Update LLVM to 91430.

author: rdivacky <rdivacky@FreeBSD.org> 2009-12-15 18:09:07 +0000
committer: rdivacky <rdivacky@FreeBSD.org> 2009-12-15 18:09:07 +0000
commit: 40a6fcdb85efd93fe0e36c9552cfb0b18b5eacd6 (patch)
tree: 076117cdf3579003f07cad4cdf0593347ce58150 /lib/CodeGen/TailDuplication.cpp
parent: e7908924d847e63b02bc82bfaa1709ab9c774dcd (diff)
download: FreeBSD-src-40a6fcdb85efd93fe0e36c9552cfb0b18b5eacd6.zip
FreeBSD-src-40a6fcdb85efd93fe0e36c9552cfb0b18b5eacd6.tar.gz
1 files changed, 427 insertions, 33 deletions
diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp
index 9c0b596..bf58902 100644
--- a/lib/CodeGen/TailDuplication.cpp
+++ b/lib/CodeGen/TailDuplication.cpp
@@ -17,15 +17,19 @@
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/MachineSSAUpdater.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/Statistic.h"
 using namespace llvm;
 
+STATISTIC(NumTails     , "Number of tails duplicated");
 STATISTIC(NumTailDups  , "Number of tail duplicated blocks");
 STATISTIC(NumInstrDups , "Additional instructions due to tail duplication");
 STATISTIC(NumDeadBlocks, "Number of dead blocks removed");
@@ -36,34 +40,71 @@ TailDuplicateSize("tail-dup-size",
                   cl::desc("Maximum instructions to consider tail duplicating"),
                   cl::init(2), cl::Hidden);
 
+static cl::opt<bool>
+TailDupVerify("tail-dup-verify",
+              cl::desc("Verify sanity of PHI instructions during taildup"),
+              cl::init(false), cl::Hidden);
+
+static cl::opt<unsigned>
+TailDupLimit("tail-dup-limit", cl::init(~0U), cl::Hidden);
+
+typedef std::vector<std::pair<MachineBasicBlock*,unsigned> > AvailableValsTy;
+
 namespace {
   /// TailDuplicatePass - Perform tail duplication.
   class TailDuplicatePass : public MachineFunctionPass {
+    bool PreRegAlloc;
     const TargetInstrInfo *TII;
     MachineModuleInfo *MMI;
+    MachineRegisterInfo *MRI;
+
+    // SSAUpdateVRs - A list of virtual registers for which to update SSA form.
+    SmallVector<unsigned, 16> SSAUpdateVRs;
+
+    // SSAUpdateVals - For each virtual register in SSAUpdateVals keep a list of
+    // source virtual registers.
+    DenseMap<unsigned, AvailableValsTy> SSAUpdateVals;
 
   public:
     static char ID;
-    explicit TailDuplicatePass() : MachineFunctionPass(&ID) {}
+    explicit TailDuplicatePass(bool PreRA) :
+      MachineFunctionPass(&ID), PreRegAlloc(PreRA) {}
 
     virtual bool runOnMachineFunction(MachineFunction &MF);
     virtual const char *getPassName() const { return "Tail Duplication"; }
 
   private:
+    void AddSSAUpdateEntry(unsigned OrigReg, unsigned NewReg,
+                           MachineBasicBlock *BB);
+    void ProcessPHI(MachineInstr *MI, MachineBasicBlock *TailBB,
+                    MachineBasicBlock *PredBB,
+                    DenseMap<unsigned, unsigned> &LocalVRMap,
+                    SmallVector<std::pair<unsigned,unsigned>, 4> &Copies);
+    void DuplicateInstruction(MachineInstr *MI,
+                              MachineBasicBlock *TailBB,
+                              MachineBasicBlock *PredBB,
+                              MachineFunction &MF,
+                              DenseMap<unsigned, unsigned> &LocalVRMap);
+    void UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
+                              SmallVector<MachineBasicBlock*, 8> &TDBBs,
+                              SmallSetVector<MachineBasicBlock*, 8> &Succs);
     bool TailDuplicateBlocks(MachineFunction &MF);
-    bool TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF);
+    bool TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
+                       SmallVector<MachineBasicBlock*, 8> &TDBBs,
+                       SmallVector<MachineInstr*, 16> &Copies);
     void RemoveDeadBlock(MachineBasicBlock *MBB);
   };
 
   char TailDuplicatePass::ID = 0;
 }
 
-FunctionPass *llvm::createTailDuplicatePass() {
-  return new TailDuplicatePass();
+FunctionPass *llvm::createTailDuplicatePass(bool PreRegAlloc) {
+  return new TailDuplicatePass(PreRegAlloc);
 }
 
 bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
   TII = MF.getTarget().getInstrInfo();
+  MRI = &MF.getRegInfo();
   MMI = getAnalysisIfAvailable<MachineModuleInfo>();
 
   bool MadeChange = false;
@@ -77,36 +118,325 @@ bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
   return MadeChange;
 }
 
+static void VerifyPHIs(MachineFunction &MF, bool CheckExtra) {
+  for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; ++I) {
+    MachineBasicBlock *MBB = I;
+    SmallSetVector<MachineBasicBlock*, 8> Preds(MBB->pred_begin(),
+                                                MBB->pred_end());
+    MachineBasicBlock::iterator MI = MBB->begin();
+    while (MI != MBB->end()) {
+      if (MI->getOpcode() != TargetInstrInfo::PHI)
+        break;
+      for (SmallSetVector<MachineBasicBlock *, 8>::iterator PI = Preds.begin(),
+             PE = Preds.end(); PI != PE; ++PI) {
+        MachineBasicBlock *PredBB = *PI;
+        bool Found = false;
+        for (unsigned i = 1, e = MI->getNumOperands(); i != e; i += 2) {
+          MachineBasicBlock *PHIBB = MI->getOperand(i+1).getMBB();
+          if (PHIBB == PredBB) {
+            Found = true;
+            break;
+          }
+        }
+        if (!Found) {
+          errs() << "Malformed PHI in BB#" << MBB->getNumber() << ": " << *MI;
+          errs() << "  missing input from predecessor BB#"
+                 << PredBB->getNumber() << '\n';
+          llvm_unreachable(0);
+        }
+      }
+
+      for (unsigned i = 1, e = MI->getNumOperands(); i != e; i += 2) {
+        MachineBasicBlock *PHIBB = MI->getOperand(i+1).getMBB();
+        if (CheckExtra && !Preds.count(PHIBB)) {
+          // This is not a hard error.
+          errs() << "Warning: malformed PHI in BB#" << MBB->getNumber()
+                 << ": " << *MI;
+          errs() << "  extra input from predecessor BB#"
+                 << PHIBB->getNumber() << '\n';
+        }
+        if (PHIBB->getNumber() < 0) {
+          errs() << "Malformed PHI in BB#" << MBB->getNumber() << ": " << *MI;
+          errs() << "  non-existing BB#" << PHIBB->getNumber() << '\n';
+          llvm_unreachable(0);
+        }
+      }
+      ++MI;
+    }
+  }
+}
+
 /// TailDuplicateBlocks - Look for small blocks that are unconditionally
 /// branched to and do not fall through. Tail-duplicate their instructions
 /// into their predecessors to eliminate (dynamic) branches.
 bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) {
   bool MadeChange = false;
 
+  if (PreRegAlloc && TailDupVerify) {
+    DEBUG(errs() << "\n*** Before tail-duplicating\n");
+    VerifyPHIs(MF, true);
+  }
+
+  SmallVector<MachineInstr*, 8> NewPHIs;
+  MachineSSAUpdater SSAUpdate(MF, &NewPHIs);
+
   for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; ) {
     MachineBasicBlock *MBB = I++;
 
+    if (NumTails == TailDupLimit)
+      break;
+
     // Only duplicate blocks that end with unconditional branches.
     if (MBB->canFallThrough())
       continue;
 
-    MadeChange |= TailDuplicate(MBB, MF);
-
-    // If it is dead, remove it.
-    if (MBB->pred_empty()) {
-      NumInstrDups -= MBB->size();
-      RemoveDeadBlock(MBB);
+    // Save the successors list.
+    SmallSetVector<MachineBasicBlock*, 8> Succs(MBB->succ_begin(),
+                                                MBB->succ_end());
+
+    SmallVector<MachineBasicBlock*, 8> TDBBs;
+    SmallVector<MachineInstr*, 16> Copies;
+    if (TailDuplicate(MBB, MF, TDBBs, Copies)) {
+      ++NumTails;
+
+      // TailBB's immediate successors are now successors of those predecessors
+      // which duplicated TailBB. Add the predecessors as sources to the PHI
+      // instructions.
+      bool isDead = MBB->pred_empty();
+      if (PreRegAlloc)
+        UpdateSuccessorsPHIs(MBB, isDead, TDBBs, Succs);
+
+      // If it is dead, remove it.
+      if (isDead) {
+        NumInstrDups -= MBB->size();
+        RemoveDeadBlock(MBB);
+        ++NumDeadBlocks;
+      }
+
+      // Update SSA form.
+      if (!SSAUpdateVRs.empty()) {
+        for (unsigned i = 0, e = SSAUpdateVRs.size(); i != e; ++i) {
+          unsigned VReg = SSAUpdateVRs[i];
+          SSAUpdate.Initialize(VReg);
+
+          // If the original definition is still around, add it as an available
+          // value.
+          MachineInstr *DefMI = MRI->getVRegDef(VReg);
+          MachineBasicBlock *DefBB = 0;
+          if (DefMI) {
+            DefBB = DefMI->getParent();
+            SSAUpdate.AddAvailableValue(DefBB, VReg);
+          }
+
+          // Add the new vregs as available values.
+          DenseMap<unsigned, AvailableValsTy>::iterator LI =
+            SSAUpdateVals.find(VReg);  
+          for (unsigned j = 0, ee = LI->second.size(); j != ee; ++j) {
+            MachineBasicBlock *SrcBB = LI->second[j].first;
+            unsigned SrcReg = LI->second[j].second;
+            SSAUpdate.AddAvailableValue(SrcBB, SrcReg);
+          }
+
+          // Rewrite uses that are outside of the original def's block.
+          MachineRegisterInfo::use_iterator UI = MRI->use_begin(VReg);
+          while (UI != MRI->use_end()) {
+            MachineOperand &UseMO = UI.getOperand();
+            MachineInstr *UseMI = &*UI;
+            ++UI;
+            if (UseMI->getParent() == DefBB)
+              continue;
+            SSAUpdate.RewriteUse(UseMO);
+          }
+        }
+
+        SSAUpdateVRs.clear();
+        SSAUpdateVals.clear();
+      }
+
+      // Eliminate some of the copies inserted tail duplication to maintain
+      // SSA form.
+      for (unsigned i = 0, e = Copies.size(); i != e; ++i) {
+        MachineInstr *Copy = Copies[i];
+        unsigned Src, Dst, SrcSR, DstSR;
+        if (TII->isMoveInstr(*Copy, Src, Dst, SrcSR, DstSR)) {
+          MachineRegisterInfo::use_iterator UI = MRI->use_begin(Src);
+          if (++UI == MRI->use_end()) {
+            // Copy is the only use. Do trivial copy propagation here.
+            MRI->replaceRegWith(Dst, Src);
+            Copy->eraseFromParent();
+          }
+        }
+      }
+
+      if (PreRegAlloc && TailDupVerify)
+        VerifyPHIs(MF, false);
       MadeChange = true;
-      ++NumDeadBlocks;
     }
   }
+
   return MadeChange;
 }
 
+static bool isDefLiveOut(unsigned Reg, MachineBasicBlock *BB,
+                         const MachineRegisterInfo *MRI) {
+  for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(Reg),
+         UE = MRI->use_end(); UI != UE; ++UI) {
+    MachineInstr *UseMI = &*UI;
+    if (UseMI->getParent() != BB)
+      return true;
+  }
+  return false;
+}
+
+static unsigned getPHISrcRegOpIdx(MachineInstr *MI, MachineBasicBlock *SrcBB) {
+  for (unsigned i = 1, e = MI->getNumOperands(); i != e; i += 2)
+    if (MI->getOperand(i+1).getMBB() == SrcBB)
+      return i;
+  return 0;
+}
+
+/// AddSSAUpdateEntry - Add a definition and source virtual registers pair for
+/// SSA update.
+void TailDuplicatePass::AddSSAUpdateEntry(unsigned OrigReg, unsigned NewReg,
+                                          MachineBasicBlock *BB) {
+  DenseMap<unsigned, AvailableValsTy>::iterator LI= SSAUpdateVals.find(OrigReg);
+  if (LI != SSAUpdateVals.end())
+    LI->second.push_back(std::make_pair(BB, NewReg));
+  else {
+    AvailableValsTy Vals;
+    Vals.push_back(std::make_pair(BB, NewReg));
+    SSAUpdateVals.insert(std::make_pair(OrigReg, Vals));
+    SSAUpdateVRs.push_back(OrigReg);
+  }
+}
+
+/// ProcessPHI - Process PHI node in TailBB by turning it into a copy in PredBB.
+/// Remember the source register that's contributed by PredBB and update SSA
+/// update map.
+void TailDuplicatePass::ProcessPHI(MachineInstr *MI,
+                                   MachineBasicBlock *TailBB,
+                                   MachineBasicBlock *PredBB,
+                                   DenseMap<unsigned, unsigned> &LocalVRMap,
+                         SmallVector<std::pair<unsigned,unsigned>, 4> &Copies) {
+  unsigned DefReg = MI->getOperand(0).getReg();
+  unsigned SrcOpIdx = getPHISrcRegOpIdx(MI, PredBB);
+  assert(SrcOpIdx && "Unable to find matching PHI source?");
+  unsigned SrcReg = MI->getOperand(SrcOpIdx).getReg();
+  const TargetRegisterClass *RC = MRI->getRegClass(DefReg);
+  LocalVRMap.insert(std::make_pair(DefReg, SrcReg));
+
+  // Insert a copy from source to the end of the block. The def register is the
+  // available value liveout of the block.
+  unsigned NewDef = MRI->createVirtualRegister(RC);
+  Copies.push_back(std::make_pair(NewDef, SrcReg));
+  if (isDefLiveOut(DefReg, TailBB, MRI))
+    AddSSAUpdateEntry(DefReg, NewDef, PredBB);
+
+  // Remove PredBB from the PHI node.
+  MI->RemoveOperand(SrcOpIdx+1);
+  MI->RemoveOperand(SrcOpIdx);
+  if (MI->getNumOperands() == 1)
+    MI->eraseFromParent();
+}
+
+/// DuplicateInstruction - Duplicate a TailBB instruction to PredBB and update
+/// the source operands due to earlier PHI translation.
+void TailDuplicatePass::DuplicateInstruction(MachineInstr *MI,
+                                     MachineBasicBlock *TailBB,
+                                     MachineBasicBlock *PredBB,
+                                     MachineFunction &MF,
+                                     DenseMap<unsigned, unsigned> &LocalVRMap) {
+  MachineInstr *NewMI = MF.CloneMachineInstr(MI);
+  for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
+    MachineOperand &MO = NewMI->getOperand(i);
+    if (!MO.isReg())
+      continue;
+    unsigned Reg = MO.getReg();
+    if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg))
+      continue;
+    if (MO.isDef()) {
+      const TargetRegisterClass *RC = MRI->getRegClass(Reg);
+      unsigned NewReg = MRI->createVirtualRegister(RC);
+      MO.setReg(NewReg);
+      LocalVRMap.insert(std::make_pair(Reg, NewReg));
+      if (isDefLiveOut(Reg, TailBB, MRI))
+        AddSSAUpdateEntry(Reg, NewReg, PredBB);
+    } else {
+      DenseMap<unsigned, unsigned>::iterator VI = LocalVRMap.find(Reg);
+      if (VI != LocalVRMap.end())
+        MO.setReg(VI->second);
+    }
+  }
+  PredBB->insert(PredBB->end(), NewMI);
+}
+
+/// UpdateSuccessorsPHIs - After FromBB is tail duplicated into its predecessor
+/// blocks, the successors have gained new predecessors. Update the PHI
+/// instructions in them accordingly.
+void
+TailDuplicatePass::UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
+                                  SmallVector<MachineBasicBlock*, 8> &TDBBs,
+                                  SmallSetVector<MachineBasicBlock*,8> &Succs) {
+  for (SmallSetVector<MachineBasicBlock*, 8>::iterator SI = Succs.begin(),
+         SE = Succs.end(); SI != SE; ++SI) {
+    MachineBasicBlock *SuccBB = *SI;
+    for (MachineBasicBlock::iterator II = SuccBB->begin(), EE = SuccBB->end();
+         II != EE; ++II) {
+      if (II->getOpcode() != TargetInstrInfo::PHI)
+        break;
+      unsigned Idx = 0;
+      for (unsigned i = 1, e = II->getNumOperands(); i != e; i += 2) {
+        MachineOperand &MO = II->getOperand(i+1);
+        if (MO.getMBB() == FromBB) {
+          Idx = i;
+          break;
+        }
+      }
+
+      assert(Idx != 0);
+      MachineOperand &MO0 = II->getOperand(Idx);
+      unsigned Reg = MO0.getReg();
+      if (isDead) {
+        // Folded into the previous BB.
+        // There could be duplicate phi source entries. FIXME: Should sdisel
+        // or earlier pass fixed this?
+        for (unsigned i = II->getNumOperands()-2; i != Idx; i -= 2) {
+          MachineOperand &MO = II->getOperand(i+1);
+          if (MO.getMBB() == FromBB) {
+            II->RemoveOperand(i+1);
+            II->RemoveOperand(i);
+          }
+        }
+        II->RemoveOperand(Idx+1);
+        II->RemoveOperand(Idx);
+      }
+      DenseMap<unsigned,AvailableValsTy>::iterator LI=SSAUpdateVals.find(Reg);
+      if (LI != SSAUpdateVals.end()) {
+        // This register is defined in the tail block.
+        for (unsigned j = 0, ee = LI->second.size(); j != ee; ++j) {
+          MachineBasicBlock *SrcBB = LI->second[j].first;
+          unsigned SrcReg = LI->second[j].second;
+          II->addOperand(MachineOperand::CreateReg(SrcReg, false));
+          II->addOperand(MachineOperand::CreateMBB(SrcBB));
+        }
+      } else {
+        // Live in tail block, must also be live in predecessors.
+        for (unsigned j = 0, ee = TDBBs.size(); j != ee; ++j) {
+          MachineBasicBlock *SrcBB = TDBBs[j];
+          II->addOperand(MachineOperand::CreateReg(Reg, false));
+          II->addOperand(MachineOperand::CreateMBB(SrcBB));
+        }
+      }
+    }
+  }
+}
+
 /// TailDuplicate - If it is profitable, duplicate TailBB's contents in each
 /// of its predecessors.
-bool TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
-                                        MachineFunction &MF) {
+bool
+TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
+                                 SmallVector<MachineBasicBlock*, 8> &TDBBs,
+                                 SmallVector<MachineInstr*, 16> &Copies) {
   // Don't try to tail-duplicate single-block loops.
   if (TailBB->isSuccessor(TailBB))
     return false;
@@ -129,28 +459,36 @@ bool TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
 
   // Check the instructions in the block to determine whether tail-duplication
   // is invalid or unlikely to be profitable.
-  unsigned i = 0;
+  unsigned InstrCount = 0;
   bool HasCall = false;
   for (MachineBasicBlock::iterator I = TailBB->begin();
-       I != TailBB->end(); ++I, ++i) {
+       I != TailBB->end(); ++I) {
     // Non-duplicable things shouldn't be tail-duplicated.
     if (I->getDesc().isNotDuplicable()) return false;
+    // Do not duplicate 'return' instructions if this is a pre-regalloc run.
+    // A return may expand into a lot more instructions (e.g. reload of callee
+    // saved registers) after PEI.
+    if (PreRegAlloc && I->getDesc().isReturn()) return false;
     // Don't duplicate more than the threshold.
-    if (i == MaxDuplicateCount) return false;
+    if (InstrCount == MaxDuplicateCount) return false;
     // Remember if we saw a call.
     if (I->getDesc().isCall()) HasCall = true;
+    if (I->getOpcode() != TargetInstrInfo::PHI)
+      InstrCount += 1;
   }
   // Heuristically, don't tail-duplicate calls if it would expand code size,
   // as it's less likely to be worth the extra cost.
-  if (i > 1 && HasCall)
+  if (InstrCount > 1 && HasCall)
     return false;
 
+  DEBUG(errs() << "\n*** Tail-duplicating BB#" << TailBB->getNumber() << '\n');
+
   // Iterate through all the unique predecessors and tail-duplicate this
   // block into them, if possible. Copying the list ahead of time also
   // avoids trouble with the predecessor list reallocating.
   bool Changed = false;
-  SmallSetVector<MachineBasicBlock *, 8> Preds(TailBB->pred_begin(),
-                                               TailBB->pred_end());
+  SmallSetVector<MachineBasicBlock*, 8> Preds(TailBB->pred_begin(),
+                                              TailBB->pred_end());
   for (SmallSetVector<MachineBasicBlock *, 8>::iterator PI = Preds.begin(),
        PE = Preds.end(); PI != PE; ++PI) {
     MachineBasicBlock *PredBB = *PI;
@@ -175,13 +513,35 @@ bool TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
     DEBUG(errs() << "\nTail-duplicating into PredBB: " << *PredBB
                  << "From Succ: " << *TailBB);
 
+    TDBBs.push_back(PredBB);
+
     // Remove PredBB's unconditional branch.
     TII->RemoveBranch(*PredBB);
+
     // Clone the contents of TailBB into PredBB.
-    for (MachineBasicBlock::iterator I = TailBB->begin(), E = TailBB->end();
-         I != E; ++I) {
-      MachineInstr *NewMI = MF.CloneMachineInstr(I);
-      PredBB->insert(PredBB->end(), NewMI);
+    DenseMap<unsigned, unsigned> LocalVRMap;
+    SmallVector<std::pair<unsigned,unsigned>, 4> CopyInfos;
+    MachineBasicBlock::iterator I = TailBB->begin();
+    while (I != TailBB->end()) {
+      MachineInstr *MI = &*I;
+      ++I;
+      if (MI->getOpcode() == TargetInstrInfo::PHI) {
+        // Replace the uses of the def of the PHI with the register coming
+        // from PredBB.
+        ProcessPHI(MI, TailBB, PredBB, LocalVRMap, CopyInfos);
+      } else {
+        // Replace def of virtual registers with new registers, and update
+        // uses with PHI source register or the new registers.
+        DuplicateInstruction(MI, TailBB, PredBB, MF, LocalVRMap);
+      }
+    }
+    MachineBasicBlock::iterator Loc = PredBB->getFirstTerminator();
+    for (unsigned i = 0, e = CopyInfos.size(); i != e; ++i) {
+      const TargetRegisterClass *RC = MRI->getRegClass(CopyInfos[i].first);
+      TII->copyRegToReg(*PredBB, Loc, CopyInfos[i].first,
+                        CopyInfos[i].second, RC,RC);
+      MachineInstr *CopyMI = prior(Loc);
+      Copies.push_back(CopyMI);
     }
     NumInstrDups += TailBB->size() - 1; // subtract one for removed branch
 
@@ -190,8 +550,8 @@ bool TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
     assert(PredBB->succ_empty() &&
            "TailDuplicate called on block with multiple successors!");
     for (MachineBasicBlock::succ_iterator I = TailBB->succ_begin(),
-         E = TailBB->succ_end(); I != E; ++I)
-       PredBB->addSuccessor(*I);
+           E = TailBB->succ_end(); I != E; ++I)
+      PredBB->addSuccessor(*I);
 
     Changed = true;
     ++NumTailDups;
@@ -200,22 +560,56 @@ bool TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
   // If TailBB was duplicated into all its predecessors except for the prior
   // block, which falls through unconditionally, move the contents of this
   // block into the prior block.
-  MachineBasicBlock &PrevBB = *prior(MachineFunction::iterator(TailBB));
+  MachineBasicBlock *PrevBB = prior(MachineFunction::iterator(TailBB));
   MachineBasicBlock *PriorTBB = 0, *PriorFBB = 0;
   SmallVector<MachineOperand, 4> PriorCond;
   bool PriorUnAnalyzable =
-    TII->AnalyzeBranch(PrevBB, PriorTBB, PriorFBB, PriorCond, true);
+    TII->AnalyzeBranch(*PrevBB, PriorTBB, PriorFBB, PriorCond, true);
   // This has to check PrevBB->succ_size() because EH edges are ignored by
   // AnalyzeBranch.
   if (!PriorUnAnalyzable && PriorCond.empty() && !PriorTBB &&
-      TailBB->pred_size() == 1 && PrevBB.succ_size() == 1 &&
+      TailBB->pred_size() == 1 && PrevBB->succ_size() == 1 &&
       !TailBB->hasAddressTaken()) {
-    DEBUG(errs() << "\nMerging into block: " << PrevBB
+    DEBUG(errs() << "\nMerging into block: " << *PrevBB
           << "From MBB: " << *TailBB);
-    PrevBB.splice(PrevBB.end(), TailBB, TailBB->begin(), TailBB->end());
-    PrevBB.removeSuccessor(PrevBB.succ_begin());;
-    assert(PrevBB.succ_empty());
-    PrevBB.transferSuccessors(TailBB);
+    if (PreRegAlloc) {
+      DenseMap<unsigned, unsigned> LocalVRMap;
+      SmallVector<std::pair<unsigned,unsigned>, 4> CopyInfos;
+      MachineBasicBlock::iterator I = TailBB->begin();
+      // Process PHI instructions first.
+      while (I != TailBB->end() && I->getOpcode() == TargetInstrInfo::PHI) {
+        // Replace the uses of the def of the PHI with the register coming
+        // from PredBB.
+        MachineInstr *MI = &*I++;
+        ProcessPHI(MI, TailBB, PrevBB, LocalVRMap, CopyInfos);
+        if (MI->getParent())
+          MI->eraseFromParent();
+      }
+
+      // Now copy the non-PHI instructions.
+      while (I != TailBB->end()) {
+        // Replace def of virtual registers with new registers, and update
+        // uses with PHI source register or the new registers.
+        MachineInstr *MI = &*I++;
+        DuplicateInstruction(MI, TailBB, PrevBB, MF, LocalVRMap);
+        MI->eraseFromParent();
+      }
+      MachineBasicBlock::iterator Loc = PrevBB->getFirstTerminator();
+      for (unsigned i = 0, e = CopyInfos.size(); i != e; ++i) {
+        const TargetRegisterClass *RC = MRI->getRegClass(CopyInfos[i].first);
+        TII->copyRegToReg(*PrevBB, Loc, CopyInfos[i].first,
+                          CopyInfos[i].second, RC, RC);
+        MachineInstr *CopyMI = prior(Loc);
+        Copies.push_back(CopyMI);
+      }
+    } else {
+      // No PHIs to worry about, just splice the instructions over.
+      PrevBB->splice(PrevBB->end(), TailBB, TailBB->begin(), TailBB->end());
+    }
+    PrevBB->removeSuccessor(PrevBB->succ_begin());
+    assert(PrevBB->succ_empty());
+    PrevBB->transferSuccessors(TailBB);
+    TDBBs.push_back(PrevBB);
     Changed = true;
   }
author	rdivacky <rdivacky@FreeBSD.org>	2009-12-15 18:09:07 +0000
committer	rdivacky <rdivacky@FreeBSD.org>	2009-12-15 18:09:07 +0000
commit	40a6fcdb85efd93fe0e36c9552cfb0b18b5eacd6 (patch)
tree	076117cdf3579003f07cad4cdf0593347ce58150 /lib/CodeGen/TailDuplication.cpp
parent	e7908924d847e63b02bc82bfaa1709ab9c774dcd (diff)
download	FreeBSD-src-40a6fcdb85efd93fe0e36c9552cfb0b18b5eacd6.zip FreeBSD-src-40a6fcdb85efd93fe0e36c9552cfb0b18b5eacd6.tar.gz