[PATCH] D76365: [cuda][hip] Add CUDA builtin surface/texture reference support.

[Michael Liao via Phabricator via cfe-commits]

hliao created this revision.
hliao added reviewers: tra, rjmccall, yaxunl.
Herald added a reviewer: a.sidorin.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

- Even though the bindless surface/texture interfaces are promoted, there are still code using surface/texture references. For example, PR#26400 <https://bugs.llvm.org/show_bug.cgi?id=26400> reports the compilation issue for code using `tex2D` with texture references. For better compatibility, this patch proposes the support of surface/texture references.
- Due to the absent documentation and magic headers, it's believed that `nvcc` does use builtins for texture support. From the limited NVVM documentation[^nvvm] and NVPTX backend texture/surface related tests[^test], it's believed that surface/texture references are supported by replacing their reference types, which are annotated with `device_builtin_surface_type`/`device_builtin_texture_type`, with the corresponding handle-like object types, `cudaSurfaceObject_t` or `cudaTextureObject_t`, in the device-side compilation. On the host side, that global handle variables are registered and will be established and updated later when corresponding binding/unbinding APIs are called[^bind]. Surface/texture references are most like device global variables but represented in different types on the host and device sides.
- In this patch, the following changes are proposed to support that behavior: + Refine `device_builtin_surface_type` and `device_builtin_texture_type` attributes to be applied on `Type` decl only to check whether a variable is of the surface/texture reference type. + Add hooks in code generation to replace that reference types with the correponding object types as well as all accesses to them. In particular, `nvvm.texsurf.handle.internal` should be used to load object handles from global reference variables[^texsurf] as well as metadata annotations. + Generate host-side registration with proper template argument parsing.

---

[^nvvm]: https://docs.nvidia.com/cuda/pdf/NVVM_IR_Specification.pdf
[^test]: https://raw.githubusercontent.com/llvm/llvm-project/master/llvm/test/CodeGen/NVPTX/tex-read-cuda.ll
[^bind]: See section 3.2.11.1.2 ``Texture reference API` in CUDA C Programming Guide <https://docs.nvidia.com/cuda/pdf/CUDA_C_Programming_Guide.pdf>.
[^texsurf]: According to NVVM IR, `nvvm.texsurf.handle` should be used.  But, the current backend doesn't have that supported. We may revise that later.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76365

Files:
  clang/include/clang/AST/Type.h
  clang/include/clang/Basic/Attr.td
  clang/include/clang/Basic/AttrDocs.td
  clang/lib/AST/Type.cpp
  clang/lib/CodeGen/CGCUDANV.cpp
  clang/lib/CodeGen/CGCUDARuntime.h
  clang/lib/CodeGen/CGExprAgg.cpp
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/lib/CodeGen/CodeGenTypes.cpp
  clang/lib/CodeGen/TargetInfo.cpp
  clang/lib/CodeGen/TargetInfo.h
  clang/lib/Sema/SemaDeclAttr.cpp
  clang/test/CodeGenCUDA/surface.cu
  clang/test/CodeGenCUDA/texture.cu
  clang/test/SemaCUDA/attr-declspec.cu
  clang/test/SemaCUDA/attributes-on-non-cuda.cu
  llvm/include/llvm/IR/Operator.h

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