[PATCH] D93585: [AArch64] Enable out-of-line atomics by default.

Tue Dec 22 16:53:06 PST 2020

ilinpv added a comment.

> I think this ought to be a Clang patch that detects which platform and  libgcc it's targeting before adding the attribute.

Do you mean implement in Cland Driver something like:

  Detect runtime library used: 
    if ToolChain::RLT_CompilerRT 
      leave outline atomics enabled
    if ToolChain::RLT_Libgcc 
      run "gcc -dumpfullversion" to get version and disable outline atomics if version < 9.3.1 
    else disable outline atomics

> Most iOS compilation still targets baseline ARMv8.0 so doesn't use LSE. The latest OS still supports phones that lack the instructions, and we'll allow back-deployment of user apps even after that stops being true.

Nice! So iOS will benefit outline atomics too.

Forgot to mention, some outline atomics benchmarks results (compiler-rt and libgcc) were posted here: https://reviews.llvm.org/D91156 https://reviews.llvm.org/D91157

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93585/new/

https://reviews.llvm.org/D93585