[PATCH] gas: Add AArch64 Windows SEH (pdata/xdata) support

[coshvji cujmlqef]

Hi. The previous patch has other bugs that would break seh on x86_64 so
they are not the same patch, the first one needs to be discarded + i did
not use git send-email because the 587 port was blocked so i resubmitted it
again. Not deliberately try to insult other devs.

Best wishes

On Wed, Aug 5, 2026 at 1:52 PM Jan Beulich <jbeulich@suse.com> wrote:

> On 04.08.2026 20:02, trcrsired wrote:
> > Implement Windows exception-handling (SEH) unwind info generation for
> > the aarch64-w64-mingw32 target in GAS.
> >
> > The existing obj-coff-seh.c only handled x64.  This adds full AArch64
> > support:
> >
> > * .seh_proc/.seh_endprologue and all AArch64 unwind directives
> >   (.seh_alloc_stack, .seh_save_fplr/x, .seh_save_reg/p/p_x,
> >   .seh_save_freg/p/p_x, .seh_save_lrpair, .seh_set_fp, .seh_add_fp,
> >   .seh_handler, etc.)
> > * Correct xdata header layout (FunctionLength / CodeWords / EpilogCount /
> >   E / X bits) matching the MS ARM64 format
> > * Emit the xdata extension word when CodeWords==0 and EpilogCount==0 so
> >   Windows exception parsers do not misread the next entry
> > * Correct opcode encodings for register save pairs (save_regp etc.)
> > * Function length computed from fragment positions instead of
> >   resolve_expression, which failed across fragments
>
> This submission is a little irritating, because work towards the same
> goal is already at v12 [1]. Furthermore, work like this would require
> an S-o-b of yours, in turn (I think) requiring a real name.
>
> Jan
>
> [1] https://sourceware.org/pipermail/binutils/2026-July/150254.html
>
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