Пример #1
0
void InstructionReplace::phase2(llvm::Module& M)
{
	for(llvm::Module::iterator F = M.begin(), ME = M.end(); F != ME; ++F) {
		for(llvm::Function::iterator BB = F->begin(),
		    FE = F->end();
		    BB != FE;
		    ++BB) {
			TaggedData& td = getAnalysis<TaggedData>(*F);
			if(!td.functionMarked(F)) {continue;}
			for( llvm::BasicBlock::iterator i = BB->begin(); i != BB->end(); i++) {
				NoCryptoFA::InstructionMetadata* md = NoCryptoFA::known[i];
				if(!md->hasBeenMasked) { continue; }
				for(Instruction::use_iterator u = i->use_begin(); u != i->use_end(); ++u) {
					Instruction* utilizzatore = cast<Instruction>(u.getUse().getUser());
					NoCryptoFA::InstructionMetadata* usemd = NoCryptoFA::known[utilizzatore];
					if(usemd->MaskedValues.empty()) {
						Unmask(i);
					}
				}
			}
		}
	}
}
Пример #2
0
void llvm::PointerMayBeCaptured(const Value *V, CaptureTracker *Tracker) {
  assert(V->getType()->isPointerTy() && "Capture is for pointers only!");
  SmallVector<Use*, Threshold> Worklist;
  SmallSet<Use*, Threshold> Visited;
  int Count = 0;

  for (Value::const_use_iterator UI = V->use_begin(), UE = V->use_end();
       UI != UE; ++UI) {
    // If there are lots of uses, conservatively say that the value
    // is captured to avoid taking too much compile time.
    if (Count++ >= Threshold)
      return Tracker->tooManyUses();

    Use *U = &UI.getUse();
    if (!Tracker->shouldExplore(U)) continue;
    Visited.insert(U);
    Worklist.push_back(U);
  }

  while (!Worklist.empty()) {
    Use *U = Worklist.pop_back_val();
    Instruction *I = cast<Instruction>(U->getUser());
    V = U->get();

    switch (I->getOpcode()) {
    case Instruction::Call:
    case Instruction::Invoke: {
      CallSite CS(I);
      // Not captured if the callee is readonly, doesn't return a copy through
      // its return value and doesn't unwind (a readonly function can leak bits
      // by throwing an exception or not depending on the input value).
      if (CS.onlyReadsMemory() && CS.doesNotThrow() && I->getType()->isVoidTy())
        break;

      // Not captured if only passed via 'nocapture' arguments.  Note that
      // calling a function pointer does not in itself cause the pointer to
      // be captured.  This is a subtle point considering that (for example)
      // the callee might return its own address.  It is analogous to saying
      // that loading a value from a pointer does not cause the pointer to be
      // captured, even though the loaded value might be the pointer itself
      // (think of self-referential objects).
      CallSite::arg_iterator B = CS.arg_begin(), E = CS.arg_end();
      for (CallSite::arg_iterator A = B; A != E; ++A)
        if (A->get() == V && !CS.doesNotCapture(A - B))
          // The parameter is not marked 'nocapture' - captured.
          if (Tracker->captured(U))
            return;
      break;
    }
    case Instruction::Load:
      // Loading from a pointer does not cause it to be captured.
      break;
    case Instruction::VAArg:
      // "va-arg" from a pointer does not cause it to be captured.
      break;
    case Instruction::Store:
      if (V == I->getOperand(0))
        // Stored the pointer - conservatively assume it may be captured.
        if (Tracker->captured(U))
          return;
      // Storing to the pointee does not cause the pointer to be captured.
      break;
    case Instruction::BitCast:
    case Instruction::GetElementPtr:
    case Instruction::PHI:
    case Instruction::Select:
      // The original value is not captured via this if the new value isn't.
      for (Instruction::use_iterator UI = I->use_begin(), UE = I->use_end();
           UI != UE; ++UI) {
        Use *U = &UI.getUse();
        if (Visited.insert(U))
          if (Tracker->shouldExplore(U))
            Worklist.push_back(U);
      }
      break;
    case Instruction::ICmp:
      // Don't count comparisons of a no-alias return value against null as
      // captures. This allows us to ignore comparisons of malloc results
      // with null, for example.
      if (ConstantPointerNull *CPN =
          dyn_cast<ConstantPointerNull>(I->getOperand(1)))
        if (CPN->getType()->getAddressSpace() == 0)
          if (isNoAliasCall(V->stripPointerCastsSafe()))
            break;
      // Otherwise, be conservative. There are crazy ways to capture pointers
      // using comparisons.
      if (Tracker->captured(U))
        return;
      break;
    default:
      // Something else - be conservative and say it is captured.
      if (Tracker->captured(U))
        return;
      break;
    }
  }

  // All uses examined.
}