/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp

Bug Summary

File:	lib/Transforms/Scalar/LoopStrengthReduce.cpp
Location:	line 4765, column 22
Description:	Called C++ object pointer is null

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/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(

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

100

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

101

#else

102

static bool StressIVChain = false;

103

#endif

104

105

namespace {

106

107

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

108

class RegSortData {

109

public:

110

/// UsedByIndices - This represents the set of LSRUse indices which reference

111

/// a particular register.

112

SmallBitVector UsedByIndices;

113

114

RegSortData() {}

115

116

void print(raw_ostream &OS) const;

117

void dump() const;

118

};

119

120

}

121

122

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

123

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

124

}

125

126

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

127

void RegSortData::dump() const {

128

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

129

}

130

#endif

131

132

namespace {

133

134

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

135

/// used.

136

class RegUseTracker {

137

typedef DenseMap<const SCEV *, RegSortData> RegUsesTy;

138

139

RegUsesTy RegUsesMap;

140

SmallVector<const SCEV *, 16> RegSequence;

141

142

public:

143

void CountRegister(const SCEV *Reg, size_t LUIdx);

144

void DropRegister(const SCEV *Reg, size_t LUIdx);

145

void SwapAndDropUse(size_t LUIdx, size_t LastLUIdx);

146

147

bool isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const;

148

149

const SmallBitVector &getUsedByIndices(const SCEV *Reg) const;

150

151

void clear();

152

153

typedef SmallVectorImpl<const SCEV *>::iterator iterator;

154

typedef SmallVectorImpl<const SCEV *>::const_iterator const_iterator;

155

iterator begin() { return RegSequence.begin(); }

156

iterator end() { return RegSequence.end(); }

157

const_iterator begin() const { return RegSequence.begin(); }

158

const_iterator end() const { return RegSequence.end(); }

159

};

160

161

}

162

163

void

164

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

165

std::pair<RegUsesTy::iterator, bool> Pair =

166

RegUsesMap.insert(std::make_pair(Reg, RegSortData()));

167

RegSortData &RSD = Pair.first->second;

168

if (Pair.second)

169

RegSequence.push_back(Reg);

170

RSD.UsedByIndices.resize(std::max(RSD.UsedByIndices.size(), LUIdx + 1));

171

RSD.UsedByIndices.set(LUIdx);

172

}

173

174

void

175

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

176

RegUsesTy::iterator It = RegUsesMap.find(Reg);

177

assert(It != RegUsesMap.end())((It != RegUsesMap.end()) ? static_cast<void> (0) : __assert_fail
("It != RegUsesMap.end()", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 177, __PRETTY_FUNCTION__));

178

RegSortData &RSD = It->second;

179

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 179, __PRETTY_FUNCTION__));

180

RSD.UsedByIndices.reset(LUIdx);

181

}

182

183

void

184

RegUseTracker::SwapAndDropUse(size_t LUIdx, size_t LastLUIdx) {

185

assert(LUIdx <= LastLUIdx)((LUIdx <= LastLUIdx) ? static_cast<void> (0) : __assert_fail
("LUIdx <= LastLUIdx", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 185, __PRETTY_FUNCTION__));

186

187

// Update RegUses. The data structure is not optimized for this purpose;

188

// we must iterate through it and update each of the bit vectors.

189

for (RegUsesTy::iterator I = RegUsesMap.begin(), E = RegUsesMap.end();

190

I != E; ++I) {

191

SmallBitVector &UsedByIndices = I->second.UsedByIndices;

192

if (LUIdx < UsedByIndices.size())

193

UsedByIndices[LUIdx] =

194

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

195

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

196

}

197

}

198

199

bool

200

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

201

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

202

if (I == RegUsesMap.end())

203

return false;

204

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

205

int i = UsedByIndices.find_first();

206

if (i == -1) return false;

207

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

208

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

209

}

210

211

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

212

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

213

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 213, __PRETTY_FUNCTION__));

214

return I->second.UsedByIndices;

215

}

216

217

void RegUseTracker::clear() {

218

RegUsesMap.clear();

219

RegSequence.clear();

220

}

221

222

namespace {

223

224

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

225

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

226

/// registers.

227

struct Formula {

228

/// Global base address used for complex addressing.

229

GlobalValue *BaseGV;

230

231

/// Base offset for complex addressing.

232

int64_t BaseOffset;

233

234

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

235

bool HasBaseReg;

236

237

/// The scale of any complex addressing.

238

int64_t Scale;

239

240

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

241

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

242

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

243

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

244

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

245

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

246

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

247

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

248

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

249

/// form.

250

SmallVector<const SCEV *, 4> BaseRegs;

251

252

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

253

/// when Scale is not zero.

254

const SCEV *ScaledReg;

255

256

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

257

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

258

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

259

int64_t UnfoldedOffset;

260

261

Formula()

262

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

263

ScaledReg(nullptr), UnfoldedOffset(0) {}

264

265

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

266

267

bool isCanonical() const;

268

269

void Canonicalize();

270

271

bool Unscale();

272

273

size_t getNumRegs() const;

274

Type *getType() const;

275

276

void DeleteBaseReg(const SCEV *&S);

277

278

bool referencesReg(const SCEV *S) const;

279

bool hasRegsUsedByUsesOtherThan(size_t LUIdx,

280

const RegUseTracker &RegUses) const;

281

282

void print(raw_ostream &OS) const;

283

void dump() const;

284

};

285

286

}

287

288

/// DoInitialMatch - Recursion helper for InitialMatch.

289

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

290

SmallVectorImpl<const SCEV *> &Good,

291

SmallVectorImpl<const SCEV *> &Bad,

292

ScalarEvolution &SE) {

293

// Collect expressions which properly dominate the loop header.

294

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

295

Good.push_back(S);

296

return;

297

}

298

299

// Look at add operands.

300

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

301

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

302

I != E; ++I)

303

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

304

return;

305

}

306

307

// Look at addrec operands.

308

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

309

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

310

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

311

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

312

AR->getStepRecurrence(SE),

313

// FIXME: AR->getNoWrapFlags()

314

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

315

L, Good, Bad, SE);

316

return;

317

}

318

319

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

320

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

321

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

322

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

323

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

324

325

SmallVector<const SCEV *, 4> MyGood;

326

SmallVector<const SCEV *, 4> MyBad;

327

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

328

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

329

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

330

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

331

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

332

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

333

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

334

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

335

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

336

return;

337

}

338

339

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

340

// register and hope for the best.

341

Bad.push_back(S);

342

}

343

344

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

345

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

346

/// single base register.

347

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

348

SmallVector<const SCEV *, 4> Good;

349

SmallVector<const SCEV *, 4> Bad;

350

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

351

if (!Good.empty()) {

352

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

353

if (!Sum->isZero())

354

BaseRegs.push_back(Sum);

355

HasBaseReg = true;

356

}

357

if (!Bad.empty()) {

358

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

359

if (!Sum->isZero())

360

BaseRegs.push_back(Sum);

361

HasBaseReg = true;

362

}

363

Canonicalize();

364

}

365

366

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

367

/// representation.

368

/// \see Formula::BaseRegs.

369

bool Formula::isCanonical() const {

370

if (ScaledReg)

371

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

372

return BaseRegs.size() <= 1;

373

}

374

375

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

376

/// \see Formula::BaseRegs.

377

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

378

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

379

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

380

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

381

void Formula::Canonicalize() {

382

if (isCanonical())

383

return;

384

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

385

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

386

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 386, __PRETTY_FUNCTION__));

387

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

388

ScaledReg = BaseRegs.back();

389

BaseRegs.pop_back();

390

Scale = 1;

391

size_t BaseRegsSize = BaseRegs.size();

392

size_t Try = 0;

393

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

394

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

395

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

396

}

397

398

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

399

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

400

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

401

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

402

bool Formula::Unscale() {

403

if (Scale != 1)

404

return false;

405

Scale = 0;

406

BaseRegs.push_back(ScaledReg);

407

ScaledReg = nullptr;

408

return true;

409

}

410

411

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

412

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

413

/// addrec strides.

414

size_t Formula::getNumRegs() const {

415

return !!ScaledReg + BaseRegs.size();

416

}

417

418

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

419

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

420

Type *Formula::getType() const {

421

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

422

ScaledReg ? ScaledReg->getType() :

423

BaseGV ? BaseGV->getType() :

424

nullptr;

425

}

426

427

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

428

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

429

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

430

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

431

BaseRegs.pop_back();

432

}

433

434

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

435

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

436

return S == ScaledReg ||

437

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

438

}

439

440

/// hasRegsUsedByUsesOtherThan - Test whether this formula uses registers

441

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

442

bool Formula::hasRegsUsedByUsesOtherThan(size_t LUIdx,

443

const RegUseTracker &RegUses) const {

444

if (ScaledReg)

445

if (RegUses.isRegUsedByUsesOtherThan(ScaledReg, LUIdx))

446

return true;

447

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

448

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

449

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

450

return true;

451

return false;

452

}

453

454

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

455

bool First = true;

456

if (BaseGV) {

457

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

458

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

459

}

460

if (BaseOffset != 0) {

461

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

462

OS << BaseOffset;

463

}

464

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

465

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

466

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

467

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

468

}

469

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

470

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

471

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

472

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

473

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

474

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

475

}

476

if (Scale != 0) {

477

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

478

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

479

if (ScaledReg)

480

OS << *ScaledReg;

481

else

482

OS << "<unknown>";

483

OS << ')';

484

}

485

if (UnfoldedOffset != 0) {

486

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

487

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

488

}

489

}

490

491

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

492

void Formula::dump() const {

493

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

494

}

495

#endif

496

497

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

498

/// without changing its value.

499

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

500

Type *WideTy =

501

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

502

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

503

}

504

505

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

506

/// without changing its value.

507

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

508

Type *WideTy =

509

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

510

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

511

}

512

513

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

514

/// without changing its value.

515

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

516

Type *WideTy =

517

IntegerType::get(SE.getContext(),

518

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

519

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

520

}

521

522

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

523

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

524

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

525

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

526

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

527

/// ignored.

528

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

529

ScalarEvolution &SE,

530

bool IgnoreSignificantBits = false) {

531

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

532

if (LHS == RHS)

533

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

534

535

// Handle a few RHS special cases.

536

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

537

if (RC) {

538

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

539

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

540

// some folding.

541

if (RA.isAllOnesValue())

542

return SE.getMulExpr(LHS, RC);

543

// Handle x /s 1 as x.

544

if (RA == 1)

545

return LHS;

546

}

547

548

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

549

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

550

if (!RC)

551

return nullptr;

552

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

553

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

554

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

555

return nullptr;

556

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

557

}

558

559

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

560

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

561

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

562

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

563

IgnoreSignificantBits);

564

if (!Step) return nullptr;

565

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

566

IgnoreSignificantBits);

567

if (!Start) return nullptr;

568

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

569

// preserved with smaller magnitude steps.

570

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

571

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

572

}

573

return nullptr;

574

}

575

576

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

577

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

578

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

579

SmallVector<const SCEV *, 8> Ops;

580

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

581

I != E; ++I) {

582

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

583

IgnoreSignificantBits);

584

if (!Op) return nullptr;

585

Ops.push_back(Op);

586

}

587

return SE.getAddExpr(Ops);

588

}

589

return nullptr;

590

}

591

592

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

593

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

594

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

595

SmallVector<const SCEV *, 4> Ops;

596

bool Found = false;

597

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

598

I != E; ++I) {

599

const SCEV *S = *I;

600

if (!Found)

601

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

602

IgnoreSignificantBits)) {

603

S = Q;

604

Found = true;

605

}

606

Ops.push_back(S);

607

}

608

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

609

}

610

return nullptr;

611

}

612

613

// Otherwise we don't know.

614

return nullptr;

615

}

616

617

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

618

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

619

/// value excluded.

620

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

621

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

622

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

623

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

624

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

625

}

626

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

627

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

628

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

629

if (Result != 0)

630

S = SE.getAddExpr(NewOps);

631

return Result;

632

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

633

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

634

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

635

if (Result != 0)

636

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

637

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

638

SCEV::FlagAnyWrap);

639

return Result;

640

}

641

return 0;

642

}

643

644

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

645

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

646

/// value excluded.

647

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

648

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

649

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

650

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

651

return GV;

652

}

653

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

654

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

655

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

656

if (Result)

657

S = SE.getAddExpr(NewOps);

658

return Result;

659

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

660

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

661

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

662

if (Result)

663

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

664

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

665

SCEV::FlagAnyWrap);

666

return Result;

667

}

668

return nullptr;

669

}

670

671

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

672

/// specified value as an address.

673

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

674

bool isAddress = isa<LoadInst>(Inst);

675

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

676

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

677

isAddress = true;

678

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

679

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

680

// of intrinsics.

681

switch (II->getIntrinsicID()) {

682

default: break;

683

case Intrinsic::prefetch:

684

case Intrinsic::x86_sse_storeu_ps:

685

case Intrinsic::x86_sse2_storeu_pd:

686

case Intrinsic::x86_sse2_storeu_dq:

687

case Intrinsic::x86_sse2_storel_dq:

688

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

689

isAddress = true;

690

break;

691

}

692

}

693

return isAddress;

694

}

695

696

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

697

static Type *getAccessType(const Instruction *Inst) {

698

Type *AccessTy = Inst->getType();

699

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

700

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

701

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

702

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

703

// of intrinsics.

704

switch (II->getIntrinsicID()) {

705

default: break;

706

case Intrinsic::x86_sse_storeu_ps:

707

case Intrinsic::x86_sse2_storeu_pd:

708

case Intrinsic::x86_sse2_storeu_dq:

709

case Intrinsic::x86_sse2_storel_dq:

710

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

711

break;

712

}

713

}

714

715

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

716

// arbitrary pointer type to minimize variation.

717

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

718

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

719

PTy->getAddressSpace());

720

721

return AccessTy;

722

}

723

724

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

725

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

726

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

727

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

728

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

729

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

730

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

731

SE.getSCEV(PN) == AR)

732

return true;

733

}

734

return false;

735

}

736

737

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

738

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

739

/// by the current IR.

740

///

741

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

742

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

743

///

744

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

745

/// obvious multiple of the UDivExpr.

746

static bool isHighCostExpansion(const SCEV *S,

747

SmallPtrSetImpl<const SCEV*> &Processed,

748

ScalarEvolution &SE) {

749

// Zero/One operand expressions

750

switch (S->getSCEVType()) {

751

case scUnknown:

752

case scConstant:

753

return false;

754

case scTruncate:

755

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

756

Processed, SE);

757

case scZeroExtend:

758

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

759

Processed, SE);

760

case scSignExtend:

761

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

762

Processed, SE);

763

}

764

765

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

766

return false;

767

768

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

769

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

770

I != E; ++I) {

771

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

772

return true;

773

}

774

return false;

775

}

776

777

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

778

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

779

// Multiplication by a constant is ok

780

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

781

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

782

783

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

784

// multiplication already generates this expression.

785

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

786

Value *UVal = U->getValue();

787

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

788

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

789

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

790

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

791

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

792

return SE.getSCEV(UI) == Mul;

793

}

794

}

795

}

796

}

797

}

798

799

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

800

if (isExistingPhi(AR, SE))

801

return false;

802

}

803

804

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

805

return true;

806

}

807

808

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

809

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

810

/// their operands subsequently dead.

811

static bool

812

DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakVH> &DeadInsts) {

813

bool Changed = false;

814

815

while (!DeadInsts.empty()) {

816

Value *V = DeadInsts.pop_back_val();

817

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

818

819

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

820

continue;

821

822

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

823

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

824

*OI = nullptr;

825

if (U->use_empty())

826

DeadInsts.push_back(U);

827

}

828

829

I->eraseFromParent();

830

Changed = true;

831

}

832

833

return Changed;

834

}

835

836

namespace {

837

class LSRUse;

838

}

839

840

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

841

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

842

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

843

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

844

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

845

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

846

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

847

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

848

/// accurate cost model.

849

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

850

const LSRUse &LU, const Formula &F);

851

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

852

static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,

853

const LSRUse &LU, const Formula &F);

854

855

namespace {

856

857

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

858

class Cost {

859

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

860

/// isn't always optimal.

861

unsigned NumRegs;

862

unsigned AddRecCost;

863

unsigned NumIVMuls;

864

unsigned NumBaseAdds;

865

unsigned ImmCost;

866

unsigned SetupCost;

867

unsigned ScaleCost;

868

869

public:

870

Cost()

871

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

872

SetupCost(0), ScaleCost(0) {}

873

874

bool operator<(const Cost &Other) const;

875

876

void Lose();

877

878

#ifndef NDEBUG

879

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

880

bool isValid() {

881

return ((NumRegs | AddRecCost | NumIVMuls | NumBaseAdds

882

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

883

|| ((NumRegs & AddRecCost & NumIVMuls & NumBaseAdds

884

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

885

}

886

#endif

887

888

bool isLoser() {

889

assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 889, __PRETTY_FUNCTION__));

890

return NumRegs == ~0u;

891

}

892

893

void RateFormula(const TargetTransformInfo &TTI,

894

const Formula &F,

895

SmallPtrSetImpl<const SCEV *> &Regs,

896

const DenseSet<const SCEV *> &VisitedRegs,

897

const Loop *L,

898

const SmallVectorImpl<int64_t> &Offsets,

899

ScalarEvolution &SE, DominatorTree &DT,

900

const LSRUse &LU,

901

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

902

903

void print(raw_ostream &OS) const;

904

void dump() const;

905

906

private:

907

void RateRegister(const SCEV *Reg,

908

SmallPtrSetImpl<const SCEV *> &Regs,

909

const Loop *L,

910

ScalarEvolution &SE, DominatorTree &DT);

911

void RatePrimaryRegister(const SCEV *Reg,

912

SmallPtrSetImpl<const SCEV *> &Regs,

913

const Loop *L,

914

ScalarEvolution &SE, DominatorTree &DT,

915

SmallPtrSetImpl<const SCEV *> *LoserRegs);

916

};

917

918

}

919

920

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

921

void Cost::RateRegister(const SCEV *Reg,

922

SmallPtrSetImpl<const SCEV *> &Regs,

923

const Loop *L,

924

ScalarEvolution &SE, DominatorTree &DT) {

925

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

926

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

927

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

928

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

929

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

930

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

931

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

932

if (isExistingPhi(AR, SE))

933

return;

934

935

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

936

Lose();

937

return;

938

}

939

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

940

941

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

942

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

943

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

944

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

945

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

946

if (isLoser())

947

return;

948

}

949

}

950

}

951

++NumRegs;

952

953

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

954

// instructions in the preheader.

955

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

956

!isa<SCEVConstant>(Reg) &&

957

!(isa<SCEVAddRecExpr>(Reg) &&

958

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

959

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

960

++SetupCost;

961

962

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

963

SE.hasComputableLoopEvolution(Reg, L);

964

}

965

966

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

967

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

968

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

969

void Cost::RatePrimaryRegister(const SCEV *Reg,

970

SmallPtrSetImpl<const SCEV *> &Regs,

971

const Loop *L,

972

ScalarEvolution &SE, DominatorTree &DT,

973

SmallPtrSetImpl<const SCEV *> *LoserRegs) {

974

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

975

Lose();

976

return;

977

}

978

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

979

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

980

if (LoserRegs && isLoser())

981

LoserRegs->insert(Reg);

982

}

983

}

984

985

void Cost::RateFormula(const TargetTransformInfo &TTI,

986

const Formula &F,

987

SmallPtrSetImpl<const SCEV *> &Regs,

988

const DenseSet<const SCEV *> &VisitedRegs,

989

const Loop *L,

990

const SmallVectorImpl<int64_t> &Offsets,

991

ScalarEvolution &SE, DominatorTree &DT,

992

const LSRUse &LU,

993

SmallPtrSetImpl<const SCEV *> *LoserRegs) {

994

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 994, __PRETTY_FUNCTION__));

995

// Tally up the registers.

996

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

997

if (VisitedRegs.count(ScaledReg)) {

998

Lose();

999

return;

1000

}

1001

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

1002

if (isLoser())

1003

return;

1004

}

1005

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

1006

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

1007

const SCEV *BaseReg = *I;

1008

if (VisitedRegs.count(BaseReg)) {

1009

Lose();

1010

return;

1011

}

1012

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

1013

if (isLoser())

1014

return;

1015

}

1016

1017

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

1018

size_t NumBaseParts = F.getNumRegs();

1019

if (NumBaseParts > 1)

1020

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

1021

// allows to fold 2 registers.

1022

NumBaseAdds +=

1023

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

1024

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

1025

1026

// Accumulate non-free scaling amounts.

1027

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

1028

1029

// Tally up the non-zero immediates.

1030

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

1031

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

1032

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

1033

if (F.BaseGV)

1034

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

1035

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

1036

else if (Offset != 0)

1037

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

1038

}

1039

1040

}

1041

1042

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

1043

void Cost::Lose() {

1044

NumRegs = ~0u;

1045

AddRecCost = ~0u;

1046

NumIVMuls = ~0u;

1047

NumBaseAdds = ~0u;

1048

ImmCost = ~0u;

1049

SetupCost = ~0u;

1050

ScaleCost = ~0u;

1051

}

1052

1053

/// operator< - Choose the lower cost.

1054

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

1055

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

1056

ImmCost, SetupCost) <

1057

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

1058

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

1059

Other.SetupCost);

1060

}

1061

1062

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

1063

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

1064

if (AddRecCost != 0)

1065

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

1066

if (NumIVMuls != 0)

1067

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

1068

if (NumBaseAdds != 0)

1069

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

1070

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

1071

if (ScaleCost != 0)

1072

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

1073

if (ImmCost != 0)

1074

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

1075

if (SetupCost != 0)

1076

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

1077

}

1078

1079

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

1080

void Cost::dump() const {

1081

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

1082

}

1083

#endif

1084

1085

namespace {

1086

1087

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

1088

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

1089

struct LSRFixup {

1090

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

1091

Instruction *UserInst;

1092

1093

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

1094

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

1095

/// will be replaced.

1096

Value *OperandValToReplace;

1097

1098

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

1099

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

1100

/// associated with the induction variable.

1101

PostIncLoopSet PostIncLoops;

1102

1103

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

1104

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

1105

size_t LUIdx;

1106

1107

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

1108

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

1109

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

1110

int64_t Offset;

1111

1112

bool isUseFullyOutsideLoop(const Loop *L) const;

1113

1114

LSRFixup();

1115

1116

void print(raw_ostream &OS) const;

1117

void dump() const;

1118

};

1119

1120

}

1121

1122

LSRFixup::LSRFixup()

1123

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

1124

Offset(0) {}

1125

1126

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

1127

/// value outside of the given loop.

1128

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

1129

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

1130

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

1131

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

1132

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

1133

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

1134

return false;

1135

return true;

1136

}

1137

1138

return !L->contains(UserInst);

1139

}

1140

1141

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

1142

OS << "UserInst=";

1143

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

1144

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

1145

OS << "store ";

1146

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

1147

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

1148

OS << UserInst->getOpcodeName();

1149

else

1150

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

1151

1152

OS << ", OperandValToReplace=";

1153

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

1154

1155

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

1156

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

1157

OS << ", PostIncLoop=";

1158

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

1159

}

1160

1161

if (LUIdx != ~size_t(0))

1162

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

1163

1164

if (Offset != 0)

1165

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

1166

}

1167

1168

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

1169

void LSRFixup::dump() const {

1170

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

1171

}

1172

#endif

1173

1174

namespace {

1175

1176

/// UniquifierDenseMapInfo - A DenseMapInfo implementation for holding

1177

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

1178

struct UniquifierDenseMapInfo {

1179

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

1180

SmallVector<const SCEV *, 4> V;

1181

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

1182

return V;

1183

}

1184

1185

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

1186

SmallVector<const SCEV *, 4> V;

1187

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

1188

return V;

1189

}

1190

1191

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

1192

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

1193

}

1194

1195

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

1196

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

1197

return LHS == RHS;

1198

}

1199

};

1200

1201

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

1202

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

1203

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

1204

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

1205

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

1206

class LSRUse {

1207

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

1208

1209

public:

1210

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

1211

/// scaled and immediate operands it might support.

1212

enum KindType {

1213

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

1214

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

1215

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

1216

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

1217

// TODO: Add a generic icmp too?

1218

};

1219

1220

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

1221

1222

KindType Kind;

1223

Type *AccessTy;

1224

1225

SmallVector<int64_t, 8> Offsets;

1226

int64_t MinOffset;

1227

int64_t MaxOffset;

1228

1229

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

1230

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

1231

/// may be used.

1232

bool AllFixupsOutsideLoop;

1233

1234

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

1235

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

1236

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

1237

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

1238

/// changing the formula.

1239

bool RigidFormula;

1240

1241

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

1242

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

1243

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

1244

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

1245

Type *WidestFixupType;

1246

1247

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

1248

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

1249

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

1250

SmallVector<Formula, 12> Formulae;

1251

1252

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

1253

SmallPtrSet<const SCEV *, 4> Regs;

1254

1255

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

1256

MinOffset(INT64_MAX(9223372036854775807L)),

1257

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

1258

AllFixupsOutsideLoop(true),

1259

RigidFormula(false),

1260

WidestFixupType(nullptr) {}

1261

1262

bool HasFormulaWithSameRegs(const Formula &F) const;

1263

bool InsertFormula(const Formula &F);

1264

void DeleteFormula(Formula &F);

1265

void RecomputeRegs(size_t LUIdx, RegUseTracker &Reguses);

1266

1267

void print(raw_ostream &OS) const;

1268

void dump() const;

1269

};

1270

1271

}

1272

1273

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

1274

/// registers as the given formula.

1275

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

1276

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

1277

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

1278

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

1279

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

1280

return Uniquifier.count(Key);

1281

}

1282

1283

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

1284

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

1285

/// The formula must be in canonical form.

1286

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

1287

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1287, __PRETTY_FUNCTION__));

1288

1289

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

1290

return false;

1291

1292

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

1293

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

1294

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

1295

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

1296

1297

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

1298

return false;

1299

1300

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

1301

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1302, __PRETTY_FUNCTION__))

1302

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1302, __PRETTY_FUNCTION__));

1303

#ifndef NDEBUG

1304

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

1305

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

1306

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1306, __PRETTY_FUNCTION__));

1307

#endif

1308

1309

// Add the formula to the list.

1310

Formulae.push_back(F);

1311

1312

// Record registers now being used by this use.

1313

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

1314

if (F.ScaledReg)

1315

Regs.insert(F.ScaledReg);

1316

1317

return true;

1318

}

1319

1320

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

1321

void LSRUse::DeleteFormula(Formula &F) {

1322

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

1323

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

1324

Formulae.pop_back();

1325

}

1326

1327

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

1328

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

1329

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

1330

SmallPtrSet<const SCEV *, 4> OldRegs = Regs;

1331

Regs.clear();

1332

for (SmallVectorImpl<Formula>::const_iterator I = Formulae.begin(),

1333

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

1334

const Formula &F = *I;

1335

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

1336

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

1337

}

1338

1339

// Update the RegTracker.

1340

for (const SCEV *S : OldRegs)

1341

if (!Regs.count(S))

1342

RegUses.DropRegister(S, LUIdx);

1343

}

1344

1345

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

1346

OS << "LSR Use: Kind=";

1347

switch (Kind) {

1348

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

1349

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

1350

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

1351

case Address:

1352

OS << "Address of ";

1353

if (AccessTy->isPointerTy())

1354

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

1355

else

1356

OS << *AccessTy;

1357

}

1358

1359

OS << ", Offsets={";

1360

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

1361

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

1362

OS << *I;

1363

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

1364

OS << ',';

1365

}

1366

OS << '}';

1367

1368

if (AllFixupsOutsideLoop)

1369

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

1370

1371

if (WidestFixupType)

1372

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

1373

}

1374

1375

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

1376

void LSRUse::dump() const {

1377

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

1378

}

1379

#endif

1380

1381

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

1382

LSRUse::KindType Kind, Type *AccessTy,

1383

GlobalValue *BaseGV, int64_t BaseOffset,

1384

bool HasBaseReg, int64_t Scale) {

1385

switch (Kind) {

1386

case LSRUse::Address:

1387

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

1388

1389

// Otherwise, just guess that reg+reg addressing is legal.

1390

//return ;

1391

1392

case LSRUse::ICmpZero:

1393

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

1394

// fold a GV into an ICmp.

1395

if (BaseGV)

1396

return false;

1397

1398

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

1399

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

1400

return false;

1401

1402

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

1403

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

1404

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

1405

return false;

1406

1407

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

1408

// integer immediate on an icmp.

1409

if (BaseOffset != 0) {

1410

// We have one of:

1411

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

1412

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

1413

// Offs is the ICmp immediate.

1414

if (Scale == 0)

1415

// The cast does the right thing with INT64_MIN.

1416

BaseOffset = -(uint64_t)BaseOffset;

1417

return TTI.isLegalICmpImmediate(BaseOffset);

1418

}

1419

1420

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

1421

return true;

1422

1423

case LSRUse::Basic:

1424

// Only handle single-register values.

1425

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

1426

1427

case LSRUse::Special:

1428

// Special case Basic to handle -1 scales.

1429

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

1430

}

1431

1432

llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1432);

1433

}

1434

1435

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

1436

int64_t MinOffset, int64_t MaxOffset,

1437

LSRUse::KindType Kind, Type *AccessTy,

1438

GlobalValue *BaseGV, int64_t BaseOffset,

1439

bool HasBaseReg, int64_t Scale) {

1440

// Check for overflow.

1441

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

1442

(MinOffset > 0))

1443

return false;

1444

MinOffset = (uint64_t)BaseOffset + MinOffset;

1445

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

1446

(MaxOffset > 0))

1447

return false;

1448

MaxOffset = (uint64_t)BaseOffset + MaxOffset;

1449

1450

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

1451

HasBaseReg, Scale) &&

1452

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

1453

HasBaseReg, Scale);

1454

}

1455

1456

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

1457

int64_t MinOffset, int64_t MaxOffset,

1458

LSRUse::KindType Kind, Type *AccessTy,

1459

const Formula &F) {

1460

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

1461

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

1462

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

1463

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

1464

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

1465

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

1466

// compile time sake.

1467

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1467, __PRETTY_FUNCTION__));

1468

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

1469

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

1470

}

1471

1472

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

1473

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

1474

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

1475

GlobalValue *BaseGV, int64_t BaseOffset, bool HasBaseReg,

1476

int64_t Scale) {

1477

// We know how to expand completely foldable formulae.

1478

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

1479

BaseOffset, HasBaseReg, Scale) ||

1480

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

1481

// registers.

1482

(Scale == 1 &&

1483

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

1484

BaseGV, BaseOffset, true, 0));

1485

}

1486

1487

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

1488

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

1489

const Formula &F) {

1490

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

1491

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

1492

}

1493

1494

static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,

1495

const LSRUse &LU, const Formula &F) {

1496

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

1497

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

1498

F.Scale);

1499

}

1500

1501

static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,

1502

const LSRUse &LU, const Formula &F) {

1503

if (!F.Scale)

1504

return 0;

1505

1506

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

1507

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

1508

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

1509

LU.AccessTy, F))

1510

return F.Scale != 1;

1511

1512

switch (LU.Kind) {

1513

case LSRUse::Address: {

1514

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

1515

int ScaleCostMinOffset =

1516

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

1517

F.BaseOffset + LU.MinOffset,

1518

F.HasBaseReg, F.Scale);

1519

int ScaleCostMaxOffset =

1520

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

1521

F.BaseOffset + LU.MaxOffset,

1522

F.HasBaseReg, F.Scale);

1523

1524

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1525, __PRETTY_FUNCTION__))

1525

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1525, __PRETTY_FUNCTION__));

1526

return std::max(ScaleCostMinOffset, ScaleCostMaxOffset);

1527

}

1528

case LSRUse::ICmpZero:

1529

case LSRUse::Basic:

1530

case LSRUse::Special:

1531

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

1532

// instruction.

1533

return 0;

1534

}

1535

1536

1537

}

1538

1539

static bool isAlwaysFoldable(const TargetTransformInfo &TTI,

1540

LSRUse::KindType Kind, Type *AccessTy,

1541

GlobalValue *BaseGV, int64_t BaseOffset,

1542

bool HasBaseReg) {

1543

// Fast-path: zero is always foldable.

1544

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

1545

1546

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

1547

// base and a scale.

1548

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

1549

1550

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

1551

// already have a base register.

1552

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

1553

Scale = 0;

1554

HasBaseReg = true;

1555

}

1556

1557

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

1558

HasBaseReg, Scale);

1559

}

1560

1561

static bool isAlwaysFoldable(const TargetTransformInfo &TTI,

1562

ScalarEvolution &SE, int64_t MinOffset,

1563

int64_t MaxOffset, LSRUse::KindType Kind,

1564

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

1565

// Fast-path: zero is always foldable.

1566

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

1567

1568

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

1569

// base and a scale.

1570

int64_t BaseOffset = ExtractImmediate(S, SE);

1571

GlobalValue *BaseGV = ExtractSymbol(S, SE);

1572

1573

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

1574

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

1575

1576

// Fast-path: zero is always foldable.

1577

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

1578

1579

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

1580

// base and a scale.

1581

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

1582

1583

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

1584

BaseOffset, HasBaseReg, Scale);

1585

}

1586

1587

namespace {

1588

1589

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

1590

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

1591

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

1592

///

1593

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

1594

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

1595

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

1596

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

1597

/// expression.

1598

struct IVInc {

1599

Instruction *UserInst;

1600

Value* IVOperand;

1601

const SCEV *IncExpr;

1602

1603

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

1604

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

1605

};

1606

1607

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

1608

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

1609

struct IVChain {

1610

SmallVector<IVInc,1> Incs;

1611

const SCEV *ExprBase;

1612

1613

IVChain() : ExprBase(nullptr) {}

1614

1615

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

1616

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

1617

1618

typedef SmallVectorImpl<IVInc>::const_iterator const_iterator;

1619

1620

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

1621

const_iterator begin() const {

1622

assert(!Incs.empty())((!Incs.empty()) ? static_cast<void> (0) : __assert_fail
("!Incs.empty()", "/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1622, __PRETTY_FUNCTION__));

1623

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

1624

}

1625

const_iterator end() const {

1626

return Incs.end();

1627

}

1628

1629

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

1630

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

1631

1632

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

1633

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

1634

1635

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

1636

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

1637

1638

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

1639

// this chain.

1640

bool isProfitableIncrement(const SCEV *OperExpr,

1641

const SCEV *IncExpr,

1642

ScalarEvolution&);

1643

};

1644

1645

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

1646

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

1647

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

1648

struct ChainUsers {

1649

SmallPtrSet<Instruction*, 4> FarUsers;

1650

SmallPtrSet<Instruction*, 4> NearUsers;

1651

};

1652

1653

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

1654

/// logic.

1655

class LSRInstance {

1656

IVUsers &IU;

1657

ScalarEvolution &SE;

1658

DominatorTree &DT;

1659

LoopInfo &LI;

1660

const TargetTransformInfo &TTI;

1661

Loop *const L;

1662

bool Changed;

1663

1664

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

1665

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

1666

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

1667

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

1668

Instruction *IVIncInsertPos;

1669

1670

/// Factors - Interesting factors between use strides.

1671

SmallSetVector<int64_t, 8> Factors;

1672

1673

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

1674

SmallSetVector<Type *, 4> Types;

1675

1676

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

1677

SmallVector<LSRFixup, 16> Fixups;

1678

1679

/// Uses - The list of interesting uses.

1680

SmallVector<LSRUse, 16> Uses;

1681

1682

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

1683

RegUseTracker RegUses;

1684

1685

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

1686

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

1687

// back to normal LSR behavior for those uses.

1688

static const unsigned MaxChains = 8;

1689

1690

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

1691

SmallVector<IVChain, MaxChains> IVChainVec;

1692

1693

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

1694

SmallPtrSet<Use*, MaxChains> IVIncSet;

1695

1696

void OptimizeShadowIV();

1697

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

1698

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

1699

void OptimizeLoopTermCond();

1700

1701

void ChainInstruction(Instruction *UserInst, Instruction *IVOper,

1702

SmallVectorImpl<ChainUsers> &ChainUsersVec);

1703

void FinalizeChain(IVChain &Chain);

1704

void CollectChains();

1705

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

1706

SmallVectorImpl<WeakVH> &DeadInsts);

1707

1708

void CollectInterestingTypesAndFactors();

1709

void CollectFixupsAndInitialFormulae();

1710

1711

LSRFixup &getNewFixup() {

1712

Fixups.push_back(LSRFixup());

1713

return Fixups.back();

1714

}

1715

1716

// Support for sharing of LSRUses between LSRFixups.

1717

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

1718

UseMapTy UseMap;

1719

1720

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

1721

LSRUse::KindType Kind, Type *AccessTy);

1722

1723

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

1724

LSRUse::KindType Kind,

1725

Type *AccessTy);

1726

1727

void DeleteUse(LSRUse &LU, size_t LUIdx);

1728

1729

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

1730

1731

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

1732

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

1733

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

1734

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

1735

1736

void CollectLoopInvariantFixupsAndFormulae();

1737

1738

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

1739

unsigned Depth = 0);

1740

1741

void GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,

1742

const Formula &Base, unsigned Depth,

1743

size_t Idx, bool IsScaledReg = false);

1744

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

1745

void GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,

1746

const Formula &Base, size_t Idx,

1747

bool IsScaledReg = false);

1748

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

1749

void GenerateConstantOffsetsImpl(LSRUse &LU, unsigned LUIdx,

1750

const Formula &Base,

1751

const SmallVectorImpl<int64_t> &Worklist,

1752

size_t Idx, bool IsScaledReg = false);

1753

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

1754

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

1755

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

1756

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

1757

void GenerateCrossUseConstantOffsets();

1758

void GenerateAllReuseFormulae();

1759

1760

void FilterOutUndesirableDedicatedRegisters();

1761

1762

size_t EstimateSearchSpaceComplexity() const;

1763

void NarrowSearchSpaceByDetectingSupersets();

1764

void NarrowSearchSpaceByCollapsingUnrolledCode();

1765

void NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();

1766

void NarrowSearchSpaceByPickingWinnerRegs();

1767

void NarrowSearchSpaceUsingHeuristics();

1768

1769

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

1770

Cost &SolutionCost,

1771

SmallVectorImpl<const Formula *> &Workspace,

1772

const Cost &CurCost,

1773

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

1774

DenseSet<const SCEV *> &VisitedRegs) const;

1775

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

1776

1777

BasicBlock::iterator

1778

HoistInsertPosition(BasicBlock::iterator IP,

1779

const SmallVectorImpl<Instruction *> &Inputs) const;

1780

BasicBlock::iterator

1781

AdjustInsertPositionForExpand(BasicBlock::iterator IP,

1782

const LSRFixup &LF,

1783

const LSRUse &LU,

1784

SCEVExpander &Rewriter) const;

1785

1786

Value *Expand(const LSRFixup &LF,

1787

const Formula &F,

1788

BasicBlock::iterator IP,

1789

SCEVExpander &Rewriter,

1790

SmallVectorImpl<WeakVH> &DeadInsts) const;

1791

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

1792

const Formula &F,

1793

SCEVExpander &Rewriter,

1794

SmallVectorImpl<WeakVH> &DeadInsts,

1795

Pass *P) const;

1796

void Rewrite(const LSRFixup &LF,

1797

const Formula &F,

1798

SCEVExpander &Rewriter,

1799

SmallVectorImpl<WeakVH> &DeadInsts,

1800

Pass *P) const;

1801

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

1802

Pass *P);

1803

1804

public:

1805

LSRInstance(Loop *L, Pass *P);

1806

1807

bool getChanged() const { return Changed; }

1808

1809

void print_factors_and_types(raw_ostream &OS) const;

1810

void print_fixups(raw_ostream &OS) const;

1811

void print_uses(raw_ostream &OS) const;

1812

void print(raw_ostream &OS) const;

1813

void dump() const;

1814

};

1815

1816

}

1817

1818

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

1819

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

1820

void LSRInstance::OptimizeShadowIV() {

1821

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

1822

if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))

1823

return;

1824

1825

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

1826

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

1827

IVUsers::const_iterator CandidateUI = UI;

1828

++UI;

1829

Instruction *ShadowUse = CandidateUI->getUser();

1830

Type *DestTy = nullptr;

1831

bool IsSigned = false;

1832

1833

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

1834

to eliminate this cast.

1835

1836

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

1837

foo((double)i);

1838

1839

is transformed into

1840

1841

double d = 0.0;

1842

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

1843

foo(d);

1844

1845

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

1846

IsSigned = false;

1847

DestTy = UCast->getDestTy();

1848

}

1849

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

1850

IsSigned = true;

1851

DestTy = SCast->getDestTy();

1852

}

1853

if (!DestTy) continue;

1854

1855

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

1856

// this transformation.

1857

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

1858

1859

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

1860

if (!PH) continue;

1861

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

1862

1863

Type *SrcTy = PH->getType();

1864

int Mantissa = DestTy->getFPMantissaWidth();

1865

if (Mantissa == -1) continue;

1866

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

1867

continue;

1868

1869

unsigned Entry, Latch;

1870

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

1871

Entry = 0;

1872

Latch = 1;

1873

} else {

1874

Entry = 1;

1875

Latch = 0;

1876

}

1877

1878

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

1879

if (!Init) continue;

1880

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

1881

(double)Init->getSExtValue() :

1882

(double)Init->getZExtValue());

1883

1884

BinaryOperator *Incr =

1885

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

1886

if (!Incr) continue;

1887

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

1888

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

1889

continue;

1890

1891

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

1892

ConstantInt *C = nullptr;

1893

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

1894

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

1895

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

1896

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

1897

else

1898

continue;

1899

1900

if (!C) continue;

1901

1902

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

1903

// correctly. TODO: Remove this restriction.

1904

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

1905

1906

/* Add new PHINode. */

1907

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

1908

1909

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

1910

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

1911

BinaryOperator *NewIncr =

1912

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

1913

Instruction::FAdd : Instruction::FSub,

1914

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

1915

1916

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

1917

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

1918

1919

/* Remove cast operation */

1920

ShadowUse->replaceAllUsesWith(NewPH);

1921

ShadowUse->eraseFromParent();

1922

Changed = true;

1923

break;

1924

}

1925

}

1926

1927

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

1928

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

1929

/// false.

1930

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

1931

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

1932

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

1933

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

1934

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

1935

// occurs enough in real life to handle.

1936

CondUse = UI;

1937

return true;

1938

}

1939

return false;

1940

}

1941

1942

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

1943

/// a max computation.

1944

///

1945

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

1946

/// like this:

1947

///

1948

/// i = 0;

1949

/// do {

1950

/// p[i] = 0.0;

1951

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

1952

///

1953

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

1954

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

1955

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

1956

/// will commonly be lowered like this:

1957

1958

/// if (n > 0) {

1959

/// i = 0;

1960

/// do {

1961

/// p[i] = 0.0;

1962

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

1963

/// }

1964

///

1965

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

1966

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

1967

///

1968

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

1969

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

1970

/// induction variable:

1971

///

1972

/// i = 0;

1973

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

1974

/// do {

1975

/// p[i] = 0.0;

1976

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

1977

///

1978

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

1979

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

1980

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

1981

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

1982

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

1983

/// the loop has a canonical induction variable.

1984

///

1985

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

1986

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

1987

///

1988

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

1989

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

1990

/// the instructions for the maximum computation.

1991

///

1992

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

1993

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

1994

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

1995

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

1996

return Cond;

1997

1998

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

1999

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

2000

2001

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

2002

if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))

2003

return Cond;

2004

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

2005

2006

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

2007

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

2008

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

2009

2010

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

2011

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

2012

// isn't interesting.

2013

CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;

2014

const SCEVNAryExpr *Max = nullptr;

2015

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

2016

Pred = ICmpInst::ICMP_SLE;

2017

Max = S;

2018

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

2019

Pred = ICmpInst::ICMP_SLT;

2020

Max = S;

2021

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

2022

Pred = ICmpInst::ICMP_ULT;

2023

Max = U;

2024

} else {

2025

// No match; bail.

2026

return Cond;

2027

}

2028

2029

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

2030

// require additional checking and setup.

2031

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

2032

return Cond;

2033

2034

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

2035

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

2036

2037

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

2038

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

2039

if (!MaxLHS ||

2040

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

2041

return Cond;

2042

2043

// Check the relevant induction variable for conformance to

2044

// the pattern.

2045

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

2046

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

2047

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

2048

AR->getStart() != One ||

2049

AR->getStepRecurrence(SE) != One)

2050

return Cond;

2051

2052

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2053, __PRETTY_FUNCTION__))

2053

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2053, __PRETTY_FUNCTION__));

2054

2055

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

2056

// be used in the new comparison instruction.

2057

Value *NewRHS = nullptr;

2058

if (ICmpInst::isTrueWhenEqual(Pred)) {

2059

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

2060

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

2061

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

2062

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

2063

NewRHS = BO->getOperand(0);

2064

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

2065

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

2066

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

2067

NewRHS = BO->getOperand(0);

2068

if (!NewRHS)

2069

return Cond;

2070

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

2071

NewRHS = Sel->getOperand(1);

2072

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

2073

NewRHS = Sel->getOperand(2);

2074

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

2075

NewRHS = SU->getValue();

2076

else

2077

// Max doesn't match expected pattern.

2078

return Cond;

2079

2080

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

2081

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

2082

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

2083

Pred = CmpInst::getInversePredicate(Pred);

2084

2085

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

2086

// delete the max calculation.

2087

ICmpInst *NewCond =

2088

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

2089

2090

// Delete the max calculation instructions.

2091

Cond->replaceAllUsesWith(NewCond);

2092

CondUse->setUser(NewCond);

2093

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

2094

Cond->eraseFromParent();

2095

Sel->eraseFromParent();

2096

if (Cmp->use_empty())

2097

Cmp->eraseFromParent();

2098

return NewCond;

2099

}

2100

2101

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

2102

/// postinc iv when possible.

2103

void

2104

LSRInstance::OptimizeLoopTermCond() {

2105

SmallPtrSet<Instruction *, 4> PostIncs;

2106

2107

BasicBlock *LatchBlock = L->getLoopLatch();

2108

SmallVector<BasicBlock*, 8> ExitingBlocks;

2109

L->getExitingBlocks(ExitingBlocks);

2110

2111

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

2112

BasicBlock *ExitingBlock = ExitingBlocks[i];

2113

2114

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

2115

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

2116

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

2117

// one register value.

2118

2119

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

2120

if (!TermBr)

2121

continue;

2122

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

2123

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

2124

continue;

2125

2126

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

2127

IVStrideUse *CondUse = nullptr;

2128

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

2129

if (!FindIVUserForCond(Cond, CondUse))

2130

continue;

2131

2132

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

2133

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

2134

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

2135

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

2136

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

2137

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

2138

Cond = OptimizeMax(Cond, CondUse);

2139

2140

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

2141

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

2142

// Check for dominance.

2143

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

2144

continue;

2145

2146

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

2147

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

2148

if (LatchBlock != ExitingBlock)

2149

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

2150

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

2151

// query is a conservative approximation of reachability.

2152

if (&*UI != CondUse &&

2153

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

2154

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

2155

// strides could be a legal scale.

2156

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

2157

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

2158

if (!A || !B) continue;

2159

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

2160

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

2161

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

2162

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

2163

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

2164

else

2165

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

2166

}

2167

if (const SCEVConstant *D =

2168

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

2169

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

2170

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

2171

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

2172

goto decline_post_inc;

2173

// Avoid weird situations.

2174

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

2175

C->getValue().isMinSignedValue())

2176

goto decline_post_inc;

2177

// Check for possible scaled-address reuse.

2178

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

2179

int64_t Scale = C->getSExtValue();

2180

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

2181

/*BaseOffset=*/ 0,

2182

/*HasBaseReg=*/ false, Scale))

2183

goto decline_post_inc;

2184

Scale = -Scale;

2185

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

2186

/*BaseOffset=*/ 0,

2187

/*HasBaseReg=*/ false, Scale))

2188

goto decline_post_inc;

2189

}

2190

}

2191

2192

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)

2193

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

2194

2195

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

2196

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

2197

// the exiting block branch, move it.

2198

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

2199

if (Cond->hasOneUse()) {

2200

Cond->moveBefore(TermBr);

2201

} else {

2202

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

2203

ICmpInst *OldCond = Cond;

2204

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

2205

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

2206

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

2207

2208

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

2209

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

2210

TermBr->replaceUsesOfWith(OldCond, Cond);

2211

}

2212

}

2213

2214

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

2215

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

2216

// live ranges for the IV correctly.

2217

CondUse->transformToPostInc(L);

2218

Changed = true;

2219

2220

PostIncs.insert(Cond);

2221

decline_post_inc:;

2222

}

2223

2224

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

2225

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

2226

// dominate the loop latch edge.

2227

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

2228

for (Instruction *Inst : PostIncs) {

2229

BasicBlock *BB =

2230

DT.findNearestCommonDominator(IVIncInsertPos->getParent(),

2231

Inst->getParent());

2232

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

2233

IVIncInsertPos = Inst;

2234

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

2235

IVIncInsertPos = BB->getTerminator();

2236

}

2237

}

2238

2239

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

2240

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

2241

/// return true.

2242

bool

2243

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

2244

LSRUse::KindType Kind, Type *AccessTy) {

2245

int64_t NewMinOffset = LU.MinOffset;

2246

int64_t NewMaxOffset = LU.MaxOffset;

2247

Type *NewAccessTy = AccessTy;

2248

2249

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

2250

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

2251

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

2252

if (LU.Kind != Kind)

2253

return false;

2254

2255

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

2256

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

2257

// addressing modes.

2258

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

2259

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

2260

2261

// Conservatively assume HasBaseReg is true for now.

2262

if (NewOffset < LU.MinOffset) {

2263

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

2264

LU.MaxOffset - NewOffset, HasBaseReg))

2265

return false;

2266

NewMinOffset = NewOffset;

2267

} else if (NewOffset > LU.MaxOffset) {

2268

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

2269

NewOffset - LU.MinOffset, HasBaseReg))

2270

return false;

2271

NewMaxOffset = NewOffset;

2272

}

2273

2274

// Update the use.

2275

LU.MinOffset = NewMinOffset;

2276

LU.MaxOffset = NewMaxOffset;

2277

LU.AccessTy = NewAccessTy;

2278

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

2279

LU.Offsets.push_back(NewOffset);

2280

return true;

2281

}

2282

2283

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

2284

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

2285

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

2286

std::pair<size_t, int64_t>

2287

LSRInstance::getUse(const SCEV *&Expr,

2288

LSRUse::KindType Kind, Type *AccessTy) {

2289

const SCEV *Copy = Expr;

2290

int64_t Offset = ExtractImmediate(Expr, SE);

2291

2292

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

2293

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

2294

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

2295

Expr = Copy;

2296

Offset = 0;

2297

}

2298

2299

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

2300

UseMap.insert(std::make_pair(LSRUse::SCEVUseKindPair(Expr, Kind), 0));

2301

if (!P.second) {

2302

// A use already existed with this base.

2303

size_t LUIdx = P.first->second;

2304

LSRUse &LU = Uses[LUIdx];

2305

if (reconcileNewOffset(LU, Offset, /*HasBaseReg=*/true, Kind, AccessTy))

2306

// Reuse this use.

2307

return std::make_pair(LUIdx, Offset);

2308

}

2309

2310

// Create a new use.

2311

size_t LUIdx = Uses.size();

2312

P.first->second = LUIdx;

2313

Uses.push_back(LSRUse(Kind, AccessTy));

2314

LSRUse &LU = Uses[LUIdx];

2315

2316

// We don't need to track redundant offsets, but we don't need to go out

2317

// of our way here to avoid them.

2318

if (LU.Offsets.empty() || Offset != LU.Offsets.back())

2319

LU.Offsets.push_back(Offset);

2320

2321

LU.MinOffset = Offset;

2322

LU.MaxOffset = Offset;

2323

return std::make_pair(LUIdx, Offset);

2324

}

2325

2326

/// DeleteUse - Delete the given use from the Uses list.

2327

void LSRInstance::DeleteUse(LSRUse &LU, size_t LUIdx) {

2328

if (&LU != &Uses.back())

2329

std::swap(LU, Uses.back());

2330

Uses.pop_back();

2331

2332

// Update RegUses.

2333

RegUses.SwapAndDropUse(LUIdx, Uses.size());

2334

}

2335

2336

/// FindUseWithFormula - Look for a use distinct from OrigLU which is has

2337

/// a formula that has the same registers as the given formula.

2338

LSRUse *

2339

LSRInstance::FindUseWithSimilarFormula(const Formula &OrigF,

2340

const LSRUse &OrigLU) {

2341

// Search all uses for the formula. This could be more clever.

2342

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

2343

LSRUse &LU = Uses[LUIdx];

2344

// Check whether this use is close enough to OrigLU, to see whether it's

2345

// worthwhile looking through its formulae.

2346

// Ignore ICmpZero uses because they may contain formulae generated by

2347

// GenerateICmpZeroScales, in which case adding fixup offsets may

2348

// be invalid.

2349

if (&LU != &OrigLU &&

2350

LU.Kind != LSRUse::ICmpZero &&

2351

LU.Kind == OrigLU.Kind && OrigLU.AccessTy == LU.AccessTy &&

2352

LU.WidestFixupType == OrigLU.WidestFixupType &&

2353

LU.HasFormulaWithSameRegs(OrigF)) {

2354

// Scan through this use's formulae.

2355

for (SmallVectorImpl<Formula>::const_iterator I = LU.Formulae.begin(),

2356

E = LU.Formulae.end(); I != E; ++I) {

2357

const Formula &F = *I;

2358

// Check to see if this formula has the same registers and symbols

2359

// as OrigF.

2360

if (F.BaseRegs == OrigF.BaseRegs &&

2361

F.ScaledReg == OrigF.ScaledReg &&

2362

F.BaseGV == OrigF.BaseGV &&

2363

F.Scale == OrigF.Scale &&

2364

F.UnfoldedOffset == OrigF.UnfoldedOffset) {

2365

if (F.BaseOffset == 0)

2366

return &LU;

2367

// This is the formula where all the registers and symbols matched;

2368

// there aren't going to be any others. Since we declined it, we

2369

// can skip the rest of the formulae and proceed to the next LSRUse.

2370

break;

2371

}

2372

}

2373

}

2374

}

2375

2376

// Nothing looked good.

2377

return nullptr;

2378

}

2379

2380

void LSRInstance::CollectInterestingTypesAndFactors() {

2381

SmallSetVector<const SCEV *, 4> Strides;

2382

2383

// Collect interesting types and strides.

2384

SmallVector<const SCEV *, 4> Worklist;

2385

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

2386

const SCEV *Expr = IU.getExpr(*UI);

2387

2388

// Collect interesting types.

2389

Types.insert(SE.getEffectiveSCEVType(Expr->getType()));

2390

2391

// Add strides for mentioned loops.

2392

Worklist.push_back(Expr);

2393

do {

2394

const SCEV *S = Worklist.pop_back_val();

2395

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

2396

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

2397

Strides.insert(AR->getStepRecurrence(SE));

2398

Worklist.push_back(AR->getStart());

2399

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

2400

Worklist.append(Add->op_begin(), Add->op_end());

2401

}

2402

} while (!Worklist.empty());

2403

}

2404

2405

// Compute interesting factors from the set of interesting strides.

2406

for (SmallSetVector<const SCEV *, 4>::const_iterator

2407

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

2408

for (SmallSetVector<const SCEV *, 4>::const_iterator NewStrideIter =

2409

std::next(I); NewStrideIter != E; ++NewStrideIter) {

2410

const SCEV *OldStride = *I;

2411

const SCEV *NewStride = *NewStrideIter;

2412

2413

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

2414

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

2415

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

2416

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

2417

NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType());

2418

else

2419

OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType());

2420

}

2421

if (const SCEVConstant *Factor =

2422

dyn_cast_or_null<SCEVConstant>(getExactSDiv(NewStride, OldStride,

2423

SE, true))) {

2424

if (Factor->getValue()->getValue().getMinSignedBits() <= 64)

2425

Factors.insert(Factor->getValue()->getValue().getSExtValue());

2426

} else if (const SCEVConstant *Factor =

2427

dyn_cast_or_null<SCEVConstant>(getExactSDiv(OldStride,

2428

NewStride,

2429

SE, true))) {

2430

if (Factor->getValue()->getValue().getMinSignedBits() <= 64)

2431

Factors.insert(Factor->getValue()->getValue().getSExtValue());

2432

}

2433

}

2434

2435

// If all uses use the same type, don't bother looking for truncation-based

2436

// reuse.

2437

if (Types.size() == 1)

2438

Types.clear();

2439

2440

DEBUG(print_factors_and_types(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_factors_and_types(dbgs()); } } while
(0);

2441

}

2442

2443

/// findIVOperand - Helper for CollectChains that finds an IV operand (computed

2444

/// by an AddRec in this loop) within [OI,OE) or returns OE. If IVUsers mapped

2445

/// Instructions to IVStrideUses, we could partially skip this.

2446

static User::op_iterator

2447

findIVOperand(User::op_iterator OI, User::op_iterator OE,

2448

Loop *L, ScalarEvolution &SE) {

2449

for(; OI != OE; ++OI) {

2450

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

2451

if (!SE.isSCEVable(Oper->getType()))

2452

continue;

2453

2454

if (const SCEVAddRecExpr *AR =

2455

dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Oper))) {

2456

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

2457

break;

2458

}

2459

}

2460

}

2461

return OI;

2462

}

2463

2464

/// getWideOperand - IVChain logic must consistenctly peek base TruncInst

2465

/// operands, so wrap it in a convenient helper.

2466

static Value *getWideOperand(Value *Oper) {

2467

if (TruncInst *Trunc = dyn_cast<TruncInst>(Oper))

2468

return Trunc->getOperand(0);

2469

return Oper;

2470

}

2471

2472

/// isCompatibleIVType - Return true if we allow an IV chain to include both

2473

/// types.

2474

static bool isCompatibleIVType(Value *LVal, Value *RVal) {

2475

Type *LType = LVal->getType();

2476

Type *RType = RVal->getType();

2477

return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy());

2478

}

2479

2480

/// getExprBase - Return an approximation of this SCEV expression's "base", or

2481

/// NULL for any constant. Returning the expression itself is

2482

/// conservative. Returning a deeper subexpression is more precise and valid as

2483

/// long as it isn't less complex than another subexpression. For expressions

2484

/// involving multiple unscaled values, we need to return the pointer-type

2485

/// SCEVUnknown. This avoids forming chains across objects, such as:

2486

/// PrevOper==a[i], IVOper==b[i], IVInc==b-a.

2487

///

2488

/// Since SCEVUnknown is the rightmost type, and pointers are the rightmost

2489

/// SCEVUnknown, we simply return the rightmost SCEV operand.

2490

static const SCEV *getExprBase(const SCEV *S) {

2491

switch (S->getSCEVType()) {

2492

default: // uncluding scUnknown.

2493

return S;

2494

case scConstant:

2495

return nullptr;

2496

case scTruncate:

2497

return getExprBase(cast<SCEVTruncateExpr>(S)->getOperand());

2498

case scZeroExtend:

2499

return getExprBase(cast<SCEVZeroExtendExpr>(S)->getOperand());

2500

case scSignExtend:

2501

return getExprBase(cast<SCEVSignExtendExpr>(S)->getOperand());

2502

case scAddExpr: {

2503

// Skip over scaled operands (scMulExpr) to follow add operands as long as

2504

// there's nothing more complex.

2505

// FIXME: not sure if we want to recognize negation.

2506

const SCEVAddExpr *Add = cast<SCEVAddExpr>(S);

2507

for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(Add->op_end()),

2508

E(Add->op_begin()); I != E; ++I) {

2509

const SCEV *SubExpr = *I;

2510

if (SubExpr->getSCEVType() == scAddExpr)

2511

return getExprBase(SubExpr);

2512

2513

if (SubExpr->getSCEVType() != scMulExpr)

2514

return SubExpr;

2515

}

2516

return S; // all operands are scaled, be conservative.

2517

}

2518

case scAddRecExpr:

2519

return getExprBase(cast<SCEVAddRecExpr>(S)->getStart());

2520

}

2521

}

2522

2523

/// Return true if the chain increment is profitable to expand into a loop

2524

/// invariant value, which may require its own register. A profitable chain

2525

/// increment will be an offset relative to the same base. We allow such offsets

2526

/// to potentially be used as chain increment as long as it's not obviously

2527

/// expensive to expand using real instructions.

2528

bool IVChain::isProfitableIncrement(const SCEV *OperExpr,

2529

const SCEV *IncExpr,

2530

ScalarEvolution &SE) {

2531

// Aggressively form chains when -stress-ivchain.

2532

if (StressIVChain)

2533

return true;

2534

2535

// Do not replace a constant offset from IV head with a nonconstant IV

2536

// increment.

2537

if (!isa<SCEVConstant>(IncExpr)) {

2538

const SCEV *HeadExpr = SE.getSCEV(getWideOperand(Incs[0].IVOperand));

2539

if (isa<SCEVConstant>(SE.getMinusSCEV(OperExpr, HeadExpr)))

2540

return 0;

2541

}

2542

2543

SmallPtrSet<const SCEV*, 8> Processed;

2544

return !isHighCostExpansion(IncExpr, Processed, SE);

2545

}

2546

2547

/// Return true if the number of registers needed for the chain is estimated to

2548

/// be less than the number required for the individual IV users. First prohibit

2549

/// any IV users that keep the IV live across increments (the Users set should

2550

/// be empty). Next count the number and type of increments in the chain.

2551

///

2552

/// Chaining IVs can lead to considerable code bloat if ISEL doesn't

2553

/// effectively use postinc addressing modes. Only consider it profitable it the

2554

/// increments can be computed in fewer registers when chained.

2555

///

2556

/// TODO: Consider IVInc free if it's already used in another chains.

2557

static bool

2558

isProfitableChain(IVChain &Chain, SmallPtrSetImpl<Instruction*> &Users,

2559

ScalarEvolution &SE, const TargetTransformInfo &TTI) {

2560

if (StressIVChain)

2561

return true;

2562

2563

if (!Chain.hasIncs())

2564

return false;

2565

2566

if (!Users.empty()) {

2567

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)

2568

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)

2569

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)

2570

})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);

2571

return false;

2572

}

2573

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2573, __PRETTY_FUNCTION__));

2574

2575

// The chain itself may require a register, so intialize cost to 1.

2576

int cost = 1;

2577

2578

// A complete chain likely eliminates the need for keeping the original IV in

2579

// a register. LSR does not currently know how to form a complete chain unless

2580

// the header phi already exists.

2581

if (isa<PHINode>(Chain.tailUserInst())

2582

&& SE.getSCEV(Chain.tailUserInst()) == Chain.Incs[0].IncExpr) {

2583

--cost;

2584

}

2585

const SCEV *LastIncExpr = nullptr;

2586

unsigned NumConstIncrements = 0;

2587

unsigned NumVarIncrements = 0;

2588

unsigned NumReusedIncrements = 0;

2589

for (IVChain::const_iterator I = Chain.begin(), E = Chain.end();

2590

I != E; ++I) {

2591

2592

if (I->IncExpr->isZero())

2593

continue;

2594

2595

// Incrementing by zero or some constant is neutral. We assume constants can

2596

// be folded into an addressing mode or an add's immediate operand.

2597

if (isa<SCEVConstant>(I->IncExpr)) {

2598

++NumConstIncrements;

2599

continue;

2600

}

2601

2602

if (I->IncExpr == LastIncExpr)

2603

++NumReusedIncrements;

2604

else

2605

++NumVarIncrements;

2606

2607

LastIncExpr = I->IncExpr;

2608

}

2609

// An IV chain with a single increment is handled by LSR's postinc

2610

// uses. However, a chain with multiple increments requires keeping the IV's

2611

// value live longer than it needs to be if chained.

2612

if (NumConstIncrements > 1)

2613

--cost;

2614

2615

// Materializing increment expressions in the preheader that didn't exist in

2616

// the original code may cost a register. For example, sign-extended array

2617

// indices can produce ridiculous increments like this:

2618

// IV + ((sext i32 (2 * %s) to i64) + (-1 * (sext i32 %s to i64)))

2619

cost += NumVarIncrements;

2620

2621

// Reusing variable increments likely saves a register to hold the multiple of

2622

// the stride.

2623

cost -= NumReusedIncrements;

2624

2625

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)

2626

<< "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " Cost: " << cost << "\n"
; } } while (0);

2627

2628

return cost < 0;

2629

}

2630

2631

/// ChainInstruction - Add this IV user to an existing chain or make it the head

2632

/// of a new chain.

2633

void LSRInstance::ChainInstruction(Instruction *UserInst, Instruction *IVOper,

2634

SmallVectorImpl<ChainUsers> &ChainUsersVec) {

2635

// When IVs are used as types of varying widths, they are generally converted

2636

// to a wider type with some uses remaining narrow under a (free) trunc.

2637

Value *const NextIV = getWideOperand(IVOper);

2638

const SCEV *const OperExpr = SE.getSCEV(NextIV);

2639

const SCEV *const OperExprBase = getExprBase(OperExpr);

2640

2641

// Visit all existing chains. Check if its IVOper can be computed as a

2642

// profitable loop invariant increment from the last link in the Chain.

2643

unsigned ChainIdx = 0, NChains = IVChainVec.size();

2644

const SCEV *LastIncExpr = nullptr;

2645

for (; ChainIdx < NChains; ++ChainIdx) {

2646

IVChain &Chain = IVChainVec[ChainIdx];

2647

2648

// Prune the solution space aggressively by checking that both IV operands

2649

// are expressions that operate on the same unscaled SCEVUnknown. This

2650

// "base" will be canceled by the subsequent getMinusSCEV call. Checking

2651

// first avoids creating extra SCEV expressions.

2652

if (!StressIVChain && Chain.ExprBase != OperExprBase)

2653

continue;

2654

2655

Value *PrevIV = getWideOperand(Chain.Incs.back().IVOperand);

2656

if (!isCompatibleIVType(PrevIV, NextIV))

2657

continue;

2658

2659

// A phi node terminates a chain.

2660

if (isa<PHINode>(UserInst) && isa<PHINode>(Chain.tailUserInst()))

2661

continue;

2662

2663

// The increment must be loop-invariant so it can be kept in a register.

2664

const SCEV *PrevExpr = SE.getSCEV(PrevIV);

2665

const SCEV *IncExpr = SE.getMinusSCEV(OperExpr, PrevExpr);

2666

if (!SE.isLoopInvariant(IncExpr, L))

2667

continue;

2668

2669

if (Chain.isProfitableIncrement(OperExpr, IncExpr, SE)) {

2670

LastIncExpr = IncExpr;

2671

break;

2672

}

2673

}

2674

// If we haven't found a chain, create a new one, unless we hit the max. Don't

2675

// bother for phi nodes, because they must be last in the chain.

2676

if (ChainIdx == NChains) {

2677

if (isa<PHINode>(UserInst))

2678

return;

2679

if (NChains >= MaxChains && !StressIVChain) {

2680

DEBUG(dbgs() << "IV Chain Limit\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain Limit\n"; } } while
(0);

2681

return;

2682

}

2683

LastIncExpr = OperExpr;

2684

// IVUsers may have skipped over sign/zero extensions. We don't currently

2685

// attempt to form chains involving extensions unless they can be hoisted

2686

// into this loop's AddRec.

2687

if (!isa<SCEVAddRecExpr>(LastIncExpr))

2688

return;

2689

++NChains;

2690

IVChainVec.push_back(IVChain(IVInc(UserInst, IVOper, LastIncExpr),

2691

OperExprBase));

2692

ChainUsersVec.resize(NChains);

2693

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)

2694

<< ") IV=" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Head: (" << *UserInst << ") IV=" <<
*LastIncExpr << "\n"; } } while (0);

2695

} else {

2696

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)

2697

<< ") IV+" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Inc: (" << *UserInst << ") IV+" <<
*LastIncExpr << "\n"; } } while (0);

2698

// Add this IV user to the end of the chain.

2699

IVChainVec[ChainIdx].add(IVInc(UserInst, IVOper, LastIncExpr));

2700

}

2701

IVChain &Chain = IVChainVec[ChainIdx];

2702

2703

SmallPtrSet<Instruction*,4> &NearUsers = ChainUsersVec[ChainIdx].NearUsers;

2704

// This chain's NearUsers become FarUsers.

2705

if (!LastIncExpr->isZero()) {

2706

ChainUsersVec[ChainIdx].FarUsers.insert(NearUsers.begin(),

2707

NearUsers.end());

2708

NearUsers.clear();

2709

}

2710

2711

// All other uses of IVOperand become near uses of the chain.

2712

// We currently ignore intermediate values within SCEV expressions, assuming

2713

// they will eventually be used be the current chain, or can be computed

2714

// from one of the chain increments. To be more precise we could

2715

// transitively follow its user and only add leaf IV users to the set.

2716

for (User *U : IVOper->users()) {

2717

Instruction *OtherUse = dyn_cast<Instruction>(U);

2718

if (!OtherUse)

2719

continue;

2720

// Uses in the chain will no longer be uses if the chain is formed.

2721

// Include the head of the chain in this iteration (not Chain.begin()).

2722

IVChain::const_iterator IncIter = Chain.Incs.begin();

2723

IVChain::const_iterator IncEnd = Chain.Incs.end();

2724

for( ; IncIter != IncEnd; ++IncIter) {

2725

if (IncIter->UserInst == OtherUse)

2726

break;

2727

}

2728

if (IncIter != IncEnd)

2729

continue;

2730

2731

if (SE.isSCEVable(OtherUse->getType())

2732

&& !isa<SCEVUnknown>(SE.getSCEV(OtherUse))

2733

&& IU.isIVUserOrOperand(OtherUse)) {

2734

continue;

2735

}

2736

NearUsers.insert(OtherUse);

2737

}

2738

2739

// Since this user is part of the chain, it's no longer considered a use

2740

// of the chain.

2741

ChainUsersVec[ChainIdx].FarUsers.erase(UserInst);

2742

}

2743

2744

/// CollectChains - Populate the vector of Chains.

2745

///

2746

/// This decreases ILP at the architecture level. Targets with ample registers,

2747

/// multiple memory ports, and no register renaming probably don't want

2748

/// this. However, such targets should probably disable LSR altogether.

2749

///

2750

/// The job of LSR is to make a reasonable choice of induction variables across

2751

/// the loop. Subsequent passes can easily "unchain" computation exposing more

2752

/// ILP *within the loop* if the target wants it.

2753

///

2754

/// Finding the best IV chain is potentially a scheduling problem. Since LSR

2755

/// will not reorder memory operations, it will recognize this as a chain, but

2756

/// will generate redundant IV increments. Ideally this would be corrected later

2757

/// by a smart scheduler:

2758

/// = A[i]

2759

/// = A[i+x]

2760

/// A[i] =

2761

/// A[i+x] =

2762

///

2763

/// TODO: Walk the entire domtree within this loop, not just the path to the

2764

/// loop latch. This will discover chains on side paths, but requires

2765

/// maintaining multiple copies of the Chains state.

2766

void LSRInstance::CollectChains() {

2767

DEBUG(dbgs() << "Collecting IV Chains.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Collecting IV Chains.\n";
} } while (0);

2768

SmallVector<ChainUsers, 8> ChainUsersVec;

2769

2770

SmallVector<BasicBlock *,8> LatchPath;

2771

BasicBlock *LoopHeader = L->getHeader();

2772

for (DomTreeNode *Rung = DT.getNode(L->getLoopLatch());

2773

Rung->getBlock() != LoopHeader; Rung = Rung->getIDom()) {

2774

LatchPath.push_back(Rung->getBlock());

2775

}

2776

LatchPath.push_back(LoopHeader);

2777

2778

// Walk the instruction stream from the loop header to the loop latch.

2779

for (SmallVectorImpl<BasicBlock *>::reverse_iterator

2780

BBIter = LatchPath.rbegin(), BBEnd = LatchPath.rend();

2781

BBIter != BBEnd; ++BBIter) {

2782

for (BasicBlock::iterator I = (*BBIter)->begin(), E = (*BBIter)->end();

2783

I != E; ++I) {

2784

// Skip instructions that weren't seen by IVUsers analysis.

2785

if (isa<PHINode>(I) || !IU.isIVUserOrOperand(I))

2786

continue;

2787

2788

// Ignore users that are part of a SCEV expression. This way we only

2789

// consider leaf IV Users. This effectively rediscovers a portion of

2790

// IVUsers analysis but in program order this time.

2791

if (SE.isSCEVable(I->getType()) && !isa<SCEVUnknown>(SE.getSCEV(I)))

2792

continue;

2793

2794

// Remove this instruction from any NearUsers set it may be in.

2795

for (unsigned ChainIdx = 0, NChains = IVChainVec.size();

2796

ChainIdx < NChains; ++ChainIdx) {

2797

ChainUsersVec[ChainIdx].NearUsers.erase(I);

2798

}

2799

// Search for operands that can be chained.

2800

SmallPtrSet<Instruction*, 4> UniqueOperands;

2801

User::op_iterator IVOpEnd = I->op_end();

2802

User::op_iterator IVOpIter = findIVOperand(I->op_begin(), IVOpEnd, L, SE);

2803

while (IVOpIter != IVOpEnd) {

2804

Instruction *IVOpInst = cast<Instruction>(*IVOpIter);

2805

if (UniqueOperands.insert(IVOpInst).second)

2806

ChainInstruction(I, IVOpInst, ChainUsersVec);

2807

IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);

2808

}

2809

} // Continue walking down the instructions.

2810

} // Continue walking down the domtree.

2811

// Visit phi backedges to determine if the chain can generate the IV postinc.

2812

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

2813

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

2814

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

2815

continue;

2816

2817

Instruction *IncV =

2818

dyn_cast<Instruction>(PN->getIncomingValueForBlock(L->getLoopLatch()));

2819

if (IncV)

2820

ChainInstruction(PN, IncV, ChainUsersVec);

2821

}

2822

// Remove any unprofitable chains.

2823

unsigned ChainIdx = 0;

2824

for (unsigned UsersIdx = 0, NChains = IVChainVec.size();

2825

UsersIdx < NChains; ++UsersIdx) {

2826

if (!isProfitableChain(IVChainVec[UsersIdx],

2827

ChainUsersVec[UsersIdx].FarUsers, SE, TTI))

2828

continue;

2829

// Preserve the chain at UsesIdx.

2830

if (ChainIdx != UsersIdx)

2831

IVChainVec[ChainIdx] = IVChainVec[UsersIdx];

2832

FinalizeChain(IVChainVec[ChainIdx]);

2833

++ChainIdx;

2834

}

2835

IVChainVec.resize(ChainIdx);

2836

}

2837

2838

void LSRInstance::FinalizeChain(IVChain &Chain) {

2839

2840

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);

2841

2842

for (IVChain::const_iterator I = Chain.begin(), E = Chain.end();

2843

I != E; ++I) {

2844

DEBUG(dbgs() << " Inc: " << *I->UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Inc: " << *
I->UserInst << "\n"; } } while (0);

2845

User::op_iterator UseI =

2846

std::find(I->UserInst->op_begin(), I->UserInst->op_end(), I->IVOperand);

2847

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2847, __PRETTY_FUNCTION__));

2848

IVIncSet.insert(UseI);

2849

}

2850

}

2851

2852

/// Return true if the IVInc can be folded into an addressing mode.

2853

static bool canFoldIVIncExpr(const SCEV *IncExpr, Instruction *UserInst,

2854

Value *Operand, const TargetTransformInfo &TTI) {

2855

const SCEVConstant *IncConst = dyn_cast<SCEVConstant>(IncExpr);

2856

if (!IncConst || !isAddressUse(UserInst, Operand))

2857

return false;

2858

2859

if (IncConst->getValue()->getValue().getMinSignedBits() > 64)

2860

return false;

2861

2862

int64_t IncOffset = IncConst->getValue()->getSExtValue();

2863

if (!isAlwaysFoldable(TTI, LSRUse::Address,

2864

getAccessType(UserInst), /*BaseGV=*/ nullptr,

2865

IncOffset, /*HaseBaseReg=*/ false))

2866

return false;

2867

2868

return true;

2869

}

2870

2871

/// GenerateIVChains - Generate an add or subtract for each IVInc in a chain to

2872

/// materialize the IV user's operand from the previous IV user's operand.

2873

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

2874

SmallVectorImpl<WeakVH> &DeadInsts) {

2875

// Find the new IVOperand for the head of the chain. It may have been replaced

2876

// by LSR.

2877

const IVInc &Head = Chain.Incs[0];

2878

User::op_iterator IVOpEnd = Head.UserInst->op_end();

2879

// findIVOperand returns IVOpEnd if it can no longer find a valid IV user.

2880

User::op_iterator IVOpIter = findIVOperand(Head.UserInst->op_begin(),

2881

IVOpEnd, L, SE);

2882

Value *IVSrc = nullptr;

2883

while (IVOpIter != IVOpEnd) {

2884

IVSrc = getWideOperand(*IVOpIter);

2885

2886

// If this operand computes the expression that the chain needs, we may use

2887

// it. (Check this after setting IVSrc which is used below.)

2888

2889

// Note that if Head.IncExpr is wider than IVSrc, then this phi is too

2890

// narrow for the chain, so we can no longer use it. We do allow using a

2891

// wider phi, assuming the LSR checked for free truncation. In that case we

2892

// should already have a truncate on this operand such that

2893

// getSCEV(IVSrc) == IncExpr.

2894

if (SE.getSCEV(*IVOpIter) == Head.IncExpr

2895

|| SE.getSCEV(IVSrc) == Head.IncExpr) {

2896

break;

2897

}

2898

IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);

2899

}

2900

if (IVOpIter == IVOpEnd) {

2901

// Gracefully give up on this chain.

2902

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);

2903

return;

2904

}

2905

2906

DEBUG(dbgs() << "Generate chain at: " << *IVSrc << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generate chain at: " <<
*IVSrc << "\n"; } } while (0);

2907

Type *IVTy = IVSrc->getType();

2908

Type *IntTy = SE.getEffectiveSCEVType(IVTy);

2909

const SCEV *LeftOverExpr = nullptr;

2910

for (IVChain::const_iterator IncI = Chain.begin(),

2911

IncE = Chain.end(); IncI != IncE; ++IncI) {

2912

2913

Instruction *InsertPt = IncI->UserInst;

2914

if (isa<PHINode>(InsertPt))

2915

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

2916

2917

// IVOper will replace the current IV User's operand. IVSrc is the IV

2918

// value currently held in a register.

2919

Value *IVOper = IVSrc;

2920

if (!IncI->IncExpr->isZero()) {

2921

// IncExpr was the result of subtraction of two narrow values, so must

2922

// be signed.

2923

const SCEV *IncExpr = SE.getNoopOrSignExtend(IncI->IncExpr, IntTy);

2924

LeftOverExpr = LeftOverExpr ?

2925

SE.getAddExpr(LeftOverExpr, IncExpr) : IncExpr;

2926

}

2927

if (LeftOverExpr && !LeftOverExpr->isZero()) {

2928

// Expand the IV increment.

2929

Rewriter.clearPostInc();

2930

Value *IncV = Rewriter.expandCodeFor(LeftOverExpr, IntTy, InsertPt);

2931

const SCEV *IVOperExpr = SE.getAddExpr(SE.getUnknown(IVSrc),

2932

SE.getUnknown(IncV));

2933

IVOper = Rewriter.expandCodeFor(IVOperExpr, IVTy, InsertPt);

2934

2935

// If an IV increment can't be folded, use it as the next IV value.

2936

if (!canFoldIVIncExpr(LeftOverExpr, IncI->UserInst, IncI->IVOperand,

2937

TTI)) {

2938

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2938, __PRETTY_FUNCTION__));

2939

IVSrc = IVOper;

2940

LeftOverExpr = nullptr;

2941

}

2942

}

2943

Type *OperTy = IncI->IVOperand->getType();

2944

if (IVTy != OperTy) {

2945

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2946, __PRETTY_FUNCTION__))

2946

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2946, __PRETTY_FUNCTION__));

2947

IRBuilder<> Builder(InsertPt);

2948

IVOper = Builder.CreateTruncOrBitCast(IVOper, OperTy, "lsr.chain");

2949

}

2950

IncI->UserInst->replaceUsesOfWith(IncI->IVOperand, IVOper);

2951

DeadInsts.push_back(IncI->IVOperand);

2952

}

2953

// If LSR created a new, wider phi, we may also replace its postinc. We only

2954

// do this if we also found a wide value for the head of the chain.

2955

if (isa<PHINode>(Chain.tailUserInst())) {

2956

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

2957

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

2958

if (!isCompatibleIVType(Phi, IVSrc))

2959

continue;

2960

Instruction *PostIncV = dyn_cast<Instruction>(

2961

Phi->getIncomingValueForBlock(L->getLoopLatch()));

2962

if (!PostIncV || (SE.getSCEV(PostIncV) != SE.getSCEV(IVSrc)))

2963

continue;

2964

Value *IVOper = IVSrc;

2965

Type *PostIncTy = PostIncV->getType();

2966

if (IVTy != PostIncTy) {

2967

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2967, __PRETTY_FUNCTION__));

2968

IRBuilder<> Builder(L->getLoopLatch()->getTerminator());

2969

Builder.SetCurrentDebugLocation(PostIncV->getDebugLoc());

2970

IVOper = Builder.CreatePointerCast(IVSrc, PostIncTy, "lsr.chain");

2971

}

2972

Phi->replaceUsesOfWith(PostIncV, IVOper);

2973

DeadInsts.push_back(PostIncV);

2974

}

2975

}

2976

}

2977

2978

void LSRInstance::CollectFixupsAndInitialFormulae() {

2979

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

2980

Instruction *UserInst = UI->getUser();

2981

// Skip IV users that are part of profitable IV Chains.

2982

User::op_iterator UseI = std::find(UserInst->op_begin(), UserInst->op_end(),

2983

UI->getOperandValToReplace());

2984

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2984, __PRETTY_FUNCTION__));

2985

if (IVIncSet.count(UseI))

2986

continue;

2987

2988

// Record the uses.

2989

LSRFixup &LF = getNewFixup();

2990

LF.UserInst = UserInst;

2991

LF.OperandValToReplace = UI->getOperandValToReplace();

2992

LF.PostIncLoops = UI->getPostIncLoops();

2993

2994

LSRUse::KindType Kind = LSRUse::Basic;

2995

Type *AccessTy = nullptr;

2996

if (isAddressUse(LF.UserInst, LF.OperandValToReplace)) {

2997

Kind = LSRUse::Address;

2998

AccessTy = getAccessType(LF.UserInst);

2999

}

3000

3001

const SCEV *S = IU.getExpr(*UI);

3002

3003

// Equality (== and !=) ICmps are special. We can rewrite (i == N) as

3004

// (N - i == 0), and this allows (N - i) to be the expression that we work

3005

// with rather than just N or i, so we can consider the register

3006

// requirements for both N and i at the same time. Limiting this code to

3007

// equality icmps is not a problem because all interesting loops use

3008

// equality icmps, thanks to IndVarSimplify.

3009

if (ICmpInst *CI = dyn_cast<ICmpInst>(LF.UserInst))

3010

if (CI->isEquality()) {

3011

// Swap the operands if needed to put the OperandValToReplace on the

3012

// left, for consistency.

3013

Value *NV = CI->getOperand(1);

3014

if (NV == LF.OperandValToReplace) {

3015

CI->setOperand(1, CI->getOperand(0));

3016

CI->setOperand(0, NV);

3017

NV = CI->getOperand(1);

3018

Changed = true;

3019

}

3020

3021

// x == y --> x - y == 0

3022

const SCEV *N = SE.getSCEV(NV);

3023

if (SE.isLoopInvariant(N, L) && isSafeToExpand(N, SE)) {

3024

// S is normalized, so normalize N before folding it into S

3025

// to keep the result normalized.

3026

N = TransformForPostIncUse(Normalize, N, CI, nullptr,

3027

LF.PostIncLoops, SE, DT);

3028

Kind = LSRUse::ICmpZero;

3029

S = SE.getMinusSCEV(N, S);

3030

}

3031

3032

// -1 and the negations of all interesting strides (except the negation

3033

// of -1) are now also interesting.

3034

for (size_t i = 0, e = Factors.size(); i != e; ++i)

3035

if (Factors[i] != -1)

3036

Factors.insert(-(uint64_t)Factors[i]);

3037

Factors.insert(-1);

3038

}

3039

3040

// Set up the initial formula for this use.

3041

std::pair<size_t, int64_t> P = getUse(S, Kind, AccessTy);

3042

LF.LUIdx = P.first;

3043

LF.Offset = P.second;

3044

LSRUse &LU = Uses[LF.LUIdx];

3045

LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);

3046

if (!LU.WidestFixupType ||

3047

SE.getTypeSizeInBits(LU.WidestFixupType) <

3048

SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))

3049

LU.WidestFixupType = LF.OperandValToReplace->getType();

3050

3051

// If this is the first use of this LSRUse, give it a formula.

3052

if (LU.Formulae.empty()) {

3053

InsertInitialFormula(S, LU, LF.LUIdx);

3054

CountRegisters(LU.Formulae.back(), LF.LUIdx);

3055

}

3056

}

3057

3058

DEBUG(print_fixups(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_fixups(dbgs()); } } while (0);

3059

}

3060

3061

/// InsertInitialFormula - Insert a formula for the given expression into

3062

/// the given use, separating out loop-variant portions from loop-invariant

3063

/// and loop-computable portions.

3064

void

3065

LSRInstance::InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx) {

3066

// Mark uses whose expressions cannot be expanded.

3067

if (!isSafeToExpand(S, SE))

3068

LU.RigidFormula = true;

3069

3070

Formula F;

3071

F.InitialMatch(S, L, SE);

3072

bool Inserted = InsertFormula(LU, LUIdx, F);

3073

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3073, __PRETTY_FUNCTION__)); (void)Inserted;

3074

}

3075

3076

/// InsertSupplementalFormula - Insert a simple single-register formula for

3077

/// the given expression into the given use.

3078

void

3079

LSRInstance::InsertSupplementalFormula(const SCEV *S,

3080

LSRUse &LU, size_t LUIdx) {

3081

Formula F;

3082

F.BaseRegs.push_back(S);

3083

F.HasBaseReg = true;

3084

bool Inserted = InsertFormula(LU, LUIdx, F);

3085

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3085, __PRETTY_FUNCTION__)); (void)Inserted;

3086

}

3087

3088

/// CountRegisters - Note which registers are used by the given formula,

3089

/// updating RegUses.

3090

void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) {

3091

if (F.ScaledReg)

3092

RegUses.CountRegister(F.ScaledReg, LUIdx);

3093

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

3094

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

3095

RegUses.CountRegister(*I, LUIdx);

3096

}

3097

3098

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

3099

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

3100

bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) {

3101

// Do not insert formula that we will not be able to expand.

3102

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3103, __PRETTY_FUNCTION__))

3103

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3103, __PRETTY_FUNCTION__));

3104

if (!LU.InsertFormula(F))

3105

return false;

3106

3107

CountRegisters(F, LUIdx);

3108

return true;

3109

}

3110

3111

/// CollectLoopInvariantFixupsAndFormulae - Check for other uses of

3112

/// loop-invariant values which we're tracking. These other uses will pin these

3113

/// values in registers, making them less profitable for elimination.

3114

/// TODO: This currently misses non-constant addrec step registers.

3115

/// TODO: Should this give more weight to users inside the loop?

3116

void

3117

LSRInstance::CollectLoopInvariantFixupsAndFormulae() {

3118

SmallVector<const SCEV *, 8> Worklist(RegUses.begin(), RegUses.end());

3119

SmallPtrSet<const SCEV *, 32> Visited;

3120

3121

while (!Worklist.empty()) {

3122

const SCEV *S = Worklist.pop_back_val();

3123

3124

// Don't process the same SCEV twice

3125

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

3126

continue;

3127

3128

if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S))

3129

Worklist.append(N->op_begin(), N->op_end());

3130

else if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S))

3131

Worklist.push_back(C->getOperand());

3132

else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {

3133

Worklist.push_back(D->getLHS());

3134

Worklist.push_back(D->getRHS());

3135

} else if (const SCEVUnknown *US = dyn_cast<SCEVUnknown>(S)) {

3136

const Value *V = US->getValue();

3137

if (const Instruction *Inst = dyn_cast<Instruction>(V)) {

3138

// Look for instructions defined outside the loop.

3139

if (L->contains(Inst)) continue;

3140

} else if (isa<UndefValue>(V))

3141

// Undef doesn't have a live range, so it doesn't matter.

3142

continue;

3143

for (const Use &U : V->uses()) {

3144

const Instruction *UserInst = dyn_cast<Instruction>(U.getUser());

3145

// Ignore non-instructions.

3146

if (!UserInst)

3147

continue;

3148

// Ignore instructions in other functions (as can happen with

3149

// Constants).

3150

if (UserInst->getParent()->getParent() != L->getHeader()->getParent())

3151

continue;

3152

// Ignore instructions not dominated by the loop.

3153

const BasicBlock *UseBB = !isa<PHINode>(UserInst) ?

3154

UserInst->getParent() :

3155

cast<PHINode>(UserInst)->getIncomingBlock(

3156

PHINode::getIncomingValueNumForOperand(U.getOperandNo()));

3157

if (!DT.dominates(L->getHeader(), UseBB))

3158

continue;

3159

// Ignore uses which are part of other SCEV expressions, to avoid

3160

// analyzing them multiple times.

3161

if (SE.isSCEVable(UserInst->getType())) {

3162

const SCEV *UserS = SE.getSCEV(const_cast<Instruction *>(UserInst));

3163

// If the user is a no-op, look through to its uses.

3164

if (!isa<SCEVUnknown>(UserS))

3165

continue;

3166

if (UserS == US) {

3167

Worklist.push_back(

3168

SE.getUnknown(const_cast<Instruction *>(UserInst)));

3169

continue;

3170

}

3171

}

3172

// Ignore icmp instructions which are already being analyzed.

3173

if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) {

3174

unsigned OtherIdx = !U.getOperandNo();

3175

Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx));

3176

if (SE.hasComputableLoopEvolution(SE.getSCEV(OtherOp), L))

3177

continue;

3178

}

3179

3180

LSRFixup &LF = getNewFixup();

3181

LF.UserInst = const_cast<Instruction *>(UserInst);

3182

LF.OperandValToReplace = U;

3183

std::pair<size_t, int64_t> P = getUse(S, LSRUse::Basic, nullptr);

3184

LF.LUIdx = P.first;

3185

LF.Offset = P.second;

3186

LSRUse &LU = Uses[LF.LUIdx];

3187

LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);

3188

if (!LU.WidestFixupType ||

3189

SE.getTypeSizeInBits(LU.WidestFixupType) <

3190

SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))

3191

LU.WidestFixupType = LF.OperandValToReplace->getType();

3192

InsertSupplementalFormula(US, LU, LF.LUIdx);

3193

CountRegisters(LU.Formulae.back(), Uses.size() - 1);

3194

break;

3195

}

3196

}

3197

}

3198

}

3199

3200

/// CollectSubexprs - Split S into subexpressions which can be pulled out into

3201

/// separate registers. If C is non-null, multiply each subexpression by C.

3202

///

3203

/// Return remainder expression after factoring the subexpressions captured by

3204

/// Ops. If Ops is complete, return NULL.

3205

static const SCEV *CollectSubexprs(const SCEV *S, const SCEVConstant *C,

3206

SmallVectorImpl<const SCEV *> &Ops,

3207

const Loop *L,

3208

ScalarEvolution &SE,

3209

unsigned Depth = 0) {

3210

// Arbitrarily cap recursion to protect compile time.

3211

if (Depth >= 3)

3212

return S;

3213

3214

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

3215

// Break out add operands.

3216

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

3217

I != E; ++I) {

3218

const SCEV *Remainder = CollectSubexprs(*I, C, Ops, L, SE, Depth+1);

3219

if (Remainder)

3220

Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);

3221

}

3222

return nullptr;

3223

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

3224

// Split a non-zero base out of an addrec.

3225

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

3226

return S;

3227

3228

const SCEV *Remainder = CollectSubexprs(AR->getStart(),

3229

C, Ops, L, SE, Depth+1);

3230

// Split the non-zero AddRec unless it is part of a nested recurrence that

3231

// does not pertain to this loop.

3232

if (Remainder && (AR->getLoop() == L || !isa<SCEVAddRecExpr>(Remainder))) {

3233

Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);

3234

Remainder = nullptr;

3235

}

3236

if (Remainder != AR->getStart()) {

3237

if (!Remainder)

3238

Remainder = SE.getConstant(AR->getType(), 0);

3239

return SE.getAddRecExpr(Remainder,

3240

AR->getStepRecurrence(SE),

3241

AR->getLoop(),

3242

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

3243

SCEV::FlagAnyWrap);

3244

}

3245

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

3246

// Break (C * (a + b + c)) into C*a + C*b + C*c.

3247

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

3248

return S;

3249

if (const SCEVConstant *Op0 =

3250

dyn_cast<SCEVConstant>(Mul->getOperand(0))) {

3251

C = C ? cast<SCEVConstant>(SE.getMulExpr(C, Op0)) : Op0;

3252

const SCEV *Remainder =

3253

CollectSubexprs(Mul->getOperand(1), C, Ops, L, SE, Depth+1);

3254

if (Remainder)

3255

Ops.push_back(SE.getMulExpr(C, Remainder));

3256

return nullptr;

3257

}

3258

}

3259

return S;

3260

}

3261

3262

/// \brief Helper function for LSRInstance::GenerateReassociations.

3263

void LSRInstance::GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,

3264

const Formula &Base,

3265

unsigned Depth, size_t Idx,

3266

bool IsScaledReg) {

3267

const SCEV *BaseReg = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];

3268

SmallVector<const SCEV *, 8> AddOps;

3269

const SCEV *Remainder = CollectSubexprs(BaseReg, nullptr, AddOps, L, SE);

3270

if (Remainder)

3271

AddOps.push_back(Remainder);

3272

3273

if (AddOps.size() == 1)

3274

return;

3275

3276

for (SmallVectorImpl<const SCEV *>::const_iterator J = AddOps.begin(),

3277

JE = AddOps.end();

3278

J != JE; ++J) {

3279

3280

// Loop-variant "unknown" values are uninteresting; we won't be able to

3281

// do anything meaningful with them.

3282

if (isa<SCEVUnknown>(*J) && !SE.isLoopInvariant(*J, L))

3283

continue;

3284

3285

// Don't pull a constant into a register if the constant could be folded

3286

// into an immediate field.

3287

if (isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,

3288

LU.AccessTy, *J, Base.getNumRegs() > 1))

3289

continue;

3290

3291

// Collect all operands except *J.

3292

SmallVector<const SCEV *, 8> InnerAddOps(

3293

((const SmallVector<const SCEV *, 8> &)AddOps).begin(), J);

3294

InnerAddOps.append(std::next(J),

3295

((const SmallVector<const SCEV *, 8> &)AddOps).end());

3296

3297

// Don't leave just a constant behind in a register if the constant could

3298

// be folded into an immediate field.

3299

if (InnerAddOps.size() == 1 &&

3300

isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,

3301

LU.AccessTy, InnerAddOps[0], Base.getNumRegs() > 1))

3302

continue;

3303

3304

const SCEV *InnerSum = SE.getAddExpr(InnerAddOps);

3305

if (InnerSum->isZero())

3306

continue;

3307

Formula F = Base;

3308

3309

// Add the remaining pieces of the add back into the new formula.

3310

const SCEVConstant *InnerSumSC = dyn_cast<SCEVConstant>(InnerSum);

3311

if (InnerSumSC && SE.getTypeSizeInBits(InnerSumSC->getType()) <= 64 &&

3312

TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +

3313

InnerSumSC->getValue()->getZExtValue())) {

3314

F.UnfoldedOffset =

3315

(uint64_t)F.UnfoldedOffset + InnerSumSC->getValue()->getZExtValue();

3316

if (IsScaledReg)

3317

F.ScaledReg = nullptr;

3318

else

3319

F.BaseRegs.erase(F.BaseRegs.begin() + Idx);

3320

} else if (IsScaledReg)

3321

F.ScaledReg = InnerSum;

3322

else

3323

F.BaseRegs[Idx] = InnerSum;

3324

3325

// Add J as its own register, or an unfolded immediate.

3326

const SCEVConstant *SC = dyn_cast<SCEVConstant>(*J);

3327

if (SC && SE.getTypeSizeInBits(SC->getType()) <= 64 &&

3328

TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +

3329

SC->getValue()->getZExtValue()))

3330

F.UnfoldedOffset =

3331

(uint64_t)F.UnfoldedOffset + SC->getValue()->getZExtValue();

3332

else

3333

F.BaseRegs.push_back(*J);

3334

// We may have changed the number of register in base regs, adjust the

3335

// formula accordingly.

3336

F.Canonicalize();

3337

3338

if (InsertFormula(LU, LUIdx, F))

3339

// If that formula hadn't been seen before, recurse to find more like

3340

// it.

3341

GenerateReassociations(LU, LUIdx, LU.Formulae.back(), Depth + 1);

3342

}

3343

}

3344

3345

/// GenerateReassociations - Split out subexpressions from adds and the bases of

3346

/// addrecs.

3347

void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx,

3348

Formula Base, unsigned Depth) {

3349

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3349, __PRETTY_FUNCTION__));

3350

// Arbitrarily cap recursion to protect compile time.

3351

if (Depth >= 3)

3352

return;

3353

3354

for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)

3355

GenerateReassociationsImpl(LU, LUIdx, Base, Depth, i);

3356

3357

if (Base.Scale == 1)

3358

GenerateReassociationsImpl(LU, LUIdx, Base, Depth,

3359

/* Idx */ -1, /* IsScaledReg */ true);

3360

}

3361

3362

/// GenerateCombinations - Generate a formula consisting of all of the

3363

/// loop-dominating registers added into a single register.

3364

void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx,

3365

Formula Base) {

3366

// This method is only interesting on a plurality of registers.

3367

if (Base.BaseRegs.size() + (Base.Scale == 1) <= 1)

3368

return;

3369

3370

// Flatten the representation, i.e., reg1 + 1*reg2 => reg1 + reg2, before

3371

// processing the formula.

3372

Base.Unscale();

3373

Formula F = Base;

3374

F.BaseRegs.clear();

3375

SmallVector<const SCEV *, 4> Ops;

3376

for (SmallVectorImpl<const SCEV *>::const_iterator

3377

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

3378

const SCEV *BaseReg = *I;

3379

if (SE.properlyDominates(BaseReg, L->getHeader()) &&

3380

!SE.hasComputableLoopEvolution(BaseReg, L))

3381

Ops.push_back(BaseReg);

3382

else

3383

F.BaseRegs.push_back(BaseReg);

3384

}

3385

if (Ops.size() > 1) {

3386

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

3387

// TODO: If Sum is zero, it probably means ScalarEvolution missed an

3388

// opportunity to fold something. For now, just ignore such cases

3389

// rather than proceed with zero in a register.

3390

if (!Sum->isZero()) {

3391

F.BaseRegs.push_back(Sum);

3392

F.Canonicalize();

3393

(void)InsertFormula(LU, LUIdx, F);

3394

}

3395

}

3396

}

3397

3398

/// \brief Helper function for LSRInstance::GenerateSymbolicOffsets.

3399

void LSRInstance::GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,

3400

const Formula &Base, size_t Idx,

3401

bool IsScaledReg) {

3402

const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];

3403

GlobalValue *GV = ExtractSymbol(G, SE);

3404

if (G->isZero() || !GV)

3405

return;

3406

Formula F = Base;

3407

F.BaseGV = GV;

3408

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))

3409

return;

3410

if (IsScaledReg)

3411

F.ScaledReg = G;

3412

else

3413

F.BaseRegs[Idx] = G;

3414

(void)InsertFormula(LU, LUIdx, F);

3415

}

3416

3417

/// GenerateSymbolicOffsets - Generate reuse formulae using symbolic offsets.

3418

void LSRInstance::GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx,

3419

Formula Base) {

3420

// We can't add a symbolic offset if the address already contains one.

3421

if (Base.BaseGV) return;

3422

3423

for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)

3424

GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, i);

3425

if (Base.Scale == 1)

3426

GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, /* Idx */ -1,

3427

/* IsScaledReg */ true);

3428

}

3429

3430

/// \brief Helper function for LSRInstance::GenerateConstantOffsets.

3431

void LSRInstance::GenerateConstantOffsetsImpl(

3432

LSRUse &LU, unsigned LUIdx, const Formula &Base,

3433

const SmallVectorImpl<int64_t> &Worklist, size_t Idx, bool IsScaledReg) {

3434

const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];

3435

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

3436

E = Worklist.end();

3437

I != E; ++I) {

3438

Formula F = Base;

3439

F.BaseOffset = (uint64_t)Base.BaseOffset - *I;

3440

if (isLegalUse(TTI, LU.MinOffset - *I, LU.MaxOffset - *I, LU.Kind,

3441

LU.AccessTy, F)) {

3442

// Add the offset to the base register.

3443

const SCEV *NewG = SE.getAddExpr(SE.getConstant(G->getType(), *I), G);

3444

// If it cancelled out, drop the base register, otherwise update it.

3445

if (NewG->isZero()) {

3446

if (IsScaledReg) {

3447

F.Scale = 0;

3448

F.ScaledReg = nullptr;

3449

} else

3450

F.DeleteBaseReg(F.BaseRegs[Idx]);

3451

F.Canonicalize();

3452

} else if (IsScaledReg)

3453

F.ScaledReg = NewG;

3454

else

3455

F.BaseRegs[Idx] = NewG;

3456

3457

(void)InsertFormula(LU, LUIdx, F);

3458

}

3459

}

3460

3461

int64_t Imm = ExtractImmediate(G, SE);

3462

if (G->isZero() || Imm == 0)

3463

return;

3464

Formula F = Base;

3465

F.BaseOffset = (uint64_t)F.BaseOffset + Imm;

3466

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))

3467

return;

3468

if (IsScaledReg)

3469

F.ScaledReg = G;

3470

else

3471

F.BaseRegs[Idx] = G;

3472

(void)InsertFormula(LU, LUIdx, F);

3473

}

3474

3475

/// GenerateConstantOffsets - Generate reuse formulae using symbolic offsets.

3476

void LSRInstance::GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx,

3477

Formula Base) {

3478

// TODO: For now, just add the min and max offset, because it usually isn't

3479

// worthwhile looking at everything inbetween.

3480

SmallVector<int64_t, 2> Worklist;

3481

Worklist.push_back(LU.MinOffset);

3482

if (LU.MaxOffset != LU.MinOffset)

3483

Worklist.push_back(LU.MaxOffset);

3484

3485

for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)

3486

GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, i);

3487

if (Base.Scale == 1)

3488

GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, /* Idx */ -1,

3489

/* IsScaledReg */ true);

3490

}

3491

3492

/// GenerateICmpZeroScales - For ICmpZero, check to see if we can scale up

3493

/// the comparison. For example, x == y -> x*c == y*c.

3494

void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,

3495

Formula Base) {

3496

if (LU.Kind != LSRUse::ICmpZero) return;

3497

3498

// Determine the integer type for the base formula.

3499

Type *IntTy = Base.getType();

3500

if (!IntTy) return;

3501

if (SE.getTypeSizeInBits(IntTy) > 64) return;

3502

3503

// Don't do this if there is more than one offset.

3504

if (LU.MinOffset != LU.MaxOffset) return;

3505

3506

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3506, __PRETTY_FUNCTION__));

3507

3508

// Check each interesting stride.

3509

for (SmallSetVector<int64_t, 8>::const_iterator

3510

I = Factors.begin(), E = Factors.end(); I != E; ++I) {

3511

int64_t Factor = *I;

3512

3513

// Check that the multiplication doesn't overflow.

3514

if (Base.BaseOffset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)

3515

continue;

3516

int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor;

3517

if (NewBaseOffset / Factor != Base.BaseOffset)

3518

continue;

3519

// If the offset will be truncated at this use, check that it is in bounds.

3520

if (!IntTy->isPointerTy() &&

3521

!ConstantInt::isValueValidForType(IntTy, NewBaseOffset))

3522

continue;

3523

3524

// Check that multiplying with the use offset doesn't overflow.

3525

int64_t Offset = LU.MinOffset;

3526

if (Offset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)

3527

continue;

3528

Offset = (uint64_t)Offset * Factor;

3529

if (Offset / Factor != LU.MinOffset)

3530

continue;

3531

// If the offset will be truncated at this use, check that it is in bounds.

3532

if (!IntTy->isPointerTy() &&

3533

!ConstantInt::isValueValidForType(IntTy, Offset))

3534

continue;

3535

3536

Formula F = Base;

3537

F.BaseOffset = NewBaseOffset;

3538

3539

// Check that this scale is legal.

3540

if (!isLegalUse(TTI, Offset, Offset, LU.Kind, LU.AccessTy, F))

3541

continue;

3542

3543

// Compensate for the use having MinOffset built into it.

3544

F.BaseOffset = (uint64_t)F.BaseOffset + Offset - LU.MinOffset;

3545

3546

const SCEV *FactorS = SE.getConstant(IntTy, Factor);

3547

3548

// Check that multiplying with each base register doesn't overflow.

3549

for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) {

3550

F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS);

3551

if (getExactSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i])

3552

goto next;

3553

}

3554

3555

// Check that multiplying with the scaled register doesn't overflow.

3556

if (F.ScaledReg) {

3557

F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS);

3558

if (getExactSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg)

3559

continue;

3560

}

3561

3562

// Check that multiplying with the unfolded offset doesn't overflow.

3563

if (F.UnfoldedOffset != 0) {

3564

if (F.UnfoldedOffset == INT64_MIN(-9223372036854775807L -1) && Factor == -1)

3565

continue;

3566

F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor;

3567

if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset)

3568

continue;

3569

// If the offset will be truncated, check that it is in bounds.

3570

if (!IntTy->isPointerTy() &&

3571

!ConstantInt::isValueValidForType(IntTy, F.UnfoldedOffset))

3572

continue;

3573

}

3574

3575

// If we make it here and it's legal, add it.

3576

(void)InsertFormula(LU, LUIdx, F);

3577

next:;

3578

}

3579

}

3580

3581

/// GenerateScales - Generate stride factor reuse formulae by making use of

3582

/// scaled-offset address modes, for example.

3583

void LSRInstance::GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base) {

3584

// Determine the integer type for the base formula.

3585

Type *IntTy = Base.getType();

3586

if (!IntTy) return;

3587

3588

// If this Formula already has a scaled register, we can't add another one.

3589

// Try to unscale the formula to generate a better scale.

3590

if (Base.Scale != 0 && !Base.Unscale())

3591

return;

3592

3593

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3593, __PRETTY_FUNCTION__));

3594

3595

// Check each interesting stride.

3596

for (SmallSetVector<int64_t, 8>::const_iterator

3597

I = Factors.begin(), E = Factors.end(); I != E; ++I) {

3598

int64_t Factor = *I;

3599

3600

Base.Scale = Factor;

3601

Base.HasBaseReg = Base.BaseRegs.size() > 1;

3602

// Check whether this scale is going to be legal.

3603

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,

3604

Base)) {

3605

// As a special-case, handle special out-of-loop Basic users specially.

3606

// TODO: Reconsider this special case.

3607

if (LU.Kind == LSRUse::Basic &&

3608

isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LSRUse::Special,

3609

LU.AccessTy, Base) &&

3610

LU.AllFixupsOutsideLoop)

3611

LU.Kind = LSRUse::Special;

3612

else

3613

continue;

3614

}

3615

// For an ICmpZero, negating a solitary base register won't lead to

3616

// new solutions.

3617

if (LU.Kind == LSRUse::ICmpZero &&

3618

!Base.HasBaseReg && Base.BaseOffset == 0 && !Base.BaseGV)

3619

continue;

3620

// For each addrec base reg, apply the scale, if possible.

3621

for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)

3622

if (const SCEVAddRecExpr *AR =

3623

dyn_cast<SCEVAddRecExpr>(Base.BaseRegs[i])) {

3624

const SCEV *FactorS = SE.getConstant(IntTy, Factor);

3625

if (FactorS->isZero())

3626

continue;

3627

// Divide out the factor, ignoring high bits, since we'll be

3628

// scaling the value back up in the end.

3629

if (const SCEV *Quotient = getExactSDiv(AR, FactorS, SE, true)) {

3630

// TODO: This could be optimized to avoid all the copying.

3631

Formula F = Base;

3632

F.ScaledReg = Quotient;

3633

F.DeleteBaseReg(F.BaseRegs[i]);

3634

// The canonical representation of 1*reg is reg, which is already in

3635

// Base. In that case, do not try to insert the formula, it will be

3636

// rejected anyway.

3637

if (F.Scale == 1 && F.BaseRegs.empty())

3638

continue;

3639

(void)InsertFormula(LU, LUIdx, F);

3640

}

3641

}

3642

}

3643

}

3644

3645

/// GenerateTruncates - Generate reuse formulae from different IV types.

3646

void LSRInstance::GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base) {

3647

// Don't bother truncating symbolic values.

3648

if (Base.BaseGV) return;

3649

3650

// Determine the integer type for the base formula.

3651

Type *DstTy = Base.getType();

3652

if (!DstTy) return;

3653

DstTy = SE.getEffectiveSCEVType(DstTy);

3654

3655

for (SmallSetVector<Type *, 4>::const_iterator

3656

I = Types.begin(), E = Types.end(); I != E; ++I) {

3657

Type *SrcTy = *I;

3658

if (SrcTy != DstTy && TTI.isTruncateFree(SrcTy, DstTy)) {

3659

Formula F = Base;

3660

3661

if (F.ScaledReg) F.ScaledReg = SE.getAnyExtendExpr(F.ScaledReg, *I);

3662

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

3663

JE = F.BaseRegs.end(); J != JE; ++J)

3664

*J = SE.getAnyExtendExpr(*J, SrcTy);

3665

3666

// TODO: This assumes we've done basic processing on all uses and

3667

// have an idea what the register usage is.

3668

if (!F.hasRegsUsedByUsesOtherThan(LUIdx, RegUses))

3669

continue;

3670

3671

(void)InsertFormula(LU, LUIdx, F);

3672

}

3673

}

3674

}

3675

3676

namespace {

3677

3678

/// WorkItem - Helper class for GenerateCrossUseConstantOffsets. It's used to

3679

/// defer modifications so that the search phase doesn't have to worry about

3680

/// the data structures moving underneath it.

3681

struct WorkItem {

3682

size_t LUIdx;

3683

int64_t Imm;

3684

const SCEV *OrigReg;

3685

3686

WorkItem(size_t LI, int64_t I, const SCEV *R)

3687

: LUIdx(LI), Imm(I), OrigReg(R) {}

3688

3689

void print(raw_ostream &OS) const;

3690

void dump() const;

3691

};

3692

3693

}

3694

3695

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

3696

OS << "in formulae referencing " << *OrigReg << " in use " << LUIdx

3697

<< " , add offset " << Imm;

3698

}

3699

3700

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

3701

void WorkItem::dump() const {

3702

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

3703

}

3704

#endif

3705

3706

/// GenerateCrossUseConstantOffsets - Look for registers which are a constant

3707

/// distance apart and try to form reuse opportunities between them.

3708

void LSRInstance::GenerateCrossUseConstantOffsets() {

3709

// Group the registers by their value without any added constant offset.

3710

typedef std::map<int64_t, const SCEV *> ImmMapTy;

3711

typedef DenseMap<const SCEV *, ImmMapTy> RegMapTy;

3712

RegMapTy Map;

3713

DenseMap<const SCEV *, SmallBitVector> UsedByIndicesMap;

3714

SmallVector<const SCEV *, 8> Sequence;

3715

for (RegUseTracker::const_iterator I = RegUses.begin(), E = RegUses.end();

3716

I != E; ++I) {

3717

const SCEV *Reg = *I;

3718

int64_t Imm = ExtractImmediate(Reg, SE);

3719

std::pair<RegMapTy::iterator, bool> Pair =

3720

Map.insert(std::make_pair(Reg, ImmMapTy()));

3721

if (Pair.second)

3722

Sequence.push_back(Reg);

3723

Pair.first->second.insert(std::make_pair(Imm, *I));

3724

UsedByIndicesMap[Reg] |= RegUses.getUsedByIndices(*I);

3725

}

3726

3727

// Now examine each set of registers with the same base value. Build up

3728

// a list of work to do and do the work in a separate step so that we're

3729

// not adding formulae and register counts while we're searching.

3730

SmallVector<WorkItem, 32> WorkItems;

3731

SmallSet<std::pair<size_t, int64_t>, 32> UniqueItems;

3732

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

3733

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

3734

const SCEV *Reg = *I;

3735

const ImmMapTy &Imms = Map.find(Reg)->second;

3736

3737

// It's not worthwhile looking for reuse if there's only one offset.

3738

if (Imms.size() == 1)

3739

continue;

3740

3741

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
)

3742

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
)

3743

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
)

3744

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
)

3745

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
);

3746

3747

// Examine each offset.

3748

for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end();

3749

J != JE; ++J) {

3750

const SCEV *OrigReg = J->second;

3751

3752

int64_t JImm = J->first;

3753

const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(OrigReg);

3754

3755

if (!isa<SCEVConstant>(OrigReg) &&

3756

UsedByIndicesMap[Reg].count() == 1) {

3757

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);

3758

continue;

3759

}

3760

3761

// Conservatively examine offsets between this orig reg a few selected

3762

// other orig regs.

3763

ImmMapTy::const_iterator OtherImms[] = {

3764

Imms.begin(), std::prev(Imms.end()),

3765

Imms.lower_bound((Imms.begin()->first + std::prev(Imms.end())->first) /

3766

3767

};

3768

for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) {

3769

ImmMapTy::const_iterator M = OtherImms[i];

3770

if (M == J || M == JE) continue;

3771

3772

// Compute the difference between the two.

3773

int64_t Imm = (uint64_t)JImm - M->first;

3774

for (int LUIdx = UsedByIndices.find_first(); LUIdx != -1;

3775

LUIdx = UsedByIndices.find_next(LUIdx))

3776

// Make a memo of this use, offset, and register tuple.

3777

if (UniqueItems.insert(std::make_pair(LUIdx, Imm)).second)

3778

WorkItems.push_back(WorkItem(LUIdx, Imm, OrigReg));

3779

}

3780

}

3781

}

3782

3783

Map.clear();

3784

Sequence.clear();

3785

UsedByIndicesMap.clear();

3786

UniqueItems.clear();

3787

3788

// Now iterate through the worklist and add new formulae.

3789

for (SmallVectorImpl<WorkItem>::const_iterator I = WorkItems.begin(),

3790

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

3791

const WorkItem &WI = *I;

3792

size_t LUIdx = WI.LUIdx;

3793

LSRUse &LU = Uses[LUIdx];

3794

int64_t Imm = WI.Imm;

3795

const SCEV *OrigReg = WI.OrigReg;

3796

3797

Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType());

3798

const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, -(uint64_t)Imm));

3799

unsigned BitWidth = SE.getTypeSizeInBits(IntTy);

3800

3801

// TODO: Use a more targeted data structure.

3802

for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) {

3803

Formula F = LU.Formulae[L];

3804

// FIXME: The code for the scaled and unscaled registers looks

3805

// very similar but slightly different. Investigate if they

3806

// could be merged. That way, we would not have to unscale the

3807

// Formula.

3808

F.Unscale();

3809

// Use the immediate in the scaled register.

3810

if (F.ScaledReg == OrigReg) {

3811

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

3812

// Don't create 50 + reg(-50).

3813

if (F.referencesReg(SE.getSCEV(

3814

ConstantInt::get(IntTy, -(uint64_t)Offset))))

3815

continue;

3816

Formula NewF = F;

3817

NewF.BaseOffset = Offset;

3818

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,

3819

NewF))

3820

continue;

3821

NewF.ScaledReg = SE.getAddExpr(NegImmS, NewF.ScaledReg);

3822

3823

// If the new scale is a constant in a register, and adding the constant

3824

// value to the immediate would produce a value closer to zero than the

3825

// immediate itself, then the formula isn't worthwhile.

3826

if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewF.ScaledReg))

3827

if (C->getValue()->isNegative() !=

3828

(NewF.BaseOffset < 0) &&

3829

(C->getValue()->getValue().abs() * APInt(BitWidth, F.Scale))

3830

.ule(abs64(NewF.BaseOffset)))

3831

continue;

3832

3833

// OK, looks good.

3834

NewF.Canonicalize();

3835

(void)InsertFormula(LU, LUIdx, NewF);

3836

} else {

3837

// Use the immediate in a base register.

3838

for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) {

3839

const SCEV *BaseReg = F.BaseRegs[N];

3840

if (BaseReg != OrigReg)

3841

continue;

3842

Formula NewF = F;

3843

NewF.BaseOffset = (uint64_t)NewF.BaseOffset + Imm;

3844

if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset,

3845

LU.Kind, LU.AccessTy, NewF)) {

3846

if (!TTI.isLegalAddImmediate((uint64_t)NewF.UnfoldedOffset + Imm))

3847

continue;

3848

NewF = F;

3849

NewF.UnfoldedOffset = (uint64_t)NewF.UnfoldedOffset + Imm;

3850

}

3851

NewF.BaseRegs[N] = SE.getAddExpr(NegImmS, BaseReg);

3852

3853

// If the new formula has a constant in a register, and adding the

3854

// constant value to the immediate would produce a value closer to

3855

// zero than the immediate itself, then the formula isn't worthwhile.

3856

for (SmallVectorImpl<const SCEV *>::const_iterator

3857

J = NewF.BaseRegs.begin(), JE = NewF.BaseRegs.end();

3858

J != JE; ++J)

3859

if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*J))

3860

if ((C->getValue()->getValue() + NewF.BaseOffset).abs().slt(

3861

abs64(NewF.BaseOffset)) &&

3862

(C->getValue()->getValue() +

3863

NewF.BaseOffset).countTrailingZeros() >=

3864

countTrailingZeros<uint64_t>(NewF.BaseOffset))

3865

goto skip_formula;

3866

3867

// Ok, looks good.

3868

NewF.Canonicalize();

3869

(void)InsertFormula(LU, LUIdx, NewF);

3870

break;

3871

skip_formula:;

3872

}

3873

}

3874

}

3875

}

3876

}

3877

3878

/// GenerateAllReuseFormulae - Generate formulae for each use.

3879

void

3880

LSRInstance::GenerateAllReuseFormulae() {

3881

// This is split into multiple loops so that hasRegsUsedByUsesOtherThan

3882

// queries are more precise.

3883

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

3884

LSRUse &LU = Uses[LUIdx];

3885

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3886

GenerateReassociations(LU, LUIdx, LU.Formulae[i]);

3887

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3888

GenerateCombinations(LU, LUIdx, LU.Formulae[i]);

3889

}

3890

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

3891

LSRUse &LU = Uses[LUIdx];

3892

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3893

GenerateSymbolicOffsets(LU, LUIdx, LU.Formulae[i]);

3894

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3895

GenerateConstantOffsets(LU, LUIdx, LU.Formulae[i]);

3896

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3897

GenerateICmpZeroScales(LU, LUIdx, LU.Formulae[i]);

3898

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3899

GenerateScales(LU, LUIdx, LU.Formulae[i]);

3900

}

3901

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

3902

LSRUse &LU = Uses[LUIdx];

3903

for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)

3904

GenerateTruncates(LU, LUIdx, LU.Formulae[i]);

3905

}

3906

3907

GenerateCrossUseConstantOffsets();

3908

3909

DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (0)

3910

"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)

3911

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (0);

3912

}

3913

3914

/// If there are multiple formulae with the same set of registers used

3915

/// by other uses, pick the best one and delete the others.

3916

void LSRInstance::FilterOutUndesirableDedicatedRegisters() {

3917

DenseSet<const SCEV *> VisitedRegs;

3918

SmallPtrSet<const SCEV *, 16> Regs;

3919

SmallPtrSet<const SCEV *, 16> LoserRegs;

3920

#ifndef NDEBUG

3921

bool ChangedFormulae = false;

3922

#endif

3923

3924

// Collect the best formula for each unique set of shared registers. This

3925

// is reset for each use.

3926

typedef DenseMap<SmallVector<const SCEV *, 4>, size_t, UniquifierDenseMapInfo>

3927

BestFormulaeTy;

3928

BestFormulaeTy BestFormulae;

3929

3930

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

3931

LSRUse &LU = Uses[LUIdx];

3932

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);

3933

3934

bool Any = false;

3935

for (size_t FIdx = 0, NumForms = LU.Formulae.size();

3936

FIdx != NumForms; ++FIdx) {

3937

Formula &F = LU.Formulae[FIdx];

3938

3939

// Some formulas are instant losers. For example, they may depend on

3940

// nonexistent AddRecs from other loops. These need to be filtered

3941

// immediately, otherwise heuristics could choose them over others leading

3942

// to an unsatisfactory solution. Passing LoserRegs into RateFormula here

3943

// avoids the need to recompute this information across formulae using the

3944

// same bad AddRec. Passing LoserRegs is also essential unless we remove

3945

// the corresponding bad register from the Regs set.

3946

Cost CostF;

3947

Regs.clear();

3948

CostF.RateFormula(TTI, F, Regs, VisitedRegs, L, LU.Offsets, SE, DT, LU,

3949

&LoserRegs);

3950

if (CostF.isLoser()) {

3951

// During initial formula generation, undesirable formulae are generated

3952

// by uses within other loops that have some non-trivial address mode or

3953

// use the postinc form of the IV. LSR needs to provide these formulae

3954

// as the basis of rediscovering the desired formula that uses an AddRec

3955

// corresponding to the existing phi. Once all formulae have been

3956

// generated, these initial losers may be pruned.

3957

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)

3958

dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering loser "; F.print
(dbgs()); dbgs() << "\n"; } } while (0);

3959

}

3960

else {

3961

SmallVector<const SCEV *, 4> Key;

3962

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

3963

JE = F.BaseRegs.end(); J != JE; ++J) {

3964

const SCEV *Reg = *J;

3965

if (RegUses.isRegUsedByUsesOtherThan(Reg, LUIdx))

3966

Key.push_back(Reg);

3967

}

3968

if (F.ScaledReg &&

3969

RegUses.isRegUsedByUsesOtherThan(F.ScaledReg, LUIdx))

3970

Key.push_back(F.ScaledReg);

3971

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

3972

// uniquifying.

3973

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

3974

3975

std::pair<BestFormulaeTy::const_iterator, bool> P =

3976

BestFormulae.insert(std::make_pair(Key, FIdx));

3977

if (P.second)

3978

continue;

3979

3980

Formula &Best = LU.Formulae[P.first->second];

3981

3982

Cost CostBest;

3983

Regs.clear();

3984

CostBest.RateFormula(TTI, Best, Regs, VisitedRegs, L, LU.Offsets, SE,

3985

DT, LU);

3986

if (CostF < CostBest)

3987

std::swap(F, Best);

3988

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)

3989

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)

3990

" 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)

3991

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);

3992

}

3993

#ifndef NDEBUG

3994

ChangedFormulae = true;

3995

#endif

3996

LU.DeleteFormula(F);

3997

--FIdx;

3998

--NumForms;

3999

Any = true;

4000

}

4001

4002

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

4003

if (Any)

4004

LU.RecomputeRegs(LUIdx, RegUses);

4005

4006

// Reset this to prepare for the next use.

4007

BestFormulae.clear();

4008

}

4009

4010

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)

4011

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)

4012

"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)

4013

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)

4014

})do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (0);

4015

}

4016

4017

// This is a rough guess that seems to work fairly well.

4018

static const size_t ComplexityLimit = UINT16_MAX(65535);

4019

4020

/// EstimateSearchSpaceComplexity - Estimate the worst-case number of

4021

/// solutions the solver might have to consider. It almost never considers

4022

/// this many solutions because it prune the search space, but the pruning

4023

/// isn't always sufficient.

4024

size_t LSRInstance::EstimateSearchSpaceComplexity() const {

4025

size_t Power = 1;

4026

for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(),

4027

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

4028

size_t FSize = I->Formulae.size();

4029

if (FSize >= ComplexityLimit) {

4030

Power = ComplexityLimit;

4031

break;

4032

}

4033

Power *= FSize;

4034

if (Power >= ComplexityLimit)

4035

break;

4036

}

4037

return Power;

4038

}

4039

4040

/// NarrowSearchSpaceByDetectingSupersets - When one formula uses a superset

4041

/// of the registers of another formula, it won't help reduce register

4042

/// pressure (though it may not necessarily hurt register pressure); remove

4043

/// it to simplify the system.

4044

void LSRInstance::NarrowSearchSpaceByDetectingSupersets() {

4045

if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {

4046

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);

4047

4048

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)

4049

"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)

4050

"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);

4051

4052

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

4053

LSRUse &LU = Uses[LUIdx];

4054

bool Any = false;

4055

for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {

4056

Formula &F = LU.Formulae[i];

4057

// Look for a formula with a constant or GV in a register. If the use

4058

// also has a formula with that same value in an immediate field,

4059

// delete the one that uses a register.

4060

for (SmallVectorImpl<const SCEV *>::const_iterator

4061

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

4062

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

4063

Formula NewF = F;

4064

NewF.BaseOffset += C->getValue()->getSExtValue();

4065

NewF.BaseRegs.erase(NewF.BaseRegs.begin() +

4066

(I - F.BaseRegs.begin()));

4067

if (LU.HasFormulaWithSameRegs(NewF)) {

4068

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);

4069

LU.DeleteFormula(F);

4070

--i;

4071

--e;

4072

Any = true;

4073

break;

4074

}

4075

} else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(*I)) {

4076

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

4077

if (!F.BaseGV) {

4078

Formula NewF = F;

4079

NewF.BaseGV = GV;

4080

NewF.BaseRegs.erase(NewF.BaseRegs.begin() +

4081

(I - F.BaseRegs.begin()));

4082

if (LU.HasFormulaWithSameRegs(NewF)) {

4083

DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)

4084

dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0);

4085

LU.DeleteFormula(F);

4086

--i;

4087

--e;

4088

Any = true;

4089

break;

4090

}

4091

}

4092

}

4093

}

4094

}

4095

if (Any)

4096

LU.RecomputeRegs(LUIdx, RegUses);

4097

}

4098

4099

DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)

4100

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0);

4101

}

4102

}

4103

4104

/// NarrowSearchSpaceByCollapsingUnrolledCode - When there are many registers

4105

/// for expressions like A, A+1, A+2, etc., allocate a single register for

4106

/// them.

4107

void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() {

4108

if (EstimateSearchSpaceComplexity() < ComplexityLimit)

4109

return;

4110

4111

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)

4112

"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)

4113

"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);

4114

4115

// This is especially useful for unrolled loops.

4116

4117

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

4118

LSRUse &LU = Uses[LUIdx];

4119

for (SmallVectorImpl<Formula>::const_iterator I = LU.Formulae.begin(),

4120

E = LU.Formulae.end(); I != E; ++I) {

4121

const Formula &F = *I;

4122

if (F.BaseOffset == 0 || (F.Scale != 0 && F.Scale != 1))

4123

continue;

4124

4125

LSRUse *LUThatHas = FindUseWithSimilarFormula(F, LU);

4126

if (!LUThatHas)

4127

continue;

4128

4129

if (!reconcileNewOffset(*LUThatHas, F.BaseOffset, /*HasBaseReg=*/ false,

4130

LU.Kind, LU.AccessTy))

4131

continue;

4132

4133

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);

4134

4135

LUThatHas->AllFixupsOutsideLoop &= LU.AllFixupsOutsideLoop;

4136

4137

// Update the relocs to reference the new use.

4138

for (SmallVectorImpl<LSRFixup>::iterator I = Fixups.begin(),

4139

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

4140

LSRFixup &Fixup = *I;

4141

if (Fixup.LUIdx == LUIdx) {

4142

Fixup.LUIdx = LUThatHas - &Uses.front();

4143

Fixup.Offset += F.BaseOffset;

4144

// Add the new offset to LUThatHas' offset list.

4145

if (LUThatHas->Offsets.back() != Fixup.Offset) {

4146

LUThatHas->Offsets.push_back(Fixup.Offset);

4147

if (Fixup.Offset > LUThatHas->MaxOffset)

4148

LUThatHas->MaxOffset = Fixup.Offset;

4149

if (Fixup.Offset < LUThatHas->MinOffset)

4150

LUThatHas->MinOffset = Fixup.Offset;

4151

}

4152

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);

4153

}

4154

if (Fixup.LUIdx == NumUses-1)

4155

Fixup.LUIdx = LUIdx;

4156

}

4157

4158

// Delete formulae from the new use which are no longer legal.

4159

bool Any = false;

4160

for (size_t i = 0, e = LUThatHas->Formulae.size(); i != e; ++i) {

4161

Formula &F = LUThatHas->Formulae[i];

4162

if (!isLegalUse(TTI, LUThatHas->MinOffset, LUThatHas->MaxOffset,

4163

LUThatHas->Kind, LUThatHas->AccessTy, F)) {

4164

DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0)

4165

dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (0);

4166

LUThatHas->DeleteFormula(F);

4167

--i;

4168

--e;

4169

Any = true;

4170

}

4171

}

4172

4173

if (Any)

4174

LUThatHas->RecomputeRegs(LUThatHas - &Uses.front(), RegUses);

4175

4176

// Delete the old use.

4177

DeleteUse(LU, LUIdx);

4178

--LUIdx;

4179

--NumUses;

4180

break;

4181

}

4182

}

4183

4184

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);

4185

}

4186

4187

/// NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters - Call

4188

/// FilterOutUndesirableDedicatedRegisters again, if necessary, now that

4189

/// we've done more filtering, as it may be able to find more formulae to

4190

/// eliminate.

4191

void LSRInstance::NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(){

4192

if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {

4193

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);

4194

4195

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)

4196

"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);

4197

4198

FilterOutUndesirableDedicatedRegisters();

4199

4200

DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)

4201

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0);

4202

}

4203

}

4204

4205

/// NarrowSearchSpaceByPickingWinnerRegs - Pick a register which seems likely

4206

/// to be profitable, and then in any use which has any reference to that

4207

/// register, delete all formulae which do not reference that register.

4208

void LSRInstance::NarrowSearchSpaceByPickingWinnerRegs() {

4209

// With all other options exhausted, loop until the system is simple

4210

// enough to handle.

4211

SmallPtrSet<const SCEV *, 4> Taken;

4212

while (EstimateSearchSpaceComplexity() >= ComplexityLimit) {

4213

// Ok, we have too many of formulae on our hands to conveniently handle.

4214

// Use a rough heuristic to thin out the list.

4215

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);

4216

4217

// Pick the register which is used by the most LSRUses, which is likely

4218

// to be a good reuse register candidate.

4219

const SCEV *Best = nullptr;

4220

unsigned BestNum = 0;

4221

for (RegUseTracker::const_iterator I = RegUses.begin(), E = RegUses.end();

4222

I != E; ++I) {

4223

const SCEV *Reg = *I;

4224

if (Taken.count(Reg))

4225

continue;

4226

if (!Best)

4227

Best = Reg;

4228

else {

4229

unsigned Count = RegUses.getUsedByIndices(Reg).count();

4230

if (Count > BestNum) {

4231

Best = Reg;

4232

BestNum = Count;

4233

}

4234

}

4235

}

4236

4237

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)

4238

<< " 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);

4239

Taken.insert(Best);

4240

4241

// In any use with formulae which references this register, delete formulae

4242

// which don't reference it.

4243

for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {

4244

LSRUse &LU = Uses[LUIdx];

4245

if (!LU.Regs.count(Best)) continue;

4246

4247

bool Any = false;

4248

for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {

4249

Formula &F = LU.Formulae[i];

4250

if (!F.referencesReg(Best)) {

4251

4252

LU.DeleteFormula(F);

4253

--e;

4254

--i;

4255

Any = true;

4256

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4256, __PRETTY_FUNCTION__));

4257

continue;

4258

}

4259

}

4260

4261

if (Any)

4262

LU.RecomputeRegs(LUIdx, RegUses);

4263

}

4264

4265

DEBUG(dbgs() << "After pre-selection:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0)

4266

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (0);

4267

}

4268

}

4269

4270

/// NarrowSearchSpaceUsingHeuristics - If there are an extraordinary number of

4271

/// formulae to choose from, use some rough heuristics to prune down the number

4272

/// of formulae. This keeps the main solver from taking an extraordinary amount

4273

/// of time in some worst-case scenarios.

4274

void LSRInstance::NarrowSearchSpaceUsingHeuristics() {

4275

NarrowSearchSpaceByDetectingSupersets();

4276

NarrowSearchSpaceByCollapsingUnrolledCode();

4277

NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();

4278

NarrowSearchSpaceByPickingWinnerRegs();

4279

}

4280

4281

/// SolveRecurse - This is the recursive solver.

4282

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

4283

Cost &SolutionCost,

4284

SmallVectorImpl<const Formula *> &Workspace,

4285

const Cost &CurCost,

4286

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

4287

DenseSet<const SCEV *> &VisitedRegs) const {

4288

// Some ideas:

4289

// - prune more:

4290

// - use more aggressive filtering

4291

// - sort the formula so that the most profitable solutions are found first

4292

// - sort the uses too

4293

// - search faster:

4294

// - don't compute a cost, and then compare. compare while computing a cost

4295

// and bail early.

4296

// - track register sets with SmallBitVector

4297

4298

const LSRUse &LU = Uses[Workspace.size()];

4299

4300

// If this use references any register that's already a part of the

4301

// in-progress solution, consider it a requirement that a formula must

4302

// reference that register in order to be considered. This prunes out

4303

// unprofitable searching.

4304

SmallSetVector<const SCEV *, 4> ReqRegs;

4305

for (const SCEV *S : CurRegs)

4306

if (LU.Regs.count(S))

4307

ReqRegs.insert(S);

4308

4309

SmallPtrSet<const SCEV *, 16> NewRegs;

4310

Cost NewCost;

4311

for (SmallVectorImpl<Formula>::const_iterator I = LU.Formulae.begin(),

4312

E = LU.Formulae.end(); I != E; ++I) {

4313

const Formula &F = *I;

4314

4315

// Ignore formulae which may not be ideal in terms of register reuse of

4316

// ReqRegs. The formula should use all required registers before

4317

// introducing new ones.

4318

int NumReqRegsToFind = std::min(F.getNumRegs(), ReqRegs.size());

4319

for (SmallSetVector<const SCEV *, 4>::const_iterator J = ReqRegs.begin(),

4320

JE = ReqRegs.end(); J != JE; ++J) {

4321

const SCEV *Reg = *J;

4322

if ((F.ScaledReg && F.ScaledReg == Reg) ||

4323

std::find(F.BaseRegs.begin(), F.BaseRegs.end(), Reg) !=

4324

F.BaseRegs.end()) {

4325

--NumReqRegsToFind;

4326

if (NumReqRegsToFind == 0)

4327

break;

4328

}

4329

}

4330

if (NumReqRegsToFind != 0) {

4331

// If none of the formulae satisfied the required registers, then we could

4332

// clear ReqRegs and try again. Currently, we simply give up in this case.

4333

continue;

4334

}

4335

4336

// Evaluate the cost of the current formula. If it's already worse than

4337

// the current best, prune the search at that point.

4338

NewCost = CurCost;

4339

NewRegs = CurRegs;

4340

NewCost.RateFormula(TTI, F, NewRegs, VisitedRegs, L, LU.Offsets, SE, DT,

4341

LU);

4342

if (NewCost < SolutionCost) {

4343

Workspace.push_back(&F);

4344

if (Workspace.size() != Uses.size()) {

4345

SolveRecurse(Solution, SolutionCost, Workspace, NewCost,

4346

NewRegs, VisitedRegs);

4347

if (F.getNumRegs() == 1 && Workspace.size() == 1)

4348

VisitedRegs.insert(F.ScaledReg ? F.ScaledReg : F.BaseRegs[0]);

4349

} else {

4350

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)

4351

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)

4352

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)

4353

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)

4354

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);

4355

4356

SolutionCost = NewCost;

4357

Solution = Workspace;

4358

}

4359

Workspace.pop_back();

4360

}

4361

}

4362

}

4363

4364

/// Solve - Choose one formula from each use. Return the results in the given

4365

/// Solution vector.

4366

void LSRInstance::Solve(SmallVectorImpl<const Formula *> &Solution) const {

4367

SmallVector<const Formula *, 8> Workspace;

4368

Cost SolutionCost;

4369

SolutionCost.Lose();

4370

Cost CurCost;

4371

SmallPtrSet<const SCEV *, 16> CurRegs;

4372

DenseSet<const SCEV *> VisitedRegs;

4373

Workspace.reserve(Uses.size());

4374

4375

// SolveRecurse does all the work.

4376

SolveRecurse(Solution, SolutionCost, Workspace, CurCost,

4377

CurRegs, VisitedRegs);

4378

if (Solution.empty()) {

4379

DEBUG(dbgs() << "\nNo Satisfactory Solution\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nNo Satisfactory Solution\n"
; } } while (0);

4380

return;

4381

}

4382

4383

// Ok, we've now made all our decisions.

4384

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)

4385

"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)

4386

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)

4387

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)

4388

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)

4389

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)

4390

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)

4391

" ";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)

4392

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)

4393

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)

4394

})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);

4395

4396

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4396, __PRETTY_FUNCTION__));

4397

}

4398

4399

/// HoistInsertPosition - Helper for AdjustInsertPositionForExpand. Climb up

4400

/// the dominator tree far as we can go while still being dominated by the

4401

/// input positions. This helps canonicalize the insert position, which

4402

/// encourages sharing.

4403

BasicBlock::iterator

4404

LSRInstance::HoistInsertPosition(BasicBlock::iterator IP,

4405

const SmallVectorImpl<Instruction *> &Inputs)

4406

const {

4407

for (;;) {

4408

const Loop *IPLoop = LI.getLoopFor(IP->getParent());

4409

unsigned IPLoopDepth = IPLoop ? IPLoop->getLoopDepth() : 0;

4410

4411

BasicBlock *IDom;

4412

for (DomTreeNode *Rung = DT.getNode(IP->getParent()); ; ) {

4413

if (!Rung) return IP;

4414

Rung = Rung->getIDom();

4415

if (!Rung) return IP;

4416

IDom = Rung->getBlock();

4417

4418

// Don't climb into a loop though.

4419

const Loop *IDomLoop = LI.getLoopFor(IDom);

4420

unsigned IDomDepth = IDomLoop ? IDomLoop->getLoopDepth() : 0;

4421

if (IDomDepth <= IPLoopDepth &&

4422

(IDomDepth != IPLoopDepth || IDomLoop == IPLoop))

4423

break;

4424

}

4425

4426

bool AllDominate = true;

4427

Instruction *BetterPos = nullptr;

4428

Instruction *Tentative = IDom->getTerminator();

4429

for (SmallVectorImpl<Instruction *>::const_iterator I = Inputs.begin(),

4430

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

4431

Instruction *Inst = *I;

4432

if (Inst == Tentative || !DT.dominates(Inst, Tentative)) {

4433

AllDominate = false;

4434

break;

4435

}

4436

// Attempt to find an insert position in the middle of the block,

4437

// instead of at the end, so that it can be used for other expansions.

4438

if (IDom == Inst->getParent() &&

4439

(!BetterPos || !DT.dominates(Inst, BetterPos)))

4440

BetterPos = std::next(BasicBlock::iterator(Inst));

4441

}

4442

if (!AllDominate)

4443

break;

4444

if (BetterPos)

4445

IP = BetterPos;

4446

else

4447

IP = Tentative;

4448

}

4449

4450

return IP;

4451

}

4452

4453

/// AdjustInsertPositionForExpand - Determine an input position which will be

4454

/// dominated by the operands and which will dominate the result.

4455

BasicBlock::iterator

4456

LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP,

4457

const LSRFixup &LF,

4458

const LSRUse &LU,

4459

SCEVExpander &Rewriter) const {

4460

// Collect some instructions which must be dominated by the

4461

// expanding replacement. These must be dominated by any operands that

4462

// will be required in the expansion.

4463

SmallVector<Instruction *, 4> Inputs;

4464

if (Instruction *I = dyn_cast<Instruction>(LF.OperandValToReplace))

4465

Inputs.push_back(I);

4466

if (LU.Kind == LSRUse::ICmpZero)

4467

if (Instruction *I =

4468

dyn_cast<Instruction>(cast<ICmpInst>(LF.UserInst)->getOperand(1)))

4469

Inputs.push_back(I);

4470

if (LF.PostIncLoops.count(L)) {

4471

if (LF.isUseFullyOutsideLoop(L))

4472

Inputs.push_back(L->getLoopLatch()->getTerminator());

4473

else

4474

Inputs.push_back(IVIncInsertPos);

4475

}

4476

// The expansion must also be dominated by the increment positions of any

4477

// loops it for which it is using post-inc mode.

4478

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

4479

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

4480

const Loop *PIL = *I;

4481

if (PIL == L) continue;

4482

4483

// Be dominated by the loop exit.

4484

SmallVector<BasicBlock *, 4> ExitingBlocks;

4485

PIL->getExitingBlocks(ExitingBlocks);

4486

if (!ExitingBlocks.empty()) {

4487

BasicBlock *BB = ExitingBlocks[0];

4488

for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i)

4489

BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]);

4490

Inputs.push_back(BB->getTerminator());

4491

}

4492

}

4493

4494

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4496, __PRETTY_FUNCTION__))

4495

&& !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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4496, __PRETTY_FUNCTION__))

4496

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4496, __PRETTY_FUNCTION__));

4497

4498

// Then, climb up the immediate dominator tree as far as we can go while

4499

// still being dominated by the input positions.

4500

BasicBlock::iterator IP = HoistInsertPosition(LowestIP, Inputs);

4501

4502

// Don't insert instructions before PHI nodes.

4503

while (isa<PHINode>(IP)) ++IP;

4504

4505

// Ignore landingpad instructions.

4506

while (isa<LandingPadInst>(IP)) ++IP;

4507

4508

// Ignore debug intrinsics.

4509

while (isa<DbgInfoIntrinsic>(IP)) ++IP;

4510

4511

// Set IP below instructions recently inserted by SCEVExpander. This keeps the

4512

// IP consistent across expansions and allows the previously inserted

4513

// instructions to be reused by subsequent expansion.

4514

while (Rewriter.isInsertedInstruction(IP) && IP != LowestIP) ++IP;

4515

4516

return IP;

4517

}

4518

4519

/// Expand - Emit instructions for the leading candidate expression for this

4520

/// LSRUse (this is called "expanding").

4521

Value *LSRInstance::Expand(const LSRFixup &LF,

4522

const Formula &F,

4523

BasicBlock::iterator IP,

4524

SCEVExpander &Rewriter,

4525

SmallVectorImpl<WeakVH> &DeadInsts) const {

4526

const LSRUse &LU = Uses[LF.LUIdx];

4527

if (LU.RigidFormula)

4528

return LF.OperandValToReplace;

4529

4530

// Determine an input position which will be dominated by the operands and

4531

// which will dominate the result.

4532

IP = AdjustInsertPositionForExpand(IP, LF, LU, Rewriter);

4533

4534

// Inform the Rewriter if we have a post-increment use, so that it can

4535

// perform an advantageous expansion.

4536

Rewriter.setPostInc(LF.PostIncLoops);

4537

4538

// This is the type that the user actually needs.

4539

Type *OpTy = LF.OperandValToReplace->getType();

4540

// This will be the type that we'll initially expand to.

4541

Type *Ty = F.getType();

4542

if (!Ty)

4543

// No type known; just expand directly to the ultimate type.

4544

Ty = OpTy;

4545

else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy))

4546

// Expand directly to the ultimate type if it's the right size.

4547

Ty = OpTy;

4548

// This is the type to do integer arithmetic in.

4549

Type *IntTy = SE.getEffectiveSCEVType(Ty);

4550

4551

// Build up a list of operands to add together to form the full base.

4552

SmallVector<const SCEV *, 8> Ops;

4553

4554

// Expand the BaseRegs portion.

4555

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

4556

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

4557

const SCEV *Reg = *I;

4558

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4558, __PRETTY_FUNCTION__));

4559

4560

// If we're expanding for a post-inc user, make the post-inc adjustment.

4561

PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);

4562

Reg = TransformForPostIncUse(Denormalize, Reg,

4563

LF.UserInst, LF.OperandValToReplace,

4564

Loops, SE, DT);

4565

4566

Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr, IP)));

4567

}

4568

4569

// Expand the ScaledReg portion.

4570

Value *ICmpScaledV = nullptr;

4571

if (F.Scale != 0) {

4572

const SCEV *ScaledS = F.ScaledReg;

4573

4574

// If we're expanding for a post-inc user, make the post-inc adjustment.

4575

PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);

4576

ScaledS = TransformForPostIncUse(Denormalize, ScaledS,

4577

LF.UserInst, LF.OperandValToReplace,

4578

Loops, SE, DT);

4579

4580

if (LU.Kind == LSRUse::ICmpZero) {

4581

// Expand ScaleReg as if it was part of the base regs.

4582

if (F.Scale == 1)

4583

Ops.push_back(

4584

SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP)));

4585

else {

4586

// An interesting way of "folding" with an icmp is to use a negated

4587

// scale, which we'll implement by inserting it into the other operand

4588

// of the icmp.

4589

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4590, __PRETTY_FUNCTION__))

4590

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4590, __PRETTY_FUNCTION__));

4591

ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr, IP);

4592

}

4593

} else {

4594

// Otherwise just expand the scaled register and an explicit scale,

4595

// which is expected to be matched as part of the address.

4596

4597

// Flush the operand list to suppress SCEVExpander hoisting address modes.

4598

// Unless the addressing mode will not be folded.

4599

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

4600

isAMCompletelyFolded(TTI, LU, F)) {

4601

Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);

4602

Ops.clear();

4603

Ops.push_back(SE.getUnknown(FullV));

4604

}

4605

ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP));

4606

if (F.Scale != 1)

4607

ScaledS =

4608

SE.getMulExpr(ScaledS, SE.getConstant(ScaledS->getType(), F.Scale));

4609

Ops.push_back(ScaledS);

4610

}

4611

}

4612

4613

// Expand the GV portion.

4614

if (F.BaseGV) {

4615

// Flush the operand list to suppress SCEVExpander hoisting.

4616

if (!Ops.empty()) {

4617

Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);

4618

Ops.clear();

4619

Ops.push_back(SE.getUnknown(FullV));

4620

}

4621

Ops.push_back(SE.getUnknown(F.BaseGV));

4622

}

4623

4624

// Flush the operand list to suppress SCEVExpander hoisting of both folded and

4625

// unfolded offsets. LSR assumes they both live next to their uses.

4626

if (!Ops.empty()) {

4627

Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty, IP);

4628

Ops.clear();

4629

Ops.push_back(SE.getUnknown(FullV));

4630

}

4631

4632

// Expand the immediate portion.

4633

int64_t Offset = (uint64_t)F.BaseOffset + LF.Offset;

4634

if (Offset != 0) {

4635

if (LU.Kind == LSRUse::ICmpZero) {

4636

// The other interesting way of "folding" with an ICmpZero is to use a

4637

// negated immediate.

4638

if (!ICmpScaledV)

4639

ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset);

4640

else {

4641

Ops.push_back(SE.getUnknown(ICmpScaledV));

4642

ICmpScaledV = ConstantInt::get(IntTy, Offset);

4643

}

4644

} else {

4645

// Just add the immediate values. These again are expected to be matched

4646

// as part of the address.

4647

Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, Offset)));

4648

}

4649

}

4650

4651

// Expand the unfolded offset portion.

4652

int64_t UnfoldedOffset = F.UnfoldedOffset;

4653

if (UnfoldedOffset != 0) {

4654

// Just add the immediate values.

4655

Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy,

4656

UnfoldedOffset)));

4657

}

4658

4659

// Emit instructions summing all the operands.

4660

const SCEV *FullS = Ops.empty() ?

4661

SE.getConstant(IntTy, 0) :

4662

SE.getAddExpr(Ops);

4663

Value *FullV = Rewriter.expandCodeFor(FullS, Ty, IP);

4664

4665

// We're done expanding now, so reset the rewriter.

4666

Rewriter.clearPostInc();

4667

4668

// An ICmpZero Formula represents an ICmp which we're handling as a

4669

// comparison against zero. Now that we've expanded an expression for that

4670

// form, update the ICmp's other operand.

4671

if (LU.Kind == LSRUse::ICmpZero) {

4672

ICmpInst *CI = cast<ICmpInst>(LF.UserInst);

4673

DeadInsts.push_back(CI->getOperand(1));

4674

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4675, __PRETTY_FUNCTION__))

4675

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4675, __PRETTY_FUNCTION__));

4676

if (F.Scale == -1) {

4677

if (ICmpScaledV->getType() != OpTy) {

4678

Instruction *Cast =

4679

CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false,

4680

OpTy, false),

4681

ICmpScaledV, OpTy, "tmp", CI);

4682

ICmpScaledV = Cast;

4683

}

4684

CI->setOperand(1, ICmpScaledV);

4685

} else {

4686

// A scale of 1 means that the scale has been expanded as part of the

4687

// base regs.

4688

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4690, __PRETTY_FUNCTION__))

4689

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4690, __PRETTY_FUNCTION__))

4690

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4690, __PRETTY_FUNCTION__));

4691

Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy),

4692

-(uint64_t)Offset);

4693

if (C->getType() != OpTy)

4694

C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,

4695

OpTy, false),

4696

C, OpTy);

4697

4698

CI->setOperand(1, C);

4699

}

4700

}

4701

4702

return FullV;

4703

}

4704

4705

/// RewriteForPHI - Helper for Rewrite. PHI nodes are special because the use

4706

/// of their operands effectively happens in their predecessor blocks, so the

4707

/// expression may need to be expanded in multiple places.

4708

void LSRInstance::RewriteForPHI(PHINode *PN,

4709

const LSRFixup &LF,

4710

const Formula &F,

4711

SCEVExpander &Rewriter,

4712

SmallVectorImpl<WeakVH> &DeadInsts,

4713

Pass *P) const {

4714

DenseMap<BasicBlock *, Value *> Inserted;

4715

for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)

Assuming 'i' is not equal to 'e'

→

←

Loop condition is true. Entering loop body

→

←

Assuming 'i' is not equal to 'e'

→

←

Loop condition is true. Entering loop body

→

←

Assuming 'i' is not equal to 'e'

→

←

Loop condition is true. Entering loop body

→

←

Assuming 'i' is not equal to 'e'

→

←

Loop condition is true. Entering loop body

→

4716

if (PN->getIncomingValue(i) == LF.OperandValToReplace) {

Taking false branch

Taking false branch

Taking false branch

Assuming pointer value is null

→

←

Taking true branch

→

4717

BasicBlock *BB = PN->getIncomingBlock(i);

4718

4719

// If this is a critical edge, split the edge so that we do not insert

4720

// the code on all predecessor/successor paths. We do this unless this

4721

// is the canonical backedge for this loop, which complicates post-inc

4722

// users.

4723

if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&

4724

!isa<IndirectBrInst>(BB->getTerminator())) {

4725

BasicBlock *Parent = PN->getParent();

4726

Loop *PNLoop = LI.getLoopFor(Parent);

4727

if (!PNLoop || Parent != PNLoop->getHeader()) {

4728

// Split the critical edge.

4729

BasicBlock *NewBB = nullptr;

4730

if (!Parent->isLandingPad()) {

4731

NewBB = SplitCriticalEdge(BB, Parent, P,

4732

/*MergeIdenticalEdges=*/true,

4733

/*DontDeleteUselessPhis=*/true);

4734

} else {

4735

SmallVector<BasicBlock*, 2> NewBBs;

4736

SplitLandingPadPredecessors(Parent, BB, "", "", P, NewBBs);

4737

NewBB = NewBBs[0];

4738

}

4739

// If NewBB==NULL, then SplitCriticalEdge refused to split because all

4740

// phi predecessors are identical. The simple thing to do is skip

4741

// splitting in this case rather than complicate the API.

4742

if (NewBB) {

4743

// If PN is outside of the loop and BB is in the loop, we want to

4744

// move the block to be immediately before the PHI block, not

4745

// immediately after BB.

4746

if (L->contains(BB) && !L->contains(PN))

4747

NewBB->moveBefore(PN->getParent());

4748

4749

// Splitting the edge can reduce the number of PHI entries we have.

4750

e = PN->getNumIncomingValues();

4751

BB = NewBB;

4752

i = PN->getBasicBlockIndex(BB);

4753

}

4754

}

4755

}

4756

4757

std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =

4758

Inserted.insert(std::make_pair(BB, static_cast<Value *>(nullptr)));

4759

if (!Pair.second)

←

Taking false branch

→

4760

PN->setIncomingValue(i, Pair.first->second);

4761

else {

4762

Value *FullV = Expand(LF, F, BB->getTerminator(), Rewriter, DeadInsts);

4763

4764

// If this is reuse-by-noop-cast, insert the noop cast.

4765

Type *OpTy = LF.OperandValToReplace->getType();

←

Called C++ object pointer is null

4766

if (FullV->getType() != OpTy)

4767

FullV =

4768

CastInst::Create(CastInst::getCastOpcode(FullV, false,

4769

OpTy, false),

4770

FullV, LF.OperandValToReplace->getType(),

4771

"tmp", BB->getTerminator());

4772

4773

PN->setIncomingValue(i, FullV);

4774

Pair.first->second = FullV;

4775

}

4776

}

4777

}

4778

4779

/// Rewrite - Emit instructions for the leading candidate expression for this

4780

/// LSRUse (this is called "expanding"), and update the UserInst to reference

4781

/// the newly expanded value.

4782

void LSRInstance::Rewrite(const LSRFixup &LF,

4783

const Formula &F,

4784

SCEVExpander &Rewriter,

4785

SmallVectorImpl<WeakVH> &DeadInsts,

4786

Pass *P) const {

4787

// First, find an insertion point that dominates UserInst. For PHI nodes,

4788

// find the nearest block which dominates all the relevant uses.

4789

if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) {

4790

RewriteForPHI(PN, LF, F, Rewriter, DeadInsts, P);

4791

} else {

4792

Value *FullV = Expand(LF, F, LF.UserInst, Rewriter, DeadInsts);

4793

4794

// If this is reuse-by-noop-cast, insert the noop cast.

4795

Type *OpTy = LF.OperandValToReplace->getType();

4796

if (FullV->getType() != OpTy) {

4797

Instruction *Cast =

4798

CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false),

4799

FullV, OpTy, "tmp", LF.UserInst);

4800

FullV = Cast;

4801

}

4802

4803

// Update the user. ICmpZero is handled specially here (for now) because

4804

// Expand may have updated one of the operands of the icmp already, and

4805

// its new value may happen to be equal to LF.OperandValToReplace, in

4806

// which case doing replaceUsesOfWith leads to replacing both operands

4807

// with the same value. TODO: Reorganize this.

4808

if (Uses[LF.LUIdx].Kind == LSRUse::ICmpZero)

4809

LF.UserInst->setOperand(0, FullV);

4810

else

4811

LF.UserInst->replaceUsesOfWith(LF.OperandValToReplace, FullV);

4812

}

4813

4814

DeadInsts.push_back(LF.OperandValToReplace);

4815

}

4816

4817

/// ImplementSolution - Rewrite all the fixup locations with new values,

4818

/// following the chosen solution.

4819

void

4820

LSRInstance::ImplementSolution(const SmallVectorImpl<const Formula *> &Solution,

4821

Pass *P) {

4822

// Keep track of instructions we may have made dead, so that

4823

// we can remove them after we are done working.

4824

SmallVector<WeakVH, 16> DeadInsts;

4825

4826

SCEVExpander Rewriter(SE, "lsr");

4827

#ifndef NDEBUG

4828

Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");

4829

#endif

4830

Rewriter.disableCanonicalMode();

4831

Rewriter.enableLSRMode();

4832

Rewriter.setIVIncInsertPos(L, IVIncInsertPos);

4833

4834

// Mark phi nodes that terminate chains so the expander tries to reuse them.

4835

for (SmallVectorImpl<IVChain>::const_iterator ChainI = IVChainVec.begin(),

4836

ChainE = IVChainVec.end(); ChainI != ChainE; ++ChainI) {

4837

if (PHINode *PN = dyn_cast<PHINode>(ChainI->tailUserInst()))

4838

Rewriter.setChainedPhi(PN);

4839

}

4840

4841

// Expand the new value definitions and update the users.

4842

for (SmallVectorImpl<LSRFixup>::const_iterator I = Fixups.begin(),

4843

E = Fixups.end(); I != E; ++I) {

4844

const LSRFixup &Fixup = *I;

4845

4846

Rewrite(Fixup, *Solution[Fixup.LUIdx], Rewriter, DeadInsts, P);

4847

4848

Changed = true;

4849

}

4850

4851

for (SmallVectorImpl<IVChain>::const_iterator ChainI = IVChainVec.begin(),

4852

ChainE = IVChainVec.end(); ChainI != ChainE; ++ChainI) {

4853

GenerateIVChain(*ChainI, Rewriter, DeadInsts);

4854

Changed = true;

4855

}

4856

// Clean up after ourselves. This must be done before deleting any

4857

// instructions.

4858

Rewriter.clear();

4859

4860

Changed |= DeleteTriviallyDeadInstructions(DeadInsts);

4861

}

4862

4863

LSRInstance::LSRInstance(Loop *L, Pass *P)

4864

: IU(P->getAnalysis<IVUsers>()), SE(P->getAnalysis<ScalarEvolution>()),

4865

DT(P->getAnalysis<DominatorTreeWrapperPass>().getDomTree()),

4866

LI(P->getAnalysis<LoopInfoWrapperPass>().getLoopInfo()),

4867

TTI(P->getAnalysis<TargetTransformInfo>()), L(L), Changed(false),

4868

IVIncInsertPos(nullptr) {

4869

// If LoopSimplify form is not available, stay out of trouble.

4870

if (!L->isLoopSimplifyForm())

4871

return;

4872

4873

// If there's no interesting work to be done, bail early.

4874

if (IU.empty()) return;

4875

4876

// If there's too much analysis to be done, bail early. We won't be able to

4877

// model the problem anyway.

4878

unsigned NumUsers = 0;

4879

for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) {

4880

if (++NumUsers > MaxIVUsers) {

4881

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)

4882

<< "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in "
<< *L << "\n"; } } while (0);

4883

return;

4884

}

4885

}

4886

4887

#ifndef NDEBUG

4888

// All dominating loops must have preheaders, or SCEVExpander may not be able

4889

// to materialize an AddRecExpr whose Start is an outer AddRecExpr.

4890

4891

// IVUsers analysis should only create users that are dominated by simple loop

4892

// headers. Since this loop should dominate all of its users, its user list

4893

// should be empty if this loop itself is not within a simple loop nest.

4894

for (DomTreeNode *Rung = DT.getNode(L->getLoopPreheader());

4895

Rung; Rung = Rung->getIDom()) {

4896

BasicBlock *BB = Rung->getBlock();

4897

const Loop *DomLoop = LI.getLoopFor(BB);

4898

if (DomLoop && DomLoop->getHeader() == BB) {

4899

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4899, __PRETTY_FUNCTION__));

4900

}

4901

}

4902

#endif // DEBUG

4903

4904

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)

4905

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)

4906

dbgs() << ":\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (0);

4907

4908

// First, perform some low-level loop optimizations.

4909

OptimizeShadowIV();

4910

OptimizeLoopTermCond();

4911

4912

// If loop preparation eliminates all interesting IV users, bail.

4913

if (IU.empty()) return;

4914

4915

// Skip nested loops until we can model them better with formulae.

4916

if (!L->empty()) {

4917

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);

4918

return;

4919

}

4920

4921

// Start collecting data and preparing for the solver.

4922

CollectChains();

4923

CollectInterestingTypesAndFactors();

4924

CollectFixupsAndInitialFormulae();

4925

CollectLoopInvariantFixupsAndFormulae();

4926

4927

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4927, __PRETTY_FUNCTION__));

4928

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
)

4929

print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR found " << Uses
.size() << " uses:\n"; print_uses(dbgs()); } } while (0
);

4930

4931

// Now use the reuse data to generate a bunch of interesting ways

4932

// to formulate the values needed for the uses.

4933

GenerateAllReuseFormulae();

4934

4935

FilterOutUndesirableDedicatedRegisters();

4936

NarrowSearchSpaceUsingHeuristics();

4937

4938

SmallVector<const Formula *, 8> Solution;

4939

Solve(Solution);

4940

4941

// Release memory that is no longer needed.

4942

Factors.clear();

4943

Types.clear();

4944

RegUses.clear();

4945

4946

if (Solution.empty())

4947

return;

4948

4949

#ifndef NDEBUG

4950

// Formulae should be legal.

4951

for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(), E = Uses.end();

4952

I != E; ++I) {

4953

const LSRUse &LU = *I;

4954

for (SmallVectorImpl<Formula>::const_iterator J = LU.Formulae.begin(),

4955

JE = LU.Formulae.end();

4956

J != JE; ++J)

4957

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4958, __PRETTY_FUNCTION__))

4958

*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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4958, __PRETTY_FUNCTION__));

4959

};

4960

#endif

4961

4962

// Now that we've decided what we want, make it so.

4963

ImplementSolution(Solution, P);

4964

}

4965

4966

void LSRInstance::print_factors_and_types(raw_ostream &OS) const {

4967

if (Factors.empty() && Types.empty()) return;

4968

4969

OS << "LSR has identified the following interesting factors and types: ";

4970

bool First = true;

4971

4972

for (SmallSetVector<int64_t, 8>::const_iterator

4973

I = Factors.begin(), E = Factors.end(); I != E; ++I) {

4974

if (!First) OS << ", ";

4975

First = false;

4976

OS << '*' << *I;

4977

}

4978

4979

for (SmallSetVector<Type *, 4>::const_iterator

4980

I = Types.begin(), E = Types.end(); I != E; ++I) {

4981

if (!First) OS << ", ";

4982

First = false;

4983

OS << '(' << **I << ')';

4984

}

4985

OS << '\n';

4986

}

4987

4988

void LSRInstance::print_fixups(raw_ostream &OS) const {

4989

OS << "LSR is examining the following fixup sites:\n";

4990

for (SmallVectorImpl<LSRFixup>::const_iterator I = Fixups.begin(),

4991

E = Fixups.end(); I != E; ++I) {

4992

dbgs() << " ";

4993

I->print(OS);

4994

OS << '\n';

4995

}

4996

}

4997

4998

void LSRInstance::print_uses(raw_ostream &OS) const {

4999

OS << "LSR is examining the following uses:\n";

5000

for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(),

5001

E = Uses.end(); I != E; ++I) {

5002

const LSRUse &LU = *I;

5003

dbgs() << " ";

5004

LU.print(OS);

5005

OS << '\n';

5006

for (SmallVectorImpl<Formula>::const_iterator J = LU.Formulae.begin(),

5007

JE = LU.Formulae.end(); J != JE; ++J) {

5008

OS << " ";

5009

J->print(OS);

5010

OS << '\n';

5011

}

5012

}

5013

}

5014

5015

void LSRInstance::print(raw_ostream &OS) const {

5016

print_factors_and_types(OS);

5017

print_fixups(OS);

5018

print_uses(OS);

5019

}

5020

5021

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

5022

void LSRInstance::dump() const {

5023

print(errs()); errs() << '\n';

5024

}

5025

#endif

5026

5027

namespace {

5028

5029

class LoopStrengthReduce : public LoopPass {

5030

public:

5031

static char ID; // Pass ID, replacement for typeid

5032

LoopStrengthReduce();

5033

5034

private:

5035

bool runOnLoop(Loop *L, LPPassManager &LPM) override;

5036

void getAnalysisUsage(AnalysisUsage &AU) const override;

5037

};

5038

5039

}

5040

5041

char LoopStrengthReduce::ID = 0;

5042

INITIALIZE_PASS_BEGIN(LoopStrengthReduce, "loop-reduce",static void* initializeLoopStrengthReducePassOnce(PassRegistry
&Registry) {

5043

"Loop Strength Reduction", false, false)static void* initializeLoopStrengthReducePassOnce(PassRegistry
&Registry) {

5044

INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)initializeTargetTransformInfoAnalysisGroup(Registry);

5045

INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)initializeDominatorTreeWrapperPassPass(Registry);

5046

INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)initializeScalarEvolutionPass(Registry);

5047

INITIALIZE_PASS_DEPENDENCY(IVUsers)initializeIVUsersPass(Registry);

5048

INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)initializeLoopInfoWrapperPassPass(Registry);

5049

INITIALIZE_PASS_DEPENDENCY(LoopSimplify)initializeLoopSimplifyPass(Registry);

5050

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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5051); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5051, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5051); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5051, &initialized); }

5051

"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~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5051); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5051, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5051); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn226397/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5051, &initialized); }

5052

5053

5054

Pass *llvm::createLoopStrengthReducePass() {

5055

return new LoopStrengthReduce();

5056

}

5057

5058

LoopStrengthReduce::LoopStrengthReduce() : LoopPass(ID) {

5059

initializeLoopStrengthReducePass(*PassRegistry::getPassRegistry());

5060

}

5061

5062

void LoopStrengthReduce::getAnalysisUsage(AnalysisUsage &AU) const {

5063

// We split critical edges, so we change the CFG. However, we do update

5064

// many analyses if they are around.

5065

AU.addPreservedID(LoopSimplifyID);

5066

5067

AU.addRequired<LoopInfoWrapperPass>();

5068

AU.addPreserved<LoopInfoWrapperPass>();

5069

AU.addRequiredID(LoopSimplifyID);

5070

AU.addRequired<DominatorTreeWrapperPass>();

5071

AU.addPreserved<DominatorTreeWrapperPass>();

5072

AU.addRequired<ScalarEvolution>();

5073

AU.addPreserved<ScalarEvolution>();

5074

// Requiring LoopSimplify a second time here prevents IVUsers from running

5075

// twice, since LoopSimplify was invalidated by running ScalarEvolution.

5076

AU.addRequiredID(LoopSimplifyID);

5077

AU.addRequired<IVUsers>();

5078

AU.addPreserved<IVUsers>();

5079

AU.addRequired<TargetTransformInfo>();

5080

}

5081

5082

bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager & /*LPM*/) {

5083

if (skipOptnoneFunction(L))

5084

return false;

5085

5086

bool Changed = false;

5087

5088

// Run the main LSR transformation.

5089

Changed |= LSRInstance(L, this).getChanged();

5090

5091

// Remove any extra phis created by processing inner loops.

5092

Changed |= DeleteDeadPHIs(L->getHeader());

5093

if (EnablePhiElim && L->isLoopSimplifyForm()) {

5094

SmallVector<WeakVH, 16> DeadInsts;

5095

SCEVExpander Rewriter(getAnalysis<ScalarEvolution>(), "lsr");

5096

#ifndef NDEBUG

5097

Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");

5098

#endif

5099

unsigned numFolded = Rewriter.replaceCongruentIVs(

5100

L, &getAnalysis<DominatorTreeWrapperPass>().getDomTree(), DeadInsts,

5101

&getAnalysis<TargetTransformInfo>());

5102

if (numFolded) {

5103

Changed = true;

5104

DeleteTriviallyDeadInstructions(DeadInsts);

5105

DeleteDeadPHIs(L->getHeader());

5106

}

5107

}

5108

return Changed;

5109

}