D2 is really that stable as it is claimed to be?

[Iain Buclaw]

On 22 September 2013 20:27, Walter Bright <newshound2 at digitalmars.com> wrote:
> On 9/22/2013 11:43 AM, Timon Gehr wrote:
>>
>> Tracking line numbers is likely worth it. I don't believe that providing
>> column
>> numbers in error messages necessitates a slowdown though.
>
>
> Please consider that:
>
>      IT ISN'T JUST FOR ERROR MESSAGES
>
> It would go in the symbolic debug info, too, where it will be required
> everywhere and will be right there on the fast path through the
> lexer/compiler.
>
> Now consider the lexer doing a fast skip over comment text (this ranks
> fairly high in the profile). This operation gets a lot slower if you're also
> keeping track of column number. Please note that:
>
>      COLUMN NUMBER ISN'T THE OFFSET FROM THE START OF THE LINE
>
> because of tabs and UTF-8 sequences.
>
> Any proposal for column number tracking must take these issues into account.
>
> Also note that g++ and clang are hardly noted for their fast compile speeds.
> Also note that g++'s compile speed has dropped significantly lately - I
> don't know why, but it also added column number support recently (!).

Depends on what you mean by "recently".  GCC has certainly gained a
fair few compilation/optimisation passes over the past few releases.

4.3 - 223 passes  (2008)
4.4 - 225 passes  (2009)
4.5 - 239 passes  (2010)
4.6 - 241 passes  (2011)
4.7 - 252 passes  (2012)
4.8 - 268 passes  (2013)
4.9 - 269 passes  (development)

And showing column numbers has been turned on since gcc-4.4 (released in 2009).


Regards
-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';