http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49851
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-07-26
14:32:35 UTC ---
(In reply to comment #2)
> AIR spends 86% of its time in DERIV[XY] (for ICC), 78% of its time there for
> GCC.
> The performance difference also reproduces when not inlining DERIV[XY] at all
> (though it's slightly less of a difference - GCC doesn't care).
Actually it does not. Without inlining:
GCC: air 2.42 4728556 3.99 10 0.1798
SUBROUTINE DERIVX(D,U,Ux,Al,Np,Nd,M) /* derivx_ total: 8194999 42.3750 */
SUBROUTINE DERIVY(D,U,Uy,Al,Np,Nd,M) /* derivy_ total: 8176250 42.2781 */
ICC: air 2.90 4072563 3.45 10 0.1809
SUBROUTINE DERIVX(D,U,Ux,Al,Np,Nd,M) /* derivx_ total: 8060834 47.2620 */
SUBROUTINE DERIVY(D,U,Uy,Al,Np,Nd,M) /* derivy_ total: 7070627 41.4563 */
so not much difference in the total hits. Which means ICC performs some
context-dependent optimization.
