2 files changed, 17 insertions, 2 deletions
diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index 3cf10b3ac6..a38c881982 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -398,8 +398,14 @@ void MachineFunction::viewCFGOnly() const
 unsigned MachineFunction::addLiveIn(unsigned PReg,
                                     const TargetRegisterClass *RC) {
   assert(RC->contains(PReg) && "Not the correct regclass!");
-  unsigned VReg = getRegInfo().createVirtualRegister(RC);
-  getRegInfo().addLiveIn(PReg, VReg);
+  MachineRegisterInfo &MRI = getRegInfo();
+  unsigned VReg = MRI.getLiveInVirtReg(PReg);
+  if (VReg) {
+    assert(MRI.getRegClass(VReg) == RC && "Register class mismatch!");
+    return VReg;
+  }
+  VReg = MRI.createVirtualRegister(RC);
+  MRI.addLiveIn(PReg, VReg);
   return VReg;
 }
 
diff --git a/lib/CodeGen/MachineRegisterInfo.cpp b/lib/CodeGen/MachineRegisterInfo.cpp
index 402be479ea..70bf7e5da5 100644
--- a/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/lib/CodeGen/MachineRegisterInfo.cpp
@@ -165,6 +165,15 @@ unsigned MachineRegisterInfo::getLiveInPhysReg(unsigned VReg) const {
   return 0;
 }
 
+/// getLiveInVirtReg - If PReg is a live-in physical register, return the
+/// corresponding live-in physical register.
+unsigned MachineRegisterInfo::getLiveInVirtReg(unsigned PReg) const {
+  for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
+    if (I->first == PReg)
+      return I->second;
+  return 0;
+}
+
 static cl::opt<bool>
 SchedLiveInCopies("schedule-livein-copies", cl::Hidden,
                   cl::desc("Schedule copies of livein registers"),