Fix an issue where the two-address conversion pass incorrectly rewrites untied

[oota-llvm.git] / lib / CodeGen / MachineBasicBlock.cpp

diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index 36963875f9e40f26c21ae4e7072afaeea48d7f64..68946a2c9d13c60245aa89e76401e212729573f0 100644 (file)
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -155,22 +155,12 @@ MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
 }
 
 MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
-  iterator B = begin(), I = end();
-  iterator Term = I;
-  while (I != B) {
-    --I;
-    // Ignore any debug values after the first terminator.
-    if (I->isDebugValue())
-      continue;
-    // Stop once we see a non-debug non-terminator.
-    if (!I->getDesc().isTerminator())
-      break;
-    // Earliest terminator so far.
-    Term = I;
-  }
-  // Return the first terminator, or end().
-  // Everything after Term is terminators and debug values.
-  return Term;
+  iterator I = end();
+  while (I != begin() && ((--I)->getDesc().isTerminator() || I->isDebugValue()))
+    ; /*noop */
+  while (I != end() && !I->getDesc().isTerminator())
+    ++I;
+  return I;
 }
 
 MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
@@ -185,6 +175,16 @@ MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
   return end();
 }
 
+const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
+  // A block with a landing pad successor only has one other successor.
+  if (succ_size() > 2)
+    return 0;
+  for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
+    if ((*I)->isLandingPad())
+      return *I;
+  return 0;
+}
+
 void MachineBasicBlock::dump() const {
   print(dbgs());
 }
@@ -363,8 +363,7 @@ void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
 }
 
 void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
-  std::vector<MachineBasicBlock *>::iterator I =
-    std::find(Predecessors.begin(), Predecessors.end(), pred);
+  pred_iterator I = std::find(Predecessors.begin(), Predecessors.end(), pred);
   assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
   Predecessors.erase(I);
 }
@@ -402,8 +401,7 @@ MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) {
 }
 
 bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
-  std::vector<MachineBasicBlock *>::const_iterator I =
-    std::find(Successors.begin(), Successors.end(), MBB);
+  const_succ_iterator I = std::find(Successors.begin(), Successors.end(), MBB);
   return I != Successors.end();
 }
 
@@ -487,6 +485,30 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
         << " -- BB#" << NMBB->getNumber()
         << " -- BB#" << Succ->getNumber() << '\n');
 
+  // On some targets like Mips, branches may kill virtual registers. Make sure
+  // that LiveVariables is properly updated after updateTerminator replaces the
+  // terminators.
+  LiveVariables *LV = P->getAnalysisIfAvailable<LiveVariables>();
+
+  // Collect a list of virtual registers killed by the terminators.
+  SmallVector<unsigned, 4> KilledRegs;
+  if (LV)
+    for (iterator I = getFirstTerminator(), E = end(); I != E; ++I) {
+      MachineInstr *MI = I;
+      for (MachineInstr::mop_iterator OI = MI->operands_begin(),
+           OE = MI->operands_end(); OI != OE; ++OI) {
+        if (!OI->isReg() || !OI->isUse() || !OI->isKill() || OI->isUndef())
+          continue;
+        unsigned Reg = OI->getReg();
+        if (TargetRegisterInfo::isVirtualRegister(Reg) &&
+            LV->getVarInfo(Reg).removeKill(MI)) {
+          KilledRegs.push_back(Reg);
+          DEBUG(dbgs() << "Removing terminator kill: " << *MI);
+          OI->setIsKill(false);
+        }
+      }
+    }
+
   ReplaceUsesOfBlockWith(Succ, NMBB);
   updateTerminator();
 
@@ -504,9 +526,22 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
       if (i->getOperand(ni+1).getMBB() == this)
         i->getOperand(ni+1).setMBB(NMBB);
 
-  if (LiveVariables *LV =
-        P->getAnalysisIfAvailable<LiveVariables>())
+  // Update LiveVariables.
+  if (LV) {
+    // Restore kills of virtual registers that were killed by the terminators.
+    while (!KilledRegs.empty()) {
+      unsigned Reg = KilledRegs.pop_back_val();
+      for (iterator I = end(), E = begin(); I != E;) {
+        if (!(--I)->addRegisterKilled(Reg, NULL, /* addIfNotFound= */ false))
+          continue;
+        LV->getVarInfo(Reg).Kills.push_back(I);
+        DEBUG(dbgs() << "Restored terminator kill: " << *I);
+        break;
+      }
+    }
+    // Update relevant live-through information.
     LV->addNewBlock(NMBB, this, Succ);
+  }
 
   if (MachineDominatorTree *MDT =
       P->getAnalysisIfAvailable<MachineDominatorTree>()) {