|RE: Eigen 3.3 vs 3.2 Performance (was RE: [eigen] 3.3-beta2 released!)|
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On Tue, 21 Aug 2018, Daniel.Vollmer@xxxxxx wrote:
I'm not quite sure how to report the gcc-8 problem to the
gcc-maintainers. I've tried running creduce over the code, but the
output (attached) seems slightly different (e.g. the copy in operator+=,
which looks like the aliasing assignment was chosen).
I've reported https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87008
(the source may be large and unreduced, but internally after the first few
rounds of optimization it is rather clear what is going on so it should be
good enough for gcc devs)
There were other regressions in gcc-8 related to the same optimization
pass (SRA) : 85459, 85762, etc. IIRC the author said he was trying to
rewrite that pass for gcc-9, but I could be wrong.
It might not be the only issue with gcc-8 though.