[fpc-devel]PowerPC, TypInfo

Florian Klaempfl F.Klaempfl at gmx.de
Sun Aug 15 00:20:47 CEST 2004

Jonas Maebe wrote:

> On 14 aug 2004, at 21:07, Mattias Gaertner wrote:
>>> The GetOrdProp is used to read boolean values. It reads a longint and
>>> applies "and $ff" to get only the lowest byte. Under PowerPC the boolean
>>> value is stored just like under i386 in the first byte. Reading the
>>> longint under i386 works, but of course it does not under powerpc.
>>> So, either the compiler is wrong or the GetOrdValue function is wrong.
>>> Which one should I report?
>> I just found out, that this is also the case for ShortInt, SmallInt, Word
>> and Byte, but not for enums.
> To me, the fact that it always reads a longint regardless of the size of 
> the property seems to be inherently wrong. What if the last field of a 
> class is a byte? Then you can read past the end of the class, possibly 
> into unallocated memory causing a crash, no?

No. Classes are always allocated on the heap so the memory block is 
always at least a multiple of 4.

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