GH-113464: Add a JIT backend for tier 2 (GH-113465)

Add an option (--enable-experimental-jit for configure-based builds
or --experimental-jit for PCbuild-based ones) to build an
*experimental* just-in-time compiler, based on copy-and-patch (https://fredrikbk.com/publications/copy-and-patch.pdf).

See Tools/jit/README.md for more information on how to install the required build-time tooling.

.github/workflows/jit.yml

@@ -0,0 +1,112 @@
+name: JIT
+on:
+  pull_request:
+    paths: '**jit**'
+  push:
+    paths: '**jit**'
+  workflow_dispatch:
+jobs:
+  jit:
+    name: ${{ matrix.target }} (${{ matrix.debug && 'Debug' || 'Release' }})
+    runs-on: ${{ matrix.runner }}
+    strategy:
+      fail-fast: false
+      matrix:
+        target:
+          - i686-pc-windows-msvc/msvc
+          - x86_64-pc-windows-msvc/msvc
+          - x86_64-apple-darwin/clang
+          - x86_64-unknown-linux-gnu/gcc
+          - x86_64-unknown-linux-gnu/clang
+          - aarch64-unknown-linux-gnu/gcc
+          - aarch64-unknown-linux-gnu/clang
+        debug:
+          - true
+          - false
+        llvm:
+          - 16
+        include:
+          - target: i686-pc-windows-msvc/msvc
+            architecture: Win32
+            runner: windows-latest
+            compiler: msvc
+          - target: x86_64-pc-windows-msvc/msvc
+            architecture: x64
+            runner: windows-latest
+            compiler: msvc
+          - target: x86_64-apple-darwin/clang
+            architecture: x86_64
+            runner: macos-latest
+            compiler: clang
+            exclude: test_embed
+          - target: x86_64-unknown-linux-gnu/gcc
+            architecture: x86_64
+            runner: ubuntu-latest
+            compiler: gcc
+          - target: x86_64-unknown-linux-gnu/clang
+            architecture: x86_64
+            runner: ubuntu-latest
+            compiler: clang
+          - target: aarch64-unknown-linux-gnu/gcc
+            architecture: aarch64
+            runner: ubuntu-latest
+            compiler: gcc
+            # These fail because of emulation, not because of the JIT:
+            exclude: test_unix_events test_init test_process_pool test_shutdown test_multiprocessing_fork test_cmd_line test_faulthandler test_os test_perf_profiler test_posix test_signal test_socket test_subprocess test_threading test_venv
+          - target: aarch64-unknown-linux-gnu/clang
+            architecture: aarch64
+            runner: ubuntu-latest
+            compiler: clang
+            # These fail because of emulation, not because of the JIT:
+            exclude: test_unix_events test_init test_process_pool test_shutdown test_multiprocessing_fork test_cmd_line test_faulthandler test_os test_perf_profiler test_posix test_signal test_socket test_subprocess test_threading test_venv
+    env:
+      CC: ${{ matrix.compiler }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Windows
+        if: runner.os == 'Windows'
+        run: |
+          choco install llvm --allow-downgrade --no-progress --version ${{ matrix.llvm }}
+          ./PCbuild/build.bat --experimental-jit ${{ matrix.debug && '-d' || '--pgo' }} -p ${{ matrix.architecture }}
+          ./PCbuild/rt.bat ${{ matrix.debug && '-d' }} -p ${{ matrix.architecture }} -q --exclude ${{ matrix.exclude }} --multiprocess 0 --timeout 3600 --verbose2 --verbose3
+
+      - name: macOS
+        if: runner.os == 'macOS'
+        run: |
+          brew install llvm@${{ matrix.llvm }}
+          export SDKROOT="$(xcrun --show-sdk-path)"
+          ./configure --enable-experimental-jit ${{ matrix.debug && '--with-pydebug' || '--enable-optimizations --with-lto' }}
+          make all --jobs 3
+          ./python.exe -m test --exclude ${{ matrix.exclude }} --multiprocess 0 --timeout 3600 --verbose2 --verbose3
+
+      - name: Native Linux
+        if: runner.os == 'Linux' && matrix.architecture == 'x86_64'
+        run: |
+          sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)" ./llvm.sh ${{ matrix.llvm }}
+          export PATH="$(llvm-config-${{ matrix.llvm }} --bindir):$PATH"
+          ./configure --enable-experimental-jit ${{ matrix.debug && '--with-pydebug' || '--enable-optimizations --with-lto' }}
+          make all --jobs 4
+          ./python -m test --exclude ${{ matrix.exclude }} --multiprocess 0 --timeout 3600 --verbose2 --verbose3
+      - name: Emulated Linux
+        if: runner.os == 'Linux' && matrix.architecture != 'x86_64'
+        run: |
+          sudo bash -c "$(wget -O - https://apt.llvm.org/llvm.sh)" ./llvm.sh ${{ matrix.llvm }}
+          export PATH="$(llvm-config-${{ matrix.llvm }} --bindir):$PATH"
+          ./configure --prefix="$(pwd)/../build"
+          make install --jobs 4
+          make clean --jobs 4
+          export HOST=${{ matrix.architecture }}-linux-gnu
+          sudo apt install --yes "gcc-$HOST" qemu-user
+          ${{ !matrix.debug && matrix.compiler == 'clang' && './configure --enable-optimizations' || '' }}
+          ${{ !matrix.debug && matrix.compiler == 'clang' && 'make profile-run-stamp --jobs 4' || '' }}
+          export CC="${{ matrix.compiler == 'clang' && 'clang --target=$HOST' || '$HOST-gcc' }}"
+          export CPP="$CC --preprocess"
+          export HOSTRUNNER=qemu-${{ matrix.architecture }}
+          export QEMU_LD_PREFIX="/usr/$HOST"
+          ./configure --enable-experimental-jit ${{ matrix.debug && '--with-pydebug' || '--enable-optimizations --with-lto' }} --build=x86_64-linux-gnu --host="$HOST" --with-build-python=../build/bin/python3 --with-pkg-config=no ac_cv_buggy_getaddrinfo=no ac_cv_file__dev_ptc=no ac_cv_file__dev_ptmx=yes
+          make all --jobs 4
+          ./python -m test --exclude ${{ matrix.exclude }} --multiprocess 0 --timeout 3600 --verbose2 --verbose3

.github/workflows/mypy.yml

@@ -12,6 +12,7 @@ on:
       - "Tools/build/generate_sbom.py"
       - "Tools/cases_generator/**"
       - "Tools/clinic/**"
+      - "Tools/jit/**"
       - "Tools/peg_generator/**"
       - "Tools/requirements-dev.txt"
       - "Tools/wasm/**"
@@ -38,6 +39,7 @@ jobs:
           "Tools/build/",
           "Tools/cases_generator",
           "Tools/clinic",
+          "Tools/jit",
           "Tools/peg_generator",
           "Tools/wasm",
         ]