Example #1
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);
}
/// performLocalRetainMotion - Scan forward from the specified retain, moving it
/// later in the function if possible, over instructions that provably can't
/// release the object.  If we get to a release of the object, zap both.
///
/// NOTE: this handles both objc_retain and swift_retain.
///
static bool performLocalRetainMotion(CallInst &Retain, BasicBlock &BB,
                                     SwiftRCIdentity *RC) {
  // FIXME: Call classifier should identify the object for us.  Too bad C++
  // doesn't have nice Swift-style enums.
  Value *RetainedObject = RC->getSwiftRCIdentityRoot(Retain.getArgOperand(0));

  BasicBlock::iterator BBI = Retain.getIterator(),
                       BBE = BB.getTerminator()->getIterator();

  bool isObjCRetain = Retain.getCalledFunction()->getName() == "objc_retain";

  bool MadeProgress = false;

  // Scan until we get to the end of the block.
  for (++BBI; BBI != BBE; ++BBI) {
    Instruction &CurInst = *BBI;

    // Classify the instruction. This switch does a "break" when the instruction
    // can be skipped and is interesting, and a "continue" when it is a retain
    // of the same pointer.
    switch (classifyInstruction(CurInst)) {
    // These instructions should not reach here based on the pass ordering.
    // i.e. LLVMARCOpt -> LLVMContractOpt.
    case RT_RetainN:
    case RT_UnknownRetainN:
    case RT_BridgeRetainN:
    case RT_ReleaseN:
    case RT_UnknownReleaseN:
    case RT_BridgeReleaseN:
        llvm_unreachable("These are only created by LLVMARCContract !");
    case RT_NoMemoryAccessed:
    case RT_AllocObject:
    case RT_CheckUnowned:
      // Skip over random instructions that don't touch memory.  They don't need
      // protection by retain/release.
      break;

    case RT_FixLifetime: // This only stops release motion. Retains can move over it.
      break;

    case RT_Retain:
    case RT_UnknownRetain:
    case RT_BridgeRetain:
    case RT_RetainUnowned:
    case RT_ObjCRetain: {  // swift_retain(obj)
      //CallInst &ThisRetain = cast<CallInst>(CurInst);
      //Value *ThisRetainedObject = ThisRetain.getArgOperand(0);

      // If we see a retain of the same object, we can skip over it, but we
      // can't count it as progress.  Just pushing a retain(x) past a retain(y)
      // doesn't change the program.
      continue;
    }


    case RT_UnknownRelease:
    case RT_BridgeRelease:
    case RT_ObjCRelease:
    case RT_Release: {
      // If we get to a release that is provably to this object, then we can zap
      // it and the retain.
      CallInst &ThisRelease = cast<CallInst>(CurInst);
      Value *ThisReleasedObject = ThisRelease.getArgOperand(0);
      ThisReleasedObject = RC->getSwiftRCIdentityRoot(ThisReleasedObject);
      if (ThisReleasedObject == RetainedObject) {
        Retain.eraseFromParent();
        ThisRelease.eraseFromParent();
        if (isObjCRetain) {
          ++NumObjCRetainReleasePairs;
        } else {
          ++NumRetainReleasePairs;
        }
        return true;
      }

      // Otherwise, if this is some other pointer, we can only ignore it if we
      // can prove that the two objects don't alias.
      // Retain.dump(); ThisRelease.dump(); BB.getParent()->dump();
      goto OutOfLoop;
    }

    case RT_Unknown:
      // Loads cannot affect the retain.
      if (isa<LoadInst>(CurInst))
        continue;

      // Load, store, memcpy etc can't do a release.
      if (isa<LoadInst>(CurInst) || isa<StoreInst>(CurInst) ||
          isa<MemIntrinsic>(CurInst))
        break;

      // CurInst->dump(); BBI->dump();
      // Otherwise, we get to something unknown/unhandled.  Bail out for now.
      goto OutOfLoop;
    }

    // If the switch did a break, we made some progress moving this retain.
    MadeProgress = true;
  }
OutOfLoop:

  // If we were able to move the retain down, move it now.
  // TODO: This is where we'd plug in some global algorithms someday.
  if (MadeProgress) {
    Retain.moveBefore(&*BBI);
    return true;
  }

  return false;
}
Example #3
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;
}
/// performLocalReleaseMotion - Scan backwards from the specified release,
/// moving it earlier in the function if possible, over instructions that do not
/// access the released object.  If we get to a retain or allocation of the
/// object, zap both.
static bool performLocalReleaseMotion(CallInst &Release, BasicBlock &BB,
                                      SwiftRCIdentity *RC) {
  // FIXME: Call classifier should identify the object for us.  Too bad C++
  // doesn't have nice Swift-style enums.
  Value *ReleasedObject = RC->getSwiftRCIdentityRoot(Release.getArgOperand(0));

  BasicBlock::iterator BBI = Release.getIterator();

  // Scan until we get to the top of the block.
  while (BBI != BB.begin()) {
    --BBI;

    // Don't analyze PHI nodes.  We can't move retains before them and they
    // aren't "interesting".
    if (isa<PHINode>(BBI) ||
        // If we found the instruction that defines the value we're releasing,
        // don't push the release past it.
        &*BBI == Release.getArgOperand(0)) {
      ++BBI;
      goto OutOfLoop;
    }

    switch (classifyInstruction(*BBI)) {
    // These instructions should not reach here based on the pass ordering.
    // i.e. LLVMARCOpt -> LLVMContractOpt.
    case RT_UnknownRetainN:
    case RT_BridgeRetainN:
    case RT_RetainN:
    case RT_UnknownReleaseN:
    case RT_BridgeReleaseN:
    case RT_ReleaseN:
        llvm_unreachable("These are only created by LLVMARCContract !");
    case RT_NoMemoryAccessed:
      // Skip over random instructions that don't touch memory.  They don't need
      // protection by retain/release.
      continue;

    case RT_UnknownRelease:
    case RT_BridgeRelease:
    case RT_ObjCRelease:
    case RT_Release: {
      // If we get to a release, we can generally ignore it and scan past it.
      // However, if we get to a release of obviously the same object, we stop
      // scanning here because it should have already be moved as early as
      // possible, so there is no reason to move its friend to the same place.
      //
      // NOTE: If this occurs frequently, maybe we can have a release(Obj, N)
      // API to drop multiple retain counts at once.
      CallInst &ThisRelease = cast<CallInst>(*BBI);
      Value *ThisReleasedObject = ThisRelease.getArgOperand(0);
      ThisReleasedObject = RC->getSwiftRCIdentityRoot(ThisReleasedObject);
      if (ThisReleasedObject == ReleasedObject) {
        //Release.dump(); ThisRelease.dump(); BB.getParent()->dump();
        ++BBI;
        goto OutOfLoop;
      }
      continue;
    }

    case RT_UnknownRetain:
    case RT_BridgeRetain:
    case RT_ObjCRetain:
    case RT_Retain: {  // swift_retain(obj)
      CallInst &Retain = cast<CallInst>(*BBI);
      Value *RetainedObject = Retain.getArgOperand(0);
      RetainedObject = RC->getSwiftRCIdentityRoot(RetainedObject);

      // Since we canonicalized earlier, we know that if our retain has any
      // uses, they were replaced already. This assertion documents this
      // assumption.
      assert(Retain.use_empty() && "Retain should have been canonicalized to "
             "have no uses.");

      // If the retain and release are to obviously pointer-equal objects, then
      // we can delete both of them.  We have proven that they do not protect
      // anything of value.
      if (RetainedObject == ReleasedObject) {
        Retain.eraseFromParent();
        Release.eraseFromParent();
        ++NumRetainReleasePairs;
        return true;
      }

      // Otherwise, this is a retain of an object that is not statically known
      // to be the same object.  It may still be dynamically the same object
      // though.  In this case, we can't move the release past it.
      // TODO: Strengthen analysis.
      //Release.dump(); ThisRelease.dump(); BB.getParent()->dump();
     ++BBI;
      goto OutOfLoop;
    }

    case RT_AllocObject: {   // %obj = swift_alloc(...)
      CallInst &Allocation = cast<CallInst>(*BBI);

      // If this is an allocation of an unrelated object, just ignore it.
      // TODO: This is not safe without proving the object being released is not
      // related to the allocated object.  Consider something silly like this:
      //   A = allocate()
      //   B = bitcast A to object
      //   release(B)
      if (ReleasedObject != &Allocation) {
        // Release.dump(); BB.getParent()->dump();
        ++BBI;
        goto OutOfLoop;
      }

      // If this is a release right after an allocation of the object, then we
      // can zap both.
      Allocation.replaceAllUsesWith(UndefValue::get(Allocation.getType()));
      Allocation.eraseFromParent();
      Release.eraseFromParent();
      ++NumAllocateReleasePairs;
      return true;
    }

    case RT_FixLifetime:
    case RT_RetainUnowned:
    case RT_CheckUnowned:
    case RT_Unknown:
      // Otherwise, we have reached something that we do not understand. Do not
      // attempt to shorten the lifetime of this object beyond this point so we
      // are conservative.
      ++BBI;
      goto OutOfLoop;
    }
  }
OutOfLoop:


  // If we got to the top of the block, (and if the instruction didn't start
  // there) move the release to the top of the block.
  // TODO: This is where we'd plug in some global algorithms someday.
  if (&*BBI != &Release) {
    Release.moveBefore(&*BBI);
    return true;
  }

  return false;
}