-//===- llvm/Analysis/Intervals.h - Interval partition Calculation-*- C++ -*--=//
+//===- llvm/Analysis/Interval.h - Interval Class Declaration -----*- C++ -*--=//
//
-// This file contains the declaration of the cfg::IntervalPartition class, which
-// calculates and represents the interval partition of a method, or a
-// preexisting interval partition.
-//
-// 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: 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.
+// This file contains the declaration of the cfg::Interval class, which
+// represents a set of CFG nodes and is a portion of an interval partition.
+//
+// Intervals have some interesting and useful properties, including the
+// following:
+// 1. The header node of an interval dominates all of the elements of the
+// interval
//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_INTERVALS_H
-#define LLVM_INTERVALS_H
+#ifndef LLVM_INTERVAL_H
+#define LLVM_INTERVAL_H
-#include "llvm/Method.h"
-#include "llvm/CFG.h"
#include <vector>
-#include <map>
-#include <stack>
-#include <set>
-#include <algorithm>
-class Method;
class BasicBlock;
namespace cfg {
-class IntervalPartition;
-
//===----------------------------------------------------------------------===//
//
// Interval Class - An Interval is a set of nodes defined such that every node
// header)
//
class Interval {
- friend class IntervalPartition;
-
// HeaderNode - The header BasicBlock, which dominates all BasicBlocks in this
// interval. Also, any loops in this interval must go through the HeaderNode.
//
typedef vector<BasicBlock*>::iterator pred_iterator;
typedef vector<BasicBlock*>::iterator node_iterator;
+ inline Interval(BasicBlock *Header) : HeaderNode(Header) {
+ Nodes.push_back(Header);
+ }
+
inline BasicBlock *getHeaderNode() const { return HeaderNode; }
// Nodes - The basic blocks in this interval.
// contains - Find out if a basic block is in this interval
inline bool contains(BasicBlock *BB) const {
- return find(Nodes.begin(), Nodes.end(), BB) != Nodes.end();
+ for (unsigned i = 0; i < Nodes.size(); ++i)
+ if (Nodes[i] == BB) return true;
+ return false;
+ // I don't want the dependency on <algorithm>
+ //return find(Nodes.begin(), Nodes.end(), BB) != Nodes.end();
}
// isSuccessor - find out if a basic block is a successor of this Interval
inline bool isSuccessor(BasicBlock *BB) const {
- return find(Successors.begin(), Successors.end(), BB) != Successors.end();
+ for (unsigned i = 0; i < Successors.size(); ++i)
+ if (Successors[i] == BB) return true;
+ return false;
+ // I don't want the dependency on <algorithm>
+ //return find(Successors.begin(), Successors.end(), BB) != Successors.end();
}
// isLoop - Find out if there is a back edge in this interval...
bool isLoop() const;
-
- //private: // Only accessable by IntervalPartition class
- inline Interval(BasicBlock *Header) : HeaderNode(Header) {
- Nodes.push_back(Header);
- }
};
return I->Predecessors.end();
}
-
-//===----------------------------------------------------------------------===//
-// 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
-// a method. This partition divides the control flow graph into a set of
-// maximal intervals, as defined with the properties above. Intuitively, a
-// BasicBlock is a (possibly nonexistent) loop with a "tail" of non looping
-// nodes following it.
-//
-class IntervalPartition {
- typedef map<BasicBlock*, Interval*> IntervalMapTy;
- IntervalMapTy IntervalMap;
-
- typedef vector<Interval*> IntervalListTy;
- IntervalListTy IntervalList;
- Interval *RootInterval;
-
-public:
- typedef IntervalListTy::iterator iterator;
-
-public:
- // IntervalPartition ctor - Build the partition for the specified method
- IntervalPartition(Method *M);
-
- // IntervalPartition ctor - Build a reduced interval partition from an
- // existing interval graph. This takes an additional boolean parameter to
- // distinguish it from a copy constructor. Always pass in false for now.
- //
- IntervalPartition(IntervalPartition &I, bool);
-
- // Destructor - Free memory
- ~IntervalPartition();
-
- // getRootInterval() - Return the root interval that contains the starting
- // block of the method.
- inline Interval *getRootInterval() { return RootInterval; }
-
- // isDegeneratePartition() - Returns true if the interval partition contains
- // a single interval, and thus cannot be simplified anymore.
- bool isDegeneratePartition() { return size() == 1; }
-
- // TODO: isIrreducible - look for triangle graph.
-
- // getBlockInterval - Return the interval that a basic block exists in.
- inline Interval *getBlockInterval(BasicBlock *BB) {
- IntervalMapTy::iterator I = IntervalMap.find(BB);
- return I != IntervalMap.end() ? I->second : 0;
- }
-
- // Iterators to iterate over all of the intervals in the method
- inline iterator begin() { return IntervalList.begin(); }
- inline iterator end() { return IntervalList.end(); }
- inline unsigned size() { return IntervalList.size(); }
-
-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.
- //
- template<class NodeTy, class OrigContainer>
- void ProcessInterval(NodeTy *Node, OrigContainer *OC);
-
- // 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.
- //
- template<class NodeTy, class OrigContainer>
- void ProcessNode(Interval *Int, NodeTy *Node, OrigContainer *OC);
-
- // 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);
- inline void addNodeToInterval(Interval *Int, BasicBlock *BB);
-
- // updatePredecessors - Interval generation only sets the successor fields of
- // the interval data structures. After interval generation is complete,
- // run through all of the intervals and propogate successor info as
- // predecessor info.
- //
- 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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