Date: Mon, 27 Nov 2000 09:41:39 +0100
From: Werner Almesberger <Werner.Almesberger@epfl.ch>
egcs-2.91.66 indeed doesn't seem to make this optimization on i386.
(Maybe the pointer increment or pointer offset solution would
actually be slower - didn't check.) But I'm not sure if this is
also true for other versions/architectures, or other code
constructs.
There is no guarentee that contiguous data or bss section members
will appear contiguous and in the same order, in the final object.
In fact, a specific optimization done on MIPS and other platforms is
to place all data members under a certain size in a special
".small.data" section. So for example:
static int a;
static struct foo b;
static int b;
Would not place 'b' at "&a + sizeof(a) + sizeof(b)"
Also I believe linkers are allowed to arbitrarily reorder members in
the data and bss sections. I could be wrong on this one though.
Later,
David S. Miller
davem@redhat.com
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu Nov 30 2000 - 21:00:16 EST