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