/// <summary>
/// Visit a boolean condition expression, where we will be wanting AssignedWhenTrue and
/// AssignedWhenFalse.
/// </summary>
/// <param name="node"></param>
protected void VisitCondition(BoundExpression node)
{
Debug.Assert(!this.state.Assigned.IsNull);
Visit(node);
// We implement the foundational rules missing from the language specification:
// v is "definitely assigned when true" after a constant expression whose value is false.
// v is "definitely assigned when false" after a constant expression whose value is true.
// These rules are to be added to the language specification.
// It was the lack of these foundational rules that led to the invention of the concept
// of "unreachable expression" in the native compiler.
if (IsConstantTrue(node))
{
state.Merge();
this.state = new FlowAnalysisLocalState(this.state.Reachable, this.state.Assigned, BitArray.AllSet(nextVariableSlot));
}
else if (IsConstantFalse(node))
{
state.Merge();
this.state = new FlowAnalysisLocalState(this.state.Reachable, BitArray.AllSet(nextVariableSlot), this.state.Assigned);
}
else
{
state.Split();
}
}
// when two control points merge. Returns true if this state changed.
public bool Join(FlowAnalysisLocalState other)
{
this.Merge();
other.Merge();
this.Reachable |= other.Reachable;
return(this.Assigned.IntersectWith(other.Assigned));
}
// when two control points merge. Returns true if this state changed.
public bool Join(FlowAnalysisLocalState other)
{
this.Merge();
other.Merge();
this.Reachable |= other.Reachable;
return this.Assigned.IntersectWith(other.Assigned);
}
