This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: PATCH column number support
On Thu, Dec 04, 2003 at 12:47:43PM -0800, Per Bothner wrote:
> However, my guess is the remaining bugs may be in cpplib
> itself, rather than the line-map.[ch], and in any case it's
> useful to get feedback on the API.
The API looks good. Thanks.
> One implementation detail: I still use shifts and masks to
> separate out the column number. An alternative might be
> to use division ('/' and '%' instead). E.g. instead of:
>
> (loc - map->start_location) >> map->column_bits
>
> do
>
> (loc - map->start_location) / map->column_limit
>
> where column_limit replaces (1 << column_bits). Doing a division
> makes the code a bit cleaner, plus we aren't limited to powers of 2.
Given that replacing division with pre-calculated mult+shift
tables in ggc-page made a real difference on modern machines,
I wouldn't discount the cost.
Lets leave the shift for now.
r~