Re: stupid pointer alignment question (re: cernlib on m68k)
> I am wondering: will g77 et al. cause programs to automatically align all
> 32-bit integers in memory with pointers that are multiples of 4 bytes?
> (Given that the integers are array elements that aren't members of any
> other structure, and exist at compile time.) Because I'm seeing a bug in
> pawX11.static (in cernlib's paw-static package) on m68k that appears to
> result from a violation of that assumption.
I don't think there's such a thing as automatic alignment to 4 byte
boundaries on m68k, so the assumption would be unjustified:
Control whether GCC aligns "int", "long", "long long", "float",
"double", and "long double" variables on a 32-bit boundary
(-malign-int) or a 16-bit boundary (-mno-align-int). Aligning
variables on 32-bit boundaries produces code that runs somewhat
faster on processors with 32-bit busses at the expense of more mem-
Warning: if you use the -malign-int switch, GCC will align struc-
tures containing the above types differently than most published
application binary interface specifications for the m68k.
(taken from gcc 3.3 info)
Note that this option is new in gcc 3 - gcc 2.95 didn't have it. And (in
accordance with above warning) it doesn't seem to be active by default.