1 files changed, 6 insertions, 4 deletions
diff --git a/lib/CodeGen/MachineRegisterInfo.cpp b/lib/CodeGen/MachineRegisterInfo.cpp
index d7953896be..d513f29e7c 100644
--- a/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/lib/CodeGen/MachineRegisterInfo.cpp
@@ -49,15 +49,17 @@ MachineRegisterInfo::setRegClass(unsigned Reg, const TargetRegisterClass *RC) {
 
 const TargetRegisterClass *
 MachineRegisterInfo::constrainRegClass(unsigned Reg,
-                                       const TargetRegisterClass *RC) {
+                                       const TargetRegisterClass *RC,
+                                       unsigned MinNumRegs) {
   const TargetRegisterClass *OldRC = getRegClass(Reg);
   if (OldRC == RC)
     return RC;
   const TargetRegisterClass *NewRC = getCommonSubClass(OldRC, RC);
-  if (!NewRC)
+  if (!NewRC || NewRC == OldRC)
+    return NewRC;
+  if (NewRC->getNumRegs() < MinNumRegs)
     return 0;
-  if (NewRC != OldRC)
-    setRegClass(Reg, NewRC);
+  setRegClass(Reg, NewRC);
   return NewRC;
 }