Update LLVM to 91430.

1 files changed, 393 insertions, 0 deletions

diff --git a/lib/CodeGen/MachineSSAUpdater.cpp b/lib/CodeGen/MachineSSAUpdater.cpp
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--- /dev/null
+++ b/lib/CodeGen/MachineSSAUpdater.cpp
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+//===- MachineSSAUpdater.cpp - Unstructured SSA Update Tool ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the MachineSSAUpdater class. It's based on SSAUpdater
+// class in lib/Transforms/Utils.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineSSAUpdater.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+typedef DenseMap<MachineBasicBlock*, unsigned> AvailableValsTy;
+typedef std::vector<std::pair<MachineBasicBlock*, unsigned> >
+                IncomingPredInfoTy;
+
+static AvailableValsTy &getAvailableVals(void *AV) {
+  return *static_cast<AvailableValsTy*>(AV);
+}
+
+static IncomingPredInfoTy &getIncomingPredInfo(void *IPI) {
+  return *static_cast<IncomingPredInfoTy*>(IPI);
+}
+
+
+MachineSSAUpdater::MachineSSAUpdater(MachineFunction &MF,
+                                     SmallVectorImpl<MachineInstr*> *NewPHI)
+  : AV(0), IPI(0), InsertedPHIs(NewPHI) {
+  TII = MF.getTarget().getInstrInfo();
+  MRI = &MF.getRegInfo();
+}
+
+MachineSSAUpdater::~MachineSSAUpdater() {
+  delete &getAvailableVals(AV);
+  delete &getIncomingPredInfo(IPI);
+}
+
+/// Initialize - Reset this object to get ready for a new set of SSA
+/// updates.  ProtoValue is the value used to name PHI nodes.
+void MachineSSAUpdater::Initialize(unsigned V) {
+  if (AV == 0)
+    AV = new AvailableValsTy();
+  else
+    getAvailableVals(AV).clear();
+
+  if (IPI == 0)
+    IPI = new IncomingPredInfoTy();
+  else
+    getIncomingPredInfo(IPI).clear();
+
+  VR = V;
+  VRC = MRI->getRegClass(VR);
+}
+
+/// HasValueForBlock - Return true if the MachineSSAUpdater already has a value for
+/// the specified block.
+bool MachineSSAUpdater::HasValueForBlock(MachineBasicBlock *BB) const {
+  return getAvailableVals(AV).count(BB);
+}
+
+/// AddAvailableValue - Indicate that a rewritten value is available in the
+/// specified block with the specified value.
+void MachineSSAUpdater::AddAvailableValue(MachineBasicBlock *BB, unsigned V) {
+  getAvailableVals(AV)[BB] = V;
+}
+
+/// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is
+/// live at the end of the specified block.
+unsigned MachineSSAUpdater::GetValueAtEndOfBlock(MachineBasicBlock *BB) {
+  return GetValueAtEndOfBlockInternal(BB);
+}
+
+static
+unsigned LookForIdenticalPHI(MachineBasicBlock *BB,
+          SmallVector<std::pair<MachineBasicBlock*, unsigned>, 8> &PredValues) {
+  if (BB->empty())
+    return 0;
+
+  MachineBasicBlock::iterator I = BB->front();
+  if (I->getOpcode() != TargetInstrInfo::PHI)
+    return 0;
+
+  AvailableValsTy AVals;
+  for (unsigned i = 0, e = PredValues.size(); i != e; ++i)
+    AVals[PredValues[i].first] = PredValues[i].second;
+  while (I != BB->end() && I->getOpcode() == TargetInstrInfo::PHI) {
+    bool Same = true;
+    for (unsigned i = 1, e = I->getNumOperands(); i != e; i += 2) {
+      unsigned SrcReg = I->getOperand(i).getReg();
+      MachineBasicBlock *SrcBB = I->getOperand(i+1).getMBB();
+      if (AVals[SrcBB] != SrcReg) {
+        Same = false;
+        break;
+      }
+    }
+    if (Same)
+      return I->getOperand(0).getReg();
+    ++I;
+  }
+  return 0;
+}
+
+/// InsertNewDef - Insert an empty PHI or IMPLICIT_DEF instruction which define
+/// a value of the given register class at the start of the specified basic
+/// block. It returns the virtual register defined by the instruction.
+static
+MachineInstr *InsertNewDef(unsigned Opcode,
+                           MachineBasicBlock *BB, MachineBasicBlock::iterator I,
+                           const TargetRegisterClass *RC,
+                           MachineRegisterInfo *MRI, const TargetInstrInfo *TII) {
+  unsigned NewVR = MRI->createVirtualRegister(RC);
+  return BuildMI(*BB, I, DebugLoc::getUnknownLoc(), TII->get(Opcode), NewVR);
+}
+                          
+/// GetValueInMiddleOfBlock - Construct SSA form, materializing a value that
+/// is live in the middle of the specified block.
+///
+/// GetValueInMiddleOfBlock is the same as GetValueAtEndOfBlock except in one
+/// important case: if there is a definition of the rewritten value after the
+/// 'use' in BB.  Consider code like this:
+///
+///      X1 = ...
+///   SomeBB:
+///      use(X)
+///      X2 = ...
+///      br Cond, SomeBB, OutBB
+///
+/// In this case, there are two values (X1 and X2) added to the AvailableVals
+/// set by the client of the rewriter, and those values are both live out of
+/// their respective blocks.  However, the use of X happens in the *middle* of
+/// a block.  Because of this, we need to insert a new PHI node in SomeBB to
+/// merge the appropriate values, and this value isn't live out of the block.
+///
+unsigned MachineSSAUpdater::GetValueInMiddleOfBlock(MachineBasicBlock *BB) {
+  // If there is no definition of the renamed variable in this block, just use
+  // GetValueAtEndOfBlock to do our work.
+  if (!getAvailableVals(AV).count(BB))
+    return GetValueAtEndOfBlockInternal(BB);
+
+  // If there are no predecessors, just return undef.
+  if (BB->pred_empty()) {
+    // Insert an implicit_def to represent an undef value.
+    MachineInstr *NewDef = InsertNewDef(TargetInstrInfo::IMPLICIT_DEF,
+                                        BB, BB->getFirstTerminator(),
+                                        VRC, MRI, TII);
+    return NewDef->getOperand(0).getReg();
+  }
+
+  // Otherwise, we have the hard case.  Get the live-in values for each
+  // predecessor.
+  SmallVector<std::pair<MachineBasicBlock*, unsigned>, 8> PredValues;
+  unsigned SingularValue = 0;
+
+  bool isFirstPred = true;
+  for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
+         E = BB->pred_end(); PI != E; ++PI) {
+    MachineBasicBlock *PredBB = *PI;
+    unsigned PredVal = GetValueAtEndOfBlockInternal(PredBB);
+    PredValues.push_back(std::make_pair(PredBB, PredVal));
+
+    // Compute SingularValue.
+    if (isFirstPred) {
+      SingularValue = PredVal;
+      isFirstPred = false;
+    } else if (PredVal != SingularValue)
+      SingularValue = 0;
+  }
+
+  // Otherwise, if all the merged values are the same, just use it.
+  if (SingularValue != 0)
+    return SingularValue;
+
+  // If an identical PHI is already in BB, just reuse it.
+  unsigned DupPHI = LookForIdenticalPHI(BB, PredValues);
+  if (DupPHI)
+    return DupPHI;
+
+  // Otherwise, we do need a PHI: insert one now.
+  MachineBasicBlock::iterator Loc = BB->empty() ? BB->end() : BB->front();
+  MachineInstr *InsertedPHI = InsertNewDef(TargetInstrInfo::PHI, BB,
+                                           Loc, VRC, MRI, TII);
+
+  // Fill in all the predecessors of the PHI.
+  MachineInstrBuilder MIB(InsertedPHI);
+  for (unsigned i = 0, e = PredValues.size(); i != e; ++i)
+    MIB.addReg(PredValues[i].second).addMBB(PredValues[i].first);
+
+  // See if the PHI node can be merged to a single value.  This can happen in
+  // loop cases when we get a PHI of itself and one other value.
+  if (unsigned ConstVal = InsertedPHI->isConstantValuePHI()) {
+    InsertedPHI->eraseFromParent();
+    return ConstVal;
+  }
+
+  // If the client wants to know about all new instructions, tell it.
+  if (InsertedPHIs) InsertedPHIs->push_back(InsertedPHI);
+
+  DEBUG(errs() << "  Inserted PHI: " << *InsertedPHI << "\n");
+  return InsertedPHI->getOperand(0).getReg();
+}
+
+static
+MachineBasicBlock *findCorrespondingPred(const MachineInstr *MI,
+                                         MachineOperand *U) {
+  for (unsigned i = 1, e = MI->getNumOperands(); i != e; i += 2) {
+    if (&MI->getOperand(i) == U)
+      return MI->getOperand(i+1).getMBB();
+  }
+
+  llvm_unreachable("MachineOperand::getParent() failure?");
+  return 0;
+}
+
+/// RewriteUse - Rewrite a use of the symbolic value.  This handles PHI nodes,
+/// which use their value in the corresponding predecessor.
+void MachineSSAUpdater::RewriteUse(MachineOperand &U) {
+  MachineInstr *UseMI = U.getParent();
+  unsigned NewVR = 0;
+  if (UseMI->getOpcode() == TargetInstrInfo::PHI) {
+    MachineBasicBlock *SourceBB = findCorrespondingPred(UseMI, &U);
+    NewVR = GetValueAtEndOfBlockInternal(SourceBB);
+  } else {
+    NewVR = GetValueInMiddleOfBlock(UseMI->getParent());
+  }
+
+  U.setReg(NewVR);
+}
+
+void MachineSSAUpdater::ReplaceRegWith(unsigned OldReg, unsigned NewReg) {
+  MRI->replaceRegWith(OldReg, NewReg);
+
+  AvailableValsTy &AvailableVals = getAvailableVals(AV);
+  for (DenseMap<MachineBasicBlock*, unsigned>::iterator
+         I = AvailableVals.begin(), E = AvailableVals.end(); I != E; ++I)
+    if (I->second == OldReg)
+      I->second = NewReg;
+}
+
+/// GetValueAtEndOfBlockInternal - Check to see if AvailableVals has an entry
+/// for the specified BB and if so, return it.  If not, construct SSA form by
+/// walking predecessors inserting PHI nodes as needed until we get to a block
+/// where the value is available.
+///
+unsigned MachineSSAUpdater::GetValueAtEndOfBlockInternal(MachineBasicBlock *BB){
+  AvailableValsTy &AvailableVals = getAvailableVals(AV);
+
+  // Query AvailableVals by doing an insertion of null.
+  std::pair<AvailableValsTy::iterator, bool> InsertRes =
+    AvailableVals.insert(std::make_pair(BB, 0));
+
+  // Handle the case when the insertion fails because we have already seen BB.
+  if (!InsertRes.second) {
+    // If the insertion failed, there are two cases.  The first case is that the
+    // value is already available for the specified block.  If we get this, just
+    // return the value.
+    if (InsertRes.first->second != 0)
+      return InsertRes.first->second;
+
+    // Otherwise, if the value we find is null, then this is the value is not
+    // known but it is being computed elsewhere in our recursion.  This means
+    // that we have a cycle.  Handle this by inserting a PHI node and returning
+    // it.  When we get back to the first instance of the recursion we will fill
+    // in the PHI node.
+    MachineBasicBlock::iterator Loc = BB->empty() ? BB->end() : BB->front();
+    MachineInstr *NewPHI = InsertNewDef(TargetInstrInfo::PHI, BB, Loc,
+                                        VRC, MRI,TII);
+    unsigned NewVR = NewPHI->getOperand(0).getReg();
+    InsertRes.first->second = NewVR;
+    return NewVR;
+  }
+
+  // If there are no predecessors, then we must have found an unreachable block
+  // just return 'undef'.  Since there are no predecessors, InsertRes must not
+  // be invalidated.
+  if (BB->pred_empty()) {
+    // Insert an implicit_def to represent an undef value.
+    MachineInstr *NewDef = InsertNewDef(TargetInstrInfo::IMPLICIT_DEF,
+                                        BB, BB->getFirstTerminator(),
+                                        VRC, MRI, TII);
+    return InsertRes.first->second = NewDef->getOperand(0).getReg();
+  }
+
+  // Okay, the value isn't in the map and we just inserted a null in the entry
+  // to indicate that we're processing the block.  Since we have no idea what
+  // value is in this block, we have to recurse through our predecessors.
+  //
+  // While we're walking our predecessors, we keep track of them in a vector,
+  // then insert a PHI node in the end if we actually need one.  We could use a
+  // smallvector here, but that would take a lot of stack space for every level
+  // of the recursion, just use IncomingPredInfo as an explicit stack.
+  IncomingPredInfoTy &IncomingPredInfo = getIncomingPredInfo(IPI);
+  unsigned FirstPredInfoEntry = IncomingPredInfo.size();
+
+  // As we're walking the predecessors, keep track of whether they are all
+  // producing the same value.  If so, this value will capture it, if not, it
+  // will get reset to null.  We distinguish the no-predecessor case explicitly
+  // below.
+  unsigned SingularValue = 0;
+  bool isFirstPred = true;
+  for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
+         E = BB->pred_end(); PI != E; ++PI) {
+    MachineBasicBlock *PredBB = *PI;
+    unsigned PredVal = GetValueAtEndOfBlockInternal(PredBB);
+    IncomingPredInfo.push_back(std::make_pair(PredBB, PredVal));
+
+    // Compute SingularValue.
+    if (isFirstPred) {
+      SingularValue = PredVal;
+      isFirstPred = false;
+    } else if (PredVal != SingularValue)
+      SingularValue = 0;
+  }
+
+  /// Look up BB's entry in AvailableVals.  'InsertRes' may be invalidated.  If
+  /// this block is involved in a loop, a no-entry PHI node will have been
+  /// inserted as InsertedVal.  Otherwise, we'll still have the null we inserted
+  /// above.
+  unsigned &InsertedVal = AvailableVals[BB];
+
+  // If all the predecessor values are the same then we don't need to insert a
+  // PHI.  This is the simple and common case.
+  if (SingularValue) {
+    // If a PHI node got inserted, replace it with the singlar value and delete
+    // it.
+    if (InsertedVal) {
+      MachineInstr *OldVal = MRI->getVRegDef(InsertedVal);
+      // Be careful about dead loops.  These RAUW's also update InsertedVal.
+      assert(InsertedVal != SingularValue && "Dead loop?");
+      ReplaceRegWith(InsertedVal, SingularValue);
+      OldVal->eraseFromParent();
+    }
+
+    InsertedVal = SingularValue;
+
+    // Drop the entries we added in IncomingPredInfo to restore the stack.
+    IncomingPredInfo.erase(IncomingPredInfo.begin()+FirstPredInfoEntry,
+                           IncomingPredInfo.end());
+    return InsertedVal;
+  }
+
+
+  // Otherwise, we do need a PHI: insert one now if we don't already have one.
+  MachineInstr *InsertedPHI;
+  if (InsertedVal == 0) {
+    MachineBasicBlock::iterator Loc = BB->empty() ? BB->end() : BB->front();
+    InsertedPHI = InsertNewDef(TargetInstrInfo::PHI, BB, Loc,
+                               VRC, MRI, TII);
+    InsertedVal = InsertedPHI->getOperand(0).getReg();
+  } else {
+    InsertedPHI = MRI->getVRegDef(InsertedVal);
+  }
+
+  // Fill in all the predecessors of the PHI.
+  MachineInstrBuilder MIB(InsertedPHI);
+  for (IncomingPredInfoTy::iterator I =
+         IncomingPredInfo.begin()+FirstPredInfoEntry,
+         E = IncomingPredInfo.end(); I != E; ++I)
+    MIB.addReg(I->second).addMBB(I->first);
+
+  // Drop the entries we added in IncomingPredInfo to restore the stack.
+  IncomingPredInfo.erase(IncomingPredInfo.begin()+FirstPredInfoEntry,
+                         IncomingPredInfo.end());
+
+  // See if the PHI node can be merged to a single value.  This can happen in
+  // loop cases when we get a PHI of itself and one other value.
+  if (unsigned ConstVal = InsertedPHI->isConstantValuePHI()) {
+    MRI->replaceRegWith(InsertedVal, ConstVal);
+    InsertedPHI->eraseFromParent();
+    InsertedVal = ConstVal;
+  } else {
+    DEBUG(errs() << "  Inserted PHI: " << *InsertedPHI << "\n");
+
+    // If the client wants to know about all new instructions, tell it.
+    if (InsertedPHIs) InsertedPHIs->push_back(InsertedPHI);
+  }
+
+  return InsertedVal;
+}