[Bug 35257] r300_fragprog_emit.c::emit_alu(): Too many ALU instructions

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=35257

--- Comment #5 from Ian Romanick <idr at freedesktop.org> 2011-03-14 14:08:08 PDT ---
(In reply to comment #4)
> Like Marek said, this isn't a bug it is a hardware limitation.  The only way
> this could work is with changes to Gnome Shell, so you should contact the Gnome
> Shell developers, although they might tell your hardware is unsupported.

Since we know there's a lot of work still to be done in the compiler's higher
level optimization passes, I always feel like this is a bit of a cop out
answer.  The TGSI input is 125 instructions, and it looks like a nightmare of
lowered if-statements.  There are way more CMP/SEQ/MUL sequences than any
program should generate.  Unsurprisingly, the driver chokes on it.  I'm sure
the i915 driver, which has limitations similar to r300, would choke even worse.

Comparing the GLSL to the generated TGSI might reveal some high-level
optimization opportunities that we're missing.  It may also help us give some
suggestions to the gnome-shell folks to make the shader more friendly to older
hardware.  There are, after all, a lot of i915s and r300s out there.

Just for giggles, could we get the output of MESA_GLSL=dump too?  Use the same
procedure as for RADEON_DEBUG=fp.

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