1 //===-- PPCCTRLoops.cpp - Identify and generate CTR loops -----------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This pass identifies loops where we can generate the PPC branch instructions 11 // that decrement and test the count register (CTR) (bdnz and friends). 12 // 13 // The pattern that defines the induction variable can changed depending on 14 // prior optimizations. For example, the IndVarSimplify phase run by 'opt' 15 // normalizes induction variables, and the Loop Strength Reduction pass 16 // run by 'llc' may also make changes to the induction variable. 17 // 18 // Criteria for CTR loops: 19 // - Countable loops (w/ ind. var for a trip count) 20 // - Try inner-most loops first 21 // - No nested CTR loops. 22 // - No function calls in loops. 23 // 24 //===----------------------------------------------------------------------===// 25 26 #include "llvm/Transforms/Scalar.h" 27 #include "PPC.h" 28 #include "PPCTargetMachine.h" 29 #include "llvm/ADT/STLExtras.h" 30 #include "llvm/ADT/Statistic.h" 31 #include "llvm/Analysis/LoopInfo.h" 32 #include "llvm/Analysis/ScalarEvolutionExpander.h" 33 #include "llvm/IR/Constants.h" 34 #include "llvm/IR/DerivedTypes.h" 35 #include "llvm/IR/Dominators.h" 36 #include "llvm/IR/InlineAsm.h" 37 #include "llvm/IR/Instructions.h" 38 #include "llvm/IR/IntrinsicInst.h" 39 #include "llvm/IR/Module.h" 40 #include "llvm/IR/ValueHandle.h" 41 #include "llvm/PassSupport.h" 42 #include "llvm/Support/CommandLine.h" 43 #include "llvm/Support/Debug.h" 44 #include "llvm/Support/raw_ostream.h" 45 #include "llvm/Target/TargetLibraryInfo.h" 46 #include "llvm/Transforms/Utils/BasicBlockUtils.h" 47 #include "llvm/Transforms/Utils/Local.h" 48 #include "llvm/Transforms/Utils/LoopUtils.h" 49 50 #ifndef NDEBUG 51 #include "llvm/CodeGen/MachineDominators.h" 52 #include "llvm/CodeGen/MachineFunction.h" 53 #include "llvm/CodeGen/MachineFunctionPass.h" 54 #include "llvm/CodeGen/MachineRegisterInfo.h" 55 #endif 56 57 #include <algorithm> 58 #include <vector> 59 60 using namespace llvm; 61 62 #define DEBUG_TYPE "ctrloops" 63 64 #ifndef NDEBUG 65 static cl::opt<int> CTRLoopLimit("ppc-max-ctrloop", cl::Hidden, cl::init(-1)); 66 #endif 67 68 STATISTIC(NumCTRLoops, "Number of loops converted to CTR loops"); 69 70 namespace llvm { 71 void initializePPCCTRLoopsPass(PassRegistry&); 72 #ifndef NDEBUG 73 void initializePPCCTRLoopsVerifyPass(PassRegistry&); 74 #endif 75 } 76 77 namespace { 78 struct PPCCTRLoops : public FunctionPass { 79 80 #ifndef NDEBUG 81 static int Counter; 82 #endif 83 84 public: 85 static char ID; 86 87 PPCCTRLoops() : FunctionPass(ID), TM(nullptr) { 88 initializePPCCTRLoopsPass(*PassRegistry::getPassRegistry()); 89 } 90 PPCCTRLoops(PPCTargetMachine &TM) : FunctionPass(ID), TM(&TM) { 91 initializePPCCTRLoopsPass(*PassRegistry::getPassRegistry()); 92 } 93 94 bool runOnFunction(Function &F) override; 95 96 void getAnalysisUsage(AnalysisUsage &AU) const override { 97 AU.addRequired<LoopInfo>(); 98 AU.addPreserved<LoopInfo>(); 99 AU.addRequired<DominatorTreeWrapperPass>(); 100 AU.addPreserved<DominatorTreeWrapperPass>(); 101 AU.addRequired<ScalarEvolution>(); 102 } 103 104 private: 105 bool mightUseCTR(const Triple &TT, BasicBlock *BB); 106 bool convertToCTRLoop(Loop *L); 107 108 private: 109 PPCTargetMachine *TM; 110 LoopInfo *LI; 111 ScalarEvolution *SE; 112 const DataLayout *DL; 113 DominatorTree *DT; 114 const TargetLibraryInfo *LibInfo; 115 }; 116 117 char PPCCTRLoops::ID = 0; 118 #ifndef NDEBUG 119 int PPCCTRLoops::Counter = 0; 120 #endif 121 122 #ifndef NDEBUG 123 struct PPCCTRLoopsVerify : public MachineFunctionPass { 124 public: 125 static char ID; 126 127 PPCCTRLoopsVerify() : MachineFunctionPass(ID) { 128 initializePPCCTRLoopsVerifyPass(*PassRegistry::getPassRegistry()); 129 } 130 131 void getAnalysisUsage(AnalysisUsage &AU) const override { 132 AU.addRequired<MachineDominatorTree>(); 133 MachineFunctionPass::getAnalysisUsage(AU); 134 } 135 136 bool runOnMachineFunction(MachineFunction &MF) override; 137 138 private: 139 MachineDominatorTree *MDT; 140 }; 141 142 char PPCCTRLoopsVerify::ID = 0; 143 #endif // NDEBUG 144 } // end anonymous namespace 145 146 INITIALIZE_PASS_BEGIN(PPCCTRLoops, "ppc-ctr-loops", "PowerPC CTR Loops", 147 false, false) 148 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) 149 INITIALIZE_PASS_DEPENDENCY(LoopInfo) 150 INITIALIZE_PASS_DEPENDENCY(ScalarEvolution) 151 INITIALIZE_PASS_END(PPCCTRLoops, "ppc-ctr-loops", "PowerPC CTR Loops", 152 false, false) 153 154 FunctionPass *llvm::createPPCCTRLoops(PPCTargetMachine &TM) { 155 return new PPCCTRLoops(TM); 156 } 157 158 #ifndef NDEBUG 159 INITIALIZE_PASS_BEGIN(PPCCTRLoopsVerify, "ppc-ctr-loops-verify", 160 "PowerPC CTR Loops Verify", false, false) 161 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) 162 INITIALIZE_PASS_END(PPCCTRLoopsVerify, "ppc-ctr-loops-verify", 163 "PowerPC CTR Loops Verify", false, false) 164 165 FunctionPass *llvm::createPPCCTRLoopsVerify() { 166 return new PPCCTRLoopsVerify(); 167 } 168 #endif // NDEBUG 169 170 bool PPCCTRLoops::runOnFunction(Function &F) { 171 LI = &getAnalysis<LoopInfo>(); 172 SE = &getAnalysis<ScalarEvolution>(); 173 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); 174 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); 175 DL = DLP ? &DLP->getDataLayout() : nullptr; 176 LibInfo = getAnalysisIfAvailable<TargetLibraryInfo>(); 177 178 bool MadeChange = false; 179 180 for (LoopInfo::iterator I = LI->begin(), E = LI->end(); 181 I != E; ++I) { 182 Loop *L = *I; 183 if (!L->getParentLoop()) 184 MadeChange |= convertToCTRLoop(L); 185 } 186 187 return MadeChange; 188 } 189 190 static bool isLargeIntegerTy(bool Is32Bit, Type *Ty) { 191 if (IntegerType *ITy = dyn_cast<IntegerType>(Ty)) 192 return ITy->getBitWidth() > (Is32Bit ? 32U : 64U); 193 194 return false; 195 } 196 197 bool PPCCTRLoops::mightUseCTR(const Triple &TT, BasicBlock *BB) { 198 for (BasicBlock::iterator J = BB->begin(), JE = BB->end(); 199 J != JE; ++J) { 200 if (CallInst *CI = dyn_cast<CallInst>(J)) { 201 if (InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue())) { 202 // Inline ASM is okay, unless it clobbers the ctr register. 203 InlineAsm::ConstraintInfoVector CIV = IA->ParseConstraints(); 204 for (unsigned i = 0, ie = CIV.size(); i < ie; ++i) { 205 InlineAsm::ConstraintInfo &C = CIV[i]; 206 if (C.Type != InlineAsm::isInput) 207 for (unsigned j = 0, je = C.Codes.size(); j < je; ++j) 208 if (StringRef(C.Codes[j]).equals_lower("{ctr}")) 209 return true; 210 } 211 212 continue; 213 } 214 215 if (!TM) 216 return true; 217 const TargetLowering *TLI = TM->getTargetLowering(); 218 219 if (Function *F = CI->getCalledFunction()) { 220 // Most intrinsics don't become function calls, but some might. 221 // sin, cos, exp and log are always calls. 222 unsigned Opcode; 223 if (F->getIntrinsicID() != Intrinsic::not_intrinsic) { 224 switch (F->getIntrinsicID()) { 225 default: continue; 226 227 // VisualStudio defines setjmp as _setjmp 228 #if defined(_MSC_VER) && defined(setjmp) && \ 229 !defined(setjmp_undefined_for_msvc) 230 # pragma push_macro("setjmp") 231 # undef setjmp 232 # define setjmp_undefined_for_msvc 233 #endif 234 235 case Intrinsic::setjmp: 236 237 #if defined(_MSC_VER) && defined(setjmp_undefined_for_msvc) 238 // let's return it to _setjmp state 239 # pragma pop_macro("setjmp") 240 # undef setjmp_undefined_for_msvc 241 #endif 242 243 case Intrinsic::longjmp: 244 245 // Exclude eh_sjlj_setjmp; we don't need to exclude eh_sjlj_longjmp 246 // because, although it does clobber the counter register, the 247 // control can't then return to inside the loop unless there is also 248 // an eh_sjlj_setjmp. 249 case Intrinsic::eh_sjlj_setjmp: 250 251 case Intrinsic::memcpy: 252 case Intrinsic::memmove: 253 case Intrinsic::memset: 254 case Intrinsic::powi: 255 case Intrinsic::log: 256 case Intrinsic::log2: 257 case Intrinsic::log10: 258 case Intrinsic::exp: 259 case Intrinsic::exp2: 260 case Intrinsic::pow: 261 case Intrinsic::sin: 262 case Intrinsic::cos: 263 return true; 264 case Intrinsic::copysign: 265 if (CI->getArgOperand(0)->getType()->getScalarType()-> 266 isPPC_FP128Ty()) 267 return true; 268 else 269 continue; // ISD::FCOPYSIGN is never a library call. 270 case Intrinsic::sqrt: Opcode = ISD::FSQRT; break; 271 case Intrinsic::floor: Opcode = ISD::FFLOOR; break; 272 case Intrinsic::ceil: Opcode = ISD::FCEIL; break; 273 case Intrinsic::trunc: Opcode = ISD::FTRUNC; break; 274 case Intrinsic::rint: Opcode = ISD::FRINT; break; 275 case Intrinsic::nearbyint: Opcode = ISD::FNEARBYINT; break; 276 case Intrinsic::round: Opcode = ISD::FROUND; break; 277 } 278 } 279 280 // PowerPC does not use [US]DIVREM or other library calls for 281 // operations on regular types which are not otherwise library calls 282 // (i.e. soft float or atomics). If adapting for targets that do, 283 // additional care is required here. 284 285 LibFunc::Func Func; 286 if (!F->hasLocalLinkage() && F->hasName() && LibInfo && 287 LibInfo->getLibFunc(F->getName(), Func) && 288 LibInfo->hasOptimizedCodeGen(Func)) { 289 // Non-read-only functions are never treated as intrinsics. 290 if (!CI->onlyReadsMemory()) 291 return true; 292 293 // Conversion happens only for FP calls. 294 if (!CI->getArgOperand(0)->getType()->isFloatingPointTy()) 295 return true; 296 297 switch (Func) { 298 default: return true; 299 case LibFunc::copysign: 300 case LibFunc::copysignf: 301 continue; // ISD::FCOPYSIGN is never a library call. 302 case LibFunc::copysignl: 303 return true; 304 case LibFunc::fabs: 305 case LibFunc::fabsf: 306 case LibFunc::fabsl: 307 continue; // ISD::FABS is never a library call. 308 case LibFunc::sqrt: 309 case LibFunc::sqrtf: 310 case LibFunc::sqrtl: 311 Opcode = ISD::FSQRT; break; 312 case LibFunc::floor: 313 case LibFunc::floorf: 314 case LibFunc::floorl: 315 Opcode = ISD::FFLOOR; break; 316 case LibFunc::nearbyint: 317 case LibFunc::nearbyintf: 318 case LibFunc::nearbyintl: 319 Opcode = ISD::FNEARBYINT; break; 320 case LibFunc::ceil: 321 case LibFunc::ceilf: 322 case LibFunc::ceill: 323 Opcode = ISD::FCEIL; break; 324 case LibFunc::rint: 325 case LibFunc::rintf: 326 case LibFunc::rintl: 327 Opcode = ISD::FRINT; break; 328 case LibFunc::round: 329 case LibFunc::roundf: 330 case LibFunc::roundl: 331 Opcode = ISD::FROUND; break; 332 case LibFunc::trunc: 333 case LibFunc::truncf: 334 case LibFunc::truncl: 335 Opcode = ISD::FTRUNC; break; 336 } 337 338 MVT VTy = 339 TLI->getSimpleValueType(CI->getArgOperand(0)->getType(), true); 340 if (VTy == MVT::Other) 341 return true; 342 343 if (TLI->isOperationLegalOrCustom(Opcode, VTy)) 344 continue; 345 else if (VTy.isVector() && 346 TLI->isOperationLegalOrCustom(Opcode, VTy.getScalarType())) 347 continue; 348 349 return true; 350 } 351 } 352 353 return true; 354 } else if (isa<BinaryOperator>(J) && 355 J->getType()->getScalarType()->isPPC_FP128Ty()) { 356 // Most operations on ppc_f128 values become calls. 357 return true; 358 } else if (isa<UIToFPInst>(J) || isa<SIToFPInst>(J) || 359 isa<FPToUIInst>(J) || isa<FPToSIInst>(J)) { 360 CastInst *CI = cast<CastInst>(J); 361 if (CI->getSrcTy()->getScalarType()->isPPC_FP128Ty() || 362 CI->getDestTy()->getScalarType()->isPPC_FP128Ty() || 363 isLargeIntegerTy(TT.isArch32Bit(), CI->getSrcTy()->getScalarType()) || 364 isLargeIntegerTy(TT.isArch32Bit(), CI->getDestTy()->getScalarType())) 365 return true; 366 } else if (isLargeIntegerTy(TT.isArch32Bit(), 367 J->getType()->getScalarType()) && 368 (J->getOpcode() == Instruction::UDiv || 369 J->getOpcode() == Instruction::SDiv || 370 J->getOpcode() == Instruction::URem || 371 J->getOpcode() == Instruction::SRem)) { 372 return true; 373 } else if (TT.isArch32Bit() && 374 isLargeIntegerTy(false, J->getType()->getScalarType()) && 375 (J->getOpcode() == Instruction::Shl || 376 J->getOpcode() == Instruction::AShr || 377 J->getOpcode() == Instruction::LShr)) { 378 // Only on PPC32, for 128-bit integers (specifically not 64-bit 379 // integers), these might be runtime calls. 380 return true; 381 } else if (isa<IndirectBrInst>(J) || isa<InvokeInst>(J)) { 382 // On PowerPC, indirect jumps use the counter register. 383 return true; 384 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(J)) { 385 if (!TM) 386 return true; 387 const TargetLowering *TLI = TM->getTargetLowering(); 388 389 if (TLI->supportJumpTables() && 390 SI->getNumCases()+1 >= (unsigned) TLI->getMinimumJumpTableEntries()) 391 return true; 392 } 393 } 394 395 return false; 396 } 397 398 bool PPCCTRLoops::convertToCTRLoop(Loop *L) { 399 bool MadeChange = false; 400 401 Triple TT = Triple(L->getHeader()->getParent()->getParent()-> 402 getTargetTriple()); 403 if (!TT.isArch32Bit() && !TT.isArch64Bit()) 404 return MadeChange; // Unknown arch. type. 405 406 // Process nested loops first. 407 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) { 408 MadeChange |= convertToCTRLoop(*I); 409 } 410 411 // If a nested loop has been converted, then we can't convert this loop. 412 if (MadeChange) 413 return MadeChange; 414 415 #ifndef NDEBUG 416 // Stop trying after reaching the limit (if any). 417 int Limit = CTRLoopLimit; 418 if (Limit >= 0) { 419 if (Counter >= CTRLoopLimit) 420 return false; 421 Counter++; 422 } 423 #endif 424 425 // We don't want to spill/restore the counter register, and so we don't 426 // want to use the counter register if the loop contains calls. 427 for (Loop::block_iterator I = L->block_begin(), IE = L->block_end(); 428 I != IE; ++I) 429 if (mightUseCTR(TT, *I)) 430 return MadeChange; 431 432 SmallVector<BasicBlock*, 4> ExitingBlocks; 433 L->getExitingBlocks(ExitingBlocks); 434 435 BasicBlock *CountedExitBlock = nullptr; 436 const SCEV *ExitCount = nullptr; 437 BranchInst *CountedExitBranch = nullptr; 438 for (SmallVectorImpl<BasicBlock *>::iterator I = ExitingBlocks.begin(), 439 IE = ExitingBlocks.end(); I != IE; ++I) { 440 const SCEV *EC = SE->getExitCount(L, *I); 441 DEBUG(dbgs() << "Exit Count for " << *L << " from block " << 442 (*I)->getName() << ": " << *EC << "\n"); 443 if (isa<SCEVCouldNotCompute>(EC)) 444 continue; 445 if (const SCEVConstant *ConstEC = dyn_cast<SCEVConstant>(EC)) { 446 if (ConstEC->getValue()->isZero()) 447 continue; 448 } else if (!SE->isLoopInvariant(EC, L)) 449 continue; 450 451 if (SE->getTypeSizeInBits(EC->getType()) > (TT.isArch64Bit() ? 64 : 32)) 452 continue; 453 454 // We now have a loop-invariant count of loop iterations (which is not the 455 // constant zero) for which we know that this loop will not exit via this 456 // exisiting block. 457 458 // We need to make sure that this block will run on every loop iteration. 459 // For this to be true, we must dominate all blocks with backedges. Such 460 // blocks are in-loop predecessors to the header block. 461 bool NotAlways = false; 462 for (pred_iterator PI = pred_begin(L->getHeader()), 463 PIE = pred_end(L->getHeader()); PI != PIE; ++PI) { 464 if (!L->contains(*PI)) 465 continue; 466 467 if (!DT->dominates(*I, *PI)) { 468 NotAlways = true; 469 break; 470 } 471 } 472 473 if (NotAlways) 474 continue; 475 476 // Make sure this blocks ends with a conditional branch. 477 Instruction *TI = (*I)->getTerminator(); 478 if (!TI) 479 continue; 480 481 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 482 if (!BI->isConditional()) 483 continue; 484 485 CountedExitBranch = BI; 486 } else 487 continue; 488 489 // Note that this block may not be the loop latch block, even if the loop 490 // has a latch block. 491 CountedExitBlock = *I; 492 ExitCount = EC; 493 break; 494 } 495 496 if (!CountedExitBlock) 497 return MadeChange; 498 499 BasicBlock *Preheader = L->getLoopPreheader(); 500 501 // If we don't have a preheader, then insert one. If we already have a 502 // preheader, then we can use it (except if the preheader contains a use of 503 // the CTR register because some such uses might be reordered by the 504 // selection DAG after the mtctr instruction). 505 if (!Preheader || mightUseCTR(TT, Preheader)) 506 Preheader = InsertPreheaderForLoop(L, this); 507 if (!Preheader) 508 return MadeChange; 509 510 DEBUG(dbgs() << "Preheader for exit count: " << Preheader->getName() << "\n"); 511 512 // Insert the count into the preheader and replace the condition used by the 513 // selected branch. 514 MadeChange = true; 515 516 SCEVExpander SCEVE(*SE, "loopcnt"); 517 LLVMContext &C = SE->getContext(); 518 Type *CountType = TT.isArch64Bit() ? Type::getInt64Ty(C) : 519 Type::getInt32Ty(C); 520 if (!ExitCount->getType()->isPointerTy() && 521 ExitCount->getType() != CountType) 522 ExitCount = SE->getZeroExtendExpr(ExitCount, CountType); 523 ExitCount = SE->getAddExpr(ExitCount, 524 SE->getConstant(CountType, 1)); 525 Value *ECValue = SCEVE.expandCodeFor(ExitCount, CountType, 526 Preheader->getTerminator()); 527 528 IRBuilder<> CountBuilder(Preheader->getTerminator()); 529 Module *M = Preheader->getParent()->getParent(); 530 Value *MTCTRFunc = Intrinsic::getDeclaration(M, Intrinsic::ppc_mtctr, 531 CountType); 532 CountBuilder.CreateCall(MTCTRFunc, ECValue); 533 534 IRBuilder<> CondBuilder(CountedExitBranch); 535 Value *DecFunc = 536 Intrinsic::getDeclaration(M, Intrinsic::ppc_is_decremented_ctr_nonzero); 537 Value *NewCond = CondBuilder.CreateCall(DecFunc); 538 Value *OldCond = CountedExitBranch->getCondition(); 539 CountedExitBranch->setCondition(NewCond); 540 541 // The false branch must exit the loop. 542 if (!L->contains(CountedExitBranch->getSuccessor(0))) 543 CountedExitBranch->swapSuccessors(); 544 545 // The old condition may be dead now, and may have even created a dead PHI 546 // (the original induction variable). 547 RecursivelyDeleteTriviallyDeadInstructions(OldCond); 548 DeleteDeadPHIs(CountedExitBlock); 549 550 ++NumCTRLoops; 551 return MadeChange; 552 } 553 554 #ifndef NDEBUG 555 static bool clobbersCTR(const MachineInstr *MI) { 556 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 557 const MachineOperand &MO = MI->getOperand(i); 558 if (MO.isReg()) { 559 if (MO.isDef() && (MO.getReg() == PPC::CTR || MO.getReg() == PPC::CTR8)) 560 return true; 561 } else if (MO.isRegMask()) { 562 if (MO.clobbersPhysReg(PPC::CTR) || MO.clobbersPhysReg(PPC::CTR8)) 563 return true; 564 } 565 } 566 567 return false; 568 } 569 570 static bool verifyCTRBranch(MachineBasicBlock *MBB, 571 MachineBasicBlock::iterator I) { 572 MachineBasicBlock::iterator BI = I; 573 SmallSet<MachineBasicBlock *, 16> Visited; 574 SmallVector<MachineBasicBlock *, 8> Preds; 575 bool CheckPreds; 576 577 if (I == MBB->begin()) { 578 Visited.insert(MBB); 579 goto queue_preds; 580 } else 581 --I; 582 583 check_block: 584 Visited.insert(MBB); 585 if (I == MBB->end()) 586 goto queue_preds; 587 588 CheckPreds = true; 589 for (MachineBasicBlock::iterator IE = MBB->begin();; --I) { 590 unsigned Opc = I->getOpcode(); 591 if (Opc == PPC::MTCTRloop || Opc == PPC::MTCTR8loop) { 592 CheckPreds = false; 593 break; 594 } 595 596 if (I != BI && clobbersCTR(I)) { 597 DEBUG(dbgs() << "BB#" << MBB->getNumber() << " (" << 598 MBB->getFullName() << ") instruction " << *I << 599 " clobbers CTR, invalidating " << "BB#" << 600 BI->getParent()->getNumber() << " (" << 601 BI->getParent()->getFullName() << ") instruction " << 602 *BI << "\n"); 603 return false; 604 } 605 606 if (I == IE) 607 break; 608 } 609 610 if (!CheckPreds && Preds.empty()) 611 return true; 612 613 if (CheckPreds) { 614 queue_preds: 615 if (MachineFunction::iterator(MBB) == MBB->getParent()->begin()) { 616 DEBUG(dbgs() << "Unable to find a MTCTR instruction for BB#" << 617 BI->getParent()->getNumber() << " (" << 618 BI->getParent()->getFullName() << ") instruction " << 619 *BI << "\n"); 620 return false; 621 } 622 623 for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(), 624 PIE = MBB->pred_end(); PI != PIE; ++PI) 625 Preds.push_back(*PI); 626 } 627 628 do { 629 MBB = Preds.pop_back_val(); 630 if (!Visited.count(MBB)) { 631 I = MBB->getLastNonDebugInstr(); 632 goto check_block; 633 } 634 } while (!Preds.empty()); 635 636 return true; 637 } 638 639 bool PPCCTRLoopsVerify::runOnMachineFunction(MachineFunction &MF) { 640 MDT = &getAnalysis<MachineDominatorTree>(); 641 642 // Verify that all bdnz/bdz instructions are dominated by a loop mtctr before 643 // any other instructions that might clobber the ctr register. 644 for (MachineFunction::iterator I = MF.begin(), IE = MF.end(); 645 I != IE; ++I) { 646 MachineBasicBlock *MBB = I; 647 if (!MDT->isReachableFromEntry(MBB)) 648 continue; 649 650 for (MachineBasicBlock::iterator MII = MBB->getFirstTerminator(), 651 MIIE = MBB->end(); MII != MIIE; ++MII) { 652 unsigned Opc = MII->getOpcode(); 653 if (Opc == PPC::BDNZ8 || Opc == PPC::BDNZ || 654 Opc == PPC::BDZ8 || Opc == PPC::BDZ) 655 if (!verifyCTRBranch(MBB, MII)) 656 llvm_unreachable("Invalid PPC CTR loop!"); 657 } 658 } 659 660 return false; 661 } 662 #endif // NDEBUG 663 664