[fpc-devel] Question on updating FPC packages

J. Gareth Moreton gareth at moreton-family.com
Fri Nov 1 01:19:35 CET 2019

To get back on track with uComplex, I didn't change any routines to make 
them inline - they were that way already.  All I did was change the 
parameters to 'const', align the complex type so it is equivalent to 
__m128d so the System V ABI can pass it all in one register, and enable 
vectorcall on Win64 so the same thing can happen on that platform.  Is 
that really too much?

Changing the Win64 build of FPC to default to vectorcall is an option, 
although the option to fall back to the fastcall-based convention needs 
to exist for the sake of interfacing with third-party libraries, and it 
doesn't change the fact that the complex type still needs to be 
aligned.  Either way, it might break assembler code that calls the 
uComplex functions, but my argument still stands that I don't think this 
a realistic set-up in the wide scheme of things.

Gareth aka. Kit

On 31/10/2019 21:13, Florian Klämpfl wrote:
> Am 31.10.19 um 20:11 schrieb Marco van de Voort:
>> Op 2019-10-30 om 23:02 schreef Florian Klämpfl:
>>> Yes. And manually adding inline is only as good as the knowledge of 
>>> the user doing so. If somebody implements it right (I did not, I 
>>> used the easiest approach and used an existing function to estimate 
>>> the complexity of a subroutine). The compiler can just count the 
>>> number of the generate instructions or even calculate the length of 
>>> the procedure and then decide to keep the node tree for inlining.
>> Well, it depends of course of what happens when. Would you really 
>> count final instructions or cycles after all optimization and 
>> peephole passes ?
> This is not really an issue: actually for inlining mainly 
> instructions/code length matters and e.g. the arm compiler even does 
> this (actually something more complex) as it has to insert the 
> constant tables at the right locations into the code because the 
> relative offsets are limited.
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