reference to memcpy

[gedeon]

Hi , i have the following problem
when i start make for my os project i have this error :
undefined reference to 'memcpy'

but i don't use memcpy

on my old system with gcc 3.2.2 it works fine

with gcc 3.3 it doesn't why ?
maybe the change between this two version is the problem

is there a command option to workarround this problem ?

[Pype.Clicker]

GCC may need memcpy to perform language operations like structures copies (i.e. when you have struct stuff=other_stuff;). The easiest workaround is to provide your own memcpy function, for instance with

Code: Select all

static inline void *memcpy(void *dest, const void *src, int n) {
   char *dst=dest; 
   for (;n;n--,dest++,src++)
        *dst=*((char*)src);
    return dest;
}

or any equivalent code you might find smarter (using rep stosb, or using integer moves rather than byte moves when both addresses are aligned on an integer boundary and n>4 ... whatever ...)

[gedeon]

Thanks a lot , it works fine

In order to understand , why the problem appears ?

I have not changed my source code when i have switched my systems. And with GCC 3.2, there was no error.

Does anymore function that i have to provide ?

[kaos]

Thanks a lot , it works fine

In order to understand , why the problem appears ?

I have not changed my source code when i have switched my systems. And with GCC 3.2, there was no error.

Does anymore function that i have to provide ?

It is hard to say why really. I'd think that both versions would have a memcpy() builtin. Have you changed the command line arguments? Are you building on the same OS with a different compiler or are there other differences? Were the compilers built the same?

Upgrading to a new version of gcc doesn't usually break code; they are pretty good about that sort of thing. In general, gcc is a fantastic compiler.

Gas, on the other hand, is a monstrosity... but I digress.

[gedeon]

The code source didn't change

before
red hat 9, kdevelop 2.1.5, gcc 3.2.2

after
Suse 8.2 , kdevelop 2.1.5, gcc 3.3

strange !!!