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/Analysis/TargetLibraryInfo.h" 34 #include "llvm/IR/Constants.h" 35 #include "llvm/IR/DerivedTypes.h" 36 #include "llvm/IR/Dominators.h" 37 #include "llvm/IR/InlineAsm.h" 38 #include "llvm/IR/Instructions.h" 39 #include "llvm/IR/IntrinsicInst.h" 40 #include "llvm/IR/Module.h" 41 #include "llvm/IR/ValueHandle.h" 42 #include "llvm/PassSupport.h" 43 #include "llvm/Support/CommandLine.h" 44 #include "llvm/Support/Debug.h" 45 #include "llvm/Support/raw_ostream.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 // Determining the address of a TLS variable results in a function call in 198 // certain TLS models. 199 static bool memAddrUsesCTR(const PPCTargetMachine *TM, 200 const llvm::Value *MemAddr) { 201 const auto *GV = dyn_cast<GlobalValue>(MemAddr); 202 if (!GV) 203 return false; 204 if (!GV->isThreadLocal()) 205 return false; 206 if (!TM) 207 return true; 208 TLSModel::Model Model = TM->getTLSModel(GV); 209 return Model == TLSModel::GeneralDynamic || Model == TLSModel::LocalDynamic; 210 } 211 212 bool PPCCTRLoops::mightUseCTR(const Triple &TT, BasicBlock *BB) { 213 for (BasicBlock::iterator J = BB->begin(), JE = BB->end(); 214 J != JE; ++J) { 215 if (CallInst *CI = dyn_cast<CallInst>(J)) { 216 if (InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue())) { 217 // Inline ASM is okay, unless it clobbers the ctr register. 218 InlineAsm::ConstraintInfoVector CIV = IA->ParseConstraints(); 219 for (unsigned i = 0, ie = CIV.size(); i < ie; ++i) { 220 InlineAsm::ConstraintInfo &C = CIV[i]; 221 if (C.Type != InlineAsm::isInput) 222 for (unsigned j = 0, je = C.Codes.size(); j < je; ++j) 223 if (StringRef(C.Codes[j]).equals_lower("{ctr}")) 224 return true; 225 } 226 227 continue; 228 } 229 230 if (!TM) 231 return true; 232 const TargetLowering *TLI = TM->getSubtargetImpl()->getTargetLowering(); 233 234 if (Function *F = CI->getCalledFunction()) { 235 // Most intrinsics don't become function calls, but some might. 236 // sin, cos, exp and log are always calls. 237 unsigned Opcode; 238 if (F->getIntrinsicID() != Intrinsic::not_intrinsic) { 239 switch (F->getIntrinsicID()) { 240 default: continue; 241 242 // VisualStudio defines setjmp as _setjmp 243 #if defined(_MSC_VER) && defined(setjmp) && \ 244 !defined(setjmp_undefined_for_msvc) 245 # pragma push_macro("setjmp") 246 # undef setjmp 247 # define setjmp_undefined_for_msvc 248 #endif 249 250 case Intrinsic::setjmp: 251 252 #if defined(_MSC_VER) && defined(setjmp_undefined_for_msvc) 253 // let's return it to _setjmp state 254 # pragma pop_macro("setjmp") 255 # undef setjmp_undefined_for_msvc 256 #endif 257 258 case Intrinsic::longjmp: 259 260 // Exclude eh_sjlj_setjmp; we don't need to exclude eh_sjlj_longjmp 261 // because, although it does clobber the counter register, the 262 // control can't then return to inside the loop unless there is also 263 // an eh_sjlj_setjmp. 264 case Intrinsic::eh_sjlj_setjmp: 265 266 case Intrinsic::memcpy: 267 case Intrinsic::memmove: 268 case Intrinsic::memset: 269 case Intrinsic::powi: 270 case Intrinsic::log: 271 case Intrinsic::log2: 272 case Intrinsic::log10: 273 case Intrinsic::exp: 274 case Intrinsic::exp2: 275 case Intrinsic::pow: 276 case Intrinsic::sin: 277 case Intrinsic::cos: 278 return true; 279 case Intrinsic::copysign: 280 if (CI->getArgOperand(0)->getType()->getScalarType()-> 281 isPPC_FP128Ty()) 282 return true; 283 else 284 continue; // ISD::FCOPYSIGN is never a library call. 285 case Intrinsic::sqrt: Opcode = ISD::FSQRT; break; 286 case Intrinsic::floor: Opcode = ISD::FFLOOR; break; 287 case Intrinsic::ceil: Opcode = ISD::FCEIL; break; 288 case Intrinsic::trunc: Opcode = ISD::FTRUNC; break; 289 case Intrinsic::rint: Opcode = ISD::FRINT; break; 290 case Intrinsic::nearbyint: Opcode = ISD::FNEARBYINT; break; 291 case Intrinsic::round: Opcode = ISD::FROUND; break; 292 } 293 } 294 295 // PowerPC does not use [US]DIVREM or other library calls for 296 // operations on regular types which are not otherwise library calls 297 // (i.e. soft float or atomics). If adapting for targets that do, 298 // additional care is required here. 299 300 LibFunc::Func Func; 301 if (!F->hasLocalLinkage() && F->hasName() && LibInfo && 302 LibInfo->getLibFunc(F->getName(), Func) && 303 LibInfo->hasOptimizedCodeGen(Func)) { 304 // Non-read-only functions are never treated as intrinsics. 305 if (!CI->onlyReadsMemory()) 306 return true; 307 308 // Conversion happens only for FP calls. 309 if (!CI->getArgOperand(0)->getType()->isFloatingPointTy()) 310 return true; 311 312 switch (Func) { 313 default: return true; 314 case LibFunc::copysign: 315 case LibFunc::copysignf: 316 continue; // ISD::FCOPYSIGN is never a library call. 317 case LibFunc::copysignl: 318 return true; 319 case LibFunc::fabs: 320 case LibFunc::fabsf: 321 case LibFunc::fabsl: 322 continue; // ISD::FABS is never a library call. 323 case LibFunc::sqrt: 324 case LibFunc::sqrtf: 325 case LibFunc::sqrtl: 326 Opcode = ISD::FSQRT; break; 327 case LibFunc::floor: 328 case LibFunc::floorf: 329 case LibFunc::floorl: 330 Opcode = ISD::FFLOOR; break; 331 case LibFunc::nearbyint: 332 case LibFunc::nearbyintf: 333 case LibFunc::nearbyintl: 334 Opcode = ISD::FNEARBYINT; break; 335 case LibFunc::ceil: 336 case LibFunc::ceilf: 337 case LibFunc::ceill: 338 Opcode = ISD::FCEIL; break; 339 case LibFunc::rint: 340 case LibFunc::rintf: 341 case LibFunc::rintl: 342 Opcode = ISD::FRINT; break; 343 case LibFunc::round: 344 case LibFunc::roundf: 345 case LibFunc::roundl: 346 Opcode = ISD::FROUND; break; 347 case LibFunc::trunc: 348 case LibFunc::truncf: 349 case LibFunc::truncl: 350 Opcode = ISD::FTRUNC; break; 351 } 352 353 MVT VTy = 354 TLI->getSimpleValueType(CI->getArgOperand(0)->getType(), true); 355 if (VTy == MVT::Other) 356 return true; 357 358 if (TLI->isOperationLegalOrCustom(Opcode, VTy)) 359 continue; 360 else if (VTy.isVector() && 361 TLI->isOperationLegalOrCustom(Opcode, VTy.getScalarType())) 362 continue; 363 364 return true; 365 } 366 } 367 368 return true; 369 } else if (isa<BinaryOperator>(J) && 370 J->getType()->getScalarType()->isPPC_FP128Ty()) { 371 // Most operations on ppc_f128 values become calls. 372 return true; 373 } else if (isa<UIToFPInst>(J) || isa<SIToFPInst>(J) || 374 isa<FPToUIInst>(J) || isa<FPToSIInst>(J)) { 375 CastInst *CI = cast<CastInst>(J); 376 if (CI->getSrcTy()->getScalarType()->isPPC_FP128Ty() || 377 CI->getDestTy()->getScalarType()->isPPC_FP128Ty() || 378 isLargeIntegerTy(TT.isArch32Bit(), CI->getSrcTy()->getScalarType()) || 379 isLargeIntegerTy(TT.isArch32Bit(), CI->getDestTy()->getScalarType())) 380 return true; 381 } else if (isLargeIntegerTy(TT.isArch32Bit(), 382 J->getType()->getScalarType()) && 383 (J->getOpcode() == Instruction::UDiv || 384 J->getOpcode() == Instruction::SDiv || 385 J->getOpcode() == Instruction::URem || 386 J->getOpcode() == Instruction::SRem)) { 387 return true; 388 } else if (TT.isArch32Bit() && 389 isLargeIntegerTy(false, J->getType()->getScalarType()) && 390 (J->getOpcode() == Instruction::Shl || 391 J->getOpcode() == Instruction::AShr || 392 J->getOpcode() == Instruction::LShr)) { 393 // Only on PPC32, for 128-bit integers (specifically not 64-bit 394 // integers), these might be runtime calls. 395 return true; 396 } else if (isa<IndirectBrInst>(J) || isa<InvokeInst>(J)) { 397 // On PowerPC, indirect jumps use the counter register. 398 return true; 399 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(J)) { 400 if (!TM) 401 return true; 402 const TargetLowering *TLI = TM->getSubtargetImpl()->getTargetLowering(); 403 404 if (SI->getNumCases() + 1 >= (unsigned)TLI->getMinimumJumpTableEntries()) 405 return true; 406 } 407 for (Value *Operand : J->operands()) 408 if (memAddrUsesCTR(TM, Operand)) 409 return true; 410 } 411 412 return false; 413 } 414 415 bool PPCCTRLoops::convertToCTRLoop(Loop *L) { 416 bool MadeChange = false; 417 418 Triple TT = Triple(L->getHeader()->getParent()->getParent()-> 419 getTargetTriple()); 420 if (!TT.isArch32Bit() && !TT.isArch64Bit()) 421 return MadeChange; // Unknown arch. type. 422 423 // Process nested loops first. 424 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) { 425 MadeChange |= convertToCTRLoop(*I); 426 } 427 428 // If a nested loop has been converted, then we can't convert this loop. 429 if (MadeChange) 430 return MadeChange; 431 432 #ifndef NDEBUG 433 // Stop trying after reaching the limit (if any). 434 int Limit = CTRLoopLimit; 435 if (Limit >= 0) { 436 if (Counter >= CTRLoopLimit) 437 return false; 438 Counter++; 439 } 440 #endif 441 442 // We don't want to spill/restore the counter register, and so we don't 443 // want to use the counter register if the loop contains calls. 444 for (Loop::block_iterator I = L->block_begin(), IE = L->block_end(); 445 I != IE; ++I) 446 if (mightUseCTR(TT, *I)) 447 return MadeChange; 448 449 SmallVector<BasicBlock*, 4> ExitingBlocks; 450 L->getExitingBlocks(ExitingBlocks); 451 452 BasicBlock *CountedExitBlock = nullptr; 453 const SCEV *ExitCount = nullptr; 454 BranchInst *CountedExitBranch = nullptr; 455 for (SmallVectorImpl<BasicBlock *>::iterator I = ExitingBlocks.begin(), 456 IE = ExitingBlocks.end(); I != IE; ++I) { 457 const SCEV *EC = SE->getExitCount(L, *I); 458 DEBUG(dbgs() << "Exit Count for " << *L << " from block " << 459 (*I)->getName() << ": " << *EC << "\n"); 460 if (isa<SCEVCouldNotCompute>(EC)) 461 continue; 462 if (const SCEVConstant *ConstEC = dyn_cast<SCEVConstant>(EC)) { 463 if (ConstEC->getValue()->isZero()) 464 continue; 465 } else if (!SE->isLoopInvariant(EC, L)) 466 continue; 467 468 if (SE->getTypeSizeInBits(EC->getType()) > (TT.isArch64Bit() ? 64 : 32)) 469 continue; 470 471 // We now have a loop-invariant count of loop iterations (which is not the 472 // constant zero) for which we know that this loop will not exit via this 473 // exisiting block. 474 475 // We need to make sure that this block will run on every loop iteration. 476 // For this to be true, we must dominate all blocks with backedges. Such 477 // blocks are in-loop predecessors to the header block. 478 bool NotAlways = false; 479 for (pred_iterator PI = pred_begin(L->getHeader()), 480 PIE = pred_end(L->getHeader()); PI != PIE; ++PI) { 481 if (!L->contains(*PI)) 482 continue; 483 484 if (!DT->dominates(*I, *PI)) { 485 NotAlways = true; 486 break; 487 } 488 } 489 490 if (NotAlways) 491 continue; 492 493 // Make sure this blocks ends with a conditional branch. 494 Instruction *TI = (*I)->getTerminator(); 495 if (!TI) 496 continue; 497 498 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 499 if (!BI->isConditional()) 500 continue; 501 502 CountedExitBranch = BI; 503 } else 504 continue; 505 506 // Note that this block may not be the loop latch block, even if the loop 507 // has a latch block. 508 CountedExitBlock = *I; 509 ExitCount = EC; 510 break; 511 } 512 513 if (!CountedExitBlock) 514 return MadeChange; 515 516 BasicBlock *Preheader = L->getLoopPreheader(); 517 518 // If we don't have a preheader, then insert one. If we already have a 519 // preheader, then we can use it (except if the preheader contains a use of 520 // the CTR register because some such uses might be reordered by the 521 // selection DAG after the mtctr instruction). 522 if (!Preheader || mightUseCTR(TT, Preheader)) 523 Preheader = InsertPreheaderForLoop(L, this); 524 if (!Preheader) 525 return MadeChange; 526 527 DEBUG(dbgs() << "Preheader for exit count: " << Preheader->getName() << "\n"); 528 529 // Insert the count into the preheader and replace the condition used by the 530 // selected branch. 531 MadeChange = true; 532 533 SCEVExpander SCEVE(*SE, "loopcnt"); 534 LLVMContext &C = SE->getContext(); 535 Type *CountType = TT.isArch64Bit() ? Type::getInt64Ty(C) : 536 Type::getInt32Ty(C); 537 if (!ExitCount->getType()->isPointerTy() && 538 ExitCount->getType() != CountType) 539 ExitCount = SE->getZeroExtendExpr(ExitCount, CountType); 540 ExitCount = SE->getAddExpr(ExitCount, 541 SE->getConstant(CountType, 1)); 542 Value *ECValue = SCEVE.expandCodeFor(ExitCount, CountType, 543 Preheader->getTerminator()); 544 545 IRBuilder<> CountBuilder(Preheader->getTerminator()); 546 Module *M = Preheader->getParent()->getParent(); 547 Value *MTCTRFunc = Intrinsic::getDeclaration(M, Intrinsic::ppc_mtctr, 548 CountType); 549 CountBuilder.CreateCall(MTCTRFunc, ECValue); 550 551 IRBuilder<> CondBuilder(CountedExitBranch); 552 Value *DecFunc = 553 Intrinsic::getDeclaration(M, Intrinsic::ppc_is_decremented_ctr_nonzero); 554 Value *NewCond = CondBuilder.CreateCall(DecFunc); 555 Value *OldCond = CountedExitBranch->getCondition(); 556 CountedExitBranch->setCondition(NewCond); 557 558 // The false branch must exit the loop. 559 if (!L->contains(CountedExitBranch->getSuccessor(0))) 560 CountedExitBranch->swapSuccessors(); 561 562 // The old condition may be dead now, and may have even created a dead PHI 563 // (the original induction variable). 564 RecursivelyDeleteTriviallyDeadInstructions(OldCond); 565 DeleteDeadPHIs(CountedExitBlock); 566 567 ++NumCTRLoops; 568 return MadeChange; 569 } 570 571 #ifndef NDEBUG 572 static bool clobbersCTR(const MachineInstr *MI) { 573 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 574 const MachineOperand &MO = MI->getOperand(i); 575 if (MO.isReg()) { 576 if (MO.isDef() && (MO.getReg() == PPC::CTR || MO.getReg() == PPC::CTR8)) 577 return true; 578 } else if (MO.isRegMask()) { 579 if (MO.clobbersPhysReg(PPC::CTR) || MO.clobbersPhysReg(PPC::CTR8)) 580 return true; 581 } 582 } 583 584 return false; 585 } 586 587 static bool verifyCTRBranch(MachineBasicBlock *MBB, 588 MachineBasicBlock::iterator I) { 589 MachineBasicBlock::iterator BI = I; 590 SmallSet<MachineBasicBlock *, 16> Visited; 591 SmallVector<MachineBasicBlock *, 8> Preds; 592 bool CheckPreds; 593 594 if (I == MBB->begin()) { 595 Visited.insert(MBB); 596 goto queue_preds; 597 } else 598 --I; 599 600 check_block: 601 Visited.insert(MBB); 602 if (I == MBB->end()) 603 goto queue_preds; 604 605 CheckPreds = true; 606 for (MachineBasicBlock::iterator IE = MBB->begin();; --I) { 607 unsigned Opc = I->getOpcode(); 608 if (Opc == PPC::MTCTRloop || Opc == PPC::MTCTR8loop) { 609 CheckPreds = false; 610 break; 611 } 612 613 if (I != BI && clobbersCTR(I)) { 614 DEBUG(dbgs() << "BB#" << MBB->getNumber() << " (" << 615 MBB->getFullName() << ") instruction " << *I << 616 " clobbers CTR, invalidating " << "BB#" << 617 BI->getParent()->getNumber() << " (" << 618 BI->getParent()->getFullName() << ") instruction " << 619 *BI << "\n"); 620 return false; 621 } 622 623 if (I == IE) 624 break; 625 } 626 627 if (!CheckPreds && Preds.empty()) 628 return true; 629 630 if (CheckPreds) { 631 queue_preds: 632 if (MachineFunction::iterator(MBB) == MBB->getParent()->begin()) { 633 DEBUG(dbgs() << "Unable to find a MTCTR instruction for BB#" << 634 BI->getParent()->getNumber() << " (" << 635 BI->getParent()->getFullName() << ") instruction " << 636 *BI << "\n"); 637 return false; 638 } 639 640 for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(), 641 PIE = MBB->pred_end(); PI != PIE; ++PI) 642 Preds.push_back(*PI); 643 } 644 645 do { 646 MBB = Preds.pop_back_val(); 647 if (!Visited.count(MBB)) { 648 I = MBB->getLastNonDebugInstr(); 649 goto check_block; 650 } 651 } while (!Preds.empty()); 652 653 return true; 654 } 655 656 bool PPCCTRLoopsVerify::runOnMachineFunction(MachineFunction &MF) { 657 MDT = &getAnalysis<MachineDominatorTree>(); 658 659 // Verify that all bdnz/bdz instructions are dominated by a loop mtctr before 660 // any other instructions that might clobber the ctr register. 661 for (MachineFunction::iterator I = MF.begin(), IE = MF.end(); 662 I != IE; ++I) { 663 MachineBasicBlock *MBB = I; 664 if (!MDT->isReachableFromEntry(MBB)) 665 continue; 666 667 for (MachineBasicBlock::iterator MII = MBB->getFirstTerminator(), 668 MIIE = MBB->end(); MII != MIIE; ++MII) { 669 unsigned Opc = MII->getOpcode(); 670 if (Opc == PPC::BDNZ8 || Opc == PPC::BDNZ || 671 Opc == PPC::BDZ8 || Opc == PPC::BDZ) 672 if (!verifyCTRBranch(MBB, MII)) 673 llvm_unreachable("Invalid PPC CTR loop!"); 674 } 675 } 676 677 return false; 678 } 679 #endif // NDEBUG 680 681