interesting metric

[Ron Young]

Steve Kargl wrote:
> On Sat, Aug 05, 2006 at 12:04:09AM -0400, Jack Howarth wrote:
>   
>>     Interesting, XL Fortran at -O3 produces exactly the same time as
>> gfortran at -O3 (121.8 seconds). At -O4, XL Fortrans is slightly 
>> faster (114.8 seconds), but only at -O5 does it break away (52.7 seconds).
>> The difference between -O4 and -O5 in XL Fortran is "-qipa=level=2"
>> which is...
>>
>>                        Full interprocedural data flow and  alias
>>                         analysis.
>>
>> Doesn't profiled IPA exist in gcc? I tried the following...
>>
>>     
>
> There is an ipa branch where changes are merged
> back into trunk.  I don't know what the status is
> with respect to performance. 
>
>   
Inlining the functions v and dv more than makes up the time difference. 
For one thing it would save one of sin calls.

! vr = sin(min(x,PI2))**2
pot = pot + 0.5_DP*sin(min(d,PI2))**2
! dvr = 2.0_DP*sin(min(x,PI2))*cos(min(x,PI2))
dvr = 2.0_DP*sin(min(d,PI2))*cos(min(d,PI2))
do k=1,nd
f(k,i) = f(k,i) - rij(k)*dvr/d
enddo

Ron Young