diff --git a/llvm/lib/CodeGen/RegAllocFast.cpp b/llvm/lib/CodeGen/RegAllocFast.cpp
index 3cf1d72..fc150d5 100644
--- a/llvm/lib/CodeGen/RegAllocFast.cpp
+++ b/llvm/lib/CodeGen/RegAllocFast.cpp
@@ -113,9 +113,6 @@
     // Allocatable - vector of allocatable physical registers.
     BitVector Allocatable;
 
-    // Reserved - vector of reserved physical registers.
-    BitVector Reserved;
-
     // SkippedInstrs - Descriptors of instructions whose clobber list was
     // ignored because all registers were spilled. It is still necessary to
     // mark all the clobbered registers as used by the function.
@@ -501,7 +498,8 @@
   // First try to find a completely free register.
   for (TargetRegisterClass::iterator I = AOB; I != AOE; ++I) {
     unsigned PhysReg = *I;
-    if (PhysRegState[PhysReg] == regFree && !UsedInInstr.test(PhysReg))
+    if (PhysRegState[PhysReg] == regFree && !UsedInInstr.test(PhysReg) &&
+        Allocatable.test(PhysReg))
       return assignVirtToPhysReg(LRE, PhysReg);
   }
 
@@ -510,6 +508,8 @@
 
   unsigned BestReg = 0, BestCost = spillImpossible;
   for (TargetRegisterClass::iterator I = AOB; I != AOE; ++I) {
+    if (!Allocatable.test(*I))
+      continue;
     unsigned Cost = calcSpillCost(*I);
     // Cost is 0 when all aliases are already disabled.
     if (Cost == 0)
@@ -712,7 +712,7 @@
   }
 
   // Restore UsedInInstr to a state usable for allocating normal virtual uses.
-  UsedInInstr = Reserved;
+  UsedInInstr.reset();
   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
     MachineOperand &MO = MI->getOperand(i);
     if (!MO.isReg() || (MO.isDef() && !MO.isEarlyClobber())) continue;
@@ -838,7 +838,7 @@
     }
 
     // Track registers used by instruction.
-    UsedInInstr = Reserved;
+    UsedInInstr.reset();
 
     // First scan.
     // Mark physreg uses and early clobbers as used.
@@ -916,7 +916,7 @@
 
     // Track registers defined by instruction - early clobbers and tied uses at
     // this point.
-    UsedInInstr = Reserved;
+    UsedInInstr.reset();
     if (hasEarlyClobbers) {
       for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
         MachineOperand &MO = MI->getOperand(i);
@@ -1014,7 +1014,6 @@
 
   UsedInInstr.resize(TRI->getNumRegs());
   Allocatable = TRI->getAllocatableSet(*MF);
-  Reserved = TRI->getReservedRegs(*MF);
 
   // initialize the virtual->physical register map to have a 'null'
   // mapping for all virtual registers