This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug middle-end/44382] Slow integer multiply
- From: "wschmidt at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 13 Oct 2011 17:30:14 +0000
- Subject: [Bug middle-end/44382] Slow integer multiply
- Auto-submitted: auto-generated
- References: <bug-44382-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44382
--- Comment #9 from William J. Schmidt <wschmidt at gcc dot gnu.org> 2011-10-13 17:30:14 UTC ---
Just adding some status information well after the fact...
We experimented with adding powerpc64 hooks to use the parallel reassociation
support from comment #8. We elected not to enable this support because the
results for SPEC were negative (quite negative in some cases), due to increased
register pressure in loops where spill was already an issue. Our plans at this
point are to live with the left-linear association, at least until the spill
costs can be mitigated in some fashion.
If parallel reassociation had some heuristics that predicted for register
pressure (difficult in tree-ssa, I know), it might become practical for us.