llvm dev - Oct 2017 - Clang/LLVM JIT - When to use "registerEHFrames()"

Hello everyone,

I was following the discussion, but I have to admit, that my skills aren't 
high enough to follow you guys. For my current exception problem, I don't 
have to stick around with the PECOFF format, so I used clang to don't 
compile to a PECOFF, but to a ELF file. Interesting, now I'm missing the 
functions:
__cxa_allocate_exception
__cxa_throw
_ZTI

I loaded the DLL "libstdc++.dll" and found all of the addresses - but
the
application still crashes when the exception is thrown.

So... Do you think, that "Julias Code" could help me? You mentioned
her in
one of the mails, but I don't know her - or her code.

Also, is it a better idea to compile all dynamic code to the ELF format, 
because PECOFF isn't fully supported?

Kind regards
Björn

Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816, 
USt.ID-Nr. DE 114 165 789
Geschäftsführer: Hiroshi Kawamura, Dr Hiroshi Nakamura, Markus Bode, Heiko 
Lampert, Takashi Nagano, Takeshi Fukushima.
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Julia is a language, and you can use their code.

Jameson Nash, could you please let us know why Julia's code has hard
coded values for the unwinding? Is your prolog/epilog some standard
one?

On Fri, Oct 6, 2017 at 2:47 AM,  <bjoern.gaier at horiba.com>
wrote:
> Hello everyone,
>
> I was following the discussion, but I have to admit, that my skills
aren't
> high enough to follow you guys. For my current exception problem, I
don't
> have to stick around with the PECOFF format, so I used clang to don't
> compile to a PECOFF, but to a ELF file. Interesting, now I'm missing
the
> functions:
> __cxa_allocate_exception
> __cxa_throw
> _ZTI
>
> I loaded the DLL "libstdc++.dll" and found all of the addresses -
but the
> application still crashes when the exception is thrown.
>
> So... Do you think, that "Julias Code" could help me? You
mentioned her in
> one of the mails, but I don't know her - or her code.
>
> Also, is it a better idea to compile all dynamic code to the ELF format,
> because PECOFF isn't fully supported?
>
> Kind regards
> Björn
>
> Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
> USt.ID-Nr. DE 114 165 789
> Geschäftsführer: Hiroshi Kawamura, Dr Hiroshi Nakamura, Markus Bode, Heiko
> Lampert, Takashi Nagano, Takeshi Fukushima.

Historically? I implemented support for exceptions back in LLVM 3.3, before
LLVM had an implementation of a Windows unwinder.

Currently? As recent as LLVM 4.0, I don't think the JIT was fully capable
of handling COFF files, and LLVM wouldn't emit the correct sections (with
the COFF-formatted unwind tables) when used in ELF mode.

The prolog is known to be standard since Julia disables FPO on all code, so
the hand-coded values simply needed to declare that to the unwinder.
Windows doesn't have epilog records (it instead infers them from the
structure of the assembly itself, and requires that LLVM only generate
function returns using a particular finite set of instructions), so that
has to be handled elsewhere during machine code selection/emission.


On Tue, Oct 10, 2017 at 11:07 AM Hayden Livingston <halivingston at
gmail.com>
wrote:
> Julia is a language, and you can use their code.
>
> Jameson Nash, could you please let us know why Julia's code has hard
> coded values for the unwinding? Is your prolog/epilog some standard
> one?
>
> On Fri, Oct 6, 2017 at 2:47 AM,  <bjoern.gaier at horiba.com> wrote:
> > Hello everyone,
> >
> > I was following the discussion, but I have to admit, that my skills
> aren't
> > high enough to follow you guys. For my current exception problem, I
don't
> > have to stick around with the PECOFF format, so I used clang to
don't
> > compile to a PECOFF, but to a ELF file. Interesting, now I'm
missing the
> > functions:
> > __cxa_allocate_exception
> > __cxa_throw
> > _ZTI
> >
> > I loaded the DLL "libstdc++.dll" and found all of the
addresses - but the
> > application still crashes when the exception is thrown.
> >
> > So... Do you think, that "Julias Code" could help me? You
mentioned her
> in
> > one of the mails, but I don't know her - or her code.
> >
> > Also, is it a better idea to compile all dynamic code to the ELF
format,
> > because PECOFF isn't fully supported?
> >
> > Kind regards
> > Björn
> >
> > Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
> > USt.ID-Nr. DE 114 165 789
> > Geschäftsführer: Hiroshi Kawamura, Dr Hiroshi Nakamura, Markus Bode,
> Heiko
> > Lampert, Takashi Nagano, Takeshi Fukushima.
>
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