Hi, I'm currently working on a glsl to llvm pass that generates LLVM IR from glsl tree for drivers that ships with a LLVM backend. The current code is located here : http://cgit.freedesktop.org/~vlj/mesa in branch glsl-to-llvm3. It is still a work in progress (I'm not fully satisfied by some factorisation and coding style is not consistant atm)
I'm testing it against evergreen at the moment thus namespace are r600 oriented (all the intrinsics are prefixed with llvm.AMDGPU. or llvm.R600.). However I'm trying to make it as driver agnostic as possible. This pass does not try to optimise the code : it does not generate MAD instructions, it does not propagate constant, it does not eliminate dead code like glsl-to-tgsi does. I chose to leave this to LLVM own pass. On the other hand, I try to make the result code as close as possible from the glsl tree : it preserves vector structure (tgsi to llvm does not), it does not convert boolean to int... This allows to find some bugs in the backend that were hidden by glsl-to-tgsi but could appear with a futur OpenCl support. On the other hand r600 backend does not like vectorised input : it generates much more MOV instruction than necessary. I've narrowed the issue : the COPY llvm internal instructions is lowered to 4 MOV even if following instruction overwrite some registers, and the store output instruction fixes the exported register, which is not optimal wrt register coalescing pass. So far I managed to get something like 200 regressions on 7000 passing tests in piglit, but recent changes (ie moving the interpolation logic inside backend) added 100 others regressions in current trunk, because of failing front/back face color issue I'm working on. However I meet some "standardisation" issue at the moment. I work with a single driver that has its own constraint and feature. For instance, I use a single intrinsic to export everything : llvm.AMDGPU.store.output. However there are some special outputs like vertex position and pixel color. I'm planning to add a llvm.AMDGPU.store.position and llvm.AMDGPU.store.color. Transform and Feedback also needs a similar special intrinsic. I'd like to request your feedback and suggestion on my work. Glsl-to-llvm does not calls any gallium function and can also be used by classic dri drivers. I don't know what is the current status of the recently announced llvm i965 compiler, I don't know if it has already its own glsl-to-llvm pass or not. If not, it would be really great if this pass was also shared by i965, as the more drivers use it, the more reliable it is. Regards, Vincent Lejeune _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
