/// <summary>
/// It visits an individual statement. It is called from VisitBlock.
///
/// It calls NonNullInstructionVisitor
/// </summary>
/// <param name="block"></param>
/// <param name="statement"></param>
/// <param name="dfstate"></param>
/// <returns></returns>
protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate)
{
// For debug purpose
if (Analyzer.Debug)
{
try{
Analyzer.WriteLine("\n:::" + new SampleInstructionVisitor().Visit(statement, null) + " ::: " + statement.SourceContext.SourceText);
}catch (Exception e) {
Analyzer.WriteLine("Print error: " + statement + ": " + e.Message);
}
}
IDataFlowState result = null;
try{
result = (IDataFlowState)(iVisitor.Visit(statement, dfstate));
}catch (Exception e) {
typeSystem.HandleError(statement, Cci.Error.InternalCompilerError, ":NonNull:" + e.Message);
Console.WriteLine(e.StackTrace);
}
if (result != null && Analyzer.Debug)
{
result.Dump();
}
return(result);
}
/// <summary>
/// It split exceptions for current handler and the next chained handler.
///
/// It will:
///
/// If the exception is completely intercepted by current handler, the
/// exception will be consumed.
///
/// If the exception caught but not completely, both current handler and
/// the next handler will take the states.
///
/// If the exception is irrelevant to current caught, the next handler
/// will take over the state. Current handler is then bypassed.
/// </summary>
/// <param name="handler"></param>
/// <param name="currentHandlerState"></param>
/// <param name="nextHandlerState"></param>
protected override void SplitExceptions(CfgBlock handler, ref IDataFlowState currentHandlerState, out IDataFlowState nextHandlerState)
{
Debug.Assert(currentHandlerState != null, "Internal error in NonNull Analysis");
ExposureState state = (ExposureState)currentHandlerState;
if (handler == null || handler.Length == 0)
{
nextHandlerState = null;
return;
}
if (handler[0] is Unwind)
{
nextHandlerState = null;
currentHandlerState = null;
return;
}
Debug.Assert(handler[0] is Catch, "Exception Handler does not starts with Catch");
Debug.Assert(state.currentException != null, "No current exception to handle");
Catch c = (Catch)handler[0];
if (handler.ExceptionHandler != null &&
!state.currentException.IsAssignableTo(c.Type))
{
nextHandlerState = state;;
}
else
{
nextHandlerState = null;
}
// Compute what trickles through to the next handler
// and what sticks to this handler.
if (state.currentException.IsAssignableTo(c.Type))
{
// everything sticks
nextHandlerState = null;
}
else if (c.Type.IsAssignableTo(state.currentException))
{
// c sticks, rest goes to next handler
nextHandlerState = state;
// copy state to modify the currentException
state = new ExposureState(state);
state.currentException = c.Type;
currentHandlerState = state;
}
else
{
// nothing stick all goes to next handler
nextHandlerState = state;
currentHandlerState = null;
}
return;
}
/// <summary>
/// Merge the new pending state with the old pending states.
/// </summary>
/// <returns>merged pending state</returns>
private IDataFlowState JoinWithPendingState(CfgBlock prev, CfgBlock block, IDataFlowState newState)
{
if (Tracing)
{
Console.WriteLine("JoinWithPendingState: block {0} -> {1}",
(prev).UniqueKey,
(block).UniqueKey);
}
IDataFlowState pending = PendingState(block);
// note, we call Merge even if old is null.
bool changed;
bool precise;
if (Tracing)
{
SourceContext sc = (block).SourceContext;
if (sc.Document == null && block.Length > 0)
{
sc = ((Statement)block[0]).SourceContext;
}
Console.WriteLine("Join with pending state at line {0}", sc.StartLine);
}
IDataFlowState merged = this.Merge(prev, block, pending, newState, out changed, out precise);
if (Tracing)
{
Console.WriteLine("Join changed {0}", changed);
}
return(merged);
}
/// <summary>
/// Compute the join of two data flow states at the given block.
/// </summary>
/// <param name="previous">Predecessor block for this new state</param>
/// <param name="joinPoint">Block at which join is computed</param>
/// <param name="atMerge">Old state at this block. Can be null, in which case the incoming state
/// is the first non-bottom state. In this case, the method must set changed
/// <c>resultDiffersFromPreviousMerge</c> to true.</param>
/// <param name="incoming">New data flow state flowing to this block.</param>
/// <param name="resultDiffersFromPreviousMerge">Boolean for fix point. If the state after
/// the merge is equal to the old <c>atMerge</c> state, set to false, otherwise set to true.</param>
/// <param name="mergeIsPrecise">can be set to true if the merged result state strictly contains only
/// information representing either the atMerge or the incoming state, but no extra approximation. If
/// this information cannot be determined by the merge, it must return false. True can only be returned
/// if result is truly precise.</param>
/// <returns>The new merged state.</returns>
protected abstract IDataFlowState Merge(
CfgBlock previous,
CfgBlock joinPoint,
IDataFlowState atMerge,
IDataFlowState incoming,
out bool resultDiffersFromPreviousMerge,
out bool mergeIsPrecise
);
private void SetPendingState(CfgBlock block, IDataFlowState pending)
{
pendingStates[block.Index] = pending;
if (Tracing)
{
Console.WriteLine("SetPendingState: block {0}", (block).UniqueKey);
}
}
/// <summary>
/// Like PendingState returns the pending state for the given block, but
/// it also sets the pending state for this block to null.
/// </summary>
/// <returns>old pending state</returns>
private IDataFlowState PopPendingState(CfgBlock block)
{
IDataFlowState pending = pendingStates[block.Index];
pendingStates[block.Index] = null;
if (Tracing)
{
Console.WriteLine("PopPendingState: block {0}", (block).UniqueKey);
}
return(pending);
}
protected override IDataFlowState Merge(CfgBlock previous, CfgBlock joinPoint, IDataFlowState atMerge,
IDataFlowState incoming, out bool resultDiffersFromPreviousMerge, out bool mergeIsPrecise)
{
resultDiffersFromPreviousMerge = false;
mergeIsPrecise = true;
if (atMerge == null)
{
resultDiffersFromPreviousMerge = true;
}
atMerge = incoming;
return(atMerge);
}
/// <summary>
/// Add the given state to the pending states of the target block. If
/// the block is enabled (by the pending edge count optimization), add the
/// block to the worklist.
///
/// Inv: DoneState => PendingState /\ PendingState != null => InQueue
///
/// Cases:
/// 1. Done => new, nothing to do
/// 2. Done |_| new is precise. Pend' = Pend |_| new, Done' = Done |_| new
/// 3. Done |_| new is imprecise. Pend' = Done |_| new, Done' = Done |_| new
/// </summary>
public void PushState(
CfgBlock currentBlock,
CfgBlock nextBlock,
IDataFlowState state
)
{
if (Tracing)
{
Console.WriteLine("PushState: block {0} -> {1}",
(currentBlock).UniqueKey,
(nextBlock).UniqueKey);
}
// state == null signals that branch is infeasible
if (state == null)
{
return;
}
bool precise;
// Add state to done state
IDataFlowState stillPending = this.StateToReanalyzeBlock(currentBlock, nextBlock, state, out precise);
if (stillPending == null)
{
if (Tracing)
{
Console.WriteLine("PushState: block {0} no new information for pending state.",
(nextBlock).UniqueKey);
}
return;
}
if (precise)
{
// join stillPending to old pending.
stillPending = this.JoinWithPendingState(currentBlock, nextBlock, stillPending);
}
this.SetPendingState(nextBlock, stillPending);
// when dequeued, the pending state is what the block needs to be analyzed under.
//
joinWorkItems.Enqueue(nextBlock);
if (Tracing)
{
Console.WriteLine("PushState: block {0} put on work queue.",
(nextBlock).UniqueKey);
}
}
/// <summary>
/// Default per block visitor. Called from Run.
///
/// It calls VisitStatement on each statement in a block.
///
/// The result of this method is used as the state for all normal control flow successors.
/// To push state onto an exception handler, use the PushExceptionState method. Furthermore, for
/// conditional branches, different states can be pushed onto the true and false branches directly
/// by calling PushPending. In that case, null should be returned from the method in order to avoid pushing
/// the returned state onto both true and false targets again.
/// </summary>
protected virtual IDataFlowState VisitBlock(CfgBlock block, IDataFlowState stateOnEntry)
{
IDataFlowState currentState = stateOnEntry;
for (int i = 0; i < block.Length; i++)
{
if (currentState == null)
{
return(null);
}
currentState = this.VisitStatement(block, (Statement)block[i], currentState);
}
return(currentState);
}
protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate) {
// For debug purpose
try{
Analyzer.WriteLine(new SampleInstructionVisitor().Visit(statement,null)+" ::: " +statement.SourceContext.SourceText);
}catch(Exception){
Analyzer.WriteLine("Print error: "+statement);
}
IDataFlowState result=null;
try{
result =(IDataFlowState)(iVisitor.Visit(statement,dfstate));
}catch(ModifiesException e){
typeSystem.HandleError(statement,System.Compiler.Error.Warning,":"+e.Message);
}catch(Exception e){
typeSystem.HandleError(statement,System.Compiler.Error.Warning,":CFG1:"+e.Message);
}
Analyzer.WriteLine(dfstate);
return dfstate;
}
protected override IDataFlowState VisitBlock(CfgBlock block, IDataFlowState stateOnEntry) {
Debug.Assert(block!=null);
currentBlock=block;
Analyzer.Write("---------block: "+block.UniqueId+";");
Analyzer.Write(" Exit:");
foreach (CfgBlock b in block.NormalSuccessors)
Analyzer.Write(b.UniqueId+";");
if (block.UniqueSuccessor!=null)
Analyzer.Write(" FallThrough: "+block.UniqueSuccessor+";");
if (block.ExceptionHandler!=null)
Analyzer.Write(" ExHandler: "+block.ExceptionHandler.UniqueId+";");
Analyzer.WriteLine("");
NonNullables newState=new NonNullables(stateOnEntry);
if (block.ExceptionHandler!=null)
this.PushExceptionState(block,newState);
return base.VisitBlock (block, newState);
}
protected override IDataFlowState VisitBlock(CfgBlock block, IDataFlowState stateOnEntry)
{
IDataFlowState resultState = stateOnEntry;
IDataFlowState newState = new MyState();
if (block.ExceptionHandler != null)
{
this.PushExceptionState(block, newState);
}
resultState = base.VisitBlock(block, newState);
if (block.UniqueId == cfg.NormalExit.UniqueId)
{
}
if (block.UniqueId == cfg.ExceptionExit.UniqueId)
{
}
return(resultState);
}
/// <summary>
/// Starts the analysis at the first instruction of the given block
/// </summary>
protected virtual void Run(ControlFlowGraph cfg, CfgBlock startBlock, IDataFlowState startState)
{
this.Reinitialize(cfg);
pendingStates[startBlock.Index] = startState;
joinWorkItems.Enqueue(startBlock);
while (joinWorkItems.Count > 0)
{
//joinWorkItems.Dump();
CfgBlock currentBlock = joinWorkItems.Dequeue();
if (Analyzer.Debug)
{
Console.WriteLine("\n*** Working on block {0} [{1} statements, line {2}]\n",
((currentBlock).UniqueKey),
currentBlock.Length,
(currentBlock.Length == 0)? -1 : ((Statement)currentBlock[0]).SourceContext.StartLine);
}
// Flow the current state through the block.
IDataFlowState currentState = PopPendingState(currentBlock);
currentState = VisitBlock(currentBlock, currentState);
// NOTE: VisitBlock may have explicitly pushed states onto some successors. In that case
// it should return null to avoid this code pushing the same state onto all successors.
if (currentState != null)
{
foreach (CfgBlock succ in currentBlock.NormalSuccessors)
{
PushState(currentBlock, succ, currentState);
}
}
} //while
}
/// <summary>
/// Push the given state onto the handler of the block.
/// This causes call-backs to SplitException in order to correctly distribute
/// the exception state among different nested handlers.
/// </summary>
/// <param name="currentBlock">Block from which exception escapes</param>
/// <param name="state">state on exception flow</param>
public void PushExceptionState(
CfgBlock currentBlock,
IDataFlowState state
)
{
IDataFlowState currentHandlerState = state;
CfgBlock currentHandler = currentBlock;
IDataFlowState nextHandlerState;
while (currentHandlerState != null)
{
Debug.Assert(currentHandler.ExceptionHandler != null,
String.Format("block {0} does not have an exception handler",
(currentHandler).UniqueKey));
currentHandler = currentHandler.ExceptionHandler;
if (Tracing)
{
Console.WriteLine("PushExceptionState (in loop): block {0} -> {1}",
(currentBlock).UniqueKey,
(currentHandler).UniqueKey);
}
SplitExceptions(currentHandler, ref currentHandlerState, out nextHandlerState);
/// We allow SplitExceptions to make decisions about not propagating any exceptions
/// Debug.Assert(currentHandlerState != null || nextHandlerState != null);
if (currentHandlerState != null)
{
PushState(currentBlock, currentHandler, currentHandlerState);
}
currentHandlerState = nextHandlerState;
}
}
/// <summary>
/// Implementation of visit Block. It is called from run.
///
/// It calls VisitStatement.
/// </summary>
/// <param name="block"></param>
/// <param name="stateOnEntry"></param>
/// <returns></returns>
protected override IDataFlowState VisitBlock(CfgBlock block, IDataFlowState stateOnEntry)
{
Debug.Assert(block != null);
currBlock = block;
Analyzer.Write("---------block: " + block.UniqueId + ";");
Analyzer.Write(" Exit:");
foreach (CfgBlock b in block.NormalSuccessors)
{
Analyzer.Write(b.UniqueId + ";");
}
if (block.UniqueSuccessor != null)
{
Analyzer.Write(" FallThrough: " + block.UniqueSuccessor + ";");
}
if (block.ExceptionHandler != null)
{
Analyzer.Write(" ExHandler: " + block.ExceptionHandler.UniqueId + ";");
}
Analyzer.WriteLine("");
ExposureState newState;
if (stateOnEntry == null)
{
newState = new ExposureState(typeSystem);
}
else
{
newState = new ExposureState((ExposureState)stateOnEntry);
}
// if (block.ExceptionHandler!=null)
// this.PushExceptionState(block,newState);
return(base.VisitBlock(block, newState));
}
/// <summary>
/// Starts the analysis at the first instruction of the given block
/// </summary>
protected virtual void Run (ControlFlowGraph cfg, CfgBlock startBlock, IDataFlowState startState)
{
this.Reinitialize(cfg);
pendingStates[startBlock.Index] = startState;
joinWorkItems.Enqueue(startBlock);
while (joinWorkItems.Count > 0)
{
//joinWorkItems.Dump();
CfgBlock currentBlock = joinWorkItems.Dequeue();
if (Analyzer.Debug)
{
Console.WriteLine("\n*** Working on block {0} [{1} statements, line {2}]\n",
((currentBlock).UniqueKey),
currentBlock.Length,
(currentBlock.Length == 0)? -1 : ((Statement)currentBlock[0]).SourceContext.StartLine);
}
// Flow the current state through the block.
IDataFlowState currentState = PopPendingState(currentBlock);
currentState = VisitBlock(currentBlock, currentState);
// NOTE: VisitBlock may have explicitly pushed states onto some successors. In that case
// it should return null to avoid this code pushing the same state onto all successors.
if (currentState != null)
{
foreach (CfgBlock succ in currentBlock.NormalSuccessors)
{
PushState(currentBlock, succ, currentState);
}
}
} //while
}
/// <summary>
/// Visit the statement. It calls the instruction visitor to perform the transfer function
/// </summary>
/// <param name="block"></param>
/// <param name="statement"></param>
/// <param name="dfstate"></param>
/// <returns></returns>
protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate)
{
PointsToAndWriteEffects ptwe = (PointsToAndWriteEffects)dfstate;
// PointsToAndWriteEffects ptweOld = new PointsToAndWriteEffects(ptwe);
IDataFlowState res = base.VisitStatement(block, statement, dfstate);
return res;
}
/// <summary>
/// Compute the Dataflow analysis for the given method
/// Returns true if the method is pure
/// </summary>
/// <param name="method"></param>
/// <returns></returns>
public bool ComputePointsToStateFor(Method method)
{
// Get or compute the CFG
ControlFlowGraph cfg = pointsToStateAnalysys.GetCFG(method);
//if (PointsToAnalysis.debug)
// CodePrinter.PrintMethod(method);
PointsToState initialState = this.pointsToStateAnalysys.Factory.NewElement(method);
// If we can compute de CFG and the method is not unsafe
// We compute the dataflow analysis
if (cfg != null && !PointsToAnalysis.IsUnsafe(method))
{
ComputeBeforeDataflow(method);
this.Run(cfg, initialState);
if (exitState == null)
{
if (PointsToAnalysis.debug)
Console.WriteLine("Method {0} exitState NULL", method.GetFullUnmangledNameWithTypeParameters());
}
// FIX
PointsToState PointsToStateAtExit = (PointsToState)exitState;
ComputeAfterDataflow(method);
return true;
}
else
{
exitState = null;
return false;
}
}
/// <summary>
/// Merge the two states for current block.
/// </summary>
/// <param name="previous"></param>
/// <param name="joinPoint"></param>
/// <param name="atMerge"></param>
/// <param name="incoming"></param>
/// <param name="resultDiffersFromPreviousMerge"></param>
/// <param name="mergeIsPrecise"></param>
/// <returns></returns>
protected override IDataFlowState Merge(CfgBlock previous, CfgBlock joinPoint, IDataFlowState atMerge, IDataFlowState incoming, out bool resultDiffersFromPreviousMerge, out bool mergeIsPrecise)
{
mergeIsPrecise = false;
// No new states;
if (incoming == null)
{
resultDiffersFromPreviousMerge = false;
return(atMerge);
}
// Initialize states
if (atMerge == null)
{
resultDiffersFromPreviousMerge = true;
return(incoming);
}
if (Analyzer.Debug)
{
Console.WriteLine("Merge at Block {0}-----------------", (joinPoint).UniqueKey);
Console.WriteLine(" State at merge");
atMerge.Dump();
Console.WriteLine(" Incoming");
incoming.Dump();
}
// Merge the two.
ExposureState newState = ExposureState.Join((ExposureState)atMerge, (ExposureState)incoming, joinPoint);
if (newState != null)
{
if (Analyzer.Debug)
{
Console.WriteLine("\n Merged State");
newState.Dump();
}
resultDiffersFromPreviousMerge = true;
return(newState);
}
if (Analyzer.Debug)
{
Console.WriteLine("Merged state same as old.");
}
resultDiffersFromPreviousMerge = false;
return(atMerge);
}
protected override IDataFlowState VisitBlock(CfgBlock block, IDataFlowState stateOnEntry)
{
//if (IsInstrumentationCode(block))
// return stateOnEntry;
return(base.VisitBlock(block, stateOnEntry));
}
/// <summary>
/// Splits the exceptions into the ones that this handler will handle and the ones that should
/// <code>currentHandlerState</code> and <code>nextHandlerState</code> cannot both be null.
/// On exit, if <code>currentHandlerState</code> is null, <code>handler</code> handles no exceptions,
/// and if <code>nextHandlerState</code> is null, <code>handler</code> handles all the exceptions in
/// the initial exception set of <code>currentHandlerState</code>.
/// </summary>
// go on to the next handler. currentHandlerState and next
protected abstract void SplitExceptions(
CfgBlock handler,
ref IDataFlowState currentHandlerState, out IDataFlowState nextHandlerState
);
/// <summary>
/// Default per statement visitor called from the default VisitBlock.
/// Does identity transformation. Subclasses either override this method
/// if the default block handling is sufficient, or they override the Visit method for blocks.
///
/// The result of this method is used as the state for all normal control flow successors.
/// To push state onto an exception handler, use the PushExceptionState method. Furthermore, for
/// conditional branches, different states can be pushed onto the true and false branches directly
/// by calling PushPending. In that case, null should be returned from the method in order to avoid pushing
/// the returned state onto both true and false targets again.
/// </summary>
protected virtual IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate)
{
// simple case analysis to distinguish throws
switch (statement.NodeType)
{
case NodeType.Throw:
case NodeType.Rethrow:
{
PushExceptionState(block, dfstate);
return(null);
}
default:
return(dfstate);
}
}
/// <summary>
/// It visits an individual statement. It is called from VisitBlock.
///
/// It calls NonNullInstructionVisitor
/// </summary>
/// <param name="block"></param>
/// <param name="statement"></param>
/// <param name="dfstate"></param>
/// <returns></returns>
protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate) {
// For debug purpose
if (Analyzer.Debug) {
try{
Analyzer.WriteLine("\n:::"+new SampleInstructionVisitor().Visit(statement,null)+" ::: " +statement.SourceContext.SourceText);
}catch(Exception e){
Analyzer.WriteLine("Print error: "+statement+": "+e.Message);
}
}
IDataFlowState result=null;
try{
result =(IDataFlowState)(iVisitor.Visit(statement,dfstate));
}catch(Exception e){
typeSystem.HandleError(statement,Cci.Error.InternalCompilerError,":NonNull:"+e.Message);
Console.WriteLine(e.StackTrace);
}
if (result != null && Analyzer.Debug){
result.Dump();
}
return result;
}
/// <summary>
/// Implementation of visit Block. It is called from run.
///
/// It calls VisitStatement.
/// </summary>
/// <param name="block"></param>
/// <param name="stateOnEntry"></param>
/// <returns></returns>
protected override IDataFlowState VisitBlock(CfgBlock block, IDataFlowState stateOnEntry) {
Debug.Assert(block!=null);
currBlock=block;
Analyzer.Write("---------block: "+block.UniqueId+";");
Analyzer.Write(" Exit:");
foreach (CfgBlock b in block.NormalSuccessors)
Analyzer.Write(b.UniqueId+";");
if (block.UniqueSuccessor!=null)
Analyzer.Write(" FallThrough: "+block.UniqueSuccessor+";");
if (block.ExceptionHandler!=null)
Analyzer.Write(" ExHandler: "+block.ExceptionHandler.UniqueId+";");
Analyzer.WriteLine("");
ExposureState newState;
if(stateOnEntry==null)
newState=new ExposureState(typeSystem);
else
newState=new ExposureState((ExposureState)stateOnEntry);
// if (block.ExceptionHandler!=null)
// this.PushExceptionState(block,newState);
return base.VisitBlock (block, newState);
}
/// <summary>
/// Merge the two states for current block.
/// </summary>
/// <param name="previous"></param>
/// <param name="joinPoint"></param>
/// <param name="atMerge"></param>
/// <param name="incoming"></param>
/// <param name="resultDiffersFromPreviousMerge"></param>
/// <param name="mergeIsPrecise"></param>
/// <returns></returns>
protected override IDataFlowState Merge(CfgBlock previous, CfgBlock joinPoint, IDataFlowState atMerge, IDataFlowState incoming, out bool resultDiffersFromPreviousMerge, out bool mergeIsPrecise) {
mergeIsPrecise = false;
// No new states;
if(incoming==null) {
resultDiffersFromPreviousMerge = false;
return atMerge;
}
// Initialize states
if(atMerge==null){
resultDiffersFromPreviousMerge = true;
return incoming;
}
if (Analyzer.Debug) {
Console.WriteLine("Merge at Block {0}-----------------", (joinPoint).UniqueKey);
Console.WriteLine(" State at merge");
atMerge.Dump();
Console.WriteLine(" Incoming");
incoming.Dump();
}
// Merge the two.
ExposureState newState = ExposureState.Join((ExposureState)atMerge, (ExposureState)incoming, joinPoint);
if (newState != null) {
if (Analyzer.Debug) {
Console.WriteLine("\n Merged State");
newState.Dump();
}
resultDiffersFromPreviousMerge = true;
return newState;
}
if (Analyzer.Debug) {
Console.WriteLine("Merged state same as old.");
}
resultDiffersFromPreviousMerge = false;
return atMerge;
}
private void SetPendingState (CfgBlock block, IDataFlowState pending)
{
pendingStates[block.Index] = pending;
if (Tracing)
{
Console.WriteLine("SetPendingState: block {0}", (block).UniqueKey);
}
}
/// <summary> /// Splits the exceptions into the ones that this handler will handle and the ones that should /// <code>currentHandlerState</code> and <code>nextHandlerState</code> cannot both be null. /// On exit, if <code>currentHandlerState</code> is null, <code>handler</code> handles no exceptions, /// and if <code>nextHandlerState</code> is null, <code>handler</code> handles all the exceptions in /// the initial exception set of <code>currentHandlerState</code>. /// </summary> // go on to the next handler. currentHandlerState and next protected abstract void SplitExceptions ( CfgBlock handler, ref IDataFlowState currentHandlerState, out IDataFlowState nextHandlerState );
/// <summary> /// Compute the join of two data flow states at the given block. /// </summary> /// <param name="previous">Predecessor block for this new state</param> /// <param name="joinPoint">Block at which join is computed</param> /// <param name="atMerge">Old state at this block. Can be null, in which case the incoming state /// is the first non-bottom state. In this case, the method must set changed /// <c>resultDiffersFromPreviousMerge</c> to true.</param> /// <param name="incoming">New data flow state flowing to this block.</param> /// <param name="resultDiffersFromPreviousMerge">Boolean for fix point. If the state after /// the merge is equal to the old <c>atMerge</c> state, set to false, otherwise set to true.</param> /// <param name="mergeIsPrecise">can be set to true if the merged result state strictly contains only /// information representing either the atMerge or the incoming state, but no extra approximation. If /// this information cannot be determined by the merge, it must return false. True can only be returned /// if result is truly precise.</param> /// <returns>The new merged state.</returns> protected abstract IDataFlowState Merge ( CfgBlock previous, CfgBlock joinPoint, IDataFlowState atMerge, IDataFlowState incoming, out bool resultDiffersFromPreviousMerge, out bool mergeIsPrecise );
/// <summary>
/// Default per statement visitor called from the default VisitBlock.
/// Does identity transformation. Subclasses either override this method
/// if the default block handling is sufficient, or they override the Visit method for blocks.
///
/// The result of this method is used as the state for all normal control flow successors.
/// To push state onto an exception handler, use the PushExceptionState method. Furthermore, for
/// conditional branches, different states can be pushed onto the true and false branches directly
/// by calling PushPending. In that case, null should be returned from the method in order to avoid pushing
/// the returned state onto both true and false targets again.
/// </summary>
protected virtual IDataFlowState VisitStatement (CfgBlock block, Statement statement, IDataFlowState dfstate)
{
// simple case analysis to distinguish throws
switch (statement.NodeType)
{
case NodeType.Throw:
case NodeType.Rethrow:
{
PushExceptionState(block, dfstate);
return null;
}
default:
return dfstate;
}
}
/// <summary>
/// Default per block visitor. Called from Run.
///
/// It calls VisitStatement on each statement in a block.
///
/// The result of this method is used as the state for all normal control flow successors.
/// To push state onto an exception handler, use the PushExceptionState method. Furthermore, for
/// conditional branches, different states can be pushed onto the true and false branches directly
/// by calling PushPending. In that case, null should be returned from the method in order to avoid pushing
/// the returned state onto both true and false targets again.
/// </summary>
protected virtual IDataFlowState VisitBlock (CfgBlock block, IDataFlowState stateOnEntry)
{
IDataFlowState currentState = stateOnEntry;
for (int i=0; i<block.Length; i++)
{
if (currentState == null) return null;
currentState = this.VisitStatement(block, (Statement)block[i], currentState);
}
return currentState;
}
/// <summary>
/// Merge two cState
/// </summary>
/// <param name="previous"></param>
/// <param name="joinPoint"></param>
/// <param name="atMerge"></param>
/// <param name="incoming"></param>
/// <param name="resultDiffersFromPreviousMerge"></param>
/// <param name="mergeIsPrecise"></param>
/// <returns></returns>
protected override IDataFlowState Merge(CfgBlock previous, CfgBlock joinPoint, IDataFlowState atMerge,
IDataFlowState incoming, out bool resultDiffersFromPreviousMerge, out bool mergeIsPrecise)
{
resultDiffersFromPreviousMerge = false;
mergeIsPrecise = false;
// No new states;
if (incoming == null)
return atMerge;
// Initialize states
if (atMerge == null)
{
resultDiffersFromPreviousMerge = true;
return incoming;
}
//if (((PointsToState )atMerge).Equals(incoming))
// return atMerge;
if (((PointsToState)atMerge).Includes((PointsToState)incoming))
return atMerge;
// Merge the two.
PointsToState newState = ((PointsToState)atMerge).Copy();
newState.Join((PointsToState)incoming);
//if( newState.Method.FullName.StartsWith("System.Runtime.Remoting.Lifetime.Lease.ProcessNextSponsor"))
//{
// PointsToState oldResult = (PointsToState)incoming;
// PointsToState newResult = newState;
// Console.Out.WriteLine("DIFERENCE a vs b");
// oldResult.PointsToGraph.DumpDifference(newResult.PointsToGraph);
// Console.Out.WriteLine("DIFERENCE b vs a");
// newResult.PointsToGraph.DumpDifference(oldResult.PointsToGraph);
//}
resultDiffersFromPreviousMerge = true;
return newState;
}
/// <summary>
/// It split exceptions for current handler and the next chained handler.
///
/// It will:
///
/// If the exception is completely intercepted by current handler, the
/// exception will be consumed.
///
/// If the exception caught but not completely, both current handler and
/// the next handler will take the states.
///
/// If the exception is irrelevant to current caught, the next handler
/// will take over the state. Current handler is then bypassed.
/// </summary>
/// <param name="handler"></param>
/// <param name="currentHandlerState"></param>
/// <param name="nextHandlerState"></param>
protected override void SplitExceptions(CfgBlock handler, ref IDataFlowState currentHandlerState, out IDataFlowState nextHandlerState) {
Debug.Assert(currentHandlerState!=null,"Internal error in NonNull Analysis");
ExposureState state = (ExposureState)currentHandlerState;
if(handler==null || handler.Length==0){
nextHandlerState=null;
return;
}
if(handler[0] is Unwind){
nextHandlerState=null;
currentHandlerState=null;
return;
}
Debug.Assert(handler[0] is Catch, "Exception Handler does not starts with Catch");
Debug.Assert(state.currentException!=null,"No current exception to handle");
Catch c=(Catch)handler[0];
if(handler.ExceptionHandler!=null &&
!state.currentException.IsAssignableTo(c.Type)) {
nextHandlerState = state;;
}
else {
nextHandlerState=null;
}
// Compute what trickles through to the next handler
// and what sticks to this handler.
if(state.currentException.IsAssignableTo(c.Type)) {
// everything sticks
nextHandlerState = null;
}
else if (c.Type.IsAssignableTo(state.currentException)) {
// c sticks, rest goes to next handler
nextHandlerState = state;
// copy state to modify the currentException
state = new ExposureState(state);
state.currentException = c.Type;
currentHandlerState = state;
}else {
// nothing stick all goes to next handler
nextHandlerState = state;
currentHandlerState = null;
}
return;
}
/// <summary>
/// Visit the statement. It calls the instruction visitor to perform the transfer function
/// </summary>
/// <param name="block"></param>
/// <param name="statement"></param>
/// <param name="dfstate"></param>
/// <returns></returns>
protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate)
{
if (PointsToAnalysis.debug)
{
Console.Out.WriteLine("Before: {0} ({1}) {2}", CodePrinter.StatementToString(statement),
statement.SourceContext.StartLine, statement.GetType());
dfstate.Dump();
}
PointsToState currentState = dfstate as PointsToState;
/*
if (PointsToAnalysis.IsCompilerGenerated(currentState.Method))
if (!this.pointsToStateAnalysys.enclosingState.ContainsKey(currentState.Method.DeclaringType))
return currentState;
*/
if (PointsToAnalysis.verbose)
{
iterationsCounter++;
if (iterationsCounter % 5000 == 0)
{
Console.Out.WriteLine("Counter: {3} {4} {0} ({1}) {2}", CodePrinter.StatementToString(statement),
statement.SourceContext.StartLine, statement.GetType(), iterationsCounter, currentState.Method.FullName);
dfstate.Dump();
}
}
//if (CodePrinter.StatementToString(statement).Contains("return value := this.f"))
// System.Diagnostics.Debugger.Break();
IDataFlowState result = (IDataFlowState)currentState;
// For Debug...
if (currentState.Method.Name.Name.Equals("Push"))
{ }
// If there are too many calls to non analyzable methods
// starts to ignore the statements
// if (!pointsToStateAnalysys.BoogieMode || currentState.CallsToNonAnalyzable.Count < pointsToStateAnalysys.maxCallToNonAnalyzable)
if (HasToVisit(currentState))
result = (IDataFlowState)(iVisitor.Visit(statement, dfstate));
if (PointsToAnalysis.debug)
{
Console.Out.WriteLine("After: {0} ({1})", CodePrinter.StatementToString(statement), statement.SourceContext.StartLine);
dfstate.Dump();
}
//return dfstate;
return result;
}
/// <summary>
/// Merge the new pending state with the old pending states.
/// </summary>
/// <returns>merged pending state</returns>
private IDataFlowState JoinWithPendingState (CfgBlock prev, CfgBlock block, IDataFlowState newState)
{
if (Tracing)
{
Console.WriteLine("JoinWithPendingState: block {0} -> {1}",
(prev).UniqueKey,
(block).UniqueKey);
}
IDataFlowState pending = PendingState(block);
// note, we call Merge even if old is null.
bool changed;
bool precise;
if (Tracing) {
SourceContext sc = (block).SourceContext;
if (sc.Document == null && block.Length > 0) {
sc = ((Statement)block[0]).SourceContext;
}
Console.WriteLine("Join with pending state at line {0}", sc.StartLine);
}
IDataFlowState merged = this.Merge(prev, block, pending, newState, out changed, out precise);
if (Tracing) {
Console.WriteLine("Join changed {0}", changed);
}
return merged;
}
// Visit the block in the CFG
protected override IDataFlowState VisitBlock(CfgBlock block, IDataFlowState stateOnEntry)
{
IDataFlowState resultState = stateOnEntry;
Debug.Assert(block != null);
currBlock = block;
Analyzer.Write("---------block: " + block.UniqueId + ";");
Analyzer.Write(" Exit:");
foreach (CfgBlock b in block.NormalSuccessors)
Analyzer.Write(b.UniqueId + ";");
if (block.UniqueSuccessor != null)
Analyzer.Write(" FallThrough: " + block.UniqueSuccessor + ";");
if (block.ExceptionHandler != null)
Analyzer.Write(" ExHandler: " + block.ExceptionHandler.UniqueId + ";");
Analyzer.WriteLine("");
PointsToState newState = ((PointsToState)stateOnEntry).Copy();
// If there are too many calls to non analyzable methods
// starts to ignore the statements
//if (!pointsToStateAnalysys.BoogieMode ||
// newState.CallsToNonAnalyzable.Count < pointsToStateAnalysys.maxCallToNonAnalyzable)
if (HasToVisit(newState))
{
if (block.ExceptionHandler != null)
this.PushExceptionState(block, newState);
resultState = base.VisitBlock(block, newState);
}
if (block.UniqueId == cfg.NormalExit.UniqueId)
{
exitState = resultState;
}
if (block.UniqueId == cfg.ExceptionExit.UniqueId)
{
exitState = resultState;
}
return resultState;
}
/// <summary>
/// Record the incoming status's sets of created and committed NN Arrays.
/// </summary>
/// <param name="block"></param>
/// <param name="statement"></param>
/// <param name="dfstate"></param>
/// <returns></returns>
protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate) {
//IDataFlowState result = base.VisitStatement(block, statement, dfstate);
table[statement.UniqueKey] = (dfstate as NNArrayStatus).CreatedButNotInitedArrays();
tableCommitted[statement.UniqueKey] = (dfstate as NNArrayStatus).CommittedArrays();
IDataFlowState result = null;
//try {
result = (IDataFlowState)(iVisitor.Visit(statement, dfstate));
if (Analyzer.Debug && result != null) {
result.Dump();
}
//}
//catch (Exception e) {
// this.TypeSystem.HandleError(statement, Error.InternalCompilerError, "NNArray Pre Analysis " + e.Message);
//}
return result;
}
protected override IDataFlowState Merge(CfgBlock previous, CfgBlock joinPoint, IDataFlowState atMerge, IDataFlowState incoming, out bool resultDiffersFromPreviousMerge, out bool mergeIsPrecise)
{
if (nonNullInfo != null)
{
INonNullState nns = nonNullInfo.OnEdge(previous, joinPoint);
if (nns == null && atMerge != null)
{
incoming = null;
}
}
return(base.Merge(previous, joinPoint, atMerge, incoming, out resultDiffersFromPreviousMerge, out mergeIsPrecise));
}
/// <summary>
/// Push the given state onto the handler of the block.
/// This causes call-backs to SplitException in order to correctly distribute
/// the exception state among different nested handlers.
/// </summary>
/// <param name="currentBlock">Block from which exception escapes</param>
/// <param name="state">state on exception flow</param>
public void PushExceptionState (
CfgBlock currentBlock,
IDataFlowState state
)
{
IDataFlowState currentHandlerState = state;
CfgBlock currentHandler = currentBlock;
IDataFlowState nextHandlerState;
while (currentHandlerState != null)
{
Debug.Assert(currentHandler.ExceptionHandler != null,
String.Format("block {0} does not have an exception handler",
(currentHandler).UniqueKey));
currentHandler = currentHandler.ExceptionHandler;
if (Tracing)
{
Console.WriteLine("PushExceptionState (in loop): block {0} -> {1}",
(currentBlock).UniqueKey,
(currentHandler).UniqueKey);
}
SplitExceptions(currentHandler, ref currentHandlerState, out nextHandlerState);
/// We allow SplitExceptions to make decisions about not propagating any exceptions
/// Debug.Assert(currentHandlerState != null || nextHandlerState != null);
if (currentHandlerState != null)
{
PushState(currentBlock, currentHandler, currentHandlerState);
}
currentHandlerState = nextHandlerState;
}
}
/// <summary>
/// Starts the analysis from the entry block of the CFG
/// </summary>
protected virtual void Run(ControlFlowGraph cfg, IDataFlowState startState)
{
this.Run(cfg, cfg.Entry, startState);
}
protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate)
{
// For debug purpose
if (Analyzer.Debug)
{
try
{
Analyzer.WriteLine(new SampleInstructionVisitor().Visit(statement, null) + " ::: " + statement.SourceContext.SourceText);
}
catch (Exception)
{
Analyzer.WriteLine("Print error: " + statement);
}
}
IDataFlowState result=null;
try{
result =(IDataFlowState)(iVisitor.Visit(statement,dfstate));
if (Analyzer.Debug && result != null) {
result.Dump();
}
}catch(Exception e){
typeSystem.HandleError(statement,Error.InternalCompilerError,"Definite Assignement: "+e.Message);
}
return result;
}
/// <summary>
/// Merge two PtWe
/// </summary>
/// <param name="previous"></param>
/// <param name="joinPoint"></param>
/// <param name="atMerge"></param>
/// <param name="incoming"></param>
/// <param name="resultDiffersFromPreviousMerge"></param>
/// <param name="mergeIsPrecise"></param>
/// <returns></returns>
protected override IDataFlowState Merge(CfgBlock previous, CfgBlock joinPoint, IDataFlowState atMerge,
IDataFlowState incoming, out bool resultDiffersFromPreviousMerge, out bool mergeIsPrecise)
{
return base.Merge(previous,joinPoint,atMerge,incoming,out resultDiffersFromPreviousMerge, out mergeIsPrecise);
}
protected override void Run(ControlFlowGraph cfg, IDataFlowState startState) {
base.Run(cfg, startState);
}
protected override void SplitExceptions(CfgBlock handler, ref IDataFlowState currentHandlerState,
out IDataFlowState nextHandlerState)
{
nextHandlerState = null;
}
/// <summary>
/// Starts the analysis from the entry block of the CFG
/// </summary>
protected virtual void Run (ControlFlowGraph cfg, IDataFlowState startState)
{
this.Run(cfg, cfg.Entry, startState);
}
/// <summary>
/// Visit the statement. It calls the instruction visitor to perform the transfer function
/// </summary>
/// <param name="block"></param>
/// <param name="statement"></param>
/// <param name="dfstate"></param>
/// <returns></returns>
protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate)
{
IDataFlowState result = (IDataFlowState)(iVisitor.Visit(statement, dfstate));
return(result);
}
/// <summary>
/// Add the given state to the pending states of the target block. If
/// the block is enabled (by the pending edge count optimization), add the
/// block to the worklist.
///
/// Inv: DoneState => PendingState /\ PendingState != null => InQueue
///
/// Cases:
/// 1. Done => new, nothing to do
/// 2. Done |_| new is precise. Pend' = Pend |_| new, Done' = Done |_| new
/// 3. Done |_| new is imprecise. Pend' = Done |_| new, Done' = Done |_| new
/// </summary>
public void PushState (
CfgBlock currentBlock,
CfgBlock nextBlock,
IDataFlowState state
)
{
if (Tracing)
{
Console.WriteLine("PushState: block {0} -> {1}",
(currentBlock).UniqueKey,
(nextBlock).UniqueKey);
}
// state == null signals that branch is infeasible
if (state == null)
{
return;
}
bool precise;
// Add state to done state
IDataFlowState stillPending = this.StateToReanalyzeBlock(currentBlock, nextBlock, state, out precise);
if (stillPending == null)
{
if (Tracing)
{
Console.WriteLine("PushState: block {0} no new information for pending state.",
(nextBlock).UniqueKey);
}
return;
}
if (precise)
{
// join stillPending to old pending.
stillPending = this.JoinWithPendingState(currentBlock, nextBlock, stillPending);
}
this.SetPendingState (nextBlock, stillPending);
// when dequeued, the pending state is what the block needs to be analyzed under.
//
joinWorkItems.Enqueue(nextBlock);
if (Tracing)
{
Console.WriteLine("PushState: block {0} put on work queue.",
(nextBlock).UniqueKey);
}
}
/// <summary>
/// merge the two state atMerge and incoming.
/// </summary>
/// <param name="previous"></param>
/// <param name="joinPoint"></param>
/// <param name="atMerge"></param>
/// <param name="incoming"></param>
/// <param name="resultDiffersFromPreviousMerge"></param>
/// <param name="mergeIsPrecise"></param>
/// <returns></returns>
protected override IDataFlowState Merge(CfgBlock previous, CfgBlock joinPoint, IDataFlowState atMerge, IDataFlowState incoming, out bool resultDiffersFromPreviousMerge, out bool mergeIsPrecise) {
resultDiffersFromPreviousMerge = false;
mergeIsPrecise = false;
// No new states;
if (incoming == null)
return atMerge;
// Initialize states
if (atMerge == null) {
resultDiffersFromPreviousMerge = true;
//
//((NNArrayStatus)incoming).FilterStackAndTemporaryLocals(joinPoint.StackDepth);
return incoming;
}
if (Analyzer.Debug ) {
Console.WriteLine("Array Reachable Def merge at block {0}", (joinPoint).UniqueKey);
Console.WriteLine("atMerge:\n---------");
atMerge.Dump();
Console.WriteLine("incoming:\n---------");
incoming.Dump();
}
// Merge the two.
NNArrayStatus newState = NNArrayStatus.Merge((NNArrayStatus)atMerge, (NNArrayStatus)incoming, joinPoint);
if (newState == null) {
if (Analyzer.Debug) {
Console.WriteLine("result UNchanged");
}
return atMerge;
}
resultDiffersFromPreviousMerge = true;
if (Analyzer.Debug) {
Console.WriteLine("Result of merge\n---------");
newState.Dump();
}
return newState;
}
// Exception management
internal void PushExceptionWrapper(IDataFlowState state)
{
this.PushExceptionState(currBlock, state);
}
protected override IDataFlowState VisitBlock(CfgBlock block, IDataFlowState state) {
Debug.Assert(block != null);
NNArrayStatus onEntry = (NNArrayStatus)state;
currBlock = block;
if (Analyzer.Debug) {
Analyzer.Write("---------block: " + block.UniqueId + ";");
Analyzer.Write(" Exit:");
foreach (CfgBlock b in block.NormalSuccessors)
Analyzer.Write(b.UniqueId + ";");
if (block.UniqueSuccessor != null)
Analyzer.Write(" FallThrough: " + block.UniqueSuccessor + ";");
if (block.ExceptionHandler != null)
Analyzer.Write(" ExHandler: " + block.ExceptionHandler.UniqueId + ";");
Analyzer.WriteLine("");
state.Dump();
}
if (block.ExceptionHandler != null) {
NNArrayStatus exnState = onEntry;
onEntry = new NNArrayStatus(onEntry); // Copy state, since common ancestor cannot be modified any longer
PushExceptionState(block, exnState);
}
NNArrayStatus resultState = (NNArrayStatus)base.VisitBlock(block, onEntry);
if (block.UniqueId == cfg.NormalExit.UniqueId) {
exitState = resultState;
}
if (resultState == null) {
return null;
}
return new NNArrayStatus(resultState);
}
/// <summary>
/// Checks if a block needs to be reanalyzed and under what state.
///
/// Updates the doneState of this block to reflect the pending state
/// </summary>
/// <returns>null if no reanalysis necessary, the DFS state if the merge is precise,
/// the merged state if the merge is imprecise
/// </returns>
private IDataFlowState StateToReanalyzeBlock (CfgBlock prev, CfgBlock block, IDataFlowState pending, out bool preciseMerge) {
IDataFlowState done = DoneState(block);
// note, we call Merge even if old is null.
bool changed;
if (Tracing) {
Console.WriteLine("StateToReanalyzeBlock: block {0} -> {1}",
(prev).UniqueKey,
(block).UniqueKey);
SourceContext sc = (block).SourceContext;
if (sc.Document == null && block.Length > 0) {
sc = ((Statement)block[0]).SourceContext;
}
Console.WriteLine("StateToReanalyzeBlock at line {0}", sc.StartLine);
}
IDataFlowState merged = this.Merge(prev, block, done, pending, out changed, out preciseMerge);
if (merged != null)
doneStates[block.Index] = merged;
if ( ! changed ) {
if (Tracing) {
Console.WriteLine("Done State");
done.Dump();
Console.WriteLine("Pending State");
pending.Dump();
Console.WriteLine("StateToReanalyzeBlock result UNchanged");
}
return null;
}
if ( preciseMerge ) return pending;
if (Tracing) {
Console.WriteLine("StateToReanalyzeBlock result CHANGED");
if (done == null) {
Console.WriteLine("no done state yet");
}
else {
Console.WriteLine("Done State");
done.Dump();
}
Console.WriteLine("Pending State");
pending.Dump();
Console.WriteLine("Merged State");
merged.Dump();
}
return merged;
}
protected override void SplitExceptions(CfgBlock handler, ref IDataFlowState currentHandlerState, out IDataFlowState nextHandlerState) {
nextHandlerState = null;
return;
}
/// <summary>
/// Checks if a block needs to be reanalyzed and under what state.
///
/// Updates the doneState of this block to reflect the pending state
/// </summary>
/// <returns>null if no reanalysis necessary, the DFS state if the merge is precise,
/// the merged state if the merge is imprecise
/// </returns>
private IDataFlowState StateToReanalyzeBlock(CfgBlock prev, CfgBlock block, IDataFlowState pending, out bool preciseMerge)
{
IDataFlowState done = DoneState(block);
// note, we call Merge even if old is null.
bool changed;
if (Tracing)
{
Console.WriteLine("StateToReanalyzeBlock: block {0} -> {1}",
(prev).UniqueKey,
(block).UniqueKey);
SourceContext sc = (block).SourceContext;
if (sc.Document == null && block.Length > 0)
{
sc = ((Statement)block[0]).SourceContext;
}
Console.WriteLine("StateToReanalyzeBlock at line {0}", sc.StartLine);
}
IDataFlowState merged = this.Merge(prev, block, done, pending, out changed, out preciseMerge);
if (merged != null)
{
doneStates[block.Index] = merged;
}
if (!changed)
{
if (Tracing)
{
Console.WriteLine("Done State");
done.Dump();
Console.WriteLine("Pending State");
pending.Dump();
Console.WriteLine("StateToReanalyzeBlock result UNchanged");
}
return(null);
}
if (preciseMerge)
{
return(pending);
}
if (Tracing)
{
Console.WriteLine("StateToReanalyzeBlock result CHANGED");
if (done == null)
{
Console.WriteLine("no done state yet");
}
else
{
Console.WriteLine("Done State");
done.Dump();
}
Console.WriteLine("Pending State");
pending.Dump();
Console.WriteLine("Merged State");
merged.Dump();
}
return(merged);
}
