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Re: GSOC Student application
On 2008/3/30, Alexey Salmin <firstname.lastname@example.org> wrote:
> > There are issues of Garbage Collection from libgcc or Boehms's GC
> > that you possibly can't use another allocators that these defaults,
> > unless you have control of the manager of the whole memory,
> > and it's too complex due to the gigant size of the project.
> salmin@salmin:~/gcc/src/include$ grep XNEW libiberty.h
> #define XNEW(T) ((T *) xmalloc (sizeof (T)))
> #define XNEWVEC(T, N) ((T *) xmalloc (sizeof (T) * (N)))
> #define XNEWVAR(T, S) ((T *) xmalloc ((S)))
> salmin@salmin:~/gcc/src/libiberty$ grep -A 11 '^xmalloc (' xmalloc.c
> xmalloc (size_t size)
> PTR newmem;
> if (size == 0)
> size = 1;
> newmem = malloc (size);
> if (!newmem)
> xmalloc_failed (size);
> return (newmem);
> So, you can see that XNEW* macro are now exactly the same as just
> malloc function and they were added only for possible future change of
> the memory allocator.
> Any malloc function should be repalced with this macro AFAIK.
> And the worst thing I can see in the code is freeing the memory
> allocated with XNEW macro. It works fine now but it's wrong as I
> salmin@salmin:~/gcc/src/libcpp$ grep XNEW * | wc -l
> salmin@salmin:~/gcc/src/libcpp$ grep XDELETE * | wc -l
> salmin@salmin:~/gcc/src/libcpp$ grep free * | wc -l
> salmin@salmin:~/gcc/src/libcpp$ grep malloc * | wc -l
> > You must know that before optimizing anything, you must profile the
> > whole code (-pg, gprof, ...) and study the beautiful formula of
> > "Amdahl's Law" for sequential machines in some books.
> > Studied this law, you can optimize better than your previous knowledge.
> I know what profiling is. And I know how parallel programs work,
> thanks. I'm just talknig here about distinct improvements I can do,
> not about some abstract optimizing.
> > Luck U.S.S.R. boy ;)
> Yes, I've been living in USSR for 2 first years of my life :)
$ objdump -t libexec/gcc/i686-pc-linux-gnu/4.4.0/cc1 | cut -c48- | \
grep -i alloc | sort -u
There are aprox. 95 symbols related to *alloc* as by example
malloc, calloc, ealloc, ecalloc, etc.
It's good idea to deforest some different symbols from this
forest of *alloc* to use common symbols.