Re: [Qemu-devel] [PATCH] [S390] Remove warning in tcg stub (tcg_out_reloc)

[Stefan Weil <weil@mail.berlios.de>]

Am 11.05.2010 18:23, schrieb Alexander Graf:
> On S390 we don't have a real TCG implementation but use a stub 
> instead. This
> stub obviously doesn't call any of the TCG helper functions that are 
> usually
> used by the other TCG targets.
>
> If such a helper function is static though, we end up getting a 
> warning that
> turns into an error thanks to Werror. So to successfully compile qemu, 
> we need
> to get rid of it. In this case it's tcg_out_reloc.
>
> To do that, I figured the easiest way is to call tcg_out_reloc with dumb
> parameters after an abort call. That way the code in question never gets
> executed, but we got rid of the warning.
>
> Signed-off-by: Alexander Graf <agraf@suse.de>
> ---
> tcg/s390/tcg-target.c | 6 ++++++
> 1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/tcg/s390/tcg-target.c b/tcg/s390/tcg-target.c
> index 265194a..f1a336d 100644
> --- a/tcg/s390/tcg-target.c
> +++ b/tcg/s390/tcg-target.c
> @@ -35,6 +35,12 @@ static void patch_reloc(uint8_t *code_ptr, int type,
> tcg_target_long value, tcg_target_long addend)
> {
> tcg_abort();
> +
> + /*
> + * XXX We need to call this function at least once, since it's static.
> + * Please remove that code when implementing real s390x tcg support.
> + */
> + tcg_out_reloc(NULL, NULL, 0, 0, 0);
> }
>
> static inline int tcg_target_get_call_iarg_regs_count(int flags)

Won't you get another warning about unreachable code
because tcg_abort never returns?

What about condition compilation for tcg_out_reloc
(don't compile it for hosts which don't need it)?

Regards,
Stefan