On Tue, Dec 17, 2013 at 10:59 AM, Paul Berry <stereotype...@gmail.com>wrote:
> On 17 December 2013 08:46, Tom Stellard <t...@stellard.net> wrote: > >> On Tue, Dec 17, 2013 at 09:57:31AM -0600, Patrick Baggett wrote: >> > Hi all, >> > >> > Is there a way to see the machine code that is generated by the GLSL >> > compiler for all GPU instruction sets? For example, I would like to >> know if >> > the optimizer optimizes certain (equivalent) constructs (or not), and >> avoid >> > them if possible. I know there is a lot to optimization on GPUs that I >> > don't know, but I'd still like to get some ballpark estimates. For >> example, >> > I'm curious whether: >> >> Each driver has its own environment variable for dumping machine code. >> >> llvmpipe: GALLIVM_DEBUG=asm (I think you need to build mesa >> with --enable-debug for this to work) >> r300g: RADEON_DEBUG=fp,vp >> r600g, radeonsi: R600_DEBUG=ps,vs >> >> I'm not sure what the other drivers use. >> >> -Tom >> > > I believe every driver also supports MESA_GLSL=dump, which prints out the > IR both before and after linking (you'll want to look at the version after > linking to see what optimizations have been applied, since some > optimizations happen at link time). Looking at the IR rather than the > machine code is more likely to give you the information you need, since > Mesa performs the same IR-level optimizations on all architectures, whereas > the optimizations that happen at machine code level are vastly different > from one driver to the next. > > I do want to see both, actually. For example, if a driver implements a specific optimization (machine code level) and another driver clearly does not, then that would be considered "interesting" to me. > Another thing which might be useful to you is Aras Pranckevičius's > "glsl-optimizer" project (https://github.com/aras-p/glsl-optimizer), > which performs Mesa's IR-level optimizations on a shader and then > translates it from IR back to GLSL. > > Paul > > Thanks to everyone for the great tips! > >> > >> > //let p1, p2, p3 be vec2 uniforms >> > >> > vec4(p1, 0, 0) + vec4(p2, 0, 0) + vec4(p3, 0, 1) >> > >> > produces identical machine code as: >> > >> > vec4(p1+p2+p3, 0, 1); >> > >> > for all architectures supported by Mesa. >> >> > _______________________________________________ >> > mesa-dev mailing list >> > mesa-dev@lists.freedesktop.org >> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev >> >> _______________________________________________ >> mesa-dev mailing list >> mesa-dev@lists.freedesktop.org >> http://lists.freedesktop.org/mailman/listinfo/mesa-dev >> > >
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