X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FMachineBasicBlock.cpp;h=f361d1ac29350ba6e684ada015ee5e28279fdc62;hb=913ff09a9acf563ae9719ff223bc117dd66ad6b0;hp=b3eb2da762812c4911b6f98a3378fe362385978a;hpb=cf143a4d917699f8f4202f331fa9e184070471fb;p=oota-llvm.git

diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index b3eb2da7628..f361d1ac293 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -13,18 +13,29 @@
 
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/BasicBlock.h"
+#include "llvm/CodeGen/LiveVariables.h"
+#include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/SlotIndexes.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetData.h"
-#include "llvm/Target/TargetInstrDesc.h"
+#include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Assembly/Writer.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/LeakDetector.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 using namespace llvm;
 
 MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb)
-  : BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false) {
+  : BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false),
+    AddressTaken(false) {
   Insts.Parent = this;
 }
 
@@ -32,12 +43,24 @@ MachineBasicBlock::~MachineBasicBlock() {
   LeakDetector::removeGarbageObject(this);
 }
 
+/// getSymbol - Return the MCSymbol for this basic block.
+///
+MCSymbol *MachineBasicBlock::getSymbol() const {
+  const MachineFunction *MF = getParent();
+  MCContext &Ctx = MF->getContext();
+  const char *Prefix = Ctx.getAsmInfo().getPrivateGlobalPrefix();
+  return Ctx.GetOrCreateSymbol(Twine(Prefix) + "BB" +
+                               Twine(MF->getFunctionNumber()) + "_" +
+                               Twine(getNumber()));
+}
+
+
 raw_ostream &llvm::operator<<(raw_ostream &OS, const MachineBasicBlock &MBB) {
   MBB.print(OS);
   return OS;
 }
 
-/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the 
+/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the
 /// parent pointer of the MBB, the MBB numbering, and any instructions in the
 /// MBB to be on the right operand list for registers.
 ///
@@ -50,7 +73,8 @@ void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock *N) {
 
   // Make sure the instructions have their operands in the reginfo lists.
   MachineRegisterInfo &RegInfo = MF.getRegInfo();
-  for (MachineBasicBlock::iterator I = N->begin(), E = N->end(); I != E; ++I)
+  for (MachineBasicBlock::instr_iterator
+         I = N->instr_begin(), E = N->instr_end(); I != E; ++I)
     I->AddRegOperandsToUseLists(RegInfo);
 
   LeakDetector::removeGarbageObject(N);
@@ -69,7 +93,7 @@ void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock *N) {
 void ilist_traits<MachineInstr>::addNodeToList(MachineInstr *N) {
   assert(N->getParent() == 0 && "machine instruction already in a basic block");
   N->setParent(Parent);
-  
+
   // Add the instruction's register operands to their corresponding
   // use/def lists.
   MachineFunction *MF = Parent->getParent();
@@ -86,7 +110,7 @@ void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr *N) {
 
   // Remove from the use/def lists.
   N->RemoveRegOperandsFromUseLists();
-  
+
   N->setParent(0);
 
   LeakDetector::addGarbageObject(N);
@@ -97,8 +121,8 @@ void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr *N) {
 /// lists.
 void ilist_traits<MachineInstr>::
 transferNodesFromList(ilist_traits<MachineInstr> &fromList,
-                      MachineBasicBlock::iterator first,
-                      MachineBasicBlock::iterator last) {
+                      ilist_iterator<MachineInstr> first,
+                      ilist_iterator<MachineInstr> last) {
   assert(Parent->getParent() == fromList.Parent->getParent() &&
         "MachineInstr parent mismatch!");
 
@@ -116,60 +140,117 @@ void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) {
   Parent->getParent()->DeleteMachineInstr(MI);
 }
 
+MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() {
+  instr_iterator I = instr_begin(), E = instr_end();
+  while (I != E && I->isPHI())
+    ++I;
+  assert(!I->isInsideBundle() && "First non-phi MI cannot be inside a bundle!");
+  return I;
+}
+
+MachineBasicBlock::iterator
+MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
+  iterator E = end();
+  while (I != E && (I->isPHI() || I->isLabel() || I->isDebugValue()))
+    ++I;
+  // FIXME: This needs to change if we wish to bundle labels / dbg_values
+  // inside the bundle.
+  assert(!I->isInsideBundle() &&
+         "First non-phi / non-label instruction is inside a bundle!");
+  return I;
+}
+
 MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
-  iterator I = end();
-  while (I != begin() && (--I)->getDesc().isTerminator())
+  iterator B = begin(), E = end(), I = E;
+  while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
     ; /*noop */
-  if (I != end() && !I->getDesc().isTerminator()) ++I;
+  while (I != E && !I->isTerminator())
+    ++I;
   return I;
 }
 
-/// isOnlyReachableViaFallthough - Return true if this basic block has
-/// exactly one predecessor and the control transfer mechanism between
-/// the predecessor and this block is a fall-through.
-bool MachineBasicBlock::isOnlyReachableByFallthrough() const {
-  // If this is a landing pad, it isn't a fall through.  If it has no preds,
-  // then nothing falls through to it.
-  if (isLandingPad() || pred_empty())
-    return false;
-  
-  // If there isn't exactly one predecessor, it can't be a fall through.
-  const_pred_iterator PI = pred_begin(), PI2 = PI;
-  ++PI2;
-  if (PI2 != pred_end())
-    return false;
-  
-  // The predecessor has to be immediately before this block.
-  const MachineBasicBlock *Pred = *PI;
-  
-  if (!Pred->isLayoutSuccessor(this))
-    return false;
-  
-  // If the block is completely empty, then it definitely does fall through.
-  if (Pred->empty())
-    return true;
-  
-  // Otherwise, check the last instruction.
-  const MachineInstr &LastInst = Pred->back();
-  return !LastInst.getDesc().isBarrier();
+MachineBasicBlock::const_iterator
+MachineBasicBlock::getFirstTerminator() const {
+  const_iterator B = begin(), E = end(), I = E;
+  while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
+    ; /*noop */
+  while (I != E && !I->isTerminator())
+    ++I;
+  return I;
+}
+
+MachineBasicBlock::instr_iterator MachineBasicBlock::getFirstInstrTerminator() {
+  instr_iterator B = instr_begin(), E = instr_end(), I = E;
+  while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
+    ; /*noop */
+  while (I != E && !I->isTerminator())
+    ++I;
+  return I;
+}
+
+MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
+  // Skip over end-of-block dbg_value instructions.
+  instr_iterator B = instr_begin(), I = instr_end();
+  while (I != B) {
+    --I;
+    // Return instruction that starts a bundle.
+    if (I->isDebugValue() || I->isInsideBundle())
+      continue;
+    return I;
+  }
+  // The block is all debug values.
+  return end();
+}
+
+MachineBasicBlock::const_iterator
+MachineBasicBlock::getLastNonDebugInstr() const {
+  // Skip over end-of-block dbg_value instructions.
+  const_instr_iterator B = instr_begin(), I = instr_end();
+  while (I != B) {
+    --I;
+    // Return instruction that starts a bundle.
+    if (I->isDebugValue() || I->isInsideBundle())
+      continue;
+    return I;
+  }
+  // The block is all debug values.
+  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(errs());
+  print(dbgs());
 }
 
-static inline void OutputReg(raw_ostream &os, unsigned RegNo,
-                             const TargetRegisterInfo *TRI = 0) {
-  if (!RegNo || TargetRegisterInfo::isPhysicalRegister(RegNo)) {
-    if (TRI)
-      os << " %" << TRI->get(RegNo).Name;
-    else
-      os << " %mreg(" << RegNo << ")";
-  } else
-    os << " %reg" << RegNo;
+StringRef MachineBasicBlock::getName() const {
+  if (const BasicBlock *LBB = getBasicBlock())
+    return LBB->getName();
+  else
+    return "(null)";
 }
 
-void MachineBasicBlock::print(raw_ostream &OS) const {
+/// Return a hopefully unique identifier for this block.
+std::string MachineBasicBlock::getFullName() const {
+  std::string Name;
+  if (getParent())
+    Name = (getParent()->getFunction()->getName() + ":").str();
+  if (getBasicBlock())
+    Name += getBasicBlock()->getName();
+  else
+    Name += (Twine("BB") + Twine(getNumber())).str();
+  return Name;
+}
+
+void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const {
   const MachineFunction *MF = getParent();
   if (!MF) {
     OS << "Can't print out MachineBasicBlock because parent MachineFunction"
@@ -177,52 +258,73 @@ void MachineBasicBlock::print(raw_ostream &OS) const {
     return;
   }
 
-  const BasicBlock *LBB = getBasicBlock();
+  if (Indexes)
+    OS << Indexes->getMBBStartIdx(this) << '\t';
+
+  OS << "BB#" << getNumber() << ": ";
+
+  const char *Comma = "";
+  if (const BasicBlock *LBB = getBasicBlock()) {
+    OS << Comma << "derived from LLVM BB ";
+    WriteAsOperand(OS, LBB, /*PrintType=*/false);
+    Comma = ", ";
+  }
+  if (isLandingPad()) { OS << Comma << "EH LANDING PAD"; Comma = ", "; }
+  if (hasAddressTaken()) { OS << Comma << "ADDRESS TAKEN"; Comma = ", "; }
+  if (Alignment)
+    OS << Comma << "Align " << Alignment << " (" << (1u << Alignment)
+       << " bytes)";
+
   OS << '\n';
-  if (LBB) OS << LBB->getName() << ": ";
-  OS << (const void*)this
-     << ", LLVM BB @" << (const void*) LBB << ", ID#" << getNumber();
-  if (Alignment) OS << ", Alignment " << Alignment;
-  if (isLandingPad()) OS << ", EH LANDING PAD";
-  OS << ":\n";
-
-  const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();  
+
+  const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
   if (!livein_empty()) {
-    OS << "Live Ins:";
-    for (const_livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
-      OutputReg(OS, *I, TRI);
+    if (Indexes) OS << '\t';
+    OS << "    Live Ins:";
+    for (livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
+      OS << ' ' << PrintReg(*I, TRI);
     OS << '\n';
   }
   // Print the preds of this block according to the CFG.
   if (!pred_empty()) {
+    if (Indexes) OS << '\t';
     OS << "    Predecessors according to CFG:";
     for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
-      OS << ' ' << *PI << " (#" << (*PI)->getNumber() << ')';
+      OS << " BB#" << (*PI)->getNumber();
     OS << '\n';
   }
-  
-  for (const_iterator I = begin(); I != end(); ++I) {
+
+  for (const_instr_iterator I = instr_begin(); I != instr_end(); ++I) {
+    if (Indexes) {
+      if (Indexes->hasIndex(I))
+        OS << Indexes->getInstructionIndex(I);
+      OS << '\t';
+    }
     OS << '\t';
+    if (I->isInsideBundle())
+      OS << "  * ";
     I->print(OS, &getParent()->getTarget());
   }
 
   // Print the successors of this block according to the CFG.
   if (!succ_empty()) {
+    if (Indexes) OS << '\t';
     OS << "    Successors according to CFG:";
     for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI)
-      OS << ' ' << *SI << " (#" << (*SI)->getNumber() << ')';
+      OS << " BB#" << (*SI)->getNumber();
     OS << '\n';
   }
 }
 
 void MachineBasicBlock::removeLiveIn(unsigned Reg) {
-  livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
-  assert(I != livein_end() && "Not a live in!");
-  LiveIns.erase(I);
+  std::vector<unsigned>::iterator I =
+    std::find(LiveIns.begin(), LiveIns.end(), Reg);
+  if (I != LiveIns.end())
+    LiveIns.erase(I);
 }
 
 bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
-  const_livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
+  livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
   return I != livein_end();
 }
 
@@ -235,33 +337,166 @@ void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
   getParent()->splice(++BBI, this);
 }
 
-
-void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) {
-  Successors.push_back(succ);
-  succ->addPredecessor(this);
+void MachineBasicBlock::updateTerminator() {
+  const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
+  // A block with no successors has no concerns with fall-through edges.
+  if (this->succ_empty()) return;
+
+  MachineBasicBlock *TBB = 0, *FBB = 0;
+  SmallVector<MachineOperand, 4> Cond;
+  DebugLoc dl;  // FIXME: this is nowhere
+  bool B = TII->AnalyzeBranch(*this, TBB, FBB, Cond);
+  (void) B;
+  assert(!B && "UpdateTerminators requires analyzable predecessors!");
+  if (Cond.empty()) {
+    if (TBB) {
+      // The block has an unconditional branch. If its successor is now
+      // its layout successor, delete the branch.
+      if (isLayoutSuccessor(TBB))
+        TII->RemoveBranch(*this);
+    } else {
+      // The block has an unconditional fallthrough. If its successor is not
+      // its layout successor, insert a branch. First we have to locate the
+      // only non-landing-pad successor, as that is the fallthrough block.
+      for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
+        if ((*SI)->isLandingPad())
+          continue;
+        assert(!TBB && "Found more than one non-landing-pad successor!");
+        TBB = *SI;
+      }
+
+      // If there is no non-landing-pad successor, the block has no
+      // fall-through edges to be concerned with.
+      if (!TBB)
+        return;
+
+      // Finally update the unconditional successor to be reached via a branch
+      // if it would not be reached by fallthrough.
+      if (!isLayoutSuccessor(TBB))
+        TII->InsertBranch(*this, TBB, 0, Cond, dl);
+    }
+  } else {
+    if (FBB) {
+      // The block has a non-fallthrough conditional branch. If one of its
+      // successors is its layout successor, rewrite it to a fallthrough
+      // conditional branch.
+      if (isLayoutSuccessor(TBB)) {
+        if (TII->ReverseBranchCondition(Cond))
+          return;
+        TII->RemoveBranch(*this);
+        TII->InsertBranch(*this, FBB, 0, Cond, dl);
+      } else if (isLayoutSuccessor(FBB)) {
+        TII->RemoveBranch(*this);
+        TII->InsertBranch(*this, TBB, 0, Cond, dl);
+      }
+    } else {
+      // Walk through the successors and find the successor which is not
+      // a landing pad and is not the conditional branch destination (in TBB)
+      // as the fallthrough successor.
+      MachineBasicBlock *FallthroughBB = 0;
+      for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
+        if ((*SI)->isLandingPad() || *SI == TBB)
+          continue;
+        assert(!FallthroughBB && "Found more than one fallthrough successor.");
+        FallthroughBB = *SI;
+      }
+      if (!FallthroughBB && canFallThrough()) {
+        // We fallthrough to the same basic block as the conditional jump
+        // targets. Remove the conditional jump, leaving unconditional
+        // fallthrough.
+        // FIXME: This does not seem like a reasonable pattern to support, but it
+        // has been seen in the wild coming out of degenerate ARM test cases.
+        TII->RemoveBranch(*this);
+
+        // Finally update the unconditional successor to be reached via a branch
+        // if it would not be reached by fallthrough.
+        if (!isLayoutSuccessor(TBB))
+          TII->InsertBranch(*this, TBB, 0, Cond, dl);
+        return;
+      }
+
+      // The block has a fallthrough conditional branch.
+      if (isLayoutSuccessor(TBB)) {
+        if (TII->ReverseBranchCondition(Cond)) {
+          // We can't reverse the condition, add an unconditional branch.
+          Cond.clear();
+          TII->InsertBranch(*this, FallthroughBB, 0, Cond, dl);
+          return;
+        }
+        TII->RemoveBranch(*this);
+        TII->InsertBranch(*this, FallthroughBB, 0, Cond, dl);
+      } else if (!isLayoutSuccessor(FallthroughBB)) {
+        TII->RemoveBranch(*this);
+        TII->InsertBranch(*this, TBB, FallthroughBB, Cond, dl);
+      }
+    }
+  }
 }
 
+void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ, uint32_t weight) {
+
+  // If we see non-zero value for the first time it means we actually use Weight
+  // list, so we fill all Weights with 0's.
+  if (weight != 0 && Weights.empty())
+    Weights.resize(Successors.size());
+
+  if (weight != 0 || !Weights.empty())
+    Weights.push_back(weight);
+
+   Successors.push_back(succ);
+   succ->addPredecessor(this);
+ }
+
 void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
   succ->removePredecessor(this);
   succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
   assert(I != Successors.end() && "Not a current successor!");
+
+  // If Weight list is empty it means we don't use it (disabled optimization).
+  if (!Weights.empty()) {
+    weight_iterator WI = getWeightIterator(I);
+    Weights.erase(WI);
+  }
+
   Successors.erase(I);
 }
 
-MachineBasicBlock::succ_iterator 
+MachineBasicBlock::succ_iterator
 MachineBasicBlock::removeSuccessor(succ_iterator I) {
   assert(I != Successors.end() && "Not a current successor!");
+
+  // If Weight list is empty it means we don't use it (disabled optimization).
+  if (!Weights.empty()) {
+    weight_iterator WI = getWeightIterator(I);
+    Weights.erase(WI);
+  }
+
   (*I)->removePredecessor(this);
   return Successors.erase(I);
 }
 
+void MachineBasicBlock::replaceSuccessor(MachineBasicBlock *Old,
+                                         MachineBasicBlock *New) {
+  uint32_t weight = 0;
+  succ_iterator SI = std::find(Successors.begin(), Successors.end(), Old);
+
+  // If Weight list is empty it means we don't use it (disabled optimization).
+  if (!Weights.empty()) {
+    weight_iterator WI = getWeightIterator(SI);
+    weight = *WI;
+  }
+
+  // Update the successor information.
+  removeSuccessor(SI);
+  addSuccessor(New, weight);
+}
+
 void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
   Predecessors.push_back(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);
 }
@@ -269,24 +504,291 @@ void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
 void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) {
   if (this == fromMBB)
     return;
-  
-  for (MachineBasicBlock::succ_iterator I = fromMBB->succ_begin(), 
-       E = fromMBB->succ_end(); I != E; ++I)
-    addSuccessor(*I);
-  
-  while (!fromMBB->succ_empty())
-    fromMBB->removeSuccessor(fromMBB->succ_begin());
+
+  while (!fromMBB->succ_empty()) {
+    MachineBasicBlock *Succ = *fromMBB->succ_begin();
+    uint32_t weight = 0;
+
+
+    // If Weight list is empty it means we don't use it (disabled optimization).
+    if (!fromMBB->Weights.empty())
+      weight = *fromMBB->Weights.begin();
+
+    addSuccessor(Succ, weight);
+    fromMBB->removeSuccessor(Succ);
+  }
+}
+
+void
+MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) {
+  if (this == fromMBB)
+    return;
+
+  while (!fromMBB->succ_empty()) {
+    MachineBasicBlock *Succ = *fromMBB->succ_begin();
+    addSuccessor(Succ);
+    fromMBB->removeSuccessor(Succ);
+
+    // Fix up any PHI nodes in the successor.
+    for (MachineBasicBlock::instr_iterator MI = Succ->instr_begin(),
+           ME = Succ->instr_end(); MI != ME && MI->isPHI(); ++MI)
+      for (unsigned i = 2, e = MI->getNumOperands()+1; i != e; i += 2) {
+        MachineOperand &MO = MI->getOperand(i);
+        if (MO.getMBB() == fromMBB)
+          MO.setMBB(this);
+      }
+  }
+}
+
+bool MachineBasicBlock::isPredecessor(const MachineBasicBlock *MBB) const {
+  return std::find(pred_begin(), pred_end(), MBB) != pred_end();
 }
 
 bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
-  std::vector<MachineBasicBlock *>::const_iterator I =
-    std::find(Successors.begin(), Successors.end(), MBB);
-  return I != Successors.end();
+  return std::find(succ_begin(), succ_end(), MBB) != succ_end();
 }
 
 bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
   MachineFunction::const_iterator I(this);
-  return next(I) == MachineFunction::const_iterator(MBB);
+  return llvm::next(I) == MachineFunction::const_iterator(MBB);
+}
+
+bool MachineBasicBlock::canFallThrough() {
+  MachineFunction::iterator Fallthrough = this;
+  ++Fallthrough;
+  // If FallthroughBlock is off the end of the function, it can't fall through.
+  if (Fallthrough == getParent()->end())
+    return false;
+
+  // If FallthroughBlock isn't a successor, no fallthrough is possible.
+  if (!isSuccessor(Fallthrough))
+    return false;
+
+  // Analyze the branches, if any, at the end of the block.
+  MachineBasicBlock *TBB = 0, *FBB = 0;
+  SmallVector<MachineOperand, 4> Cond;
+  const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
+  if (TII->AnalyzeBranch(*this, TBB, FBB, Cond)) {
+    // If we couldn't analyze the branch, examine the last instruction.
+    // If the block doesn't end in a known control barrier, assume fallthrough
+    // is possible. The isPredicated check is needed because this code can be
+    // called during IfConversion, where an instruction which is normally a
+    // Barrier is predicated and thus no longer an actual control barrier.
+    return empty() || !back().isBarrier() || TII->isPredicated(&back());
+  }
+
+  // If there is no branch, control always falls through.
+  if (TBB == 0) return true;
+
+  // If there is some explicit branch to the fallthrough block, it can obviously
+  // reach, even though the branch should get folded to fall through implicitly.
+  if (MachineFunction::iterator(TBB) == Fallthrough ||
+      MachineFunction::iterator(FBB) == Fallthrough)
+    return true;
+
+  // If it's an unconditional branch to some block not the fall through, it
+  // doesn't fall through.
+  if (Cond.empty()) return false;
+
+  // Otherwise, if it is conditional and has no explicit false block, it falls
+  // through.
+  return FBB == 0;
+}
+
+MachineBasicBlock *
+MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
+  // Splitting the critical edge to a landing pad block is non-trivial. Don't do
+  // it in this generic function.
+  if (Succ->isLandingPad())
+    return NULL;
+
+  MachineFunction *MF = getParent();
+  DebugLoc dl;  // FIXME: this is nowhere
+
+  // We may need to update this's terminator, but we can't do that if
+  // AnalyzeBranch fails. If this uses a jump table, we won't touch it.
+  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
+  MachineBasicBlock *TBB = 0, *FBB = 0;
+  SmallVector<MachineOperand, 4> Cond;
+  if (TII->AnalyzeBranch(*this, TBB, FBB, Cond))
+    return NULL;
+
+  // Avoid bugpoint weirdness: A block may end with a conditional branch but
+  // jumps to the same MBB is either case. We have duplicate CFG edges in that
+  // case that we can't handle. Since this never happens in properly optimized
+  // code, just skip those edges.
+  if (TBB && TBB == FBB) {
+    DEBUG(dbgs() << "Won't split critical edge after degenerate BB#"
+                 << getNumber() << '\n');
+    return NULL;
+  }
+
+  MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock();
+  MF->insert(llvm::next(MachineFunction::iterator(this)), NMBB);
+  DEBUG(dbgs() << "Splitting critical edge:"
+        " BB#" << getNumber()
+        << " -- 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 (instr_iterator I = getFirstInstrTerminator(), E = instr_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->getReg() == 0 ||
+            !OI->isUse() || !OI->isKill() || OI->isUndef())
+          continue;
+        unsigned Reg = OI->getReg();
+        if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
+            LV->getVarInfo(Reg).removeKill(MI)) {
+          KilledRegs.push_back(Reg);
+          DEBUG(dbgs() << "Removing terminator kill: " << *MI);
+          OI->setIsKill(false);
+        }
+      }
+    }
+
+  ReplaceUsesOfBlockWith(Succ, NMBB);
+  updateTerminator();
+
+  // Insert unconditional "jump Succ" instruction in NMBB if necessary.
+  NMBB->addSuccessor(Succ);
+  if (!NMBB->isLayoutSuccessor(Succ)) {
+    Cond.clear();
+    MF->getTarget().getInstrInfo()->InsertBranch(*NMBB, Succ, NULL, Cond, dl);
+  }
+
+  // Fix PHI nodes in Succ so they refer to NMBB instead of this
+  for (MachineBasicBlock::instr_iterator
+         i = Succ->instr_begin(),e = Succ->instr_end();
+       i != e && i->isPHI(); ++i)
+    for (unsigned ni = 1, ne = i->getNumOperands(); ni != ne; ni += 2)
+      if (i->getOperand(ni+1).getMBB() == this)
+        i->getOperand(ni+1).setMBB(NMBB);
+
+  // Inherit live-ins from the successor
+  for (MachineBasicBlock::livein_iterator I = Succ->livein_begin(),
+         E = Succ->livein_end(); I != E; ++I)
+    NMBB->addLiveIn(*I);
+
+  // Update LiveVariables.
+  const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
+  if (LV) {
+    // Restore kills of virtual registers that were killed by the terminators.
+    while (!KilledRegs.empty()) {
+      unsigned Reg = KilledRegs.pop_back_val();
+      for (instr_iterator I = instr_end(), E = instr_begin(); I != E;) {
+        if (!(--I)->addRegisterKilled(Reg, TRI, /* addIfNotFound= */ false))
+          continue;
+        if (TargetRegisterInfo::isVirtualRegister(Reg))
+          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>()) {
+    // Update dominator information.
+    MachineDomTreeNode *SucccDTNode = MDT->getNode(Succ);
+
+    bool IsNewIDom = true;
+    for (const_pred_iterator PI = Succ->pred_begin(), E = Succ->pred_end();
+         PI != E; ++PI) {
+      MachineBasicBlock *PredBB = *PI;
+      if (PredBB == NMBB)
+        continue;
+      if (!MDT->dominates(SucccDTNode, MDT->getNode(PredBB))) {
+        IsNewIDom = false;
+        break;
+      }
+    }
+
+    // We know "this" dominates the newly created basic block.
+    MachineDomTreeNode *NewDTNode = MDT->addNewBlock(NMBB, this);
+
+    // If all the other predecessors of "Succ" are dominated by "Succ" itself
+    // then the new block is the new immediate dominator of "Succ". Otherwise,
+    // the new block doesn't dominate anything.
+    if (IsNewIDom)
+      MDT->changeImmediateDominator(SucccDTNode, NewDTNode);
+  }
+
+  if (MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>())
+    if (MachineLoop *TIL = MLI->getLoopFor(this)) {
+      // If one or the other blocks were not in a loop, the new block is not
+      // either, and thus LI doesn't need to be updated.
+      if (MachineLoop *DestLoop = MLI->getLoopFor(Succ)) {
+        if (TIL == DestLoop) {
+          // Both in the same loop, the NMBB joins loop.
+          DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase());
+        } else if (TIL->contains(DestLoop)) {
+          // Edge from an outer loop to an inner loop.  Add to the outer loop.
+          TIL->addBasicBlockToLoop(NMBB, MLI->getBase());
+        } else if (DestLoop->contains(TIL)) {
+          // Edge from an inner loop to an outer loop.  Add to the outer loop.
+          DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase());
+        } else {
+          // Edge from two loops with no containment relation.  Because these
+          // are natural loops, we know that the destination block must be the
+          // header of its loop (adding a branch into a loop elsewhere would
+          // create an irreducible loop).
+          assert(DestLoop->getHeader() == Succ &&
+                 "Should not create irreducible loops!");
+          if (MachineLoop *P = DestLoop->getParentLoop())
+            P->addBasicBlockToLoop(NMBB, MLI->getBase());
+        }
+      }
+    }
+
+  return NMBB;
+}
+
+MachineBasicBlock::iterator
+MachineBasicBlock::erase(MachineBasicBlock::iterator I) {
+  if (I->isBundle()) {
+    MachineBasicBlock::iterator E = llvm::next(I);
+    return Insts.erase(I.getInstrIterator(), E.getInstrIterator());
+  }
+
+  return Insts.erase(I.getInstrIterator());
+}
+
+MachineInstr *MachineBasicBlock::remove(MachineInstr *I) {
+  if (I->isBundle()) {
+    instr_iterator MII = llvm::next(I);
+    iterator E = end();
+    while (MII != E && MII->isInsideBundle()) {
+      MachineInstr *MI = &*MII++;
+      Insts.remove(MI);
+    }
+  }
+
+  return Insts.remove(I);
+}
+
+void MachineBasicBlock::splice(MachineBasicBlock::iterator where,
+                               MachineBasicBlock *Other,
+                               MachineBasicBlock::iterator From) {
+  if (From->isBundle()) {
+    MachineBasicBlock::iterator To = llvm::next(From);
+    Insts.splice(where.getInstrIterator(), Other->Insts,
+                 From.getInstrIterator(), To.getInstrIterator());
+    return;
+  }
+
+  Insts.splice(where.getInstrIterator(), Other->Insts, From.getInstrIterator());
 }
 
 /// removeFromParent - This method unlinks 'this' from the containing function,
@@ -312,10 +814,10 @@ void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
                                                MachineBasicBlock *New) {
   assert(Old != New && "Cannot replace self with self!");
 
-  MachineBasicBlock::iterator I = end();
-  while (I != begin()) {
+  MachineBasicBlock::instr_iterator I = instr_end();
+  while (I != instr_begin()) {
     --I;
-    if (!I->getDesc().isTerminator()) break;
+    if (!I->isTerminator()) break;
 
     // Scan the operands of this machine instruction, replacing any uses of Old
     // with New.
@@ -326,67 +828,120 @@ void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
   }
 
   // Update the successor information.
-  removeSuccessor(Old);
-  addSuccessor(New);
+  replaceSuccessor(Old, New);
 }
 
 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
 /// CFG to be inserted.  If we have proven that MBB can only branch to DestA and
-/// DestB, remove any other MBB successors from the CFG.  DestA and DestB can
-/// be null.
+/// DestB, remove any other MBB successors from the CFG.  DestA and DestB can be
+/// null.
+///
 /// Besides DestA and DestB, retain other edges leading to LandingPads
 /// (currently there can be only one; we don't check or require that here).
 /// Note it is possible that DestA and/or DestB are LandingPads.
 bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA,
                                              MachineBasicBlock *DestB,
                                              bool isCond) {
-  bool MadeChange = false;
-  bool AddedFallThrough = false;
-
-  MachineFunction::iterator FallThru = next(MachineFunction::iterator(this));
-  
-  // If this block ends with a conditional branch that falls through to its
-  // successor, set DestB as the successor.
-  if (isCond) {
-    if (DestB == 0 && FallThru != getParent()->end()) {
+  // The values of DestA and DestB frequently come from a call to the
+  // 'TargetInstrInfo::AnalyzeBranch' method. We take our meaning of the initial
+  // values from there.
+  //
+  // 1. If both DestA and DestB are null, then the block ends with no branches
+  //    (it falls through to its successor).
+  // 2. If DestA is set, DestB is null, and isCond is false, then the block ends
+  //    with only an unconditional branch.
+  // 3. If DestA is set, DestB is null, and isCond is true, then the block ends
+  //    with a conditional branch that falls through to a successor (DestB).
+  // 4. If DestA and DestB is set and isCond is true, then the block ends with a
+  //    conditional branch followed by an unconditional branch. DestA is the
+  //    'true' destination and DestB is the 'false' destination.
+
+  bool Changed = false;
+
+  MachineFunction::iterator FallThru =
+    llvm::next(MachineFunction::iterator(this));
+
+  if (DestA == 0 && DestB == 0) {
+    // Block falls through to successor.
+    DestA = FallThru;
+    DestB = FallThru;
+  } else if (DestA != 0 && DestB == 0) {
+    if (isCond)
+      // Block ends in conditional jump that falls through to successor.
       DestB = FallThru;
-      AddedFallThrough = true;
-    }
   } else {
-    // If this is an unconditional branch with no explicit dest, it must just be
-    // a fallthrough into DestB.
-    if (DestA == 0 && FallThru != getParent()->end()) {
-      DestA = FallThru;
-      AddedFallThrough = true;
-    }
+    assert(DestA && DestB && isCond &&
+           "CFG in a bad state. Cannot correct CFG edges");
   }
-  
+
+  // Remove superfluous edges. I.e., those which aren't destinations of this
+  // basic block, duplicate edges, or landing pads.
+  SmallPtrSet<const MachineBasicBlock*, 8> SeenMBBs;
   MachineBasicBlock::succ_iterator SI = succ_begin();
-  MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB;
   while (SI != succ_end()) {
-    if (*SI == DestA && DestA == DestB) {
-      DestA = DestB = 0;
-      ++SI;
-    } else if (*SI == DestA) {
-      DestA = 0;
-      ++SI;
-    } else if (*SI == DestB) {
-      DestB = 0;
-      ++SI;
-    } else if ((*SI)->isLandingPad() && 
-               *SI!=OrigDestA && *SI!=OrigDestB) {
-      ++SI;
-    } else {
-      // Otherwise, this is a superfluous edge, remove it.
+    const MachineBasicBlock *MBB = *SI;
+    if (!SeenMBBs.insert(MBB) ||
+        (MBB != DestA && MBB != DestB && !MBB->isLandingPad())) {
+      // This is a superfluous edge, remove it.
       SI = removeSuccessor(SI);
-      MadeChange = true;
+      Changed = true;
+    } else {
+      ++SI;
     }
   }
-  if (!AddedFallThrough) {
-    assert(DestA == 0 && DestB == 0 &&
-           "MachineCFG is missing edges!");
-  } else if (isCond) {
-    assert(DestA == 0 && "MachineCFG is missing edges!");
-  }
-  return MadeChange;
+
+  return Changed;
+}
+
+/// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
+/// any DBG_VALUE instructions.  Return UnknownLoc if there is none.
+DebugLoc
+MachineBasicBlock::findDebugLoc(instr_iterator MBBI) {
+  DebugLoc DL;
+  instr_iterator E = instr_end();
+  if (MBBI == E)
+    return DL;
+
+  // Skip debug declarations, we don't want a DebugLoc from them.
+  while (MBBI != E && MBBI->isDebugValue())
+    MBBI++;
+  if (MBBI != E)
+    DL = MBBI->getDebugLoc();
+  return DL;
+}
+
+/// getSuccWeight - Return weight of the edge from this block to MBB.
+///
+uint32_t MachineBasicBlock::getSuccWeight(const MachineBasicBlock *succ) const {
+  if (Weights.empty())
+    return 0;
+
+  const_succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
+  return *getWeightIterator(I);
 }
+
+/// getWeightIterator - Return wight iterator corresonding to the I successor
+/// iterator
+MachineBasicBlock::weight_iterator MachineBasicBlock::
+getWeightIterator(MachineBasicBlock::succ_iterator I) {
+  assert(Weights.size() == Successors.size() && "Async weight list!");
+  size_t index = std::distance(Successors.begin(), I);
+  assert(index < Weights.size() && "Not a current successor!");
+  return Weights.begin() + index;
+}
+
+/// getWeightIterator - Return wight iterator corresonding to the I successor
+/// iterator
+MachineBasicBlock::const_weight_iterator MachineBasicBlock::
+getWeightIterator(MachineBasicBlock::const_succ_iterator I) const {
+  assert(Weights.size() == Successors.size() && "Async weight list!");
+  const size_t index = std::distance(Successors.begin(), I);
+  assert(index < Weights.size() && "Not a current successor!");
+  return Weights.begin() + index;
+}
+
+void llvm::WriteAsOperand(raw_ostream &OS, const MachineBasicBlock *MBB,
+                          bool t) {
+  OS << "BB#" << MBB->getNumber();
+}
+