Re: [PATCH] x86/vdso: include generic __lshrdi3 in 32-bit vDSO

[Peter Zijlstra]

On Mon, Mar 18, 2019 at 10:09:37AM -0700, Nick Desaulniers wrote:
> On Fri, Mar 15, 2019 at 3:29 PM Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote:
> > On Fri, Mar 15, 2019 at 02:31:09PM -0700, 'Nick Desaulniers' via Clang Built Linux wrote:
> > > Is there a config I can set to reproduce this, in order to help
> > > test?
> >
> > I encountered it with a Chrome OS specific configuration, but a
> > defconfig should do.
> 
> defconfig selects CONFIG_OPTIMIZE_FOR_PERFORMANCE=y.  I needed to
> select CONFIG_CC_OPTIMIZE_FOR_SIZE=y to repro.  My CI is simply
> running defconfigs, which is why I didn't catch this.

I suspect the right fix is to make clang use -Os and abolish that -Oz
madness.