On 3/12/07, Steven Bosscher <[EMAIL PROTECTED]> wrote:
On 3/12/07, David Edelsohn <[EMAIL PROTECTED]> wrote:
> I thought that the Tuples conversion was suppose to address this
> in the long term.
The tuples conversion is only going to make things worse in the short term.
Doug, isn't there a lang_tree bit you can make available, and use it
to make the tree code field 9 bits wide? I know this is also not
quite optimal,
It's going to have a big performance impact. To extract a 9-bit value,
the compiler will need to do a lot of masking every time it accesses
the TREE_CODE. We need the size of CODE to match the size of a
built-in integer type, which means we need to either expand the
structure or find 8 (!) free bits to shuffle.
but adding 24 bits like this is an invitation to
everyone to start using those bits, and before you know it we're stuck
with a larger-than-necessary tree structure... :-(
Yep, that's what got us where we are today. We said, "oh, we'll never
need more than 256 codes, let's use the other 24 bits for flags!"
Cheers,
Doug
