[PATCH] D142317: [Support][LLD] Avoid using uninitialized threadIndex.

[Alexey Lapshin via Phabricator via llvm-commits]

avl created this revision.
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llvm::parallel::getThreadIndex() is used to get unique index of threads
used with llvm::parallelFor(). Unique threads indexes are assigned in
constructor of ThreadPoolExecutor. The llvm::parallelFor() uses threads
created by ThreadPoolExecutor as well as main thread. The index for the main
thread is not assigned:

  parallel::TaskGroup TG;
  for (; Begin + TaskSize < End; Begin += TaskSize) {
    TG.spawn([=, &Fn] {
      for (size_t I = Begin, E = Begin + TaskSize; I != E; ++I)
        Fn(I);
    });
  }
  for (; Begin != End; ++Begin)    <<<< executed by main thread.
    Fn(Begin);                     <<<<
  return;                          <<<<

This patch assigns index for the main thread and introduces function
which can be used to determine number of threads used by llvm::parallelFor().


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D142317

Files:
  lld/ELF/SyntheticSections.cpp
  lld/ELF/SyntheticSections.h
  lld/ELF/Writer.cpp
  llvm/include/llvm/Support/Parallel.h
  llvm/lib/Support/Parallel.cpp

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