Why does CompiledMethod>>#objectAt:put: work no longer on spur?

>
>
> In V3, this works:
> | cm |
> cm := (CompiledMethod newFrom: (ByteString >> #findSubstring:in:startingAt:matchTable:)).
> cm objectAt: 1 put: (cm header bitAnd: 16r1FF bitInvert).
>
> In SPUR, objectAt:put: raises a primitive Failed.
>
> Best regards
>         -Tobias

>
> Note that the CompiledMethod header format has changed. That code now
> erases part of the literal counter in the header, if I am not
> mistaken. The primitive implementation prevents modification of the
> literal count explicitly.
>
> Best regards
> Jakob
>
> 2015-06-25 11:59 GMT+02:00 Tobias Pape <[hidden email]>:
>>
>>
>> In V3, this works:
>> | cm |
>> cm := (CompiledMethod newFrom: (ByteString >> #findSubstring:in:startingAt:matchTable:)).
>> cm objectAt: 1 put: (cm header bitAnd: 16r1FF bitInvert).
>>
>> In SPUR, objectAt:put: raises a primitive Failed.
>>
>> Best regards
>>        -Tobias