[PATCH] D71059: [LLD][ELF] Add time-trace to ELF LLD (1/2)

[Russell Gallop via Phabricator via llvm-commits]

russell.gallop updated this revision to Diff 236388.
russell.gallop edited the summary of this revision.
russell.gallop added a comment.

I reverted this at the end of last year MacOS build issues.

This new version fixes some build issues on various platforms and with LLVM_ENABLE_THREADS=OFF by using LLVM_THREAD_LOCAL.

Not all minimum host toolchains [1] support thread_local (i.e. Apple Clang 6.0) so this falls back to __thread on MacOS and other platforms which don't advertise it with __has_feature(cxx_thread_local) (even if they support thread_local like gcc). On Windows this uses __declspec(thread) which (from vs2017) is effectively thread_local [2].

This involved rolling back use of unique_ptr to raw pointers.

In time (with higher minimum host tools) LLVM_THREAD_LOCAL could become:

  #if LLVM_ENABLE_THREADS
  #define LLVM_THREAD_LOCAL thread_local
  #else
  #define LLVM_THREAD_LOCAL
  #endif

and this change should still work.

Tested with Linux with clang and gcc host compiler and Windows with MSVC2017. Also tested with LLVM_ENABLE_THREADS=OFF.

[1] https://llvm.org/docs/GettingStarted.html#host-c-toolchain-both-compiler-and-standard-library
[2] https://docs.microsoft.com/en-us/cpp/cpp/thread?view=vs-2017


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71059/new/

https://reviews.llvm.org/D71059

Files:
  llvm/include/llvm/Support/TimeProfiler.h
  llvm/lib/Support/TimeProfiler.cpp

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