private static Instruction FindNextConstructionMethod(MethodDefinition method, Instruction instruction)
{
var cursor = instruction;
//the description object should be on the stack, and nothing on top of it.
int stackDepth = 1;
while (cursor.Next != null)
{
cursor = cursor.Next;
var result = CecilHelpers.MatchesDelegateProducingPattern(method, cursor, CecilHelpers.DelegateProducingPattern.MatchSide.Start);
if (result != null)
{
cursor = result.Instructions.Last();
stackDepth += 1;
continue;
}
if (CecilHelpers.IsUnsupportedBranch(cursor))
{
UserError.DC0010(method, cursor).Throw();
}
if (cursor.OpCode == OpCodes.Call && cursor.Operand is MethodReference mr && IsLambdaJobDescriptionConstructionMethod(mr))
{
return(cursor);
}
stackDepth -= cursor.GetPopDelta();
if (stackDepth < 1)
{
UserError.DC0011(method, cursor).Throw();
}
stackDepth += cursor.GetPushDelta();
}
return(null);
}
public static Instruction FindInstructionThatPushedArg(MethodDefinition containingMethod, int argNumber,
Instruction callInstructionsWhoseArgumentsWeWantToFind)
{
containingMethod.Body.EnsurePreviousAndNextAreSet();
var cursor = callInstructionsWhoseArgumentsWeWantToFind.Previous;
int stackSlotWhoseWriteWeAreLookingFor = argNumber;
int stackSlotWhereNextPushWouldBeWrittenTo = InstructionExtensions.GetPopDelta(callInstructionsWhoseArgumentsWeWantToFind);
var seenInstructions = new HashSet <Instruction>()
{
callInstructionsWhoseArgumentsWeWantToFind, cursor
};
while (cursor != null)
{
var pushAmount = cursor.GetPushDelta();
var popAmount = cursor.GetPopDelta();
var result = CecilHelpers.MatchesDelegateProducingPattern(containingMethod, cursor, CecilHelpers.DelegateProducingPattern.MatchSide.End);
if (result != null)
{
//so we are crawling backwards through isntructions. if we find a "this is roslyn caching a delegate" sequence,
//we're going to pretend it is a single instruction, that pushes the delegate on the stack, and pops nothing.
cursor = result.Instructions.First();
pushAmount = 1;
popAmount = 0;
}
else if (cursor.IsBranch())
{
var target = (Instruction)cursor.Operand;
if (!seenInstructions.Contains(target))
{
if (IsUnsupportedBranch(cursor))
{
UserError.DC0010(containingMethod, cursor).Throw();
}
}
}
for (int i = 0; i != pushAmount; i++)
{
stackSlotWhereNextPushWouldBeWrittenTo--;
if (stackSlotWhereNextPushWouldBeWrittenTo == stackSlotWhoseWriteWeAreLookingFor)
{
return(cursor);
}
}
for (int i = 0; i != popAmount; i++)
{
stackSlotWhereNextPushWouldBeWrittenTo++;
}
cursor = cursor.Previous;
seenInstructions.Add(cursor);
}
return(null);
}