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().

llvm-svn: 257130

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/Support/IntEqClasses.cpp b/llvm/lib/Support/IntEqClasses.cpp
index 11344956e4c..ff213570807 100644
--- a/llvm/lib/Support/IntEqClasses.cpp
+++ b/llvm/lib/Support/IntEqClasses.cpp
@@ -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, unsigned b) {
       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 {