1 files changed, 34 insertions, 8 deletions

diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 348ed3a..6ea933d 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -65,6 +65,7 @@ LiveVariables::VarInfo::findKill(const MachineBasicBlock *MBB) const {
 }
 
 void LiveVariables::VarInfo::dump() const {
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
   dbgs() << "  Alive in blocks: ";
   for (SparseBitVector<>::iterator I = AliveBlocks.begin(),
            E = AliveBlocks.end(); I != E; ++I)
@@ -77,6 +78,7 @@ void LiveVariables::VarInfo::dump() const {
       dbgs() << "\n    #" << i << ": " << *Kills[i];
     dbgs() << "\n";
   }
+#endif
 }
 
 /// getVarInfo - Get (possibly creating) a VarInfo object for the given vreg.
@@ -501,8 +503,6 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
   MRI = &mf.getRegInfo();
   TRI = MF->getTarget().getRegisterInfo();
 
-  ReservedRegisters = TRI->getReservedRegs(mf);
-
   unsigned NumRegs = TRI->getNumRegs();
   PhysRegDef  = new MachineInstr*[NumRegs];
   PhysRegUse  = new MachineInstr*[NumRegs];
@@ -586,7 +586,7 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
         unsigned MOReg = UseRegs[i];
         if (TargetRegisterInfo::isVirtualRegister(MOReg))
           HandleVirtRegUse(MOReg, MBB, MI);
-        else if (!ReservedRegisters[MOReg])
+        else if (!MRI->isReserved(MOReg))
           HandlePhysRegUse(MOReg, MI);
       }
 
@@ -599,7 +599,7 @@ bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
         unsigned MOReg = DefRegs[i];
         if (TargetRegisterInfo::isVirtualRegister(MOReg))
           HandleVirtRegDef(MOReg, MI);
-        else if (!ReservedRegisters[MOReg])
+        else if (!MRI->isReserved(MOReg))
           HandlePhysRegDef(MOReg, MI, Defs);
       }
       UpdatePhysRegDefs(MI, Defs);
@@ -806,18 +806,44 @@ void LiveVariables::addNewBlock(MachineBasicBlock *BB,
                                 MachineBasicBlock *SuccBB) {
   const unsigned NumNew = BB->getNumber();
 
-  // All registers used by PHI nodes in SuccBB must be live through BB.
-  for (MachineBasicBlock::iterator BBI = SuccBB->begin(),
-         BBE = SuccBB->end(); BBI != BBE && BBI->isPHI(); ++BBI)
+  SmallSet<unsigned, 16> Defs, Kills;
+
+  MachineBasicBlock::iterator BBI = SuccBB->begin(), BBE = SuccBB->end();
+  for (; BBI != BBE && BBI->isPHI(); ++BBI) {
+    // Record the def of the PHI node.
+    Defs.insert(BBI->getOperand(0).getReg());
+
+    // All registers used by PHI nodes in SuccBB must be live through BB.
     for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
       if (BBI->getOperand(i+1).getMBB() == BB)
         getVarInfo(BBI->getOperand(i).getReg()).AliveBlocks.set(NumNew);
+  }
+
+  // Record all vreg defs and kills of all instructions in SuccBB.
+  for (; BBI != BBE; ++BBI) {
+    for (MachineInstr::mop_iterator I = BBI->operands_begin(),
+         E = BBI->operands_end(); I != E; ++I) {
+      if (I->isReg() && TargetRegisterInfo::isVirtualRegister(I->getReg())) {
+        if (I->isDef())
+          Defs.insert(I->getReg());
+        else if (I->isKill())
+          Kills.insert(I->getReg());
+      }
+    }
+  }
 
   // Update info for all live variables
   for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
     unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
+
+    // If the Defs is defined in the successor it can't be live in BB.
+    if (Defs.count(Reg))
+      continue;
+
+    // If the register is either killed in or live through SuccBB it's also live
+    // through BB.
     VarInfo &VI = getVarInfo(Reg);
-    if (!VI.AliveBlocks.test(NumNew) && VI.isLiveIn(*SuccBB, Reg, *MRI))
+    if (Kills.count(Reg) || VI.AliveBlocks.test(SuccBB->getNumber()))
       VI.AliveBlocks.set(NumNew);
   }
 }