On Tue, Aug 6, 2013 at 4:14 AM, Christoph Bumiller <e0425...@student.tuwien.ac.at> wrote: > On 06.08.2013 03:28, Kenneth Graunke wrote: >> Many GLSL shaders contain code of the form: >> >> x = condition ? foo : bar >> >> The compiler emits an ir_if tree for this, since each subexpression >> might be a complex tree that could have side-effects and short-circuit >> logic operations. >> >> However, the common case is to simply pick one of two constants or >> variable's values---which is exactly what SEL is for. Replacing IF/ELSE >> with SEL also simplifies the control flow graph, making optimization >> passes which work on basic blocks more effective. >> > > Don't you think something like that should be implemented in common code > so that all drivers can profit ?
We would love that. As part of an work in progress, I'm adding conditional-select to the GLSL IR. We planned a few months ago to do this as a step toward SSA at the IR level, but have only laid a little bit of groundwork in that direction (Ian's vector insert/extract series). Looks like your backend already does SSA. Shouldn't that be implemented in common code? :) > It would be really nice to have more, useful device-independent > optimizations or simplifications like this already done instead of > requiring each driver to re-implement them (or use llvm). Yes, it definitely would. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
