Kazu Hirata wrote:
To see what kind of code GCC generates for FOR_EACH_EDGE, I wrote a simple dummy function.
Kazu, I hope I have time to look in detail at your investigation, however one thing that might be causing a problem is that FOR_EACH_EDGE is an iterator that works for a non-constant VEC. This means there's an extra level of indirection that the optimizer cannot remove, unless it completely inlines the body of the loop (there might be some cases it can do it without inlining, but I suspect not). I wonder if it is worthwhile implementing FOR_EACH_EDGE and FOR_EACH_EDGE_VOLATILE (I want the default, shorter name, to be the constant iterator, so that you have to chose to use the non-constant one).
Even with a constant iterator, it might be necessary to help the optimizer by copying the vector length to somewhere local that the optimizer can see cannot be changed by the body of the loop. Hmm, I guess that does mean you need a proper iterator object, rather than the integer index that VEC_iterate employs.
nathan
-- Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC [EMAIL PROTECTED] :: http://www.planetfall.pwp.blueyonder.co.uk
