[PATCH] D44351: [WebAssembly] Add support for thread-local data

[Nicholas Wilson via Phabricator via llvm-commits]

ncw created this revision.
Herald added subscribers: llvm-commits, sunfish, aheejin, kristof.beyls, jgravelle-google, sbc100, dschuff, jfb.

MOSTLY FINISHED - SOME BITS STILL TO TIDY UP

- Enables users to use `static __thread int threadLocalValue` variable declarations
- Enables Musl to use the existing `__builtin_thread_pointer()` intrinsic to read from the "thread-local register" (on x86 that intrinsic would be reading the `%fs` register, on ARM it might be the CP15 register?)

OK, OK, I know Wasm doesn't have threads quite yet - but it will do soon, surely sometime in 2018. At that point having the infrastructure in place would be quite nice.

I'm implementing the Itanium TLS ABI, as on ARM (x86 has a weird legacy model).

TODO:

- Add some tests
- Add an intrinsic `__builtin_wasm_set_thread_pointer()` to allow Musl to initialise its TLS block
- Open the corresponding review for LLD (halfway done, I put it to one side about a month ago)


Repository:
  rL LLVM

https://reviews.llvm.org/D44351

Files:
  include/llvm/BinaryFormat/Wasm.h
  include/llvm/BinaryFormat/WasmRelocs.def
  include/llvm/MC/MCSectionWasm.h
  lib/MC/WasmObjectWriter.cpp
  lib/Object/WasmObjectFile.cpp
  lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
  lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
  lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
  lib/Target/WebAssembly/WebAssemblyISelLowering.h
  lib/Target/WebAssembly/WebAssemblyInstrInfo.td
  lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
  lib/Target/WebAssembly/WebAssemblyMCInstLower.h
  tools/llvm-readobj/WasmDumper.cpp
  tools/yaml2obj/yaml2wasm.cpp

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