[PATCH] D153092: [Clang][CodeGen]`vtable`, `typeinfo` et al. are globals

[Alex Voicu via Phabricator via cfe-commits]

AlexVlx created this revision.
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All data structures and values associated with handling virtual functions / inheritance, as well as RTTI, are globals and thus can only reside in the `global` address space. This was not taken fully taken into account because for most targets, `global` & `generic` appear to coincide. However, on targets where `global` & `generic` `AS`es differ (e.g. AMDGPU), this was problematic, since it led to the generation of invalid `bitcast`s (which would trigger `assert`s in Debug) and less than optimal code. This patch does two things:

- ensures that `vtable`s, `vptr`s, `vtt`s, `typeinfo` are generated in the right AS, and populated accordingly;
- removes a bunch of `bitcast`s which look like left-overs from the typed ptr era.

This is a bit more noisy than I'd have liked, but functionality is somewhat spread out. There's one bit of less than ideal code, stemming from the fact that functions are in the `generic` AS, and thus it's necessary to insert a `constexpr` cast from `generic` to `global` when populating the `vtable`. Adjusting appears disruptive enough to prefer to do it separately (unless I missed something obvious).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D153092

Files:
  clang/lib/CodeGen/CGVTT.cpp
  clang/lib/CodeGen/CGVTables.cpp
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/lib/CodeGen/ItaniumCXXABI.cpp
  clang/test/CodeGenCXX/vtable-align-address-space.cpp
  clang/test/CodeGenCXX/vtable-assume-load-address-space.cpp
  clang/test/CodeGenCXX/vtable-consteval-address-space.cpp
  clang/test/CodeGenCXX/vtable-constexpr-address-space.cpp
  clang/test/CodeGenCXX/vtable-key-function-address-space.cpp
  clang/test/CodeGenCXX/vtable-layout-extreme-address-space.cpp
  clang/test/CodeGenCXX/vtable-linkage-address-space.cpp
  clang/test/CodeGenCXX/vtable-pointer-initialization-address-space.cpp
  clang/test/CodeGenCXX/vtt-address-space.cpp
  clang/test/CodeGenCXX/vtt-layout-address-space.cpp
  clang/test/Headers/hip-header.hip

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