Use IntEqClasses to compute connected components of live intervals.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122296 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/IntEqClasses.h

@@ -39,13 +39,20 @@ class IntEqClasses {
 
 public:
   /// IntEqClasses - Create an equivalence class mapping for 0 .. N-1.
-  IntEqClasses(unsigned N) : NumClasses(0) { grow(N); }
+  IntEqClasses(unsigned N = 0) : NumClasses(0) { grow(N); }
 
   /// grow - Increase capacity to hold 0 .. N-1, putting new integers in unique
   /// equivalence classes.
   /// This requires an uncompressed map.
   void grow(unsigned N);
 
+  /// clear - Clear all classes so that grow() will assign a unique class to
+  /// every integer.
+  void clear() {
+    EC.clear();
+    NumClasses = 0;
+  }
+
   /// join - Join the equivalence classes of a and b. After joining classes,
   /// findLeader(a) == findLeader(b).
   /// This requires an uncompressed map.

include/llvm/CodeGen/LiveInterval.h

@@ -21,7 +21,7 @@
 #ifndef LLVM_CODEGEN_LIVEINTERVAL_H
 #define LLVM_CODEGEN_LIVEINTERVAL_H
 
-#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/IntEqClasses.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/AlignOf.h"
 #include "llvm/CodeGen/SlotIndexes.h"
@@ -561,11 +561,7 @@ namespace llvm {
 
   class ConnectedVNInfoEqClasses {
     LiveIntervals &lis_;
-
-    // Map each value number to its equivalence class.
-    // The invariant is that EqClass[x] <= x.
-    // Two values are connected iff EqClass[x] == EqClass[b].
-    SmallVector<unsigned, 8> eqClass_;
+    IntEqClasses eqClass_;
 
     // Note that values a and b are connected.
     void Connect(unsigned a, unsigned b);