On Mon, 19 Mar 2007, Doug Gregor wrote:
> 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.
So, about 16% slower with --enable-checking, 5% slower with
--disable-checking.
Subcodes might still be the way to go, but I'm feeling less bad about
the 9-bit tree code option.
As an interested outsider: GCC's compile-time speed has been gradually
decreasing for a while now. It seems to be acknowledged as an undesirable
thing, but not much has happened to change it. AIUI, this is largely
because it's very difficult. Nonetheless, seeing a 5% slow-down caused by
fixing a data structure design bogon is disappointing.
Nick
