/// <summary>
/// Get index of deconstruction result or tuple element
/// Returns -1 on failure.
/// </summary>
int FindIndex(ILInstruction inst, out Action <DeconstructInstruction> delayedActions)
{
delayedActions = null;
if (inst.MatchLdLoc(out var v))
{
if (!deconstructionResultsLookup.TryGetValue(v, out int index))
{
return(-1);
}
return(index);
}
if (inst.MatchLdFld(out _, out _))
{
if (!TupleTransform.MatchTupleFieldAccess((LdFlda)((LdObj)inst).Target, out var tupleType, out var target, out int index))
{
return(-1);
}
// Item fields are one-based, we use zero-based indexing.
index--;
// normalize tuple type
tupleType = TupleType.FromUnderlyingType(context.TypeSystem, tupleType);
if (!target.MatchLdLoca(out v))
{
return(-1);
}
if (this.tupleVariable == null)
{
this.tupleVariable = v;
this.tupleType = (TupleType)tupleType;
this.deconstructionResults = new ILVariable[this.tupleType.Cardinality];
}
if (this.tupleType.Cardinality < 2)
{
return(-1);
}
if (v != tupleVariable || !this.tupleType.Equals(tupleType))
{
return(-1);
}
if (this.deconstructionResults[index] == null)
{
var freshVar = new ILVariable(VariableKind.StackSlot, this.tupleType.ElementTypes[index])
{
Name = "E_" + index
};
delayedActions += _ => context.Function.Variables.Add(freshVar);
this.deconstructionResults[index] = freshVar;
}
delayedActions += _ => {
inst.ReplaceWith(new LdLoc(this.deconstructionResults[index]));
};
return(index);
}
return(-1);
}