[LLVMdev] Indirect function call

Nai Xia nelson.xia at gmail.com
Wed May 24 05:36:01 PDT 2006

On Tuesday 23 May 2006 23:11, Andrew Lenharth wrote:
> On Tue, 2006-05-23 at 13:32 +0800, Nai Xia wrote:
> > On Monday 22 May 2006 22:22, Andrew Lenharth wrote:
> > > On Mon, 2006-05-22 at 15:33 +0800, 婢跺繋绔村锟� wrote:
> > > > But my code does not always works: if the arguments are not pointer,
> > > > CompleteBUDataStructures not records it. So, if you want to find all indirect
> > > > calls, you maybe have to repair CompleteBUDataStructures. :)
> > > 
> > > Not surprising, CBU is trying to do something entirely different that
> > > what you are.
> > > 
> > > > If you do not use BUDataStructures, you can do it yourself: find all load/store
> > > > instructions with its destination is function type.
> > > 
> > > You may want to look at how the call graph builder works.  It finds all
> > > indirect call sites, and also finds all functions whose address escapes
> > > (this is, may be called indirectly).
> > 
> >   The BasicCallGraph class only lines out the indirect calls(makes the caller point to external node), 
> > but do not resolves them using alias analysis such as DSA. 
> > I think DSA solve this problem for interested call sites by finding the corresponding globals(i.e. the functions) 
> > for the callsite DSnode. Maybe 澶忎竴姘� just wanted to point out that DSA does not take all callsite into count.
> > But just as suggested in callgraph.h, "As an extension in the future, there may be multiple nodes with a null
> > function.  These will be used when we can prove (through pointer analysis) that an indirect call site can 
> > call only a specific set of functions." 
> First, if you want call site information, you need TD not BU.  Second,
> TD still isn't perfect.  I have a series of patches that improve DSA's
> indirect call handling, but they are ugly and not yet ready for
> incorporation into mainline.  If you really want to try them I can send
> you patches, or you can check out my monotone tree.
> I also have some clients of the TD call graph that make use of it (well
> make use of the Global list in the function pointer's DSNode), such as a
> devirtualizer.  Again, I can send you a copy or you can checkout my
> tree.
That would be great! Unfortunately, I did not find your personal cvs in your homepage.
So could you tell me your cvs entry and please point out briefly those codes in interest?
Of course, It's ok to sent the patches to this email.
Thank you very much !

> Andrew


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