Shrink a BitVector that didn't mean to store bits for all physical registers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123108 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 693fbb6..63e6ec3 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1016,8 +1016,7 @@
         << MF.getFunction()->getName() << '\n');
 
   // ReMatRegs - Keep track of the registers whose def's are remat'ed.
-  BitVector ReMatRegs;
-  ReMatRegs.resize(MRI->getLastVirtReg()+1);
+  BitVector ReMatRegs(MRI->getNumVirtRegs());
 
   typedef DenseMap<unsigned, SmallVector<std::pair<unsigned, unsigned>, 4> >
     TiedOperandMap;
@@ -1146,7 +1145,7 @@
             DEBUG(dbgs() << "2addr: REMATTING : " << *DefMI << "\n");
             unsigned regASubIdx = mi->getOperand(DstIdx).getSubReg();
             TII->reMaterialize(*mbbi, mi, regA, regASubIdx, DefMI, *TRI);
-            ReMatRegs.set(regB);
+            ReMatRegs.set(TargetRegisterInfo::virtReg2Index(regB));
             ++NumReMats;
           } else {
             BuildMI(*mbbi, mi, mi->getDebugLoc(), TII->get(TargetOpcode::COPY),
@@ -1232,13 +1231,12 @@
   }
 
   // Some remat'ed instructions are dead.
-  int VReg = ReMatRegs.find_first();
-  while (VReg != -1) {
+  for (int i = ReMatRegs.find_first(); i != -1; i = ReMatRegs.find_next(i)) {
+    unsigned VReg = TargetRegisterInfo::index2VirtReg(i);
     if (MRI->use_nodbg_empty(VReg)) {
       MachineInstr *DefMI = MRI->getVRegDef(VReg);
       DefMI->eraseFromParent();
     }
-    VReg = ReMatRegs.find_next(VReg);
   }
 
   // Eliminate REG_SEQUENCE instructions. Their whole purpose was to preseve