On 07/03/2014 06:12 PM, DJ Delorie wrote:
The hardware transfers data in and out of byte-oriented memory in
TYPE_SIZE_UNITS chunks. Once in a hardware register, all operations
are either 8, 16, or 20 bits (TYPE_SIZE) in size. So yes, values are
padded in memory, but no, they are not padded in registers.
Setting TYPE_PRECISION is mostly useless, because most of gcc assumes
it's the same as TYPE_SIZE and ignores it.
That's what'll need fixing then. I doubt there are too many places that
require changing.
Also, the above seems inaccurate:
$ grep TYPE_PREC *.c|wc -l
633
$ grep TYPE_SIZE *.c|wc -l
551
Heck, most of gcc is
oblivious to the idea that types might not be powers-of-two in size.
GCC doesn't even bother with a DECL_PRECISION.
Sure - why would you even need one?
Thus, in these cases, TYPE_SIZE and TYPE_SIZE_UNIT no longer have
a "* BITS_PER_UNIT" mathematical relationship.
I'm skeptical this can work, it's pretty fundamental.
It seems to work just fine in testing, and I'm trying to make it
non-fundamental.
I also think this is not a very good idea.
Bernd
