[Mesa-dev] X test suite regression due to gallivm change

Rob Clark robdclark at gmail.com
Fri Feb 24 17:46:02 UTC 2017

On Fri, Feb 24, 2017 at 12:32 PM, Jose Fonseca <jfonseca at vmware.com> wrote:
> On 23/02/17 21:54, Adam Jackson wrote:
>> On Thu, 2017-02-23 at 21:59 +0100, Roland Scheidegger wrote:
>>> So, what does the failing test do?
>> Not much, curiously. There are five that fail and they're all fairly
>> trivial, although the xts harness makes that hard to see.
>> XClearArea/6 and XClearWindow/4 set the window background pixmap to
>> None and calls XClearArea. This should not change any pixels;
>> apparently it does.
>> XClearArea/7 and XClearWindow/5 create a parent window, then a child,
>> sets the parent bg to None, the child to ParentRelative, and clears the
>> child. Again, this should not change anything, but does.
>> XCopyArea/1 creates two windows, tiles the background of the first one
>> (equivalent to ClearWindow), copies from one window to the other, and
>> verifies that the second one has the right content.
>> The first four there are a little strange because, in principle, the
>> thing they're testing is that no rendering happens. Presumably what's
>> being measured is that some _other_ rendering prior to the action under
>> test is being done incorrectly. The CopyArea test is probably closest
>> to the root cause. I'll drill down a bit on exactly what that turns
>> into in terms of GL draws.
>> - ajax
> I'm not sure if apitrace w/ glamor is practical / feasible, but being able
> to repro the issue outside X would be great.

I'm sure Adam knows this already, but for the record (and so I can
find it again 3yrs from now when I need to):

 MESA_EXTENSION_OVERRIDE="-GL_ARB_buffer_storage" apitrace trace
/usr/bin/Xephyr -glamor :1 -screen 1024x768

works like a charm.. I've used it to debug bugs that glamor triggers before


> Another tack on this issue would be to revert parts of
> 320d1191c61a0a82444605c12e5c4b2ee0b241eb separately and see which
> trigger/fix the problem.
> In particular:
> - src/gallium/drivers/llvmpipe/lp_bld_interp.c for interpolation
> - src/gallium/auxiliary/draw/draw_llvm.c for viewport / clipping
> - src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c for TGSI translation
> I tried to use fmad everywhere I could, but it's possible a couple or so is
> simply a bad idea.
> Jose
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