// Loop through the inline asm constraints and look for something that clobbers
// ctr.
static bool asmClobbersCTR(InlineAsm *IA) {
  InlineAsm::ConstraintInfoVector CIV = IA->ParseConstraints();
  for (unsigned i = 0, ie = CIV.size(); i < ie; ++i) {
    InlineAsm::ConstraintInfo &C = CIV[i];
    if (C.Type != InlineAsm::isInput)
      for (unsigned j = 0, je = C.Codes.size(); j < je; ++j)
        if (StringRef(C.Codes[j]).equals_lower("{ctr}"))
          return true;
  }
  return false;
}

/// hasInlineAsmMemConstraint - Return true if the inline asm instruction being
/// processed uses a memory 'm' constraint.
bool
llvm::hasInlineAsmMemConstraint(InlineAsm::ConstraintInfoVector &CInfos,
                                const TargetLowering &TLI) {
  for (unsigned i = 0, e = CInfos.size(); i != e; ++i) {
    InlineAsm::ConstraintInfo &CI = CInfos[i];
    for (unsigned j = 0, ee = CI.Codes.size(); j != ee; ++j) {
      TargetLowering::ConstraintType CType = TLI.getConstraintType(CI.Codes[j]);
      if (CType == TargetLowering::C_Memory)
        return true;
    }

    // Indirect operand accesses access memory.
    if (CI.isIndirect)
      return true;
  }

  return false;
}

bool PPCCTRLoops::mightUseCTR(const Triple &TT, BasicBlock *BB) {
  for (BasicBlock::iterator J = BB->begin(), JE = BB->end();
       J != JE; ++J) {
    if (CallInst *CI = dyn_cast<CallInst>(J)) {
      if (InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue())) {
        // Inline ASM is okay, unless it clobbers the ctr register.
        InlineAsm::ConstraintInfoVector CIV = IA->ParseConstraints();
        for (unsigned i = 0, ie = CIV.size(); i < ie; ++i) {
          InlineAsm::ConstraintInfo &C = CIV[i];
          if (C.Type != InlineAsm::isInput)
            for (unsigned j = 0, je = C.Codes.size(); j < je; ++j)
              if (StringRef(C.Codes[j]).equals_lower("{ctr}"))
                return true;
        }

        continue;
      }

      if (!TM)
        return true;
      const TargetLowering *TLI = TM->getTargetLowering();

      if (Function *F = CI->getCalledFunction()) {
        // Most intrinsics don't become function calls, but some might.
        // sin, cos, exp and log are always calls.
        unsigned Opcode;
        if (F->getIntrinsicID() != Intrinsic::not_intrinsic) {
          switch (F->getIntrinsicID()) {
          default: continue;

// VisualStudio defines setjmp as _setjmp
#if defined(_MSC_VER) && defined(setjmp) && \
                       !defined(setjmp_undefined_for_msvc)
#  pragma push_macro("setjmp")
#  undef setjmp
#  define setjmp_undefined_for_msvc
#endif

          case Intrinsic::setjmp:

#if defined(_MSC_VER) && defined(setjmp_undefined_for_msvc)
 // let's return it to _setjmp state
#  pragma pop_macro("setjmp")
#  undef setjmp_undefined_for_msvc
#endif

          case Intrinsic::longjmp:

          // Exclude eh_sjlj_setjmp; we don't need to exclude eh_sjlj_longjmp
          // because, although it does clobber the counter register, the
          // control can't then return to inside the loop unless there is also
          // an eh_sjlj_setjmp.
          case Intrinsic::eh_sjlj_setjmp:

          case Intrinsic::memcpy:
          case Intrinsic::memmove:
          case Intrinsic::memset:
          case Intrinsic::powi:
          case Intrinsic::log:
          case Intrinsic::log2:
          case Intrinsic::log10:
          case Intrinsic::exp:
          case Intrinsic::exp2:
          case Intrinsic::pow:
          case Intrinsic::sin:
          case Intrinsic::cos:
            return true;
          case Intrinsic::copysign:
            if (CI->getArgOperand(0)->getType()->getScalarType()->
                isPPC_FP128Ty())
              return true;
            else
              continue; // ISD::FCOPYSIGN is never a library call.
          case Intrinsic::sqrt:      Opcode = ISD::FSQRT;      break;
          case Intrinsic::floor:     Opcode = ISD::FFLOOR;     break;
          case Intrinsic::ceil:      Opcode = ISD::FCEIL;      break;
          case Intrinsic::trunc:     Opcode = ISD::FTRUNC;     break;
          case Intrinsic::rint:      Opcode = ISD::FRINT;      break;
          case Intrinsic::nearbyint: Opcode = ISD::FNEARBYINT; break;
          case Intrinsic::round:     Opcode = ISD::FROUND;     break;
          }
        }

        // PowerPC does not use [US]DIVREM or other library calls for
        // operations on regular types which are not otherwise library calls
        // (i.e. soft float or atomics). If adapting for targets that do,
        // additional care is required here.

        LibFunc::Func Func;
        if (!F->hasLocalLinkage() && F->hasName() && LibInfo &&
            LibInfo->getLibFunc(F->getName(), Func) &&
            LibInfo->hasOptimizedCodeGen(Func)) {
          // Non-read-only functions are never treated as intrinsics.
          if (!CI->onlyReadsMemory())
            return true;

          // Conversion happens only for FP calls.
          if (!CI->getArgOperand(0)->getType()->isFloatingPointTy())
            return true;

//.........这里部分代码省略.........

/// Parse - Analyze the specified string (e.g. "==&{eax}") and fill in the
/// fields in this structure.  If the constraint string is not understood,
/// return true, otherwise return false.
bool InlineAsm::ConstraintInfo::Parse(StringRef Str,
                     InlineAsm::ConstraintInfoVector &ConstraintsSoFar) {
  StringRef::iterator I = Str.begin(), E = Str.end();
  unsigned multipleAlternativeCount = Str.count('|') + 1;
  unsigned multipleAlternativeIndex = 0;
  ConstraintCodeVector *pCodes = &Codes;

  // Initialize
  isMultipleAlternative = multipleAlternativeCount > 1;
  if (isMultipleAlternative) {
    multipleAlternatives.resize(multipleAlternativeCount);
    pCodes = &multipleAlternatives[0].Codes;
  }
  Type = isInput;
  isEarlyClobber = false;
  MatchingInput = -1;
  isCommutative = false;
  isIndirect = false;
  currentAlternativeIndex = 0;
  
  // Parse prefixes.
  if (*I == '~') {
    Type = isClobber;
    ++I;

    // '{' must immediately follow '~'.
    if (I != E && *I != '{')
      return true;
  } else if (*I == '=') {
    ++I;
    Type = isOutput;
  }

  if (*I == '*') {
    isIndirect = true;
    ++I;
  }

  if (I == E) return true;  // Just a prefix, like "==" or "~".
  
  // Parse the modifiers.
  bool DoneWithModifiers = false;
  while (!DoneWithModifiers) {
    switch (*I) {
    default:
      DoneWithModifiers = true;
      break;
    case '&':     // Early clobber.
      if (Type != isOutput ||      // Cannot early clobber anything but output.
          isEarlyClobber)          // Reject &&&&&&
        return true;
      isEarlyClobber = true;
      break;
    case '%':     // Commutative.
      if (Type == isClobber ||     // Cannot commute clobbers.
          isCommutative)           // Reject %%%%%
        return true;
      isCommutative = true;
      break;
    case '#':     // Comment.
    case '*':     // Register preferencing.
      return true;     // Not supported.
    }
    
    if (!DoneWithModifiers) {
      ++I;
      if (I == E) return true;   // Just prefixes and modifiers!
    }
  }
  
  // Parse the various constraints.
  while (I != E) {
    if (*I == '{') {   // Physical register reference.
      // Find the end of the register name.
      StringRef::iterator ConstraintEnd = std::find(I+1, E, '}');
      if (ConstraintEnd == E) return true;  // "{foo"
      pCodes->push_back(std::string(I, ConstraintEnd+1));
      I = ConstraintEnd+1;
    } else if (isdigit(static_cast<unsigned char>(*I))) { // Matching Constraint
      // Maximal munch numbers.
      StringRef::iterator NumStart = I;
      while (I != E && isdigit(static_cast<unsigned char>(*I)))
        ++I;
      pCodes->push_back(std::string(NumStart, I));
      unsigned N = atoi(pCodes->back().c_str());
      // Check that this is a valid matching constraint!
      if (N >= ConstraintsSoFar.size() || ConstraintsSoFar[N].Type != isOutput||
          Type != isInput)
        return true;  // Invalid constraint number.
      
      // If Operand N already has a matching input, reject this.  An output
      // can't be constrained to the same value as multiple inputs.
      if (isMultipleAlternative) {
        if (multipleAlternativeIndex >=
            ConstraintsSoFar[N].multipleAlternatives.size())
          return true;
        InlineAsm::SubConstraintInfo &scInfo =
//.........这里部分代码省略.........