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Re: V2 [PATCH] x86: Use _rdtsc intrinsic for HP_TIMING_NOW


On Tue, Oct 2, 2018 at 10:23 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 02/10/2018 13:56, H.J. Lu wrote:
> > On Tue, Oct 2, 2018 at 6:45 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>
> >> On Tue, Oct 2, 2018 at 6:15 AM Adhemerval Zanella
> >> <adhemerval.zanella@linaro.org> wrote:
> >
> >>> I am not very found of cross abi includes like this one, wouldn't be better
> >>> to create a 'sysdeps/x86/hp-timing.h' and for 32-bit use _rdtsc iff
> >>> __i686__ is defined otherwise include generic header?
> >>
> >> I can do that.
> >
> > Here is the V2 patch.  OK for master?
> >
>
> > NB: Checking if __i686__ isn't sufficient since __i686__ may not be
> > defined when building for i686 class processors.
>
> Right, it seems gcc does not define it for -march newer than pentium4.
>
> > diff --git a/sysdeps/i386/i586/init-arch.h b/sysdeps/i386/i586/isa.h
> > similarity index 89%
> > rename from sysdeps/i386/i586/init-arch.h
> > rename to sysdeps/i386/i586/isa.h
> > index 72fb46c61e..a2b5d585d4 100644
> > --- a/sysdeps/i386/i586/init-arch.h
> > +++ b/sysdeps/i386/i586/isa.h
> > @@ -1,4 +1,4 @@
> > -/* Copyright (C) 2015-2018 Free Software Foundation, Inc.
> > +/* Copyright (C) 2018 Free Software Foundation, Inc.
> >     This file is part of the GNU C Library.
> >
> >     The GNU C Library is free software; you can redistribute it and/or
> > @@ -15,5 +15,9 @@
> >     License along with the GNU C Library; if not, see
> >     <http://www.gnu.org/licenses/>.  */
> >
> > +#ifndef _isa_h
> > +#define _isa_h
> > +
>
> Not sure if this is explicit on our coding rules, but usually we
> use uppercase caps for preprocessor guards.  I think it requires
> a one-line description as well (same for other isa.h files).

I will change that.

> > -#ifndef _HP_TIMING_H
> > -#define _HP_TIMING_H 1
> > +#include <isa.h>
> > +
> > +#if MINIMUM_ISA == 686 || MINIMUM_ISA == 8664
> > +# ifndef _HP_TIMING_H
> > +#  define _HP_TIMING_H       1
> > +
>
> The include guard inside the MINIMUM_ISA check seems off, why do
> you need it?

<sysdeps/generic/hp-timing.h> will be skipped if _HP_TIMING_H is
defined.  That is the draw back for the single x86 hp-timing.h.

-- 
H.J.


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