[Bug 79029] INTEL_DEBUG=shader_time is full of lies

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=79029

Kenneth Graunke <kenneth at whitecape.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #2 from Kenneth Graunke <kenneth at whitecape.org> ---
This should pretty much be fixed by:

commit d0575d98fc595dcc17706dc73d1eb461027ca17a
Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Sat Jun 14 03:53:07 2014 -0700

    i965/vec4: Fix dead code elimination for VGRFs of size > 1.

    When faced with code such as:

        mov vgrf31.0:UD, 960D
        mov vgrf31.1:UD, vgrf30.xxxx:UD

    The dead code eliminator didn't consider reg_offsets, so it decided that
    the second instruction was writing was writing to the same register as
    the first one, and eliminated the first one.  But they're actually
    different registers.

    This fixes INTEL_DEBUG=shader_time for vertex shaders.  In the above
    code, vgrf31.0 represents the offset into the shader_time buffer where
    the data should be written, and vgrf31.1 represents the actual time
    data.  With a completely undefined offset, results were...unexpected.

    I think this is probably one of the few cases (maybe only case) where we
    generate multiple MOVs to a large VGRF.  Normally, we just use them as
    texturing results; the other SEND-from-GRF uses a size 1 VGRF.

    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=79029
    Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
    Reviewed-by: Matt Turner <mattst88 at gmail.com>
    Cc: mesa-stable at lists.freedesktop.org

It's at least now giving me data in the same ballpark as the other methods,
though I haven't checked if it's entirely the same.  Thankfully it was
something simple.

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