C++ AliasAnalysis::getModRefInfo方法代码示例

bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
                                  AliasAnalysis &AA) const {

  if (AliasAny)
    return true;

  assert(Inst->mayReadOrWriteMemory() &&
         "Instruction must either read or write memory.");

  for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
    if (auto *UnknownInst = getUnknownInst(i)) {
      const auto *C1 = dyn_cast<CallBase>(UnknownInst);
      const auto *C2 = dyn_cast<CallBase>(Inst);
      if (!C1 || !C2 || isModOrRefSet(AA.getModRefInfo(C1, C2)) ||
          isModOrRefSet(AA.getModRefInfo(C2, C1)))
        return true;
    }
  }

  for (iterator I = begin(), E = end(); I != E; ++I)
    if (isModOrRefSet(AA.getModRefInfo(
            Inst, MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo()))))
      return true;

  return false;
}

static bool isSafeToMove(Instruction *Inst, AliasAnalysis &AA,
                         SmallPtrSetImpl<Instruction *> &Stores) {

  if (Inst->mayWriteToMemory()) {
    Stores.insert(Inst);
    return false;
  }

  if (LoadInst *L = dyn_cast<LoadInst>(Inst)) {
    MemoryLocation Loc = MemoryLocation::get(L);
    for (Instruction *S : Stores)
      if (isModSet(AA.getModRefInfo(S, Loc)))
        return false;
  }

  if (Inst->isTerminator() || isa<PHINode>(Inst) || Inst->isEHPad() ||
      Inst->mayThrow())
    return false;

  if (auto *Call = dyn_cast<CallBase>(Inst)) {
    // Convergent operations cannot be made control-dependent on additional
    // values.
    if (Call->hasFnAttr(Attribute::Convergent))
      return false;

    for (Instruction *S : Stores)
      if (isModSet(AA.getModRefInfo(S, Call)))
        return false;
  }

  return true;
}

/// aliasesPointer - Return true if the specified pointer "may" (or must)
/// alias one of the members in the set.
///
bool AliasSet::aliasesPointer(const Value *Ptr, uint64_t Size,
                              const MDNode *TBAAInfo,
                              AliasAnalysis &AA) const {
  if (AliasTy == MustAlias) {
    assert(UnknownInsts.empty() && "Illegal must alias set!");

    // If this is a set of MustAliases, only check to see if the pointer aliases
    // SOME value in the set.
    PointerRec *SomePtr = getSomePointer();
    assert(SomePtr && "Empty must-alias set??");
    return AA.alias(AliasAnalysis::Location(SomePtr->getValue(),
                                            SomePtr->getSize(),
                                            SomePtr->getTBAAInfo()),
                    AliasAnalysis::Location(Ptr, Size, TBAAInfo));
  }

  // If this is a may-alias set, we have to check all of the pointers in the set
  // to be sure it doesn't alias the set...
  for (iterator I = begin(), E = end(); I != E; ++I)
    if (AA.alias(AliasAnalysis::Location(Ptr, Size, TBAAInfo),
                 AliasAnalysis::Location(I.getPointer(), I.getSize(),
                                         I.getTBAAInfo())))
      return true;

  // Check the unknown instructions...
  if (!UnknownInsts.empty()) {
    for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
      if (AA.getModRefInfo(UnknownInsts[i],
                           AliasAnalysis::Location(Ptr, Size, TBAAInfo)) !=
            AliasAnalysis::NoModRef)
        return true;
  }

  return false;
}

/// aliasesPointer - Return true if the specified pointer "may" (or must)
/// alias one of the members in the set.
///
bool AliasSet::aliasesPointer(const Value *Ptr, unsigned Size,
                              AliasAnalysis &AA) const {
  if (AliasTy == MustAlias) {
    assert(CallSites.empty() && "Illegal must alias set!");

    // If this is a set of MustAliases, only check to see if the pointer aliases
    // SOME value in the set...
    HashNodePair *SomePtr = getSomePointer();
    assert(SomePtr && "Empty must-alias set??");
    return AA.alias(SomePtr->first, SomePtr->second.getSize(), Ptr, Size);
  }

  // If this is a may-alias set, we have to check all of the pointers in the set
  // to be sure it doesn't alias the set...
  for (iterator I = begin(), E = end(); I != E; ++I)
    if (AA.alias(Ptr, Size, I.getPointer(), I.getSize()))
      return true;

  // Check the call sites list and invoke list...
  if (!CallSites.empty()) {
    if (AA.hasNoModRefInfoForCalls())
      return true;

    for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
      if (AA.getModRefInfo(CallSites[i], const_cast<Value*>(Ptr), Size)
                   != AliasAnalysis::NoModRef)
        return true;
  }

  return false;
}

bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
  if (AA.doesNotAccessMemory(CS))
    return false;

  for (unsigned i = 0, e = CallSites.size(); i != e; ++i) {
    if (AA.getModRefInfo(getCallSite(i), CS) != AliasAnalysis::NoModRef ||
        AA.getModRefInfo(CS, getCallSite(i)) != AliasAnalysis::NoModRef)
      return true;
  }

  for (iterator I = begin(), E = end(); I != E; ++I)
    if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
           AliasAnalysis::NoModRef)
      return true;

  return false;
}

bool AliasSet::aliasesUnknownInst(const Instruction *Inst,
                                  AliasAnalysis &AA) const {
    if (!Inst->mayReadOrWriteMemory())
        return false;

    for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
        ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
        if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
                AA.getModRefInfo(C2, C1) != MRI_NoModRef)
            return true;
    }

    for (iterator I = begin(), E = end(); I != E; ++I)
        if (AA.getModRefInfo(Inst, MemoryLocation(I.getPointer(), I.getSize(),
                             I.getAAInfo())) != MRI_NoModRef)
            return true;

    return false;
}

bool AliasSet::aliasesUnknownInst(Instruction *Inst, AliasAnalysis &AA) const {
  if (!Inst->mayReadOrWriteMemory())
    return false;

  for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
    CallSite C1 = getUnknownInst(i), C2 = Inst;
    if (!C1 || !C2 ||
        AA.getModRefInfo(C1, C2) != AliasAnalysis::NoModRef ||
        AA.getModRefInfo(C2, C1) != AliasAnalysis::NoModRef)
      return true;
  }

  for (iterator I = begin(), E = end(); I != E; ++I)
    if (AA.getModRefInfo(Inst, I.getPointer(), I.getSize()) !=
           AliasAnalysis::NoModRef)
      return true;

  return false;
}

bool AliasSet::aliasesCallSite(CallSite CS, AliasAnalysis &AA) const {
  if (Function *F = CS.getCalledFunction())
    if (AA.doesNotAccessMemory(F))
      return false;

  if (AA.hasNoModRefInfoForCalls())
    return true;

  for (unsigned i = 0, e = CallSites.size(); i != e; ++i)
    if (AA.getModRefInfo(CallSites[i], CS) != AliasAnalysis::NoModRef ||
        AA.getModRefInfo(CS, CallSites[i]) != AliasAnalysis::NoModRef)
      return true;

  for (iterator I = begin(), E = end(); I != E; ++I)
    if (AA.getModRefInfo(CS, I.getPointer(), I.getSize()) !=
           AliasAnalysis::NoModRef)
      return true;

  return false;
}

/// aliasesPointer - If the specified pointer "may" (or must) alias one of the
/// members in the set return the appropriate AliasResult. Otherwise return
/// NoAlias.
///
AliasResult AliasSet::aliasesPointer(const Value *Ptr, LocationSize Size,
                                     const AAMDNodes &AAInfo,
                                     AliasAnalysis &AA) const {
  if (AliasAny)
    return MayAlias;

  if (Alias == SetMustAlias) {
    assert(UnknownInsts.empty() && "Illegal must alias set!");

    // If this is a set of MustAliases, only check to see if the pointer aliases
    // SOME value in the set.
    PointerRec *SomePtr = getSomePointer();
    assert(SomePtr && "Empty must-alias set??");
    return AA.alias(MemoryLocation(SomePtr->getValue(), SomePtr->getSize(),
                                   SomePtr->getAAInfo()),
                    MemoryLocation(Ptr, Size, AAInfo));
  }

  // If this is a may-alias set, we have to check all of the pointers in the set
  // to be sure it doesn't alias the set...
  for (iterator I = begin(), E = end(); I != E; ++I)
    if (AliasResult AR = AA.alias(
            MemoryLocation(Ptr, Size, AAInfo),
            MemoryLocation(I.getPointer(), I.getSize(), I.getAAInfo())))
      return AR;

  // Check the unknown instructions...
  if (!UnknownInsts.empty()) {
    for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
      if (auto *Inst = getUnknownInst(i))
        if (isModOrRefSet(
                AA.getModRefInfo(Inst, MemoryLocation(Ptr, Size, AAInfo))))
          return MayAlias;
  }

  return NoAlias;
}