[fpc-devel] 64 Bit / 32 Bit

Michael Schnell mschnell at lumino.de
Tue Oct 2 10:09:06 CEST 2007

> FPC can create IA32 and AMD64 code, not IA64 code.
That is what I meant by IA 32/64. I did not suppose it can create 
Inatium code :-) .
> A 64-bit OS is necessary.
I suppose this is because the API calls generated are 64 bit. Correct ?
>> Does / can a 64 Bit FPC generated program include 32 Bit code as well so that
>> it can run on a 32 Bit CPU ?
> No.
So you would need to compile/deploy both versions if you want the 
customer to optionally take advantage of 64 bit. No problem IMHO.

I suppose the 64 Bit OS takes care that any 32 bit program can run, 
anyway. Correct ?
> No, because if the program can run on 32-bit, the only adavtage to go for 
> 64-bit is speed. But, FPC generates currently slower 64-bit executables 
> than 32-bit executables.
Oops ?!?! I supposed that using the much greater count of registers in 
64 bit mode could speed up any kind of software. I suppose that the 
experts _are _working on that, though.

Thanks for your answers !

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