------- Comment #11 from dnovillo at gcc dot gnu dot org 2006-12-14 19:29
-------
(In reply to comment #10)
> (In reply to comment #9)
> > (In reply to comment #8)
> > > There must be. mem-ssa is @119760. If you can reproduce with @119760,
> > > then
> > > let me know and I'll take a look.
> >
> > I can reproduce it at @119761 which is the same revision for the trunk as
> > 119761 was a revision on a branch.
> >
> OK, I'll take a look. FX mind sending me that data about the test? I can't
> reproduce it locally.
>
Oh, boy. Now I see it. We are making different partitioning decisions because
the order of the symbols in the partitioned alias set changed. So, sometimes
we get one SFT into a partition which just happens to cross a call-site, and if
it's added to the partition, we miss the optimization. In this case, the SFT
associated with b.s.w is added to MPT.69.
<L1>:;
# MPT.69_8 = VDEF <MPT.69_7(D)> { MPT.69 }
b.s.w = 3;
# VUSE <SFT.54_9(D), SFT.55_10(D), SFT.56_11(D)> { SFT.54 SFT.55 SFT.56
SFT.62 }
# SFT.62_13 = VDEF <SFT.62_12(D)>
# MPT.69_14 = VDEF <MPT.69_8> { SFT.62 MPT.69 }
x = bar1 (*c_1, *c_1);
# VUSE <MPT.69_14> { MPT.69 }
D.1993_6 = b.s.w;
But if aliases are stored in different order in the alias set (different
DECL_UID assignment), we just happen not to choose this SFT for partitioning,
leaving the IL as:
<L1>:;
# SFT.61_8 = VDEF <SFT.61_7(D)> { SFT.61 }
b.s.w = 3;
# VUSE <SFT.58_9(D), SFT.59_10(D), SFT.60_11(D), SFT.61_8> { SFT.58 SFT.59
SFT.60 SFT.61 }
# MPT.69_13 = VDEF <MPT.69_12(D)> { MPT.69 }
x = bar1 (*c_1, *c_1);
# VUSE <SFT.61_8> { SFT.61 }
D.1990_6 = b.s.w;
I will workaround this by increasing partitioning thresholds on this test, for
now, but I will leave the PR assigned to me while I figure out better
partitioning heuristics.
--
dnovillo at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |dnovillo at gcc dot gnu dot
|dot org |org
Status|UNCONFIRMED |ASSIGNED
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2006-12-14 19:29:22
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30194
