bench-linux.yml

name: Bench Linux

on:
  # SECURITY INVARIANT: use `pull_request`, NEVER `pull_request_target`.
  # `pull_request` runs fork code with a read-only token and no secrets;
  # `pull_request_target` would expose a read-write token + secrets to
  # untrusted PR code. Benchmarks on PRs are gated by the `benchmarks`
  # environment approval below (see the job's `environment:`); pushes to the
  # default branches run automatically to keep the CodSpeed baseline fresh.
  # `workflow_dispatch` runs are also un-gated (ad-hoc manual runs).
  push:
    branches: [ main, develop, master ]
  pull_request:
    branches: [ main, develop, master ]
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  # Per-ref group: a new push to a PR supersedes that PR's older, not-yet-approved
  # benchmark run (GitHub can't distinguish "waiting for approval" from "running",
  # so cancel-in-progress cancels the stale waiting run too — desired, since the
  # superseded commit's run is stale anyway). Per-ref (not global) so one PR never
  # cancels another PR's or the default branch's run. The approval gate is now the
  # throttle, so global serialization is no longer needed. For default-branch
  # pushes, a rapid second push likewise supersedes the first; CodSpeed still
  # records the latest commit as the baseline.
  group: bench-${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

env:
  CODSPEED_VERSION: v2.3.0

jobs:
  build:
    # OPT-IN GATE: on pull_request, reference the protected `benchmarks`
    # environment so a required reviewer must approve before any PR code runs.
    # On push/workflow_dispatch the name is empty -> no environment -> no gate,
    # so default-branch baseline runs stay automatic.
    environment: ${{ github.event_name == 'pull_request' && 'benchmarks' || '' }}
    runs-on: ${{ matrix.os }}
    env:
      BUILD_CONFIG: "${{ matrix.os }}_${{ matrix.compiler }}_${{ matrix.window }}_${{ matrix.precision_opt == '' && 'double' || matrix.precision_opt == '--enable-float' && 'float' || matrix.precision_opt == '--enable-long-double' && 'long-double' || 'unknown' }}"
    name: "${{ matrix.os }}-${{ matrix.compiler }}-${{ matrix.window }}-${{ matrix.precision_opt == '' && 'double' || matrix.precision_opt == '--enable-float' && 'float' || matrix.precision_opt == '--enable-long-double' && 'long-double' || 'unknown' }}"
    strategy:
      matrix:
        os: ["codspeed-macro"]
        compiler: ["gcc"]
        window: ["kaiserbessel"]
        precision_opt: ["", "--enable-float", "--enable-long-double"]
    steps:    
    - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v6
      with:
        persist-credentials: false

    # - name: Disable initramfs update
    #   run: sudo sed -i 's/yes/no/g' /etc/initramfs-tools/update-initramfs.conf

    # - name: Disable man-db update
    #   run: sudo rm -f /var/lib/man-db/auto-update        

    - name: Install dependencies
      run: |
        sudo apt-get install -y software-properties-common
        sudo add-apt-repository universe
        sudo apt-get update
        sudo apt-get install -y libc6-dbg build-essential cmake libfftw3-dev libomp-dev libatomic1

    - name: Cache CodSpeed integration library
      uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
      id: cache-codspeed
      with:
        path: codspeed-cpp
        key: codspeed-cpp-${{ runner.arch }}-${{ matrix.os }}-${{ env.CODSPEED_VERSION }}

    - name: Checkout CodSpeed integration library
      if: steps.cache-codspeed.outputs.cache-hit != 'true'
      uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v6
      with:
        persist-credentials: false
        repository: CodSpeedHQ/codspeed-cpp
        ref: "${{ env.CODSPEED_VERSION }}"
        path: codspeed-cpp
        submodules: recursive

    - name: CMake — Configure
      shell: bash
      env:
        WINDOW: ${{ matrix.window }}
        PRECISION_OPT: ${{ matrix.precision_opt }}
        COMPILER: ${{ matrix.compiler }}
      run: |
        case "${PRECISION_OPT}" in
          "")                     CMAKE_PREC="" ;;
          "--enable-float")       CMAKE_PREC="-DNFFT_ENABLE_FLOAT=ON" ;;
          "--enable-long-double") CMAKE_PREC="-DNFFT_ENABLE_LONG_DOUBLE=ON" ;;
          *) echo "Unknown PRECISION_OPT '${PRECISION_OPT}'" >&2; exit 1 ;;
        esac
        EXTRA=()
        AGNOSTIC_FLAGS="window:1,openmp:1"
        [ "${PRECISION_OPT}" = "" ] && AGNOSTIC_FLAGS="$AGNOSTIC_FLAGS,precision:1" || AGNOSTIC_FLAGS="$AGNOSTIC_FLAGS,precision:0"
        EXTRA+=( -DNFFT_BENCHMARK_MODE=walltime
                 -DBENCHMARKS_PREFIX="${BUILD_CONFIG}/"
                 -DNFFT_AGNOSTIC_BENCHMARKS="$AGNOSTIC_FLAGS"
                 -DFETCHCONTENT_SOURCE_DIR_CODSPEED="$(pwd)/codspeed-cpp" )
        # -falign-functions/-falign-loops: force deterministic code layout so an
        # unrelated function's hot loop can't shift to a worse alignment when a
        # nearby function changes size (avoids phantom instruction-count regressions).
        cmake -S . -B build-cmake \
          -DCMAKE_C_FLAGS="-O3 -g -fomit-frame-pointer -fstrict-aliasing -ffast-math -falign-functions=64 -falign-loops=32" \
          -DNFFT_WINDOW="${WINDOW}" ${CMAKE_PREC} -DNFFT_ENABLE_OPENMP=ON \
          -DNFFT_ENABLE_EXHAUSTIVE_UNIT_TESTS=OFF \
          -DNFFT_ENABLE_EXAMPLES=OFF -DNFFT_ENABLE_APPLICATIONS=OFF \
          "${EXTRA[@]}"

    - name: CMake — Build
      run: cmake --build build-cmake -j

    - name: CMake — Benchmarks
      uses: CodSpeedHQ/action@a4a36bb07c0638b0b4ca52bf1f3dad1b4289e52f # v4
      with:
        # "walltime" measures real elapsed time instead of the deterministic
        # instruction-count "simulation" build. Must match -DCODSPEED_MODE=walltime
        # in the configure step above. NOTE: walltime on shared GitHub-hosted
        # runners is sensitive to neighbour noise; CodSpeed recommends their
        # hosted macro runners for stable walltime data.
        mode: walltime
        run: |
          ./build-cmake/benchmarks/bench_nfft_direct
          if [ -x ./build-cmake/benchmarks/bench_nfft_direct_omp ]; then
            ./build-cmake/benchmarks/bench_nfft_direct_omp
          fi
          ./build-cmake/benchmarks/bench_nfct_direct
          if [ -x ./build-cmake/benchmarks/bench_nfct_direct_omp ]; then
            ./build-cmake/benchmarks/bench_nfct_direct_omp
          fi
          ./build-cmake/benchmarks/bench_nfst_direct
          if [ -x ./build-cmake/benchmarks/bench_nfst_direct_omp ]; then
            ./build-cmake/benchmarks/bench_nfst_direct_omp
          fi