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SPECfp95: Huge performance loss with -fnew-ra?
- From: Diego Novillo <dnovillo at redhat dot com>
- To: gcc at gcc dot gnu dot org
- Date: Mon, 22 Jul 2002 21:03:25 -0400
- Subject: SPECfp95: Huge performance loss with -fnew-ra?
- Organization: Red Hat Canada
I started using "-O2 -fnew-ra" for SPEC95 peak runs. The flag
seems to have had a negligible effect on SPECint, but on SPECfp
we have lost 4 SPEC marks (about 25% performance loss).
http://people.redhat.com/dnovillo/SPEC/gcc/global-run-ratio.html
I am not sure at the moment if it's the new register allocator by
itself or some combination of -fnew-ra and some other change.
The first run with the new allocator was on 2002-07-17.
Diego.