void Executor_ImplementationEntered(object sender, Symbooglix.Executor.EnterImplementationEventArgs e)
{
// Handle the case where we enter a new implementation and the first block
// is a loop header. This is the only case we don't get notified of a basic block
// change.
var state = Executor.CurrentState; // FIXME: The state should be part of the event arg
var sf = state.Mem.Stack.Last();
var loopInfo = ProgramLoopInfo.GetLoopInfoForHeader(sf.CurrentBlock);
if (loopInfo == null)
{
return; // Not a loop. Nothing to do.
}
var executionStateSingleLoopInfo = new ExecutionStateSingleLoopInfo(sf, loopInfo);
StateToCurrentLoops[state].NestedLoops.Push(executionStateSingleLoopInfo);
}
public ExecutionStateNestedLoopInfo Clone(ExecutionState newState)
{
var other = (ExecutionStateNestedLoopInfo)this.MemberwiseClone();
other.State = newState;
other.NestedLoops = new Stack <ExecutionStateSingleLoopInfo>(NestedLoops.Count);
// Traverse in reverse order (i.e. start at bottom of the stack)
// so we can push elements on to the new stack in the right order
foreach (var sli in NestedLoops.Reverse())
{
StackFrame stackFrameInNewState = GetCorrespondingStackFrame(newState, sli.Stack);
ExecutionStateSingleLoopInfo newSli = sli.Clone(stackFrameInNewState);
other.NestedLoops.Push(newSli);
}
Debug.Assert(other.NestedLoops.Count == NestedLoops.Count);
return(other);
}
void Executor_BasicBlockChanged(object sender, Symbooglix.Executor.TransferToBlockEventArgs eventArgs)
{
// Control flow has transferred to a different basic block
var state = eventArgs.State;
var sf = state.Mem.Stack.Last();
var executionStateNestedLoopInfo = StateToCurrentLoops[state];
// Cases:
// * No existing loops, enter loop header
// * No existing loops, do not enter loop header
// * Existing loop, stackframe doesn't match (i.e. a call must have happenend), enter loop header
// * Existing loop, stackframe doesn't match (i.e. a call must have happenend), do not enter loop header
// * Existing loop, stackframe matches, enter loop header (must increment counter)
// * Existing loop, stackframe matches, leave loop via exit basic block (we are leaving the current loop)
// * Existing loop, stackframe matches, enter nested loop header (must push new loop on to stack)
// * Existing loop, stackframe matches, stay in current loop (nothing to do)
bool stackframeMatches = false;
if (executionStateNestedLoopInfo.NestedLoops.Count > 0)
{
stackframeMatches = object.ReferenceEquals(executionStateNestedLoopInfo.NestedLoops.Peek().Stack,
sf);
}
ExecutionStateSingleLoopInfo executionStateSingleLoopInfo = null;
if (!stackframeMatches)
{
// This handles the case that there are no existing loops on the stack or
// there are existing loops but they are in another stackframe (i.e. we were in a loop
// and then called into another implementation).
var loopInfo = ProgramLoopInfo.GetLoopInfoForHeader(eventArgs.NewBlock);
if (loopInfo == null)
{
// The block we've entered is not a loop header and there are no
// existing loops we are in that we can enter/exit so there is nothing
// left to do
return;
}
// We've enterred a new loop push it on to the loop stack
executionStateSingleLoopInfo = new ExecutionStateSingleLoopInfo(sf, loopInfo);
executionStateNestedLoopInfo.NestedLoops.Push(executionStateSingleLoopInfo);
return;
}
// We are currently inside a loop and are still in the context of that loop's stackframe on the
// call stack.
executionStateSingleLoopInfo = executionStateNestedLoopInfo.NestedLoops.Peek();
if (object.ReferenceEquals(executionStateSingleLoopInfo.LInfo.Header, eventArgs.NewBlock))
{
// We are going to the loop header so we must have just completed one iteration
// of the loop. Increment the counter.
executionStateSingleLoopInfo.IncrementCounter();
// Don't check bound here. The executor will misbehave (see goto look ahead)
// if we try to terminate state here.
return;
}
else if (executionStateSingleLoopInfo.LInfo.EscapingBlocks.Contains(eventArgs.NewBlock))
{
// We are in a loop but are about to jump to a basic block that escapes from the loop.
// So pop this loop from the stack.
executionStateNestedLoopInfo.NestedLoops.Pop();
return;
}
var newLoopInfo = ProgramLoopInfo.GetLoopInfoForHeader(eventArgs.NewBlock);
if (newLoopInfo == null)
{
// We are in a loop but we are jumping to a basic block that
// * does not escape the current loop
// * does not go to the loop head
// * does not enter a nested loop (i.e. another loop head)
// So there is nothing left to do.
return;
}
// We are entering a nested loop. Push this loop onto the stack.
var newExecutionStateSingleLoopInfo = new ExecutionStateSingleLoopInfo(sf, newLoopInfo);
executionStateNestedLoopInfo.NestedLoops.Push(newExecutionStateSingleLoopInfo);
return;
}