CPython

編譯 - 編譯和執行平台相同

Debug 模式:

# CPython source code 已經從自己 Hosting 轉移到 GitHub 上了
$ git clone https://github.com/python/cpython
$ cd cpython
$ ./configure --with-pydebug
$ make -j8
$ ./python -m test -j8

編譯 - 編譯和執行平台不同 - Android

# 下載 Android NDK
mkdir ndk
cd ndk
wget https://dl.google.com/android/repository/android-ndk-r15c-linux-x86_64.zip
unzip android-ndk-r15c-linux-x86_64.zip
cd ../

# 下載 CPython 程式碼
git clone https://github.com/python/cpython
cd cpython
mkdir mybuild

# 編譯 host CPython
# 在 Cross Compile 時需要同版本的 CPython
./configure
make -j BUILDPYTHON=hostpython hostpython PGEN=Parser/hostpgen Parser/hostpgen
mv Parser/hostpgen hostpgen


# 設定 NDK 環境
# ==> 變動區域,自行根據需求更換
export ANDROID_NDK_ROOT="$HOME/ndk/android-ndk-r15c"
export ANDROID_NDK_VERSION="15"
export ANDROID_API="24"
export ANDROID_ARCH="arm"
export GCC_VERSION="4.9"
# 要執行編譯結果的機器
export ANDROID_HOST="arm-linux-androideabi"
# 負責編譯的機器
export ANDROID_BUILD="x86_64-pc-linux-gnu"
export TARGET_ABI="armeabi-v7a"
export TARGET="arm-none-linux-android"
export KERNEL=linux
export MACHINE=x86_64
# ==> 固定區域
export SYSROOT="$ANDROID_NDK_ROOT/platforms/android-$ANDROID_API/arch-$ANDROID_ARCH"
export LLVM_TOOLCHAIN="$ANDROID_NDK_ROOT/toolchains/llvm/prebuilt/$KERNEL-$MACHINE"
# NDK 編譯器現在是 Clang,但是底下仍然需要一些 GCC 的工具
export GCC_TOOLCHAIN_NAME=$ANDROID_HOST-$GCC_VERSION
export GCC_TOOLCHAIN="$ANDROID_NDK_ROOT/toolchains/$GCC_TOOLCHAIN_NAME/prebuilt/$KERNEL-$MACHINE"
export CC="$LLVM_TOOLCHAIN/bin/clang -target $TARGET -gcc-toolchain $GCC_TOOLCHAIN"
export CXX="$LLVM_TOOLCHAIN/bin/clang++ -target $TARGET -gcc-toolchain $GCC_TOOLCHAIN"
export GCC="$GCC_TOOLCHAIN/bin/$ANDROID_HOST-gcc"
export AR="$GCC_TOOLCHAIN/bin/$ANDROID_HOST-ar"
export LD="$GCC_TOOLCHAIN/bin/$ANDROID_HOST-ld"
export RANLIB="$GCC_TOOLCHAIN/bin/$ANDROID_HOST-ranlib"
export READELF="$GCC_TOOLCHAIN/bin/$ANDROID_HOST-readelf"
export STRIP="$GCC_TOOLCHAIN/bin/$ANDROID_HOST-strip --strip-debug --strip-unneeded"
export NDK_FLAGS="--sysroot=$SYSROOT -D__ANDROID_API__=$ANDROID_API -isystem $ANDROID_NDK_ROOT/sysroot/usr/include/$ANDROID_HOST -I$ANDROID_NDK_ROOT/sources/cxx-stl/llvm-libc++/include -L$ANDROID_NDK_ROOT/sources/cxx-stl/llvm-libc++/libs/$TARGET_ABI"
export CPPFLAGS="$CPPFLAGS $NDK_FLAGS"
export CFLAGS="$CFLAGS $NDK_FLAGS -Wno-unused-value -Wno-empty-body -Qunused-arguments -Wno-nullability-completeness"
export LDFLAGS="$LDFLAGS --sysroot=$SYSROOT"

# configure 時也要寫參數
./configure CC="$CC" \
            AR="$AR" \
            LD="$LD" \
            RANLIB="$RANLIB" \
            READELF="$READELF" \
            CPPFLAGS="$CPPFLAGS" \
            LDFLAGS="$LDFLAGS" \
            CFLAGS="$CFLAGS" \
            --host=$ANDROID_HOST \
            --build=$ANDROID_BUILD \
            --enable-shared \
            --enable-ipv6 \
            --without-ensurepip \
            ac_cv_file__dev_ptmx=yes \
            ac_cv_file__dev_ptc=no \
            ac_cv_little_endian_double=yes \
            --prefix=$PWD/mybuild

# Cross Compile,並指定 host CPython
$ make -j CROSS_COMPILE_TARGET=yes HOSTPYTHON=./hostpython HOSTPGEN=./hostpgen
# 安裝到指定資料夾
$ make -j install CROSS_COMPILE_TARGET=yes HOSTPYTHON=./hostpython HOSTPGEN=./hostpgen

開關 CPython 內建 Extension

Modules/Setup.dist

decimal

在改 CPython 的 PKGBUILD 時, 才發現從 3.3 開始支援了一個 library 叫 libmpdec , 用來提升 decimal module 的效能 (libmpdec 是用 C 實作的 library)。

接到 CPython 上的 module 名稱叫作 _decimal , 在 import decimal 時會先去嘗試尋找 _decimal (看系統有沒有 libmpdec) 沒有的話會使用純 Python 實作的 _pydecimal

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