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From: Laurent Vivier <laurent@vivier.eu>
To: "Philippe Mathieu-Daudé" <f4bug@amsat.org>, qemu-devel@nongnu.org
Cc: Richard Henderson <richard.henderson@linaro.org>
Subject: Re: [PATCH] target/m68k: Remove unused variable in ABCD/SBCD memory opcodes
Date: Wed, 5 May 2021 18:43:25 +0200	[thread overview]
Message-ID: <4c67e219-8698-5855-909b-21fb1c45a385@vivier.eu> (raw)
In-Reply-To: <20210505160344.1394843-1-f4bug@amsat.org>

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


  reply	other threads:[~2021-05-05 17:22 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-05 16:03 [PATCH] target/m68k: Remove unused variable in ABCD/SBCD memory opcodes Philippe Mathieu-Daudé
2021-05-05 16:43 ` Laurent Vivier [this message]
2021-05-06 10:29   ` Laurent Vivier
2021-05-25  8:32     ` Philippe Mathieu-Daudé

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