Connor Abbott <cwabbo...@gmail.com> writes: > On Wed, Aug 6, 2014 at 6:29 PM, Marek Olšák <mar...@gmail.com> wrote: >> What IR? A flatland GLSL IR? A replacement for Mesa IR? Something else? > > It's a flatland IR, similar to TGSI/Direct3D style with enough GLSL > IR-like stuff to get existing things working now and enable us to > eventually do linking in it (so we can use the same optimizations > before linking and after). I was hoping to get a patch series out soon > for discussion, and I've got an experimental i965 fs backend to try it > out. It should be able to replace Mesa IR too, but that's not the > primary goal - it's mostly to be able to do SSA-based optimizations in > a backend-independent way. You can find a branch here: > > https://github.com/cwabbott0/mesa/tree/nir > > but I'd like to wait on discussing it until I put out some patches. > >> >> It's more of a question of which gallium hardware drivers are going to >> support it. I don't think there will be any eager candidates. > > AFAIK almost every HW out there supports predication in one form or > another - why wouldn't it make sense for a higher level part of the > compiler to do e.g. if-conversion based on cost estimates provided by > the driver, similar to how LLVM handles vectorization? That way, it > can take advantage of the fact that things are predicated by being > more aggressive with optimizations like code motion, CSE, etc. - > that's why I originally added support for predication to NIR. Also, > I'm sure that drivers that don't support control flow (i.e. vc4) will > like having the frontend do if-conversion for them and pass along the > predicated code - Eric?
I'd be much more likely to eat whatever TGSI is generated, generate NIR, and then do lowering to predicated moves in NIR.
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