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[Bug tree-optimization/35639] [4.3/4.4 Regression] -fprofile-generate + PRE = big compile-time
- From: "bonzini at gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 22 Nov 2008 16:00:40 -0000
- Subject: [Bug tree-optimization/35639] [4.3/4.4 Regression] -fprofile-generate + PRE = big compile-time
- References: <bug-35639-7849@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #8 from bonzini at gnu dot org 2008-11-22 16:00 -------
The problem was that without -fprofile-generate the time spent there was
basically zero. Since the profiling code is building a MST of the control-flow
graph, it should produce absolutely no PRE opportunity and it's a pity that it
causes such a slowdown.
I wonder if there is some low-hanging fruit to eliminate value numbers that
cannot be redundant.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35639