https://bugs.freedesktop.org/show_bug.cgi?id=32271 --- Comment #4 from Marek OlÅÃk <maraeo@xxxxxxxxx> 2010-12-11 01:59:58 PST --- (In reply to comment #3) > (In reply to comment #2) > > I wonder if lowering DDX/DDY to SFL makes any difference compared to using a > > shader that outputs (0,0,0,1). > > The lowering pass I was referring to would happen long before the Mesa IR > level. At that point there is no SFL instruction. We'd just replace the > ir_unop_dFdx and ir_unop_dFdy expressions with constants of 0 in the > appropriate type. Backends (e.g., ir_to_mesa) can convert these constants to > whatever is appropriate. This way backends for GPUs that can't handle these > operations will never even see them. That is, after all, the whole point of > the various lowering passes in the GLSL compiler. :) I meant that it's no longer lowering when you replace a function that returns X with another function that returns 0. It's an incorrect transformation that changes the code to something completely different. Think of my "lowering to SFL" as a way to describe what is going on. -- Configure bugmail: https://bugs.freedesktop.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
