Re: [PATCH] PR61868

[Richard Biener <richard dot guenther at gmail dot com>]

On Wed, Jul 30, 2014 at 2:48 PM, Bingfeng Mei <bmei@broadcom.com> wrote:
> On the second thought, maybe the change should be made in set_random_seed. Otherwise, init_random_seed is invoked every time get_random_seed get called (not sure how often). What do you think?
>
> const char *
> set_random_seed (const char *val)
> {
>   const char *old = flag_random_seed;
>   flag_random_seed = val;
> + init_random_seed ();
>   return old;
> }

I think it makes more sense to move the if (flag_random_seed)
code from init_random_seed inline here as init_random_seed is
never called with flag_random_set == true.

Richard.

> Bingfeng
>
>> -----Original Message-----
>> From: Richard Biener [mailto:richard.guenther@gmail.com]
>> Sent: 30 July 2014 10:43
>> To: Bingfeng Mei
>> Cc: Andi Kleen; gcc-patches@gcc.gnu.org
>> Subject: Re: [PATCH] PR61868
>>
>> On Wed, Jul 30, 2014 at 10:52 AM, Bingfeng Mei <bmei@broadcom.com> wrote:
>> > Yes, opts-global.c fills flag_random_seed with string passed in
>> command line. But init_random_seed in toplev.c is the one that processes
>> the flag and set random_seed variable, which is returned by
>> get_random_seed function.
>>
>> Err, I meant opts-global.c:handle_common_deferred_options
>>
>> > By default, my configuration enables LTO. How to test LTO bootstrap?
>>
>> configure with --with-build-config=bootstrap-lto (and reduce the
>> set of languages to c,c++ to get a sane bootstrap time).
>>
>> Richard.
>>
>> > Bingfeng
>> >
>> >> -----Original Message-----
>> >> From: Richard Biener [mailto:richard.guenther@gmail.com]
>> >> Sent: 30 July 2014 08:47
>> >> To: Bingfeng Mei; Andi Kleen
>> >> Cc: gcc-patches@gcc.gnu.org
>> >> Subject: Re: [PATCH] PR61868
>> >>
>> >> On Tue, Jul 29, 2014 at 3:01 PM, Bingfeng Mei <bmei@broadcom.com>
>> wrote:
>> >> > Hi,
>> >> > Please find the patches for pr61868. The problem is that even with
>> -
>> >> frandom-seed gcc always uses 0 instead of specified number/string for
>> >> places such as lto section names. init_random_seed is never called
>> with
>> >> -frandom-seed. Bootstrapped and tested on x86-64. OK for trunk?
>> >>
>> >> Hmm, but -frandom-seed= is honored by opts.c calling set_random_seed?
>> >>
>> >> Andi, wasn't this used to support partial linking of LTO objects?
>> Thus,
>> >> this shortcut was on purpose?  Otherwise passing -frandom-seed to
>> >> LTO would break that?
>> >>
>> >> Bingfeng, did you test if LTO bootstrap still works after this patch?
>> >>
>> >> Thanks,
>> >> Richard.
>> >>
>> >> > Thanks,
>> >> > Bingfeng Mei
>> >> >
>> >> >
>> >> > ===================================================================
>> >> > --- ChangeLog   (revision 213152)
>> >> > +++ ChangeLog   (working copy)
>> >> > @@ -1,3 +1,9 @@
>> >> > +2014-07-29  Bingfeng Mei <bmei@broadcom.com>
>> >> > +
>> >> > +       PR lto/61868
>> >> > +       * toplev.c (init_random_seed): Generate random seed when
>> >> > +       flag_random_seed is specified.
>> >> > +
>> >> >  2014-07-28  Jan Hubicka  <hubicka@ucw.cz>
>> >> >
>> >> >         * cgraph.c (cgraph_node::create_indirect_edge): Copy
>> >> speculative data.
>> >> > Index: toplev.c
>> >> > ===================================================================
>> >> > --- toplev.c    (revision 213152)
>> >> > +++ toplev.c    (working copy)
>> >> > @@ -301,7 +301,7 @@ init_random_seed (void)
>> >> >  HOST_WIDE_INT
>> >> >  get_random_seed (bool noinit)
>> >> >  {
>> >> > -  if (!flag_random_seed && !noinit)
>> >> > +  if (!noinit)
>> >> >      init_random_seed ();
>> >> >    return random_seed;
>> >> >  }
>> >> > Index: testsuite/ChangeLog
>> >> > ===================================================================
>> >> > --- testsuite/ChangeLog (revision 213152)
>> >> > +++ testsuite/ChangeLog (working copy)
>> >> > @@ -1,3 +1,8 @@
>> >> > +2014-07-29  Bingfeng Mei  <bmei@broadcom.com>
>> >> > +
>> >> > +       PR lto/61868
>> >> > +       * gcc.dg/pr61868.c: New test.
>> >> > +
>> >> >  2014-07-28  Richard Biener  <rguenther@suse.de>
>> >> >
>> >> >         PR rtl-optimization/61801
>> >> > Index: testsuite/gcc.dg/pr61868.c
>> >> > ===================================================================
>> >> > --- testsuite/gcc.dg/pr61868.c  (revision 0)
>> >> > +++ testsuite/gcc.dg/pr61868.c  (revision 0)
>> >> > @@ -0,0 +1,9 @@
>> >> > +/* { dg-do compile } */
>> >> > +/* { dg-options "-flto -frandom-seed=0x12345" }  */
>> >> > +extern int foo (int);
>> >> > +int main ()
>> >> > +{
>> >> > +  foo (100);
>> >> > +  return 0;
>> >> > +}
>> >> > +/* { dg-final { scan-assembler "\.gnu\.lto.*.12345" } } */
>> >> >