[Bug libstdc++/11706] std::pow(T, int) implementation pessimizes code

["rguenth at tat dot physik dot uni-tuebingen dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From rguenth at tat dot physik dot uni-tuebingen dot de  2004-03-11 20:14 -------
Subject: Re:  std::pow(T, int) implementation pessimizes
 code

gdr at integrable-solutions dot net wrote:
> ------- Additional Comments From gdr at integrable-solutions dot net  2004-03-10 20:43 -------
> Subject: Re:  std::pow(T, int) implementation pessimizes code
> 
> "pcarlini at suse dot de" <gcc-bugzilla@gcc.gnu.org> writes:
> 
> | ------- Additional Comments From pcarlini at suse dot de  2004-03-10 20:26 -------
> | Subject: Re:  std::pow(T, int) implementation pessimizes
> |  code
> | 
> | gdr at integrable-solutions dot net wrote:
> | 
> | >Did you get the report that ::pow() is no longer inlined?
> | >  
> | >
> | Why, now you are discussing ::pow, if in your comment #6 and #8 you
> | emphasized that we should not use ::pow?
> 
> I'm discussing ::pow() because that is what the reporter wanted V3 to
> use. I emphasize against those, and I would strongly advise against
> any patch that does that.  Which is why I'm telling you that upfront
> before you waste your time in that direction.
> The only fix that I should have applied is to make __cmath_power()
> inline.  Any other if or #if are just papering over the fundamental
> problem. That is not fix.

As I said numerous times, inlining __cmath_power() will make things 
worse, because you need a _very_ clever inliner to notice the profitable 
cases.  My preffered solution would be a added __builtin_cmath_power() 
with appropriate folders.

Richard.



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11706