Clang as default compiler November 4th

Steve Kargl sgk at troutmask.apl.washington.edu
Tue Sep 11 13:24:17 UTC 2012


On Tue, Sep 11, 2012 at 02:06:49PM +0200, Roman Divacky wrote:
> > > tl;dr: Clang will become the default compiler for x86 architectures on 2012-11-04
> 
> > Another issue with the switch, which seems to be not only not addressed,
> > but even not talked about, is the performance impact of the change. I
> > do not remember any measurements, whatever silly they could be, of the
> > performance change by the compiler switch. We often have serious and
> > argumented push-back for kernel changes that give as low as 2-3% of
> > the speed hit. What are the numbers for clang change, any numbers ?
> 
> Agreed. We should provide numbers. At least how buildworld times change
> with clang compiled kernel/workd and gcc compiler kernel/world.

How fast clang builds world in comparison to gcc is irrelevant.
What is important is whether software built with clang functions
correctly.  See for example, 

http://math-atlas.sourceforge.net/errata.html#WhatComp

Has anyone run Spec CPU2006 on i386 and amd64 FreeBSD?

-- 
Steve


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