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Vikram Adve

2002-Nov-25 12:36 UTC

[LLVMdev] globals in DS graph

Ganesh,

I modified DataStructure.cpp so that global nodes are no longer
removed from any graphs.  Only that file has changed.

Chris, if you get a chance to do this, it would be nice if you could
take a quick look at the change I made and make sure that's all that's
needed. 

Thanks,

--Vikram
http://www.cs.uiuc.edu/~vadve

> From: Chris Lattner <sabre at nondot.org>
> Subject: Re: [LLVMdev] globals in DS graph
> Sender: llvmdev-admin at cs.uiuc.edu
> Date: Mon, 25 Nov 2002 01:34:14 -0600 (CST)
> 
> > Specifically, I wrote the following simple program:
> > List *g;
> > void alloc_func(){
> >   g = ( List* ) malloc( sizeof( List ) );
> > }
> > void free_func(){
> >   free( g );
> > }
> 
> I don't have an LLVM tree available to me right now (as
> tank/llvm.cs.uiuc.edu) is down, so take this with a grain of salt...
> 
> > I noticed that the DSnode for g in alloc_func is different from that
of
> > free_func and NEITHER of them had GlobalNode bit set in their types.
Only
> > the malloc bit and the incomplete bit have been set. I am completely
> > clueless how to figure out if it is a global node or not. I used
> > getGlobals and found that the returned map had size 0.
> 
> There may be a few different things going on here.  First of all, the
> "globals" graph is only partially implemented currently.  Right
now, nodes
> eligable to be moved to the globals graph are properly removed from the
> individual function graphs, but they are never reinserted into the globals
> graph.  This can cause some funny disappearances that don't make a lot
of
> sense, and...
> 
> > How can I get the "common" global node of g?
> 
> ... the common node in this case never gets unified.  This is one of the
> top priorities for me when I get back to Illinois (after thanksgiving
> break), but it is unlikely to make much progress in the mean time.  If you
> would like to disable this behavior, look in the DSGraph::removeDeadNodes
> (or similar) in DataStructure.cpp.  In it you will see the code that marks
> nodes as being "alive" in the current graph.  All you have to do
is add
> code to mark all globals as alive, and they will be propogated up to main.
> Alternatively, take a look at the CVS revisions a few checkins back to see
> when the globals graph stuff was added... and revert it.
> 
> I hope this helps some :)
> 
> -Chris
> 
> -- 
> http://llvm.cs.uiuc.edu/
> http://www.nondot.org/~sabre/Projects/
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Chris Lattner

2002-Nov-25 12:51 UTC

head link

[LLVMdev] globals in DS graph

On Mon, 25 Nov 2002, Vikram Adve wrote:> I modified DataStructure.cpp so that global nodes are no longer
> removed from any graphs.  Only that file has changed.
>
> Chris, if you get a chance to do this, it would be nice if you could
> take a quick look at the change I made and make sure that's all
that's
> needed.
That looks right to me, thanks!

-Chris
> > From: Chris Lattner <sabre at nondot.org>
> > Subject: Re: [LLVMdev] globals in DS graph
> > Sender: llvmdev-admin at cs.uiuc.edu
> > Date: Mon, 25 Nov 2002 01:34:14 -0600 (CST)
> >
> > > Specifically, I wrote the following simple program:
> > > List *g;
> > > void alloc_func(){
> > >   g = ( List* ) malloc( sizeof( List ) );
> > > }
> > > void free_func(){
> > >   free( g );
> > > }
> >
> > I don't have an LLVM tree available to me right now (as
> > tank/llvm.cs.uiuc.edu) is down, so take this with a grain of salt...
> >
> > > I noticed that the DSnode for g in alloc_func is different from
that of
> > > free_func and NEITHER of them had GlobalNode bit set in their
types. Only
> > > the malloc bit and the incomplete bit have been set. I am
completely
> > > clueless how to figure out if it is a global node or not. I used
> > > getGlobals and found that the returned map had size 0.
> >
> > There may be a few different things going on here.  First of all, the
> > "globals" graph is only partially implemented currently. 
Right now, nodes
> > eligable to be moved to the globals graph are properly removed from
the
> > individual function graphs, but they are never reinserted into the
globals
> > graph.  This can cause some funny disappearances that don't make a
lot of
> > sense, and...
> >
> > > How can I get the "common" global node of g?
> >
> > ... the common node in this case never gets unified.  This is one of
the
> > top priorities for me when I get back to Illinois (after thanksgiving
> > break), but it is unlikely to make much progress in the mean time.  If
you
> > would like to disable this behavior, look in the
DSGraph::removeDeadNodes
> > (or similar) in DataStructure.cpp.  In it you will see the code that
marks
> > nodes as being "alive" in the current graph.  All you have
to do is add
> > code to mark all globals as alive, and they will be propogated up to
main.
> > Alternatively, take a look at the CVS revisions a few checkins back to
see
> > when the globals graph stuff was added... and revert it.
> >
> > I hope this helps some :)
> >
> > -Chris
> >
> > --
> > http://llvm.cs.uiuc.edu/
> > http://www.nondot.org/~sabre/Projects/
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
>
>
-Chris

-- 
http://llvm.cs.uiuc.edu/
http://www.nondot.org/~sabre/Projects/

Ganesh Bikshandi

2002-Nov-25 17:47 UTC

head link

[LLVMdev] globals in DS graph

Prof. Vikram,

I updated the DataStructure.cpp and recompiled the llvm. But still I have
the same scenario. I don't get the same DSnode for global. I tried several
methods; but none of them were successful. I used the getNodeForValue and
again I found that the global value had different nodes in different
functions. However, the getGlobals worked well for function call.

Thanks,
Ganesh
On Mon, 25 Nov 2002, Vikram Adve wrote:
> Ganesh,
>
> I modified DataStructure.cpp so that global nodes are no longer
> removed from any graphs.  Only that file has changed.
>
> Chris, if you get a chance to do this, it would be nice if you could
> take a quick look at the change I made and make sure that's all
that's
> needed.
>
> Thanks,
>
> --Vikram
> http://www.cs.uiuc.edu/~vadve
>
>
> > From: Chris Lattner <sabre at nondot.org>
> > Subject: Re: [LLVMdev] globals in DS graph
> > Sender: llvmdev-admin at cs.uiuc.edu
> > Date: Mon, 25 Nov 2002 01:34:14 -0600 (CST)
> >
> > > Specifically, I wrote the following simple program:
> > > List *g;
> > > void alloc_func(){
> > >   g = ( List* ) malloc( sizeof( List ) );
> > > }
> > > void free_func(){
> > >   free( g );
> > > }
> >
> > I don't have an LLVM tree available to me right now (as
> > tank/llvm.cs.uiuc.edu) is down, so take this with a grain of salt...
> >
> > > I noticed that the DSnode for g in alloc_func is different from
that of
> > > free_func and NEITHER of them had GlobalNode bit set in their
types. Only
> > > the malloc bit and the incomplete bit have been set. I am
completely
> > > clueless how to figure out if it is a global node or not. I used
> > > getGlobals and found that the returned map had size 0.
> >
> > There may be a few different things going on here.  First of all, the
> > "globals" graph is only partially implemented currently. 
Right now, nodes
> > eligable to be moved to the globals graph are properly removed from
the
> > individual function graphs, but they are never reinserted into the
globals
> > graph.  This can cause some funny disappearances that don't make a
lot of
> > sense, and...
> >
> > > How can I get the "common" global node of g?
> >
> > ... the common node in this case never gets unified.  This is one of
the
> > top priorities for me when I get back to Illinois (after thanksgiving
> > break), but it is unlikely to make much progress in the mean time.  If
you
> > would like to disable this behavior, look in the
DSGraph::removeDeadNodes
> > (or similar) in DataStructure.cpp.  In it you will see the code that
marks
> > nodes as being "alive" in the current graph.  All you have
to do is add
> > code to mark all globals as alive, and they will be propogated up to
main.
> > Alternatively, take a look at the CVS revisions a few checkins back to
see
> > when the globals graph stuff was added... and revert it.
> >
> > I hope this helps some :)
> >
> > -Chris
> >
> > --
> > http://llvm.cs.uiuc.edu/
> > http://www.nondot.org/~sabre/Projects/
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
>
Graduate Research Assistant
Computer Science
University of Illinois, Champaign-Urbana

Vikram Adve

2002-Nov-26 07:31 UTC

head link

[LLVMdev] globals in DS graph

Ganesh,

Every graph has a separate copy of the node for a global.
There is no sharing of nodes between graphs.  For any particular
global object (a GlobalValue*), you can find the node for that
global in each graph from the ScalarMap for that graph.

Eventually, irrelevant^(*) globals within each function's graph will
be deleted but other globals will stay the same as they are now.
When that happens, we will need to fully implement the globals
graph for our graph construction algorithm, but even then many
clients (including yours) may never really need to know about
the globals graph.

(*) A global is irrelevant in a function if it is not reachable from
    and cannot reach any node that is accessible within that function.
    Such a global cannot be used to reference or modify any accessible
    node within that function.

--Vikram
http://www.cs.uiuc.edu/~vadve

> From: Ganesh Bikshandi <bikshand at students.uiuc.edu>
> Date: Mon, 25 Nov 2002 17:46:33 -0600 (CST)
> Subject: Re: [LLVMdev] globals in DS graph
> 
> Prof. Vikram,
> 
> I updated the DataStructure.cpp and recompiled the llvm. But still I have
> the same scenario. I don't get the same DSnode for global. I tried
several
> methods; but none of them were successful. I used the getNodeForValue and
> again I found that the global value had different nodes in different
> functions. However, the getGlobals worked well for function call.
> 
> Thanks,
> Ganesh
> On Mon, 25 Nov 2002, Vikram Adve wrote:
> 
> > Ganesh,
> >
> > I modified DataStructure.cpp so that global nodes are no longer
> > removed from any graphs.  Only that file has changed.
> >
> > Chris, if you get a chance to do this, it would be nice if you could
> > take a quick look at the change I made and make sure that's all
that's
> > needed.
> >
> > Thanks,
> >
> > --Vikram
> > http://www.cs.uiuc.edu/~vadve

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