It appears that the copy propagation pass in the GLSL compiler (in opt_copy_propagation.cpp) doesn't do copy propagation when the components of a variable are initialized separately, like this:
(declare (temporary ) vec4 vec_ctor) (assign (w) (var_ref vec_ctor) (constant float (1.000000)) ) (assign (xyz) (var_ref vec_ctor) (var_ref assignment_tmp@16) ) (assign (xyzw) (var_ref gl_FragColor) (var_ref vec_ctor) ) In the past, this wasn't visible in the Mesa IR output because Mesa IR optimization seems to do the copy propagation. However, glsl_to_tgsi doesn't do copy propagation to output registers - in fact, I believe this is the only case left where ir_to_mesa produces better code than glsl_to_tgsi. I'm not very enthusiastic about the idea adding to the copy propagation pass in glsl_to_tgsi, since this case is something that should really be optimized by the GLSL compiler before it reaches the IR backend. So, is there a reason why the GLSL copy propagation pass doesn't operate per-component? Bryan _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
