[Bug tree-optimization/39839] [4.3/4.4/4.5 regression] loop invariant motion causes stack spill

[vmakarov at redhat dot com]

------- Comment #3 from vmakarov at redhat dot com  2009-04-22 20:37 -------
Actually YARA did not have a rematerialization as IRA.  Reload has a primitive
rematerialization of constant values.

Although about 5 years I did implemented a register pressure relief through
rematerialization which is close to Simpson's thesis.  It was reported on the
2nd GCC summit.  I had a mixed feeling about this: wrong register pressure
calculation (because we have not cover classes at that time), small improvement
but a few additional percents to compilation time.

Probably it is time to return to this and make it optional or default which
will eat a chunk of your recent 5% compilation time improvement :)  I'll try to
include this in my plans.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39839