSigned = false;
1825 DestTy = UCast->getDestTy();
1826 }
1827 else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser())) {
1828 IsSigned = true;
1829 DestTy = SCast->getDestTy();
1830 }
1831 if (!DestTy) continue;
1832
1833 // If target does not support DestTy natively then do not apply
1834 // this transformation.
1835 if (!TTI.isTypeLegal(DestTy)) continue;
1836
1837 PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0));
1838 if (!PH) continue;
1839 if (PH->getNumIncomingValues() != 2) continue;
1840
1841 Type *SrcTy = PH->getType();
1842 int Mantissa = DestTy->getFPMantissaWidth();
1843 if (Mantissa == -1) continue;
1844 if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa)
1845 continue;
1846
1847 unsigned Entry, Latch;
1848 if (PH->getIncomingBlock(0) == L->getLoopPreheader()) {
1849 Entry = 0;
1850 Latch = 1;
1851 } else {
1852 Entry = 1;
1853 Latch = 0;
1854 }
1855
1856 ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));
1857 if (!Init) continue;
1858 Constant *NewInit = ConstantFP::get(DestTy, IsSigned ?
1859 (double)Init->getSExtValue() :
1860 (double)Init->getZExtValue());
1861
1862 BinaryOperator *Incr =
1863 dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));
1864 if (!Incr) continue;
1865 if (Incr->getOpcode() != Instruction::Add
1866 && Incr->getOpcode() != Instruction::Sub)
1867 continue;
1868
1869 /* Initialize new IV, double d = 0.0 in above example. */
1870 ConstantInt *C = nullptr;
1871 if (Incr->getOperand(0) == PH)
1872 C = dyn_cast<ConstantInt>(Incr->getOperand(1));
1873 else if (Incr->getOperand(1) == PH)
1874 C = dyn_cast<ConstantInt>(Incr->getOperand(0));
1875 else
1876 continue;
1877
1878 if (!C) continue;
1879
1880 // Ignore negative constants, as the code below doesn't handle them
1881 // correctly. TODO: Remove this restriction.
1882 if (!C->getValue().isStrictlyPositive()) continue;
1883
1884 /* Add new PHINode. */
1885 PHINode *NewPH = PHINode::Create(DestTy, 2, "IV.S.", PH);
1886
1887 /* create new increment. '++d' in above example. */
1888 Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue());
1889 BinaryOperator *NewIncr =
1890 BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ?
1891 Instruction::FAdd : Instruction::FSub,
1892 NewPH, CFP, "IV.S.next.", Incr);
1893
1894 NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry));
1895 NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch));
1896
1897 /* Remove cast operation */
1898 ShadowUse->replaceAllUsesWith(NewPH);
1899 ShadowUse->eraseFromParent();
1900 Changed = true;
1901 break;
1902 }
1903}
1904
1905/// FindIVUserForCond - If Cond has an operand that is an expression of an IV,
1906/// set the IV user and stride information and return true, otherwise return
1907/// false.
1908bool LSRInstance::FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse) {
1909 for (IVStrideUse &U : IU)
1910 if (U.getUser() == Cond) {
1911 // NOTE: we could handle setcc instructions with multiple uses here, but
1912 // InstCombine does it as well for simple uses, it's not clear that it
1913 // occurs enough in real life to handle.
1914 CondUse = &U;
1915 return true;
1916 }
1917 return false;
1918}
1919
1920/// OptimizeMax - Rewrite the loop's terminating condition if it uses
1921/// a max computation.
1922///
1923/// This is a narrow solution to a specific, but acute, problem. For loops
1924/// like this:
1925///
1926/// i = 0;
1927/// do {
1928/// p[i] = 0.0;
1929/// } while (++i < n);
1930///
1931/// the trip count isn't just 'n', because 'n' might not be positive. And
1932/// unfortunately this can come up even for loops where the user didn't use
1933/// a C do-while loop. For example, seemingly well-behaved top-test loops
1934/// will commonly be lowered like this:
1935//
1936/// if (n > 0) {
1937/// i = 0;
1938/// do {
1939/// p[i] = 0.0;
1940/// } while (++i < n);
1941/// }
1942///
1943/// and then it's possible for subsequent optimization to obscure the if
1944/// test in such a way that indvars can't find it.
1945///
1946/// When indvars can't find the if test in loops like this, it creates a
1947/// max expression, which allows it to give the loop a canonical
1948/// induction variable:
1949///
1950/// i = 0;
1951/// max = n < 1 ? 1 : n;
1952/// do {
1953/// p[i] = 0.0;
1954/// } while (++i != max);
1955///
1956/// Canonical induction variables are necessary because the loop passes
1957/// are designed around them. The most obvious example of this is the
1958/// LoopInfo analysis, which doesn't remember trip count values. It
1959/// expects to be able to rediscover the trip count each time it is
1960/// needed, and it does this using a simple analysis that only succeeds if
1961/// the loop has a canonical induction variable.
1962///
1963/// However, when it comes time to generate code, the maximum operation
1964/// can be quite costly, especially if it's inside of an outer loop.
1965///
1966/// This function solves this problem by detecting this type of loop and
1967/// rewriting their conditions from ICMP_NE back to ICMP_SLT, and deleting
1968/// the instructions for the maximum computation.
1969///
1970ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) {
1971 // Check that the loop matches the pattern we're looking for.
1972 if (Cond->getPredicate() != CmpInst::ICMP_EQ &&
1973 Cond->getPredicate() != CmpInst::ICMP_NE)
1974 return Cond;
1975
1976 SelectInst *Sel = dyn_cast<SelectInst>(Cond->getOperand(1));
1977 if (!Sel || !Sel->hasOneUse()) return Cond;
1978
1979 const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
1980 if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
1981 return Cond;
1982 const SCEV *One = SE.getConstant(BackedgeTakenCount->getType(), 1);
1983
1984 // Add one to the backedge-taken count to get the trip count.
1985 const SCEV *IterationCount = SE.getAddExpr(One, BackedgeTakenCount);
1986 if (IterationCount != SE.getSCEV(Sel)) return Cond;
1987
1988 // Check for a max calculation that matches the pattern. There's no check
1989 // for ICMP_ULE here because the comparison would be with zero, which
1990 // isn't interesting.
1991 CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1992 const SCEVNAryExpr *Max = nullptr;
1993 if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(BackedgeTakenCount)) {
1994 Pred = ICmpInst::ICMP_SLE;
1995 Max = S;
1996 } else if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(IterationCount)) {
1997 Pred = ICmpInst::ICMP_SLT;
1998 Max = S;
1999 } else if (const SCEVUMaxExpr *U = dyn_cast<SCEVUMaxExpr>(IterationCount)) {
2000 Pred = ICmpInst::ICMP_ULT;
2001 Max = U;
2002 } else {
2003 // No match; bail.
2004 return Cond;
2005 }
2006
2007 // To handle a max with more than two operands, this optimization would
2008 // require additional checking and setup.
2009 if (Max->getNumOperands() != 2)
2010 return Cond;
2011
2012 const SCEV *MaxLHS = Max->getOperand(0);
2013 const SCEV *MaxRHS = Max->getOperand(1);
2014
2015 // ScalarEvolution canonicalizes constants to the left. For < and >, look
2016 // for a comparison with 1. For <= and >=, a comparison with zero.
2017 if (!MaxLHS ||
2018 (ICmpInst::isTrueWhenEqual(Pred) ? !MaxLHS->isZero() : (MaxLHS != One)))
2019 return Cond;
2020
2021 // Check the relevant induction variable for conformance to
2022 // the pattern.
2023 const SCEV *IV = SE.getSCEV(Cond->getOperand(0));
2024 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV);
2025 if (!AR || !AR->isAffine() ||
2026 AR->getStart() != One ||
2027 AR->getStepRecurrence(SE) != One)
2028 return Cond;
2029
2030 assert(AR->getLoop() == L &&((AR->getLoop() == L && "Loop condition operand is an addrec in a different loop!"
) ? static_cast<void> (0) : __assert_fail ("AR->getLoop() == L && \"Loop condition operand is an addrec in a different loop!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2031, __PRETTY_FUNCTION__))
2031 "Loop condition operand is an addrec in a different loop!")((AR->getLoop() == L && "Loop condition operand is an addrec in a different loop!"
) ? static_cast<void> (0) : __assert_fail ("AR->getLoop() == L && \"Loop condition operand is an addrec in a different loop!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2031, __PRETTY_FUNCTION__))
;
2032
2033 // Check the right operand of the select, and remember it, as it will
2034 // be used in the new comparison instruction.
2035 Value *NewRHS = nullptr;
2036 if (ICmpInst::isTrueWhenEqual(Pred)) {
2037 // Look for n+1, and grab n.
2038 if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(1)))
2039 if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1)))
2040 if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS)
2041 NewRHS = BO->getOperand(0);
2042 if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(2)))
2043 if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1)))
2044 if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS)
2045 NewRHS = BO->getOperand(0);
2046 if (!NewRHS)
2047 return Cond;
2048 } else if (SE.getSCEV(Sel->getOperand(1)) == MaxRHS)
2049 NewRHS = Sel->getOperand(1);
2050 else if (SE.getSCEV(Sel->getOperand(2)) == MaxRHS)
2051 NewRHS = Sel->getOperand(2);
2052 else if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(MaxRHS))
2053 NewRHS = SU->getValue();
2054 else
2055 // Max doesn't match expected pattern.
2056 return Cond;
2057
2058 // Determine the new comparison opcode. It may be signed or unsigned,
2059 // and the original comparison may be either equality or inequality.
2060 if (Cond->getPredicate() == CmpInst::ICMP_EQ)
2061 Pred = CmpInst::getInversePredicate(Pred);
2062
2063 // Ok, everything looks ok to change the condition into an SLT or SGE and
2064 // delete the max calculation.
2065 ICmpInst *NewCond =
2066 new ICmpInst(Cond, Pred, Cond->getOperand(0), NewRHS, "scmp");
2067
2068 // Delete the max calculation instructions.
2069 Cond->replaceAllUsesWith(NewCond);
2070 CondUse->setUser(NewCond);
2071 Instruction *Cmp = cast<Instruction>(Sel->getOperand(0));
2072 Cond->eraseFromParent();
2073 Sel->eraseFromParent();
2074 if (Cmp->use_empty())
2075 Cmp->eraseFromParent();
2076 return NewCond;
2077}
2078
2079/// OptimizeLoopTermCond - Change loop terminating condition to use the
2080/// postinc iv when possible.
2081void
2082LSRInstance::OptimizeLoopTermCond() {
2083 SmallPtrSet<Instruction *, 4> PostIncs;
2084
2085 BasicBlock *LatchBlock = L->getLoopLatch();
2086 SmallVector<BasicBlock*, 8> ExitingBlocks;
2087 L->getExitingBlocks(ExitingBlocks);
2088
2089 for (BasicBlock *ExitingBlock : ExitingBlocks) {
2090
2091 // Get the terminating condition for the loop if possible. If we
2092 // can, we want to change it to use a post-incremented version of its
2093 // induction variable, to allow coalescing the live ranges for the IV into
2094 // one register value.
2095
2096 BranchInst *TermBr = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
2097 if (!TermBr)
2098 continue;
2099 // FIXME: Overly conservative, termination condition could be an 'or' etc..
2100 if (TermBr->isUnconditional() || !isa<ICmpInst>(TermBr->getCondition()))
2101 continue;
2102
2103 // Search IVUsesByStride to find Cond's IVUse if there is one.
2104 IVStrideUse *CondUse = nullptr;
2105 ICmpInst *Cond = cast<ICmpInst>(TermBr->getCondition());
2106 if (!FindIVUserForCond(Cond, CondUse))
2107 continue;
2108
2109 // If the trip count is computed in terms of a max (due to ScalarEvolution
2110 // being unable to find a sufficient guard, for example), change the loop
2111 // comparison to use SLT or ULT instead of NE.
2112 // One consequence of doing this now is that it disrupts the count-down
2113 // optimization. That's not always a bad thing though, because in such
2114 // cases it may still be worthwhile to avoid a max.
2115 Cond = OptimizeMax(Cond, CondUse);
2116
2117 // If this exiting block dominates the latch block, it may also use
2118 // the post-inc value if it won't be shared with other uses.
2119 // Check for dominance.
2120 if (!DT.dominates(ExitingBlock, LatchBlock))
2121 continue;
2122
2123 // Conservatively avoid trying to use the post-inc value in non-latch
2124 // exits if there may be pre-inc users in intervening blocks.
2125 if (LatchBlock != ExitingBlock)
2126 for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI)
2127 // Test if the use is reachable from the exiting block. This dominator
2128 // query is a conservative approximation of reachability.
2129 if (&*UI != CondUse &&
2130 !DT.properlyDominates(UI->getUser()->getParent(), ExitingBlock)) {
2131 // Conservatively assume there may be reuse if the quotient of their
2132 // strides could be a legal scale.
2133 const SCEV *A = IU.getStride(*CondUse, L);
2134 const SCEV *B = IU.getStride(*UI, L);
2135 if (!A || !B) continue;
2136 if (SE.getTypeSizeInBits(A->getType()) !=
2137 SE.getTypeSizeInBits(B->getType())) {
2138 if (SE.getTypeSizeInBits(A->getType()) >
2139 SE.getTypeSizeInBits(B->getType()))
2140 B = SE.getSignExtendExpr(B, A->getType());
2141 else
2142 A = SE.getSignExtendExpr(A, B->getType());
2143 }
2144 if (const SCEVConstant *D =
2145 dyn_cast_or_null<SCEVConstant>(getExactSDiv(B, A, SE))) {
2146 const ConstantInt *C = D->getValue();
2147 // Stride of one or negative one can have reuse with non-addresses.
2148 if (C->isOne() || C->isAllOnesValue())
2149 goto decline_post_inc;
2150 // Avoid weird situations.
2151 if (C->getValue().getMinSignedBits() >= 64 ||
2152 C->getValue().isMinSignedValue())
2153 goto decline_post_inc;
2154 // Check for possible scaled-address reuse.
2155 Type *AccessTy = getAccessType(UI->getUser());
2156 int64_t Scale = C->getSExtValue();
2157 if (TTI.isLegalAddressingMode(AccessTy, /*BaseGV=*/ nullptr,
2158 /*BaseOffset=*/ 0,
2159 /*HasBaseReg=*/ false, Scale))
2160 goto decline_post_inc;
2161 Scale = -Scale;
2162 if (TTI.isLegalAddressingMode(AccessTy, /*BaseGV=*/ nullptr,
2163 /*BaseOffset=*/ 0,
2164 /*HasBaseReg=*/ false, Scale))
2165 goto decline_post_inc;
2166 }
2167 }
2168
2169 DEBUG(dbgs() << " Change loop exiting icmp to use postinc iv: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: "
<< *Cond << '\n'; } } while (0)
2170 << *Cond << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: "
<< *Cond << '\n'; } } while (0)
;
2171
2172 // It's possible for the setcc instruction to be anywhere in the loop, and
2173 // possible for it to have multiple users. If it is not immediately before
2174 // the exiting block branch, move it.
2175 if (&*++BasicBlock::iterator(Cond) != TermBr) {
2176 if (Cond->hasOneUse()) {
2177 Cond->moveBefore(TermBr);
2178 } else {
2179 // Clone the terminating condition and insert into the loopend.
2180 ICmpInst *OldCond = Cond;
2181 Cond = cast<ICmpInst>(Cond->clone());
2182 Cond->setName(L->getHeader()->getName() + ".termcond");
2183 ExitingBlock->getInstList().insert(TermBr, Cond);
2184
2185 // Clone the IVUse, as the old use still exists!
2186 CondUse = &IU.AddUser(Cond, CondUse->getOperandValToReplace());
2187 TermBr->replaceUsesOfWith(OldCond, Cond);
2188 }
2189 }
2190
2191 // If we get to here, we know that we can transform the setcc instruction to
2192 // use the post-incremented version of the IV, allowing us to coalesce the
2193 // live ranges for the IV correctly.
2194 CondUse->transformToPostInc(L);
2195 Changed = true;
2196
2197 PostIncs.insert(Cond);
2198 decline_post_inc:;
2199 }
2200
2201 // Determine an insertion point for the loop induction variable increment. It
2202 // must dominate all the post-inc comparisons we just set up, and it must
2203 // dominate the loop latch edge.
2204 IVIncInsertPos = L->getLoopLatch()->getTerminator();
2205 for (Instruction *Inst : PostIncs) {
2206 BasicBlock *BB =
2207 DT.findNearestCommonDominator(IVIncInsertPos->getParent(),
2208 Inst->getParent());
2209 if (BB == Inst->getParent())
2210 IVIncInsertPos = Inst;
2211 else if (BB != IVIncInsertPos->getParent())
2212 IVIncInsertPos = BB->getTerminator();
2213 }
2214}
2215
2216/// reconcileNewOffset - Determine if the given use can accommodate a fixup
2217/// at the given offset and other details. If so, update the use and
2218/// return true.
2219bool
2220LSRInstance::reconcileNewOffset(LSRUse &LU, int64_t NewOffset, bool HasBaseReg,
2221 LSRUse::KindType Kind, Type *AccessTy) {
2222 int64_t NewMinOffset = LU.MinOffset;
2223 int64_t NewMaxOffset = LU.MaxOffset;
2224 Type *NewAccessTy = AccessTy;
2225
2226 // Check for a mismatched kind. It's tempting to collapse mismatched kinds to
2227 // something conservative, however this can pessimize in the case that one of
2228 // the uses will have all its uses outside the loop, for example.
2229 if (LU.Kind != Kind)
2230 return false;
2231
2232 // Check for a mismatched access type, and fall back conservatively as needed.
2233 // TODO: Be less conservative when the type is similar and can use the same
2234 // addressing modes.
2235 if (Kind == LSRUse::Address && AccessTy != LU.AccessTy)
2236 NewAccessTy = Type::getVoidTy(AccessTy->getContext());
2237
2238 // Conservatively assume HasBaseReg is true for now.
2239 if (NewOffset < LU.MinOffset) {
2240 if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr,
2241 LU.MaxOffset - NewOffset, HasBaseReg))
2242 return false;
2243 NewMinOffset = NewOffset;
2244 } else if (NewOffset > LU.MaxOffset) {
2245 if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr,
2246 NewOffset - LU.MinOffset, HasBaseReg))
2247 return false;
2248 NewMaxOffset = NewOffset;
2249 }
2250
2251 // Update the use.
2252 LU.MinOffset = NewMinOffset;
2253 LU.MaxOffset = NewMaxOffset;
2254 LU.AccessTy = NewAccessTy;
2255 if (NewOffset != LU.Offsets.back())
2256 LU.Offsets.push_back(NewOffset);
2257 return true;
2258}
2259
2260/// getUse - Return an LSRUse index and an offset value for a fixup which
2261/// needs the given expression, with the given kind and optional access type.
2262/// Either reuse an existing use or create a new one, as needed.
2263std::pair<size_t, int64_t>
2264LSRInstance::getUse(const SCEV *&Expr,
2265 LSRUse::KindType Kind, Type *AccessTy) {
2266 const SCEV *Copy = Expr;
2267 int64_t Offset = ExtractImmediate(Expr, SE);
2268
2269 // Basic uses can't accept any offset, for example.
2270 if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr,
2271 Offset, /*HasBaseReg=*/ true)) {
2272 Expr = Copy;
2273 Offset = 0;
2274 }
2275
2276 std::pair<UseMapTy::iterator, bool> P =
2277 UseMap.insert(std::make_pair(LSRUse::SCEVUseKindPair(Expr, Kind), 0));
2278 if (!P.second) {
2279 // A use already existed with this base.
2280 size_t LUIdx = P.first->second;
2281 LSRUse &LU = Uses[LUIdx];
2282 if (reconcileNewOffset(LU, Offset, /*HasBaseReg=*/true, Kind, AccessTy))
2283 // Reuse this use.
2284 return std::make_pair(LUIdx, Offset);
2285 }
2286
2287 // Create a new use.
2288 size_t LUIdx = Uses.size();
2289 P.first->second = LUIdx;
2290 Uses.push_back(LSRUse(Kind, AccessTy));
2291 LSRUse &LU = Uses[LUIdx];
2292
2293 // We don't need to track redundant offsets, but we don't need to go out
2294 // of our way here to avoid them.
2295 if (LU.Offsets.empty() || Offset != LU.Offsets.back())
2296 LU.Offsets.push_back(Offset);
2297
2298 LU.MinOffset = Offset;
2299 LU.MaxOffset = Offset;
2300 return std::make_pair(LUIdx, Offset);
2301}
2302
2303/// DeleteUse - Delete the given use from the Uses list.
2304void LSRInstance::DeleteUse(LSRUse &LU, size_t LUIdx) {
2305 if (&LU != &Uses.back())
2306 std::swap(LU, Uses.back());
2307 Uses.pop_back();
2308
2309 // Update RegUses.
2310 RegUses.SwapAndDropUse(LUIdx, Uses.size());
2311}
2312
2313/// FindUseWithFormula - Look for a use distinct from OrigLU which is has
2314/// a formula that has the same registers as the given formula.
2315LSRUse *
2316LSRInstance::FindUseWithSimilarFormula(const Formula &OrigF,
2317 const LSRUse &OrigLU) {
2318 // Search all uses for the formula. This could be more clever.
2319 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
2320 LSRUse &LU = Uses[LUIdx];
2321 // Check whether this use is close enough to OrigLU, to see whether it's
2322 // worthwhile looking through its formulae.
2323 // Ignore ICmpZero uses because they may contain formulae generated by
2324 // GenerateICmpZeroScales, in which case adding fixup offsets may
2325 // be invalid.
2326 if (&LU != &OrigLU &&
2327 LU.Kind != LSRUse::ICmpZero &&
2328 LU.Kind == OrigLU.Kind && OrigLU.AccessTy == LU.AccessTy &&
2329 LU.WidestFixupType == OrigLU.WidestFixupType &&
2330 LU.HasFormulaWithSameRegs(OrigF)) {
2331 // Scan through this use's formulae.
2332 for (const Formula &F : LU.Formulae) {
2333 // Check to see if this formula has the same registers and symbols
2334 // as OrigF.
2335 if (F.BaseRegs == OrigF.BaseRegs &&
2336 F.ScaledReg == OrigF.ScaledReg &&
2337 F.BaseGV == OrigF.BaseGV &&
2338 F.Scale == OrigF.Scale &&
2339 F.UnfoldedOffset == OrigF.UnfoldedOffset) {
2340 if (F.BaseOffset == 0)
2341 return &LU;
2342 // This is the formula where all the registers and symbols matched;
2343 // there aren't going to be any others. Since we declined it, we
2344 // can skip the rest of the formulae and proceed to the next LSRUse.
2345 break;
2346 }
2347 }
2348 }
2349 }
2350
2351 // Nothing looked good.
2352 return nullptr;
2353}
2354
2355void LSRInstance::CollectInterestingTypesAndFactors() {
2356 SmallSetVector<const SCEV *, 4> Strides;
2357
2358 // Collect interesting types and strides.
2359 SmallVector<const SCEV *, 4> Worklist;
2360 for (const IVStrideUse &U : IU) {
2361 const SCEV *Expr = IU.getExpr(U);
2362
2363 // Collect interesting types.
2364 Types.insert(SE.getEffectiveSCEVType(Expr->getType()));
2365
2366 // Add strides for mentioned loops.
2367 Worklist.push_back(Expr);
2368 do {
2369 const SCEV *S = Worklist.pop_back_val();
2370 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
2371 if (AR->getLoop() == L)
2372 Strides.insert(AR->getStepRecurrence(SE));
2373 Worklist.push_back(AR->getStart());
2374 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
2375 Worklist.append(Add->op_begin(), Add->op_end());
2376 }
2377 } while (!Worklist.empty());
2378 }
2379
2380 // Compute interesting factors from the set of interesting strides.
2381 for (SmallSetVector<const SCEV *, 4>::const_iterator
2382 I = Strides.begin(), E = Strides.end(); I != E; ++I)
2383 for (SmallSetVector<const SCEV *, 4>::const_iterator NewStrideIter =
2384 std::next(I); NewStrideIter != E; ++NewStrideIter) {
2385 const SCEV *OldStride = *I;
2386 const SCEV *NewStride = *NewStrideIter;
2387
2388 if (SE.getTypeSizeInBits(OldStride->getType()) !=
2389 SE.getTypeSizeInBits(NewStride->getType())) {
2390 if (SE.getTypeSizeInBits(OldStride->getType()) >
2391 SE.getTypeSizeInBits(NewStride->getType()))
2392 NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType());
2393 else
2394 OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType());
2395 }
2396 if (const SCEVConstant *Factor =
2397 dyn_cast_or_null<SCEVConstant>(getExactSDiv(NewStride, OldStride,
2398 SE, true))) {
2399 if (Factor->getValue()->getValue().getMinSignedBits() <= 64)
2400 Factors.insert(Factor->getValue()->getValue().getSExtValue());
2401 } else if (const SCEVConstant *Factor =
2402 dyn_cast_or_null<SCEVConstant>(getExactSDiv(OldStride,
2403 NewStride,
2404 SE, true))) {
2405 if (Factor->getValue()->getValue().getMinSignedBits() <= 64)
2406 Factors.insert(Factor->getValue()->getValue().getSExtValue());
2407 }
2408 }
2409
2410 // If all uses use the same type, don't bother looking for truncation-based
2411 // reuse.
2412 if (Types.size() == 1)
2413 Types.clear();
2414
2415 DEBUG(print_factors_and_types(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_factors_and_types(dbgs()); } } while
(0)
;
2416}
2417
2418/// findIVOperand - Helper for CollectChains that finds an IV operand (computed
2419/// by an AddRec in this loop) within [OI,OE) or returns OE. If IVUsers mapped
2420/// Instructions to IVStrideUses, we could partially skip this.
2421static User::op_iterator
2422findIVOperand(User::op_iterator OI, User::op_iterator OE,
2423 Loop *L, ScalarEvolution &SE) {
2424 for(; OI != OE; ++OI) {
2425 if (Instruction *Oper = dyn_cast<Instruction>(*OI)) {
2426 if (!SE.isSCEVable(Oper->getType()))
2427 continue;
2428
2429 if (const SCEVAddRecExpr *AR =
2430 dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Oper))) {
2431 if (AR->getLoop() == L)
2432 break;
2433 }
2434 }
2435 }
2436 return OI;
2437}
2438
2439/// getWideOperand - IVChain logic must consistenctly peek base TruncInst
2440/// operands, so wrap it in a convenient helper.
2441static Value *getWideOperand(Value *Oper) {
2442 if (TruncInst *Trunc = dyn_cast<TruncInst>(Oper))
2443 return Trunc->getOperand(0);
2444 return Oper;
2445}
2446
2447/// isCompatibleIVType - Return true if we allow an IV chain to include both
2448/// types.
2449static bool isCompatibleIVType(Value *LVal, Value *RVal) {
2450 Type *LType = LVal->getType();
2451 Type *RType = RVal->getType();
2452 return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy());
2453}
2454
2455/// getExprBase - Return an approximation of this SCEV expression's "base", or
2456/// NULL for any constant. Returning the expression itself is
2457/// conservative. Returning a deeper subexpression is more precise and valid as
2458/// long as it isn't less complex than another subexpression. For expressions
2459/// involving multiple unscaled values, we need to return the pointer-type
2460/// SCEVUnknown. This avoids forming chains across objects, such as:
2461/// PrevOper==a[i], IVOper==b[i], IVInc==b-a.
2462///
2463/// Since SCEVUnknown is the rightmost type, and pointers are the rightmost
2464/// SCEVUnknown, we simply return the rightmost SCEV operand.
2465static const SCEV *getExprBase(const SCEV *S) {
2466 switch (S->getSCEVType()) {
2467 default: // uncluding scUnknown.
2468 return S;
2469 case scConstant:
2470 return nullptr;
2471 case scTruncate:
2472 return getExprBase(cast<SCEVTruncateExpr>(S)->getOperand());
2473 case scZeroExtend:
2474 return getExprBase(cast<SCEVZeroExtendExpr>(S)->getOperand());
2475 case scSignExtend:
2476 return getExprBase(cast<SCEVSignExtendExpr>(S)->getOperand());
2477 case scAddExpr: {
2478 // Skip over scaled operands (scMulExpr) to follow add operands as long as
2479 // there's nothing more complex.
2480 // FIXME: not sure if we want to recognize negation.
2481 const SCEVAddExpr *Add = cast<SCEVAddExpr>(S);
2482 for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(Add->op_end()),
2483 E(Add->op_begin()); I != E; ++I) {
2484 const SCEV *SubExpr = *I;
2485 if (SubExpr->getSCEVType() == scAddExpr)
2486 return getExprBase(SubExpr);
2487
2488 if (SubExpr->getSCEVType() != scMulExpr)
2489 return SubExpr;
2490 }
2491 return S; // all operands are scaled, be conservative.
2492 }
2493 case scAddRecExpr:
2494 return getExprBase(cast<SCEVAddRecExpr>(S)->getStart());
2495 }
2496}
2497
2498/// Return true if the chain increment is profitable to expand into a loop
2499/// invariant value, which may require its own register. A profitable chain
2500/// increment will be an offset relative to the same base. We allow such offsets
2501/// to potentially be used as chain increment as long as it's not obviously
2502/// expensive to expand using real instructions.
2503bool IVChain::isProfitableIncrement(const SCEV *OperExpr,
2504 const SCEV *IncExpr,
2505 ScalarEvolution &SE) {
2506 // Aggressively form chains when -stress-ivchain.
2507 if (StressIVChain)
2508 return true;
2509
2510 // Do not replace a constant offset from IV head with a nonconstant IV
2511 // increment.
2512 if (!isa<SCEVConstant>(IncExpr)) {
2513 const SCEV *HeadExpr = SE.getSCEV(getWideOperand(Incs[0].IVOperand));
2514 if (isa<SCEVConstant>(SE.getMinusSCEV(OperExpr, HeadExpr)))
2515 return 0;
2516 }
2517
2518 SmallPtrSet<const SCEV*, 8> Processed;
2519 return !isHighCostExpansion(IncExpr, Processed, SE);
2520}
2521
2522/// Return true if the number of registers needed for the chain is estimated to
2523/// be less than the number required for the individual IV users. First prohibit
2524/// any IV users that keep the IV live across increments (the Users set should
2525/// be empty). Next count the number and type of increments in the chain.
2526///
2527/// Chaining IVs can lead to considerable code bloat if ISEL doesn't
2528/// effectively use postinc addressing modes. Only consider it profitable it the
2529/// increments can be computed in fewer registers when chained.
2530///
2531/// TODO: Consider IVInc free if it's already used in another chains.
2532static bool
2533isProfitableChain(IVChain &Chain, SmallPtrSetImpl<Instruction*> &Users,
2534 ScalarEvolution &SE, const TargetTransformInfo &TTI) {
2535 if (StressIVChain)
2536 return true;
2537
2538 if (!Chain.hasIncs())
2539 return false;
2540
2541 if (!Users.empty()) {
2542 DEBUG(dbgs() << "Chain: " << *Chain.Incs[0].UserInst << " users:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " users:\n"; for (Instruction *Inst
: Users) { dbgs() << " " << *Inst << "\n"
; }; } } while (0)
2543 for (Instruction *Inst : Users) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " users:\n"; for (Instruction *Inst
: Users) { dbgs() << " " << *Inst << "\n"
; }; } } while (0)
2544 dbgs() << " " << *Inst << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " users:\n"; for (Instruction *Inst
: Users) { dbgs() << " " << *Inst << "\n"
; }; } } while (0)
2545 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " users:\n"; for (Instruction *Inst
: Users) { dbgs() << " " << *Inst << "\n"
; }; } } while (0)
;
2546 return false;
2547 }
2548 assert(!Chain.Incs.empty() && "empty IV chains are not allowed")((!Chain.Incs.empty() && "empty IV chains are not allowed"
) ? static_cast<void> (0) : __assert_fail ("!Chain.Incs.empty() && \"empty IV chains are not allowed\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2548, __PRETTY_FUNCTION__))
;
2549
2550 // The chain itself may require a register, so intialize cost to 1.
2551 int cost = 1;
2552
2553 // A complete chain likely eliminates the need for keeping the original IV in
2554 // a register. LSR does not currently know how to form a complete chain unless
2555 // the header phi already exists.
2556 if (isa<PHINode>(Chain.tailUserInst())
2557 && SE.getSCEV(Chain.tailUserInst()) == Chain.Incs[0].IncExpr) {
2558 --cost;
2559 }
2560 const SCEV *LastIncExpr = nullptr;
2561 unsigned NumConstIncrements = 0;
2562 unsigned NumVarIncrements = 0;
2563 unsigned NumReusedIncrements = 0;
2564 for (const IVInc &Inc : Chain) {
2565 if (Inc.IncExpr->isZero())
2566 continue;
2567
2568 // Incrementing by zero or some constant is neutral. We assume constants can
2569 // be folded into an addressing mode or an add's immediate operand.
2570 if (isa<SCEVConstant>(Inc.IncExpr)) {
2571 ++NumConstIncrements;
2572 continue;
2573 }
2574
2575 if (Inc.IncExpr == LastIncExpr)
2576 ++NumReusedIncrements;
2577 else
2578 ++NumVarIncrements;
2579
2580 LastIncExpr = Inc.IncExpr;
2581 }
2582 // An IV chain with a single increment is handled by LSR's postinc
2583 // uses. However, a chain with multiple increments requires keeping the IV's
2584 // value live longer than it needs to be if chained.
2585 if (NumConstIncrements > 1)
2586 --cost;
2587
2588 // Materializing increment expressions in the preheader that didn't exist in
2589 // the original code may cost a register. For example, sign-extended array
2590 // indices can produce ridiculous increments like this:
2591 // IV + ((sext i32 (2 * %s) to i64) + (-1 * (sext i32 %s to i64)))
2592 cost += NumVarIncrements;
2593
2594 // Reusing variable increments likely saves a register to hold the multiple of
2595 // the stride.
2596 cost -= NumReusedIncrements;
2597
2598 DEBUG(dbgs() << "Chain: " << *Chain.Incs[0].UserInst << " Cost: " << costdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " Cost: " << cost << "\n"
; } } while (0)
2599 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " Cost: " << cost << "\n"
; } } while (0)
;
2600
2601 return cost < 0;
2602}
2603
2604/// ChainInstruction - Add this IV user to an existing chain or make it the head
2605/// of a new chain.
2606void LSRInstance::ChainInstruction(Instruction *UserInst, Instruction *IVOper,
2607 SmallVectorImpl<ChainUsers> &ChainUsersVec) {
2608 // When IVs are used as types of varying widths, they are generally converted
2609 // to a wider type with some uses remaining narrow under a (free) trunc.
2610 Value *const NextIV = getWideOperand(IVOper);
2611 const SCEV *const OperExpr = SE.getSCEV(NextIV);
2612 const SCEV *const OperExprBase = getExprBase(OperExpr);
2613
2614 // Visit all existing chains. Check if its IVOper can be computed as a
2615 // profitable loop invariant increment from the last link in the Chain.
2616 unsigned ChainIdx = 0, NChains = IVChainVec.size();
2617 const SCEV *LastIncExpr = nullptr;
2618 for (; ChainIdx < NChains; ++ChainIdx) {
2619 IVChain &Chain = IVChainVec[ChainIdx];
2620
2621 // Prune the solution space aggressively by checking that both IV operands
2622 // are expressions that operate on the same unscaled SCEVUnknown. This
2623 // "base" will be canceled by the subsequent getMinusSCEV call. Checking
2624 // first avoids creating extra SCEV expressions.
2625 if (!StressIVChain && Chain.ExprBase != OperExprBase)
2626 continue;
2627
2628 Value *PrevIV = getWideOperand(Chain.Incs.back().IVOperand);
2629 if (!isCompatibleIVType(PrevIV, NextIV))
2630 continue;
2631
2632 // A phi node terminates a chain.
2633 if (isa<PHINode>(UserInst) && isa<PHINode>(Chain.tailUserInst()))
2634 continue;
2635
2636 // The increment must be loop-invariant so it can be kept in a register.
2637 const SCEV *PrevExpr = SE.getSCEV(PrevIV);
2638 const SCEV *IncExpr = SE.getMinusSCEV(OperExpr, PrevExpr);
2639 if (!SE.isLoopInvariant(IncExpr, L))
2640 continue;
2641
2642 if (Chain.isProfitableIncrement(OperExpr, IncExpr, SE)) {
2643 LastIncExpr = IncExpr;
2644 break;
2645 }
2646 }
2647 // If we haven't found a chain, create a new one, unless we hit the max. Don't
2648 // bother for phi nodes, because they must be last in the chain.
2649 if (ChainIdx == NChains) {
2650 if (isa<PHINode>(UserInst))
2651 return;
2652 if (NChains >= MaxChains && !StressIVChain) {
2653 DEBUG(dbgs() << "IV Chain Limit\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain Limit\n"; } } while
(0)
;
2654 return;
2655 }
2656 LastIncExpr = OperExpr;
2657 // IVUsers may have skipped over sign/zero extensions. We don't currently
2658 // attempt to form chains involving extensions unless they can be hoisted
2659 // into this loop's AddRec.
2660 if (!isa<SCEVAddRecExpr>(LastIncExpr))
2661 return;
2662 ++NChains;
2663 IVChainVec.push_back(IVChain(IVInc(UserInst, IVOper, LastIncExpr),
2664 OperExprBase));
2665 ChainUsersVec.resize(NChains);
2666 DEBUG(dbgs() << "IV Chain#" << ChainIdx << " Head: (" << *UserInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Head: (" << *UserInst << ") IV=" <<
*LastIncExpr << "\n"; } } while (0)
2667 << ") IV=" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Head: (" << *UserInst << ") IV=" <<
*LastIncExpr << "\n"; } } while (0)
;
2668 } else {
2669 DEBUG(dbgs() << "IV Chain#" << ChainIdx << " Inc: (" << *UserInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Inc: (" << *UserInst << ") IV+" <<
*LastIncExpr << "\n"; } } while (0)
2670 << ") IV+" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Inc: (" << *UserInst << ") IV+" <<
*LastIncExpr << "\n"; } } while (0)
;
2671 // Add this IV user to the end of the chain.
2672 IVChainVec[ChainIdx].add(IVInc(UserInst, IVOper, LastIncExpr));
2673 }
2674 IVChain &Chain = IVChainVec[ChainIdx];
2675
2676 SmallPtrSet<Instruction*,4> &NearUsers = ChainUsersVec[ChainIdx].NearUsers;
2677 // This chain's NearUsers become FarUsers.
2678 if (!LastIncExpr->isZero()) {
2679 ChainUsersVec[ChainIdx].FarUsers.insert(NearUsers.begin(),
2680 NearUsers.end());
2681 NearUsers.clear();
2682 }
2683
2684 // All other uses of IVOperand become near uses of the chain.
2685 // We currently ignore intermediate values within SCEV expressions, assuming
2686 // they will eventually be used be the current chain, or can be computed
2687 // from one of the chain increments. To be more precise we could
2688 // transitively follow its user and only add leaf IV users to the set.
2689 for (User *U : IVOper->users()) {
2690 Instruction *OtherUse = dyn_cast<Instruction>(U);
2691 if (!OtherUse)
2692 continue;
2693 // Uses in the chain will no longer be uses if the chain is formed.
2694 // Include the head of the chain in this iteration (not Chain.begin()).
2695 IVChain::const_iterator IncIter = Chain.Incs.begin();
2696 IVChain::const_iterator IncEnd = Chain.Incs.end();
2697 for( ; IncIter != IncEnd; ++IncIter) {
2698 if (IncIter->UserInst == OtherUse)
2699 break;
2700 }
2701 if (IncIter != IncEnd)
2702 continue;
2703
2704 if (SE.isSCEVable(OtherUse->getType())
2705 && !isa<SCEVUnknown>(SE.getSCEV(OtherUse))
2706 && IU.isIVUserOrOperand(OtherUse)) {
2707 continue;
2708 }
2709 NearUsers.insert(OtherUse);
2710 }
2711
2712 // Since this user is part of the chain, it's no longer considered a use
2713 // of the chain.
2714 ChainUsersVec[ChainIdx].FarUsers.erase(UserInst);
2715}
2716
2717/// CollectChains - Populate the vector of Chains.
2718///
2719/// This decreases ILP at the architecture level. Targets with ample registers,
2720/// multiple memory ports, and no register renaming probably don't want
2721/// this. However, such targets should probably disable LSR altogether.
2722///
2723/// The job of LSR is to make a reasonable choice of induction variables across
2724/// the loop. Subsequent passes can easily "unchain" computation exposing more
2725/// ILP *within the loop* if the target wants it.
2726///
2727/// Finding the best IV chain is potentially a scheduling problem. Since LSR
2728/// will not reorder memory operations, it will recognize this as a chain, but
2729/// will generate redundant IV increments. Ideally this would be corrected later
2730/// by a smart scheduler:
2731/// = A[i]
2732/// = A[i+x]
2733/// A[i] =
2734/// A[i+x] =
2735///
2736/// TODO: Walk the entire domtree within this loop, not just the path to the
2737/// loop latch. This will discover chains on side paths, but requires
2738/// maintaining multiple copies of the Chains state.
2739void LSRInstance::CollectChains() {
2740 DEBUG(dbgs() << "Collecting IV Chains.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Collecting IV Chains.\n";
} } while (0)
;
2741 SmallVector<ChainUsers, 8> ChainUsersVec;
2742
2743 SmallVector<BasicBlock *,8> LatchPath;
2744 BasicBlock *LoopHeader = L->getHeader();
2745 for (DomTreeNode *Rung = DT.getNode(L->getLoopLatch());
2746 Rung->getBlock() != LoopHeader; Rung = Rung->getIDom()) {
2747 LatchPath.push_back(Rung->getBlock());
2748 }
2749 LatchPath.push_back(LoopHeader);
2750
2751 // Walk the instruction stream from the loop header to the loop latch.
2752 for (SmallVectorImpl<BasicBlock *>::reverse_iterator
2753 BBIter = LatchPath.rbegin(), BBEnd = LatchPath.rend();
2754 BBIter != BBEnd; ++BBIter) {
2755 for (BasicBlock::iterator I = (*BBIter)->begin(), E = (*BBIter)->end();
2756 I != E; ++I) {
2757 // Skip instructions that weren't seen by IVUsers analysis.
2758 if (isa<PHINode>(I) || !IU.isIVUserOrOperand(I))
2759 continue;
2760
2761 // Ignore users that are part of a SCEV expression. This way we only
2762 // consider leaf IV Users. This effectively rediscovers a portion of
2763 // IVUsers analysis but in program order this time.
2764 if (SE.isSCEVable(I->getType()) && !isa<SCEVUnknown>(SE.getSCEV(I)))
2765 continue;
2766
2767 // Remove this instruction from any NearUsers set it may be in.
2768 for (unsigned ChainIdx = 0, NChains = IVChainVec.size();
2769 ChainIdx < NChains; ++ChainIdx) {
2770 ChainUsersVec[ChainIdx].NearUsers.erase(I);
2771 }
2772 // Search for operands that can be chained.
2773 SmallPtrSet<Instruction*, 4> UniqueOperands;
2774 User::op_iterator IVOpEnd = I->op_end();
2775 User::op_iterator IVOpIter = findIVOperand(I->op_begin(), IVOpEnd, L, SE);
2776 while (IVOpIter != IVOpEnd) {
2777 Instruction *IVOpInst = cast<Instruction>(*IVOpIter);
2778 if (UniqueOperands.insert(IVOpInst).second)
2779 ChainInstruction(I, IVOpInst, ChainUsersVec);
2780 IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);
2781 }
2782 } // Continue walking down the instructions.
2783 } // Continue walking down the domtree.
2784 // Visit phi backedges to determine if the chain can generate the IV postinc.
2785 for (BasicBlock::iterator I = L->getHeader()->begin();
2786 PHINode *PN = dyn_cast<PHINode>(I); ++I) {
2787 if (!SE.isSCEVable(PN->getType()))
2788 continue;
2789
2790 Instruction *IncV =
2791 dyn_cast<Instruction>(PN->getIncomingValueForBlock(L->getLoopLatch()));
2792 if (IncV)
2793 ChainInstruction(PN, IncV, ChainUsersVec);
2794 }
2795 // Remove any unprofitable chains.
2796 unsigned ChainIdx = 0;
2797 for (unsigned UsersIdx = 0, NChains = IVChainVec.size();
2798 UsersIdx < NChains; ++UsersIdx) {
2799 if (!isProfitableChain(IVChainVec[UsersIdx],
2800 ChainUsersVec[UsersIdx].FarUsers, SE, TTI))
2801 continue;
2802 // Preserve the chain at UsesIdx.
2803 if (ChainIdx != UsersIdx)
2804 IVChainVec[ChainIdx] = IVChainVec[UsersIdx];
2805 FinalizeChain(IVChainVec[ChainIdx]);
2806 ++ChainIdx;
2807 }
2808 IVChainVec.resize(ChainIdx);
2809}
2810
2811void LSRInstance::FinalizeChain(IVChain &Chain) {
2812 assert(!Chain.Incs.empty() && "empty IV chains are not allowed")((!Chain.Incs.empty() && "empty IV chains are not allowed"
) ? static_cast<void> (0) : __assert_fail ("!Chain.Incs.empty() && \"empty IV chains are not allowed\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2812, __PRETTY_FUNCTION__))
;
2813 DEBUG(dbgs() << "Final Chain: " << *Chain.Incs[0].UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Final Chain: " << *
Chain.Incs[0].UserInst << "\n"; } } while (0)
;
2814
2815 for (const IVInc &Inc : Chain) {
2816 DEBUG(dbgs() << " Inc: " << Inc.UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Inc: " << Inc
.UserInst << "\n"; } } while (0)
;
2817 auto UseI = std::find(Inc.UserInst->op_begin(), Inc.UserInst->op_end(),
2818 Inc.IVOperand);
2819 assert(UseI != Inc.UserInst->op_end() && "cannot find IV operand")((UseI != Inc.UserInst->op_end() && "cannot find IV operand"
) ? static_cast<void> (0) : __assert_fail ("UseI != Inc.UserInst->op_end() && \"cannot find IV operand\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2819, __PRETTY_FUNCTION__))
;
2820 IVIncSet.insert(UseI);
2821 }
2822}
2823
2824/// Return true if the IVInc can be folded into an addressing mode.
2825static bool canFoldIVIncExpr(const SCEV *IncExpr, Instruction *UserInst,
2826 Value *Operand, const TargetTransformInfo &TTI) {
2827 const SCEVConstant *IncConst = dyn_cast<SCEVConstant>(IncExpr);
2828 if (!IncConst || !isAddressUse(UserInst, Operand))
2829 return false;
2830
2831 if (IncConst->getValue()->getValue().getMinSignedBits() > 64)
2832 return false;
2833
2834 int64_t IncOffset = IncConst->getValue()->getSExtValue();
2835 if (!isAlwaysFoldable(TTI, LSRUse::Address,
2836 getAccessType(UserInst), /*BaseGV=*/ nullptr,
2837 IncOffset, /*HaseBaseReg=*/ false))
2838 return false;
2839
2840 return true;
2841}
2842
2843/// GenerateIVChains - Generate an add or subtract for each IVInc in a chain to
2844/// materialize the IV user's operand from the previous IV user's operand.
2845void LSRInstance::GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,
2846 SmallVectorImpl<WeakVH> &DeadInsts) {
2847 // Find the new IVOperand for the head of the chain. It may have been replaced
2848 // by LSR.
2849 const IVInc &Head = Chain.Incs[0];
2850 User::op_iterator IVOpEnd = Head.UserInst->op_end();
2851 // findIVOperand returns IVOpEnd if it can no longer find a valid IV user.
2852 User::op_iterator IVOpIter = findIVOperand(Head.UserInst->op_begin(),
2853 IVOpEnd, L, SE);
2854 Value *IVSrc = nullptr;
2855 while (IVOpIter != IVOpEnd) {
2856 IVSrc = getWideOperand(*IVOpIter);
2857
2858 // If this operand computes the expression that the chain needs, we may use
2859 // it. (Check this after setting IVSrc which is used below.)
2860 //
2861 // Note that if Head.IncExpr is wider than IVSrc, then this phi is too
2862 // narrow for the chain, so we can no longer use it. We do allow using a
2863 // wider phi, assuming the LSR checked for free truncation. In that case we
2864 // should already have a truncate on this operand such that
2865 // getSCEV(IVSrc) == IncExpr.
2866 if (SE.getSCEV(*IVOpIter) == Head.IncExpr
2867 || SE.getSCEV(IVSrc) == Head.IncExpr) {
2868 break;
2869 }
2870 IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);
2871 }
2872 if (IVOpIter == IVOpEnd) {
2873 // Gracefully give up on this chain.
2874 DEBUG(dbgs() << "Concealed chain head: " << *Head.UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Concealed chain head: " <<
*Head.UserInst << "\n"; } } while (0)
;
2875 return;
2876 }
2877
2878 DEBUG(dbgs() << "Generate chain at: " << *IVSrc << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generate chain at: " <<
*IVSrc << "\n"; } } while (0)
;
2879 Type *IVTy = IVSrc->getType();
2880 Type *IntTy = SE.getEffectiveSCEVType(IVTy);
2881 const SCEV *LeftOverExpr = nullptr;
2882 for (const IVInc &Inc : Chain) {
2883 Instruction *InsertPt = Inc.UserInst;
2884 if (isa<PHINode>(InsertPt))
2885 InsertPt = L->getLoopLatch()->getTerminator();
2886
2887 // IVOper will replace the current IV User's operand. IVSrc is the IV
2888 // value currently held in a register.
2889 Value *IVOper = IVSrc;
2890 if (!Inc.IncExpr->isZero()) {
2891 // IncExpr was the result of subtraction of two narrow values, so must
2892 // be signed.
2893 const SCEV *IncExpr = SE.getNoopOrSignExtend(Inc.IncExpr, IntTy);
2894 LeftOverExpr = LeftOverExpr ?
2895 SE.getAddExpr(LeftOverExpr, IncExpr) : IncExpr;
2896 }
2897 if (LeftOverExpr && !LeftOverExpr->isZero()) {
2898 // Expand the IV increment.
2899 Rewriter.clearPostInc();
2900 Value *IncV = Rewriter.expandCodeFor(LeftOverExpr, IntTy, InsertPt);
2901 const SCEV *IVOperExpr = SE.getAddExpr(SE.getUnknown(IVSrc),
2902 SE.getUnknown(IncV));
2903 IVOper = Rewriter.expandCodeFor(IVOperExpr, IVTy, InsertPt);
2904
2905 // If an IV increment can't be folded, use it as the next IV value.
2906 if (!canFoldIVIncExpr(LeftOverExpr, Inc.UserInst, Inc.IVOperand, TTI)) {
2907 assert(IVTy == IVOper->getType() && "inconsistent IV increment type")((IVTy == IVOper->getType() && "inconsistent IV increment type"
) ? static_cast<void> (0) : __assert_fail ("IVTy == IVOper->getType() && \"inconsistent IV increment type\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2907, __PRETTY_FUNCTION__))
;
2908 IVSrc = IVOper;
2909 LeftOverExpr = nullptr;
2910 }
2911 }
2912 Type *OperTy = Inc.IVOperand->getType();
2913 if (IVTy != OperTy) {
2914 assert(SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) &&((SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy
) && "cannot extend a chained IV") ? static_cast<void
> (0) : __assert_fail ("SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) && \"cannot extend a chained IV\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2915, __PRETTY_FUNCTION__))
2915 "cannot extend a chained IV")((SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy
) && "cannot extend a chained IV") ? static_cast<void
> (0) : __assert_fail ("SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) && \"cannot extend a chained IV\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2915, __PRETTY_FUNCTION__))
;
2916 IRBuilder<> Builder(InsertPt);
2917 IVOper = Builder.CreateTruncOrBitCast(IVOper, OperTy, "lsr.chain");
2918 }
2919 Inc.UserInst->replaceUsesOfWith(Inc.IVOperand, IVOper);
2920 DeadInsts.emplace_back(Inc.IVOperand);
2921 }
2922 // If LSR created a new, wider phi, we may also replace its postinc. We only
2923 // do this if we also found a wide value for the head of the chain.
2924 if (isa<PHINode>(Chain.tailUserInst())) {
2925 for (BasicBlock::iterator I = L->getHeader()->begin();
2926 PHINode *Phi = dyn_cast<PHINode>(I); ++I) {
2927 if (!isCompatibleIVType(Phi, IVSrc))
2928 continue;
2929 Instruction *PostIncV = dyn_cast<Instruction>(
2930 Phi->getIncomingValueForBlock(L->getLoopLatch()));
2931 if (!PostIncV || (SE.getSCEV(PostIncV) != SE.getSCEV(IVSrc)))
2932 continue;
2933 Value *IVOper = IVSrc;
2934 Type *PostIncTy = PostIncV->getType();
2935 if (IVTy != PostIncTy) {
2936 assert(PostIncTy->isPointerTy() && "mixing int/ptr IV types")((PostIncTy->isPointerTy() && "mixing int/ptr IV types"
) ? static_cast<void> (0) : __assert_fail ("PostIncTy->isPointerTy() && \"mixing int/ptr IV types\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2936, __PRETTY_FUNCTION__))
;
2937 IRBuilder<> Builder(L->getLoopLatch()->getTerminator());
2938 Builder.SetCurrentDebugLocation(PostIncV->getDebugLoc());
2939 IVOper = Builder.CreatePointerCast(IVSrc, PostIncTy, "lsr.chain");
2940 }
2941 Phi->replaceUsesOfWith(PostIncV, IVOper);
2942 DeadInsts.emplace_back(PostIncV);
2943 }
2944 }
2945}
2946
2947void LSRInstance::CollectFixupsAndInitialFormulae() {
2948 for (const IVStrideUse &U : IU) {
2949 Instruction *UserInst = U.getUser();
2950 // Skip IV users that are part of profitable IV Chains.
2951 User::op_iterator UseI = std::find(UserInst->op_begin(), UserInst->op_end(),
2952 U.getOperandValToReplace());
2953 assert(UseI != UserInst->op_end() && "cannot find IV operand")((UseI != UserInst->op_end() && "cannot find IV operand"
) ? static_cast<void> (0) : __assert_fail ("UseI != UserInst->op_end() && \"cannot find IV operand\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2953, __PRETTY_FUNCTION__))
;
2954 if (IVIncSet.count(UseI))
2955 continue;
2956
2957 // Record the uses.
2958 LSRFixup &LF = getNewFixup();
2959 LF.UserInst = UserInst;
2960 LF.OperandValToReplace = U.getOperandValToReplace();
2961 LF.PostIncLoops = U.getPostIncLoops();
2962
2963 LSRUse::KindType Kind = LSRUse::Basic;
2964 Type *AccessTy = nullptr;
2965 if (isAddressUse(LF.UserInst, LF.OperandValToReplace)) {
2966 Kind = LSRUse::Address;
2967 AccessTy = getAccessType(LF.UserInst);
2968 }
2969
2970 const SCEV *S = IU.getExpr(U);
2971
2972 // Equality (== and !=) ICmps are special. We can rewrite (i == N) as
2973 // (N - i == 0), and this allows (N - i) to be the expression that we work
2974 // with rather than just N or i, so we can consider the register
2975 // requirements for both N and i at the same time. Limiting this code to
2976 // equality icmps is not a problem because all interesting loops use
2977 // equality icmps, thanks to IndVarSimplify.
2978 if (ICmpInst *CI = dyn_cast<ICmpInst>(LF.UserInst))
2979 if (CI->isEquality()) {
2980 // Swap the operands if needed to put the OperandValToReplace on the
2981 // left, for consistency.
2982 Value *NV = CI->getOperand(1);
2983 if (NV == LF.OperandValToReplace) {
2984 CI->setOperand(1, CI->getOperand(0));
2985 CI->setOperand(0, NV);
2986 NV = CI->getOperand(1);
2987 Changed = true;
2988 }
2989
2990 // x == y --> x - y == 0
2991 const SCEV *N = SE.getSCEV(NV);
2992 if (SE.isLoopInvariant(N, L) && isSafeToExpand(N, SE)) {
2993 // S is normalized, so normalize N before folding it into S
2994 // to keep the result normalized.
2995 N = TransformForPostIncUse(Normalize, N, CI, nullptr,
2996 LF.PostIncLoops, SE, DT);
2997 Kind = LSRUse::ICmpZero;
2998 S = SE.getMinusSCEV(N, S);
2999 }
3000
3001 // -1 and the negations of all interesting strides (except the negation
3002 // of -1) are now also interesting.
3003 for (size_t i = 0, e = Factors.size(); i != e; ++i)
3004 if (Factors[i] != -1)
3005 Factors.insert(-(uint64_t)Factors[i]);
3006 Factors.insert(-1);
3007 }
3008
3009 // Set up the initial formula for this use.
3010 std::pair<size_t, int64_t> P = getUse(S, Kind, AccessTy);
3011 LF.LUIdx = P.first;
3012 LF.Offset = P.second;
3013 LSRUse &LU = Uses[LF.LUIdx];
3014 LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);
3015 if (!LU.WidestFixupType ||
3016 SE.getTypeSizeInBits(LU.WidestFixupType) <
3017 SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))
3018 LU.WidestFixupType = LF.OperandValToReplace->getType();
3019
3020 // If this is the first use of this LSRUse, give it a formula.
3021 if (LU.Formulae.empty()) {
3022 InsertInitialFormula(S, LU, LF.LUIdx);
3023 CountRegisters(LU.Formulae.back(), LF.LUIdx);
3024 }
3025 }
3026
3027 DEBUG(print_fixups(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_fixups(dbgs()); } } while (0)
;
3028}
3029
3030/// InsertInitialFormula - Insert a formula for the given expression into
3031/// the given use, separating out loop-variant portions from loop-invariant
3032/// and loop-computable portions.
3033void
3034LSRInstance::InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx) {
3035 // Mark uses whose expressions cannot be expanded.
3036 if (!isSafeToExpand(S, SE))
3037 LU.RigidFormula = true;
3038
3039 Formula F;
3040 F.InitialMatch(S, L, SE);
3041 bool Inserted = InsertFormula(LU, LUIdx, F);
3042 assert(Inserted && "Initial formula already exists!")((Inserted && "Initial formula already exists!") ? static_cast
<void> (0) : __assert_fail ("Inserted && \"Initial formula already exists!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3042, __PRETTY_FUNCTION__))
; (void)Inserted;
3043}
3044
3045/// InsertSupplementalFormula - Insert a simple single-register formula for
3046/// the given expression into the given use.
3047void
3048LSRInstance::InsertSupplementalFormula(const SCEV *S,
3049 LSRUse &LU, size_t LUIdx) {
3050 Formula F;
3051 F.BaseRegs.push_back(S);
3052 F.HasBaseReg = true;
3053 bool Inserted = InsertFormula(LU, LUIdx, F);
3054 assert(Inserted && "Supplemental formula already exists!")((Inserted && "Supplemental formula already exists!")
? static_cast<void> (0) : __assert_fail ("Inserted && \"Supplemental formula already exists!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3054, __PRETTY_FUNCTION__))
; (void)Inserted;
3055}
3056
3057/// CountRegisters - Note which registers are used by the given formula,
3058/// updating RegUses.
3059void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) {
3060 if (F.ScaledReg)
3061 RegUses.CountRegister(F.ScaledReg, LUIdx);
3062 for (const SCEV *BaseReg : F.BaseRegs)
3063 RegUses.CountRegister(BaseReg, LUIdx);
3064}
3065
3066/// InsertFormula - If the given formula has not yet been inserted, add it to
3067/// the list, and return true. Return false otherwise.
3068bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) {
3069 // Do not insert formula that we will not be able to expand.
3070 assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) &&((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, F) && "Formula is illegal") ? static_cast<void>
(0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Formula is illegal\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3071, __PRETTY_FUNCTION__))
3071 "Formula is illegal")((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, F) && "Formula is illegal") ? static_cast<void>
(0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Formula is illegal\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3071, __PRETTY_FUNCTION__))
;
3072 if (!LU.InsertFormula(F))
3073 return false;
3074
3075 CountRegisters(F, LUIdx);
3076 return true;
3077}
3078
3079/// CollectLoopInvariantFixupsAndFormulae - Check for other uses of
3080/// loop-invariant values which we're tracking. These other uses will pin these
3081/// values in registers, making them less profitable for elimination.
3082/// TODO: This currently misses non-constant addrec step registers.
3083/// TODO: Should this give more weight to users inside the loop?
3084void
3085LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
3086 SmallVector<const SCEV *, 8> Worklist(RegUses.begin(), RegUses.end());
3087 SmallPtrSet<const SCEV *, 32> Visited;
3088
3089 while (!Worklist.empty()) {
3090 const SCEV *S = Worklist.pop_back_val();
3091
3092 // Don't process the same SCEV twice
3093 if (!Visited.insert(S).second)
3094 continue;
3095
3096 if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S))
3097 Worklist.append(N->op_begin(), N->op_end());
3098 else if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S))
3099 Worklist.push_back(C->getOperand());
3100 else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
3101 Worklist.push_back(D->getLHS());
3102 Worklist.push_back(D->getRHS());
3103 } else if (const SCEVUnknown *US = dyn_cast<SCEVUnknown>(S)) {
3104 const Value *V = US->getValue();
3105 if (const Instruction *Inst = dyn_cast<Instruction>(V)) {
3106 // Look for instructions defined outside the loop.
3107 if (L->contains(Inst)) continue;
3108 } else if (isa<UndefValue>(V))
3109 // Undef doesn't have a live range, so it doesn't matter.
3110 continue;
3111 for (const Use &U : V->uses()) {
3112 const Instruction *UserInst = dyn_cast<Instruction>(U.getUser());
3113 // Ignore non-instructions.
3114 if (!UserInst)
3115 continue;
3116 // Ignore instructions in other functions (as can happen with
3117 // Constants).
3118 if (UserInst->getParent()->getParent() != L->getHeader()->getParent())
3119 continue;
3120 // Ignore instructions not dominated by the loop.
3121 const BasicBlock *UseBB = !isa<PHINode>(UserInst) ?
3122 UserInst->getParent() :
3123 cast<PHINode>(UserInst)->getIncomingBlock(
3124 PHINode::getIncomingValueNumForOperand(U.getOperandNo()));
3125 if (!DT.dominates(L->getHeader(), UseBB))
3126 continue;
3127 // Ignore uses which are part of other SCEV expressions, to avoid
3128 // analyzing them multiple times.
3129 if (SE.isSCEVable(UserInst->getType())) {
3130 const SCEV *UserS = SE.getSCEV(const_cast<Instruction *>(UserInst));
3131 // If the user is a no-op, look through to its uses.
3132 if (!isa<SCEVUnknown>(UserS))
3133 continue;
3134 if (UserS == US) {
3135 Worklist.push_back(
3136 SE.getUnknown(const_cast<Instruction *>(UserInst)));
3137 continue;
3138 }
3139 }
3140 // Ignore icmp instructions which are already being analyzed.
3141 if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) {
3142 unsigned OtherIdx = !U.getOperandNo();
3143 Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx));
3144 if (SE.hasComputableLoopEvolution(SE.getSCEV(OtherOp), L))
3145 continue;
3146 }
3147
3148 LSRFixup &LF = getNewFixup();
3149 LF.UserInst = const_cast<Instruction *>(UserInst);
3150 LF.OperandValToReplace = U;
3151 std::pair<size_t, int64_t> P = getUse(S, LSRUse::Basic, nullptr);
3152 LF.LUIdx = P.first;
3153 LF.Offset = P.second;
3154 LSRUse &LU = Uses[LF.LUIdx];
3155 LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);
3156 if (!LU.WidestFixupType ||
3157 SE.getTypeSizeInBits(LU.WidestFixupType) <
3158 SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))
3159 LU.WidestFixupType = LF.OperandValToReplace->getType();
3160 InsertSupplementalFormula(US, LU, LF.LUIdx);
3161 CountRegisters(LU.Formulae.back(), Uses.size() - 1);
3162 break;
3163 }
3164 }
3165 }
3166}
3167
3168/// CollectSubexprs - Split S into subexpressions which can be pulled out into
3169/// separate registers. If C is non-null, multiply each subexpression by C.
3170///
3171/// Return remainder expression after factoring the subexpressions captured by
3172/// Ops. If Ops is complete, return NULL.
3173static const SCEV *CollectSubexprs(const SCEV *S, const SCEVConstant *C,
3174 SmallVectorImpl<const SCEV *> &Ops,
3175 const Loop *L,
3176 ScalarEvolution &SE,
3177 unsigned Depth = 0) {
3178 // Arbitrarily cap recursion to protect compile time.
3179 if (Depth >= 3)
3180 return S;
3181
3182 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
3183 // Break out add operands.
3184 for (const SCEV *S : Add->operands()) {
3185 const SCEV *Remainder = CollectSubexprs(S, C, Ops, L, SE, Depth+1);
3186 if (Remainder)
3187 Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);
3188 }
3189 return nullptr;
3190 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
3191 // Split a non-zero base out of an addrec.
3192 if (AR->getStart()->isZero())
3193 return S;
3194
3195 const SCEV *Remainder = CollectSubexprs(AR->getStart(),
3196 C, Ops, L, SE, Depth+1);
3197 // Split the non-zero AddRec unless it is part of a nested recurrence that
3198 // does not pertain to this loop.
3199 if (Remainder && (AR->getLoop() == L || !isa<SCEVAddRecExpr>(Remainder))) {
3200 Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);
3201 Remainder = nullptr;
3202 }
3203 if (Remainder != AR->getStart()) {
3204 if (!Remainder)
3205 Remainder = SE.getConstant(AR->getType(), 0);
3206 return SE.getAddRecExpr(Remainder,
3207 AR->getStepRecurrence(SE),
3208 AR->getLoop(),
3209 //FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
3210 SCEV::FlagAnyWrap);
3211 }
3212 } else if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
3213 // Break (C * (a + b + c)) into C*a + C*b + C*c.
3214 if (Mul->getNumOperands() != 2)
3215 return S;
3216 if (const SCEVConstant *Op0 =
3217 dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3218 C = C ? cast<SCEVConstant>(SE.getMulExpr(C, Op0)) : Op0;
3219 const SCEV *Remainder =
3220 CollectSubexprs(Mul->getOperand(1), C, Ops, L, SE, Depth+1);
3221 if (Remainder)
3222 Ops.push_back(SE.getMulExpr(C, Remainder));
3223 return nullptr;
3224 }
3225 }
3226 return S;
3227}
3228
3229/// \brief Helper function for LSRInstance::GenerateReassociations.
3230void LSRInstance::GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,
3231 const Formula &Base,
3232 unsigned Depth, size_t Idx,
3233 bool IsScaledReg) {
3234 const SCEV *BaseReg = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3235 SmallVector<const SCEV *, 8> AddOps;
3236 const SCEV *Remainder = CollectSubexprs(BaseReg, nullptr, AddOps, L, SE);
3237 if (Remainder)
3238 AddOps.push_back(Remainder);
3239
3240 if (AddOps.size() == 1)
3241 return;
3242
3243 for (SmallVectorImpl<const SCEV *>::const_iterator J = AddOps.begin(),
3244 JE = AddOps.end();
3245 J != JE; ++J) {
3246
3247 // Loop-variant "unknown" values are uninteresting; we won't be able to
3248 // do anything meaningful with them.
3249 if (isa<SCEVUnknown>(*J) && !SE.isLoopInvariant(*J, L))
3250 continue;
3251
3252 // Don't pull a constant into a register if the constant could be folded
3253 // into an immediate field.
3254 if (isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,
3255 LU.AccessTy, *J, Base.getNumRegs() > 1))
3256 continue;
3257
3258 // Collect all operands except *J.
3259 SmallVector<const SCEV *, 8> InnerAddOps(
3260 ((const SmallVector<const SCEV *, 8> &)AddOps).begin(), J);
3261 InnerAddOps.append(std::next(J),
3262 ((const SmallVector<const SCEV *, 8> &)AddOps).end());
3263
3264 // Don't leave just a constant behind in a register if the constant could
3265 // be folded into an immediate field.
3266 if (InnerAddOps.size() == 1 &&
3267 isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,
3268 LU.AccessTy, InnerAddOps[0], Base.getNumRegs() > 1))
3269 continue;
3270
3271 const SCEV *InnerSum = SE.getAddExpr(InnerAddOps);
3272 if (InnerSum->isZero())
3273 continue;
3274 Formula F = Base;
3275
3276 // Add the remaining pieces of the add back into the new formula.
3277 const SCEVConstant *InnerSumSC = dyn_cast<SCEVConstant>(InnerSum);
3278 if (InnerSumSC && SE.getTypeSizeInBits(InnerSumSC->getType()) <= 64 &&
3279 TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +
3280 InnerSumSC->getValue()->getZExtValue())) {
3281 F.UnfoldedOffset =
3282 (uint64_t)F.UnfoldedOffset + InnerSumSC->getValue()->getZExtValue();
3283 if (IsScaledReg)
3284 F.ScaledReg = nullptr;
3285 else
3286 F.BaseRegs.erase(F.BaseRegs.begin() + Idx);
3287 } else if (IsScaledReg)
3288 F.ScaledReg = InnerSum;
3289 else
3290 F.BaseRegs[Idx] = InnerSum;
3291
3292 // Add J as its own register, or an unfolded immediate.
3293 const SCEVConstant *SC = dyn_cast<SCEVConstant>(*J);
3294 if (SC && SE.getTypeSizeInBits(SC->getType()) <= 64 &&
3295 TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +
3296 SC->getValue()->getZExtValue()))
3297 F.UnfoldedOffset =
3298 (uint64_t)F.UnfoldedOffset + SC->getValue()->getZExtValue();
3299 else
3300 F.BaseRegs.push_back(*J);
3301 // We may have changed the number of register in base regs, adjust the
3302 // formula accordingly.
3303 F.Canonicalize();
3304
3305 if (InsertFormula(LU, LUIdx, F))
3306 // If that formula hadn't been seen before, recurse to find more like
3307 // it.
3308 GenerateReassociations(LU, LUIdx, LU.Formulae.back(), Depth + 1);
3309 }
3310}
3311
3312/// GenerateReassociations - Split out subexpressions from adds and the bases of
3313/// addrecs.
3314void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx,
3315 Formula Base, unsigned Depth) {
3316 assert(Base.isCanonical() && "Input must be in the canonical form")((Base.isCanonical() && "Input must be in the canonical form"
) ? static_cast<void> (0) : __assert_fail ("Base.isCanonical() && \"Input must be in the canonical form\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3316, __PRETTY_FUNCTION__))
;
3317 // Arbitrarily cap recursion to protect compile time.
3318 if (Depth >= 3)
3319 return;
3320
3321 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3322 GenerateReassociationsImpl(LU, LUIdx, Base, Depth, i);
3323
3324 if (Base.Scale == 1)
3325 GenerateReassociationsImpl(LU, LUIdx, Base, Depth,
3326 /* Idx */ -1, /* IsScaledReg */ true);
3327}
3328
3329/// GenerateCombinations - Generate a formula consisting of all of the
3330/// loop-dominating registers added into a single register.
3331void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx,
3332 Formula Base) {
3333 // This method is only interesting on a plurality of registers.
3334 if (Base.BaseRegs.size() + (Base.Scale == 1) <= 1)
3335 return;
3336
3337 // Flatten the representation, i.e., reg1 + 1*reg2 => reg1 + reg2, before
3338 // processing the formula.
3339 Base.Unscale();
3340 Formula F = Base;
3341 F.BaseRegs.clear();
3342 SmallVector<const SCEV *, 4> Ops;
3343 for (const SCEV *BaseReg : Base.BaseRegs) {
3344 if (SE.properlyDominates(BaseReg, L->getHeader()) &&
3345 !SE.hasComputableLoopEvolution(BaseReg, L))
3346 Ops.push_back(BaseReg);
3347 else
3348 F.BaseRegs.push_back(BaseReg);
3349 }
3350 if (Ops.size() > 1) {
3351 const SCEV *Sum = SE.getAddExpr(Ops);
3352 // TODO: If Sum is zero, it probably means ScalarEvolution missed an
3353 // opportunity to fold something. For now, just ignore such cases
3354 // rather than proceed with zero in a register.
3355 if (!Sum->isZero()) {
3356 F.BaseRegs.push_back(Sum);
3357 F.Canonicalize();
3358 (void)InsertFormula(LU, LUIdx, F);
3359 }
3360 }
3361}
3362
3363/// \brief Helper function for LSRInstance::GenerateSymbolicOffsets.
3364void LSRInstance::GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,
3365 const Formula &Base, size_t Idx,
3366 bool IsScaledReg) {
3367 const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3368 GlobalValue *GV = ExtractSymbol(G, SE);
3369 if (G->isZero() || !GV)
3370 return;
3371 Formula F = Base;
3372 F.BaseGV = GV;
3373 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))
3374 return;
3375 if (IsScaledReg)
3376 F.ScaledReg = G;
3377 else
3378 F.BaseRegs[Idx] = G;
3379 (void)InsertFormula(LU, LUIdx, F);
3380}
3381
3382/// GenerateSymbolicOffsets - Generate reuse formulae using symbolic offsets.
3383void LSRInstance::GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx,
3384 Formula Base) {
3385 // We can't add a symbolic offset if the address already contains one.
3386 if (Base.BaseGV) return;
3387
3388 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3389 GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, i);
3390 if (Base.Scale == 1)
3391 GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, /* Idx */ -1,
3392 /* IsScaledReg */ true);
3393}
3394
3395/// \brief Helper function for LSRInstance::GenerateConstantOffsets.
3396void LSRInstance::GenerateConstantOffsetsImpl(
3397 LSRUse &LU, unsigned LUIdx, const Formula &Base,
3398 const SmallVectorImpl<int64_t> &Worklist, size_t Idx, bool IsScaledReg) {
3399 const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3400 for (int64_t Offset : Worklist) {
3401 Formula F = Base;
3402 F.BaseOffset = (uint64_t)Base.BaseOffset - Offset;
3403 if (isLegalUse(TTI, LU.MinOffset - Offset, LU.MaxOffset - Offset, LU.Kind,
3404 LU.AccessTy, F)) {
3405 // Add the offset to the base register.
3406 const SCEV *NewG = SE.getAddExpr(SE.getConstant(G->getType(), Offset), G);
3407 // If it cancelled out, drop the base register, otherwise update it.
3408 if (NewG->isZero()) {
3409 if (IsScaledReg) {
3410 F.Scale = 0;
3411 F.ScaledReg = nullptr;
3412 } else
3413 F.DeleteBaseReg(F.BaseRegs[Idx]);
3414 F.Canonicalize();
3415 } else if (IsScaledReg)
3416 F.ScaledReg = NewG;
3417 else
3418 F.BaseRegs[Idx] = NewG;
3419
3420 (void)InsertFormula(LU, LUIdx, F);
3421 }
3422 }
3423
3424 int64_t Imm = ExtractImmediate(G, SE);
3425 if (G->isZero() || Imm == 0)
3426 return;
3427 Formula F = Base;
3428 F.BaseOffset = (uint64_t)F.BaseOffset + Imm;
3429 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))
3430 return;
3431 if (IsScaledReg)
3432 F.ScaledReg = G;
3433 else
3434 F.BaseRegs[Idx] = G;
3435 (void)InsertFormula(LU, LUIdx, F);
3436}
3437
3438/// GenerateConstantOffsets - Generate reuse formulae using symbolic offsets.
3439void LSRInstance::GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx,
3440 Formula Base) {
3441 // TODO: For now, just add the min and max offset, because it usually isn't
3442 // worthwhile looking at everything inbetween.
3443 SmallVector<int64_t, 2> Worklist;
3444 Worklist.push_back(LU.MinOffset);
3445 if (LU.MaxOffset != LU.MinOffset)
3446 Worklist.push_back(LU.MaxOffset);
3447
3448 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3449 GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, i);
3450 if (Base.Scale == 1)
3451 GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, /* Idx */ -1,
3452 /* IsScaledReg */ true);
3453}
3454
3455/// GenerateICmpZeroScales - For ICmpZero, check to see if we can scale up
3456/// the comparison. For example, x == y -> x*c == y*c.
3457void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,
3458 Formula Base) {
3459 if (LU.Kind != LSRUse::ICmpZero) return;
3460
3461 // Determine the integer type for the base formula.
3462 Type *IntTy = Base.getType();
3463 if (!IntTy) return;
3464 if (SE.getTypeSizeInBits(IntTy) > 64) return;
3465
3466 // Don't do this if there is more than one offset.
3467 if (LU.MinOffset != LU.MaxOffset) return;
3468
3469 assert(!Base.BaseGV && "ICmpZero use is not legal!")((!Base.BaseGV && "ICmpZero use is not legal!") ? static_cast
<void> (0) : __assert_fail ("!Base.BaseGV && \"ICmpZero use is not legal!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3469, __PRETTY_FUNCTION__))
;
3470
3471 // Check each interesting stride.
3472 for (int64_t Factor : Factors) {
3473 // Check that the multiplication doesn't overflow.
3474 if (Base.BaseOffset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)
3475 continue;
3476 int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor;
3477 if (NewBaseOffset / Factor != Base.BaseOffset)
3478 continue;
3479 // If the offset will be truncated at this use, check that it is in bounds.
3480 if (!IntTy->isPointerTy() &&
3481 !ConstantInt::isValueValidForType(IntTy, NewBaseOffset))
3482 continue;
3483
3484 // Check that multiplying with the use offset doesn't overflow.
3485 int64_t Offset = LU.MinOffset;
3486 if (Offset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)
3487 continue;
3488 Offset = (uint64_t)Offset * Factor;
3489 if (Offset / Factor != LU.MinOffset)
3490 continue;
3491 // If the offset will be truncated at this use, check that it is in bounds.
3492 if (!IntTy->isPointerTy() &&
3493 !ConstantInt::isValueValidForType(IntTy, Offset))
3494 continue;
3495
3496 Formula F = Base;
3497 F.BaseOffset = NewBaseOffset;
3498
3499 // Check that this scale is legal.
3500 if (!isLegalUse(TTI, Offset, Offset, LU.Kind, LU.AccessTy, F))
3501 continue;
3502
3503 // Compensate for the use having MinOffset built into it.
3504 F.BaseOffset = (uint64_t)F.BaseOffset + Offset - LU.MinOffset;
3505
3506 const SCEV *FactorS = SE.getConstant(IntTy, Factor);
3507
3508 // Check that multiplying with each base register doesn't overflow.
3509 for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) {
3510 F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS);
3511 if (getExactSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i])
3512 goto next;
3513 }
3514
3515 // Check that multiplying with the scaled register doesn't overflow.
3516 if (F.ScaledReg) {
3517 F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS);
3518 if (getExactSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg)
3519 continue;
3520 }
3521
3522 // Check that multiplying with the unfolded offset doesn't overflow.
3523 if (F.UnfoldedOffset != 0) {
3524 if (F.UnfoldedOffset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)
3525 continue;
3526 F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor;
3527 if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset)
3528 continue;
3529 // If the offset will be truncated, check that it is in bounds.
3530 if (!IntTy->isPointerTy() &&
3531 !ConstantInt::isValueValidForType(IntTy, F.UnfoldedOffset))
3532 continue;
3533 }
3534
3535 // If we make it here and it's legal, add it.
3536 (void)InsertFormula(LU, LUIdx, F);
3537 next:;
3538 }
3539}
3540
3541/// GenerateScales - Generate stride factor reuse formulae by making use of
3542/// scaled-offset address modes, for example.
3543void LSRInstance::GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base) {
3544 // Determine the integer type for the base formula.
3545 Type *IntTy = Base.getType();
3546 if (!IntTy) return;
3547
3548 // If this Formula already has a scaled register, we can't add another one.
3549 // Try to unscale the formula to generate a better scale.
3550 if (Base.Scale != 0 && !Base.Unscale())
3551 return;
3552
3553 assert(Base.Scale == 0 && "Unscale did not did its job!")((Base.Scale == 0 && "Unscale did not did its job!") ?
static_cast<void> (0) : __assert_fail ("Base.Scale == 0 && \"Unscale did not did its job!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3553, __PRETTY_FUNCTION__))
;
3554
3555 // Check each interesting stride.
3556 for (int64_t Factor : Factors) {
3557 Base.Scale = Factor;
3558 Base.HasBaseReg = Base.BaseRegs.size() > 1;
3559 // Check whether this scale is going to be legal.
3560 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,
3561 Base)) {
3562 // As a special-case, handle special out-of-loop Basic users specially.
3563 // TODO: Reconsider this special case.
3564 if (LU.Kind == LSRUse::Basic &&
3565 isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LSRUse::Special,
3566 LU.AccessTy, Base) &&
3567 LU.AllFixupsOutsideLoop)
3568 LU.Kind = LSRUse::Special;
3569 else
3570 continue;
3571 }
3572 // For an ICmpZero, negating a solitary base register won't lead to
3573 // new solutions.
3574 if (LU.Kind == LSRUse::ICmpZero &&
3575 !Base.HasBaseReg && Base.BaseOffset == 0 && !Base.BaseGV)
3576 continue;
3577 // For each addrec base reg, apply the scale, if possible.
3578 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3579 if (const SCEVAddRecExpr *AR =
3580 dyn_cast<SCEVAddRecExpr>(Base.BaseRegs[i])) {
3581 const SCEV *FactorS = SE.getConstant(IntTy, Factor);
3582 if (FactorS->isZero())
3583 continue;
3584 // Divide out the factor, ignoring high bits, since we'll be
3585 // scaling the value back up in the end.
3586 if (const SCEV *Quotient = getExactSDiv(AR, FactorS, SE, true)) {
3587 // TODO: This could be optimized to avoid all the copying.
3588 Formula F = Base;
3589 F.ScaledReg = Quotient;
3590 F.DeleteBaseReg(F.BaseRegs[i]);
3591 // The canonical representation of 1*reg is reg, which is already in
3592 // Base. In that case, do not try to insert the formula, it will be
3593 // rejected anyway.
3594 if (F.Scale == 1 && F.BaseRegs.empty())
3595 continue;
3596 (void)InsertFormula(LU, LUIdx, F);
3597 }
3598 }
3599 }
3600}
3601
3602/// GenerateTruncates - Generate reuse formulae from different IV types.
3603void LSRInstance::GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base) {
3604 // Don't bother truncating symbolic values.
3605 if (Base.BaseGV) return;
3606
3607 // Determine the integer type for the base formula.
3608 Type *DstTy = Base.getType();
3609 if (!DstTy) return;
3610 DstTy = SE.getEffectiveSCEVType(DstTy);
3611
3612 for (Type *SrcTy : Types) {
3613 if (SrcTy != DstTy && TTI.isTruncateFree(SrcTy, DstTy)) {
3614 Formula F = Base;
3615
3616 if (F.ScaledReg) F.ScaledReg = SE.getAnyExtendExpr(F.ScaledReg, SrcTy);
3617 for (const SCEV *&BaseReg : F.BaseRegs)
3618 BaseReg = SE.getAnyExtendExpr(BaseReg, SrcTy);
3619
3620 // TODO: This assumes we've done basic processing on all uses and
3621 // have an idea what the register usage is.
3622 if (!F.hasRegsUsedByUsesOtherThan(LUIdx, RegUses))
3623 continue;
3624
3625 (void)InsertFormula(LU, LUIdx, F);
3626 }
3627 }
3628}
3629
3630namespace {
3631
3632/// WorkItem - Helper class for GenerateCrossUseConstantOffsets. It's used to
3633/// defer modifications so that the search phase doesn't have to worry about
3634/// the data structures moving underneath it.
3635struct WorkItem {
3636 size_t LUIdx;
3637 int64_t Imm;
3638 const SCEV *OrigReg;
3639
3640 WorkItem(size_t LI, int64_t I, const SCEV *R)
3641 : LUIdx(LI), Imm(I), OrigReg(R) {}
3642
3643 void print(raw_ostream &OS) const;
3644 void dump() const;
3645};
3646
3647}
3648
3649void WorkItem::print(raw_ostream &OS) const {
3650 OS << "in formulae referencing " << *OrigReg << " in use " << LUIdx
3651 << " , add offset " << Imm;
3652}
3653
3654#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
3655void WorkItem::dump() const {
3656 print(errs()); errs() << '\n';
3657}
3658#endif
3659
3660/// GenerateCrossUseConstantOffsets - Look for registers which are a constant
3661/// distance apart and try to form reuse opportunities between them.
3662void LSRInstance::GenerateCrossUseConstantOffsets() {
3663 // Group the registers by their value without any added constant offset.
3664 typedef std::map<int64_t, const SCEV *> ImmMapTy;
3665 DenseMap<const SCEV *, ImmMapTy> Map;
3666 DenseMap<const SCEV *, SmallBitVector> UsedByIndicesMap;
3667 SmallVector<const SCEV *, 8> Sequence;
3668 for (const SCEV *Use : RegUses) {
3669 const SCEV *Reg = Use; // Make a copy for ExtractImmediate to modify.
3670 int64_t Imm = ExtractImmediate(Reg, SE);
3671 auto Pair = Map.insert(std::make_pair(Reg, ImmMapTy()));
3672 if (Pair.second)
3673 Sequence.push_back(Reg);
3674 Pair.first->second.insert(std::make_pair(Imm, Use));
3675 UsedByIndicesMap[Reg] |= RegUses.getUsedByIndices(Use);
3676 }
3677
3678 // Now examine each set of registers with the same base value. Build up
3679 // a list of work to do and do the work in a separate step so that we're
3680 // not adding formulae and register counts while we're searching.
3681 SmallVector<WorkItem, 32> WorkItems;
3682 SmallSet<std::pair<size_t, int64_t>, 32> UniqueItems;
3683 for (const SCEV *Reg : Sequence) {
3684 const ImmMapTy &Imms = Map.find(Reg)->second;
3685
3686 // It's not worthwhile looking for reuse if there's only one offset.
3687 if (Imms.size() == 1)
3688 continue;
3689
3690 DEBUG(dbgs() << "Generating cross-use offsets for " << *Reg << ':';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (0)
3691 for (const auto &Entry : Imms)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (0)
3692 dbgs() << ' ' << Entry.first;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (0)
3693 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (0)
;
3694
3695 // Examine each offset.
3696 for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end();
3697 J != JE; ++J) {
3698 const SCEV *OrigReg = J->second;
3699
3700 int64_t JImm = J->first;
3701 const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(OrigReg);
3702
3703 if (!isa<SCEVConstant>(OrigReg) &&
3704 UsedByIndicesMap[Reg].count() == 1) {
3705 DEBUG(dbgs() << "Skipping cross-use reuse for " << *OrigReg << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Skipping cross-use reuse for "
<< *OrigReg << '\n'; } } while (0)
;
3706 continue;
3707 }
3708
3709 // Conservatively examine offsets between this orig reg a few selected
3710 // other orig regs.
3711 ImmMapTy::const_iterator OtherImms[] = {
3712 Imms.begin(), std::prev(Imms.end()),
3713 Imms.lower_bound((Imms.begin()->first + std::prev(Imms.end())->first) /
3714 2)
3715 };
3716 for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) {
3717 ImmMapTy::const_iterator M = OtherImms[i];
3718 if (M == J || M == JE) continue;
3719
3720 // Compute the difference between the two.
3721 int64_t Imm = (uint64_t)JImm - M->first;
3722 for (int LUIdx = UsedByIndices.find_first(); LUIdx != -1;
3723 LUIdx = UsedByIndices.find_next(LUIdx))
3724 // Make a memo of this use, offset, and register tuple.
3725 if (UniqueItems.insert(std::make_pair(LUIdx, Imm)).second)
3726 WorkItems.push_back(WorkItem(LUIdx, Imm, OrigReg));
3727 }
3728 }
3729 }
3730
3731 Map.clear();
3732 Sequence.clear();
3733 UsedByIndicesMap.clear();
3734 UniqueItems.clear();
3735
3736 // Now iterate through the worklist and add new formulae.
3737 for (const WorkItem &WI : WorkItems) {
3738 size_t LUIdx = WI.LUIdx;
3739 LSRUse &LU = Uses[LUIdx];
3740 int64_t Imm = WI.Imm;
3741 const SCEV *OrigReg = WI.OrigReg;
3742
3743 Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType());
3744 const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, -(uint64_t)Imm));
3745 unsigned BitWidth = SE.getTypeSizeInBits(IntTy);
3746
3747 // TODO: Use a more targeted data structure.
3748 for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) {
3749 Formula F = LU.Formulae[L];
3750 // FIXME: The code for the scaled and unscaled registers looks
3751 // very similar but slightly different. Investigate if they
3752 // could be merged. That way, we would not have to unscale the
3753 // Formula.
3754 F.Unscale();
3755 // Use the immediate in the scaled register.
3756 if (F.ScaledReg == OrigReg) {
3757 int64_t Offset = (uint64_t)F.BaseOffset + Imm * (uint64_t)F.Scale;
3758 // Don't create 50 + reg(-50).
3759 if (F.referencesReg(SE.getSCEV(
3760 ConstantInt::get(IntTy, -(uint64_t)Offset))))
3761 continue;
3762 Formula NewF = F;
3763 NewF.BaseOffset = Offset;
3764 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,
3765 NewF))
3766 continue;
3767 NewF.ScaledReg = SE.getAddExpr(NegImmS, NewF.ScaledReg);
3768
3769 // If the new scale is a constant in a register, and adding the constant
3770 // value to the immediate would produce a value closer to zero than the
3771 // immediate itself, then the formula isn't worthwhile.
3772 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewF.ScaledReg))
3773 if (C->getValue()->isNegative() !=
3774 (NewF.BaseOffset < 0) &&
3775 (C->getValue()->getValue().abs() * APInt(BitWidth, F.Scale))
3776 .ule(std::abs(NewF.BaseOffset)))
3777 continue;
3778
3779 // OK, looks good.
3780 NewF.Canonicalize();
3781 (void)InsertFormula(LU, LUIdx, NewF);
3782 } else {
3783 // Use the immediate in a base register.
3784 for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) {
3785 const SCEV *BaseReg = F.BaseRegs[N];
3786 if (BaseReg != OrigReg)
3787 continue;
3788 Formula NewF = F;
3789 NewF.BaseOffset = (uint64_t)NewF.BaseOffset + Imm;
3790 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset,
3791 LU.Kind, LU.AccessTy, NewF)) {
3792 if (!TTI.isLegalAddImmediate((uint64_t)NewF.UnfoldedOffset + Imm))
3793 continue;
3794 NewF = F;
3795 NewF.UnfoldedOffset = (uint64_t)NewF.UnfoldedOffset + Imm;
3796 }
3797 NewF.BaseRegs[N] = SE.getAddExpr(NegImmS, BaseReg);
3798
3799 // If the new formula has a constant in a register, and adding the
3800 // constant value to the immediate would produce a value closer to
3801 // zero than the immediate itself, then the formula isn't worthwhile.
3802 for (const SCEV *NewReg : NewF.BaseRegs)
3803 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewReg))
3804 if ((C->getValue()->getValue() + NewF.BaseOffset).abs().slt(
3805 std::abs(NewF.BaseOffset)) &&
3806 (C->getValue()->getValue() +
3807 NewF.BaseOffset).countTrailingZeros() >=
3808 countTrailingZeros<uint64_t>(NewF.BaseOffset))
3809 goto skip_formula;
3810
3811 // Ok, looks good.
3812 NewF.Canonicalize();
3813 (void)InsertFormula(LU, LUIdx, NewF);
3814 break;
3815 skip_formula:;
3816 }
3817 }
3818 }
3819 }
3820}
3821
3822/// GenerateAllReuseFormulae - Generate formulae for each use.
3823void
3824LSRInstance::GenerateAllReuseFormulae() {
3825 // This is split into multiple loops so that hasRegsUsedByUsesOtherThan
3826 // queries are more precise.
3827 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
3828 LSRUse &LU = Uses[LUIdx];
3829 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
3830 GenerateReassociations(LU, LUIdx, LU.Formulae[i]);
3831 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
3832 GenerateCombinations(LU, LUIdx, LU.Formulae[i]);
3833 }
3834 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
3835 LSRUse &LU = Uses[LUIdx];
3836 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
3837 GenerateSymbolicOffsets(LU, LUIdx, LU.Formulae[i]);
3838 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
3839 GenerateConstantOffsets(LU, LUIdx, LU.Formulae[i]);
3840 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
3841 GenerateICmpZeroScales(LU, LUIdx, LU.Formulae[i]);
3842 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
3843 GenerateScales(LU, LUIdx, LU.Formulae[i]);
3844 }
3845 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
3846 LSRUse &LU = Uses[LUIdx];
3847 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
3848 GenerateTruncates(LU, LUIdx, LU.Formulae[i]);
3849 }
3850
3851 GenerateCrossUseConstantOffsets();
3852
3853 DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (0)
3854 "After generating reuse formulae:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (0)
3855 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (0)
;
3856}
3857
3858/// If there are multiple formulae with the same set of registers used
3859/// by other uses, pick the best one and delete the others.
3860void LSRInstance::FilterOutUndesirableDedicatedRegisters() {
3861 DenseSet<const SCEV *> VisitedRegs;
3862 SmallPtrSet<const SCEV *, 16> Regs;
3863 SmallPtrSet<const SCEV *, 16> LoserRegs;
3864#ifndef NDEBUG
3865 bool ChangedFormulae = false;
3866#endif
3867
3868 // Collect the best formula for each unique set of shared registers. This
3869 // is reset for each use.
3870 typedef DenseMap<SmallVector<const SCEV *, 4>, size_t, UniquifierDenseMapInfo>
3871 BestFormulaeTy;
3872 BestFormulaeTy BestFormulae;
3873
3874 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
3875 LSRUse &LU = Uses[LUIdx];
3876 DEBUG(dbgs() << "Filtering for use "; LU.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Filtering for use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (0)
;
3877
3878 bool Any = false;
3879 for (size_t FIdx = 0, NumForms = LU.Formulae.size();
3880 FIdx != NumForms; ++FIdx) {
3881 Formula &F = LU.Formulae[FIdx];
3882
3883 // Some formulas are instant losers. For example, they may depend on
3884 // nonexistent AddRecs from other loops. These need to be filtered
3885 // immediately, otherwise heuristics could choose them over others leading
3886 // to an unsatisfactory solution. Passing LoserRegs into RateFormula here
3887 // avoids the need to recompute this information across formulae using the
3888 // same bad AddRec. Passing LoserRegs is also essential unless we remove
3889 // the corresponding bad register from the Regs set.
3890 Cost CostF;
3891 Regs.clear();
3892 CostF.RateFormula(TTI, F, Regs, VisitedRegs, L, LU.Offsets, SE, DT, LU,
3893 &LoserRegs);
3894 if (CostF.isLoser()) {
3895 // During initial formula generation, undesirable formulae are generated
3896 // by uses within other loops that have some non-trivial address mode or
3897 // use the postinc form of the IV. LSR needs to provide these formulae
3898 // as the basis of rediscovering the desired formula that uses an AddRec
3899 // corresponding to the existing phi. Once all formulae have been
3900 // generated, these initial losers may be pruned.
3901 DEBUG(dbgs() << " Filtering loser "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering loser "; F.print
(dbgs()); dbgs() << "\n"; } } while (0)
3902 dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering loser "; F.print
(dbgs()); dbgs() << "\n"; } } while (0)
;
3903 }
3904 else {
3905 SmallVector<const SCEV *, 4> Key;
3906 for (const SCEV *Reg : F.BaseRegs) {
3907 if (RegUses.isRegUsedByUsesOtherThan(Reg, LUIdx))
3908 Key.push_back(Reg);
3909 }
3910 if (F.ScaledReg &&
3911 RegUses.isRegUsedByUsesOtherThan(F.ScaledReg, LUIdx))
3912 Key.push_back(F.ScaledReg);
3913 // Unstable sort by host order ok, because this is only used for
3914 // uniquifying.
3915 std::sort(Key.begin(), Key.end());
3916
3917 std::pair<BestFormulaeTy::const_iterator, bool> P =
3918 BestFormulae.insert(std::make_pair(Key, FIdx));
3919 if (P.second)
3920 continue;
3921
3922 Formula &Best = LU.Formulae[P.first->second];
3923
3924 Cost CostBest;
3925 Regs.clear();
3926 CostBest.RateFormula(TTI, Best, Regs, VisitedRegs, L, LU.Offsets, SE,
3927 DT, LU);
3928 if (CostF < CostBest)
3929 std::swap(F, Best);
3930 DEBUG(dbgs() << " Filtering out formula "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (0)
3931 dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (0)
3932 " in favor of formula "; Best.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (0)
3933 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (0)
;
3934 }
3935#ifndef NDEBUG
3936 ChangedFormulae = true;
3937#endif
3938 LU.DeleteFormula(F);
3939 --FIdx;
3940 --NumForms;
3941 Any = true;
3942 }
3943
3944 // Now that we've filtered out some formulae, recompute the Regs set.
3945 if (Any)
3946 LU.RecomputeRegs(LUIdx, RegUses);
3947
3948 // Reset this to prepare for the next use.
3949 BestFormulae.clear();
3950 }
3951
3952 DEBUG(if (ChangedFormulae) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (0)
3953 dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (0)
3954 "After filtering out undesirable candidates:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (0)
3955 print_uses(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (0)
3956 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (0)
;
3957}
3958
3959// This is a rough guess that seems to work fairly well.
3960static const size_t ComplexityLimit = UINT16_MAX(65535);
3961
3962/// EstimateSearchSpaceComplexity - Estimate the worst-case number of
3963/// solutions the solver might have to consider. It almost never considers
3964/// this many solutions because it prune the search space, but the pruning
3965/// isn't always sufficient.
3966size_t LSRInstance::EstimateSearchSpaceComplexity() const {
3967 size_t Power = 1;
3968 for (const LSRUse &LU : Uses) {
3969 size_t FSize = LU.Formulae.size();
3970 if (FSize >= ComplexityLimit) {
3971 Power = ComplexityLimit;
3972 break;
3973 }
3974 Power *= FSize;
3975 if (Power >= ComplexityLimit)
3976 break;
3977 }
3978 return Power;
3979}
3980
3981/// NarrowSearchSpaceByDetectingSupersets - When one formula uses a superset
3982/// of the registers of another formula, it won't help reduce register
3983/// pressure (though it may not necessarily hurt register pressure); remove
3984/// it to simplify the system.
3985void LSRInstance::NarrowSearchSpaceByDetectingSupersets() {
3986 if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
3987 DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
; } } while (0)
;
3988
3989 DEBUG(dbgs() << "Narrowing the search space by eliminating formulae "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae "
"which use a superset of registers used by other " "formulae.\n"
; } } while (0)
3990 "which use a superset of registers used by other "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae "
"which use a superset of registers used by other " "formulae.\n"
; } } while (0)
3991 "formulae.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae "
"which use a superset of registers used by other " "formulae.\n"
; } } while (0)
;
3992
3993 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
3994 LSRUse &LU = Uses[LUIdx];
3995 bool Any = false;
3996 for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {
3997 Formula &F = LU.Formulae[i];
3998 // Look for a formula with a constant or GV in a register. If the use
3999 // also has a formula with that same value in an immediate field,
4000 // delete the one that uses a register.
4001 for (SmallVectorImpl<const SCEV *>::const_iterator
4002 I = F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) {
4003 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*I)) {
4004 Formula NewF = F;
4005 NewF.BaseOffset += C->getValue()->getSExtValue();
4006 NewF.BaseRegs.erase(NewF.BaseRegs.begin() +
4007 (I - F.BaseRegs.begin()));
4008 if (LU.HasFormulaWithSameRegs(NewF)) {
4009 DEBUG(dbgs() << " Deleting "; F.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)
;
4010 LU.DeleteFormula(F);
4011 --i;
4012 --e;
4013 Any = true;
4014 break;
4015 }
4016 } else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(*I)) {
4017 if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue()))
4018 if (!F.BaseGV) {
4019 Formula NewF = F;
4020 NewF.BaseGV = GV;
4021 NewF.BaseRegs.erase(NewF.BaseRegs.begin() +
4022 (I - F.BaseRegs.begin()));
4023 if (LU.HasFormulaWithSameRegs(NewF)) {
4024 DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)
4025 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)
;
4026 LU.DeleteFormula(F);
4027 --i;
4028 --e;
4029 Any = true;
4030 break;
4031 }
4032 }
4033 }
4034 }
4035 }
4036 if (Any)
4037 LU.RecomputeRegs(LUIdx, RegUses);
4038 }
4039
4040 DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)
4041 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)
;
4042 }
4043}
4044
4045/// NarrowSearchSpaceByCollapsingUnrolledCode - When there are many registers
4046/// for expressions like A, A+1, A+2, etc., allocate a single register for
4047/// them.
4048void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() {
4049 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4050 return;
4051
4052 DEBUG(dbgs() << "The search space is too complex.\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by assuming that uses separated "
"by a constant offset will use the same registers.\n"; } } while
(0)
4053 "Narrowing the search space by assuming that uses separated "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by assuming that uses separated "
"by a constant offset will use the same registers.\n"; } } while
(0)
4054 "by a constant offset will use the same registers.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by assuming that uses separated "
"by a constant offset will use the same registers.\n"; } } while
(0)
;
4055
4056 // This is especially useful for unrolled loops.
4057
4058 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4059 LSRUse &LU = Uses[LUIdx];
4060 for (const Formula &F : LU.Formulae) {
4061 if (F.BaseOffset == 0 || (F.Scale != 0 && F.Scale != 1))
4062 continue;
4063
4064 LSRUse *LUThatHas = FindUseWithSimilarFormula(F, LU);
4065 if (!LUThatHas)
4066 continue;
4067
4068 if (!reconcileNewOffset(*LUThatHas, F.BaseOffset, /*HasBaseReg=*/ false,
4069 LU.Kind, LU.AccessTy))
4070 continue;
4071
4072 DEBUG(dbgs() << " Deleting use "; LU.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (0)
;
4073
4074 LUThatHas->AllFixupsOutsideLoop &= LU.AllFixupsOutsideLoop;
4075
4076 // Update the relocs to reference the new use.
4077 for (LSRFixup &Fixup : Fixups) {
4078 if (Fixup.LUIdx == LUIdx) {
4079 Fixup.LUIdx = LUThatHas - &Uses.front();
4080 Fixup.Offset += F.BaseOffset;
4081 // Add the new offset to LUThatHas' offset list.
4082 if (LUThatHas->Offsets.back() != Fixup.Offset) {
4083 LUThatHas->Offsets.push_back(Fixup.Offset);
4084 if (Fixup.Offset > LUThatHas->MaxOffset)
4085 LUThatHas->MaxOffset = Fixup.Offset;
4086 if (Fixup.Offset < LUThatHas->MinOffset)
4087 LUThatHas->MinOffset = Fixup.Offset;
4088 }
4089 DEBUG(dbgs() << "New fixup has offset " << Fixup.Offset << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New fixup has offset " <<
Fixup.Offset << '\n'; } } while (0)
;
4090 }
4091 if (Fixup.LUIdx == NumUses-1)
4092 Fixup.LUIdx = LUIdx;
4093 }
4094
4095 // Delete formulae from the new use which are no longer legal.
4096 bool Any = false;
4097 for (size_t i = 0, e = LUThatHas->Formulae.size(); i != e; ++i) {
4098 Formula &F = LUThatHas->Formulae[i];
4099 if (!isLegalUse(TTI, LUThatHas->MinOffset, LUThatHas->MaxOffset,
4100 LUThatHas->Kind, LUThatHas->AccessTy, F)) {
4101 DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)
4102 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)
;
4103 LUThatHas->DeleteFormula(F);
4104 --i;
4105 --e;
4106 Any = true;
4107 }
4108 }
4109
4110 if (Any)
4111 LUThatHas->RecomputeRegs(LUThatHas - &Uses.front(), RegUses);
4112
4113 // Delete the old use.
4114 DeleteUse(LU, LUIdx);
4115 --LUIdx;
4116 --NumUses;
4117 break;
4118 }
4119 }
4120
4121 DEBUG(dbgs() << "After pre-selection:\n"; print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)
;
4122}
4123
4124/// NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters - Call
4125/// FilterOutUndesirableDedicatedRegisters again, if necessary, now that
4126/// we've done more filtering, as it may be able to find more formulae to
4127/// eliminate.
4128void LSRInstance::NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(){
4129 if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
4130 DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
; } } while (0)
;
4131
4132 DEBUG(dbgs() << "Narrowing the search space by re-filtering out "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by re-filtering out "
"undesirable dedicated registers.\n"; } } while (0)
4133 "undesirable dedicated registers.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by re-filtering out "
"undesirable dedicated registers.\n"; } } while (0)
;
4134
4135 FilterOutUndesirableDedicatedRegisters();
4136
4137 DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)
4138 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)
;
4139 }
4140}
4141
4142/// NarrowSearchSpaceByPickingWinnerRegs - Pick a register which seems likely
4143/// to be profitable, and then in any use which has any reference to that
4144/// register, delete all formulae which do not reference that register.
4145void LSRInstance::NarrowSearchSpaceByPickingWinnerRegs() {
4146 // With all other options exhausted, loop until the system is simple
4147 // enough to handle.
4148 SmallPtrSet<const SCEV *, 4> Taken;
4149 while (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
4150 // Ok, we have too many of formulae on our hands to conveniently handle.
4151 // Use a rough heuristic to thin out the list.
4152 DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
; } } while (0)
;
4153
4154 // Pick the register which is used by the most LSRUses, which is likely
4155 // to be a good reuse register candidate.
4156 const SCEV *Best = nullptr;
4157 unsigned BestNum = 0;
4158 for (const SCEV *Reg : RegUses) {
4159 if (Taken.count(Reg))
4160 continue;
4161 if (!Best)
4162 Best = Reg;
4163 else {
4164 unsigned Count = RegUses.getUsedByIndices(Reg).count();
4165 if (Count > BestNum) {
4166 Best = Reg;
4167 BestNum = Count;
4168 }
4169 }
4170 }
4171
4172 DEBUG(dbgs() << "Narrowing the search space by assuming " << *Bestdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by assuming "
<< *Best << " will yield profitable reuse.\n"; }
} while (0)
4173 << " will yield profitable reuse.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by assuming "
<< *Best << " will yield profitable reuse.\n"; }
} while (0)
;
4174 Taken.insert(Best);
4175
4176 // In any use with formulae which references this register, delete formulae
4177 // which don't reference it.
4178 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4179 LSRUse &LU = Uses[LUIdx];
4180 if (!LU.Regs.count(Best)) continue;
4181
4182 bool Any = false;
4183 for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {
4184 Formula &F = LU.Formulae[i];
4185 if (!F.referencesReg(Best)) {
4186 DEBUG(dbgs() << " Deleting "; F.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)
;
4187 LU.DeleteFormula(F);
4188 --e;
4189 --i;
4190 Any = true;
4191 assert(e != 0 && "Use has no formulae left! Is Regs inconsistent?")((e != 0 && "Use has no formulae left! Is Regs inconsistent?"
) ? static_cast<void> (0) : __assert_fail ("e != 0 && \"Use has no formulae left! Is Regs inconsistent?\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4191, __PRETTY_FUNCTION__))
;
4192 continue;
4193 }
4194 }
4195
4196 if (Any)
4197 LU.RecomputeRegs(LUIdx, RegUses);
4198 }
4199
4200 DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)
4201 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)
;
4202 }
4203}
4204
4205/// NarrowSearchSpaceUsingHeuristics - If there are an extraordinary number of
4206/// formulae to choose from, use some rough heuristics to prune down the number
4207/// of formulae. This keeps the main solver from taking an extraordinary amount
4208/// of time in some worst-case scenarios.
4209void LSRInstance::NarrowSearchSpaceUsingHeuristics() {
4210 NarrowSearchSpaceByDetectingSupersets();
4211 NarrowSearchSpaceByCollapsingUnrolledCode();
4212 NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();
4213 NarrowSearchSpaceByPickingWinnerRegs();
4214}
4215
4216/// SolveRecurse - This is the recursive solver.
4217void LSRInstance::SolveRecurse(SmallVectorImpl<const Formula *> &Solution,
4218 Cost &SolutionCost,
4219 SmallVectorImpl<const Formula *> &Workspace,
4220 const Cost &CurCost,
4221 const SmallPtrSet<const SCEV *, 16> &CurRegs,
4222 DenseSet<const SCEV *> &VisitedRegs) const {
4223 // Some ideas:
4224 // - prune more:
4225 // - use more aggressive filtering
4226 // - sort the formula so that the most profitable solutions are found first
4227 // - sort the uses too
4228 // - search faster:
4229 // - don't compute a cost, and then compare. compare while computing a cost
4230 // and bail early.
4231 // - track register sets with SmallBitVector
4232
4233 const LSRUse &LU = Uses[Workspace.size()];
4234
4235 // If this use references any register that's already a part of the
4236 // in-progress solution, consider it a requirement that a formula must
4237 // reference that register in order to be considered. This prunes out
4238 // unprofitable searching.
4239 SmallSetVector<const SCEV *, 4> ReqRegs;
4240 for (const SCEV *S : CurRegs)
4241 if (LU.Regs.count(S))
4242 ReqRegs.insert(S);
4243
4244 SmallPtrSet<const SCEV *, 16> NewRegs;
4245 Cost NewCost;
4246 for (const Formula &F : LU.Formulae) {
4247 // Ignore formulae which may not be ideal in terms of register reuse of
4248 // ReqRegs. The formula should use all required registers before
4249 // introducing new ones.
4250 int NumReqRegsToFind = std::min(F.getNumRegs(), ReqRegs.size());
4251 for (const SCEV *Reg : ReqRegs) {
4252 if ((F.ScaledReg && F.ScaledReg == Reg) ||
4253 std::find(F.BaseRegs.begin(), F.BaseRegs.end(), Reg) !=
4254 F.BaseRegs.end()) {
4255 --NumReqRegsToFind;
4256 if (NumReqRegsToFind == 0)
4257 break;
4258 }
4259 }
4260 if (NumReqRegsToFind != 0) {
4261 // If none of the formulae satisfied the required registers, then we could
4262 // clear ReqRegs and try again. Currently, we simply give up in this case.
4263 continue;
4264 }
4265
4266 // Evaluate the cost of the current formula. If it's already worse than
4267 // the current best, prune the search at that point.
4268 NewCost = CurCost;
4269 NewRegs = CurRegs;
4270 NewCost.RateFormula(TTI, F, NewRegs, VisitedRegs, L, LU.Offsets, SE, DT,
4271 LU);
4272 if (NewCost < SolutionCost) {
4273 Workspace.push_back(&F);
4274 if (Workspace.size() != Uses.size()) {
4275 SolveRecurse(Solution, SolutionCost, Workspace, NewCost,
4276 NewRegs, VisitedRegs);
4277 if (F.getNumRegs() == 1 && Workspace.size() == 1)
4278 VisitedRegs.insert(F.ScaledReg ? F.ScaledReg : F.BaseRegs[0]);
4279 } else {
4280 DEBUG(dbgs() << "New best at "; NewCost.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs
) dbgs() << ' ' << *S; dbgs() << '\n'; } } while
(0)
4281 dbgs() << ".\n Regs:";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs
) dbgs() << ' ' << *S; dbgs() << '\n'; } } while
(0)
4282 for (const SCEV *S : NewRegs)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs
) dbgs() << ' ' << *S; dbgs() << '\n'; } } while
(0)
4283 dbgs() << ' ' << *S;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs
) dbgs() << ' ' << *S; dbgs() << '\n'; } } while
(0)
4284 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\n Regs:"; for (const SCEV *S : NewRegs
) dbgs() << ' ' << *S; dbgs() << '\n'; } } while
(0)
;
4285
4286 SolutionCost = NewCost;
4287 Solution = Workspace;
4288 }
4289 Workspace.pop_back();
4290 }
4291 }
4292}
4293
4294/// Solve - Choose one formula from each use. Return the results in the given
4295/// Solution vector.
4296void LSRInstance::Solve(SmallVectorImpl<const Formula *> &Solution) const {
4297 SmallVector<const Formula *, 8> Workspace;
4298 Cost SolutionCost;
4299 SolutionCost.Lose();
4300 Cost CurCost;
4301 SmallPtrSet<const SCEV *, 16> CurRegs;
4302 DenseSet<const SCEV *> VisitedRegs;
4303 Workspace.reserve(Uses.size());
4304
4305 // SolveRecurse does all the work.
4306 SolveRecurse(Solution, SolutionCost, Workspace, CurCost,
4307 CurRegs, VisitedRegs);
4308 if (Solution.empty()) {
4309 DEBUG(dbgs() << "\nNo Satisfactory Solution\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nNo Satisfactory Solution\n"
; } } while (0)
;
4310 return;
4311 }
4312
4313 // Ok, we've now made all our decisions.
4314 DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4315 "The chosen solution requires "; SolutionCost.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4316 dbgs() << ":\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4317 for (size_t i = 0, e = Uses.size(); i != e; ++i) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4318 dbgs() << " ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4319 Uses[i].print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4320 dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4321 " ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4322 Solution[i]->print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4323 dbgs() << '\n';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
4324 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (0)
;
4325
4326 assert(Solution.size() == Uses.size() && "Malformed solution!")((Solution.size() == Uses.size() && "Malformed solution!"
) ? static_cast<void> (0) : __assert_fail ("Solution.size() == Uses.size() && \"Malformed solution!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4326, __PRETTY_FUNCTION__))
;
4327}
4328
4329/// HoistInsertPosition - Helper for AdjustInsertPositionForExpand. Climb up
4330/// the dominator tree far as we can go while still being dominated by the
4331/// input positions. This helps canonicalize the insert position, which
4332/// encourages sharing.
4333BasicBlock::iterator
4334LSRInstance::HoistInsertPosition(BasicBlock::iterator IP,
4335 const SmallVectorImpl<Instruction *> &Inputs)
4336 const {
4337 for (;;) {
4338 const Loop *IPLoop = LI.getLoopFor(IP->getParent());
4339 unsigned IPLoopDepth = IPLoop ? IPLoop->getLoopDepth() : 0;
4340
4341 BasicBlock *IDom;
4342 for (DomTreeNode *Rung = DT.getNode(IP->getParent()); ; ) {
4343 if (!Rung) return IP;
4344 Rung = Rung->getIDom();
4345 if (!Rung) return IP;
4346 IDom = Rung->getBlock();
4347
4348 // Don't climb into a loop though.
4349 const Loop *IDomLoop = LI.getLoopFor(IDom);
4350 unsigned IDomDepth = IDomLoop ? IDomLoop->getLoopDepth() : 0;
4351 if (IDomDepth <= IPLoopDepth &&
4352 (IDomDepth != IPLoopDepth || IDomLoop == IPLoop))
4353 break;
4354 }
4355
4356 bool AllDominate = true;
4357 Instruction *BetterPos = nullptr;
4358 Instruction *Tentative = IDom->getTerminator();
4359 for (Instruction *Inst : Inputs) {
4360 if (Inst == Tentative || !DT.dominates(Inst, Tentative)) {
4361 AllDominate = false;
4362 break;
4363 }
4364 // Attempt to find an insert position in the middle of the block,
4365 // instead of at the end, so that it can be used for other expansions.
4366 if (IDom == Inst->getParent() &&
4367 (!BetterPos || !DT.dominates(Inst, BetterPos)))
4368 BetterPos = std::next(BasicBlock::iterator(Inst));
4369 }
4370 if (!AllDominate)
4371 break;
4372 if (BetterPos)
4373 IP = BetterPos;
4374 else
4375 IP = Tentative;
4376 }
4377
4378 return IP;
4379}
4380
4381/// AdjustInsertPositionForExpand - Determine an input position which will be
4382/// dominated by the operands and which will dominate the result.
4383BasicBlock::iterator
4384LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP,
4385 const LSRFixup &LF,
4386 const LSRUse &LU,
4387 SCEVExpander &Rewriter) const {
4388 // Collect some instructions which must be dominated by the
4389 // expanding replacement. These must be dominated by any operands that
4390 // will be required in the expansion.
4391 SmallVector<Instruction *, 4> Inputs;
4392 if (Instruction *I = dyn_cast<Instruction>(LF.OperandValToReplace))
4393 Inputs.push_back(I);
4394 if (LU.Kind == LSRUse::ICmpZero)
4395 if (Instruction *I =
4396 dyn_cast<Instruction>(cast<ICmpInst>(LF.UserInst)->getOperand(1)))
4397 Inputs.push_back(I);
4398 if (LF.PostIncLoops.count(L)) {
4399 if (LF.isUseFullyOutsideLoop(L))
4400 Inputs.push_back(L->getLoopLatch()->getTerminator());
4401 else
4402 Inputs.push_back(IVIncInsertPos);
4403 }
4404 // The expansion must also be dominated by the increment positions of any
4405 // loops it for which it is using post-inc mode.
4406 for (const Loop *PIL : LF.PostIncLoops) {
4407 if (PIL == L) continue;
4408
4409 // Be dominated by the loop exit.
4410 SmallVector<BasicBlock *, 4> ExitingBlocks;
4411 PIL->getExitingBlocks(ExitingBlocks);
4412 if (!ExitingBlocks.empty()) {
4413 BasicBlock *BB = ExitingBlocks[0];
4414 for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i)
4415 BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]);
4416 Inputs.push_back(BB->getTerminator());
4417 }
4418 }
4419
4420 assert(!isa<PHINode>(LowestIP) && !isa<LandingPadInst>(LowestIP)((!isa<PHINode>(LowestIP) && !isa<LandingPadInst
>(LowestIP) && !isa<DbgInfoIntrinsic>(LowestIP
) && "Insertion point must be a normal instruction") ?
static_cast<void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !isa<LandingPadInst>(LowestIP) && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4422, __PRETTY_FUNCTION__))
4421 && !isa<DbgInfoIntrinsic>(LowestIP) &&((!isa<PHINode>(LowestIP) && !isa<LandingPadInst
>(LowestIP) && !isa<DbgInfoIntrinsic>(LowestIP
) && "Insertion point must be a normal instruction") ?
static_cast<void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !isa<LandingPadInst>(LowestIP) && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4422, __PRETTY_FUNCTION__))
4422 "Insertion point must be a normal instruction")((!isa<PHINode>(LowestIP) && !isa<LandingPadInst
>(LowestIP) && !isa<DbgInfoIntrinsic>(LowestIP
) && "Insertion point must be a normal instruction") ?
static_cast<void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !isa<LandingPadInst>(LowestIP) && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4422, __PRETTY_FUNCTION__))
;
4423
4424 // Then, climb up the immediate dominator tree as far as we can go while
4425 // still being dominated by the input positions.
4426 BasicBlock::iterator IP = HoistInsertPosition(LowestIP, Inputs);
4427
4428 // Don't insert instructions before PHI nodes.
4429 while (isa<PHINode>(IP)) ++IP;
4430
4431 // Ignore landingpad instructions.
4432 while (isa<LandingPadInst>(IP)) ++IP;
4433
4434 // Ignore debug intrinsics.
4435 while (isa<DbgInfoIntrinsic>(IP)) ++IP;
4436
4437 // Set IP below instructions recently inserted by SCEVExpander. This keeps the
4438 // IP consistent across expansions and allows the previously inserted
4439 // instructions to be reused by subsequent expansion.
4440 while (Rewriter.isInsertedInstruction(IP) && IP != LowestIP) ++IP;
4441
4442 return IP;
4443}
4444
4445/// Expand - Emit instructions for the leading candidate expression for this
4446/// LSRUse (this is called "expanding").
4447Value *LSRInstance::Expand(const LSRFixup &LF,
4448 const Formula &F,
4449 BasicBlock::iterator IP,
4450 SCEVExpander &Rewriter,
4451 SmallVectorImpl<WeakVH> &DeadInsts) const {
4452 const LSRUse &LU = Uses[LF.LUIdx];
4453 if (LU.RigidFormula)
4454 return LF.OperandValToReplace;
4455
4456 // Determine an input position which will be dominated by the operands and
4457 // which will dominate the result.
4458 IP = AdjustInsertPositionForExpand(IP, LF, LU, Rewriter);
4459
4460 // Inform the Rewriter if we have a post-increment use, so that it can
4461 // perform an advantageous expansion.
4462 Rewriter.setPostInc(LF.PostIncLoops);
4463
4464 // This is the type that the user actually needs.
4465 Type *OpTy = LF.OperandValToReplace->getType();
4466 // This will be the type that we'll initially expand to.
4467 Type *Ty = F.getType();
4468 if (!Ty)
4469 // No type known; just expand directly to the ultimate type.
4470 Ty = OpTy;
4471 else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy))
4472 // Expand directly to the ultimate type if it's the right size.
4473 Ty = OpTy;
4474 // This is the type to do integer arithmetic in.
4475 Type *IntTy = SE.getEffectiveSCEVType(Ty);
4476
4477 // Build up a list of operands to add together to form the full base.
4478 SmallVector<const SCEV *, 8> Ops;
4479
4480 // Expand the BaseRegs portion.
4481 for (const SCEV *Reg : F.BaseRegs) {
4482 assert(!Reg->isZero() && "Zero allocated in a base register!")((!Reg->isZero() && "Zero allocated in a base register!"
) ? static_cast<void> (0) : __assert_fail ("!Reg->isZero() && \"Zero allocated in a base register!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4482, __PRETTY_FUNCTION__))
;
4483
4484 // If we're expanding for a post-inc user, make the post-inc adjustment.
4485 PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);
4486 Reg = TransformForPostIncUse(Denormalize, Reg,
4487 LF.UserInst, LF.OperandValToReplace,
4488 Loops, SE, DT);
4489
4490 Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr, IP)));
4491 }
4492
4493 // Expand the ScaledReg portion.
4494 Value *ICmpScaledV = nullptr;
4495 if (F.Scale != 0) {
4496 const SCEV *ScaledS = F.ScaledReg;
4497
4498 // If we're expanding for a post-inc user, make the post-inc adjustment.
4499 PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);
4500 ScaledS = TransformForPostIncUse(Denormalize, ScaledS,
4501 LF.UserInst, LF.OperandValToReplace,
4502 Loops, SE, DT);
4503
4504 if (LU.Kind == LSRUse::ICmpZero) {
4505 // Expand ScaleReg as if it was part of the base regs.
4506 if (F.Scale == 1)
4507 Ops.push_back(
4508 SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP)));
4509 else {
4510 // An interesting way of "folding" with an icmp is to use a negated
4511 // scale, which we'll implement by inserting it into the other operand
4512 // of the icmp.
4513 assert(F.Scale == -1 &&((F.Scale == -1 && "The only scale supported by ICmpZero uses is -1!"
) ? static_cast<void> (0) : __assert_fail ("F.Scale == -1 && \"The only scale supported by ICmpZero uses is -1!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4514, __PRETTY_FUNCTION__))
4514 "The only scale supported by ICmpZero uses is -1!")((F.Scale == -1 && "The only scale supported by ICmpZero uses is -1!"
) ? static_cast<void> (0) : __assert_fail ("F.Scale == -1 && \"The only scale supported by ICmpZero uses is -1!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4514, __PRETTY_FUNCTION__))
;
4515 ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr, IP);
4516 }
4517 } else {
4518 // Otherwise just expand the scaled register and an explicit scale,
4519 // which is expected to be matched as part of the address.
4520
4521 // Flush the operand list to suppress SCEVExpander hoisting address modes.
4522 // Unless the addressing mode will not be folded.
4523 if (!Ops.empty() && LU.Kind == LSRUse::Address &&
4524 isAMCompletelyFolded(TTI, LU, F)) {
4525 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);
4526 Ops.clear();
4527 Ops.push_back(SE.getUnknown(FullV));
4528 }
4529 ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP));
4530 if (F.Scale != 1)
4531 ScaledS =
4532 SE.getMulExpr(ScaledS, SE.getConstant(ScaledS->getType(), F.Scale));
4533 Ops.push_back(ScaledS);
4534 }
4535 }
4536
4537 // Expand the GV portion.
4538 if (F.BaseGV) {
4539 // Flush the operand list to suppress SCEVExpander hoisting.
4540 if (!Ops.empty()) {
4541 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);
4542 Ops.clear();
4543 Ops.push_back(SE.getUnknown(FullV));
4544 }
4545 Ops.push_back(SE.getUnknown(F.BaseGV));
4546 }
4547
4548 // Flush the operand list to suppress SCEVExpander hoisting of both folded and
4549 // unfolded offsets. LSR assumes they both live next to their uses.
4550 if (!Ops.empty()) {
4551 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);
4552 Ops.clear();
4553 Ops.push_back(SE.getUnknown(FullV));
4554 }
4555
4556 // Expand the immediate portion.
4557 int64_t Offset = (uint64_t)F.BaseOffset + LF.Offset;
4558 if (Offset != 0) {
4559 if (LU.Kind == LSRUse::ICmpZero) {
4560 // The other interesting way of "folding" with an ICmpZero is to use a
4561 // negated immediate.
4562 if (!ICmpScaledV)
4563 ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset);
4564 else {
4565 Ops.push_back(SE.getUnknown(ICmpScaledV));
4566 ICmpScaledV = ConstantInt::get(IntTy, Offset);
4567 }
4568 } else {
4569 // Just add the immediate values. These again are expected to be matched
4570 // as part of the address.
4571 Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, Offset)));
4572 }
4573 }
4574
4575 // Expand the unfolded offset portion.
4576 int64_t UnfoldedOffset = F.UnfoldedOffset;
4577 if (UnfoldedOffset != 0) {
4578 // Just add the immediate values.
4579 Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy,
4580 UnfoldedOffset)));
4581 }
4582
4583 // Emit instructions summing all the operands.
4584 const SCEV *FullS = Ops.empty() ?
4585 SE.getConstant(IntTy, 0) :
4586 SE.getAddExpr(Ops);
4587 Value *FullV = Rewriter.expandCodeFor(FullS, Ty, IP);
4588
4589 // We're done expanding now, so reset the rewriter.
4590 Rewriter.clearPostInc();
4591
4592 // An ICmpZero Formula represents an ICmp which we're handling as a
4593 // comparison against zero. Now that we've expanded an expression for that
4594 // form, update the ICmp's other operand.
4595 if (LU.Kind == LSRUse::ICmpZero) {
4596 ICmpInst *CI = cast<ICmpInst>(LF.UserInst);
4597 DeadInsts.emplace_back(CI->getOperand(1));
4598 assert(!F.BaseGV && "ICmp does not support folding a global value and "((!F.BaseGV && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("!F.BaseGV && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4599, __PRETTY_FUNCTION__))
4599 "a scale at the same time!")((!F.BaseGV && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("!F.BaseGV && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4599, __PRETTY_FUNCTION__))
;
4600 if (F.Scale == -1) {
4601 if (ICmpScaledV->getType() != OpTy) {
4602 Instruction *Cast =
4603 CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false,
4604 OpTy, false),
4605 ICmpScaledV, OpTy, "tmp", CI);
4606 ICmpScaledV = Cast;
4607 }
4608 CI->setOperand(1, ICmpScaledV);
4609 } else {
4610 // A scale of 1 means that the scale has been expanded as part of the
4611 // base regs.
4612 assert((F.Scale == 0 || F.Scale == 1) &&(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4614, __PRETTY_FUNCTION__))
4613 "ICmp does not support folding a global value and "(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4614, __PRETTY_FUNCTION__))
4614 "a scale at the same time!")(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4614, __PRETTY_FUNCTION__))
;
4615 Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy),
4616 -(uint64_t)Offset);
4617 if (C->getType() != OpTy)
4618 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
4619 OpTy, false),
4620 C, OpTy);
4621
4622 CI->setOperand(1, C);
4623 }
4624 }
4625
4626 return FullV;
4627}
4628
4629/// RewriteForPHI - Helper for Rewrite. PHI nodes are special because the use
4630/// of their operands effectively happens in their predecessor blocks, so the
4631/// expression may need to be expanded in multiple places.
4632void LSRInstance::RewriteForPHI(PHINode *PN,
4633 const LSRFixup &LF,
4634 const Formula &F,
4635 SCEVExpander &Rewriter,
4636 SmallVectorImpl<WeakVH> &DeadInsts,
4637 Pass *P) const {
4638 DenseMap<BasicBlock *, Value *> Inserted;
4639 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
1
Assuming 'i' is not equal to 'e'
2
Loop condition is true. Entering loop body
4
Assuming 'i' is not equal to 'e'
5
Loop condition is true. Entering loop body
7
Assuming 'i' is not equal to 'e'
8
Loop condition is true. Entering loop body
10
Assuming 'i' is not equal to 'e'
11
Loop condition is true. Entering loop body
4640 if (PN->getIncomingValue(i) == LF.OperandValToReplace) {
3
Taking false branch
6
Taking false branch
9
Taking false branch
12
Assuming pointer value is null
13
Taking true branch
4641 BasicBlock *BB = PN->getIncomingBlock(i);
4642
4643 // If this is a critical edge, split the edge so that we do not insert
4644 // the code on all predecessor/successor paths. We do this unless this
4645 // is the canonical backedge for this loop, which complicates post-inc
4646 // users.
4647 if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&
4648 !isa<IndirectBrInst>(BB->getTerminator())) {
4649 BasicBlock *Parent = PN->getParent();
4650 Loop *PNLoop = LI.getLoopFor(Parent);
4651 if (!PNLoop || Parent != PNLoop->getHeader()) {
4652 // Split the critical edge.
4653 BasicBlock *NewBB = nullptr;
4654 if (!Parent->isLandingPad()) {
4655 NewBB = SplitCriticalEdge(BB, Parent,
4656 CriticalEdgeSplittingOptions(&DT, &LI)
4657 .setMergeIdenticalEdges()
4658 .setDontDeleteUselessPHIs());
4659 } else {
4660 SmallVector<BasicBlock*, 2> NewBBs;
4661 SplitLandingPadPredecessors(Parent, BB, "", "", NewBBs,
4662 /*AliasAnalysis*/ nullptr, &DT, &LI);
4663 NewBB = NewBBs[0];
4664 }
4665 // If NewBB==NULL, then SplitCriticalEdge refused to split because all
4666 // phi predecessors are identical. The simple thing to do is skip
4667 // splitting in this case rather than complicate the API.
4668 if (NewBB) {
4669 // If PN is outside of the loop and BB is in the loop, we want to
4670 // move the block to be immediately before the PHI block, not
4671 // immediately after BB.
4672 if (L->contains(BB) && !L->contains(PN))
4673 NewBB->moveBefore(PN->getParent());
4674
4675 // Splitting the edge can reduce the number of PHI entries we have.
4676 e = PN->getNumIncomingValues();
4677 BB = NewBB;
4678 i = PN->getBasicBlockIndex(BB);
4679 }
4680 }
4681 }
4682
4683 std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =
4684 Inserted.insert(std::make_pair(BB, static_cast<Value *>(nullptr)));
4685 if (!Pair.second)
14
Taking false branch
4686 PN->setIncomingValue(i, Pair.first->second);
4687 else {
4688 Value *FullV = Expand(LF, F, BB->getTerminator(), Rewriter, DeadInsts);
4689
4690 // If this is reuse-by-noop-cast, insert the noop cast.
4691 Type *OpTy = LF.OperandValToReplace->getType();
15
Called C++ object pointer is null
4692 if (FullV->getType() != OpTy)
4693 FullV =
4694 CastInst::Create(CastInst::getCastOpcode(FullV, false,
4695 OpTy, false),
4696 FullV, LF.OperandValToReplace->getType(),
4697 "tmp", BB->getTerminator());
4698
4699 PN->setIncomingValue(i, FullV);
4700 Pair.first->second = FullV;
4701 }
4702 }
4703}
4704
4705/// Rewrite - Emit instructions for the leading candidate expression for this
4706/// LSRUse (this is called "expanding"), and update the UserInst to reference
4707/// the newly expanded value.
4708void LSRInstance::Rewrite(const LSRFixup &LF,
4709 const Formula &F,
4710 SCEVExpander &Rewriter,
4711 SmallVectorImpl<WeakVH> &DeadInsts,
4712 Pass *P) const {
4713 // First, find an insertion point that dominates UserInst. For PHI nodes,
4714 // find the nearest block which dominates all the relevant uses.
4715 if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) {
4716 RewriteForPHI(PN, LF, F, Rewriter, DeadInsts, P);
4717 } else {
4718 Value *FullV = Expand(LF, F, LF.UserInst, Rewriter, DeadInsts);
4719
4720 // If this is reuse-by-noop-cast, insert the noop cast.
4721 Type *OpTy = LF.OperandValToReplace->getType();
4722 if (FullV->getType() != OpTy) {
4723 Instruction *Cast =
4724 CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false),
4725 FullV, OpTy, "tmp", LF.UserInst);
4726 FullV = Cast;
4727 }
4728
4729 // Update the user. ICmpZero is handled specially here (for now) because
4730 // Expand may have updated one of the operands of the icmp already, and
4731 // its new value may happen to be equal to LF.OperandValToReplace, in
4732 // which case doing replaceUsesOfWith leads to replacing both operands
4733 // with the same value. TODO: Reorganize this.
4734 if (Uses[LF.LUIdx].Kind == LSRUse::ICmpZero)
4735 LF.UserInst->setOperand(0, FullV);
4736 else
4737 LF.UserInst->replaceUsesOfWith(LF.OperandValToReplace, FullV);
4738 }
4739
4740 DeadInsts.emplace_back(LF.OperandValToReplace);
4741}
4742
4743/// ImplementSolution - Rewrite all the fixup locations with new values,
4744/// following the chosen solution.
4745void
4746LSRInstance::ImplementSolution(const SmallVectorImpl<const Formula *> &Solution,
4747 Pass *P) {
4748 // Keep track of instructions we may have made dead, so that
4749 // we can remove them after we are done working.
4750 SmallVector<WeakVH, 16> DeadInsts;
4751
4752 SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(),
4753 "lsr");
4754#ifndef NDEBUG
4755 Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");
4756#endif
4757 Rewriter.disableCanonicalMode();
4758 Rewriter.enableLSRMode();
4759 Rewriter.setIVIncInsertPos(L, IVIncInsertPos);
4760
4761 // Mark phi nodes that terminate chains so the expander tries to reuse them.
4762 for (const IVChain &Chain : IVChainVec) {
4763 if (PHINode *PN = dyn_cast<PHINode>(Chain.tailUserInst()))
4764 Rewriter.setChainedPhi(PN);
4765 }
4766
4767 // Expand the new value definitions and update the users.
4768 for (const LSRFixup &Fixup : Fixups) {
4769 Rewrite(Fixup, *Solution[Fixup.LUIdx], Rewriter, DeadInsts, P);
4770
4771 Changed = true;
4772 }
4773
4774 for (const IVChain &Chain : IVChainVec) {
4775 GenerateIVChain(Chain, Rewriter, DeadInsts);
4776 Changed = true;
4777 }
4778 // Clean up after ourselves. This must be done before deleting any
4779 // instructions.
4780 Rewriter.clear();
4781
4782 Changed |= DeleteTriviallyDeadInstructions(DeadInsts);
4783}
4784
4785LSRInstance::LSRInstance(Loop *L, Pass *P)
4786 : IU(P->getAnalysis<IVUsers>()), SE(P->getAnalysis<ScalarEvolution>()),
4787 DT(P->getAnalysis<DominatorTreeWrapperPass>().getDomTree()),
4788 LI(P->getAnalysis<LoopInfoWrapperPass>().getLoopInfo()),
4789 TTI(P->getAnalysis<TargetTransformInfoWrapperPass>().getTTI(
4790 *L->getHeader()->getParent())),
4791 L(L), Changed(false), IVIncInsertPos(nullptr) {
4792 // If LoopSimplify form is not available, stay out of trouble.
4793 if (!L->isLoopSimplifyForm())
4794 return;
4795
4796 // If there's no interesting work to be done, bail early.
4797 if (IU.empty()) return;
4798
4799 // If there's too much analysis to be done, bail early. We won't be able to
4800 // model the problem anyway.
4801 unsigned NumUsers = 0;
4802 for (const IVStrideUse &U : IU) {
4803 if (++NumUsers > MaxIVUsers) {
4804 (void)U;
4805 DEBUG(dbgs() << "LSR skipping loop, too many IV Users in " << U << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in "
<< U << "\n"; } } while (0)
;
4806 return;
4807 }
4808 }
4809
4810#ifndef NDEBUG
4811 // All dominating loops must have preheaders, or SCEVExpander may not be able
4812 // to materialize an AddRecExpr whose Start is an outer AddRecExpr.
4813 //
4814 // IVUsers analysis should only create users that are dominated by simple loop
4815 // headers. Since this loop should dominate all of its users, its user list
4816 // should be empty if this loop itself is not within a simple loop nest.
4817 for (DomTreeNode *Rung = DT.getNode(L->getLoopPreheader());
4818 Rung; Rung = Rung->getIDom()) {
4819 BasicBlock *BB = Rung->getBlock();
4820 const Loop *DomLoop = LI.getLoopFor(BB);
4821 if (DomLoop && DomLoop->getHeader() == BB) {
4822 assert(DomLoop->getLoopPreheader() && "LSR needs a simplified loop nest")((DomLoop->getLoopPreheader() && "LSR needs a simplified loop nest"
) ? static_cast<void> (0) : __assert_fail ("DomLoop->getLoopPreheader() && \"LSR needs a simplified loop nest\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4822, __PRETTY_FUNCTION__))
;
4823 }
4824 }
4825#endif // DEBUG
4826
4827 DEBUG(dbgs() << "\nLSR on loop ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (0)
4828 L->getHeader()->printAsOperand(dbgs(), /*PrintType=*/false);do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (0)
4829 dbgs() << ":\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (0)
;
4830
4831 // First, perform some low-level loop optimizations.
4832 OptimizeShadowIV();
4833 OptimizeLoopTermCond();
4834
4835 // If loop preparation eliminates all interesting IV users, bail.
4836 if (IU.empty()) return;
4837
4838 // Skip nested loops until we can model them better with formulae.
4839 if (!L->empty()) {
4840 DEBUG(dbgs() << "LSR skipping outer loop " << *L << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping outer loop "
<< *L << "\n"; } } while (0)
;
4841 return;
4842 }
4843
4844 // Start collecting data and preparing for the solver.
4845 CollectChains();
4846 CollectInterestingTypesAndFactors();
4847 CollectFixupsAndInitialFormulae();
4848 CollectLoopInvariantFixupsAndFormulae();
4849
4850 assert(!Uses.empty() && "IVUsers reported at least one use")((!Uses.empty() && "IVUsers reported at least one use"
) ? static_cast<void> (0) : __assert_fail ("!Uses.empty() && \"IVUsers reported at least one use\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4850, __PRETTY_FUNCTION__))
;
4851 DEBUG(dbgs() << "LSR found " << Uses.size() << " uses:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR found " << Uses
.size() << " uses:\n"; print_uses(dbgs()); } } while (0
)
4852 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR found " << Uses
.size() << " uses:\n"; print_uses(dbgs()); } } while (0
)
;
4853
4854 // Now use the reuse data to generate a bunch of interesting ways
4855 // to formulate the values needed for the uses.
4856 GenerateAllReuseFormulae();
4857
4858 FilterOutUndesirableDedicatedRegisters();
4859 NarrowSearchSpaceUsingHeuristics();
4860
4861 SmallVector<const Formula *, 8> Solution;
4862 Solve(Solution);
4863
4864 // Release memory that is no longer needed.
4865 Factors.clear();
4866 Types.clear();
4867 RegUses.clear();
4868
4869 if (Solution.empty())
4870 return;
4871
4872#ifndef NDEBUG
4873 // Formulae should be legal.
4874 for (const LSRUse &LU : Uses) {
4875 for (const Formula &F : LU.Formulae)
4876 assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, F) && "Illegal formula generated!") ? static_cast<
void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Illegal formula generated!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4877, __PRETTY_FUNCTION__))
4877 F) && "Illegal formula generated!")((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, F) && "Illegal formula generated!") ? static_cast<
void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Illegal formula generated!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4877, __PRETTY_FUNCTION__))
;
4878 };
4879#endif
4880
4881 // Now that we've decided what we want, make it so.
4882 ImplementSolution(Solution, P);
4883}
4884
4885void LSRInstance::print_factors_and_types(raw_ostream &OS) const {
4886 if (Factors.empty() && Types.empty()) return;
4887
4888 OS << "LSR has identified the following interesting factors and types: ";
4889 bool First = true;
4890
4891 for (int64_t Factor : Factors) {
4892 if (!First) OS << ", ";
4893 First = false;
4894 OS << '*' << Factor;
4895 }
4896
4897 for (Type *Ty : Types) {
4898 if (!First) OS << ", ";
4899 First = false;
4900 OS << '(' << *Ty << ')';
4901 }
4902 OS << '\n';
4903}
4904
4905void LSRInstance::print_fixups(raw_ostream &OS) const {
4906 OS << "LSR is examining the following fixup sites:\n";
4907 for (const LSRFixup &LF : Fixups) {
4908 dbgs() << " ";
4909 LF.print(OS);
4910 OS << '\n';
4911 }
4912}
4913
4914void LSRInstance::print_uses(raw_ostream &OS) const {
4915 OS << "LSR is examining the following uses:\n";
4916 for (const LSRUse &LU : Uses) {
4917 dbgs() << " ";
4918 LU.print(OS);
4919 OS << '\n';
4920 for (const Formula &F : LU.Formulae) {
4921 OS << " ";
4922 F.print(OS);
4923 OS << '\n';
4924 }
4925 }
4926}
4927
4928void LSRInstance::print(raw_ostream &OS) const {
4929 print_factors_and_types(OS);
4930 print_fixups(OS);
4931 print_uses(OS);
4932}
4933
4934#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
4935void LSRInstance::dump() const {
4936 print(errs()); errs() << '\n';
4937}
4938#endif
4939
4940namespace {
4941
4942class LoopStrengthReduce : public LoopPass {
4943public:
4944 static char ID; // Pass ID, replacement for typeid
4945 LoopStrengthReduce();
4946
4947private:
4948 bool runOnLoop(Loop *L, LPPassManager &LPM) override;
4949 void getAnalysisUsage(AnalysisUsage &AU) const override;
4950};
4951
4952}
4953
4954char LoopStrengthReduce::ID = 0;
4955INITIALIZE_PASS_BEGIN(LoopStrengthReduce, "loop-reduce",static void* initializeLoopStrengthReducePassOnce(PassRegistry
&Registry) {
4956 "Loop Strength Reduction", false, false)static void* initializeLoopStrengthReducePassOnce(PassRegistry
&Registry) {
4957INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry);
4958INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);
4959INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)initializeScalarEvolutionPass(Registry);
4960INITIALIZE_PASS_DEPENDENCY(IVUsers)initializeIVUsersPass(Registry);
4961INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);
4962INITIALIZE_PASS_DEPENDENCY(LoopSimplify)initializeLoopSimplifyPass(Registry);
4963INITIALIZE_PASS_END(LoopStrengthReduce, "loop-reduce",PassInfo *PI = new PassInfo("Loop Strength Reduction", "loop-reduce"
, & LoopStrengthReduce ::ID, PassInfo::NormalCtor_t(callDefaultCtor
< LoopStrengthReduce >), false, false); Registry.registerPass
(*PI, true); return PI; } void llvm::initializeLoopStrengthReducePass
(PassRegistry &Registry) { static volatile sys::cas_flag initialized
= 0; sys::cas_flag old_val = sys::CompareAndSwap(&initialized
, 1, 0); if (old_val == 0) { initializeLoopStrengthReducePassOnce
(Registry); sys::MemoryFence(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4964); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4964, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4964); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4964, &initialized); }
4964 "Loop Strength Reduction", false, false)PassInfo *PI = new PassInfo("Loop Strength Reduction", "loop-reduce"
, & LoopStrengthReduce ::ID, PassInfo::NormalCtor_t(callDefaultCtor
< LoopStrengthReduce >), false, false); Registry.registerPass
(*PI, true); return PI; } void llvm::initializeLoopStrengthReducePass
(PassRegistry &Registry) { static volatile sys::cas_flag initialized
= 0; sys::cas_flag old_val = sys::CompareAndSwap(&initialized
, 1, 0); if (old_val == 0) { initializeLoopStrengthReducePassOnce
(Registry); sys::MemoryFence(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4964); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4964, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4964); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn239598/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4964, &initialized); }
4965
4966
4967Pass *llvm::createLoopStrengthReducePass() {
4968 return new LoopStrengthReduce();
4969}
4970
4971LoopStrengthReduce::LoopStrengthReduce() : LoopPass(ID) {
4972 initializeLoopStrengthReducePass(*PassRegistry::getPassRegistry());
4973}
4974
4975void LoopStrengthReduce::getAnalysisUsage(AnalysisUsage &AU) const {
4976 // We split critical edges, so we change the CFG. However, we do update
4977 // many analyses if they are around.
4978 AU.addPreservedID(LoopSimplifyID);
4979
4980 AU.addRequired<LoopInfoWrapperPass>();
4981 AU.addPreserved<LoopInfoWrapperPass>();
4982 AU.addRequiredID(LoopSimplifyID);
4983 AU.addRequired<DominatorTreeWrapperPass>();
4984 AU.addPreserved<DominatorTreeWrapperPass>();
4985 AU.addRequired<ScalarEvolution>();
4986 AU.addPreserved<ScalarEvolution>();
4987 // Requiring LoopSimplify a second time here prevents IVUsers from running
4988 // twice, since LoopSimplify was invalidated by running ScalarEvolution.
4989 AU.addRequiredID(LoopSimplifyID);
4990 AU.addRequired<IVUsers>();
4991 AU.addPreserved<IVUsers>();
4992 AU.addRequired<TargetTransformInfoWrapperPass>();
4993}
4994
4995bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager & /*LPM*/) {
4996 if (skipOptnoneFunction(L))
4997 return false;
4998
4999 bool Changed = false;
5000
5001 // Run the main LSR transformation.
5002 Changed |= LSRInstance(L, this).getChanged();
5003
5004 // Remove any extra phis created by processing inner loops.
5005 Changed |= DeleteDeadPHIs(L->getHeader());
5006 if (EnablePhiElim && L->isLoopSimplifyForm()) {
5007 SmallVector<WeakVH, 16> DeadInsts;
5008 const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
5009 SCEVExpander Rewriter(getAnalysis<ScalarEvolution>(), DL, "lsr");
5010#ifndef NDEBUG
5011 Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");
5012#endif
5013 unsigned numFolded = Rewriter.replaceCongruentIVs(
5014 L, &getAnalysis<DominatorTreeWrapperPass>().getDomTree(), DeadInsts,
5015 &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(
5016 *L->getHeader()->getParent()));
5017 if (numFolded) {
5018 Changed = true;
5019 DeleteTriviallyDeadInstructions(DeadInsts);
5020 DeleteDeadPHIs(L->getHeader());
5021 }
5022 }
5023 return Changed;
5024}