List <AstNode> ConvertToAst(List <ByteCode> body, HashSet <ExceptionHandler> ehs)
{
var ast = new List <AstNode>();
while (ehs.Any())
{
var tryCatchBlock = new AstTryCatchBlock(null);
// Find the first and widest scope
var tryStart = ehs.Min(eh => eh.TryStart.Offset);
var tryEnd = ehs.Where(eh => eh.TryStart.Offset == tryStart).Max(eh => eh.TryEnd.Offset);
var handlers = ehs.Where(eh => eh.TryStart.Offset == tryStart && eh.TryEnd.Offset == tryEnd).OrderBy(eh => eh.TryStart.Offset).ToList();
// Remember that any part of the body migt have been removed due to unreachability
// Cut all instructions up to the try block
{
var tryStartIdx = 0;
while (tryStartIdx < body.Count && body[tryStartIdx].Offset < tryStart)
{
tryStartIdx++;
}
ast.AddRange(ConvertToAst(CollectionExtensions.CutRange(body, 0, tryStartIdx)));
}
// Cut the try block
{
var nestedEHs = new HashSet <ExceptionHandler>(
ehs.Where(eh => (tryStart <= eh.TryStart.Offset && eh.TryEnd.Offset < tryEnd) || (tryStart < eh.TryStart.Offset && eh.TryEnd.Offset <= tryEnd)));
ehs.ExceptWith(nestedEHs);
var tryEndIdx = 0;
while (tryEndIdx < body.Count && body[tryEndIdx].Offset < tryEnd)
{
tryEndIdx++;
}
var converted = ConvertToAst(CollectionExtensions.CutRange(body, 0, tryEndIdx), nestedEHs);
tryCatchBlock.TryBlock = new AstBlock(converted.Select(x => x.SourceLocation).FirstOrDefault(), converted);
}
// Cut all handlers
tryCatchBlock.CatchBlocks.Clear();
foreach (var eh in handlers)
{
var handlerEndOffset = eh.HandlerEnd == null ? methodDef.Body.CodeSize : eh.HandlerEnd.Offset;
var startIdx = 0;
while (startIdx < body.Count && body[startIdx].Offset < eh.HandlerStart.Offset)
{
startIdx++;
}
var endIdx = 0;
while (endIdx < body.Count && body[endIdx].Offset < handlerEndOffset)
{
endIdx++;
}
var nestedEHs = new HashSet <ExceptionHandler>(ehs.Where(e => (eh.HandlerStart.Offset <= e.TryStart.Offset && e.TryEnd.Offset < handlerEndOffset) || (eh.HandlerStart.Offset < e.TryStart.Offset && e.TryEnd.Offset <= handlerEndOffset)));
ehs.ExceptWith(nestedEHs);
var handlerAst = ConvertToAst(CollectionExtensions.CutRange(body, startIdx, endIdx - startIdx), nestedEHs);
if (eh.HandlerType == ExceptionHandlerType.Catch)
{
var catchType = eh.CatchType.IsSystemObject() ? module.TypeSystem.Exception : XBuilder.AsTypeReference(module, eh.CatchType);
var catchBlock = new AstTryCatchBlock.CatchBlock(handlerAst.Select(x => x.SourceLocation).FirstOrDefault(), tryCatchBlock)
{
ExceptionType = catchType,
Body = handlerAst
};
// Handle the automatically pushed exception on the stack
var ldexception = ldexceptions[eh];
if (ldexception.StoreTo == null || ldexception.StoreTo.Count == 0)
{
// Exception is not used
catchBlock.ExceptionVariable = null;
}
else if (ldexception.StoreTo.Count == 1)
{
var first = catchBlock.Body[0] as AstExpression;
if (first != null &&
first.Code == AstCode.Pop &&
first.Arguments[0].Code == AstCode.Ldloc &&
first.Arguments[0].Operand == ldexception.StoreTo[0])
{
// The exception is just poped - optimize it all away;
if (context.Settings.AlwaysGenerateExceptionVariableForCatchBlocks)
{
catchBlock.ExceptionVariable = new AstGeneratedVariable("ex_" + eh.HandlerStart.Offset.ToString("X2"), null);
}
else
{
catchBlock.ExceptionVariable = null;
}
catchBlock.Body.RemoveAt(0);
}
else
{
catchBlock.ExceptionVariable = ldexception.StoreTo[0];
}
}
else
{
var exTemp = new AstGeneratedVariable("ex_" + eh.HandlerStart.Offset.ToString("X2"), null);
catchBlock.ExceptionVariable = exTemp;
foreach (var storeTo in ldexception.StoreTo)
{
catchBlock.Body.Insert(0, new AstExpression(catchBlock.SourceLocation, AstCode.Stloc, storeTo, new AstExpression(catchBlock.SourceLocation, AstCode.Ldloc, exTemp)));
}
}
tryCatchBlock.CatchBlocks.Add(catchBlock);
}
else if (eh.HandlerType == ExceptionHandlerType.Finally)
{
tryCatchBlock.FinallyBlock = new AstBlock(handlerAst);
}
else if (eh.HandlerType == ExceptionHandlerType.Fault)
{
tryCatchBlock.FaultBlock = new AstBlock(handlerAst);
}
else
{
// TODO: ExceptionHandlerType.Filter
}
}
ehs.ExceptWith(handlers);
ast.Add(tryCatchBlock);
}
// Add whatever is left
ast.AddRange(ConvertToAst(body));
return(ast);
}
