[Vm-dev] Funny Floats [WAS OpenSmalltalk current on aarch64]

Nicolas Cellier nicolas.cellier.aka.nice at gmail.com
Fri Dec 6 17:24:47 UTC 2019


 This is because legacy fdlibm relies on pointer aliasing which is
forbidden for some times now (it prevents efficient compiler optimization)
Try replacing fdlibm with https://github.com/nicolas-cellier-aka-nice/fdlibm
It was in our plans to integrate and maintain that replacement in
opensmalltalk until we find a better library (both supported and doing the
right thing)

Le ven. 6 déc. 2019 à 18:22, Tobias Pape <Das.Linux at gmx.de> a écrit :

>
>
> > On 06.12.2019, at 17:46, Christian Kellermann <ckeen at pestilenz.org>
> wrote:
> >
> >
> > * ken.dickey at whidbey.com <ken.dickey at whidbey.com> [191206 17:33]:
> >>
> >> Greetings,
> >>
> >> OK. So current VM on aarch64.  I have an older VM in which floats work
> fine
> >> (same machine).
> >>
> >> I am doing diffs like:
> >>  diff -r {kens-,oscog}vm/platforms/Cross/plugins/FloatMathPlugin
> >>  diff -r {kens-,oscog}vm/platforms/unix/plugins/FloatMathPlugin
> >>  diff -r {kens-,oscog}vm/platforms/Cross/vm
> >>
> >> but not finding differences in float calculations.
> >>
> >> Any hints on where to look for "1.0 = 1.1  --> true" ?? [Same w Squeak
> or
> >> Cuis]
> >
> > Have you tried switching off compiler optimisations? I recall running
> > into similar problems with a newer gcc and turning off optimisations
> > has been a workaround.
>
> I recall such a thing from another thread.
> Apparently using clang also helped, IIRC
>
> Best regards
>         -Tobias
>
>
>
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