1239310Sdim//===-- PPCCTRLoops.cpp - Identify and generate CTR loops -----------------===// 2239310Sdim// 3239310Sdim// The LLVM Compiler Infrastructure 4239310Sdim// 5239310Sdim// This file is distributed under the University of Illinois Open Source 6239310Sdim// License. See LICENSE.TXT for details. 7239310Sdim// 8239310Sdim//===----------------------------------------------------------------------===// 9239310Sdim// 10239310Sdim// This pass identifies loops where we can generate the PPC branch instructions 11239310Sdim// that decrement and test the count register (CTR) (bdnz and friends). 12239310Sdim// 13239310Sdim// The pattern that defines the induction variable can changed depending on 14239310Sdim// prior optimizations. For example, the IndVarSimplify phase run by 'opt' 15239310Sdim// normalizes induction variables, and the Loop Strength Reduction pass 16239310Sdim// run by 'llc' may also make changes to the induction variable. 17239310Sdim// 18239310Sdim// Criteria for CTR loops: 19239310Sdim// - Countable loops (w/ ind. var for a trip count) 20239310Sdim// - Try inner-most loops first 21239310Sdim// - No nested CTR loops. 22239310Sdim// - No function calls in loops. 23239310Sdim// 24239310Sdim//===----------------------------------------------------------------------===// 25239310Sdim 26239310Sdim#define DEBUG_TYPE "ctrloops" 27263508Sdim 28263508Sdim#include "llvm/Transforms/Scalar.h" 29263508Sdim#include "llvm/ADT/Statistic.h" 30263508Sdim#include "llvm/ADT/STLExtras.h" 31263508Sdim#include "llvm/Analysis/Dominators.h" 32263508Sdim#include "llvm/Analysis/LoopInfo.h" 33263508Sdim#include "llvm/Analysis/ScalarEvolutionExpander.h" 34263508Sdim#include "llvm/IR/Constants.h" 35263508Sdim#include "llvm/IR/DerivedTypes.h" 36263508Sdim#include "llvm/IR/InlineAsm.h" 37263508Sdim#include "llvm/IR/Instructions.h" 38263508Sdim#include "llvm/IR/IntrinsicInst.h" 39263508Sdim#include "llvm/IR/Module.h" 40263508Sdim#include "llvm/PassSupport.h" 41263508Sdim#include "llvm/Support/CommandLine.h" 42263508Sdim#include "llvm/Support/Debug.h" 43263508Sdim#include "llvm/Support/ValueHandle.h" 44263508Sdim#include "llvm/Support/raw_ostream.h" 45263508Sdim#include "llvm/Transforms/Utils/BasicBlockUtils.h" 46263508Sdim#include "llvm/Transforms/Utils/Local.h" 47263508Sdim#include "llvm/Transforms/Utils/LoopUtils.h" 48263508Sdim#include "llvm/Target/TargetLibraryInfo.h" 49263508Sdim#include "PPCTargetMachine.h" 50239310Sdim#include "PPC.h" 51263508Sdim 52263508Sdim#ifndef NDEBUG 53239310Sdim#include "llvm/CodeGen/MachineDominators.h" 54239310Sdim#include "llvm/CodeGen/MachineFunction.h" 55239310Sdim#include "llvm/CodeGen/MachineFunctionPass.h" 56239310Sdim#include "llvm/CodeGen/MachineRegisterInfo.h" 57263508Sdim#endif 58263508Sdim 59239310Sdim#include <algorithm> 60263508Sdim#include <vector> 61239310Sdim 62239310Sdimusing namespace llvm; 63239310Sdim 64263508Sdim#ifndef NDEBUG 65263508Sdimstatic cl::opt<int> CTRLoopLimit("ppc-max-ctrloop", cl::Hidden, cl::init(-1)); 66263508Sdim#endif 67263508Sdim 68239310SdimSTATISTIC(NumCTRLoops, "Number of loops converted to CTR loops"); 69239310Sdim 70249423Sdimnamespace llvm { 71249423Sdim void initializePPCCTRLoopsPass(PassRegistry&); 72263508Sdim#ifndef NDEBUG 73263508Sdim void initializePPCCTRLoopsVerifyPass(PassRegistry&); 74263508Sdim#endif 75249423Sdim} 76249423Sdim 77239310Sdimnamespace { 78263508Sdim struct PPCCTRLoops : public FunctionPass { 79239310Sdim 80263508Sdim#ifndef NDEBUG 81263508Sdim static int Counter; 82263508Sdim#endif 83263508Sdim 84239310Sdim public: 85263508Sdim static char ID; 86239310Sdim 87263508Sdim PPCCTRLoops() : FunctionPass(ID), TM(0) { 88249423Sdim initializePPCCTRLoopsPass(*PassRegistry::getPassRegistry()); 89249423Sdim } 90263508Sdim PPCCTRLoops(PPCTargetMachine &TM) : FunctionPass(ID), TM(&TM) { 91263508Sdim initializePPCCTRLoopsPass(*PassRegistry::getPassRegistry()); 92263508Sdim } 93239310Sdim 94263508Sdim virtual bool runOnFunction(Function &F); 95239310Sdim 96239310Sdim virtual void getAnalysisUsage(AnalysisUsage &AU) const { 97263508Sdim AU.addRequired<LoopInfo>(); 98263508Sdim AU.addPreserved<LoopInfo>(); 99263508Sdim AU.addRequired<DominatorTree>(); 100263508Sdim AU.addPreserved<DominatorTree>(); 101263508Sdim AU.addRequired<ScalarEvolution>(); 102239310Sdim } 103239310Sdim 104239310Sdim private: 105263508Sdim bool mightUseCTR(const Triple &TT, BasicBlock *BB); 106263508Sdim bool convertToCTRLoop(Loop *L); 107239310Sdim 108263508Sdim private: 109263508Sdim PPCTargetMachine *TM; 110263508Sdim LoopInfo *LI; 111263508Sdim ScalarEvolution *SE; 112263508Sdim DataLayout *TD; 113263508Sdim DominatorTree *DT; 114263508Sdim const TargetLibraryInfo *LibInfo; 115239310Sdim }; 116239310Sdim 117239310Sdim char PPCCTRLoops::ID = 0; 118263508Sdim#ifndef NDEBUG 119263508Sdim int PPCCTRLoops::Counter = 0; 120263508Sdim#endif 121239310Sdim 122263508Sdim#ifndef NDEBUG 123263508Sdim struct PPCCTRLoopsVerify : public MachineFunctionPass { 124239310Sdim public: 125263508Sdim static char ID; 126239310Sdim 127263508Sdim PPCCTRLoopsVerify() : MachineFunctionPass(ID) { 128263508Sdim initializePPCCTRLoopsVerifyPass(*PassRegistry::getPassRegistry()); 129263508Sdim } 130239310Sdim 131263508Sdim virtual void getAnalysisUsage(AnalysisUsage &AU) const { 132263508Sdim AU.addRequired<MachineDominatorTree>(); 133263508Sdim MachineFunctionPass::getAnalysisUsage(AU); 134239310Sdim } 135239310Sdim 136263508Sdim virtual bool runOnMachineFunction(MachineFunction &MF); 137263508Sdim 138263508Sdim private: 139263508Sdim MachineDominatorTree *MDT; 140239310Sdim }; 141263508Sdim 142263508Sdim char PPCCTRLoopsVerify::ID = 0; 143263508Sdim#endif // NDEBUG 144239310Sdim} // end anonymous namespace 145239310Sdim 146249423SdimINITIALIZE_PASS_BEGIN(PPCCTRLoops, "ppc-ctr-loops", "PowerPC CTR Loops", 147249423Sdim false, false) 148263508SdimINITIALIZE_PASS_DEPENDENCY(DominatorTree) 149263508SdimINITIALIZE_PASS_DEPENDENCY(LoopInfo) 150263508SdimINITIALIZE_PASS_DEPENDENCY(ScalarEvolution) 151249423SdimINITIALIZE_PASS_END(PPCCTRLoops, "ppc-ctr-loops", "PowerPC CTR Loops", 152249423Sdim false, false) 153239310Sdim 154263508SdimFunctionPass *llvm::createPPCCTRLoops(PPCTargetMachine &TM) { 155263508Sdim return new PPCCTRLoops(TM); 156239310Sdim} 157239310Sdim 158263508Sdim#ifndef NDEBUG 159263508SdimINITIALIZE_PASS_BEGIN(PPCCTRLoopsVerify, "ppc-ctr-loops-verify", 160263508Sdim "PowerPC CTR Loops Verify", false, false) 161263508SdimINITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) 162263508SdimINITIALIZE_PASS_END(PPCCTRLoopsVerify, "ppc-ctr-loops-verify", 163263508Sdim "PowerPC CTR Loops Verify", false, false) 164239310Sdim 165263508SdimFunctionPass *llvm::createPPCCTRLoopsVerify() { 166263508Sdim return new PPCCTRLoopsVerify(); 167239310Sdim} 168263508Sdim#endif // NDEBUG 169239310Sdim 170263508Sdimbool PPCCTRLoops::runOnFunction(Function &F) { 171263508Sdim LI = &getAnalysis<LoopInfo>(); 172263508Sdim SE = &getAnalysis<ScalarEvolution>(); 173263508Sdim DT = &getAnalysis<DominatorTree>(); 174263508Sdim TD = getAnalysisIfAvailable<DataLayout>(); 175263508Sdim LibInfo = getAnalysisIfAvailable<TargetLibraryInfo>(); 176239310Sdim 177263508Sdim bool MadeChange = false; 178239310Sdim 179263508Sdim for (LoopInfo::iterator I = LI->begin(), E = LI->end(); 180239310Sdim I != E; ++I) { 181263508Sdim Loop *L = *I; 182263508Sdim if (!L->getParentLoop()) 183263508Sdim MadeChange |= convertToCTRLoop(L); 184239310Sdim } 185239310Sdim 186263508Sdim return MadeChange; 187239310Sdim} 188239310Sdim 189266715Sdimstatic bool isLargeIntegerTy(bool Is32Bit, Type *Ty) { 190266715Sdim if (IntegerType *ITy = dyn_cast<IntegerType>(Ty)) 191266715Sdim return ITy->getBitWidth() > (Is32Bit ? 32 : 64); 192266715Sdim 193266715Sdim return false; 194266715Sdim} 195266715Sdim 196263508Sdimbool PPCCTRLoops::mightUseCTR(const Triple &TT, BasicBlock *BB) { 197263508Sdim for (BasicBlock::iterator J = BB->begin(), JE = BB->end(); 198263508Sdim J != JE; ++J) { 199263508Sdim if (CallInst *CI = dyn_cast<CallInst>(J)) { 200263508Sdim if (InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue())) { 201263508Sdim // Inline ASM is okay, unless it clobbers the ctr register. 202263508Sdim InlineAsm::ConstraintInfoVector CIV = IA->ParseConstraints(); 203263508Sdim for (unsigned i = 0, ie = CIV.size(); i < ie; ++i) { 204263508Sdim InlineAsm::ConstraintInfo &C = CIV[i]; 205263508Sdim if (C.Type != InlineAsm::isInput) 206263508Sdim for (unsigned j = 0, je = C.Codes.size(); j < je; ++j) 207263508Sdim if (StringRef(C.Codes[j]).equals_lower("{ctr}")) 208263508Sdim return true; 209263508Sdim } 210239310Sdim 211263508Sdim continue; 212239310Sdim } 213239310Sdim 214263508Sdim if (!TM) 215263508Sdim return true; 216263508Sdim const TargetLowering *TLI = TM->getTargetLowering(); 217239310Sdim 218263508Sdim if (Function *F = CI->getCalledFunction()) { 219263508Sdim // Most intrinsics don't become function calls, but some might. 220263508Sdim // sin, cos, exp and log are always calls. 221263508Sdim unsigned Opcode; 222263508Sdim if (F->getIntrinsicID() != Intrinsic::not_intrinsic) { 223263508Sdim switch (F->getIntrinsicID()) { 224263508Sdim default: continue; 225239310Sdim 226263508Sdim// VisualStudio defines setjmp as _setjmp 227263508Sdim#if defined(_MSC_VER) && defined(setjmp) && \ 228263508Sdim !defined(setjmp_undefined_for_msvc) 229263508Sdim# pragma push_macro("setjmp") 230263508Sdim# undef setjmp 231263508Sdim# define setjmp_undefined_for_msvc 232263508Sdim#endif 233239310Sdim 234263508Sdim case Intrinsic::setjmp: 235239310Sdim 236263508Sdim#if defined(_MSC_VER) && defined(setjmp_undefined_for_msvc) 237263508Sdim // let's return it to _setjmp state 238263508Sdim# pragma pop_macro("setjmp") 239263508Sdim# undef setjmp_undefined_for_msvc 240263508Sdim#endif 241239310Sdim 242263508Sdim case Intrinsic::longjmp: 243239310Sdim 244263508Sdim // Exclude eh_sjlj_setjmp; we don't need to exclude eh_sjlj_longjmp 245263508Sdim // because, although it does clobber the counter register, the 246263508Sdim // control can't then return to inside the loop unless there is also 247263508Sdim // an eh_sjlj_setjmp. 248263508Sdim case Intrinsic::eh_sjlj_setjmp: 249239310Sdim 250263508Sdim case Intrinsic::memcpy: 251263508Sdim case Intrinsic::memmove: 252263508Sdim case Intrinsic::memset: 253263508Sdim case Intrinsic::powi: 254263508Sdim case Intrinsic::log: 255263508Sdim case Intrinsic::log2: 256263508Sdim case Intrinsic::log10: 257263508Sdim case Intrinsic::exp: 258263508Sdim case Intrinsic::exp2: 259263508Sdim case Intrinsic::pow: 260263508Sdim case Intrinsic::sin: 261263508Sdim case Intrinsic::cos: 262263508Sdim return true; 263263508Sdim case Intrinsic::copysign: 264263508Sdim if (CI->getArgOperand(0)->getType()->getScalarType()-> 265263508Sdim isPPC_FP128Ty()) 266263508Sdim return true; 267263508Sdim else 268263508Sdim continue; // ISD::FCOPYSIGN is never a library call. 269263508Sdim case Intrinsic::sqrt: Opcode = ISD::FSQRT; break; 270263508Sdim case Intrinsic::floor: Opcode = ISD::FFLOOR; break; 271263508Sdim case Intrinsic::ceil: Opcode = ISD::FCEIL; break; 272263508Sdim case Intrinsic::trunc: Opcode = ISD::FTRUNC; break; 273263508Sdim case Intrinsic::rint: Opcode = ISD::FRINT; break; 274263508Sdim case Intrinsic::nearbyint: Opcode = ISD::FNEARBYINT; break; 275263508Sdim case Intrinsic::round: Opcode = ISD::FROUND; break; 276263508Sdim } 277263508Sdim } 278239310Sdim 279263508Sdim // PowerPC does not use [US]DIVREM or other library calls for 280263508Sdim // operations on regular types which are not otherwise library calls 281263508Sdim // (i.e. soft float or atomics). If adapting for targets that do, 282263508Sdim // additional care is required here. 283239310Sdim 284263508Sdim LibFunc::Func Func; 285263508Sdim if (!F->hasLocalLinkage() && F->hasName() && LibInfo && 286263508Sdim LibInfo->getLibFunc(F->getName(), Func) && 287263508Sdim LibInfo->hasOptimizedCodeGen(Func)) { 288263508Sdim // Non-read-only functions are never treated as intrinsics. 289263508Sdim if (!CI->onlyReadsMemory()) 290263508Sdim return true; 291239310Sdim 292263508Sdim // Conversion happens only for FP calls. 293263508Sdim if (!CI->getArgOperand(0)->getType()->isFloatingPointTy()) 294263508Sdim return true; 295249423Sdim 296263508Sdim switch (Func) { 297263508Sdim default: return true; 298263508Sdim case LibFunc::copysign: 299263508Sdim case LibFunc::copysignf: 300263508Sdim continue; // ISD::FCOPYSIGN is never a library call. 301263508Sdim case LibFunc::copysignl: 302263508Sdim return true; 303263508Sdim case LibFunc::fabs: 304263508Sdim case LibFunc::fabsf: 305263508Sdim case LibFunc::fabsl: 306263508Sdim continue; // ISD::FABS is never a library call. 307263508Sdim case LibFunc::sqrt: 308263508Sdim case LibFunc::sqrtf: 309263508Sdim case LibFunc::sqrtl: 310263508Sdim Opcode = ISD::FSQRT; break; 311263508Sdim case LibFunc::floor: 312263508Sdim case LibFunc::floorf: 313263508Sdim case LibFunc::floorl: 314263508Sdim Opcode = ISD::FFLOOR; break; 315263508Sdim case LibFunc::nearbyint: 316263508Sdim case LibFunc::nearbyintf: 317263508Sdim case LibFunc::nearbyintl: 318263508Sdim Opcode = ISD::FNEARBYINT; break; 319263508Sdim case LibFunc::ceil: 320263508Sdim case LibFunc::ceilf: 321263508Sdim case LibFunc::ceill: 322263508Sdim Opcode = ISD::FCEIL; break; 323263508Sdim case LibFunc::rint: 324263508Sdim case LibFunc::rintf: 325263508Sdim case LibFunc::rintl: 326263508Sdim Opcode = ISD::FRINT; break; 327263508Sdim case LibFunc::round: 328263508Sdim case LibFunc::roundf: 329263508Sdim case LibFunc::roundl: 330263508Sdim Opcode = ISD::FROUND; break; 331263508Sdim case LibFunc::trunc: 332263508Sdim case LibFunc::truncf: 333263508Sdim case LibFunc::truncl: 334263508Sdim Opcode = ISD::FTRUNC; break; 335239310Sdim } 336239310Sdim 337263508Sdim MVT VTy = 338263508Sdim TLI->getSimpleValueType(CI->getArgOperand(0)->getType(), true); 339263508Sdim if (VTy == MVT::Other) 340263508Sdim return true; 341263508Sdim 342263508Sdim if (TLI->isOperationLegalOrCustom(Opcode, VTy)) 343263508Sdim continue; 344263508Sdim else if (VTy.isVector() && 345263508Sdim TLI->isOperationLegalOrCustom(Opcode, VTy.getScalarType())) 346263508Sdim continue; 347249423Sdim 348263508Sdim return true; 349239310Sdim } 350239310Sdim } 351239310Sdim 352239310Sdim return true; 353263508Sdim } else if (isa<BinaryOperator>(J) && 354263508Sdim J->getType()->getScalarType()->isPPC_FP128Ty()) { 355263508Sdim // Most operations on ppc_f128 values become calls. 356263508Sdim return true; 357263508Sdim } else if (isa<UIToFPInst>(J) || isa<SIToFPInst>(J) || 358263508Sdim isa<FPToUIInst>(J) || isa<FPToSIInst>(J)) { 359263508Sdim CastInst *CI = cast<CastInst>(J); 360263508Sdim if (CI->getSrcTy()->getScalarType()->isPPC_FP128Ty() || 361263508Sdim CI->getDestTy()->getScalarType()->isPPC_FP128Ty() || 362266715Sdim isLargeIntegerTy(TT.isArch32Bit(), CI->getSrcTy()->getScalarType()) || 363266715Sdim isLargeIntegerTy(TT.isArch32Bit(), CI->getDestTy()->getScalarType())) 364263508Sdim return true; 365266715Sdim } else if (isLargeIntegerTy(TT.isArch32Bit(), 366266715Sdim J->getType()->getScalarType()) && 367263508Sdim (J->getOpcode() == Instruction::UDiv || 368263508Sdim J->getOpcode() == Instruction::SDiv || 369263508Sdim J->getOpcode() == Instruction::URem || 370263508Sdim J->getOpcode() == Instruction::SRem)) { 371263508Sdim return true; 372263508Sdim } else if (isa<IndirectBrInst>(J) || isa<InvokeInst>(J)) { 373263508Sdim // On PowerPC, indirect jumps use the counter register. 374263508Sdim return true; 375263508Sdim } else if (SwitchInst *SI = dyn_cast<SwitchInst>(J)) { 376263508Sdim if (!TM) 377263508Sdim return true; 378263508Sdim const TargetLowering *TLI = TM->getTargetLowering(); 379239310Sdim 380263508Sdim if (TLI->supportJumpTables() && 381263508Sdim SI->getNumCases()+1 >= (unsigned) TLI->getMinimumJumpTableEntries()) 382239310Sdim return true; 383239310Sdim } 384239310Sdim } 385263508Sdim 386239310Sdim return false; 387239310Sdim} 388239310Sdim 389263508Sdimbool PPCCTRLoops::convertToCTRLoop(Loop *L) { 390263508Sdim bool MadeChange = false; 391239310Sdim 392263508Sdim Triple TT = Triple(L->getHeader()->getParent()->getParent()-> 393263508Sdim getTargetTriple()); 394263508Sdim if (!TT.isArch32Bit() && !TT.isArch64Bit()) 395263508Sdim return MadeChange; // Unknown arch. type. 396239310Sdim 397263508Sdim // Process nested loops first. 398263508Sdim for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) { 399263508Sdim MadeChange |= convertToCTRLoop(*I); 400263508Sdim } 401239310Sdim 402263508Sdim // If a nested loop has been converted, then we can't convert this loop. 403263508Sdim if (MadeChange) 404263508Sdim return MadeChange; 405239310Sdim 406263508Sdim#ifndef NDEBUG 407263508Sdim // Stop trying after reaching the limit (if any). 408263508Sdim int Limit = CTRLoopLimit; 409263508Sdim if (Limit >= 0) { 410263508Sdim if (Counter >= CTRLoopLimit) 411263508Sdim return false; 412263508Sdim Counter++; 413239310Sdim } 414263508Sdim#endif 415239310Sdim 416263508Sdim // We don't want to spill/restore the counter register, and so we don't 417263508Sdim // want to use the counter register if the loop contains calls. 418263508Sdim for (Loop::block_iterator I = L->block_begin(), IE = L->block_end(); 419263508Sdim I != IE; ++I) 420263508Sdim if (mightUseCTR(TT, *I)) 421263508Sdim return MadeChange; 422239310Sdim 423263508Sdim SmallVector<BasicBlock*, 4> ExitingBlocks; 424263508Sdim L->getExitingBlocks(ExitingBlocks); 425239310Sdim 426263508Sdim BasicBlock *CountedExitBlock = 0; 427263508Sdim const SCEV *ExitCount = 0; 428263508Sdim BranchInst *CountedExitBranch = 0; 429263508Sdim for (SmallVectorImpl<BasicBlock *>::iterator I = ExitingBlocks.begin(), 430263508Sdim IE = ExitingBlocks.end(); I != IE; ++I) { 431263508Sdim const SCEV *EC = SE->getExitCount(L, *I); 432263508Sdim DEBUG(dbgs() << "Exit Count for " << *L << " from block " << 433263508Sdim (*I)->getName() << ": " << *EC << "\n"); 434263508Sdim if (isa<SCEVCouldNotCompute>(EC)) 435263508Sdim continue; 436263508Sdim if (const SCEVConstant *ConstEC = dyn_cast<SCEVConstant>(EC)) { 437263508Sdim if (ConstEC->getValue()->isZero()) 438263508Sdim continue; 439263508Sdim } else if (!SE->isLoopInvariant(EC, L)) 440263508Sdim continue; 441239310Sdim 442263508Sdim if (SE->getTypeSizeInBits(EC->getType()) > (TT.isArch64Bit() ? 64 : 32)) 443263508Sdim continue; 444263508Sdim 445263508Sdim // We now have a loop-invariant count of loop iterations (which is not the 446263508Sdim // constant zero) for which we know that this loop will not exit via this 447263508Sdim // exisiting block. 448263508Sdim 449263508Sdim // We need to make sure that this block will run on every loop iteration. 450263508Sdim // For this to be true, we must dominate all blocks with backedges. Such 451263508Sdim // blocks are in-loop predecessors to the header block. 452263508Sdim bool NotAlways = false; 453263508Sdim for (pred_iterator PI = pred_begin(L->getHeader()), 454263508Sdim PIE = pred_end(L->getHeader()); PI != PIE; ++PI) { 455263508Sdim if (!L->contains(*PI)) 456239310Sdim continue; 457263508Sdim 458263508Sdim if (!DT->dominates(*I, *PI)) { 459263508Sdim NotAlways = true; 460263508Sdim break; 461239310Sdim } 462239310Sdim } 463239310Sdim 464263508Sdim if (NotAlways) 465263508Sdim continue; 466239310Sdim 467263508Sdim // Make sure this blocks ends with a conditional branch. 468263508Sdim Instruction *TI = (*I)->getTerminator(); 469263508Sdim if (!TI) 470263508Sdim continue; 471239310Sdim 472263508Sdim if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 473263508Sdim if (!BI->isConditional()) 474263508Sdim continue; 475249423Sdim 476263508Sdim CountedExitBranch = BI; 477263508Sdim } else 478263508Sdim continue; 479249423Sdim 480263508Sdim // Note that this block may not be the loop latch block, even if the loop 481263508Sdim // has a latch block. 482263508Sdim CountedExitBlock = *I; 483263508Sdim ExitCount = EC; 484263508Sdim break; 485249423Sdim } 486249423Sdim 487263508Sdim if (!CountedExitBlock) 488263508Sdim return MadeChange; 489239310Sdim 490263508Sdim BasicBlock *Preheader = L->getLoopPreheader(); 491239310Sdim 492263508Sdim // If we don't have a preheader, then insert one. If we already have a 493263508Sdim // preheader, then we can use it (except if the preheader contains a use of 494263508Sdim // the CTR register because some such uses might be reordered by the 495263508Sdim // selection DAG after the mtctr instruction). 496263508Sdim if (!Preheader || mightUseCTR(TT, Preheader)) 497263508Sdim Preheader = InsertPreheaderForLoop(L, this); 498263508Sdim if (!Preheader) 499263508Sdim return MadeChange; 500239310Sdim 501263508Sdim DEBUG(dbgs() << "Preheader for exit count: " << Preheader->getName() << "\n"); 502263508Sdim 503263508Sdim // Insert the count into the preheader and replace the condition used by the 504263508Sdim // selected branch. 505263508Sdim MadeChange = true; 506263508Sdim 507263508Sdim SCEVExpander SCEVE(*SE, "loopcnt"); 508263508Sdim LLVMContext &C = SE->getContext(); 509263508Sdim Type *CountType = TT.isArch64Bit() ? Type::getInt64Ty(C) : 510263508Sdim Type::getInt32Ty(C); 511263508Sdim if (!ExitCount->getType()->isPointerTy() && 512263508Sdim ExitCount->getType() != CountType) 513263508Sdim ExitCount = SE->getZeroExtendExpr(ExitCount, CountType); 514263508Sdim ExitCount = SE->getAddExpr(ExitCount, 515263508Sdim SE->getConstant(CountType, 1)); 516263508Sdim Value *ECValue = SCEVE.expandCodeFor(ExitCount, CountType, 517263508Sdim Preheader->getTerminator()); 518263508Sdim 519263508Sdim IRBuilder<> CountBuilder(Preheader->getTerminator()); 520263508Sdim Module *M = Preheader->getParent()->getParent(); 521263508Sdim Value *MTCTRFunc = Intrinsic::getDeclaration(M, Intrinsic::ppc_mtctr, 522263508Sdim CountType); 523263508Sdim CountBuilder.CreateCall(MTCTRFunc, ECValue); 524263508Sdim 525263508Sdim IRBuilder<> CondBuilder(CountedExitBranch); 526263508Sdim Value *DecFunc = 527263508Sdim Intrinsic::getDeclaration(M, Intrinsic::ppc_is_decremented_ctr_nonzero); 528263508Sdim Value *NewCond = CondBuilder.CreateCall(DecFunc); 529263508Sdim Value *OldCond = CountedExitBranch->getCondition(); 530263508Sdim CountedExitBranch->setCondition(NewCond); 531263508Sdim 532263508Sdim // The false branch must exit the loop. 533263508Sdim if (!L->contains(CountedExitBranch->getSuccessor(0))) 534263508Sdim CountedExitBranch->swapSuccessors(); 535263508Sdim 536263508Sdim // The old condition may be dead now, and may have even created a dead PHI 537263508Sdim // (the original induction variable). 538263508Sdim RecursivelyDeleteTriviallyDeadInstructions(OldCond); 539263508Sdim DeleteDeadPHIs(CountedExitBlock); 540263508Sdim 541263508Sdim ++NumCTRLoops; 542263508Sdim return MadeChange; 543263508Sdim} 544263508Sdim 545263508Sdim#ifndef NDEBUG 546263508Sdimstatic bool clobbersCTR(const MachineInstr *MI) { 547263508Sdim for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 548263508Sdim const MachineOperand &MO = MI->getOperand(i); 549263508Sdim if (MO.isReg()) { 550263508Sdim if (MO.isDef() && (MO.getReg() == PPC::CTR || MO.getReg() == PPC::CTR8)) 551263508Sdim return true; 552263508Sdim } else if (MO.isRegMask()) { 553263508Sdim if (MO.clobbersPhysReg(PPC::CTR) || MO.clobbersPhysReg(PPC::CTR8)) 554263508Sdim return true; 555239310Sdim } 556239310Sdim } 557239310Sdim 558263508Sdim return false; 559263508Sdim} 560239310Sdim 561263508Sdimstatic bool verifyCTRBranch(MachineBasicBlock *MBB, 562263508Sdim MachineBasicBlock::iterator I) { 563263508Sdim MachineBasicBlock::iterator BI = I; 564263508Sdim SmallSet<MachineBasicBlock *, 16> Visited; 565263508Sdim SmallVector<MachineBasicBlock *, 8> Preds; 566263508Sdim bool CheckPreds; 567239310Sdim 568263508Sdim if (I == MBB->begin()) { 569263508Sdim Visited.insert(MBB); 570263508Sdim goto queue_preds; 571263508Sdim } else 572263508Sdim --I; 573239310Sdim 574263508Sdimcheck_block: 575263508Sdim Visited.insert(MBB); 576263508Sdim if (I == MBB->end()) 577263508Sdim goto queue_preds; 578263508Sdim 579263508Sdim CheckPreds = true; 580263508Sdim for (MachineBasicBlock::iterator IE = MBB->begin();; --I) { 581263508Sdim unsigned Opc = I->getOpcode(); 582263508Sdim if (Opc == PPC::MTCTRloop || Opc == PPC::MTCTR8loop) { 583263508Sdim CheckPreds = false; 584263508Sdim break; 585239310Sdim } 586239310Sdim 587263508Sdim if (I != BI && clobbersCTR(I)) { 588263508Sdim DEBUG(dbgs() << "BB#" << MBB->getNumber() << " (" << 589263508Sdim MBB->getFullName() << ") instruction " << *I << 590263508Sdim " clobbers CTR, invalidating " << "BB#" << 591263508Sdim BI->getParent()->getNumber() << " (" << 592263508Sdim BI->getParent()->getFullName() << ") instruction " << 593263508Sdim *BI << "\n"); 594263508Sdim return false; 595263508Sdim } 596239310Sdim 597263508Sdim if (I == IE) 598263508Sdim break; 599239310Sdim } 600239310Sdim 601263508Sdim if (!CheckPreds && Preds.empty()) 602263508Sdim return true; 603239310Sdim 604263508Sdim if (CheckPreds) { 605263508Sdimqueue_preds: 606263508Sdim if (MachineFunction::iterator(MBB) == MBB->getParent()->begin()) { 607263508Sdim DEBUG(dbgs() << "Unable to find a MTCTR instruction for BB#" << 608263508Sdim BI->getParent()->getNumber() << " (" << 609263508Sdim BI->getParent()->getFullName() << ") instruction " << 610263508Sdim *BI << "\n"); 611263508Sdim return false; 612263508Sdim } 613239310Sdim 614263508Sdim for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(), 615263508Sdim PIE = MBB->pred_end(); PI != PIE; ++PI) 616263508Sdim Preds.push_back(*PI); 617239310Sdim } 618239310Sdim 619263508Sdim do { 620263508Sdim MBB = Preds.pop_back_val(); 621263508Sdim if (!Visited.count(MBB)) { 622263508Sdim I = MBB->getLastNonDebugInstr(); 623263508Sdim goto check_block; 624263508Sdim } 625263508Sdim } while (!Preds.empty()); 626239310Sdim 627263508Sdim return true; 628263508Sdim} 629239310Sdim 630263508Sdimbool PPCCTRLoopsVerify::runOnMachineFunction(MachineFunction &MF) { 631263508Sdim MDT = &getAnalysis<MachineDominatorTree>(); 632239310Sdim 633263508Sdim // Verify that all bdnz/bdz instructions are dominated by a loop mtctr before 634263508Sdim // any other instructions that might clobber the ctr register. 635263508Sdim for (MachineFunction::iterator I = MF.begin(), IE = MF.end(); 636263508Sdim I != IE; ++I) { 637263508Sdim MachineBasicBlock *MBB = I; 638263508Sdim if (!MDT->isReachableFromEntry(MBB)) 639263508Sdim continue; 640239310Sdim 641263508Sdim for (MachineBasicBlock::iterator MII = MBB->getFirstTerminator(), 642263508Sdim MIIE = MBB->end(); MII != MIIE; ++MII) { 643263508Sdim unsigned Opc = MII->getOpcode(); 644263508Sdim if (Opc == PPC::BDNZ8 || Opc == PPC::BDNZ || 645263508Sdim Opc == PPC::BDZ8 || Opc == PPC::BDZ) 646263508Sdim if (!verifyCTRBranch(MBB, MII)) 647263508Sdim llvm_unreachable("Invalid PPC CTR loop!"); 648263508Sdim } 649263508Sdim } 650263508Sdim 651263508Sdim return false; 652239310Sdim} 653263508Sdim#endif // NDEBUG 654239310Sdim 655