C 编译过程浅析

 

    From where i stand,

        there are two programmig languages in the world,

            which is C lang and the other.

　

编译(compile)

• 预处理(也称预编译，Preprocessing)
• 编译(Compilation)
• 汇编 (Assembly)
• 连接(Linking)

GCC参考

gcc - GNU project C and C++ compiler

If you only want some of the stages of compilation, you can use -x (or filename suffixes) to tell gcc where to start, and one of the options -c, -S, or -E to say where gcc is to stop. Note that some combinations (for example, -x cpp-output -E) instruct gcc to do nothing at all.

• -E Stop after the preprocessing stage; do not run the compiler proper.
• -S Stop after the stage of compilation proper; do not assemble.
• -c Compile or assemble the source files, but do not link.
• -o targetfile Place output in file targetfile.

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[root@standby gcc]# date +%F_%H:%M:%S
2016-11-29_23:31:29
[root@standby gcc]# pwd
/data/gcc
[root@standby gcc]# ll
total 4
-rw-r--r-- 1 root root 82 Nov 29 23:27 hello.c
[root@standby gcc]# cat hello.c 
#include <stdio.h>
int main(void)
{
    printf("Hello World!
");
    return 0;
}
[root@standby gcc]# 
[root@standby gcc]# file hello.c
hello.c: ASCII C program text
[root@standby gcc]#

预处理/Preprocessing

'删除注释和";"、进行宏替换、将头文件插入进来、条件编译等'

[root@standby gcc]# gcc -E hello.c -o hello.i
[root@standby gcc]# ll
total 24
-rw-r--r-- 1 root root    82 Nov 29 23:27 hello.c
-rw-r--r-- 1 root root 16742 Nov 29 23:58 hello.i
[root@standby gcc]# file hello.i
hello.i: ASCII C program text
[root@standby gcc]#

编译/Compilation

'生成汇编代码'

[root@standby gcc]# gcc -S hello.i -o hello.s
[root@standby gcc]# ll
total 28
-rw-r--r-- 1 root root    82 Nov 29 23:27 hello.c
-rw-r--r-- 1 root root 16742 Nov 29 23:58 hello.i
-rw-r--r-- 1 root root   444 Nov 30 00:00 hello.s
[root@standby gcc]# file hello.s
hello.s: ASCII assembler program text
[root@standby gcc]#

汇编/Assembly

'生成目标文件'

[root@standby gcc]# gcc -c hello.s -o hello.o
[root@standby gcc]# ll
total 32
-rw-r--r-- 1 root root    82 Nov 29 23:27 hello.c
-rw-r--r-- 1 root root 16742 Nov 29 23:58 hello.i
-rw-r--r-- 1 root root  1504 Nov 30 00:03 hello.o
-rw-r--r-- 1 root root   444 Nov 30 00:00 hello.s
[root@standby gcc]# file hello.o 
hello.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped
[root@standby gcc]#

连接/Linking

'生成可执行文件'

[root@standby gcc]# gcc hello.o -o helloworld
[root@standby gcc]# ll
total 40
-rw-r--r-- 1 root root    82 Nov 29 23:27 hello.c
-rw-r--r-- 1 root root 16742 Nov 29 23:58 hello.i
-rw-r--r-- 1 root root  1504 Nov 30 00:03 hello.o
-rw-r--r-- 1 root root   444 Nov 30 00:00 hello.s
-rwxr-xr-x 1 root root  6425 Nov 30 00:04 helloworld
[root@standby gcc]# file helloworld 
helloworld: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, not stripped
[root@standby gcc]# 
[root@standby gcc]# ./helloworld 
Hello World!
[root@standby gcc]#

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汇编代码

[root@standby gcc]# cat hello.s 
    .file    "hello.c"
    .section    .rodata
.LC0:
    .string    "Hello World!"
    .text
.globl main
    .type    main, @function
main:
.LFB0:
    .cfi_startproc
    pushq    %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register 6
    movl    $.LC0, %edi
    call    puts
    movl    $0, %eax
    leave
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE0:
    .size    main, .-main
    .ident    "GCC: (GNU) 4.4.7 20120313 (Red Hat 4.4.7-17)"
    .section    .note.GNU-stack,"",@progbits
[root@standby gcc]#