-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Marek Olšák wrote: > On Tue, Aug 31, 2010 at 7:20 PM, Ian Romanick <i...@freedesktop.org > <mailto:i...@freedesktop.org>> wrote: > Marek Ol?ák wrote: >> a D3D10 feature), which kind of makes this optimization a no-go. I >> suggest using SEQ instead: > >> bvec4 selector = equal(vec4(i), vec4(0,1,2,3)); >> float f = dot(v, vec4(selector)); > >> which should end up being just SEQ followed by DP4. > > SEQ isn't part of the ARB_fragment_program / ARB_vertex_program > instruction set either. Does R300 support that? I won't be surprised > if i915 doesn't. Of course, it doesn't support the ARL-based > optimization either. > > >> R500 vertex shaders support SEQ natively. > >> For R300 vertex shaders, SEQ is lowered to a sequence of opcodes SGE, >> SGE, MUL. (because CMP is unsupported in hw) > >> For R300-R500 fragment shaders, SEQ is lowered to a sequence of opcodes >> ADD, CMP. (because SGE is unsupported in hw) > >> SEQ is probably the best "high-level" instruction here, but I am ok with >> anything other than ARL.
Hmm... it sounds like SEQ is the right way to go. We may miss some small optimization opportunities, but variable indexing of a vector happens infrequently enough that it shouldn't be a big deal. Thanks for your input. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkx9ZScACgkQX1gOwKyEAw89FACgigKF/cK4UHg054PSmv3cTHZu jn4An07jZ4pr6g+F/aw4PEE9WmYg1zbl =FO2d -----END PGP SIGNATURE----- _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
