void InitLocalsRefs2(CilType plainType, BoxedType boxedType, bool arg, int index)
{
if (arg)
{
code.NewInstruction(plainType.LoadOpcode, null, index);
}
else
{
code.NewInstruction(plainType.InitOpcode, null, null);
}
stackMap.PushStack(plainType);
if (boxedType != null)
{
boxedType.BoxValue(code);
}
else if (plainType.IsGenericParameter)
{
GenericUtil.ValueClone(code);
}
else
{
CilMethod.ValueMethod(CilMethod.ValueClone, code);
code.NewInstruction(0xC0 /* checkcast */, plainType, null);
}
code.NewInstruction(0x3A /* astore */, null, index);
stackMap.PopStack(CilMain.Where);
}
void LoadObject(Code cilOp, object data)
{
if (data is TypeReference typeRef)
{
var dataType = CilType.From(typeRef);
var fromType = (CilType)code.StackMap.PopStack(CilMain.Where);
if (CodeSpan.LoadStore(true, fromType, null, dataType, code))
{
return;
}
if ((!dataType.IsReference) && cilOp == Code.Ldobj &&
fromType is BoxedType fromBoxedType &&
dataType.PrimitiveType == fromBoxedType.UnboxedType.PrimitiveType)
{
// 'ldobj primitive' with a corresponding boxed type on the stack.
// we implement by unboxing the boxed type into a primitive value.
fromBoxedType.GetValue(code);
stackMap.PushStack(fromBoxedType.UnboxedType);
return;
}
if (dataType.IsGenericParameter ||
(dataType.IsValueClass && dataType.Equals(fromType)))
{
code.StackMap.PushStack(dataType);
if (SkipClone(cilInst.Next, fromType))
{
// see below for the several cases where we determine
// that we can safely avoid making a clone of the value
code.NewInstruction(0x00 /* nop */, null, null);
}
else if (dataType.IsGenericParameter)
{
GenericUtil.ValueClone(code);
}
else if (cilOp == Code.Ldobj)
{
code.NewInstruction(0x00 /* nop */, null, null);
}
else
{
CilMethod.ValueMethod(CilMethod.ValueClone, code);
}
return;
}
if (dataType.IsReference && cilOp == Code.Box)
{
// 'box' is permitted on reference types, we treat it as a cast
code.StackMap.PushStack(fromType);
CastToClass(data);
return;
}
if (!dataType.IsReference)
{
var boxedType = new BoxedType(dataType, false);
code.StackMap.PushStack(boxedType);
boxedType.BoxValue(code);
return;
}
}
throw new InvalidProgramException();
bool SkipClone(Mono.Cecil.Cil.Instruction next, CilType checkType)
{
if (checkType.IsByReference)
{
return(true);
}
if (next == null)
{
return(false);
}
var op = next.OpCode.Code;
if (IsBrTrueBrFalseIsInst(op))
{
// if 'ldobj' or 'box' is followed by a check for null,
// we don't actually need to clone just for the test
return(true);
}
if (op == Code.Box)
{
if (next.Operand is TypeReference nextTypeRef)
{
// 'ldobj' may be followed by 'box', to load the value
// of a byref value type, and then box it into an object.
// effectively we only need to clone once, in such a case.
return(CilType.From(nextTypeRef).Equals(checkType));
}
}
var(storeType, _) = locals.GetLocalFromStoreInst(op, next.Operand);
if (storeType != null)
{
// 'ldobj' or 'box' may be followed by a store instruction.
// if storing into a variable of the same value type, the
// next instruction will copy the value, so skip clone.
return(storeType.Equals(checkType));
}
if (op == Code.Ret && checkType.IsClonedAtTop)
{
// if the value on the stack was cloned/boxed at the top of
// the method, then we can avoid clone and return it directly.
// see also: CilType.MakeClonedAtTop and its callers.
return(true);
}
if (op == Code.Unbox_Any)
{
if (next.Operand is TypeReference nextTypeRef)
{
// 'ldobj' or 'box' may be followed by 'unbox' and
// then one of the instructions above, e.g. 'brtrue'
// or 'stloc'. we still want to detect such a case
// and prevent a needless clone.
return(SkipClone(next.Next, CilType.From(nextTypeRef)));
}
}
return(false);
}
}
