Re: [PLUG] RedHat 7.1 glibc2.1 Backward compat - revisited

[Walt Mankowski <walt@verne.myxa.com>]

On Thu, May 24, 2001 at 04:59:30PM -0400, Mental wrote:
> The main reason you've never heard of this so much is because its the
> compilers job to do this. Sure, we could all be men and use punch cards,
> or manually manipulate the inodes on the disk with a magnet, but I'm lazy.
> I'd much rather let gcc worry about byte boundaries and alignment. So
> would lots of other lazy people. Thats what the -m switches are for in gcc
> :)

I've run into issues exactly like this on other platforms.  Imagine a
structure that looks like this:

struct foo {
	char c;
	int i;
}

It may look like i still start one byte after c, but in fact for
performance reasons the compiler may decide to insert some filler so
that i can start on an even-byte or perhaps a 4-byte boundary.  We
were moving some code from a 16-bit to a 32-bit box, and discovered
that the compiler now wanted to line up int's on addresses divisible
by 4 instead of by 2.

Walt


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