什么是编译器工具链？

Question

在最新的CS:GO 更新中，一位阀门开发人员在reddit post 上对此发表了评论：

我们正在升级用于构建 CS:GO 的编译器工具链。这 预发布分支具有使用新工具链构建的 CS:GO。我们是 将其作为预发布分支发布，以便在它之前进行测试 在下次更新中使用。

没有预期的功能变化，虽然新的编译器 工具链可能会产生小的性能提升。

谁能解释一下什么是编译器工具链？

Answer 1

工具链是一组工具（工具链），用于创建编程产品（可运行/可执行程序等）。

通常在嵌入式世界中使用工具链进行交叉编译，这意味着在主机上创建最终将在不同类型的目标上运行的程序 - 因此需要使用特定的编译器、链接器、调试器等

为了从头开始为目标创建编译器，您需要使用特定工具链交叉编译它 - 即编译器工具链。 因此，通过使用编译器工具链，您将能够为您的目标系统创建编译器。

Answer 2

编译器工具链是一组工具、支持库和头文件，可帮助将程序从源代码构建为可在机器上运行的可执行文件。要查看在编译过程中调用了哪些不同的工具，请传递“-v”标志。例如，gcc -v hello.c 将打印以下内容（注意 cmets # 是我的）：

$ /usr/local/Cellar/gcc/11.2.0/bin/gcc-11 -v hello.c

# Configuration options which were used to build gcc itself.
Using built-in specs.
COLLECT_GCC=/usr/local/Cellar/gcc/11.2.0/bin/gcc-11
COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc/11.2.0/libexec/gcc/x86_64-apple-darwin20/11.2.0/lto-wrapper
Target: x86_64-apple-darwin20
Configured with: ../configure --prefix=/usr/local/Cellar/gcc/11.2.0 --libdir=/usr/local/Cellar/gcc/11.2.0/lib/gcc/11 --disable-nls --enable-checking=release --enable-languages=c,c++,objc,obj-c++,fortran,d --program-suffix=-11 --with-gmp=/usr/local/opt/gmp --with-mpfr=/usr/local/opt/mpfr --with-mpc=/usr/local/opt/libmpc --with-isl=/usr/local/opt/isl --with-zstd=/usr/local/opt/zstd --with-pkgversion='Homebrew GCC 11.2.0' --with-bugurl=https://github.com/Homebrew/homebrew-core/issues --enable-libphobos --build=x86_64-apple-darwin20 --with-system-zlib --disable-multilib --without-build-config --with-native-system-header-dir=/usr/include --with-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.2.0 (Homebrew GCC 11.2.0) 
COLLECT_GCC_OPTIONS='-v' '-mmacosx-version-min=11.5.0' '-asm_macosx_version_min=11.5' '-mtune=core2' '-dumpdir' 'a-'

# Compiler invocation of cc1
 /usr/local/Cellar/gcc/11.2.0/libexec/gcc/x86_64-apple-darwin20/11.2.0/cc1 -quiet -v -D__DYNAMIC__ hello.c -fPIC -quiet -dumpdir a- -dumpbase hello.c -dumpbase-ext .c -mmacosx-version-min=11.5.0 -mtune=core2 -version -o /var/folders/1n/lll3n8mj6wj975zjw804hg300000gq/T//ccfvEkdl.s
GNU C17 (Homebrew GCC 11.2.0) version 11.2.0 (x86_64-apple-darwin20)
    compiled by GNU C version 11.2.0, GMP version 6.2.1, MPFR version 4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/local/include"
ignoring nonexistent directory "/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0/../../../../../../x86_64-apple-darwin20/include"
ignoring nonexistent directory "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0/include
 /usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0/include-fixed
 /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include
 /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks
End of search list.
GNU C17 (Homebrew GCC 11.2.0) version 11.2.0 (x86_64-apple-darwin20)
    compiled by GNU C version 11.2.0, GMP version 6.2.1, MPFR version 4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: d0f2649375ab2f2193374e77e0a72e7c
COLLECT_GCC_OPTIONS='-v' '-mmacosx-version-min=11.5.0'  '-mtune=core2' '-dumpdir' 'a-'

# Assembler invocation
 as -arch x86_64 -v -force_cpusubtype_ALL -mmacosx-version-min=11.5 -o /var/folders/1n/lll3n8mj6wj975zjw804hg300000gq/T//cc2nzxXo.o /var/folders/1n/lll3n8mj6wj975zjw804hg300000gq/T//ccfvEkdl.s
Apple clang version 12.0.5 (clang-1205.0.22.9)
Target: x86_64-apple-darwin20.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" -cc1as -triple x86_64-apple-macosx11.5.0 -filetype obj -main-file-name ccfvEkdl.s -target-cpu penryn -fdebug-compilation-dir /Users/Coolest -dwarf-debug-producer "Apple clang version 12.0.5 (clang-1205.0.22.9)" -dwarf-version=4 -mrelocation-model pic -mllvm -disable-aligned-alloc-awareness=1 -o /var/folders/1n/lll3n8mj6wj975zjw804hg300000gq/T//cc2nzxXo.o /var/folders/1n/lll3n8mj6wj975zjw804hg300000gq/T//ccfvEkdl.s
COMPILER_PATH=/usr/local/Cellar/gcc/11.2.0/libexec/gcc/x86_64-apple-darwin20/11.2.0/:/usr/local/Cellar/gcc/11.2.0/libexec/gcc/x86_64-apple-darwin20/11.2.0/:/usr/local/Cellar/gcc/11.2.0/libexec/gcc/x86_64-apple-darwin20/:/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0/:/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/
LIBRARY_PATH=/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0/:/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0/../../../
COLLECT_GCC_OPTIONS='-v' '-mmacosx-version-min=11.5.0'  '-mtune=core2' '-dumpdir' 'a.'
 /usr/local/Cellar/gcc/11.2.0/libexec/gcc/x86_64-apple-darwin20/11.2.0/collect2 -syslibroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/ -dynamic -arch x86_64 -macosx_version_min 11.5.0 -weak_reference_mismatches non-weak -o a.out -L/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0 -L/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0/../../.. /var/folders/1n/lll3n8mj6wj975zjw804hg300000gq/T//cc2nzxXo.o -lSystem -lgcc_ext.10.5 -lgcc -lSystem -no_compact_unwind -v
collect2 version 11.2.0

# linker invocation
/usr/bin/ld -syslibroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/ -dynamic -arch x86_64 -macosx_version_min 11.5.0 -weak_reference_mismatches non-weak -o a.out -L/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0 -L/usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0/../../.. /var/folders/1n/lll3n8mj6wj975zjw804hg300000gq/T//cc2nzxXo.o -lSystem -lgcc_ext.10.5 -lgcc -lSystem -no_compact_unwind -v
@(#)PROGRAM:ld  PROJECT:ld64-650.9
BUILD 00:19:30 Mar 17 2021
configured to support archs: armv6 armv7 armv7s arm64 arm64e arm64_32 i386 x86_64 x86_64h armv6m armv7k armv7m armv7em
Library search paths:
    /usr/local/Cellar/gcc/11.2.0/lib/gcc/11/gcc/x86_64-apple-darwin20/11.2.0
    /usr/local/Cellar/gcc/11.2.0/lib/gcc/11
    /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib
Framework search paths:
    /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/

请注意，编译器工具链是构建可执行文件所必需的，但这还不够。工具链中缺少构建可执行程序所需的“一切”是“sysroot”。

通常，当我们为同一台机器编译程序时，编译器会使用“/usr/include”中可用的标准头文件和“/usr/lib”中的库。这些路径在编译器本身中是硬编码的，因此我们永远不必考虑它。但是，在构建自定义编译器或交叉编译程序时，我们必须通过传递标志来告诉编译器 sysroot 在哪里，例如

gcc --sysroot="/path/to/arm64/sysroot/usr" hello.c

大多数预打包的交叉编译器都附带一个脚本/二进制文件，其中嵌入了“sysroot”路径。例如，aarch64-linux-gnu-gcc (https://packages.ubuntu.com/xenial/devel/gcc-aarch64-linux-gnu)。