[fpc-pascal] options for better performance & declaration of system procedures

Marco van de Voort marcov at stack.nl
Thu Sep 24 12:48:43 CEST 2009

In our previous episode, 章宏九 said:
> I just tried to unfairly compare fpc-compiled binary and gcc-compiled
> binary under my Gentoo box. FPC is incredible. `ps` data shows the fpc
> one costs nearly no memory? But I still notice it is a little slow. It
> usually costs 0.5~1.0 time more than the gcc one. It seems as if fpc
> saves memory in the cost of performance loss. Is it true? If so, is
> there any options for better performance and no such insane memory
> saving?

Performance is not an homogenous entity where you can pull on a lever, and
it will optimize the program in the direction that you imagine.

First you will have to determine what the bottleneck exactly is, and if it
is similar to the bottleneck in your real application.

It might not be related to the actual generated code at all, just a overly
big reliance one bit of library functionality that happens to be slightly
faster in gcc.

It could even be a matter of slightly different defaults, like that FPC has
standard fairly small I/O buffers iirc, and setting larger buffers on I/O
might help.

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