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Re: Enabling -frename-registers?
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: David Edelsohn <dje dot gcc at gmail dot com>
- Cc: gcc-patches at gcc dot gnu dot org, Richard Biener <richard dot guenther at gmail dot com>, Bernd Schmidt <bschmidt at redhat dot com>, Jeffrey Law <law at redhat dot com>, Segher Boessenkool <segher at kernel dot crashing dot org>
- Date: Wed, 04 May 2016 12:03:23 +0200
- Subject: Re: Enabling -frename-registers?
- Authentication-results: sourceware.org; auth=none
- References: <CAGWvnykBEjYMgOCaR_ZGLwB3fxPg-pB3WPSwAvmUBXzmXct8gg at mail dot gmail dot com> <443D7834-6E23-4046-8DD7-F1D8F2593F2B at gmail dot com> <CAGWvny=KPTheWKc-CbKrWGsGfBXB9vWz57RfVRUY_NTOBPUKZg at mail dot gmail dot com>
> The IBM LTC team has tested the benefit of -frename-registers at -O2
> and sees no net benefit for PowerPC -- some benchmarks improve
> slightly but others degrade slightly (a few percent). You mentioned
> no overall benefit for x86. Although you mentioned benefit for
> Itanium, it is not a primary nor secondary architecture target for GCC
> and continues to have limited adoption. Andreas also reported a
> bootstrap comparison failure for Itanium due to the change.
...which had nothing to do with -frename-registers but was a latent issue in
the speculation support of the scheduler, see the audit trail.
--
Eric Botcazou