[cfe-dev] asm directive: symbolic label syntax

[Brian Cain via cfe-dev]

Can you post a godbolt link?  that would also show which command line
options you're using.

So this is with gas and -fno-integrated-as?

On Mon, Oct 11, 2021, 1:42 AM Alexander von Below <below at mac.com> wrote:

> Hello,
>
> one thing I should stress: This appears to be a C-Frontend issue (and thus
> I am posting it here) because when using as directly, this problem does not
> occur:
> https://github.com/below/HelloSilicon/blob/main/Chapter%2005/upper.s
>
> I have taken your suggestions: Changing the name of „cont“ to something
> that does not sound like a keyword does not help.
> Adding a ".global _faz\n“ (or ".global faz“) does not change anything,
> neither does „BGT .Lfaz\n“ seem to have any effect.
>
> Let me know if you have any other ideas
>
> Thanks
>
> Alex
>
> > Am 11.10.2021 um 01:59 schrieb Brian Cain <brian.cain at gmail.com>:
> >
> > Does the behavior change if you declare "cont" as a global symbol?  Does
> the symbol have to be "cont"?  Would ".Lcont" suffice?  Many targets treat
> leading ".L" as implicitly local symbols.
> >
> > On Sun, Oct 10, 2021 at 6:30 PM Alexander von Below via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
> > Thanks a lot for your answer, and yes, I do:
> >
> > Working code (using numeric label):
> https://github.com/below/HelloSilicon/blob/main/Chapter%2009/uppertst4.c
> > Non-working (original) code:
> https://github.com/below/HelloSilicon/blob/4c4b2911c43644adfd3b78aee093857444f28472/Chapter%209/uppertst4.c
> >
> > Compile using the makefile in the same folder, or using "clang -o
> uppertst4 uppertst4.c“
> >
> > On godbolt, running the original code through  armv8-a-clang 11.0.1 or
> trunk, everything seems to work fine. There is an unrelated warning, but no
> errors. The output shows both the loop and the cont labels:
> https://godbolt.org/z/xY5afcYdW
> >
> > Compiling the code with the symbolic cont label on an M1 using
> clang-1300.0.29.3 produces the errors:
> >
> > uppertst4.c:22:4: error: conditional branch requires assembler-local
> label. 'cont' is external.
> >                 "BGT    cont\n"
> >                  ^
> > <inline asm>:4:1: note: instantiated into assembly here
> > BGT     cont
> > ^
> > uppertst4.c:24:4: error: conditional branch requires assembler-local
> label. 'cont' is external.
> >                 "BLT    cont\n"
> >                  ^
> > <inline asm>:6:1: note: instantiated into assembly here
> > BLT     cont
> > ^
> > uppertst4.c:28:4: error: conditional branch requires assembler-local
> label. 'loop' is external.
> >                 "B.NE   loop\n"
> >                  ^
> > <inline asm>:10:1: note: instantiated into assembly here
> > B.NE    loop
> > ^
> >
> > Notably, now for both loop and cont, while it is sufficient to replace
> cont with a numeric label.
> >
> > I would be glad to find out if I am doing it wrong, or if this is an
> issue in clang. And now my curiosity is raised why godbolt appears to
> differ from clang on macOS …
> >
> > Thanks again
> >
> > Alex
> >
> >
> > > Am 11.10.2021 um 00:26 schrieb Joerg Sonnenberger via cfe-dev <
> cfe-dev at lists.llvm.org>:
> > >
> > > On Sun, Oct 10, 2021 at 12:27:28PM +0200, Alexander von Below via
> cfe-dev wrote:
> > >> I have tried to adapt gnu as code for Apple Silicon, and I have found
> > >> explanations for most differences. There is one issue I still have:
> > >
> > > Do you actually have a complete self-contained example? Try
> godbolt.org.
> > >
> > > Joerg
> > > _______________________________________________
> > > cfe-dev mailing list
> > > cfe-dev at lists.llvm.org
> > > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> >
> > _______________________________________________
> > cfe-dev mailing list
> > cfe-dev at lists.llvm.org
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> >
> >
> > --
> > -Brian
>
>
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