专题3-1.编译过程简介

1. 编译过程序

编译器做了什么
a:
预编译
•处理所有的注释，以空格代替
•将所有的#define删除，并且展开所有的宏定义
•处理条件编译指令#if, #ifdef, #elif, #else, #endif
•处理#include，展开被包含的文件
•保留编译器需要使用的#pragma指令

//filename: file.c#include<stdio.h>#define HELLO_WORLD "hello world!\n"int main(){printf(HELLO_WORLD);return 0;}

  预处理指令：
gcc –E file.c –o hello.i

在linux gcc环境下执行,看结果.

    结果如下

# 1 "03-1.c"# 1 "<built-in>"# 1 "<command-line>"# 1 "03-1.c"# 1 "/usr/include/stdio.h" 1 3 4# 28 "/usr/include/stdio.h" 3 4# 1 "/usr/include/features.h" 1 3 4# 313 "/usr/include/features.h" 3 4# 1 "/usr/include/bits/predefs.h" 1 3 4# 314 "/usr/include/features.h" 2 3 4# 346 "/usr/include/features.h" 3 4# 1 "/usr/include/sys/cdefs.h" 1 3 4# 353 "/usr/include/sys/cdefs.h" 3 4# 1 "/usr/include/bits/wordsize.h" 1 3 4# 354 "/usr/include/sys/cdefs.h" 2 3 4# 347 "/usr/include/features.h" 2 3 4# 378 "/usr/include/features.h" 3 4# 1 "/usr/include/gnu/stubs.h" 1 3 4# 1 "/usr/include/bits/wordsize.h" 1 3 4# 5 "/usr/include/gnu/stubs.h" 2 3 4# 1 "/usr/include/gnu/stubs-32.h" 1 3 4# 8 "/usr/include/gnu/stubs.h" 2 3 4# 379 "/usr/include/features.h" 2 3 4# 29 "/usr/include/stdio.h" 2 3 4# 1 "/usr/lib/gcc/i486-linux-gnu/4.4.1/include/stddef.h" 1 3 4# 211 "/usr/lib/gcc/i486-linux-gnu/4.4.1/include/stddef.h" 3 4typedef unsigned int size_t;# 35 "/usr/include/stdio.h" 2 3 4# 1 "/usr/include/bits/types.h" 1 3 4# 28 "/usr/include/bits/types.h" 3 4# 1 "/usr/include/bits/wordsize.h" 1 3 4# 29 "/usr/include/bits/types.h" 2 3 4typedef unsigned char __u_char;typedef unsigned short int __u_short;typedef unsigned int __u_int;typedef unsigned long int __u_long;typedef signed char __int8_t;typedef unsigned char __uint8_t;typedef signed short int __int16_t;typedef unsigned short int __uint16_t;typedef signed int __int32_t;typedef unsigned int __uint32_t;__extension__ typedef signed long long int __int64_t;__extension__ typedef unsigned long long int __uint64_t;__extension__ typedef long long int __quad_t;__extension__ typedef unsigned long long int __u_quad_t;# 131 "/usr/include/bits/types.h" 3 4# 1 "/usr/include/bits/typesizes.h" 1 3 4# 132 "/usr/include/bits/types.h" 2 3 4__extension__ typedef __u_quad_t __dev_t;__extension__ typedef unsigned int __uid_t;__extension__ typedef unsigned int __gid_t;__extension__ typedef unsigned long int __ino_t;__extension__ typedef __u_quad_t __ino64_t;__extension__ typedef unsigned int __mode_t;__extension__ typedef unsigned int __nlink_t;__extension__ typedef long int __off_t;__extension__ typedef __quad_t __off64_t;__extension__ typedef int __pid_t;__extension__ typedef struct { int __val[2]; } __fsid_t;__extension__ typedef long int __clock_t;__extension__ typedef unsigned long int __rlim_t;__extension__ typedef __u_quad_t __rlim64_t;__extension__ typedef unsigned int __id_t;__extension__ typedef long int __time_t;__extension__ typedef unsigned int __useconds_t;__extension__ typedef long int __suseconds_t;__extension__ typedef int __daddr_t;__extension__ typedef long int __swblk_t;__extension__ typedef int __key_t;__extension__ typedef int __clockid_t;__extension__ typedef void * __timer_t;__extension__ typedef long int __blksize_t;__extension__ typedef long int __blkcnt_t;__extension__ typedef __quad_t __blkcnt64_t;__extension__ typedef unsigned long int __fsblkcnt_t;__extension__ typedef __u_quad_t __fsblkcnt64_t;__extension__ typedef unsigned long int __fsfilcnt_t;__extension__ typedef __u_quad_t __fsfilcnt64_t;__extension__ typedef int __ssize_t;typedef __off64_t __loff_t;typedef __quad_t *__qaddr_t;typedef char *__caddr_t;__extension__ typedef int __intptr_t;__extension__ typedef unsigned int __socklen_t;# 37 "/usr/include/stdio.h" 2 3 4# 45 "/usr/include/stdio.h" 3 4struct _IO_FILE;typedef struct _IO_FILE FILE;# 65 "/usr/include/stdio.h" 3 4typedef struct _IO_FILE __FILE;# 75 "/usr/include/stdio.h" 3 4# 1 "/usr/include/libio.h" 1 3 4# 32 "/usr/include/libio.h" 3 4# 1 "/usr/include/_G_config.h" 1 3 4# 15 "/usr/include/_G_config.h" 3 4# 1 "/usr/lib/gcc/i486-linux-gnu/4.4.1/include/stddef.h" 1 3 4# 16 "/usr/include/_G_config.h" 2 3 4# 1 "/usr/include/wchar.h" 1 3 4# 83 "/usr/include/wchar.h" 3 4typedef struct{  int __count;  union  {    unsigned int __wch;    char __wchb[4];  } __value;} __mbstate_t;# 21 "/usr/include/_G_config.h" 2 3 4typedef struct{  __off_t __pos;  __mbstate_t __state;} _G_fpos_t;typedef struct{  __off64_t __pos;  __mbstate_t __state;} _G_fpos64_t;# 53 "/usr/include/_G_config.h" 3 4typedef int _G_int16_t __attribute__ ((__mode__ (__HI__)));typedef int _G_int32_t __attribute__ ((__mode__ (__SI__)));typedef unsigned int _G_uint16_t __attribute__ ((__mode__ (__HI__)));typedef unsigned int _G_uint32_t __attribute__ ((__mode__ (__SI__)));# 33 "/usr/include/libio.h" 2 3 4# 53 "/usr/include/libio.h" 3 4# 1 "/usr/lib/gcc/i486-linux-gnu/4.4.1/include/stdarg.h" 1 3 4# 40 "/usr/lib/gcc/i486-linux-gnu/4.4.1/include/stdarg.h" 3 4typedef __builtin_va_list __gnuc_va_list;# 54 "/usr/include/libio.h" 2 3 4# 170 "/usr/include/libio.h" 3 4struct _IO_jump_t; struct _IO_FILE;# 180 "/usr/include/libio.h" 3 4typedef void _IO_lock_t;struct _IO_marker {  struct _IO_marker *_next;  struct _IO_FILE *_sbuf;  int _pos;# 203 "/usr/include/libio.h" 3 4};enum __codecvt_result{  __codecvt_ok,  __codecvt_partial,  __codecvt_error,  __codecvt_noconv};# 271 "/usr/include/libio.h" 3 4struct _IO_FILE {  int _flags;  char* _IO_read_ptr;  char* _IO_read_end;  char* _IO_read_base;  char* _IO_write_base;  char* _IO_write_ptr;  char* _IO_write_end;  char* _IO_buf_base;  char* _IO_buf_end;  char *_IO_save_base;  char *_IO_backup_base;  char *_IO_save_end;  struct _IO_marker *_markers;  struct _IO_FILE *_chain;  int _fileno;  int _flags2;  __off_t _old_offset;  unsigned short _cur_column;  signed char _vtable_offset;  char _shortbuf[1];  _IO_lock_t *_lock;# 319 "/usr/include/libio.h" 3 4  __off64_t _offset;# 328 "/usr/include/libio.h" 3 4  void *__pad1;  void *__pad2;  void *__pad3;  void *__pad4;  size_t __pad5;  int _mode;  char _unused2[15 * sizeof (int) - 4 * sizeof (void *) - sizeof (size_t)];};typedef struct _IO_FILE _IO_FILE;struct _IO_FILE_plus;extern struct _IO_FILE_plus _IO_2_1_stdin_;extern struct _IO_FILE_plus _IO_2_1_stdout_;extern struct _IO_FILE_plus _IO_2_1_stderr_;# 364 "/usr/include/libio.h" 3 4typedef __ssize_t __io_read_fn (void *__cookie, char *__buf, size_t __nbytes);typedef __ssize_t __io_write_fn (void *__cookie, __const char *__buf,     size_t __n);typedef int __io_seek_fn (void *__cookie, __off64_t *__pos, int __w);typedef int __io_close_fn (void *__cookie);# 416 "/usr/include/libio.h" 3 4extern int __underflow (_IO_FILE *);extern int __uflow (_IO_FILE *);extern int __overflow (_IO_FILE *, int);# 458 "/usr/include/libio.h" 3 4extern int _IO_getc (_IO_FILE *__fp);extern int _IO_putc (int __c, _IO_FILE *__fp);extern int _IO_feof (_IO_FILE *__fp) __attribute__ ((__nothrow__));extern int _IO_ferror (_IO_FILE *__fp) __attribute__ ((__nothrow__));extern int _IO_peekc_locked (_IO_FILE *__fp);extern void _IO_flockfile (_IO_FILE *) __attribute__ ((__nothrow__));extern void _IO_funlockfile (_IO_FILE *) __attribute__ ((__nothrow__));extern int _IO_ftrylockfile (_IO_FILE *) __attribute__ ((__nothrow__));# 488 "/usr/include/libio.h" 3 4extern int _IO_vfscanf (_IO_FILE * __restrict, const char * __restrict,   __gnuc_va_list, int *__restrict);extern int _IO_vfprintf (_IO_FILE *__restrict, const char *__restrict,    __gnuc_va_list);extern __ssize_t _IO_padn (_IO_FILE *, int, __ssize_t);extern size_t _IO_sgetn (_IO_FILE *, void *, size_t);extern __off64_t _IO_seekoff (_IO_FILE *, __off64_t, int, int);extern __off64_t _IO_seekpos (_IO_FILE *, __off64_t, int);extern void _IO_free_backup_area (_IO_FILE *) __attribute__ ((__nothrow__));# 76 "/usr/include/stdio.h" 2 3 4# 89 "/usr/include/stdio.h" 3 4typedef _G_fpos_t fpos_t;# 141 "/usr/include/stdio.h" 3 4# 1 "/usr/include/bits/stdio_lim.h" 1 3 4# 142 "/usr/include/stdio.h" 2 3 4extern struct _IO_FILE *stdin;extern struct _IO_FILE *stdout;extern struct _IO_FILE *stderr;extern int remove (__const char *__filename) __attribute__ ((__nothrow__));extern int rename (__const char *__old, __const char *__new) __attribute__ ((__nothrow__));extern int renameat (int __oldfd, __const char *__old, int __newfd,       __const char *__new) __attribute__ ((__nothrow__));extern FILE *tmpfile (void) ;# 186 "/usr/include/stdio.h" 3 4extern char *tmpnam (char *__s) __attribute__ ((__nothrow__)) ;extern char *tmpnam_r (char *__s) __attribute__ ((__nothrow__)) ;# 204 "/usr/include/stdio.h" 3 4extern char *tempnam (__const char *__dir, __const char *__pfx)     __attribute__ ((__nothrow__)) __attribute__ ((__malloc__)) ;extern int fclose (FILE *__stream);extern int fflush (FILE *__stream);# 229 "/usr/include/stdio.h" 3 4extern int fflush_unlocked (FILE *__stream);# 243 "/usr/include/stdio.h" 3 4extern FILE *fopen (__const char *__restrict __filename,      __const char *__restrict __modes) ;extern FILE *freopen (__const char *__restrict __filename,        __const char *__restrict __modes,        FILE *__restrict __stream) ;# 272 "/usr/include/stdio.h" 3 4# 283 "/usr/include/stdio.h" 3 4extern FILE *fdopen (int __fd, __const char *__modes) __attribute__ ((__nothrow__)) ;# 296 "/usr/include/stdio.h" 3 4extern FILE *fmemopen (void *__s, size_t __len, __const char *__modes)  __attribute__ ((__nothrow__)) ;extern FILE *open_memstream (char **__bufloc, size_t *__sizeloc) __attribute__ ((__nothrow__)) ;extern void setbuf (FILE *__restrict __stream, char *__restrict __buf) __attribute__ ((__nothrow__));extern int setvbuf (FILE *__restrict __stream, char *__restrict __buf,      int __modes, size_t __n) __attribute__ ((__nothrow__));extern void setbuffer (FILE *__restrict __stream, char *__restrict __buf,         size_t __size) __attribute__ ((__nothrow__));extern void setlinebuf (FILE *__stream) __attribute__ ((__nothrow__));extern int fprintf (FILE *__restrict __stream,      __const char *__restrict __format, ...);extern int printf (__const char *__restrict __format, ...);extern int sprintf (char *__restrict __s,      __const char *__restrict __format, ...) __attribute__ ((__nothrow__));extern int vfprintf (FILE *__restrict __s, __const char *__restrict __format,       __gnuc_va_list __arg);extern int vprintf (__const char *__restrict __format, __gnuc_va_list __arg);extern int vsprintf (char *__restrict __s, __const char *__restrict __format,       __gnuc_va_list __arg) __attribute__ ((__nothrow__));extern int snprintf (char *__restrict __s, size_t __maxlen,       __const char *__restrict __format, ...)     __attribute__ ((__nothrow__)) __attribute__ ((__format__ (__printf__, 3, 4)));extern int vsnprintf (char *__restrict __s, size_t __maxlen,        __const char *__restrict __format, __gnuc_va_list __arg)     __attribute__ ((__nothrow__)) __attribute__ ((__format__ (__printf__, 3, 0)));# 394 "/usr/include/stdio.h" 3 4extern int vdprintf (int __fd, __const char *__restrict __fmt,       __gnuc_va_list __arg)     __attribute__ ((__format__ (__printf__, 2, 0)));extern int dprintf (int __fd, __const char *__restrict __fmt, ...)     __attribute__ ((__format__ (__printf__, 2, 3)));extern int fscanf (FILE *__restrict __stream,     __const char *__restrict __format, ...) ;extern int scanf (__const char *__restrict __format, ...) ;extern int sscanf (__const char *__restrict __s,     __const char *__restrict __format, ...) __attribute__ ((__nothrow__));# 425 "/usr/include/stdio.h" 3 4extern int fscanf (FILE *__restrict __stream, __const char *__restrict __format, ...) __asm__ ("" "__isoc99_fscanf") ;extern int scanf (__const char *__restrict __format, ...) __asm__ ("" "__isoc99_scanf") ;extern int sscanf (__const char *__restrict __s, __const char *__restrict __format, ...) __asm__ ("" "__isoc99_sscanf") __attribute__ ((__nothrow__));# 445 "/usr/include/stdio.h" 3 4extern int vfscanf (FILE *__restrict __s, __const char *__restrict __format,      __gnuc_va_list __arg)     __attribute__ ((__format__ (__scanf__, 2, 0))) ;extern int vscanf (__const char *__restrict __format, __gnuc_va_list __arg)     __attribute__ ((__format__ (__scanf__, 1, 0))) ;extern int vsscanf (__const char *__restrict __s,      __const char *__restrict __format, __gnuc_va_list __arg)     __attribute__ ((__nothrow__)) __attribute__ ((__format__ (__scanf__, 2, 0)));# 476 "/usr/include/stdio.h" 3 4extern int vfscanf (FILE *__restrict __s, __const char *__restrict __format, __gnuc_va_list __arg) __asm__ ("" "__isoc99_vfscanf")     __attribute__ ((__format__ (__scanf__, 2, 0))) ;extern int vscanf (__const char *__restrict __format, __gnuc_va_list __arg) __asm__ ("" "__isoc99_vscanf")     __attribute__ ((__format__ (__scanf__, 1, 0))) ;extern int vsscanf (__const char *__restrict __s, __const char *__restrict __format, __gnuc_va_list __arg) __asm__ ("" "__isoc99_vsscanf")     __attribute__ ((__nothrow__)) __attribute__ ((__format__ (__scanf__, 2, 0)));# 504 "/usr/include/stdio.h" 3 4extern int fgetc (FILE *__stream);extern int getc (FILE *__stream);extern int getchar (void);# 532 "/usr/include/stdio.h" 3 4extern int getc_unlocked (FILE *__stream);extern int getchar_unlocked (void);# 543 "/usr/include/stdio.h" 3 4extern int fgetc_unlocked (FILE *__stream);extern int fputc (int __c, FILE *__stream);extern int putc (int __c, FILE *__stream);extern int putchar (int __c);# 576 "/usr/include/stdio.h" 3 4extern int fputc_unlocked (int __c, FILE *__stream);extern int putc_unlocked (int __c, FILE *__stream);extern int putchar_unlocked (int __c);extern int getw (FILE *__stream);extern int putw (int __w, FILE *__stream);extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)     ;extern char *gets (char *__s) ;# 638 "/usr/include/stdio.h" 3 4extern __ssize_t __getdelim (char **__restrict __lineptr,          size_t *__restrict __n, int __delimiter,          FILE *__restrict __stream) ;extern __ssize_t getdelim (char **__restrict __lineptr,        size_t *__restrict __n, int __delimiter,        FILE *__restrict __stream) ;extern __ssize_t getline (char **__restrict __lineptr,       size_t *__restrict __n,       FILE *__restrict __stream) ;extern int fputs (__const char *__restrict __s, FILE *__restrict __stream);extern int puts (__const char *__s);extern int ungetc (int __c, FILE *__stream);extern size_t fread (void *__restrict __ptr, size_t __size,       size_t __n, FILE *__restrict __stream) ;extern size_t fwrite (__const void *__restrict __ptr, size_t __size,        size_t __n, FILE *__restrict __s);# 710 "/usr/include/stdio.h" 3 4extern size_t fread_unlocked (void *__restrict __ptr, size_t __size,         size_t __n, FILE *__restrict __stream) ;extern size_t fwrite_unlocked (__const void *__restrict __ptr, size_t __size,          size_t __n, FILE *__restrict __stream);extern int fseek (FILE *__stream, long int __off, int __whence);extern long int ftell (FILE *__stream) ;extern void rewind (FILE *__stream);# 746 "/usr/include/stdio.h" 3 4extern int fseeko (FILE *__stream, __off_t __off, int __whence);extern __off_t ftello (FILE *__stream) ;# 765 "/usr/include/stdio.h" 3 4extern int fgetpos (FILE *__restrict __stream, fpos_t *__restrict __pos);extern int fsetpos (FILE *__stream, __const fpos_t *__pos);# 788 "/usr/include/stdio.h" 3 4# 797 "/usr/include/stdio.h" 3 4extern void clearerr (FILE *__stream) __attribute__ ((__nothrow__));extern int feof (FILE *__stream) __attribute__ ((__nothrow__)) ;extern int ferror (FILE *__stream) __attribute__ ((__nothrow__)) ;extern void clearerr_unlocked (FILE *__stream) __attribute__ ((__nothrow__));extern int feof_unlocked (FILE *__stream) __attribute__ ((__nothrow__)) ;extern int ferror_unlocked (FILE *__stream) __attribute__ ((__nothrow__)) ;extern void perror (__const char *__s);# 1 "/usr/include/bits/sys_errlist.h" 1 3 4# 27 "/usr/include/bits/sys_errlist.h" 3 4extern int sys_nerr;extern __const char *__const sys_errlist[];# 827 "/usr/include/stdio.h" 2 3 4extern int fileno (FILE *__stream) __attribute__ ((__nothrow__)) ;extern int fileno_unlocked (FILE *__stream) __attribute__ ((__nothrow__)) ;# 846 "/usr/include/stdio.h" 3 4extern FILE *popen (__const char *__command, __const char *__modes) ;extern int pclose (FILE *__stream);extern char *ctermid (char *__s) __attribute__ ((__nothrow__));# 886 "/usr/include/stdio.h" 3 4extern void flockfile (FILE *__stream) __attribute__ ((__nothrow__));extern int ftrylockfile (FILE *__stream) __attribute__ ((__nothrow__)) ;extern void funlockfile (FILE *__stream) __attribute__ ((__nothrow__));# 916 "/usr/include/stdio.h" 3 4# 2 "03-1.c" 2int main(){ printf("hello world!\n"); return 0;}

b:编译. 

编译
•对预处理文件进行一系列词法分析，语法分析和语义分析
•词法分析主要分析关键字，标示符，立即数等是否合法
•语法分析主要分析表达式是否遵循语法规则
•语义分析在语法分析的基础上进一步分析表达式是否合法
•分析结束后进行代码优化生成相应的汇编代码文件
编译指令：
gcc –S file.c –o file.s
   执行结果如下

.file"03-1.c".section.rodata.LC0:.string"hello world!".text.globl main.typemain, @functionmain:pushl%ebpmovl%esp, %ebpandl$-16, %espsubl$16, %espmovl$.LC0, (%esp)callputsmovl$0, %eaxleaveret.sizemain, .-main.ident"GCC: (Ubuntu 4.4.1-4ubuntu8) 4.4.1".section.note.GNU-stack,"",@progbits

上面的执行是编译结果导致的,编译器的编译动作其中就是把源文件翻译成汇编代码.

c: 

汇编
•汇编器将汇编代码转变为机器可以执行的指令
•每个汇编语句几乎都对应一条机器指令
汇编指令：
gcc –c file.s –o hello.o

 

d: 链接器的意义.

  

连接器的主要作用是把各个模块之间相互引用的部分
处理好，使得各个模块之间能够正确的衔接。

 

   模块拼装

     编译器将编译工作主要分为预处理，编译和汇编三部

  连接器的工作是把各个独立的模块链接为可执行程序
   
静态链接在编译期完成，动态链接在运行期完成