/// \brief Concrete subclass of DominatorTreeBase that is used to compute a
/// normal dominator tree.
+///
+/// Definition: A block is said to be forward statically reachable if there is
+/// a path from the entry of the function to the block. A statically reachable
+/// block may become statically unreachable during optimization.
+///
+/// A forward unreachable block may appear in the dominator tree, or it may
+/// not. If it does, dominance queries will return results as if all reachable
+/// blocks dominate it. When asking for a Node corresponding to a potentially
+/// unreachable block, calling code must handle the case where the block was
+/// unreachable and the result of getNode() is nullptr.
+///
+/// Generally, a block known to be unreachable when the dominator tree is
+/// constructed will not be in the tree. One which becomes unreachable after
+/// the dominator tree is initially constructed may still exist in the tree,
+/// even if the tree is properly updated. Calling code should not rely on the
+/// preceding statements; this is stated only to assist human understanding.
class DominatorTree : public DominatorTreeBase<BasicBlock> {
public:
typedef DominatorTreeBase<BasicBlock> Base;
DominatorTree() : DominatorTreeBase<BasicBlock>(false) {}
+ explicit DominatorTree(Function &F) : DominatorTreeBase<BasicBlock>(false) {
+ recalculate(F);
+ }
DominatorTree(DominatorTree &&Arg)
: Base(std::move(static_cast<Base &>(Arg))) {}
// DominatorTree GraphTraits specializations so the DominatorTree can be
// iterable by generic graph iterators.
-template <> struct GraphTraits<DomTreeNode*> {
- typedef DomTreeNode NodeType;
- typedef NodeType::iterator ChildIteratorType;
+template <class Node, class ChildIterator> struct DomTreeGraphTraitsBase {
+ typedef Node NodeType;
+ typedef ChildIterator ChildIteratorType;
+ typedef df_iterator<Node *, SmallPtrSet<NodeType *, 8>> nodes_iterator;
- static NodeType *getEntryNode(NodeType *N) {
- return N;
- }
+ static NodeType *getEntryNode(NodeType *N) { return N; }
static inline ChildIteratorType child_begin(NodeType *N) {
return N->begin();
}
- static inline ChildIteratorType child_end(NodeType *N) {
- return N->end();
- }
+ static inline ChildIteratorType child_end(NodeType *N) { return N->end(); }
- typedef df_iterator<DomTreeNode*> nodes_iterator;
-
- static nodes_iterator nodes_begin(DomTreeNode *N) {
+ static nodes_iterator nodes_begin(NodeType *N) {
return df_begin(getEntryNode(N));
}
- static nodes_iterator nodes_end(DomTreeNode *N) {
+ static nodes_iterator nodes_end(NodeType *N) {
return df_end(getEntryNode(N));
}
};
-template <> struct GraphTraits<const DomTreeNode *> {
- typedef const DomTreeNode NodeType;
- typedef NodeType::const_iterator ChildIteratorType;
+template <>
+struct GraphTraits<DomTreeNode *>
+ : public DomTreeGraphTraitsBase<DomTreeNode, DomTreeNode::iterator> {};
- static NodeType *getEntryNode(NodeType *N) {
- return N;
- }
- static inline ChildIteratorType child_begin(NodeType *N) {
- return N->begin();
- }
- static inline ChildIteratorType child_end(NodeType *N) {
- return N->end();
- }
-
- typedef df_iterator<const DomTreeNode *> nodes_iterator;
-
- static nodes_iterator nodes_begin(const DomTreeNode *N) {
- return df_begin(getEntryNode(N));
- }
-
- static nodes_iterator nodes_end(const DomTreeNode *N) {
- return df_end(getEntryNode(N));
- }
-};
+template <>
+struct GraphTraits<const DomTreeNode *>
+ : public DomTreeGraphTraitsBase<const DomTreeNode,
+ DomTreeNode::const_iterator> {};
template <> struct GraphTraits<DominatorTree*>
: public GraphTraits<DomTreeNode*> {