Linux编程-GCC编译命令的使用，gcc

小灰灰 2023-10-16 18:50 169阅读 0赞

**1.内容简介：**

GCC,即GNU编译器套件（GNU Compiler Collection），是最为广泛使用的编译器之一，几乎包含了我们熟知的大部分编程语言，包括CC、C++、 Objective-C、 Fortran、Java、Ada和Go语言前端，也包括了这些语言的库（如libstdc++，libgcj等）。正如某些流行的技术一样，一开始，并没有想到会发展的如此庞大和广泛，GCC的初衷是为GNU操作系统专门编写的一款编译器。

**2. GCC快速使用：gcc filename.c直接编译成可执行文件**

先来快速看看GCC怎么使用，看下面这个例子：

#include <stdio.h>
    int main() {
    	int a = 5;
    	int b =3;
    	int res = sum(a,b);
    	printf("sum=%d",res);
     
    }
     
    int sum(int a,int b) {
    	int c = a+b;
    	return c;
    }

用GCC编译结果：

> gcc my\_sum.c
> 
> **my\_sum.c:5:12:** **error:** **implicit declaration of function 'sum' is invalid in C99 \[-Werror,-Wimplicit-function-declaration\]**
> 
> int res = sum(a,b);
> 
>  **^**
> 
> 1 error generated.

很显然，在编译时，找不到my\_sum，可是明明定义了呀。还记得，谭浩强的C语言编程书中说的，先声明，再引用么？把my\_sum放在main函数前面，试一下：

#include <stdio.h>
    int sum(int a,int b) {
    	int c = a+b;
    	return c;
    }
    
    int main() {
    	int a = 5;
    	int b =3;
    	int res = sum(a,b);
    	printf("sum=%d",res);
     
    }

编译成功，运行：

> gcc my\_sum.c
> 
> aibook@aibookdeMacBook-Pro c\_stu % ./a.out
> 
> sum=8

**3. GCC命令常用选项和说明：**

将C，C++源代码编译为可执行代码的过程，可以拆分成4个步骤：预处理（Preprocessing）、编译（Compilation）、汇编（Assembly）和链接（Linking）。  
上面的gcc filename.c就直讲完成上面4个步骤，编译生成a.out,这个是默认的目标文件名称。

GCC还有许多选项，常用的如下：  
\-E: 对源文件进行预处理。  
\-S: 汇编，生成汇编文件。  
\-c: 生成目标文件。但不进行链接，生成的文件还不能直接运行。当-c后跟多个源文件，会为每个源文件生成一个.o文件，但此时是不能使用-o的。  
\-o: 指定要生成的结果文件，o是output，而非object。即生成可执行文件。

这个过程，分开可以这样编译：

aibook@aibookdeMacBook-Pro chaper1 % gcc -E my_sum.c -o my_sum.i
    aibook@aibookdeMacBook-Pro chaper1 % ls
    a.out		my_sum.c	my_sum.i
    aibook@aibookdeMacBook-Pro chaper1 % gcc -S my_sum.i
    aibook@aibookdeMacBook-Pro chaper1 % ls
    a.out		my_sum.c	my_sum.i	my_sum.s
    aibook@aibookdeMacBook-Pro chaper1 % gcc -c my_sum.s
    aibook@aibookdeMacBook-Pro chaper1 % ls
    a.out		my_sum.c	my_sum.i	my_sum.o	my_sum.s
    aibook@aibookdeMacBook-Pro chaper1 % gcc -o my_sum my_sum.o
    aibook@aibookdeMacBook-Pro chaper1 % ls
    a.out		my_sum		my_sum.c	my_sum.i	my_sum.o	my_sum.s
    aibook@aibookdeMacBook-Pro chaper1 % my_sum 
    sum=8                                                                                                                     aibook@aibookdeMacBook-Pro chaper1 %

当然，我们可以一步到位，知道结果文件：

aibook@aibookdeMacBook-Pro chaper1 % gcc -o my_sum2 my_sum.c
    aibook@aibookdeMacBook-Pro chaper1 % ls
    a.out		my_sum		my_sum.c	my_sum.i	my_sum.o	my_sum.s	my_sum2
    aibook@aibookdeMacBook-Pro chaper1 %

运行my\_sum2,结果如下：

> aibook@aibookdeMacBook-Pro chaper1 % my\_sum2
> 
> sum=8

**4. 这些中间文件长啥样：**

上面编译生成的有.i,.s.o等文件，我们主要来看.i和.s文件的代码：

**my\_sum.i:**

# 1 "my_sum.c"
    # 1 "<built-in>" 1
    # 1 "<built-in>" 3
    # 367 "<built-in>" 3
    # 1 "<command line>" 1
    # 1 "<built-in>" 2
    # 1 "my_sum.c" 2
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h" 1 3 4
    # 64 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h" 1 3 4
    # 68 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h" 1 3 4
    # 649 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_symbol_aliasing.h" 1 3 4
    # 650 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h" 2 3 4
    # 715 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_posix_availability.h" 1 3 4
    # 716 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/cdefs.h" 2 3 4
    # 69 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/Availability.h" 1 3 4
    # 135 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/Availability.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/AvailabilityVersions.h" 1 3 4
    # 136 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/Availability.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/AvailabilityInternal.h" 1 3 4
    # 137 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/Availability.h" 2 3 4
    # 70 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h" 2 3 4
    
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_types.h" 1 3 4
    # 27 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_types.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types.h" 1 3 4
    # 33 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/machine/_types.h" 1 3 4
    # 32 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/machine/_types.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/_types.h" 1 3 4
    # 37 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.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/MacOSX.sdk/usr/include/machine/_types.h" 2 3 4
    # 34 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types.h" 2 3 4
    # 55 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.sdk/usr/include/sys/_pthread/_pthread_types.h" 1 3 4
    # 57 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.sdk/usr/include/sys/_types.h" 2 3 4
    # 28 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_types.h" 2 3 4
    # 40 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.sdk/usr/include/_stdio.h" 2 3 4
    
    
    
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_va_list.h" 1 3 4
    # 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_va_list.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/machine/types.h" 1 3 4
    # 35 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/machine/types.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 1 3 4
    # 76 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_int8_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_int8_t.h" 3 4
    typedef signed char int8_t;
    # 77 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_int16_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_int16_t.h" 3 4
    typedef short int16_t;
    # 78 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_int32_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_int32_t.h" 3 4
    typedef int int32_t;
    # 79 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_int64_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_int64_t.h" 3 4
    typedef long long int64_t;
    # 80 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_u_int8_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_u_int8_t.h" 3 4
    typedef unsigned char u_int8_t;
    # 82 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_u_int16_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_u_int16_t.h" 3 4
    typedef unsigned short u_int16_t;
    # 83 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_u_int32_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_u_int32_t.h" 3 4
    typedef unsigned int u_int32_t;
    # 84 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_u_int64_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_u_int64_t.h" 3 4
    typedef unsigned long long u_int64_t;
    # 85 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    
    
    typedef int64_t register_t;
    
    
    
    
    
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_intptr_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_intptr_t.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/machine/types.h" 1 3 4
    # 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_intptr_t.h" 2 3 4
    
    typedef __darwin_intptr_t intptr_t;
    # 93 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/i386/types.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_uintptr_t.h" 1 3 4
    # 30 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_uintptr_t.h" 3 4
    typedef unsigned long uintptr_t;
    # 94 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.sdk/usr/include/machine/types.h" 2 3 4
    # 32 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_va_list.h" 2 3 4
    typedef __darwin_va_list va_list;
    # 76 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_size_t.h" 1 3 4
    # 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_size_t.h" 3 4
    typedef __darwin_size_t size_t;
    # 77 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h" 2 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_null.h" 1 3 4
    # 78 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h" 2 3 4
    
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/stdio.h" 1 3 4
    # 39 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.sdk/usr/include/_stdio.h" 2 3 4
    
    typedef __darwin_off_t fpos_t;
    # 92 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_stdio.h" 3 4
    struct __sbuf {
     unsigned char *_base;
     int _size;
    };
    
    
    struct __sFILEX;
    # 126 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.sdk/usr/include/stdio.h" 2 3 4
    
    
    extern FILE *__stdinp;
    extern FILE *__stdoutp;
    extern FILE *__stderrp;
    # 142 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.sdk/usr/include/stdio.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_ctermid.h" 1 3 4
    # 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/_ctermid.h" 3 4
    char *ctermid(char *);
    # 206 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h" 2 3 4
    
    
    
    
    FILE *fdopen(int, const char *) __asm("_" "fdopen" );
    
    int fileno(FILE *);
    # 228 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.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/MacOSX.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/MacOSX.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/MacOSX.sdk/usr/include/stdio.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_off_t.h" 1 3 4
    # 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_off_t.h" 3 4
    typedef __darwin_off_t off_t;
    # 325 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.sdk/usr/include/stdio.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_ssize_t.h" 1 3 4
    # 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/_types/_ssize_t.h" 3 4
    typedef __darwin_ssize_t ssize_t;
    # 350 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.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/MacOSX.sdk/usr/include/stdio.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/secure/_stdio.h" 1 3 4
    # 31 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/secure/_stdio.h" 3 4
    # 1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/secure/_common.h" 1 3 4
    # 32 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/secure/_stdio.h" 2 3 4
    # 42 "/Library/Developer/CommandLineTools/SDKs/MacOSX.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/MacOSX.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/MacOSX.sdk/usr/include/stdio.h" 2 3 4
    # 2 "my_sum.c" 2
    int sum(int a,int b) {
     int c = a+b;
     return c;
    }
    
    int main() {
     int a = 5;
     int b =3;
     int res = sum(a,b);
     printf("sum=%d",res);
    
    }

my\_sum.s:

.section	__TEXT,__text,regular,pure_instructions
    	.build_version macos, 11, 0	sdk_version 11, 3
    	.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
    	movl	%edi, -4(%rbp)
    	movl	%esi, -8(%rbp)
    	movl	-4(%rbp), %eax
    	addl	-8(%rbp), %eax
    	movl	%eax, -12(%rbp)
    	movl	-12(%rbp), %eax
    	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
    	subq	$16, %rsp
    	movl	$5, -4(%rbp)
    	movl	$3, -8(%rbp)
    	movl	-4(%rbp), %edi
    	movl	-8(%rbp), %esi
    	callq	_sum
    	movl	%eax, -12(%rbp)
    	movl	-12(%rbp), %esi
    	leaq	L_.str(%rip), %rdi
    	movb	$0, %al
    	callq	_printf
    	xorl	%ecx, %ecx
    	movl	%eax, -16(%rbp)                 ## 4-byte Spill
    	movl	%ecx, %eax
    	addq	$16, %rsp
    	popq	%rbp
    	retq
    	.cfi_endproc
                                            ## -- End function
    	.section	__TEXT,__cstring,cstring_literals
    L_.str:                                 ## @.str
    	.asciz	"sum=%d"
    
    .subsections_via_symbols