Question

I need to understand some internals of data structures by generating the assembly code for functions and global, local structures, variables.

From this link:

http://axelio.wordpress.com/2007/07/24/be-careful-with-packed-structures/

I can see that the structure members are shown the allocated size explicitly in assembly code.

_my:
    .byte   10  <--- c
    .long   20  <--- i
    .byte   30  <--- s.c
    .space 3    <--- 3 bytes of alignment
    .long   40  <--- s.i

How to generate this kind of assembly.
Using

# gcc -S  file.c 

didnot generate the above output for structures.

Answer 1

It does.

struct S
{
  int x;
  float y;
};

struct S t = {
  .x = 10,
  .y = 1.0
};

Compile with gcc -S strasm.c

And in resulting strasm.s you will see:

  .data
  .type t, @object
  .size t, 8
t:
  .long 10
  .long 1065353216

All you need is explicitly initialized object.