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[Bug target/23322] [4.1/4.2/4.3 regression] performance regression
- From: "hubicka at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 6 Feb 2008 11:55:15 -0000
- Subject: [Bug target/23322] [4.1/4.2/4.3 regression] performance regression
- References: <bug-23322-10914@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #27 from hubicka at gcc dot gnu dot org 2008-02-06 11:55 -------
I noticed those posts. Part of the problem might be that hoisting triggers the
partial memory stall bug I fixed. Partial memory stalls are quite expensive, so
this might improve scores without the hack in some cases. I will at least give
it a try on SPECs.
Also with DF merge we ought to have liveness readily available? Perhaps we can
just strictly special case the initialization loop: count number of FP regs
touched by loop live across loop latch edge and if the constant is at most 1
allow one extra invariant to be lifted. Naturally this is as ugly as it can
get, prettier solution would be preferred...
Honza
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23322