C/C++|物联网开发入门+项目实战|C语言基础|C语言的预处理及编译过程分析-学习笔记（2）

摘自： 麦子学院-C语言程序设计及快速入门

C语言的预处理及编译过程分析

gcc -v -o build 1.c

输出内容

C:\Users\Vera\Desktop>gcc -v -o build 1.c
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../libexec/gcc/x86_64-w64-mingw32/4.7.0/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../../../build/gcc/src/configure --target=x86_64-w64-mingw32 --prefix=/c/bb/vista64-mingw32/mingw-x86-x86_64/build/build/root --with-sysroot=/c/bb/vista64-mingw32/mingw-x86-x86_64/build/build/root --enable-languages=all,obj-c++ --enable-fully-dynamic-string --disable-multilib
Thread model: win32
gcc version 4.7.0 20111220 (experimental) (GCC)
COLLECT_GCC_OPTIONS='-v' '-o' 'build.exe' '-mtune=generic' '-march=x86-64'
 f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../libexec/gcc/x86_64-w64-mingw32/4.7.0/cc1.exe -quiet -v -iprefix f:\anaconda3\pkgs\mingw-4.7-1\mingw\bin\../lib/gcc/x86_64-w64-mingw32/4.7.0/ -U_REENTRANT 1.c -quiet -dumpbase 1.c -mtune=generic -march=x86-64 -auxbase 1 -version -o C:\Users\Vera\AppData\Local\Temp\ccRFZVtk.s
GNU C (GCC) version 4.7.0 20111220 (experimental) (x86_64-w64-mingw32)
        compiled by GNU C version 4.5.2, GMP version 5.0.1, MPFR version 2.4.2, MPC version 0.8.2
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
ignoring duplicate directory "f:/anaconda3/pkgs/mingw-4.7-1/mingw/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/4.7.0/include"
ignoring nonexistent directory "c:/bb/vista64-mingw32/mingw-x86-x86_64/build/build/rootc:/bb/vista64-mingw32/mingw-x86-x86_64/build/build/root/lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../include"
ignoring duplicate directory "f:/anaconda3/pkgs/mingw-4.7-1/mingw/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/4.7.0/include-fixed"
ignoring duplicate directory "f:/anaconda3/pkgs/mingw-4.7-1/mingw/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include"
ignoring nonexistent directory "c:/bb/vista64-mingw32/mingw-x86-x86_64/build/build/rootc:/mingw/include"
#include "..." search starts here:
#include <...> search starts here:
 f:\anaconda3\pkgs\mingw-4.7-1\mingw\bin\../lib/gcc/x86_64-w64-mingw32/4.7.0/include
 f:\anaconda3\pkgs\mingw-4.7-1\mingw\bin\../lib/gcc/x86_64-w64-mingw32/4.7.0/include-fixed
 f:\anaconda3\pkgs\mingw-4.7-1\mingw\bin\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include
End of search list.
GNU C (GCC) version 4.7.0 20111220 (experimental) (x86_64-w64-mingw32)
        compiled by GNU C version 4.5.2, GMP version 5.0.1, MPFR version 2.4.2, MPC version 0.8.2
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: 6dafe883c1f59de430b201ea1dfaaae8
COLLECT_GCC_OPTIONS='-v' '-o' 'build.exe' '-mtune=generic' '-march=x86-64'
 f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/bin/as.exe -o C:\Users\Vera\AppData\Local\Temp\ccaZqlwM.o C:\Users\Vera\AppData\Local\Temp\ccRFZVtk.s
COMPILER_PATH=f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../libexec/gcc/x86_64-w64-mingw32/4.7.0/;f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../libexec/gcc/;f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/bin/
LIBRARY_PATH=f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/;f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/;f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/lib/../lib/;f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/lib/
COLLECT_GCC_OPTIONS='-v' '-o' 'build.exe' '-mtune=generic' '-march=x86-64'
 f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../libexec/gcc/x86_64-w64-mingw32/4.7.0/collect2.exe --sysroot=c:/bb/vista64-mingw32/mingw-x86-x86_64/build/build/root -m i386pep -Bdynamic -o build.exe f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/lib/../lib/crt2.o f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/lib/../lib/crtbegin.o -Lf:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0 -Lf:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc -Lf:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/lib/../lib -Lf:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/lib C:\Users\Vera\AppData\Local\Temp\ccaZqlwM.o -lmingw32 -lgcc_eh -lgcc -lmoldname -lmingwex -lmsvcrt -ladvapi32 -lshell32 -luser32 -lkernel32 -lmingw32 -lgcc_eh -lgcc -lmoldname -lmingwex -lmsvcrt f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/lib/../lib/crtend.o

主要步骤

预处理（相当于替换）

cpp -o build.i 1.c 相当于gcc -E -o build.i 1.c

示例

修改1.c，加入define：

C:\Users\Vera\Desktop>type 1.c
#include <stdio.h>
#define POLICE  110
int main()
{
    int a =POLICE;
    printf("hello world! 你好\n");
    return 0;
}

C:\Users\Vera\Desktop>gcc -E -o build.i 1.c
显示build.i的内容：

C:\Users\Vera\Desktop>type build.i

输出值：

# 1 "1.c"
# 1 "<command-line>"
# 1 "1.c"
# 1 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/stdio.h" 1 3
# 9 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/stdio.h" 3
# 1 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw.h" 1 3
# 10 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw.h" 3
# 1 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw_mac.h" 1 3
# 32 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw_mac.h" 3

# 41 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw_mac.h" 3

# 11 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw.h" 2 3
# 293 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw.h" 3
# 1 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/vadefs.h" 1 3
# 13 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/vadefs.h" 3
# 1 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw.h" 1 3
# 739 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/_mingw.h" 3
# 1 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/sdks/_mingw_directx.h" 1 3
......
# 1025 "f:\\anaconda3\\pkgs\\mingw-4.7-1\\mingw\\bin\\../lib/gcc/x86_64-w64-mingw32/4.7.0/../../../../x86_64-w64-mingw32/include/stdio.h" 2 3
# 2 "1.c" 2

int main()
{
    int a =110;
    printf("hello world! 你好\n");
    return 0;
}

1、主程序体以上的输出内容是预编译时加入的头文件部分，编译器自动加入；
2、可以看到宏名POLICE已经被110替换了。define，include均在本阶段被执行了，所以本质上将它们都不是关键字（关键字应该由编译器处理）。

编译

第一条调用的命令：f:/anaconda3/pkgs/mingw-4.7-1/mingw/bin/…/libexec/gcc/x86_64-w64-mingw32/4.7.0/cc1.exe … 1.c…-o \ccRFZVtk.s**

cc1.exe称作编译器，相当于gcc -S 1.c ccRFZVtk.s

汇编（让cpu认识代码）

第2条调用的命令：x86_64-w64-mingw32/bin/as.exe …-o \ccaZqlwM.o…\ccRFZVtk.s

上一步的输出文件ccRFZVtk.s作为本次的输入文件，执行as.exe后输出\ccaZqlwM.o文件。
as.exe执行的操作，相当于gcc -c，即先执行编译，再执行汇编，因为不能直接汇编1.c，即-c选项直接生成.o。

链接器（链接系统标准库）

第3条调用的命令：/x86_64-w64-mingw32/4.7.0/collect2.exe -o build.exe 多个.o文件

collect2.exe的操作，相当于gcc -o，已包含了-S,-c的操作。

示例

C:\Users\Vera\Desktop>gcc -S -o build.s 1.c

C:\Users\Vera\Desktop>dir/w
驱动器 C 中的卷是 OS
卷的序列号是 70C8-B66E

C:\Users\Vera\Desktop 的目录

[.] […] 1.c build.s

C:\Users\Vera\Desktop>notepad build.s
这里生成的是x86的汇编代码：

C:\Users\Vera\Desktop>gcc -c -o build.o build.s

C:\Users\Vera\Desktop>dir/w
驱动器 C 中的卷是 OS
卷的序列号是 70C8-B66E

C:\Users\Vera\Desktop 的目录

[.] […] 1.c build.o build.s

C:\Users\Vera\Desktop>notepad build.o
这里生成二进制代码。
C:\Users\Vera\Desktop>gcc -o build 1.c

C:\Users\Vera\Desktop>dir/w
驱动器 C 中的卷是 OS
卷的序列号是 70C8-B66E

C:\Users\Vera\Desktop 的目录

[.] […] 1.c build.exe build.o build.s

C:\Users\Vera\Desktop>build
hello world! 你好