[Bug 34156] r600g performance regression between 780c183b and 862ebb41

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=34156

--- Comment #5 from Dave Witbrodt <dawitbro at sbcglobal.net> 2011-02-18 11:21:39 PST ---
In comment 3, I made two naive attempts to revert the problem commit.  Both
failed, but I am only able to work on this stuff in my spare time -- and I have
not been able to look at this more carefully until today.

I discovered that several commits following the problem commit touch the same
code in 'src/gallium/drivers/r600/r600_shader.c', so today I decided to create
a branch from Mesa master at the last of those commits, revert them in reverse
order, then merge master onto the branch.  I expected to have the benefits of
code added since Feb. 7 without the performance regression identified in this
bug.

The commits involved were:

    $ git log a77e813d^..HEAD src/gallium/drivers/r600/r600_shader.c

    commit 077c448d184799e0d9ec962013ec784c6a5c1807
    Author: Henri Verbeet <hverbeet at gmail.com>
    Date:   Mon Feb 7 15:22:08 2011 +0100

        r600g: Add support for relative addressing on constant buffers.

    commit 7687eabaa0470261e059a2d6502628fffd209345
    Author: Henri Verbeet <hverbeet at gmail.com>
    Date:   Mon Feb 7 15:22:07 2011 +0100

        r600g: Split constants in r600_shader_from_tgsi().

    commit 1fa95c7f9e7f1b63364b1f9c6289690418cf6313
    Author: Henri Verbeet <hverbeet at gmail.com>
    Date:   Mon Feb 7 15:22:07 2011 +0100

        r600g: Do the tgsi_full_src_register to r600_shader_src conversion in
    r600_s

    commit a77e813de32643ae2dfffd7ad12abed596172cab
    Author: Henri Verbeet <hverbeet at gmail.com>
    Date:   Mon Feb 7 15:22:07 2011 +0100

        r600g: Split r600_bc_alu_src.

I branched from 077c448d, reverted each of these, then merged master onto the
branch.  It merged cleanly.

Unfortunately, this did not restore performance.  From that, I am concluding
that later code changes introduced at least one other regression.  I will be
busy with other tasks for the rest of the day, but tomorrow I will try some
more involved attempts to find out what is going on.

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