From: Andrew MacLeod <amacleod@redhat.com>
To: Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz>
Cc: Jeff Law <law@redhat.com>, Diego Novillo <dnovillo@redhat.com>,
gcc mailing list <gcc@gcc.gnu.org>
Subject: Re: [tree-ssa] Lazy updating of stmt operands
Date: Wed, 17 Dec 2003 00:21:00 -0000 [thread overview]
Message-ID: <1071614936.13039.201.camel@p4> (raw)
In-Reply-To: <20031216222051.GA6302@atrey.karlin.mff.cuni.cz>
On Tue, 2003-12-16 at 17:20, Zdenek Dvorak wrote:
> Hello,
>
> > > > defining stmt's annotation, so given any SSA variable, you can get to
> > > > the immediate uses by looking at the annotation for SSA_NAME_DEF_STMT.
> > > > It needs a marginal extention to deal with the fact that there can be
> > > > multiple defs/vdefs on one stmt, but we need to do that to handle
> > > > virtual defs anyway. I would prefer to keep this information right with
> > > > the stmt rather than in a table on the side.
> > >
> > > Immediate use is not a property of the statement, but the property of
> > > the ssa name; so it should be in the SSA_NAME, as my patch does,
> > > not in the statement annotations.
> >
> > After pondering it, I have concluded you are correct, the immediate uses
> > info should be attached to the SSA_NAME. The pragmatic reason is that
> > it eliminates the need to have the def stmt of the SSA_NAME in place
> > before the uses are seen...
> >
> > ie, keeping the information accurate when you are adding a new ssa_name
> > would *require* you to create the DEF first, or you have no place to put
> > the uses information. Although its probably good practice to issue the
> > DEF first, enforcing that is pretty lame. Putting it in the SSA_NAME
> > resolves ths problem since the SSA_NAME must exist in order to actually
> > occur in the stmt :-).
>
> my reason for having the information stored in the SSA_NAME actually
> was that there may be multiple definitions in a single statement,
> thus making it necessary to somehow determine of which of them is used
> in the statement recorded as the immediate use; this would be extremely
> cumbersome.
>
I would have just associated it with the new operand infrastructure..
ie, you ask for the immediate uses info for a def index or vdef index,
since we have that index info available easily. It was maintaining it
that was the clincher for me.
Andrew
next prev parent reply other threads:[~2003-12-16 22:49 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-12-07 16:22 Zdenek Dvorak
2003-12-07 17:14 ` Diego Novillo
2003-12-07 17:28 ` Zdenek Dvorak
2003-12-07 17:36 ` Diego Novillo
2003-12-07 18:09 ` Zdenek Dvorak
2003-12-11 19:39 ` law
2003-12-07 22:20 ` Steven Bosscher
2003-12-09 14:30 ` Andrew MacLeod
2003-12-09 20:40 ` Zdenek Dvorak
2003-12-11 19:41 ` law
2003-12-11 19:38 ` law
2003-12-11 19:52 ` Zdenek Dvorak
2003-12-11 22:36 ` Zdenek Dvorak
2003-12-11 23:34 ` Andrew MacLeod
2003-12-15 19:10 ` Andrew MacLeod
2003-12-15 19:19 ` Zdenek Dvorak
2003-12-15 20:55 ` Andrew MacLeod
2003-12-15 21:06 ` Zdenek Dvorak
2003-12-15 21:39 ` Andrew MacLeod
2003-12-15 21:49 ` Zdenek Dvorak
2003-12-15 22:04 ` Andrew MacLeod
2003-12-15 22:39 ` law
2003-12-17 4:56 ` law
2003-12-16 23:32 ` Andrew MacLeod
2003-12-17 0:09 ` Zdenek Dvorak
2003-12-17 0:21 ` Andrew MacLeod [this message]
2003-12-17 3:28 ` law
2003-12-15 19:28 ` Diego Novillo
2003-12-11 22:31 Chris Lattner
2003-12-12 3:14 ` law
2003-12-12 3:58 ` Chris Lattner
2003-12-12 19:25 ` Andrew MacLeod
2003-12-12 19:42 ` Zdenek Dvorak
2003-12-12 19:45 ` Andrew MacLeod
2003-12-12 19:54 ` Chris Lattner
2003-12-12 19:55 ` Andrew MacLeod
2003-12-12 21:26 ` Diego Novillo
2003-12-12 19:57 ` Chris Lattner
2003-12-13 16:02 ` Andrew MacLeod
2003-12-14 3:39 ` Chris Lattner
2003-12-15 23:41 ` law
2003-12-16 6:02 ` Andrew MacLeod
2003-12-15 20:47 Chris Lattner
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