[ET Trac] [Einstein Toolkit] #437: Correct autoconfiguration of restrict keyword; add support for builtin_expect

[Erik Schnetter]

On Sun, Jun 5, 2011 at 2:59 PM, Einstein Toolkit
<trac-noreply at einsteintoolkit.org> wrote:
>  This sounds like potentially quite a nice addition. How difficult would it
>  be to take this further and enable the use of profile guided optimization
>  (eg. http://stackoverflow.com/questions/2738835/learning-sample-of-likely-
>  and-unlikely-compiler-hints). Do you think it would be likely to help
>  much?

Profile-guided optimisations need to be handled differently, namely
via compiler options, not via source code annotations. One also needs
a representative test case. I assume the main problem with this is to
ensure that the compiler can make the necessary connections between
executable, object files, and source files, which often fails since
Cactus places object files in libraries.

Apart from this, PGO would just involve experimenting with compiler
options to see whether one can obtain a performance benefit.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/