This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: RTL
Sir,
you told that stack is 16 byte aligned for the MMX/SSE/SSE2
instructions..I can see that the structure and array declarations are
also 16 byte aligned..is this also for the same purpose?..
In the RTl file all the strings will be replaced by some *.LC0 *.LC1
etc..where exactly is this strings stored? how you are accessing it?
Reply me please..
Thanking you ,
Sruthy C.N.
SRUTHY C.N.
> Sruthy C.N wrote:
>> In the RTL file (gcc version 3.2.2) there is some
>> instructions(insn
>> 6,8,10,12) which do some manipulations on esp..what is it doing?
>
> As I mentioned in a previous message, it is aligning the stack in main
> to a 16 byte boundary. I believe this is for the MMX/SSE/SSE2
> instructions, which are faster if the stack is 16 byte aligned. Some
> systems don't align the stack to 16 bytes at program startup, so we do
> it in main. This extra instruction only occurs in the main function.
>
>> If we consider the assembly program corresponding to this
>> there is
>> no such instructions corresponding to this..why?
>
> Please give a testcase. I suspect you got your examples mixed up. Or
> maybe it got optimized away, though that seems unlikely.
> --
> Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com