1 files changed, 4 insertions, 2 deletions
diff --git a/llvm/lib/CodeGen/CriticalAntiDepBreaker.cpp b/llvm/lib/CodeGen/CriticalAntiDepBreaker.cpp
index e3746a98564..9d486651ce0 100644
--- a/llvm/lib/CodeGen/CriticalAntiDepBreaker.cpp
+++ b/llvm/lib/CodeGen/CriticalAntiDepBreaker.cpp
@@ -34,6 +34,9 @@ CriticalAntiDepBreaker(MachineFunction& MFi) :
   TRI(MF.getTarget().getRegisterInfo()),
   AllocatableSet(TRI->getAllocatableSet(MF))
 {
+  Classes.reserve(TRI->getNumRegs());
+  KillIndices.reserve(TRI->getNumRegs());
+  DefIndices.reserve(TRI->getNumRegs());
 }
 
 CriticalAntiDepBreaker::~CriticalAntiDepBreaker() {
@@ -41,8 +44,7 @@ CriticalAntiDepBreaker::~CriticalAntiDepBreaker() {
 
 void CriticalAntiDepBreaker::StartBlock(MachineBasicBlock *BB) {
   // Clear out the register class data.
-  std::fill(Classes, array_endof(Classes),
-            static_cast<const TargetRegisterClass *>(0));
+  Classes.clear();
 
   // Initialize the indices to indicate that no registers are live.
   const unsigned BBSize = BB->size();