程序编译过程
2021-01-11 本文已影响0人
不仅仅是个程序猿
本文编译的文件cpu架构为X86_64。
编译型语言编译过程主要有预编译、编译、汇编、链接。
-
预编译
This stage parses the input file, translating preprocessor tokens into a parse tree. Once in the form of a parse tree, it
applies semantic analysis to compute types for expressions as
well and determine whether the code is well formed. This stage
is responsible for generating most of the compiler warnings as
well as parse errors. The output of this stage is an "Abstract
Syntax Tree" (AST).预编译主要是将程序中的#开头的一些宏和引入的一些文件（#include, #import等）做一些替换，也会删除程序中包含的注释，检查语法。
-
编译
This stage translates an AST into low-level intermediate code (known as "LLVM IR") and ultimately to machine code. This phase is responsible for optimizing the generated code and handling target-specific code generation. The output of this stage is typically called a ".s" file or "assembly" file.编译是将高级语言翻译成汇编语言的过程
-
汇编
Assembler
This stage runs the target assembler to translate the output of the compiler into a target object file. The output of this stage
is typically called a ".o" file or "object" file.汇编是将汇编语言转化为对象文件（.o文件）
-
链接 ( link )
Linker
This stage runs the target linker to merge multiple object files into an executable or dynamic library. The output of this stage is typically called an "a.out", ".dylib" or ".so" file.将多个.o文件合进一个可执行文件或动态库，输出文件为a.out，.dylib或.so文件
下面以一个c语言文件来看下具体过程。
首先新建一个main.c文件。里面包含了注释和宏定义。
//这是一个C程序
/**C语言*/
#include <stdio.h>
#define Num 10
void sum(int x, int y) {
int sum = x + y;
printf("sum = %d\n",sum);
}
int main() {
sum(1, Num);
}
- 预编译
使用gcc命令预编译c文件。 -o表示输出，后面跟输出文件的路径
gcc -E main.c -o a.c
查看预编译后的a.c文件
# 1 "main.c"
# 1 "<built-in>" 1
# 1 "<built-in>" 3
# 361 "<built-in>" 3
# 1 "<command line>" 1
# 1 "<built-in>" 2
# 1 "main.c" 2
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 1 3 4
# 64 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 1 3 4
# 68 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/cdefs.h" 1 3 4
# 630 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/cdefs.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_symbol_aliasing.h" 1 3 4
# 631 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/cdefs.h" 2 3 4
# 696 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/cdefs.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_posix_availability.h" 1 3 4
# 697 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/cdefs.h" 2 3 4
# 69 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/Availability.h" 1 3 4
# 251 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/Availability.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/AvailabilityInternal.h" 1 3 4
# 252 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/Availability.h" 2 3 4
# 70 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_types.h" 1 3 4
# 27 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_types.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types.h" 1 3 4
# 33 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/machine/_types.h" 1 3 4
# 32 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/machine/_types.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/_types.h" 1 3 4
# 37 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/_types.h" 3 4
typedef signed char __int8_t;
typedef unsigned char __uint8_t;
typedef short __int16_t;
typedef unsigned short __uint16_t;
typedef int __int32_t;
typedef unsigned int __uint32_t;
typedef long long __int64_t;
typedef unsigned long long __uint64_t;
typedef long __darwin_intptr_t;
typedef unsigned int __darwin_natural_t;
# 70 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/_types.h" 3 4
typedef int __darwin_ct_rune_t;
typedef union {
char __mbstate8[128];
long long _mbstateL;
} __mbstate_t;
typedef __mbstate_t __darwin_mbstate_t;
typedef long int __darwin_ptrdiff_t;
typedef long unsigned int __darwin_size_t;
typedef __builtin_va_list __darwin_va_list;
typedef int __darwin_wchar_t;
typedef __darwin_wchar_t __darwin_rune_t;
typedef int __darwin_wint_t;
typedef unsigned long __darwin_clock_t;
typedef __uint32_t __darwin_socklen_t;
typedef long __darwin_ssize_t;
typedef long __darwin_time_t;
# 33 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/machine/_types.h" 2 3 4
# 34 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types.h" 2 3 4
# 55 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types.h" 3 4
typedef __int64_t __darwin_blkcnt_t;
typedef __int32_t __darwin_blksize_t;
typedef __int32_t __darwin_dev_t;
typedef unsigned int __darwin_fsblkcnt_t;
typedef unsigned int __darwin_fsfilcnt_t;
typedef __uint32_t __darwin_gid_t;
typedef __uint32_t __darwin_id_t;
typedef __uint64_t __darwin_ino64_t;
typedef __darwin_ino64_t __darwin_ino_t;
typedef __darwin_natural_t __darwin_mach_port_name_t;
typedef __darwin_mach_port_name_t __darwin_mach_port_t;
typedef __uint16_t __darwin_mode_t;
typedef __int64_t __darwin_off_t;
typedef __int32_t __darwin_pid_t;
typedef __uint32_t __darwin_sigset_t;
typedef __int32_t __darwin_suseconds_t;
typedef __uint32_t __darwin_uid_t;
typedef __uint32_t __darwin_useconds_t;
typedef unsigned char __darwin_uuid_t[16];
typedef char __darwin_uuid_string_t[37];
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_pthread/_pthread_types.h" 1 3 4
# 57 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_pthread/_pthread_types.h" 3 4
struct __darwin_pthread_handler_rec {
void (*__routine)(void *);
void *__arg;
struct __darwin_pthread_handler_rec *__next;
};
struct _opaque_pthread_attr_t {
long __sig;
char __opaque[56];
};
struct _opaque_pthread_cond_t {
long __sig;
char __opaque[40];
};
struct _opaque_pthread_condattr_t {
long __sig;
char __opaque[8];
};
struct _opaque_pthread_mutex_t {
long __sig;
char __opaque[56];
};
struct _opaque_pthread_mutexattr_t {
long __sig;
char __opaque[8];
};
struct _opaque_pthread_once_t {
long __sig;
char __opaque[8];
};
struct _opaque_pthread_rwlock_t {
long __sig;
char __opaque[192];
};
struct _opaque_pthread_rwlockattr_t {
long __sig;
char __opaque[16];
};
struct _opaque_pthread_t {
long __sig;
struct __darwin_pthread_handler_rec *__cleanup_stack;
char __opaque[8176];
};
typedef struct _opaque_pthread_attr_t __darwin_pthread_attr_t;
typedef struct _opaque_pthread_cond_t __darwin_pthread_cond_t;
typedef struct _opaque_pthread_condattr_t __darwin_pthread_condattr_t;
typedef unsigned long __darwin_pthread_key_t;
typedef struct _opaque_pthread_mutex_t __darwin_pthread_mutex_t;
typedef struct _opaque_pthread_mutexattr_t __darwin_pthread_mutexattr_t;
typedef struct _opaque_pthread_once_t __darwin_pthread_once_t;
typedef struct _opaque_pthread_rwlock_t __darwin_pthread_rwlock_t;
typedef struct _opaque_pthread_rwlockattr_t __darwin_pthread_rwlockattr_t;
typedef struct _opaque_pthread_t *__darwin_pthread_t;
# 81 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types.h" 2 3 4
# 28 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_types.h" 2 3 4
# 40 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_types.h" 3 4
typedef int __darwin_nl_item;
typedef int __darwin_wctrans_t;
typedef __uint32_t __darwin_wctype_t;
# 72 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_va_list.h" 1 3 4
# 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_va_list.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/machine/types.h" 1 3 4
# 35 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/machine/types.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 1 3 4
# 76 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_int8_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_int8_t.h" 3 4
typedef signed char int8_t;
# 77 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_int16_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_int16_t.h" 3 4
typedef short int16_t;
# 78 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_int32_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_int32_t.h" 3 4
typedef int int32_t;
# 79 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_int64_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_int64_t.h" 3 4
typedef long long int64_t;
# 80 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_u_int8_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_u_int8_t.h" 3 4
typedef unsigned char u_int8_t;
# 82 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_u_int16_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_u_int16_t.h" 3 4
typedef unsigned short u_int16_t;
# 83 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_u_int32_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_u_int32_t.h" 3 4
typedef unsigned int u_int32_t;
# 84 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_u_int64_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_u_int64_t.h" 3 4
typedef unsigned long long u_int64_t;
# 85 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
typedef int64_t register_t;
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_intptr_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_intptr_t.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/machine/types.h" 1 3 4
# 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_intptr_t.h" 2 3 4
typedef __darwin_intptr_t intptr_t;
# 93 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_uintptr_t.h" 1 3 4
# 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_uintptr_t.h" 3 4
typedef unsigned long uintptr_t;
# 94 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/i386/types.h" 2 3 4
typedef u_int64_t user_addr_t;
typedef u_int64_t user_size_t;
typedef int64_t user_ssize_t;
typedef int64_t user_long_t;
typedef u_int64_t user_ulong_t;
typedef int64_t user_time_t;
typedef int64_t user_off_t;
typedef u_int64_t syscall_arg_t;
# 36 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/machine/types.h" 2 3 4
# 32 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_va_list.h" 2 3 4
typedef __darwin_va_list va_list;
# 76 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_size_t.h" 1 3 4
# 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_size_t.h" 3 4
typedef __darwin_size_t size_t;
# 77 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_null.h" 1 3 4
# 78 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 2 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/stdio.h" 1 3 4
# 39 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/stdio.h" 3 4
int renameat(int, const char *, int, const char *) __attribute__((availability(macosx,introduced=10.10)));
int renamex_np(const char *, const char *, unsigned int) __attribute__((availability(macosx,introduced=10.12))) __attribute__((availability(ios,introduced=10.0))) __attribute__((availability(tvos,introduced=10.0))) __attribute__((availability(watchos,introduced=3.0)));
int renameatx_np(int, const char *, int, const char *, unsigned int) __attribute__((availability(macosx,introduced=10.12))) __attribute__((availability(ios,introduced=10.0))) __attribute__((availability(tvos,introduced=10.0))) __attribute__((availability(watchos,introduced=3.0)));
# 80 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 2 3 4
typedef __darwin_off_t fpos_t;
# 92 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 3 4
struct __sbuf {
unsigned char *_base;
int _size;
};
struct __sFILEX;
# 126 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_stdio.h" 3 4
typedef struct __sFILE {
unsigned char *_p;
int _r;
int _w;
short _flags;
short _file;
struct __sbuf _bf;
int _lbfsize;
void *_cookie;
int (* _Nullable _close)(void *);
int (* _Nullable _read) (void *, char *, int);
fpos_t (* _Nullable _seek) (void *, fpos_t, int);
int (* _Nullable _write)(void *, const char *, int);
struct __sbuf _ub;
struct __sFILEX *_extra;
int _ur;
unsigned char _ubuf[3];
unsigned char _nbuf[1];
struct __sbuf _lb;
int _blksize;
fpos_t _offset;
} FILE;
# 65 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 2 3 4
extern FILE *__stdinp;
extern FILE *__stdoutp;
extern FILE *__stderrp;
# 142 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
void clearerr(FILE *);
int fclose(FILE *);
int feof(FILE *);
int ferror(FILE *);
int fflush(FILE *);
int fgetc(FILE *);
int fgetpos(FILE * restrict, fpos_t *);
char *fgets(char * restrict, int, FILE *);
FILE *fopen(const char * restrict __filename, const char * restrict __mode) __asm("_" "fopen" );
int fprintf(FILE * restrict, const char * restrict, ...) __attribute__((__format__ (__printf__, 2, 3)));
int fputc(int, FILE *);
int fputs(const char * restrict, FILE * restrict) __asm("_" "fputs" );
size_t fread(void * restrict __ptr, size_t __size, size_t __nitems, FILE * restrict __stream);
FILE *freopen(const char * restrict, const char * restrict,
FILE * restrict) __asm("_" "freopen" );
int fscanf(FILE * restrict, const char * restrict, ...) __attribute__((__format__ (__scanf__, 2, 3)));
int fseek(FILE *, long, int);
int fsetpos(FILE *, const fpos_t *);
long ftell(FILE *);
size_t fwrite(const void * restrict __ptr, size_t __size, size_t __nitems, FILE * restrict __stream) __asm("_" "fwrite" );
int getc(FILE *);
int getchar(void);
char *gets(char *);
void perror(const char *) __attribute__((__cold__));
int printf(const char * restrict, ...) __attribute__((__format__ (__printf__, 1, 2)));
int putc(int, FILE *);
int putchar(int);
int puts(const char *);
int remove(const char *);
int rename (const char *__old, const char *__new);
void rewind(FILE *);
int scanf(const char * restrict, ...) __attribute__((__format__ (__scanf__, 1, 2)));
void setbuf(FILE * restrict, char * restrict);
int setvbuf(FILE * restrict, char * restrict, int, size_t);
int sprintf(char * restrict, const char * restrict, ...) __attribute__((__format__ (__printf__, 2, 3))) __attribute__((__availability__(swift, unavailable, message="Use snprintf instead.")));
int sscanf(const char * restrict, const char * restrict, ...) __attribute__((__format__ (__scanf__, 2, 3)));
FILE *tmpfile(void);
__attribute__((__availability__(swift, unavailable, message="Use mkstemp(3) instead.")))
__attribute__((__deprecated__("This function is provided for compatibility reasons only. Due to security concerns inherent in the design of tmpnam(3), it is highly recommended that you use mkstemp(3) instead.")))
char *tmpnam(char *);
int ungetc(int, FILE *);
int vfprintf(FILE * restrict, const char * restrict, va_list) __attribute__((__format__ (__printf__, 2, 0)));
int vprintf(const char * restrict, va_list) __attribute__((__format__ (__printf__, 1, 0)));
int vsprintf(char * restrict, const char * restrict, va_list) __attribute__((__format__ (__printf__, 2, 0))) __attribute__((__availability__(swift, unavailable, message="Use vsnprintf instead.")));
# 205 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_ctermid.h" 1 3 4
# 26 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/_ctermid.h" 3 4
char *ctermid(char *);
# 206 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 2 3 4
FILE *fdopen(int, const char *) __asm("_" "fdopen" );
int fileno(FILE *);
# 228 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
int pclose(FILE *) __attribute__((__availability__(swift, unavailable, message="Use posix_spawn APIs or NSTask instead.")));
FILE *popen(const char *, const char *) __asm("_" "popen" ) __attribute__((__availability__(swift, unavailable, message="Use posix_spawn APIs or NSTask instead.")));
# 249 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
int __srget(FILE *);
int __svfscanf(FILE *, const char *, va_list) __attribute__((__format__ (__scanf__, 2, 0)));
int __swbuf(int, FILE *);
# 260 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
inline __attribute__ ((__always_inline__)) int __sputc(int _c, FILE *_p) {
if (--_p->_w >= 0 || (_p->_w >= _p->_lbfsize && (char)_c != '\n'))
return (*_p->_p++ = _c);
else
return (__swbuf(_c, _p));
}
# 286 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
void flockfile(FILE *);
int ftrylockfile(FILE *);
void funlockfile(FILE *);
int getc_unlocked(FILE *);
int getchar_unlocked(void);
int putc_unlocked(int, FILE *);
int putchar_unlocked(int);
int getw(FILE *);
int putw(int, FILE *);
__attribute__((__availability__(swift, unavailable, message="Use mkstemp(3) instead.")))
__attribute__((__deprecated__("This function is provided for compatibility reasons only. Due to security concerns inherent in the design of tempnam(3), it is highly recommended that you use mkstemp(3) instead.")))
char *tempnam(const char *__dir, const char *__prefix) __asm("_" "tempnam" );
# 324 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_off_t.h" 1 3 4
# 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_off_t.h" 3 4
typedef __darwin_off_t off_t;
# 325 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 2 3 4
int fseeko(FILE * __stream, off_t __offset, int __whence);
off_t ftello(FILE * __stream);
int snprintf(char * restrict __str, size_t __size, const char * restrict __format, ...) __attribute__((__format__ (__printf__, 3, 4)));
int vfscanf(FILE * restrict __stream, const char * restrict __format, va_list) __attribute__((__format__ (__scanf__, 2, 0)));
int vscanf(const char * restrict __format, va_list) __attribute__((__format__ (__scanf__, 1, 0)));
int vsnprintf(char * restrict __str, size_t __size, const char * restrict __format, va_list) __attribute__((__format__ (__printf__, 3, 0)));
int vsscanf(const char * restrict __str, const char * restrict __format, va_list) __attribute__((__format__ (__scanf__, 2, 0)));
# 349 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_ssize_t.h" 1 3 4
# 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/_types/_ssize_t.h" 3 4
typedef __darwin_ssize_t ssize_t;
# 350 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 2 3 4
int dprintf(int, const char * restrict, ...) __attribute__((__format__ (__printf__, 2, 3))) __attribute__((availability(macosx,introduced=10.7)));
int vdprintf(int, const char * restrict, va_list) __attribute__((__format__ (__printf__, 2, 0))) __attribute__((availability(macosx,introduced=10.7)));
ssize_t getdelim(char ** restrict __linep, size_t * restrict __linecapp, int __delimiter, FILE * restrict __stream) __attribute__((availability(macosx,introduced=10.7)));
ssize_t getline(char ** restrict __linep, size_t * restrict __linecapp, FILE * restrict __stream) __attribute__((availability(macosx,introduced=10.7)));
FILE *fmemopen(void * restrict __buf, size_t __size, const char * restrict __mode) __attribute__((availability(macos,introduced=10.13))) __attribute__((availability(ios,introduced=11.0))) __attribute__((availability(tvos,introduced=11.0))) __attribute__((availability(watchos,introduced=4.0)));
FILE *open_memstream(char **__bufp, size_t *__sizep) __attribute__((availability(macos,introduced=10.13))) __attribute__((availability(ios,introduced=11.0))) __attribute__((availability(tvos,introduced=11.0))) __attribute__((availability(watchos,introduced=4.0)));
# 367 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
extern const int sys_nerr;
extern const char *const sys_errlist[];
int asprintf(char ** restrict, const char * restrict, ...) __attribute__((__format__ (__printf__, 2, 3)));
char *ctermid_r(char *);
char *fgetln(FILE *, size_t *);
const char *fmtcheck(const char *, const char *);
int fpurge(FILE *);
void setbuffer(FILE *, char *, int);
int setlinebuf(FILE *);
int vasprintf(char ** restrict, const char * restrict, va_list) __attribute__((__format__ (__printf__, 2, 0)));
FILE *zopen(const char *, const char *, int);
FILE *funopen(const void *,
int (* _Nullable)(void *, char *, int),
int (* _Nullable)(void *, const char *, int),
fpos_t (* _Nullable)(void *, fpos_t, int),
int (* _Nullable)(void *));
# 407 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/secure/_stdio.h" 1 3 4
# 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/secure/_stdio.h" 3 4
# 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/secure/_common.h" 1 3 4
# 32 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/secure/_stdio.h" 2 3 4
# 42 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/secure/_stdio.h" 3 4
extern int __sprintf_chk (char * restrict, int, size_t,
const char * restrict, ...);
# 52 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/secure/_stdio.h" 3 4
extern int __snprintf_chk (char * restrict, size_t, int, size_t,
const char * restrict, ...);
extern int __vsprintf_chk (char * restrict, int, size_t,
const char * restrict, va_list);
extern int __vsnprintf_chk (char * restrict, size_t, int, size_t,
const char * restrict, va_list);
# 408 "/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdio.h" 2 3 4
# 6 "main.c" 2
void sum(int x, int y) {
int sum = x + y;
printf("sum = %d\n",sum);
}
int main() {
sum(1, 10);
}
可以看到预处理后的a.c文件，原本main.c中的前2行程序注释已经没有了，定义的宏Num也不见了，直接被替换成了10。#include <stdio.h>直接被替换成了stdio.h 头文件中的内容。
- 编译
gcc -S a.c -o a.s
查看编译后的a.s文件（此处生成的是X86_64架构的）：
.section __TEXT,__text,regular,pure_instructions
.build_version macos, 10, 15 sdk_version 10, 15
.globl _sum ## -- Begin function sum
.p2align 4, 0x90
_sum: ## @sum
.cfi_startproc
## %bb.0:
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset %rbp, -16
movq %rsp, %rbp
.cfi_def_cfa_register %rbp
subq $16, %rsp
movl %edi, -4(%rbp)
movl %esi, -8(%rbp)
movl -4(%rbp), %esi
addl -8(%rbp), %esi
movl %esi, -12(%rbp)
movl -12(%rbp), %esi
leaq L_.str(%rip), %rdi
movb $0, %al
callq _printf
movl %eax, -16(%rbp) ## 4-byte Spill
addq $16, %rsp
popq %rbp
retq
.cfi_endproc
## -- End function
.globl _main ## -- Begin function main
.p2align 4, 0x90
_main: ## @main
.cfi_startproc
## %bb.0:
pushq %rbp
.cfi_def_cfa_offset 16
.cfi_offset %rbp, -16
movq %rsp, %rbp
.cfi_def_cfa_register %rbp
movl $1, %edi
movl $10, %esi
callq _sum
xorl %eax, %eax
popq %rbp
retq
.cfi_endproc
## -- End function
.section __TEXT,__cstring,cstring_literals
L_.str: ## @.str
.asciz "sum = %d\n"
.subsections_via_symbols
- 汇编
gcc -c a.s -o a.o
查看.o文件
- 链接
gcc a.o
此命令执行完成后会产生一个a.out的可执行文件。
查看.out文件类型
执行a.out可执行文件
