1、同一文件，默认编译选项
在同一.c文件内gcc默认编译选项：
gcc -S test.c -o test1.s
生成的test.s中不会内联展开，而是对其普通函数处理。
2、同一文件，编译选项O3优化
在同一.c文件内gcc O3编译选项：
gcc -S test.c -o test2.s -O3
生成的test.s中会内联展开
3、不同文件，编译选项O3优化
gcc -S main.c -o main.s -O3
gcc -S fun.c -o fun.s -O3
目测且分析是没有内联展开，具体结果可以看附件。
分析是gcc编译单独编译文件成汇编代码，而在编译main.c的时候，还没有fun.s的汇编代码，只能做call调用,虽然已经在声明中声明了inline。但是根据https://blog.csdn.net/hanchaoman/article/details/7268839 的表述，声明是不管用的，不给报错就不错了。
附件1-test.c
#include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> #include <unistd.h> #include <fcntl.h> inline void fun(){ printf("inline run "); } int main(int argc, char *argv[]){ fun(); return 0; }
附件2-test1.s
1 .file "test.c" 2 .section .rodata 3 .LC0: 4 .string "inline run" 5 .text 6 .globl fun 7 .type fun, @function 8 fun: 9 .LFB2: 10 .cfi_startproc 11 pushq %rbp 12 .cfi_def_cfa_offset 16 13 .cfi_offset 6, -16 14 movq %rsp, %rbp 15 .cfi_def_cfa_register 6 16 movl $.LC0, %edi 17 call puts 18 popq %rbp 19 .cfi_def_cfa 7, 8 20 ret 21 .cfi_endproc 22 .LFE2: 23 .size fun, .-fun 24 .globl main 25 .type main, @function 26 main: 27 .LFB3: 28 .cfi_startproc 29 pushq %rbp 30 .cfi_def_cfa_offset 16 31 .cfi_offset 6, -16 32 movq %rsp, %rbp 33 .cfi_def_cfa_register 6 34 subq $16, %rsp 35 movl %edi, -4(%rbp) 36 movq %rsi, -16(%rbp) 37 movl $0, %eax 38 call fun 39 movl $0, %eax 40 leave 41 .cfi_def_cfa 7, 8 42 ret 43 .cfi_endproc 44 .LFE3: 45 .size main, .-main 46 .ident "GCC: (GNU) 4.8.5 20150623 (Red Hat 4.8.5-39)" 47 .section .note.GNU-stack,"",@progbits
附件3-test2.s
1 .file "test.c" 2 .section .rodata.str1.1,"aMS",@progbits,1 3 .LC0: 4 .string "inline run" 5 .text 6 .p2align 4,,15 7 .globl fun 8 .type fun, @function 9 fun: 10 .LFB35: 11 .cfi_startproc 12 movl $.LC0, %edi 13 jmp puts 14 .cfi_endproc 15 .LFE35: 16 .size fun, .-fun 17 .section .text.startup,"ax",@progbits 18 .p2align 4,,15 19 .globl main 20 .type main, @function 21 main: 22 .LFB36: 23 .cfi_startproc 24 subq $8, %rsp 25 .cfi_def_cfa_offset 16 26 movl $.LC0, %edi 27 call puts 28 xorl %eax, %eax 29 addq $8, %rsp 30 .cfi_def_cfa_offset 8 31 ret 32 .cfi_endproc 33 .LFE36: 34 .size main, .-main 35 .ident "GCC: (GNU) 4.8.5 20150623 (Red Hat 4.8.5-39)" 36 .section .note.GNU-stack,"",@progbits
附件4-main.c
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <string.h> 4 #include <math.h> 5 6 #include <unistd.h> 7 #include <fcntl.h> 8 extern inline void fun(); 9 int main(int argc, char *argv[]){ 10 fun(); 11 return 0; 12 }
附件5-main.s
1 .file "main.c" 2 .text 3 .globl main 4 .type main, @function 5 main: 6 .LFB2: 7 .cfi_startproc 8 pushq %rbp 9 .cfi_def_cfa_offset 16 10 .cfi_offset 6, -16 11 movq %rsp, %rbp 12 .cfi_def_cfa_register 6 13 subq $16, %rsp 14 movl %edi, -4(%rbp) 15 movq %rsi, -16(%rbp) 16 movl $0, %eax 17 call fun 18 movl $0, %eax 19 leave 20 .cfi_def_cfa 7, 8 21 ret 22 .cfi_endproc 23 .LFE2: 24 .size main, .-main 25 .ident "GCC: (GNU) 4.8.5 20150623 (Red Hat 4.8.5-39)" 26 .section .note.GNU-stack,"",@progbits
附件6-fun.c
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <string.h> 4 #include <math.h> 5 6 #include <unistd.h> 7 #include <fcntl.h> 8 inline void fun(){ 9 printf("inline run "); 10 }
附件7-fun.s
1 .file "fun.c" 2 .section .rodata.str1.1,"aMS",@progbits,1 3 .LC0: 4 .string "inline run" 5 .text 6 .p2align 4,,15 7 .globl fun 8 .type fun, @function 9 fun: 10 .LFB35: 11 .cfi_startproc 12 movl $.LC0, %edi 13 jmp puts 14 .cfi_endproc 15 .LFE35: 16 .size fun, .-fun 17 .ident "GCC: (GNU) 4.8.5 20150623 (Red Hat 4.8.5-39)" 18 .section .note.GNU-stack,"",@progbits