// In this way, the interval partition may be used to reduce a flow graph down
// to its degenerate single node interval partition (unless it is irreducible).
//
-// TODO: Provide an interval iterator that codifies the internals of
-// IntervalPartition. Inside, it would have a stack of Interval*'s, and would
-// walk the interval partition in depth first order. IntervalPartition would
-// then be a client of this iterator. The iterator should work on Method*,
-// const Method*, IntervalPartition*, and const IntervalPartition*.
+// TODO: The IntervalPartition class should take a bool parameter that tells
+// whether it should add the "tails" of an interval to an interval itself or if
+// they should be represented as distinct intervals.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_INTERVALS_H
#define LLVM_INTERVALS_H
+#include "llvm/Method.h"
+#include "llvm/CFG.h"
#include <vector>
#include <map>
+#include <stack>
+#include <set>
#include <algorithm>
class Method;
// isLoop - Find out if there is a back edge in this interval...
bool isLoop() const;
-private: // Only accessable by IntervalPartition class
+ //private: // Only accessable by IntervalPartition class
inline Interval(BasicBlock *Header) : HeaderNode(Header) {
Nodes.push_back(Header);
}
}
+//===----------------------------------------------------------------------===//
+// IntervalIterator
+//
+// TODO: Provide an interval iterator that codifies the internals of
+// IntervalPartition. Inside, it would have a stack of Interval*'s, and would
+// walk the interval partition in depth first order. IntervalPartition would
+// then be a client of this iterator. The iterator should work on Method*,
+// const Method*, IntervalPartition*, and const IntervalPartition*.
+//
+
+template<class NodeTy, class OrigContainer_t>
+class IntervalIterator {
+ stack<pair<Interval, typename Interval::succ_iterator> > IntStack;
+ set<BasicBlock*> Visited;
+ OrigContainer_t *OrigContainer;
+public:
+ typedef BasicBlock* _BB;
+
+ typedef IntervalIterator<NodeTy, OrigContainer_t> _Self;
+ typedef forward_iterator_tag iterator_category;
+
+ IntervalIterator() {} // End iterator, empty stack
+ IntervalIterator(Method *M) {
+ OrigContainer = M;
+ if (!ProcessInterval(M->getBasicBlocks().front())) {
+ assert(0 && "ProcessInterval should never fail for first interval!");
+ }
+ }
+
+ inline bool operator==(const _Self& x) const { return IntStack == x.IntStack; }
+ inline bool operator!=(const _Self& x) const { return !operator==(x); }
+
+ inline Interval &operator*() const { return IntStack.top(); }
+ inline Interval *operator->() const { return &(operator*()); }
+
+ inline _Self& operator++() { // Preincrement
+ do {
+ // All of the intervals on the stack have been visited. Try visiting their
+ // successors now.
+ Interval &CurInt = IntStack.top().first;
+ Interval::iterator &SuccIt = IntStack.top().second,End = succ_end(&CurInt);
+
+ for (; SuccIt != End; ++SuccIt) // Loop over all interval successors
+ if (ProcessInterval(*SuccIt)) // Found a new interval!
+ return *this; // Use it!
+
+ // We ran out of successors for this interval... pop off the stack
+ IntStack.pop();
+ } while (!IntStack.empty());
+
+ return *this;
+ }
+ inline _Self operator++(int) { // Postincrement
+ _Self tmp = *this; ++*this; return tmp;
+ }
+
+private:
+ // ProcessInterval - This method is used during the construction of the
+ // interval graph. It walks through the source graph, recursively creating
+ // an interval per invokation until the entire graph is covered. This uses
+ // the ProcessNode method to add all of the nodes to the interval.
+ //
+ // This method is templated because it may operate on two different source
+ // graphs: a basic block graph, or a preexisting interval graph.
+ //
+ bool ProcessInterval(NodeTy *Node) {
+ BasicBlock *Header = getNodeHeader(Node);
+ if (Visited.count(Header)) return false;
+
+ Interval Int(Header);
+ Visited.insert(Header); // The header has now been visited!
+
+ // Check all of our successors to see if they are in the interval...
+ for (typename NodeTy::succ_iterator I = succ_begin(Node), E = succ_end(Node);
+ I != E; ++I)
+ ProcessNode(&Int, getSourceGraphNode(OrigContainer, *I));
+
+ IntStack.push(make_pair(Int, succ_begin(&Int)));
+ return true;
+ }
+
+ // ProcessNode - This method is called by ProcessInterval to add nodes to the
+ // interval being constructed, and it is also called recursively as it walks
+ // the source graph. A node is added to the current interval only if all of
+ // its predecessors are already in the graph. This also takes care of keeping
+ // the successor set of an interval up to date.
+ //
+ // This method is templated because it may operate on two different source
+ // graphs: a basic block graph, or a preexisting interval graph.
+ //
+ void ProcessNode(Interval *Int, NodeTy *Node) {
+ assert(Int && "Null interval == bad!");
+ assert(Node && "Null Node == bad!");
+
+ BasicBlock *NodeHeader = getNodeHeader(Node);
+
+ if (Visited.count(NodeHeader)) { // Node already been visited?
+ if (Int->contains(NodeHeader)) { // Already in this interval...
+ return;
+ } else { // In another interval, add as successor
+ if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set
+ Int->Successors.push_back(NodeHeader);
+ }
+ } else { // Otherwise, not in interval yet
+ for (typename NodeTy::pred_iterator I = pred_begin(Node),
+ E = pred_end(Node); I != E; ++I) {
+ if (!Int->contains(*I)) { // If pred not in interval, we can't be
+ if (!Int->isSuccessor(NodeHeader)) // Add only if not already in set
+ Int->Successors.push_back(NodeHeader);
+ return; // See you later
+ }
+ }
+
+ // If we get here, then all of the predecessors of BB are in the interval
+ // already. In this case, we must add BB to the interval!
+ addNodeToInterval(Int, Node);
+ Visited.insert(NodeHeader); // The node has now been visited!
+
+ if (Int->isSuccessor(NodeHeader)) {
+ // If we were in the successor list from before... remove from succ list
+ Int->Successors.erase(remove(Int->Successors.begin(),
+ Int->Successors.end(), NodeHeader),
+ Int->Successors.end());
+ }
+
+ // Now that we have discovered that Node is in the interval, perhaps some
+ // of its successors are as well?
+ for (typename NodeTy::succ_iterator It = succ_begin(Node),
+ End = succ_end(Node); It != End; ++It)
+ ProcessNode(Int, getSourceGraphNode(OrigContainer, *It));
+ }
+ }
+};
+
+
//===----------------------------------------------------------------------===//
//
// IntervalPartition - This class builds and holds an "interval partition" for
void updatePredecessors(Interval *Int);
};
+
+
+// getNodeHeader - Given a source graph node and the source graph, return the
+// BasicBlock that is the header node. This is the opposite of
+// getSourceGraphNode.
+//
+inline BasicBlock *getNodeHeader(BasicBlock *BB) { return BB; }
+inline BasicBlock *getNodeHeader(Interval *I) { return I->getHeaderNode(); }
+
+// getSourceGraphNode - Given a BasicBlock and the source graph, return the
+// source graph node that corresponds to the BasicBlock. This is the opposite
+// of getNodeHeader.
+//
+inline BasicBlock *getSourceGraphNode(Method *, BasicBlock *BB) {
+ return BB;
+}
+inline Interval *getSourceGraphNode(IntervalPartition *IP, BasicBlock *BB) {
+ return IP->getBlockInterval(BB);
+}
+
+// addNodeToInterval - This method exists to assist the generic ProcessNode
+// with the task of adding a node to the new interval, depending on the
+// type of the source node. In the case of a CFG source graph (BasicBlock
+// case), the BasicBlock itself is added to the interval.
+//
+inline void addNodeToInterval(Interval *Int, BasicBlock *BB){
+ Int->Nodes.push_back(BB);
+}
+
+// addNodeToInterval - This method exists to assist the generic ProcessNode
+// with the task of adding a node to the new interval, depending on the
+// type of the source node. In the case of a CFG source graph (BasicBlock
+// case), the BasicBlock itself is added to the interval. In the case of
+// an IntervalPartition source graph (Interval case), all of the member
+// BasicBlocks are added to the interval.
+//
+inline void addNodeToInterval(Interval *Int, Interval *I) {
+ // Add all of the nodes in I as new nodes in Int.
+ copy(I->Nodes.begin(), I->Nodes.end(), back_inserter(Int->Nodes));
+}
+
+
+
+
+typedef IntervalIterator<BasicBlock, Method> method_interval_iterator;
+
+
+method_interval_iterator intervals_begin(Method *M) {
+ return method_interval_iterator(M);
+}
+method_interval_iterator intervals_end(Method *M) {
+ return method_interval_iterator();
+}
+
} // End namespace cfg
#endif
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