Python Front-end to GCC

[Grant Edwards]

On 2013-10-22, Dave Angel <davea at davea.name> wrote:
> On 22/10/2013 08:00, Steven D'Aprano wrote:

>>     [quote]
>>     C does not require you to set static global arrays to ?0?, so the 
>>     for loop in the main function can go...
>>
>> Wait a minute... Haskell, I'm pretty sure, zeroes memory. C doesn't. So 
>
> Static int variables are in fact zeroed.  However, most C compilers
> do it by putting four bytes (or whatever) into the image of the
> executable so it has no runtime cost.

No, that's not how gcc works (nor is it how any other C compiler I've
ever seen works).  Static variables get located in a "bss" section[1],
which is zeroed out at run-time by startup code that gets executed
before main() is called.  The ELF executable contains headers that
describe the size/location of bss section, but the object file
contains no actual _data_. 

[1] IIRC, the name "bss" is a historical hold-over from the PDP-11
    assembler directive that is used to declare a section of memory
    that is to be filled with zeros.  Not all compilers use that
    section name, but they all use the same mechanism.

> int  myvar = 34 * 768;
>
> it'll put the product directly in the executable image, and no
> runtime code is generated.

That is true.

-- 
Grant Edwards               grant.b.edwards        Yow! My EARS are GONE!!
                                  at               
                              gmail.com