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[Bug tree-optimization/68654] [6 Regression] CoreMark Pro performance degradation
- From: "law at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 10 Dec 2015 07:25:52 +0000
- Subject: [Bug tree-optimization/68654] [6 Regression] CoreMark Pro performance degradation
- Auto-submitted: auto-generated
- References: <bug-68654-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68654
--- Comment #10 from Jeffrey A. Law <law at redhat dot com> ---
I've just scanned the provided dumps. This is almost certainly a difference in
the SSA_NAME_VERSIONs causing different coalescing. The tell-tale sign is
seeing identical code in the .optimized dump, except that the SSA_NAME versions
are different, then seeing different code being generated in the .expand dump.
This can be confirmed by providing the same dumps, but with the "details"
modifier. ie, -fdump-tree-optimized-details