1 files changed, 14 insertions, 4 deletions

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 3909c56bdbb2..58763718f9b5 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -2371,16 +2371,26 @@ namespace {
   struct DepthMBBCompare {
     typedef std::pair<unsigned, MachineBasicBlock*> DepthMBBPair;
     bool operator()(const DepthMBBPair &LHS, const DepthMBBPair &RHS) const {
-      if (LHS.first > RHS.first) return true;   // Deeper loops first
-      return LHS.first == RHS.first &&
-        LHS.second->getNumber() < RHS.second->getNumber();
+      // Deeper loops first
+      if (LHS.first != RHS.first)
+        return LHS.first > RHS.first;
+
+      // Prefer blocks that are more connected in the CFG. This takes care of
+      // the most difficult copies first while intervals are short.
+      unsigned cl = LHS.second->pred_size() + LHS.second->succ_size();
+      unsigned cr = RHS.second->pred_size() + RHS.second->succ_size();
+      if (cl != cr)
+        return cl > cr;
+
+      // As a last resort, sort by block number.
+      return LHS.second->getNumber() < RHS.second->getNumber();
     }
   };
 }
 
 void SimpleRegisterCoalescing::CopyCoalesceInMBB(MachineBasicBlock *MBB,
                                                std::vector<CopyRec> &TryAgain) {
-  DEBUG(errs() << ((Value*)MBB->getBasicBlock())->getName() << ":\n");
+  DEBUG(errs() << MBB->getName() << ":\n");
 
   std::vector<CopyRec> VirtCopies;
   std::vector<CopyRec> PhysCopies;