/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp

Bug Summary

File:	lib/Transforms/Scalar/LoopStrengthReduce.cpp
Location:	line 4231, column 5
Description:	Forming reference to null pointer

Annotated Source Code

//===- LoopStrengthReduce.cpp - Strength Reduce IVs in Loops --------------===//

// The LLVM Compiler Infrastructure

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//===----------------------------------------------------------------------===//

// This transformation analyzes and transforms the induction variables (and

// computations derived from them) into forms suitable for efficient execution

// on the target.

// This pass performs a strength reduction on array references inside loops that

// have as one or more of their components the loop induction variable, it

// rewrites expressions to take advantage of scaled-index addressing modes

// available on the target, and it performs a variety of other optimizations

// related to loop induction variables.

// Terminology note: this code has a lot of handling for "post-increment" or

// "post-inc" users. This is not talking about post-increment addressing modes;

// it is instead talking about code like this:

// %i = phi [ 0, %entry ], [ %i.next, %latch ]

// ...

// %i.next = add %i, 1

// %c = icmp eq %i.next, %n

// The SCEV for %i is {0,+,1}<%L>. The SCEV for %i.next is {1,+,1}<%L>, however

// it's useful to think about these as the same register, with some uses using

// the value of the register before the add and some using it after. In this

// example, the icmp is a post-increment user, since it uses %i.next, which is

// the value of the induction variable after the increment. The other common

// case of post-increment users is users outside the loop.

// TODO: More sophistication in the way Formulae are generated and filtered.

// TODO: Handle multiple loops at a time.

// TODO: Should the addressing mode BaseGV be changed to a ConstantExpr instead

// of a GlobalValue?

// TODO: When truncation is free, truncate ICmp users' operands to make it a

// smaller encoding (on x86 at least).

// TODO: When a negated register is used by an add (such as in a list of

// multiple base registers, or as the increment expression in an addrec),

// we may not actually need both reg and (-1 * reg) in registers; the

// negation can be implemented by using a sub instead of an add. The

// lack of support for taking this into consideration when making

// register pressure decisions is partly worked around by the "Special"

// use kind.

//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Scalar.h"

#include "llvm/ADT/DenseSet.h"

#include "llvm/ADT/Hashing.h"

#include "llvm/ADT/STLExtras.h"

#include "llvm/ADT/SetVector.h"

#include "llvm/ADT/SmallBitVector.h"

#include "llvm/Analysis/IVUsers.h"

#include "llvm/Analysis/LoopPass.h"

#include "llvm/Analysis/ScalarEvolutionExpander.h"

#include "llvm/Analysis/TargetTransformInfo.h"

#include "llvm/IR/Constants.h"

#include "llvm/IR/DerivedTypes.h"

#include "llvm/IR/Dominators.h"

#include "llvm/IR/Instructions.h"

#include "llvm/IR/IntrinsicInst.h"

#include "llvm/IR/Module.h"

#include "llvm/IR/ValueHandle.h"

#include "llvm/Support/CommandLine.h"

#include "llvm/Support/Debug.h"

#include "llvm/Support/raw_ostream.h"

#include "llvm/Transforms/Utils/BasicBlockUtils.h"

#include "llvm/Transforms/Utils/Local.h"

#include <algorithm>

using namespace llvm;

#define DEBUG_TYPE"loop-reduce" "loop-reduce"

/// MaxIVUsers is an arbitrary threshold that provides an early opportunitiy for

/// bail out. This threshold is far beyond the number of users that LSR can

/// conceivably solve, so it should not affect generated code, but catches the

/// worst cases before LSR burns too much compile time and stack space.

static const unsigned MaxIVUsers = 200;

// Temporary flag to cleanup congruent phis after LSR phi expansion.

// It's currently disabled until we can determine whether it's truly useful or

// not. The flag should be removed after the v3.0 release.

// This is now needed for ivchains.

static cl::opt<bool> EnablePhiElim(

"enable-lsr-phielim", cl::Hidden, cl::init(true),

cl::desc("Enable LSR phi elimination"));

#ifndef NDEBUG

// Stress test IV chain generation.

static cl::opt<bool> StressIVChain(

100

"stress-ivchain", cl::Hidden, cl::init(false),

101

cl::desc("Stress test LSR IV chains"));

102

#else

103

static bool StressIVChain = false;

104

#endif

105

106

namespace {

107

108

/// RegSortData - This class holds data which is used to order reuse candidates.

109

class RegSortData {

110

public:

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

121

void RegSortData::print(raw_ostream &OS) const {

122

OS << "[NumUses=" << UsedByIndices.count() << ']';

123

}

124

125

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

126

void RegSortData::dump() const {

127

print(errs()); errs() << '\n';

128

}

129

#endif

130

131

namespace {

132

133

/// RegUseTracker - Map register candidates to information about how they are

134

/// used.

135

class RegUseTracker {

136

typedef DenseMap<const SCEV *, RegSortData> RegUsesTy;

137

138

RegUsesTy RegUsesMap;

139

SmallVector<const SCEV *, 16> RegSequence;

140

141

public:

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

162

void

163

RegUseTracker::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

173

void

174

RegUseTracker::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~svn237945/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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 178, __PRETTY_FUNCTION__));

179

RSD.UsedByIndices.reset(LUIdx);

180

}

181

182

void

183

RegUseTracker::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~svn237945/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 (RegUsesTy::iterator I = RegUsesMap.begin(), E = RegUsesMap.end();

189

I != E; ++I) {

190

SmallBitVector &UsedByIndices = I->second.UsedByIndices;

191

if (LUIdx < UsedByIndices.size())

192

UsedByIndices[LUIdx] =

193

LastLUIdx < UsedByIndices.size() ? UsedByIndices[LastLUIdx] : 0;

194

UsedByIndices.resize(std::min(UsedByIndices.size(), LastLUIdx));

195

}

196

}

197

198

bool

199

RegUseTracker::isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const {

200

RegUsesTy::const_iterator I = RegUsesMap.find(Reg);

201

if (I == RegUsesMap.end())

202

return false;

203

const SmallBitVector &UsedByIndices = I->second.UsedByIndices;

204

int i = UsedByIndices.find_first();

205

if (i == -1) return false;

206

if ((size_t)i != LUIdx) return true;

207

return UsedByIndices.find_next(i) != -1;

208

}

209

210

const SmallBitVector &RegUseTracker::getUsedByIndices(const SCEV *Reg) const {

211

RegUsesTy::const_iterator I = RegUsesMap.find(Reg);

212

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 212, __PRETTY_FUNCTION__));

213

return I->second.UsedByIndices;

214

}

215

216

void RegUseTracker::clear() {

217

RegUsesMap.clear();

218

RegSequence.clear();

219

}

220

221

namespace {

222

223

/// Formula - This class holds information that describes a formula for

224

/// computing satisfying a use. It may include broken-out immediates and scaled

225

/// registers.

226

struct Formula {

227

/// Global base address used for complex addressing.

228

GlobalValue *BaseGV;

229

230

/// Base offset for complex addressing.

231

int64_t BaseOffset;

232

233

/// Whether any complex addressing has a base register.

234

bool HasBaseReg;

235

236

/// The scale of any complex addressing.

237

int64_t Scale;

238

239

/// BaseRegs - The list of "base" registers for this use. When this is

240

/// non-empty. The canonical representation of a formula is

241

/// 1. BaseRegs.size > 1 implies ScaledReg != NULL and

242

/// 2. ScaledReg != NULL implies Scale != 1 || !BaseRegs.empty().

243

/// #1 enforces that the scaled register is always used when at least two

244

/// registers are needed by the formula: e.g., reg1 + reg2 is reg1 + 1 * reg2.

245

/// #2 enforces that 1 * reg is reg.

246

/// This invariant can be temporarly broken while building a formula.

247

/// However, every formula inserted into the LSRInstance must be in canonical

248

/// form.

249

SmallVector<const SCEV *, 4> BaseRegs;

250

251

/// ScaledReg - The 'scaled' register for this use. This should be non-null

252

/// when Scale is not zero.

253

const SCEV *ScaledReg;

254

255

/// UnfoldedOffset - An additional constant offset which added near the

256

/// use. This requires a temporary register, but the offset itself can

257

/// live in an add immediate field rather than a register.

258

int64_t UnfoldedOffset;

259

260

Formula()

261

: BaseGV(nullptr), BaseOffset(0), HasBaseReg(false), Scale(0),

262

ScaledReg(nullptr), UnfoldedOffset(0) {}

263

264

void InitialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE);

265

266

bool isCanonical() const;

267

268

void Canonicalize();

269

270

bool Unscale();

271

272

size_t getNumRegs() const;

273

Type *getType() const;

274

275

void DeleteBaseReg(const SCEV *&S);

276

277

bool referencesReg(const SCEV *S) const;

278

bool hasRegsUsedByUsesOtherThan(size_t LUIdx,

279

const RegUseTracker &RegUses) const;

280

281

void print(raw_ostream &OS) const;

282

void dump() const;

283

};

284

285

}

286

287

/// DoInitialMatch - Recursion helper for InitialMatch.

288

static void DoInitialMatch(const SCEV *S, Loop *L,

289

SmallVectorImpl<const SCEV *> &Good,

290

SmallVectorImpl<const SCEV *> &Bad,

291

ScalarEvolution &SE) {

292

// Collect expressions which properly dominate the loop header.

293

if (SE.properlyDominates(S, L->getHeader())) {

294

Good.push_back(S);

295

return;

296

}

297

298

// Look at add operands.

299

if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {

300

for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();

301

I != E; ++I)

302

DoInitialMatch(*I, L, Good, Bad, SE);

303

return;

304

}

305

306

// Look at addrec operands.

307

if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))

308

if (!AR->getStart()->isZero()) {

309

DoInitialMatch(AR->getStart(), L, Good, Bad, SE);

310

DoInitialMatch(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0),

311

AR->getStepRecurrence(SE),

312

// FIXME: AR->getNoWrapFlags()

313

AR->getLoop(), SCEV::FlagAnyWrap),

314

L, Good, Bad, SE);

315

return;

316

}

317

318

// Handle a multiplication by -1 (negation) if it didn't fold.

319

if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S))

320

if (Mul->getOperand(0)->isAllOnesValue()) {

321

SmallVector<const SCEV *, 4> Ops(Mul->op_begin()+1, Mul->op_end());

322

const SCEV *NewMul = SE.getMulExpr(Ops);

323

324

SmallVector<const SCEV *, 4> MyGood;

325

SmallVector<const SCEV *, 4> MyBad;

326

DoInitialMatch(NewMul, L, MyGood, MyBad, SE);

327

const SCEV *NegOne = SE.getSCEV(ConstantInt::getAllOnesValue(

328

SE.getEffectiveSCEVType(NewMul->getType())));

329

for (SmallVectorImpl<const SCEV *>::const_iterator I = MyGood.begin(),

330

E = MyGood.end(); I != E; ++I)

331

Good.push_back(SE.getMulExpr(NegOne, *I));

332

for (SmallVectorImpl<const SCEV *>::const_iterator I = MyBad.begin(),

333

E = MyBad.end(); I != E; ++I)

334

Bad.push_back(SE.getMulExpr(NegOne, *I));

335

return;

336

}

337

338

// Ok, we can't do anything interesting. Just stuff the whole thing into a

339

// register and hope for the best.

340

Bad.push_back(S);

341

}

342

343

/// InitialMatch - Incorporate loop-variant parts of S into this Formula,

344

/// attempting to keep all loop-invariant and loop-computable values in a

345

/// single base register.

346

void Formula::InitialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE) {

347

SmallVector<const SCEV *, 4> Good;

348

SmallVector<const SCEV *, 4> Bad;

349

DoInitialMatch(S, L, Good, Bad, SE);

350

if (!Good.empty()) {

351

const SCEV *Sum = SE.getAddExpr(Good);

352

if (!Sum->isZero())

353

BaseRegs.push_back(Sum);

354

HasBaseReg = true;

355

}

356

if (!Bad.empty()) {

357

const SCEV *Sum = SE.getAddExpr(Bad);

358

if (!Sum->isZero())

359

BaseRegs.push_back(Sum);

360

HasBaseReg = true;

361

}

362

Canonicalize();

363

}

364

365

/// \brief Check whether or not this formula statisfies the canonical

366

/// representation.

367

/// \see Formula::BaseRegs.

368

bool Formula::isCanonical() const {

369

if (ScaledReg)

370

return Scale != 1 || !BaseRegs.empty();

371

return BaseRegs.size() <= 1;

372

}

373

374

/// \brief Helper method to morph a formula into its canonical representation.

375

/// \see Formula::BaseRegs.

376

/// Every formula having more than one base register, must use the ScaledReg

377

/// field. Otherwise, we would have to do special cases everywhere in LSR

378

/// to treat reg1 + reg2 + ... the same way as reg1 + 1*reg2 + ...

379

/// On the other hand, 1*reg should be canonicalized into reg.

380

void Formula::Canonicalize() {

381

if (isCanonical())

382

return;

383

// So far we did not need this case. This is easy to implement but it is

384

// useless to maintain dead code. Beside it could hurt compile time.

385

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 385, __PRETTY_FUNCTION__));

386

// Keep the invariant sum in BaseRegs and one of the variant sum in ScaledReg.

387

ScaledReg = BaseRegs.back();

388

BaseRegs.pop_back();

389

Scale = 1;

390

size_t BaseRegsSize = BaseRegs.size();

391

size_t Try = 0;

392

// If ScaledReg is an invariant, try to find a variant expression.

393

while (Try < BaseRegsSize && !isa<SCEVAddRecExpr>(ScaledReg))

394

std::swap(ScaledReg, BaseRegs[Try++]);

395

}

396

397

/// \brief Get rid of the scale in the formula.

398

/// In other words, this method morphes reg1 + 1*reg2 into reg1 + reg2.

399

/// \return true if it was possible to get rid of the scale, false otherwise.

400

/// \note After this operation the formula may not be in the canonical form.

401

bool Formula::Unscale() {

402

if (Scale != 1)

403

return false;

404

Scale = 0;

405

BaseRegs.push_back(ScaledReg);

406

ScaledReg = nullptr;

407

return true;

408

}

409

410

/// getNumRegs - Return the total number of register operands used by this

411

/// formula. This does not include register uses implied by non-constant

412

/// addrec strides.

413

size_t Formula::getNumRegs() const {

414

return !!ScaledReg + BaseRegs.size();

415

}

416

417

/// getType - Return the type of this formula, if it has one, or null

418

/// otherwise. This type is meaningless except for the bit size.

419

Type *Formula::getType() const {

420

return !BaseRegs.empty() ? BaseRegs.front()->getType() :

421

ScaledReg ? ScaledReg->getType() :

422

BaseGV ? BaseGV->getType() :

423

nullptr;

424

}

425

426

/// DeleteBaseReg - Delete the given base reg from the BaseRegs list.

427

void Formula::DeleteBaseReg(const SCEV *&S) {

428

if (&S != &BaseRegs.back())

429

std::swap(S, BaseRegs.back());

430

BaseRegs.pop_back();

431

}

432

433

/// referencesReg - Test if this formula references the given register.

434

bool Formula::referencesReg(const SCEV *S) const {

435

return S == ScaledReg ||

436

std::find(BaseRegs.begin(), BaseRegs.end(), S) != BaseRegs.end();

437

}

438

439

/// hasRegsUsedByUsesOtherThan - Test whether this formula uses registers

440

/// which are used by uses other than the use with the given index.

441

bool Formula::hasRegsUsedByUsesOtherThan(size_t LUIdx,

442

const RegUseTracker &RegUses) const {

443

if (ScaledReg)

444

if (RegUses.isRegUsedByUsesOtherThan(ScaledReg, LUIdx))

445

return true;

446

for (SmallVectorImpl<const SCEV *>::const_iterator I = BaseRegs.begin(),

447

E = BaseRegs.end(); I != E; ++I)

448

if (RegUses.isRegUsedByUsesOtherThan(*I, LUIdx))

449

return true;

450

return false;

451

}

452

453

void Formula::print(raw_ostream &OS) const {

454

bool First = true;

455

if (BaseGV) {

456

if (!First) OS << " + "; else First = false;

457

BaseGV->printAsOperand(OS, /*PrintType=*/false);

458

}

459

if (BaseOffset != 0) {

460

if (!First) OS << " + "; else First = false;

461

OS << BaseOffset;

462

}

463

for (SmallVectorImpl<const SCEV *>::const_iterator I = BaseRegs.begin(),

464

E = BaseRegs.end(); I != E; ++I) {

465

if (!First) OS << " + "; else First = false;

466

OS << "reg(" << **I << ')';

467

}

468

if (HasBaseReg && BaseRegs.empty()) {

469

if (!First) OS << " + "; else First = false;

470

OS << "**error: HasBaseReg**";

471

} else if (!HasBaseReg && !BaseRegs.empty()) {

472

if (!First) OS << " + "; else First = false;

473

OS << "**error: !HasBaseReg**";

474

}

475

if (Scale != 0) {

476

if (!First) OS << " + "; else First = false;

477

OS << Scale << "*reg(";

478

if (ScaledReg)

479

OS << *ScaledReg;

480

else

481

OS << "<unknown>";

482

OS << ')';

483

}

484

if (UnfoldedOffset != 0) {

485

if (!First) OS << " + ";

486

OS << "imm(" << UnfoldedOffset << ')';

487

}

488

}

489

490

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

491

void Formula::dump() const {

492

print(errs()); errs() << '\n';

493

}

494

#endif

495

496

/// isAddRecSExtable - Return true if the given addrec can be sign-extended

497

/// without changing its value.

498

static bool isAddRecSExtable(const SCEVAddRecExpr *AR, ScalarEvolution &SE) {

499

Type *WideTy =

500

IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(AR->getType()) + 1);

501

return isa<SCEVAddRecExpr>(SE.getSignExtendExpr(AR, WideTy));

502

}

503

504

/// isAddSExtable - Return true if the given add can be sign-extended

505

/// without changing its value.

506

static bool isAddSExtable(const SCEVAddExpr *A, ScalarEvolution &SE) {

507

Type *WideTy =

508

IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(A->getType()) + 1);

509

return isa<SCEVAddExpr>(SE.getSignExtendExpr(A, WideTy));

510

}

511

512

/// isMulSExtable - Return true if the given mul can be sign-extended

513

/// without changing its value.

514

static bool isMulSExtable(const SCEVMulExpr *M, ScalarEvolution &SE) {

515

Type *WideTy =

516

IntegerType::get(SE.getContext(),

517

SE.getTypeSizeInBits(M->getType()) * M->getNumOperands());

518

return isa<SCEVMulExpr>(SE.getSignExtendExpr(M, WideTy));

519

}

520

521

/// getExactSDiv - Return an expression for LHS /s RHS, if it can be determined

522

/// and if the remainder is known to be zero, or null otherwise. If

523

/// IgnoreSignificantBits is true, expressions like (X * Y) /s Y are simplified

524

/// to Y, ignoring that the multiplication may overflow, which is useful when

525

/// the result will be used in a context where the most significant bits are

526

/// ignored.

527

static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS,

528

ScalarEvolution &SE,

529

bool IgnoreSignificantBits = false) {

530

// Handle the trivial case, which works for any SCEV type.

531

if (LHS == RHS)

532

return SE.getConstant(LHS->getType(), 1);

533

534

// Handle a few RHS special cases.

535

const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS);

536

if (RC) {

537

const APInt &RA = RC->getValue()->getValue();

538

// Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do

539

// some folding.

540

if (RA.isAllOnesValue())

541

return SE.getMulExpr(LHS, RC);

542

// Handle x /s 1 as x.

543

if (RA == 1)

544

return LHS;

545

}

546

547

// Check for a division of a constant by a constant.

548

if (const SCEVConstant *C = dyn_cast<SCEVConstant>(LHS)) {

549

if (!RC)

550

return nullptr;

551

const APInt &LA = C->getValue()->getValue();

552

const APInt &RA = RC->getValue()->getValue();

553

if (LA.srem(RA) != 0)

554

return nullptr;

555

return SE.getConstant(LA.sdiv(RA));

556

}

557

558

// Distribute the sdiv over addrec operands, if the addrec doesn't overflow.

559

if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) {

560

if (IgnoreSignificantBits || isAddRecSExtable(AR, SE)) {

561

const SCEV *Step = getExactSDiv(AR->getStepRecurrence(SE), RHS, SE,

562

IgnoreSignificantBits);

563

if (!Step) return nullptr;

564

const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE,

565

IgnoreSignificantBits);

566

if (!Start) return nullptr;

567

// FlagNW is independent of the start value, step direction, and is

568

// preserved with smaller magnitude steps.

569

// FIXME: AR->getNoWrapFlags(SCEV::FlagNW)

570

return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap);

571

}

572

return nullptr;

573

}

574

575

// Distribute the sdiv over add operands, if the add doesn't overflow.

576

if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(LHS)) {

577

if (IgnoreSignificantBits || isAddSExtable(Add, SE)) {

578

SmallVector<const SCEV *, 8> Ops;

579

for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();

580

I != E; ++I) {

581

const SCEV *Op = getExactSDiv(*I, RHS, SE,

582

IgnoreSignificantBits);

583

if (!Op) return nullptr;

584

Ops.push_back(Op);

585

}

586

return SE.getAddExpr(Ops);

587

}

588

return nullptr;

589

}

590

591

// Check for a multiply operand that we can pull RHS out of.

592

if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS)) {

593

if (IgnoreSignificantBits || isMulSExtable(Mul, SE)) {

594

SmallVector<const SCEV *, 4> Ops;

595

bool Found = false;

596

for (SCEVMulExpr::op_iterator I = Mul->op_begin(), E = Mul->op_end();

597

I != E; ++I) {

598

const SCEV *S = *I;

599

if (!Found)

600

if (const SCEV *Q = getExactSDiv(S, RHS, SE,

601

IgnoreSignificantBits)) {

602

S = Q;

603

Found = true;

604

}

605

Ops.push_back(S);

606

}

607

return Found ? SE.getMulExpr(Ops) : nullptr;

608

}

609

return nullptr;

610

}

611

612

// Otherwise we don't know.

613

return nullptr;

614

}

615

616

/// ExtractImmediate - If S involves the addition of a constant integer value,

617

/// return that integer value, and mutate S to point to a new SCEV with that

618

/// value excluded.

619

static int64_t ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) {

620

if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {

621

if (C->getValue()->getValue().getMinSignedBits() <= 64) {

622

S = SE.getConstant(C->getType(), 0);

623

return C->getValue()->getSExtValue();

624

}

625

} else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {

626

SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());

627

int64_t Result = ExtractImmediate(NewOps.front(), SE);

628

if (Result != 0)

629

S = SE.getAddExpr(NewOps);

630

return Result;

631

} else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {

632

SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());

633

int64_t Result = ExtractImmediate(NewOps.front(), SE);

634

if (Result != 0)

635

S = SE.getAddRecExpr(NewOps, AR->getLoop(),

636

// FIXME: AR->getNoWrapFlags(SCEV::FlagNW)

637

SCEV::FlagAnyWrap);

638

return Result;

639

}

640

return 0;

641

}

642

643

/// ExtractSymbol - If S involves the addition of a GlobalValue address,

644

/// return that symbol, and mutate S to point to a new SCEV with that

645

/// value excluded.

646

static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) {

647

if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {

648

if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) {

649

S = SE.getConstant(GV->getType(), 0);

650

return GV;

651

}

652

} else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {

653

SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());

654

GlobalValue *Result = ExtractSymbol(NewOps.back(), SE);

655

if (Result)

656

S = SE.getAddExpr(NewOps);

657

return Result;

658

} else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {

659

SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());

660

GlobalValue *Result = ExtractSymbol(NewOps.front(), SE);

661

if (Result)

662

S = SE.getAddRecExpr(NewOps, AR->getLoop(),

663

// FIXME: AR->getNoWrapFlags(SCEV::FlagNW)

664

SCEV::FlagAnyWrap);

665

return Result;

666

}

667

return nullptr;

668

}

669

670

/// isAddressUse - Returns true if the specified instruction is using the

671

/// specified value as an address.

672

static bool isAddressUse(Instruction *Inst, Value *OperandVal) {

673

bool isAddress = isa<LoadInst>(Inst);

674

if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {

675

if (SI->getOperand(1) == OperandVal)

676

isAddress = true;

677

} else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {

678

// Addressing modes can also be folded into prefetches and a variety

679

// of intrinsics.

680

switch (II->getIntrinsicID()) {

681

default: break;

682

case Intrinsic::prefetch:

683

case Intrinsic::x86_sse_storeu_ps:

684

case Intrinsic::x86_sse2_storeu_pd:

685

case Intrinsic::x86_sse2_storeu_dq:

686

case Intrinsic::x86_sse2_storel_dq:

687

if (II->getArgOperand(0) == OperandVal)

688

isAddress = true;

689

break;

690

}

691

}

692

return isAddress;

693

}

694

695

/// getAccessType - Return the type of the memory being accessed.

696

static Type *getAccessType(const Instruction *Inst) {

697

Type *AccessTy = Inst->getType();

698

if (const StoreInst *SI = dyn_cast<StoreInst>(Inst))

699

AccessTy = SI->getOperand(0)->getType();

700

else if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {

701

// Addressing modes can also be folded into prefetches and a variety

702

// of intrinsics.

703

switch (II->getIntrinsicID()) {

704

default: break;

705

case Intrinsic::x86_sse_storeu_ps:

706

case Intrinsic::x86_sse2_storeu_pd:

707

case Intrinsic::x86_sse2_storeu_dq:

708

case Intrinsic::x86_sse2_storel_dq:

709

AccessTy = II->getArgOperand(0)->getType();

710

break;

711

}

712

}

713

714

// All pointers have the same requirements, so canonicalize them to an

715

// arbitrary pointer type to minimize variation.

716

if (PointerType *PTy = dyn_cast<PointerType>(AccessTy))

717

AccessTy = PointerType::get(IntegerType::get(PTy->getContext(), 1),

718

PTy->getAddressSpace());

719

720

return AccessTy;

721

}

722

723

/// isExistingPhi - Return true if this AddRec is already a phi in its loop.

724

static bool isExistingPhi(const SCEVAddRecExpr *AR, ScalarEvolution &SE) {

725

for (BasicBlock::iterator I = AR->getLoop()->getHeader()->begin();

726

PHINode *PN = dyn_cast<PHINode>(I); ++I) {

727

if (SE.isSCEVable(PN->getType()) &&

728

(SE.getEffectiveSCEVType(PN->getType()) ==

729

SE.getEffectiveSCEVType(AR->getType())) &&

730

SE.getSCEV(PN) == AR)

731

return true;

732

}

733

return false;

734

}

735

736

/// Check if expanding this expression is likely to incur significant cost. This

737

/// is tricky because SCEV doesn't track which expressions are actually computed

738

/// by the current IR.

739

///

740

/// We currently allow expansion of IV increments that involve adds,

741

/// multiplication by constants, and AddRecs from existing phis.

742

///

743

/// TODO: Allow UDivExpr if we can find an existing IV increment that is an

744

/// obvious multiple of the UDivExpr.

745

static bool isHighCostExpansion(const SCEV *S,

746

SmallPtrSetImpl<const SCEV*> &Processed,

747

ScalarEvolution &SE) {

748

// Zero/One operand expressions

749

switch (S->getSCEVType()) {

750

case scUnknown:

751

case scConstant:

752

return false;

753

case scTruncate:

754

return isHighCostExpansion(cast<SCEVTruncateExpr>(S)->getOperand(),

755

Processed, SE);

756

case scZeroExtend:

757

return isHighCostExpansion(cast<SCEVZeroExtendExpr>(S)->getOperand(),

758

Processed, SE);

759

case scSignExtend:

760

return isHighCostExpansion(cast<SCEVSignExtendExpr>(S)->getOperand(),

761

Processed, SE);

762

}

763

764

if (!Processed.insert(S).second)

765

return false;

766

767

if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {

768

for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();

769

I != E; ++I) {

770

if (isHighCostExpansion(*I, Processed, SE))

771

return true;

772

}

773

return false;

774

}

775

776

if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {

777

if (Mul->getNumOperands() == 2) {

778

// Multiplication by a constant is ok

779

if (isa<SCEVConstant>(Mul->getOperand(0)))

780

return isHighCostExpansion(Mul->getOperand(1), Processed, SE);

781

782

// If we have the value of one operand, check if an existing

783

// multiplication already generates this expression.

784

if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Mul->getOperand(1))) {

785

Value *UVal = U->getValue();

786

for (User *UR : UVal->users()) {

787

// If U is a constant, it may be used by a ConstantExpr.

788

Instruction *UI = dyn_cast<Instruction>(UR);

789

if (UI && UI->getOpcode() == Instruction::Mul &&

790

SE.isSCEVable(UI->getType())) {

791

return SE.getSCEV(UI) == Mul;

792

}

793

}

794

}

795

}

796

}

797

798

if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {

799

if (isExistingPhi(AR, SE))

800

return false;

801

}

802

803

// Fow now, consider any other type of expression (div/mul/min/max) high cost.

804

return true;

805

}

806

807

/// DeleteTriviallyDeadInstructions - If any of the instructions is the

808

/// specified set are trivially dead, delete them and see if this makes any of

809

/// their operands subsequently dead.

810

static bool

811

DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakVH> &DeadInsts) {

812

bool Changed = false;

813

814

while (!DeadInsts.empty()) {

815

Value *V = DeadInsts.pop_back_val();

816

Instruction *I = dyn_cast_or_null<Instruction>(V);

817

818

if (!I || !isInstructionTriviallyDead(I))

819

continue;

820

821

for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI)

822

if (Instruction *U = dyn_cast<Instruction>(*OI)) {

823

*OI = nullptr;

824

if (U->use_empty())

825

DeadInsts.push_back(U);

826

}

827

828

I->eraseFromParent();

829

Changed = true;

830

}

831

832

return Changed;

833

}

834

835

namespace {

836

class LSRUse;

837

}

838

839

/// \brief Check if the addressing mode defined by \p F is completely

840

/// folded in \p LU at isel time.

841

/// This includes address-mode folding and special icmp tricks.

842

/// This function returns true if \p LU can accommodate what \p F

843

/// defines and up to 1 base + 1 scaled + offset.

844

/// In other words, if \p F has several base registers, this function may

845

/// still return true. Therefore, users still need to account for

846

/// additional base registers and/or unfolded offsets to derive an

847

/// accurate cost model.

848

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

849

const LSRUse &LU, const Formula &F);

850

// Get the cost of the scaling factor used in F for LU.

851

static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,

852

const LSRUse &LU, const Formula &F);

853

854

namespace {

855

856

/// Cost - This class is used to measure and compare candidate formulae.

857

class Cost {

858

/// TODO: Some of these could be merged. Also, a lexical ordering

859

/// isn't always optimal.

860

unsigned NumRegs;

861

unsigned AddRecCost;

862

unsigned NumIVMuls;

863

unsigned NumBaseAdds;

864

unsigned ImmCost;

865

unsigned SetupCost;

866

unsigned ScaleCost;

867

868

public:

869

Cost()

870

: NumRegs(0), AddRecCost(0), NumIVMuls(0), NumBaseAdds(0), ImmCost(0),

871

SetupCost(0), ScaleCost(0) {}

872

873

bool operator<(const Cost &Other) const;

874

875

void Lose();

876

877

#ifndef NDEBUG

878

// Once any of the metrics loses, they must all remain losers.

879

bool isValid() {

880

return ((NumRegs | AddRecCost | NumIVMuls | NumBaseAdds

881

| ImmCost | SetupCost | ScaleCost) != ~0u)

882

|| ((NumRegs & AddRecCost & NumIVMuls & NumBaseAdds

883

& ImmCost & SetupCost & ScaleCost) == ~0u);

884

}

885

#endif

886

887

bool isLoser() {

888

assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 888, __PRETTY_FUNCTION__));

889

return NumRegs == ~0u;

890

}

891

892

void RateFormula(const TargetTransformInfo &TTI,

893

const Formula &F,

894

SmallPtrSetImpl<const SCEV *> &Regs,

895

const DenseSet<const SCEV *> &VisitedRegs,

896

const Loop *L,

897

const SmallVectorImpl<int64_t> &Offsets,

898

ScalarEvolution &SE, DominatorTree &DT,

899

const LSRUse &LU,

900

SmallPtrSetImpl<const SCEV *> *LoserRegs = nullptr);

901

902

void print(raw_ostream &OS) const;

903

void dump() const;

904

905

private:

906

void RateRegister(const SCEV *Reg,

907

SmallPtrSetImpl<const SCEV *> &Regs,

908

const Loop *L,

909

ScalarEvolution &SE, DominatorTree &DT);

910

void RatePrimaryRegister(const SCEV *Reg,

911

SmallPtrSetImpl<const SCEV *> &Regs,

912

const Loop *L,

913

ScalarEvolution &SE, DominatorTree &DT,

914

SmallPtrSetImpl<const SCEV *> *LoserRegs);

915

};

916

917

}

918

919

/// RateRegister - Tally up interesting quantities from the given register.

920

void Cost::RateRegister(const SCEV *Reg,

921

SmallPtrSetImpl<const SCEV *> &Regs,

922

const Loop *L,

923

ScalarEvolution &SE, DominatorTree &DT) {

924

if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg)) {

925

// If this is an addrec for another loop, don't second-guess its addrec phi

926

// nodes. LSR isn't currently smart enough to reason about more than one

927

// loop at a time. LSR has already run on inner loops, will not run on outer

928

// loops, and cannot be expected to change sibling loops.

929

if (AR->getLoop() != L) {

930

// If the AddRec exists, consider it's register free and leave it alone.

931

if (isExistingPhi(AR, SE))

932

return;

933

934

// Otherwise, do not consider this formula at all.

935

Lose();

936

return;

937

}

938

AddRecCost += 1; /// TODO: This should be a function of the stride.

939

940

// Add the step value register, if it needs one.

941

// TODO: The non-affine case isn't precisely modeled here.

942

if (!AR->isAffine() || !isa<SCEVConstant>(AR->getOperand(1))) {

943

if (!Regs.count(AR->getOperand(1))) {

944

RateRegister(AR->getOperand(1), Regs, L, SE, DT);

945

if (isLoser())

946

return;

947

}

948

}

949

}

950

++NumRegs;

951

952

// Rough heuristic; favor registers which don't require extra setup

953

// instructions in the preheader.

954

if (!isa<SCEVUnknown>(Reg) &&

955

!isa<SCEVConstant>(Reg) &&

956

!(isa<SCEVAddRecExpr>(Reg) &&

957

(isa<SCEVUnknown>(cast<SCEVAddRecExpr>(Reg)->getStart()) ||

958

isa<SCEVConstant>(cast<SCEVAddRecExpr>(Reg)->getStart()))))

959

++SetupCost;

960

961

NumIVMuls += isa<SCEVMulExpr>(Reg) &&

962

SE.hasComputableLoopEvolution(Reg, L);

963

}

964

965

/// RatePrimaryRegister - Record this register in the set. If we haven't seen it

966

/// before, rate it. Optional LoserRegs provides a way to declare any formula

967

/// that refers to one of those regs an instant loser.

968

void Cost::RatePrimaryRegister(const SCEV *Reg,

969

SmallPtrSetImpl<const SCEV *> &Regs,

970

const Loop *L,

971

ScalarEvolution &SE, DominatorTree &DT,

972

SmallPtrSetImpl<const SCEV *> *LoserRegs) {

973

if (LoserRegs && LoserRegs->count(Reg)) {

974

Lose();

975

return;

976

}

977

if (Regs.insert(Reg).second) {

978

RateRegister(Reg, Regs, L, SE, DT);

979

if (LoserRegs && isLoser())

980

LoserRegs->insert(Reg);

981

}

982

}

983

984

void Cost::RateFormula(const TargetTransformInfo &TTI,

985

const Formula &F,

986

SmallPtrSetImpl<const SCEV *> &Regs,

987

const DenseSet<const SCEV *> &VisitedRegs,

988

const Loop *L,

989

const SmallVectorImpl<int64_t> &Offsets,

990

ScalarEvolution &SE, DominatorTree &DT,

991

const LSRUse &LU,

992

SmallPtrSetImpl<const SCEV *> *LoserRegs) {

993

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 993, __PRETTY_FUNCTION__));

994

// Tally up the registers.

995

if (const SCEV *ScaledReg = F.ScaledReg) {

996

if (VisitedRegs.count(ScaledReg)) {

997

Lose();

998

return;

999

}

1000

RatePrimaryRegister(ScaledReg, Regs, L, SE, DT, LoserRegs);

1001

if (isLoser())

1002

return;

1003

}

1004

for (SmallVectorImpl<const SCEV *>::const_iterator I = F.BaseRegs.begin(),

1005

E = F.BaseRegs.end(); I != E; ++I) {

1006

const SCEV *BaseReg = *I;

1007

if (VisitedRegs.count(BaseReg)) {

1008

Lose();

1009

return;

1010

}

1011

RatePrimaryRegister(BaseReg, Regs, L, SE, DT, LoserRegs);

1012

if (isLoser())

1013

return;

1014

}

1015

1016

// Determine how many (unfolded) adds we'll need inside the loop.

1017

size_t NumBaseParts = F.getNumRegs();

1018

if (NumBaseParts > 1)

1019

// Do not count the base and a possible second register if the target

1020

// allows to fold 2 registers.

1021

NumBaseAdds +=

1022

NumBaseParts - (1 + (F.Scale && isAMCompletelyFolded(TTI, LU, F)));

1023

NumBaseAdds += (F.UnfoldedOffset != 0);

1024

1025

// Accumulate non-free scaling amounts.

1026

ScaleCost += getScalingFactorCost(TTI, LU, F);

1027

1028

// Tally up the non-zero immediates.

1029

for (SmallVectorImpl<int64_t>::const_iterator I = Offsets.begin(),

1030

E = Offsets.end(); I != E; ++I) {

1031

int64_t Offset = (uint64_t)*I + F.BaseOffset;

1032

if (F.BaseGV)

1033

ImmCost += 64; // Handle symbolic values conservatively.

1034

// TODO: This should probably be the pointer size.

1035

else if (Offset != 0)

1036

ImmCost += APInt(64, Offset, true).getMinSignedBits();

1037

}

1038

1039

}

1040

1041

/// Lose - Set this cost to a losing value.

1042

void Cost::Lose() {

1043

NumRegs = ~0u;

1044

AddRecCost = ~0u;

1045

NumIVMuls = ~0u;

1046

NumBaseAdds = ~0u;

1047

ImmCost = ~0u;

1048

SetupCost = ~0u;

1049

ScaleCost = ~0u;

1050

}

1051

1052

/// operator< - Choose the lower cost.

1053

bool Cost::operator<(const Cost &Other) const {

1054

return std::tie(NumRegs, AddRecCost, NumIVMuls, NumBaseAdds, ScaleCost,

1055

ImmCost, SetupCost) <

1056

std::tie(Other.NumRegs, Other.AddRecCost, Other.NumIVMuls,

1057

Other.NumBaseAdds, Other.ScaleCost, Other.ImmCost,

1058

Other.SetupCost);

1059

}

1060

1061

void Cost::print(raw_ostream &OS) const {

1062

OS << NumRegs << " reg" << (NumRegs == 1 ? "" : "s");

1063

if (AddRecCost != 0)

1064

OS << ", with addrec cost " << AddRecCost;

1065

if (NumIVMuls != 0)

1066

OS << ", plus " << NumIVMuls << " IV mul" << (NumIVMuls == 1 ? "" : "s");

1067

if (NumBaseAdds != 0)

1068

OS << ", plus " << NumBaseAdds << " base add"

1069

<< (NumBaseAdds == 1 ? "" : "s");

1070

if (ScaleCost != 0)

1071

OS << ", plus " << ScaleCost << " scale cost";

1072

if (ImmCost != 0)

1073

OS << ", plus " << ImmCost << " imm cost";

1074

if (SetupCost != 0)

1075

OS << ", plus " << SetupCost << " setup cost";

1076

}

1077

1078

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

1079

void Cost::dump() const {

1080

print(errs()); errs() << '\n';

1081

}

1082

#endif

1083

1084

namespace {

1085

1086

/// LSRFixup - An operand value in an instruction which is to be replaced

1087

/// with some equivalent, possibly strength-reduced, replacement.

1088

struct LSRFixup {

1089

/// UserInst - The instruction which will be updated.

1090

Instruction *UserInst;

1091

1092

/// OperandValToReplace - The operand of the instruction which will

1093

/// be replaced. The operand may be used more than once; every instance

1094

/// will be replaced.

1095

Value *OperandValToReplace;

1096

1097

/// PostIncLoops - If this user is to use the post-incremented value of an

1098

/// induction variable, this variable is non-null and holds the loop

1099

/// associated with the induction variable.

1100

PostIncLoopSet PostIncLoops;

1101

1102

/// LUIdx - The index of the LSRUse describing the expression which

1103

/// this fixup needs, minus an offset (below).

1104

size_t LUIdx;

1105

1106

/// Offset - A constant offset to be added to the LSRUse expression.

1107

/// This allows multiple fixups to share the same LSRUse with different

1108

/// offsets, for example in an unrolled loop.

1109

int64_t Offset;

1110

1111

bool isUseFullyOutsideLoop(const Loop *L) const;

1112

1113

LSRFixup();

1114

1115

void print(raw_ostream &OS) const;

1116

void dump() const;

1117

};

1118

1119

}

1120

1121

LSRFixup::LSRFixup()

1122

: UserInst(nullptr), OperandValToReplace(nullptr), LUIdx(~size_t(0)),

1123

Offset(0) {}

1124

1125

/// isUseFullyOutsideLoop - Test whether this fixup always uses its

1126

/// value outside of the given loop.

1127

bool LSRFixup::isUseFullyOutsideLoop(const Loop *L) const {

1128

// PHI nodes use their value in their incoming blocks.

1129

if (const PHINode *PN = dyn_cast<PHINode>(UserInst)) {

1130

for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)

1131

if (PN->getIncomingValue(i) == OperandValToReplace &&

1132

L->contains(PN->getIncomingBlock(i)))

1133

return false;

1134

return true;

1135

}

1136

1137

return !L->contains(UserInst);

1138

}

1139

1140

void LSRFixup::print(raw_ostream &OS) const {

1141

OS << "UserInst=";

1142

// Store is common and interesting enough to be worth special-casing.

1143

if (StoreInst *Store = dyn_cast<StoreInst>(UserInst)) {

1144

OS << "store ";

1145

Store->getOperand(0)->printAsOperand(OS, /*PrintType=*/false);

1146

} else if (UserInst->getType()->isVoidTy())

1147

OS << UserInst->getOpcodeName();

1148

else

1149

UserInst->printAsOperand(OS, /*PrintType=*/false);

1150

1151

OS << ", OperandValToReplace=";

1152

OperandValToReplace->printAsOperand(OS, /*PrintType=*/false);

1153

1154

for (PostIncLoopSet::const_iterator I = PostIncLoops.begin(),

1155

E = PostIncLoops.end(); I != E; ++I) {

1156

OS << ", PostIncLoop=";

1157

(*I)->getHeader()->printAsOperand(OS, /*PrintType=*/false);

1158

}

1159

1160

if (LUIdx != ~size_t(0))

1161

OS << ", LUIdx=" << LUIdx;

1162

1163

if (Offset != 0)

1164

OS << ", Offset=" << Offset;

1165

}

1166

1167

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

1168

void LSRFixup::dump() const {

1169

print(errs()); errs() << '\n';

1170

}

1171

#endif

1172

1173

namespace {

1174

1175

/// UniquifierDenseMapInfo - A DenseMapInfo implementation for holding

1176

/// DenseMaps and DenseSets of sorted SmallVectors of const SCEV*.

1177

struct UniquifierDenseMapInfo {

1178

static SmallVector<const SCEV *, 4> getEmptyKey() {

1179

SmallVector<const SCEV *, 4> V;

1180

V.push_back(reinterpret_cast<const SCEV *>(-1));

1181

return V;

1182

}

1183

1184

static SmallVector<const SCEV *, 4> getTombstoneKey() {

1185

SmallVector<const SCEV *, 4> V;

1186

V.push_back(reinterpret_cast<const SCEV *>(-2));

1187

return V;

1188

}

1189

1190

static unsigned getHashValue(const SmallVector<const SCEV *, 4> &V) {

1191

return static_cast<unsigned>(hash_combine_range(V.begin(), V.end()));

1192

}

1193

1194

static bool isEqual(const SmallVector<const SCEV *, 4> &LHS,

1195

const SmallVector<const SCEV *, 4> &RHS) {

1196

return LHS == RHS;

1197

}

1198

};

1199

1200

/// LSRUse - This class holds the state that LSR keeps for each use in

1201

/// IVUsers, as well as uses invented by LSR itself. It includes information

1202

/// about what kinds of things can be folded into the user, information about

1203

/// the user itself, and information about how the use may be satisfied.

1204

/// TODO: Represent multiple users of the same expression in common?

1205

class LSRUse {

1206

DenseSet<SmallVector<const SCEV *, 4>, UniquifierDenseMapInfo> Uniquifier;

1207

1208

public:

1209

/// KindType - An enum for a kind of use, indicating what types of

1210

/// scaled and immediate operands it might support.

1211

enum KindType {

1212

Basic, ///< A normal use, with no folding.

1213

Special, ///< A special case of basic, allowing -1 scales.

1214

Address, ///< An address use; folding according to TargetLowering

1215

ICmpZero ///< An equality icmp with both operands folded into one.

1216

// TODO: Add a generic icmp too?

1217

};

1218

1219

typedef PointerIntPair<const SCEV *, 2, KindType> SCEVUseKindPair;

1220

1221

KindType Kind;

1222

Type *AccessTy;

1223

1224

SmallVector<int64_t, 8> Offsets;

1225

int64_t MinOffset;

1226

int64_t MaxOffset;

1227

1228

/// AllFixupsOutsideLoop - This records whether all of the fixups using this

1229

/// LSRUse are outside of the loop, in which case some special-case heuristics

1230

/// may be used.

1231

bool AllFixupsOutsideLoop;

1232

1233

/// RigidFormula is set to true to guarantee that this use will be associated

1234

/// with a single formula--the one that initially matched. Some SCEV

1235

/// expressions cannot be expanded. This allows LSR to consider the registers

1236

/// used by those expressions without the need to expand them later after

1237

/// changing the formula.

1238

bool RigidFormula;

1239

1240

/// WidestFixupType - This records the widest use type for any fixup using

1241

/// this LSRUse. FindUseWithSimilarFormula can't consider uses with different

1242

/// max fixup widths to be equivalent, because the narrower one may be relying

1243

/// on the implicit truncation to truncate away bogus bits.

1244

Type *WidestFixupType;

1245

1246

/// Formulae - A list of ways to build a value that can satisfy this user.

1247

/// After the list is populated, one of these is selected heuristically and

1248

/// used to formulate a replacement for OperandValToReplace in UserInst.

1249

SmallVector<Formula, 12> Formulae;

1250

1251

/// Regs - The set of register candidates used by all formulae in this LSRUse.

1252

SmallPtrSet<const SCEV *, 4> Regs;

1253

1254

LSRUse(KindType K, Type *T) : Kind(K), AccessTy(T),

1255

MinOffset(INT64_MAX(9223372036854775807L)),

1256

MaxOffset(INT64_MIN(-9223372036854775807L -1)),

1257

AllFixupsOutsideLoop(true),

1258

RigidFormula(false),

1259

WidestFixupType(nullptr) {}

1260

1261

bool HasFormulaWithSameRegs(const Formula &F) const;

1262

bool InsertFormula(const Formula &F);

1263

void DeleteFormula(Formula &F);

1264

void RecomputeRegs(size_t LUIdx, RegUseTracker &Reguses);

1265

1266

void print(raw_ostream &OS) const;

1267

void dump() const;

1268

};

1269

1270

}

1271

1272

/// HasFormula - Test whether this use as a formula which has the same

1273

/// registers as the given formula.

1274

bool LSRUse::HasFormulaWithSameRegs(const Formula &F) const {

1275

SmallVector<const SCEV *, 4> Key = F.BaseRegs;

1276

if (F.ScaledReg) Key.push_back(F.ScaledReg);

1277

// Unstable sort by host order ok, because this is only used for uniquifying.

1278

std::sort(Key.begin(), Key.end());

1279

return Uniquifier.count(Key);

1280

}

1281

1282

/// InsertFormula - If the given formula has not yet been inserted, add it to

1283

/// the list, and return true. Return false otherwise.

1284

/// The formula must be in canonical form.

1285

bool LSRUse::InsertFormula(const Formula &F) {

1286

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1286, __PRETTY_FUNCTION__));

1287

1288

if (!Formulae.empty() && RigidFormula)

1289

return false;

1290

1291

SmallVector<const SCEV *, 4> Key = F.BaseRegs;

1292

if (F.ScaledReg) Key.push_back(F.ScaledReg);

1293

// Unstable sort by host order ok, because this is only used for uniquifying.

1294

std::sort(Key.begin(), Key.end());

1295

1296

if (!Uniquifier.insert(Key).second)

1297

return false;

1298

1299

// Using a register to hold the value of 0 is not profitable.

1300

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1301, __PRETTY_FUNCTION__))

1301

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1301, __PRETTY_FUNCTION__));

1302

#ifndef NDEBUG

1303

for (SmallVectorImpl<const SCEV *>::const_iterator I =

1304

F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I)

1305

assert(!(*I)->isZero() && "Zero allocated in a base register!")((!(*I)->isZero() && "Zero allocated in a base register!"
) ? static_cast<void> (0) : __assert_fail ("!(*I)->isZero() && \"Zero allocated in a base register!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1305, __PRETTY_FUNCTION__));

1306

#endif

1307

1308

// Add the formula to the list.

1309

Formulae.push_back(F);

1310

1311

// Record registers now being used by this use.

1312

Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end());

1313

if (F.ScaledReg)

1314

Regs.insert(F.ScaledReg);

1315

1316

return true;

1317

}

1318

1319

/// DeleteFormula - Remove the given formula from this use's list.

1320

void LSRUse::DeleteFormula(Formula &F) {

1321

if (&F != &Formulae.back())

1322

std::swap(F, Formulae.back());

1323

Formulae.pop_back();

1324

}

1325

1326

/// RecomputeRegs - Recompute the Regs field, and update RegUses.

1327

void LSRUse::RecomputeRegs(size_t LUIdx, RegUseTracker &RegUses) {

1328

// Now that we've filtered out some formulae, recompute the Regs set.

1329

SmallPtrSet<const SCEV *, 4> OldRegs = std::move(Regs);

1330

Regs.clear();

1331

for (const Formula &F : Formulae) {

1332

if (F.ScaledReg) Regs.insert(F.ScaledReg);

1333

Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end());

1334

}

1335

1336

// Update the RegTracker.

1337

for (const SCEV *S : OldRegs)

1338

if (!Regs.count(S))

1339

RegUses.DropRegister(S, LUIdx);

1340

}

1341

1342

void LSRUse::print(raw_ostream &OS) const {

1343

OS << "LSR Use: Kind=";

1344

switch (Kind) {

1345

case Basic: OS << "Basic"; break;

1346

case Special: OS << "Special"; break;

1347

case ICmpZero: OS << "ICmpZero"; break;

1348

case Address:

1349

OS << "Address of ";

1350

if (AccessTy->isPointerTy())

1351

OS << "pointer"; // the full pointer type could be really verbose

1352

else

1353

OS << *AccessTy;

1354

}

1355

1356

OS << ", Offsets={";

1357

for (SmallVectorImpl<int64_t>::const_iterator I = Offsets.begin(),

1358

E = Offsets.end(); I != E; ++I) {

1359

OS << *I;

1360

if (std::next(I) != E)

1361

OS << ',';

1362

}

1363

OS << '}';

1364

1365

if (AllFixupsOutsideLoop)

1366

OS << ", all-fixups-outside-loop";

1367

1368

if (WidestFixupType)

1369

OS << ", widest fixup type: " << *WidestFixupType;

1370

}

1371

1372

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

1373

void LSRUse::dump() const {

1374

print(errs()); errs() << '\n';

1375

}

1376

#endif

1377

1378

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

1379

LSRUse::KindType Kind, Type *AccessTy,

1380

GlobalValue *BaseGV, int64_t BaseOffset,

1381

bool HasBaseReg, int64_t Scale) {

1382

switch (Kind) {

1383

case LSRUse::Address:

1384

return TTI.isLegalAddressingMode(AccessTy, BaseGV, BaseOffset, HasBaseReg, Scale);

1385

1386

case LSRUse::ICmpZero:

1387

// There's not even a target hook for querying whether it would be legal to

1388

// fold a GV into an ICmp.

1389

if (BaseGV)

1390

return false;

1391

1392

// ICmp only has two operands; don't allow more than two non-trivial parts.

1393

if (Scale != 0 && HasBaseReg && BaseOffset != 0)

1394

return false;

1395

1396

// ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale by

1397

// putting the scaled register in the other operand of the icmp.

1398

if (Scale != 0 && Scale != -1)

1399

return false;

1400

1401

// If we have low-level target information, ask the target if it can fold an

1402

// integer immediate on an icmp.

1403

if (BaseOffset != 0) {

1404

// We have one of:

1405

// ICmpZero BaseReg + BaseOffset => ICmp BaseReg, -BaseOffset

1406

// ICmpZero -1*ScaleReg + BaseOffset => ICmp ScaleReg, BaseOffset

1407

// Offs is the ICmp immediate.

1408

if (Scale == 0)

1409

// The cast does the right thing with INT64_MIN.

1410

BaseOffset = -(uint64_t)BaseOffset;

1411

return TTI.isLegalICmpImmediate(BaseOffset);

1412

}

1413

1414

// ICmpZero BaseReg + -1*ScaleReg => ICmp BaseReg, ScaleReg

1415

return true;

1416

1417

case LSRUse::Basic:

1418

// Only handle single-register values.

1419

return !BaseGV && Scale == 0 && BaseOffset == 0;

1420

1421

case LSRUse::Special:

1422

// Special case Basic to handle -1 scales.

1423

return !BaseGV && (Scale == 0 || Scale == -1) && BaseOffset == 0;

1424

}

1425

1426

llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1426);

1427

}

1428

1429

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

1430

int64_t MinOffset, int64_t MaxOffset,

1431

LSRUse::KindType Kind, Type *AccessTy,

1432

GlobalValue *BaseGV, int64_t BaseOffset,

1433

bool HasBaseReg, int64_t Scale) {

1434

// Check for overflow.

1435

if (((int64_t)((uint64_t)BaseOffset + MinOffset) > BaseOffset) !=

1436

(MinOffset > 0))

1437

return false;

1438

MinOffset = (uint64_t)BaseOffset + MinOffset;

1439

if (((int64_t)((uint64_t)BaseOffset + MaxOffset) > BaseOffset) !=

1440

(MaxOffset > 0))

1441

return false;

1442

MaxOffset = (uint64_t)BaseOffset + MaxOffset;

1443

1444

return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MinOffset,

1445

HasBaseReg, Scale) &&

1446

isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MaxOffset,

1447

HasBaseReg, Scale);

1448

}

1449

1450

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

1451

int64_t MinOffset, int64_t MaxOffset,

1452

LSRUse::KindType Kind, Type *AccessTy,

1453

const Formula &F) {

1454

// For the purpose of isAMCompletelyFolded either having a canonical formula

1455

// or a scale not equal to zero is correct.

1456

// Problems may arise from non canonical formulae having a scale == 0.

1457

// Strictly speaking it would best to just rely on canonical formulae.

1458

// However, when we generate the scaled formulae, we first check that the

1459

// scaling factor is profitable before computing the actual ScaledReg for

1460

// compile time sake.

1461

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1461, __PRETTY_FUNCTION__));

1462

return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy,

1463

F.BaseGV, F.BaseOffset, F.HasBaseReg, F.Scale);

1464

}

1465

1466

/// isLegalUse - Test whether we know how to expand the current formula.

1467

static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset,

1468

int64_t MaxOffset, LSRUse::KindType Kind, Type *AccessTy,

1469

GlobalValue *BaseGV, int64_t BaseOffset, bool HasBaseReg,

1470

int64_t Scale) {

1471

// We know how to expand completely foldable formulae.

1472

return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV,

1473

BaseOffset, HasBaseReg, Scale) ||

1474

// Or formulae that use a base register produced by a sum of base

1475

// registers.

1476

(Scale == 1 &&

1477

isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy,

1478

BaseGV, BaseOffset, true, 0));

1479

}

1480

1481

static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset,

1482

int64_t MaxOffset, LSRUse::KindType Kind, Type *AccessTy,

1483

const Formula &F) {

1484

return isLegalUse(TTI, MinOffset, MaxOffset, Kind, AccessTy, F.BaseGV,

1485

F.BaseOffset, F.HasBaseReg, F.Scale);

1486

}

1487

1488

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

1489

const LSRUse &LU, const Formula &F) {

1490

return isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,

1491

LU.AccessTy, F.BaseGV, F.BaseOffset, F.HasBaseReg,

1492

F.Scale);

1493

}

1494

1495

static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,

1496

const LSRUse &LU, const Formula &F) {

1497

if (!F.Scale)

1498

return 0;

1499

1500

// If the use is not completely folded in that instruction, we will have to

1501

// pay an extra cost only for scale != 1.

1502

if (!isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,

1503

LU.AccessTy, F))

1504

return F.Scale != 1;

1505

1506

switch (LU.Kind) {

1507

case LSRUse::Address: {

1508

// Check the scaling factor cost with both the min and max offsets.

1509

int ScaleCostMinOffset =

1510

TTI.getScalingFactorCost(LU.AccessTy, F.BaseGV,

1511

F.BaseOffset + LU.MinOffset,

1512

F.HasBaseReg, F.Scale);

1513

int ScaleCostMaxOffset =

1514

TTI.getScalingFactorCost(LU.AccessTy, F.BaseGV,

1515

F.BaseOffset + LU.MaxOffset,

1516

F.HasBaseReg, F.Scale);

1517

1518

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1519, __PRETTY_FUNCTION__))

1519

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1519, __PRETTY_FUNCTION__));

1520

return std::max(ScaleCostMinOffset, ScaleCostMaxOffset);

1521

}

1522

case LSRUse::ICmpZero:

1523

case LSRUse::Basic:

1524

case LSRUse::Special:

1525

// The use is completely folded, i.e., everything is folded into the

1526

// instruction.

1527

return 0;

1528

}

1529

1530

1531

}

1532

1533

static bool isAlwaysFoldable(const TargetTransformInfo &TTI,

1534

LSRUse::KindType Kind, Type *AccessTy,

1535

GlobalValue *BaseGV, int64_t BaseOffset,

1536

bool HasBaseReg) {

1537

// Fast-path: zero is always foldable.

1538

if (BaseOffset == 0 && !BaseGV) return true;

1539

1540

// Conservatively, create an address with an immediate and a

1541

// base and a scale.

1542

int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1;

1543

1544

// Canonicalize a scale of 1 to a base register if the formula doesn't

1545

// already have a base register.

1546

if (!HasBaseReg && Scale == 1) {

1547

Scale = 0;

1548

HasBaseReg = true;

1549

}

1550

1551

return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, BaseOffset,

1552

HasBaseReg, Scale);

1553

}

1554

1555

static bool isAlwaysFoldable(const TargetTransformInfo &TTI,

1556

ScalarEvolution &SE, int64_t MinOffset,

1557

int64_t MaxOffset, LSRUse::KindType Kind,

1558

Type *AccessTy, const SCEV *S, bool HasBaseReg) {

1559

// Fast-path: zero is always foldable.

1560

if (S->isZero()) return true;

1561

1562

// Conservatively, create an address with an immediate and a

1563

// base and a scale.

1564

int64_t BaseOffset = ExtractImmediate(S, SE);

1565

GlobalValue *BaseGV = ExtractSymbol(S, SE);

1566

1567

// If there's anything else involved, it's not foldable.

1568

if (!S->isZero()) return false;

1569

1570

// Fast-path: zero is always foldable.

1571

if (BaseOffset == 0 && !BaseGV) return true;

1572

1573

// Conservatively, create an address with an immediate and a

1574

// base and a scale.

1575

int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1;

1576

1577

return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV,

1578

BaseOffset, HasBaseReg, Scale);

1579

}

1580

1581

namespace {

1582

1583

/// IVInc - An individual increment in a Chain of IV increments.

1584

/// Relate an IV user to an expression that computes the IV it uses from the IV

1585

/// used by the previous link in the Chain.

1586

///

1587

/// For the head of a chain, IncExpr holds the absolute SCEV expression for the

1588

/// original IVOperand. The head of the chain's IVOperand is only valid during

1589

/// chain collection, before LSR replaces IV users. During chain generation,

1590

/// IncExpr can be used to find the new IVOperand that computes the same

1591

/// expression.

1592

struct IVInc {

1593

Instruction *UserInst;

1594

Value* IVOperand;

1595

const SCEV *IncExpr;

1596

1597

IVInc(Instruction *U, Value *O, const SCEV *E):

1598

UserInst(U), IVOperand(O), IncExpr(E) {}

1599

};

1600

1601

// IVChain - The list of IV increments in program order.

1602

// We typically add the head of a chain without finding subsequent links.

1603

struct IVChain {

1604

SmallVector<IVInc,1> Incs;

1605

const SCEV *ExprBase;

1606

1607

IVChain() : ExprBase(nullptr) {}

1608

1609

IVChain(const IVInc &Head, const SCEV *Base)

1610

: Incs(1, Head), ExprBase(Base) {}

1611

1612

typedef SmallVectorImpl<IVInc>::const_iterator const_iterator;

1613

1614

// begin - return the first increment in the chain.

1615

const_iterator begin() const {

1616

assert(!Incs.empty())((!Incs.empty()) ? static_cast<void> (0) : __assert_fail
("!Incs.empty()", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1616, __PRETTY_FUNCTION__));

1617

return std::next(Incs.begin());

1618

}

1619

const_iterator end() const {

1620

return Incs.end();

1621

}

1622

1623

// hasIncs - Returns true if this chain contains any increments.

1624

bool hasIncs() const { return Incs.size() >= 2; }

1625

1626

// add - Add an IVInc to the end of this chain.

1627

void add(const IVInc &X) { Incs.push_back(X); }

1628

1629

// tailUserInst - Returns the last UserInst in the chain.

1630

Instruction *tailUserInst() const { return Incs.back().UserInst; }

1631

1632

// isProfitableIncrement - Returns true if IncExpr can be profitably added to

1633

// this chain.

1634

bool isProfitableIncrement(const SCEV *OperExpr,

1635

const SCEV *IncExpr,

1636

ScalarEvolution&);

1637

};

1638

1639

/// ChainUsers - Helper for CollectChains to track multiple IV increment uses.

1640

/// Distinguish between FarUsers that definitely cross IV increments and

1641

/// NearUsers that may be used between IV increments.

1642

struct ChainUsers {

1643

SmallPtrSet<Instruction*, 4> FarUsers;

1644

SmallPtrSet<Instruction*, 4> NearUsers;

1645

};

1646

1647

/// LSRInstance - This class holds state for the main loop strength reduction

1648

/// logic.

1649

class LSRInstance {

1650

IVUsers &IU;

1651

ScalarEvolution &SE;

1652

DominatorTree &DT;

1653

LoopInfo &LI;

1654

const TargetTransformInfo &TTI;

1655

Loop *const L;

1656

bool Changed;

1657

1658

/// IVIncInsertPos - This is the insert position that the current loop's

1659

/// induction variable increment should be placed. In simple loops, this is

1660

/// the latch block's terminator. But in more complicated cases, this is a

1661

/// position which will dominate all the in-loop post-increment users.

1662

Instruction *IVIncInsertPos;

1663

1664

/// Factors - Interesting factors between use strides.

1665

SmallSetVector<int64_t, 8> Factors;

1666

1667

/// Types - Interesting use types, to facilitate truncation reuse.

1668

SmallSetVector<Type *, 4> Types;

1669

1670

/// Fixups - The list of operands which are to be replaced.

1671

SmallVector<LSRFixup, 16> Fixups;

1672

1673

/// Uses - The list of interesting uses.

1674

SmallVector<LSRUse, 16> Uses;

1675

1676

/// RegUses - Track which uses use which register candidates.

1677

RegUseTracker RegUses;

1678

1679

// Limit the number of chains to avoid quadratic behavior. We don't expect to

1680

// have more than a few IV increment chains in a loop. Missing a Chain falls

1681

// back to normal LSR behavior for those uses.

1682

static const unsigned MaxChains = 8;

1683

1684

/// IVChainVec - IV users can form a chain of IV increments.

1685

SmallVector<IVChain, MaxChains> IVChainVec;

1686

1687

/// IVIncSet - IV users that belong to profitable IVChains.

1688

SmallPtrSet<Use*, MaxChains> IVIncSet;

1689

1690

void OptimizeShadowIV();

1691

bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse);

1692

ICmpInst *OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse);

1693

void OptimizeLoopTermCond();

1694

1695

void ChainInstruction(Instruction *UserInst, Instruction *IVOper,

1696

SmallVectorImpl<ChainUsers> &ChainUsersVec);

1697

void FinalizeChain(IVChain &Chain);

1698

void CollectChains();

1699

void GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,

1700

SmallVectorImpl<WeakVH> &DeadInsts);

1701

1702

void CollectInterestingTypesAndFactors();

1703

void CollectFixupsAndInitialFormulae();

1704

1705

LSRFixup &getNewFixup() {

1706

Fixups.push_back(LSRFixup());

1707

return Fixups.back();

1708

}

1709

1710

// Support for sharing of LSRUses between LSRFixups.

1711

typedef DenseMap<LSRUse::SCEVUseKindPair, size_t> UseMapTy;

1712

UseMapTy UseMap;

1713

1714

bool reconcileNewOffset(LSRUse &LU, int64_t NewOffset, bool HasBaseReg,

1715

LSRUse::KindType Kind, Type *AccessTy);

1716

1717

std::pair<size_t, int64_t> getUse(const SCEV *&Expr,

1718

LSRUse::KindType Kind,

1719

Type *AccessTy);

1720

1721

void DeleteUse(LSRUse &LU, size_t LUIdx);

1722

1723

LSRUse *FindUseWithSimilarFormula(const Formula &F, const LSRUse &OrigLU);

1724

1725

void InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx);

1726

void InsertSupplementalFormula(const SCEV *S, LSRUse &LU, size_t LUIdx);

1727

void CountRegisters(const Formula &F, size_t LUIdx);

1728

bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F);

1729

1730

void CollectLoopInvariantFixupsAndFormulae();

1731

1732

void GenerateReassociations(LSRUse &LU, unsigned LUIdx, Formula Base,

1733

unsigned Depth = 0);

1734

1735

void GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,

1736

const Formula &Base, unsigned Depth,

1737

size_t Idx, bool IsScaledReg = false);

1738

void GenerateCombinations(LSRUse &LU, unsigned LUIdx, Formula Base);

1739

void GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,

1740

const Formula &Base, size_t Idx,

1741

bool IsScaledReg = false);

1742

void GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, Formula Base);

1743

void GenerateConstantOffsetsImpl(LSRUse &LU, unsigned LUIdx,

1744

const Formula &Base,

1745

const SmallVectorImpl<int64_t> &Worklist,

1746

size_t Idx, bool IsScaledReg = false);

1747

void GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, Formula Base);

1748

void GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, Formula Base);

1749

void GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base);

1750

void GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base);

1751

void GenerateCrossUseConstantOffsets();

1752

void GenerateAllReuseFormulae();

1753

1754

void FilterOutUndesirableDedicatedRegisters();

1755

1756

size_t EstimateSearchSpaceComplexity() const;

1757

void NarrowSearchSpaceByDetectingSupersets();

1758

void NarrowSearchSpaceByCollapsingUnrolledCode();

1759

void NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();

1760

void NarrowSearchSpaceByPickingWinnerRegs();

1761

void NarrowSearchSpaceUsingHeuristics();

1762

1763

void SolveRecurse(SmallVectorImpl<const Formula *> &Solution,

1764

Cost &SolutionCost,

1765

SmallVectorImpl<const Formula *> &Workspace,

1766

const Cost &CurCost,

1767

const SmallPtrSet<const SCEV *, 16> &CurRegs,

1768

DenseSet<const SCEV *> &VisitedRegs) const;

1769

void Solve(SmallVectorImpl<const Formula *> &Solution) const;

1770

1771

BasicBlock::iterator

1772

HoistInsertPosition(BasicBlock::iterator IP,

1773

const SmallVectorImpl<Instruction *> &Inputs) const;

1774

BasicBlock::iterator

1775

AdjustInsertPositionForExpand(BasicBlock::iterator IP,

1776

const LSRFixup &LF,

1777

const LSRUse &LU,

1778

SCEVExpander &Rewriter) const;

1779

1780

Value *Expand(const LSRFixup &LF,

1781

const Formula &F,

1782

BasicBlock::iterator IP,

1783

SCEVExpander &Rewriter,

1784

SmallVectorImpl<WeakVH> &DeadInsts) const;

1785

void RewriteForPHI(PHINode *PN, const LSRFixup &LF,

1786

const Formula &F,

1787

SCEVExpander &Rewriter,

1788

SmallVectorImpl<WeakVH> &DeadInsts,

1789

Pass *P) const;

1790

void Rewrite(const LSRFixup &LF,

1791

const Formula &F,

1792

SCEVExpander &Rewriter,

1793

SmallVectorImpl<WeakVH> &DeadInsts,

1794

Pass *P) const;

1795

void ImplementSolution(const SmallVectorImpl<const Formula *> &Solution,

1796

Pass *P);

1797

1798

public:

1799

LSRInstance(Loop *L, Pass *P);

1800

1801

bool getChanged() const { return Changed; }

1802

1803

void print_factors_and_types(raw_ostream &OS) const;

1804

void print_fixups(raw_ostream &OS) const;

1805

void print_uses(raw_ostream &OS) const;

1806

void print(raw_ostream &OS) const;

1807

void dump() const;

1808

};

1809

1810

}

1811

1812

/// OptimizeShadowIV - If IV is used in a int-to-float cast

1813

/// inside the loop then try to eliminate the cast operation.

1814

void LSRInstance::OptimizeShadowIV() {

1815

const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);

1816

if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))

1817

return;

1818

1819

for (IVUsers::const_iterator UI = IU.begin(), E = IU.end();

1820

UI != E; /* empty */) {

1821

IVUsers::const_iterator CandidateUI = UI;

1822

++UI;

1823

Instruction *ShadowUse = CandidateUI->getUser();

1824

Type *DestTy = nullptr;

1825

bool IsSigned = false;

1826

1827

/* If shadow use is a int->float cast then insert a second IV

1828

to eliminate this cast.

1829

1830

for (unsigned i = 0; i < n; ++i)

1831

foo((double)i);

1832

1833

is transformed into

1834

1835

double d = 0.0;

1836

for (unsigned i = 0; i < n; ++i, ++d)

1837

foo(d);

1838

1839

if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser())) {

1840

IsSigned = false;

1841

DestTy = UCast->getDestTy();

1842

}

1843

else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser())) {

1844

IsSigned = true;

1845

DestTy = SCast->getDestTy();

1846

}

1847

if (!DestTy) continue;

1848

1849

// If target does not support DestTy natively then do not apply

1850

// this transformation.

1851

if (!TTI.isTypeLegal(DestTy)) continue;

1852

1853

PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0));

1854

if (!PH) continue;

1855

if (PH->getNumIncomingValues() != 2) continue;

1856

1857

Type *SrcTy = PH->getType();

1858

int Mantissa = DestTy->getFPMantissaWidth();

1859

if (Mantissa == -1) continue;

1860

if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa)

1861

continue;

1862

1863

unsigned Entry, Latch;

1864

if (PH->getIncomingBlock(0) == L->getLoopPreheader()) {

1865

Entry = 0;

1866

Latch = 1;

1867

} else {

1868

Entry = 1;

1869

Latch = 0;

1870

}

1871

1872

ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));

1873

if (!Init) continue;

1874

Constant *NewInit = ConstantFP::get(DestTy, IsSigned ?

1875

(double)Init->getSExtValue() :

1876

(double)Init->getZExtValue());

1877

1878

BinaryOperator *Incr =

1879

dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));

1880

if (!Incr) continue;

1881

if (Incr->getOpcode() != Instruction::Add

1882

&& Incr->getOpcode() != Instruction::Sub)

1883

continue;

1884

1885

/* Initialize new IV, double d = 0.0 in above example. */

1886

ConstantInt *C = nullptr;

1887

if (Incr->getOperand(0) == PH)

1888

C = dyn_cast<ConstantInt>(Incr->getOperand(1));

1889

else if (Incr->getOperand(1) == PH)

1890

C = dyn_cast<ConstantInt>(Incr->getOperand(0));

1891

else

1892

continue;

1893

1894

if (!C) continue;

1895

1896

// Ignore negative constants, as the code below doesn't handle them

1897

// correctly. TODO: Remove this restriction.

1898

if (!C->getValue().isStrictlyPositive()) continue;

1899

1900

/* Add new PHINode. */

1901

PHINode *NewPH = PHINode::Create(DestTy, 2, "IV.S.", PH);

1902

1903

/* create new increment. '++d' in above example. */

1904

Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue());

1905

BinaryOperator *NewIncr =

1906

BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ?

1907

Instruction::FAdd : Instruction::FSub,

1908

NewPH, CFP, "IV.S.next.", Incr);

1909

1910

NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry));

1911

NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch));

1912

1913

/* Remove cast operation */

1914

ShadowUse->replaceAllUsesWith(NewPH);

1915

ShadowUse->eraseFromParent();

1916

Changed = true;

1917

break;

1918

}

1919

}

1920

1921

/// FindIVUserForCond - If Cond has an operand that is an expression of an IV,

1922

/// set the IV user and stride information and return true, otherwise return

1923

/// false.

1924

bool LSRInstance::FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse) {

1925

for (IVUsers::iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI)

1926

if (UI->getUser() == Cond) {

1927

// NOTE: we could handle setcc instructions with multiple uses here, but

1928

// InstCombine does it as well for simple uses, it's not clear that it

1929

// occurs enough in real life to handle.

1930

CondUse = UI;

1931

return true;

1932

}

1933

return false;

1934

}

1935

1936

/// OptimizeMax - Rewrite the loop's terminating condition if it uses

1937

/// a max computation.

1938

///

1939

/// This is a narrow solution to a specific, but acute, problem. For loops

1940

/// like this:

1941

///

1942

/// i = 0;

1943

/// do {

1944

/// p[i] = 0.0;

1945

/// } while (++i < n);

1946

///

1947

/// the trip count isn't just 'n', because 'n' might not be positive. And

1948

/// unfortunately this can come up even for loops where the user didn't use

1949

/// a C do-while loop. For example, seemingly well-behaved top-test loops

1950

/// will commonly be lowered like this:

1951

1952

/// if (n > 0) {

1953

/// i = 0;

1954

/// do {

1955

/// p[i] = 0.0;

1956

/// } while (++i < n);

1957

/// }

1958

///

1959

/// and then it's possible for subsequent optimization to obscure the if

1960

/// test in such a way that indvars can't find it.

1961

///

1962

/// When indvars can't find the if test in loops like this, it creates a

1963

/// max expression, which allows it to give the loop a canonical

1964

/// induction variable:

1965

///

1966

/// i = 0;

1967

/// max = n < 1 ? 1 : n;

1968

/// do {

1969

/// p[i] = 0.0;

1970

/// } while (++i != max);

1971

///

1972

/// Canonical induction variables are necessary because the loop passes

1973

/// are designed around them. The most obvious example of this is the

1974

/// LoopInfo analysis, which doesn't remember trip count values. It

1975

/// expects to be able to rediscover the trip count each time it is

1976

/// needed, and it does this using a simple analysis that only succeeds if

1977

/// the loop has a canonical induction variable.

1978

///

1979

/// However, when it comes time to generate code, the maximum operation

1980

/// can be quite costly, especially if it's inside of an outer loop.

1981

///

1982

/// This function solves this problem by detecting this type of loop and

1983

/// rewriting their conditions from ICMP_NE back to ICMP_SLT, and deleting

1984

/// the instructions for the maximum computation.

1985

///

1986

ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) {

1987

// Check that the loop matches the pattern we're looking for.

1988

if (Cond->getPredicate() != CmpInst::ICMP_EQ &&

1989

Cond->getPredicate() != CmpInst::ICMP_NE)

1990

return Cond;

1991

1992

SelectInst *Sel = dyn_cast<SelectInst>(Cond->getOperand(1));

1993

if (!Sel || !Sel->hasOneUse()) return Cond;

1994

1995

const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);

1996

if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))

1997

return Cond;

1998

const SCEV *One = SE.getConstant(BackedgeTakenCount->getType(), 1);

1999

2000

// Add one to the backedge-taken count to get the trip count.

2001

const SCEV *IterationCount = SE.getAddExpr(One, BackedgeTakenCount);

2002

if (IterationCount != SE.getSCEV(Sel)) return Cond;

2003

2004

// Check for a max calculation that matches the pattern. There's no check

2005

// for ICMP_ULE here because the comparison would be with zero, which

2006

// isn't interesting.

2007

CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;

2008

const SCEVNAryExpr *Max = nullptr;

2009

if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(BackedgeTakenCount)) {

2010

Pred = ICmpInst::ICMP_SLE;

2011

Max = S;

2012

} else if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(IterationCount)) {

2013

Pred = ICmpInst::ICMP_SLT;

2014

Max = S;

2015

} else if (const SCEVUMaxExpr *U = dyn_cast<SCEVUMaxExpr>(IterationCount)) {

2016

Pred = ICmpInst::ICMP_ULT;

2017

Max = U;

2018

} else {

2019

// No match; bail.

2020

return Cond;

2021

}

2022

2023

// To handle a max with more than two operands, this optimization would

2024

// require additional checking and setup.

2025

if (Max->getNumOperands() != 2)

2026

return Cond;

2027

2028

const SCEV *MaxLHS = Max->getOperand(0);

2029

const SCEV *MaxRHS = Max->getOperand(1);

2030

2031

// ScalarEvolution canonicalizes constants to the left. For < and >, look

2032

// for a comparison with 1. For <= and >=, a comparison with zero.

2033

if (!MaxLHS ||

2034

(ICmpInst::isTrueWhenEqual(Pred) ? !MaxLHS->isZero() : (MaxLHS != One)))

2035

return Cond;

2036

2037

// Check the relevant induction variable for conformance to

2038

// the pattern.

2039

const SCEV *IV = SE.getSCEV(Cond->getOperand(0));

2040

const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV);

2041

if (!AR || !AR->isAffine() ||

2042

AR->getStart() != One ||

2043

AR->getStepRecurrence(SE) != One)

2044

return Cond;

2045

2046

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2047, __PRETTY_FUNCTION__))

2047

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2047, __PRETTY_FUNCTION__));

2048

2049

// Check the right operand of the select, and remember it, as it will

2050

// be used in the new comparison instruction.

2051

Value *NewRHS = nullptr;

2052

if (ICmpInst::isTrueWhenEqual(Pred)) {

2053

// Look for n+1, and grab n.

2054

if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(1)))

2055

if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1)))

2056

if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS)

2057

NewRHS = BO->getOperand(0);

2058

if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(2)))

2059

if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1)))

2060

if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS)

2061

NewRHS = BO->getOperand(0);

2062

if (!NewRHS)

2063

return Cond;

2064

} else if (SE.getSCEV(Sel->getOperand(1)) == MaxRHS)

2065

NewRHS = Sel->getOperand(1);

2066

else if (SE.getSCEV(Sel->getOperand(2)) == MaxRHS)

2067

NewRHS = Sel->getOperand(2);

2068

else if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(MaxRHS))

2069

NewRHS = SU->getValue();

2070

else

2071

// Max doesn't match expected pattern.

2072

return Cond;

2073

2074

// Determine the new comparison opcode. It may be signed or unsigned,

2075

// and the original comparison may be either equality or inequality.

2076

if (Cond->getPredicate() == CmpInst::ICMP_EQ)

2077

Pred = CmpInst::getInversePredicate(Pred);

2078

2079

// Ok, everything looks ok to change the condition into an SLT or SGE and

2080

// delete the max calculation.

2081

ICmpInst *NewCond =

2082

new ICmpInst(Cond, Pred, Cond->getOperand(0), NewRHS, "scmp");

2083

2084

// Delete the max calculation instructions.

2085

Cond->replaceAllUsesWith(NewCond);

2086

CondUse->setUser(NewCond);

2087

Instruction *Cmp = cast<Instruction>(Sel->getOperand(0));

2088

Cond->eraseFromParent();

2089

Sel->eraseFromParent();

2090

if (Cmp->use_empty())

2091

Cmp->eraseFromParent();

2092

return NewCond;

2093

}

2094

2095

/// OptimizeLoopTermCond - Change loop terminating condition to use the

2096

/// postinc iv when possible.

2097

void

2098

LSRInstance::OptimizeLoopTermCond() {

2099

SmallPtrSet<Instruction *, 4> PostIncs;

2100

2101

BasicBlock *LatchBlock = L->getLoopLatch();

2102

SmallVector<BasicBlock*, 8> ExitingBlocks;

2103

L->getExitingBlocks(ExitingBlocks);

2104

2105

for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {

2106

BasicBlock *ExitingBlock = ExitingBlocks[i];

2107

2108

// Get the terminating condition for the loop if possible. If we

2109

// can, we want to change it to use a post-incremented version of its

2110

// induction variable, to allow coalescing the live ranges for the IV into

2111

// one register value.

2112

2113

BranchInst *TermBr = dyn_cast<BranchInst>(ExitingBlock->getTerminator());

2114

if (!TermBr)

2115

continue;

2116

// FIXME: Overly conservative, termination condition could be an 'or' etc..

2117

if (TermBr->isUnconditional() || !isa<ICmpInst>(TermBr->getCondition()))

2118

continue;

2119

2120

// Search IVUsesByStride to find Cond's IVUse if there is one.

2121

IVStrideUse *CondUse = nullptr;

2122

ICmpInst *Cond = cast<ICmpInst>(TermBr->getCondition());

2123

if (!FindIVUserForCond(Cond, CondUse))

2124

continue;

2125

2126

// If the trip count is computed in terms of a max (due to ScalarEvolution

2127

// being unable to find a sufficient guard, for example), change the loop

2128

// comparison to use SLT or ULT instead of NE.

2129

// One consequence of doing this now is that it disrupts the count-down

2130

// optimization. That's not always a bad thing though, because in such

2131

// cases it may still be worthwhile to avoid a max.

2132

Cond = OptimizeMax(Cond, CondUse);

2133

2134

// If this exiting block dominates the latch block, it may also use

2135

// the post-inc value if it won't be shared with other uses.

2136

// Check for dominance.

2137

if (!DT.dominates(ExitingBlock, LatchBlock))

2138

continue;

2139

2140

// Conservatively avoid trying to use the post-inc value in non-latch

2141

// exits if there may be pre-inc users in intervening blocks.

2142

if (LatchBlock != ExitingBlock)

2143

for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI)

2144

// Test if the use is reachable from the exiting block. This dominator

2145

// query is a conservative approximation of reachability.

2146

if (&*UI != CondUse &&

2147

!DT.properlyDominates(UI->getUser()->getParent(), ExitingBlock)) {

2148

// Conservatively assume there may be reuse if the quotient of their

2149

// strides could be a legal scale.

2150

const SCEV *A = IU.getStride(*CondUse, L);

2151

const SCEV *B = IU.getStride(*UI, L);

2152

if (!A || !B) continue;

2153

if (SE.getTypeSizeInBits(A->getType()) !=

2154

SE.getTypeSizeInBits(B->getType())) {

2155

if (SE.getTypeSizeInBits(A->getType()) >

2156

SE.getTypeSizeInBits(B->getType()))

2157

B = SE.getSignExtendExpr(B, A->getType());

2158

else

2159

A = SE.getSignExtendExpr(A, B->getType());

2160

}

2161

if (const SCEVConstant *D =

2162

dyn_cast_or_null<SCEVConstant>(getExactSDiv(B, A, SE))) {

2163

const ConstantInt *C = D->getValue();

2164

// Stride of one or negative one can have reuse with non-addresses.

2165

if (C->isOne() || C->isAllOnesValue())

2166

goto decline_post_inc;

2167

// Avoid weird situations.

2168

if (C->getValue().getMinSignedBits() >= 64 ||

2169

C->getValue().isMinSignedValue())

2170

goto decline_post_inc;

2171

// Check for possible scaled-address reuse.

2172

Type *AccessTy = getAccessType(UI->getUser());

2173

int64_t Scale = C->getSExtValue();

2174

if (TTI.isLegalAddressingMode(AccessTy, /*BaseGV=*/ nullptr,

2175

/*BaseOffset=*/ 0,

2176

/*HasBaseReg=*/ false, Scale))

2177

goto decline_post_inc;

2178

Scale = -Scale;

2179

if (TTI.isLegalAddressingMode(AccessTy, /*BaseGV=*/ nullptr,

2180

/*BaseOffset=*/ 0,

2181

/*HasBaseReg=*/ false, Scale))

2182

goto decline_post_inc;

2183

}

2184

}

2185

2186

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)

2187

<< *Cond << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: "
<< *Cond << '\n'; } } while (0);

2188

2189

// It's possible for the setcc instruction to be anywhere in the loop, and

2190

// possible for it to have multiple users. If it is not immediately before

2191

// the exiting block branch, move it.

2192

if (&*++BasicBlock::iterator(Cond) != TermBr) {

2193

if (Cond->hasOneUse()) {

2194

Cond->moveBefore(TermBr);

2195

} else {

2196

// Clone the terminating condition and insert into the loopend.

2197

ICmpInst *OldCond = Cond;

2198

Cond = cast<ICmpInst>(Cond->clone());

2199

Cond->setName(L->getHeader()->getName() + ".termcond");

2200

ExitingBlock->getInstList().insert(TermBr, Cond);

2201

2202

// Clone the IVUse, as the old use still exists!

2203

CondUse = &IU.AddUser(Cond, CondUse->getOperandValToReplace());

2204

TermBr->replaceUsesOfWith(OldCond, Cond);

2205

}

2206

}

2207

2208

// If we get to here, we know that we can transform the setcc instruction to

2209

// use the post-incremented version of the IV, allowing us to coalesce the

2210

// live ranges for the IV correctly.

2211

CondUse->transformToPostInc(L);

2212

Changed = true;

2213

2214

PostIncs.insert(Cond);

2215

decline_post_inc:;

2216

}

2217

2218

// Determine an insertion point for the loop induction variable increment. It

2219

// must dominate all the post-inc comparisons we just set up, and it must

2220

// dominate the loop latch edge.

2221

IVIncInsertPos = L->getLoopLatch()->getTerminator();

2222

for (Instruction *Inst : PostIncs) {

2223

BasicBlock *BB =

2224

DT.findNearestCommonDominator(IVIncInsertPos->getParent(),

2225

Inst->getParent());

2226

if (BB == Inst->getParent())

2227

IVIncInsertPos = Inst;

2228

else if (BB != IVIncInsertPos->getParent())

2229

IVIncInsertPos = BB->getTerminator();

2230

}

2231

}

2232

2233

/// reconcileNewOffset - Determine if the given use can accommodate a fixup

2234

/// at the given offset and other details. If so, update the use and

2235

/// return true.

2236

bool

2237

LSRInstance::reconcileNewOffset(LSRUse &LU, int64_t NewOffset, bool HasBaseReg,

2238

LSRUse::KindType Kind, Type *AccessTy) {

2239

int64_t NewMinOffset = LU.MinOffset;

2240

int64_t NewMaxOffset = LU.MaxOffset;

2241

Type *NewAccessTy = AccessTy;

2242

2243

// Check for a mismatched kind. It's tempting to collapse mismatched kinds to

2244

// something conservative, however this can pessimize in the case that one of

2245

// the uses will have all its uses outside the loop, for example.

2246

if (LU.Kind != Kind)

2247

return false;

2248

2249

// Check for a mismatched access type, and fall back conservatively as needed.

2250

// TODO: Be less conservative when the type is similar and can use the same

2251

// addressing modes.

2252

if (Kind == LSRUse::Address && AccessTy != LU.AccessTy)

2253

NewAccessTy = Type::getVoidTy(AccessTy->getContext());

2254

2255

// Conservatively assume HasBaseReg is true for now.

2256

if (NewOffset < LU.MinOffset) {

2257

if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr,

2258

LU.MaxOffset - NewOffset, HasBaseReg))

2259

return false;

2260

NewMinOffset = NewOffset;

2261

} else if (NewOffset > LU.MaxOffset) {

2262

if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr,

2263

NewOffset - LU.MinOffset, HasBaseReg))

2264

return false;

2265

NewMaxOffset = NewOffset;

2266

}

2267

2268

// Update the use.

2269

LU.MinOffset = NewMinOffset;

2270

LU.MaxOffset = NewMaxOffset;

2271

LU.AccessTy = NewAccessTy;

2272

if (NewOffset != LU.Offsets.back())

2273

LU.Offsets.push_back(NewOffset);

2274

return true;

2275

}

2276

2277

/// getUse - Return an LSRUse index and an offset value for a fixup which

2278

/// needs the given expression, with the given kind and optional access type.

2279

/// Either reuse an existing use or create a new one, as needed.

2280

std::pair<size_t, int64_t>

2281

LSRInstance::getUse(const SCEV *&Expr,

2282

LSRUse::KindType Kind, Type *AccessTy) {

2283

const SCEV *Copy = Expr;

2284

int64_t Offset = ExtractImmediate(Expr, SE);

2285

2286

// Basic uses can't accept any offset, for example.

2287

if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr,

2288

Offset, /*HasBaseReg=*/ true)) {

2289

Expr = Copy;

2290

Offset = 0;

2291

}

2292

2293

std::pair<UseMapTy::iterator, bool> P =

2294

UseMap.insert(std::make_pair(LSRUse::SCEVUseKindPair(Expr, Kind), 0));

2295

if (!P.second) {

2296

// A use already existed with this base.

2297

size_t LUIdx = P.first->second;

2298

LSRUse &LU = Uses[LUIdx];

2299

if (reconcileNewOffset(LU, Offset, /*HasBaseReg=*/true, Kind, AccessTy))

2300

// Reuse this use.

2301

return std::make_pair(LUIdx, Offset);

2302

}

2303

2304

// Create a new use.

2305

size_t LUIdx = Uses.size();

2306

P.first->second = LUIdx;

2307

Uses.push_back(LSRUse(Kind, AccessTy));

2308

LSRUse &LU = Uses[LUIdx];

2309

2310

// We don't need to track redundant offsets, but we don't need to go out

2311

// of our way here to avoid them.

2312

if (LU.Offsets.empty() || Offset != LU.Offsets.back())

2313

LU.Offsets.push_back(Offset);

2314

2315

LU.MinOffset = Offset;

2316

LU.MaxOffset = Offset;

2317

return std::make_pair(LUIdx, Offset);

2318

}

2319

2320

/// DeleteUse - Delete the given use from the Uses list.

2321

void LSRInstance::DeleteUse(LSRUse &LU, size_t LUIdx) {

2322

if (&LU != &Uses.back())

2323

std::swap(LU, Uses.back());

2324

Uses.pop_back();

2325

2326

// Update RegUses.

2327

RegUses.SwapAndDropUse(LUIdx, Uses.size());

2328

}

2329

2330

/// FindUseWithFormula - Look for a use distinct from OrigLU which is has

2331

/// a formula that has the same registers as the given formula.

2332

LSRUse *

2333

LSRInstance::FindUseWithSimilarFormula(const Formula &OrigF,

2334

const LSRUse &OrigLU) {

2335

// Search all uses for the formula. This could be more clever.

2336

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

2337

LSRUse &LU = Uses[LUIdx];

2338

// Check whether this use is close enough to OrigLU, to see whether it's

2339

// worthwhile looking through its formulae.

2340

// Ignore ICmpZero uses because they may contain formulae generated by

2341

// GenerateICmpZeroScales, in which case adding fixup offsets may

2342

// be invalid.

2343

if (&LU != &OrigLU &&

2344

LU.Kind != LSRUse::ICmpZero &&

2345

LU.Kind == OrigLU.Kind && OrigLU.AccessTy == LU.AccessTy &&

2346

LU.WidestFixupType == OrigLU.WidestFixupType &&

2347

LU.HasFormulaWithSameRegs(OrigF)) {

2348

// Scan through this use's formulae.

2349

for (SmallVectorImpl<Formula>::const_iterator I = LU.Formulae.begin(),

2350

E = LU.Formulae.end(); I != E; ++I) {

2351

const Formula &F = *I;

2352

// Check to see if this formula has the same registers and symbols

2353

// as OrigF.

2354

if (F.BaseRegs == OrigF.BaseRegs &&

2355

F.ScaledReg == OrigF.ScaledReg &&

2356

F.BaseGV == OrigF.BaseGV &&

2357

F.Scale == OrigF.Scale &&

2358

F.UnfoldedOffset == OrigF.UnfoldedOffset) {

2359

if (F.BaseOffset == 0)

2360

return &LU;

2361

// This is the formula where all the registers and symbols matched;

2362

// there aren't going to be any others. Since we declined it, we

2363

// can skip the rest of the formulae and proceed to the next LSRUse.

2364

break;

2365

}

2366

}

2367

}

2368

}

2369

2370

// Nothing looked good.

2371

return nullptr;

2372

}

2373

2374

void LSRInstance::CollectInterestingTypesAndFactors() {

2375

SmallSetVector<const SCEV *, 4> Strides;

2376

2377

// Collect interesting types and strides.

2378

SmallVector<const SCEV *, 4> Worklist;

2379

for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) {

2380

const SCEV *Expr = IU.getExpr(*UI);

2381

2382

// Collect interesting types.

2383

Types.insert(SE.getEffectiveSCEVType(Expr->getType()));

2384

2385

// Add strides for mentioned loops.

2386

Worklist.push_back(Expr);

2387

do {

2388

const SCEV *S = Worklist.pop_back_val();

2389

if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {

2390

if (AR->getLoop() == L)

2391

Strides.insert(AR->getStepRecurrence(SE));

2392

Worklist.push_back(AR->getStart());

2393

} else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {

2394

Worklist.append(Add->op_begin(), Add->op_end());

2395

}

2396

} while (!Worklist.empty());

2397

}

2398

2399

// Compute interesting factors from the set of interesting strides.

2400

for (SmallSetVector<const SCEV *, 4>::const_iterator

2401

I = Strides.begin(), E = Strides.end(); I != E; ++I)

2402

for (SmallSetVector<const SCEV *, 4>::const_iterator NewStrideIter =

2403

std::next(I); NewStrideIter != E; ++NewStrideIter) {

2404

const SCEV *OldStride = *I;

2405

const SCEV *NewStride = *NewStrideIter;

2406

2407

if (SE.getTypeSizeInBits(OldStride->getType()) !=

2408

SE.getTypeSizeInBits(NewStride->getType())) {

2409

if (SE.getTypeSizeInBits(OldStride->getType()) >

2410

SE.getTypeSizeInBits(NewStride->getType()))

2411

NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType());

2412

else

2413

OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType());

2414

}

2415

if (const SCEVConstant *Factor =

2416

dyn_cast_or_null<SCEVConstant>(getExactSDiv(NewStride, OldStride,

2417

SE, true))) {

2418

if (Factor->getValue()->getValue().getMinSignedBits() <= 64)

2419

Factors.insert(Factor->getValue()->getValue().getSExtValue());

2420

} else if (const SCEVConstant *Factor =

2421

dyn_cast_or_null<SCEVConstant>(getExactSDiv(OldStride,

2422

NewStride,

2423

SE, true))) {

2424

if (Factor->getValue()->getValue().getMinSignedBits() <= 64)

2425

Factors.insert(Factor->getValue()->getValue().getSExtValue());

2426

}

2427

}

2428

2429

// If all uses use the same type, don't bother looking for truncation-based

2430

// reuse.

2431

if (Types.size() == 1)

2432

Types.clear();

2433

2434

DEBUG(print_factors_and_types(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_factors_and_types(dbgs()); } } while
(0);

2435

}

2436

2437

/// findIVOperand - Helper for CollectChains that finds an IV operand (computed

2438

/// by an AddRec in this loop) within [OI,OE) or returns OE. If IVUsers mapped

2439

/// Instructions to IVStrideUses, we could partially skip this.

2440

static User::op_iterator

2441

findIVOperand(User::op_iterator OI, User::op_iterator OE,

2442

Loop *L, ScalarEvolution &SE) {

2443

for(; OI != OE; ++OI) {

2444

if (Instruction *Oper = dyn_cast<Instruction>(*OI)) {

2445

if (!SE.isSCEVable(Oper->getType()))

2446

continue;

2447

2448

if (const SCEVAddRecExpr *AR =

2449

dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Oper))) {

2450

if (AR->getLoop() == L)

2451

break;

2452

}

2453

}

2454

}

2455

return OI;

2456

}

2457

2458

/// getWideOperand - IVChain logic must consistenctly peek base TruncInst

2459

/// operands, so wrap it in a convenient helper.

2460

static Value *getWideOperand(Value *Oper) {

2461

if (TruncInst *Trunc = dyn_cast<TruncInst>(Oper))

2462

return Trunc->getOperand(0);

2463

return Oper;

2464

}

2465

2466

/// isCompatibleIVType - Return true if we allow an IV chain to include both

2467

/// types.

2468

static bool isCompatibleIVType(Value *LVal, Value *RVal) {

2469

Type *LType = LVal->getType();

2470

Type *RType = RVal->getType();

2471

return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy());

2472

}

2473

2474

/// getExprBase - Return an approximation of this SCEV expression's "base", or

2475

/// NULL for any constant. Returning the expression itself is

2476

/// conservative. Returning a deeper subexpression is more precise and valid as

2477

/// long as it isn't less complex than another subexpression. For expressions

2478

/// involving multiple unscaled values, we need to return the pointer-type

2479

/// SCEVUnknown. This avoids forming chains across objects, such as:

2480

/// PrevOper==a[i], IVOper==b[i], IVInc==b-a.

2481

///

2482

/// Since SCEVUnknown is the rightmost type, and pointers are the rightmost

2483

/// SCEVUnknown, we simply return the rightmost SCEV operand.

2484

static const SCEV *getExprBase(const SCEV *S) {

2485

switch (S->getSCEVType()) {

2486

default: // uncluding scUnknown.

2487

return S;

2488

case scConstant:

2489

return nullptr;

2490

case scTruncate:

2491

return getExprBase(cast<SCEVTruncateExpr>(S)->getOperand());

2492

case scZeroExtend:

2493

return getExprBase(cast<SCEVZeroExtendExpr>(S)->getOperand());

2494

case scSignExtend:

2495

return getExprBase(cast<SCEVSignExtendExpr>(S)->getOperand());

2496

case scAddExpr: {

2497

// Skip over scaled operands (scMulExpr) to follow add operands as long as

2498

// there's nothing more complex.

2499

// FIXME: not sure if we want to recognize negation.

2500

const SCEVAddExpr *Add = cast<SCEVAddExpr>(S);

2501

for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(Add->op_end()),

2502

E(Add->op_begin()); I != E; ++I) {

2503

const SCEV *SubExpr = *I;

2504

if (SubExpr->getSCEVType() == scAddExpr)

2505

return getExprBase(SubExpr);

2506

2507

if (SubExpr->getSCEVType() != scMulExpr)

2508

return SubExpr;

2509

}

2510

return S; // all operands are scaled, be conservative.

2511

}

2512

case scAddRecExpr:

2513

return getExprBase(cast<SCEVAddRecExpr>(S)->getStart());

2514

}

2515

}

2516

2517

/// Return true if the chain increment is profitable to expand into a loop

2518

/// invariant value, which may require its own register. A profitable chain

2519

/// increment will be an offset relative to the same base. We allow such offsets

2520

/// to potentially be used as chain increment as long as it's not obviously

2521

/// expensive to expand using real instructions.

2522

bool IVChain::isProfitableIncrement(const SCEV *OperExpr,

2523

const SCEV *IncExpr,

2524

ScalarEvolution &SE) {

2525

// Aggressively form chains when -stress-ivchain.

2526

if (StressIVChain)

2527

return true;

2528

2529

// Do not replace a constant offset from IV head with a nonconstant IV

2530

// increment.

2531

if (!isa<SCEVConstant>(IncExpr)) {

2532

const SCEV *HeadExpr = SE.getSCEV(getWideOperand(Incs[0].IVOperand));

2533

if (isa<SCEVConstant>(SE.getMinusSCEV(OperExpr, HeadExpr)))

2534

return 0;

2535

}

2536

2537

SmallPtrSet<const SCEV*, 8> Processed;

2538

return !isHighCostExpansion(IncExpr, Processed, SE);

2539

}

2540

2541

/// Return true if the number of registers needed for the chain is estimated to

2542

/// be less than the number required for the individual IV users. First prohibit

2543

/// any IV users that keep the IV live across increments (the Users set should

2544

/// be empty). Next count the number and type of increments in the chain.

2545

///

2546

/// Chaining IVs can lead to considerable code bloat if ISEL doesn't

2547

/// effectively use postinc addressing modes. Only consider it profitable it the

2548

/// increments can be computed in fewer registers when chained.

2549

///

2550

/// TODO: Consider IVInc free if it's already used in another chains.

2551

static bool

2552

isProfitableChain(IVChain &Chain, SmallPtrSetImpl<Instruction*> &Users,

2553

ScalarEvolution &SE, const TargetTransformInfo &TTI) {

2554

if (StressIVChain)

2555

return true;

2556

2557

if (!Chain.hasIncs())

2558

return false;

2559

2560

if (!Users.empty()) {

2561

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)

2562

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)

2563

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)

2564

})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);

2565

return false;

2566

}

2567

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2567, __PRETTY_FUNCTION__));

2568

2569

// The chain itself may require a register, so intialize cost to 1.

2570

int cost = 1;

2571

2572

// A complete chain likely eliminates the need for keeping the original IV in

2573

// a register. LSR does not currently know how to form a complete chain unless

2574

// the header phi already exists.

2575

if (isa<PHINode>(Chain.tailUserInst())

2576

&& SE.getSCEV(Chain.tailUserInst()) == Chain.Incs[0].IncExpr) {

2577

--cost;

2578

}

2579

const SCEV *LastIncExpr = nullptr;

2580

unsigned NumConstIncrements = 0;

2581

unsigned NumVarIncrements = 0;

2582

unsigned NumReusedIncrements = 0;

2583

for (IVChain::const_iterator I = Chain.begin(), E = Chain.end();

2584

I != E; ++I) {

2585

2586

if (I->IncExpr->isZero())

2587

continue;

2588

2589

// Incrementing by zero or some constant is neutral. We assume constants can

2590

// be folded into an addressing mode or an add's immediate operand.

2591

if (isa<SCEVConstant>(I->IncExpr)) {

2592

++NumConstIncrements;

2593

continue;

2594

}

2595

2596

if (I->IncExpr == LastIncExpr)

2597

++NumReusedIncrements;

2598

else

2599

++NumVarIncrements;

2600

2601

LastIncExpr = I->IncExpr;

2602

}

2603

// An IV chain with a single increment is handled by LSR's postinc

2604

// uses. However, a chain with multiple increments requires keeping the IV's

2605

// value live longer than it needs to be if chained.

2606

if (NumConstIncrements > 1)

2607

--cost;

2608

2609

// Materializing increment expressions in the preheader that didn't exist in

2610

// the original code may cost a register. For example, sign-extended array

2611

// indices can produce ridiculous increments like this:

2612

// IV + ((sext i32 (2 * %s) to i64) + (-1 * (sext i32 %s to i64)))

2613

cost += NumVarIncrements;

2614

2615

// Reusing variable increments likely saves a register to hold the multiple of

2616

// the stride.

2617

cost -= NumReusedIncrements;

2618

2619

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)

2620

<< "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " Cost: " << cost << "\n"
; } } while (0);

2621

2622

return cost < 0;

2623

}

2624

2625

/// ChainInstruction - Add this IV user to an existing chain or make it the head

2626

/// of a new chain.

2627

void LSRInstance::ChainInstruction(Instruction *UserInst, Instruction *IVOper,

2628

SmallVectorImpl<ChainUsers> &ChainUsersVec) {

2629

// When IVs are used as types of varying widths, they are generally converted

2630

// to a wider type with some uses remaining narrow under a (free) trunc.

2631

Value *const NextIV = getWideOperand(IVOper);

2632

const SCEV *const OperExpr = SE.getSCEV(NextIV);

2633

const SCEV *const OperExprBase = getExprBase(OperExpr);

2634

2635

// Visit all existing chains. Check if its IVOper can be computed as a

2636

// profitable loop invariant increment from the last link in the Chain.

2637

unsigned ChainIdx = 0, NChains = IVChainVec.size();

2638

const SCEV *LastIncExpr = nullptr;

2639

for (; ChainIdx < NChains; ++ChainIdx) {

2640

IVChain &Chain = IVChainVec[ChainIdx];

2641

2642

// Prune the solution space aggressively by checking that both IV operands

2643

// are expressions that operate on the same unscaled SCEVUnknown. This

2644

// "base" will be canceled by the subsequent getMinusSCEV call. Checking

2645

// first avoids creating extra SCEV expressions.

2646

if (!StressIVChain && Chain.ExprBase != OperExprBase)

2647

continue;

2648

2649

Value *PrevIV = getWideOperand(Chain.Incs.back().IVOperand);

2650

if (!isCompatibleIVType(PrevIV, NextIV))

2651

continue;

2652

2653

// A phi node terminates a chain.

2654

if (isa<PHINode>(UserInst) && isa<PHINode>(Chain.tailUserInst()))

2655

continue;

2656

2657

// The increment must be loop-invariant so it can be kept in a register.

2658

const SCEV *PrevExpr = SE.getSCEV(PrevIV);

2659

const SCEV *IncExpr = SE.getMinusSCEV(OperExpr, PrevExpr);

2660

if (!SE.isLoopInvariant(IncExpr, L))

2661

continue;

2662

2663

if (Chain.isProfitableIncrement(OperExpr, IncExpr, SE)) {

2664

LastIncExpr = IncExpr;

2665

break;

2666

}

2667

}

2668

// If we haven't found a chain, create a new one, unless we hit the max. Don't

2669

// bother for phi nodes, because they must be last in the chain.

2670

if (ChainIdx == NChains) {

2671

if (isa<PHINode>(UserInst))

2672

return;

2673

if (NChains >= MaxChains && !StressIVChain) {

2674

DEBUG(dbgs() << "IV Chain Limit\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain Limit\n"; } } while
(0);

2675

return;

2676

}

2677

LastIncExpr = OperExpr;

2678

// IVUsers may have skipped over sign/zero extensions. We don't currently

2679

// attempt to form chains involving extensions unless they can be hoisted

2680

// into this loop's AddRec.

2681

if (!isa<SCEVAddRecExpr>(LastIncExpr))

2682

return;

2683

++NChains;

2684

IVChainVec.push_back(IVChain(IVInc(UserInst, IVOper, LastIncExpr),

2685

OperExprBase));

2686

ChainUsersVec.resize(NChains);

2687

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)

2688

<< ") IV=" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Head: (" << *UserInst << ") IV=" <<
*LastIncExpr << "\n"; } } while (0);

2689

} else {

2690

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)

2691

<< ") IV+" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Inc: (" << *UserInst << ") IV+" <<
*LastIncExpr << "\n"; } } while (0);

2692

// Add this IV user to the end of the chain.

2693

IVChainVec[ChainIdx].add(IVInc(UserInst, IVOper, LastIncExpr));

2694

}

2695

IVChain &Chain = IVChainVec[ChainIdx];

2696

2697

SmallPtrSet<Instruction*,4> &NearUsers = ChainUsersVec[ChainIdx].NearUsers;

2698

// This chain's NearUsers become FarUsers.

2699

if (!LastIncExpr->isZero()) {

2700

ChainUsersVec[ChainIdx].FarUsers.insert(NearUsers.begin(),

2701

NearUsers.end());

2702

NearUsers.clear();

2703

}

2704

2705

// All other uses of IVOperand become near uses of the chain.

2706

// We currently ignore intermediate values within SCEV expressions, assuming

2707

// they will eventually be used be the current chain, or can be computed

2708

// from one of the chain increments. To be more precise we could

2709

// transitively follow its user and only add leaf IV users to the set.

2710

for (User *U : IVOper->users()) {

2711

Instruction *OtherUse = dyn_cast<Instruction>(U);

2712

if (!OtherUse)

2713

continue;

2714

// Uses in the chain will no longer be uses if the chain is formed.

2715

// Include the head of the chain in this iteration (not Chain.begin()).

2716

IVChain::const_iterator IncIter = Chain.Incs.begin();

2717

IVChain::const_iterator IncEnd = Chain.Incs.end();

2718

for( ; IncIter != IncEnd; ++IncIter) {

2719

if (IncIter->UserInst == OtherUse)

2720

break;

2721

}

2722

if (IncIter != IncEnd)

2723

continue;

2724

2725

if (SE.isSCEVable(OtherUse->getType())

2726

&& !isa<SCEVUnknown>(SE.getSCEV(OtherUse))

2727

&& IU.isIVUserOrOperand(OtherUse)) {

2728

continue;

2729

}

2730

NearUsers.insert(OtherUse);

2731

}

2732

2733

// Since this user is part of the chain, it's no longer considered a use

2734

// of the chain.

2735

ChainUsersVec[ChainIdx].FarUsers.erase(UserInst);

2736

}

2737

2738

/// CollectChains - Populate the vector of Chains.

2739

///

2740

/// This decreases ILP at the architecture level. Targets with ample registers,

2741

/// multiple memory ports, and no register renaming probably don't want

2742

/// this. However, such targets should probably disable LSR altogether.

2743

///

2744

/// The job of LSR is to make a reasonable choice of induction variables across

2745

/// the loop. Subsequent passes can easily "unchain" computation exposing more

2746

/// ILP *within the loop* if the target wants it.

2747

///

2748

/// Finding the best IV chain is potentially a scheduling problem. Since LSR

2749

/// will not reorder memory operations, it will recognize this as a chain, but

2750

/// will generate redundant IV increments. Ideally this would be corrected later

2751

/// by a smart scheduler:

2752

/// = A[i]

2753

/// = A[i+x]

2754

/// A[i] =

2755

/// A[i+x] =

2756

///

2757

/// TODO: Walk the entire domtree within this loop, not just the path to the

2758

/// loop latch. This will discover chains on side paths, but requires

2759

/// maintaining multiple copies of the Chains state.

2760

void LSRInstance::CollectChains() {

2761

DEBUG(dbgs() << "Collecting IV Chains.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Collecting IV Chains.\n";
} } while (0);

2762

SmallVector<ChainUsers, 8> ChainUsersVec;

2763

2764

SmallVector<BasicBlock *,8> LatchPath;

2765

BasicBlock *LoopHeader = L->getHeader();

2766

for (DomTreeNode *Rung = DT.getNode(L->getLoopLatch());

2767

Rung->getBlock() != LoopHeader; Rung = Rung->getIDom()) {

2768

LatchPath.push_back(Rung->getBlock());

2769

}

2770

LatchPath.push_back(LoopHeader);

2771

2772

// Walk the instruction stream from the loop header to the loop latch.

2773

for (SmallVectorImpl<BasicBlock *>::reverse_iterator

2774

BBIter = LatchPath.rbegin(), BBEnd = LatchPath.rend();

2775

BBIter != BBEnd; ++BBIter) {

2776

for (BasicBlock::iterator I = (*BBIter)->begin(), E = (*BBIter)->end();

2777

I != E; ++I) {

2778

// Skip instructions that weren't seen by IVUsers analysis.

2779

if (isa<PHINode>(I) || !IU.isIVUserOrOperand(I))

2780

continue;

2781

2782

// Ignore users that are part of a SCEV expression. This way we only

2783

// consider leaf IV Users. This effectively rediscovers a portion of

2784

// IVUsers analysis but in program order this time.

2785

if (SE.isSCEVable(I->getType()) && !isa<SCEVUnknown>(SE.getSCEV(I)))

2786

continue;

2787

2788

// Remove this instruction from any NearUsers set it may be in.

2789

for (unsigned ChainIdx = 0, NChains = IVChainVec.size();

2790

ChainIdx < NChains; ++ChainIdx) {

2791

ChainUsersVec[ChainIdx].NearUsers.erase(I);

2792

}

2793

// Search for operands that can be chained.

2794

SmallPtrSet<Instruction*, 4> UniqueOperands;

2795

User::op_iterator IVOpEnd = I->op_end();

2796

User::op_iterator IVOpIter = findIVOperand(I->op_begin(), IVOpEnd, L, SE);

2797

while (IVOpIter != IVOpEnd) {

2798

Instruction *IVOpInst = cast<Instruction>(*IVOpIter);

2799

if (UniqueOperands.insert(IVOpInst).second)

2800

ChainInstruction(I, IVOpInst, ChainUsersVec);

2801

IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);

2802

}

2803

} // Continue walking down the instructions.

2804

} // Continue walking down the domtree.

2805

// Visit phi backedges to determine if the chain can generate the IV postinc.

2806

for (BasicBlock::iterator I = L->getHeader()->begin();

2807

PHINode *PN = dyn_cast<PHINode>(I); ++I) {

2808

if (!SE.isSCEVable(PN->getType()))

2809

continue;

2810

2811

Instruction *IncV =

2812

dyn_cast<Instruction>(PN->getIncomingValueForBlock(L->getLoopLatch()));

2813

if (IncV)

2814

ChainInstruction(PN, IncV, ChainUsersVec);

2815

}

2816

// Remove any unprofitable chains.

2817

unsigned ChainIdx = 0;

2818

for (unsigned UsersIdx = 0, NChains = IVChainVec.size();

2819

UsersIdx < NChains; ++UsersIdx) {

2820

if (!isProfitableChain(IVChainVec[UsersIdx],

2821

ChainUsersVec[UsersIdx].FarUsers, SE, TTI))

2822

continue;

2823

// Preserve the chain at UsesIdx.

2824

if (ChainIdx != UsersIdx)

2825

IVChainVec[ChainIdx] = IVChainVec[UsersIdx];

2826

FinalizeChain(IVChainVec[ChainIdx]);

2827

++ChainIdx;

2828

}

2829

IVChainVec.resize(ChainIdx);

2830

}

2831

2832

void LSRInstance::FinalizeChain(IVChain &Chain) {

2833

2834

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);

2835

2836

for (IVChain::const_iterator I = Chain.begin(), E = Chain.end();

2837

I != E; ++I) {

2838

DEBUG(dbgs() << " Inc: " << *I->UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Inc: " << *
I->UserInst << "\n"; } } while (0);

2839

User::op_iterator UseI =

2840

std::find(I->UserInst->op_begin(), I->UserInst->op_end(), I->IVOperand);

2841

assert(UseI != I->UserInst->op_end() && "cannot find IV operand")((UseI != I->UserInst->op_end() && "cannot find IV operand"
) ? static_cast<void> (0) : __assert_fail ("UseI != I->UserInst->op_end() && \"cannot find IV operand\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2841, __PRETTY_FUNCTION__));

2842

IVIncSet.insert(UseI);

2843

}

2844

}

2845

2846

/// Return true if the IVInc can be folded into an addressing mode.

2847

static bool canFoldIVIncExpr(const SCEV *IncExpr, Instruction *UserInst,

2848

Value *Operand, const TargetTransformInfo &TTI) {

2849

const SCEVConstant *IncConst = dyn_cast<SCEVConstant>(IncExpr);

2850

if (!IncConst || !isAddressUse(UserInst, Operand))

2851

return false;

2852

2853

if (IncConst->getValue()->getValue().getMinSignedBits() > 64)

2854

return false;

2855

2856

int64_t IncOffset = IncConst->getValue()->getSExtValue();

2857

if (!isAlwaysFoldable(TTI, LSRUse::Address,

2858

getAccessType(UserInst), /*BaseGV=*/ nullptr,

2859

IncOffset, /*HaseBaseReg=*/ false))

2860

return false;

2861

2862

return true;

2863

}

2864

2865

/// GenerateIVChains - Generate an add or subtract for each IVInc in a chain to

2866

/// materialize the IV user's operand from the previous IV user's operand.

2867

void LSRInstance::GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,

2868

SmallVectorImpl<WeakVH> &DeadInsts) {

2869

// Find the new IVOperand for the head of the chain. It may have been replaced

2870

// by LSR.

2871

const IVInc &Head = Chain.Incs[0];

2872

User::op_iterator IVOpEnd = Head.UserInst->op_end();

2873

// findIVOperand returns IVOpEnd if it can no longer find a valid IV user.

2874

User::op_iterator IVOpIter = findIVOperand(Head.UserInst->op_begin(),

2875

IVOpEnd, L, SE);

2876

Value *IVSrc = nullptr;

2877

while (IVOpIter != IVOpEnd) {

2878

IVSrc = getWideOperand(*IVOpIter);

2879

2880

// If this operand computes the expression that the chain needs, we may use

2881

// it. (Check this after setting IVSrc which is used below.)

2882

2883

// Note that if Head.IncExpr is wider than IVSrc, then this phi is too

2884

// narrow for the chain, so we can no longer use it. We do allow using a

2885

// wider phi, assuming the LSR checked for free truncation. In that case we

2886

// should already have a truncate on this operand such that

2887

// getSCEV(IVSrc) == IncExpr.

2888

if (SE.getSCEV(*IVOpIter) == Head.IncExpr

2889

|| SE.getSCEV(IVSrc) == Head.IncExpr) {

2890

break;

2891

}

2892

IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);

2893

}

2894

if (IVOpIter == IVOpEnd) {

2895

// Gracefully give up on this chain.

2896

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);

2897

return;

2898

}

2899

2900

DEBUG(dbgs() << "Generate chain at: " << *IVSrc << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generate chain at: " <<
*IVSrc << "\n"; } } while (0);

2901

Type *IVTy = IVSrc->getType();

2902

Type *IntTy = SE.getEffectiveSCEVType(IVTy);

2903

const SCEV *LeftOverExpr = nullptr;

2904

for (IVChain::const_iterator IncI = Chain.begin(),

2905

IncE = Chain.end(); IncI != IncE; ++IncI) {

2906

2907

Instruction *InsertPt = IncI->UserInst;

2908

if (isa<PHINode>(InsertPt))

2909

InsertPt = L->getLoopLatch()->getTerminator();

2910

2911

// IVOper will replace the current IV User's operand. IVSrc is the IV

2912

// value currently held in a register.

2913

Value *IVOper = IVSrc;

2914

if (!IncI->IncExpr->isZero()) {

2915

// IncExpr was the result of subtraction of two narrow values, so must

2916

// be signed.

2917

const SCEV *IncExpr = SE.getNoopOrSignExtend(IncI->IncExpr, IntTy);

2918

LeftOverExpr = LeftOverExpr ?

2919

SE.getAddExpr(LeftOverExpr, IncExpr) : IncExpr;

2920

}

2921

if (LeftOverExpr && !LeftOverExpr->isZero()) {

2922

// Expand the IV increment.

2923

Rewriter.clearPostInc();

2924

Value *IncV = Rewriter.expandCodeFor(LeftOverExpr, IntTy, InsertPt);

2925

const SCEV *IVOperExpr = SE.getAddExpr(SE.getUnknown(IVSrc),

2926

SE.getUnknown(IncV));

2927

IVOper = Rewriter.expandCodeFor(IVOperExpr, IVTy, InsertPt);

2928

2929

// If an IV increment can't be folded, use it as the next IV value.

2930

if (!canFoldIVIncExpr(LeftOverExpr, IncI->UserInst, IncI->IVOperand,

2931

TTI)) {

2932

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2932, __PRETTY_FUNCTION__));

2933

IVSrc = IVOper;

2934

LeftOverExpr = nullptr;

2935

}

2936

}

2937

Type *OperTy = IncI->IVOperand->getType();

2938

if (IVTy != OperTy) {

2939

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2940, __PRETTY_FUNCTION__))

2940

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2940, __PRETTY_FUNCTION__));

2941

IRBuilder<> Builder(InsertPt);

2942

IVOper = Builder.CreateTruncOrBitCast(IVOper, OperTy, "lsr.chain");

2943

}

2944

IncI->UserInst->replaceUsesOfWith(IncI->IVOperand, IVOper);

2945

DeadInsts.push_back(IncI->IVOperand);

2946

}

2947

// If LSR created a new, wider phi, we may also replace its postinc. We only

2948

// do this if we also found a wide value for the head of the chain.

2949

if (isa<PHINode>(Chain.tailUserInst())) {

2950

for (BasicBlock::iterator I = L->getHeader()->begin();

2951

PHINode *Phi = dyn_cast<PHINode>(I); ++I) {

2952

if (!isCompatibleIVType(Phi, IVSrc))

2953

continue;

2954

Instruction *PostIncV = dyn_cast<Instruction>(

2955

Phi->getIncomingValueForBlock(L->getLoopLatch()));

2956

if (!PostIncV || (SE.getSCEV(PostIncV) != SE.getSCEV(IVSrc)))

2957

continue;

2958

Value *IVOper = IVSrc;

2959

Type *PostIncTy = PostIncV->getType();

2960

if (IVTy != PostIncTy) {

2961

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2961, __PRETTY_FUNCTION__));

2962

IRBuilder<> Builder(L->getLoopLatch()->getTerminator());

2963

Builder.SetCurrentDebugLocation(PostIncV->getDebugLoc());

2964

IVOper = Builder.CreatePointerCast(IVSrc, PostIncTy, "lsr.chain");

2965

}

2966

Phi->replaceUsesOfWith(PostIncV, IVOper);

2967

DeadInsts.push_back(PostIncV);

2968

}

2969

}

2970

}

2971

2972

void LSRInstance::CollectFixupsAndInitialFormulae() {

2973

for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) {

2974

Instruction *UserInst = UI->getUser();

2975

// Skip IV users that are part of profitable IV Chains.

2976

User::op_iterator UseI = std::find(UserInst->op_begin(), UserInst->op_end(),

2977

UI->getOperandValToReplace());

2978

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2978, __PRETTY_FUNCTION__));

2979

if (IVIncSet.count(UseI))

2980

continue;

2981

2982

// Record the uses.

2983

LSRFixup &LF = getNewFixup();

2984

LF.UserInst = UserInst;

2985

LF.OperandValToReplace = UI->getOperandValToReplace();

2986

LF.PostIncLoops = UI->getPostIncLoops();

2987

2988

LSRUse::KindType Kind = LSRUse::Basic;

2989

Type *AccessTy = nullptr;

2990

if (isAddressUse(LF.UserInst, LF.OperandValToReplace)) {

2991

Kind = LSRUse::Address;

2992

AccessTy = getAccessType(LF.UserInst);

2993

}

2994

2995

const SCEV *S = IU.getExpr(*UI);

2996

2997

// Equality (== and !=) ICmps are special. We can rewrite (i == N) as

2998

// (N - i == 0), and this allows (N - i) to be the expression that we work

2999

// with rather than just N or i, so we can consider the register

3000

// requirements for both N and i at the same time. Limiting this code to

3001

// equality icmps is not a problem because all interesting loops use

3002

// equality icmps, thanks to IndVarSimplify.

3003

if (ICmpInst *CI = dyn_cast<ICmpInst>(LF.UserInst))

3004

if (CI->isEquality()) {

3005

// Swap the operands if needed to put the OperandValToReplace on the

3006

// left, for consistency.

3007

Value *NV = CI->getOperand(1);

3008

if (NV == LF.OperandValToReplace) {

3009

CI->setOperand(1, CI->getOperand(0));

3010

CI->setOperand(0, NV);

3011

NV = CI->getOperand(1);

3012

Changed = true;

3013

}

3014

3015

// x == y --> x - y == 0

3016

const SCEV *N = SE.getSCEV(NV);

3017

if (SE.isLoopInvariant(N, L) && isSafeToExpand(N, SE)) {

3018

// S is normalized, so normalize N before folding it into S

3019

// to keep the result normalized.

3020

N = TransformForPostIncUse(Normalize, N, CI, nullptr,

3021

LF.PostIncLoops, SE, DT);

3022

Kind = LSRUse::ICmpZero;

3023

S = SE.getMinusSCEV(N, S);

3024

}

3025

3026

// -1 and the negations of all interesting strides (except the negation

3027

// of -1) are now also interesting.

3028

for (size_t i = 0, e = Factors.size(); i != e; ++i)

3029

if (Factors[i] != -1)

3030

Factors.insert(-(uint64_t)Factors[i]);

3031

Factors.insert(-1);

3032

}

3033

3034

// Set up the initial formula for this use.

3035

std::pair<size_t, int64_t> P = getUse(S, Kind, AccessTy);

3036

LF.LUIdx = P.first;

3037

LF.Offset = P.second;

3038

LSRUse &LU = Uses[LF.LUIdx];

3039

LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);

3040

if (!LU.WidestFixupType ||

3041

SE.getTypeSizeInBits(LU.WidestFixupType) <

3042

SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))

3043

LU.WidestFixupType = LF.OperandValToReplace->getType();

3044

3045

// If this is the first use of this LSRUse, give it a formula.

3046

if (LU.Formulae.empty()) {

3047

InsertInitialFormula(S, LU, LF.LUIdx);

3048

CountRegisters(LU.Formulae.back(), LF.LUIdx);

3049

}

3050

}

3051

3052

DEBUG(print_fixups(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_fixups(dbgs()); } } while (0);

3053

}

3054

3055

/// InsertInitialFormula - Insert a formula for the given expression into

3056

/// the given use, separating out loop-variant portions from loop-invariant

3057

/// and loop-computable portions.

3058

void

3059

LSRInstance::InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx) {

3060

// Mark uses whose expressions cannot be expanded.

3061

if (!isSafeToExpand(S, SE))

3062

LU.RigidFormula = true;

3063

3064

Formula F;

3065

F.InitialMatch(S, L, SE);

3066

bool Inserted = InsertFormula(LU, LUIdx, F);

3067

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3067, __PRETTY_FUNCTION__)); (void)Inserted;

3068

}

3069

3070

/// InsertSupplementalFormula - Insert a simple single-register formula for

3071

/// the given expression into the given use.

3072

void

3073

LSRInstance::InsertSupplementalFormula(const SCEV *S,

3074

LSRUse &LU, size_t LUIdx) {

3075

Formula F;

3076

F.BaseRegs.push_back(S);

3077

F.HasBaseReg = true;

3078

bool Inserted = InsertFormula(LU, LUIdx, F);

3079

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3079, __PRETTY_FUNCTION__)); (void)Inserted;

3080

}

3081

3082

/// CountRegisters - Note which registers are used by the given formula,

3083

/// updating RegUses.

3084

void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) {

3085

if (F.ScaledReg)

3086

RegUses.CountRegister(F.ScaledReg, LUIdx);

3087

for (SmallVectorImpl<const SCEV *>::const_iterator I = F.BaseRegs.begin(),

3088

E = F.BaseRegs.end(); I != E; ++I)

3089

RegUses.CountRegister(*I, LUIdx);

3090

}

3091

3092

/// InsertFormula - If the given formula has not yet been inserted, add it to

3093

/// the list, and return true. Return false otherwise.

3094

bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) {

3095

// Do not insert formula that we will not be able to expand.

3096

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3097, __PRETTY_FUNCTION__))

3097

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3097, __PRETTY_FUNCTION__));

3098

if (!LU.InsertFormula(F))

3099

return false;

3100

3101

CountRegisters(F, LUIdx);

3102

return true;

3103

}

3104

3105

/// CollectLoopInvariantFixupsAndFormulae - Check for other uses of

3106

/// loop-invariant values which we're tracking. These other uses will pin these

3107

/// values in registers, making them less profitable for elimination.

3108

/// TODO: This currently misses non-constant addrec step registers.

3109

/// TODO: Should this give more weight to users inside the loop?

3110

void

3111

LSRInstance::CollectLoopInvariantFixupsAndFormulae() {

3112

SmallVector<const SCEV *, 8> Worklist(RegUses.begin(), RegUses.end());

3113

SmallPtrSet<const SCEV *, 32> Visited;

3114

3115

while (!Worklist.empty()) {

3116

const SCEV *S = Worklist.pop_back_val();

3117

3118

// Don't process the same SCEV twice

3119

if (!Visited.insert(S).second)

3120

continue;

3121

3122

if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S))

3123

Worklist.append(N->op_begin(), N->op_end());

3124

else if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S))

3125

Worklist.push_back(C->getOperand());

3126

else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {

3127

Worklist.push_back(D->getLHS());

3128

Worklist.push_back(D->getRHS());

3129

} else if (const SCEVUnknown *US = dyn_cast<SCEVUnknown>(S)) {

3130

const Value *V = US->getValue();

3131

if (const Instruction *Inst = dyn_cast<Instruction>(V)) {

3132

// Look for instructions defined outside the loop.

3133

if (L->contains(Inst)) continue;

3134

} else if (isa<UndefValue>(V))

3135

// Undef doesn't have a live range, so it doesn't matter.

3136

continue;

3137

for (const Use &U : V->uses()) {

3138

const Instruction *UserInst = dyn_cast<Instruction>(U.getUser());

3139

// Ignore non-instructions.

3140

if (!UserInst)

3141

continue;

3142

// Ignore instructions in other functions (as can happen with

3143

// Constants).

3144

if (UserInst->getParent()->getParent() != L->getHeader()->getParent())

3145

continue;

3146

// Ignore instructions not dominated by the loop.

3147

const BasicBlock *UseBB = !isa<PHINode>(UserInst) ?

3148

UserInst->getParent() :

3149

cast<PHINode>(UserInst)->getIncomingBlock(

3150

PHINode::getIncomingValueNumForOperand(U.getOperandNo()));

3151

if (!DT.dominates(L->getHeader(), UseBB))

3152

continue;

3153

// Ignore uses which are part of other SCEV expressions, to avoid

3154

// analyzing them multiple times.

3155

if (SE.isSCEVable(UserInst->getType())) {

3156

const SCEV *UserS = SE.getSCEV(const_cast<Instruction *>(UserInst));

3157

// If the user is a no-op, look through to its uses.

3158

if (!isa<SCEVUnknown>(UserS))

3159

continue;

3160

if (UserS == US) {

3161

Worklist.push_back(

3162

SE.getUnknown(const_cast<Instruction *>(UserInst)));

3163

continue;

3164

}

3165

}

3166

// Ignore icmp instructions which are already being analyzed.

3167

if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) {

3168

unsigned OtherIdx = !U.getOperandNo();

3169

Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx));

3170

if (SE.hasComputableLoopEvolution(SE.getSCEV(OtherOp), L))

3171

continue;

3172

}

3173

3174

LSRFixup &LF = getNewFixup();

3175

LF.UserInst = const_cast<Instruction *>(UserInst);

3176

LF.OperandValToReplace = U;

3177

std::pair<size_t, int64_t> P = getUse(S, LSRUse::Basic, nullptr);

3178

LF.LUIdx = P.first;

3179

LF.Offset = P.second;

3180

LSRUse &LU = Uses[LF.LUIdx];

3181

LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);

3182

if (!LU.WidestFixupType ||

3183

SE.getTypeSizeInBits(LU.WidestFixupType) <

3184

SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))

3185

LU.WidestFixupType = LF.OperandValToReplace->getType();

3186

InsertSupplementalFormula(US, LU, LF.LUIdx);

3187

CountRegisters(LU.Formulae.back(), Uses.size() - 1);

3188

break;

3189

}

3190

}

3191

}

3192

}

3193

3194

/// CollectSubexprs - Split S into subexpressions which can be pulled out into

3195

/// separate registers. If C is non-null, multiply each subexpression by C.

3196

///

3197

/// Return remainder expression after factoring the subexpressions captured by

3198

/// Ops. If Ops is complete, return NULL.

3199

static const SCEV *CollectSubexprs(const SCEV *S, const SCEVConstant *C,

3200

SmallVectorImpl<const SCEV *> &Ops,

3201

const Loop *L,

3202

ScalarEvolution &SE,

3203

unsigned Depth = 0) {

3204

// Arbitrarily cap recursion to protect compile time.

3205

if (Depth >= 3)

3206

return S;

3207

3208

if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {

3209

// Break out add operands.

3210

for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();

3211

I != E; ++I) {

3212

const SCEV *Remainder = CollectSubexprs(*I, C, Ops, L, SE, Depth+1);

3213

if (Remainder)

3214

Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);

3215

}

3216

return nullptr;

3217

} else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {

3218

// Split a non-zero base out of an addrec.

3219

if (AR->getStart()->isZero())

3220

return S;

3221

3222

const SCEV *Remainder = CollectSubexprs(AR->getStart(),

3223

C, Ops, L, SE, Depth+1);

3224

// Split the non-zero AddRec unless it is part of a nested recurrence that

3225

// does not pertain to this loop.

3226

if (Remainder && (AR->getLoop() == L || !isa<SCEVAddRecExpr>(Remainder))) {

3227

Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);

3228

Remainder = nullptr;

3229

}

3230

if (Remainder != AR->getStart()) {

3231

if (!Remainder)

3232

Remainder = SE.getConstant(AR->getType(), 0);

3233

return SE.getAddRecExpr(Remainder,

3234

AR->getStepRecurrence(SE),

3235

AR->getLoop(),

3236

//FIXME: AR->getNoWrapFlags(SCEV::FlagNW)

3237

SCEV::FlagAnyWrap);

3238

}

3239

} else if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {

3240

// Break (C * (a + b + c)) into C*a + C*b + C*c.

3241

if (Mul->getNumOperands() != 2)

3242

return S;

3243

if (const SCEVConstant *Op0 =

3244

dyn_cast<SCEVConstant>(Mul->getOperand(0))) {

3245

C = C ? cast<SCEVConstant>(SE.getMulExpr(C, Op0)) : Op0;

3246

const SCEV *Remainder =

3247

CollectSubexprs(Mul->getOperand(1), C, Ops, L, SE, Depth+1);

3248

if (Remainder)

3249

Ops.push_back(SE.getMulExpr(C, Remainder));

3250

return nullptr;

3251

}

3252

}

3253

return S;

3254

}

3255

3256

/// \brief Helper function for LSRInstance::GenerateReassociations.

3257

void LSRInstance::GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,

3258

const Formula &Base,

3259

unsigned Depth, size_t Idx,

3260

bool IsScaledReg) {

3261

const SCEV *BaseReg = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];

3262

SmallVector<const SCEV *, 8> AddOps;

3263

const SCEV *Remainder = CollectSubexprs(BaseReg, nullptr, AddOps, L, SE);

3264

if (Remainder)

3265

AddOps.push_back(Remainder);

3266

3267

if (AddOps.size() == 1)

3268

return;

3269

3270

for (SmallVectorImpl<const SCEV *>::const_iterator J = AddOps.begin(),

3271

JE = AddOps.end();

3272

J != JE; ++J) {

3273

3274

// Loop-variant "unknown" values are uninteresting; we won't be able to

3275

// do anything meaningful with them.

3276

if (isa<SCEVUnknown>(*J) && !SE.isLoopInvariant(*J, L))

3277

continue;

3278

3279

// Don't pull a constant into a register if the constant could be folded

3280

// into an immediate field.

3281

if (isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,

3282

LU.AccessTy, *J, Base.getNumRegs() > 1))

3283

continue;

3284

3285

// Collect all operands except *J.

3286

SmallVector<const SCEV *, 8> InnerAddOps(

3287

((const SmallVector<const SCEV *, 8> &)AddOps).begin(), J);

3288

InnerAddOps.append(std::next(J),

3289

((const SmallVector<const SCEV *, 8> &)AddOps).end());

3290

3291

// Don't leave just a constant behind in a register if the constant could

3292

// be folded into an immediate field.

3293

if (InnerAddOps.size() == 1 &&

3294

isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,

3295

LU.AccessTy, InnerAddOps[0], Base.getNumRegs() > 1))

3296

continue;

3297

3298

const SCEV *InnerSum = SE.getAddExpr(InnerAddOps);

3299

if (InnerSum->isZero())

3300

continue;

3301

Formula F = Base;

3302

3303

// Add the remaining pieces of the add back into the new formula.

3304

const SCEVConstant *InnerSumSC = dyn_cast<SCEVConstant>(InnerSum);

3305

if (InnerSumSC && SE.getTypeSizeInBits(InnerSumSC->getType()) <= 64 &&

3306

TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +

3307

InnerSumSC->getValue()->getZExtValue())) {

3308

F.UnfoldedOffset =

3309

(uint64_t)F.UnfoldedOffset + InnerSumSC->getValue()->getZExtValue();

3310

if (IsScaledReg)

3311

F.ScaledReg = nullptr;

3312

else

3313

F.BaseRegs.erase(F.BaseRegs.begin() + Idx);

3314

} else if (IsScaledReg)

3315

F.ScaledReg = InnerSum;

3316

else

3317

F.BaseRegs[Idx] = InnerSum;

3318

3319

// Add J as its own register, or an unfolded immediate.

3320

const SCEVConstant *SC = dyn_cast<SCEVConstant>(*J);

3321

if (SC && SE.getTypeSizeInBits(SC->getType()) <= 64 &&

3322

TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +

3323

SC->getValue()->getZExtValue()))

3324

F.UnfoldedOffset =

3325

(uint64_t)F.UnfoldedOffset + SC->getValue()->getZExtValue();

3326

else

3327

F.BaseRegs.push_back(*J);

3328

// We may have changed the number of register in base regs, adjust the

3329

// formula accordingly.

3330

F.Canonicalize();

3331

3332

if (InsertFormula(LU, LUIdx, F))

3333

// If that formula hadn't been seen before, recurse to find more like

3334

// it.

3335

GenerateReassociations(LU, LUIdx, LU.Formulae.back(), Depth + 1);

3336

}

3337

}

3338

3339

/// GenerateReassociations - Split out subexpressions from adds and the bases of

3340

/// addrecs.

3341

void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx,

3342

Formula Base, unsigned Depth) {

3343

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3343, __PRETTY_FUNCTION__));

3344

// Arbitrarily cap recursion to protect compile time.

3345

if (Depth >= 3)

3346

return;

3347

3348

for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)

3349

GenerateReassociationsImpl(LU, LUIdx, Base, Depth, i);

3350

3351

if (Base.Scale == 1)

3352

GenerateReassociationsImpl(LU, LUIdx, Base, Depth,

3353

/* Idx */ -1, /* IsScaledReg */ true);

3354

}

3355

3356

/// GenerateCombinations - Generate a formula consisting of all of the

3357

/// loop-dominating registers added into a single register.

3358

void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx,

3359

Formula Base) {

3360

// This method is only interesting on a plurality of registers.

3361

if (Base.BaseRegs.size() + (Base.Scale == 1) <= 1)

3362

return;

3363

3364

// Flatten the representation, i.e., reg1 + 1*reg2 => reg1 + reg2, before

3365

// processing the formula.

3366

Base.Unscale();

3367

Formula F = Base;

3368

F.BaseRegs.clear();

3369

SmallVector<const SCEV *, 4> Ops;

3370

for (SmallVectorImpl<const SCEV *>::const_iterator

3371

I = Base.BaseRegs.begin(), E = Base.BaseRegs.end(); I != E; ++I) {

3372

const SCEV *BaseReg = *I;

3373

if (SE.properlyDominates(BaseReg, L->getHeader()) &&

3374

!SE.hasComputableLoopEvolution(BaseReg, L))

3375

Ops.push_back(BaseReg);

3376

else

3377

F.BaseRegs.push_back(BaseReg);

3378

}

3379

if (Ops.size() > 1) {

3380

const SCEV *Sum = SE.getAddExpr(Ops);

3381

// TODO: If Sum is zero, it probably means ScalarEvolution missed an

3382

// opportunity to fold something. For now, just ignore such cases

3383

// rather than proceed with zero in a register.

3384

if (!Sum->isZero()) {

3385

F.BaseRegs.push_back(Sum);

3386

F.Canonicalize();

3387

(void)InsertFormula(LU, LUIdx, F);

3388

}

3389

}

3390

}

3391

3392

/// \brief Helper function for LSRInstance::GenerateSymbolicOffsets.

3393

void LSRInstance::GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,

3394

const Formula &Base, size_t Idx,

3395

bool IsScaledReg) {

3396

const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];

3397

GlobalValue *GV = ExtractSymbol(G, SE);

3398

if (G->isZero() || !GV)

3399

return;

3400

Formula F = Base;

3401

F.BaseGV = GV;

3402

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))

3403

return;

3404

if (IsScaledReg)

3405

F.ScaledReg = G;

3406

else

3407

F.BaseRegs[Idx] = G;

3408

(void)InsertFormula(LU, LUIdx, F);

3409

}

3410

3411

/// GenerateSymbolicOffsets - Generate reuse formulae using symbolic offsets.

3412

void LSRInstance::GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx,

3413

Formula Base) {

3414

// We can't add a symbolic offset if the address already contains one.

3415

if (Base.BaseGV) return;

3416

3417

for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)

3418

GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, i);

3419

if (Base.Scale == 1)

3420

GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, /* Idx */ -1,

3421

/* IsScaledReg */ true);

3422

}

3423

3424

/// \brief Helper function for LSRInstance::GenerateConstantOffsets.

3425

void LSRInstance::GenerateConstantOffsetsImpl(

3426

LSRUse &LU, unsigned LUIdx, const Formula &Base,

3427

const SmallVectorImpl<int64_t> &Worklist, size_t Idx, bool IsScaledReg) {

3428

const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];

3429

for (SmallVectorImpl<int64_t>::const_iterator I = Worklist.begin(),

3430

E = Worklist.end();

3431

I != E; ++I) {

3432

Formula F = Base;

3433

F.BaseOffset = (uint64_t)Base.BaseOffset - *I;

3434

if (isLegalUse(TTI, LU.MinOffset - *I, LU.MaxOffset - *I, LU.Kind,

3435

LU.AccessTy, F)) {

3436

// Add the offset to the base register.

3437

const SCEV *NewG = SE.getAddExpr(SE.getConstant(G->getType(), *I), G);

3438

// If it cancelled out, drop the base register, otherwise update it.

3439

if (NewG->isZero()) {

3440

if (IsScaledReg) {

3441

F.Scale = 0;

3442

F.ScaledReg = nullptr;

3443

} else

3444

F.DeleteBaseReg(F.BaseRegs[Idx]);

3445

F.Canonicalize();

3446

} else if (IsScaledReg)

3447

F.ScaledReg = NewG;

3448

else

3449

F.BaseRegs[Idx] = NewG;

3450

3451

(void)InsertFormula(LU, LUIdx, F);

3452

}

3453

}

3454

3455

int64_t Imm = ExtractImmediate(G, SE);

3456

if (G->isZero() || Imm == 0)

3457

return;

3458

Formula F = Base;

3459

F.BaseOffset = (uint64_t)F.BaseOffset + Imm;

3460

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))

3461

return;

3462

if (IsScaledReg)

3463

F.ScaledReg = G;

3464

else

3465

F.BaseRegs[Idx] = G;

3466

(void)InsertFormula(LU, LUIdx, F);

3467

}

3468

3469

/// GenerateConstantOffsets - Generate reuse formulae using symbolic offsets.

3470

void LSRInstance::GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx,

3471

Formula Base) {

3472

// TODO: For now, just add the min and max offset, because it usually isn't

3473

// worthwhile looking at everything inbetween.

3474

SmallVector<int64_t, 2> Worklist;

3475

Worklist.push_back(LU.MinOffset);

3476

if (LU.MaxOffset != LU.MinOffset)

3477

Worklist.push_back(LU.MaxOffset);

3478

3479

for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)

3480

GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, i);

3481

if (Base.Scale == 1)

3482

GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, /* Idx */ -1,

3483

/* IsScaledReg */ true);

3484

}

3485

3486

/// GenerateICmpZeroScales - For ICmpZero, check to see if we can scale up

3487

/// the comparison. For example, x == y -> x*c == y*c.

3488

void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,

3489

Formula Base) {

3490

if (LU.Kind != LSRUse::ICmpZero) return;

3491

3492

// Determine the integer type for the base formula.

3493

Type *IntTy = Base.getType();

3494

if (!IntTy) return;

3495

if (SE.getTypeSizeInBits(IntTy) > 64) return;

3496

3497

// Don't do this if there is more than one offset.

3498

if (LU.MinOffset != LU.MaxOffset) return;

3499

3500

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3500, __PRETTY_FUNCTION__));

3501

3502

// Check each interesting stride.

3503

for (SmallSetVector<int64_t, 8>::const_iterator

3504

I = Factors.begin(), E = Factors.end(); I != E; ++I) {

3505

int64_t Factor = *I;

3506

3507

// Check that the multiplication doesn't overflow.

3508

if (Base.BaseOffset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)

3509

continue;

3510

int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor;

3511

if (NewBaseOffset / Factor != Base.BaseOffset)

3512

continue;

3513

// If the offset will be truncated at this use, check that it is in bounds.

3514

if (!IntTy->isPointerTy() &&

3515

!ConstantInt::isValueValidForType(IntTy, NewBaseOffset))

3516

continue;

3517

3518

// Check that multiplying with the use offset doesn't overflow.

3519

int64_t Offset = LU.MinOffset;

3520

if (Offset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)

3521

continue;

3522

Offset = (uint64_t)Offset * Factor;

3523

if (Offset / Factor != LU.MinOffset)

3524

continue;

3525

// If the offset will be truncated at this use, check that it is in bounds.

3526

if (!IntTy->isPointerTy() &&

3527

!ConstantInt::isValueValidForType(IntTy, Offset))

3528

continue;

3529

3530

Formula F = Base;

3531

F.BaseOffset = NewBaseOffset;

3532

3533

// Check that this scale is legal.

3534

if (!isLegalUse(TTI, Offset, Offset, LU.Kind, LU.AccessTy, F))

3535

continue;

3536

3537

// Compensate for the use having MinOffset built into it.

3538

F.BaseOffset = (uint64_t)F.BaseOffset + Offset - LU.MinOffset;

3539

3540

const SCEV *FactorS = SE.getConstant(IntTy, Factor);

3541

3542

// Check that multiplying with each base register doesn't overflow.

3543

for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) {

3544

F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS);

3545

if (getExactSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i])

3546

goto next;

3547

}

3548

3549

// Check that multiplying with the scaled register doesn't overflow.

3550

if (F.ScaledReg) {

3551

F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS);

3552

if (getExactSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg)

3553

continue;

3554

}

3555

3556

// Check that multiplying with the unfolded offset doesn't overflow.

3557

if (F.UnfoldedOffset != 0) {

3558

if (F.UnfoldedOffset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)

3559

continue;

3560

F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor;

3561

if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset)

3562

continue;

3563

// If the offset will be truncated, check that it is in bounds.

3564

if (!IntTy->isPointerTy() &&

3565

!ConstantInt::isValueValidForType(IntTy, F.UnfoldedOffset))

3566

continue;

3567

}

3568

3569

// If we make it here and it's legal, add it.

3570

(void)InsertFormula(LU, LUIdx, F);

3571

next:;

3572

}

3573

}

3574

3575

/// GenerateScales - Generate stride factor reuse formulae by making use of

3576

/// scaled-offset address modes, for example.

3577

void LSRInstance::GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base) {

3578

// Determine the integer type for the base formula.

3579

Type *IntTy = Base.getType();

3580

if (!IntTy) return;

3581

3582

// If this Formula already has a scaled register, we can't add another one.

3583

// Try to unscale the formula to generate a better scale.

3584

if (Base.Scale != 0 && !Base.Unscale())

3585

return;

3586

3587

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3587, __PRETTY_FUNCTION__));

3588

3589

// Check each interesting stride.

3590

for (SmallSetVector<int64_t, 8>::const_iterator

3591

I = Factors.begin(), E = Factors.end(); I != E; ++I) {

3592

int64_t Factor = *I;

3593

3594

Base.Scale = Factor;

3595

Base.HasBaseReg = Base.BaseRegs.size() > 1;

3596

// Check whether this scale is going to be legal.

3597

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,

3598

Base)) {

3599

// As a special-case, handle special out-of-loop Basic users specially.

3600

// TODO: Reconsider this special case.

3601

if (LU.Kind == LSRUse::Basic &&

3602

isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LSRUse::Special,

3603

LU.AccessTy, Base) &&

3604

LU.AllFixupsOutsideLoop)

3605

LU.Kind = LSRUse::Special;

3606

else

3607

continue;

3608

}

3609

// For an ICmpZero, negating a solitary base register won't lead to

3610

// new solutions.

3611

if (LU.Kind == LSRUse::ICmpZero &&

3612

!Base.HasBaseReg && Base.BaseOffset == 0 && !Base.BaseGV)

3613

continue;

3614

// For each addrec base reg, apply the scale, if possible.

3615

for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)

3616

if (const SCEVAddRecExpr *AR =

3617

dyn_cast<SCEVAddRecExpr>(Base.BaseRegs[i])) {

3618

const SCEV *FactorS = SE.getConstant(IntTy, Factor);

3619

if (FactorS->isZero())

3620

continue;

3621

// Divide out the factor, ignoring high bits, since we'll be

3622

// scaling the value back up in the end.

3623

if (const SCEV *Quotient = getExactSDiv(AR, FactorS, SE, true)) {

3624

// TODO: This could be optimized to avoid all the copying.

3625

Formula F = Base;

3626

F.ScaledReg = Quotient;

3627

F.DeleteBaseReg(F.BaseRegs[i]);

3628

// The canonical representation of 1*reg is reg, which is already in

3629

// Base. In that case, do not try to insert the formula, it will be

3630

// rejected anyway.

3631

if (F.Scale == 1 && F.BaseRegs.empty())

3632

continue;

3633

(void)InsertFormula(LU, LUIdx, F);

3634

}

3635

}

3636

}

3637

}

3638

3639

/// GenerateTruncates - Generate reuse formulae from different IV types.

3640

void LSRInstance::GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base) {

3641

// Don't bother truncating symbolic values.

3642

if (Base.BaseGV) return;

3643

3644

// Determine the integer type for the base formula.

3645

Type *DstTy = Base.getType();

3646

if (!DstTy) return;

3647

DstTy = SE.getEffectiveSCEVType(DstTy);

3648

3649

for (SmallSetVector<Type *, 4>::const_iterator

3650

I = Types.begin(), E = Types.end(); I != E; ++I) {

3651

Type *SrcTy = *I;

3652

if (SrcTy != DstTy && TTI.isTruncateFree(SrcTy, DstTy)) {

3653

Formula F = Base;

3654

3655

if (F.ScaledReg) F.ScaledReg = SE.getAnyExtendExpr(F.ScaledReg, *I);

3656

for (SmallVectorImpl<const SCEV *>::iterator J = F.BaseRegs.begin(),

3657

JE = F.BaseRegs.end(); J != JE; ++J)

3658

*J = SE.getAnyExtendExpr(*J, SrcTy);

3659

3660

// TODO: This assumes we've done basic processing on all uses and

3661

// have an idea what the register usage is.

3662

if (!F.hasRegsUsedByUsesOtherThan(LUIdx, RegUses))

3663

continue;

3664

3665

(void)InsertFormula(LU, LUIdx, F);

3666

}

3667

}

3668

}

3669

3670

namespace {

3671

3672

/// WorkItem - Helper class for GenerateCrossUseConstantOffsets. It's used to

3673

/// defer modifications so that the search phase doesn't have to worry about

3674

/// the data structures moving underneath it.

3675

struct WorkItem {

3676

size_t LUIdx;

3677

int64_t Imm;

3678

const SCEV *OrigReg;

3679

3680

WorkItem(size_t LI, int64_t I, const SCEV *R)

3681

: LUIdx(LI), Imm(I), OrigReg(R) {}

3682

3683

void print(raw_ostream &OS) const;

3684

void dump() const;

3685

};

3686

3687

}

3688

3689

void WorkItem::print(raw_ostream &OS) const {

3690

OS << "in formulae referencing " << *OrigReg << " in use " << LUIdx

3691

<< " , add offset " << Imm;

3692

}

3693

3694

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

3695

void WorkItem::dump() const {

3696

print(errs()); errs() << '\n';

3697

}

3698

#endif

3699

3700

/// GenerateCrossUseConstantOffsets - Look for registers which are a constant

3701

/// distance apart and try to form reuse opportunities between them.

3702

void LSRInstance::GenerateCrossUseConstantOffsets() {

3703

// Group the registers by their value without any added constant offset.

3704

typedef std::map<int64_t, const SCEV *> ImmMapTy;

3705

typedef DenseMap<const SCEV *, ImmMapTy> RegMapTy;

3706

RegMapTy Map;

3707

DenseMap<const SCEV *, SmallBitVector> UsedByIndicesMap;

3708

SmallVector<const SCEV *, 8> Sequence;

3709

for (RegUseTracker::const_iterator I = RegUses.begin(), E = RegUses.end();

3710

I != E; ++I) {

3711

const SCEV *Reg = *I;

3712

int64_t Imm = ExtractImmediate(Reg, SE);

3713

std::pair<RegMapTy::iterator, bool> Pair =

3714

Map.insert(std::make_pair(Reg, ImmMapTy()));

3715

if (Pair.second)

3716

Sequence.push_back(Reg);

3717

Pair.first->second.insert(std::make_pair(Imm, *I));

3718

UsedByIndicesMap[Reg] |= RegUses.getUsedByIndices(*I);

3719

}

3720

3721

// Now examine each set of registers with the same base value. Build up

3722

// a list of work to do and do the work in a separate step so that we're

3723

// not adding formulae and register counts while we're searching.

3724

SmallVector<WorkItem, 32> WorkItems;

3725

SmallSet<std::pair<size_t, int64_t>, 32> UniqueItems;

3726

for (SmallVectorImpl<const SCEV *>::const_iterator I = Sequence.begin(),

3727

E = Sequence.end(); I != E; ++I) {

3728

const SCEV *Reg = *I;

3729

const ImmMapTy &Imms = Map.find(Reg)->second;

3730

3731

// It's not worthwhile looking for reuse if there's only one offset.

3732

if (Imms.size() == 1)

3733

continue;

3734

3735

DEBUG(dbgs() << "Generating cross-use offsets for " << *Reg << ':';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (ImmMapTy::const_iterator J =
Imms.begin(), JE = Imms.end(); J != JE; ++J) dbgs() <<
' ' << J->first; dbgs() << '\n'; } } while (0
)

3736

for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end();do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (ImmMapTy::const_iterator J =
Imms.begin(), JE = Imms.end(); J != JE; ++J) dbgs() <<
' ' << J->first; dbgs() << '\n'; } } while (0
)

3737

J != JE; ++J)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (ImmMapTy::const_iterator J =
Imms.begin(), JE = Imms.end(); J != JE; ++J) dbgs() <<
' ' << J->first; dbgs() << '\n'; } } while (0
)

3738

dbgs() << ' ' << J->first;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (ImmMapTy::const_iterator J =
Imms.begin(), JE = Imms.end(); J != JE; ++J) dbgs() <<
' ' << J->first; dbgs() << '\n'; } } while (0
)

3739

dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (ImmMapTy::const_iterator J =
Imms.begin(), JE = Imms.end(); J != JE; ++J) dbgs() <<
' ' << J->first; dbgs() << '\n'; } } while (0
);

3740

3741

// Examine each offset.

3742

for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end();

3743

J != JE; ++J) {

3744

const SCEV *OrigReg = J->second;

3745

3746

int64_t JImm = J->first;

3747

const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(OrigReg);

3748

3749

if (!isa<SCEVConstant>(OrigReg) &&

3750

UsedByIndicesMap[Reg].count() == 1) {

3751

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);

3752

continue;

3753

}

3754

3755

// Conservatively examine offsets between this orig reg a few selected

3756

// other orig regs.

3757

ImmMapTy::const_iterator OtherImms[] = {

3758

Imms.begin(), std::prev(Imms.end()),

3759

Imms.lower_bound((Imms.begin()->first + std::prev(Imms.end())->first) /

3760

3761

};

3762

for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) {

3763

ImmMapTy::const_iterator M = OtherImms[i];

3764

if (M == J || M == JE) continue;

3765

3766

// Compute the difference between the two.

3767

int64_t Imm = (uint64_t)JImm - M->first;

3768

for (int LUIdx = UsedByIndices.find_first(); LUIdx != -1;

3769

LUIdx = UsedByIndices.find_next(LUIdx))

3770

// Make a memo of this use, offset, and register tuple.

3771

if (UniqueItems.insert(std::make_pair(LUIdx, Imm)).second)

3772

WorkItems.push_back(WorkItem(LUIdx, Imm, OrigReg));

3773

}

3774

}

3775

}

3776

3777

Map.clear();

3778

Sequence.clear();

3779

UsedByIndicesMap.clear();

3780

UniqueItems.clear();

3781

3782

// Now iterate through the worklist and add new formulae.

3783

for (SmallVectorImpl<WorkItem>::const_iterator I = WorkItems.begin(),

3784

E = WorkItems.end(); I != E; ++I) {

3785

const WorkItem &WI = *I;

3786

size_t LUIdx = WI.LUIdx;

3787

LSRUse &LU = Uses[LUIdx];

3788

int64_t Imm = WI.Imm;

3789

const SCEV *OrigReg = WI.OrigReg;

3790

3791

Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType());

3792

const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, -(uint64_t)Imm));

3793

unsigned BitWidth = SE.getTypeSizeInBits(IntTy);

3794

3795

// TODO: Use a more targeted data structure.

3796

for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) {

3797

Formula F = LU.Formulae[L];

3798

// FIXME: The code for the scaled and unscaled registers looks

3799

// very similar but slightly different. Investigate if they

3800

// could be merged. That way, we would not have to unscale the

3801

// Formula.

3802

F.Unscale();

3803

// Use the immediate in the scaled register.

3804

if (F.ScaledReg == OrigReg) {

3805

int64_t Offset = (uint64_t)F.BaseOffset + Imm * (uint64_t)F.Scale;

3806

// Don't create 50 + reg(-50).

3807

if (F.referencesReg(SE.getSCEV(

3808

ConstantInt::get(IntTy, -(uint64_t)Offset))))

3809

continue;

3810

Formula NewF = F;

3811

NewF.BaseOffset = Offset;

3812

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,

3813

NewF))

3814

continue;

3815

NewF.ScaledReg = SE.getAddExpr(NegImmS, NewF.ScaledReg);

3816

3817

// If the new scale is a constant in a register, and adding the constant

3818

// value to the immediate would produce a value closer to zero than the

3819

// immediate itself, then the formula isn't worthwhile.

3820

if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewF.ScaledReg))

3821

if (C->getValue()->isNegative() !=

3822

(NewF.BaseOffset < 0) &&

3823

(C->getValue()->getValue().abs() * APInt(BitWidth, F.Scale))

3824

.ule(std::abs(NewF.BaseOffset)))

3825

continue;

3826

3827

// OK, looks good.

3828

NewF.Canonicalize();

3829

(void)InsertFormula(LU, LUIdx, NewF);

3830

} else {

3831

// Use the immediate in a base register.

3832

for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) {

3833

const SCEV *BaseReg = F.BaseRegs[N];

3834

if (BaseReg != OrigReg)

3835

continue;

3836

Formula NewF = F;

3837

NewF.BaseOffset = (uint64_t)NewF.BaseOffset + Imm;

3838

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset,

3839

LU.Kind, LU.AccessTy, NewF)) {

3840

if (!TTI.isLegalAddImmediate((uint64_t)NewF.UnfoldedOffset + Imm))

3841

continue;

3842

NewF = F;

3843

NewF.UnfoldedOffset = (uint64_t)NewF.UnfoldedOffset + Imm;

3844

}

3845

NewF.BaseRegs[N] = SE.getAddExpr(NegImmS, BaseReg);

3846

3847

// If the new formula has a constant in a register, and adding the

3848

// constant value to the immediate would produce a value closer to

3849

// zero than the immediate itself, then the formula isn't worthwhile.

3850

for (SmallVectorImpl<const SCEV *>::const_iterator

3851

J = NewF.BaseRegs.begin(), JE = NewF.BaseRegs.end();

3852

J != JE; ++J)

3853

if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*J))

3854

if ((C->getValue()->getValue() + NewF.BaseOffset).abs().slt(

3855

std::abs(NewF.BaseOffset)) &&

3856

(C->getValue()->getValue() +

3857

NewF.BaseOffset).countTrailingZeros() >=

3858

countTrailingZeros<uint64_t>(NewF.BaseOffset))

3859

goto skip_formula;

3860

3861

// Ok, looks good.

3862

NewF.Canonicalize();

3863

(void)InsertFormula(LU, LUIdx, NewF);

3864

break;

3865

skip_formula:;

3866

}

3867

}

3868

}

3869

}

3870

}

3871

3872

/// GenerateAllReuseFormulae - Generate formulae for each use.

3873

void

3874

LSRInstance::GenerateAllReuseFormulae() {

3875

// This is split into multiple loops so that hasRegsUsedByUsesOtherThan

3876

// queries are more precise.

3877

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

3878

LSRUse &LU = Uses[LUIdx];

3879

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3880

GenerateReassociations(LU, LUIdx, LU.Formulae[i]);

3881

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3882

GenerateCombinations(LU, LUIdx, LU.Formulae[i]);

3883

}

3884

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

3885

LSRUse &LU = Uses[LUIdx];

3886

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3887

GenerateSymbolicOffsets(LU, LUIdx, LU.Formulae[i]);

3888

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3889

GenerateConstantOffsets(LU, LUIdx, LU.Formulae[i]);

3890

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3891

GenerateICmpZeroScales(LU, LUIdx, LU.Formulae[i]);

3892

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3893

GenerateScales(LU, LUIdx, LU.Formulae[i]);

3894

}

3895

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

3896

LSRUse &LU = Uses[LUIdx];

3897

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3898

GenerateTruncates(LU, LUIdx, LU.Formulae[i]);

3899

}

3900

3901

GenerateCrossUseConstantOffsets();

3902

3903

DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (0)

3904

"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)

3905

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (0);

3906

}

3907

3908

/// If there are multiple formulae with the same set of registers used

3909

/// by other uses, pick the best one and delete the others.

3910

void LSRInstance::FilterOutUndesirableDedicatedRegisters() {

3911

DenseSet<const SCEV *> VisitedRegs;

3912

SmallPtrSet<const SCEV *, 16> Regs;

3913

SmallPtrSet<const SCEV *, 16> LoserRegs;

3914

#ifndef NDEBUG

3915

bool ChangedFormulae = false;

3916

#endif

3917

3918

// Collect the best formula for each unique set of shared registers. This

3919

// is reset for each use.

3920

typedef DenseMap<SmallVector<const SCEV *, 4>, size_t, UniquifierDenseMapInfo>

3921

BestFormulaeTy;

3922

BestFormulaeTy BestFormulae;

3923

3924

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

3925

LSRUse &LU = Uses[LUIdx];

3926

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);

3927

3928

bool Any = false;

3929

for (size_t FIdx = 0, NumForms = LU.Formulae.size();

3930

FIdx != NumForms; ++FIdx) {

3931

Formula &F = LU.Formulae[FIdx];

3932

3933

// Some formulas are instant losers. For example, they may depend on

3934

// nonexistent AddRecs from other loops. These need to be filtered

3935

// immediately, otherwise heuristics could choose them over others leading

3936

// to an unsatisfactory solution. Passing LoserRegs into RateFormula here

3937

// avoids the need to recompute this information across formulae using the

3938

// same bad AddRec. Passing LoserRegs is also essential unless we remove

3939

// the corresponding bad register from the Regs set.

3940

Cost CostF;

3941

Regs.clear();

3942

CostF.RateFormula(TTI, F, Regs, VisitedRegs, L, LU.Offsets, SE, DT, LU,

3943

&LoserRegs);

3944

if (CostF.isLoser()) {

3945

// During initial formula generation, undesirable formulae are generated

3946

// by uses within other loops that have some non-trivial address mode or

3947

// use the postinc form of the IV. LSR needs to provide these formulae

3948

// as the basis of rediscovering the desired formula that uses an AddRec

3949

// corresponding to the existing phi. Once all formulae have been

3950

// generated, these initial losers may be pruned.

3951

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)

3952

dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering loser "; F.print
(dbgs()); dbgs() << "\n"; } } while (0);

3953

}

3954

else {

3955

SmallVector<const SCEV *, 4> Key;

3956

for (SmallVectorImpl<const SCEV *>::const_iterator J = F.BaseRegs.begin(),

3957

JE = F.BaseRegs.end(); J != JE; ++J) {

3958

const SCEV *Reg = *J;

3959

if (RegUses.isRegUsedByUsesOtherThan(Reg, LUIdx))

3960

Key.push_back(Reg);

3961

}

3962

if (F.ScaledReg &&

3963

RegUses.isRegUsedByUsesOtherThan(F.ScaledReg, LUIdx))

3964

Key.push_back(F.ScaledReg);

3965

// Unstable sort by host order ok, because this is only used for

3966

// uniquifying.

3967

std::sort(Key.begin(), Key.end());

3968

3969

std::pair<BestFormulaeTy::const_iterator, bool> P =

3970

BestFormulae.insert(std::make_pair(Key, FIdx));

3971

if (P.second)

3972

continue;

3973

3974

Formula &Best = LU.Formulae[P.first->second];

3975

3976

Cost CostBest;

3977

Regs.clear();

3978

CostBest.RateFormula(TTI, Best, Regs, VisitedRegs, L, LU.Offsets, SE,

3979

DT, LU);

3980

if (CostF < CostBest)

3981

std::swap(F, Best);

3982

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)

3983

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)

3984

" 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)

3985

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);

3986

}

3987

#ifndef NDEBUG

3988

ChangedFormulae = true;

3989

#endif

3990

LU.DeleteFormula(F);

3991

--FIdx;

3992

--NumForms;

3993

Any = true;

3994

}

3995

3996

// Now that we've filtered out some formulae, recompute the Regs set.

3997

if (Any)

3998

LU.RecomputeRegs(LUIdx, RegUses);

3999

4000

// Reset this to prepare for the next use.

4001

BestFormulae.clear();

4002

}

4003

4004

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)

4005

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)

4006

"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)

4007

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)

4008

})do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (0);

4009

}

4010

4011

// This is a rough guess that seems to work fairly well.

4012

static const size_t ComplexityLimit = UINT16_MAX(65535);

4013

4014

/// EstimateSearchSpaceComplexity - Estimate the worst-case number of

4015

/// solutions the solver might have to consider. It almost never considers

4016

/// this many solutions because it prune the search space, but the pruning

4017

/// isn't always sufficient.

4018

size_t LSRInstance::EstimateSearchSpaceComplexity() const {

4019

size_t Power = 1;

4020

for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(),

4021

E = Uses.end(); I != E; ++I) {

4022

size_t FSize = I->Formulae.size();

4023

if (FSize >= ComplexityLimit) {

4024

Power = ComplexityLimit;

4025

break;

4026

}

4027

Power *= FSize;

4028

if (Power >= ComplexityLimit)

4029

break;

4030

}

4031

return Power;

4032

}

4033

4034

/// NarrowSearchSpaceByDetectingSupersets - When one formula uses a superset

4035

/// of the registers of another formula, it won't help reduce register

4036

/// pressure (though it may not necessarily hurt register pressure); remove

4037

/// it to simplify the system.

4038

void LSRInstance::NarrowSearchSpaceByDetectingSupersets() {

4039

if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {

4040

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);

4041

4042

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)

4043

"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)

4044

"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);

4045

4046

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

4047

LSRUse &LU = Uses[LUIdx];

4048

bool Any = false;

4049

for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {

4050

Formula &F = LU.Formulae[i];

4051

// Look for a formula with a constant or GV in a register. If the use

4052

// also has a formula with that same value in an immediate field,

4053

// delete the one that uses a register.

4054

for (SmallVectorImpl<const SCEV *>::const_iterator

4055

I = F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) {

4056

if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*I)) {

4057

Formula NewF = F;

4058

NewF.BaseOffset += C->getValue()->getSExtValue();

4059

NewF.BaseRegs.erase(NewF.BaseRegs.begin() +

4060

(I - F.BaseRegs.begin()));

4061

if (LU.HasFormulaWithSameRegs(NewF)) {

4062

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);

4063

LU.DeleteFormula(F);

4064

--i;

4065

--e;

4066

Any = true;

4067

break;

4068

}

4069

} else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(*I)) {

4070

if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue()))

4071

if (!F.BaseGV) {

4072

Formula NewF = F;

4073

NewF.BaseGV = GV;

4074

NewF.BaseRegs.erase(NewF.BaseRegs.begin() +

4075

(I - F.BaseRegs.begin()));

4076

if (LU.HasFormulaWithSameRegs(NewF)) {

4077

DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)

4078

dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0);

4079

LU.DeleteFormula(F);

4080

--i;

4081

--e;

4082

Any = true;

4083

break;

4084

}

4085

}

4086

}

4087

}

4088

}

4089

if (Any)

4090

LU.RecomputeRegs(LUIdx, RegUses);

4091

}

4092

4093

DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)

4094

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0);

4095

}

4096

}

4097

4098

/// NarrowSearchSpaceByCollapsingUnrolledCode - When there are many registers

4099

/// for expressions like A, A+1, A+2, etc., allocate a single register for

4100

/// them.

4101

void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() {

4102

if (EstimateSearchSpaceComplexity() < ComplexityLimit)

4103

return;

4104

4105

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)

4106

"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)

4107

"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);

4108

4109

// This is especially useful for unrolled loops.

4110

4111

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

4112

LSRUse &LU = Uses[LUIdx];

4113

for (SmallVectorImpl<Formula>::const_iterator I = LU.Formulae.begin(),

4114

E = LU.Formulae.end(); I != E; ++I) {

4115

const Formula &F = *I;

4116

if (F.BaseOffset == 0 || (F.Scale != 0 && F.Scale != 1))

4117

continue;

4118

4119

LSRUse *LUThatHas = FindUseWithSimilarFormula(F, LU);

4120

if (!LUThatHas)

4121

continue;

4122

4123

if (!reconcileNewOffset(*LUThatHas, F.BaseOffset, /*HasBaseReg=*/ false,

4124

LU.Kind, LU.AccessTy))

4125

continue;

4126

4127

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);

4128

4129

LUThatHas->AllFixupsOutsideLoop &= LU.AllFixupsOutsideLoop;

4130

4131

// Update the relocs to reference the new use.

4132

for (SmallVectorImpl<LSRFixup>::iterator I = Fixups.begin(),

4133

E = Fixups.end(); I != E; ++I) {

4134

LSRFixup &Fixup = *I;

4135

if (Fixup.LUIdx == LUIdx) {

4136

Fixup.LUIdx = LUThatHas - &Uses.front();

4137

Fixup.Offset += F.BaseOffset;

4138

// Add the new offset to LUThatHas' offset list.

4139

if (LUThatHas->Offsets.back() != Fixup.Offset) {

4140

LUThatHas->Offsets.push_back(Fixup.Offset);

4141

if (Fixup.Offset > LUThatHas->MaxOffset)

4142

LUThatHas->MaxOffset = Fixup.Offset;

4143

if (Fixup.Offset < LUThatHas->MinOffset)

4144

LUThatHas->MinOffset = Fixup.Offset;

4145

}

4146

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);

4147

}

4148

if (Fixup.LUIdx == NumUses-1)

4149

Fixup.LUIdx = LUIdx;

4150

}

4151

4152

// Delete formulae from the new use which are no longer legal.

4153

bool Any = false;

4154

for (size_t i = 0, e = LUThatHas->Formulae.size(); i != e; ++i) {

4155

Formula &F = LUThatHas->Formulae[i];

4156

if (!isLegalUse(TTI, LUThatHas->MinOffset, LUThatHas->MaxOffset,

4157

LUThatHas->Kind, LUThatHas->AccessTy, F)) {

4158

DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)

4159

dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0);

4160

LUThatHas->DeleteFormula(F);

4161

--i;

4162

--e;

4163

Any = true;

4164

}

4165

}

4166

4167

if (Any)

4168

LUThatHas->RecomputeRegs(LUThatHas - &Uses.front(), RegUses);

4169

4170

// Delete the old use.

4171

DeleteUse(LU, LUIdx);

4172

--LUIdx;

4173

--NumUses;

4174

break;

4175

}

4176

}

4177

4178

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);

4179

}

4180

4181

/// NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters - Call

4182

/// FilterOutUndesirableDedicatedRegisters again, if necessary, now that

4183

/// we've done more filtering, as it may be able to find more formulae to

4184

/// eliminate.

4185

void LSRInstance::NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(){

4186

if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {

4187

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);

4188

4189

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)

4190

"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);

4191

4192

FilterOutUndesirableDedicatedRegisters();

4193

4194

DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)

4195

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0);

4196

}

4197

}

4198

4199

/// NarrowSearchSpaceByPickingWinnerRegs - Pick a register which seems likely

4200

/// to be profitable, and then in any use which has any reference to that

4201

/// register, delete all formulae which do not reference that register.

4202

void LSRInstance::NarrowSearchSpaceByPickingWinnerRegs() {

4203

// With all other options exhausted, loop until the system is simple

4204

// enough to handle.

4205

SmallPtrSet<const SCEV *, 4> Taken;

4206

while (EstimateSearchSpaceComplexity() >= ComplexityLimit) {

←

Loop condition is true. Entering loop body

→

←

Loop condition is true. Entering loop body

→

←

Loop condition is true. Entering loop body

→

←

Loop condition is true. Entering loop body

→

4207

// Ok, we have too many of formulae on our hands to conveniently handle.

4208

// Use a rough heuristic to thin out the list.

4209

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);

4210

4211

// Pick the register which is used by the most LSRUses, which is likely

4212

// to be a good reuse register candidate.

4213

const SCEV *Best = nullptr;

←

'Best' initialized to a null pointer value

→

4214

unsigned BestNum = 0;

4215

for (RegUseTracker::const_iterator I = RegUses.begin(), E = RegUses.end();

←

Loop condition is false. Execution continues on line 4231

→

←

Loop condition is false. Execution continues on line 4231

→

←

Loop condition is false. Execution continues on line 4231

→

←

Loop condition is false. Execution continues on line 4231

→

4216

I != E; ++I) {

←

Assuming 'I' is equal to 'E'

→

←

Assuming 'I' is equal to 'E'

→

←

Assuming 'I' is equal to 'E'

→

←

Assuming 'I' is equal to 'E'

→

4217

const SCEV *Reg = *I;

4218

if (Taken.count(Reg))

4219

continue;

4220

if (!Best)

4221

Best = Reg;

4222

else {

4223

unsigned Count = RegUses.getUsedByIndices(Reg).count();

4224

if (Count > BestNum) {

4225

Best = Reg;

4226

BestNum = Count;

4227

}

4228

}

4229

}

4230

4231

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)

←

Within the expansion of the macro 'DEBUG':

a	Forming reference to null pointer

4232

<< " 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);

4233

Taken.insert(Best);

4234

4235

// In any use with formulae which references this register, delete formulae

4236

// which don't reference it.

4237

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

←

Assuming 'LUIdx' is equal to 'NumUses'

→

←

Loop condition is false. Execution continues on line 4259

→

←

Assuming 'LUIdx' is equal to 'NumUses'

→

←

Loop condition is false. Execution continues on line 4259

→

←

Assuming 'LUIdx' is equal to 'NumUses'

→

←

Loop condition is false. Execution continues on line 4259

→

4238

LSRUse &LU = Uses[LUIdx];

4239

if (!LU.Regs.count(Best)) continue;

4240

4241

bool Any = false;

4242

for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {

4243

Formula &F = LU.Formulae[i];

4244

if (!F.referencesReg(Best)) {

4245

4246

LU.DeleteFormula(F);

4247

--e;

4248

--i;

4249

Any = true;

4250

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4250, __PRETTY_FUNCTION__));

4251

continue;

4252

}

4253

}

4254

4255

if (Any)

4256

LU.RecomputeRegs(LUIdx, RegUses);

4257

}

4258

4259

DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)

4260

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0);

4261

}

4262

}

4263

4264

/// NarrowSearchSpaceUsingHeuristics - If there are an extraordinary number of

4265

/// formulae to choose from, use some rough heuristics to prune down the number

4266

/// of formulae. This keeps the main solver from taking an extraordinary amount

4267

/// of time in some worst-case scenarios.

4268

void LSRInstance::NarrowSearchSpaceUsingHeuristics() {

4269

NarrowSearchSpaceByDetectingSupersets();

4270

NarrowSearchSpaceByCollapsingUnrolledCode();

4271

NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();

4272

NarrowSearchSpaceByPickingWinnerRegs();

Calling 'LSRInstance::NarrowSearchSpaceByPickingWinnerRegs'

→

4273

}

4274

4275

/// SolveRecurse - This is the recursive solver.

4276

void LSRInstance::SolveRecurse(SmallVectorImpl<const Formula *> &Solution,

4277

Cost &SolutionCost,

4278

SmallVectorImpl<const Formula *> &Workspace,

4279

const Cost &CurCost,

4280

const SmallPtrSet<const SCEV *, 16> &CurRegs,

4281

DenseSet<const SCEV *> &VisitedRegs) const {

4282

// Some ideas:

4283

// - prune more:

4284

// - use more aggressive filtering

4285

// - sort the formula so that the most profitable solutions are found first

4286

// - sort the uses too

4287

// - search faster:

4288

// - don't compute a cost, and then compare. compare while computing a cost

4289

// and bail early.

4290

// - track register sets with SmallBitVector

4291

4292

const LSRUse &LU = Uses[Workspace.size()];

4293

4294

// If this use references any register that's already a part of the

4295

// in-progress solution, consider it a requirement that a formula must

4296

// reference that register in order to be considered. This prunes out

4297

// unprofitable searching.

4298

SmallSetVector<const SCEV *, 4> ReqRegs;

4299

for (const SCEV *S : CurRegs)

4300

if (LU.Regs.count(S))

4301

ReqRegs.insert(S);

4302

4303

SmallPtrSet<const SCEV *, 16> NewRegs;

4304

Cost NewCost;

4305

for (SmallVectorImpl<Formula>::const_iterator I = LU.Formulae.begin(),

4306

E = LU.Formulae.end(); I != E; ++I) {

4307

const Formula &F = *I;

4308

4309

// Ignore formulae which may not be ideal in terms of register reuse of

4310

// ReqRegs. The formula should use all required registers before

4311

// introducing new ones.

4312

int NumReqRegsToFind = std::min(F.getNumRegs(), ReqRegs.size());

4313

for (SmallSetVector<const SCEV *, 4>::const_iterator J = ReqRegs.begin(),

4314

JE = ReqRegs.end(); J != JE; ++J) {

4315

const SCEV *Reg = *J;

4316

if ((F.ScaledReg && F.ScaledReg == Reg) ||

4317

std::find(F.BaseRegs.begin(), F.BaseRegs.end(), Reg) !=

4318

F.BaseRegs.end()) {

4319

--NumReqRegsToFind;

4320

if (NumReqRegsToFind == 0)

4321

break;

4322

}

4323

}

4324

if (NumReqRegsToFind != 0) {

4325

// If none of the formulae satisfied the required registers, then we could

4326

// clear ReqRegs and try again. Currently, we simply give up in this case.

4327

continue;

4328

}

4329

4330

// Evaluate the cost of the current formula. If it's already worse than

4331

// the current best, prune the search at that point.

4332

NewCost = CurCost;

4333

NewRegs = CurRegs;

4334

NewCost.RateFormula(TTI, F, NewRegs, VisitedRegs, L, LU.Offsets, SE, DT,

4335

LU);

4336

if (NewCost < SolutionCost) {

4337

Workspace.push_back(&F);

4338

if (Workspace.size() != Uses.size()) {

4339

SolveRecurse(Solution, SolutionCost, Workspace, NewCost,

4340

NewRegs, VisitedRegs);

4341

if (F.getNumRegs() == 1 && Workspace.size() == 1)

4342

VisitedRegs.insert(F.ScaledReg ? F.ScaledReg : F.BaseRegs[0]);

4343

} else {

4344

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)

4345

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)

4346

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)

4347

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)

4348

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);

4349

4350

SolutionCost = NewCost;

4351

Solution = Workspace;

4352

}

4353

Workspace.pop_back();

4354

}

4355

}

4356

}

4357

4358

/// Solve - Choose one formula from each use. Return the results in the given

4359

/// Solution vector.

4360

void LSRInstance::Solve(SmallVectorImpl<const Formula *> &Solution) const {

4361

SmallVector<const Formula *, 8> Workspace;

4362

Cost SolutionCost;

4363

SolutionCost.Lose();

4364

Cost CurCost;

4365

SmallPtrSet<const SCEV *, 16> CurRegs;

4366

DenseSet<const SCEV *> VisitedRegs;

4367

Workspace.reserve(Uses.size());

4368

4369

// SolveRecurse does all the work.

4370

SolveRecurse(Solution, SolutionCost, Workspace, CurCost,

4371

CurRegs, VisitedRegs);

4372

if (Solution.empty()) {

4373

DEBUG(dbgs() << "\nNo Satisfactory Solution\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nNo Satisfactory Solution\n"
; } } while (0);

4374

return;

4375

}

4376

4377

// Ok, we've now made all our decisions.

4378

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)

4379

"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)

4380

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)

4381

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)

4382

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)

4383

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)

4384

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)

4385

" ";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)

4386

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)

4387

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)

4388

})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);

4389

4390

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4390, __PRETTY_FUNCTION__));

4391

}

4392

4393

/// HoistInsertPosition - Helper for AdjustInsertPositionForExpand. Climb up

4394

/// the dominator tree far as we can go while still being dominated by the

4395

/// input positions. This helps canonicalize the insert position, which

4396

/// encourages sharing.

4397

BasicBlock::iterator

4398

LSRInstance::HoistInsertPosition(BasicBlock::iterator IP,

4399

const SmallVectorImpl<Instruction *> &Inputs)

4400

const {

4401

for (;;) {

4402

const Loop *IPLoop = LI.getLoopFor(IP->getParent());

4403

unsigned IPLoopDepth = IPLoop ? IPLoop->getLoopDepth() : 0;

4404

4405

BasicBlock *IDom;

4406

for (DomTreeNode *Rung = DT.getNode(IP->getParent()); ; ) {

4407

if (!Rung) return IP;

4408

Rung = Rung->getIDom();

4409

if (!Rung) return IP;

4410

IDom = Rung->getBlock();

4411

4412

// Don't climb into a loop though.

4413

const Loop *IDomLoop = LI.getLoopFor(IDom);

4414

unsigned IDomDepth = IDomLoop ? IDomLoop->getLoopDepth() : 0;

4415

if (IDomDepth <= IPLoopDepth &&

4416

(IDomDepth != IPLoopDepth || IDomLoop == IPLoop))

4417

break;

4418

}

4419

4420

bool AllDominate = true;

4421

Instruction *BetterPos = nullptr;

4422

Instruction *Tentative = IDom->getTerminator();

4423

for (SmallVectorImpl<Instruction *>::const_iterator I = Inputs.begin(),

4424

E = Inputs.end(); I != E; ++I) {

4425

Instruction *Inst = *I;

4426

if (Inst == Tentative || !DT.dominates(Inst, Tentative)) {

4427

AllDominate = false;

4428

break;

4429

}

4430

// Attempt to find an insert position in the middle of the block,

4431

// instead of at the end, so that it can be used for other expansions.

4432

if (IDom == Inst->getParent() &&

4433

(!BetterPos || !DT.dominates(Inst, BetterPos)))

4434

BetterPos = std::next(BasicBlock::iterator(Inst));

4435

}

4436

if (!AllDominate)

4437

break;

4438

if (BetterPos)

4439

IP = BetterPos;

4440

else

4441

IP = Tentative;

4442

}

4443

4444

return IP;

4445

}

4446

4447

/// AdjustInsertPositionForExpand - Determine an input position which will be

4448

/// dominated by the operands and which will dominate the result.

4449

BasicBlock::iterator

4450

LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP,

4451

const LSRFixup &LF,

4452

const LSRUse &LU,

4453

SCEVExpander &Rewriter) const {

4454

// Collect some instructions which must be dominated by the

4455

// expanding replacement. These must be dominated by any operands that

4456

// will be required in the expansion.

4457

SmallVector<Instruction *, 4> Inputs;

4458

if (Instruction *I = dyn_cast<Instruction>(LF.OperandValToReplace))

4459

Inputs.push_back(I);

4460

if (LU.Kind == LSRUse::ICmpZero)

4461

if (Instruction *I =

4462

dyn_cast<Instruction>(cast<ICmpInst>(LF.UserInst)->getOperand(1)))

4463

Inputs.push_back(I);

4464

if (LF.PostIncLoops.count(L)) {

4465

if (LF.isUseFullyOutsideLoop(L))

4466

Inputs.push_back(L->getLoopLatch()->getTerminator());

4467

else

4468

Inputs.push_back(IVIncInsertPos);

4469

}

4470

// The expansion must also be dominated by the increment positions of any

4471

// loops it for which it is using post-inc mode.

4472

for (PostIncLoopSet::const_iterator I = LF.PostIncLoops.begin(),

4473

E = LF.PostIncLoops.end(); I != E; ++I) {

4474

const Loop *PIL = *I;

4475

if (PIL == L) continue;

4476

4477

// Be dominated by the loop exit.

4478

SmallVector<BasicBlock *, 4> ExitingBlocks;

4479

PIL->getExitingBlocks(ExitingBlocks);

4480

if (!ExitingBlocks.empty()) {

4481

BasicBlock *BB = ExitingBlocks[0];

4482

for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i)

4483

BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]);

4484

Inputs.push_back(BB->getTerminator());

4485

}

4486

}

4487

4488

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4490, __PRETTY_FUNCTION__))

4489

&& !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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4490, __PRETTY_FUNCTION__))

4490

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4490, __PRETTY_FUNCTION__));

4491

4492

// Then, climb up the immediate dominator tree as far as we can go while

4493

// still being dominated by the input positions.

4494

BasicBlock::iterator IP = HoistInsertPosition(LowestIP, Inputs);

4495

4496

// Don't insert instructions before PHI nodes.

4497

while (isa<PHINode>(IP)) ++IP;

4498

4499

// Ignore landingpad instructions.

4500

while (isa<LandingPadInst>(IP)) ++IP;

4501

4502

// Ignore debug intrinsics.

4503

while (isa<DbgInfoIntrinsic>(IP)) ++IP;

4504

4505

// Set IP below instructions recently inserted by SCEVExpander. This keeps the

4506

// IP consistent across expansions and allows the previously inserted

4507

// instructions to be reused by subsequent expansion.

4508

while (Rewriter.isInsertedInstruction(IP) && IP != LowestIP) ++IP;

4509

4510

return IP;

4511

}

4512

4513

/// Expand - Emit instructions for the leading candidate expression for this

4514

/// LSRUse (this is called "expanding").

4515

Value *LSRInstance::Expand(const LSRFixup &LF,

4516

const Formula &F,

4517

BasicBlock::iterator IP,

4518

SCEVExpander &Rewriter,

4519

SmallVectorImpl<WeakVH> &DeadInsts) const {

4520

const LSRUse &LU = Uses[LF.LUIdx];

4521

if (LU.RigidFormula)

4522

return LF.OperandValToReplace;

4523

4524

// Determine an input position which will be dominated by the operands and

4525

// which will dominate the result.

4526

IP = AdjustInsertPositionForExpand(IP, LF, LU, Rewriter);

4527

4528

// Inform the Rewriter if we have a post-increment use, so that it can

4529

// perform an advantageous expansion.

4530

Rewriter.setPostInc(LF.PostIncLoops);

4531

4532

// This is the type that the user actually needs.

4533

Type *OpTy = LF.OperandValToReplace->getType();

4534

// This will be the type that we'll initially expand to.

4535

Type *Ty = F.getType();

4536

if (!Ty)

4537

// No type known; just expand directly to the ultimate type.

4538

Ty = OpTy;

4539

else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy))

4540

// Expand directly to the ultimate type if it's the right size.

4541

Ty = OpTy;

4542

// This is the type to do integer arithmetic in.

4543

Type *IntTy = SE.getEffectiveSCEVType(Ty);

4544

4545

// Build up a list of operands to add together to form the full base.

4546

SmallVector<const SCEV *, 8> Ops;

4547

4548

// Expand the BaseRegs portion.

4549

for (SmallVectorImpl<const SCEV *>::const_iterator I = F.BaseRegs.begin(),

4550

E = F.BaseRegs.end(); I != E; ++I) {

4551

const SCEV *Reg = *I;

4552

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4552, __PRETTY_FUNCTION__));

4553

4554

// If we're expanding for a post-inc user, make the post-inc adjustment.

4555

PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);

4556

Reg = TransformForPostIncUse(Denormalize, Reg,

4557

LF.UserInst, LF.OperandValToReplace,

4558

Loops, SE, DT);

4559

4560

Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr, IP)));

4561

}

4562

4563

// Expand the ScaledReg portion.

4564

Value *ICmpScaledV = nullptr;

4565

if (F.Scale != 0) {

4566

const SCEV *ScaledS = F.ScaledReg;

4567

4568

// If we're expanding for a post-inc user, make the post-inc adjustment.

4569

PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);

4570

ScaledS = TransformForPostIncUse(Denormalize, ScaledS,

4571

LF.UserInst, LF.OperandValToReplace,

4572

Loops, SE, DT);

4573

4574

if (LU.Kind == LSRUse::ICmpZero) {

4575

// Expand ScaleReg as if it was part of the base regs.

4576

if (F.Scale == 1)

4577

Ops.push_back(

4578

SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP)));

4579

else {

4580

// An interesting way of "folding" with an icmp is to use a negated

4581

// scale, which we'll implement by inserting it into the other operand

4582

// of the icmp.

4583

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4584, __PRETTY_FUNCTION__))

4584

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4584, __PRETTY_FUNCTION__));

4585

ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr, IP);

4586

}

4587

} else {

4588

// Otherwise just expand the scaled register and an explicit scale,

4589

// which is expected to be matched as part of the address.

4590

4591

// Flush the operand list to suppress SCEVExpander hoisting address modes.

4592

// Unless the addressing mode will not be folded.

4593

if (!Ops.empty() && LU.Kind == LSRUse::Address &&

4594

isAMCompletelyFolded(TTI, LU, F)) {

4595

Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);

4596

Ops.clear();

4597

Ops.push_back(SE.getUnknown(FullV));

4598

}

4599

ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP));

4600

if (F.Scale != 1)

4601

ScaledS =

4602

SE.getMulExpr(ScaledS, SE.getConstant(ScaledS->getType(), F.Scale));

4603

Ops.push_back(ScaledS);

4604

}

4605

}

4606

4607

// Expand the GV portion.

4608

if (F.BaseGV) {

4609

// Flush the operand list to suppress SCEVExpander hoisting.

4610

if (!Ops.empty()) {

4611

Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);

4612

Ops.clear();

4613

Ops.push_back(SE.getUnknown(FullV));

4614

}

4615

Ops.push_back(SE.getUnknown(F.BaseGV));

4616

}

4617

4618

// Flush the operand list to suppress SCEVExpander hoisting of both folded and

4619

// unfolded offsets. LSR assumes they both live next to their uses.

4620

if (!Ops.empty()) {

4621

Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);

4622

Ops.clear();

4623

Ops.push_back(SE.getUnknown(FullV));

4624

}

4625

4626

// Expand the immediate portion.

4627

int64_t Offset = (uint64_t)F.BaseOffset + LF.Offset;

4628

if (Offset != 0) {

4629

if (LU.Kind == LSRUse::ICmpZero) {

4630

// The other interesting way of "folding" with an ICmpZero is to use a

4631

// negated immediate.

4632

if (!ICmpScaledV)

4633

ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset);

4634

else {

4635

Ops.push_back(SE.getUnknown(ICmpScaledV));

4636

ICmpScaledV = ConstantInt::get(IntTy, Offset);

4637

}

4638

} else {

4639

// Just add the immediate values. These again are expected to be matched

4640

// as part of the address.

4641

Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, Offset)));

4642

}

4643

}

4644

4645

// Expand the unfolded offset portion.

4646

int64_t UnfoldedOffset = F.UnfoldedOffset;

4647

if (UnfoldedOffset != 0) {

4648

// Just add the immediate values.

4649

Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy,

4650

UnfoldedOffset)));

4651

}

4652

4653

// Emit instructions summing all the operands.

4654

const SCEV *FullS = Ops.empty() ?

4655

SE.getConstant(IntTy, 0) :

4656

SE.getAddExpr(Ops);

4657

Value *FullV = Rewriter.expandCodeFor(FullS, Ty, IP);

4658

4659

// We're done expanding now, so reset the rewriter.

4660

Rewriter.clearPostInc();

4661

4662

// An ICmpZero Formula represents an ICmp which we're handling as a

4663

// comparison against zero. Now that we've expanded an expression for that

4664

// form, update the ICmp's other operand.

4665

if (LU.Kind == LSRUse::ICmpZero) {

4666

ICmpInst *CI = cast<ICmpInst>(LF.UserInst);

4667

DeadInsts.push_back(CI->getOperand(1));

4668

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4669, __PRETTY_FUNCTION__))

4669

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4669, __PRETTY_FUNCTION__));

4670

if (F.Scale == -1) {

4671

if (ICmpScaledV->getType() != OpTy) {

4672

Instruction *Cast =

4673

CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false,

4674

OpTy, false),

4675

ICmpScaledV, OpTy, "tmp", CI);

4676

ICmpScaledV = Cast;

4677

}

4678

CI->setOperand(1, ICmpScaledV);

4679

} else {

4680

// A scale of 1 means that the scale has been expanded as part of the

4681

// base regs.

4682

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4684, __PRETTY_FUNCTION__))

4683

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4684, __PRETTY_FUNCTION__))

4684

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4684, __PRETTY_FUNCTION__));

4685

Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy),

4686

-(uint64_t)Offset);

4687

if (C->getType() != OpTy)

4688

C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,

4689

OpTy, false),

4690

C, OpTy);

4691

4692

CI->setOperand(1, C);

4693

}

4694

}

4695

4696

return FullV;

4697

}

4698

4699

/// RewriteForPHI - Helper for Rewrite. PHI nodes are special because the use

4700

/// of their operands effectively happens in their predecessor blocks, so the

4701

/// expression may need to be expanded in multiple places.

4702

void LSRInstance::RewriteForPHI(PHINode *PN,

4703

const LSRFixup &LF,

4704

const Formula &F,

4705

SCEVExpander &Rewriter,

4706

SmallVectorImpl<WeakVH> &DeadInsts,

4707

Pass *P) const {

4708

DenseMap<BasicBlock *, Value *> Inserted;

4709

for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)

4710

if (PN->getIncomingValue(i) == LF.OperandValToReplace) {

4711

BasicBlock *BB = PN->getIncomingBlock(i);

4712

4713

// If this is a critical edge, split the edge so that we do not insert

4714

// the code on all predecessor/successor paths. We do this unless this

4715

// is the canonical backedge for this loop, which complicates post-inc

4716

// users.

4717

if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&

4718

!isa<IndirectBrInst>(BB->getTerminator())) {

4719

BasicBlock *Parent = PN->getParent();

4720

Loop *PNLoop = LI.getLoopFor(Parent);

4721

if (!PNLoop || Parent != PNLoop->getHeader()) {

4722

// Split the critical edge.

4723

BasicBlock *NewBB = nullptr;

4724

if (!Parent->isLandingPad()) {

4725

NewBB = SplitCriticalEdge(BB, Parent,

4726

CriticalEdgeSplittingOptions(&DT, &LI)

4727

.setMergeIdenticalEdges()

4728

.setDontDeleteUselessPHIs());

4729

} else {

4730

SmallVector<BasicBlock*, 2> NewBBs;

4731

SplitLandingPadPredecessors(Parent, BB, "", "", NewBBs,

4732

/*AliasAnalysis*/ nullptr, &DT, &LI);

4733

NewBB = NewBBs[0];

4734

}

4735

// If NewBB==NULL, then SplitCriticalEdge refused to split because all

4736

// phi predecessors are identical. The simple thing to do is skip

4737

// splitting in this case rather than complicate the API.

4738

if (NewBB) {

4739

// If PN is outside of the loop and BB is in the loop, we want to

4740

// move the block to be immediately before the PHI block, not

4741

// immediately after BB.

4742

if (L->contains(BB) && !L->contains(PN))

4743

NewBB->moveBefore(PN->getParent());

4744

4745

// Splitting the edge can reduce the number of PHI entries we have.

4746

e = PN->getNumIncomingValues();

4747

BB = NewBB;

4748

i = PN->getBasicBlockIndex(BB);

4749

}

4750

}

4751

}

4752

4753

std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =

4754

Inserted.insert(std::make_pair(BB, static_cast<Value *>(nullptr)));

4755

if (!Pair.second)

4756

PN->setIncomingValue(i, Pair.first->second);

4757

else {

4758

Value *FullV = Expand(LF, F, BB->getTerminator(), Rewriter, DeadInsts);

4759

4760

// If this is reuse-by-noop-cast, insert the noop cast.

4761

Type *OpTy = LF.OperandValToReplace->getType();

4762

if (FullV->getType() != OpTy)

4763

FullV =

4764

CastInst::Create(CastInst::getCastOpcode(FullV, false,

4765

OpTy, false),

4766

FullV, LF.OperandValToReplace->getType(),

4767

"tmp", BB->getTerminator());

4768

4769

PN->setIncomingValue(i, FullV);

4770

Pair.first->second = FullV;

4771

}

4772

}

4773

}

4774

4775

/// Rewrite - Emit instructions for the leading candidate expression for this

4776

/// LSRUse (this is called "expanding"), and update the UserInst to reference

4777

/// the newly expanded value.

4778

void LSRInstance::Rewrite(const LSRFixup &LF,

4779

const Formula &F,

4780

SCEVExpander &Rewriter,

4781

SmallVectorImpl<WeakVH> &DeadInsts,

4782

Pass *P) const {

4783

// First, find an insertion point that dominates UserInst. For PHI nodes,

4784

// find the nearest block which dominates all the relevant uses.

4785

if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) {

4786

RewriteForPHI(PN, LF, F, Rewriter, DeadInsts, P);

4787

} else {

4788

Value *FullV = Expand(LF, F, LF.UserInst, Rewriter, DeadInsts);

4789

4790

// If this is reuse-by-noop-cast, insert the noop cast.

4791

Type *OpTy = LF.OperandValToReplace->getType();

4792

if (FullV->getType() != OpTy) {

4793

Instruction *Cast =

4794

CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false),

4795

FullV, OpTy, "tmp", LF.UserInst);

4796

FullV = Cast;

4797

}

4798

4799

// Update the user. ICmpZero is handled specially here (for now) because

4800

// Expand may have updated one of the operands of the icmp already, and

4801

// its new value may happen to be equal to LF.OperandValToReplace, in

4802

// which case doing replaceUsesOfWith leads to replacing both operands

4803

// with the same value. TODO: Reorganize this.

4804

if (Uses[LF.LUIdx].Kind == LSRUse::ICmpZero)

4805

LF.UserInst->setOperand(0, FullV);

4806

else

4807

LF.UserInst->replaceUsesOfWith(LF.OperandValToReplace, FullV);

4808

}

4809

4810

DeadInsts.push_back(LF.OperandValToReplace);

4811

}

4812

4813

/// ImplementSolution - Rewrite all the fixup locations with new values,

4814

/// following the chosen solution.

4815

void

4816

LSRInstance::ImplementSolution(const SmallVectorImpl<const Formula *> &Solution,

4817

Pass *P) {

4818

// Keep track of instructions we may have made dead, so that

4819

// we can remove them after we are done working.

4820

SmallVector<WeakVH, 16> DeadInsts;

4821

4822

SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(),

4823

"lsr");

4824

#ifndef NDEBUG

4825

Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");

4826

#endif

4827

Rewriter.disableCanonicalMode();

4828

Rewriter.enableLSRMode();

4829

Rewriter.setIVIncInsertPos(L, IVIncInsertPos);

4830

4831

// Mark phi nodes that terminate chains so the expander tries to reuse them.

4832

for (SmallVectorImpl<IVChain>::const_iterator ChainI = IVChainVec.begin(),

4833

ChainE = IVChainVec.end(); ChainI != ChainE; ++ChainI) {

4834

if (PHINode *PN = dyn_cast<PHINode>(ChainI->tailUserInst()))

4835

Rewriter.setChainedPhi(PN);

4836

}

4837

4838

// Expand the new value definitions and update the users.

4839

for (SmallVectorImpl<LSRFixup>::const_iterator I = Fixups.begin(),

4840

E = Fixups.end(); I != E; ++I) {

4841

const LSRFixup &Fixup = *I;

4842

4843

Rewrite(Fixup, *Solution[Fixup.LUIdx], Rewriter, DeadInsts, P);

4844

4845

Changed = true;

4846

}

4847

4848

for (SmallVectorImpl<IVChain>::const_iterator ChainI = IVChainVec.begin(),

4849

ChainE = IVChainVec.end(); ChainI != ChainE; ++ChainI) {

4850

GenerateIVChain(*ChainI, Rewriter, DeadInsts);

4851

Changed = true;

4852

}

4853

// Clean up after ourselves. This must be done before deleting any

4854

// instructions.

4855

Rewriter.clear();

4856

4857

Changed |= DeleteTriviallyDeadInstructions(DeadInsts);

4858

}

4859

4860

LSRInstance::LSRInstance(Loop *L, Pass *P)

4861

: IU(P->getAnalysis<IVUsers>()), SE(P->getAnalysis<ScalarEvolution>()),

4862

DT(P->getAnalysis<DominatorTreeWrapperPass>().getDomTree()),

4863

LI(P->getAnalysis<LoopInfoWrapperPass>().getLoopInfo()),

4864

TTI(P->getAnalysis<TargetTransformInfoWrapperPass>().getTTI(

4865

*L->getHeader()->getParent())),

4866

L(L), Changed(false), IVIncInsertPos(nullptr) {

4867

// If LoopSimplify form is not available, stay out of trouble.

4868

if (!L->isLoopSimplifyForm())

4869

return;

4870

4871

// If there's no interesting work to be done, bail early.

4872

if (IU.empty()) return;

4873

4874

// If there's too much analysis to be done, bail early. We won't be able to

4875

// model the problem anyway.

4876

unsigned NumUsers = 0;

4877

for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) {

4878

if (++NumUsers > MaxIVUsers) {

4879

DEBUG(dbgs() << "LSR skipping loop, too many IV Users in " << *Ldo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in "
<< *L << "\n"; } } while (0)

4880

<< "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in "
<< *L << "\n"; } } while (0);

4881

return;

4882

}

4883

}

4884

4885

#ifndef NDEBUG

4886

// All dominating loops must have preheaders, or SCEVExpander may not be able

4887

// to materialize an AddRecExpr whose Start is an outer AddRecExpr.

4888

4889

// IVUsers analysis should only create users that are dominated by simple loop

4890

// headers. Since this loop should dominate all of its users, its user list

4891

// should be empty if this loop itself is not within a simple loop nest.

4892

for (DomTreeNode *Rung = DT.getNode(L->getLoopPreheader());

4893

Rung; Rung = Rung->getIDom()) {

4894

BasicBlock *BB = Rung->getBlock();

4895

const Loop *DomLoop = LI.getLoopFor(BB);

4896

if (DomLoop && DomLoop->getHeader() == BB) {

4897

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4897, __PRETTY_FUNCTION__));

4898

}

4899

}

4900

#endif // DEBUG

4901

4902

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)

4903

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)

4904

dbgs() << ":\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (0);

4905

4906

// First, perform some low-level loop optimizations.

4907

OptimizeShadowIV();

4908

OptimizeLoopTermCond();

4909

4910

// If loop preparation eliminates all interesting IV users, bail.

4911

if (IU.empty()) return;

4912

4913

// Skip nested loops until we can model them better with formulae.

4914

if (!L->empty()) {

4915

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);

4916

return;

4917

}

4918

4919

// Start collecting data and preparing for the solver.

4920

CollectChains();

4921

CollectInterestingTypesAndFactors();

4922

CollectFixupsAndInitialFormulae();

4923

CollectLoopInvariantFixupsAndFormulae();

4924

4925

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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4925, __PRETTY_FUNCTION__));

4926

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
)

4927

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR found " << Uses
.size() << " uses:\n"; print_uses(dbgs()); } } while (0
);

4928

4929

// Now use the reuse data to generate a bunch of interesting ways

4930

// to formulate the values needed for the uses.

4931

GenerateAllReuseFormulae();

4932

4933

FilterOutUndesirableDedicatedRegisters();

4934

NarrowSearchSpaceUsingHeuristics();

4935

4936

SmallVector<const Formula *, 8> Solution;

4937

Solve(Solution);

4938

4939

// Release memory that is no longer needed.

4940

Factors.clear();

4941

Types.clear();

4942

RegUses.clear();

4943

4944

if (Solution.empty())

4945

return;

4946

4947

#ifndef NDEBUG

4948

// Formulae should be legal.

4949

for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(), E = Uses.end();

4950

I != E; ++I) {

4951

const LSRUse &LU = *I;

4952

for (SmallVectorImpl<Formula>::const_iterator J = LU.Formulae.begin(),

4953

JE = LU.Formulae.end();

4954

J != JE; ++J)

4955

assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, *J) && "Illegal formula generated!") ? static_cast<
void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, *J) && \"Illegal formula generated!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4956, __PRETTY_FUNCTION__))

4956

*J) && "Illegal formula generated!")((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, *J) && "Illegal formula generated!") ? static_cast<
void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, *J) && \"Illegal formula generated!\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4956, __PRETTY_FUNCTION__));

4957

};

4958

#endif

4959

4960

// Now that we've decided what we want, make it so.

4961

ImplementSolution(Solution, P);

4962

}

4963

4964

void LSRInstance::print_factors_and_types(raw_ostream &OS) const {

4965

if (Factors.empty() && Types.empty()) return;

4966

4967

OS << "LSR has identified the following interesting factors and types: ";

4968

bool First = true;

4969

4970

for (SmallSetVector<int64_t, 8>::const_iterator

4971

I = Factors.begin(), E = Factors.end(); I != E; ++I) {

4972

if (!First) OS << ", ";

4973

First = false;

4974

OS << '*' << *I;

4975

}

4976

4977

for (SmallSetVector<Type *, 4>::const_iterator

4978

I = Types.begin(), E = Types.end(); I != E; ++I) {

4979

if (!First) OS << ", ";

4980

First = false;

4981

OS << '(' << **I << ')';

4982

}

4983

OS << '\n';

4984

}

4985

4986

void LSRInstance::print_fixups(raw_ostream &OS) const {

4987

OS << "LSR is examining the following fixup sites:\n";

4988

for (SmallVectorImpl<LSRFixup>::const_iterator I = Fixups.begin(),

4989

E = Fixups.end(); I != E; ++I) {

4990

dbgs() << " ";

4991

I->print(OS);

4992

OS << '\n';

4993

}

4994

}

4995

4996

void LSRInstance::print_uses(raw_ostream &OS) const {

4997

OS << "LSR is examining the following uses:\n";

4998

for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(),

4999

E = Uses.end(); I != E; ++I) {

5000

const LSRUse &LU = *I;

5001

dbgs() << " ";

5002

LU.print(OS);

5003

OS << '\n';

5004

for (SmallVectorImpl<Formula>::const_iterator J = LU.Formulae.begin(),

5005

JE = LU.Formulae.end(); J != JE; ++J) {

5006

OS << " ";

5007

J->print(OS);

5008

OS << '\n';

5009

}

5010

}

5011

}

5012

5013

void LSRInstance::print(raw_ostream &OS) const {

5014

print_factors_and_types(OS);

5015

print_fixups(OS);

5016

print_uses(OS);

5017

}

5018

5019

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

5020

void LSRInstance::dump() const {

5021

print(errs()); errs() << '\n';

5022

}

5023

#endif

5024

5025

namespace {

5026

5027

class LoopStrengthReduce : public LoopPass {

5028

public:

5029

static char ID; // Pass ID, replacement for typeid

5030

LoopStrengthReduce();

5031

5032

private:

5033

bool runOnLoop(Loop *L, LPPassManager &LPM) override;

5034

void getAnalysisUsage(AnalysisUsage &AU) const override;

5035

};

5036

5037

}

5038

5039

char LoopStrengthReduce::ID = 0;

5040

INITIALIZE_PASS_BEGIN(LoopStrengthReduce, "loop-reduce",static void* initializeLoopStrengthReducePassOnce(PassRegistry
&Registry) {

5041

"Loop Strength Reduction", false, false)static void* initializeLoopStrengthReducePassOnce(PassRegistry
&Registry) {

5042

INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)initializeTargetTransformInfoWrapperPassPass(Registry);

5043

INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);

5044

INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)initializeScalarEvolutionPass(Registry);

5045

INITIALIZE_PASS_DEPENDENCY(IVUsers)initializeIVUsersPass(Registry);

5046

INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);

5047

INITIALIZE_PASS_DEPENDENCY(LoopSimplify)initializeLoopSimplifyPass(Registry);

5048

INITIALIZE_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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5049); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5049, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5049); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5049, &initialized); }

5049

"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~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5049); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5049, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5049); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn237945/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5049, &initialized); }

5050

5051

5052

Pass *llvm::createLoopStrengthReducePass() {

5053

return new LoopStrengthReduce();

5054

}

5055

5056

LoopStrengthReduce::LoopStrengthReduce() : LoopPass(ID) {

5057

initializeLoopStrengthReducePass(*PassRegistry::getPassRegistry());

5058

}

5059

5060

void LoopStrengthReduce::getAnalysisUsage(AnalysisUsage &AU) const {

5061

// We split critical edges, so we change the CFG. However, we do update

5062

// many analyses if they are around.

5063

AU.addPreservedID(LoopSimplifyID);

5064

5065

AU.addRequired<LoopInfoWrapperPass>();

5066

AU.addPreserved<LoopInfoWrapperPass>();

5067

AU.addRequiredID(LoopSimplifyID);

5068

AU.addRequired<DominatorTreeWrapperPass>();

5069

AU.addPreserved<DominatorTreeWrapperPass>();

5070

AU.addRequired<ScalarEvolution>();

5071

AU.addPreserved<ScalarEvolution>();

5072

// Requiring LoopSimplify a second time here prevents IVUsers from running

5073

// twice, since LoopSimplify was invalidated by running ScalarEvolution.

5074

AU.addRequiredID(LoopSimplifyID);

5075

AU.addRequired<IVUsers>();

5076

AU.addPreserved<IVUsers>();

5077

AU.addRequired<TargetTransformInfoWrapperPass>();

5078

}

5079

5080

bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager & /*LPM*/) {

5081

if (skipOptnoneFunction(L))

5082

return false;

5083

5084

bool Changed = false;

5085

5086

// Run the main LSR transformation.

5087

Changed |= LSRInstance(L, this).getChanged();

5088

5089

// Remove any extra phis created by processing inner loops.

5090

Changed |= DeleteDeadPHIs(L->getHeader());

5091

if (EnablePhiElim && L->isLoopSimplifyForm()) {

5092

SmallVector<WeakVH, 16> DeadInsts;

5093

const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();

5094

SCEVExpander Rewriter(getAnalysis<ScalarEvolution>(), DL, "lsr");

5095

#ifndef NDEBUG

5096

Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");

5097

#endif

5098

unsigned numFolded = Rewriter.replaceCongruentIVs(

5099

L, &getAnalysis<DominatorTreeWrapperPass>().getDomTree(), DeadInsts,

5100

&getAnalysis<TargetTransformInfoWrapperPass>().getTTI(

5101

*L->getHeader()->getParent()));

5102

if (numFolded) {

5103

Changed = true;

5104

DeleteTriviallyDeadInstructions(DeadInsts);

5105

DeleteDeadPHIs(L->getHeader());

5106

}

5107

}

5108

return Changed;

5109

}