http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48006
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-03-07
10:23:11 UTC ---
I think what you are seeing is type-based alias analysis at work. When using
unsigned long long you get no aliasing of the accesses to *rows to the
nrows, ncols ... members (they use size_t which is unsigned long). But as
soon as you change the typedef to unsigned long (which means the same type
as size_t) then the compiler has to assume all stores to *rows alias the
size_t members and so their loads are not hoisted out of the loop.
You should probably try to play with restrict qualifying some of the pointers
to tell the compiler that *rows does not point to nrows.
