/// <summary>
/// Visits block statements and its edge to next block.
/// </summary>
protected virtual void VisitCFGBlockInternal(BoundBlock x)
{
VisitCFGBlockStatements(x);
if (x.NextEdge != null)
x.NextEdge.Visit(this);
}
/// <summary>
/// Subscribe a block to be analysed when the exit block is reached and the routine return value changes.
/// </summary>
internal void Subscribe(BoundBlock x)
{
if (_subscribers == null)
_subscribers = new HashSet<BoundBlock>();
_subscribers.Add(x);
}
void VisitCFGBlockStatements(BoundBlock x)
{
for (int i = 0; i < x.Statements.Count; i++)
{
Accept(x.Statements[i]);
}
}
public virtual void VisitBlockStatement(Graph.BoundBlock x)
{
for (int i = 0; i < x.Statements.Count; i++)
{
Accept(x.Statements[i]);
}
}
protected virtual TResult DefaultVisitBlock(BoundBlock x) => default;
public virtual void VisitBlockStatement(Graph.BoundBlock x)
{
x.Statements.ForEach(Accept);
}
public BreakTargetScope(BoundBlock breakBlock, BoundBlock continueBlock)
{
BreakTarget = breakBlock;
ContinueTarget = continueBlock;
}
internal TryCatchEdge(BoundBlock source, BoundBlock body, CatchBlock[] catchBlocks, BoundBlock finallyBlock, BoundBlock endBlock)
: base(source)
{
_body = body;
_catchBlocks = catchBlocks;
_finallyBlock = finallyBlock;
_end = endBlock;
Connect(source);
}
internal LeaveEdge(BoundBlock source, BoundBlock target)
:base(source, target)
{
}
/// <summary>
/// Helper method that merges state with the target block and determines whether to continue by visiting the target block.
/// </summary>
/// <param name="state">Locals state in which we are entering the target.</param>
/// <param name="target">Target block.</param>
/// <remarks>Only for traversing into blocks within the same routine (same type context).</remarks>
private void TraverseToBlock(FlowState/*!*/state, BoundBlock/*!*/target)
{
Contract.ThrowIfNull(state); // state should be already set by previous block
var targetState = target.FlowState;
if (targetState != null)
{
Debug.Assert(targetState.FlowContext == state.FlowContext);
// block was visited already,
// merge and check whether state changed
state = state.Merge(targetState); // merge states into new one
if (state.Equals(targetState))
{
return; // state convergated, we don't have to analyse target block again
}
}
else
{
// block was not visited yet
state = state.Clone(); // copy state into new one
}
// update target block state
target.FlowState = state;
//
_worklist.Enqueue(target);
}
public override void VisitSwitchStmt(SwitchStmt x)
{
var items = x.SwitchItems;
if (items == null || items.Length == 0)
{
return;
}
// get bound item for switch value & connect potential pre-switch-value blocks
var boundBagForSwitchValue = _binder.BindWholeExpression(x.SwitchValue, BoundAccess.Read);
ConnectBoundItemsBagBlocksToCurrentBlock(boundBagForSwitchValue);
var switchValue = boundBagForSwitchValue.BoundElement;
var end = NewBlock();
bool hasDefault = false;
var cases = new List <CaseBlock>(items.Length);
for (int i = 0; i < items.Length; i++)
{
cases.Add(NewBlock(items[i]));
hasDefault |= (items[i] is DefaultItem);
}
if (!hasDefault)
{
// create implicit default:
cases.Add(NewBlock(new DefaultItem(x.Span, Array.Empty <Statement>())));
}
// if switch value isn't a constant & there're case values with preBoundStatements
// -> the switch value might get evaluated multiple times (see SwitchEdge.Generate) -> preemptively evaluate and cache it
if (!switchValue.IsConstant() && !cases.All(c => c.CaseValue.IsOnlyBoundElement))
{
var result = GeneratorSemanticsBinder.CreateAndAssignSynthesizedVariable(switchValue, BoundAccess.Read, $"<switchValueCacher>{x.Span}");
switchValue = result.BoundExpr;
_current.Add(new BoundExpressionStatement(result.Assignment));
}
// SwitchEdge // Connects _current to cases
var edge = new SwitchEdge(_current, switchValue, cases.ToImmutableArray(), end);
_current = WithNewOrdinal(cases[0]);
OpenBreakScope(end, end); // NOTE: inside switch, Continue ~ Break
for (int i = 0; i < cases.Count; i++)
{
OpenScope(_current);
if (i < items.Length)
{
items[i].Statements.ForEach(VisitElement); // any break will connect block to end
}
CloseScope();
_current = WithNewOrdinal(Connect(_current, (i == cases.Count - 1) ? end : cases[i + 1]));
}
CloseBreakScope();
Debug.Assert(_current == end);
}
private void OpenScope(BoundBlock block, LocalScope scope = LocalScope.Code)
{
_scopes.Push(new LocalScopeInfo(block, scope));
}
public LocalScopeInfo(BoundBlock firstBlock, LocalScope scope)
{
this.FirstBlock = firstBlock;
this.Scope = scope;
}
private BoundBlock /*!*/ Leave(BoundBlock /*!*/ source, BoundBlock /*!*/ target)
{
new LeaveEdge(source, target);
return(target);
}
private BoundBlock /*!*/ Connect(BoundBlock /*!*/ source, BoundBlock /*!*/ target)
{
new SimpleEdge(source, target);
return(target);
}
private BoundBlock /*!*/ Connect(BoundBlock /*!*/ source, BoundBlock /*!*/ ifTarget, BoundBlock /*!*/ elseTarget, Expression condition, bool isloop = false)
{
if (condition != null)
{
// bind condition expression & connect pre-condition blocks to source
var boundConditionBag = _binder.BindWholeExpression(condition, BoundAccess.Read);
source = ConnectBoundItemsBagBlocks(boundConditionBag, source);
new ConditionalEdge(source, ifTarget, elseTarget, boundConditionBag.BoundElement)
{
IsLoop = isloop,
};
return(ifTarget);
}
else
{
// jump to ifTarget if there is no condition (always true) // e.g. for (;;) { [ifTarget] }
return(Connect(source, ifTarget));
}
}
private void ConnectBoundItemsBagBlocksToCurrentBlock <T>(BoundItemsBag <T> bag) where T : class, IPhpOperation
{
_current = ConnectBoundItemsBagBlocks(bag, _current);
}
/// <summary>
/// Called to initialize <see cref="VisitCFGBlock"/> call.
/// Sets <see cref="_state"/> to known initial block state.
/// </summary>
protected virtual void VisitCFGBlockInit(BoundBlock/*!*/x)
{
Contract.ThrowIfNull(x.FlowState); // state should be already set by previous edge
_state = x.FlowState.Clone(); // TFlowState for the statements in the block
this.CurrentBlock = x;
}
public override void VisitCFGBlock(BoundBlock x)
{
VisitCFGBlockInit(x);
VisitCFGBlockInternal(x); // modifies _state, traverses to the edge
}
public override void VisitTryStmt(TryStmt x)
{
// try {
// x.Body
// }
// catch (E1) { body }
// catch (E2) { body }
// finally { body }
// end
var end = NewBlock();
var body = NewBlock();
// init catch blocks and finally block
var catchBlocks = ImmutableArray <CatchBlock> .Empty;
if (x.Catches != null)
{
var catchBuilder = ImmutableArray.CreateBuilder <CatchBlock>(x.Catches.Length);
for (int i = 0; i < x.Catches.Length; i++)
{
catchBuilder.Add(NewBlock(x.Catches[i]));
}
catchBlocks = catchBuilder.MoveToImmutable();
}
BoundBlock finallyBlock = null;
if (x.FinallyItem != null)
{
finallyBlock = NewBlock();
}
// TryCatchEdge // Connects _current to body, catch blocks and finally
var edge = new TryCatchEdge(_current, body, catchBlocks, finallyBlock, end);
var oldstates0 = _binder.StatesCount;
// build try body
OpenTryScope(edge);
OpenScope(body, LocalScope.Try);
_current = WithNewOrdinal(body);
VisitElement(x.Body);
CloseScope();
CloseTryScope();
_current = Leave(_current, finallyBlock ?? end);
var oldstates1 = _binder.StatesCount;
// built catches
for (int i = 0; i < catchBlocks.Length; i++)
{
_current = WithOpenScope(WithNewOrdinal(catchBlocks[i]), LocalScope.Catch);
VisitElement(x.Catches[i].Body);
CloseScope();
_current = Leave(_current, finallyBlock ?? end);
}
// build finally
var oldReturnCount = _returnCounter;
if (finallyBlock != null)
{
_current = WithOpenScope(WithNewOrdinal(finallyBlock), LocalScope.Finally);
VisitElement(x.FinallyItem.Body);
CloseScope();
_current = Leave(_current, end);
}
//
if ((oldstates0 != oldstates1 && finallyBlock != null) || // yield in "try" with "finally" block
oldstates1 != _binder.StatesCount || // yield in "catch" or "finally"
oldReturnCount != _returnCounter) // return in "finally"
{
// catch or finally introduces new states to the state machine
// or there is "return" in finally block:
// catch/finally must not be handled by CLR
edge.EmitCatchFinallyOutsideScope = true;
}
// _current == end
_current.Ordinal = NewOrdinal();
}
internal SimpleEdge(BoundBlock source, BoundBlock target)
: base(source)
{
Debug.Assert(source != target);
_target = target;
Connect(source);
}
internal ForeachMoveNextEdge(BoundBlock/*!*/source, BoundBlock/*!*/body, BoundBlock/*!*/end, ForeachEnumereeEdge/*!*/enumereeEdge, BoundReferenceExpression keyVar, BoundReferenceExpression/*!*/valueVar)
: base(source)
{
Contract.ThrowIfNull(body);
Contract.ThrowIfNull(end);
Contract.ThrowIfNull(enumereeEdge);
_body = body;
_end = end;
_enumereeEdge = enumereeEdge;
_keyVariable = keyVar;
_valueVariable = valueVar;
Connect(source);
}
internal ConditionalEdge(BoundBlock source, BoundBlock @true, BoundBlock @false, BoundExpression cond)
: base(source)
{
Debug.Assert(@true != @false);
_true = @true;
_false = @false;
_condition = cond;
Connect(source);
}
internal Edge(BoundBlock/*!*/source)
{
Contract.ThrowIfNull(source);
}
internal ForeachEnumereeEdge(BoundBlock/*!*/source, BoundBlock/*!*/target, BoundExpression/*!*/enumeree, bool aliasedValues)
: base(source, target)
{
Contract.ThrowIfNull(enumeree);
_enumeree = enumeree;
_aliasedValues = aliasedValues;
}
public virtual TResult VisitCFGBlock(BoundBlock x) => DefaultVisitBlock(x);
internal SwitchEdge(BoundBlock source, BoundExpression switchValue, CaseBlock[] caseBlocks, BoundBlock endBlock)
: base(source)
{
Contract.ThrowIfNull(caseBlocks);
_switchValue = switchValue;
_caseBlocks = caseBlocks;
_end = endBlock;
Connect(source);
}
public virtual void VisitCFGBlock(BoundBlock x)
{
VisitCFGBlockInternal(x);
}
protected void Connect(BoundBlock/*!*/source)
{
source.NextEdge = this;
}
void AnalyzeBlock(BoundBlock block) // TODO: driver
{
// TODO: pool of CFGAnalysis
// TODO: async
// TODO: in parallel
block.Accept(AnalysisFactory());
}
/// <summary>
/// Enqueues the standalone expression for analysis.
/// </summary>
void EnqueueExpression(BoundExpression expression, TypeRefContext/*!*/ctx, NamingContext naming)
{
Contract.ThrowIfNull(expression);
Contract.ThrowIfNull(ctx);
var dummy = new BoundBlock()
{
FlowState = new FlowState(new FlowContext(ctx, null)),
Naming = naming
};
dummy.Add(new BoundExpressionStatement(expression));
_worklist.Enqueue(dummy);
}
private ControlFlowGraph(BoundBlock/*!*/start, BoundBlock/*!*/exit, BoundBlock exception, LabelBlockState[] labels, List<BoundBlock> unreachable)
{
Contract.ThrowIfNull(start);
Contract.ThrowIfNull(exit);
_start = start;
_exit = exit;
//_exception = exception;
_labels = labels;
_unrecachable = unreachable ?? new List<BoundBlock>();
}
public virtual TResult VisitBlockStatement(Graph.BoundBlock x) => DefaultVisitOperation(x);
/// <summary>Visits given block.</summary> protected TResult Accept(BoundBlock x) => (x != null) ? x.Accept(this) : default;