I recommend folks to take advantage of the Open64 Tutorial/Workshop to
engage face to face discussion. I hope we could resolve several outstanding
reviews on the spot.
Shin
On Mon, Jun 6, 2011 at 10:27 PM, Sun Chan <sun.c...@gmail.com> wrote:
> And Sxy has a point, and I now remember this is why we did CAND/CIOR
> etc. I would say, this is a case where your change is not always a
> win. Any suggestion/pointer?
> Sun
>
> On Mon, Jun 6, 2011 at 12:10 PM, Chandrasekhar Murthy <mur...@sgi.com>
> wrote:
> > Would replacing CAND/CIOR by LAND/LIOR work for the cases you are looking
> > at.
> >
> >
> >
> > Murthy
> >
> >
> >
> > ________________________________
> >
> > From: shuxin yang [mailto:shuxin.ope...@gmail.com]
> > Sent: Monday, June 06, 2011 10:32 AM
> > To: Chandrasekhar Murthy
> > Cc: Sun Chan; open64-devel
> >
> > Subject: Re: [Open64-devel] patch to enable more if-conversion
> >
> >
> >
> > Hi:
> > (Just a general question about conditional and/or, not specific to
> > open64.)
> >
> > More often than not, I find it is more convenient to directly deal
> with
> > cand/cor at the level higher than CG. I don't remember all these
> situations
> > I ran into. Here is some examples:
> >
> > e.g.1: merge the if-then-else constructs
> > if (c1||c1) s1 then s2;
> > ..
> > if (c1||c2) s3 then s4;
> >
> > e.g.2 PRE complicate cand/cor
> > if (cand-cor) {..}
> >
> >
> > .. some stmts here
> >
> > if (cand-cor) {}
> >
> > e.g3 reorder the sub-expr in the cand/cor, suppose it is safe to to
> that
> > c1 || c2 || c3 => c3 || c2 || c1
> >
> > I believe sometimes lowered cand-cor could be more convenient. However,
> > dealing with CFG is far more difficult than expression. If I were
> compiler
> > designer, I would keep cand/cor all the way down to the point right
> before
> > CG. What is your take?
> >
> > Thanks
> > Shuxin
> >
> > On Mon, Jun 6, 2011 at 8:42 AM, Chandrasekhar Murthy <mur...@sgi.com>
> wrote:
> >
> > As some of the files in lno (access_vector.cxx, array_bounds.cxx, etc..)
> are
> > processing these nodes, I think the lowering is done after LNO.
> >
> > Murthy
> >
> > -----Original Message-----
> > From: Sun Chan [mailto:sun.c...@gmail.com]
> >
> > Sent: Monday, June 06, 2011 8:20 AM
> > To: Chandrasekhar Murthy
> > Cc: David Coakley; open64-devel
> > Subject: Re: [Open64-devel] patch to enable more if-conversion
> >
> > Thx Murthy, does this mean we should keep these nodes till after LNO?
> > David,
> > Is your if-conv fix at mainopt? Or is it at preopt? From this
> > discussion so far, this should be done in mainopt, i.e. the lowering
> > into your new form ought to be done at mainopt, after LNO.
> > Sun
> >
> > On Mon, Jun 6, 2011 at 7:24 AM, Chandrasekhar Murthy <mur...@sgi.com>
> wrote:
> >> && and || were initially handled in the frontend.
> >> CAND/CIOR were added later in order to move the lowering to VHO.
> >> The lowering was deferred to later so that LNO could also process these
> >> nodes.
> >>
> >> Murthy
> >>
> >> -----Original Message-----
> >> From: Sun Chan [mailto:sun.c...@gmail.com]
> >> Sent: Saturday, June 04, 2011 9:54 PM
> >> To: David Coakley
> >> Cc: open64-devel
> >> Subject: Re: [Open64-devel] patch to enable more if-conversion
> >>
> >> I forgot why we did cand anymore. OTOH, I do remember lowering that
> >> with profile feedback info is tricky to get that right. Can you double
> >> check that you are not breaking profile info and consistency check
> >> with your changes?
> >> Sun
> >>
> >> On Fri, Jun 3, 2011 at 1:53 PM, David Coakley <dcoak...@gmail.com>
> wrote:
> >>> Could a gatekeeper please review the attached change that enables more
> >>> if-conversion?
> >>>
> >>> Here is the proposed log message:
> >>>
> >>> Convert:
> >>> if (a && b)
> >>> x = ...
> >>> To:
> >>> if (a)
> >>> if (b)
> >>> x = ...
> >>> To enable more if-conversion.
> >>>
> >>> Without this transformation, WHIRL-lowering creates control flow
> >>> that WOPT-if-conversion can't handle. With this transformation,
> >>> this now looks like any other if-conversion opportunity to WOPT.
> >>> So this transformation enables more if-conversion (i.e. replace
> >>> branch with conditional move). No if-conversion code was touched -
> >>> only lowering code.
> >>>
> >>>
> >>>
> >>>
> >>> I have also attached a small test program that demonstrates when the
> >>> transformation occurs. Thanks,
> >>>
> >>> -David Coakley / AMD Open Source Compiler Engineering
> >>>
> >>>
> >>>
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