[PATCH] D91156: [AArch64] Compiler-rt interface for out-of-line atomics.

[Sebastian Pop via Phabricator via llvm-commits]

sebpop added a comment.

I tested this change on Graviton2 aarch64-linux with `clang -moutline-atomics`.
clang was configured with compiler-rt:

  cmake -v -G Ninja \
    -DCLANG_DEFAULT_RTLIB:STRING=compiler-rt \
    -DLLVM_ENABLE_PROJECTS:STRING="clang;compiler-rt;libunwind" \
    -DCLANG_DEFAULT_UNWINDLIB:STRING=libunwind \
    -DCMAKE_BUILD_TYPE:STRING=Release \
    -DCMAKE_INSTALL_PREFIX:PATH=/home/ubuntu/llvm/usr/ \
    ../llvm

I built and tested https://github.com/xianyi/OpenBLAS and https://github.com/boostorg/boost.git and there are no new fails.
I also tested the micro-benchmark as described in https://reviews.llvm.org/D91157

  + export LD_LIBRARY_PATH=/home/ubuntu/llvm/usr/lib
  + LD_LIBRARY_PATH=/home/ubuntu/llvm/usr/lib
  + /home/ubuntu/llvm/usr/bin/clang++ -o clang-generic-v8 a.cc -std=c++11 -O2 -isystem benchmark/include -Lbenchmark/build/src -lbenchmark -lpthread
  + ./clang-generic-v8
  2020-12-16 23:22:45
  Running ./clang-generic-v8
  Run on (64 X 243.75 MHz CPU s)
  CPU Caches:
    L1 Data 64 KiB (x64)
    L1 Instruction 64 KiB (x64)
    L2 Unified 1024 KiB (x64)
    L3 Unified 32768 KiB (x1)
  Load Average: 0.33, 2.58, 7.68
  ***WARNING*** Library was built as DEBUG. Timings may be affected.
  -------------------------------------------------------------------------
  Benchmark                               Time             CPU   Iterations
  -------------------------------------------------------------------------
  BM_atomic_increment                  9.21 ns         9.21 ns     76001652
  BM_atomic_fetch_add                  9.21 ns         9.21 ns     76021489
  BM_atomic_compare_exchange           7.61 ns         7.61 ns     92024848
  BM_std_atomic_compare_exchange       12.4 ns         12.4 ns     56402874
  + /home/ubuntu/llvm/usr/bin/clang++ -o clang-lse -march=armv8-a+lse a.cc -std=c++11 -O2 -isystem benchmark/include -Lbenchmark/build/src -lbenchmark -lpthread
  + ./clang-lse
  2020-12-16 23:22:49
  Running ./clang-lse
  Run on (64 X 243.75 MHz CPU s)
  CPU Caches:
    L1 Data 64 KiB (x64)
    L1 Instruction 64 KiB (x64)
    L2 Unified 1024 KiB (x64)
    L3 Unified 32768 KiB (x1)
  Load Average: 0.38, 2.55, 7.64
  ***WARNING*** Library was built as DEBUG. Timings may be affected.
  -------------------------------------------------------------------------
  Benchmark                               Time             CPU   Iterations
  -------------------------------------------------------------------------
  BM_atomic_increment                  7.21 ns         7.21 ns     97070064
  BM_atomic_fetch_add                  7.21 ns         7.21 ns     97124037
  BM_atomic_compare_exchange           7.21 ns         7.21 ns     97134576
  BM_std_atomic_compare_exchange       11.8 ns         11.8 ns     59414449
  + /home/ubuntu/llvm/usr/bin/clang++ -o clang-moutline -moutline-atomics a.cc -std=c++11 -O2 -isystem benchmark/include -Lbenchmark/build/src -lbenchmark -lpthread
  + ./clang-moutline
  2020-12-16 23:22:52
  Running ./clang-moutline
  Run on (64 X 243.75 MHz CPU s)
  CPU Caches:
    L1 Data 64 KiB (x64)
    L1 Instruction 64 KiB (x64)
    L2 Unified 1024 KiB (x64)
    L3 Unified 32768 KiB (x1)
  Load Average: 0.38, 2.55, 7.64
  ***WARNING*** Library was built as DEBUG. Timings may be affected.
  -------------------------------------------------------------------------
  Benchmark                               Time             CPU   Iterations
  -------------------------------------------------------------------------
  BM_atomic_increment                  7.21 ns         7.21 ns     97090953
  BM_atomic_fetch_add                  7.21 ns         7.21 ns     97136432
  BM_atomic_compare_exchange           7.21 ns         7.21 ns     97132760
  BM_std_atomic_compare_exchange       11.6 ns         11.6 ns     60292533


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D91156/new/

https://reviews.llvm.org/D91156