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Re: Enabling -frename-registers?
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Bernd Schmidt <bschmidt at redhat dot com>
- Cc: Eric Botcazou <ebotcazou at adacore dot com>, David Edelsohn <dje dot gcc at gmail dot com>, gcc-patches at gcc dot gnu dot org, Richard Biener <richard dot guenther at gmail dot com>, Jeffrey Law <law at redhat dot com>
- Date: Wed, 4 May 2016 12:50:42 -0500
- 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> <2317874 dot CXT2IFrHHt at polaris> <5729CAB8 dot 8040805 at redhat dot com>
On Wed, May 04, 2016 at 12:11:04PM +0200, Bernd Schmidt wrote:
> Given how many latent bugs it has shown up I think that alone would make
> it valuable to have enabled at -O2.
It is finding so many latent bugs simply because it is changing register
allocation so much, and very aggressively. That does not mean enabling
it by default is a good thing, quite the opposite, if there is no
performance (or code size, etc.) advantage to doing so.
Segher