Subject: Re: [cryptodev:master 130/134] aes_generic.c:undefined reference to `_restgpr_31_x'

From: Segher Boessenkool <[email-masked]>
Date: Fri, 12 Jan 2018 16:10:50 -0600

On Fri, Jan 12, 2018 at 10:45:31PM +0100, Arnd Bergmann wrote:
> > I guess you could enable the _x routines whenever you use ubsan?  Ubsan
> > will cause much bigger code growth than the handful of insns in those
> > routines?
> 
> Right, that could work, too. My patch that Herbert merged intentionally
> used -Os also for non-UBSAN builds because it turned out to
> be much faster (see gcc PR83651),

"Much"?

-Os is *slower* with 8.0, 5% faster with 7.2, 4% faster with 7.1,
slower with 7.0 and 6.3.  Your numbers, #c1.

Anf this is the generic code of course, which is slow anyway (not to
mention insecure).

> but we could revert that back
> to the default and only use the -Os for UBSAN, essentially
> addressing only PR83356 but not PR83651.

Segher