C语言的编译器及编译过程

编译器

GCC

GNU组织开发的开源免费的编译器。

MinGW

Windows操作系统下的GCC。

Clang

Clang 是一个 C++ 编写、基于 LLVM、发布于 LLVM BSD 许可证下的 C/C++/Objective C/Objective C++ 编译器，其目标（之一）就是超越 GCC。Mac系统已去掉GCC，Xcode自带Clang。

Visual C++ :: cl.exe

Microsoft VC++自带的编译器。

MinGW(GCC)的命令

一段hello world

// helloworld.c
#include <stdio.h>
int main() {
printf("hello world\n");
return 0;
}

一步到位的编译指令

gcc helloworld.c -o helloworld
gcc helloworld.c -o helloworld.exe

会在当前目录生成

helloworld.exe

可执行文件。

如果不使用

-o

，默认生成

a.exe

可执行文件

gcc helloworld.c

会在当前目录生成

a.exe

可执行文件。

实际上，上述编译过程是分为四个阶段进行的，即预处理(也称预编译，Preprocessing)、编译(Compilation)、汇编 (Assembly)和链接(Linking)。

(1) 预处理

gcc -E helloworld.c -o helloworld.i

会在当前目录生成

helloworld.i

文件。

如果不使用

-o

，则会把预处理后的内容(即上面helloworld.i中的内容)输出到命令行窗口中。

gcc -E helloworld.c

预处理主要做两件事：

一是把预处理语句中的内容替换过来；

二是宏替换。

helloworld.i

仍是C代码，下面把

helloworld.i

中的内容粘贴过来

# 1 "helloworld.c"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "helloworld.c"
# 1 "c:\\mingw\\include\\stdio.h" 1 3
# 19 "c:\\mingw\\include\\stdio.h" 3
# 1 "c:\\mingw\\include\\_mingw.h" 1 3
# 41 "c:\\mingw\\include\\_mingw.h" 3

# 42 "c:\\mingw\\include\\_mingw.h" 3
# 20 "c:\\mingw\\include\\stdio.h" 2 3

# 1 "c:\\mingw\\lib\\gcc\\mingw32\\4.9.3\\include\\stddef.h" 1 3 4
# 212 "c:\\mingw\\lib\\gcc\\mingw32\\4.9.3\\include\\stddef.h" 3 4
typedef unsigned int size_t;
# 324 "c:\\mingw\\lib\\gcc\\mingw32\\4.9.3\\include\\stddef.h" 3 4
typedef short unsigned int wchar_t;
# 353 "c:\\mingw\\lib\\gcc\\mingw32\\4.9.3\\include\\stddef.h" 3 4
typedef short unsigned int wint_t;
# 27 "c:\\mingw\\include\\stdio.h" 2 3

# 1 "c:\\mingw\\lib\\gcc\\mingw32\\4.9.3\\include\\stdarg.h" 1 3 4
# 40 "c:\\mingw\\lib\\gcc\\mingw32\\4.9.3\\include\\stdarg.h" 3 4
typedef __builtin_va_list __gnuc_va_list;
# 29 "c:\\mingw\\include\\stdio.h" 2 3
# 130 "c:\\mingw\\include\\stdio.h" 3
typedef struct _iobuf
{
char* _ptr;
int _cnt;
char* _base;
int _flag;
int _file;
int _charbuf;
int _bufsiz;
char* _tmpfname;
} FILE;
# 155 "c:\\mingw\\include\\stdio.h" 3
extern __attribute__ ((__dllimport__)) FILE _iob[];

FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fopen (const char*, const char*);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) freopen (const char*, const char*, FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fflush (FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fclose (FILE*);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) remove (const char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) rename (const char*, const char*);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) tmpfile (void);
char* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) tmpnam (char*);

char* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _tempnam (const char*, const char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _rmtmp(void);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _unlink (const char*);

char* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) tempnam (const char*, const char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) rmtmp(void);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) unlink (const char*);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) setvbuf (FILE*, char*, int, size_t);

void __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) setbuf (FILE*, char*);
# 203 "c:\\mingw\\include\\stdio.h" 3
extern int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __mingw_fprintf(FILE*, const char*, ...);
extern int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __mingw_printf(const char*, ...);
extern int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __mingw_sprintf(char*, const char*, ...);
extern int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __mingw_snprintf(char*, size_t, const char*, ...);
extern int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __mingw_vfprintf(FILE*, const char*, __gnuc_va_list);
extern int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __mingw_vprintf(const char*, __gnuc_va_list);
extern int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __mingw_vsprintf(char*, const char*, __gnuc_va_list);
extern int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __mingw_vsnprintf(char*, size_t, const char*, __gnuc_va_list);
# 292 "c:\\mingw\\include\\stdio.h" 3
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fprintf (FILE*, const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) printf (const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) sprintf (char*, const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vfprintf (FILE*, const char*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vprintf (const char*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vsprintf (char*, const char*, __gnuc_va_list);
# 307 "c:\\mingw\\include\\stdio.h" 3
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __msvcrt_fprintf(FILE*, const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __msvcrt_printf(const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __msvcrt_sprintf(char*, const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __msvcrt_vfprintf(FILE*, const char*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __msvcrt_vprintf(const char*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) __msvcrt_vsprintf(char*, const char*, __gnuc_va_list);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _snprintf (char*, size_t, const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _vsnprintf (char*, size_t, const char*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _vscprintf (const char*, __gnuc_va_list);
# 330 "c:\\mingw\\include\\stdio.h" 3
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) snprintf (char *, size_t, const char *, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vsnprintf (char *, size_t, const char *, __gnuc_va_list);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vscanf (const char * __restrict__, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vfscanf (FILE * __restrict__, const char * __restrict__,
__gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vsscanf (const char * __restrict__,
const char * __restrict__, __gnuc_va_list);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fscanf (FILE*, const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) scanf (const char*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) sscanf (const char*, const char*, ...);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fgetc (FILE*);
char* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fgets (char*, int, FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fputc (int, FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fputs (const char*, FILE*);
char* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) gets (char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) puts (const char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) ungetc (int, FILE*);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _filbuf (FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _flsbuf (int, FILE*);

extern __inline__ int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) getc (FILE* __F)
{
return (--__F->_cnt >= 0)
? (int) (unsigned char) *__F->_ptr++
: _filbuf (__F);
}

extern __inline__ int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) putc (int __c, FILE* __F)
{
return (--__F->_cnt >= 0)
? (int) (unsigned char) (*__F->_ptr++ = (char)__c)
: _flsbuf (__c, __F);
}

extern __inline__ int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) getchar (void)
{
return (--(&_iob[0])->_cnt >= 0)
? (int) (unsigned char) *(&_iob[0])->_ptr++
: _filbuf ((&_iob[0]));
}

extern __inline__ int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) putchar(int __c)
{
return (--(&_iob[1])->_cnt >= 0)
? (int) (unsigned char) (*(&_iob[1])->_ptr++ = (char)__c)
: _flsbuf (__c, (&_iob[1]));}
# 411 "c:\\mingw\\include\\stdio.h" 3
size_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fread (void*, size_t, size_t, FILE*);
size_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fwrite (const void*, size_t, size_t, FILE*);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fseek (FILE*, long, int);
long __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) ftell (FILE*);
void __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) rewind (FILE*);
# 454 "c:\\mingw\\include\\stdio.h" 3
typedef long long fpos_t;

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fgetpos (FILE*, fpos_t*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fsetpos (FILE*, const fpos_t*);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) feof (FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) ferror (FILE*);
# 479 "c:\\mingw\\include\\stdio.h" 3
void __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) clearerr (FILE*);
void __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) perror (const char*);

FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _popen (const char*, const char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _pclose (FILE*);

FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) popen (const char*, const char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) pclose (FILE*);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _flushall (void);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _fgetchar (void);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _fputchar (int);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _fdopen (int, const char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _fileno (FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _fcloseall (void);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _fsopen (const char*, const char*, int);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _getmaxstdio (void);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _setmaxstdio (int);
# 526 "c:\\mingw\\include\\stdio.h" 3
unsigned int __attribute__((__cdecl__)) __mingw_get_output_format (void);
unsigned int __attribute__((__cdecl__)) __mingw_set_output_format (unsigned int);

int __attribute__((__cdecl__)) __mingw_get_printf_count_output (void);
int __attribute__((__cdecl__)) __mingw_set_printf_count_output (int);
# 553 "c:\\mingw\\include\\stdio.h" 3
extern __inline__ __attribute__((__always_inline__)) unsigned int __attribute__((__cdecl__)) _get_output_format (void)
{ return __mingw_get_output_format (); }

extern __inline__ __attribute__((__always_inline__)) unsigned int __attribute__((__cdecl__)) _set_output_format (unsigned int __style)
{ return __mingw_set_output_format (__style); }
# 579 "c:\\mingw\\include\\stdio.h" 3
extern __inline__ __attribute__((__always_inline__)) int __attribute__((__cdecl__)) _get_printf_count_output (void)
{ return 0 ? 1 : __mingw_get_printf_count_output (); }

extern __inline__ __attribute__((__always_inline__)) int __attribute__((__cdecl__)) _set_printf_count_output (int __mode)
{ return 0 ? 1 : __mingw_set_printf_count_output (__mode); }

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fgetchar (void);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fputchar (int);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fdopen (int, const char*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fileno (FILE*);
# 599 "c:\\mingw\\include\\stdio.h" 3
# 1 "c:\\mingw\\include\\sys\\types.h" 1 3
# 35 "c:\\mingw\\include\\sys\\types.h" 3

# 36 "c:\\mingw\\include\\sys\\types.h" 3
# 45 "c:\\mingw\\include\\sys\\types.h" 3
# 1 "c:\\mingw\\lib\\gcc\\mingw32\\4.9.3\\include\\stddef.h" 1 3 4
# 147 "c:\\mingw\\lib\\gcc\\mingw32\\4.9.3\\include\\stddef.h" 3 4
typedef int ptrdiff_t;
# 46 "c:\\mingw\\include\\sys\\types.h" 2 3

# 1 "c:\\mingw\\include\\parts\\time.h" 1 3
# 64 "c:\\mingw\\include\\parts\\time.h" 3
typedef long __time32_t;
typedef long long __time64_t;
# 74 "c:\\mingw\\include\\parts\\time.h" 3
typedef __time32_t time_t;
# 50 "c:\\mingw\\include\\sys\\types.h" 2 3

typedef long _off_t;

typedef _off_t off_t;

typedef unsigned int _dev_t;

typedef _dev_t dev_t;

typedef short _ino_t;

typedef _ino_t ino_t;

typedef int _pid_t;

typedef _pid_t pid_t;

typedef unsigned short _mode_t;

typedef _mode_t mode_t;

typedef int _sigset_t;

typedef _sigset_t sigset_t;

typedef int _ssize_t;

typedef _ssize_t ssize_t;

typedef long long fpos64_t;

typedef long long off64_t;

typedef unsigned long useconds_t __attribute__ ((__deprecated__));
# 600 "c:\\mingw\\include\\stdio.h" 2 3
extern __inline__
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fopen64 (const char* filename, const char* mode)
{ return fopen (filename, mode); }

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fseeko64 (FILE*, off64_t, int);

extern __inline__
off64_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) ftello64 (FILE * stream)
{
fpos_t pos;
if (fgetpos(stream, &pos))
return -1LL;
else
return ((off64_t) pos);
}
# 628 "c:\\mingw\\include\\stdio.h" 3
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fwprintf (FILE*, const wchar_t*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) wprintf (const wchar_t*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _snwprintf (wchar_t*, size_t, const wchar_t*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vfwprintf (FILE*, const wchar_t*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vwprintf (const wchar_t*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _vsnwprintf (wchar_t*, size_t, const wchar_t*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _vscwprintf (const wchar_t*, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fwscanf (FILE*, const wchar_t*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) wscanf (const wchar_t*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) swscanf (const wchar_t*, const wchar_t*, ...);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fgetwc (FILE*);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fputwc (wchar_t, FILE*);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) ungetwc (wchar_t, FILE*);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) swprintf (wchar_t*, const wchar_t*, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vswprintf (wchar_t*, const wchar_t*, __gnuc_va_list);

wchar_t* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fgetws (wchar_t*, int, FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fputws (const wchar_t*, FILE*);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) getwc (FILE*);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) getwchar (void);
wchar_t* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _getws (wchar_t*);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) putwc (wint_t, FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _putws (const wchar_t*);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) putwchar (wint_t);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wfdopen(int, const wchar_t *);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wfopen (const wchar_t*, const wchar_t*);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wfreopen (const wchar_t*, const wchar_t*, FILE*);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wfsopen (const wchar_t*, const wchar_t*, int);
wchar_t* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wtmpnam (wchar_t*);
wchar_t* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wtempnam (const wchar_t*, const wchar_t*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wrename (const wchar_t*, const wchar_t*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wremove (const wchar_t*);
void __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wperror (const wchar_t*);
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _wpopen (const wchar_t*, const wchar_t*);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) snwprintf (wchar_t* s, size_t n, const wchar_t* format, ...);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vsnwprintf (wchar_t* s, size_t n, const wchar_t* format, __gnuc_va_list arg);

int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vwscanf (const wchar_t * __restrict__, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vfwscanf (FILE * __restrict__,
const wchar_t * __restrict__, __gnuc_va_list);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) vswscanf (const wchar_t * __restrict__,
const wchar_t * __restrict__, __gnuc_va_list);
# 690 "c:\\mingw\\include\\stdio.h" 3
FILE* __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) wpopen (const wchar_t*, const wchar_t*);

wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _fgetwchar (void);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _fputwchar (wint_t);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _getw (FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _putw (int, FILE*);

wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fgetwchar (void);
wint_t __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) fputwchar (wint_t);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) getw (FILE*);
int __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) putw (int, FILE*);

# 2 "helloworld.c" 2

int main() {
printf("hello world\n");
return 0;
}

(2) 编译

预处理之后，对生成的

helloworld.i

文件编译，生成汇编代码

gcc -S helloworld.i -o helloworld.s

helloworld.s

中的内容如下

.file   "helloworld.c"
.def    ___main;    .scl    2;  .type   32; .endef
.section .rdata,"dr"
LC0:
.ascii "hello world\0"
.text
.globl  _main
.def    _main;  .scl    2;  .type   32; .endef
_main:
LFB10:
.cfi_startproc
pushl   %ebp
.cfi_def_cfa_offset 8
.cfi_offset 5, -8
movl    %esp, %ebp
.cfi_def_cfa_register 5
andl    $-16, %esp
subl    $16, %esp
call    ___main
movl    $LC0, (%esp)
call    _puts
movl    $0, %eax
leave
.cfi_restore 5
.cfi_def_cfa 4, 4
ret
.cfi_endproc
LFE10:
.ident  "GCC: (GNU) 4.9.3"
.def    _puts;  .scl    2;  .type   32; .endef

(3) 汇编

把

helloworld.s

编译为目标文件

gcc -c helloworld.s -o helloworld.o

helloworld.o

已是二进制文件，无法查看了。

(4) 链接

将目标文件与所需的所有附加的目标文件连接起来，最终生成可执行文件。附加的目标文件包括静态连接库和动态连接库。

这里

helloworld.o

将与Ｃ标准输入输出库进行链接

gcc helloworld.o -o helloworld

生成

helloworld.exe

可执行文件。

乱了，来张图