+idr On Thu, Oct 19, 2017 at 11:04 AM, Jason Ekstrand <ja...@jlekstrand.net> wrote:
> Not to be confused with variablePointersStorageBuffer which is the > subset of VK_KHR_variable_pointers required to enable the extension. > This gives us "full" support for variable pointers. > > The approach chosen here was to do the lowering to _shared intrinsics > directly in spirv_to_nir instead of using the _var intrinsics and using > nir_lower_io. Pointers with a storage class of Workgroup are given an > implicit std430 layout and now go through the same offset pointer paths as > UBO and SSBO access. The whole thing really ended up working out rather > cleanly. > > There are some downsides to this approach. One, is that we can't delete > unused shared variables post-optimization. Also, the driver may be able to > handle better than std430. Both of these can lead to some waisted SLM > space. This also means that we can't do any deref-based load/store > elimination optimizations on SLM but we didn't really before so that's no > great loss; SLM is now exactly as hard to optimize as SSBOs. > > Connor, Yes, I know that this is not quite the approach you were suggesting > on IRC. I considered how we might add some sort of deref intrinsic and I > don't see a good way of doing so without rewriting large chunks of NIR. I > think that rewrite is probably worth it some day but that day is not today. > We people asking for this feature so I really don't want to delay on a > major NIR rewrite. > > Cc: Connor Abbott <cwabbo...@gmail.com> > Cc: Chad Versace <chadvers...@chromium.org> > Cc: Dave Airlie <airl...@redhat.com> > > Jason Ekstrand (12): > spirv: Drop the impl field from vtn_builder > spirv: Only emit functions which are actually used > spirv: Use a dereference instead of vtn_variable_resource_index > spirv: Add a switch statement for the block store opcode > spirv: Refactor the base case of offset_pointer_dereference > spirv: Convert the supported_extensions struct to spirv_options > spirv: Refactor a couple of pointer query helpers > spirv: Use offset_pointer_dereference to instead of > get_vulkan_resource_index > spirv: Add theoretical support for single component pointers > spirv: Rename get_shared_nir_atomic_op to get_var_nir_atomic_op > spirv: Add support for lowering workgroup access to offsets > anv: Add support for the variablePointers feature > > src/amd/vulkan/radv_shader.c | 23 ++-- > src/compiler/spirv/nir_spirv.h | 34 ++++-- > src/compiler/spirv/spirv_to_nir.c | 180 ++++++++++++++++++++++++----- > src/compiler/spirv/vtn_cfg.c | 4 +- > src/compiler/spirv/vtn_private.h | 30 +++-- > src/compiler/spirv/vtn_variables.c | 229 ++++++++++++++++++++++++------ > ------- > src/intel/vulkan/anv_device.c | 2 +- > src/intel/vulkan/anv_pipeline.c | 25 ++-- > 8 files changed, 372 insertions(+), 155 deletions(-) > > -- > 2.5.0.400.gff86faf > >
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