[FFmpeg-devel] [PATCH] checkasm/blockdsp: don't randomize the buffers for fill_block_tab

[James Almer]

On 5/7/2024 7:49 AM, Andreas Rheinhardt wrote:
> Martin Storsjö:
>> On Mon, 6 May 2024, James Almer wrote:
>>
>>> It ignores and overwrites the previous values.
>>> Fixes running the test under ubsan.
>>>
>>> Signed-off-by: James Almer <jamrial at gmail.com>
>>> ---
>>> tests/checkasm/blockdsp.c | 3 ++-
>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> The change is probably correct, but what issue is ubsan complaining
>> about? If this would just be a dead store of unused random values, that
>> shouldn't be an ubsan issue in general, right?
>>
> 
> UBSan complains about unaligned stores in randomize_buffers; which is
> obvious given that i is incremented by 1, not by 2. I sent a patch that
> fixes this without removing randomization:

There's no reason to keep the randomization for this test. That's why i 
replaced it with a memset instead of fixing the unaligned writes.

> https://ffmpeg.org/pipermail/ffmpeg-devel/2024-May/326945.html
> 
> (Ideally, this test should be extended to cover cases of stride != width.)
> 
> - Andreas
> 
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