private Expression VisitExpression(ref BoundSpillSequenceBuilder builder, Expression expression)
{
// wrap the node in a spill sequence to mark the fact that it must be moved up the tree.
// The caller will handle this node type if the result is discarded.
if (expression != null && expression.NodeType == NodeType.AwaitExpression)
{
// we force the await expression to be assigned to a temp variable
var awaitExpression = (AwaitExpression)expression;
awaitExpression.BaseExpression = VisitExpression(ref builder, awaitExpression.BaseExpression);
var local = _F.DeclareTempLocal(_currentMethod, awaitExpression.ExpressionType);
var replacement = _F.CreateAssignment(
awaitExpression.LexicalInfo,
_F.CreateLocalReference(local),
awaitExpression);
if (builder == null)
{
builder = new BoundSpillSequenceBuilder();
}
builder.AddLocal(local);
builder.AddStatement(new ExpressionStatement(replacement));
return(_F.CreateLocalReference(local));
}
var e = Visit(expression);
if (e == null || e.NodeType != SpillSequenceBuilder)
{
return(e);
}
var newBuilder = (BoundSpillSequenceBuilder)e;
if (builder == null)
{
builder = newBuilder.Update(null);
}
else
{
builder.Include(newBuilder);
}
return(newBuilder.Value);
}