1 files changed, 32 insertions, 15 deletions

diff --git a/contrib/llvm-project/llvm/lib/CodeGen/PHIElimination.cpp b/contrib/llvm-project/llvm/lib/CodeGen/PHIElimination.cpp
index 54805584dbc1..77a6c37e1362 100644
--- a/contrib/llvm-project/llvm/lib/CodeGen/PHIElimination.cpp
+++ b/contrib/llvm-project/llvm/lib/CodeGen/PHIElimination.cpp
@@ -107,6 +107,7 @@ namespace {
     using BBVRegPair = std::pair<unsigned, Register>;
     using VRegPHIUse = DenseMap<BBVRegPair, unsigned>;
 
+    // Count the number of non-undef PHI uses of each register in each BB.
     VRegPHIUse VRegPHIUseCount;
 
     // Defs of PHI sources which are implicit_def.
@@ -426,9 +427,13 @@ void PHIElimination::LowerPHINode(MachineBasicBlock &MBB,
   }
 
   // Adjust the VRegPHIUseCount map to account for the removal of this PHI node.
-  for (unsigned i = 1; i != MPhi->getNumOperands(); i += 2)
-    --VRegPHIUseCount[BBVRegPair(MPhi->getOperand(i+1).getMBB()->getNumber(),
-                                 MPhi->getOperand(i).getReg())];
+  for (unsigned i = 1; i != MPhi->getNumOperands(); i += 2) {
+    if (!MPhi->getOperand(i).isUndef()) {
+      --VRegPHIUseCount[BBVRegPair(
+          MPhi->getOperand(i + 1).getMBB()->getNumber(),
+          MPhi->getOperand(i).getReg())];
+    }
+  }
 
   // Now loop over all of the incoming arguments, changing them to copy into the
   // IncomingReg register in the corresponding predecessor basic block.
@@ -461,6 +466,15 @@ void PHIElimination::LowerPHINode(MachineBasicBlock &MBB,
       assert(MRI->use_empty(SrcReg) &&
              "Expected a single use from UnspillableTerminator");
       SrcRegDef->getOperand(0).setReg(IncomingReg);
+
+      // Update LiveVariables.
+      if (LV) {
+        LiveVariables::VarInfo &SrcVI = LV->getVarInfo(SrcReg);
+        LiveVariables::VarInfo &IncomingVI = LV->getVarInfo(IncomingReg);
+        IncomingVI.AliveBlocks = std::move(SrcVI.AliveBlocks);
+        SrcVI.AliveBlocks.clear();
+      }
+
       continue;
     }
 
@@ -515,9 +529,8 @@ void PHIElimination::LowerPHINode(MachineBasicBlock &MBB,
       // case, we should mark the last such terminator as being the killing
       // block, not the copy.
       MachineBasicBlock::iterator KillInst = opBlock.end();
-      MachineBasicBlock::iterator FirstTerm = opBlock.getFirstTerminator();
-      for (MachineBasicBlock::iterator Term = FirstTerm;
-          Term != opBlock.end(); ++Term) {
+      for (MachineBasicBlock::iterator Term = InsertPos; Term != opBlock.end();
+           ++Term) {
         if (Term->readsRegister(SrcReg))
           KillInst = Term;
       }
@@ -527,7 +540,7 @@ void PHIElimination::LowerPHINode(MachineBasicBlock &MBB,
 
         if (reusedIncoming || !IncomingReg) {
           // We may have to rewind a bit if we didn't insert a copy this time.
-          KillInst = FirstTerm;
+          KillInst = InsertPos;
           while (KillInst != opBlock.begin()) {
             --KillInst;
             if (KillInst->isDebugInstr())
@@ -574,9 +587,8 @@ void PHIElimination::LowerPHINode(MachineBasicBlock &MBB,
 
         if (!isLiveOut) {
           MachineBasicBlock::iterator KillInst = opBlock.end();
-          MachineBasicBlock::iterator FirstTerm = opBlock.getFirstTerminator();
-          for (MachineBasicBlock::iterator Term = FirstTerm;
-              Term != opBlock.end(); ++Term) {
+          for (MachineBasicBlock::iterator Term = InsertPos;
+               Term != opBlock.end(); ++Term) {
             if (Term->readsRegister(SrcReg))
               KillInst = Term;
           }
@@ -586,7 +598,7 @@ void PHIElimination::LowerPHINode(MachineBasicBlock &MBB,
 
             if (reusedIncoming || !IncomingReg) {
               // We may have to rewind a bit if we didn't just insert a copy.
-              KillInst = FirstTerm;
+              KillInst = InsertPos;
               while (KillInst != opBlock.begin()) {
                 --KillInst;
                 if (KillInst->isDebugInstr())
@@ -623,14 +635,19 @@ void PHIElimination::LowerPHINode(MachineBasicBlock &MBB,
 /// used in a PHI node. We map that to the BB the vreg is coming from. This is
 /// used later to determine when the vreg is killed in the BB.
 void PHIElimination::analyzePHINodes(const MachineFunction& MF) {
-  for (const auto &MBB : MF)
+  for (const auto &MBB : MF) {
     for (const auto &BBI : MBB) {
       if (!BBI.isPHI())
         break;
-      for (unsigned i = 1, e = BBI.getNumOperands(); i != e; i += 2)
-        ++VRegPHIUseCount[BBVRegPair(BBI.getOperand(i+1).getMBB()->getNumber(),
-                                     BBI.getOperand(i).getReg())];
+      for (unsigned i = 1, e = BBI.getNumOperands(); i != e; i += 2) {
+        if (!BBI.getOperand(i).isUndef()) {
+          ++VRegPHIUseCount[BBVRegPair(
+              BBI.getOperand(i + 1).getMBB()->getNumber(),
+              BBI.getOperand(i).getReg())];
+        }
+      }
     }
+  }
 }
 
 bool PHIElimination::SplitPHIEdges(MachineFunction &MF,