[Bug 111405] shader_test leads mesa master to an infinity compilation

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=111405

            Bug ID: 111405
           Summary: shader_test leads mesa master to an infinity
                    compilation
           Product: Mesa
           Version: git
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/DRI/i965
          Assignee: intel-3d-bugs at lists.freedesktop.org
          Reporter: andrey.simiklit.1989 at gmail.com
        QA Contact: intel-3d-bugs at lists.freedesktop.org

Created attachment 145070
  --> https://bugs.freedesktop.org/attachment.cgi?id=145070&action=edit
reproducer

While I was trying to create a shader_test for the issue:
https://bugs.freedesktop.org/show_bug.cgi?id=111069
I created a test which leads the latest mesa master to an infinity compilation.

Like in the mentioned issue there is a loop without any exits.
And compiler stucks in an optimization loop because 'progress' always is true.
One of optimization can't stop some constants generation( here is a part of
nir: 

>   vec1 32 ssa_5 = load_const (0x3fc00000 /* 1.500000 */)
>   vec1 32 ssa_6 = load_const (0x40100000 /* 2.250000 */)
>   vec1 32 ssa_7 = load_const (0x40580000 /* 3.375000 */)
>   ...
>   ...
>   vec1 32 ssa_221 = load_const (0x7ef509be /* 162855721648427948063735027106695872512.000000 */)
>   vec1 32 ssa_222 = load_const (0x7f37c74e /* 244283572331437120269767328686418165760.000000 */)
>   vec1 32 ssa_223 = load_const (0x7f800000 /* inf */)


Possible that this and mentioned issue could be fixed using a single solution
which was mentioned by Jason Ekstrand in the bug111069:
> 1. Detect when we've deleted the last exit of a loop and simply delete the entire loop immediately in nir_opt_dead_cf.
But it is just an assumption.

I am investigating this issue.

-- 
You are receiving this mail because:
You are the assignee for the bug.
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-3d-bugs/attachments/20190815/905ee687/attachment.html>