Re: Scheduling fix (fixes gcc.c-torture/execute/980506-1.c on ppc)

[Jeffrey A Law <law at cygnus dot com>]

  In message <199808260521.PAA14575@geoffk.wattle.id.au>you write:
  > > Date: Tue, 25 Aug 1998 16:52:57 +0200
  > > From: Franz Sirl <Franz.Sirl-kernel@lauterbach.com>
  > 
  > > is this patch needed in addition to this one:
  > > 
  > > Tue Aug 18 10:32:11 1998  Jeffrey A Law  (law@cygnus.com)
  > > 
  > >         * haifa-sched.c (sched_analyze): Put all JUMP_INSNs on the last
  > >         pending memory flush list.
  > > 
  > > This patch alone fixed 980506-1.c for me and others. Doesn't it fix all
  > > possible cases?
  > 
  > That patch is a "optimisation doesn't work, let's turn it off" class
  > of patch, which I hope is only for the 1.1 release.  My patch fixes
  > the underlying problem.
No it is not such a patch.  The scheduler is not supposed to be moving
memory references like that.

  > Notice that since loops usually end with JUMP_INSNs, the patch
  > effectively disables all interblock scheduling; and I always thought
  > the whole point of the Haifa scheduler was that it could do
  > speculative loads around loops.
No, it disables interblock scheduling of memory references, which it
should not have been doing to start with.

jeff