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[Bug rtl-optimization/33922] [4.3 Regression] slow compilation on ia64 (postreload scheduling)
- 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: 1 Nov 2007 20:59:37 -0000
- Subject: [Bug rtl-optimization/33922] [4.3 Regression] slow compilation on ia64 (postreload scheduling)
- References: <bug-33922-12387@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #22 from jakub at gcc dot gnu dot org 2007-11-01 20:59 -------
The most important cause of the slowdown e.g. compared to 4.2.x is the totally
insane thing -ftree-pre creates though.
For -O3 -fno-tree-vectorize -fdump-tree-all pr33922.c
wc -l shows
2361 pr33922.c.090t.sink
while for -O3 -fno-tree-vectorize -fno-tree-pre -fdump-tree-all pr33922.c
324 pr33922.c.090t.sink
and of course the size of assembly corresponds to this:
11400 pr33922.s # -O3 -fno-tree-vectorize
195 pr33922.s # -O3 -fno-tree-vectorize -fno-tree-pre
-O3 -fno-tree-vectorize -fdump-tree-pre-all dump contains
2081 ^Created.*value lines and all those constants are actually created and
many PHI nodes as well. I believe this might be what nickc was trying to fix
today by adding a limit, but wasn't that limit huge (131072 bits)?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33922