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Re: [tree-ssa] Removing redundant loads
- From: Andrew MacLeod <amacleod at redhat dot com>
- To: Jeff Law <law at redhat dot com>
- Cc: Jason Merrill <jason at redhat dot com>,Diego Novillo <dnovillo at redhat dot com>,gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: 03 Jun 2003 12:28:11 -0400
- Subject: Re: [tree-ssa] Removing redundant loads
- References: <200306010205.h5125Q8G024851@speedy.slc.redhat.com>
On Sat, 2003-05-31 at 22:05, law@redhat.com wrote:
> In message <wvlbrxk0vve.fsf@prospero.boston.redhat.com>, Jason Merrill writes:
> >On Fri, 30 May 2003 18:34:45 -0600, law@redhat.com wrote:
> >
> >> In message <wvln0h40yjy.fsf@prospero.boston.redhat.com>, Jason Merrill writ
> >es:
> >> >> For example, if you pass it this tree for both operands, you'll get a
> >> >> false back from operand_b because this expression has tree_side_effects
> >> >> set.
> >> >
> >> >Why does that expression have TREE_SIDE_EFFECTS set?
> >
> >> Because we unconditionally set TREE_SIDE_EFFECTS on STMT_EXPRs. That
> >> gets propagated up to the COMPONENT_REFs.
> >
> >The gimplifier should have cleared that flag while processing the
> >COMPONENT_REF. I'll check it out.
> Thanks. FWIW, I'm offline all next week, so I won't be able to poke
> at anything you may come up with until June 10/11.
>
So, this removing redundant loads patch is what is causing the bootstrap
failure with overlapping live ranges, so it would appear that there is
more to this than meets the eye...
And of course Jeff isn't around all this week :-)
I will look at it for a bit... but If I dont get anywhere with it
perhaps we ought to revert it until we can look at it closer...
Andrew