Merge remote-tracking branch 'libm/merge-into-builtins-prep' into absorb-libm

Absorb the libm repository into `compiler-builtins`.

This was done using `git-filter-repo` to ensure hashes mentioned in
commit messages were correctly rewritten, I used the same strategy to
merge `ctest` into `libc` [1] and it worked quite well. Approximately:

    # `git filter-repo` requires a clean clone
    git clone https://github.com/rust-lang/libm.git

    # Move all code to a `libm` subdirectory for all history
    git filter-repo --to-subdirectory-filter libm

    # The default merge messages are "merge pull request #nnn from
    # user/branch". GH links these incorrectly in the new repo, so
    # rewrite messages from `#nnn` to `rust-lang/libm#nnn`.
    echo 'regex:(^|\s)(#\d+)==>\1rust-lang/libm\2' > messages.txt
    git filter-repo --replace-message messages.txt

    # Re-add a remote and push as a new branch
    git remote add upstream https://github.com/rust-lang/libm.git
    git switch -c merge-into-builtins-prep
    git push --set-upstream upstream merge-into-builtins-prep

    # Now in a compiler-builtins, add `libm` as a remote
    git remote add libm https://github.com/rust-lang/libm.git
    git fetch libm

    # Do the merge that creates this commit
    git merge libm/merge-into-builtins-prep --allow-unrelated-histories

The result should be correct git history and blame for all files, with
messages that use correct rewritten hashes when they are referenced.
There is some reorganization and CI work needed, but that will be a
follow up.

After this merges I will need to push tags from `libm`, which I have
already rewritten to include a `libm-` prefix. Old tags in
compiler-builtins should likely also be rewritten to add a prefix (we
already have this for newer tags), but this can be done at any point.

* Original remote: https://github.com/rust-lang/libm.git
* Default HEAD: c94017af75c3ec4616d5b7f9b6b1b3826b934469 ("Migrate all
  crates except `libm` to edition 2024")
* HEAD after rewriting history: 15fb630
  ("Migrate all crates except `libm` to edition 2024")

[1]: rust-lang/libc#4283 (comment)

Author: tgross35

libm/.editorconfig

@@ -0,0 +1,21 @@
+# EditorConfig helps developers define and maintain consistent
+# coding styles between different editors and IDEs
+# editorconfig.org
+
+root = true
+
+[*]
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+indent_style = space
+indent_size = 4
+
+[*.md]
+# double whitespace at end of line
+# denotes a line break in Markdown
+trim_trailing_whitespace = false
+
+[*.yml]
+indent_size = 2

libm/.git-blame-ignore-revs

@@ -0,0 +1,5 @@
+# Use `git config blame.ignorerevsfile .git-blame-ignore-revs` to make
+# `git blame` ignore the following commits.
+
+# Reformat with a new `.rustfmt.toml`
+5882cabb83c30bf7c36023f9a55a80583636b0e8

libm/.github/workflows/main.yaml

@@ -0,0 +1,324 @@
+name: CI
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+concurrency:
+  # Make sure that new pushes cancel running jobs
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTDOCFLAGS: -Dwarnings
+  RUSTFLAGS: -Dwarnings
+  RUST_BACKTRACE: full
+  BENCHMARK_RUSTC: nightly-2025-01-16 # Pin the toolchain for reproducable results
+
+jobs:
+  test:
+    name: Build and test
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+        - target: aarch64-apple-darwin
+          os: macos-15
+          # FIXME: pinned due to https://github.com/llvm/llvm-project/issues/127804
+          channel: nightly-2025-02-07
+        - target: aarch64-unknown-linux-gnu
+          os: ubuntu-24.04-arm
+          # FIXME: pinned due to https://github.com/llvm/llvm-project/issues/127804
+          channel: nightly-2025-02-07
+        - target: aarch64-pc-windows-msvc
+          os: windows-2025
+          build_only: 1 # Can't run on x86 hosts
+        - target: arm-unknown-linux-gnueabi
+          os: ubuntu-24.04
+        - target: arm-unknown-linux-gnueabihf
+          os: ubuntu-24.04
+        - target: armv7-unknown-linux-gnueabihf
+          os: ubuntu-24.04
+        - target: i586-unknown-linux-gnu
+          os: ubuntu-24.04
+        - target: i686-unknown-linux-gnu
+          os: ubuntu-24.04
+        - target: loongarch64-unknown-linux-gnu
+          os: ubuntu-24.04
+        - target: powerpc-unknown-linux-gnu
+          os: ubuntu-24.04
+        - target: powerpc64-unknown-linux-gnu
+          os: ubuntu-24.04
+        - target: powerpc64le-unknown-linux-gnu
+          os: ubuntu-24.04
+        - target: riscv64gc-unknown-linux-gnu
+          os: ubuntu-24.04
+        - target: thumbv6m-none-eabi
+          os: ubuntu-24.04
+        - target: thumbv7em-none-eabi
+          os: ubuntu-24.04
+        - target: thumbv7em-none-eabihf
+          os: ubuntu-24.04
+        - target: thumbv7m-none-eabi
+          os: ubuntu-24.04
+        - target: x86_64-unknown-linux-gnu
+          os: ubuntu-24.04
+        - target: x86_64-apple-darwin
+          os: macos-13
+        - target: wasm32-unknown-unknown
+          os: ubuntu-24.04
+          build_only: 1
+        - target: i686-pc-windows-msvc
+          os: windows-2025
+        - target: x86_64-pc-windows-msvc
+          os: windows-2025
+        - target: i686-pc-windows-gnu
+          os: windows-2025
+          # FIXME: pinned due to https://github.com/rust-lang/rust/issues/136795
+          channel: nightly-2025-02-07-i686-gnu
+        - target: x86_64-pc-windows-gnu
+          os: windows-2025
+          channel: nightly-x86_64-gnu
+    runs-on: ${{ matrix.os }}
+    env:
+      BUILD_ONLY: ${{ matrix.build_only }}
+    steps:
+    - name: Print runner information
+      run: uname -a
+    - uses: actions/checkout@v4
+      with:
+        submodules: true
+    - name: Install Rust (rustup)
+      shell: bash
+      run: |
+        channel="nightly"
+        # Account for channels that have required components (MinGW)
+        [ -n "${{ matrix.channel }}" ] && channel="${{ matrix.channel }}"
+        rustup update "$channel" --no-self-update
+        rustup default "$channel"
+        rustup target add "${{ matrix.target }}"
+        rustup component add clippy llvm-tools-preview
+    - uses: taiki-e/install-action@nextest
+    - uses: Swatinem/rust-cache@v2
+      with:
+        key: ${{ matrix.target }}
+
+    - name: Verify API list
+      if: matrix.os == 'ubuntu-24.04'
+      run: python3 etc/update-api-list.py --check
+
+    # Non-linux tests just use our raw script
+    - name: Run locally
+      if: matrix.os != 'ubuntu-24.04' || contains(matrix.target, 'wasm')
+      shell: bash
+      run: ./ci/run.sh ${{ matrix.target }}
+
+    # Otherwise we use our docker containers to run builds
+    - name: Run in Docker
+      if: matrix.os == 'ubuntu-24.04' && !contains(matrix.target, 'wasm')
+      run: |
+        rustup target add x86_64-unknown-linux-musl
+        cargo generate-lockfile && ./ci/run-docker.sh ${{ matrix.target }}
+
+    - name: Print test logs if available
+      if: always()
+      run: if [ -f "target/test-log.txt" ]; then cat target/test-log.txt; fi
+      shell: bash
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    steps:
+    - uses: actions/checkout@master
+      with:
+        submodules: true
+    - name: Install Rust
+      run: |
+        rustup update nightly --no-self-update
+        rustup default nightly
+        rustup component add clippy
+    - uses: Swatinem/rust-cache@v2
+    - run: cargo clippy --all --all-features --all-targets
+
+  builtins:
+    name: Check use with compiler-builtins
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust
+      run: rustup update nightly --no-self-update && rustup default nightly
+    - uses: Swatinem/rust-cache@v2
+    - run: cargo check --manifest-path crates/compiler-builtins-smoke-test/Cargo.toml
+    - run: cargo test --manifest-path crates/compiler-builtins-smoke-test/Cargo.toml
+
+  benchmarks:
+    name: Benchmarks
+    runs-on: ubuntu-24.04
+    timeout-minutes: 20
+    steps:
+    - uses: actions/checkout@master
+      with:
+        submodules: true
+    - uses: taiki-e/install-action@cargo-binstall
+
+    - name: Set up dependencies
+      run: |
+        sudo apt update
+        sudo apt install -y valgrind gdb libc6-dbg # Needed for iai-callgrind
+        rustup update "$BENCHMARK_RUSTC" --no-self-update
+        rustup default "$BENCHMARK_RUSTC"
+        # Install the version of iai-callgrind-runner that is specified in Cargo.toml
+        iai_version="$(cargo metadata --format-version=1 --features icount |
+           jq -r '.packages[] | select(.name == "iai-callgrind").version')"
+        cargo binstall -y iai-callgrind-runner --version "$iai_version"
+        sudo apt-get install valgrind
+
+    - uses: Swatinem/rust-cache@v2
+
+    - name: Run icount benchmarks
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        PR_NUMBER: ${{ github.event.pull_request.number }}
+      run: ./ci/bench-icount.sh
+
+    - name: Upload the benchmark baseline
+      uses: actions/upload-artifact@v4
+      with:
+        name: ${{ env.BASELINE_NAME }}
+        path: ${{ env.BASELINE_NAME }}.tar.xz
+    
+    - name: Run wall time benchmarks
+      run: |
+        # Always use the same seed for benchmarks. Ideally we should switch to a
+        # non-random generator.
+        export LIBM_SEED=benchesbenchesbenchesbencheswoo!
+        cargo bench --all --features short-benchmarks,build-musl,force-soft-floats
+
+    - name: Print test logs if available
+      if: always()
+      run: if [ -f "target/test-log.txt" ]; then cat target/test-log.txt; fi
+      shell: bash
+
+  msrv:
+    name: Check MSRV
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    env:
+      RUSTFLAGS: # No need to check warnings on old MSRV, unset `-Dwarnings`
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust
+      run: |
+        msrv="$(perl -ne 'print if s/rust-version\s*=\s*"(.*)"/\1/g' libm/Cargo.toml)"
+        echo "MSRV: $msrv"
+        rustup update "$msrv" --no-self-update && rustup default "$msrv"
+    - uses: Swatinem/rust-cache@v2
+    - run: |
+        # FIXME(msrv): Remove the workspace Cargo.toml so 1.63 cargo doesn't see
+        # `edition = "2024"` and get spooked.
+        rm Cargo.toml
+        cargo build --manifest-path libm/Cargo.toml
+
+  rustfmt:
+    name: Rustfmt
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust
+      run: |
+        rustup update nightly --no-self-update
+        rustup default nightly
+        rustup component add rustfmt
+    - run: cargo fmt -- --check
+
+  # Determine which extensive tests should be run based on changed files.
+  calculate_extensive_matrix:
+    name: Calculate job matrix
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    env:
+      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      PR_NUMBER: ${{ github.event.pull_request.number }}
+    outputs:
+      matrix: ${{ steps.script.outputs.matrix }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 100
+      - name: Fetch pull request ref
+        run: git fetch origin "$GITHUB_REF:$GITHUB_REF"
+        if: github.event_name == 'pull_request'
+      - run: python3 ci/ci-util.py generate-matrix >> "$GITHUB_OUTPUT"
+        id: script
+
+  extensive:
+    name: Extensive tests for ${{ matrix.ty }}
+    needs:
+      # Wait on `clippy` so we have some confidence that the crate will build
+      - clippy
+      - calculate_extensive_matrix
+    runs-on: ubuntu-24.04
+    timeout-minutes: 240 # 4 hours
+    strategy:
+      matrix:
+        # Use the output from `calculate_extensive_matrix` to calculate the matrix
+        # FIXME: it would be better to run all jobs (i.e. all types) but mark those that
+        # didn't change as skipped, rather than completely excluding the job. However,
+        # this is not currently possible https://github.com/actions/runner/issues/1985.
+        include: ${{ fromJSON(needs.calculate_extensive_matrix.outputs.matrix).matrix }}
+    env:
+      TO_TEST: ${{ matrix.to_test }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+      - name: Install Rust
+        run: |
+          rustup update nightly --no-self-update
+          rustup default nightly
+      - uses: Swatinem/rust-cache@v2
+      - name: Run extensive tests
+        run: |
+          echo "Tests to run: '$TO_TEST'"
+          if [ -z "$TO_TEST" ]; then
+            echo "No tests to run, exiting."
+            exit
+          fi
+
+          set -x
+
+          # Run the non-extensive tests first to catch any easy failures
+          cargo t --profile release-checked -- "$TO_TEST"
+
+          LIBM_EXTENSIVE_TESTS="$TO_TEST" cargo t \
+            --features build-mpfr,unstable,force-soft-floats \
+            --profile release-checked \
+            -- extensive
+      - name: Print test logs if available
+        run: if [ -f "target/test-log.txt" ]; then cat target/test-log.txt; fi
+        shell: bash
+
+  success:
+    needs:
+      - test
+      - builtins
+      - benchmarks
+      - msrv
+      - rustfmt
+      - extensive
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
+    # GitHub branch protection is exceedingly silly and treats "jobs skipped because a dependency
+    # failed" as success. So we have to do some contortions to ensure the job fails if any of its
+    # dependencies fails.
+    if: always() # make sure this is never "skipped"
+    steps:
+      # Manually check the status of all dependencies. `if: failure()` does not work.
+      - name: check if any dependency failed
+        run: jq --exit-status 'all(.result == "success")' <<< '${{ toJson(needs) }}'

libm/.github/workflows/publish.yaml

@@ -0,0 +1,27 @@
+name: Release-plz
+
+permissions:
+  pull-requests: write
+  contents: write
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  release-plz:
+    name: Release-plz
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Install Rust (rustup)
+        run: rustup update nightly --no-self-update && rustup default nightly
+      - name: Run release-plz
+        uses: MarcoIeni/release-plz-action@v0.5
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}

libm/.gitignore

@@ -0,0 +1,11 @@
+**.bk
+.#*
+/bin
+/math/src
+target
+Cargo.lock
+**.tar.gz
+
+# Benchmark cache
+iai-home
+baseline-*

libm/.gitmodules

@@ -0,0 +1,4 @@
+[submodule "musl"]
+	path = crates/musl-math-sys/musl
+	url = https://git.musl-libc.org/git/musl
+	shallow = true