[llvm] r257130 - IntEqClasses: Let join() return the new leader

[Matthias Braun via llvm-commits]

Author: matze
Date: Thu Jan  7 19:16:39 2016
New Revision: 257130

URL: http://llvm.org/viewvc/llvm-project?rev=257130&view=rev
Log:
IntEqClasses: Let join() return the new leader

The new leader is known anyway so we can return it for some micro
optimization in code where it is easy to pass along the result to the
next join().

Modified:
    llvm/trunk/include/llvm/ADT/IntEqClasses.h
    llvm/trunk/lib/Support/IntEqClasses.cpp

Modified: llvm/trunk/include/llvm/ADT/IntEqClasses.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/IntEqClasses.h?rev=257130&r1=257129&r2=257130&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/IntEqClasses.h (original)
+++ llvm/trunk/include/llvm/ADT/IntEqClasses.h Thu Jan  7 19:16:39 2016
@@ -53,10 +53,10 @@ public:
     NumClasses = 0;
   }
 
-  /// join - Join the equivalence classes of a and b. After joining classes,
-  /// findLeader(a) == findLeader(b).
-  /// This requires an uncompressed map.
-  void join(unsigned a, unsigned b);
+  /// Join the equivalence classes of a and b. After joining classes,
+  /// findLeader(a) == findLeader(b). This requires an uncompressed map.
+  /// Returns the new leader.
+  unsigned join(unsigned a, unsigned b);
 
   /// findLeader - Compute the leader of a's equivalence class. This is the
   /// smallest member of the class.

Modified: llvm/trunk/lib/Support/IntEqClasses.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/IntEqClasses.cpp?rev=257130&r1=257129&r2=257130&view=diff
==============================================================================
--- llvm/trunk/lib/Support/IntEqClasses.cpp (original)
+++ llvm/trunk/lib/Support/IntEqClasses.cpp Thu Jan  7 19:16:39 2016
@@ -29,7 +29,7 @@ void IntEqClasses::grow(unsigned N) {
     EC.push_back(EC.size());
 }
 
-void IntEqClasses::join(unsigned a, unsigned b) {
+unsigned IntEqClasses::join(unsigned a, unsigned b) {
   assert(NumClasses == 0 && "join() called after compress().");
   unsigned eca = EC[a];
   unsigned ecb = EC[b];
@@ -41,6 +41,8 @@ void IntEqClasses::join(unsigned a, unsi
       EC[b] = eca, b = ecb, ecb = EC[b];
     else
       EC[a] = ecb, a = eca, eca = EC[a];
+
+  return eca;
 }
 
 unsigned IntEqClasses::findLeader(unsigned a) const {