Compiling gcc in 64 bits mode

[kevin diggs]

Hi,

On Sat, Jul 30, 2011 at 3:48 AM, Jeremy Hall <gcc.hall@gmail.com> wrote:
>> I don't have any x86-64 (int64) systems. Is it better to use 64-bit on
>> x86-64 even with the larger memory footprint (because the programming
>> model is better (more registers, etc))?
>
> I'd say yes.   As you suggest, there is more to x64 than the memory
> footprint.  There are there are twice as many general purpose
> registers amongst other things.   So for example more function
> arguments are passed in registers than on the stack.
>
> Here are some figures for a small program compiled identically on both
> 32 and 64 bits.
>
> 32 bit code
>   Insns 15506,  Jumps 3218,  Mem refs 3819,  Stack refs 1671
> 64 bit code
>   Insns 14631,  Jumps 3158,  Mem refs 3142,  Stack refs 1042
>
> The 64 bit executable was only about 10% larger.
>
> Jeremy
>

I was actually referring to the runtime size (data segment). I've
never actually tried to build a PPC 64-bit Firefox (i.e. I have a
64-bit PPC box). I'd like to see the data size usage compared to
32-bit.

kevin