Generating a Mixed Source and Assembly List Using GCC

When do debugging and optimization, we sometimes need to generate and investigate into the assembly generated by the compiler. Generating a mixed source and assembly list will help the programmer a lot for debugging and optimization. gcc can achieve this by working the the assembler.

Generate assembly list mixed with the source code

Just add these gcc compile options:

-Wa,-adhln -g

The command:

$ gcc -Wa,-adhln -g source_code.c > assembly_list.s

The options:

 -g: Produce debugging information
 -Wa,option: Pass option as an option to the assembler
 -adhln:
 a: turn on listings
 d: omit debugging directives; n: omit forms processing
 h: include high-level source
 l: include assembly

One example

The source code:

helloworld.c:

#include <stdio.h>
int main()
{
  printf("Helloworld!n");
  return 0;
}

The command:

$ gcc -Wa,-adhln -g helloworld.c > helloworld.s

helloworld.s:

...

0:helloworld.c  **** #include <stdio.h>
1:helloworld.c  ****
2:helloworld.c  **** int main()
3:helloworld.c  **** {
19                            .loc 1 4 0
20                            .cfi_startproc
21 0000 55                    pushq   %rbp
22                    .LCFI0:
23                            .cfi_def_cfa_offset 16
24 0001 4889E5                movq    %rsp, %rbp
25                            .cfi_offset 6, -16
26                    .LCFI1:
27                            .cfi_def_cfa_register 6
4:helloworld.c  ****   printf("Helloworld!n");
28                            .loc 1 5 0
29 0004 BF000000              movl    $.LC0, %edi
29      00
30 0009 E8000000              call    puts
30      00
5:helloworld.c  ****   return 0;
31                            .loc 1 6 0
32 000e B8000000              movl    $0, %eax
32      00
6:helloworld.c  **** }

...

Updated history
17 Mar. 2010. Add example source code.
24 Feb. 2010.
Oct. 19, 2011. revise and make the writting better.