gdtr value

Anuz Pratap Singh Tomar chambilkethakur at gmail.com
Mon Feb 18 10:05:21 EST 2013


On Mon, Feb 18, 2013 at 5:07 AM, horseriver <horserivers at gmail.com> wrote:

> hi:)
>
>   I have compiled a .S file ,using command gcc -c x.S -o x.
>   Then I use objdump to look up its asm code, even find that some code is
> not the
>   same as that .S file , more important is , some code in origin  .S file
> has disappear .
>
>   what is about the reason ? If it is due to version , why some code
> chould get lost after compile?
>
> Couple of things
1. Please don't piggy back questions over the unrelated topic, that is
totally misdirecting the discussion.
2. You ask a lot of question related to compilation and stuff, which are
off-topic here, why not READ a little bit more or consult relevant
documentation?
3. You seem to do no homework before asking viz googling or reading basic
books on relevant topic for example in this case reading a book on assembly
language programming.

When you write any assembly code(or for that matter any code) your code is
written to be read by HUMANS and not machines. For machines a lot of that
code is redundant and has no use so machine code will be generated in such
a form that it is most optimized for the execution. For example take any
*.c code and do

#gcc -S *.c
you will see an equivalent assembly code. It may not exactly be similar to
the code which you will write in assembly for same logic. There are some
rules according to which compilers generate code, please read some book on
compilers and lex and yacc.




> thanks!
>



-- 
Thank you
Warm Regards
Anuz
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