I would rather give a hint to change the code - because only for unmanaged types the semantic of FillChar is equal to default().
As for performance - I just ran some benchmarks comparing the way FPC does it and how Delphi does it. xor a register and mov that into place (Delphi way) is faster in all cases I tested. Also once the record is large enough FPC uses rep movs, Delphi does rep stos. rep stos has faster timings that rep movs so I cannot see how it could be faster given the initial overhead to produce the empty temp. > On 19/04/2022 14:49 J. Gareth Moreton via fpc-devel > <fpc-devel@lists.freepascal.org> wrote: > > > Interesting - I wasn't aware of this intrinsic! I'll make a note of > that one. > > It might be useful to transform FillChar calls to the Default intrinsic > at the node level. > > Gareth aka. Kit > > On 19/04/2022 12:43, Stefan Glienke via fpc-devel wrote: > > You are the expert but I am not sure how that can be the case given you > > only need to zero a register and blast that into the record location > > opposed to twice as many mov operations being generated that I have seen > > with the record that Gareth originally posted. > > > >> On 19/04/2022 13:37 Sven Barth via fpc-devel > >> <fpc-devel@lists.freepascal.org> wrote: > >> > >> > >> Stefan Glienke via fpc-devel <fpc-devel@lists.freepascal.org> schrieb am > >> Di., 19. Apr. 2022, 12:38: > >>> If you want to zero small records more efficiently it might be better > >>> using Default(t) for that and looking at optimizing the code the compiler > >>> generates for that as it seems it produces an empty temp variable which > >>> it assigns instead of simply zeroing the record variable where default() > >>> is being assigned to. > >> This was an explicit design choice I made, because it pays of as soon as a > >> second such assignment for the same type is made. > >> > >> Regards, > >> Sven > >> _______________________________________________ > >> fpc-devel maillist - fpc-devel@lists.freepascal.org > >> https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel > > _______________________________________________ > > fpc-devel maillist - fpc-devel@lists.freepascal.org > > https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel > > > > -- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > _______________________________________________ > fpc-devel maillist - fpc-devel@lists.freepascal.org > https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
