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[Bug rtl-optimization/20376] The missed-optimization of general induction variables in the new rtl-level loop optimizer cause performance degradation.
- From: "rakdver at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 24 Jun 2005 16:39:41 -0000
- Subject: [Bug rtl-optimization/20376] The missed-optimization of general induction variables in the new rtl-level loop optimizer cause performance degradation.
- References: <20050308024912.20376.canqun@nudt.edu.cn>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From rakdver at gcc dot gnu dot org 2005-06-24 16:39 -------
Induction variable splitting works as expected (note that r17 and r19 from each
iteration are computed independently, so they should not block scheduling).
Iv splitting does not rename the variables in different iterations of the
unrolled loop directly. But you will get this if you also use -fweb.
Note however that even with -fweb you won't get the code you would like,
simply because register allocator decides to put all the new registers back
into one (which is ok, since their life ranges do not overlap).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20376