/// AddCatchInfo - Extract the personality and type infos from an eh.selector
/// call, and add them to the specified machine basic block.
void llvm::AddCatchInfo(CallInst &I, MachineModuleInfo *MMI,
                        MachineBasicBlock *MBB) {
  // Inform the MachineModuleInfo of the personality for this landing pad.
  ConstantExpr *CE = cast<ConstantExpr>(I.getOperand(2));
  assert(CE->getOpcode() == Instruction::BitCast &&
         isa<Function>(CE->getOperand(0)) &&
         "Personality should be a function");
  MMI->addPersonality(MBB, cast<Function>(CE->getOperand(0)));

  // Gather all the type infos for this landing pad and pass them along to
  // MachineModuleInfo.
  std::vector<GlobalVariable *> TyInfo;
  unsigned N = I.getNumOperands();

  for (unsigned i = N - 1; i > 2; --i) {
    if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(i))) {
      unsigned FilterLength = CI->getZExtValue();
      unsigned FirstCatch = i + FilterLength + !FilterLength;
      assert (FirstCatch <= N && "Invalid filter length");

      if (FirstCatch < N) {
        TyInfo.reserve(N - FirstCatch);
        for (unsigned j = FirstCatch; j < N; ++j)
          TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
        MMI->addCatchTypeInfo(MBB, TyInfo);
        TyInfo.clear();
      }

      if (!FilterLength) {
        // Cleanup.
        MMI->addCleanup(MBB);
      } else {
        // Filter.
        TyInfo.reserve(FilterLength - 1);
        for (unsigned j = i + 1; j < FirstCatch; ++j)
          TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
        MMI->addFilterTypeInfo(MBB, TyInfo);
        TyInfo.clear();
      }

      N = i;
    }
  }

  if (N > 3) {
    TyInfo.reserve(N - 3);
    for (unsigned j = 3; j < N; ++j)
      TyInfo.push_back(ExtractTypeInfo(I.getOperand(j)));
    MMI->addCatchTypeInfo(MBB, TyInfo);
  }
}
Exemplo n.º 2
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// Return the copied value if the value is a bs copy, otherwise null
Value *getBSCopyValue(Value *v) {
  CallInst *call = dyn_cast<CallInst>(v);
  if (!call) return nullptr;
  // This is kind of dubious
  return call->getName().find(".__rmc_bs_copy") != StringRef::npos?
    call->getOperand(0) : nullptr;
}
Exemplo n.º 3
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//
// Function: makeFSParameterCallsComplete()
//
// Description:
//  Finds calls to sc.fsparameter and fills in the completeness byte which
//  is the last argument to such call. The second argument to the function
//  is the one which is analyzed for completeness.
//
// Inputs:
//  M      - Reference to the the module to analyze
//
void
CompleteChecks::makeFSParameterCallsComplete(Module &M)
{
  Function *sc_fsparameter = M.getFunction("sc.fsparameter");

  if (sc_fsparameter == NULL)
    return;

  std::set<CallInst *> toComplete;

  //
  // Iterate over all uses of sc.fsparameter and discover which have a complete
  // pointer argument.
  //
  for (Function::use_iterator i = sc_fsparameter->use_begin();
       i != sc_fsparameter->use_end(); ++i) {
    CallInst *CI;
    CI = dyn_cast<CallInst>(*i);
    if (CI == 0 || CI->getCalledFunction() != sc_fsparameter)
      continue;

    //
    // Get the parent function to which this call belongs.
    //
    Function *P = CI->getParent()->getParent();
    Value *PtrOperand = CI->getOperand(2);
    
    DSNode *N = getDSNodeHandle(PtrOperand, P).getNode();

    if (N == 0                ||
        N->isExternalNode()   ||
        N->isIncompleteNode() ||
        N->isUnknownNode()    ||
        N->isPtrToIntNode()   ||
        N->isIntToPtrNode()) {
      continue;
    }

    toComplete.insert(CI);
  }

  //
  // Fill in a 1 for each call instruction that has a complete pointer
  // argument.
  //
  Type *int8      = Type::getInt8Ty(M.getContext());
  Constant *complete = ConstantInt::get(int8, 1);

  for (std::set<CallInst *>::iterator i = toComplete.begin();
       i != toComplete.end();
       ++i) {
    CallInst *CI = *i;
    CI->setOperand(4, complete);
  }

  return;
}
Exemplo n.º 4
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CallInst* FunctionCalls::changeFunctionCall(Module &module, Change* change) {
  FunctionChange *funChange = (FunctionChange*)change;
  CallInst *oldCallInst = dyn_cast<CallInst>(funChange->getValue());
  CallInst *newCallInst = NULL;
  string oldFunction = oldCallInst->getCalledFunction()->getName();
  string newFunction = funChange->getSwitch();

  // TODO: use the types vector to not assume signature
  Function *newCallee = module.getFunction(newFunction);
  if (newCallee) {
    errs() << "Changing function call from " << oldFunction << " to " << newFunction << "\n";
    
    if (oldFunction != newFunction) {
      // retrieving original operand
      Value *oldOperand = oldCallInst->getOperand(0);
      
      // downcasting operand    
      Type *fType = Type::getFloatTy(module.getContext());
      FPTruncInst *newOperand = new FPTruncInst(oldOperand, fType, "", oldCallInst);
      
      // populating array of operands
      vector<Value*> operands;
      operands.push_back(newOperand);
      ArrayRef<Value*> *arrayRefOperands = new ArrayRef<Value*>(operands);
      
      // creating the new CallInst
      newCallInst = CallInst::Create(newCallee, *arrayRefOperands, "newCall", oldCallInst);
      
      // casting result to double
      Type *dType = Type::getDoubleTy(module.getContext());
      FPExtInst *result = new FPExtInst(newCallInst, dType, "", oldCallInst);
      
      // replacing all uses of call instruction
      oldCallInst->replaceAllUsesWith(result);
    
      // deleting old callInst
      oldCallInst->eraseFromParent();
      
      errs() << "\tChange was successful\n";
    }
    else {
      errs() << "\tNo change required\n";
    }
  }
  else {
    errs() << "\tDid not find function " << newFunction << "\n";
  }
  
  return newCallInst;
}
Exemplo n.º 5
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void LLVMDefUseAnalysis::handleCallInst(LLVMNode *node)
{
    CallInst *CI = cast<CallInst>(node->getKey());

    if (CI->isInlineAsm()) {
        handleInlineAsm(node);
        return;
    }

    Function *func
        = dyn_cast<Function>(CI->getCalledValue()->stripPointerCasts());
    if (func) {
        if (func->isIntrinsic() && !isa<DbgInfoIntrinsic>(CI)) {
            handleIntrinsicCall(node, CI);
            return;
        }

        // for realloc, we need to make it data dependent on the
        // memory it reallocates, since that is the memory it copies
        if (func->size() == 0) {
            using analysis::AllocationFunction;
            auto type = _options.getAllocationFunction(func->getName());

            if (type == AllocationFunction::REALLOC) {
                addDataDependence(node, CI, CI->getOperand(0), Offset::UNKNOWN /* FIXME */);
            } else if (type == AllocationFunction::NONE) {
                handleUndefinedCall(node, CI);
            }// else {
             // we do not want to do anything for the memory
             // allocation functions
             // }

            // the function is undefined, so do not even try to
            // add the edges from return statements
            return;
        }
    }

    // add edges from the return nodes of subprocedure
    // to the call (if the call returns something)
    for (LLVMDependenceGraph *subgraph : node->getSubgraphs())
        addReturnEdge(node, subgraph);
}
Exemplo n.º 6
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void LLVMDefUseAnalysis::handleInlineAsm(LLVMNode *callNode)
{
    CallInst *CI = cast<CallInst>(callNode->getValue());
    LLVMDependenceGraph *dg = callNode->getDG();

    // the last operand is the asm itself, so iterate only to e - 1
    for (unsigned i = 0, e = CI->getNumOperands(); i < e - 1; ++i) {
        Value *opVal = CI->getOperand(i);
        if (!opVal->getType()->isPointerTy())
            continue;

        LLVMNode *opNode = dg->getNode(opVal->stripInBoundsOffsets());
        if (!opNode) {
            // FIXME: ConstantExpr
            llvmutils::printerr("WARN: unhandled inline asm operand: ", opVal);
            continue;
        }

        assert(opNode && "Do not have an operand for inline asm");

        // if nothing else, this call at least uses the operands
        opNode->addDataDependence(callNode);
    }
}
Exemplo n.º 7
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  void visitCallInst(CallInst &I) {
    string intrinsic = I.getCalledFunction()->getName().str();

    if(intrinsic.find("modmul") != -1) {

      CallInst *enterMontpro1 = enterMontgomery(I.getOperand(0), I.getOperand(2), &I);
      CallInst *enterMontpro2 = enterMontgomery(I.getOperand(1), I.getOperand(2), &I);
      CallInst *mulMontpro = mulMontgomery(I.getName().str(), enterMontpro1, enterMontpro2, I.getOperand(2), &I);
      CallInst *exitMontpro = leaveMontgomery(mulMontpro, I.getOperand(2), &I);

      I.replaceAllUsesWith(exitMontpro);

      I.removeFromParent();
    } else if(intrinsic.find("modexp") != -1) {
      
      CallInst *enterMontpro1 = enterMontgomery(I.getOperand(0), I.getOperand(2), &I);
      CallInst *expMontpro = expMontgomery(I.getName().str(), enterMontpro1, I.getOperand(1), I.getOperand(2), &I);
      CallInst *exitMontpro = leaveMontgomery(expMontpro, I.getOperand(2), &I);

      I.replaceAllUsesWith(exitMontpro);

      I.eraseFromParent();
    }
  }
Exemplo n.º 8
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//
// Function: makeCStdLibCallsComplete()
//
// Description:
//  Fills in completeness information for all calls of a given CStdLib function
//  assumed to be of the form:
//
//   pool_X(POOL *p1, ..., POOL *pN, void *a1, ..., void *aN, ..., uint8_t c);
//
//  Specifically, this function assumes that there are as many pointer arguments
//  to check as there are initial pool arguments, and the pointer arguments
//  follow the pool arguments in corresponding order. Also, it is assumed that
//  the final argument to the function is a byte sized bit vector.
//
//  This function fills in this final byte with a constant value whose ith
//  bit is set exactly when the ith pointer argument is complete.
//
// Inputs:
//
//  F            - A pointer to the CStdLib function appearing in the module
//                 (non-null).
//  PoolArgs     - The number of initial pool arguments for which a
//                 corresponding pointer value requires a completeness check
//                 (required to be at most 8).
//
void
CompleteChecks::makeCStdLibCallsComplete(Function *F, unsigned PoolArgs) {
  assert(F != 0 && "Null function argument!");

  assert(PoolArgs <= 8 && \
    "Only up to 8 arguments are supported by CStdLib completeness checks!");

  Value::use_iterator U = F->use_begin();
  Value::use_iterator E = F->use_end();

  //
  // Hold the call instructions that need changing.
  //
  typedef std::pair<CallInst *, uint8_t> VectorReplacement;
  std::set<VectorReplacement> callsToChange;

  Type *int8ty = Type::getInt8Ty(F->getContext());
  FunctionType *F_type = F->getFunctionType();

  //
  // Verify the type of the function is as expected.
  //
  // There should be as many pointer parameters to check for completeness
  // as there are pool parameters. The last parameter should be a byte.
  //
  assert(F_type->getNumParams() >= PoolArgs * 2 && \
    "Not enough arguments to transformed CStdLib function call!");
  for (unsigned arg = PoolArgs; arg < PoolArgs * 2; ++arg)
    assert(isa<PointerType>(F_type->getParamType(arg)) && \
      "Expected pointer argument to function!");

  //
  // This is the position of the vector operand in the call.
  //
  unsigned vect_position = F_type->getNumParams();

  assert(F_type->getParamType(vect_position - 1) == int8ty && \
    "Last parameter to the function should be a byte!");

  //
  // Iterate over all calls of the function in the module, computing the
  // vectors for each call as it is found.
  //
  for (; U != E; ++U) {
    CallInst *CI;
    if ((CI = dyn_cast<CallInst>(*U)) && \
      CI->getCalledValue()->stripPointerCasts() == F) {

      uint8_t vector = 0x0;

      //
      // Get the parent function to which this instruction belongs.
      //
      Function *P = CI->getParent()->getParent();

      //
      // Iterate over the pointer arguments that need completeness checking
      // and build the completeness vector.
      //
      for (unsigned arg = 0; arg < PoolArgs; ++arg) {
        bool complete = true;
        //
        // Go past all the pool arguments to get the pointer to check.
        //
        Value *V = CI->getOperand(1 + PoolArgs + arg);

        //
        // Check for completeness of the pointer using DSA and 
        // set the bit in the vector accordingly.
        //
        DSNode *N;
        if ((N = getDSNodeHandle(V, P).getNode()) &&
              (N->isExternalNode() || N->isIncompleteNode() ||
               N->isUnknownNode()  || N->isIntToPtrNode()   ||
               N->isPtrToIntNode()) ) {
            complete = false;
        }

        if (complete)
          vector |= (1 << arg);
      }

      //
      // Add the instruction and vector to the set of instructions to change.
      //
      callsToChange.insert(VectorReplacement(CI, vector));
    }
  }


  //
  // Iterate over all call instructions that need changing, modifying the
  // final operand of the call to hold the bit vector value.
  //
  std::set<VectorReplacement>::iterator change = callsToChange.begin();
  std::set<VectorReplacement>::iterator change_end = callsToChange.end();

  while (change != change_end) {
    Constant *vect_value = ConstantInt::get(int8ty, change->second);
    change->first->setOperand(vect_position, vect_value);
    ++change;
  }

  return;

}
Exemplo n.º 9
0
//
// Method: runOnModule()
//
// Description:
//  Entry point for this LLVM pass.
//  Clone functions that take GEPs as arguments
//
// Inputs:
//  M - A reference to the LLVM module to transform
//
// Outputs:
//  M - The transformed LLVM module.
//
// Return value:
//  true  - The module was modified.
//  false - The module was not modified.
//
bool GEPExprArgs::runOnModule(Module& M) {
  bool changed;
  do {
    changed = false;
    for (Module::iterator F = M.begin(); F != M.end(); ++F){
      for (Function::iterator B = F->begin(), FE = F->end(); B != FE; ++B) {
        for (BasicBlock::iterator I = B->begin(), BE = B->end(); I != BE;) {
          CallInst *CI = dyn_cast<CallInst>(I++);
          if(!CI)
            continue;

          if(CI->hasByValArgument())
            continue;
          // if the GEP calls a function, that is externally defined,
          // or might be changed, ignore this call site.
          Function *F = CI->getCalledFunction();

          if (!F || (F->isDeclaration() || F->mayBeOverridden())) 
            continue;
          if(F->hasStructRetAttr())
            continue;
          if(F->isVarArg())
            continue;

          // find the argument we must replace
          Function::arg_iterator ai = F->arg_begin(), ae = F->arg_end();
          unsigned argNum = 1;
          for(; argNum < CI->getNumOperands();argNum++, ++ai) {
            if(ai->use_empty())
              continue;
            if (isa<GEPOperator>(CI->getOperand(argNum)))
              break;
          }

          // if no argument was a GEP operator to be changed 
          if(ai == ae)
            continue;

          GEPOperator *GEP = dyn_cast<GEPOperator>(CI->getOperand(argNum));
          if(!GEP->hasAllConstantIndices())
            continue;

          // Construct the new Type
          // Appends the struct Type at the beginning
          std::vector<Type*>TP;
          TP.push_back(GEP->getPointerOperand()->getType());
          for(unsigned c = 1; c < CI->getNumOperands();c++) {
            TP.push_back(CI->getOperand(c)->getType());
          }

          //return type is same as that of original instruction
          FunctionType *NewFTy = FunctionType::get(CI->getType(), TP, false);
          Function *NewF;
          numSimplified++;
          if(numSimplified > 800) 
            return true;

          NewF = Function::Create(NewFTy,
                                  GlobalValue::InternalLinkage,
                                  F->getName().str() + ".TEST",
                                  &M);

          Function::arg_iterator NI = NewF->arg_begin();
          NI->setName("GEParg");
          ++NI;

          ValueToValueMapTy ValueMap;

          for (Function::arg_iterator II = F->arg_begin(); NI != NewF->arg_end(); ++II, ++NI) {
            ValueMap[II] = NI;
            NI->setName(II->getName());
            NI->addAttr(F->getAttributes().getParamAttributes(II->getArgNo() + 1));
          }
          NewF->setAttributes(NewF->getAttributes().addAttr(
              0, F->getAttributes().getRetAttributes()));
          // Perform the cloning.
          SmallVector<ReturnInst*,100> Returns;
          CloneFunctionInto(NewF, F, ValueMap, false, Returns);
          std::vector<Value*> fargs;
          for(Function::arg_iterator ai = NewF->arg_begin(), 
              ae= NewF->arg_end(); ai != ae; ++ai) {
            fargs.push_back(ai);
          }

          NewF->setAttributes(NewF->getAttributes().addAttr(
              ~0, F->getAttributes().getFnAttributes()));
          //Get the point to insert the GEP instr.
          SmallVector<Value*, 8> Ops(CI->op_begin()+1, CI->op_end());
          Instruction *InsertPoint;
          for (BasicBlock::iterator insrt = NewF->front().begin(); 
               isa<AllocaInst>(InsertPoint = insrt); ++insrt) {;}

          NI = NewF->arg_begin();
          SmallVector<Value*, 8> Indices;
          Indices.append(GEP->op_begin()+1, GEP->op_end());
          GetElementPtrInst *GEP_new = GetElementPtrInst::Create(cast<Value>(NI),
                                                                 Indices, 
                                                                 "", InsertPoint);
          fargs.at(argNum)->replaceAllUsesWith(GEP_new);
          unsigned j = argNum + 1;
          for(; j < CI->getNumOperands();j++) {
            if(CI->getOperand(j) == GEP)
              fargs.at(j)->replaceAllUsesWith(GEP_new);
          }

          SmallVector<AttributeWithIndex, 8> AttributesVec;

          // Get the initial attributes of the call
          AttrListPtr CallPAL = CI->getAttributes();
          Attributes RAttrs = CallPAL.getRetAttributes();
          Attributes FnAttrs = CallPAL.getFnAttributes();
          if (RAttrs)
            AttributesVec.push_back(AttributeWithIndex::get(0, RAttrs));

          SmallVector<Value*, 8> Args;
          Args.push_back(GEP->getPointerOperand());
          for(unsigned j =1;j<CI->getNumOperands();j++) {
            Args.push_back(CI->getOperand(j));
            // position in the AttributesVec
            if (Attributes Attrs = CallPAL.getParamAttributes(j))
              AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs));
          }
          // Create the new attributes vec.
          if (FnAttrs != Attribute::None)
            AttributesVec.push_back(AttributeWithIndex::get(~0, FnAttrs));

          AttrListPtr NewCallPAL = AttrListPtr::get(AttributesVec.begin(),
                                                    AttributesVec.end());

          CallInst *CallI = CallInst::Create(NewF,Args,"", CI);
          CallI->setCallingConv(CI->getCallingConv());
          CallI->setAttributes(NewCallPAL);
          CI->replaceAllUsesWith(CallI);
          CI->eraseFromParent();
          changed = true;
        }
      }
    }
  } while(changed);
  return true;
}
Exemplo n.º 10
0
void TracingNoGiri::visitCallInst(CallInst &CI) {
  // Attempt to get the called function.
  Function *CalledFunc = CI.getCalledFunction();
  if (!CalledFunc)
    return;

  // Do not instrument calls to tracing run-time functions or debug functions.
  if (isTracerFunction(CalledFunc))
    return;

  if (!CalledFunc->getName().str().compare(0,9,"llvm.dbg."))
    return;

  // Instrument external calls which can have invariants on its return value
  if (CalledFunc->isDeclaration() && CalledFunc->isIntrinsic()) {
     // Instrument special external calls which loads/stores
     // e.g. strlen(), strcpy(), memcpy() etc.
     visitSpecialCall(CI);
     return;
  }

  // If the called value is inline assembly code, then don't instrument it.
  if (isa<InlineAsm>(CI.getCalledValue()->stripPointerCasts()))
    return;

  instrumentLock(&CI);
  // Get the ID of the store instruction.
  Value *CallID = ConstantInt::get(Int32Type, lsNumPass->getID(&CI));
  // Get the called function value and cast it to a void pointer.
  Value *FP = castTo(CI.getCalledValue(), VoidPtrType, "", &CI);
  // Create the call to the run-time to record the call instruction.
  std::vector<Value *> args = make_vector<Value *>(CallID, FP, 0);
  // Do not add calls to function call stack for external functions
  // as return records won't be used/needed for them, so call a special record function
  // FIXME!!!! Do we still need it after adding separate return records????
  Instruction *RC;
  if (CalledFunc->isDeclaration())
    RC = CallInst::Create(RecordExtCall, args, "", &CI);
  else
    RC = CallInst::Create(RecordCall, args, "", &CI);
  instrumentUnlock(RC);

  // Create the call to the run-time to record the return of call instruction.
  CallInst *CallInst = CallInst::Create(RecordReturn, args, "", &CI);
  CI.moveBefore(CallInst);
  instrumentLock(CallInst);
  instrumentUnlock(CallInst);

  ++NumCalls; // Update statistics

  // The best way to handle external call is to set a flag before calling ext fn and
  // use that to determine if an internal function is called from ext fn. It flag can be
  // reset afterwards and restored to its original value before returning to ext code.
  // FIXME!!!! LATER

#if 0
  if (CalledFunc->isDeclaration() &&
      CalledFunc->getName().str() == "pthread_create") {
    // If pthread_create is called then handle it specially as it calls
    // functions externally and add an extra call for the externally
    // called functions with the same id so that returns can match with it.
    // In addition to a function call to pthread_create.
    // Get the external function pointer operand and cast it to a void pointer
    Value *FP = castTo(CI.getOperand(2), VoidPtrType, "", &CI);
    // Create the call to the run-time to record the call instruction.
    std::vector<Value *> argsExt = make_vector<Value *>(CallID, FP, 0);
    CallInst = CallInst::Create(RecordCall, argsExt, "", &CI);
    CI.moveBefore(CallInst);

    // Update statistics
    ++Calls;

    // For, both external functions and internal/ext functions called from
    // external functions, return records are not useful as they won't be used.
    // Since, we won't create return records for them, simply update the call
    // stack to mark the end of function call.

    //args = make_vector<Value *>(CallID, FP, 0);
    //CallInst::Create(RecordExtCallRet, args.begin(), args.end(), "", &CI);

    // Create the call to the run-time to record the return of call instruction.
    CallInst::Create(RecordReturn, argsExt, "", &CI);
  }
#endif

  // Instrument special external calls which loads/stores
  // like strlen, strcpy, memcpy etc.
  visitSpecialCall(CI);
}
Exemplo n.º 11
0
bool TracingNoGiri::visitSpecialCall(CallInst &CI) {
  Function *CalledFunc = CI.getCalledFunction();

  // We do not support indirect calls to special functions.
  if (CalledFunc == nullptr)
    return false;

  // Do not consider a function special if it has a function body; in this
  // case, the programmer has supplied his or her version of the function, and
  // we will instrument it.
  if (!CalledFunc->isDeclaration())
    return false;

  // Check the name of the function against a list of known special functions.
  std::string name = CalledFunc->getName().str();
  if (name.substr(0,12) == "llvm.memset.") {
    instrumentLock(&CI);

    // Get the destination pointer and cast it to a void pointer.
    Value *dstPointer = CI.getOperand(0);
    dstPointer = castTo(dstPointer, VoidPtrType, dstPointer->getName(), &CI);
    // Get the number of bytes that will be written into the buffer.
    Value *NumElts = CI.getOperand(2);
    // Get the ID of the external funtion call instruction.
    Value *CallID = ConstantInt::get(Int32Type, lsNumPass->getID(&CI));
    // Create the call to the run-time to record the external call instruction.
    std::vector<Value *> args = make_vector(CallID, dstPointer, NumElts, 0);
    CallInst::Create(RecordStore, args, "", &CI);

    instrumentUnlock(&CI);
    ++NumExtFuns; // Update statistics
    return true;
  } else if (name.substr(0,12) == "llvm.memcpy." ||
             name.substr(0,13) == "llvm.memmove." ||
             name == "strcpy") {
    instrumentLock(&CI);

    /* Record Load src, [CI] Load dst [CI] */
    // Get the destination and source pointers and cast them to void pointers.
    Value *dstPointer = CI.getOperand(0);
    Value *srcPointer  = CI.getOperand(1);
    dstPointer = castTo(dstPointer, VoidPtrType, dstPointer->getName(), &CI);
    srcPointer  = castTo(srcPointer,  VoidPtrType, srcPointer->getName(), &CI);
    // Get the ID of the ext fun call instruction.
    Value *CallID = ConstantInt::get(Int32Type, lsNumPass->getID(&CI));

    // Create the call to the run-time to record the loads and stores of
    // external call instruction.
    if(name == "strcpy") {
      // FIXME: If the tracer function should be inserted before or after????
      std::vector<Value *> args = make_vector(CallID, srcPointer, 0);
      CallInst::Create(RecordStrLoad, args, "", &CI);

      args = make_vector(CallID, dstPointer, 0);
      CallInst *recStore = CallInst::Create(RecordStrStore, args, "", &CI);
      CI.moveBefore(recStore);
    } else {
      // get the num elements to be transfered
      Value *NumElts = CI.getOperand(2);
      std::vector<Value *> args = make_vector(CallID, srcPointer, NumElts, 0);
      CallInst::Create(RecordLoad, args, "", &CI);

      args = make_vector(CallID, dstPointer, NumElts, 0);
      CallInst::Create(RecordStore, args, "", &CI);
    }

    instrumentUnlock(&CI);
    ++NumExtFuns; // Update statistics
    return true;
  } else if (name == "strcat") { /* Record Load dst, Load Src, Store dst-end before call inst  */
    instrumentLock(&CI);

    // Get the destination and source pointers and cast them to void pointers.
    Value *dstPointer = CI.getOperand(0);
    Value *srcPointer = CI.getOperand(1);
    dstPointer = castTo(dstPointer, VoidPtrType, dstPointer->getName(), &CI);
    srcPointer  = castTo(srcPointer,  VoidPtrType, srcPointer->getName(), &CI);

    // Get the ID of the ext fun call instruction.
    Value *CallID = ConstantInt::get(Int32Type, lsNumPass->getID(&CI));

    // Create the call to the run-time to record the loads and stores of
    // external call instruction.
    // CHECK: If the tracer function should be inserted before or after????
    std::vector<Value *> args = make_vector(CallID, dstPointer, 0);
    CallInst::Create(RecordStrLoad, args, "", &CI);

    args = make_vector(CallID, srcPointer, 0);
    CallInst::Create(RecordStrLoad, args, "", &CI);

    // Record the addresses before concat as they will be lost after concat
    args = make_vector(CallID, dstPointer, srcPointer, 0);
    CallInst::Create(RecordStrcatStore, args, "", &CI);

    instrumentUnlock(&CI);
    ++NumExtFuns; // Update statistics
    return true;
  } else if (name == "strlen") { /* Record Load */
    instrumentLock(&CI);

    // Get the destination and source pointers and cast them to void pointers.
    Value *srcPointer  = CI.getOperand(0);
    srcPointer  = castTo(srcPointer,  VoidPtrType, srcPointer->getName(), &CI);
    // Get the ID of the ext fun call instruction.
    Value *CallID = ConstantInt::get(Int32Type, lsNumPass->getID(&CI));
    std::vector<Value *> args = make_vector(CallID, srcPointer, 0);
    CallInst::Create(RecordStrLoad, args, "", &CI);

    instrumentUnlock(&CI);
    ++NumExtFuns; // Update statistics
    return true;
  } else if (name == "calloc") {
    instrumentLock(&CI);

    // Get the number of bytes that will be written into the buffer.
    Value *NumElts = BinaryOperator::Create(BinaryOperator::Mul,
                                            CI.getOperand(0),
                                            CI.getOperand(1),
                                            "calloc par1 * par2",
                                            &CI);
    // Get the destination pointer and cast it to a void pointer.
    // Instruction * dstPointerInst;
    Value *dstPointer = castTo(&CI, VoidPtrType, CI.getName(), &CI);

    /* // To move after call inst, we need to know if cast is a constant expr or inst
    if ((dstPointerInst = dyn_cast<Instruction>(dstPointer))) {
        CI.moveBefore(dstPointerInst); // dstPointerInst->insertAfter(&CI);
        // ((Instruction *)NumElts)->insertAfter(dstPointerInst);
    }
    else {
        CI.moveBefore((Instruction *)NumElts); // ((Instruction *)NumElts)->insertAfter(&CI);
	}
    dstPointer = dstPointerInst; // Assign to dstPointer for instrn or non-instrn values
    */

    // Get the ID of the external funtion call instruction.
    Value *CallID = ConstantInt::get(Int32Type, lsNumPass->getID(&CI));

    //
    // Create the call to the run-time to record the external call instruction.
    //
    std::vector<Value *> args = make_vector(CallID, dstPointer, NumElts, 0);
    CallInst *recStore = CallInst::Create(RecordStore, args, "", &CI);
    CI.moveBefore(recStore); //recStore->insertAfter((Instruction *)NumElts);

    // Moove cast, #byte computation and store to after call inst
    CI.moveBefore(cast<Instruction>(NumElts));

    instrumentUnlock(&CI);
    ++NumExtFuns; // Update statistics
    return true;
  } else if (name == "tolower" || name == "toupper") {
    // Not needed as there are no loads and stores
  /*  } else if (name == "strncpy/itoa/stdarg/scanf/fscanf/sscanf/fread/complex/strftime/strptime/asctime/ctime") { */
  } else if (name == "fscanf") {
    // TODO
    // In stead of parsing format string, can we use the type of the arguments??
  } else if (name == "sscanf") {
    // TODO
  } else if (name == "sprintf") {
    instrumentLock(&CI);
    // Get the pointer to the destination buffer.
    Value *dstPointer = CI.getOperand(0);
    dstPointer = castTo(dstPointer, VoidPtrType, dstPointer->getName(), &CI);

    // Get the ID of the call instruction.
    Value *CallID = ConstantInt::get(Int32Type, lsNumPass->getID(&CI));

    // Scan through the arguments looking for what appears to be a character
    // string.  Generate load records for each of these strings.
    for (unsigned index = 2; index < CI.getNumOperands(); ++index) {
      if (CI.getOperand(index)->getType() == VoidPtrType) {
        // Create the call to the run-time to record the load from the string.
        // What about other loads??
        Value *Ptr = CI.getOperand(index);
        std::vector<Value *> args = make_vector(CallID, Ptr, 0);
        CallInst::Create(RecordStrLoad, args, "", &CI);

        ++NumLoadStrings; // Update statistics
      }
    }

    // Create the call to the run-time to record the external call instruction.
    std::vector<Value *> args = make_vector(CallID, dstPointer, 0);
    CallInst *recStore = CallInst::Create(RecordStrStore, args, "", &CI);
    CI.moveBefore(recStore);

    instrumentUnlock(&CI);
    ++NumStoreStrings; // Update statistics
    return true;
  } else if (name == "fgets") {
    instrumentLock(&CI);

    // Get the pointer to the destination buffer.
    Value * dstPointer = CI.getOperand(0);
    dstPointer = castTo(dstPointer, VoidPtrType, dstPointer->getName(), &CI);

    // Get the ID of the ext fun call instruction.
    Value * CallID = ConstantInt::get(Int32Type, lsNumPass->getID(&CI));

    // Create the call to the run-time to record the external call instruction.
    std::vector<Value *> args = make_vector(CallID, dstPointer, 0);
    CallInst *recStore = CallInst::Create(RecordStrStore, args, "", &CI);
    CI.moveBefore(recStore);

    instrumentUnlock(&CI);
    // Update statistics
    ++NumStoreStrings;
    return true;
  }

  return false;
}
Exemplo n.º 12
0
//
// Method: runOnModule()
//
// Description:
//  Entry point for this LLVM pass.
//  Search for all call sites to casted functions.
//  Check if they only differ in an argument type
//  Cast the argument, and call the original function
//
// Inputs:
//  M - A reference to the LLVM module to transform
//
// Outputs:
//  M - The transformed LLVM module.
//
// Return value:
//  true  - The module was modified.
//  false - The module was not modified.
//
bool ArgCast::runOnModule(Module& M) {

  std::vector<CallInst*> worklist;
  for (Module::iterator I = M.begin(); I != M.end(); ++I) {
    if (I->mayBeOverridden())
      continue;
    // Find all uses of this function
    for(Value::user_iterator ui = I->user_begin(), ue = I->user_end(); ui != ue; ) {
      // check if is ever casted to a different function type
      ConstantExpr *CE = dyn_cast<ConstantExpr>(*ui++);
      if(!CE)
        continue;
      if (CE->getOpcode() != Instruction::BitCast)
        continue;
      if(CE->getOperand(0) != I)
        continue;
      const PointerType *PTy = dyn_cast<PointerType>(CE->getType());
      if (!PTy)
        continue;
      const Type *ETy = PTy->getElementType();
      const FunctionType *FTy  = dyn_cast<FunctionType>(ETy); 
      if(!FTy)
        continue;
      // casting to a varargs funtion
      // or function with same number of arguments
      // possibly varying types of arguments
      
      if(FTy->getNumParams() != I->arg_size() && !FTy->isVarArg())
        continue;
      for(Value::user_iterator uii = CE->user_begin(),
          uee = CE->user_end(); uii != uee; ++uii) {
        // Find all uses of the casted value, and check if it is 
        // used in a Call Instruction
        if (CallInst* CI = dyn_cast<CallInst>(*uii)) {
          // Check that it is the called value, and not an argument
          if(CI->getCalledValue() != CE) 
            continue;
          // Check that the number of arguments passed, and expected
          // by the function are the same.
          if(!I->isVarArg()) {
            if(CI->getNumOperands() != I->arg_size() + 1)
              continue;
          } else {
            if(CI->getNumOperands() < I->arg_size() + 1)
              continue;
          }
          // If so, add to worklist
          worklist.push_back(CI);
        }
      }
    }
  }

  // Proces the worklist of potential call sites to transform
  while(!worklist.empty()) {
    CallInst *CI = worklist.back();
    worklist.pop_back();
    // Get the called Function
    Function *F = cast<Function>(CI->getCalledValue()->stripPointerCasts());
    const FunctionType *FTy = F->getFunctionType();

    SmallVector<Value*, 8> Args;
    unsigned i =0;
    for(i =0; i< FTy->getNumParams(); ++i) {
      Type *ArgType = CI->getOperand(i+1)->getType();
      Type *FormalType = FTy->getParamType(i);
      // If the types for this argument match, just add it to the
      // parameter list. No cast needs to be inserted.
      if(ArgType == FormalType) {
        Args.push_back(CI->getOperand(i+1));
      }
      else if(ArgType->isPointerTy() && FormalType->isPointerTy()) {
        CastInst *CastI = CastInst::CreatePointerCast(CI->getOperand(i+1), 
                                                      FormalType, "", CI);
        Args.push_back(CastI);
      } else if (ArgType->isIntegerTy() && FormalType->isIntegerTy()) {
        unsigned SrcBits = ArgType->getScalarSizeInBits();
        unsigned DstBits = FormalType->getScalarSizeInBits();
        if(SrcBits > DstBits) {
          CastInst *CastI = CastInst::CreateIntegerCast(CI->getOperand(i+1), 
                                                        FormalType, true, "", CI);
          Args.push_back(CastI);
        } else {
          if (F->getAttributes().hasAttribute(i+1, Attribute::SExt)) {
            CastInst *CastI = CastInst::CreateIntegerCast(CI->getOperand(i+1), 
                                                          FormalType, true, "", CI);
            Args.push_back(CastI);
          } else if (F->getAttributes().hasAttribute(i+1, Attribute::ZExt)) {
            CastInst *CastI = CastInst::CreateIntegerCast(CI->getOperand(i+1), 
                                                          FormalType, false, "", CI);
            Args.push_back(CastI);
          } else {
            // Use ZExt in default case.
            // Derived from InstCombine. Also, the only reason this should happen
            // is mismatched prototypes.
            // Seen in case of integer constants which get interpreted as i32, 
            // even if being used as i64.
            // TODO: is this correct?
            CastInst *CastI = CastInst::CreateIntegerCast(CI->getOperand(i+1), 
                                                          FormalType, false, "", CI);
            Args.push_back(CastI);
          } 
        } 
      } else {
        DEBUG(ArgType->dump());
        DEBUG(FormalType->dump());
        break;
      }
    }

    // If we found an argument we could not cast, try the next instruction
    if(i != FTy->getNumParams()) {
      continue;
    }

    if(FTy->isVarArg()) {
      for(; i< CI->getNumOperands() - 1 ;i++) {
        Args.push_back(CI->getOperand(i+1));
      }
    }

    // else replace the call instruction
    CallInst *CINew = CallInst::Create(F, Args, "", CI);
    CINew->setCallingConv(CI->getCallingConv());
    CINew->setAttributes(CI->getAttributes());
    if(!CI->use_empty()) {
      CastInst *RetCast;
      if(CI->getType() != CINew->getType()) {
        if(CI->getType()->isPointerTy() && CINew->getType()->isPointerTy())
          RetCast = CastInst::CreatePointerCast(CINew, CI->getType(), "", CI);
        else if(CI->getType()->isIntOrIntVectorTy() && CINew->getType()->isIntOrIntVectorTy())
          RetCast = CastInst::CreateIntegerCast(CINew, CI->getType(), false, "", CI);
        else if(CI->getType()->isIntOrIntVectorTy() && CINew->getType()->isPointerTy())
          RetCast = CastInst::CreatePointerCast(CINew, CI->getType(), "", CI);
        else if(CI->getType()->isPointerTy() && CINew->getType()->isIntOrIntVectorTy()) 
          RetCast = new IntToPtrInst(CINew, CI->getType(), "", CI);
        else {
          // TODO: I'm not sure what right behavior is here, but this case should be handled.
          llvm_unreachable("Unexpected type conversion in call!");
          abort();
        }
        CI->replaceAllUsesWith(RetCast);
      } else {
        CI->replaceAllUsesWith(CINew);
      }
    }

    // Debug printing
    DEBUG(errs() << "ARGCAST:");
    DEBUG(errs() << "ERASE:");
    DEBUG(CI->dump());
    DEBUG(errs() << "ARGCAST:");
    DEBUG(errs() << "ADDED:");
    DEBUG(CINew->dump());

    CI->eraseFromParent();
    numChanged++;
  }
  return true;
}
Exemplo n.º 13
0
//
// Method: runOnModule()
//
// Description:
//  Entry point for this LLVM pass.
//  If a function returns a struct, make it return
//  a pointer to the struct.
//
// Inputs:
//  M - A reference to the LLVM module to transform
//
// Outputs:
//  M - The transformed LLVM module.
//
// Return value:
//  true  - The module was modified.
//  false - The module was not modified.
//
bool StructRet::runOnModule(Module& M) {
  const llvm::DataLayout targetData(&M);

  std::vector<Function*> worklist;
  for (Module::iterator I = M.begin(); I != M.end(); ++I)
    if (!I->mayBeOverridden()) {
      if(I->hasAddressTaken())
        continue;
      if(I->getReturnType()->isStructTy()) {
        worklist.push_back(I);
      }
    }

  while(!worklist.empty()) {
    Function *F = worklist.back();
    worklist.pop_back();
    Type *NewArgType = F->getReturnType()->getPointerTo();

    // Construct the new Type
    std::vector<Type*>TP;
    TP.push_back(NewArgType);
    for (Function::arg_iterator ii = F->arg_begin(), ee = F->arg_end();
         ii != ee; ++ii) {
      TP.push_back(ii->getType());
    }

    FunctionType *NFTy = FunctionType::get(F->getReturnType(), TP, F->isVarArg());

    // Create the new function body and insert it into the module.
    Function *NF = Function::Create(NFTy, 
                                    F->getLinkage(),
                                    F->getName(), &M);
    ValueToValueMapTy ValueMap;
    Function::arg_iterator NI = NF->arg_begin();
    NI->setName("ret");
    ++NI;
    for (Function::arg_iterator II = F->arg_begin(); II != F->arg_end(); ++II, ++NI) {
      ValueMap[II] = NI;
      NI->setName(II->getName());
      AttributeSet attrs = F->getAttributes().getParamAttributes(II->getArgNo() + 1);
      if (!attrs.isEmpty())
        NI->addAttr(attrs);
    }
    // Perform the cloning.
    SmallVector<ReturnInst*,100> Returns;
    if (!F->isDeclaration())
      CloneFunctionInto(NF, F, ValueMap, false, Returns);
    std::vector<Value*> fargs;
    for(Function::arg_iterator ai = NF->arg_begin(), 
        ae= NF->arg_end(); ai != ae; ++ai) {
      fargs.push_back(ai);
    }
    NF->setAttributes(NF->getAttributes().addAttributes(
        M.getContext(), 0, F->getAttributes().getRetAttributes()));
    NF->setAttributes(NF->getAttributes().addAttributes(
        M.getContext(), ~0, F->getAttributes().getFnAttributes()));
    
    for (Function::iterator B = NF->begin(), FE = NF->end(); B != FE; ++B) {      
      for (BasicBlock::iterator I = B->begin(), BE = B->end(); I != BE;) {
        ReturnInst * RI = dyn_cast<ReturnInst>(I++);
        if(!RI)
          continue;
        LoadInst *LI = dyn_cast<LoadInst>(RI->getOperand(0));
        assert(LI && "Return should be preceded by a load instruction");
        IRBuilder<> Builder(RI);
        Builder.CreateMemCpy(fargs.at(0),
            LI->getPointerOperand(),
            targetData.getTypeStoreSize(LI->getType()),
            targetData.getPrefTypeAlignment(LI->getType()));
      }
    }

    for(Value::use_iterator ui = F->use_begin(), ue = F->use_end();
        ui != ue; ) {
      CallInst *CI = dyn_cast<CallInst>(*ui++);
      if(!CI)
        continue;
      if(CI->getCalledFunction() != F)
        continue;
      if(CI->hasByValArgument())
        continue;
      AllocaInst *AllocaNew = new AllocaInst(F->getReturnType(), 0, "", CI);
      SmallVector<Value*, 8> Args;

      //this should probably be done in a different manner
      AttributeSet NewCallPAL=AttributeSet();
      
      // Get the initial attributes of the call
      AttributeSet CallPAL = CI->getAttributes();
      AttributeSet RAttrs = CallPAL.getRetAttributes();
      AttributeSet FnAttrs = CallPAL.getFnAttributes();
      
      if (!RAttrs.isEmpty())
        NewCallPAL=NewCallPAL.addAttributes(F->getContext(),0, RAttrs);

      Args.push_back(AllocaNew);
      for(unsigned j = 0; j < CI->getNumOperands()-1; j++) {
        Args.push_back(CI->getOperand(j));
        // position in the NewCallPAL
        AttributeSet Attrs = CallPAL.getParamAttributes(j);
        if (!Attrs.isEmpty())
          NewCallPAL=NewCallPAL.addAttributes(F->getContext(),Args.size(), Attrs);
      }
      // Create the new attributes vec.
      if (!FnAttrs.isEmpty())
        NewCallPAL=NewCallPAL.addAttributes(F->getContext(),~0, FnAttrs);

      CallInst *CallI = CallInst::Create(NF, Args, "", CI);
      CallI->setCallingConv(CI->getCallingConv());
      CallI->setAttributes(NewCallPAL);
      LoadInst *LI = new LoadInst(AllocaNew, "", CI);
      CI->replaceAllUsesWith(LI);
      CI->eraseFromParent();
    }
    if(F->use_empty())
      F->eraseFromParent();
  }
  return true;
}
Exemplo n.º 14
0
bool IRTranslator::translateKnownIntrinsic(const CallInst &CI,
                                           Intrinsic::ID ID) {
  unsigned Op = 0;
  switch (ID) {
  default: return false;
  case Intrinsic::uadd_with_overflow: Op = TargetOpcode::G_UADDE; break;
  case Intrinsic::sadd_with_overflow: Op = TargetOpcode::G_SADDO; break;
  case Intrinsic::usub_with_overflow: Op = TargetOpcode::G_USUBE; break;
  case Intrinsic::ssub_with_overflow: Op = TargetOpcode::G_SSUBO; break;
  case Intrinsic::umul_with_overflow: Op = TargetOpcode::G_UMULO; break;
  case Intrinsic::smul_with_overflow: Op = TargetOpcode::G_SMULO; break;
  case Intrinsic::memcpy:
    return translateMemcpy(CI);
  case Intrinsic::eh_typeid_for: {
    GlobalValue *GV = ExtractTypeInfo(CI.getArgOperand(0));
    unsigned Reg = getOrCreateVReg(CI);
    unsigned TypeID = MIRBuilder.getMF().getMMI().getTypeIDFor(GV);
    MIRBuilder.buildConstant(Reg, TypeID);
    return true;
  }
  case Intrinsic::objectsize: {
    // If we don't know by now, we're never going to know.
    const ConstantInt *Min = cast<ConstantInt>(CI.getArgOperand(1));

    MIRBuilder.buildConstant(getOrCreateVReg(CI), Min->isZero() ? -1ULL : 0);
    return true;
  }
  case Intrinsic::stackguard:
    getStackGuard(getOrCreateVReg(CI));
    return true;
  case Intrinsic::stackprotector: {
    MachineFunction &MF = MIRBuilder.getMF();
    LLT PtrTy{*CI.getArgOperand(0)->getType(), *DL};
    unsigned GuardVal = MRI->createGenericVirtualRegister(PtrTy);
    getStackGuard(GuardVal);

    AllocaInst *Slot = cast<AllocaInst>(CI.getArgOperand(1));
    MIRBuilder.buildStore(
        GuardVal, getOrCreateVReg(*Slot),
        *MF.getMachineMemOperand(
            MachinePointerInfo::getFixedStack(MF, getOrCreateFrameIndex(*Slot)),
            MachineMemOperand::MOStore | MachineMemOperand::MOVolatile,
            PtrTy.getSizeInBits() / 8, 8));
    return true;
  }
  }

  LLT Ty{*CI.getOperand(0)->getType(), *DL};
  LLT s1 = LLT::scalar(1);
  unsigned Width = Ty.getSizeInBits();
  unsigned Res = MRI->createGenericVirtualRegister(Ty);
  unsigned Overflow = MRI->createGenericVirtualRegister(s1);
  auto MIB = MIRBuilder.buildInstr(Op)
                 .addDef(Res)
                 .addDef(Overflow)
                 .addUse(getOrCreateVReg(*CI.getOperand(0)))
                 .addUse(getOrCreateVReg(*CI.getOperand(1)));

  if (Op == TargetOpcode::G_UADDE || Op == TargetOpcode::G_USUBE) {
    unsigned Zero = MRI->createGenericVirtualRegister(s1);
    EntryBuilder.buildConstant(Zero, 0);
    MIB.addUse(Zero);
  }

  MIRBuilder.buildSequence(getOrCreateVReg(CI), Res, 0, Overflow, Width);
  return true;
}
Exemplo n.º 15
0
bool TypeChecksOpt::runOnModule(Module &M) {
  TS = &getAnalysis<dsa::TypeSafety<TDDataStructures> >();

  // Create the necessary prototypes
  VoidTy = IntegerType::getVoidTy(M.getContext());
  Int8Ty = IntegerType::getInt8Ty(M.getContext());
  Int32Ty = IntegerType::getInt32Ty(M.getContext());
  Int64Ty = IntegerType::getInt64Ty(M.getContext());
  VoidPtrTy = PointerType::getUnqual(Int8Ty);
  TypeTagTy = Int8Ty;
  TypeTagPtrTy = PointerType::getUnqual(TypeTagTy);

  Constant *memsetF = M.getOrInsertFunction ("llvm.memset.i64", VoidTy,
                                             VoidPtrTy,
                                             Int8Ty,
                                             Int64Ty,
                                             Int32Ty,
                                             NULL);
  trackGlobal = M.getOrInsertFunction("trackGlobal",
                                      VoidTy,
                                      VoidPtrTy,/*ptr*/
                                      TypeTagTy,/*type*/
                                      Int64Ty,/*size*/
                                      Int32Ty,/*tag*/
                                      NULL);
  trackInitInst = M.getOrInsertFunction("trackInitInst",
                                        VoidTy,
                                        VoidPtrTy,/*ptr*/
                                        Int64Ty,/*size*/
                                        Int32Ty,/*tag*/
                                        NULL);
  trackUnInitInst = M.getOrInsertFunction("trackUnInitInst",
                                          VoidTy,
                                          VoidPtrTy,/*ptr*/
                                          Int64Ty,/*size*/
                                          Int32Ty,/*tag*/
                                          NULL);
  trackStoreInst = M.getOrInsertFunction("trackStoreInst",
                                         VoidTy,
                                         VoidPtrTy,/*ptr*/
                                         TypeTagTy,/*type*/
                                         Int64Ty,/*size*/
                                         Int32Ty,/*tag*/
                                         NULL);
  checkTypeInst = M.getOrInsertFunction("checkType",
                                        VoidTy,
                                        TypeTagTy,/*type*/
                                        Int64Ty,/*size*/
                                        TypeTagPtrTy,
                                        VoidPtrTy,/*ptr*/
                                        Int32Ty,/*tag*/
                                        NULL);
  copyTypeInfo = M.getOrInsertFunction("copyTypeInfo",
                                       VoidTy,
                                       VoidPtrTy,/*dest ptr*/
                                       VoidPtrTy,/*src ptr*/
                                       Int64Ty,/*size*/
                                       Int32Ty,/*tag*/
                                       NULL);
  setTypeInfo = M.getOrInsertFunction("setTypeInfo",
                                      VoidTy,
                                      VoidPtrTy,/*dest ptr*/
                                      TypeTagPtrTy,/*metadata*/
                                      Int64Ty,/*size*/
                                      TypeTagTy,
                                      VoidPtrTy,
                                      Int32Ty,/*tag*/
                                      NULL);
  trackStringInput = M.getOrInsertFunction("trackStringInput",
                                           VoidTy,
                                           VoidPtrTy,
                                           Int32Ty,
                                           NULL);
  getTypeTag = M.getOrInsertFunction("getTypeTag",
                                     VoidTy,
                                     VoidPtrTy, /*ptr*/
                                     Int64Ty, /*size*/
                                     TypeTagPtrTy, /*dest for type tag*/
                                     Int32Ty, /*tag*/
                                     NULL);
  MallocFunc = M.getFunction("malloc");

  for(Value::use_iterator User = trackGlobal->use_begin(); User != trackGlobal->use_end(); ++User) {
    CallInst *CI = dyn_cast<CallInst>(*User);
    assert(CI);
    if(TS->isTypeSafe(CI->getOperand(1)->stripPointerCasts(), CI->getParent()->getParent())) {
      std::vector<Value*>Args;
      Args.push_back(CI->getOperand(1));
      Args.push_back(CI->getOperand(3));
      Args.push_back(CI->getOperand(4));
      CallInst::Create(trackInitInst, Args, "", CI);
      toDelete.push_back(CI);
    }
  }

  for(Value::use_iterator User = checkTypeInst->use_begin(); User != checkTypeInst->use_end(); ++User) {
    CallInst *CI = dyn_cast<CallInst>(*User);
    assert(CI);

    if(TS->isTypeSafe(CI->getOperand(4)->stripPointerCasts(), CI->getParent()->getParent())) {
      toDelete.push_back(CI);
    }
  }

  for(Value::use_iterator User = trackStoreInst->use_begin(); User != trackStoreInst->use_end(); ++User) {
    CallInst *CI = dyn_cast<CallInst>(*User);
    assert(CI);

    if(TS->isTypeSafe(CI->getOperand(1)->stripPointerCasts(), CI->getParent()->getParent())) {
      toDelete.push_back(CI);
    }
  }

  // for alloca's if they are type known
  // assume initialized with TOP
  for(Value::use_iterator User = trackUnInitInst->use_begin(); User != trackUnInitInst->use_end(); ) {
    CallInst *CI = dyn_cast<CallInst>(*(User++));
    assert(CI);

    // check if operand is an alloca inst.
    if(TS->isTypeSafe(CI->getOperand(1)->stripPointerCasts(), CI->getParent()->getParent())) {
      CI->setCalledFunction(trackInitInst);

      if(AllocaInst *AI = dyn_cast<AllocaInst>(CI->getOperand(1)->stripPointerCasts())) {
        // Initialize the allocation to NULL
        std::vector<Value *> Args2;
        Args2.push_back(CI->getOperand(1));
        Args2.push_back(ConstantInt::get(Int8Ty, 0));
        Args2.push_back(CI->getOperand(2));
        Args2.push_back(ConstantInt::get(Int32Ty, AI->getAlignment()));
        CallInst::Create(memsetF, Args2, "", CI);
      }
    }
  }

  if(MallocFunc) {
    for(Value::use_iterator User = MallocFunc->use_begin(); User != MallocFunc->use_end(); User ++) {
      CallInst *CI = dyn_cast<CallInst>(*User);
      if(!CI)
        continue;
      if(TS->isTypeSafe(CI, CI->getParent()->getParent())){
        CastInst *BCI = BitCastInst::CreatePointerCast(CI, VoidPtrTy);
        CastInst *Size = CastInst::CreateSExtOrBitCast(CI->getOperand(1), Int64Ty);
        Size->insertAfter(CI);
        BCI->insertAfter(Size);
        std::vector<Value *>Args;
        Args.push_back(BCI);
        Args.push_back(Size);
        Args.push_back(ConstantInt::get(Int32Ty, 0));
        CallInst *CINew = CallInst::Create(trackInitInst, Args);
        CINew->insertAfter(BCI);
      }
    }
  }

  // also do for mallocs/calloc/other allocators???
  // other allocators??

  for(Value::use_iterator User = copyTypeInfo->use_begin(); User != copyTypeInfo->use_end(); ++User) {
    CallInst *CI = dyn_cast<CallInst>(*User);
    assert(CI);

    if(TS->isTypeSafe(CI->getOperand(1)->stripPointerCasts(), CI->getParent()->getParent())) {
      std::vector<Value*> Args;
      Args.push_back(CI->getOperand(1));
      Args.push_back(CI->getOperand(3)); // size
      Args.push_back(CI->getOperand(4));
      CallInst::Create(trackInitInst, Args, "", CI);
      toDelete.push_back(CI);
    }
  }
  for(Value::use_iterator User = setTypeInfo->use_begin(); User != setTypeInfo->use_end(); ++User) {
    CallInst *CI = dyn_cast<CallInst>(*User);
    assert(CI);

    if(TS->isTypeSafe(CI->getOperand(1)->stripPointerCasts(), CI->getParent()->getParent())) {
      std::vector<Value*> Args;
      Args.push_back(CI->getOperand(1));
      Args.push_back(CI->getOperand(3)); // size
      Args.push_back(CI->getOperand(6));
      CallInst::Create(trackInitInst, Args, "", CI);
      toDelete.push_back(CI);
    }
  }

  for(Value::use_iterator User = getTypeTag->use_begin(); User != getTypeTag->use_end(); ++User) {
    CallInst *CI = dyn_cast<CallInst>(*User);
    assert(CI);
    if(TS->isTypeSafe(CI->getOperand(1)->stripPointerCasts(), CI->getParent()->getParent())) {
      AllocaInst *AI = dyn_cast<AllocaInst>(CI->getOperand(3)->stripPointerCasts());
      assert(AI);
      std::vector<Value*>Args;
      Args.push_back(CI->getOperand(3));
      Args.push_back(ConstantInt::get(Int8Ty, 255));
      Args.push_back(CI->getOperand(2));
      Args.push_back(ConstantInt::get(Int32Ty, AI->getAlignment()));
      CallInst::Create(memsetF, Args, "", CI);
      toDelete.push_back(CI);
    }
  }

  numSafe += toDelete.size();

  while(!toDelete.empty()) {
    Instruction *I = toDelete.back();
    toDelete.pop_back();
    I->eraseFromParent();
  }

  return (numSafe > 0);
}
Exemplo n.º 16
0
string esp::parseName(Value *value){
  // has existed
  if(names.find(value) != names.end())
    return names[value];

  string name = "";
  Value *current = value;

  /*
  bool continueFlag = true;
  do{
    if(isa<Instruction > (current)){
      Instruction* inst = dyn_cast<Instruction>(current);
      unsigned op = inst->getOpcode();
      switch(op){
      case Instruction::Ret :{
        break;
      }

      case Instruction::Br :{
        break;
      }

      case Instruction::Switch :{
        break;
      }

      case Instruction::Call :{
        CallInst *callinst = (CallInst*) current;

        if (((CallInst*) current)->getCalledFunction() != NULL) {
            name += string("@")+((CallInst*) current)->getCalledFunction()->getNameStr() + "(";
        } else {
            name += string("@[funcPTR](");
            name += ((CallInst*) current)->getCalledValue()->getNameStr();
        }

        for (unsigned i = 1; i < callinst->getNumOperands(); i++) {
            name += esp::parseName(callinst->getOperand(i));
        }

        name += string(")");
        continueFlag = false;
        break;
      }

      case Instruction::PHI :{
        name += string("PHI[");
        name += current->getNameStr();
        PHINode *phi = (PHINode*) current;
        for (unsigned i = 0; i < phi->getNumIncomingValues(); i++) {
            Value *incoming = phi->getIncomingValue(i);
            if (i != 0) name += ",";
            if (!hasLoop(incoming)) {
                if (!incoming->hasName()) {
                    name += esp::parseName(incoming);
                } else {
                    name += incoming->getNameStr();
                }

            }
        }

        name += std::string("]");
        continueFlag = false;
        break;
      }

      case Instruction::Select :{
        break;
      }

      case Instruction::Add :{
        name += "+";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::Sub :{
        name += "-";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::Mul :{
        name += "*";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::UDiv :{
        name += "/";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::SDiv :{
        name += "//";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::And :{
        name += "&";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::Or :{
        name += "|";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::Xor :{
        name += "^";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::Shl :{
        name += "<<";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::LShr :{
        name += ">>";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::AShr :{
        name += ">>>";
        name += parseBinaryOpName(inst);
        break;
      }

      case Instruction::ICmp :{
        ICmpInst * icmp = dyn_cast<ICmpInst>(current);
        if (isa<Constant>(icmp->getOperand(0))) {
          name += esp::parseName(icmp->getOperand(1));
          continueFlag = false;
        } else {
          name += esp::parseName(icmp->getOperand(0));
          continueFlag = false;
        }
        break;
      }

      case Instruction::Alloca :{
        name += current->getNameStr();
        break;
      }

      case Instruction::Load :{
        if (((LoadInst*) inst)->isVolatile())
          name += std::string("@VolatileLoad");
        name += "*";
        name += esp::parseName(inst->getOperand(0));
        continueFlag = false;
        break;
      }

      case Instruction::Store :{
        // need to handle
        continueFlag = false;
        break;
      }

      case Instruction::GetElementPtr :{
        GetElementPtrInst * gep = dyn_cast<GetElementPtrInst>(current);
        unsigned ops = gep->getNumOperands();
        name += "[";
        for (unsigned i = 1; i < ops; i++) {
          Value *v = gep->getOperand(i);
          if (ConstantInt * ci = dyn_cast<ConstantInt>(v)) {
            if (i == 1 && ci->equalsInt(0))
              continue;
            name += ".";
            name += ci->getValue().toString(10, false);
          } else {
            name += ".";
            name += esp::parseName(v);
          }
        }
        name += "]";
        name += esp::parseName(gep->getOperand(0));
        continueFlag = false;
        break;
      }

      case Instruction::BitCast:{
        name += esp::parseName(inst->getOperand(0));
        continueFlag = false;
        break;
      }

      default :{
        // Illegal or unsupported instruction
        name += current->getNameStr();
        break;
      }
      }

    }else if(isa<Argument>(current)){
      if (arguments.find(current) != arguments.end())
        name += std::string("$") + current->getNameStr();

    }else if(isa<GlobalValue>(current)){
      name += std::string("@") + current->getNameStr();

    }else if(isa<ConstantInt>(current)){
      ConstantInt * cint = dyn_cast<ConstantInt > (current);
      name += cint->getValue().toString(10, true);

    }else if (isa<Constant > (current)) {
      Constant *c = dyn_cast<Constant > (current);
      if (c->isNullValue()) {
          name += "null";
      }
  }else{
      // Illegal format
  }
  if(!continueFlag)
    break;
  current = parents[current];
  }while(current);
  */

  //Refactor

   do {
     if (isa<LoadInst > (current)) {
       name += "*";
       if (parents[current] == NULL)
         name += (((LoadInst*) current)->getOperand(0))->getNameStr();
       if (((LoadInst*) current)->isVolatile())
         name += std::string("@VolatileLoad");

     } else if (dyn_cast<GetElementPtrInst > (current)) {
       GetElementPtrInst * gep = dyn_cast<GetElementPtrInst > (current);
       unsigned ops = gep->getNumOperands();
       name += "[";
       for (unsigned i = 1; i < ops; i++) {
         Value *v = gep->getOperand(i);
         if (dyn_cast<ConstantInt > (current)) {
           ConstantInt * ci = dyn_cast<ConstantInt > (current);
           if (i == 1 && ci->equalsInt(0)) continue;
           name += ".";
           name += ci->getValue().toString(10, false);
         } else {
           name += ".";
           name += parseName(v);
         }

       }
       name += "]";
       name += parseName(gep->getOperand(0));
       break;

     } else if (isa<AllocaInst > (current)) {
       name += current->getNameStr();
     } else if (isa<Argument > (current)) {
       if (arguments.find(current) != arguments.end())
         name += std::string("$") + current->getNameStr();
     } else if (isa<GlobalValue > (current)) {
       name += std::string("@") + current->getNameStr();
     } else if (isa<CallInst > (current)) {
       CallInst *callinst = (CallInst*) current;

       if (((CallInst*) current)->getCalledFunction() != NULL) {
         name += std::string("@")+((CallInst*) current)->getCalledFunction()->getNameStr() + "(";
       } else {
         name += std::string("@[funcPTR](");
         name += ((CallInst*) current)->getCalledValue()->getNameStr();
       }

       for (unsigned i = 1; i < callinst->getNumOperands(); i++) {
         name += parseName(callinst->getOperand(i));
       }

       name += std::string(")");
       break;
     } else if (isa<CastInst > (current)) {
     } else if (isa<PHINode > (current)) {
       /*
       name += std::string("PHI[");
       s += parent->getNameStr();
       PHINode *phi = (PHINode*) parent;
       for (unsigned i = 0; i < phi->getNumIncomingValues(); i++) {
         //s+=phi->getIncomingBlock(i)->getNameStr();
         Value *incoming = phi->getIncomingValue(i);
         if (i != 0) s += ",";
         if (!hasLoop(incoming)) {
           DEBUG(errs() << "incoming#" << i << " no loop(i rather doubt it)\n");
           if (!incoming->hasName()) {
             s += parseName(incoming);
           } else {
             s += incoming->getNameStr();
           }

         }
       }

       // PHI nodes...ugh
       s += std::string("]");
       break;
       */

     } else if (isa<BinaryOperator > (current)) {
       BinaryOperator *bo = dyn_cast<BinaryOperator > (current);
       Instruction::BinaryOps opcode = bo->getOpcode();
       if (opcode == Instruction::Add) {
         name.append("+");
       } else if (opcode == Instruction::Sub) {
         name.append("-");
       } else if (opcode == Instruction::Or) {
         name.append("||");
       } else if (opcode == Instruction::Mul) {
         name.append("*");
       } else if (opcode == Instruction::Xor) {
         name.append("^");
       } else if (opcode == Instruction::And) {
         name.append("&&");
       } else if (opcode == Instruction::Shl) {
         name.append("<<");
       } else if (opcode == Instruction::AShr) {
         name.append(">>");
       } else if (opcode == Instruction::LShr) {
         name.append(">>>");
       }
       Value *v0 = bo->getOperand(0);
       Value *v1 = bo->getOperand(1);
       if (isa<ConstantInt > (v0)) {
         name += ((ConstantInt*) v0)->getValue().toString(10, false);
       } else if (isa<ConstantInt > (v1)) {
         name += ((ConstantInt*) v1)->getValue().toString(10, false);
       } else {
         printDebugMsg("Binary Operation between non-constants\n");
       }
     } else if (dyn_cast<GEPOperator > (current)) {
       GEPOperator * gep = dyn_cast<GEPOperator > (current);
       unsigned ops = gep->getNumOperands();
       name += "[";
       for (unsigned i = 1; i < ops; i++) {
         Value *v = gep->getOperand(i);
         if (dyn_cast<ConstantInt > (v)) {
           ConstantInt * ci = dyn_cast<ConstantInt > (v);
           if (i == 1 && ci->equalsInt(0)) continue;
           name += ".";
           name += ci->getValue().toString(10, false);
         }

       }
       name += "]";

       name += parseName(gep->getOperand(0));
       break;

     } else if (dyn_cast<ICmpInst > (current)) {
       ICmpInst * icmp = dyn_cast<ICmpInst > (current);
       if (isa<Constant > (icmp->getOperand(0))) {
         name += parseName(icmp->getOperand(1));
         break;
       } else {
         name += parseName(icmp->getOperand(0));
         break;
       }
     } else if (dyn_cast<ConstantInt > (current)) {
       ConstantInt * cint = dyn_cast<ConstantInt > (current);
       name += cint->getValue().toString(10, true);
     } else {
       name += current->getNameStr(); // might not work
     }

   } while ((current = parents[current]));

  names[value] = name;

  return name;
}
bool TailCallElim::ProcessReturningBlock(ReturnInst *Ret, BasicBlock *&OldEntry,
                                         bool &TailCallsAreMarkedTail,
                                         SmallVector<PHINode*, 8> &ArgumentPHIs,
                                       bool CannotTailCallElimCallsMarkedTail) {
  BasicBlock *BB = Ret->getParent();
  Function *F = BB->getParent();

  if (&BB->front() == Ret) // Make sure there is something before the ret...
    return false;
  
  // If the return is in the entry block, then making this transformation would
  // turn infinite recursion into an infinite loop.  This transformation is ok
  // in theory, but breaks some code like:
  //   double fabs(double f) { return __builtin_fabs(f); } // a 'fabs' call
  // disable this xform in this case, because the code generator will lower the
  // call to fabs into inline code.
  if (BB == &F->getEntryBlock())
    return false;

  // Scan backwards from the return, checking to see if there is a tail call in
  // this block.  If so, set CI to it.
  CallInst *CI;
  BasicBlock::iterator BBI = Ret;
  while (1) {
    CI = dyn_cast<CallInst>(BBI);
    if (CI && CI->getCalledFunction() == F)
      break;

    if (BBI == BB->begin())
      return false;          // Didn't find a potential tail call.
    --BBI;
  }

  // If this call is marked as a tail call, and if there are dynamic allocas in
  // the function, we cannot perform this optimization.
  if (CI->isTailCall() && CannotTailCallElimCallsMarkedTail)
    return false;

  // If we are introducing accumulator recursion to eliminate associative
  // operations after the call instruction, this variable contains the initial
  // value for the accumulator.  If this value is set, we actually perform
  // accumulator recursion elimination instead of simple tail recursion
  // elimination.
  Value *AccumulatorRecursionEliminationInitVal = 0;
  Instruction *AccumulatorRecursionInstr = 0;

  // Ok, we found a potential tail call.  We can currently only transform the
  // tail call if all of the instructions between the call and the return are
  // movable to above the call itself, leaving the call next to the return.
  // Check that this is the case now.
  for (BBI = CI, ++BBI; &*BBI != Ret; ++BBI)
    if (!CanMoveAboveCall(BBI, CI)) {
      // If we can't move the instruction above the call, it might be because it
      // is an associative operation that could be tranformed using accumulator
      // recursion elimination.  Check to see if this is the case, and if so,
      // remember the initial accumulator value for later.
      if ((AccumulatorRecursionEliminationInitVal =
                             CanTransformAccumulatorRecursion(BBI, CI))) {
        // Yes, this is accumulator recursion.  Remember which instruction
        // accumulates.
        AccumulatorRecursionInstr = BBI;
      } else {
        return false;   // Otherwise, we cannot eliminate the tail recursion!
      }
    }

  // We can only transform call/return pairs that either ignore the return value
  // of the call and return void, ignore the value of the call and return a
  // constant, return the value returned by the tail call, or that are being
  // accumulator recursion variable eliminated.
  if (Ret->getNumOperands() == 1 && Ret->getReturnValue() != CI &&
      !isa<UndefValue>(Ret->getReturnValue()) &&
      AccumulatorRecursionEliminationInitVal == 0 &&
      !getCommonReturnValue(Ret, CI))
    return false;

  // OK! We can transform this tail call.  If this is the first one found,
  // create the new entry block, allowing us to branch back to the old entry.
  if (OldEntry == 0) {
    OldEntry = &F->getEntryBlock();
    BasicBlock *NewEntry = BasicBlock::Create(F->getContext(), "", F, OldEntry);
    NewEntry->takeName(OldEntry);
    OldEntry->setName("tailrecurse");
    BranchInst::Create(OldEntry, NewEntry);

    // If this tail call is marked 'tail' and if there are any allocas in the
    // entry block, move them up to the new entry block.
    TailCallsAreMarkedTail = CI->isTailCall();
    if (TailCallsAreMarkedTail)
      // Move all fixed sized allocas from OldEntry to NewEntry.
      for (BasicBlock::iterator OEBI = OldEntry->begin(), E = OldEntry->end(),
             NEBI = NewEntry->begin(); OEBI != E; )
        if (AllocaInst *AI = dyn_cast<AllocaInst>(OEBI++))
          if (isa<ConstantInt>(AI->getArraySize()))
            AI->moveBefore(NEBI);

    // Now that we have created a new block, which jumps to the entry
    // block, insert a PHI node for each argument of the function.
    // For now, we initialize each PHI to only have the real arguments
    // which are passed in.
    Instruction *InsertPos = OldEntry->begin();
    for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
         I != E; ++I) {
      PHINode *PN = PHINode::Create(I->getType(),
                                    I->getName() + ".tr", InsertPos);
      I->replaceAllUsesWith(PN); // Everyone use the PHI node now!
      PN->addIncoming(I, NewEntry);
      ArgumentPHIs.push_back(PN);
    }
  }

  // If this function has self recursive calls in the tail position where some
  // are marked tail and some are not, only transform one flavor or another.  We
  // have to choose whether we move allocas in the entry block to the new entry
  // block or not, so we can't make a good choice for both.  NOTE: We could do
  // slightly better here in the case that the function has no entry block
  // allocas.
  if (TailCallsAreMarkedTail && !CI->isTailCall())
    return false;

  // Ok, now that we know we have a pseudo-entry block WITH all of the
  // required PHI nodes, add entries into the PHI node for the actual
  // parameters passed into the tail-recursive call.
  for (unsigned i = 0, e = CI->getNumOperands()-1; i != e; ++i)
    ArgumentPHIs[i]->addIncoming(CI->getOperand(i+1), BB);

  // If we are introducing an accumulator variable to eliminate the recursion,
  // do so now.  Note that we _know_ that no subsequent tail recursion
  // eliminations will happen on this function because of the way the
  // accumulator recursion predicate is set up.
  //
  if (AccumulatorRecursionEliminationInitVal) {
    Instruction *AccRecInstr = AccumulatorRecursionInstr;
    // Start by inserting a new PHI node for the accumulator.
    PHINode *AccPN = PHINode::Create(AccRecInstr->getType(), "accumulator.tr",
                                     OldEntry->begin());

    // Loop over all of the predecessors of the tail recursion block.  For the
    // real entry into the function we seed the PHI with the initial value,
    // computed earlier.  For any other existing branches to this block (due to
    // other tail recursions eliminated) the accumulator is not modified.
    // Because we haven't added the branch in the current block to OldEntry yet,
    // it will not show up as a predecessor.
    for (pred_iterator PI = pred_begin(OldEntry), PE = pred_end(OldEntry);
         PI != PE; ++PI) {
      if (*PI == &F->getEntryBlock())
        AccPN->addIncoming(AccumulatorRecursionEliminationInitVal, *PI);
      else
        AccPN->addIncoming(AccPN, *PI);
    }

    // Add an incoming argument for the current block, which is computed by our
    // associative accumulator instruction.
    AccPN->addIncoming(AccRecInstr, BB);

    // Next, rewrite the accumulator recursion instruction so that it does not
    // use the result of the call anymore, instead, use the PHI node we just
    // inserted.
    AccRecInstr->setOperand(AccRecInstr->getOperand(0) != CI, AccPN);

    // Finally, rewrite any return instructions in the program to return the PHI
    // node instead of the "initval" that they do currently.  This loop will
    // actually rewrite the return value we are destroying, but that's ok.
    for (Function::iterator BBI = F->begin(), E = F->end(); BBI != E; ++BBI)
      if (ReturnInst *RI = dyn_cast<ReturnInst>(BBI->getTerminator()))
        RI->setOperand(0, AccPN);
    ++NumAccumAdded;
  }

  // Now that all of the PHI nodes are in place, remove the call and
  // ret instructions, replacing them with an unconditional branch.
  BranchInst::Create(OldEntry, Ret);
  BB->getInstList().erase(Ret);  // Remove return.
  BB->getInstList().erase(CI);   // Remove call.
  ++NumEliminated;
  return true;
}