[CAULDRON] Topics for the Toolchain and Linux kernel BoF

[Sam James]

Xi Ruoyao <xry111@xry111.site> writes:

> On Mon, 2024-09-23 at 08:02 +0100, Sam James wrote:
>> Xi Ruoyao <xry111@xry111.site> writes:
>> 
>> > On Thu, 2024-09-12 at 18:13 +0200, Jose E. Marchesi wrote:
>> > > - "noreturn" and jump tables run-time hints
>> > > 
>> > >   It has been expressed on the kernel side the desire of having the C compiler
>> > >   emit run-time hints marking functions that are not supposed to return and
>> > >   also to provide annotations on jump tables.  This is for the benefit of
>> > >   objtool in arm64, see references below.
>> > > 
>> > >   Goal of the discussion:
>> > > 
>> > >   Collect and assess the requirements of these features, discuss their
>> > >   pertinence and the way it could be best implemented.  The outcome of the
>> > >   discussion will then be used to continue the discussion with the clang/llvm
>> > >   and kernel hackers at LPC.
>> > > 
>> > >   References:
>> > >   https://lore.kernel.org/linux-arm-kernel/YyLmhUxTUaNzaieC@hirez.programming.kicks-ass.net/
>> > 
>> > FWIW we are having very similar issues for using objtool in loongarch. 
>> > And we also hit a similar issue with table-based computed goto.  I'm not
>> > sure if the computed goto is an issue for arm64 either.
>> 
>> I brought it up briefly on your behalf.
>> 
>> > 
>> > Some related materials:
>> > 
>> > - https://gcc.gnu.org/PR82365#c13
>> > - https://gcc.gnu.org/PR116483
>> > - https://gcc.gnu.org/pipermail/gcc-patches/2024-July/657641.html
>> > (Nacked off-line)
>
> Is there's something conclusive from the meeting?  I was busy on
> $RANDOM_MESSY_THINGS last week and had not noticed it before.

Sorry, this fell out of my inbox. I don't remember the details -- it was
only a quick interjection and the discussion was moving on through the
remaining topics. I _think_ we ended up talking a bit about SFrames and
about how there's a kind of tangential need for this sort of thing there
too but I might be making that up.

Jose, do you have any notes about it? (Or maybe Indu?)