[Mesa-dev] gallium bound checking patch broke r600g in weird way

keith whitwell keith.whitwell at gmail.com
Mon Aug 2 15:49:52 PDT 2010

On Mon, Aug 2, 2010 at 3:53 PM, Brian Paul <brianp at vmware.com> wrote:
> On 08/01/2010 01:55 AM, Chia-I Wu wrote:
>> On Sat, Jul 31, 2010 at 7:10 AM, Zack Rusin<zackr at vmware.com>  wrote:
>>> On Friday 30 July 2010 17:51:21 Jakob Bornecrantz wrote:
>>>> On 30 jul 2010, at 14.02, Jakob Bornecrantz wrote:
>>>>> On 30 jul 2010, at 13.32, Brian Paul wrote:
>>>>>> On 07/30/2010 12:38 PM, Jerome Glisse wrote:
>>>>>>> Hi Brian,
>>>>>>> I am facing a strange segfault with r600g on top of lastest git,
>>>>>>> git bisect pointed to gallium: implement bounds checking for
>>>>>>> constant buffers
>>>>>>> My feeling is that it should only affect software pipeline but
>>>>>>> somehow r600g seem to take different path now, attached if full
>>>>>>> but i can't make much sense out of it, do you have a clue on what
>>>>>>> might went wrong ?
>>>>>> I took a quick look but didn't find anything.
>>>>>> Maybe try a make clean and rebuild just in case?
>>>>> I'm getting the same with swrastg on in 32bit VM, "git clean -fdx":ed
>>>>> even.
>>>> Me and Jerome tracked it down to the SSE code generated by the tgsi
>>>> runtime. Exporting GALLIUM_NOSSE avoids the bug. I'm guessing you are
>>>> either using LLVM or 64bit which doesn't have SSE codegen.
>> I am having this warning
>>   draw/draw_vs_sse.c: In function ‘draw_create_vs_sse’:
>>   draw/draw_vs_sse.c:172: warning: assignment from incompatible pointer
>> type
>> It seems the prototype of vs_sse_run_linear was not updated in the commit
>> and
>> the function body is accessing the wrong arguments.
> Dave Airlie fixed this and it seems to resolve the issue (I just tesed with
> and without Dave's fix on 32-bit and it worked for me).
>>> We actually talked about removing the SSE code from draw. We have the
>>> interpreted paths (safe and easier to debug) and the LLVM paths (for
>>> performance) and the no one is too keen to maintain the SSE code.
>>> Unless someone would like to maintain the SSE paths if I'll have a bit of
>>> time
>>> I'm probably going to remove them next week. They'll be still in the git
>>> history if someone will ever want to bring them back but right now they
>>> tend
>>> to crash a bit (like in this case) which is more trouble than it's worth.
>> Yeah, that sounds good.  This is not the first time (#28752) the SSE
>> path gives weird bugs.
> I'd prefer to keep the SSE code for now.  It's sometimes useful for me when
> I'm debugging things to do comparisons between SSE and the TGSI interpreter.
> The code is working fine again.  I'm sorry my change caused such a
> commotion.  I was in a hurry on Friday and just didn't test on 32-bit.

Would comparing between llvm and the interpreter work as well for you Brian?

What about keeping the SSE code but hiding it behind an option and
making LLVM the default?


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