[Bug regression/16703] [3.5 Regression] g++ v3.5.0 produces slower code than v3.4.1 for loops.

["godaves at yahoo dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From godaves at yahoo dot com  2004-07-26 00:13 -------
(In reply to comment #3)
> Well, those benchmarks are highly artificial, and therefore of doubtful
> value. They certainly also don't all measure the same thing. Moreover, if

The point of the report and the simple code submitted with it is to hopefully
provide the code-gen team with some low-hanging fruit to determine the reason
for the lower performance, especially given that SSA/GENERIC/GIMPLE has been
mainlined in 3.5.0.

Granted, the differences aren't that great but the performance does regress a
bit for this trivial code, at least with the 20040718 build, so I think the
heads-up is prudent.

I'll give it a shot with the 20040725 build that just became available as well,
when/if I get the time.

> you're interested in loop performance, you should really try the lno branch,
> since that is the only place where loop work is going on. It already brings
> some progress, for example "nestedloop" is about 746 times faster :-)
> 
> I suggest you retry with lno-branch, and then single out benchmarks which
> shows really noticeable (say, >50%) regression.

Since computers spend a great deal of their time looping, I'm very interested in
loop performance. And if you have some benchmarks in mind, don't hesitate to
pass them along.

When is the lno-branch due to be mainlined?


-- 
           What    |Removed                     |Added
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  GCC build triplet|                            |20040718


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16703