protected internal override void VisitLdElema(LdElema inst)
{
base.VisitLdElema(inst);
CleanUpArrayIndices(inst.Indices);
if (IndexRangeTransform.HandleLdElema(inst, context))
{
return;
}
}
/// <summary>
/// Called by expression transforms.
/// Handles the `array[System.Index]` cases.
/// </summary>
public static bool HandleLdElema(LdElema ldelema, ILTransformContext context)
{
if (!context.Settings.Ranges)
{
return(false);
}
if (!ldelema.Array.MatchLdLoc(out ILVariable array))
{
return(false);
}
if (ldelema.Indices.Count != 1)
{
return(false); // the index/range feature doesn't support multi-dimensional arrays
}
var index = ldelema.Indices[0];
if (index is CallInstruction call && call.Method.Name == "GetOffset" && call.Method.DeclaringType.IsKnownType(KnownTypeCode.Index))
{
// ldelema T(ldloc array, call GetOffset(..., ldlen.i4(ldloc array)))
// -> withsystemindex.ldelema T(ldloc array, ...)
if (call.Arguments.Count != 2)
{
return(false);
}
if (!(call.Arguments[1].MatchLdLen(StackType.I4, out var arrayLoad) && arrayLoad.MatchLdLoc(array)))
{
return(false);
}
context.Step("ldelema with System.Index", ldelema);
foreach (var node in call.Arguments[1].Descendants)
{
ldelema.AddILRange(node);
}
ldelema.AddILRange(call);
ldelema.WithSystemIndex = true;
// The method call had a `ref System.Index` argument for the this pointer, but we want a `System.Index` by-value.
ldelema.Indices[0] = new LdObj(call.Arguments[0], call.Method.DeclaringType);
return(true);
}
protected internal override void VisitLdElema(LdElema inst)
{
base.VisitLdElema(inst);
CleanUpArrayIndices(inst.Indices);
}
