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[Bug rtl-optimization/38583] [4.4 Regression] ira memory explosion
- From: "vmakarov at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 30 Dec 2008 14:33:52 -0000
- Subject: [Bug rtl-optimization/38583] [4.4 Regression] ira memory explosion
- References: <bug-38583-6642@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #1 from vmakarov at redhat dot com 2008-12-30 14:33 -------
I don't think that the problem occurred because of transition to IRA. The old
register allocator (-fno-ira) uses about the same size conflict table and peak
virtual memory (it is 9230MB for the old RA on this case). So original reason
for the degradation is in some other compiler changes.
Saying that we still need to prevent building huge conflict tables (although
the old RA and IRA have sophisticated algorithms for the table compression
resulting to 2000 times smaller size in some extreme cases). I'll make patch
to prevent building conflicts and to use allocation without allocno conflicts
for such extreme cases on next week.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38583