private void CompileTryExpression(Expression expr) {
var node = (TryExpression)expr;
Label startOfFinally = MakeLabel();
if (node.Finally != null) {
_finallyLabels.Push(new FinallyLabels(startOfFinally));
}
int startingStack = _currentStackDepth;
int start = _instructions.Count;
this.Compile(node.Body);
int end = _instructions.Count;
if (_currentStackDepth != -1) {
AddBranch(startOfFinally);
}
if (node.Finally == null && node.Fault == null && node.Handlers.Count == 1) {
var handler = node.Handlers[0];
if (handler.Filter == null && handler.Test == typeof(Exception) && handler.Variable == null) {
if (EndsWithRethrow(handler.Body)) {
var fault = this.AddHandler(null, null, start, end);
_currentStackDepth = startingStack;
CompileWithoutRethrow(handler.Body);
fault.EndHandlerIndex = this._instructions.Count;
startOfFinally.Mark();
return;
}
}
}
foreach (var handler in node.Handlers) {
if (handler.Filter != null) throw new NotImplementedException();
var parameter = handler.Variable;
// TODO we should only create one of these if needed for a rethrow
if (parameter == null) {
parameter = Expression.Parameter(handler.Test, "currentException");
AddVariable(parameter);
}
this.AddHandler(handler.Test, parameter, start, end);
_exceptionForRethrowStack.Push(parameter);
_currentStackDepth = startingStack + 1;
SetVariable(parameter, true);
this.Compile(handler.Body);
//TODO pop this scoped variable that we no longer need
//PopVariable(parameter);
_exceptionForRethrowStack.Pop();
AddBranch(startOfFinally);
}
if (node.Fault != null) {
throw new NotImplementedException();
}
if (node.Finally != null) {
var myLabels = _finallyLabels.Pop();
var myNewTargets = new List<Label>();
int finallyStart = _instructions.Count;
ParameterExpression finallyStateVar = null;
ParameterExpression finallyStackValue = null;
foreach (var kv in myLabels.labels) {
var label = kv.Key;
if (label._index == -1 || label._index < start || label._index > finallyStart) {
myNewTargets.Add(label);
var currentLabel = MakeLabel();
_currentStackDepth = -1;
currentLabel._expectedStackSize = label._expectedStackSize;
currentLabel.Mark();
foreach (var branch in kv.Value) {
currentLabel.SetOffset(branch);
label.RemoveBinding(branch);
}
if (finallyStateVar == null) {
finallyStateVar = Expression.Parameter(typeof(int), "finallyBranch");
AddVariable(finallyStateVar);
finallyStackValue = Expression.Parameter(typeof(object), "stackValue");
AddVariable(finallyStackValue);
}
if (myLabels.labelHasValue[label]) {
SetVariable(finallyStackValue, true);
}
PushConstant(myNewTargets.Count-1);
SetVariable(finallyStateVar, true);
AddBranch(startOfFinally);
}
}
_currentStackDepth = startingStack + ((node.Body.Type == typeof(void)) ? 0 : 1);
startOfFinally.Mark();
var faultHandler = this.AddHandler(null, null, start, end);
this.Compile(node.Finally);
if (node.Finally.Type != typeof(void)) {
AddInstruction(PopInstruction.Instance);
}
faultHandler.EndHandlerIndex = _instructions.Count;
if (finallyStateVar != null) {
// we can make this much more efficient in the future
var si = new SwitchInstruction();
AddInstruction(GetVariable(finallyStateVar));
int switchIndex = _instructions.Count;
AddInstruction(si);
int switchStack = _currentStackDepth;
for (int i = 0; i < myNewTargets.Count; i++) {
_currentStackDepth = switchStack;
si.AddCase(i, _instructions.Count-switchIndex);
if (myLabels.labelHasValue[myNewTargets[i]]) {
AddInstruction(GetVariable(finallyStackValue));
}
var branchInstruction = AddBranch(myNewTargets[i]);
if (_finallyLabels.Count > 0) {
var labels = _finallyLabels.Peek();
labels.AddBranch(branchInstruction, myNewTargets[i], myLabels.labelHasValue[myNewTargets[i]]);
}
}
si.AddDefault(_instructions.Count - switchIndex);
_currentStackDepth = switchStack; // we might exit totally normally!
}
} else {
startOfFinally.Mark();
}
}
private void CompileSwitchExpression(Expression expr) {
var node = (SwitchExpression)expr;
if (node.Test.Type != typeof(int)) throw new NotImplementedException();
Debug.Assert(node.Type == typeof(void));
this.Compile(node.Test);
int start = _instructions.Count;
var switchInstruction = new SwitchInstruction();
AddInstruction(switchInstruction);
bool setDefault = false;
int switchStack = _currentStackDepth;
foreach (var clause in node.SwitchCases) {
_currentStackDepth = switchStack;
int offset = _instructions.Count - start;
if (clause.IsDefault) {
setDefault = true;
switchInstruction.AddDefault(offset);
} else {
switchInstruction.AddCase(clause.Value, offset);
}
this.Compile(clause.Body);
Debug.Assert(_currentStackDepth == -1 || _currentStackDepth == switchStack);
}
if (!setDefault) {
switchInstruction.AddDefault(_instructions.Count - start);
_currentStackDepth = switchStack;
}
if (node.BreakLabel != null) {
ReferenceLabel(node.BreakLabel).Mark();
}
}