/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp

Bug Summary

File:	lib/CodeGen/CodeGenPrepare.cpp
Warning:	line 1961, column 60 Called C++ object pointer is uninitialized

Annotated Source Code

//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//

// The LLVM Compiler Infrastructure

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

// License. See LICENSE.TXT for details.

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

// This pass munges the code in the input function to better prepare it for

// SelectionDAG-based code generation. This works around limitations in it's

// basic-block-at-a-time approach. It should eventually be removed.

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

#include "llvm/ADT/APInt.h"

#include "llvm/ADT/ArrayRef.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/PointerIntPair.h"

#include "llvm/ADT/STLExtras.h"

#include "llvm/ADT/SetVector.h"

#include "llvm/ADT/SmallPtrSet.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/ADT/Statistic.h"

#include "llvm/Analysis/BlockFrequencyInfo.h"

#include "llvm/Analysis/BranchProbabilityInfo.h"

#include "llvm/Analysis/ConstantFolding.h"

#include "llvm/Analysis/InstructionSimplify.h"

#include "llvm/Analysis/LoopInfo.h"

#include "llvm/Analysis/MemoryBuiltins.h"

#include "llvm/Analysis/ProfileSummaryInfo.h"

#include "llvm/Analysis/TargetLibraryInfo.h"

#include "llvm/Analysis/TargetTransformInfo.h"

#include "llvm/Analysis/ValueTracking.h"

#include "llvm/CodeGen/Analysis.h"

#include "llvm/CodeGen/ISDOpcodes.h"

#include "llvm/CodeGen/MachineValueType.h"

#include "llvm/CodeGen/SelectionDAGNodes.h"

#include "llvm/CodeGen/TargetPassConfig.h"

#include "llvm/CodeGen/ValueTypes.h"

#include "llvm/IR/Argument.h"

#include "llvm/IR/Attributes.h"

#include "llvm/IR/BasicBlock.h"

#include "llvm/IR/CallSite.h"

#include "llvm/IR/Constant.h"

#include "llvm/IR/Constants.h"

#include "llvm/IR/DataLayout.h"

#include "llvm/IR/DerivedTypes.h"

#include "llvm/IR/Dominators.h"

#include "llvm/IR/Function.h"

#include "llvm/IR/GetElementPtrTypeIterator.h"

#include "llvm/IR/GlobalValue.h"

#include "llvm/IR/GlobalVariable.h"

#include "llvm/IR/IRBuilder.h"

#include "llvm/IR/InlineAsm.h"

#include "llvm/IR/InstrTypes.h"

#include "llvm/IR/Instruction.h"

#include "llvm/IR/Instructions.h"

#include "llvm/IR/IntrinsicInst.h"

#include "llvm/IR/Intrinsics.h"

#include "llvm/IR/LLVMContext.h"

#include "llvm/IR/MDBuilder.h"

#include "llvm/IR/Module.h"

#include "llvm/IR/Operator.h"

#include "llvm/IR/PatternMatch.h"

#include "llvm/IR/Statepoint.h"

#include "llvm/IR/Type.h"

#include "llvm/IR/Use.h"

#include "llvm/IR/User.h"

#include "llvm/IR/Value.h"

#include "llvm/IR/ValueHandle.h"

#include "llvm/IR/ValueMap.h"

#include "llvm/Pass.h"

#include "llvm/Support/BlockFrequency.h"

#include "llvm/Support/BranchProbability.h"

#include "llvm/Support/Casting.h"

#include "llvm/Support/CommandLine.h"

#include "llvm/Support/Compiler.h"

#include "llvm/Support/Debug.h"

#include "llvm/Support/ErrorHandling.h"

#include "llvm/Support/MathExtras.h"

#include "llvm/Support/raw_ostream.h"

#include "llvm/Target/TargetLowering.h"

#include "llvm/Target/TargetMachine.h"

#include "llvm/Target/TargetOptions.h"

#include "llvm/Target/TargetSubtargetInfo.h"

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

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

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

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

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

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

#include <algorithm>

#include <cassert>

#include <cstdint>

#include <iterator>

#include <limits>

#include <memory>

#include <utility>

100

#include <vector>

101

102

using namespace llvm;

103

using namespace llvm::PatternMatch;

104

105

#define DEBUG_TYPE"codegenprepare" "codegenprepare"

106

107

STATISTIC(NumBlocksElim, "Number of blocks eliminated")static llvm::Statistic NumBlocksElim = {"codegenprepare", "NumBlocksElim"
, "Number of blocks eliminated", {0}, false};

108

STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated")static llvm::Statistic NumPHIsElim = {"codegenprepare", "NumPHIsElim"
, "Number of trivial PHIs eliminated", {0}, false};

109

STATISTIC(NumGEPsElim, "Number of GEPs converted to casts")static llvm::Statistic NumGEPsElim = {"codegenprepare", "NumGEPsElim"
, "Number of GEPs converted to casts", {0}, false};

110

STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, false}

111

"sunken Cmps")static llvm::Statistic NumCmpUses = {"codegenprepare", "NumCmpUses"
, "Number of uses of Cmp expressions replaced with uses of " "sunken Cmps"
, {0}, false};

112

STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, false}

113

"of sunken Casts")static llvm::Statistic NumCastUses = {"codegenprepare", "NumCastUses"
, "Number of uses of Cast expressions replaced with uses " "of sunken Casts"
, {0}, false};

114

STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, false}

115

"computations were sunk")static llvm::Statistic NumMemoryInsts = {"codegenprepare", "NumMemoryInsts"
, "Number of memory instructions whose address " "computations were sunk"
, {0}, false};

116

STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads")static llvm::Statistic NumExtsMoved = {"codegenprepare", "NumExtsMoved"
, "Number of [s|z]ext instructions combined with loads", {0},
false};

117

STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized")static llvm::Statistic NumExtUses = {"codegenprepare", "NumExtUses"
, "Number of uses of [s|z]ext instructions optimized", {0}, false
};

118

STATISTIC(NumAndsAdded,static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, false}

119

"Number of and mask instructions added to form ext loads")static llvm::Statistic NumAndsAdded = {"codegenprepare", "NumAndsAdded"
, "Number of and mask instructions added to form ext loads", {
0}, false};

120

STATISTIC(NumAndUses, "Number of uses of and mask instructions optimized")static llvm::Statistic NumAndUses = {"codegenprepare", "NumAndUses"
, "Number of uses of and mask instructions optimized", {0}, false
};

121

STATISTIC(NumRetsDup, "Number of return instructions duplicated")static llvm::Statistic NumRetsDup = {"codegenprepare", "NumRetsDup"
, "Number of return instructions duplicated", {0}, false};

122

STATISTIC(NumDbgValueMoved, "Number of debug value instructions moved")static llvm::Statistic NumDbgValueMoved = {"codegenprepare", "NumDbgValueMoved"
, "Number of debug value instructions moved", {0}, false};

123

STATISTIC(NumSelectsExpanded, "Number of selects turned into branches")static llvm::Statistic NumSelectsExpanded = {"codegenprepare"
, "NumSelectsExpanded", "Number of selects turned into branches"
, {0}, false};

124

STATISTIC(NumStoreExtractExposed, "Number of store(extractelement) exposed")static llvm::Statistic NumStoreExtractExposed = {"codegenprepare"
, "NumStoreExtractExposed", "Number of store(extractelement) exposed"
, {0}, false};

125

126

STATISTIC(NumMemCmpCalls, "Number of memcmp calls")static llvm::Statistic NumMemCmpCalls = {"codegenprepare", "NumMemCmpCalls"
, "Number of memcmp calls", {0}, false};

127

STATISTIC(NumMemCmpNotConstant, "Number of memcmp calls without constant size")static llvm::Statistic NumMemCmpNotConstant = {"codegenprepare"
, "NumMemCmpNotConstant", "Number of memcmp calls without constant size"
, {0}, false};

128

STATISTIC(NumMemCmpGreaterThanMax,static llvm::Statistic NumMemCmpGreaterThanMax = {"codegenprepare"
, "NumMemCmpGreaterThanMax", "Number of memcmp calls with size greater than max size"
, {0}, false}

129

"Number of memcmp calls with size greater than max size")static llvm::Statistic NumMemCmpGreaterThanMax = {"codegenprepare"
, "NumMemCmpGreaterThanMax", "Number of memcmp calls with size greater than max size"
, {0}, false};

130

STATISTIC(NumMemCmpInlined, "Number of inlined memcmp calls")static llvm::Statistic NumMemCmpInlined = {"codegenprepare", "NumMemCmpInlined"
, "Number of inlined memcmp calls", {0}, false};

131

132

static cl::opt<bool> DisableBranchOpts(

133

"disable-cgp-branch-opts", cl::Hidden, cl::init(false),

134

cl::desc("Disable branch optimizations in CodeGenPrepare"));

135

136

static cl::opt<bool>

137

DisableGCOpts("disable-cgp-gc-opts", cl::Hidden, cl::init(false),

138

cl::desc("Disable GC optimizations in CodeGenPrepare"));

139

140

static cl::opt<bool> DisableSelectToBranch(

141

"disable-cgp-select2branch", cl::Hidden, cl::init(false),

142

cl::desc("Disable select to branch conversion."));

143

144

static cl::opt<bool> AddrSinkUsingGEPs(

145

"addr-sink-using-gep", cl::Hidden, cl::init(true),

146

cl::desc("Address sinking in CGP using GEPs."));

147

148

static cl::opt<bool> EnableAndCmpSinking(

149

"enable-andcmp-sinking", cl::Hidden, cl::init(true),

150

cl::desc("Enable sinkinig and/cmp into branches."));

151

152

static cl::opt<bool> DisableStoreExtract(

153

"disable-cgp-store-extract", cl::Hidden, cl::init(false),

154

cl::desc("Disable store(extract) optimizations in CodeGenPrepare"));

155

156

static cl::opt<bool> StressStoreExtract(

157

"stress-cgp-store-extract", cl::Hidden, cl::init(false),

158

cl::desc("Stress test store(extract) optimizations in CodeGenPrepare"));

159

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static cl::opt<bool> DisableExtLdPromotion(

161

"disable-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),

162

cl::desc("Disable ext(promotable(ld)) -> promoted(ext(ld)) optimization in "

163

"CodeGenPrepare"));

164

165

static cl::opt<bool> StressExtLdPromotion(

166

"stress-cgp-ext-ld-promotion", cl::Hidden, cl::init(false),

167

cl::desc("Stress test ext(promotable(ld)) -> promoted(ext(ld)) "

168

"optimization in CodeGenPrepare"));

169

170

static cl::opt<bool> DisablePreheaderProtect(

171

"disable-preheader-prot", cl::Hidden, cl::init(false),

172

cl::desc("Disable protection against removing loop preheaders"));

173

174

static cl::opt<bool> ProfileGuidedSectionPrefix(

175

"profile-guided-section-prefix", cl::Hidden, cl::init(true), cl::ZeroOrMore,

176

cl::desc("Use profile info to add section prefix for hot/cold functions"));

177

178

static cl::opt<unsigned> FreqRatioToSkipMerge(

179

"cgp-freq-ratio-to-skip-merge", cl::Hidden, cl::init(2),

180

cl::desc("Skip merging empty blocks if (frequency of empty block) / "

181

"(frequency of destination block) is greater than this ratio"));

182

183

static cl::opt<bool> ForceSplitStore(

184

"force-split-store", cl::Hidden, cl::init(false),

185

cl::desc("Force store splitting no matter what the target query says."));

186

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static cl::opt<bool>

188

EnableTypePromotionMerge("cgp-type-promotion-merge", cl::Hidden,

189

cl::desc("Enable merging of redundant sexts when one is dominating"

190

" the other."), cl::init(true));

191

192

static cl::opt<unsigned> MemCmpNumLoadsPerBlock(

193

"memcmp-num-loads-per-block", cl::Hidden, cl::init(1),

194

cl::desc("The number of loads per basic block for inline expansion of "

195

"memcmp that is only being compared against zero."));

196

197

namespace {

198

199

using SetOfInstrs = SmallPtrSet<Instruction *, 16>;

200

using TypeIsSExt = PointerIntPair<Type *, 1, bool>;

201

using InstrToOrigTy = DenseMap<Instruction *, TypeIsSExt>;

202

using SExts = SmallVector<Instruction *, 16>;

203

using ValueToSExts = DenseMap<Value *, SExts>;

204

205

class TypePromotionTransaction;

206

207

class CodeGenPrepare : public FunctionPass {

208

const TargetMachine *TM = nullptr;

209

const TargetSubtargetInfo *SubtargetInfo;

210

const TargetLowering *TLI = nullptr;

211

const TargetRegisterInfo *TRI;

212

const TargetTransformInfo *TTI = nullptr;

213

const TargetLibraryInfo *TLInfo;

214

const LoopInfo *LI;

215

std::unique_ptr<BlockFrequencyInfo> BFI;

216

std::unique_ptr<BranchProbabilityInfo> BPI;

217

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/// As we scan instructions optimizing them, this is the next instruction

219

/// to optimize. Transforms that can invalidate this should update it.

220

BasicBlock::iterator CurInstIterator;

221

222

/// Keeps track of non-local addresses that have been sunk into a block.

223

/// This allows us to avoid inserting duplicate code for blocks with

224

/// multiple load/stores of the same address.

225

ValueMap<Value*, Value*> SunkAddrs;

226

227

/// Keeps track of all instructions inserted for the current function.

228

SetOfInstrs InsertedInsts;

229

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/// Keeps track of the type of the related instruction before their

231

/// promotion for the current function.

232

InstrToOrigTy PromotedInsts;

233

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/// Keep track of instructions removed during promotion.

235

SetOfInstrs RemovedInsts;

236

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/// Keep track of sext chains based on their initial value.

238

DenseMap<Value *, Instruction *> SeenChainsForSExt;

239

240

/// Keep track of SExt promoted.

241

ValueToSExts ValToSExtendedUses;

242

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/// True if CFG is modified in any way.

244

bool ModifiedDT;

245

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/// True if optimizing for size.

247

bool OptSize;

248

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/// DataLayout for the Function being processed.

250

const DataLayout *DL = nullptr;

251

252

public:

253

static char ID; // Pass identification, replacement for typeid

254

255

CodeGenPrepare() : FunctionPass(ID) {

256

initializeCodeGenPreparePass(*PassRegistry::getPassRegistry());

257

}

258

259

bool runOnFunction(Function &F) override;

260

261

StringRef getPassName() const override { return "CodeGen Prepare"; }

262

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void getAnalysisUsage(AnalysisUsage &AU) const override {

264

// FIXME: When we can selectively preserve passes, preserve the domtree.

265

AU.addRequired<ProfileSummaryInfoWrapperPass>();

266

AU.addRequired<TargetLibraryInfoWrapperPass>();

267

AU.addRequired<TargetTransformInfoWrapperPass>();

268

AU.addRequired<LoopInfoWrapperPass>();

269

}

270

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private:

272

bool eliminateFallThrough(Function &F);

273

bool eliminateMostlyEmptyBlocks(Function &F);

274

BasicBlock *findDestBlockOfMergeableEmptyBlock(BasicBlock *BB);

275

bool canMergeBlocks(const BasicBlock *BB, const BasicBlock *DestBB) const;

276

void eliminateMostlyEmptyBlock(BasicBlock *BB);

277

bool isMergingEmptyBlockProfitable(BasicBlock *BB, BasicBlock *DestBB,

278

bool isPreheader);

279

bool optimizeBlock(BasicBlock &BB, bool &ModifiedDT);

280

bool optimizeInst(Instruction *I, bool &ModifiedDT);

281

bool optimizeMemoryInst(Instruction *I, Value *Addr,

282

Type *AccessTy, unsigned AS);

283

bool optimizeInlineAsmInst(CallInst *CS);

284

bool optimizeCallInst(CallInst *CI, bool &ModifiedDT);

285

bool optimizeExt(Instruction *&I);

286

bool optimizeExtUses(Instruction *I);

287

bool optimizeLoadExt(LoadInst *I);

288

bool optimizeSelectInst(SelectInst *SI);

289

bool optimizeShuffleVectorInst(ShuffleVectorInst *SI);

290

bool optimizeSwitchInst(SwitchInst *CI);

291

bool optimizeExtractElementInst(Instruction *Inst);

292

bool dupRetToEnableTailCallOpts(BasicBlock *BB);

293

bool placeDbgValues(Function &F);

294

bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,

295

LoadInst *&LI, Instruction *&Inst, bool HasPromoted);

296

bool tryToPromoteExts(TypePromotionTransaction &TPT,

297

const SmallVectorImpl<Instruction *> &Exts,

298

SmallVectorImpl<Instruction *> &ProfitablyMovedExts,

299

unsigned CreatedInstsCost = 0);

300

bool mergeSExts(Function &F);

301

bool performAddressTypePromotion(

302

Instruction *&Inst,

303

bool AllowPromotionWithoutCommonHeader,

304

bool HasPromoted, TypePromotionTransaction &TPT,

305

SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);

306

bool splitBranchCondition(Function &F);

307

bool simplifyOffsetableRelocate(Instruction &I);

308

bool splitIndirectCriticalEdges(Function &F);

309

};

310

311

} // end anonymous namespace

312

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char CodeGenPrepare::ID = 0;

314

315

INITIALIZE_PASS_BEGIN(CodeGenPrepare, DEBUG_TYPE,static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {

316

"Optimize for code generation", false, false)static void *initializeCodeGenPreparePassOnce(PassRegistry &
Registry) {

317

INITIALIZE_PASS_DEPENDENCY(ProfileSummaryInfoWrapperPass)initializeProfileSummaryInfoWrapperPassPass(Registry);

318

INITIALIZE_PASS_END(CodeGenPrepare, DEBUG_TYPE,PassInfo *PI = new PassInfo( "Optimize for code generation", "codegenprepare"
, &CodeGenPrepare::ID, PassInfo::NormalCtor_t(callDefaultCtor
<CodeGenPrepare>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeCodeGenPreparePassFlag
; void llvm::initializeCodeGenPreparePass(PassRegistry &Registry
) { llvm::call_once(InitializeCodeGenPreparePassFlag, initializeCodeGenPreparePassOnce
, std::ref(Registry)); }

319

"Optimize for code generation", false, false)PassInfo *PI = new PassInfo( "Optimize for code generation", "codegenprepare"
, &CodeGenPrepare::ID, PassInfo::NormalCtor_t(callDefaultCtor
<CodeGenPrepare>), false, false); Registry.registerPass
(*PI, true); return PI; } static llvm::once_flag InitializeCodeGenPreparePassFlag
; void llvm::initializeCodeGenPreparePass(PassRegistry &Registry
) { llvm::call_once(InitializeCodeGenPreparePassFlag, initializeCodeGenPreparePassOnce
, std::ref(Registry)); }

320

321

FunctionPass *llvm::createCodeGenPreparePass() { return new CodeGenPrepare(); }

322

323

bool CodeGenPrepare::runOnFunction(Function &F) {

324

if (skipFunction(F))

325

return false;

326

327

DL = &F.getParent()->getDataLayout();

328

329

bool EverMadeChange = false;

330

// Clear per function information.

331

InsertedInsts.clear();

332

PromotedInsts.clear();

333

BFI.reset();

334

BPI.reset();

335

336

ModifiedDT = false;

337

if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) {

338

TM = &TPC->getTM<TargetMachine>();

339

SubtargetInfo = TM->getSubtargetImpl(F);

340

TLI = SubtargetInfo->getTargetLowering();

341

TRI = SubtargetInfo->getRegisterInfo();

342

}

343

TLInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();

344

TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);

345

LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();

346

OptSize = F.optForSize();

347

348

if (ProfileGuidedSectionPrefix) {

349

ProfileSummaryInfo *PSI =

350

getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();

351

if (PSI->isFunctionHotInCallGraph(&F))

352

F.setSectionPrefix(".hot");

353

else if (PSI->isFunctionColdInCallGraph(&F))

354

F.setSectionPrefix(".unlikely");

355

}

356

357

/// This optimization identifies DIV instructions that can be

358

/// profitably bypassed and carried out with a shorter, faster divide.

359

if (!OptSize && TLI && TLI->isSlowDivBypassed()) {

360

const DenseMap<unsigned int, unsigned int> &BypassWidths =

361

TLI->getBypassSlowDivWidths();

362

BasicBlock* BB = &*F.begin();

363

while (BB != nullptr) {

364

// bypassSlowDivision may create new BBs, but we don't want to reapply the

365

// optimization to those blocks.

366

BasicBlock* Next = BB->getNextNode();

367

EverMadeChange |= bypassSlowDivision(BB, BypassWidths);

368

BB = Next;

369

}

370

}

371

372

// Eliminate blocks that contain only PHI nodes and an

373

// unconditional branch.

374

EverMadeChange |= eliminateMostlyEmptyBlocks(F);

375

376

// llvm.dbg.value is far away from the value then iSel may not be able

377

// handle it properly. iSel will drop llvm.dbg.value if it can not

378

// find a node corresponding to the value.

379

EverMadeChange |= placeDbgValues(F);

380

381

if (!DisableBranchOpts)

382

EverMadeChange |= splitBranchCondition(F);

383

384

// Split some critical edges where one of the sources is an indirect branch,

385

// to help generate sane code for PHIs involving such edges.

386

EverMadeChange |= splitIndirectCriticalEdges(F);

387

388

bool MadeChange = true;

389

while (MadeChange) {

390

MadeChange = false;

391

SeenChainsForSExt.clear();

392

ValToSExtendedUses.clear();

393

RemovedInsts.clear();

394

for (Function::iterator I = F.begin(); I != F.end(); ) {

395

BasicBlock *BB = &*I++;

396

bool ModifiedDTOnIteration = false;

397

MadeChange |= optimizeBlock(*BB, ModifiedDTOnIteration);

398

399

// Restart BB iteration if the dominator tree of the Function was changed

400

if (ModifiedDTOnIteration)

401

break;

402

}

403

if (EnableTypePromotionMerge && !ValToSExtendedUses.empty())

404

MadeChange |= mergeSExts(F);

405

406

// Really free removed instructions during promotion.

407

for (Instruction *I : RemovedInsts)

408

I->deleteValue();

409

410

EverMadeChange |= MadeChange;

411

}

412

413

SunkAddrs.clear();

414

415

if (!DisableBranchOpts) {

416

MadeChange = false;

417

SmallPtrSet<BasicBlock*, 8> WorkList;

418

for (BasicBlock &BB : F) {

419

SmallVector<BasicBlock *, 2> Successors(succ_begin(&BB), succ_end(&BB));

420

MadeChange |= ConstantFoldTerminator(&BB, true);

421

if (!MadeChange) continue;

422

423

for (SmallVectorImpl<BasicBlock*>::iterator

424

II = Successors.begin(), IE = Successors.end(); II != IE; ++II)

425

if (pred_begin(*II) == pred_end(*II))

426

WorkList.insert(*II);

427

}

428

429

// Delete the dead blocks and any of their dead successors.

430

MadeChange |= !WorkList.empty();

431

while (!WorkList.empty()) {

432

BasicBlock *BB = *WorkList.begin();

433

WorkList.erase(BB);

434

SmallVector<BasicBlock*, 2> Successors(succ_begin(BB), succ_end(BB));

435

436

DeleteDeadBlock(BB);

437

438

for (SmallVectorImpl<BasicBlock*>::iterator

439

II = Successors.begin(), IE = Successors.end(); II != IE; ++II)

440

if (pred_begin(*II) == pred_end(*II))

441

WorkList.insert(*II);

442

}

443

444

// Merge pairs of basic blocks with unconditional branches, connected by

445

// a single edge.

446

if (EverMadeChange || MadeChange)

447

MadeChange |= eliminateFallThrough(F);

448

449

EverMadeChange |= MadeChange;

450

}

451

452

if (!DisableGCOpts) {

453

SmallVector<Instruction *, 2> Statepoints;

454

for (BasicBlock &BB : F)

455

for (Instruction &I : BB)

456

if (isStatepoint(I))

457

Statepoints.push_back(&I);

458

for (auto &I : Statepoints)

459

EverMadeChange |= simplifyOffsetableRelocate(*I);

460

}

461

462

return EverMadeChange;

463

}

464

465

/// Merge basic blocks which are connected by a single edge, where one of the

466

/// basic blocks has a single successor pointing to the other basic block,

467

/// which has a single predecessor.

468

bool CodeGenPrepare::eliminateFallThrough(Function &F) {

469

bool Changed = false;

470

// Scan all of the blocks in the function, except for the entry block.

471

for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {

472

BasicBlock *BB = &*I++;

473

// If the destination block has a single pred, then this is a trivial

474

// edge, just collapse it.

475

BasicBlock *SinglePred = BB->getSinglePredecessor();

476

477

// Don't merge if BB's address is taken.

478

if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;

479

480

BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());

481

if (Term && !Term->isConditional()) {

482

Changed = true;

483

DEBUG(dbgs() << "To merge:\n"<< *SinglePred << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "To merge:\n"<< *
SinglePred << "\n\n\n"; } } while (false);

484

// Remember if SinglePred was the entry block of the function.

485

// If so, we will need to move BB back to the entry position.

486

bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();

487

MergeBasicBlockIntoOnlyPred(BB, nullptr);

488

489

if (isEntry && BB != &BB->getParent()->getEntryBlock())

490

BB->moveBefore(&BB->getParent()->getEntryBlock());

491

492

// We have erased a block. Update the iterator.

493

I = BB->getIterator();

494

}

495

}

496

return Changed;

497

}

498

499

/// Find a destination block from BB if BB is mergeable empty block.

500

BasicBlock *CodeGenPrepare::findDestBlockOfMergeableEmptyBlock(BasicBlock *BB) {

501

// If this block doesn't end with an uncond branch, ignore it.

502

BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());

503

if (!BI || !BI->isUnconditional())

504

return nullptr;

505

506

// If the instruction before the branch (skipping debug info) isn't a phi

507

// node, then other stuff is happening here.

508

BasicBlock::iterator BBI = BI->getIterator();

509

if (BBI != BB->begin()) {

510

--BBI;

511

while (isa<DbgInfoIntrinsic>(BBI)) {

512

if (BBI == BB->begin())

513

break;

514

--BBI;

515

}

516

if (!isa<DbgInfoIntrinsic>(BBI) && !isa<PHINode>(BBI))

517

return nullptr;

518

}

519

520

// Do not break infinite loops.

521

BasicBlock *DestBB = BI->getSuccessor(0);

522

if (DestBB == BB)

523

return nullptr;

524

525

if (!canMergeBlocks(BB, DestBB))

526

DestBB = nullptr;

527

528

return DestBB;

529

}

530

531

// Return the unique indirectbr predecessor of a block. This may return null

532

// even if such a predecessor exists, if it's not useful for splitting.

533

// If a predecessor is found, OtherPreds will contain all other (non-indirectbr)

534

// predecessors of BB.

535

static BasicBlock *

536

findIBRPredecessor(BasicBlock *BB, SmallVectorImpl<BasicBlock *> &OtherPreds) {

537

// If the block doesn't have any PHIs, we don't care about it, since there's

538

// no point in splitting it.

539

PHINode *PN = dyn_cast<PHINode>(BB->begin());

540

if (!PN)

541

return nullptr;

542

543

// Verify we have exactly one IBR predecessor.

544

// Conservatively bail out if one of the other predecessors is not a "regular"

545

// terminator (that is, not a switch or a br).

546

BasicBlock *IBB = nullptr;

547

for (unsigned Pred = 0, E = PN->getNumIncomingValues(); Pred != E; ++Pred) {

548

BasicBlock *PredBB = PN->getIncomingBlock(Pred);

549

TerminatorInst *PredTerm = PredBB->getTerminator();

550

switch (PredTerm->getOpcode()) {

551

case Instruction::IndirectBr:

552

if (IBB)

553

return nullptr;

554

IBB = PredBB;

555

break;

556

case Instruction::Br:

557

case Instruction::Switch:

558

OtherPreds.push_back(PredBB);

559

continue;

560

default:

561

return nullptr;

562

}

563

}

564

565

return IBB;

566

}

567

568

// Split critical edges where the source of the edge is an indirectbr

569

// instruction. This isn't always possible, but we can handle some easy cases.

570

// This is useful because MI is unable to split such critical edges,

571

// which means it will not be able to sink instructions along those edges.

572

// This is especially painful for indirect branches with many successors, where

573

// we end up having to prepare all outgoing values in the origin block.

574

575

// Our normal algorithm for splitting critical edges requires us to update

576

// the outgoing edges of the edge origin block, but for an indirectbr this

577

// is hard, since it would require finding and updating the block addresses

578

// the indirect branch uses. But if a block only has a single indirectbr

579

// predecessor, with the others being regular branches, we can do it in a

580

// different way.

581

// Say we have A -> D, B -> D, I -> D where only I -> D is an indirectbr.

582

// We can split D into D0 and D1, where D0 contains only the PHIs from D,

583

// and D1 is the D block body. We can then duplicate D0 as D0A and D0B, and

584

// create the following structure:

585

// A -> D0A, B -> D0A, I -> D0B, D0A -> D1, D0B -> D1

586

bool CodeGenPrepare::splitIndirectCriticalEdges(Function &F) {

587

// Check whether the function has any indirectbrs, and collect which blocks

588

// they may jump to. Since most functions don't have indirect branches,

589

// this lowers the common case's overhead to O(Blocks) instead of O(Edges).

590

SmallSetVector<BasicBlock *, 16> Targets;

591

for (auto &BB : F) {

592

auto *IBI = dyn_cast<IndirectBrInst>(BB.getTerminator());

593

if (!IBI)

594

continue;

595

596

for (unsigned Succ = 0, E = IBI->getNumSuccessors(); Succ != E; ++Succ)

597

Targets.insert(IBI->getSuccessor(Succ));

598

}

599

600

if (Targets.empty())

601

return false;

602

603

bool Changed = false;

604

for (BasicBlock *Target : Targets) {

605

SmallVector<BasicBlock *, 16> OtherPreds;

606

BasicBlock *IBRPred = findIBRPredecessor(Target, OtherPreds);

607

// If we did not found an indirectbr, or the indirectbr is the only

608

// incoming edge, this isn't the kind of edge we're looking for.

609

if (!IBRPred || OtherPreds.empty())

610

continue;

611

612

// Don't even think about ehpads/landingpads.

613

Instruction *FirstNonPHI = Target->getFirstNonPHI();

614

if (FirstNonPHI->isEHPad() || Target->isLandingPad())

615

continue;

616

617

BasicBlock *BodyBlock = Target->splitBasicBlock(FirstNonPHI, ".split");

618

// It's possible Target was its own successor through an indirectbr.

619

// In this case, the indirectbr now comes from BodyBlock.

620

if (IBRPred == Target)

621

IBRPred = BodyBlock;

622

623

// At this point Target only has PHIs, and BodyBlock has the rest of the

624

// block's body. Create a copy of Target that will be used by the "direct"

625

// preds.

626

ValueToValueMapTy VMap;

627

BasicBlock *DirectSucc = CloneBasicBlock(Target, VMap, ".clone", &F);

628

629

for (BasicBlock *Pred : OtherPreds) {

630

// If the target is a loop to itself, then the terminator of the split

631

// block needs to be updated.

632

if (Pred == Target)

633

BodyBlock->getTerminator()->replaceUsesOfWith(Target, DirectSucc);

634

else

635

Pred->getTerminator()->replaceUsesOfWith(Target, DirectSucc);

636

}

637

638

// Ok, now fix up the PHIs. We know the two blocks only have PHIs, and that

639

// they are clones, so the number of PHIs are the same.

640

// (a) Remove the edge coming from IBRPred from the "Direct" PHI

641

// (b) Leave that as the only edge in the "Indirect" PHI.

642

// (c) Merge the two in the body block.

643

BasicBlock::iterator Indirect = Target->begin(),

644

End = Target->getFirstNonPHI()->getIterator();

645

BasicBlock::iterator Direct = DirectSucc->begin();

646

BasicBlock::iterator MergeInsert = BodyBlock->getFirstInsertionPt();

647

648

assert(&*End == Target->getTerminator() &&((&*End == Target->getTerminator() && "Block was expected to only contain PHIs"
) ? static_cast<void> (0) : __assert_fail ("&*End == Target->getTerminator() && \"Block was expected to only contain PHIs\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 649, __PRETTY_FUNCTION__))

649

"Block was expected to only contain PHIs")((&*End == Target->getTerminator() && "Block was expected to only contain PHIs"
) ? static_cast<void> (0) : __assert_fail ("&*End == Target->getTerminator() && \"Block was expected to only contain PHIs\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 649, __PRETTY_FUNCTION__));

650

651

while (Indirect != End) {

652

PHINode *DirPHI = cast<PHINode>(Direct);

653

PHINode *IndPHI = cast<PHINode>(Indirect);

654

655

// Now, clean up - the direct block shouldn't get the indirect value,

656

// and vice versa.

657

DirPHI->removeIncomingValue(IBRPred);

658

Direct++;

659

660

// Advance the pointer here, to avoid invalidation issues when the old

661

// PHI is erased.

662

Indirect++;

663

664

PHINode *NewIndPHI = PHINode::Create(IndPHI->getType(), 1, "ind", IndPHI);

665

NewIndPHI->addIncoming(IndPHI->getIncomingValueForBlock(IBRPred),

666

IBRPred);

667

668

// Create a PHI in the body block, to merge the direct and indirect

669

// predecessors.

670

PHINode *MergePHI =

671

PHINode::Create(IndPHI->getType(), 2, "merge", &*MergeInsert);

672

MergePHI->addIncoming(NewIndPHI, Target);

673

MergePHI->addIncoming(DirPHI, DirectSucc);

674

675

IndPHI->replaceAllUsesWith(MergePHI);

676

IndPHI->eraseFromParent();

677

}

678

679

Changed = true;

680

}

681

682

return Changed;

683

}

684

685

/// Eliminate blocks that contain only PHI nodes, debug info directives, and an

686

/// unconditional branch. Passes before isel (e.g. LSR/loopsimplify) often split

687

/// edges in ways that are non-optimal for isel. Start by eliminating these

688

/// blocks so we can split them the way we want them.

689

bool CodeGenPrepare::eliminateMostlyEmptyBlocks(Function &F) {

690

SmallPtrSet<BasicBlock *, 16> Preheaders;

691

SmallVector<Loop *, 16> LoopList(LI->begin(), LI->end());

692

while (!LoopList.empty()) {

693

Loop *L = LoopList.pop_back_val();

694

LoopList.insert(LoopList.end(), L->begin(), L->end());

695

if (BasicBlock *Preheader = L->getLoopPreheader())

696

Preheaders.insert(Preheader);

697

}

698

699

bool MadeChange = false;

700

// Note that this intentionally skips the entry block.

701

for (Function::iterator I = std::next(F.begin()), E = F.end(); I != E;) {

702

BasicBlock *BB = &*I++;

703

BasicBlock *DestBB = findDestBlockOfMergeableEmptyBlock(BB);

704

if (!DestBB ||

705

!isMergingEmptyBlockProfitable(BB, DestBB, Preheaders.count(BB)))

706

continue;

707

708

eliminateMostlyEmptyBlock(BB);

709

MadeChange = true;

710

}

711

return MadeChange;

712

}

713

714

bool CodeGenPrepare::isMergingEmptyBlockProfitable(BasicBlock *BB,

715

BasicBlock *DestBB,

716

bool isPreheader) {

717

// Do not delete loop preheaders if doing so would create a critical edge.

718

// Loop preheaders can be good locations to spill registers. If the

719

// preheader is deleted and we create a critical edge, registers may be

720

// spilled in the loop body instead.

721

if (!DisablePreheaderProtect && isPreheader &&

722

!(BB->getSinglePredecessor() &&

723

BB->getSinglePredecessor()->getSingleSuccessor()))

724

return false;

725

726

// Try to skip merging if the unique predecessor of BB is terminated by a

727

// switch or indirect branch instruction, and BB is used as an incoming block

728

// of PHIs in DestBB. In such case, merging BB and DestBB would cause ISel to

729

// add COPY instructions in the predecessor of BB instead of BB (if it is not

730

// merged). Note that the critical edge created by merging such blocks wont be

731

// split in MachineSink because the jump table is not analyzable. By keeping

732

// such empty block (BB), ISel will place COPY instructions in BB, not in the

733

// predecessor of BB.

734

BasicBlock *Pred = BB->getUniquePredecessor();

735

if (!Pred ||

736

!(isa<SwitchInst>(Pred->getTerminator()) ||

737

isa<IndirectBrInst>(Pred->getTerminator())))

738

return true;

739

740

if (BB->getTerminator() != BB->getFirstNonPHI())

741

return true;

742

743

// We use a simple cost heuristic which determine skipping merging is

744

// profitable if the cost of skipping merging is less than the cost of

745

// merging : Cost(skipping merging) < Cost(merging BB), where the

746

// Cost(skipping merging) is Freq(BB) * (Cost(Copy) + Cost(Branch)), and

747

// the Cost(merging BB) is Freq(Pred) * Cost(Copy).

748

// Assuming Cost(Copy) == Cost(Branch), we could simplify it to :

749

// Freq(Pred) / Freq(BB) > 2.

750

// Note that if there are multiple empty blocks sharing the same incoming

751

// value for the PHIs in the DestBB, we consider them together. In such

752

// case, Cost(merging BB) will be the sum of their frequencies.

753

754

if (!isa<PHINode>(DestBB->begin()))

755

return true;

756

757

SmallPtrSet<BasicBlock *, 16> SameIncomingValueBBs;

758

759

// Find all other incoming blocks from which incoming values of all PHIs in

760

// DestBB are the same as the ones from BB.

761

for (pred_iterator PI = pred_begin(DestBB), E = pred_end(DestBB); PI != E;

762

++PI) {

763

BasicBlock *DestBBPred = *PI;

764

if (DestBBPred == BB)

765

continue;

766

767

bool HasAllSameValue = true;

768

BasicBlock::const_iterator DestBBI = DestBB->begin();

769

while (const PHINode *DestPN = dyn_cast<PHINode>(DestBBI++)) {

770

if (DestPN->getIncomingValueForBlock(BB) !=

771

DestPN->getIncomingValueForBlock(DestBBPred)) {

772

HasAllSameValue = false;

773

break;

774

}

775

}

776

if (HasAllSameValue)

777

SameIncomingValueBBs.insert(DestBBPred);

778

}

779

780

// See if all BB's incoming values are same as the value from Pred. In this

781

// case, no reason to skip merging because COPYs are expected to be place in

782

// Pred already.

783

if (SameIncomingValueBBs.count(Pred))

784

return true;

785

786

if (!BFI) {

787

Function &F = *BB->getParent();

788

LoopInfo LI{DominatorTree(F)};

789

BPI.reset(new BranchProbabilityInfo(F, LI));

790

BFI.reset(new BlockFrequencyInfo(F, *BPI, LI));

791

}

792

793

BlockFrequency PredFreq = BFI->getBlockFreq(Pred);

794

BlockFrequency BBFreq = BFI->getBlockFreq(BB);

795

796

for (auto SameValueBB : SameIncomingValueBBs)

797

if (SameValueBB->getUniquePredecessor() == Pred &&

798

DestBB == findDestBlockOfMergeableEmptyBlock(SameValueBB))

799

BBFreq += BFI->getBlockFreq(SameValueBB);

800

801

return PredFreq.getFrequency() <=

802

BBFreq.getFrequency() * FreqRatioToSkipMerge;

803

}

804

805

/// Return true if we can merge BB into DestBB if there is a single

806

/// unconditional branch between them, and BB contains no other non-phi

807

/// instructions.

808

bool CodeGenPrepare::canMergeBlocks(const BasicBlock *BB,

809

const BasicBlock *DestBB) const {

810

// We only want to eliminate blocks whose phi nodes are used by phi nodes in

811

// the successor. If there are more complex condition (e.g. preheaders),

812

// don't mess around with them.

813

BasicBlock::const_iterator BBI = BB->begin();

814

while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {

815

for (const User *U : PN->users()) {

816

const Instruction *UI = cast<Instruction>(U);

817

if (UI->getParent() != DestBB || !isa<PHINode>(UI))

818

return false;

819

// If User is inside DestBB block and it is a PHINode then check

820

// incoming value. If incoming value is not from BB then this is

821

// a complex condition (e.g. preheaders) we want to avoid here.

822

if (UI->getParent() == DestBB) {

823

if (const PHINode *UPN = dyn_cast<PHINode>(UI))

824

for (unsigned I = 0, E = UPN->getNumIncomingValues(); I != E; ++I) {

825

Instruction *Insn = dyn_cast<Instruction>(UPN->getIncomingValue(I));

826

if (Insn && Insn->getParent() == BB &&

827

Insn->getParent() != UPN->getIncomingBlock(I))

828

return false;

829

}

830

}

831

}

832

}

833

834

// If BB and DestBB contain any common predecessors, then the phi nodes in BB

835

// and DestBB may have conflicting incoming values for the block. If so, we

836

// can't merge the block.

837

const PHINode *DestBBPN = dyn_cast<PHINode>(DestBB->begin());

838

if (!DestBBPN) return true; // no conflict.

839

840

// Collect the preds of BB.

841

SmallPtrSet<const BasicBlock*, 16> BBPreds;

842

if (const PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {

843

// It is faster to get preds from a PHI than with pred_iterator.

844

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

845

BBPreds.insert(BBPN->getIncomingBlock(i));

846

} else {

847

BBPreds.insert(pred_begin(BB), pred_end(BB));

848

}

849

850

// Walk the preds of DestBB.

851

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

852

BasicBlock *Pred = DestBBPN->getIncomingBlock(i);

853

if (BBPreds.count(Pred)) { // Common predecessor?

854

BBI = DestBB->begin();

855

while (const PHINode *PN = dyn_cast<PHINode>(BBI++)) {

856

const Value *V1 = PN->getIncomingValueForBlock(Pred);

857

const Value *V2 = PN->getIncomingValueForBlock(BB);

858

859

// If V2 is a phi node in BB, look up what the mapped value will be.

860

if (const PHINode *V2PN = dyn_cast<PHINode>(V2))

861

if (V2PN->getParent() == BB)

862

V2 = V2PN->getIncomingValueForBlock(Pred);

863

864

// If there is a conflict, bail out.

865

if (V1 != V2) return false;

866

}

867

}

868

}

869

870

return true;

871

}

872

873

/// Eliminate a basic block that has only phi's and an unconditional branch in

874

/// it.

875

void CodeGenPrepare::eliminateMostlyEmptyBlock(BasicBlock *BB) {

876

BranchInst *BI = cast<BranchInst>(BB->getTerminator());

877

BasicBlock *DestBB = BI->getSuccessor(0);

878

879

DEBUG(dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n" << *BB << *DestBB)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "MERGING MOSTLY EMPTY BLOCKS - BEFORE:\n"
<< *BB << *DestBB; } } while (false);

880

881

// If the destination block has a single pred, then this is a trivial edge,

882

// just collapse it.

883

if (BasicBlock *SinglePred = DestBB->getSinglePredecessor()) {

884

if (SinglePred != DestBB) {

885

// Remember if SinglePred was the entry block of the function. If so, we

886

// will need to move BB back to the entry position.

887

bool isEntry = SinglePred == &SinglePred->getParent()->getEntryBlock();

888

MergeBasicBlockIntoOnlyPred(DestBB, nullptr);

889

890

if (isEntry && BB != &BB->getParent()->getEntryBlock())

891

BB->moveBefore(&BB->getParent()->getEntryBlock());

892

893

DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false);

894

return;

895

}

896

}

897

898

// Otherwise, we have multiple predecessors of BB. Update the PHIs in DestBB

899

// to handle the new incoming edges it is about to have.

900

PHINode *PN;

901

for (BasicBlock::iterator BBI = DestBB->begin();

902

(PN = dyn_cast<PHINode>(BBI)); ++BBI) {

903

// Remove the incoming value for BB, and remember it.

904

Value *InVal = PN->removeIncomingValue(BB, false);

905

906

// Two options: either the InVal is a phi node defined in BB or it is some

907

// value that dominates BB.

908

PHINode *InValPhi = dyn_cast<PHINode>(InVal);

909

if (InValPhi && InValPhi->getParent() == BB) {

910

// Add all of the input values of the input PHI as inputs of this phi.

911

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

912

PN->addIncoming(InValPhi->getIncomingValue(i),

913

InValPhi->getIncomingBlock(i));

914

} else {

915

// Otherwise, add one instance of the dominating value for each edge that

916

// we will be adding.

917

if (PHINode *BBPN = dyn_cast<PHINode>(BB->begin())) {

918

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

919

PN->addIncoming(InVal, BBPN->getIncomingBlock(i));

920

} else {

921

for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)

922

PN->addIncoming(InVal, *PI);

923

}

924

}

925

}

926

927

// The PHIs are now updated, change everything that refers to BB to use

928

// DestBB and remove BB.

929

BB->replaceAllUsesWith(DestBB);

930

BB->eraseFromParent();

931

++NumBlocksElim;

932

933

DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "AFTER:\n" << *DestBB
<< "\n\n\n"; } } while (false);

934

}

935

936

// Computes a map of base pointer relocation instructions to corresponding

937

// derived pointer relocation instructions given a vector of all relocate calls

938

static void computeBaseDerivedRelocateMap(

939

const SmallVectorImpl<GCRelocateInst *> &AllRelocateCalls,

940

DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>>

941

&RelocateInstMap) {

942

// Collect information in two maps: one primarily for locating the base object

943

// while filling the second map; the second map is the final structure holding

944

// a mapping between Base and corresponding Derived relocate calls

945

DenseMap<std::pair<unsigned, unsigned>, GCRelocateInst *> RelocateIdxMap;

946

for (auto *ThisRelocate : AllRelocateCalls) {

947

auto K = std::make_pair(ThisRelocate->getBasePtrIndex(),

948

ThisRelocate->getDerivedPtrIndex());

949

RelocateIdxMap.insert(std::make_pair(K, ThisRelocate));

950

}

951

for (auto &Item : RelocateIdxMap) {

952

std::pair<unsigned, unsigned> Key = Item.first;

953

if (Key.first == Key.second)

954

// Base relocation: nothing to insert

955

continue;

956

957

GCRelocateInst *I = Item.second;

958

auto BaseKey = std::make_pair(Key.first, Key.first);

959

960

// We're iterating over RelocateIdxMap so we cannot modify it.

961

auto MaybeBase = RelocateIdxMap.find(BaseKey);

962

if (MaybeBase == RelocateIdxMap.end())

963

// TODO: We might want to insert a new base object relocate and gep off

964

// that, if there are enough derived object relocates.

965

continue;

966

967

RelocateInstMap[MaybeBase->second].push_back(I);

968

}

969

}

970

971

// Accepts a GEP and extracts the operands into a vector provided they're all

972

// small integer constants

973

static bool getGEPSmallConstantIntOffsetV(GetElementPtrInst *GEP,

974

SmallVectorImpl<Value *> &OffsetV) {

975

for (unsigned i = 1; i < GEP->getNumOperands(); i++) {

976

// Only accept small constant integer operands

977

auto Op = dyn_cast<ConstantInt>(GEP->getOperand(i));

978

if (!Op || Op->getZExtValue() > 20)

979

return false;

980

}

981

982

for (unsigned i = 1; i < GEP->getNumOperands(); i++)

983

OffsetV.push_back(GEP->getOperand(i));

984

return true;

985

}

986

987

// Takes a RelocatedBase (base pointer relocation instruction) and Targets to

988

// replace, computes a replacement, and affects it.

989

static bool

990

simplifyRelocatesOffABase(GCRelocateInst *RelocatedBase,

991

const SmallVectorImpl<GCRelocateInst *> &Targets) {

992

bool MadeChange = false;

993

// We must ensure the relocation of derived pointer is defined after

994

// relocation of base pointer. If we find a relocation corresponding to base

995

// defined earlier than relocation of base then we move relocation of base

996

// right before found relocation. We consider only relocation in the same

997

// basic block as relocation of base. Relocations from other basic block will

998

// be skipped by optimization and we do not care about them.

999

for (auto R = RelocatedBase->getParent()->getFirstInsertionPt();

1000

&*R != RelocatedBase; ++R)

1001

if (auto RI = dyn_cast<GCRelocateInst>(R))

1002

if (RI->getStatepoint() == RelocatedBase->getStatepoint())

1003

if (RI->getBasePtrIndex() == RelocatedBase->getBasePtrIndex()) {

1004

RelocatedBase->moveBefore(RI);

1005

break;

1006

}

1007

1008

for (GCRelocateInst *ToReplace : Targets) {

1009

assert(ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() &&((ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex
() && "Not relocating a derived object of the original base object"
) ? static_cast<void> (0) : __assert_fail ("ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1010, __PRETTY_FUNCTION__))

1010

"Not relocating a derived object of the original base object")((ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex
() && "Not relocating a derived object of the original base object"
) ? static_cast<void> (0) : __assert_fail ("ToReplace->getBasePtrIndex() == RelocatedBase->getBasePtrIndex() && \"Not relocating a derived object of the original base object\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1010, __PRETTY_FUNCTION__));

1011

if (ToReplace->getBasePtrIndex() == ToReplace->getDerivedPtrIndex()) {

1012

// A duplicate relocate call. TODO: coalesce duplicates.

1013

continue;

1014

}

1015

1016

if (RelocatedBase->getParent() != ToReplace->getParent()) {

1017

// Base and derived relocates are in different basic blocks.

1018

// In this case transform is only valid when base dominates derived

1019

// relocate. However it would be too expensive to check dominance

1020

// for each such relocate, so we skip the whole transformation.

1021

continue;

1022

}

1023

1024

Value *Base = ToReplace->getBasePtr();

1025

auto Derived = dyn_cast<GetElementPtrInst>(ToReplace->getDerivedPtr());

1026

if (!Derived || Derived->getPointerOperand() != Base)

1027

continue;

1028

1029

SmallVector<Value *, 2> OffsetV;

1030

if (!getGEPSmallConstantIntOffsetV(Derived, OffsetV))

1031

continue;

1032

1033

// Create a Builder and replace the target callsite with a gep

1034

assert(RelocatedBase->getNextNode() &&((RelocatedBase->getNextNode() && "Should always have one since it's not a terminator"
) ? static_cast<void> (0) : __assert_fail ("RelocatedBase->getNextNode() && \"Should always have one since it's not a terminator\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1035, __PRETTY_FUNCTION__))

1035

"Should always have one since it's not a terminator")((RelocatedBase->getNextNode() && "Should always have one since it's not a terminator"
) ? static_cast<void> (0) : __assert_fail ("RelocatedBase->getNextNode() && \"Should always have one since it's not a terminator\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1035, __PRETTY_FUNCTION__));

1036

1037

// Insert after RelocatedBase

1038

IRBuilder<> Builder(RelocatedBase->getNextNode());

1039

Builder.SetCurrentDebugLocation(ToReplace->getDebugLoc());

1040

1041

// If gc_relocate does not match the actual type, cast it to the right type.

1042

// In theory, there must be a bitcast after gc_relocate if the type does not

1043

// match, and we should reuse it to get the derived pointer. But it could be

1044

// cases like this:

1045

// bb1:

1046

// ...

1047

// %g1 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)

1048

// br label %merge

1049

1050

// bb2:

1051

// ...

1052

// %g2 = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(...)

1053

// br label %merge

1054

1055

// merge:

1056

// %p1 = phi i8 addrspace(1)* [ %g1, %bb1 ], [ %g2, %bb2 ]

1057

// %cast = bitcast i8 addrspace(1)* %p1 in to i32 addrspace(1)*

1058

1059

// In this case, we can not find the bitcast any more. So we insert a new bitcast

1060

// no matter there is already one or not. In this way, we can handle all cases, and

1061

// the extra bitcast should be optimized away in later passes.

1062

Value *ActualRelocatedBase = RelocatedBase;

1063

if (RelocatedBase->getType() != Base->getType()) {

1064

ActualRelocatedBase =

1065

Builder.CreateBitCast(RelocatedBase, Base->getType());

1066

}

1067

Value *Replacement = Builder.CreateGEP(

1068

Derived->getSourceElementType(), ActualRelocatedBase, makeArrayRef(OffsetV));

1069

Replacement->takeName(ToReplace);

1070

// If the newly generated derived pointer's type does not match the original derived

1071

// pointer's type, cast the new derived pointer to match it. Same reasoning as above.

1072

Value *ActualReplacement = Replacement;

1073

if (Replacement->getType() != ToReplace->getType()) {

1074

ActualReplacement =

1075

Builder.CreateBitCast(Replacement, ToReplace->getType());

1076

}

1077

ToReplace->replaceAllUsesWith(ActualReplacement);

1078

ToReplace->eraseFromParent();

1079

1080

MadeChange = true;

1081

}

1082

return MadeChange;

1083

}

1084

1085

// Turns this:

1086

1087

// %base = ...

1088

// %ptr = gep %base + 15

1089

// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)

1090

// %base' = relocate(%tok, i32 4, i32 4)

1091

// %ptr' = relocate(%tok, i32 4, i32 5)

1092

// %val = load %ptr'

1093

1094

// into this:

1095

1096

// %base = ...

1097

// %ptr = gep %base + 15

1098

// %tok = statepoint (%fun, i32 0, i32 0, i32 0, %base, %ptr)

1099

// %base' = gc.relocate(%tok, i32 4, i32 4)

1100

// %ptr' = gep %base' + 15

1101

// %val = load %ptr'

1102

bool CodeGenPrepare::simplifyOffsetableRelocate(Instruction &I) {

1103

bool MadeChange = false;

1104

SmallVector<GCRelocateInst *, 2> AllRelocateCalls;

1105

1106

for (auto *U : I.users())

1107

if (GCRelocateInst *Relocate = dyn_cast<GCRelocateInst>(U))

1108

// Collect all the relocate calls associated with a statepoint

1109

AllRelocateCalls.push_back(Relocate);

1110

1111

// We need atleast one base pointer relocation + one derived pointer

1112

// relocation to mangle

1113

if (AllRelocateCalls.size() < 2)

1114

return false;

1115

1116

// RelocateInstMap is a mapping from the base relocate instruction to the

1117

// corresponding derived relocate instructions

1118

DenseMap<GCRelocateInst *, SmallVector<GCRelocateInst *, 2>> RelocateInstMap;

1119

computeBaseDerivedRelocateMap(AllRelocateCalls, RelocateInstMap);

1120

if (RelocateInstMap.empty())

1121

return false;

1122

1123

for (auto &Item : RelocateInstMap)

1124

// Item.first is the RelocatedBase to offset against

1125

// Item.second is the vector of Targets to replace

1126

MadeChange = simplifyRelocatesOffABase(Item.first, Item.second);

1127

return MadeChange;

1128

}

1129

1130

/// SinkCast - Sink the specified cast instruction into its user blocks

1131

static bool SinkCast(CastInst *CI) {

1132

BasicBlock *DefBB = CI->getParent();

1133

1134

/// InsertedCasts - Only insert a cast in each block once.

1135

DenseMap<BasicBlock*, CastInst*> InsertedCasts;

1136

1137

bool MadeChange = false;

1138

for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();

1139

UI != E; ) {

1140

Use &TheUse = UI.getUse();

1141

Instruction *User = cast<Instruction>(*UI);

1142

1143

// Figure out which BB this cast is used in. For PHI's this is the

1144

// appropriate predecessor block.

1145

BasicBlock *UserBB = User->getParent();

1146

if (PHINode *PN = dyn_cast<PHINode>(User)) {

1147

UserBB = PN->getIncomingBlock(TheUse);

1148

}

1149

1150

// Preincrement use iterator so we don't invalidate it.

1151

++UI;

1152

1153

// The first insertion point of a block containing an EH pad is after the

1154

// pad. If the pad is the user, we cannot sink the cast past the pad.

1155

if (User->isEHPad())

1156

continue;

1157

1158

// If the block selected to receive the cast is an EH pad that does not

1159

// allow non-PHI instructions before the terminator, we can't sink the

1160

// cast.

1161

if (UserBB->getTerminator()->isEHPad())

1162

continue;

1163

1164

// If this user is in the same block as the cast, don't change the cast.

1165

if (UserBB == DefBB) continue;

1166

1167

// If we have already inserted a cast into this block, use it.

1168

CastInst *&InsertedCast = InsertedCasts[UserBB];

1169

1170

if (!InsertedCast) {

1171

BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();

1172

assert(InsertPt != UserBB->end())((InsertPt != UserBB->end()) ? static_cast<void> (0)
: __assert_fail ("InsertPt != UserBB->end()", "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1172, __PRETTY_FUNCTION__));

1173

InsertedCast = CastInst::Create(CI->getOpcode(), CI->getOperand(0),

1174

CI->getType(), "", &*InsertPt);

1175

}

1176

1177

// Replace a use of the cast with a use of the new cast.

1178

TheUse = InsertedCast;

1179

MadeChange = true;

1180

++NumCastUses;

1181

}

1182

1183

// If we removed all uses, nuke the cast.

1184

if (CI->use_empty()) {

1185

CI->eraseFromParent();

1186

MadeChange = true;

1187

}

1188

1189

return MadeChange;

1190

}

1191

1192

/// If the specified cast instruction is a noop copy (e.g. it's casting from

1193

/// one pointer type to another, i32->i8 on PPC), sink it into user blocks to

1194

/// reduce the number of virtual registers that must be created and coalesced.

1195

///

1196

/// Return true if any changes are made.

1197

static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI,

1198

const DataLayout &DL) {

1199

// Sink only "cheap" (or nop) address-space casts. This is a weaker condition

1200

// than sinking only nop casts, but is helpful on some platforms.

1201

if (auto *ASC = dyn_cast<AddrSpaceCastInst>(CI)) {

1202

if (!TLI.isCheapAddrSpaceCast(ASC->getSrcAddressSpace(),

1203

ASC->getDestAddressSpace()))

1204

return false;

1205

}

1206

1207

// If this is a noop copy,

1208

EVT SrcVT = TLI.getValueType(DL, CI->getOperand(0)->getType());

1209

EVT DstVT = TLI.getValueType(DL, CI->getType());

1210

1211

// This is an fp<->int conversion?

1212

if (SrcVT.isInteger() != DstVT.isInteger())

1213

return false;

1214

1215

// If this is an extension, it will be a zero or sign extension, which

1216

// isn't a noop.

1217

if (SrcVT.bitsLT(DstVT)) return false;

1218

1219

// If these values will be promoted, find out what they will be promoted

1220

// to. This helps us consider truncates on PPC as noop copies when they

1221

// are.

1222

if (TLI.getTypeAction(CI->getContext(), SrcVT) ==

1223

TargetLowering::TypePromoteInteger)

1224

SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);

1225

if (TLI.getTypeAction(CI->getContext(), DstVT) ==

1226

TargetLowering::TypePromoteInteger)

1227

DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);

1228

1229

// If, after promotion, these are the same types, this is a noop copy.

1230

if (SrcVT != DstVT)

1231

return false;

1232

1233

return SinkCast(CI);

1234

}

1235

1236

/// Try to combine CI into a call to the llvm.uadd.with.overflow intrinsic if

1237

/// possible.

1238

///

1239

/// Return true if any changes were made.

1240

static bool CombineUAddWithOverflow(CmpInst *CI) {

1241

Value *A, *B;

1242

Instruction *AddI;

1243

if (!match(CI,

1244

m_UAddWithOverflow(m_Value(A), m_Value(B), m_Instruction(AddI))))

1245

return false;

1246

1247

Type *Ty = AddI->getType();

1248

if (!isa<IntegerType>(Ty))

1249

return false;

1250

1251

// We don't want to move around uses of condition values this late, so we we

1252

// check if it is legal to create the call to the intrinsic in the basic

1253

// block containing the icmp:

1254

1255

if (AddI->getParent() != CI->getParent() && !AddI->hasOneUse())

1256

return false;

1257

1258

#ifndef NDEBUG

1259

// Someday m_UAddWithOverflow may get smarter, but this is a safe assumption

1260

// for now:

1261

if (AddI->hasOneUse())

1262

assert(*AddI->user_begin() == CI && "expected!")((*AddI->user_begin() == CI && "expected!") ? static_cast
<void> (0) : __assert_fail ("*AddI->user_begin() == CI && \"expected!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1262, __PRETTY_FUNCTION__));

1263

#endif

1264

1265

Module *M = CI->getModule();

1266

Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);

1267

1268

auto *InsertPt = AddI->hasOneUse() ? CI : AddI;

1269

1270

auto *UAddWithOverflow =

1271

CallInst::Create(F, {A, B}, "uadd.overflow", InsertPt);

1272

auto *UAdd = ExtractValueInst::Create(UAddWithOverflow, 0, "uadd", InsertPt);

1273

auto *Overflow =

1274

ExtractValueInst::Create(UAddWithOverflow, 1, "overflow", InsertPt);

1275

1276

CI->replaceAllUsesWith(Overflow);

1277

AddI->replaceAllUsesWith(UAdd);

1278

CI->eraseFromParent();

1279

AddI->eraseFromParent();

1280

return true;

1281

}

1282

1283

/// Sink the given CmpInst into user blocks to reduce the number of virtual

1284

/// registers that must be created and coalesced. This is a clear win except on

1285

/// targets with multiple condition code registers (PowerPC), where it might

1286

/// lose; some adjustment may be wanted there.

1287

///

1288

/// Return true if any changes are made.

1289

static bool SinkCmpExpression(CmpInst *CI, const TargetLowering *TLI) {

1290

BasicBlock *DefBB = CI->getParent();

1291

1292

// Avoid sinking soft-FP comparisons, since this can move them into a loop.

1293

if (TLI && TLI->useSoftFloat() && isa<FCmpInst>(CI))

1294

return false;

1295

1296

// Only insert a cmp in each block once.

1297

DenseMap<BasicBlock*, CmpInst*> InsertedCmps;

1298

1299

bool MadeChange = false;

1300

for (Value::user_iterator UI = CI->user_begin(), E = CI->user_end();

1301

UI != E; ) {

1302

Use &TheUse = UI.getUse();

1303

Instruction *User = cast<Instruction>(*UI);

1304

1305

// Preincrement use iterator so we don't invalidate it.

1306

++UI;

1307

1308

// Don't bother for PHI nodes.

1309

if (isa<PHINode>(User))

1310

continue;

1311

1312

// Figure out which BB this cmp is used in.

1313

BasicBlock *UserBB = User->getParent();

1314

1315

// If this user is in the same block as the cmp, don't change the cmp.

1316

if (UserBB == DefBB) continue;

1317

1318

// If we have already inserted a cmp into this block, use it.

1319

CmpInst *&InsertedCmp = InsertedCmps[UserBB];

1320

1321

if (!InsertedCmp) {

1322

BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();

1323

1324

InsertedCmp =

1325

CmpInst::Create(CI->getOpcode(), CI->getPredicate(),

1326

CI->getOperand(0), CI->getOperand(1), "", &*InsertPt);

1327

// Propagate the debug info.

1328

InsertedCmp->setDebugLoc(CI->getDebugLoc());

1329

}

1330

1331

// Replace a use of the cmp with a use of the new cmp.

1332

TheUse = InsertedCmp;

1333

MadeChange = true;

1334

++NumCmpUses;

1335

}

1336

1337

// If we removed all uses, nuke the cmp.

1338

if (CI->use_empty()) {

1339

CI->eraseFromParent();

1340

MadeChange = true;

1341

}

1342

1343

return MadeChange;

1344

}

1345

1346

static bool OptimizeCmpExpression(CmpInst *CI, const TargetLowering *TLI) {

1347

if (SinkCmpExpression(CI, TLI))

1348

return true;

1349

1350

if (CombineUAddWithOverflow(CI))

1351

return true;

1352

1353

return false;

1354

}

1355

1356

/// Duplicate and sink the given 'and' instruction into user blocks where it is

1357

/// used in a compare to allow isel to generate better code for targets where

1358

/// this operation can be combined.

1359

///

1360

/// Return true if any changes are made.

1361

static bool sinkAndCmp0Expression(Instruction *AndI,

1362

const TargetLowering &TLI,

1363

SetOfInstrs &InsertedInsts) {

1364

// Double-check that we're not trying to optimize an instruction that was

1365

// already optimized by some other part of this pass.

1366

assert(!InsertedInsts.count(AndI) &&((!InsertedInsts.count(AndI) && "Attempting to optimize already optimized and instruction"
) ? static_cast<void> (0) : __assert_fail ("!InsertedInsts.count(AndI) && \"Attempting to optimize already optimized and instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1367, __PRETTY_FUNCTION__))

1367

"Attempting to optimize already optimized and instruction")((!InsertedInsts.count(AndI) && "Attempting to optimize already optimized and instruction"
) ? static_cast<void> (0) : __assert_fail ("!InsertedInsts.count(AndI) && \"Attempting to optimize already optimized and instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1367, __PRETTY_FUNCTION__));

1368

(void) InsertedInsts;

1369

1370

// Nothing to do for single use in same basic block.

1371

if (AndI->hasOneUse() &&

1372

AndI->getParent() == cast<Instruction>(*AndI->user_begin())->getParent())

1373

return false;

1374

1375

// Try to avoid cases where sinking/duplicating is likely to increase register

1376

// pressure.

1377

if (!isa<ConstantInt>(AndI->getOperand(0)) &&

1378

!isa<ConstantInt>(AndI->getOperand(1)) &&

1379

AndI->getOperand(0)->hasOneUse() && AndI->getOperand(1)->hasOneUse())

1380

return false;

1381

1382

for (auto *U : AndI->users()) {

1383

Instruction *User = cast<Instruction>(U);

1384

1385

// Only sink for and mask feeding icmp with 0.

1386

if (!isa<ICmpInst>(User))

1387

return false;

1388

1389

auto *CmpC = dyn_cast<ConstantInt>(User->getOperand(1));

1390

if (!CmpC || !CmpC->isZero())

1391

return false;

1392

}

1393

1394

if (!TLI.isMaskAndCmp0FoldingBeneficial(*AndI))

1395

return false;

1396

1397

DEBUG(dbgs() << "found 'and' feeding only icmp 0;\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "found 'and' feeding only icmp 0;\n"
; } } while (false);

1398

DEBUG(AndI->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { AndI->getParent()->dump(); } } while
(false);

1399

1400

// Push the 'and' into the same block as the icmp 0. There should only be

1401

// one (icmp (and, 0)) in each block, since CSE/GVN should have removed any

1402

// others, so we don't need to keep track of which BBs we insert into.

1403

for (Value::user_iterator UI = AndI->user_begin(), E = AndI->user_end();

1404

UI != E; ) {

1405

Use &TheUse = UI.getUse();

1406

Instruction *User = cast<Instruction>(*UI);

1407

1408

// Preincrement use iterator so we don't invalidate it.

1409

++UI;

1410

1411

DEBUG(dbgs() << "sinking 'and' use: " << *User << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "sinking 'and' use: " <<
*User << "\n"; } } while (false);

1412

1413

// Keep the 'and' in the same place if the use is already in the same block.

1414

Instruction *InsertPt =

1415

User->getParent() == AndI->getParent() ? AndI : User;

1416

Instruction *InsertedAnd =

1417

BinaryOperator::Create(Instruction::And, AndI->getOperand(0),

1418

AndI->getOperand(1), "", InsertPt);

1419

// Propagate the debug info.

1420

InsertedAnd->setDebugLoc(AndI->getDebugLoc());

1421

1422

// Replace a use of the 'and' with a use of the new 'and'.

1423

TheUse = InsertedAnd;

1424

++NumAndUses;

1425

DEBUG(User->getParent()->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { User->getParent()->dump(); } } while
(false);

1426

}

1427

1428

// We removed all uses, nuke the and.

1429

AndI->eraseFromParent();

1430

return true;

1431

}

1432

1433

/// Check if the candidates could be combined with a shift instruction, which

1434

/// includes:

1435

/// 1. Truncate instruction

1436

/// 2. And instruction and the imm is a mask of the low bits:

1437

/// imm & (imm+1) == 0

1438

static bool isExtractBitsCandidateUse(Instruction *User) {

1439

if (!isa<TruncInst>(User)) {

1440

if (User->getOpcode() != Instruction::And ||

1441

!isa<ConstantInt>(User->getOperand(1)))

1442

return false;

1443

1444

const APInt &Cimm = cast<ConstantInt>(User->getOperand(1))->getValue();

1445

1446

if ((Cimm & (Cimm + 1)).getBoolValue())

1447

return false;

1448

}

1449

return true;

1450

}

1451

1452

/// Sink both shift and truncate instruction to the use of truncate's BB.

1453

static bool

1454

SinkShiftAndTruncate(BinaryOperator *ShiftI, Instruction *User, ConstantInt *CI,

1455

DenseMap<BasicBlock *, BinaryOperator *> &InsertedShifts,

1456

const TargetLowering &TLI, const DataLayout &DL) {

1457

BasicBlock *UserBB = User->getParent();

1458

DenseMap<BasicBlock *, CastInst *> InsertedTruncs;

1459

TruncInst *TruncI = dyn_cast<TruncInst>(User);

1460

bool MadeChange = false;

1461

1462

for (Value::user_iterator TruncUI = TruncI->user_begin(),

1463

TruncE = TruncI->user_end();

1464

TruncUI != TruncE;) {

1465

1466

Use &TruncTheUse = TruncUI.getUse();

1467

Instruction *TruncUser = cast<Instruction>(*TruncUI);

1468

// Preincrement use iterator so we don't invalidate it.

1469

1470

++TruncUI;

1471

1472

int ISDOpcode = TLI.InstructionOpcodeToISD(TruncUser->getOpcode());

1473

if (!ISDOpcode)

1474

continue;

1475

1476

// If the use is actually a legal node, there will not be an

1477

// implicit truncate.

1478

// FIXME: always querying the result type is just an

1479

// approximation; some nodes' legality is determined by the

1480

// operand or other means. There's no good way to find out though.

1481

if (TLI.isOperationLegalOrCustom(

1482

ISDOpcode, TLI.getValueType(DL, TruncUser->getType(), true)))

1483

continue;

1484

1485

// Don't bother for PHI nodes.

1486

if (isa<PHINode>(TruncUser))

1487

continue;

1488

1489

BasicBlock *TruncUserBB = TruncUser->getParent();

1490

1491

if (UserBB == TruncUserBB)

1492

continue;

1493

1494

BinaryOperator *&InsertedShift = InsertedShifts[TruncUserBB];

1495

CastInst *&InsertedTrunc = InsertedTruncs[TruncUserBB];

1496

1497

if (!InsertedShift && !InsertedTrunc) {

1498

BasicBlock::iterator InsertPt = TruncUserBB->getFirstInsertionPt();

1499

assert(InsertPt != TruncUserBB->end())((InsertPt != TruncUserBB->end()) ? static_cast<void>
(0) : __assert_fail ("InsertPt != TruncUserBB->end()", "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1499, __PRETTY_FUNCTION__));

1500

// Sink the shift

1501

if (ShiftI->getOpcode() == Instruction::AShr)

1502

InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,

1503

"", &*InsertPt);

1504

else

1505

InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,

1506

"", &*InsertPt);

1507

1508

// Sink the trunc

1509

BasicBlock::iterator TruncInsertPt = TruncUserBB->getFirstInsertionPt();

1510

TruncInsertPt++;

1511

assert(TruncInsertPt != TruncUserBB->end())((TruncInsertPt != TruncUserBB->end()) ? static_cast<void
> (0) : __assert_fail ("TruncInsertPt != TruncUserBB->end()"
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1511, __PRETTY_FUNCTION__));

1512

1513

InsertedTrunc = CastInst::Create(TruncI->getOpcode(), InsertedShift,

1514

TruncI->getType(), "", &*TruncInsertPt);

1515

1516

MadeChange = true;

1517

1518

TruncTheUse = InsertedTrunc;

1519

}

1520

}

1521

return MadeChange;

1522

}

1523

1524

/// Sink the shift *right* instruction into user blocks if the uses could

1525

/// potentially be combined with this shift instruction and generate BitExtract

1526

/// instruction. It will only be applied if the architecture supports BitExtract

1527

/// instruction. Here is an example:

1528

/// BB1:

1529

/// %x.extract.shift = lshr i64 %arg1, 32

1530

/// BB2:

1531

/// %x.extract.trunc = trunc i64 %x.extract.shift to i16

1532

/// ==>

1533

///

1534

/// BB2:

1535

/// %x.extract.shift.1 = lshr i64 %arg1, 32

1536

/// %x.extract.trunc = trunc i64 %x.extract.shift.1 to i16

1537

///

1538

/// CodeGen will recoginze the pattern in BB2 and generate BitExtract

1539

/// instruction.

1540

/// Return true if any changes are made.

1541

static bool OptimizeExtractBits(BinaryOperator *ShiftI, ConstantInt *CI,

1542

const TargetLowering &TLI,

1543

const DataLayout &DL) {

1544

BasicBlock *DefBB = ShiftI->getParent();

1545

1546

/// Only insert instructions in each block once.

1547

DenseMap<BasicBlock *, BinaryOperator *> InsertedShifts;

1548

1549

bool shiftIsLegal = TLI.isTypeLegal(TLI.getValueType(DL, ShiftI->getType()));

1550

1551

bool MadeChange = false;

1552

for (Value::user_iterator UI = ShiftI->user_begin(), E = ShiftI->user_end();

1553

UI != E;) {

1554

Use &TheUse = UI.getUse();

1555

Instruction *User = cast<Instruction>(*UI);

1556

// Preincrement use iterator so we don't invalidate it.

1557

++UI;

1558

1559

// Don't bother for PHI nodes.

1560

if (isa<PHINode>(User))

1561

continue;

1562

1563

if (!isExtractBitsCandidateUse(User))

1564

continue;

1565

1566

BasicBlock *UserBB = User->getParent();

1567

1568

if (UserBB == DefBB) {

1569

// If the shift and truncate instruction are in the same BB. The use of

1570

// the truncate(TruncUse) may still introduce another truncate if not

1571

// legal. In this case, we would like to sink both shift and truncate

1572

// instruction to the BB of TruncUse.

1573

// for example:

1574

// BB1:

1575

// i64 shift.result = lshr i64 opnd, imm

1576

// trunc.result = trunc shift.result to i16

1577

1578

// BB2:

1579

// ----> We will have an implicit truncate here if the architecture does

1580

// not have i16 compare.

1581

// cmp i16 trunc.result, opnd2

1582

1583

if (isa<TruncInst>(User) && shiftIsLegal

1584

// If the type of the truncate is legal, no trucate will be

1585

// introduced in other basic blocks.

1586

1587

(!TLI.isTypeLegal(TLI.getValueType(DL, User->getType()))))

1588

MadeChange =

1589

SinkShiftAndTruncate(ShiftI, User, CI, InsertedShifts, TLI, DL);

1590

1591

continue;

1592

}

1593

// If we have already inserted a shift into this block, use it.

1594

BinaryOperator *&InsertedShift = InsertedShifts[UserBB];

1595

1596

if (!InsertedShift) {

1597

BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();

1598

1599

1600

if (ShiftI->getOpcode() == Instruction::AShr)

1601

InsertedShift = BinaryOperator::CreateAShr(ShiftI->getOperand(0), CI,

1602

"", &*InsertPt);

1603

else

1604

InsertedShift = BinaryOperator::CreateLShr(ShiftI->getOperand(0), CI,

1605

"", &*InsertPt);

1606

1607

MadeChange = true;

1608

}

1609

1610

// Replace a use of the shift with a use of the new shift.

1611

TheUse = InsertedShift;

1612

}

1613

1614

// If we removed all uses, nuke the shift.

1615

if (ShiftI->use_empty())

1616

ShiftI->eraseFromParent();

1617

1618

return MadeChange;

1619

}

1620

1621

/// If counting leading or trailing zeros is an expensive operation and a zero

1622

/// input is defined, add a check for zero to avoid calling the intrinsic.

1623

///

1624

/// We want to transform:

1625

/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 false)

1626

///

1627

/// into:

1628

/// entry:

1629

/// %cmpz = icmp eq i64 %A, 0

1630

/// br i1 %cmpz, label %cond.end, label %cond.false

1631

/// cond.false:

1632

/// %z = call i64 @llvm.cttz.i64(i64 %A, i1 true)

1633

/// br label %cond.end

1634

/// cond.end:

1635

/// %ctz = phi i64 [ 64, %entry ], [ %z, %cond.false ]

1636

///

1637

/// If the transform is performed, return true and set ModifiedDT to true.

1638

static bool despeculateCountZeros(IntrinsicInst *CountZeros,

1639

const TargetLowering *TLI,

1640

const DataLayout *DL,

1641

bool &ModifiedDT) {

1642

if (!TLI || !DL)

1643

return false;

1644

1645

// If a zero input is undefined, it doesn't make sense to despeculate that.

1646

if (match(CountZeros->getOperand(1), m_One()))

1647

return false;

1648

1649

// If it's cheap to speculate, there's nothing to do.

1650

auto IntrinsicID = CountZeros->getIntrinsicID();

1651

if ((IntrinsicID == Intrinsic::cttz && TLI->isCheapToSpeculateCttz()) ||

1652

(IntrinsicID == Intrinsic::ctlz && TLI->isCheapToSpeculateCtlz()))

1653

return false;

1654

1655

// Only handle legal scalar cases. Anything else requires too much work.

1656

Type *Ty = CountZeros->getType();

1657

unsigned SizeInBits = Ty->getPrimitiveSizeInBits();

1658

if (Ty->isVectorTy() || SizeInBits > DL->getLargestLegalIntTypeSizeInBits())

1659

return false;

1660

1661

// The intrinsic will be sunk behind a compare against zero and branch.

1662

BasicBlock *StartBlock = CountZeros->getParent();

1663

BasicBlock *CallBlock = StartBlock->splitBasicBlock(CountZeros, "cond.false");

1664

1665

// Create another block after the count zero intrinsic. A PHI will be added

1666

// in this block to select the result of the intrinsic or the bit-width

1667

// constant if the input to the intrinsic is zero.

1668

BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(CountZeros));

1669

BasicBlock *EndBlock = CallBlock->splitBasicBlock(SplitPt, "cond.end");

1670

1671

// Set up a builder to create a compare, conditional branch, and PHI.

1672

IRBuilder<> Builder(CountZeros->getContext());

1673

Builder.SetInsertPoint(StartBlock->getTerminator());

1674

Builder.SetCurrentDebugLocation(CountZeros->getDebugLoc());

1675

1676

// Replace the unconditional branch that was created by the first split with

1677

// a compare against zero and a conditional branch.

1678

Value *Zero = Constant::getNullValue(Ty);

1679

Value *Cmp = Builder.CreateICmpEQ(CountZeros->getOperand(0), Zero, "cmpz");

1680

Builder.CreateCondBr(Cmp, EndBlock, CallBlock);

1681

StartBlock->getTerminator()->eraseFromParent();

1682

1683

// Create a PHI in the end block to select either the output of the intrinsic

1684

// or the bit width of the operand.

1685

Builder.SetInsertPoint(&EndBlock->front());

1686

PHINode *PN = Builder.CreatePHI(Ty, 2, "ctz");

1687

CountZeros->replaceAllUsesWith(PN);

1688

Value *BitWidth = Builder.getInt(APInt(SizeInBits, SizeInBits));

1689

PN->addIncoming(BitWidth, StartBlock);

1690

PN->addIncoming(CountZeros, CallBlock);

1691

1692

// We are explicitly handling the zero case, so we can set the intrinsic's

1693

// undefined zero argument to 'true'. This will also prevent reprocessing the

1694

// intrinsic; we only despeculate when a zero input is defined.

1695

CountZeros->setArgOperand(1, Builder.getTrue());

1696

ModifiedDT = true;

1697

return true;

1698

}

1699

1700

namespace {

1701

1702

// This class provides helper functions to expand a memcmp library call into an

1703

// inline expansion.

1704

class MemCmpExpansion {

1705

struct ResultBlock {

1706

BasicBlock *BB = nullptr;

1707

PHINode *PhiSrc1 = nullptr;

1708

PHINode *PhiSrc2 = nullptr;

1709

1710

ResultBlock() = default;

1711

};

1712

1713

CallInst *CI;

1714

ResultBlock ResBlock;

1715

unsigned MaxLoadSize;

1716

unsigned NumBlocks;

1717

unsigned NumBlocksNonOneByte;

1718

unsigned NumLoadsPerBlock;

1719

std::vector<BasicBlock *> LoadCmpBlocks;

1720

BasicBlock *EndBlock;

1721

PHINode *PhiRes;

1722

bool IsUsedForZeroCmp;

1723

const DataLayout &DL;

1724

IRBuilder<> Builder;

1725

1726

unsigned calculateNumBlocks(unsigned Size);

1727

void createLoadCmpBlocks();

1728

void createResultBlock();

1729

void setupResultBlockPHINodes();

1730

void setupEndBlockPHINodes();

1731

void emitLoadCompareBlock(unsigned Index, unsigned LoadSize,

1732

unsigned GEPIndex);

1733

Value *getCompareLoadPairs(unsigned Index, unsigned Size,

1734

unsigned &NumBytesProcessed);

1735

void emitLoadCompareBlockMultipleLoads(unsigned Index, unsigned Size,

1736

unsigned &NumBytesProcessed);

1737

void emitLoadCompareByteBlock(unsigned Index, unsigned GEPIndex);

1738

void emitMemCmpResultBlock();

1739

Value *getMemCmpExpansionZeroCase(unsigned Size);

1740

Value *getMemCmpEqZeroOneBlock(unsigned Size);

1741

Value *getMemCmpOneBlock(unsigned Size);

1742

unsigned getLoadSize(unsigned Size);

1743

unsigned getNumLoads(unsigned Size);

1744

1745

public:

1746

MemCmpExpansion(CallInst *CI, uint64_t Size, unsigned MaxLoadSize,

1747

unsigned NumLoadsPerBlock, const DataLayout &DL);

1748

1749

Value *getMemCmpExpansion(uint64_t Size);

1750

};

1751

1752

} // end anonymous namespace

1753

1754

// Initialize the basic block structure required for expansion of memcmp call

1755

// with given maximum load size and memcmp size parameter.

1756

// This structure includes:

1757

// 1. A list of load compare blocks - LoadCmpBlocks.

1758

// 2. An EndBlock, split from original instruction point, which is the block to

1759

// return from.

1760

// 3. ResultBlock, block to branch to for early exit when a

1761

// LoadCmpBlock finds a difference.

1762

MemCmpExpansion::MemCmpExpansion(CallInst *CI, uint64_t Size,

1763

unsigned MaxLoadSize, unsigned LoadsPerBlock,

1764

const DataLayout &TheDataLayout)

1765

: CI(CI), MaxLoadSize(MaxLoadSize), NumLoadsPerBlock(LoadsPerBlock),

1766

DL(TheDataLayout), Builder(CI) {

1767

// A memcmp with zero-comparison with only one block of load and compare does

1768

// not need to set up any extra blocks. This case could be handled in the DAG,

1769

// but since we have all of the machinery to flexibly expand any memcpy here,

1770

// we choose to handle this case too to avoid fragmented lowering.

1771

IsUsedForZeroCmp = isOnlyUsedInZeroEqualityComparison(CI);

1772

NumBlocks = calculateNumBlocks(Size);

1773

if ((!IsUsedForZeroCmp && NumLoadsPerBlock != 1) || NumBlocks != 1) {

1774

BasicBlock *StartBlock = CI->getParent();

1775

EndBlock = StartBlock->splitBasicBlock(CI, "endblock");

1776

setupEndBlockPHINodes();

1777

createResultBlock();

1778

1779

// If return value of memcmp is not used in a zero equality, we need to

1780

// calculate which source was larger. The calculation requires the

1781

// two loaded source values of each load compare block.

1782

// These will be saved in the phi nodes created by setupResultBlockPHINodes.

1783

if (!IsUsedForZeroCmp)

1784

setupResultBlockPHINodes();

1785

1786

// Create the number of required load compare basic blocks.

1787

createLoadCmpBlocks();

1788

1789

// Update the terminator added by splitBasicBlock to branch to the first

1790

// LoadCmpBlock.

1791

StartBlock->getTerminator()->setSuccessor(0, LoadCmpBlocks[0]);

1792

}

1793

1794

Builder.SetCurrentDebugLocation(CI->getDebugLoc());

1795

}

1796

1797

void MemCmpExpansion::createLoadCmpBlocks() {

1798

for (unsigned i = 0; i < NumBlocks; i++) {

1799

BasicBlock *BB = BasicBlock::Create(CI->getContext(), "loadbb",

1800

EndBlock->getParent(), EndBlock);

1801

LoadCmpBlocks.push_back(BB);

1802

}

1803

}

1804

1805

void MemCmpExpansion::createResultBlock() {

1806

ResBlock.BB = BasicBlock::Create(CI->getContext(), "res_block",

1807

EndBlock->getParent(), EndBlock);

1808

}

1809

1810

// This function creates the IR instructions for loading and comparing 1 byte.

1811

// It loads 1 byte from each source of the memcmp parameters with the given

1812

// GEPIndex. It then subtracts the two loaded values and adds this result to the

1813

// final phi node for selecting the memcmp result.

1814

void MemCmpExpansion::emitLoadCompareByteBlock(unsigned Index,

1815

unsigned GEPIndex) {

1816

Value *Source1 = CI->getArgOperand(0);

1817

Value *Source2 = CI->getArgOperand(1);

1818

1819

Builder.SetInsertPoint(LoadCmpBlocks[Index]);

1820

Type *LoadSizeType = Type::getInt8Ty(CI->getContext());

1821

// Cast source to LoadSizeType*.

1822

if (Source1->getType() != LoadSizeType)

1823

Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());

1824

if (Source2->getType() != LoadSizeType)

1825

Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());

1826

1827

// Get the base address using the GEPIndex.

1828

if (GEPIndex != 0) {

1829

Source1 = Builder.CreateGEP(LoadSizeType, Source1,

1830

ConstantInt::get(LoadSizeType, GEPIndex));

1831

Source2 = Builder.CreateGEP(LoadSizeType, Source2,

1832

ConstantInt::get(LoadSizeType, GEPIndex));

1833

}

1834

1835

Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);

1836

Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);

1837

1838

LoadSrc1 = Builder.CreateZExt(LoadSrc1, Type::getInt32Ty(CI->getContext()));

1839

LoadSrc2 = Builder.CreateZExt(LoadSrc2, Type::getInt32Ty(CI->getContext()));

1840

Value *Diff = Builder.CreateSub(LoadSrc1, LoadSrc2);

1841

1842

PhiRes->addIncoming(Diff, LoadCmpBlocks[Index]);

1843

1844

if (Index < (LoadCmpBlocks.size() - 1)) {

1845

// Early exit branch if difference found to EndBlock. Otherwise, continue to

1846

// next LoadCmpBlock,

1847

Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_NE, Diff,

1848

ConstantInt::get(Diff->getType(), 0));

1849

BranchInst *CmpBr =

1850

BranchInst::Create(EndBlock, LoadCmpBlocks[Index + 1], Cmp);

1851

Builder.Insert(CmpBr);

1852

} else {

1853

// The last block has an unconditional branch to EndBlock.

1854

BranchInst *CmpBr = BranchInst::Create(EndBlock);

1855

Builder.Insert(CmpBr);

1856

}

1857

}

1858

1859

unsigned MemCmpExpansion::getNumLoads(unsigned Size) {

1860

return (Size / MaxLoadSize) + countPopulation(Size % MaxLoadSize);

1861

}

1862

1863

unsigned MemCmpExpansion::getLoadSize(unsigned Size) {

1864

return MinAlign(PowerOf2Floor(Size), MaxLoadSize);

1865

}

1866

1867

/// Generate an equality comparison for one or more pairs of loaded values.

1868

/// This is used in the case where the memcmp() call is compared equal or not

1869

/// equal to zero.

1870

Value *MemCmpExpansion::getCompareLoadPairs(unsigned Index, unsigned Size,

1871

unsigned &NumBytesProcessed) {

1872

std::vector<Value *> XorList, OrList;

1873

Value *Diff;

←

'Diff' declared without an initial value

→

1874

1875

unsigned RemainingBytes = Size - NumBytesProcessed;

1876

unsigned NumLoadsRemaining = getNumLoads(RemainingBytes);

1877

unsigned NumLoads = std::min(NumLoadsRemaining, NumLoadsPerBlock);

1878

1879

// For a single-block expansion, start inserting before the memcmp call.

1880

if (LoadCmpBlocks.empty())

←

Assuming the condition is false

→

←

Taking false branch

→

1881

Builder.SetInsertPoint(CI);

1882

else

1883

Builder.SetInsertPoint(LoadCmpBlocks[Index]);

1884

1885

Value *Cmp = nullptr;

1886

for (unsigned i = 0; i < NumLoads; ++i) {

←

Assuming 'i' is >= 'NumLoads'

→

←

Loop condition is false. Execution continues on line 1945

→

1887

unsigned LoadSize = getLoadSize(RemainingBytes);

1888

unsigned GEPIndex = NumBytesProcessed / LoadSize;

1889

NumBytesProcessed += LoadSize;

1890

RemainingBytes -= LoadSize;

1891

1892

Type *LoadSizeType = IntegerType::get(CI->getContext(), LoadSize * 8);

1893

Type *MaxLoadType = IntegerType::get(CI->getContext(), MaxLoadSize * 8);

1894

assert(LoadSize <= MaxLoadSize && "Unexpected load type")((LoadSize <= MaxLoadSize && "Unexpected load type"
) ? static_cast<void> (0) : __assert_fail ("LoadSize <= MaxLoadSize && \"Unexpected load type\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 1894, __PRETTY_FUNCTION__));

1895

1896

Value *Source1 = CI->getArgOperand(0);

1897

Value *Source2 = CI->getArgOperand(1);

1898

1899

// Cast source to LoadSizeType*.

1900

if (Source1->getType() != LoadSizeType)

1901

Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());

1902

if (Source2->getType() != LoadSizeType)

1903

Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());

1904

1905

// Get the base address using the GEPIndex.

1906

if (GEPIndex != 0) {

1907

Source1 = Builder.CreateGEP(LoadSizeType, Source1,

1908

ConstantInt::get(LoadSizeType, GEPIndex));

1909

Source2 = Builder.CreateGEP(LoadSizeType, Source2,

1910

ConstantInt::get(LoadSizeType, GEPIndex));

1911

}

1912

1913

// Get a constant or load a value for each source address.

1914

Value *LoadSrc1 = nullptr;

1915

if (auto *Source1C = dyn_cast<Constant>(Source1))

1916

LoadSrc1 = ConstantFoldLoadFromConstPtr(Source1C, LoadSizeType, DL);

1917

if (!LoadSrc1)

1918

LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);

1919

1920

Value *LoadSrc2 = nullptr;

1921

if (auto *Source2C = dyn_cast<Constant>(Source2))

1922

LoadSrc2 = ConstantFoldLoadFromConstPtr(Source2C, LoadSizeType, DL);

1923

if (!LoadSrc2)

1924

LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);

1925

1926

if (NumLoads != 1) {

1927

if (LoadSizeType != MaxLoadType) {

1928

LoadSrc1 = Builder.CreateZExt(LoadSrc1, MaxLoadType);

1929

LoadSrc2 = Builder.CreateZExt(LoadSrc2, MaxLoadType);

1930

}

1931

// If we have multiple loads per block, we need to generate a composite

1932

// comparison using xor+or.

1933

Diff = Builder.CreateXor(LoadSrc1, LoadSrc2);

1934

Diff = Builder.CreateZExt(Diff, MaxLoadType);

1935

XorList.push_back(Diff);

1936

} else {

1937

// If there's only one load per block, we just compare the loaded values.

1938

Cmp = Builder.CreateICmpNE(LoadSrc1, LoadSrc2);

1939

}

1940

}

1941

1942

auto pairWiseOr = [&](std::vector<Value *> &InList) -> std::vector<Value *> {

1943

std::vector<Value *> OutList;

1944

for (unsigned i = 0; i < InList.size() - 1; i = i + 2) {

1945

Value *Or = Builder.CreateOr(InList[i], InList[i + 1]);

1946

OutList.push_back(Or);

1947

}

1948

if (InList.size() % 2 != 0)

1949

OutList.push_back(InList.back());

1950

return OutList;

1951

};

1952

1953

if (!Cmp) {

←

Taking true branch

→

1954

// Pairwise OR the XOR results.

1955

OrList = pairWiseOr(XorList);

1956

1957

// Pairwise OR the OR results until one result left.

1958

while (OrList.size() != 1) {

←

Assuming the condition is false

→

←

Loop condition is false. Execution continues on line 1961

→

1959

OrList = pairWiseOr(OrList);

1960

}

1961

Cmp = Builder.CreateICmpNE(OrList[0], ConstantInt::get(Diff->getType(), 0));

←

Called C++ object pointer is uninitialized

1962

}

1963

1964

return Cmp;

1965

}

1966

1967

void MemCmpExpansion::emitLoadCompareBlockMultipleLoads(

1968

unsigned Index, unsigned Size, unsigned &NumBytesProcessed) {

1969

Value *Cmp = getCompareLoadPairs(Index, Size, NumBytesProcessed);

←

Calling 'MemCmpExpansion::getCompareLoadPairs'

→

1970

1971

BasicBlock *NextBB = (Index == (LoadCmpBlocks.size() - 1))

1972

? EndBlock

1973

: LoadCmpBlocks[Index + 1];

1974

// Early exit branch if difference found to ResultBlock. Otherwise,

1975

// continue to next LoadCmpBlock or EndBlock.

1976

BranchInst *CmpBr = BranchInst::Create(ResBlock.BB, NextBB, Cmp);

1977

Builder.Insert(CmpBr);

1978

1979

// Add a phi edge for the last LoadCmpBlock to Endblock with a value of 0

1980

// since early exit to ResultBlock was not taken (no difference was found in

1981

// any of the bytes).

1982

if (Index == LoadCmpBlocks.size() - 1) {

1983

Value *Zero = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 0);

1984

PhiRes->addIncoming(Zero, LoadCmpBlocks[Index]);

1985

}

1986

}

1987

1988

// This function creates the IR intructions for loading and comparing using the

1989

// given LoadSize. It loads the number of bytes specified by LoadSize from each

1990

// source of the memcmp parameters. It then does a subtract to see if there was

1991

// a difference in the loaded values. If a difference is found, it branches

1992

// with an early exit to the ResultBlock for calculating which source was

1993

// larger. Otherwise, it falls through to the either the next LoadCmpBlock or

1994

// the EndBlock if this is the last LoadCmpBlock. Loading 1 byte is handled with

1995

// a special case through emitLoadCompareByteBlock. The special handling can

1996

// simply subtract the loaded values and add it to the result phi node.

1997

void MemCmpExpansion::emitLoadCompareBlock(unsigned Index, unsigned LoadSize,

1998

unsigned GEPIndex) {

1999

if (LoadSize == 1) {

2000

MemCmpExpansion::emitLoadCompareByteBlock(Index, GEPIndex);

2001

return;

2002

}

2003

2004

Type *LoadSizeType = IntegerType::get(CI->getContext(), LoadSize * 8);

2005

Type *MaxLoadType = IntegerType::get(CI->getContext(), MaxLoadSize * 8);

2006

2007

2008

Value *Source1 = CI->getArgOperand(0);

2009

Value *Source2 = CI->getArgOperand(1);

2010

2011

Builder.SetInsertPoint(LoadCmpBlocks[Index]);

2012

// Cast source to LoadSizeType*.

2013

if (Source1->getType() != LoadSizeType)

2014

Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());

2015

if (Source2->getType() != LoadSizeType)

2016

Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());

2017

2018

// Get the base address using the GEPIndex.

2019

if (GEPIndex != 0) {

2020

Source1 = Builder.CreateGEP(LoadSizeType, Source1,

2021

ConstantInt::get(LoadSizeType, GEPIndex));

2022

Source2 = Builder.CreateGEP(LoadSizeType, Source2,

2023

ConstantInt::get(LoadSizeType, GEPIndex));

2024

}

2025

2026

// Load LoadSizeType from the base address.

2027

Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);

2028

Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);

2029

2030

if (DL.isLittleEndian()) {

2031

Function *Bswap = Intrinsic::getDeclaration(CI->getModule(),

2032

Intrinsic::bswap, LoadSizeType);

2033

LoadSrc1 = Builder.CreateCall(Bswap, LoadSrc1);

2034

LoadSrc2 = Builder.CreateCall(Bswap, LoadSrc2);

2035

}

2036

2037

if (LoadSizeType != MaxLoadType) {

2038

LoadSrc1 = Builder.CreateZExt(LoadSrc1, MaxLoadType);

2039

LoadSrc2 = Builder.CreateZExt(LoadSrc2, MaxLoadType);

2040

}

2041

2042

// Add the loaded values to the phi nodes for calculating memcmp result only

2043

// if result is not used in a zero equality.

2044

if (!IsUsedForZeroCmp) {

2045

ResBlock.PhiSrc1->addIncoming(LoadSrc1, LoadCmpBlocks[Index]);

2046

ResBlock.PhiSrc2->addIncoming(LoadSrc2, LoadCmpBlocks[Index]);

2047

}

2048

2049

Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, LoadSrc1, LoadSrc2);

2050

BasicBlock *NextBB = (Index == (LoadCmpBlocks.size() - 1))

2051

? EndBlock

2052

: LoadCmpBlocks[Index + 1];

2053

// Early exit branch if difference found to ResultBlock. Otherwise, continue

2054

// to next LoadCmpBlock or EndBlock.

2055

BranchInst *CmpBr = BranchInst::Create(NextBB, ResBlock.BB, Cmp);

2056

Builder.Insert(CmpBr);

2057

2058

// Add a phi edge for the last LoadCmpBlock to Endblock with a value of 0

2059

// since early exit to ResultBlock was not taken (no difference was found in

2060

// any of the bytes).

2061

if (Index == LoadCmpBlocks.size() - 1) {

2062

Value *Zero = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 0);

2063

PhiRes->addIncoming(Zero, LoadCmpBlocks[Index]);

2064

}

2065

}

2066

2067

// This function populates the ResultBlock with a sequence to calculate the

2068

// memcmp result. It compares the two loaded source values and returns -1 if

2069

// src1 < src2 and 1 if src1 > src2.

2070

void MemCmpExpansion::emitMemCmpResultBlock() {

2071

// Special case: if memcmp result is used in a zero equality, result does not

2072

// need to be calculated and can simply return 1.

2073

if (IsUsedForZeroCmp) {

2074

BasicBlock::iterator InsertPt = ResBlock.BB->getFirstInsertionPt();

2075

Builder.SetInsertPoint(ResBlock.BB, InsertPt);

2076

Value *Res = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 1);

2077

PhiRes->addIncoming(Res, ResBlock.BB);

2078

BranchInst *NewBr = BranchInst::Create(EndBlock);

2079

Builder.Insert(NewBr);

2080

return;

2081

}

2082

BasicBlock::iterator InsertPt = ResBlock.BB->getFirstInsertionPt();

2083

Builder.SetInsertPoint(ResBlock.BB, InsertPt);

2084

2085

Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_ULT, ResBlock.PhiSrc1,

2086

ResBlock.PhiSrc2);

2087

2088

Value *Res =

2089

Builder.CreateSelect(Cmp, ConstantInt::get(Builder.getInt32Ty(), -1),

2090

ConstantInt::get(Builder.getInt32Ty(), 1));

2091

2092

BranchInst *NewBr = BranchInst::Create(EndBlock);

2093

Builder.Insert(NewBr);

2094

PhiRes->addIncoming(Res, ResBlock.BB);

2095

}

2096

2097

unsigned MemCmpExpansion::calculateNumBlocks(unsigned Size) {

2098

unsigned NumBlocks = 0;

2099

bool HaveOneByteLoad = false;

2100

unsigned RemainingSize = Size;

2101

unsigned LoadSize = MaxLoadSize;

2102

while (RemainingSize) {

2103

if (LoadSize == 1)

2104

HaveOneByteLoad = true;

2105

NumBlocks += RemainingSize / LoadSize;

2106

RemainingSize = RemainingSize % LoadSize;

2107

LoadSize = LoadSize / 2;

2108

}

2109

NumBlocksNonOneByte = HaveOneByteLoad ? (NumBlocks - 1) : NumBlocks;

2110

2111

if (IsUsedForZeroCmp)

2112

NumBlocks = NumBlocks / NumLoadsPerBlock +

2113

(NumBlocks % NumLoadsPerBlock != 0 ? 1 : 0);

2114

2115

return NumBlocks;

2116

}

2117

2118

void MemCmpExpansion::setupResultBlockPHINodes() {

2119

Type *MaxLoadType = IntegerType::get(CI->getContext(), MaxLoadSize * 8);

2120

Builder.SetInsertPoint(ResBlock.BB);

2121

ResBlock.PhiSrc1 =

2122

Builder.CreatePHI(MaxLoadType, NumBlocksNonOneByte, "phi.src1");

2123

ResBlock.PhiSrc2 =

2124

Builder.CreatePHI(MaxLoadType, NumBlocksNonOneByte, "phi.src2");

2125

}

2126

2127

void MemCmpExpansion::setupEndBlockPHINodes() {

2128

Builder.SetInsertPoint(&EndBlock->front());

2129

PhiRes = Builder.CreatePHI(Type::getInt32Ty(CI->getContext()), 2, "phi.res");

2130

}

2131

2132

Value *MemCmpExpansion::getMemCmpExpansionZeroCase(unsigned Size) {

2133

unsigned NumBytesProcessed = 0;

2134

// This loop populates each of the LoadCmpBlocks with the IR sequence to

2135

// handle multiple loads per block.

2136

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

Assuming the condition is true

→

←

Loop condition is true. Entering loop body

→

2137

emitLoadCompareBlockMultipleLoads(i, Size, NumBytesProcessed);

←

Calling 'MemCmpExpansion::emitLoadCompareBlockMultipleLoads'

→

2138

2139

emitMemCmpResultBlock();

2140

return PhiRes;

2141

}

2142

2143

/// A memcmp expansion that compares equality with 0 and only has one block of

2144

/// load and compare can bypass the compare, branch, and phi IR that is required

2145

/// in the general case.

2146

Value *MemCmpExpansion::getMemCmpEqZeroOneBlock(unsigned Size) {

2147

unsigned NumBytesProcessed = 0;

2148

Value *Cmp = getCompareLoadPairs(0, Size, NumBytesProcessed);

2149

return Builder.CreateZExt(Cmp, Type::getInt32Ty(CI->getContext()));

2150

}

2151

2152

/// A memcmp expansion that only has one block of load and compare can bypass

2153

/// the compare, branch, and phi IR that is required in the general case.

2154

Value *MemCmpExpansion::getMemCmpOneBlock(unsigned Size) {

2155

assert(NumLoadsPerBlock == 1 && "Only handles one load pair per block")((NumLoadsPerBlock == 1 && "Only handles one load pair per block"
) ? static_cast<void> (0) : __assert_fail ("NumLoadsPerBlock == 1 && \"Only handles one load pair per block\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 2155, __PRETTY_FUNCTION__));

2156

2157

Type *LoadSizeType = IntegerType::get(CI->getContext(), Size * 8);

2158

Value *Source1 = CI->getArgOperand(0);

2159

Value *Source2 = CI->getArgOperand(1);

2160

2161

// Cast source to LoadSizeType*.

2162

if (Source1->getType() != LoadSizeType)

2163

Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());

2164

if (Source2->getType() != LoadSizeType)

2165

Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());

2166

2167

// Load LoadSizeType from the base address.

2168

Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);

2169

Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);

2170

2171

if (DL.isLittleEndian() && Size != 1) {

2172

Function *Bswap = Intrinsic::getDeclaration(CI->getModule(),

2173

Intrinsic::bswap, LoadSizeType);

2174

LoadSrc1 = Builder.CreateCall(Bswap, LoadSrc1);

2175

LoadSrc2 = Builder.CreateCall(Bswap, LoadSrc2);

2176

}

2177

2178

if (Size < 4) {

2179

// The i8 and i16 cases don't need compares. We zext the loaded values and

2180

// subtract them to get the suitable negative, zero, or positive i32 result.

2181

LoadSrc1 = Builder.CreateZExt(LoadSrc1, Builder.getInt32Ty());

2182

LoadSrc2 = Builder.CreateZExt(LoadSrc2, Builder.getInt32Ty());

2183

return Builder.CreateSub(LoadSrc1, LoadSrc2);

2184

}

2185

2186

// The result of memcmp is negative, zero, or positive, so produce that by

2187

// subtracting 2 extended compare bits: sub (ugt, ult).

2188

// If a target prefers to use selects to get -1/0/1, they should be able

2189

// to transform this later. The inverse transform (going from selects to math)

2190

// may not be possible in the DAG because the selects got converted into

2191

// branches before we got there.

2192

Value *CmpUGT = Builder.CreateICmpUGT(LoadSrc1, LoadSrc2);

2193

Value *CmpULT = Builder.CreateICmpULT(LoadSrc1, LoadSrc2);

2194

Value *ZextUGT = Builder.CreateZExt(CmpUGT, Builder.getInt32Ty());

2195

Value *ZextULT = Builder.CreateZExt(CmpULT, Builder.getInt32Ty());

2196

return Builder.CreateSub(ZextUGT, ZextULT);

2197

}

2198

2199

// This function expands the memcmp call into an inline expansion and returns

2200

// the memcmp result.

2201

Value *MemCmpExpansion::getMemCmpExpansion(uint64_t Size) {

2202

if (IsUsedForZeroCmp)

2203

return NumBlocks == 1 ? getMemCmpEqZeroOneBlock(Size) :

2204

getMemCmpExpansionZeroCase(Size);

2205

2206

// TODO: Handle more than one load pair per block in getMemCmpOneBlock().

2207

if (NumBlocks == 1 && NumLoadsPerBlock == 1)

2208

return getMemCmpOneBlock(Size);

2209

2210

// This loop calls emitLoadCompareBlock for comparing Size bytes of the two

2211

// memcmp sources. It starts with loading using the maximum load size set by

2212

// the target. It processes any remaining bytes using a load size which is the

2213

// next smallest power of 2.

2214

unsigned LoadSize = MaxLoadSize;

2215

unsigned NumBytesToBeProcessed = Size;

2216

unsigned Index = 0;

2217

while (NumBytesToBeProcessed) {

2218

// Calculate how many blocks we can create with the current load size.

2219

unsigned NumBlocks = NumBytesToBeProcessed / LoadSize;

2220

unsigned GEPIndex = (Size - NumBytesToBeProcessed) / LoadSize;

2221

NumBytesToBeProcessed = NumBytesToBeProcessed % LoadSize;

2222

2223

// For each NumBlocks, populate the instruction sequence for loading and

2224

// comparing LoadSize bytes.

2225

while (NumBlocks--) {

2226

emitLoadCompareBlock(Index, LoadSize, GEPIndex);

2227

Index++;

2228

GEPIndex++;

2229

}

2230

// Get the next LoadSize to use.

2231

LoadSize = LoadSize / 2;

2232

}

2233

2234

emitMemCmpResultBlock();

2235

return PhiRes;

2236

}

2237

2238

// This function checks to see if an expansion of memcmp can be generated.

2239

// It checks for constant compare size that is less than the max inline size.

2240

// If an expansion cannot occur, returns false to leave as a library call.

2241

// Otherwise, the library call is replaced with a new IR instruction sequence.

2242

/// We want to transform:

2243

/// %call = call signext i32 @memcmp(i8* %0, i8* %1, i64 15)

2244

/// To:

2245

/// loadbb:

2246

/// %0 = bitcast i32* %buffer2 to i8*

2247

/// %1 = bitcast i32* %buffer1 to i8*

2248

/// %2 = bitcast i8* %1 to i64*

2249

/// %3 = bitcast i8* %0 to i64*

2250

/// %4 = load i64, i64* %2

2251

/// %5 = load i64, i64* %3

2252

/// %6 = call i64 @llvm.bswap.i64(i64 %4)

2253

/// %7 = call i64 @llvm.bswap.i64(i64 %5)

2254

/// %8 = sub i64 %6, %7

2255

/// %9 = icmp ne i64 %8, 0

2256

/// br i1 %9, label %res_block, label %loadbb1

2257

/// res_block: ; preds = %loadbb2,

2258

/// %loadbb1, %loadbb

2259

/// %phi.src1 = phi i64 [ %6, %loadbb ], [ %22, %loadbb1 ], [ %36, %loadbb2 ]

2260

/// %phi.src2 = phi i64 [ %7, %loadbb ], [ %23, %loadbb1 ], [ %37, %loadbb2 ]

2261

/// %10 = icmp ult i64 %phi.src1, %phi.src2

2262

/// %11 = select i1 %10, i32 -1, i32 1

2263

/// br label %endblock

2264

/// loadbb1: ; preds = %loadbb

2265

/// %12 = bitcast i32* %buffer2 to i8*

2266

/// %13 = bitcast i32* %buffer1 to i8*

2267

/// %14 = bitcast i8* %13 to i32*

2268

/// %15 = bitcast i8* %12 to i32*

2269

/// %16 = getelementptr i32, i32* %14, i32 2

2270

/// %17 = getelementptr i32, i32* %15, i32 2

2271

/// %18 = load i32, i32* %16

2272

/// %19 = load i32, i32* %17

2273

/// %20 = call i32 @llvm.bswap.i32(i32 %18)

2274

/// %21 = call i32 @llvm.bswap.i32(i32 %19)

2275

/// %22 = zext i32 %20 to i64

2276

/// %23 = zext i32 %21 to i64

2277

/// %24 = sub i64 %22, %23

2278

/// %25 = icmp ne i64 %24, 0

2279

/// br i1 %25, label %res_block, label %loadbb2

2280

/// loadbb2: ; preds = %loadbb1

2281

/// %26 = bitcast i32* %buffer2 to i8*

2282

/// %27 = bitcast i32* %buffer1 to i8*

2283

/// %28 = bitcast i8* %27 to i16*

2284

/// %29 = bitcast i8* %26 to i16*

2285

/// %30 = getelementptr i16, i16* %28, i16 6

2286

/// %31 = getelementptr i16, i16* %29, i16 6

2287

/// %32 = load i16, i16* %30

2288

/// %33 = load i16, i16* %31

2289

/// %34 = call i16 @llvm.bswap.i16(i16 %32)

2290

/// %35 = call i16 @llvm.bswap.i16(i16 %33)

2291

/// %36 = zext i16 %34 to i64

2292

/// %37 = zext i16 %35 to i64

2293

/// %38 = sub i64 %36, %37

2294

/// %39 = icmp ne i64 %38, 0

2295

/// br i1 %39, label %res_block, label %loadbb3

2296

/// loadbb3: ; preds = %loadbb2

2297

/// %40 = bitcast i32* %buffer2 to i8*

2298

/// %41 = bitcast i32* %buffer1 to i8*

2299

/// %42 = getelementptr i8, i8* %41, i8 14

2300

/// %43 = getelementptr i8, i8* %40, i8 14

2301

/// %44 = load i8, i8* %42

2302

/// %45 = load i8, i8* %43

2303

/// %46 = zext i8 %44 to i32

2304

/// %47 = zext i8 %45 to i32

2305

/// %48 = sub i32 %46, %47

2306

/// br label %endblock

2307

/// endblock: ; preds = %res_block,

2308

/// %loadbb3

2309

/// %phi.res = phi i32 [ %48, %loadbb3 ], [ %11, %res_block ]

2310

/// ret i32 %phi.res

2311

static bool expandMemCmp(CallInst *CI, const TargetTransformInfo *TTI,

2312

const TargetLowering *TLI, const DataLayout *DL) {

2313

NumMemCmpCalls++;

2314

2315

// TTI call to check if target would like to expand memcmp. Also, get the

2316

// MaxLoadSize.

2317

unsigned MaxLoadSize;

2318

if (!TTI->enableMemCmpExpansion(MaxLoadSize))

2319

return false;

2320

2321

// Early exit from expansion if -Oz.

2322

if (CI->getFunction()->optForMinSize())

2323

return false;

2324

2325

// Early exit from expansion if size is not a constant.

2326

ConstantInt *SizeCast = dyn_cast<ConstantInt>(CI->getArgOperand(2));

2327

if (!SizeCast) {

2328

NumMemCmpNotConstant++;

2329

return false;

2330

}

2331

2332

// Scale the max size down if the target can load more bytes than we need.

2333

uint64_t SizeVal = SizeCast->getZExtValue();

2334

if (MaxLoadSize > SizeVal)

2335

MaxLoadSize = 1 << SizeCast->getValue().logBase2();

2336

2337

// Calculate how many load pairs are needed for the constant size.

2338

unsigned NumLoads = 0;

2339

unsigned RemainingSize = SizeVal;

2340

unsigned LoadSize = MaxLoadSize;

2341

while (RemainingSize) {

2342

NumLoads += RemainingSize / LoadSize;

2343

RemainingSize = RemainingSize % LoadSize;

2344

LoadSize = LoadSize / 2;

2345

}

2346

2347

// Don't expand if this will require more loads than desired by the target.

2348

if (NumLoads > TLI->getMaxExpandSizeMemcmp(CI->getFunction()->optForSize())) {

2349

NumMemCmpGreaterThanMax++;

2350

return false;

2351

}

2352

2353

NumMemCmpInlined++;

2354

2355

// MemCmpHelper object creates and sets up basic blocks required for

2356

// expanding memcmp with size SizeVal.

2357

unsigned NumLoadsPerBlock = MemCmpNumLoadsPerBlock;

2358

MemCmpExpansion MemCmpHelper(CI, SizeVal, MaxLoadSize, NumLoadsPerBlock, *DL);

2359

2360

Value *Res = MemCmpHelper.getMemCmpExpansion(SizeVal);

2361

2362

// Replace call with result of expansion and erase call.

2363

CI->replaceAllUsesWith(Res);

2364

CI->eraseFromParent();

2365

2366

return true;

2367

}

2368

2369

bool CodeGenPrepare::optimizeCallInst(CallInst *CI, bool &ModifiedDT) {

2370

BasicBlock *BB = CI->getParent();

2371

2372

// Lower inline assembly if we can.

2373

// If we found an inline asm expession, and if the target knows how to

2374

// lower it to normal LLVM code, do so now.

2375

if (TLI && isa<InlineAsm>(CI->getCalledValue())) {

2376

if (TLI->ExpandInlineAsm(CI)) {

2377

// Avoid invalidating the iterator.

2378

CurInstIterator = BB->begin();

2379

// Avoid processing instructions out of order, which could cause

2380

// reuse before a value is defined.

2381

SunkAddrs.clear();

2382

return true;

2383

}

2384

// Sink address computing for memory operands into the block.

2385

if (optimizeInlineAsmInst(CI))

2386

return true;

2387

}

2388

2389

// Align the pointer arguments to this call if the target thinks it's a good

2390

// idea

2391

unsigned MinSize, PrefAlign;

2392

if (TLI && TLI->shouldAlignPointerArgs(CI, MinSize, PrefAlign)) {

2393

for (auto &Arg : CI->arg_operands()) {

2394

// We want to align both objects whose address is used directly and

2395

// objects whose address is used in casts and GEPs, though it only makes

2396

// sense for GEPs if the offset is a multiple of the desired alignment and

2397

// if size - offset meets the size threshold.

2398

if (!Arg->getType()->isPointerTy())

2399

continue;

2400

APInt Offset(DL->getPointerSizeInBits(

2401

cast<PointerType>(Arg->getType())->getAddressSpace()),

2402

0);

2403

Value *Val = Arg->stripAndAccumulateInBoundsConstantOffsets(*DL, Offset);

2404

uint64_t Offset2 = Offset.getLimitedValue();

2405

if ((Offset2 & (PrefAlign-1)) != 0)

2406

continue;

2407

AllocaInst *AI;

2408

if ((AI = dyn_cast<AllocaInst>(Val)) && AI->getAlignment() < PrefAlign &&

2409

DL->getTypeAllocSize(AI->getAllocatedType()) >= MinSize + Offset2)

2410

AI->setAlignment(PrefAlign);

2411

// Global variables can only be aligned if they are defined in this

2412

// object (i.e. they are uniquely initialized in this object), and

2413

// over-aligning global variables that have an explicit section is

2414

// forbidden.

2415

GlobalVariable *GV;

2416

if ((GV = dyn_cast<GlobalVariable>(Val)) && GV->canIncreaseAlignment() &&

2417

GV->getPointerAlignment(*DL) < PrefAlign &&

2418

DL->getTypeAllocSize(GV->getValueType()) >=

2419

MinSize + Offset2)

2420

GV->setAlignment(PrefAlign);

2421

}

2422

// If this is a memcpy (or similar) then we may be able to improve the

2423

// alignment

2424

if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(CI)) {

2425

unsigned Align = getKnownAlignment(MI->getDest(), *DL);

2426

if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI))

2427

Align = std::min(Align, getKnownAlignment(MTI->getSource(), *DL));

2428

if (Align > MI->getAlignment())

2429

MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), Align));

2430

}

2431

}

2432

2433

// If we have a cold call site, try to sink addressing computation into the

2434

// cold block. This interacts with our handling for loads and stores to

2435

// ensure that we can fold all uses of a potential addressing computation

2436

// into their uses. TODO: generalize this to work over profiling data

2437

if (!OptSize && CI->hasFnAttr(Attribute::Cold))

2438

for (auto &Arg : CI->arg_operands()) {

2439

if (!Arg->getType()->isPointerTy())

2440

continue;

2441

unsigned AS = Arg->getType()->getPointerAddressSpace();

2442

return optimizeMemoryInst(CI, Arg, Arg->getType(), AS);

2443

}

2444

2445

IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);

2446

if (II) {

2447

switch (II->getIntrinsicID()) {

2448

default: break;

2449

case Intrinsic::objectsize: {

2450

// Lower all uses of llvm.objectsize.*

2451

ConstantInt *RetVal =

2452

lowerObjectSizeCall(II, *DL, TLInfo, /*MustSucceed=*/true);

2453

// Substituting this can cause recursive simplifications, which can

2454

// invalidate our iterator. Use a WeakTrackingVH to hold onto it in case

2455

// this

2456

// happens.

2457

Value *CurValue = &*CurInstIterator;

2458

WeakTrackingVH IterHandle(CurValue);

2459

2460

replaceAndRecursivelySimplify(CI, RetVal, TLInfo, nullptr);

2461

2462

// If the iterator instruction was recursively deleted, start over at the

2463

// start of the block.

2464

if (IterHandle != CurValue) {

2465

CurInstIterator = BB->begin();

2466

SunkAddrs.clear();

2467

}

2468

return true;

2469

}

2470

case Intrinsic::aarch64_stlxr:

2471

case Intrinsic::aarch64_stxr: {

2472

ZExtInst *ExtVal = dyn_cast<ZExtInst>(CI->getArgOperand(0));

2473

if (!ExtVal || !ExtVal->hasOneUse() ||

2474

ExtVal->getParent() == CI->getParent())

2475

return false;

2476

// Sink a zext feeding stlxr/stxr before it, so it can be folded into it.

2477

ExtVal->moveBefore(CI);

2478

// Mark this instruction as "inserted by CGP", so that other

2479

// optimizations don't touch it.

2480

InsertedInsts.insert(ExtVal);

2481

return true;

2482

}

2483

case Intrinsic::invariant_group_barrier:

2484

II->replaceAllUsesWith(II->getArgOperand(0));

2485

II->eraseFromParent();

2486

return true;

2487

2488

case Intrinsic::cttz:

2489

case Intrinsic::ctlz:

2490

// If counting zeros is expensive, try to avoid it.

2491

return despeculateCountZeros(II, TLI, DL, ModifiedDT);

2492

}

2493

2494

if (TLI) {

2495

SmallVector<Value*, 2> PtrOps;

2496

Type *AccessTy;

2497

if (TLI->getAddrModeArguments(II, PtrOps, AccessTy))

2498

while (!PtrOps.empty()) {

2499

Value *PtrVal = PtrOps.pop_back_val();

2500

unsigned AS = PtrVal->getType()->getPointerAddressSpace();

2501

if (optimizeMemoryInst(II, PtrVal, AccessTy, AS))

2502

return true;

2503

}

2504

}

2505

}

2506

2507

// From here on out we're working with named functions.

2508

if (!CI->getCalledFunction()) return false;

2509

2510

// Lower all default uses of _chk calls. This is very similar

2511

// to what InstCombineCalls does, but here we are only lowering calls

2512

// to fortified library functions (e.g. __memcpy_chk) that have the default

2513

// "don't know" as the objectsize. Anything else should be left alone.

2514

FortifiedLibCallSimplifier Simplifier(TLInfo, true);

2515

if (Value *V = Simplifier.optimizeCall(CI)) {

2516

CI->replaceAllUsesWith(V);

2517

CI->eraseFromParent();

2518

return true;

2519

}

2520

2521

LibFunc Func;

2522

if (TLInfo->getLibFunc(ImmutableCallSite(CI), Func) &&

2523

Func == LibFunc_memcmp && expandMemCmp(CI, TTI, TLI, DL)) {

2524

ModifiedDT = true;

2525

return true;

2526

}

2527

return false;

2528

}

2529

2530

/// Look for opportunities to duplicate return instructions to the predecessor

2531

/// to enable tail call optimizations. The case it is currently looking for is:

2532

/// @code

2533

/// bb0:

2534

/// %tmp0 = tail call i32 @f0()

2535

/// br label %return

2536

/// bb1:

2537

/// %tmp1 = tail call i32 @f1()

2538

/// br label %return

2539

/// bb2:

2540

/// %tmp2 = tail call i32 @f2()

2541

/// br label %return

2542

/// return:

2543

/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]

2544

/// ret i32 %retval

2545

/// @endcode

2546

///

2547

/// =>

2548

///

2549

/// @code

2550

/// bb0:

2551

/// %tmp0 = tail call i32 @f0()

2552

/// ret i32 %tmp0

2553

/// bb1:

2554

/// %tmp1 = tail call i32 @f1()

2555

/// ret i32 %tmp1

2556

/// bb2:

2557

/// %tmp2 = tail call i32 @f2()

2558

/// ret i32 %tmp2

2559

/// @endcode

2560

bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB) {

2561

if (!TLI)

2562

return false;

2563

2564

ReturnInst *RetI = dyn_cast<ReturnInst>(BB->getTerminator());

2565

if (!RetI)

2566

return false;

2567

2568

PHINode *PN = nullptr;

2569

BitCastInst *BCI = nullptr;

2570

Value *V = RetI->getReturnValue();

2571

if (V) {

2572

BCI = dyn_cast<BitCastInst>(V);

2573

if (BCI)

2574

V = BCI->getOperand(0);

2575

2576

PN = dyn_cast<PHINode>(V);

2577

if (!PN)

2578

return false;

2579

}

2580

2581

if (PN && PN->getParent() != BB)

2582

return false;

2583

2584

// Make sure there are no instructions between the PHI and return, or that the

2585

// return is the first instruction in the block.

2586

if (PN) {

2587

BasicBlock::iterator BI = BB->begin();

2588

do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));

2589

if (&*BI == BCI)

2590

// Also skip over the bitcast.

2591

++BI;

2592

if (&*BI != RetI)

2593

return false;

2594

} else {

2595

BasicBlock::iterator BI = BB->begin();

2596

while (isa<DbgInfoIntrinsic>(BI)) ++BI;

2597

if (&*BI != RetI)

2598

return false;

2599

}

2600

2601

/// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail

2602

/// call.

2603

const Function *F = BB->getParent();

2604

SmallVector<CallInst*, 4> TailCalls;

2605

if (PN) {

2606

for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {

2607

CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));

2608

// Make sure the phi value is indeed produced by the tail call.

2609

if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&

2610

TLI->mayBeEmittedAsTailCall(CI) &&

2611

attributesPermitTailCall(F, CI, RetI, *TLI))

2612

TailCalls.push_back(CI);

2613

}

2614

} else {

2615

SmallPtrSet<BasicBlock*, 4> VisitedBBs;

2616

for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {

2617

if (!VisitedBBs.insert(*PI).second)

2618

continue;

2619

2620

BasicBlock::InstListType &InstList = (*PI)->getInstList();

2621

BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();

2622

BasicBlock::InstListType::reverse_iterator RE = InstList.rend();

2623

do { ++RI; } while (RI != RE && isa<DbgInfoIntrinsic>(&*RI));

2624

if (RI == RE)

2625

continue;

2626

2627

CallInst *CI = dyn_cast<CallInst>(&*RI);

2628

if (CI && CI->use_empty() && TLI->mayBeEmittedAsTailCall(CI) &&

2629

attributesPermitTailCall(F, CI, RetI, *TLI))

2630

TailCalls.push_back(CI);

2631

}

2632

}

2633

2634

bool Changed = false;

2635

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

2636

CallInst *CI = TailCalls[i];

2637

CallSite CS(CI);

2638

2639

// Conservatively require the attributes of the call to match those of the

2640

// return. Ignore noalias because it doesn't affect the call sequence.

2641

AttributeList CalleeAttrs = CS.getAttributes();

2642

if (AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)

2643

.removeAttribute(Attribute::NoAlias) !=

2644

AttrBuilder(CalleeAttrs, AttributeList::ReturnIndex)

2645

.removeAttribute(Attribute::NoAlias))

2646

continue;

2647

2648

// Make sure the call instruction is followed by an unconditional branch to

2649

// the return block.

2650

BasicBlock *CallBB = CI->getParent();

2651

BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());

2652

if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)

2653

continue;

2654

2655

// Duplicate the return into CallBB.

2656

(void)FoldReturnIntoUncondBranch(RetI, BB, CallBB);

2657

ModifiedDT = Changed = true;

2658

++NumRetsDup;

2659

}

2660

2661

// If we eliminated all predecessors of the block, delete the block now.

2662

if (Changed && !BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))

2663

BB->eraseFromParent();

2664

2665

return Changed;

2666

}

2667

2668

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

2669

// Memory Optimization

2670

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

2671

2672

namespace {

2673

2674

/// This is an extended version of TargetLowering::AddrMode

2675

/// which holds actual Value*'s for register values.

2676

struct ExtAddrMode : public TargetLowering::AddrMode {

2677

Value *BaseReg = nullptr;

2678

Value *ScaledReg = nullptr;

2679

Value *OriginalValue = nullptr;

2680

2681

enum FieldName {

2682

NoField = 0x00,

2683

BaseRegField = 0x01,

2684

BaseGVField = 0x02,

2685

BaseOffsField = 0x04,

2686

ScaledRegField = 0x08,

2687

ScaleField = 0x10,

2688

MultipleFields = 0xff

2689

};

2690

2691

ExtAddrMode() = default;

2692

2693

void print(raw_ostream &OS) const;

2694

void dump() const;

2695

2696

FieldName compare(const ExtAddrMode &other) {

2697

// First check that the types are the same on each field, as differing types

2698

// is something we can't cope with later on.

2699

if (BaseReg && other.BaseReg &&

2700

BaseReg->getType() != other.BaseReg->getType())

2701

return MultipleFields;

2702

if (BaseGV && other.BaseGV &&

2703

BaseGV->getType() != other.BaseGV->getType())

2704

return MultipleFields;

2705

if (ScaledReg && other.ScaledReg &&

2706

ScaledReg->getType() != other.ScaledReg->getType())

2707

return MultipleFields;

2708

2709

// Check each field to see if it differs.

2710

unsigned Result = NoField;

2711

if (BaseReg != other.BaseReg)

2712

Result |= BaseRegField;

2713

if (BaseGV != other.BaseGV)

2714

Result |= BaseGVField;

2715

if (BaseOffs != other.BaseOffs)

2716

Result |= BaseOffsField;

2717

if (ScaledReg != other.ScaledReg)

2718

Result |= ScaledRegField;

2719

// Don't count 0 as being a different scale, because that actually means

2720

// unscaled (which will already be counted by having no ScaledReg).

2721

if (Scale && other.Scale && Scale != other.Scale)

2722

Result |= ScaleField;

2723

2724

if (countPopulation(Result) > 1)

2725

return MultipleFields;

2726

else

2727

return static_cast<FieldName>(Result);

2728

}

2729

2730

// AddrModes with a base reg or gv where the reg/gv is just the original

2731

// value are trivial.

2732

bool isTrivial() {

2733

bool Trivial = (BaseGV && BaseGV == OriginalValue) ||

2734

(BaseReg && BaseReg == OriginalValue);

2735

// If the AddrMode is trivial it shouldn't have an offset or be scaled.

2736

if (Trivial) {

2737

assert(BaseOffs == 0)((BaseOffs == 0) ? static_cast<void> (0) : __assert_fail
("BaseOffs == 0", "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 2737, __PRETTY_FUNCTION__));

2738

assert(Scale == 0)((Scale == 0) ? static_cast<void> (0) : __assert_fail (
"Scale == 0", "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 2738, __PRETTY_FUNCTION__));

2739

}

2740

return Trivial;

2741

}

2742

};

2743

2744

} // end anonymous namespace

2745

2746

#ifndef NDEBUG

2747

static inline raw_ostream &operator<<(raw_ostream &OS, const ExtAddrMode &AM) {

2748

AM.print(OS);

2749

return OS;

2750

}

2751

#endif

2752

2753

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

2754

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

2755

bool NeedPlus = false;

2756

OS << "[";

2757

if (BaseGV) {

2758

OS << (NeedPlus ? " + " : "")

2759

<< "GV:";

2760

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

2761

NeedPlus = true;

2762

}

2763

2764

if (BaseOffs) {

2765

OS << (NeedPlus ? " + " : "")

2766

<< BaseOffs;

2767

NeedPlus = true;

2768

}

2769

2770

if (BaseReg) {

2771

OS << (NeedPlus ? " + " : "")

2772

<< "Base:";

2773

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

2774

NeedPlus = true;

2775

}

2776

if (Scale) {

2777

OS << (NeedPlus ? " + " : "")

2778

<< Scale << "*";

2779

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

2780

}

2781

2782

OS << ']';

2783

}

2784

2785

LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void ExtAddrMode::dump() const {

2786

print(dbgs());

2787

dbgs() << '\n';

2788

}

2789

#endif

2790

2791

namespace {

2792

2793

/// \brief This class provides transaction based operation on the IR.

2794

/// Every change made through this class is recorded in the internal state and

2795

/// can be undone (rollback) until commit is called.

2796

class TypePromotionTransaction {

2797

/// \brief This represents the common interface of the individual transaction.

2798

/// Each class implements the logic for doing one specific modification on

2799

/// the IR via the TypePromotionTransaction.

2800

class TypePromotionAction {

2801

protected:

2802

/// The Instruction modified.

2803

Instruction *Inst;

2804

2805

public:

2806

/// \brief Constructor of the action.

2807

/// The constructor performs the related action on the IR.

2808

TypePromotionAction(Instruction *Inst) : Inst(Inst) {}

2809

2810

virtual ~TypePromotionAction() = default;

2811

2812

/// \brief Undo the modification done by this action.

2813

/// When this method is called, the IR must be in the same state as it was

2814

/// before this action was applied.

2815

/// \pre Undoing the action works if and only if the IR is in the exact same

2816

/// state as it was directly after this action was applied.

2817

virtual void undo() = 0;

2818

2819

/// \brief Advocate every change made by this action.

2820

/// When the results on the IR of the action are to be kept, it is important

2821

/// to call this function, otherwise hidden information may be kept forever.

2822

virtual void commit() {

2823

// Nothing to be done, this action is not doing anything.

2824

}

2825

};

2826

2827

/// \brief Utility to remember the position of an instruction.

2828

class InsertionHandler {

2829

/// Position of an instruction.

2830

/// Either an instruction:

2831

/// - Is the first in a basic block: BB is used.

2832

/// - Has a previous instructon: PrevInst is used.

2833

union {

2834

Instruction *PrevInst;

2835

BasicBlock *BB;

2836

} Point;

2837

2838

/// Remember whether or not the instruction had a previous instruction.

2839

bool HasPrevInstruction;

2840

2841

public:

2842

/// \brief Record the position of \p Inst.

2843

InsertionHandler(Instruction *Inst) {

2844

BasicBlock::iterator It = Inst->getIterator();

2845

HasPrevInstruction = (It != (Inst->getParent()->begin()));

2846

if (HasPrevInstruction)

2847

Point.PrevInst = &*--It;

2848

else

2849

Point.BB = Inst->getParent();

2850

}

2851

2852

/// \brief Insert \p Inst at the recorded position.

2853

void insert(Instruction *Inst) {

2854

if (HasPrevInstruction) {

2855

if (Inst->getParent())

2856

Inst->removeFromParent();

2857

Inst->insertAfter(Point.PrevInst);

2858

} else {

2859

Instruction *Position = &*Point.BB->getFirstInsertionPt();

2860

if (Inst->getParent())

2861

Inst->moveBefore(Position);

2862

else

2863

Inst->insertBefore(Position);

2864

}

2865

}

2866

};

2867

2868

/// \brief Move an instruction before another.

2869

class InstructionMoveBefore : public TypePromotionAction {

2870

/// Original position of the instruction.

2871

InsertionHandler Position;

2872

2873

public:

2874

/// \brief Move \p Inst before \p Before.

2875

InstructionMoveBefore(Instruction *Inst, Instruction *Before)

2876

: TypePromotionAction(Inst), Position(Inst) {

2877

DEBUG(dbgs() << "Do: move: " << *Inst << "\nbefore: " << *Before << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: move: " << *
Inst << "\nbefore: " << *Before << "\n"; } }
while (false);

2878

Inst->moveBefore(Before);

2879

}

2880

2881

/// \brief Move the instruction back to its original position.

2882

void undo() override {

2883

DEBUG(dbgs() << "Undo: moveBefore: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: moveBefore: " <<
*Inst << "\n"; } } while (false);

2884

Position.insert(Inst);

2885

}

2886

};

2887

2888

/// \brief Set the operand of an instruction with a new value.

2889

class OperandSetter : public TypePromotionAction {

2890

/// Original operand of the instruction.

2891

Value *Origin;

2892

2893

/// Index of the modified instruction.

2894

unsigned Idx;

2895

2896

public:

2897

/// \brief Set \p Idx operand of \p Inst with \p NewVal.

2898

OperandSetter(Instruction *Inst, unsigned Idx, Value *NewVal)

2899

: TypePromotionAction(Inst), Idx(Idx) {

2900

DEBUG(dbgs() << "Do: setOperand: " << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)

2901

<< "for:" << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false)

2902

<< "with:" << *NewVal << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: setOperand: " <<
Idx << "\n" << "for:" << *Inst << "\n"
<< "with:" << *NewVal << "\n"; } } while (
false);

2903

Origin = Inst->getOperand(Idx);

2904

Inst->setOperand(Idx, NewVal);

2905

}

2906

2907

/// \brief Restore the original value of the instruction.

2908

void undo() override {

2909

DEBUG(dbgs() << "Undo: setOperand:" << Idx << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)

2910

<< "for: " << *Inst << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false)

2911

<< "with: " << *Origin << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: setOperand:" <<
Idx << "\n" << "for: " << *Inst << "\n"
<< "with: " << *Origin << "\n"; } } while (
false);

2912

Inst->setOperand(Idx, Origin);

2913

}

2914

};

2915

2916

/// \brief Hide the operands of an instruction.

2917

/// Do as if this instruction was not using any of its operands.

2918

class OperandsHider : public TypePromotionAction {

2919

/// The list of original operands.

2920

SmallVector<Value *, 4> OriginalValues;

2921

2922

public:

2923

/// \brief Remove \p Inst from the uses of the operands of \p Inst.

2924

OperandsHider(Instruction *Inst) : TypePromotionAction(Inst) {

2925

DEBUG(dbgs() << "Do: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: OperandsHider: " <<
*Inst << "\n"; } } while (false);

2926

unsigned NumOpnds = Inst->getNumOperands();

2927

OriginalValues.reserve(NumOpnds);

2928

for (unsigned It = 0; It < NumOpnds; ++It) {

2929

// Save the current operand.

2930

Value *Val = Inst->getOperand(It);

2931

OriginalValues.push_back(Val);

2932

// Set a dummy one.

2933

// We could use OperandSetter here, but that would imply an overhead

2934

// that we are not willing to pay.

2935

Inst->setOperand(It, UndefValue::get(Val->getType()));

2936

}

2937

}

2938

2939

/// \brief Restore the original list of uses.

2940

void undo() override {

2941

DEBUG(dbgs() << "Undo: OperandsHider: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: OperandsHider: "
<< *Inst << "\n"; } } while (false);

2942

for (unsigned It = 0, EndIt = OriginalValues.size(); It != EndIt; ++It)

2943

Inst->setOperand(It, OriginalValues[It]);

2944

}

2945

};

2946

2947

/// \brief Build a truncate instruction.

2948

class TruncBuilder : public TypePromotionAction {

2949

Value *Val;

2950

2951

public:

2952

/// \brief Build a truncate instruction of \p Opnd producing a \p Ty

2953

/// result.

2954

/// trunc Opnd to Ty.

2955

TruncBuilder(Instruction *Opnd, Type *Ty) : TypePromotionAction(Opnd) {

2956

IRBuilder<> Builder(Opnd);

2957

Val = Builder.CreateTrunc(Opnd, Ty, "promoted");

2958

DEBUG(dbgs() << "Do: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: TruncBuilder: " <<
*Val << "\n"; } } while (false);

2959

}

2960

2961

/// \brief Get the built value.

2962

Value *getBuiltValue() { return Val; }

2963

2964

/// \brief Remove the built instruction.

2965

void undo() override {

2966

DEBUG(dbgs() << "Undo: TruncBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: TruncBuilder: " <<
*Val << "\n"; } } while (false);

2967

if (Instruction *IVal = dyn_cast<Instruction>(Val))

2968

IVal->eraseFromParent();

2969

}

2970

};

2971

2972

/// \brief Build a sign extension instruction.

2973

class SExtBuilder : public TypePromotionAction {

2974

Value *Val;

2975

2976

public:

2977

/// \brief Build a sign extension instruction of \p Opnd producing a \p Ty

2978

/// result.

2979

/// sext Opnd to Ty.

2980

SExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)

2981

: TypePromotionAction(InsertPt) {

2982

IRBuilder<> Builder(InsertPt);

2983

Val = Builder.CreateSExt(Opnd, Ty, "promoted");

2984

DEBUG(dbgs() << "Do: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: SExtBuilder: " <<
*Val << "\n"; } } while (false);

2985

}

2986

2987

/// \brief Get the built value.

2988

Value *getBuiltValue() { return Val; }

2989

2990

/// \brief Remove the built instruction.

2991

void undo() override {

2992

DEBUG(dbgs() << "Undo: SExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: SExtBuilder: " <<
*Val << "\n"; } } while (false);

2993

if (Instruction *IVal = dyn_cast<Instruction>(Val))

2994

IVal->eraseFromParent();

2995

}

2996

};

2997

2998

/// \brief Build a zero extension instruction.

2999

class ZExtBuilder : public TypePromotionAction {

3000

Value *Val;

3001

3002

public:

3003

/// \brief Build a zero extension instruction of \p Opnd producing a \p Ty

3004

/// result.

3005

/// zext Opnd to Ty.

3006

ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)

3007

: TypePromotionAction(InsertPt) {

3008

IRBuilder<> Builder(InsertPt);

3009

Val = Builder.CreateZExt(Opnd, Ty, "promoted");

3010

DEBUG(dbgs() << "Do: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: ZExtBuilder: " <<
*Val << "\n"; } } while (false);

3011

}

3012

3013

/// \brief Get the built value.

3014

Value *getBuiltValue() { return Val; }

3015

3016

/// \brief Remove the built instruction.

3017

void undo() override {

3018

DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Val << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: ZExtBuilder: " <<
*Val << "\n"; } } while (false);

3019

if (Instruction *IVal = dyn_cast<Instruction>(Val))

3020

IVal->eraseFromParent();

3021

}

3022

};

3023

3024

/// \brief Mutate an instruction to another type.

3025

class TypeMutator : public TypePromotionAction {

3026

/// Record the original type.

3027

Type *OrigTy;

3028

3029

public:

3030

/// \brief Mutate the type of \p Inst into \p NewTy.

3031

TypeMutator(Instruction *Inst, Type *NewTy)

3032

: TypePromotionAction(Inst), OrigTy(Inst->getType()) {

3033

DEBUG(dbgs() << "Do: MutateType: " << *Inst << " with " << *NewTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false)

3034

<< "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: MutateType: " <<
*Inst << " with " << *NewTy << "\n"; } } while
(false);

3035

Inst->mutateType(NewTy);

3036

}

3037

3038

/// \brief Mutate the instruction back to its original type.

3039

void undo() override {

3040

DEBUG(dbgs() << "Undo: MutateType: " << *Inst << " with " << *OrigTydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false)

3041

<< "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: MutateType: " <<
*Inst << " with " << *OrigTy << "\n"; } } while
(false);

3042

Inst->mutateType(OrigTy);

3043

}

3044

};

3045

3046

/// \brief Replace the uses of an instruction by another instruction.

3047

class UsesReplacer : public TypePromotionAction {

3048

/// Helper structure to keep track of the replaced uses.

3049

struct InstructionAndIdx {

3050

/// The instruction using the instruction.

3051

Instruction *Inst;

3052

3053

/// The index where this instruction is used for Inst.

3054

unsigned Idx;

3055

3056

InstructionAndIdx(Instruction *Inst, unsigned Idx)

3057

: Inst(Inst), Idx(Idx) {}

3058

};

3059

3060

/// Keep track of the original uses (pair Instruction, Index).

3061

SmallVector<InstructionAndIdx, 4> OriginalUses;

3062

3063

using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;

3064

3065

public:

3066

/// \brief Replace all the use of \p Inst by \p New.

3067

UsesReplacer(Instruction *Inst, Value *New) : TypePromotionAction(Inst) {

3068

DEBUG(dbgs() << "Do: UsersReplacer: " << *Inst << " with " << *Newdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false)

3069

<< "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: UsersReplacer: " <<
*Inst << " with " << *New << "\n"; } } while
(false);

3070

// Record the original uses.

3071

for (Use &U : Inst->uses()) {

3072

Instruction *UserI = cast<Instruction>(U.getUser());

3073

OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));

3074

}

3075

// Now, we can replace the uses.

3076

Inst->replaceAllUsesWith(New);

3077

}

3078

3079

/// \brief Reassign the original uses of Inst to Inst.

3080

void undo() override {

3081

DEBUG(dbgs() << "Undo: UsersReplacer: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: UsersReplacer: "
<< *Inst << "\n"; } } while (false);

3082

for (use_iterator UseIt = OriginalUses.begin(),

3083

EndIt = OriginalUses.end();

3084

UseIt != EndIt; ++UseIt) {

3085

UseIt->Inst->setOperand(UseIt->Idx, Inst);

3086

}

3087

}

3088

};

3089

3090

/// \brief Remove an instruction from the IR.

3091

class InstructionRemover : public TypePromotionAction {

3092

/// Original position of the instruction.

3093

InsertionHandler Inserter;

3094

3095

/// Helper structure to hide all the link to the instruction. In other

3096

/// words, this helps to do as if the instruction was removed.

3097

OperandsHider Hider;

3098

3099

/// Keep track of the uses replaced, if any.

3100

UsesReplacer *Replacer = nullptr;

3101

3102

/// Keep track of instructions removed.

3103

SetOfInstrs &RemovedInsts;

3104

3105

public:

3106

/// \brief Remove all reference of \p Inst and optinally replace all its

3107

/// uses with New.

3108

/// \p RemovedInsts Keep track of the instructions removed by this Action.

3109

/// \pre If !Inst->use_empty(), then New != nullptr

3110

InstructionRemover(Instruction *Inst, SetOfInstrs &RemovedInsts,

3111

Value *New = nullptr)

3112

: TypePromotionAction(Inst), Inserter(Inst), Hider(Inst),

3113

RemovedInsts(RemovedInsts) {

3114

if (New)

3115

Replacer = new UsesReplacer(Inst, New);

3116

DEBUG(dbgs() << "Do: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Do: InstructionRemover: "
<< *Inst << "\n"; } } while (false);

3117

RemovedInsts.insert(Inst);

3118

/// The instructions removed here will be freed after completing

3119

/// optimizeBlock() for all blocks as we need to keep track of the

3120

/// removed instructions during promotion.

3121

Inst->removeFromParent();

3122

}

3123

3124

~InstructionRemover() override { delete Replacer; }

3125

3126

/// \brief Resurrect the instruction and reassign it to the proper uses if

3127

/// new value was provided when build this action.

3128

void undo() override {

3129

DEBUG(dbgs() << "Undo: InstructionRemover: " << *Inst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Undo: InstructionRemover: "
<< *Inst << "\n"; } } while (false);

3130

Inserter.insert(Inst);

3131

if (Replacer)

3132

Replacer->undo();

3133

Hider.undo();

3134

RemovedInsts.erase(Inst);

3135

}

3136

};

3137

3138

public:

3139

/// Restoration point.

3140

/// The restoration point is a pointer to an action instead of an iterator

3141

/// because the iterator may be invalidated but not the pointer.

3142

using ConstRestorationPt = const TypePromotionAction *;

3143

3144

TypePromotionTransaction(SetOfInstrs &RemovedInsts)

3145

: RemovedInsts(RemovedInsts) {}

3146

3147

/// Advocate every changes made in that transaction.

3148

void commit();

3149

3150

/// Undo all the changes made after the given point.

3151

void rollback(ConstRestorationPt Point);

3152

3153

/// Get the current restoration point.

3154

ConstRestorationPt getRestorationPoint() const;

3155

3156

/// \name API for IR modification with state keeping to support rollback.

3157

/// @{

3158

/// Same as Instruction::setOperand.

3159

void setOperand(Instruction *Inst, unsigned Idx, Value *NewVal);

3160

3161

/// Same as Instruction::eraseFromParent.

3162

void eraseInstruction(Instruction *Inst, Value *NewVal = nullptr);

3163

3164

/// Same as Value::replaceAllUsesWith.

3165

void replaceAllUsesWith(Instruction *Inst, Value *New);

3166

3167

/// Same as Value::mutateType.

3168

void mutateType(Instruction *Inst, Type *NewTy);

3169

3170

/// Same as IRBuilder::createTrunc.

3171

Value *createTrunc(Instruction *Opnd, Type *Ty);

3172

3173

/// Same as IRBuilder::createSExt.

3174

Value *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);

3175

3176

/// Same as IRBuilder::createZExt.

3177

Value *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);

3178

3179

/// Same as Instruction::moveBefore.

3180

void moveBefore(Instruction *Inst, Instruction *Before);

3181

/// @}

3182

3183

private:

3184

/// The ordered list of actions made so far.

3185

SmallVector<std::unique_ptr<TypePromotionAction>, 16> Actions;

3186

3187

using CommitPt = SmallVectorImpl<std::unique_ptr<TypePromotionAction>>::iterator;

3188

3189

SetOfInstrs &RemovedInsts;

3190

};

3191

3192

} // end anonymous namespace

3193

3194

void TypePromotionTransaction::setOperand(Instruction *Inst, unsigned Idx,

3195

Value *NewVal) {

3196

Actions.push_back(llvm::make_unique<TypePromotionTransaction::OperandSetter>(

3197

Inst, Idx, NewVal));

3198

}

3199

3200

void TypePromotionTransaction::eraseInstruction(Instruction *Inst,

3201

Value *NewVal) {

3202

Actions.push_back(

3203

llvm::make_unique<TypePromotionTransaction::InstructionRemover>(

3204

Inst, RemovedInsts, NewVal));

3205

}

3206

3207

void TypePromotionTransaction::replaceAllUsesWith(Instruction *Inst,

3208

Value *New) {

3209

Actions.push_back(

3210

llvm::make_unique<TypePromotionTransaction::UsesReplacer>(Inst, New));

3211

}

3212

3213

void TypePromotionTransaction::mutateType(Instruction *Inst, Type *NewTy) {

3214

Actions.push_back(

3215

llvm::make_unique<TypePromotionTransaction::TypeMutator>(Inst, NewTy));

3216

}

3217

3218

Value *TypePromotionTransaction::createTrunc(Instruction *Opnd,

3219

Type *Ty) {

3220

std::unique_ptr<TruncBuilder> Ptr(new TruncBuilder(Opnd, Ty));

3221

Value *Val = Ptr->getBuiltValue();

3222

Actions.push_back(std::move(Ptr));

3223

return Val;

3224

}

3225

3226

Value *TypePromotionTransaction::createSExt(Instruction *Inst,

3227

Value *Opnd, Type *Ty) {

3228

std::unique_ptr<SExtBuilder> Ptr(new SExtBuilder(Inst, Opnd, Ty));

3229

Value *Val = Ptr->getBuiltValue();

3230

Actions.push_back(std::move(Ptr));

3231

return Val;

3232

}

3233

3234

Value *TypePromotionTransaction::createZExt(Instruction *Inst,

3235

Value *Opnd, Type *Ty) {

3236

std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));

3237

Value *Val = Ptr->getBuiltValue();

3238

Actions.push_back(std::move(Ptr));

3239

return Val;

3240

}

3241

3242

void TypePromotionTransaction::moveBefore(Instruction *Inst,

3243

Instruction *Before) {

3244

Actions.push_back(

3245

llvm::make_unique<TypePromotionTransaction::InstructionMoveBefore>(

3246

Inst, Before));

3247

}

3248

3249

TypePromotionTransaction::ConstRestorationPt

3250

TypePromotionTransaction::getRestorationPoint() const {

3251

return !Actions.empty() ? Actions.back().get() : nullptr;

3252

}

3253

3254

void TypePromotionTransaction::commit() {

3255

for (CommitPt It = Actions.begin(), EndIt = Actions.end(); It != EndIt;

3256

++It)

3257

(*It)->commit();

3258

Actions.clear();

3259

}

3260

3261

void TypePromotionTransaction::rollback(

3262

TypePromotionTransaction::ConstRestorationPt Point) {

3263

while (!Actions.empty() && Point != Actions.back().get()) {

3264

std::unique_ptr<TypePromotionAction> Curr = Actions.pop_back_val();

3265

Curr->undo();

3266

}

3267

}

3268

3269

namespace {

3270

3271

/// \brief A helper class for matching addressing modes.

3272

///

3273

/// This encapsulates the logic for matching the target-legal addressing modes.

3274

class AddressingModeMatcher {

3275

SmallVectorImpl<Instruction*> &AddrModeInsts;

3276

const TargetLowering &TLI;

3277

const TargetRegisterInfo &TRI;

3278

const DataLayout &DL;

3279

3280

/// AccessTy/MemoryInst - This is the type for the access (e.g. double) and

3281

/// the memory instruction that we're computing this address for.

3282

Type *AccessTy;

3283

unsigned AddrSpace;

3284

Instruction *MemoryInst;

3285

3286

/// This is the addressing mode that we're building up. This is

3287

/// part of the return value of this addressing mode matching stuff.

3288

ExtAddrMode &AddrMode;

3289

3290

/// The instructions inserted by other CodeGenPrepare optimizations.

3291

const SetOfInstrs &InsertedInsts;

3292

3293

/// A map from the instructions to their type before promotion.

3294

InstrToOrigTy &PromotedInsts;

3295

3296

/// The ongoing transaction where every action should be registered.

3297

TypePromotionTransaction &TPT;

3298

3299

/// This is set to true when we should not do profitability checks.

3300

/// When true, IsProfitableToFoldIntoAddressingMode always returns true.

3301

bool IgnoreProfitability;

3302

3303

AddressingModeMatcher(SmallVectorImpl<Instruction *> &AMI,

3304

const TargetLowering &TLI,

3305

const TargetRegisterInfo &TRI,

3306

Type *AT, unsigned AS,

3307

Instruction *MI, ExtAddrMode &AM,

3308

const SetOfInstrs &InsertedInsts,

3309

InstrToOrigTy &PromotedInsts,

3310

TypePromotionTransaction &TPT)

3311

: AddrModeInsts(AMI), TLI(TLI), TRI(TRI),

3312

DL(MI->getModule()->getDataLayout()), AccessTy(AT), AddrSpace(AS),

3313

MemoryInst(MI), AddrMode(AM), InsertedInsts(InsertedInsts),

3314

PromotedInsts(PromotedInsts), TPT(TPT) {

3315

IgnoreProfitability = false;

3316

}

3317

3318

public:

3319

/// Find the maximal addressing mode that a load/store of V can fold,

3320

/// give an access type of AccessTy. This returns a list of involved

3321

/// instructions in AddrModeInsts.

3322

/// \p InsertedInsts The instructions inserted by other CodeGenPrepare

3323

/// optimizations.

3324

/// \p PromotedInsts maps the instructions to their type before promotion.

3325

/// \p The ongoing transaction where every action should be registered.

3326

static ExtAddrMode Match(Value *V, Type *AccessTy, unsigned AS,

3327

Instruction *MemoryInst,

3328

SmallVectorImpl<Instruction*> &AddrModeInsts,

3329

const TargetLowering &TLI,

3330

const TargetRegisterInfo &TRI,

3331

const SetOfInstrs &InsertedInsts,

3332

InstrToOrigTy &PromotedInsts,

3333

TypePromotionTransaction &TPT) {

3334

ExtAddrMode Result;

3335

3336

bool Success = AddressingModeMatcher(AddrModeInsts, TLI, TRI,

3337

AccessTy, AS,

3338

MemoryInst, Result, InsertedInsts,

3339

PromotedInsts, TPT).matchAddr(V, 0);

3340

(void)Success; assert(Success && "Couldn't select *anything*?")((Success && "Couldn't select *anything*?") ? static_cast
<void> (0) : __assert_fail ("Success && \"Couldn't select *anything*?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 3340, __PRETTY_FUNCTION__));

3341

return Result;

3342

}

3343

3344

private:

3345

bool matchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);

3346

bool matchAddr(Value *V, unsigned Depth);

3347

bool matchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth,

3348

bool *MovedAway = nullptr);

3349

bool isProfitableToFoldIntoAddressingMode(Instruction *I,

3350

ExtAddrMode &AMBefore,

3351

ExtAddrMode &AMAfter);

3352

bool valueAlreadyLiveAtInst(Value *Val, Value *KnownLive1, Value *KnownLive2);

3353

bool isPromotionProfitable(unsigned NewCost, unsigned OldCost,

3354

Value *PromotedOperand) const;

3355

};

3356

3357

/// \brief A helper class for combining addressing modes.

3358

class AddressingModeCombiner {

3359

private:

3360

/// The addressing modes we've collected.

3361

SmallVector<ExtAddrMode, 16> AddrModes;

3362

3363

/// The field in which the AddrModes differ, when we have more than one.

3364

ExtAddrMode::FieldName DifferentField = ExtAddrMode::NoField;

3365

3366

/// Are the AddrModes that we have all just equal to their original values?

3367

bool AllAddrModesTrivial = true;

3368

3369

public:

3370

/// \brief Get the combined AddrMode

3371

const ExtAddrMode &getAddrMode() const {

3372

return AddrModes[0];

3373

}

3374

3375

/// \brief Add a new AddrMode if it's compatible with the AddrModes we already

3376

/// have.

3377

/// \return True iff we succeeded in doing so.

3378

bool addNewAddrMode(ExtAddrMode &NewAddrMode) {

3379

// Take note of if we have any non-trivial AddrModes, as we need to detect

3380

// when all AddrModes are trivial as then we would introduce a phi or select

3381

// which just duplicates what's already there.

3382

AllAddrModesTrivial = AllAddrModesTrivial && NewAddrMode.isTrivial();

3383

3384

// If this is the first addrmode then everything is fine.

3385

if (AddrModes.empty()) {

3386

AddrModes.emplace_back(NewAddrMode);

3387

return true;

3388

}

3389

3390

// Figure out how different this is from the other address modes, which we

3391

// can do just by comparing against the first one given that we only care

3392

// about the cumulative difference.

3393

ExtAddrMode::FieldName ThisDifferentField =

3394

AddrModes[0].compare(NewAddrMode);

3395

if (DifferentField == ExtAddrMode::NoField)

3396

DifferentField = ThisDifferentField;

3397

else if (DifferentField != ThisDifferentField)

3398

DifferentField = ExtAddrMode::MultipleFields;

3399

3400

// If this AddrMode is the same as all the others then everything is fine

3401

// (which should only happen when there is actually only one AddrMode).

3402

if (DifferentField == ExtAddrMode::NoField) {

3403

assert(AddrModes.size() == 1)((AddrModes.size() == 1) ? static_cast<void> (0) : __assert_fail
("AddrModes.size() == 1", "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 3403, __PRETTY_FUNCTION__));

3404

return true;

3405

}

3406

3407

// If NewAddrMode differs in only one dimension then we can handle it by

3408

// inserting a phi/select later on.

3409

if (DifferentField != ExtAddrMode::MultipleFields) {

3410

AddrModes.emplace_back(NewAddrMode);

3411

return true;

3412

}

3413

3414

// We couldn't combine NewAddrMode with the rest, so return failure.

3415

AddrModes.clear();

3416

return false;

3417

}

3418

3419

/// \brief Combine the addressing modes we've collected into a single

3420

/// addressing mode.

3421

/// \return True iff we successfully combined them or we only had one so

3422

/// didn't need to combine them anyway.

3423

bool combineAddrModes() {

3424

// If we have no AddrModes then they can't be combined.

3425

if (AddrModes.size() == 0)

3426

return false;

3427

3428

// A single AddrMode can trivially be combined.

3429

if (AddrModes.size() == 1)

3430

return true;

3431

3432

// If the AddrModes we collected are all just equal to the value they are

3433

// derived from then combining them wouldn't do anything useful.

3434

if (AllAddrModesTrivial)

3435

return false;

3436

3437

// TODO: Combine multiple AddrModes by inserting a select or phi for the

3438

// field in which the AddrModes differ.

3439

return false;

3440

}

3441

};

3442

3443

} // end anonymous namespace

3444

3445

/// Try adding ScaleReg*Scale to the current addressing mode.

3446

/// Return true and update AddrMode if this addr mode is legal for the target,

3447

/// false if not.

3448

bool AddressingModeMatcher::matchScaledValue(Value *ScaleReg, int64_t Scale,

3449

unsigned Depth) {

3450

// If Scale is 1, then this is the same as adding ScaleReg to the addressing

3451

// mode. Just process that directly.

3452

if (Scale == 1)

3453

return matchAddr(ScaleReg, Depth);

3454

3455

// If the scale is 0, it takes nothing to add this.

3456

if (Scale == 0)

3457

return true;

3458

3459

// If we already have a scale of this value, we can add to it, otherwise, we

3460

// need an available scale field.

3461

if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)

3462

return false;

3463

3464

ExtAddrMode TestAddrMode = AddrMode;

3465

3466

// Add scale to turn X*4+X*3 -> X*7. This could also do things like

3467

// [A+B + A*7] -> [B+A*8].

3468

TestAddrMode.Scale += Scale;

3469

TestAddrMode.ScaledReg = ScaleReg;

3470

3471

// If the new address isn't legal, bail out.

3472

if (!TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace))

3473

return false;

3474

3475

// It was legal, so commit it.

3476

AddrMode = TestAddrMode;

3477

3478

// Okay, we decided that we can add ScaleReg+Scale to AddrMode. Check now

3479

// to see if ScaleReg is actually X+C. If so, we can turn this into adding

3480

// X*Scale + C*Scale to addr mode.

3481

ConstantInt *CI = nullptr; Value *AddLHS = nullptr;

3482

if (isa<Instruction>(ScaleReg) && // not a constant expr.

3483

match(ScaleReg, m_Add(m_Value(AddLHS), m_ConstantInt(CI)))) {

3484

TestAddrMode.ScaledReg = AddLHS;

3485

TestAddrMode.BaseOffs += CI->getSExtValue()*TestAddrMode.Scale;

3486

3487

// If this addressing mode is legal, commit it and remember that we folded

3488

// this instruction.

3489

if (TLI.isLegalAddressingMode(DL, TestAddrMode, AccessTy, AddrSpace)) {

3490

AddrModeInsts.push_back(cast<Instruction>(ScaleReg));

3491

AddrMode = TestAddrMode;

3492

return true;

3493

}

3494

}

3495

3496

// Otherwise, not (x+c)*scale, just return what we have.

3497

return true;

3498

}

3499

3500

/// This is a little filter, which returns true if an addressing computation

3501

/// involving I might be folded into a load/store accessing it.

3502

/// This doesn't need to be perfect, but needs to accept at least

3503

/// the set of instructions that MatchOperationAddr can.

3504

static bool MightBeFoldableInst(Instruction *I) {

3505

switch (I->getOpcode()) {

3506

case Instruction::BitCast:

3507

case Instruction::AddrSpaceCast:

3508

// Don't touch identity bitcasts.

3509

if (I->getType() == I->getOperand(0)->getType())

3510

return false;

3511

return I->getType()->isPointerTy() || I->getType()->isIntegerTy();

3512

case Instruction::PtrToInt:

3513

// PtrToInt is always a noop, as we know that the int type is pointer sized.

3514

return true;

3515

case Instruction::IntToPtr:

3516

// We know the input is intptr_t, so this is foldable.

3517

return true;

3518

case Instruction::Add:

3519

return true;

3520

case Instruction::Mul:

3521

case Instruction::Shl:

3522

// Can only handle X*C and X << C.

3523

return isa<ConstantInt>(I->getOperand(1));

3524

case Instruction::GetElementPtr:

3525

return true;

3526

default:

3527

return false;

3528

}

3529

}

3530

3531

/// \brief Check whether or not \p Val is a legal instruction for \p TLI.

3532

/// \note \p Val is assumed to be the product of some type promotion.

3533

/// Therefore if \p Val has an undefined state in \p TLI, this is assumed

3534

/// to be legal, as the non-promoted value would have had the same state.

3535

static bool isPromotedInstructionLegal(const TargetLowering &TLI,

3536

const DataLayout &DL, Value *Val) {

3537

Instruction *PromotedInst = dyn_cast<Instruction>(Val);

3538

if (!PromotedInst)

3539

return false;

3540

int ISDOpcode = TLI.InstructionOpcodeToISD(PromotedInst->getOpcode());

3541

// If the ISDOpcode is undefined, it was undefined before the promotion.

3542

if (!ISDOpcode)

3543

return true;

3544

// Otherwise, check if the promoted instruction is legal or not.

3545

return TLI.isOperationLegalOrCustom(

3546

ISDOpcode, TLI.getValueType(DL, PromotedInst->getType()));

3547

}

3548

3549

namespace {

3550

3551

/// \brief Hepler class to perform type promotion.

3552

class TypePromotionHelper {

3553

/// \brief Utility function to check whether or not a sign or zero extension

3554

/// of \p Inst with \p ConsideredExtType can be moved through \p Inst by

3555

/// either using the operands of \p Inst or promoting \p Inst.

3556

/// The type of the extension is defined by \p IsSExt.

3557

/// In other words, check if:

3558

/// ext (Ty Inst opnd1 opnd2 ... opndN) to ConsideredExtType.

3559

/// #1 Promotion applies:

3560

/// ConsideredExtType Inst (ext opnd1 to ConsideredExtType, ...).

3561

/// #2 Operand reuses:

3562

/// ext opnd1 to ConsideredExtType.

3563

/// \p PromotedInsts maps the instructions to their type before promotion.

3564

static bool canGetThrough(const Instruction *Inst, Type *ConsideredExtType,

3565

const InstrToOrigTy &PromotedInsts, bool IsSExt);

3566

3567

/// \brief Utility function to determine if \p OpIdx should be promoted when

3568

/// promoting \p Inst.

3569

static bool shouldExtOperand(const Instruction *Inst, int OpIdx) {

3570

return !(isa<SelectInst>(Inst) && OpIdx == 0);

3571

}

3572

3573

/// \brief Utility function to promote the operand of \p Ext when this

3574

/// operand is a promotable trunc or sext or zext.

3575

/// \p PromotedInsts maps the instructions to their type before promotion.

3576

/// \p CreatedInstsCost[out] contains the cost of all instructions

3577

/// created to promote the operand of Ext.

3578

/// Newly added extensions are inserted in \p Exts.

3579

/// Newly added truncates are inserted in \p Truncs.

3580

/// Should never be called directly.

3581

/// \return The promoted value which is used instead of Ext.

3582

static Value *promoteOperandForTruncAndAnyExt(

3583

Instruction *Ext, TypePromotionTransaction &TPT,

3584

InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,

3585

SmallVectorImpl<Instruction *> *Exts,

3586

SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI);

3587

3588

/// \brief Utility function to promote the operand of \p Ext when this

3589

/// operand is promotable and is not a supported trunc or sext.

3590

/// \p PromotedInsts maps the instructions to their type before promotion.

3591

/// \p CreatedInstsCost[out] contains the cost of all the instructions

3592

/// created to promote the operand of Ext.

3593

/// Newly added extensions are inserted in \p Exts.

3594

/// Newly added truncates are inserted in \p Truncs.

3595

/// Should never be called directly.

3596

/// \return The promoted value which is used instead of Ext.

3597

static Value *promoteOperandForOther(Instruction *Ext,

3598

TypePromotionTransaction &TPT,

3599

InstrToOrigTy &PromotedInsts,

3600

unsigned &CreatedInstsCost,

3601

SmallVectorImpl<Instruction *> *Exts,

3602

SmallVectorImpl<Instruction *> *Truncs,

3603

const TargetLowering &TLI, bool IsSExt);

3604

3605

/// \see promoteOperandForOther.

3606

static Value *signExtendOperandForOther(

3607

Instruction *Ext, TypePromotionTransaction &TPT,

3608

InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,

3609

SmallVectorImpl<Instruction *> *Exts,

3610

SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {

3611

return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,

3612

Exts, Truncs, TLI, true);

3613

}

3614

3615

/// \see promoteOperandForOther.

3616

static Value *zeroExtendOperandForOther(

3617

Instruction *Ext, TypePromotionTransaction &TPT,

3618

InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,

3619

SmallVectorImpl<Instruction *> *Exts,

3620

SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {

3621

return promoteOperandForOther(Ext, TPT, PromotedInsts, CreatedInstsCost,

3622

Exts, Truncs, TLI, false);

3623

}

3624

3625

public:

3626

/// Type for the utility function that promotes the operand of Ext.

3627

using Action = Value *(*)(Instruction *Ext, TypePromotionTransaction &TPT,

3628

InstrToOrigTy &PromotedInsts,

3629

unsigned &CreatedInstsCost,

3630

SmallVectorImpl<Instruction *> *Exts,

3631

SmallVectorImpl<Instruction *> *Truncs,

3632

const TargetLowering &TLI);

3633

3634

/// \brief Given a sign/zero extend instruction \p Ext, return the approriate

3635

/// action to promote the operand of \p Ext instead of using Ext.

3636

/// \return NULL if no promotable action is possible with the current

3637

/// sign extension.

3638

/// \p InsertedInsts keeps track of all the instructions inserted by the

3639

/// other CodeGenPrepare optimizations. This information is important

3640

/// because we do not want to promote these instructions as CodeGenPrepare

3641

/// will reinsert them later. Thus creating an infinite loop: create/remove.

3642

/// \p PromotedInsts maps the instructions to their type before promotion.

3643

static Action getAction(Instruction *Ext, const SetOfInstrs &InsertedInsts,

3644

const TargetLowering &TLI,

3645

const InstrToOrigTy &PromotedInsts);

3646

};

3647

3648

} // end anonymous namespace

3649

3650

bool TypePromotionHelper::canGetThrough(const Instruction *Inst,

3651

Type *ConsideredExtType,

3652

const InstrToOrigTy &PromotedInsts,

3653

bool IsSExt) {

3654

// The promotion helper does not know how to deal with vector types yet.

3655

// To be able to fix that, we would need to fix the places where we

3656

// statically extend, e.g., constants and such.

3657

if (Inst->getType()->isVectorTy())

3658

return false;

3659

3660

// We can always get through zext.

3661

if (isa<ZExtInst>(Inst))

3662

return true;

3663

3664

// sext(sext) is ok too.

3665

if (IsSExt && isa<SExtInst>(Inst))

3666

return true;

3667

3668

// We can get through binary operator, if it is legal. In other words, the

3669

// binary operator must have a nuw or nsw flag.

3670

const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(Inst);

3671

if (BinOp && isa<OverflowingBinaryOperator>(BinOp) &&

3672

((!IsSExt && BinOp->hasNoUnsignedWrap()) ||

3673

(IsSExt && BinOp->hasNoSignedWrap())))

3674

return true;

3675

3676

// Check if we can do the following simplification.

3677

// ext(trunc(opnd)) --> ext(opnd)

3678

if (!isa<TruncInst>(Inst))

3679

return false;

3680

3681

Value *OpndVal = Inst->getOperand(0);

3682

// Check if we can use this operand in the extension.

3683

// If the type is larger than the result type of the extension, we cannot.

3684

if (!OpndVal->getType()->isIntegerTy() ||

3685

OpndVal->getType()->getIntegerBitWidth() >

3686

ConsideredExtType->getIntegerBitWidth())

3687

return false;

3688

3689

// If the operand of the truncate is not an instruction, we will not have

3690

// any information on the dropped bits.

3691

// (Actually we could for constant but it is not worth the extra logic).

3692

Instruction *Opnd = dyn_cast<Instruction>(OpndVal);

3693

if (!Opnd)

3694

return false;

3695

3696

// Check if the source of the type is narrow enough.

3697

// I.e., check that trunc just drops extended bits of the same kind of

3698

// the extension.

3699

// #1 get the type of the operand and check the kind of the extended bits.

3700

const Type *OpndType;

3701

InstrToOrigTy::const_iterator It = PromotedInsts.find(Opnd);

3702

if (It != PromotedInsts.end() && It->second.getInt() == IsSExt)

3703

OpndType = It->second.getPointer();

3704

else if ((IsSExt && isa<SExtInst>(Opnd)) || (!IsSExt && isa<ZExtInst>(Opnd)))

3705

OpndType = Opnd->getOperand(0)->getType();

3706

else

3707

return false;

3708

3709

// #2 check that the truncate just drops extended bits.

3710

return Inst->getType()->getIntegerBitWidth() >=

3711

OpndType->getIntegerBitWidth();

3712

}

3713

3714

TypePromotionHelper::Action TypePromotionHelper::getAction(

3715

Instruction *Ext, const SetOfInstrs &InsertedInsts,

3716

const TargetLowering &TLI, const InstrToOrigTy &PromotedInsts) {

3717

assert((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&(((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
"Unexpected instruction type") ? static_cast<void> (0)
: __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 3718, __PRETTY_FUNCTION__))

3718

"Unexpected instruction type")(((isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) &&
"Unexpected instruction type") ? static_cast<void> (0)
: __assert_fail ("(isa<SExtInst>(Ext) || isa<ZExtInst>(Ext)) && \"Unexpected instruction type\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 3718, __PRETTY_FUNCTION__));

3719

Instruction *ExtOpnd = dyn_cast<Instruction>(Ext->getOperand(0));

3720

Type *ExtTy = Ext->getType();

3721

bool IsSExt = isa<SExtInst>(Ext);

3722

// If the operand of the extension is not an instruction, we cannot

3723

// get through.

3724

// If it, check we can get through.

3725

if (!ExtOpnd || !canGetThrough(ExtOpnd, ExtTy, PromotedInsts, IsSExt))

3726

return nullptr;

3727

3728

// Do not promote if the operand has been added by codegenprepare.

3729

// Otherwise, it means we are undoing an optimization that is likely to be

3730

// redone, thus causing potential infinite loop.

3731

if (isa<TruncInst>(ExtOpnd) && InsertedInsts.count(ExtOpnd))

3732

return nullptr;

3733

3734

// SExt or Trunc instructions.

3735

// Return the related handler.

3736

if (isa<SExtInst>(ExtOpnd) || isa<TruncInst>(ExtOpnd) ||

3737

isa<ZExtInst>(ExtOpnd))

3738

return promoteOperandForTruncAndAnyExt;

3739

3740

// Regular instruction.

3741

// Abort early if we will have to insert non-free instructions.

3742

if (!ExtOpnd->hasOneUse() && !TLI.isTruncateFree(ExtTy, ExtOpnd->getType()))

3743

return nullptr;

3744

return IsSExt ? signExtendOperandForOther : zeroExtendOperandForOther;

3745

}

3746

3747

Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(

3748

Instruction *SExt, TypePromotionTransaction &TPT,

3749

InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,

3750

SmallVectorImpl<Instruction *> *Exts,

3751

SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI) {

3752

// By construction, the operand of SExt is an instruction. Otherwise we cannot

3753

// get through it and this method should not be called.

3754

Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));

3755

Value *ExtVal = SExt;

3756

bool HasMergedNonFreeExt = false;

3757

if (isa<ZExtInst>(SExtOpnd)) {

3758

// Replace s|zext(zext(opnd))

3759

// => zext(opnd).

3760

HasMergedNonFreeExt = !TLI.isExtFree(SExtOpnd);

3761

Value *ZExt =

3762

TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());

3763

TPT.replaceAllUsesWith(SExt, ZExt);

3764

TPT.eraseInstruction(SExt);

3765

ExtVal = ZExt;

3766

} else {

3767

// Replace z|sext(trunc(opnd)) or sext(sext(opnd))

3768

// => z|sext(opnd).

3769

TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));

3770

}

3771

CreatedInstsCost = 0;

3772

3773

// Remove dead code.

3774

if (SExtOpnd->use_empty())

3775

TPT.eraseInstruction(SExtOpnd);

3776

3777

// Check if the extension is still needed.

3778

Instruction *ExtInst = dyn_cast<Instruction>(ExtVal);

3779

if (!ExtInst || ExtInst->getType() != ExtInst->getOperand(0)->getType()) {

3780

if (ExtInst) {

3781

if (Exts)

3782

Exts->push_back(ExtInst);

3783

CreatedInstsCost = !TLI.isExtFree(ExtInst) && !HasMergedNonFreeExt;

3784

}

3785

return ExtVal;

3786

}

3787

3788

// At this point we have: ext ty opnd to ty.

3789

// Reassign the uses of ExtInst to the opnd and remove ExtInst.

3790

Value *NextVal = ExtInst->getOperand(0);

3791

TPT.eraseInstruction(ExtInst, NextVal);

3792

return NextVal;

3793

}

3794

3795

Value *TypePromotionHelper::promoteOperandForOther(

3796

Instruction *Ext, TypePromotionTransaction &TPT,

3797

InstrToOrigTy &PromotedInsts, unsigned &CreatedInstsCost,

3798

SmallVectorImpl<Instruction *> *Exts,

3799

SmallVectorImpl<Instruction *> *Truncs, const TargetLowering &TLI,

3800

bool IsSExt) {

3801

// By construction, the operand of Ext is an instruction. Otherwise we cannot

3802

// get through it and this method should not be called.

3803

Instruction *ExtOpnd = cast<Instruction>(Ext->getOperand(0));

3804

CreatedInstsCost = 0;

3805

if (!ExtOpnd->hasOneUse()) {

3806

// ExtOpnd will be promoted.

3807

// All its uses, but Ext, will need to use a truncated value of the

3808

// promoted version.

3809

// Create the truncate now.

3810

Value *Trunc = TPT.createTrunc(Ext, ExtOpnd->getType());

3811

if (Instruction *ITrunc = dyn_cast<Instruction>(Trunc)) {

3812

// Insert it just after the definition.

3813

ITrunc->moveAfter(ExtOpnd);

3814

if (Truncs)

3815

Truncs->push_back(ITrunc);

3816

}

3817

3818

TPT.replaceAllUsesWith(ExtOpnd, Trunc);

3819

// Restore the operand of Ext (which has been replaced by the previous call

3820

// to replaceAllUsesWith) to avoid creating a cycle trunc <-> sext.

3821

TPT.setOperand(Ext, 0, ExtOpnd);

3822

}

3823

3824

// Get through the Instruction:

3825

// 1. Update its type.

3826

// 2. Replace the uses of Ext by Inst.

3827

// 3. Extend each operand that needs to be extended.

3828

3829

// Remember the original type of the instruction before promotion.

3830

// This is useful to know that the high bits are sign extended bits.

3831

PromotedInsts.insert(std::pair<Instruction *, TypeIsSExt>(

3832

ExtOpnd, TypeIsSExt(ExtOpnd->getType(), IsSExt)));

3833

// Step #1.

3834

TPT.mutateType(ExtOpnd, Ext->getType());

3835

// Step #2.

3836

TPT.replaceAllUsesWith(Ext, ExtOpnd);

3837

// Step #3.

3838

Instruction *ExtForOpnd = Ext;

3839

3840

DEBUG(dbgs() << "Propagate Ext to operands\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Propagate Ext to operands\n"
; } } while (false);

3841

for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;

3842

++OpIdx) {

3843

DEBUG(dbgs() << "Operand:\n" << *(ExtOpnd->getOperand(OpIdx)) << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Operand:\n" << *
(ExtOpnd->getOperand(OpIdx)) << '\n'; } } while (false
);

3844

if (ExtOpnd->getOperand(OpIdx)->getType() == Ext->getType() ||

3845

!shouldExtOperand(ExtOpnd, OpIdx)) {

3846

DEBUG(dbgs() << "No need to propagate\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "No need to propagate\n"
; } } while (false);

3847

continue;

3848

}

3849

// Check if we can statically extend the operand.

3850

Value *Opnd = ExtOpnd->getOperand(OpIdx);

3851

if (const ConstantInt *Cst = dyn_cast<ConstantInt>(Opnd)) {

3852

DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false);

3853

unsigned BitWidth = Ext->getType()->getIntegerBitWidth();

3854

APInt CstVal = IsSExt ? Cst->getValue().sext(BitWidth)

3855

: Cst->getValue().zext(BitWidth);

3856

TPT.setOperand(ExtOpnd, OpIdx, ConstantInt::get(Ext->getType(), CstVal));

3857

continue;

3858

}

3859

// UndefValue are typed, so we have to statically sign extend them.

3860

if (isa<UndefValue>(Opnd)) {

3861

DEBUG(dbgs() << "Statically extend\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Statically extend\n"; }
} while (false);

3862

TPT.setOperand(ExtOpnd, OpIdx, UndefValue::get(Ext->getType()));

3863

continue;

3864

}

3865

3866

// Otherwise we have to explicity sign extend the operand.

3867

// Check if Ext was reused to extend an operand.

3868

if (!ExtForOpnd) {

3869

// If yes, create a new one.

3870

DEBUG(dbgs() << "More operands to ext\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "More operands to ext\n"
; } } while (false);

3871

Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())

3872

: TPT.createZExt(Ext, Opnd, Ext->getType());

3873

if (!isa<Instruction>(ValForExtOpnd)) {

3874

TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);

3875

continue;

3876

}

3877

ExtForOpnd = cast<Instruction>(ValForExtOpnd);

3878

}

3879

if (Exts)

3880

Exts->push_back(ExtForOpnd);

3881

TPT.setOperand(ExtForOpnd, 0, Opnd);

3882

3883

// Move the sign extension before the insertion point.

3884

TPT.moveBefore(ExtForOpnd, ExtOpnd);

3885

TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);

3886

CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);

3887

// If more sext are required, new instructions will have to be created.

3888

ExtForOpnd = nullptr;

3889

}

3890

if (ExtForOpnd == Ext) {

3891

DEBUG(dbgs() << "Extension is useless now\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Extension is useless now\n"
; } } while (false);

3892

TPT.eraseInstruction(Ext);

3893

}

3894

return ExtOpnd;

3895

}

3896

3897

/// Check whether or not promoting an instruction to a wider type is profitable.

3898

/// \p NewCost gives the cost of extension instructions created by the

3899

/// promotion.

3900

/// \p OldCost gives the cost of extension instructions before the promotion

3901

/// plus the number of instructions that have been

3902

/// matched in the addressing mode the promotion.

3903

/// \p PromotedOperand is the value that has been promoted.

3904

/// \return True if the promotion is profitable, false otherwise.

3905

bool AddressingModeMatcher::isPromotionProfitable(

3906

unsigned NewCost, unsigned OldCost, Value *PromotedOperand) const {

3907

DEBUG(dbgs() << "OldCost: " << OldCost << "\tNewCost: " << NewCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "OldCost: " << OldCost
<< "\tNewCost: " << NewCost << '\n'; } } while
(false);

3908

// The cost of the new extensions is greater than the cost of the

3909

// old extension plus what we folded.

3910

// This is not profitable.

3911

if (NewCost > OldCost)

3912

return false;

3913

if (NewCost < OldCost)

3914

return true;

3915

// The promotion is neutral but it may help folding the sign extension in

3916

// loads for instance.

3917

// Check that we did not create an illegal instruction.

3918

return isPromotedInstructionLegal(TLI, DL, PromotedOperand);

3919

}

3920

3921

/// Given an instruction or constant expr, see if we can fold the operation

3922

/// into the addressing mode. If so, update the addressing mode and return

3923

/// true, otherwise return false without modifying AddrMode.

3924

/// If \p MovedAway is not NULL, it contains the information of whether or

3925

/// not AddrInst has to be folded into the addressing mode on success.

3926

/// If \p MovedAway == true, \p AddrInst will not be part of the addressing

3927

/// because it has been moved away.

3928

/// Thus AddrInst must not be added in the matched instructions.

3929

/// This state can happen when AddrInst is a sext, since it may be moved away.

3930

/// Therefore, AddrInst may not be valid when MovedAway is true and it must

3931

/// not be referenced anymore.

3932

bool AddressingModeMatcher::matchOperationAddr(User *AddrInst, unsigned Opcode,

3933

unsigned Depth,

3934

bool *MovedAway) {

3935

// Avoid exponential behavior on extremely deep expression trees.

3936

if (Depth >= 5) return false;

3937

3938

// By default, all matched instructions stay in place.

3939

if (MovedAway)

3940

*MovedAway = false;

3941

3942

switch (Opcode) {

3943

case Instruction::PtrToInt:

3944

// PtrToInt is always a noop, as we know that the int type is pointer sized.

3945

return matchAddr(AddrInst->getOperand(0), Depth);

3946

case Instruction::IntToPtr: {

3947

auto AS = AddrInst->getType()->getPointerAddressSpace();

3948

auto PtrTy = MVT::getIntegerVT(DL.getPointerSizeInBits(AS));

3949

// This inttoptr is a no-op if the integer type is pointer sized.

3950

if (TLI.getValueType(DL, AddrInst->getOperand(0)->getType()) == PtrTy)

3951

return matchAddr(AddrInst->getOperand(0), Depth);

3952

return false;

3953

}

3954

case Instruction::BitCast:

3955

// BitCast is always a noop, and we can handle it as long as it is

3956

// int->int or pointer->pointer (we don't want int<->fp or something).

3957

if ((AddrInst->getOperand(0)->getType()->isPointerTy() ||

3958

AddrInst->getOperand(0)->getType()->isIntegerTy()) &&

3959

// Don't touch identity bitcasts. These were probably put here by LSR,

3960

// and we don't want to mess around with them. Assume it knows what it

3961

// is doing.

3962

AddrInst->getOperand(0)->getType() != AddrInst->getType())

3963

return matchAddr(AddrInst->getOperand(0), Depth);

3964

return false;

3965

case Instruction::AddrSpaceCast: {

3966

unsigned SrcAS

3967

= AddrInst->getOperand(0)->getType()->getPointerAddressSpace();

3968

unsigned DestAS = AddrInst->getType()->getPointerAddressSpace();

3969

if (TLI.isNoopAddrSpaceCast(SrcAS, DestAS))

3970

return matchAddr(AddrInst->getOperand(0), Depth);

3971

return false;

3972

}

3973

case Instruction::Add: {

3974

// Check to see if we can merge in the RHS then the LHS. If so, we win.

3975

ExtAddrMode BackupAddrMode = AddrMode;

3976

unsigned OldSize = AddrModeInsts.size();

3977

// Start a transaction at this point.

3978

// The LHS may match but not the RHS.

3979

// Therefore, we need a higher level restoration point to undo partially

3980

// matched operation.

3981

TypePromotionTransaction::ConstRestorationPt LastKnownGood =

3982

TPT.getRestorationPoint();

3983

3984

if (matchAddr(AddrInst->getOperand(1), Depth+1) &&

3985

matchAddr(AddrInst->getOperand(0), Depth+1))

3986

return true;

3987

3988

// Restore the old addr mode info.

3989

AddrMode = BackupAddrMode;

3990

AddrModeInsts.resize(OldSize);

3991

TPT.rollback(LastKnownGood);

3992

3993

// Otherwise this was over-aggressive. Try merging in the LHS then the RHS.

3994

if (matchAddr(AddrInst->getOperand(0), Depth+1) &&

3995

matchAddr(AddrInst->getOperand(1), Depth+1))

3996

return true;

3997

3998

// Otherwise we definitely can't merge the ADD in.

3999

AddrMode = BackupAddrMode;

4000

AddrModeInsts.resize(OldSize);

4001

TPT.rollback(LastKnownGood);

4002

break;

4003

}

4004

//case Instruction::Or:

4005

// TODO: We can handle "Or Val, Imm" iff this OR is equivalent to an ADD.

4006

//break;

4007

case Instruction::Mul:

4008

case Instruction::Shl: {

4009

// Can only handle X*C and X << C.

4010

ConstantInt *RHS = dyn_cast<ConstantInt>(AddrInst->getOperand(1));

4011

if (!RHS)

4012

return false;

4013

int64_t Scale = RHS->getSExtValue();

4014

if (Opcode == Instruction::Shl)

4015

Scale = 1LL << Scale;

4016

4017

return matchScaledValue(AddrInst->getOperand(0), Scale, Depth);

4018

}

4019

case Instruction::GetElementPtr: {

4020

// Scan the GEP. We check it if it contains constant offsets and at most

4021

// one variable offset.

4022

int VariableOperand = -1;

4023

unsigned VariableScale = 0;

4024

4025

int64_t ConstantOffset = 0;

4026

gep_type_iterator GTI = gep_type_begin(AddrInst);

4027

for (unsigned i = 1, e = AddrInst->getNumOperands(); i != e; ++i, ++GTI) {

4028

if (StructType *STy = GTI.getStructTypeOrNull()) {

4029

const StructLayout *SL = DL.getStructLayout(STy);

4030

unsigned Idx =

4031

cast<ConstantInt>(AddrInst->getOperand(i))->getZExtValue();

4032

ConstantOffset += SL->getElementOffset(Idx);

4033

} else {

4034

uint64_t TypeSize = DL.getTypeAllocSize(GTI.getIndexedType());

4035

if (ConstantInt *CI = dyn_cast<ConstantInt>(AddrInst->getOperand(i))) {

4036

ConstantOffset += CI->getSExtValue()*TypeSize;

4037

} else if (TypeSize) { // Scales of zero don't do anything.

4038

// We only allow one variable index at the moment.

4039

if (VariableOperand != -1)

4040

return false;

4041

4042

// Remember the variable index.

4043

VariableOperand = i;

4044

VariableScale = TypeSize;

4045

}

4046

}

4047

}

4048

4049

// A common case is for the GEP to only do a constant offset. In this case,

4050

// just add it to the disp field and check validity.

4051

if (VariableOperand == -1) {

4052

AddrMode.BaseOffs += ConstantOffset;

4053

if (ConstantOffset == 0 ||

4054

TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace)) {

4055

// Check to see if we can fold the base pointer in too.

4056

if (matchAddr(AddrInst->getOperand(0), Depth+1))

4057

return true;

4058

}

4059

AddrMode.BaseOffs -= ConstantOffset;

4060

return false;

4061

}

4062

4063

// Save the valid addressing mode in case we can't match.

4064

ExtAddrMode BackupAddrMode = AddrMode;

4065

unsigned OldSize = AddrModeInsts.size();

4066

4067

// See if the scale and offset amount is valid for this target.

4068

AddrMode.BaseOffs += ConstantOffset;

4069

4070

// Match the base operand of the GEP.

4071

if (!matchAddr(AddrInst->getOperand(0), Depth+1)) {

4072

// If it couldn't be matched, just stuff the value in a register.

4073

if (AddrMode.HasBaseReg) {

4074

AddrMode = BackupAddrMode;

4075

AddrModeInsts.resize(OldSize);

4076

return false;

4077

}

4078

AddrMode.HasBaseReg = true;

4079

AddrMode.BaseReg = AddrInst->getOperand(0);

4080

}

4081

4082

// Match the remaining variable portion of the GEP.

4083

if (!matchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,

4084

Depth)) {

4085

// If it couldn't be matched, try stuffing the base into a register

4086

// instead of matching it, and retrying the match of the scale.

4087

AddrMode = BackupAddrMode;

4088

AddrModeInsts.resize(OldSize);

4089

if (AddrMode.HasBaseReg)

4090

return false;

4091

AddrMode.HasBaseReg = true;

4092

AddrMode.BaseReg = AddrInst->getOperand(0);

4093

AddrMode.BaseOffs += ConstantOffset;

4094

if (!matchScaledValue(AddrInst->getOperand(VariableOperand),

4095

VariableScale, Depth)) {

4096

// If even that didn't work, bail.

4097

AddrMode = BackupAddrMode;

4098

AddrModeInsts.resize(OldSize);

4099

return false;

4100

}

4101

}

4102

4103

return true;

4104

}

4105

case Instruction::SExt:

4106

case Instruction::ZExt: {

4107

Instruction *Ext = dyn_cast<Instruction>(AddrInst);

4108

if (!Ext)

4109

return false;

4110

4111

// Try to move this ext out of the way of the addressing mode.

4112

// Ask for a method for doing so.

4113

TypePromotionHelper::Action TPH =

4114

TypePromotionHelper::getAction(Ext, InsertedInsts, TLI, PromotedInsts);

4115

if (!TPH)

4116

return false;

4117

4118

TypePromotionTransaction::ConstRestorationPt LastKnownGood =

4119

TPT.getRestorationPoint();

4120

unsigned CreatedInstsCost = 0;

4121

unsigned ExtCost = !TLI.isExtFree(Ext);

4122

Value *PromotedOperand =

4123

TPH(Ext, TPT, PromotedInsts, CreatedInstsCost, nullptr, nullptr, TLI);

4124

// SExt has been moved away.

4125

// Thus either it will be rematched later in the recursive calls or it is

4126

// gone. Anyway, we must not fold it into the addressing mode at this point.

4127

// E.g.,

4128

// op = add opnd, 1

4129

// idx = ext op

4130

// addr = gep base, idx

4131

// is now:

4132

// promotedOpnd = ext opnd <- no match here

4133

// op = promoted_add promotedOpnd, 1 <- match (later in recursive calls)

4134

// addr = gep base, op <- match

4135

if (MovedAway)

4136

*MovedAway = true;

4137

4138

assert(PromotedOperand &&((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 4139, __PRETTY_FUNCTION__))

4139

"TypePromotionHelper should have filtered out those cases")((PromotedOperand && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedOperand && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 4139, __PRETTY_FUNCTION__));

4140

4141

ExtAddrMode BackupAddrMode = AddrMode;

4142

unsigned OldSize = AddrModeInsts.size();

4143

4144

if (!matchAddr(PromotedOperand, Depth) ||

4145

// The total of the new cost is equal to the cost of the created

4146

// instructions.

4147

// The total of the old cost is equal to the cost of the extension plus

4148

// what we have saved in the addressing mode.

4149

!isPromotionProfitable(CreatedInstsCost,

4150

ExtCost + (AddrModeInsts.size() - OldSize),

4151

PromotedOperand)) {

4152

AddrMode = BackupAddrMode;

4153

AddrModeInsts.resize(OldSize);

4154

DEBUG(dbgs() << "Sign extension does not pay off: rollback\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Sign extension does not pay off: rollback\n"
; } } while (false);

4155

TPT.rollback(LastKnownGood);

4156

return false;

4157

}

4158

return true;

4159

}

4160

}

4161

return false;

4162

}

4163

4164

/// If we can, try to add the value of 'Addr' into the current addressing mode.

4165

/// If Addr can't be added to AddrMode this returns false and leaves AddrMode

4166

/// unmodified. This assumes that Addr is either a pointer type or intptr_t

4167

/// for the target.

4168

///

4169

bool AddressingModeMatcher::matchAddr(Value *Addr, unsigned Depth) {

4170

// Start a transaction at this point that we will rollback if the matching

4171

// fails.

4172

TypePromotionTransaction::ConstRestorationPt LastKnownGood =

4173

TPT.getRestorationPoint();

4174

if (ConstantInt *CI = dyn_cast<ConstantInt>(Addr)) {

4175

// Fold in immediates if legal for the target.

4176

AddrMode.BaseOffs += CI->getSExtValue();

4177

if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))

4178

return true;

4179

AddrMode.BaseOffs -= CI->getSExtValue();

4180

} else if (GlobalValue *GV = dyn_cast<GlobalValue>(Addr)) {

4181

// If this is a global variable, try to fold it into the addressing mode.

4182

if (!AddrMode.BaseGV) {

4183

AddrMode.BaseGV = GV;

4184

if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))

4185

return true;

4186

AddrMode.BaseGV = nullptr;

4187

}

4188

} else if (Instruction *I = dyn_cast<Instruction>(Addr)) {

4189

ExtAddrMode BackupAddrMode = AddrMode;

4190

unsigned OldSize = AddrModeInsts.size();

4191

4192

// Check to see if it is possible to fold this operation.

4193

bool MovedAway = false;

4194

if (matchOperationAddr(I, I->getOpcode(), Depth, &MovedAway)) {

4195

// This instruction may have been moved away. If so, there is nothing

4196

// to check here.

4197

if (MovedAway)

4198

return true;

4199

// Okay, it's possible to fold this. Check to see if it is actually

4200

// *profitable* to do so. We use a simple cost model to avoid increasing

4201

// register pressure too much.

4202

if (I->hasOneUse() ||

4203

isProfitableToFoldIntoAddressingMode(I, BackupAddrMode, AddrMode)) {

4204

AddrModeInsts.push_back(I);

4205

return true;

4206

}

4207

4208

// It isn't profitable to do this, roll back.

4209

//cerr << "NOT FOLDING: " << *I;

4210

AddrMode = BackupAddrMode;

4211

AddrModeInsts.resize(OldSize);

4212

TPT.rollback(LastKnownGood);

4213

}

4214

} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr)) {

4215

if (matchOperationAddr(CE, CE->getOpcode(), Depth))

4216

return true;

4217

TPT.rollback(LastKnownGood);

4218

} else if (isa<ConstantPointerNull>(Addr)) {

4219

// Null pointer gets folded without affecting the addressing mode.

4220

return true;

4221

}

4222

4223

// Worse case, the target should support [reg] addressing modes. :)

4224

if (!AddrMode.HasBaseReg) {

4225

AddrMode.HasBaseReg = true;

4226

AddrMode.BaseReg = Addr;

4227

// Still check for legality in case the target supports [imm] but not [i+r].

4228

if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))

4229

return true;

4230

AddrMode.HasBaseReg = false;

4231

AddrMode.BaseReg = nullptr;

4232

}

4233

4234

// If the base register is already taken, see if we can do [r+r].

4235

if (AddrMode.Scale == 0) {

4236

AddrMode.Scale = 1;

4237

AddrMode.ScaledReg = Addr;

4238

if (TLI.isLegalAddressingMode(DL, AddrMode, AccessTy, AddrSpace))

4239

return true;

4240

AddrMode.Scale = 0;

4241

AddrMode.ScaledReg = nullptr;

4242

}

4243

// Couldn't match.

4244

TPT.rollback(LastKnownGood);

4245

return false;

4246

}

4247

4248

/// Check to see if all uses of OpVal by the specified inline asm call are due

4249

/// to memory operands. If so, return true, otherwise return false.

4250

static bool IsOperandAMemoryOperand(CallInst *CI, InlineAsm *IA, Value *OpVal,

4251

const TargetLowering &TLI,

4252

const TargetRegisterInfo &TRI) {

4253

const Function *F = CI->getFunction();

4254

TargetLowering::AsmOperandInfoVector TargetConstraints =

4255

TLI.ParseConstraints(F->getParent()->getDataLayout(), &TRI,

4256

ImmutableCallSite(CI));

4257

4258

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

4259

TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];

4260

4261

// Compute the constraint code and ConstraintType to use.

4262

TLI.ComputeConstraintToUse(OpInfo, SDValue());

4263

4264

// If this asm operand is our Value*, and if it isn't an indirect memory

4265

// operand, we can't fold it!

4266

if (OpInfo.CallOperandVal == OpVal &&

4267

(OpInfo.ConstraintType != TargetLowering::C_Memory ||

4268

!OpInfo.isIndirect))

4269

return false;

4270

}

4271

4272

return true;

4273

}

4274

4275

// Max number of memory uses to look at before aborting the search to conserve

4276

// compile time.

4277

static constexpr int MaxMemoryUsesToScan = 20;

4278

4279

/// Recursively walk all the uses of I until we find a memory use.

4280

/// If we find an obviously non-foldable instruction, return true.

4281

/// Add the ultimately found memory instructions to MemoryUses.

4282

static bool FindAllMemoryUses(

4283

Instruction *I,

4284

SmallVectorImpl<std::pair<Instruction *, unsigned>> &MemoryUses,

4285

SmallPtrSetImpl<Instruction *> &ConsideredInsts, const TargetLowering &TLI,

4286

const TargetRegisterInfo &TRI, int SeenInsts = 0) {

4287

// If we already considered this instruction, we're done.

4288

if (!ConsideredInsts.insert(I).second)

4289

return false;

4290

4291

// If this is an obviously unfoldable instruction, bail out.

4292

if (!MightBeFoldableInst(I))

4293

return true;

4294

4295

const bool OptSize = I->getFunction()->optForSize();

4296

4297

// Loop over all the uses, recursively processing them.

4298

for (Use &U : I->uses()) {

4299

// Conservatively return true if we're seeing a large number or a deep chain

4300

// of users. This avoids excessive compilation times in pathological cases.

4301

if (SeenInsts++ >= MaxMemoryUsesToScan)

4302

return true;

4303

4304

Instruction *UserI = cast<Instruction>(U.getUser());

4305

if (LoadInst *LI = dyn_cast<LoadInst>(UserI)) {

4306

MemoryUses.push_back(std::make_pair(LI, U.getOperandNo()));

4307

continue;

4308

}

4309

4310

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

4311

unsigned opNo = U.getOperandNo();

4312

if (opNo != StoreInst::getPointerOperandIndex())

4313

return true; // Storing addr, not into addr.

4314

MemoryUses.push_back(std::make_pair(SI, opNo));

4315

continue;

4316

}

4317

4318

if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(UserI)) {

4319

unsigned opNo = U.getOperandNo();

4320

if (opNo != AtomicRMWInst::getPointerOperandIndex())

4321

return true; // Storing addr, not into addr.

4322

MemoryUses.push_back(std::make_pair(RMW, opNo));

4323

continue;

4324

}

4325

4326

if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(UserI)) {

4327

unsigned opNo = U.getOperandNo();

4328

if (opNo != AtomicCmpXchgInst::getPointerOperandIndex())

4329

return true; // Storing addr, not into addr.

4330

MemoryUses.push_back(std::make_pair(CmpX, opNo));

4331

continue;

4332

}

4333

4334

if (CallInst *CI = dyn_cast<CallInst>(UserI)) {

4335

// If this is a cold call, we can sink the addressing calculation into

4336

// the cold path. See optimizeCallInst

4337

if (!OptSize && CI->hasFnAttr(Attribute::Cold))

4338

continue;

4339

4340

InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue());

4341

if (!IA) return true;

4342

4343

// If this is a memory operand, we're cool, otherwise bail out.

4344

if (!IsOperandAMemoryOperand(CI, IA, I, TLI, TRI))

4345

return true;

4346

continue;

4347

}

4348

4349

if (FindAllMemoryUses(UserI, MemoryUses, ConsideredInsts, TLI, TRI,

4350

SeenInsts))

4351

return true;

4352

}

4353

4354

return false;

4355

}

4356

4357

/// Return true if Val is already known to be live at the use site that we're

4358

/// folding it into. If so, there is no cost to include it in the addressing

4359

/// mode. KnownLive1 and KnownLive2 are two values that we know are live at the

4360

/// instruction already.

4361

bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,Value *KnownLive1,

4362

Value *KnownLive2) {

4363

// If Val is either of the known-live values, we know it is live!

4364

if (Val == nullptr || Val == KnownLive1 || Val == KnownLive2)

4365

return true;

4366

4367

// All values other than instructions and arguments (e.g. constants) are live.

4368

if (!isa<Instruction>(Val) && !isa<Argument>(Val)) return true;

4369

4370

// If Val is a constant sized alloca in the entry block, it is live, this is

4371

// true because it is just a reference to the stack/frame pointer, which is

4372

// live for the whole function.

4373

if (AllocaInst *AI = dyn_cast<AllocaInst>(Val))

4374

if (AI->isStaticAlloca())

4375

return true;

4376

4377

// Check to see if this value is already used in the memory instruction's

4378

// block. If so, it's already live into the block at the very least, so we

4379

// can reasonably fold it.

4380

return Val->isUsedInBasicBlock(MemoryInst->getParent());

4381

}

4382

4383

/// It is possible for the addressing mode of the machine to fold the specified

4384

/// instruction into a load or store that ultimately uses it.

4385

/// However, the specified instruction has multiple uses.

4386

/// Given this, it may actually increase register pressure to fold it

4387

/// into the load. For example, consider this code:

4388

///

4389

/// X = ...

4390

/// Y = X+1

4391

/// use(Y) -> nonload/store

4392

/// Z = Y+1

4393

/// load Z

4394

///

4395

/// In this case, Y has multiple uses, and can be folded into the load of Z

4396

/// (yielding load [X+2]). However, doing this will cause both "X" and "X+1" to

4397

/// be live at the use(Y) line. If we don't fold Y into load Z, we use one

4398

/// fewer register. Since Y can't be folded into "use(Y)" we don't increase the

4399

/// number of computations either.

4400

///

4401

/// Note that this (like most of CodeGenPrepare) is just a rough heuristic. If

4402

/// X was live across 'load Z' for other reasons, we actually *would* want to

4403

/// fold the addressing mode in the Z case. This would make Y die earlier.

4404

bool AddressingModeMatcher::

4405

isProfitableToFoldIntoAddressingMode(Instruction *I, ExtAddrMode &AMBefore,

4406

ExtAddrMode &AMAfter) {

4407

if (IgnoreProfitability) return true;

4408

4409

// AMBefore is the addressing mode before this instruction was folded into it,

4410

// and AMAfter is the addressing mode after the instruction was folded. Get

4411

// the set of registers referenced by AMAfter and subtract out those

4412

// referenced by AMBefore: this is the set of values which folding in this

4413

// address extends the lifetime of.

4414

4415

// Note that there are only two potential values being referenced here,

4416

// BaseReg and ScaleReg (global addresses are always available, as are any

4417

// folded immediates).

4418

Value *BaseReg = AMAfter.BaseReg, *ScaledReg = AMAfter.ScaledReg;

4419

4420

// If the BaseReg or ScaledReg was referenced by the previous addrmode, their

4421

// lifetime wasn't extended by adding this instruction.

4422

if (valueAlreadyLiveAtInst(BaseReg, AMBefore.BaseReg, AMBefore.ScaledReg))

4423

BaseReg = nullptr;

4424

if (valueAlreadyLiveAtInst(ScaledReg, AMBefore.BaseReg, AMBefore.ScaledReg))

4425

ScaledReg = nullptr;

4426

4427

// If folding this instruction (and it's subexprs) didn't extend any live

4428

// ranges, we're ok with it.

4429

if (!BaseReg && !ScaledReg)

4430

return true;

4431

4432

// If all uses of this instruction can have the address mode sunk into them,

4433

// we can remove the addressing mode and effectively trade one live register

4434

// for another (at worst.) In this context, folding an addressing mode into

4435

// the use is just a particularly nice way of sinking it.

4436

SmallVector<std::pair<Instruction*,unsigned>, 16> MemoryUses;

4437

SmallPtrSet<Instruction*, 16> ConsideredInsts;

4438

if (FindAllMemoryUses(I, MemoryUses, ConsideredInsts, TLI, TRI))

4439

return false; // Has a non-memory, non-foldable use!

4440

4441

// Now that we know that all uses of this instruction are part of a chain of

4442

// computation involving only operations that could theoretically be folded

4443

// into a memory use, loop over each of these memory operation uses and see

4444

// if they could *actually* fold the instruction. The assumption is that

4445

// addressing modes are cheap and that duplicating the computation involved

4446

// many times is worthwhile, even on a fastpath. For sinking candidates

4447

// (i.e. cold call sites), this serves as a way to prevent excessive code

4448

// growth since most architectures have some reasonable small and fast way to

4449

// compute an effective address. (i.e LEA on x86)

4450

SmallVector<Instruction*, 32> MatchedAddrModeInsts;

4451

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

4452

Instruction *User = MemoryUses[i].first;

4453

unsigned OpNo = MemoryUses[i].second;

4454

4455

// Get the access type of this use. If the use isn't a pointer, we don't

4456

// know what it accesses.

4457

Value *Address = User->getOperand(OpNo);

4458

PointerType *AddrTy = dyn_cast<PointerType>(Address->getType());

4459

if (!AddrTy)

4460

return false;

4461

Type *AddressAccessTy = AddrTy->getElementType();

4462

unsigned AS = AddrTy->getAddressSpace();

4463

4464

// Do a match against the root of this address, ignoring profitability. This

4465

// will tell us if the addressing mode for the memory operation will

4466

// *actually* cover the shared instruction.

4467

ExtAddrMode Result;

4468

TypePromotionTransaction::ConstRestorationPt LastKnownGood =

4469

TPT.getRestorationPoint();

4470

AddressingModeMatcher Matcher(MatchedAddrModeInsts, TLI, TRI,

4471

AddressAccessTy, AS,

4472

MemoryInst, Result, InsertedInsts,

4473

PromotedInsts, TPT);

4474

Matcher.IgnoreProfitability = true;

4475

bool Success = Matcher.matchAddr(Address, 0);

4476

4477

4478

// The match was to check the profitability, the changes made are not

4479

// part of the original matcher. Therefore, they should be dropped

4480

// otherwise the original matcher will not present the right state.

4481

TPT.rollback(LastKnownGood);

4482

4483

// If the match didn't cover I, then it won't be shared by it.

4484

if (!is_contained(MatchedAddrModeInsts, I))

4485

return false;

4486

4487

MatchedAddrModeInsts.clear();

4488

}

4489

4490

return true;

4491

}

4492

4493

/// Return true if the specified values are defined in a

4494

/// different basic block than BB.

4495

static bool IsNonLocalValue(Value *V, BasicBlock *BB) {

4496

if (Instruction *I = dyn_cast<Instruction>(V))

4497

return I->getParent() != BB;

4498

return false;

4499

}

4500

4501

/// Sink addressing mode computation immediate before MemoryInst if doing so

4502

/// can be done without increasing register pressure. The need for the

4503

/// register pressure constraint means this can end up being an all or nothing

4504

/// decision for all uses of the same addressing computation.

4505

///

4506

/// Load and Store Instructions often have addressing modes that can do

4507

/// significant amounts of computation. As such, instruction selection will try

4508

/// to get the load or store to do as much computation as possible for the

4509

/// program. The problem is that isel can only see within a single block. As

4510

/// such, we sink as much legal addressing mode work into the block as possible.

4511

///

4512

/// This method is used to optimize both load/store and inline asms with memory

4513

/// operands. It's also used to sink addressing computations feeding into cold

4514

/// call sites into their (cold) basic block.

4515

///

4516

/// The motivation for handling sinking into cold blocks is that doing so can

4517

/// both enable other address mode sinking (by satisfying the register pressure

4518

/// constraint above), and reduce register pressure globally (by removing the

4519

/// addressing mode computation from the fast path entirely.).

4520

bool CodeGenPrepare::optimizeMemoryInst(Instruction *MemoryInst, Value *Addr,

4521

Type *AccessTy, unsigned AddrSpace) {

4522

Value *Repl = Addr;

4523

4524

// Try to collapse single-value PHI nodes. This is necessary to undo

4525

// unprofitable PRE transformations.

4526

SmallVector<Value*, 8> worklist;

4527

SmallPtrSet<Value*, 16> Visited;

4528

worklist.push_back(Addr);

4529

4530

// Use a worklist to iteratively look through PHI and select nodes, and

4531

// ensure that the addressing mode obtained from the non-PHI/select roots of

4532

// the graph are compatible.

4533

bool PhiOrSelectSeen = false;

4534

SmallVector<Instruction*, 16> AddrModeInsts;

4535

AddressingModeCombiner AddrModes;

4536

TypePromotionTransaction TPT(RemovedInsts);

4537

TypePromotionTransaction::ConstRestorationPt LastKnownGood =

4538

TPT.getRestorationPoint();

4539

while (!worklist.empty()) {

4540

Value *V = worklist.back();

4541

worklist.pop_back();

4542

4543

// We allow traversing cyclic Phi nodes.

4544

// In case of success after this loop we ensure that traversing through

4545

// Phi nodes ends up with all cases to compute address of the form

4546

// BaseGV + Base + Scale * Index + Offset

4547

// where Scale and Offset are constans and BaseGV, Base and Index

4548

// are exactly the same Values in all cases.

4549

// It means that BaseGV, Scale and Offset dominate our memory instruction

4550

// and have the same value as they had in address computation represented

4551

// as Phi. So we can safely sink address computation to memory instruction.

4552

if (!Visited.insert(V).second)

4553

continue;

4554

4555

// For a PHI node, push all of its incoming values.

4556

if (PHINode *P = dyn_cast<PHINode>(V)) {

4557

for (Value *IncValue : P->incoming_values())

4558

worklist.push_back(IncValue);

4559

PhiOrSelectSeen = true;

4560

continue;

4561

}

4562

// Similar for select.

4563

if (SelectInst *SI = dyn_cast<SelectInst>(V)) {

4564

worklist.push_back(SI->getFalseValue());

4565

worklist.push_back(SI->getTrueValue());

4566

PhiOrSelectSeen = true;

4567

continue;

4568

}

4569

4570

// For non-PHIs, determine the addressing mode being computed. Note that

4571

// the result may differ depending on what other uses our candidate

4572

// addressing instructions might have.

4573

AddrModeInsts.clear();

4574

ExtAddrMode NewAddrMode = AddressingModeMatcher::Match(

4575

V, AccessTy, AddrSpace, MemoryInst, AddrModeInsts, *TLI, *TRI,

4576

InsertedInsts, PromotedInsts, TPT);

4577

NewAddrMode.OriginalValue = V;

4578

4579

if (!AddrModes.addNewAddrMode(NewAddrMode))

4580

break;

4581

}

4582

4583

// Try to combine the AddrModes we've collected. If we couldn't collect any,

4584

// or we have multiple but either couldn't combine them or combining them

4585

// wouldn't do anything useful, bail out now.

4586

if (!AddrModes.combineAddrModes()) {

4587

TPT.rollback(LastKnownGood);

4588

return false;

4589

}

4590

TPT.commit();

4591

4592

// Get the combined AddrMode (or the only AddrMode, if we only had one).

4593

ExtAddrMode AddrMode = AddrModes.getAddrMode();

4594

4595

// If all the instructions matched are already in this BB, don't do anything.

4596

// If we saw a Phi node then it is not local definitely, and if we saw a select

4597

// then we want to push the address calculation past it even if it's already

4598

// in this BB.

4599

if (!PhiOrSelectSeen && none_of(AddrModeInsts, [&](Value *V) {

4600

return IsNonLocalValue(V, MemoryInst->getParent());

4601

})) {

4602

DEBUG(dbgs() << "CGP: Found local addrmode: " << AddrMode << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Found local addrmode: "
<< AddrMode << "\n"; } } while (false);

4603

return false;

4604

}

4605

4606

// Insert this computation right after this user. Since our caller is

4607

// scanning from the top of the BB to the bottom, reuse of the expr are

4608

// guaranteed to happen later.

4609

IRBuilder<> Builder(MemoryInst);

4610

4611

// Now that we determined the addressing expression we want to use and know

4612

// that we have to sink it into this block. Check to see if we have already

4613

// done this for some other load/store instr in this block. If so, reuse the

4614

// computation.

4615

Value *&SunkAddr = SunkAddrs[Addr];

4616

if (SunkAddr) {

4617

DEBUG(dbgs() << "CGP: Reusing nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)

4618

<< *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: Reusing nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false);

4619

if (SunkAddr->getType() != Addr->getType())

4620

SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());

4621

} else if (AddrSinkUsingGEPs ||

4622

(!AddrSinkUsingGEPs.getNumOccurrences() && TM &&

4623

SubtargetInfo->useAA())) {

4624

// By default, we use the GEP-based method when AA is used later. This

4625

// prevents new inttoptr/ptrtoint pairs from degrading AA capabilities.

4626

DEBUG(dbgs() << "CGP: SINKING nonlocal addrmode: " << AddrMode << " for "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false)

4627

<< *MemoryInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "CGP: SINKING nonlocal addrmode: "
<< AddrMode << " for " << *MemoryInst <<
"\n"; } } while (false);

4628

Type *IntPtrTy = DL->getIntPtrType(Addr->getType());

4629

Value *ResultPtr = nullptr, *ResultIndex = nullptr;

4630

4631

// First, find the pointer.

4632

if (AddrMode.BaseReg && AddrMode.BaseReg->getType()->isPointerTy()) {

4633

ResultPtr = AddrMode.BaseReg;

4634

AddrMode.BaseReg = nullptr;

4635

}

4636

4637

if (AddrMode.Scale && AddrMode.ScaledReg->getType()->isPointerTy()) {

4638

// We can't add more than one pointer together, nor can we scale a

4639

// pointer (both of which seem meaningless).

4640

if (ResultPtr || AddrMode.Scale != 1)

4641

return false;

4642

4643

ResultPtr = AddrMode.ScaledReg;

4644

AddrMode.Scale = 0;

4645

}

4646

4647

// It is only safe to sign extend the BaseReg if we know that the math

4648

// required to create it did not overflow before we extend it. Since

4649

// the original IR value was tossed in favor of a constant back when

4650

// the AddrMode was created we need to bail out gracefully if widths

4651

// do not match instead of extending it.

4652

4653

// (See below for code to add the scale.)

4654

if (AddrMode.Scale) {

4655

Type *ScaledRegTy = AddrMode.ScaledReg->getType();

4656

if (cast<IntegerType>(IntPtrTy)->getBitWidth() >

4657

cast<IntegerType>(ScaledRegTy)->getBitWidth())

4658

return false;

4659

}

4660

4661

if (AddrMode.BaseGV) {

4662

if (ResultPtr)

4663

return false;

4664

4665

ResultPtr = AddrMode.BaseGV;

4666

}

4667

4668

// If the real base value actually came from an inttoptr, then the matcher

4669

// will look through it and provide only the integer value. In that case,

4670

// use it here.

4671

if (!DL->isNonIntegralPointerType(Addr->getType())) {

4672

if (!ResultPtr && AddrMode.BaseReg) {

4673

ResultPtr = Builder.CreateIntToPtr(AddrMode.BaseReg, Addr->getType(),

4674

"sunkaddr");

4675

AddrMode.BaseReg = nullptr;

4676

} else if (!ResultPtr && AddrMode.Scale == 1) {

4677

ResultPtr = Builder.CreateIntToPtr(AddrMode.ScaledReg, Addr->getType(),

4678

"sunkaddr");

4679

AddrMode.Scale = 0;

4680

}

4681

}

4682

4683

if (!ResultPtr &&

4684

!AddrMode.BaseReg && !AddrMode.Scale && !AddrMode.BaseOffs) {

4685

SunkAddr = Constant::getNullValue(Addr->getType());

4686

} else if (!ResultPtr) {

4687

return false;

4688

} else {

4689

Type *I8PtrTy =

4690

Builder.getInt8PtrTy(Addr->getType()->getPointerAddressSpace());

4691

Type *I8Ty = Builder.getInt8Ty();

4692

4693

// Start with the base register. Do this first so that subsequent address

4694

// matching finds it last, which will prevent it from trying to match it

4695

// as the scaled value in case it happens to be a mul. That would be

4696

// problematic if we've sunk a different mul for the scale, because then

4697

// we'd end up sinking both muls.

4698

if (AddrMode.BaseReg) {

4699

Value *V = AddrMode.BaseReg;

4700

if (V->getType() != IntPtrTy)

4701

V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");

4702

4703

ResultIndex = V;

4704

}

4705

4706

// Add the scale value.

4707

if (AddrMode.Scale) {

4708

Value *V = AddrMode.ScaledReg;

4709

if (V->getType() == IntPtrTy) {

4710

// done.

4711

} else {

4712

assert(cast<IntegerType>(IntPtrTy)->getBitWidth() <((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 4714, __PRETTY_FUNCTION__))

4713

cast<IntegerType>(V->getType())->getBitWidth() &&((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 4714, __PRETTY_FUNCTION__))

4714

"We can't transform if ScaledReg is too narrow")((cast<IntegerType>(IntPtrTy)->getBitWidth() < cast
<IntegerType>(V->getType())->getBitWidth() &&
"We can't transform if ScaledReg is too narrow") ? static_cast
<void> (0) : __assert_fail ("cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth() && \"We can't transform if ScaledReg is too narrow\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 4714, __PRETTY_FUNCTION__));

4715

V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");

4716

}

4717

4718

if (AddrMode.Scale != 1)

4719

V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),

4720

"sunkaddr");

4721

if (ResultIndex)

4722

ResultIndex = Builder.CreateAdd(ResultIndex, V, "sunkaddr");

4723

else

4724

ResultIndex = V;

4725

}

4726

4727

// Add in the Base Offset if present.

4728

if (AddrMode.BaseOffs) {

4729

Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);

4730

if (ResultIndex) {

4731

// We need to add this separately from the scale above to help with

4732

// SDAG consecutive load/store merging.

4733

if (ResultPtr->getType() != I8PtrTy)

4734

ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);

4735

ResultPtr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");

4736

}

4737

4738

ResultIndex = V;

4739

}

4740

4741

if (!ResultIndex) {

4742

SunkAddr = ResultPtr;

4743

} else {

4744

if (ResultPtr->getType() != I8PtrTy)

4745

ResultPtr = Builder.CreatePointerCast(ResultPtr, I8PtrTy);

4746

SunkAddr = Builder.CreateGEP(I8Ty, ResultPtr, ResultIndex, "sunkaddr");

4747

}

4748

4749

if (SunkAddr->getType() != Addr->getType())

4750

SunkAddr = Builder.CreatePointerCast(SunkAddr, Addr->getType());

4751

}

4752

} else {

4753

// We'd require a ptrtoint/inttoptr down the line, which we can't do for

4754

// non-integral pointers, so in that case bail out now.

4755

Type *BaseTy = AddrMode.BaseReg ? AddrMode.BaseReg->getType() : nullptr;

4756

Type *ScaleTy = AddrMode.Scale ? AddrMode.ScaledReg->getType() : nullptr;

4757

PointerType *BasePtrTy = dyn_cast_or_null<PointerType>(BaseTy);

4758

PointerType *ScalePtrTy = dyn_cast_or_null<PointerType>(ScaleTy);

4759

if (DL->isNonIntegralPointerType(Addr->getType()) ||

4760

(BasePtrTy && DL->isNonIntegralPointerType(BasePtrTy)) ||

4761

(ScalePtrTy && DL->isNonIntegralPointerType(ScalePtrTy)) ||

4762

(AddrMode.BaseGV &&

4763

DL->isNonIntegralPointerType(AddrMode.BaseGV->getType())))

4764

return false;

4765

4766

4767

4768

Type *IntPtrTy = DL->getIntPtrType(Addr->getType());

4769

Value *Result = nullptr;

4770

4771

// Start with the base register. Do this first so that subsequent address

4772

// matching finds it last, which will prevent it from trying to match it

4773

// as the scaled value in case it happens to be a mul. That would be

4774

// problematic if we've sunk a different mul for the scale, because then

4775

// we'd end up sinking both muls.

4776

if (AddrMode.BaseReg) {

4777

Value *V = AddrMode.BaseReg;

4778

if (V->getType()->isPointerTy())

4779

V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");

4780

if (V->getType() != IntPtrTy)

4781

V = Builder.CreateIntCast(V, IntPtrTy, /*isSigned=*/true, "sunkaddr");

4782

Result = V;

4783

}

4784

4785

// Add the scale value.

4786

if (AddrMode.Scale) {

4787

Value *V = AddrMode.ScaledReg;

4788

if (V->getType() == IntPtrTy) {

4789

// done.

4790

} else if (V->getType()->isPointerTy()) {

4791

V = Builder.CreatePtrToInt(V, IntPtrTy, "sunkaddr");

4792

} else if (cast<IntegerType>(IntPtrTy)->getBitWidth() <

4793

cast<IntegerType>(V->getType())->getBitWidth()) {

4794

V = Builder.CreateTrunc(V, IntPtrTy, "sunkaddr");

4795

} else {

4796

// It is only safe to sign extend the BaseReg if we know that the math

4797

// required to create it did not overflow before we extend it. Since

4798

// the original IR value was tossed in favor of a constant back when

4799

// the AddrMode was created we need to bail out gracefully if widths

4800

// do not match instead of extending it.

4801

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

4802

if (I && (Result != AddrMode.BaseReg))

4803

I->eraseFromParent();

4804

return false;

4805

}

4806

if (AddrMode.Scale != 1)

4807

V = Builder.CreateMul(V, ConstantInt::get(IntPtrTy, AddrMode.Scale),

4808

"sunkaddr");

4809

if (Result)

4810

Result = Builder.CreateAdd(Result, V, "sunkaddr");

4811

else

4812

Result = V;

4813

}

4814

4815

// Add in the BaseGV if present.

4816

if (AddrMode.BaseGV) {

4817

Value *V = Builder.CreatePtrToInt(AddrMode.BaseGV, IntPtrTy, "sunkaddr");

4818

if (Result)

4819

Result = Builder.CreateAdd(Result, V, "sunkaddr");

4820

else

4821

Result = V;

4822

}

4823

4824

// Add in the Base Offset if present.

4825

if (AddrMode.BaseOffs) {

4826

Value *V = ConstantInt::get(IntPtrTy, AddrMode.BaseOffs);

4827

if (Result)

4828

Result = Builder.CreateAdd(Result, V, "sunkaddr");

4829

else

4830

Result = V;

4831

}

4832

4833

if (!Result)

4834

SunkAddr = Constant::getNullValue(Addr->getType());

4835

else

4836

SunkAddr = Builder.CreateIntToPtr(Result, Addr->getType(), "sunkaddr");

4837

}

4838

4839

MemoryInst->replaceUsesOfWith(Repl, SunkAddr);

4840

4841

// If we have no uses, recursively delete the value and all dead instructions

4842

// using it.

4843

if (Repl->use_empty()) {

4844

// This can cause recursive deletion, which can invalidate our iterator.

4845

// Use a WeakTrackingVH to hold onto it in case this happens.

4846

Value *CurValue = &*CurInstIterator;

4847

WeakTrackingVH IterHandle(CurValue);

4848

BasicBlock *BB = CurInstIterator->getParent();

4849

4850

RecursivelyDeleteTriviallyDeadInstructions(Repl, TLInfo);

4851

4852

if (IterHandle != CurValue) {

4853

// If the iterator instruction was recursively deleted, start over at the

4854

// start of the block.

4855

CurInstIterator = BB->begin();

4856

SunkAddrs.clear();

4857

}

4858

}

4859

++NumMemoryInsts;

4860

return true;

4861

}

4862

4863

/// If there are any memory operands, use OptimizeMemoryInst to sink their

4864

/// address computing into the block when possible / profitable.

4865

bool CodeGenPrepare::optimizeInlineAsmInst(CallInst *CS) {

4866

bool MadeChange = false;

4867

4868

const TargetRegisterInfo *TRI =

4869

TM->getSubtargetImpl(*CS->getFunction())->getRegisterInfo();

4870

TargetLowering::AsmOperandInfoVector TargetConstraints =

4871

TLI->ParseConstraints(*DL, TRI, CS);

4872

unsigned ArgNo = 0;

4873

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

4874

TargetLowering::AsmOperandInfo &OpInfo = TargetConstraints[i];

4875

4876

// Compute the constraint code and ConstraintType to use.

4877

TLI->ComputeConstraintToUse(OpInfo, SDValue());

4878

4879

if (OpInfo.ConstraintType == TargetLowering::C_Memory &&

4880

OpInfo.isIndirect) {

4881

Value *OpVal = CS->getArgOperand(ArgNo++);

4882

MadeChange |= optimizeMemoryInst(CS, OpVal, OpVal->getType(), ~0u);

4883

} else if (OpInfo.Type == InlineAsm::isInput)

4884

ArgNo++;

4885

}

4886

4887

return MadeChange;

4888

}

4889

4890

/// \brief Check if all the uses of \p Val are equivalent (or free) zero or

4891

/// sign extensions.

4892

static bool hasSameExtUse(Value *Val, const TargetLowering &TLI) {

4893

assert(!Val->use_empty() && "Input must have at least one use")((!Val->use_empty() && "Input must have at least one use"
) ? static_cast<void> (0) : __assert_fail ("!Val->use_empty() && \"Input must have at least one use\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 4893, __PRETTY_FUNCTION__));

4894

const Instruction *FirstUser = cast<Instruction>(*Val->user_begin());

4895

bool IsSExt = isa<SExtInst>(FirstUser);

4896

Type *ExtTy = FirstUser->getType();

4897

for (const User *U : Val->users()) {

4898

const Instruction *UI = cast<Instruction>(U);

4899

if ((IsSExt && !isa<SExtInst>(UI)) || (!IsSExt && !isa<ZExtInst>(UI)))

4900

return false;

4901

Type *CurTy = UI->getType();

4902

// Same input and output types: Same instruction after CSE.

4903

if (CurTy == ExtTy)

4904

continue;

4905

4906

// If IsSExt is true, we are in this situation:

4907

// a = Val

4908

// b = sext ty1 a to ty2

4909

// c = sext ty1 a to ty3

4910

// Assuming ty2 is shorter than ty3, this could be turned into:

4911

// a = Val

4912

// b = sext ty1 a to ty2

4913

// c = sext ty2 b to ty3

4914

// However, the last sext is not free.

4915

if (IsSExt)

4916

return false;

4917

4918

// This is a ZExt, maybe this is free to extend from one type to another.

4919

// In that case, we would not account for a different use.

4920

Type *NarrowTy;

4921

Type *LargeTy;

4922

if (ExtTy->getScalarType()->getIntegerBitWidth() >

4923

CurTy->getScalarType()->getIntegerBitWidth()) {

4924

NarrowTy = CurTy;

4925

LargeTy = ExtTy;

4926

} else {

4927

NarrowTy = ExtTy;

4928

LargeTy = CurTy;

4929

}

4930

4931

if (!TLI.isZExtFree(NarrowTy, LargeTy))

4932

return false;

4933

}

4934

// All uses are the same or can be derived from one another for free.

4935

return true;

4936

}

4937

4938

/// \brief Try to speculatively promote extensions in \p Exts and continue

4939

/// promoting through newly promoted operands recursively as far as doing so is

4940

/// profitable. Save extensions profitably moved up, in \p ProfitablyMovedExts.

4941

/// When some promotion happened, \p TPT contains the proper state to revert

4942

/// them.

4943

///

4944

/// \return true if some promotion happened, false otherwise.

4945

bool CodeGenPrepare::tryToPromoteExts(

4946

TypePromotionTransaction &TPT, const SmallVectorImpl<Instruction *> &Exts,

4947

SmallVectorImpl<Instruction *> &ProfitablyMovedExts,

4948

unsigned CreatedInstsCost) {

4949

bool Promoted = false;

4950

4951

// Iterate over all the extensions to try to promote them.

4952

for (auto I : Exts) {

4953

// Early check if we directly have ext(load).

4954

if (isa<LoadInst>(I->getOperand(0))) {

4955

ProfitablyMovedExts.push_back(I);

4956

continue;

4957

}

4958

4959

// Check whether or not we want to do any promotion. The reason we have

4960

// this check inside the for loop is to catch the case where an extension

4961

// is directly fed by a load because in such case the extension can be moved

4962

// up without any promotion on its operands.

4963

if (!TLI || !TLI->enableExtLdPromotion() || DisableExtLdPromotion)

4964

return false;

4965

4966

// Get the action to perform the promotion.

4967

TypePromotionHelper::Action TPH =

4968

TypePromotionHelper::getAction(I, InsertedInsts, *TLI, PromotedInsts);

4969

// Check if we can promote.

4970

if (!TPH) {

4971

// Save the current extension as we cannot move up through its operand.

4972

ProfitablyMovedExts.push_back(I);

4973

continue;

4974

}

4975

4976

// Save the current state.

4977

TypePromotionTransaction::ConstRestorationPt LastKnownGood =

4978

TPT.getRestorationPoint();

4979

SmallVector<Instruction *, 4> NewExts;

4980

unsigned NewCreatedInstsCost = 0;

4981

unsigned ExtCost = !TLI->isExtFree(I);

4982

// Promote.

4983

Value *PromotedVal = TPH(I, TPT, PromotedInsts, NewCreatedInstsCost,

4984

&NewExts, nullptr, *TLI);

4985

assert(PromotedVal &&((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 4986, __PRETTY_FUNCTION__))

4986

"TypePromotionHelper should have filtered out those cases")((PromotedVal && "TypePromotionHelper should have filtered out those cases"
) ? static_cast<void> (0) : __assert_fail ("PromotedVal && \"TypePromotionHelper should have filtered out those cases\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 4986, __PRETTY_FUNCTION__));

4987

4988

// We would be able to merge only one extension in a load.

4989

// Therefore, if we have more than 1 new extension we heuristically

4990

// cut this search path, because it means we degrade the code quality.

4991

// With exactly 2, the transformation is neutral, because we will merge

4992

// one extension but leave one. However, we optimistically keep going,

4993

// because the new extension may be removed too.

4994

long long TotalCreatedInstsCost = CreatedInstsCost + NewCreatedInstsCost;

4995

// FIXME: It would be possible to propagate a negative value instead of

4996

// conservatively ceiling it to 0.

4997

TotalCreatedInstsCost =

4998

std::max((long long)0, (TotalCreatedInstsCost - ExtCost));

4999

if (!StressExtLdPromotion &&

5000

(TotalCreatedInstsCost > 1 ||

5001

!isPromotedInstructionLegal(*TLI, *DL, PromotedVal))) {

5002

// This promotion is not profitable, rollback to the previous state, and

5003

// save the current extension in ProfitablyMovedExts as the latest

5004

// speculative promotion turned out to be unprofitable.

5005

TPT.rollback(LastKnownGood);

5006

ProfitablyMovedExts.push_back(I);

5007

continue;

5008

}

5009

// Continue promoting NewExts as far as doing so is profitable.

5010

SmallVector<Instruction *, 2> NewlyMovedExts;

5011

(void)tryToPromoteExts(TPT, NewExts, NewlyMovedExts, TotalCreatedInstsCost);

5012

bool NewPromoted = false;

5013

for (auto ExtInst : NewlyMovedExts) {

5014

Instruction *MovedExt = cast<Instruction>(ExtInst);

5015

Value *ExtOperand = MovedExt->getOperand(0);

5016

// If we have reached to a load, we need this extra profitability check

5017

// as it could potentially be merged into an ext(load).

5018

if (isa<LoadInst>(ExtOperand) &&

5019

!(StressExtLdPromotion || NewCreatedInstsCost <= ExtCost ||

5020

(ExtOperand->hasOneUse() || hasSameExtUse(ExtOperand, *TLI))))

5021

continue;

5022

5023

ProfitablyMovedExts.push_back(MovedExt);

5024

NewPromoted = true;

5025

}

5026

5027

// If none of speculative promotions for NewExts is profitable, rollback

5028

// and save the current extension (I) as the last profitable extension.

5029

if (!NewPromoted) {

5030

TPT.rollback(LastKnownGood);

5031

ProfitablyMovedExts.push_back(I);

5032

continue;

5033

}

5034

// The promotion is profitable.

5035

Promoted = true;

5036

}

5037

return Promoted;

5038

}

5039

5040

/// Merging redundant sexts when one is dominating the other.

5041

bool CodeGenPrepare::mergeSExts(Function &F) {

5042

DominatorTree DT(F);

5043

bool Changed = false;

5044

for (auto &Entry : ValToSExtendedUses) {

5045

SExts &Insts = Entry.second;

5046

SExts CurPts;

5047

for (Instruction *Inst : Insts) {

5048

if (RemovedInsts.count(Inst) || !isa<SExtInst>(Inst) ||

5049

Inst->getOperand(0) != Entry.first)

5050

continue;

5051

bool inserted = false;

5052

for (auto &Pt : CurPts) {

5053

if (DT.dominates(Inst, Pt)) {

5054

Pt->replaceAllUsesWith(Inst);

5055

RemovedInsts.insert(Pt);

5056

Pt->removeFromParent();

5057

Pt = Inst;

5058

inserted = true;

5059

Changed = true;

5060

break;

5061

}

5062

if (!DT.dominates(Pt, Inst))

5063

// Give up if we need to merge in a common dominator as the

5064

// expermients show it is not profitable.

5065

continue;

5066

Inst->replaceAllUsesWith(Pt);

5067

RemovedInsts.insert(Inst);

5068

Inst->removeFromParent();

5069

inserted = true;

5070

Changed = true;

5071

break;

5072

}

5073

if (!inserted)

5074

CurPts.push_back(Inst);

5075

}

5076

}

5077

return Changed;

5078

}

5079

5080

/// Return true, if an ext(load) can be formed from an extension in

5081

/// \p MovedExts.

5082

bool CodeGenPrepare::canFormExtLd(

5083

const SmallVectorImpl<Instruction *> &MovedExts, LoadInst *&LI,

5084

Instruction *&Inst, bool HasPromoted) {

5085

for (auto *MovedExtInst : MovedExts) {

5086

if (isa<LoadInst>(MovedExtInst->getOperand(0))) {

5087

LI = cast<LoadInst>(MovedExtInst->getOperand(0));

5088

Inst = MovedExtInst;

5089

break;

5090

}

5091

}

5092

if (!LI)

5093

return false;

5094

5095

// If they're already in the same block, there's nothing to do.

5096

// Make the cheap checks first if we did not promote.

5097

// If we promoted, we need to check if it is indeed profitable.

5098

if (!HasPromoted && LI->getParent() == Inst->getParent())

5099

return false;

5100

5101

return TLI->isExtLoad(LI, Inst, *DL);

5102

}

5103

5104

/// Move a zext or sext fed by a load into the same basic block as the load,

5105

/// unless conditions are unfavorable. This allows SelectionDAG to fold the

5106

/// extend into the load.

5107

///

5108

/// E.g.,

5109

/// \code

5110

/// %ld = load i32* %addr

5111

/// %add = add nuw i32 %ld, 4

5112

/// %zext = zext i32 %add to i64

5113

// \endcode

5114

/// =>

5115

/// \code

5116

/// %ld = load i32* %addr

5117

/// %zext = zext i32 %ld to i64

5118

/// %add = add nuw i64 %zext, 4

5119

/// \encode

5120

/// Note that the promotion in %add to i64 is done in tryToPromoteExts(), which

5121

/// allow us to match zext(load i32*) to i64.

5122

///

5123

/// Also, try to promote the computations used to obtain a sign extended

5124

/// value used into memory accesses.

5125

/// E.g.,

5126

/// \code

5127

/// a = add nsw i32 b, 3

5128

/// d = sext i32 a to i64

5129

/// e = getelementptr ..., i64 d

5130

/// \endcode

5131

/// =>

5132

/// \code

5133

/// f = sext i32 b to i64

5134

/// a = add nsw i64 f, 3

5135

/// e = getelementptr ..., i64 a

5136

/// \endcode

5137

///

5138

/// \p Inst[in/out] the extension may be modified during the process if some

5139

/// promotions apply.

5140

bool CodeGenPrepare::optimizeExt(Instruction *&Inst) {

5141

// ExtLoad formation and address type promotion infrastructure requires TLI to

5142

// be effective.

5143

if (!TLI)

5144

return false;

5145

5146

bool AllowPromotionWithoutCommonHeader = false;

5147

/// See if it is an interesting sext operations for the address type

5148

/// promotion before trying to promote it, e.g., the ones with the right

5149

/// type and used in memory accesses.

5150

bool ATPConsiderable = TTI->shouldConsiderAddressTypePromotion(

5151

*Inst, AllowPromotionWithoutCommonHeader);

5152

TypePromotionTransaction TPT(RemovedInsts);

5153

TypePromotionTransaction::ConstRestorationPt LastKnownGood =

5154

TPT.getRestorationPoint();

5155

SmallVector<Instruction *, 1> Exts;

5156

SmallVector<Instruction *, 2> SpeculativelyMovedExts;

5157

Exts.push_back(Inst);

5158

5159

bool HasPromoted = tryToPromoteExts(TPT, Exts, SpeculativelyMovedExts);

5160

5161

// Look for a load being extended.

5162

LoadInst *LI = nullptr;

5163

Instruction *ExtFedByLoad;

5164

5165

// Try to promote a chain of computation if it allows to form an extended

5166

// load.

5167

if (canFormExtLd(SpeculativelyMovedExts, LI, ExtFedByLoad, HasPromoted)) {

5168

assert(LI && ExtFedByLoad && "Expect a valid load and extension")((LI && ExtFedByLoad && "Expect a valid load and extension"
) ? static_cast<void> (0) : __assert_fail ("LI && ExtFedByLoad && \"Expect a valid load and extension\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 5168, __PRETTY_FUNCTION__));

5169

TPT.commit();

5170

// Move the extend into the same block as the load

5171

ExtFedByLoad->moveAfter(LI);

5172

// CGP does not check if the zext would be speculatively executed when moved

5173

// to the same basic block as the load. Preserving its original location

5174

// would pessimize the debugging experience, as well as negatively impact

5175

// the quality of sample pgo. We don't want to use "line 0" as that has a

5176

// size cost in the line-table section and logically the zext can be seen as

5177

// part of the load. Therefore we conservatively reuse the same debug

5178

// location for the load and the zext.

5179

ExtFedByLoad->setDebugLoc(LI->getDebugLoc());

5180

++NumExtsMoved;

5181

Inst = ExtFedByLoad;

5182

return true;

5183

}

5184

5185

// Continue promoting SExts if known as considerable depending on targets.

5186

if (ATPConsiderable &&

5187

performAddressTypePromotion(Inst, AllowPromotionWithoutCommonHeader,

5188

HasPromoted, TPT, SpeculativelyMovedExts))

5189

return true;

5190

5191

TPT.rollback(LastKnownGood);

5192

return false;

5193

}

5194

5195

// Perform address type promotion if doing so is profitable.

5196

// If AllowPromotionWithoutCommonHeader == false, we should find other sext

5197

// instructions that sign extended the same initial value. However, if

5198

// AllowPromotionWithoutCommonHeader == true, we expect promoting the

5199

// extension is just profitable.

5200

bool CodeGenPrepare::performAddressTypePromotion(

5201

Instruction *&Inst, bool AllowPromotionWithoutCommonHeader,

5202

bool HasPromoted, TypePromotionTransaction &TPT,

5203

SmallVectorImpl<Instruction *> &SpeculativelyMovedExts) {

5204

bool Promoted = false;

5205

SmallPtrSet<Instruction *, 1> UnhandledExts;

5206

bool AllSeenFirst = true;

5207

for (auto I : SpeculativelyMovedExts) {

5208

Value *HeadOfChain = I->getOperand(0);

5209

DenseMap<Value *, Instruction *>::iterator AlreadySeen =

5210

SeenChainsForSExt.find(HeadOfChain);

5211

// If there is an unhandled SExt which has the same header, try to promote

5212

// it as well.

5213

if (AlreadySeen != SeenChainsForSExt.end()) {

5214

if (AlreadySeen->second != nullptr)

5215

UnhandledExts.insert(AlreadySeen->second);

5216

AllSeenFirst = false;

5217

}

5218

}

5219

5220

if (!AllSeenFirst || (AllowPromotionWithoutCommonHeader &&

5221

SpeculativelyMovedExts.size() == 1)) {

5222

TPT.commit();

5223

if (HasPromoted)

5224

Promoted = true;

5225

for (auto I : SpeculativelyMovedExts) {

5226

Value *HeadOfChain = I->getOperand(0);

5227

SeenChainsForSExt[HeadOfChain] = nullptr;

5228

ValToSExtendedUses[HeadOfChain].push_back(I);

5229

}

5230

// Update Inst as promotion happen.

5231

Inst = SpeculativelyMovedExts.pop_back_val();

5232

} else {

5233

// This is the first chain visited from the header, keep the current chain

5234

// as unhandled. Defer to promote this until we encounter another SExt

5235

// chain derived from the same header.

5236

for (auto I : SpeculativelyMovedExts) {

5237

Value *HeadOfChain = I->getOperand(0);

5238

SeenChainsForSExt[HeadOfChain] = Inst;

5239

}

5240

return false;

5241

}

5242

5243

if (!AllSeenFirst && !UnhandledExts.empty())

5244

for (auto VisitedSExt : UnhandledExts) {

5245

if (RemovedInsts.count(VisitedSExt))

5246

continue;

5247

TypePromotionTransaction TPT(RemovedInsts);

5248

SmallVector<Instruction *, 1> Exts;

5249

SmallVector<Instruction *, 2> Chains;

5250

Exts.push_back(VisitedSExt);

5251

bool HasPromoted = tryToPromoteExts(TPT, Exts, Chains);

5252

TPT.commit();

5253

if (HasPromoted)

5254

Promoted = true;

5255

for (auto I : Chains) {

5256

Value *HeadOfChain = I->getOperand(0);

5257

// Mark this as handled.

5258

SeenChainsForSExt[HeadOfChain] = nullptr;

5259

ValToSExtendedUses[HeadOfChain].push_back(I);

5260

}

5261

}

5262

return Promoted;

5263

}

5264

5265

bool CodeGenPrepare::optimizeExtUses(Instruction *I) {

5266

BasicBlock *DefBB = I->getParent();

5267

5268

// If the result of a {s|z}ext and its source are both live out, rewrite all

5269

// other uses of the source with result of extension.

5270

Value *Src = I->getOperand(0);

5271

if (Src->hasOneUse())

5272

return false;

5273

5274

// Only do this xform if truncating is free.

5275

if (TLI && !TLI->isTruncateFree(I->getType(), Src->getType()))

5276

return false;

5277

5278

// Only safe to perform the optimization if the source is also defined in

5279

// this block.

5280

if (!isa<Instruction>(Src) || DefBB != cast<Instruction>(Src)->getParent())

5281

return false;

5282

5283

bool DefIsLiveOut = false;

5284

for (User *U : I->users()) {

5285

Instruction *UI = cast<Instruction>(U);

5286

5287

// Figure out which BB this ext is used in.

5288

BasicBlock *UserBB = UI->getParent();

5289

if (UserBB == DefBB) continue;

5290

DefIsLiveOut = true;

5291

break;

5292

}

5293

if (!DefIsLiveOut)

5294

return false;

5295

5296

// Make sure none of the uses are PHI nodes.

5297

for (User *U : Src->users()) {

5298

Instruction *UI = cast<Instruction>(U);

5299

BasicBlock *UserBB = UI->getParent();

5300

if (UserBB == DefBB) continue;

5301

// Be conservative. We don't want this xform to end up introducing

5302

// reloads just before load / store instructions.

5303

if (isa<PHINode>(UI) || isa<LoadInst>(UI) || isa<StoreInst>(UI))

5304

return false;

5305

}

5306

5307

// InsertedTruncs - Only insert one trunc in each block once.

5308

DenseMap<BasicBlock*, Instruction*> InsertedTruncs;

5309

5310

bool MadeChange = false;

5311

for (Use &U : Src->uses()) {

5312

Instruction *User = cast<Instruction>(U.getUser());

5313

5314

// Figure out which BB this ext is used in.

5315

BasicBlock *UserBB = User->getParent();

5316

if (UserBB == DefBB) continue;

5317

5318

// Both src and def are live in this block. Rewrite the use.

5319

Instruction *&InsertedTrunc = InsertedTruncs[UserBB];

5320

5321

if (!InsertedTrunc) {

5322

BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();

5323

5324

InsertedTrunc = new TruncInst(I, Src->getType(), "", &*InsertPt);

5325

InsertedInsts.insert(InsertedTrunc);

5326

}

5327

5328

// Replace a use of the {s|z}ext source with a use of the result.

5329

U = InsertedTrunc;

5330

++NumExtUses;

5331

MadeChange = true;

5332

}

5333

5334

return MadeChange;

5335

}

5336

5337

// Find loads whose uses only use some of the loaded value's bits. Add an "and"

5338

// just after the load if the target can fold this into one extload instruction,

5339

// with the hope of eliminating some of the other later "and" instructions using

5340

// the loaded value. "and"s that are made trivially redundant by the insertion

5341

// of the new "and" are removed by this function, while others (e.g. those whose

5342

// path from the load goes through a phi) are left for isel to potentially

5343

// remove.

5344

5345

// For example:

5346

5347

// b0:

5348

// x = load i32

5349

// ...

5350

// b1:

5351

// y = and x, 0xff

5352

// z = use y

5353

5354

// becomes:

5355

5356

// b0:

5357

// x = load i32

5358

// x' = and x, 0xff

5359

// ...

5360

// b1:

5361

// z = use x'

5362

5363

// whereas:

5364

5365

// b0:

5366

// x1 = load i32

5367

// ...

5368

// b1:

5369

// x2 = load i32

5370

// ...

5371

// b2:

5372

// x = phi x1, x2

5373

// y = and x, 0xff

5374

5375

// becomes (after a call to optimizeLoadExt for each load):

5376

5377

// b0:

5378

// x1 = load i32

5379

// x1' = and x1, 0xff

5380

// ...

5381

// b1:

5382

// x2 = load i32

5383

// x2' = and x2, 0xff

5384

// ...

5385

// b2:

5386

// x = phi x1', x2'

5387

// y = and x, 0xff

5388

bool CodeGenPrepare::optimizeLoadExt(LoadInst *Load) {

5389

if (!Load->isSimple() ||

5390

!(Load->getType()->isIntegerTy() || Load->getType()->isPointerTy()))

5391

return false;

5392

5393

// Skip loads we've already transformed.

5394

if (Load->hasOneUse() &&

5395

InsertedInsts.count(cast<Instruction>(*Load->user_begin())))

5396

return false;

5397

5398

// Look at all uses of Load, looking through phis, to determine how many bits

5399

// of the loaded value are needed.

5400

SmallVector<Instruction *, 8> WorkList;

5401

SmallPtrSet<Instruction *, 16> Visited;

5402

SmallVector<Instruction *, 8> AndsToMaybeRemove;

5403

for (auto *U : Load->users())

5404

WorkList.push_back(cast<Instruction>(U));

5405

5406

EVT LoadResultVT = TLI->getValueType(*DL, Load->getType());

5407

unsigned BitWidth = LoadResultVT.getSizeInBits();

5408

APInt DemandBits(BitWidth, 0);

5409

APInt WidestAndBits(BitWidth, 0);

5410

5411

while (!WorkList.empty()) {

5412

Instruction *I = WorkList.back();

5413

WorkList.pop_back();

5414

5415

// Break use-def graph loops.

5416

if (!Visited.insert(I).second)

5417

continue;

5418

5419

// For a PHI node, push all of its users.

5420

if (auto *Phi = dyn_cast<PHINode>(I)) {

5421

for (auto *U : Phi->users())

5422

WorkList.push_back(cast<Instruction>(U));

5423

continue;

5424

}

5425

5426

switch (I->getOpcode()) {

5427

case Instruction::And: {

5428

auto *AndC = dyn_cast<ConstantInt>(I->getOperand(1));

5429

if (!AndC)

5430

return false;

5431

APInt AndBits = AndC->getValue();

5432

DemandBits |= AndBits;

5433

// Keep track of the widest and mask we see.

5434

if (AndBits.ugt(WidestAndBits))

5435

WidestAndBits = AndBits;

5436

if (AndBits == WidestAndBits && I->getOperand(0) == Load)

5437

AndsToMaybeRemove.push_back(I);

5438

break;

5439

}

5440

5441

case Instruction::Shl: {

5442

auto *ShlC = dyn_cast<ConstantInt>(I->getOperand(1));

5443

if (!ShlC)

5444

return false;

5445

uint64_t ShiftAmt = ShlC->getLimitedValue(BitWidth - 1);

5446

DemandBits.setLowBits(BitWidth - ShiftAmt);

5447

break;

5448

}

5449

5450

case Instruction::Trunc: {

5451

EVT TruncVT = TLI->getValueType(*DL, I->getType());

5452

unsigned TruncBitWidth = TruncVT.getSizeInBits();

5453

DemandBits.setLowBits(TruncBitWidth);

5454

break;

5455

}

5456

5457

default:

5458

return false;

5459

}

5460

}

5461

5462

uint32_t ActiveBits = DemandBits.getActiveBits();

5463

// Avoid hoisting (and (load x) 1) since it is unlikely to be folded by the

5464

// target even if isLoadExtLegal says an i1 EXTLOAD is valid. For example,

5465

// for the AArch64 target isLoadExtLegal(ZEXTLOAD, i32, i1) returns true, but

5466

// (and (load x) 1) is not matched as a single instruction, rather as a LDR

5467

// followed by an AND.

5468

// TODO: Look into removing this restriction by fixing backends to either

5469

// return false for isLoadExtLegal for i1 or have them select this pattern to

5470

// a single instruction.

5471

5472

// Also avoid hoisting if we didn't see any ands with the exact DemandBits

5473

// mask, since these are the only ands that will be removed by isel.

5474

if (ActiveBits <= 1 || !DemandBits.isMask(ActiveBits) ||

5475

WidestAndBits != DemandBits)

5476

return false;

5477

5478

LLVMContext &Ctx = Load->getType()->getContext();

5479

Type *TruncTy = Type::getIntNTy(Ctx, ActiveBits);

5480

EVT TruncVT = TLI->getValueType(*DL, TruncTy);

5481

5482

// Reject cases that won't be matched as extloads.

5483

if (!LoadResultVT.bitsGT(TruncVT) || !TruncVT.isRound() ||

5484

!TLI->isLoadExtLegal(ISD::ZEXTLOAD, LoadResultVT, TruncVT))

5485

return false;

5486

5487

IRBuilder<> Builder(Load->getNextNode());

5488

auto *NewAnd = dyn_cast<Instruction>(

5489

Builder.CreateAnd(Load, ConstantInt::get(Ctx, DemandBits)));

5490

// Mark this instruction as "inserted by CGP", so that other

5491

// optimizations don't touch it.

5492

InsertedInsts.insert(NewAnd);

5493

5494

// Replace all uses of load with new and (except for the use of load in the

5495

// new and itself).

5496

Load->replaceAllUsesWith(NewAnd);

5497

NewAnd->setOperand(0, Load);

5498

5499

// Remove any and instructions that are now redundant.

5500

for (auto *And : AndsToMaybeRemove)

5501

// Check that the and mask is the same as the one we decided to put on the

5502

// new and.

5503

if (cast<ConstantInt>(And->getOperand(1))->getValue() == DemandBits) {

5504

And->replaceAllUsesWith(NewAnd);

5505

if (&*CurInstIterator == And)

5506

CurInstIterator = std::next(And->getIterator());

5507

And->eraseFromParent();

5508

++NumAndUses;

5509

}

5510

5511

++NumAndsAdded;

5512

return true;

5513

}

5514

5515

/// Check if V (an operand of a select instruction) is an expensive instruction

5516

/// that is only used once.

5517

static bool sinkSelectOperand(const TargetTransformInfo *TTI, Value *V) {

5518

auto *I = dyn_cast<Instruction>(V);

5519

// If it's safe to speculatively execute, then it should not have side

5520

// effects; therefore, it's safe to sink and possibly *not* execute.

5521

return I && I->hasOneUse() && isSafeToSpeculativelyExecute(I) &&

5522

TTI->getUserCost(I) >= TargetTransformInfo::TCC_Expensive;

5523

}

5524

5525

/// Returns true if a SelectInst should be turned into an explicit branch.

5526

static bool isFormingBranchFromSelectProfitable(const TargetTransformInfo *TTI,

5527

const TargetLowering *TLI,

5528

SelectInst *SI) {

5529

// If even a predictable select is cheap, then a branch can't be cheaper.

5530

if (!TLI->isPredictableSelectExpensive())

5531

return false;

5532

5533

// FIXME: This should use the same heuristics as IfConversion to determine

5534

// whether a select is better represented as a branch.

5535

5536

// If metadata tells us that the select condition is obviously predictable,

5537

// then we want to replace the select with a branch.

5538

uint64_t TrueWeight, FalseWeight;

5539

if (SI->extractProfMetadata(TrueWeight, FalseWeight)) {

5540

uint64_t Max = std::max(TrueWeight, FalseWeight);

5541

uint64_t Sum = TrueWeight + FalseWeight;

5542

if (Sum != 0) {

5543

auto Probability = BranchProbability::getBranchProbability(Max, Sum);

5544

if (Probability > TLI->getPredictableBranchThreshold())

5545

return true;

5546

}

5547

}

5548

5549

CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());

5550

5551

// If a branch is predictable, an out-of-order CPU can avoid blocking on its

5552

// comparison condition. If the compare has more than one use, there's

5553

// probably another cmov or setcc around, so it's not worth emitting a branch.

5554

if (!Cmp || !Cmp->hasOneUse())

5555

return false;

5556

5557

// If either operand of the select is expensive and only needed on one side

5558

// of the select, we should form a branch.

5559

if (sinkSelectOperand(TTI, SI->getTrueValue()) ||

5560

sinkSelectOperand(TTI, SI->getFalseValue()))

5561

return true;

5562

5563

return false;

5564

}

5565

5566

/// If \p isTrue is true, return the true value of \p SI, otherwise return

5567

/// false value of \p SI. If the true/false value of \p SI is defined by any

5568

/// select instructions in \p Selects, look through the defining select

5569

/// instruction until the true/false value is not defined in \p Selects.

5570

static Value *getTrueOrFalseValue(

5571

SelectInst *SI, bool isTrue,

5572

const SmallPtrSet<const Instruction *, 2> &Selects) {

5573

Value *V;

5574

5575

for (SelectInst *DefSI = SI; DefSI != nullptr && Selects.count(DefSI);

5576

DefSI = dyn_cast<SelectInst>(V)) {

5577

assert(DefSI->getCondition() == SI->getCondition() &&((DefSI->getCondition() == SI->getCondition() &&
"The condition of DefSI does not match with SI") ? static_cast
<void> (0) : __assert_fail ("DefSI->getCondition() == SI->getCondition() && \"The condition of DefSI does not match with SI\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 5578, __PRETTY_FUNCTION__))

5578

"The condition of DefSI does not match with SI")((DefSI->getCondition() == SI->getCondition() &&
"The condition of DefSI does not match with SI") ? static_cast
<void> (0) : __assert_fail ("DefSI->getCondition() == SI->getCondition() && \"The condition of DefSI does not match with SI\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 5578, __PRETTY_FUNCTION__));

5579

V = (isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());

5580

}

5581

return V;

5582

}

5583

5584

/// If we have a SelectInst that will likely profit from branch prediction,

5585

/// turn it into a branch.

5586

bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI) {

5587

// Find all consecutive select instructions that share the same condition.

5588

SmallVector<SelectInst *, 2> ASI;

5589

ASI.push_back(SI);

5590

for (BasicBlock::iterator It = ++BasicBlock::iterator(SI);

5591

It != SI->getParent()->end(); ++It) {

5592

SelectInst *I = dyn_cast<SelectInst>(&*It);

5593

if (I && SI->getCondition() == I->getCondition()) {

5594

ASI.push_back(I);

5595

} else {

5596

break;

5597

}

5598

}

5599

5600

SelectInst *LastSI = ASI.back();

5601

// Increment the current iterator to skip all the rest of select instructions

5602

// because they will be either "not lowered" or "all lowered" to branch.

5603

CurInstIterator = std::next(LastSI->getIterator());

5604

5605

bool VectorCond = !SI->getCondition()->getType()->isIntegerTy(1);

5606

5607

// Can we convert the 'select' to CF ?

5608

if (DisableSelectToBranch || OptSize || !TLI || VectorCond ||

5609

SI->getMetadata(LLVMContext::MD_unpredictable))

5610

return false;

5611

5612

TargetLowering::SelectSupportKind SelectKind;

5613

if (VectorCond)

5614

SelectKind = TargetLowering::VectorMaskSelect;

5615

else if (SI->getType()->isVectorTy())

5616

SelectKind = TargetLowering::ScalarCondVectorVal;

5617

else

5618

SelectKind = TargetLowering::ScalarValSelect;

5619

5620

if (TLI->isSelectSupported(SelectKind) &&

5621

!isFormingBranchFromSelectProfitable(TTI, TLI, SI))

5622

return false;

5623

5624

ModifiedDT = true;

5625

5626

// Transform a sequence like this:

5627

// start:

5628

// %cmp = cmp uge i32 %a, %b

5629

// %sel = select i1 %cmp, i32 %c, i32 %d

5630

5631

// Into:

5632

// start:

5633

// %cmp = cmp uge i32 %a, %b

5634

// br i1 %cmp, label %select.true, label %select.false

5635

// select.true:

5636

// br label %select.end

5637

// select.false:

5638

// br label %select.end

5639

// select.end:

5640

// %sel = phi i32 [ %c, %select.true ], [ %d, %select.false ]

5641

5642

// In addition, we may sink instructions that produce %c or %d from

5643

// the entry block into the destination(s) of the new branch.

5644

// If the true or false blocks do not contain a sunken instruction, that

5645

// block and its branch may be optimized away. In that case, one side of the

5646

// first branch will point directly to select.end, and the corresponding PHI

5647

// predecessor block will be the start block.

5648

5649

// First, we split the block containing the select into 2 blocks.

5650

BasicBlock *StartBlock = SI->getParent();

5651

BasicBlock::iterator SplitPt = ++(BasicBlock::iterator(LastSI));

5652

BasicBlock *EndBlock = StartBlock->splitBasicBlock(SplitPt, "select.end");

5653

5654

// Delete the unconditional branch that was just created by the split.

5655

StartBlock->getTerminator()->eraseFromParent();

5656

5657

// These are the new basic blocks for the conditional branch.

5658

// At least one will become an actual new basic block.

5659

BasicBlock *TrueBlock = nullptr;

5660

BasicBlock *FalseBlock = nullptr;

5661

BranchInst *TrueBranch = nullptr;

5662

BranchInst *FalseBranch = nullptr;

5663

5664

// Sink expensive instructions into the conditional blocks to avoid executing

5665

// them speculatively.

5666

for (SelectInst *SI : ASI) {

5667

if (sinkSelectOperand(TTI, SI->getTrueValue())) {

5668

if (TrueBlock == nullptr) {

5669

TrueBlock = BasicBlock::Create(SI->getContext(), "select.true.sink",

5670

EndBlock->getParent(), EndBlock);

5671

TrueBranch = BranchInst::Create(EndBlock, TrueBlock);

5672

}

5673

auto *TrueInst = cast<Instruction>(SI->getTrueValue());

5674

TrueInst->moveBefore(TrueBranch);

5675

}

5676

if (sinkSelectOperand(TTI, SI->getFalseValue())) {

5677

if (FalseBlock == nullptr) {

5678

FalseBlock = BasicBlock::Create(SI->getContext(), "select.false.sink",

5679

EndBlock->getParent(), EndBlock);

5680

FalseBranch = BranchInst::Create(EndBlock, FalseBlock);

5681

}

5682

auto *FalseInst = cast<Instruction>(SI->getFalseValue());

5683

FalseInst->moveBefore(FalseBranch);

5684

}

5685

}

5686

5687

// If there was nothing to sink, then arbitrarily choose the 'false' side

5688

// for a new input value to the PHI.

5689

if (TrueBlock == FalseBlock) {

5690

assert(TrueBlock == nullptr &&((TrueBlock == nullptr && "Unexpected basic block transform while optimizing select"
) ? static_cast<void> (0) : __assert_fail ("TrueBlock == nullptr && \"Unexpected basic block transform while optimizing select\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 5691, __PRETTY_FUNCTION__))

5691

"Unexpected basic block transform while optimizing select")((TrueBlock == nullptr && "Unexpected basic block transform while optimizing select"
) ? static_cast<void> (0) : __assert_fail ("TrueBlock == nullptr && \"Unexpected basic block transform while optimizing select\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 5691, __PRETTY_FUNCTION__));

5692

5693

FalseBlock = BasicBlock::Create(SI->getContext(), "select.false",

5694

EndBlock->getParent(), EndBlock);

5695

BranchInst::Create(EndBlock, FalseBlock);

5696

}

5697

5698

// Insert the real conditional branch based on the original condition.

5699

// If we did not create a new block for one of the 'true' or 'false' paths

5700

// of the condition, it means that side of the branch goes to the end block

5701

// directly and the path originates from the start block from the point of

5702

// view of the new PHI.

5703

BasicBlock *TT, *FT;

5704

if (TrueBlock == nullptr) {

5705

TT = EndBlock;

5706

FT = FalseBlock;

5707

TrueBlock = StartBlock;

5708

} else if (FalseBlock == nullptr) {

5709

TT = TrueBlock;

5710

FT = EndBlock;

5711

FalseBlock = StartBlock;

5712

} else {

5713

TT = TrueBlock;

5714

FT = FalseBlock;

5715

}

5716

IRBuilder<>(SI).CreateCondBr(SI->getCondition(), TT, FT, SI);

5717

5718

SmallPtrSet<const Instruction *, 2> INS;

5719

INS.insert(ASI.begin(), ASI.end());

5720

// Use reverse iterator because later select may use the value of the

5721

// earlier select, and we need to propagate value through earlier select

5722

// to get the PHI operand.

5723

for (auto It = ASI.rbegin(); It != ASI.rend(); ++It) {

5724

SelectInst *SI = *It;

5725

// The select itself is replaced with a PHI Node.

5726

PHINode *PN = PHINode::Create(SI->getType(), 2, "", &EndBlock->front());

5727

PN->takeName(SI);

5728

PN->addIncoming(getTrueOrFalseValue(SI, true, INS), TrueBlock);

5729

PN->addIncoming(getTrueOrFalseValue(SI, false, INS), FalseBlock);

5730

5731

SI->replaceAllUsesWith(PN);

5732

SI->eraseFromParent();

5733

INS.erase(SI);

5734

++NumSelectsExpanded;

5735

}

5736

5737

// Instruct OptimizeBlock to skip to the next block.

5738

CurInstIterator = StartBlock->end();

5739

return true;

5740

}

5741

5742

static bool isBroadcastShuffle(ShuffleVectorInst *SVI) {

5743

SmallVector<int, 16> Mask(SVI->getShuffleMask());

5744

int SplatElem = -1;

5745

for (unsigned i = 0; i < Mask.size(); ++i) {

5746

if (SplatElem != -1 && Mask[i] != -1 && Mask[i] != SplatElem)

5747

return false;

5748

SplatElem = Mask[i];

5749

}

5750

5751

return true;

5752

}

5753

5754

/// Some targets have expensive vector shifts if the lanes aren't all the same

5755

/// (e.g. x86 only introduced "vpsllvd" and friends with AVX2). In these cases

5756

/// it's often worth sinking a shufflevector splat down to its use so that

5757

/// codegen can spot all lanes are identical.

5758

bool CodeGenPrepare::optimizeShuffleVectorInst(ShuffleVectorInst *SVI) {

5759

BasicBlock *DefBB = SVI->getParent();

5760

5761

// Only do this xform if variable vector shifts are particularly expensive.

5762

if (!TLI || !TLI->isVectorShiftByScalarCheap(SVI->getType()))

5763

return false;

5764

5765

// We only expect better codegen by sinking a shuffle if we can recognise a

5766

// constant splat.

5767

if (!isBroadcastShuffle(SVI))

5768

return false;

5769

5770

// InsertedShuffles - Only insert a shuffle in each block once.

5771

DenseMap<BasicBlock*, Instruction*> InsertedShuffles;

5772

5773

bool MadeChange = false;

5774

for (User *U : SVI->users()) {

5775

Instruction *UI = cast<Instruction>(U);

5776

5777

// Figure out which BB this ext is used in.

5778

BasicBlock *UserBB = UI->getParent();

5779

if (UserBB == DefBB) continue;

5780

5781

// For now only apply this when the splat is used by a shift instruction.

5782

if (!UI->isShift()) continue;

5783

5784

// Everything checks out, sink the shuffle if the user's block doesn't

5785

// already have a copy.

5786

Instruction *&InsertedShuffle = InsertedShuffles[UserBB];

5787

5788

if (!InsertedShuffle) {

5789

BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();

5790

5791

InsertedShuffle =

5792

new ShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),

5793

SVI->getOperand(2), "", &*InsertPt);

5794

}

5795

5796

UI->replaceUsesOfWith(SVI, InsertedShuffle);

5797

MadeChange = true;

5798

}

5799

5800

// If we removed all uses, nuke the shuffle.

5801

if (SVI->use_empty()) {

5802

SVI->eraseFromParent();

5803

MadeChange = true;

5804

}

5805

5806

return MadeChange;

5807

}

5808

5809

bool CodeGenPrepare::optimizeSwitchInst(SwitchInst *SI) {

5810

if (!TLI || !DL)

5811

return false;

5812

5813

Value *Cond = SI->getCondition();

5814

Type *OldType = Cond->getType();

5815

LLVMContext &Context = Cond->getContext();

5816

MVT RegType = TLI->getRegisterType(Context, TLI->getValueType(*DL, OldType));

5817

unsigned RegWidth = RegType.getSizeInBits();

5818

5819

if (RegWidth <= cast<IntegerType>(OldType)->getBitWidth())

5820

return false;

5821

5822

// If the register width is greater than the type width, expand the condition

5823

// of the switch instruction and each case constant to the width of the

5824

// register. By widening the type of the switch condition, subsequent

5825

// comparisons (for case comparisons) will not need to be extended to the

5826

// preferred register width, so we will potentially eliminate N-1 extends,

5827

// where N is the number of cases in the switch.

5828

auto *NewType = Type::getIntNTy(Context, RegWidth);

5829

5830

// Zero-extend the switch condition and case constants unless the switch

5831

// condition is a function argument that is already being sign-extended.

5832

// In that case, we can avoid an unnecessary mask/extension by sign-extending

5833

// everything instead.

5834

Instruction::CastOps ExtType = Instruction::ZExt;

5835

if (auto *Arg = dyn_cast<Argument>(Cond))

5836

if (Arg->hasSExtAttr())

5837

ExtType = Instruction::SExt;

5838

5839

auto *ExtInst = CastInst::Create(ExtType, Cond, NewType);

5840

ExtInst->insertBefore(SI);

5841

SI->setCondition(ExtInst);

5842

for (auto Case : SI->cases()) {

5843

APInt NarrowConst = Case.getCaseValue()->getValue();

5844

APInt WideConst = (ExtType == Instruction::ZExt) ?

5845

NarrowConst.zext(RegWidth) : NarrowConst.sext(RegWidth);

5846

Case.setValue(ConstantInt::get(Context, WideConst));

5847

}

5848

5849

return true;

5850

}

5851

5852

5853

namespace {

5854

5855

/// \brief Helper class to promote a scalar operation to a vector one.

5856

/// This class is used to move downward extractelement transition.

5857

/// E.g.,

5858

/// a = vector_op <2 x i32>

5859

/// b = extractelement <2 x i32> a, i32 0

5860

/// c = scalar_op b

5861

/// store c

5862

///

5863

/// =>

5864

/// a = vector_op <2 x i32>

5865

/// c = vector_op a (equivalent to scalar_op on the related lane)

5866

/// * d = extractelement <2 x i32> c, i32 0

5867

/// * store d

5868

/// Assuming both extractelement and store can be combine, we get rid of the

5869

/// transition.

5870

class VectorPromoteHelper {

5871

/// DataLayout associated with the current module.

5872

const DataLayout &DL;

5873

5874

/// Used to perform some checks on the legality of vector operations.

5875

const TargetLowering &TLI;

5876

5877

/// Used to estimated the cost of the promoted chain.

5878

const TargetTransformInfo &TTI;

5879

5880

/// The transition being moved downwards.

5881

Instruction *Transition;

5882

5883

/// The sequence of instructions to be promoted.

5884

SmallVector<Instruction *, 4> InstsToBePromoted;

5885

5886

/// Cost of combining a store and an extract.

5887

unsigned StoreExtractCombineCost;

5888

5889

/// Instruction that will be combined with the transition.

5890

Instruction *CombineInst = nullptr;

5891

5892

/// \brief The instruction that represents the current end of the transition.

5893

/// Since we are faking the promotion until we reach the end of the chain

5894

/// of computation, we need a way to get the current end of the transition.

5895

Instruction *getEndOfTransition() const {

5896

if (InstsToBePromoted.empty())

5897

return Transition;

5898

return InstsToBePromoted.back();

5899

}

5900

5901

/// \brief Return the index of the original value in the transition.

5902

/// E.g., for "extractelement <2 x i32> c, i32 1" the original value,

5903

/// c, is at index 0.

5904

unsigned getTransitionOriginalValueIdx() const {

5905

assert(isa<ExtractElementInst>(Transition) &&((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 5906, __PRETTY_FUNCTION__))

5906

"Other kind of transitions are not supported yet")((isa<ExtractElementInst>(Transition) && "Other kind of transitions are not supported yet"
) ? static_cast<void> (0) : __assert_fail ("isa<ExtractElementInst>(Transition) && \"Other kind of transitions are not supported yet\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 5906, __PRETTY_FUNCTION__));

5907

return 0;

5908

}

5909

5910

/// \brief Return the index of the index in the transition.

5911

/// E.g., for "extractelement <2 x i32> c, i32 0" the index

5912

/// is at index 1.

5913

unsigned getTransitionIdx() const {

5914

5915

5916

return 1;

5917

}

5918

5919

/// \brief Get the type of the transition.

5920

/// This is the type of the original value.

5921

/// E.g., for "extractelement <2 x i32> c, i32 1" the type of the

5922

/// transition is <2 x i32>.

5923

Type *getTransitionType() const {

5924

return Transition->getOperand(getTransitionOriginalValueIdx())->getType();

5925

}

5926

5927

/// \brief Promote \p ToBePromoted by moving \p Def downward through.

5928

/// I.e., we have the following sequence:

5929

/// Def = Transition <ty1> a to <ty2>

5930

/// b = ToBePromoted <ty2> Def, ...

5931

/// =>

5932

/// b = ToBePromoted <ty1> a, ...

5933

/// Def = Transition <ty1> ToBePromoted to <ty2>

5934

void promoteImpl(Instruction *ToBePromoted);

5935

5936

/// \brief Check whether or not it is profitable to promote all the

5937

/// instructions enqueued to be promoted.

5938

bool isProfitableToPromote() {

5939

Value *ValIdx = Transition->getOperand(getTransitionOriginalValueIdx());

5940

unsigned Index = isa<ConstantInt>(ValIdx)

5941

? cast<ConstantInt>(ValIdx)->getZExtValue()

5942

: -1;

5943

Type *PromotedType = getTransitionType();

5944

5945

StoreInst *ST = cast<StoreInst>(CombineInst);

5946

unsigned AS = ST->getPointerAddressSpace();

5947

unsigned Align = ST->getAlignment();

5948

// Check if this store is supported.

5949

if (!TLI.allowsMisalignedMemoryAccesses(

5950

TLI.getValueType(DL, ST->getValueOperand()->getType()), AS,

5951

Align)) {

5952

// If this is not supported, there is no way we can combine

5953

// the extract with the store.

5954

return false;

5955

}

5956

5957

// The scalar chain of computation has to pay for the transition

5958

// scalar to vector.

5959

// The vector chain has to account for the combining cost.

5960

uint64_t ScalarCost =

5961

TTI.getVectorInstrCost(Transition->getOpcode(), PromotedType, Index);

5962

uint64_t VectorCost = StoreExtractCombineCost;

5963

for (const auto &Inst : InstsToBePromoted) {

5964

// Compute the cost.

5965

// By construction, all instructions being promoted are arithmetic ones.

5966

// Moreover, one argument is a constant that can be viewed as a splat

5967

// constant.

5968

Value *Arg0 = Inst->getOperand(0);

5969

bool IsArg0Constant = isa<UndefValue>(Arg0) || isa<ConstantInt>(Arg0) ||

5970

isa<ConstantFP>(Arg0);

5971

TargetTransformInfo::OperandValueKind Arg0OVK =

5972

IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue

5973

: TargetTransformInfo::OK_AnyValue;

5974

TargetTransformInfo::OperandValueKind Arg1OVK =

5975

!IsArg0Constant ? TargetTransformInfo::OK_UniformConstantValue

5976

: TargetTransformInfo::OK_AnyValue;

5977

ScalarCost += TTI.getArithmeticInstrCost(

5978

Inst->getOpcode(), Inst->getType(), Arg0OVK, Arg1OVK);

5979

VectorCost += TTI.getArithmeticInstrCost(Inst->getOpcode(), PromotedType,

5980

Arg0OVK, Arg1OVK);

5981

}

5982

DEBUG(dbgs() << "Estimated cost of computation to be promoted:\nScalar: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false)

5983

<< ScalarCost << "\nVector: " << VectorCost << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Estimated cost of computation to be promoted:\nScalar: "
<< ScalarCost << "\nVector: " << VectorCost
<< '\n'; } } while (false);

5984

return ScalarCost > VectorCost;

5985

}

5986

5987

/// \brief Generate a constant vector with \p Val with the same

5988

/// number of elements as the transition.

5989

/// \p UseSplat defines whether or not \p Val should be replicated

5990

/// across the whole vector.

5991

/// In other words, if UseSplat == true, we generate <Val, Val, ..., Val>,

5992

/// otherwise we generate a vector with as many undef as possible:

5993

/// <undef, ..., undef, Val, undef, ..., undef> where \p Val is only

5994

/// used at the index of the extract.

5995

Value *getConstantVector(Constant *Val, bool UseSplat) const {

5996

unsigned ExtractIdx = std::numeric_limits<unsigned>::max();

5997

if (!UseSplat) {

5998

// If we cannot determine where the constant must be, we have to

5999

// use a splat constant.

6000

Value *ValExtractIdx = Transition->getOperand(getTransitionIdx());

6001

if (ConstantInt *CstVal = dyn_cast<ConstantInt>(ValExtractIdx))

6002

ExtractIdx = CstVal->getSExtValue();

6003

else

6004

UseSplat = true;

6005

}

6006

6007

unsigned End = getTransitionType()->getVectorNumElements();

6008

if (UseSplat)

6009

return ConstantVector::getSplat(End, Val);

6010

6011

SmallVector<Constant *, 4> ConstVec;

6012

UndefValue *UndefVal = UndefValue::get(Val->getType());

6013

for (unsigned Idx = 0; Idx != End; ++Idx) {

6014

if (Idx == ExtractIdx)

6015

ConstVec.push_back(Val);

6016

else

6017

ConstVec.push_back(UndefVal);

6018

}

6019

return ConstantVector::get(ConstVec);

6020

}

6021

6022

/// \brief Check if promoting to a vector type an operand at \p OperandIdx

6023

/// in \p Use can trigger undefined behavior.

6024

static bool canCauseUndefinedBehavior(const Instruction *Use,

6025

unsigned OperandIdx) {

6026

// This is not safe to introduce undef when the operand is on

6027

// the right hand side of a division-like instruction.

6028

if (OperandIdx != 1)

6029

return false;

6030

switch (Use->getOpcode()) {

6031

default:

6032

return false;

6033

case Instruction::SDiv:

6034

case Instruction::UDiv:

6035

case Instruction::SRem:

6036

case Instruction::URem:

6037

return true;

6038

case Instruction::FDiv:

6039

case Instruction::FRem:

6040

return !Use->hasNoNaNs();

6041

}

6042

llvm_unreachable(nullptr)::llvm::llvm_unreachable_internal(nullptr, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6042);

6043

}

6044

6045

public:

6046

VectorPromoteHelper(const DataLayout &DL, const TargetLowering &TLI,

6047

const TargetTransformInfo &TTI, Instruction *Transition,

6048

unsigned CombineCost)

6049

: DL(DL), TLI(TLI), TTI(TTI), Transition(Transition),

6050

StoreExtractCombineCost(CombineCost) {

6051

assert(Transition && "Do not know how to promote null")((Transition && "Do not know how to promote null") ? static_cast
<void> (0) : __assert_fail ("Transition && \"Do not know how to promote null\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6051, __PRETTY_FUNCTION__));

6052

}

6053

6054

/// \brief Check if we can promote \p ToBePromoted to \p Type.

6055

bool canPromote(const Instruction *ToBePromoted) const {

6056

// We could support CastInst too.

6057

return isa<BinaryOperator>(ToBePromoted);

6058

}

6059

6060

/// \brief Check if it is profitable to promote \p ToBePromoted

6061

/// by moving downward the transition through.

6062

bool shouldPromote(const Instruction *ToBePromoted) const {

6063

// Promote only if all the operands can be statically expanded.

6064

// Indeed, we do not want to introduce any new kind of transitions.

6065

for (const Use &U : ToBePromoted->operands()) {

6066

const Value *Val = U.get();

6067

if (Val == getEndOfTransition()) {

6068

// If the use is a division and the transition is on the rhs,

6069

// we cannot promote the operation, otherwise we may create a

6070

// division by zero.

6071

if (canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()))

6072

return false;

6073

continue;

6074

}

6075

if (!isa<ConstantInt>(Val) && !isa<UndefValue>(Val) &&

6076

!isa<ConstantFP>(Val))

6077

return false;

6078

}

6079

// Check that the resulting operation is legal.

6080

int ISDOpcode = TLI.InstructionOpcodeToISD(ToBePromoted->getOpcode());

6081

if (!ISDOpcode)

6082

return false;

6083

return StressStoreExtract ||

6084

TLI.isOperationLegalOrCustom(

6085

ISDOpcode, TLI.getValueType(DL, getTransitionType(), true));

6086

}

6087

6088

/// \brief Check whether or not \p Use can be combined

6089

/// with the transition.

6090

/// I.e., is it possible to do Use(Transition) => AnotherUse?

6091

bool canCombine(const Instruction *Use) { return isa<StoreInst>(Use); }

6092

6093

/// \brief Record \p ToBePromoted as part of the chain to be promoted.

6094

void enqueueForPromotion(Instruction *ToBePromoted) {

6095

InstsToBePromoted.push_back(ToBePromoted);

6096

}

6097

6098

/// \brief Set the instruction that will be combined with the transition.

6099

void recordCombineInstruction(Instruction *ToBeCombined) {

6100

assert(canCombine(ToBeCombined) && "Unsupported instruction to combine")((canCombine(ToBeCombined) && "Unsupported instruction to combine"
) ? static_cast<void> (0) : __assert_fail ("canCombine(ToBeCombined) && \"Unsupported instruction to combine\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6100, __PRETTY_FUNCTION__));

6101

CombineInst = ToBeCombined;

6102

}

6103

6104

/// \brief Promote all the instructions enqueued for promotion if it is

6105

/// is profitable.

6106

/// \return True if the promotion happened, false otherwise.

6107

bool promote() {

6108

// Check if there is something to promote.

6109

// Right now, if we do not have anything to combine with,

6110

// we assume the promotion is not profitable.

6111

if (InstsToBePromoted.empty() || !CombineInst)

6112

return false;

6113

6114

// Check cost.

6115

if (!StressStoreExtract && !isProfitableToPromote())

6116

return false;

6117

6118

// Promote.

6119

for (auto &ToBePromoted : InstsToBePromoted)

6120

promoteImpl(ToBePromoted);

6121

InstsToBePromoted.clear();

6122

return true;

6123

}

6124

};

6125

6126

} // end anonymous namespace

6127

6128

void VectorPromoteHelper::promoteImpl(Instruction *ToBePromoted) {

6129

// At this point, we know that all the operands of ToBePromoted but Def

6130

// can be statically promoted.

6131

// For Def, we need to use its parameter in ToBePromoted:

6132

// b = ToBePromoted ty1 a

6133

// Def = Transition ty1 b to ty2

6134

// Move the transition down.

6135

// 1. Replace all uses of the promoted operation by the transition.

6136

// = ... b => = ... Def.

6137

assert(ToBePromoted->getType() == Transition->getType() &&((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6139, __PRETTY_FUNCTION__))

6138

"The type of the result of the transition does not match "((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6139, __PRETTY_FUNCTION__))

6139

"the final type")((ToBePromoted->getType() == Transition->getType() &&
"The type of the result of the transition does not match " "the final type"
) ? static_cast<void> (0) : __assert_fail ("ToBePromoted->getType() == Transition->getType() && \"The type of the result of the transition does not match \" \"the final type\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6139, __PRETTY_FUNCTION__));

6140

ToBePromoted->replaceAllUsesWith(Transition);

6141

// 2. Update the type of the uses.

6142

// b = ToBePromoted ty2 Def => b = ToBePromoted ty1 Def.

6143

Type *TransitionTy = getTransitionType();

6144

ToBePromoted->mutateType(TransitionTy);

6145

// 3. Update all the operands of the promoted operation with promoted

6146

// operands.

6147

// b = ToBePromoted ty1 Def => b = ToBePromoted ty1 a.

6148

for (Use &U : ToBePromoted->operands()) {

6149

Value *Val = U.get();

6150

Value *NewVal = nullptr;

6151

if (Val == Transition)

6152

NewVal = Transition->getOperand(getTransitionOriginalValueIdx());

6153

else if (isa<UndefValue>(Val) || isa<ConstantInt>(Val) ||

6154

isa<ConstantFP>(Val)) {

6155

// Use a splat constant if it is not safe to use undef.

6156

NewVal = getConstantVector(

6157

cast<Constant>(Val),

6158

isa<UndefValue>(Val) ||

6159

canCauseUndefinedBehavior(ToBePromoted, U.getOperandNo()));

6160

} else

6161

llvm_unreachable("Did you modified shouldPromote and forgot to update "::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6162)

6162

"this?")::llvm::llvm_unreachable_internal("Did you modified shouldPromote and forgot to update "
"this?", "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6162);

6163

ToBePromoted->setOperand(U.getOperandNo(), NewVal);

6164

}

6165

Transition->moveAfter(ToBePromoted);

6166

Transition->setOperand(getTransitionOriginalValueIdx(), ToBePromoted);

6167

}

6168

6169

/// Some targets can do store(extractelement) with one instruction.

6170

/// Try to push the extractelement towards the stores when the target

6171

/// has this feature and this is profitable.

6172

bool CodeGenPrepare::optimizeExtractElementInst(Instruction *Inst) {

6173

unsigned CombineCost = std::numeric_limits<unsigned>::max();

6174

if (DisableStoreExtract || !TLI ||

6175

(!StressStoreExtract &&

6176

!TLI->canCombineStoreAndExtract(Inst->getOperand(0)->getType(),

6177

Inst->getOperand(1), CombineCost)))

6178

return false;

6179

6180

// At this point we know that Inst is a vector to scalar transition.

6181

// Try to move it down the def-use chain, until:

6182

// - We can combine the transition with its single use

6183

// => we got rid of the transition.

6184

// - We escape the current basic block

6185

// => we would need to check that we are moving it at a cheaper place and

6186

// we do not do that for now.

6187

BasicBlock *Parent = Inst->getParent();

6188

DEBUG(dbgs() << "Found an interesting transition: " << *Inst << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Found an interesting transition: "
<< *Inst << '\n'; } } while (false);

6189

VectorPromoteHelper VPH(*DL, *TLI, *TTI, Inst, CombineCost);

6190

// If the transition has more than one use, assume this is not going to be

6191

// beneficial.

6192

while (Inst->hasOneUse()) {

6193

Instruction *ToBePromoted = cast<Instruction>(*Inst->user_begin());

6194

DEBUG(dbgs() << "Use: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Use: " << *ToBePromoted
<< '\n'; } } while (false);

6195

6196

if (ToBePromoted->getParent() != Parent) {

6197

DEBUG(dbgs() << "Instruction to promote is in a different block ("do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)

6198

<< ToBePromoted->getParent()->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false)

6199

<< ") than the transition (" << Parent->getName() << ").\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Instruction to promote is in a different block ("
<< ToBePromoted->getParent()->getName() <<
") than the transition (" << Parent->getName() <<
").\n"; } } while (false);

6200

return false;

6201

}

6202

6203

if (VPH.canCombine(ToBePromoted)) {

6204

DEBUG(dbgs() << "Assume " << *Inst << '\n'do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (false)

6205

<< "will be combined with: " << *ToBePromoted << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Assume " << *Inst
<< '\n' << "will be combined with: " << *ToBePromoted
<< '\n'; } } while (false);

6206

VPH.recordCombineInstruction(ToBePromoted);

6207

bool Changed = VPH.promote();

6208

NumStoreExtractExposed += Changed;

6209

return Changed;

6210

}

6211

6212

DEBUG(dbgs() << "Try promoting.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Try promoting.\n"; } }
while (false);

6213

if (!VPH.canPromote(ToBePromoted) || !VPH.shouldPromote(ToBePromoted))

6214

return false;

6215

6216

DEBUG(dbgs() << "Promoting is possible... Enqueue for promotion!\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Promoting is possible... Enqueue for promotion!\n"
; } } while (false);

6217

6218

VPH.enqueueForPromotion(ToBePromoted);

6219

Inst = ToBePromoted;

6220

}

6221

return false;

6222

}

6223

6224

/// For the instruction sequence of store below, F and I values

6225

/// are bundled together as an i64 value before being stored into memory.

6226

/// Sometimes it is more efficent to generate separate stores for F and I,

6227

/// which can remove the bitwise instructions or sink them to colder places.

6228

///

6229

/// (store (or (zext (bitcast F to i32) to i64),

6230

/// (shl (zext I to i64), 32)), addr) -->

6231

/// (store F, addr) and (store I, addr+4)

6232

///

6233

/// Similarly, splitting for other merged store can also be beneficial, like:

6234

/// For pair of {i32, i32}, i64 store --> two i32 stores.

6235

/// For pair of {i32, i16}, i64 store --> two i32 stores.

6236

/// For pair of {i16, i16}, i32 store --> two i16 stores.

6237

/// For pair of {i16, i8}, i32 store --> two i16 stores.

6238

/// For pair of {i8, i8}, i16 store --> two i8 stores.

6239

///

6240

/// We allow each target to determine specifically which kind of splitting is

6241

/// supported.

6242

///

6243

/// The store patterns are commonly seen from the simple code snippet below

6244

/// if only std::make_pair(...) is sroa transformed before inlined into hoo.

6245

/// void goo(const std::pair<int, float> &);

6246

/// hoo() {

6247

/// ...

6248

/// goo(std::make_pair(tmp, ftmp));

6249

/// ...

6250

/// }

6251

///

6252

/// Although we already have similar splitting in DAG Combine, we duplicate

6253

/// it in CodeGenPrepare to catch the case in which pattern is across

6254

/// multiple BBs. The logic in DAG Combine is kept to catch case generated

6255

/// during code expansion.

6256

static bool splitMergedValStore(StoreInst &SI, const DataLayout &DL,

6257

const TargetLowering &TLI) {

6258

// Handle simple but common cases only.

6259

Type *StoreType = SI.getValueOperand()->getType();

6260

if (DL.getTypeStoreSizeInBits(StoreType) != DL.getTypeSizeInBits(StoreType) ||

6261

DL.getTypeSizeInBits(StoreType) == 0)

6262

return false;

6263

6264

unsigned HalfValBitSize = DL.getTypeSizeInBits(StoreType) / 2;

6265

Type *SplitStoreType = Type::getIntNTy(SI.getContext(), HalfValBitSize);

6266

if (DL.getTypeStoreSizeInBits(SplitStoreType) !=

6267

DL.getTypeSizeInBits(SplitStoreType))

6268

return false;

6269

6270

// Match the following patterns:

6271

// (store (or (zext LValue to i64),

6272

// (shl (zext HValue to i64), 32)), HalfValBitSize)

6273

// or

6274

// (store (or (shl (zext HValue to i64), 32)), HalfValBitSize)

6275

// (zext LValue to i64),

6276

// Expect both operands of OR and the first operand of SHL have only

6277

// one use.

6278

Value *LValue, *HValue;

6279

if (!match(SI.getValueOperand(),

6280

m_c_Or(m_OneUse(m_ZExt(m_Value(LValue))),

6281

m_OneUse(m_Shl(m_OneUse(m_ZExt(m_Value(HValue))),

6282

m_SpecificInt(HalfValBitSize))))))

6283

return false;

6284

6285

// Check LValue and HValue are int with size less or equal than 32.

6286

if (!LValue->getType()->isIntegerTy() ||

6287

DL.getTypeSizeInBits(LValue->getType()) > HalfValBitSize ||

6288

!HValue->getType()->isIntegerTy() ||

6289

DL.getTypeSizeInBits(HValue->getType()) > HalfValBitSize)

6290

return false;

6291

6292

// If LValue/HValue is a bitcast instruction, use the EVT before bitcast

6293

// as the input of target query.

6294

auto *LBC = dyn_cast<BitCastInst>(LValue);

6295

auto *HBC = dyn_cast<BitCastInst>(HValue);

6296

EVT LowTy = LBC ? EVT::getEVT(LBC->getOperand(0)->getType())

6297

: EVT::getEVT(LValue->getType());

6298

EVT HighTy = HBC ? EVT::getEVT(HBC->getOperand(0)->getType())

6299

: EVT::getEVT(HValue->getType());

6300

if (!ForceSplitStore && !TLI.isMultiStoresCheaperThanBitsMerge(LowTy, HighTy))

6301

return false;

6302

6303

// Start to split store.

6304

IRBuilder<> Builder(SI.getContext());

6305

Builder.SetInsertPoint(&SI);

6306

6307

// If LValue/HValue is a bitcast in another BB, create a new one in current

6308

// BB so it may be merged with the splitted stores by dag combiner.

6309

if (LBC && LBC->getParent() != SI.getParent())

6310

LValue = Builder.CreateBitCast(LBC->getOperand(0), LBC->getType());

6311

if (HBC && HBC->getParent() != SI.getParent())

6312

HValue = Builder.CreateBitCast(HBC->getOperand(0), HBC->getType());

6313

6314

auto CreateSplitStore = [&](Value *V, bool Upper) {

6315

V = Builder.CreateZExtOrBitCast(V, SplitStoreType);

6316

Value *Addr = Builder.CreateBitCast(

6317

SI.getOperand(1),

6318

SplitStoreType->getPointerTo(SI.getPointerAddressSpace()));

6319

if (Upper)

6320

Addr = Builder.CreateGEP(

6321

SplitStoreType, Addr,

6322

ConstantInt::get(Type::getInt32Ty(SI.getContext()), 1));

6323

Builder.CreateAlignedStore(

6324

V, Addr, Upper ? SI.getAlignment() / 2 : SI.getAlignment());

6325

};

6326

6327

CreateSplitStore(LValue, false);

6328

CreateSplitStore(HValue, true);

6329

6330

// Delete the old store.

6331

SI.eraseFromParent();

6332

return true;

6333

}

6334

6335

// Return true if the GEP has two operands, the first operand is of a sequential

6336

// type, and the second operand is a constant.

6337

static bool GEPSequentialConstIndexed(GetElementPtrInst *GEP) {

6338

gep_type_iterator I = gep_type_begin(*GEP);

6339

return GEP->getNumOperands() == 2 &&

6340

I.isSequential() &&

6341

isa<ConstantInt>(GEP->getOperand(1));

6342

}

6343

6344

// Try unmerging GEPs to reduce liveness interference (register pressure) across

6345

// IndirectBr edges. Since IndirectBr edges tend to touch on many blocks,

6346

// reducing liveness interference across those edges benefits global register

6347

// allocation. Currently handles only certain cases.

6348

6349

// For example, unmerge %GEPI and %UGEPI as below.

6350

6351

// ---------- BEFORE ----------

6352

// SrcBlock:

6353

// ...

6354

// %GEPIOp = ...

6355

// ...

6356

// %GEPI = gep %GEPIOp, Idx

6357

// ...

6358

// indirectbr ... [ label %DstB0, label %DstB1, ... label %DstBi ... ]

6359

// (* %GEPI is alive on the indirectbr edges due to other uses ahead)

6360

// (* %GEPIOp is alive on the indirectbr edges only because of it's used by

6361

// %UGEPI)

6362

6363

// DstB0: ... (there may be a gep similar to %UGEPI to be unmerged)

6364

// DstB1: ... (there may be a gep similar to %UGEPI to be unmerged)

6365

// ...

6366

6367

// DstBi:

6368

// ...

6369

// %UGEPI = gep %GEPIOp, UIdx

6370

// ...

6371

// ---------------------------

6372

6373

// ---------- AFTER ----------

6374

// SrcBlock:

6375

// ... (same as above)

6376

// (* %GEPI is still alive on the indirectbr edges)

6377

// (* %GEPIOp is no longer alive on the indirectbr edges as a result of the

6378

// unmerging)

6379

// ...

6380

6381

// DstBi:

6382

// ...

6383

// %UGEPI = gep %GEPI, (UIdx-Idx)

6384

// ...

6385

// ---------------------------

6386

6387

// The register pressure on the IndirectBr edges is reduced because %GEPIOp is

6388

// no longer alive on them.

6389

6390

// We try to unmerge GEPs here in CodGenPrepare, as opposed to limiting merging

6391

// of GEPs in the first place in InstCombiner::visitGetElementPtrInst() so as

6392

// not to disable further simplications and optimizations as a result of GEP

6393

// merging.

6394

6395

// Note this unmerging may increase the length of the data flow critical path

6396

// (the path from %GEPIOp to %UGEPI would go through %GEPI), which is a tradeoff

6397

// between the register pressure and the length of data-flow critical

6398

// path. Restricting this to the uncommon IndirectBr case would minimize the

6399

// impact of potentially longer critical path, if any, and the impact on compile

6400

// time.

6401

static bool tryUnmergingGEPsAcrossIndirectBr(GetElementPtrInst *GEPI,

6402

const TargetTransformInfo *TTI) {

6403

BasicBlock *SrcBlock = GEPI->getParent();

6404

// Check that SrcBlock ends with an IndirectBr. If not, give up. The common

6405

// (non-IndirectBr) cases exit early here.

6406

if (!isa<IndirectBrInst>(SrcBlock->getTerminator()))

6407

return false;

6408

// Check that GEPI is a simple gep with a single constant index.

6409

if (!GEPSequentialConstIndexed(GEPI))

6410

return false;

6411

ConstantInt *GEPIIdx = cast<ConstantInt>(GEPI->getOperand(1));

6412

// Check that GEPI is a cheap one.

6413

if (TTI->getIntImmCost(GEPIIdx->getValue(), GEPIIdx->getType())

6414

> TargetTransformInfo::TCC_Basic)

6415

return false;

6416

Value *GEPIOp = GEPI->getOperand(0);

6417

// Check that GEPIOp is an instruction that's also defined in SrcBlock.

6418

if (!isa<Instruction>(GEPIOp))

6419

return false;

6420

auto *GEPIOpI = cast<Instruction>(GEPIOp);

6421

if (GEPIOpI->getParent() != SrcBlock)

6422

return false;

6423

// Check that GEP is used outside the block, meaning it's alive on the

6424

// IndirectBr edge(s).

6425

if (find_if(GEPI->users(), [&](User *Usr) {

6426

if (auto *I = dyn_cast<Instruction>(Usr)) {

6427

if (I->getParent() != SrcBlock) {

6428

return true;

6429

}

6430

}

6431

return false;

6432

}) == GEPI->users().end())

6433

return false;

6434

// The second elements of the GEP chains to be unmerged.

6435

std::vector<GetElementPtrInst *> UGEPIs;

6436

// Check each user of GEPIOp to check if unmerging would make GEPIOp not alive

6437

// on IndirectBr edges.

6438

for (User *Usr : GEPIOp->users()) {

6439

if (Usr == GEPI) continue;

6440

// Check if Usr is an Instruction. If not, give up.

6441

if (!isa<Instruction>(Usr))

6442

return false;

6443

auto *UI = cast<Instruction>(Usr);

6444

// Check if Usr in the same block as GEPIOp, which is fine, skip.

6445

if (UI->getParent() == SrcBlock)

6446

continue;

6447

// Check if Usr is a GEP. If not, give up.

6448

if (!isa<GetElementPtrInst>(Usr))

6449

return false;

6450

auto *UGEPI = cast<GetElementPtrInst>(Usr);

6451

// Check if UGEPI is a simple gep with a single constant index and GEPIOp is

6452

// the pointer operand to it. If so, record it in the vector. If not, give

6453

// up.

6454

if (!GEPSequentialConstIndexed(UGEPI))

6455

return false;

6456

if (UGEPI->getOperand(0) != GEPIOp)

6457

return false;

6458

if (GEPIIdx->getType() !=

6459

cast<ConstantInt>(UGEPI->getOperand(1))->getType())

6460

return false;

6461

ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));

6462

if (TTI->getIntImmCost(UGEPIIdx->getValue(), UGEPIIdx->getType())

6463

> TargetTransformInfo::TCC_Basic)

6464

return false;

6465

UGEPIs.push_back(UGEPI);

6466

}

6467

if (UGEPIs.size() == 0)

6468

return false;

6469

// Check the materializing cost of (Uidx-Idx).

6470

for (GetElementPtrInst *UGEPI : UGEPIs) {

6471

ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));

6472

APInt NewIdx = UGEPIIdx->getValue() - GEPIIdx->getValue();

6473

unsigned ImmCost = TTI->getIntImmCost(NewIdx, GEPIIdx->getType());

6474

if (ImmCost > TargetTransformInfo::TCC_Basic)

6475

return false;

6476

}

6477

// Now unmerge between GEPI and UGEPIs.

6478

for (GetElementPtrInst *UGEPI : UGEPIs) {

6479

UGEPI->setOperand(0, GEPI);

6480

ConstantInt *UGEPIIdx = cast<ConstantInt>(UGEPI->getOperand(1));

6481

Constant *NewUGEPIIdx =

6482

ConstantInt::get(GEPIIdx->getType(),

6483

UGEPIIdx->getValue() - GEPIIdx->getValue());

6484

UGEPI->setOperand(1, NewUGEPIIdx);

6485

// If GEPI is not inbounds but UGEPI is inbounds, change UGEPI to not

6486

// inbounds to avoid UB.

6487

if (!GEPI->isInBounds()) {

6488

UGEPI->setIsInBounds(false);

6489

}

6490

}

6491

// After unmerging, verify that GEPIOp is actually only used in SrcBlock (not

6492

// alive on IndirectBr edges).

6493

assert(find_if(GEPIOp->users(), [&](User *Usr) {((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6495, __PRETTY_FUNCTION__))

6494

return cast<Instruction>(Usr)->getParent() != SrcBlock;((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6495, __PRETTY_FUNCTION__))

6495

}) == GEPIOp->users().end() && "GEPIOp is used outside SrcBlock")((find_if(GEPIOp->users(), [&](User *Usr) { return cast
<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp
->users().end() && "GEPIOp is used outside SrcBlock"
) ? static_cast<void> (0) : __assert_fail ("find_if(GEPIOp->users(), [&](User *Usr) { return cast<Instruction>(Usr)->getParent() != SrcBlock; }) == GEPIOp->users().end() && \"GEPIOp is used outside SrcBlock\""
, "/build/llvm-toolchain-snapshot-6.0~svn316259/lib/CodeGen/CodeGenPrepare.cpp"
, 6495, __PRETTY_FUNCTION__));

6496

return true;

6497

}

6498

6499

bool CodeGenPrepare::optimizeInst(Instruction *I, bool &ModifiedDT) {

6500

// Bail out if we inserted the instruction to prevent optimizations from

6501

// stepping on each other's toes.

6502

if (InsertedInsts.count(I))

6503

return false;

6504

6505

if (PHINode *P = dyn_cast<PHINode>(I)) {

6506

// It is possible for very late stage optimizations (such as SimplifyCFG)

6507

// to introduce PHI nodes too late to be cleaned up. If we detect such a

6508

// trivial PHI, go ahead and zap it here.

6509

if (Value *V = SimplifyInstruction(P, {*DL, TLInfo})) {

6510

P->replaceAllUsesWith(V);

6511

P->eraseFromParent();

6512

++NumPHIsElim;

6513

return true;

6514

}

6515

return false;

6516

}

6517

6518

if (CastInst *CI = dyn_cast<CastInst>(I)) {

6519

// If the source of the cast is a constant, then this should have

6520

// already been constant folded. The only reason NOT to constant fold

6521

// it is if something (e.g. LSR) was careful to place the constant

6522

// evaluation in a block other than then one that uses it (e.g. to hoist

6523

// the address of globals out of a loop). If this is the case, we don't

6524

// want to forward-subst the cast.

6525

if (isa<Constant>(CI->getOperand(0)))

6526

return false;

6527

6528

if (TLI && OptimizeNoopCopyExpression(CI, *TLI, *DL))

6529

return true;

6530

6531

if (isa<ZExtInst>(I) || isa<SExtInst>(I)) {

6532

/// Sink a zext or sext into its user blocks if the target type doesn't

6533

/// fit in one register

6534

if (TLI &&

6535

TLI->getTypeAction(CI->getContext(),

6536

TLI->getValueType(*DL, CI->getType())) ==

6537

TargetLowering::TypeExpandInteger) {

6538

return SinkCast(CI);

6539

} else {

6540

bool MadeChange = optimizeExt(I);

6541

return MadeChange | optimizeExtUses(I);

6542

}

6543

}

6544

return false;

6545

}

6546

6547

if (CmpInst *CI = dyn_cast<CmpInst>(I))

6548

if (!TLI || !TLI->hasMultipleConditionRegisters())

6549

return OptimizeCmpExpression(CI, TLI);

6550

6551

if (LoadInst *LI = dyn_cast<LoadInst>(I)) {

6552

LI->setMetadata(LLVMContext::MD_invariant_group, nullptr);

6553

if (TLI) {

6554

bool Modified = optimizeLoadExt(LI);

6555

unsigned AS = LI->getPointerAddressSpace();

6556

Modified |= optimizeMemoryInst(I, I->getOperand(0), LI->getType(), AS);

6557

return Modified;

6558

}

6559

return false;

6560

}

6561

6562

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

6563

if (TLI && splitMergedValStore(*SI, *DL, *TLI))

6564

return true;

6565

SI->setMetadata(LLVMContext::MD_invariant_group, nullptr);

6566

if (TLI) {

6567

unsigned AS = SI->getPointerAddressSpace();

6568

return optimizeMemoryInst(I, SI->getOperand(1),

6569

SI->getOperand(0)->getType(), AS);

6570

}

6571

return false;

6572

}

6573

6574

if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {

6575

unsigned AS = RMW->getPointerAddressSpace();

6576

return optimizeMemoryInst(I, RMW->getPointerOperand(),

6577

RMW->getType(), AS);

6578

}

6579

6580

if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(I)) {

6581

unsigned AS = CmpX->getPointerAddressSpace();

6582

return optimizeMemoryInst(I, CmpX->getPointerOperand(),

6583

CmpX->getCompareOperand()->getType(), AS);

6584

}

6585

6586

BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I);

6587

6588

if (BinOp && (BinOp->getOpcode() == Instruction::And) &&

6589

EnableAndCmpSinking && TLI)

6590

return sinkAndCmp0Expression(BinOp, *TLI, InsertedInsts);

6591

6592

if (BinOp && (BinOp->getOpcode() == Instruction::AShr ||

6593

BinOp->getOpcode() == Instruction::LShr)) {

6594

ConstantInt *CI = dyn_cast<ConstantInt>(BinOp->getOperand(1));

6595

if (TLI && CI && TLI->hasExtractBitsInsn())

6596

return OptimizeExtractBits(BinOp, CI, *TLI, *DL);

6597

6598

return false;

6599

}

6600

6601

if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {

6602

if (GEPI->hasAllZeroIndices()) {

6603

/// The GEP operand must be a pointer, so must its result -> BitCast

6604

Instruction *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(),

6605

GEPI->getName(), GEPI);

6606

GEPI->replaceAllUsesWith(NC);

6607

GEPI->eraseFromParent();

6608

++NumGEPsElim;

6609

optimizeInst(NC, ModifiedDT);

6610

return true;

6611

}

6612

if (tryUnmergingGEPsAcrossIndirectBr(GEPI, TTI)) {

6613

return true;

6614

}

6615

return false;

6616

}

6617

6618

if (CallInst *CI = dyn_cast<CallInst>(I))

6619

return optimizeCallInst(CI, ModifiedDT);

6620

6621

if (SelectInst *SI = dyn_cast<SelectInst>(I))

6622

return optimizeSelectInst(SI);

6623

6624

if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))

6625

return optimizeShuffleVectorInst(SVI);

6626

6627

if (auto *Switch = dyn_cast<SwitchInst>(I))

6628

return optimizeSwitchInst(Switch);

6629

6630

if (isa<ExtractElementInst>(I))

6631

return optimizeExtractElementInst(I);

6632

6633

return false;

6634

}

6635

6636

/// Given an OR instruction, check to see if this is a bitreverse

6637

/// idiom. If so, insert the new intrinsic and return true.

6638

static bool makeBitReverse(Instruction &I, const DataLayout &DL,

6639

const TargetLowering &TLI) {

6640

if (!I.getType()->isIntegerTy() ||

6641

!TLI.isOperationLegalOrCustom(ISD::BITREVERSE,

6642

TLI.getValueType(DL, I.getType(), true)))

6643

return false;

6644

6645

SmallVector<Instruction*, 4> Insts;

6646

if (!recognizeBSwapOrBitReverseIdiom(&I, false, true, Insts))

6647

return false;

6648

Instruction *LastInst = Insts.back();

6649

I.replaceAllUsesWith(LastInst);

6650

RecursivelyDeleteTriviallyDeadInstructions(&I);

6651

return true;

6652

}

6653

6654

// In this pass we look for GEP and cast instructions that are used

6655

// across basic blocks and rewrite them to improve basic-block-at-a-time

6656

// selection.

6657

bool CodeGenPrepare::optimizeBlock(BasicBlock &BB, bool &ModifiedDT) {

6658

SunkAddrs.clear();

6659

bool MadeChange = false;

6660

6661

CurInstIterator = BB.begin();

6662

while (CurInstIterator != BB.end()) {

6663

MadeChange |= optimizeInst(&*CurInstIterator++, ModifiedDT);

6664

if (ModifiedDT)

6665

return true;

6666

}

6667

6668

bool MadeBitReverse = true;

6669

while (TLI && MadeBitReverse) {

6670

MadeBitReverse = false;

6671

for (auto &I : reverse(BB)) {

6672

if (makeBitReverse(I, *DL, *TLI)) {

6673

MadeBitReverse = MadeChange = true;

6674

ModifiedDT = true;

6675

break;

6676

}

6677

}

6678

}

6679

MadeChange |= dupRetToEnableTailCallOpts(&BB);

6680

6681

return MadeChange;

6682

}

6683

6684

// llvm.dbg.value is far away from the value then iSel may not be able

6685

// handle it properly. iSel will drop llvm.dbg.value if it can not

6686

// find a node corresponding to the value.

6687

bool CodeGenPrepare::placeDbgValues(Function &F) {

6688

bool MadeChange = false;

6689

for (BasicBlock &BB : F) {

6690

Instruction *PrevNonDbgInst = nullptr;

6691

for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {

6692

Instruction *Insn = &*BI++;

6693

DbgValueInst *DVI = dyn_cast<DbgValueInst>(Insn);

6694

// Leave dbg.values that refer to an alloca alone. These

6695

// instrinsics describe the address of a variable (= the alloca)

6696

// being taken. They should not be moved next to the alloca

6697

// (and to the beginning of the scope), but rather stay close to

6698

// where said address is used.

6699

if (!DVI || (DVI->getValue() && isa<AllocaInst>(DVI->getValue()))) {

6700

PrevNonDbgInst = Insn;

6701

continue;

6702

}

6703

6704

Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());

6705

if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {

6706

// If VI is a phi in a block with an EHPad terminator, we can't insert

6707

// after it.

6708

if (isa<PHINode>(VI) && VI->getParent()->getTerminator()->isEHPad())

6709

continue;

6710

DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Moving Debug Value before :\n"
<< *DVI << ' ' << *VI; } } while (false);

6711

DVI->removeFromParent();

6712

if (isa<PHINode>(VI))

6713

DVI->insertBefore(&*VI->getParent()->getFirstInsertionPt());

6714

else

6715

DVI->insertAfter(VI);

6716

MadeChange = true;

6717

++NumDbgValueMoved;

6718

}

6719

}

6720

}

6721

return MadeChange;

6722

}

6723

6724

/// \brief Scale down both weights to fit into uint32_t.

6725

static void scaleWeights(uint64_t &NewTrue, uint64_t &NewFalse) {

6726

uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;

6727

uint32_t Scale = (NewMax / std::numeric_limits<uint32_t>::max()) + 1;

6728

NewTrue = NewTrue / Scale;

6729

NewFalse = NewFalse / Scale;

6730

}

6731

6732

/// \brief Some targets prefer to split a conditional branch like:

6733

/// \code

6734

/// %0 = icmp ne i32 %a, 0

6735

/// %1 = icmp ne i32 %b, 0

6736

/// %or.cond = or i1 %0, %1

6737

/// br i1 %or.cond, label %TrueBB, label %FalseBB

6738

/// \endcode

6739

/// into multiple branch instructions like:

6740

/// \code

6741

/// bb1:

6742

/// %0 = icmp ne i32 %a, 0

6743

/// br i1 %0, label %TrueBB, label %bb2

6744

/// bb2:

6745

/// %1 = icmp ne i32 %b, 0

6746

/// br i1 %1, label %TrueBB, label %FalseBB

6747

/// \endcode

6748

/// This usually allows instruction selection to do even further optimizations

6749

/// and combine the compare with the branch instruction. Currently this is

6750

/// applied for targets which have "cheap" jump instructions.

6751

///

6752

/// FIXME: Remove the (equivalent?) implementation in SelectionDAG.

6753

///

6754

bool CodeGenPrepare::splitBranchCondition(Function &F) {

6755

if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive())

6756

return false;

6757

6758

bool MadeChange = false;

6759

for (auto &BB : F) {

6760

// Does this BB end with the following?

6761

// %cond1 = icmp|fcmp|binary instruction ...

6762

// %cond2 = icmp|fcmp|binary instruction ...

6763

// %cond.or = or|and i1 %cond1, cond2

6764

// br i1 %cond.or label %dest1, label %dest2"

6765

BinaryOperator *LogicOp;

6766

BasicBlock *TBB, *FBB;

6767

if (!match(BB.getTerminator(), m_Br(m_OneUse(m_BinOp(LogicOp)), TBB, FBB)))

6768

continue;

6769

6770

auto *Br1 = cast<BranchInst>(BB.getTerminator());

6771

if (Br1->getMetadata(LLVMContext::MD_unpredictable))

6772

continue;

6773

6774

unsigned Opc;

6775

Value *Cond1, *Cond2;

6776

if (match(LogicOp, m_And(m_OneUse(m_Value(Cond1)),

6777

m_OneUse(m_Value(Cond2)))))

6778

Opc = Instruction::And;

6779

else if (match(LogicOp, m_Or(m_OneUse(m_Value(Cond1)),

6780

m_OneUse(m_Value(Cond2)))))

6781

Opc = Instruction::Or;

6782

else

6783

continue;

6784

6785

if (!match(Cond1, m_CombineOr(m_Cmp(), m_BinOp())) ||

6786

!match(Cond2, m_CombineOr(m_Cmp(), m_BinOp())) )

6787

continue;

6788

6789

DEBUG(dbgs() << "Before branch condition splitting\n"; BB.dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "Before branch condition splitting\n"
; BB.dump(); } } while (false);

6790

6791

// Create a new BB.

6792

auto TmpBB =

6793

BasicBlock::Create(BB.getContext(), BB.getName() + ".cond.split",

6794

BB.getParent(), BB.getNextNode());

6795

6796

// Update original basic block by using the first condition directly by the

6797

// branch instruction and removing the no longer needed and/or instruction.

6798

Br1->setCondition(Cond1);

6799

LogicOp->eraseFromParent();

6800

6801

// Depending on the conditon we have to either replace the true or the false

6802

// successor of the original branch instruction.

6803

if (Opc == Instruction::And)

6804

Br1->setSuccessor(0, TmpBB);

6805

else

6806

Br1->setSuccessor(1, TmpBB);

6807

6808

// Fill in the new basic block.

6809

auto *Br2 = IRBuilder<>(TmpBB).CreateCondBr(Cond2, TBB, FBB);

6810

if (auto *I = dyn_cast<Instruction>(Cond2)) {

6811

I->removeFromParent();

6812

I->insertBefore(Br2);

6813

}

6814

6815

// Update PHI nodes in both successors. The original BB needs to be

6816

// replaced in one successor's PHI nodes, because the branch comes now from

6817

// the newly generated BB (NewBB). In the other successor we need to add one

6818

// incoming edge to the PHI nodes, because both branch instructions target

6819

// now the same successor. Depending on the original branch condition

6820

// (and/or) we have to swap the successors (TrueDest, FalseDest), so that

6821

// we perform the correct update for the PHI nodes.

6822

// This doesn't change the successor order of the just created branch

6823

// instruction (or any other instruction).

6824

if (Opc == Instruction::Or)

6825

std::swap(TBB, FBB);

6826

6827

// Replace the old BB with the new BB.

6828

for (auto &I : *TBB) {

6829

PHINode *PN = dyn_cast<PHINode>(&I);

6830

if (!PN)

6831

break;

6832

int i;

6833

while ((i = PN->getBasicBlockIndex(&BB)) >= 0)

6834

PN->setIncomingBlock(i, TmpBB);

6835

}

6836

6837

// Add another incoming edge form the new BB.

6838

for (auto &I : *FBB) {

6839

PHINode *PN = dyn_cast<PHINode>(&I);

6840

if (!PN)

6841

break;

6842

auto *Val = PN->getIncomingValueForBlock(&BB);

6843

PN->addIncoming(Val, TmpBB);

6844

}

6845

6846

// Update the branch weights (from SelectionDAGBuilder::

6847

// FindMergedConditions).

6848

if (Opc == Instruction::Or) {

6849

// Codegen X | Y as:

6850

// BB1:

6851

// jmp_if_X TBB

6852

// jmp TmpBB

6853

// TmpBB:

6854

// jmp_if_Y TBB

6855

// jmp FBB

6856

6857

6858

// We have flexibility in setting Prob for BB1 and Prob for NewBB.

6859

// The requirement is that

6860

// TrueProb for BB1 + (FalseProb for BB1 * TrueProb for TmpBB)

6861

// = TrueProb for orignal BB.

6862

// Assuming the orignal weights are A and B, one choice is to set BB1's

6863

// weights to A and A+2B, and set TmpBB's weights to A and 2B. This choice

6864

// assumes that

6865

// TrueProb for BB1 == FalseProb for BB1 * TrueProb for TmpBB.

6866

// Another choice is to assume TrueProb for BB1 equals to TrueProb for

6867

// TmpBB, but the math is more complicated.

6868

uint64_t TrueWeight, FalseWeight;

6869

if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {

6870

uint64_t NewTrueWeight = TrueWeight;

6871

uint64_t NewFalseWeight = TrueWeight + 2 * FalseWeight;

6872

scaleWeights(NewTrueWeight, NewFalseWeight);

6873

Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())

6874

.createBranchWeights(TrueWeight, FalseWeight));

6875

6876

NewTrueWeight = TrueWeight;

6877

NewFalseWeight = 2 * FalseWeight;

6878

scaleWeights(NewTrueWeight, NewFalseWeight);

6879

Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())

6880

.createBranchWeights(TrueWeight, FalseWeight));

6881

}

6882

} else {

6883

// Codegen X & Y as:

6884

// BB1:

6885

// jmp_if_X TmpBB

6886

// jmp FBB

6887

// TmpBB:

6888

// jmp_if_Y TBB

6889

// jmp FBB

6890

6891

// This requires creation of TmpBB after CurBB.

6892

6893

// We have flexibility in setting Prob for BB1 and Prob for TmpBB.

6894

// The requirement is that

6895

// FalseProb for BB1 + (TrueProb for BB1 * FalseProb for TmpBB)

6896

// = FalseProb for orignal BB.

6897

// Assuming the orignal weights are A and B, one choice is to set BB1's

6898

// weights to 2A+B and B, and set TmpBB's weights to 2A and B. This choice

6899

// assumes that

6900

// FalseProb for BB1 == TrueProb for BB1 * FalseProb for TmpBB.

6901

uint64_t TrueWeight, FalseWeight;

6902

if (Br1->extractProfMetadata(TrueWeight, FalseWeight)) {

6903

uint64_t NewTrueWeight = 2 * TrueWeight + FalseWeight;

6904

uint64_t NewFalseWeight = FalseWeight;

6905

scaleWeights(NewTrueWeight, NewFalseWeight);

6906

Br1->setMetadata(LLVMContext::MD_prof, MDBuilder(Br1->getContext())

6907

.createBranchWeights(TrueWeight, FalseWeight));

6908

6909

NewTrueWeight = 2 * TrueWeight;

6910

NewFalseWeight = FalseWeight;

6911

scaleWeights(NewTrueWeight, NewFalseWeight);

6912

Br2->setMetadata(LLVMContext::MD_prof, MDBuilder(Br2->getContext())

6913

.createBranchWeights(TrueWeight, FalseWeight));

6914

}

6915

}

6916

6917

// Note: No point in getting fancy here, since the DT info is never

6918

// available to CodeGenPrepare.

6919

ModifiedDT = true;

6920

6921

MadeChange = true;

6922

6923

DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump();do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (false)

6924

TmpBB->dump())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("codegenprepare")) { dbgs() << "After branch condition splitting\n"
; BB.dump(); TmpBB->dump(); } } while (false);

6925

}

6926

return MadeChange;

6927

}