[Bug rtl-optimization/17950] Over Aggressive Use of Data Cache Touch Instructions During FDO

[jgrimm2 at us dot ibm dot com]

------- Additional Comments From jgrimm2 at us dot ibm dot com  2004-11-18 01:32 -------
Hmmm... looks like a couple things (maybe more) come in to play here.  First,
value-profile code doesn't seem to merge prefetches (among other things).  That
is, it should be pretty easy (crude?) to track the last prefetch and not
prefetch addresses that look close.  Doing so seems to help this test case quite
a bit (96 prefetches down to 24), but probably not enough..... as it seems that
the loop unroller comes through afterwards and does its damage too.   Might need
to teach the unroller about prefetch a bit too??


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jgrimm2 at us dot ibm dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17950