Re: [Qemu-devel] [PATCH] Remove left shifts of negative signed integers

[John Snow <jsnow@redhat.com>]

On 06/30/2016 04:11 PM, Peter Maydell wrote:
> On 30 June 2016 at 20:36, John Snow <jsnow@redhat.com> wrote:
>> Another exercise in placating Clang's increasingly strict -Werror mode.
>> Technically, this is undefined behavior. In practice, -N<<M is the same
>> as -(N<<M).
>>
>> Signed-off-by: John Snow <jsnow@redhat.com>
>> ---
>>  hw/audio/fmopl.c      | 2 +-
>>  target-i386/monitor.c | 2 +-
>>  2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/audio/fmopl.c b/hw/audio/fmopl.c
>> index 731110f..de9338b 100644
>> --- a/hw/audio/fmopl.c
>> +++ b/hw/audio/fmopl.c
>> @@ -69,7 +69,7 @@ static int opl_dbg_maxchip,opl_dbg_chip;
>>  /* final output shift , limit minimum and maximum */
>>  #define OPL_OUTSB   (TL_BITS+3-16)             /* OPL output final shift 16bit */
>>  #define OPL_MAXOUT (0x7fff<<OPL_OUTSB)
>> -#define OPL_MINOUT (-0x8000<<OPL_OUTSB)
>> +#define OPL_MINOUT (-(0x8000<<OPL_OUTSB))
> 
> We have been down this path before:
> http://patchwork.ozlabs.org/patch/545238/
> 
> Paolo will doubtless be along with the rant shortly.
> 
> -- PMM
> 

I figured, so I CC'd him. Nobody can say I didn't try.

--js