[fpc-devel] fpc_ compilerproc

[J. Gareth Moreton]

If I'm right in thinking, things like "fpc_abs_real" are fallback 
functions that have to be overridden by a platform-specific 
implementation, and return runtime errors if they aren't implemented.  
In many cases, such internal compiler routines are not called at all 
because there's a direct instruction available in the architecture (e.g. 
for integer min and max functions, AArch64 has SMIN and SMAX 
respectively, but x86 doesn't have such direct operations).

I may have gotten a few details wrong - it's been a while since I worked 
on the RTL (last time was to implement a more optimised exponential 
function, and to be cleverer with optimising min/max functions).

Kit

On 25/06/2025 07:07, Mattias Gaertner via fpc-devel wrote:
> Hi,
>
> How do the fpc_ compileprocs in the rtl like fpc_abs_real work?
>
> Some platforms have assembler code, others just raises an error.
>
> They are included by a comment:
>
> { documenting compiler proc. is useless, they shouldn't be used by the 
> user anyways }
> {$ifndef fpdocsystem}
> {$i compproc.inc}
>
> They are included if fpdocsystem is *not* defined, but the comment 
> says they are for documentation only. Confusing.
>
>
> Mattias
>
>
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