[llvm-dev] Clang/LLVM JIT - When to use "registerEHFrames()"

[via llvm-dev]

I'm losing track a little bit...

So... there is no way to make throw and catch working in a jitted code 
under Windows?

Also - to get rid of reallocation problems, it's no help to compile to 
.elf files?

(Sorry Mr. Nash >.<)



From:   Jameson Nash <vtjnash at gmail.com>
To:     Hayden Livingston <halivingston at gmail.com>, 
bjoern.gaier at horiba.com
Cc:     LLVM Developers Mailing List <llvm-dev at lists.llvm.org>, Stefan 
Gränitz <stefan.graenitz at gmail.com>
Date:   16.10.2017 23:04
Subject:        Re: [llvm-dev] Clang/LLVM JIT - When to use 
"registerEHFrames()"



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.


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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