Add capability to build a derived interval graph

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/Interval.h b/include/llvm/Analysis/Interval.h
index a17e655c9e4853652bacdd2d47f85216988367df..3c22f6dc7caf5daa29b3a72b55579b772687f770 100644 (file)
--- a/include/llvm/Analysis/Interval.h
+++ b/include/llvm/Analysis/Interval.h
@@ -1,7 +1,11 @@
 //===- llvm/Analysis/Intervals.h - Interval partition Calculation-*- C++ -*--=//
 //
 // This file contains the declaration of the cfg::IntervalPartition class, which
-// calculates and represent the interval partition of a method.
+// 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).
 //
 //===----------------------------------------------------------------------===//
 
@@ -64,6 +68,28 @@ private:           // Only accessable by IntervalPartition class
 };
 
 
+// succ_begin/succ_end - define global functions so that Intervals may be used
+// just like BasicBlocks can with the succ_* functions, and *::succ_iterator.
+//
+inline Interval::succ_iterator succ_begin(Interval *I) { 
+  return I->Successors.begin();
+}
+inline Interval::succ_iterator succ_end(Interval *I) { 
+  return I->Successors.end();
+}
+
+// pred_begin/pred_end - define global functions so that Intervals may be used
+// just like BasicBlocks can with the pred_* functions, and *::pred_iterator.
+//
+inline Interval::pred_iterator pred_begin(Interval *I) { 
+  return I->Predecessors.begin();
+}
+inline Interval::pred_iterator pred_end(Interval *I) { 
+  return I->Predecessors.end();
+}
+
+
+
 // 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
@@ -85,6 +111,12 @@ 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);
+
   // getRootInterval() - Return the root interval that contains the starting
   // block of the method
   inline Interval *getRootInterval() { return RootInterval; }
@@ -102,9 +134,45 @@ public:
   inline iterator end()   { return IntervalList.end(); }
 
 private:
-  void ProcessInterval(BasicBlock *Header);
-  void ProcessBasicBlock(Interval *I, BasicBlock *BB);
-  void UpdateSuccessors(Interval *Int);
+  // 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);
 };
 
 }    // End namespace cfg

diff --git a/lib/Analysis/Interval.cpp b/lib/Analysis/Interval.cpp
index f1737fc39af106f46a7eb83e1e3f952b76b632b0..ac4846ae62020e2f26a049cdbceb4979009e66bc 100644 (file)
--- a/lib/Analysis/Interval.cpp
+++ b/lib/Analysis/Interval.cpp
@@ -10,76 +10,185 @@
 #include "llvm/BasicBlock.h"
 #include "llvm/CFG.h"
 
-void cfg::IntervalPartition::UpdateSuccessors(cfg::Interval *Int) {
-  BasicBlock *Header = Int->HeaderNode;
-  for (cfg::Interval::succ_iterator I = Int->Successors.begin(), 
-                                   E = Int->Successors.end(); I != E; ++I)
-    getBlockInterval(*I)->Predecessors.push_back(Header);
-}
+using namespace cfg;
 
-// IntervalPartition ctor - Build the partition for the specified method
-cfg::IntervalPartition::IntervalPartition(Method *M) {
-  BasicBlock *MethodStart = M->getBasicBlocks().front();
-  assert(MethodStart && "Cannot operate on prototypes!");
+// 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 static BasicBlock *getNodeHeader(BasicBlock *BB) { return BB; }
+inline static BasicBlock *getNodeHeader(Interval *I) { return I->HeaderNode; }
 
-  ProcessInterval(MethodStart);
-  RootInterval = getBlockInterval(MethodStart);
 
-  // Now that we know all of the successor information, propogate this to the
-  // predecessors for each block...
-  for(iterator I = begin(), E = end(); I != E; ++I)
-    UpdateSuccessors(*I);
+// 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 static BasicBlock *getSourceGraphNode(Method *, BasicBlock *BB) {
+  return BB; 
+}
+inline static Interval *getSourceGraphNode(IntervalPartition *IP, 
+                                          BasicBlock *BB) { 
+  return IP->getBlockInterval(BB);
 }
 
-void cfg::IntervalPartition::ProcessInterval(BasicBlock *Header) {
-  if (getBlockInterval(Header)) return;  // Interval already constructed
 
-  Interval *Int = new Interval(Header);
-  IntervalList.push_back(Int);           // Add the interval to our current set
-  IntervalMap.insert(make_pair(Header, Int));
+// 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 IntervalPartition::addNodeToInterval(Interval *Int, BasicBlock *BB){
+  Int->Nodes.push_back(BB);
+  IntervalMap.insert(make_pair(BB, Int));
+}
 
-  // Check all of our successors to see if they are in the interval...
-  for (succ_iterator I = succ_begin(Header), E = succ_end(Header); I != E; ++I)
-    ProcessBasicBlock(Int, *I);
+// 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 IntervalPartition::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));
 
-  // Build all of the successor intervals of this interval now...
-  for(Interval::succ_iterator I = Int->Successors.begin(), 
-       E = Int->Successors.end(); I != E; ++I)
-    ProcessInterval(*I);
+  // Add mappings for all of the basic blocks in I to the IntervalPartition
+  for (Interval::node_iterator It = I->Nodes.begin(), End = I->Nodes.end();
+       It != End; ++It)
+    IntervalMap.insert(make_pair(*It, Int));
 }
 
-void cfg::IntervalPartition::ProcessBasicBlock(Interval *Int, BasicBlock *BB) {
-  assert(Int && "Null interval == bad!");
-  assert(BB && "Null interval == bad!");
 
-  Interval *CurInt = getBlockInterval(BB);
+// 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 IntervalPartition::ProcessNode(Interval *Int, 
+                                   NodeTy *Node, OrigContainer *OC) {
+  assert(Int && "Null interval == bad!");
+  assert(Node && "Null Node == bad!");
+  
+  BasicBlock *NodeHeader = getNodeHeader(Node);
+  Interval *CurInt = getBlockInterval(NodeHeader);
   if (CurInt == Int) {                  // Already in this interval...
     return;
   } else if (CurInt != 0) {             // In another interval, add as successor
-    if (!Int->isSuccessor(BB))          // Add only if not already in set
-      Int->Successors.push_back(BB);
+    if (!Int->isSuccessor(NodeHeader))  // Add only if not already in set
+      Int->Successors.push_back(NodeHeader);
   } else {                              // Otherwise, not in interval yet
-    for (pred_iterator I = pred_begin(BB), E = pred_end(BB); I != E; ++I) {
+    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(BB))      // Add only if not already in set
-         Int->Successors.push_back(BB);
+       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!
-    Int->Nodes.push_back(BB);
-    IntervalMap.insert(make_pair(BB, Int));
+    addNodeToInterval(Int, Node);
     
-    if (Int->isSuccessor(BB)) {
+    if (Int->isSuccessor(NodeHeader)) {
       // If we were in the successor list from before... remove from succ list
-      remove(Int->Successors.begin(), Int->Successors.end(), BB);
+      Int->Successors.erase(remove(Int->Successors.begin(),
+                                  Int->Successors.end(), NodeHeader), 
+                           Int->Successors.end());
     }
     
-    // Now that we have discovered that BB is in the interval, perhaps some of
+    // Now that we have discovered that Node is in the interval, perhaps some of
     // its successors are as well?
-    for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
-      ProcessBasicBlock(Int, *I);
+    for (typename NodeTy::succ_iterator It = succ_begin(Node), 
+                                       End = succ_end(Node); It != End; ++It)
+      ProcessNode(Int, getSourceGraphNode(OC, *It), OC);
   }
 }
+
+
+// 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 IntervalPartition::ProcessInterval(NodeTy *Node, OrigContainer *OC) {
+  BasicBlock *Header = getNodeHeader(Node);
+  if (getBlockInterval(Header)) return;  // Interval already constructed?
+
+  // Create a new interval and add the interval to our current set
+  Interval *Int = new Interval(Header);
+  IntervalList.push_back(Int);
+  IntervalMap.insert(make_pair(Header, Int));
+
+  // 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(OC, *I), OC);
+
+  // Build all of the successor intervals of this interval now...
+  for(Interval::succ_iterator I = Int->Successors.begin(), 
+                              E = Int->Successors.end(); I != E; ++I) {
+    ProcessInterval(getSourceGraphNode(OC, *I), OC);
+  }
+}
+
+
+
+// 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 IntervalPartition::updatePredecessors(cfg::Interval *Int) {
+  BasicBlock *Header = Int->HeaderNode;
+  for (Interval::succ_iterator I = Int->Successors.begin(), 
+                              E = Int->Successors.end(); I != E; ++I)
+    getBlockInterval(*I)->Predecessors.push_back(Header);
+}
+
+
+
+// IntervalPartition ctor - Build the first level interval partition for the
+// specified method...
+//
+IntervalPartition::IntervalPartition(Method *M) {
+  BasicBlock *MethodStart = M->getBasicBlocks().front();
+  assert(MethodStart && "Cannot operate on prototypes!");
+
+  ProcessInterval(MethodStart, M);
+  RootInterval = getBlockInterval(MethodStart);
+
+  // Now that we know all of the successor information, propogate this to the
+  // predecessors for each block...
+  for(iterator I = begin(), E = end(); I != E; ++I)
+    updatePredecessors(*I);
+}
+
+
+// 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(IntervalPartition &I, bool) {
+  Interval *MethodStart = I.getRootInterval();
+  assert(MethodStart && "Cannot operate on empty IntervalPartitions!");
+
+  ProcessInterval(MethodStart, &I);
+  RootInterval = getBlockInterval(*MethodStart->Nodes.begin());
+
+  // Now that we know all of the successor information, propogate this to the
+  // predecessors for each block...
+  for(iterator I = begin(), E = end(); I != E; ++I)
+    updatePredecessors(*I);
+}