Bug 111071

Created attachment 144710 [details]
bactrace

added backtrace from 
Mesa 19.2.0-devel (git-0cc02c9ea6)


and confirming the fail on earlier mesa (18.0.0)

[den@den-pc Debug]$ ./amber ~/Downloads/nested-ifs-and-return-in-for-loop.amber 
/home/den/Downloads/nested-ifs-and-return-in-for-loop.amber: Line 159: Probe failed at: 0, 0
  Expected RGBA: 255.000000, 0.000000, 0.000000, 255.000000
  Actual RGBA: 255.000000, 255.000000, 255.000000, 255.000000
Probe failed in 1 pixels

Summary of Failures:
  /home/den/Downloads/nested-ifs-and-return-in-for-loop.amber

Summary: 0 pass, 1 fail

will try to look on that

https://gitlab.freedesktop.org/mesa/mesa/merge_requests/1312

That fixes the validation fail and gets us back to rendering the wrong color.  Haven't debugged that issue yet.

Also, are you sure that test is correct?  It's doing

> void main()
> {
>  _GLF_color = vec4(1.0, 0.0, 0.0, 1.0);
>  for(
>      int i = 0;
>      i < 10;
>      i ++
>  )
>   {
>    _GLF_color = vec4(1.0);
>    if(1.0 > injectionSwitch.y)
>     {
>      _GLF_color = vec4(1.0, 0.0, 0.0, 1.0);
>      if(true)
>       {
>        return;
>       }
>     }
>   }
> }

but the input data it sets up has injectionSwitch.y == 1.0 so the if will fail because 1.0 > 1.0 is false and so _GLF_color will get overwritten to vec4(1.0) and never written back to red.  Our compiler seems to be compiling it correctly.

Created attachment 144756 [details]
Rectified test

Thanks for fixing the validation issue, Jason.

My bad regarding the probe in the test - I overlooked that write of vec4(1.0) when writing the probe.

You are correct that white should indeed be rendered.  The attached test case exposes the original bug (the error), and this time really should pass (and indeed does pass on my Mesa 18.0.5 driver).

Fixed by the following commit now in master:

commit 7a19e05e8c84152af3a15868f5ef781142ac8e23
Author: Jason Ekstrand <jason@jlekstrand.net>
Date:   Wed Jul 10 15:14:42 2019 -0500

    nir/opt_if: Clean up single-src phis in opt_if_loop_terminator
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111071
    Fixes: 2a74296f24ba "nir: add opt_if_loop_terminator()"
    Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>