[PATCH] Make updateDFSNumbers API public

[Daniel Berlin]

It looks like it generated the stupidest diff possible for this change.

In reality, what happened is i moved the updateDFSNumbers below the
public: line.

Instead, it generated a diff that makes it look like i moved everything up.
:)


On Thu, Apr 9, 2015 at 5:35 PM, Daniel Berlin <dberlin at dberlin.org> wrote:
> Hi chandlerc,
>
> There are a number of passes that could be sped up by using dominator tree DFS numbers to order or compare things across multiple bbs
> (MemorySSA, MergedLoadStoreMotion, EarlyCSE, Sinking, GVN, NewGVN, for starters :P).
>
> For example, GVN/CSE elimination can be done with a simple stack/etc (instead of full-on scoped hash table or repeated leader set walks)
>   if the DFS pair is stored next to leaders.
>
> The dominator tree keeps them, and the DOM tree nodes expose them as public, but you have no guarantee they are up to date (and in fact,
> if you split blocks or whatever during your pass, they definitely won't be)
>
> This means passes either have to compute their own versions[1], or make 32 queries, or ....
> Rather than try to hide this, i just made the API public, and make it do nothing if the numbers are already valid.
>
> [1] Which we want as a non-recursive walk, which is not pretty, sadly,
> because it cannot use the depth first iterators since you don't get called on the way back up. So you either have to do one walk with po_iterator
> and one with df_iterator, or write your own non-recursive walk that looks identical to the one in updateDFSNumbers.
>
> http://reviews.llvm.org/D8946
>
> Files:
>   include/llvm/Support/GenericDomTree.h
>
> Index: include/llvm/Support/GenericDomTree.h
> ===================================================================
> --- include/llvm/Support/GenericDomTree.h
> +++ include/llvm/Support/GenericDomTree.h
> @@ -637,10 +637,35 @@
>    friend void
>    Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType> &DT, FuncT &F);
>
> +
> +  DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
> +    if (DomTreeNodeBase<NodeT> *Node = getNode(BB))
> +      return Node;
> +
> +    // Haven't calculated this node yet?  Get or calculate the node for the
> +    // immediate dominator.
> +    NodeT *IDom = getIDom(BB);
> +
> +    assert(IDom || this->DomTreeNodes[nullptr]);
> +    DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
> +
> +    // Add a new tree node for this NodeT, and link it as a child of
> +    // IDomNode
> +    return (this->DomTreeNodes[BB] = IDomNode->addChild(
> +                llvm::make_unique<DomTreeNodeBase<NodeT>>(BB, IDomNode))).get();
> +  }
> +
> +  NodeT *getIDom(NodeT *BB) const { return IDoms.lookup(BB); }
> +
> +  void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
> +
> +public:
>    /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
>    /// dominator tree in dfs order.
>    void updateDFSNumbers() const {
>      unsigned DFSNum = 0;
> +    if (!DFSInfoValid)
> +        return;
>
>      SmallVector<std::pair<const DomTreeNodeBase<NodeT> *,
>                            typename DomTreeNodeBase<NodeT>::const_iterator>,
> @@ -682,28 +707,6 @@
>      DFSInfoValid = true;
>    }
>
> -  DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
> -    if (DomTreeNodeBase<NodeT> *Node = getNode(BB))
> -      return Node;
> -
> -    // Haven't calculated this node yet?  Get or calculate the node for the
> -    // immediate dominator.
> -    NodeT *IDom = getIDom(BB);
> -
> -    assert(IDom || this->DomTreeNodes[nullptr]);
> -    DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
> -
> -    // Add a new tree node for this NodeT, and link it as a child of
> -    // IDomNode
> -    return (this->DomTreeNodes[BB] = IDomNode->addChild(
> -                llvm::make_unique<DomTreeNodeBase<NodeT>>(BB, IDomNode))).get();
> -  }
> -
> -  NodeT *getIDom(NodeT *BB) const { return IDoms.lookup(BB); }
> -
> -  void addRoot(NodeT *BB) { this->Roots.push_back(BB); }
> -
> -public:
>    /// recalculate - compute a dominator tree for the given function
>    template <class FT> void recalculate(FT &F) {
>      typedef GraphTraits<FT *> TraitsTy;
>
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