[llvm-dev] GraphTraits dereferencing

[Jared Carlson via llvm-dev]

Thanks Tim,

That’s the direction I was trying to go, but it felt as if I were making things worse so I backed out.  I think I might have been missing the llvm::pointer_iterator and the llvm::pointee_iterator as means to remedy some of this.  I’ll give it a shot and see where I end up, thanks!

Jared



> On May 24, 2017, at 8:17 PM, Tim Shen <timshen at google.com> wrote:
> 
> On Tue, May 23, 2017 at 7:56 PM Jared Carlson via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> Hello,
> 
> I’m trying to port a project up to 4.0 and I’m seeing the following error:
> 
> In file included from /Users/jaredcarlson/Projects/llvm-4.0.0.src/include/llvm/ADT/StringRef.h:13:
> /Users/jaredcarlson/Projects/llvm-4.0.0.src/include/llvm/ADT/STLExtras.h:139:13: error: no type named 'type' in 'std::__1::result_of<std::__1::pointer_to_unary_function<llvm::DSNode *, llvm::DSNode &>
>       (llvm::DSNode &)>'
>           ::type value_type;
>           ~~^~~~
> /Users/jaredcarlson/Projects/crab-llvm/dsa-seahorn/include/dsa/DSGraphTraits.h:122:25: note: in instantiation of template class
>       'llvm::mapped_iterator<llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::DSNode, true, false, void>, false, false>, std::__1::pointer_to_unary_function<llvm::DSNode *, llvm::DSNode &> >'
>       requested here
>   static nodes_iterator nodes_begin(DSGraph *G) {
> 
> So, it looks to me like in DSGraph, the iterator needs to be dereferenced correctly.  Right now the source reads:
> 
>  template <> struct GraphTraits<DSGraph*> {
>   typedef DSNode NodeType;
>   typedef DSNode::iterator ChildIteratorType;
> 
>   // not sure this is necessary anymore as NodeRef must be a pointer
>   typedef std::pointer_to_unary_function<DSNode *, DSNode&> DerefFun;
> 
>   // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
>   typedef mapped_iterator<DSGraph::node_iterator, DerefFun> nodes_iterator;
> 
>   static nodes_iterator nodes_begin(DSGraph *G) {
>     return map_iterator( G->node_begin(), DerefFun(dereference) );
>   }
>   static nodes_iterator nodes_end(DSGraph *G) {
>     return map_iterator( G->node_end(), DerefFun(dereference) );
>   }
> 
>   static ChildIteratorType child_begin(NodeType *N) { return N->begin(); }
>   static ChildIteratorType child_end(NodeType *N) { return N->end(); }
> };
> 
> I”m just unsure as in 4.0, there’s a need for a NodeRef to leverage the GraphTraits template which needs to be.a pointer but I don’t think that’s all that relevant here and the above code looks consistent with what I’m used to…
> 
> Please refer to include/llvm/ADT/GraphTraits.h for the documentation.
> 
> In your case, for nodes, simply change `typedef DSNode NodeType;` to `typedef DSNode* NodeRef;`
> 
> I'm not sure what DSGraph::iterator returns on dereference; but ultimately you want both ChildIteratorType and nodes_iterator to dereference to a NodeRef, as documented. You may find llvm::pointer_iterator or llvm::pointee_iterator helpful.
> 
> I'd try to remove DerefFun and the usage of mapped_iterator.
>  
> 
> DSGraph::iterator by the way is ilist<DSNode>::iterator, as the graph allows walking the nodes….
> 
> Any hints, would be much appreciated…. Thanks!
> 
> 
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