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[Bug tree-optimization/32901] [4.1/4.2/4.3 regression] bitfield constants with multiple bitfields take up space in .data
- From: "jakub at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 4 Dec 2007 19:58:14 -0000
- Subject: [Bug tree-optimization/32901] [4.1/4.2/4.3 regression] bitfield constants with multiple bitfields take up space in .data
- References: <bug-32901-11199@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #7 from jakub at gcc dot gnu dot org 2007-12-04 19:58 -------
The problem is that we really don't have any optimization which would before
expand merge all the sets to adjacent bitfield fields into one (or few)
BITFIELD_REFs. If we are lucky and the RTL passes merge it together,
initializing small structs containing bitfields this way will be a win, but
it might be an pessimization as well.
BTW, shouldn't TER try to merge several consecutive initializations of fields
of one aggregate into a CONSTRUCTOR again, so that RTL expanders can do better
job on it? This wouldn't be the only bug which could be helped by that.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32901