Re: [Qemu-devel] [PULL 00/21] tcg patch queue

[Peter Maydell]

On 21 October 2018 at 16:01, Peter Maydell <address@hidden> wrote:
> Any idea what's going on here? tcg/tcg.h has a comment saying
>  * The cmpxchg functions are only defined if HAVE_CMPXCHG128
> so presumably the issue is that the helper-a64 code is
> trying to refer to them anyway. There certainly doesn't
> seem to be any kind of #defining around the listed functions
> in helper-a64.c to stop them being compiled in this situation.
>
> NB: I build with --enable-debug in this tree -- are you
> perhaps accidentally relying on the compiler's optimisation
> to discard these functions if they're not needed?

Adding a #if HAVE_CMPXCHG128 around the helper-a64.c
functions just pushes the link error back a step to the
references to those helpers:
  LINK    aarch64-softmmu/qemu-system-aarch64w.exe
tcg/tcg.o:tcg.c:(.rdata+0x9810): undefined reference to
`helper_paired_cmpxchg64_le_parallel'
tcg/tcg.o:tcg.c:(.rdata+0x9830): undefined reference to
`helper_paired_cmpxchg64_be_parallel'
tcg/tcg.o:tcg.c:(.rdata+0x9840): undefined reference to
`helper_casp_le_parallel'
tcg/tcg.o:tcg.c:(.rdata+0x9850): undefined reference to
`helper_casp_be_parallel'

which in turn I guess is because they're in the array
of all helpers in tcg.c, so we need to also #if out the
prototypes in helper-a64.h, which is awkward because
there we don't have the HAVE_CMPXCHG128 defined...

thanks
-- PMM