[fpc-devel] FillWord, FillDWord and FillQWord are very poorly optimised on Win64 (not sure about x86-64 on Linux)
pascaldragon at googlemail.com
Wed Nov 1 08:46:03 CET 2017
Am 01.11.2017 05:58 schrieb "J. Gareth Moreton" <gareth at moreton-family.com>:
Would it be worth opening up a bug report for this, with the attached
assembler routines as suggestions? I
haven't worked out how to implement internal functions into the compiler
yet, and I rather clear it with you
guys first before I make such an addition. I had a thought that the simple
routines above could be used for
when compiling for small code size, while larger, more advanced ones are
used for when compiling for speed.
Improvements like these are always welcome. Two points however:
The Fill* routines are not part of the compiler, but of the RTL (the Pascal
routines are in rtl/inc/generic.inc, the assembly ones reside in
rtl/CPU/CPU.inc) and they aren't handled differently depending on the
current optimization flags, so a one-size-fits-all is needed (look at e.g.
the i386 ones).
I also think that you might need to handle memory that isn't correctly
aligned for the assembler instructions (I didn't look at your routines in
detail so I don't know whether they'd need to be adjusted for that). A
check of the i386 routines will probably help here as well.
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