Re: [PATCH] target/m68k: Remove unused variable in ABCD/SBCD memory opcodes

[Laurent Vivier]

Le 05/05/2021 à 18:03, Philippe Mathieu-Daudé a écrit :
> The ABCD / SBCD memory opcodes (introduced in commit fb5543d8200)
> don't use their "addr" variable.
> 
> Remove the unused variable and pass a NULL argument instead to
> gen_ea_mode(). This fixes warnings generated when building with
> CFLAGS=-O3 (using GCC 10.2.1 20201125):
> 
>   target/m68k/translate.c: In function ‘disas_sbcd_mem’:
>   target/m68k/translate.c:897:13: warning: ‘addr’ may be used uninitialized 
> in this function [-Wmaybe-uninitialized]
>     897 |             delay_set_areg(s, reg0, tmp, false);
>         |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   target/m68k/translate.c:1866:21: note: ‘addr’ was declared here
>    1866 |     TCGv src, dest, addr;
>         |                     ^~~~
> 
>   target/m68k/translate.c: In function ‘disas_abcd_mem’:
>   target/m68k/translate.c:897:13: warning: ‘addr’ may be used uninitialized 
> in this function [-Wmaybe-uninitialized]
>     897 |             delay_set_areg(s, reg0, tmp, false);
>         |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   target/m68k/translate.c:1829:21: note: ‘addr’ was declared here
>    1829 |     TCGv src, dest, addr;
>         |                     ^~~~
> 

It's really strange because ABCD and SBCD support indirect predecrement (mode 
4, "-(Ay),-(Ax)"), and
if you look into gen_ea_mode() &addr (addrp) is used with mode 4, it is 
initialized on EA_LOADU to
be reused on EA_STORE.

The bug is somewhere else...

Thanks,
Laurent