Stack space and declarations

[Václav Haisman]

Andreas Pfeil wrote:
> Hi,
> 
> which architecture are you talking about? On PowerPC, if none of the
> variables are marked volatile, then probably no stack space will be
> allocated for the variables. This depends on the ABI of the processor,
> I'd believe.
I understand that the whole thing can be architecture dependent.

The code is just for illustration. Let's say that the variables are all
used in //some code and that the compiler will have to store them onto
the stack. On x86 it would be because of lack of registers. What I want
to know is what is the general approach that the compiler takes. In
other words, does this theoretically lessen stack space pressure?

> 
> Cheers,
> Andreas
> 
> Václav Haisman wrote:
> 
>> Hi,
>> first some C code:
>>
>> void foo (int x)
>> {
>>   int y = 0;
>>   if (x) {
>>     int z = 0;
>>     // some more code
>>   }
>>   else {
>>     int w = 0;
>>     // some more code
>>   }
>> }
>>
>> Now, how much stack space is getting allocated in the function? Is it
>> (assuming 32bit architecture) 2*4=8 bytes (y + (z or w)) or is it 3*4=12
>> (each variable gets its own slot)?
>>
>>
>> Vaclav Haisman

Vaclav Haisman

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 546 bytes
Desc: OpenPGP digital signature
URL: <https://gcc.gnu.org/pipermail/gcc-help/attachments/20051216/b8bfa913/attachment-0001.sig>