[LLVMdev] Dominator Trees (original) (raw)

Speziale Ettore speziale.ettore at gmail.com
Fri Oct 31 17:42:45 PDT 2014

Hello everyone,

I would like to implement a query to check if a node in the CallGraph dominates another CallGraph node. I thus started specializing DomTreeNodeBase and DominatorTreeBase such as I can have CallGraphDomTreeNode and CallGraphDominatorTree.

After allocating the tree, I call DomTreeNode::recalculate(CallGraph &). However, I cannot instantiate the template as it does seem the part of that function dealing with initializing the post-dominator roots:

00692 // Initialize the roots list 00693 for (typename TraitsTy::nodes_iterator I = TraitsTy::nodes_begin(&F), 00694 E = TraitsTy::nodes_end(&F); I != E; ++I) { 00695 if (TraitsTy::child_begin(I) == TraitsTy::child_end(I)) 00696 addRoot(I); 00697 00698 // Prepopulate maps so that we don't get iterator invalidation issues later. 00699 this->IDoms[I] = nullptr; 00700 this->DomTreeNodes[I] = nullptr; 00701 }

implicitly assumes that it should be possible to convert a TraitsTy::nodes_iterator into a NodeT *.

In my case, TraitsTy is GraphTraits<CallGraph *> and NodeT is CallGraphNode. I was able to understand that this works fine for the DominatorTree class, as the corresponding TraitsTy::nodes_iterator is a iplist::iterator, which provides a type-cast operator to BasicBlock *. I was also able to understand the error I got, since the same operator is missing for GraphTraits<CallGraph *>::nodes_iterator.

My question is whether the ability of casting a GraphTraits::nodes_iterator into a NodeT * is a mandatory requirement for using DominatorTreeBase.

Thanks, Ettore Speziale -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20141031/a7a7d18d/attachment.html>

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