private void EmitSwitchExpression(Expression expr)
{
SwitchExpression node = (SwitchExpression)expr;
LabelInfo breakTarget = DefineLabel(node.BreakLabel);
Label defaultTarget = breakTarget.Label;
Label[] labels = new Label[node.SwitchCases.Count];
// Create all labels
for (int i = 0; i < node.SwitchCases.Count; i++)
{
labels[i] = _ilg.DefineLabel();
// Default case.
if (node.SwitchCases[i].IsDefault)
{
// Set the default target
defaultTarget = labels[i];
}
}
// Emit the test value
EmitExpression(node.Test);
// Check if jmp table can be emitted
if (!TryEmitJumpTable(node, labels, defaultTarget))
{
// There might be scenario(s) where the jmp table is not emitted
// Emit the switch as conditional branches then
EmitConditionalBranches(node, labels);
}
// If "default" present, execute default code, else exit the switch
_ilg.Emit(OpCodes.Br, defaultTarget);
// Emit the bodies
for (int i = 0; i < node.SwitchCases.Count; i++)
{
// First put the corresponding labels
_ilg.MarkLabel(labels[i]);
// And then emit the Body!!
EmitExpressionAsVoid(node.SwitchCases[i].Body);
}
breakTarget.Mark();
}
private void EmitLabelExpression(Expression expr, CompilationFlags flags)
{
var node = (LabelExpression)expr;
Debug.Assert(node.Target != null);
// If we're an immediate child of a block, our label will already
// be defined. If not, we need to define our own block so this
// label isn't exposed except to its own child expression.
LabelInfo label = null;
if (_labelBlock.Kind == LabelScopeKind.Block)
{
_labelBlock.TryGetLabelInfo(node.Target, out label);
// We're in a block but didn't find our label, try switch
if (label == null && _labelBlock.Parent.Kind == LabelScopeKind.Switch)
{
_labelBlock.Parent.TryGetLabelInfo(node.Target, out label);
}
// if we're in a switch or block, we should've found the label
Debug.Assert(label != null);
}
if (label == null)
{
label = DefineLabel(node.Target);
}
if (node.DefaultValue != null)
{
if (node.Target.Type == typeof(void))
{
EmitExpressionAsVoid(node.DefaultValue, flags);
}
else
{
flags = UpdateEmitExpressionStartFlag(flags, CompilationFlags.EmitExpressionStart);
EmitExpression(node.DefaultValue, flags);
}
}
label.Mark();
}
private void EmitLoopExpression(Expression expr)
{
LoopExpression node = (LoopExpression)expr;
PushLabelBlock(LabelBlockKind.Block);
LabelInfo breakTarget = DefineLabel(node.BreakLabel);
LabelInfo continueTarget = DefineLabel(node.ContinueLabel);
continueTarget.Mark();
EmitExpressionAsVoid(node.Body);
_ilg.Emit(OpCodes.Br, continueTarget.Label);
PopLabelBlock(LabelBlockKind.Block);
breakTarget.Mark();
}
