C++ const_iterator::getTerminator方法代码示例

// SurveyFunction - This performs the initial survey of the specified function,
// checking out whether or not it uses any of its incoming arguments or whether
// any callers use the return value.  This fills in the LiveValues set and Uses
// map.
//
// We consider arguments of non-internal functions to be intrinsically alive as
// well as arguments to functions which have their "address taken".
//
void DAE::SurveyFunction(const Function &F) {
  unsigned RetCount = NumRetVals(&F);
  // Assume all return values are dead
  typedef SmallVector<Liveness, 5> RetVals;
  RetVals RetValLiveness(RetCount, MaybeLive);

  typedef SmallVector<UseVector, 5> RetUses;
  // These vectors map each return value to the uses that make it MaybeLive, so
  // we can add those to the Uses map if the return value really turns out to be
  // MaybeLive. Initialized to a list of RetCount empty lists.
  RetUses MaybeLiveRetUses(RetCount);

  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
    if (const ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
      if (RI->getNumOperands() != 0 && RI->getOperand(0)->getType()
          != F.getFunctionType()->getReturnType()) {
        // We don't support old style multiple return values.
        MarkLive(F);
        return;
      }

  if (!F.hasLocalLinkage() && (!ShouldHackArguments() || F.isIntrinsic())) {
    MarkLive(F);
    return;
  }

  DEBUG(dbgs() << "DAE - Inspecting callers for fn: " << F.getName() << "\n");
  // Keep track of the number of live retvals, so we can skip checks once all
  // of them turn out to be live.
  unsigned NumLiveRetVals = 0;
  Type *STy = dyn_cast<StructType>(F.getReturnType());
  // Loop all uses of the function.
  for (Value::const_use_iterator I = F.use_begin(), E = F.use_end();
       I != E; ++I) {
    // If the function is PASSED IN as an argument, its address has been
    // taken.
    ImmutableCallSite CS(*I);
    if (!CS || !CS.isCallee(I)) {
      MarkLive(F);
      return;
    }

    // If this use is anything other than a call site, the function is alive.
    const Instruction *TheCall = CS.getInstruction();
    if (!TheCall) {   // Not a direct call site?
      MarkLive(F);
      return;
    }

    // If we end up here, we are looking at a direct call to our function.

    // Now, check how our return value(s) is/are used in this caller. Don't
    // bother checking return values if all of them are live already.
    if (NumLiveRetVals != RetCount) {
      if (STy) {
        // Check all uses of the return value.
        for (Value::const_use_iterator I = TheCall->use_begin(),
             E = TheCall->use_end(); I != E; ++I) {
          const ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(*I);
          if (Ext && Ext->hasIndices()) {
            // This use uses a part of our return value, survey the uses of
            // that part and store the results for this index only.
            unsigned Idx = *Ext->idx_begin();
            if (RetValLiveness[Idx] != Live) {
              RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]);
              if (RetValLiveness[Idx] == Live)
                NumLiveRetVals++;
            }
          } else {
            // Used by something else than extractvalue. Mark all return
            // values as live.
            for (unsigned i = 0; i != RetCount; ++i )
              RetValLiveness[i] = Live;
            NumLiveRetVals = RetCount;
            break;
          }
        }
      } else {
        // Single return value
        RetValLiveness[0] = SurveyUses(TheCall, MaybeLiveRetUses[0]);
        if (RetValLiveness[0] == Live)
          NumLiveRetVals = RetCount;
      }
    }
  }

  // Now we've inspected all callers, record the liveness of our return values.
  for (unsigned i = 0; i != RetCount; ++i)
    MarkValue(CreateRet(&F, i), RetValLiveness[i], MaybeLiveRetUses[i]);

  DEBUG(dbgs() << "DAE - Inspecting args for fn: " << F.getName() << "\n");

//.........这里部分代码省略.........

// SurveyFunction - This performs the initial survey of the specified function,
// checking out whether or not it uses any of its incoming arguments or whether
// any callers use the return value.  This fills in the LiveValues set and Uses
// map.
//
// We consider arguments of non-internal functions to be intrinsically alive as
// well as arguments to functions which have their "address taken".
//
void DAE::SurveyFunction(const Function &F) {
  // Functions with inalloca parameters are expecting args in a particular
  // register and memory layout.
  if (F.getAttributes().hasAttrSomewhere(Attribute::InAlloca)) {
    MarkLive(F);
    return;
  }

  // Don't touch naked functions. The assembly might be using an argument, or
  // otherwise rely on the frame layout in a way that this analysis will not
  // see.
  if (F.hasFnAttribute(Attribute::Naked)) {
    MarkLive(F);
    return;
  }

  unsigned RetCount = NumRetVals(&F);
  // Assume all return values are dead
  typedef SmallVector<Liveness, 5> RetVals;
  RetVals RetValLiveness(RetCount, MaybeLive);

  typedef SmallVector<UseVector, 5> RetUses;
  // These vectors map each return value to the uses that make it MaybeLive, so
  // we can add those to the Uses map if the return value really turns out to be
  // MaybeLive. Initialized to a list of RetCount empty lists.
  RetUses MaybeLiveRetUses(RetCount);

  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
    if (const ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator()))
      if (RI->getNumOperands() != 0 && RI->getOperand(0)->getType()
          != F.getFunctionType()->getReturnType()) {
        // We don't support old style multiple return values.
        MarkLive(F);
        return;
      }

  if (!F.hasLocalLinkage() && (!ShouldHackArguments() || F.isIntrinsic())) {
    MarkLive(F);
    return;
  }

  DEBUG(dbgs() << "DAE - Inspecting callers for fn: " << F.getName() << "\n");
  // Keep track of the number of live retvals, so we can skip checks once all
  // of them turn out to be live.
  unsigned NumLiveRetVals = 0;
  // Loop all uses of the function.
  for (const Use &U : F.uses()) {
    // If the function is PASSED IN as an argument, its address has been
    // taken.
    ImmutableCallSite CS(U.getUser());
    if (!CS || !CS.isCallee(&U)) {
      MarkLive(F);
      return;
    }

    // If this use is anything other than a call site, the function is alive.
    const Instruction *TheCall = CS.getInstruction();
    if (!TheCall) {   // Not a direct call site?
      MarkLive(F);
      return;
    }

    // If we end up here, we are looking at a direct call to our function.

    // Now, check how our return value(s) is/are used in this caller. Don't
    // bother checking return values if all of them are live already.
    if (NumLiveRetVals == RetCount)
      continue;

    // Check all uses of the return value.
    for (const Use &U : TheCall->uses()) {
      if (ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(U.getUser())) {
        // This use uses a part of our return value, survey the uses of
        // that part and store the results for this index only.
        unsigned Idx = *Ext->idx_begin();
        if (RetValLiveness[Idx] != Live) {
          RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]);
          if (RetValLiveness[Idx] == Live)
            NumLiveRetVals++;
        }
      } else {
        // Used by something else than extractvalue. Survey, but assume that the
        // result applies to all sub-values.
        UseVector MaybeLiveAggregateUses;
        if (SurveyUse(&U, MaybeLiveAggregateUses) == Live) {
          NumLiveRetVals = RetCount;
          RetValLiveness.assign(RetCount, Live);
          break;
        } else {
          for (unsigned i = 0; i != RetCount; ++i) {
            if (RetValLiveness[i] != Live)
              MaybeLiveRetUses[i].append(MaybeLiveAggregateUses.begin(),
//.........这里部分代码省略.........

//.........这里部分代码省略.........
          const Value *Address = DI->getAddress();
          if (Address) {
            if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
              Address = BCI->getOperand(0);
            if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
              DenseMap<const AllocaInst *, int>::iterator SI =
                StaticAllocaMap.find(AI);
              if (SI != StaticAllocaMap.end()) { // Check for VLAs.
                int FI = SI->second;
                MMI.setVariableDbgInfo(DI->getVariable(), DI->getExpression(),
                                       FI, DI->getDebugLoc());
              }
            }
          }
        }
      }

      // Decide the preferred extend type for a value.
      PreferredExtendType[I] = getPreferredExtendForValue(I);
    }

  // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
  // also creates the initial PHI MachineInstrs, though none of the input
  // operands are populated.
  for (BB = Fn->begin(); BB != EB; ++BB) {
    MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
    MBBMap[BB] = MBB;
    MF->push_back(MBB);

    // Transfer the address-taken flag. This is necessary because there could
    // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
    // the first one should be marked.
    if (BB->hasAddressTaken())
      MBB->setHasAddressTaken();

    // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
    // appropriate.
    for (BasicBlock::const_iterator I = BB->begin();
         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
      if (PN->use_empty()) continue;

      // Skip empty types
      if (PN->getType()->isEmptyTy())
        continue;

      DebugLoc DL = PN->getDebugLoc();
      unsigned PHIReg = ValueMap[PN];
      assert(PHIReg && "PHI node does not have an assigned virtual register!");

      SmallVector<EVT, 4> ValueVTs;
      ComputeValueVTs(*TLI, PN->getType(), ValueVTs);
      for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
        EVT VT = ValueVTs[vti];
        unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT);
        const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
        for (unsigned i = 0; i != NumRegisters; ++i)
          BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
        PHIReg += NumRegisters;
      }
    }
  }

  // Mark landing pad blocks.
  SmallVector<const LandingPadInst *, 4> LPads;
  for (BB = Fn->begin(); BB != EB; ++BB) {
    if (const auto *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
      MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
    if (BB->isLandingPad())
      LPads.push_back(BB->getLandingPadInst());
  }

  // If this is an MSVC EH personality, we need to do a bit more work.
  EHPersonality Personality = EHPersonality::Unknown;
  if (!LPads.empty())
    Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
  if (!isMSVCEHPersonality(Personality))
    return;

  if (Personality == EHPersonality::MSVC_Win64SEH ||
      Personality == EHPersonality::MSVC_X86SEH) {
    addSEHHandlersForLPads(LPads);
  }

  WinEHFuncInfo &EHInfo = MMI.getWinEHFuncInfo(&fn);
  if (Personality == EHPersonality::MSVC_CXX) {
    const Function *WinEHParentFn = MMI.getWinEHParent(&fn);
    calculateWinCXXEHStateNumbers(WinEHParentFn, EHInfo);
  }

  // Copy the state numbers to LandingPadInfo for the current function, which
  // could be a handler or the parent. This should happen for 32-bit SEH and
  // C++ EH.
  if (Personality == EHPersonality::MSVC_CXX ||
      Personality == EHPersonality::MSVC_X86SEH) {
    for (const LandingPadInst *LP : LPads) {
      MachineBasicBlock *LPadMBB = MBBMap[LP->getParent()];
      MMI.addWinEHState(LPadMBB, EHInfo.LandingPadStateMap[LP]);
    }
  }
}

//.........这里部分代码省略.........
                    for (size_t I = 0, E = Ops.size(); I != E; ++I) {
                        TargetLowering::AsmOperandInfo &Op = Ops[I];
                        if (Op.Type == InlineAsm::isClobber) {
                            // Clobbers don't have SDValue operands, hence SDValue().
                            TLI->ComputeConstraintToUse(Op, SDValue(), DAG);
                            std::pair<unsigned, const TargetRegisterClass*> PhysReg =
                                TLI->getRegForInlineAsmConstraint(Op.ConstraintCode,
                                                                  Op.ConstraintVT);
                            if (PhysReg.first == SP)
                                MF->getFrameInfo()->setHasInlineAsmWithSPAdjust(true);
                        }
                    }
                }
            }

            // Mark values used outside their block as exported, by allocating
            // a virtual register for them.
            if (isUsedOutsideOfDefiningBlock(I))
                if (!isa<AllocaInst>(I) ||
                        !StaticAllocaMap.count(cast<AllocaInst>(I)))
                    InitializeRegForValue(I);

            // Collect llvm.dbg.declare information. This is done now instead of
            // during the initial isel pass through the IR so that it is done
            // in a predictable order.
            if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
                MachineModuleInfo &MMI = MF->getMMI();
                DIVariable DIVar(DI->getVariable());
                assert((!DIVar || DIVar.isVariable()) &&
                       "Variable in DbgDeclareInst should be either null or a DIVariable.");
                if (MMI.hasDebugInfo() &&
                        DIVar &&
                        !DI->getDebugLoc().isUnknown()) {
                    // Don't handle byval struct arguments or VLAs, for example.
                    // Non-byval arguments are handled here (they refer to the stack
                    // temporary alloca at this point).
                    const Value *Address = DI->getAddress();
                    if (Address) {
                        if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
                            Address = BCI->getOperand(0);
                        if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
                            DenseMap<const AllocaInst *, int>::iterator SI =
                                StaticAllocaMap.find(AI);
                            if (SI != StaticAllocaMap.end()) { // Check for VLAs.
                                int FI = SI->second;
                                MMI.setVariableDbgInfo(DI->getVariable(),
                                                       FI, DI->getDebugLoc());
                            }
                        }
                    }
                }
            }
        }

    // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
    // also creates the initial PHI MachineInstrs, though none of the input
    // operands are populated.
    for (BB = Fn->begin(); BB != EB; ++BB) {
        MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
        MBBMap[BB] = MBB;
        MF->push_back(MBB);

        // Transfer the address-taken flag. This is necessary because there could
        // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
        // the first one should be marked.
        if (BB->hasAddressTaken())
            MBB->setHasAddressTaken();

        // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
        // appropriate.
        for (BasicBlock::const_iterator I = BB->begin();
                const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
            if (PN->use_empty()) continue;

            // Skip empty types
            if (PN->getType()->isEmptyTy())
                continue;

            DebugLoc DL = PN->getDebugLoc();
            unsigned PHIReg = ValueMap[PN];
            assert(PHIReg && "PHI node does not have an assigned virtual register!");

            SmallVector<EVT, 4> ValueVTs;
            ComputeValueVTs(*TLI, PN->getType(), ValueVTs);
            for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
                EVT VT = ValueVTs[vti];
                unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT);
                const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
                for (unsigned i = 0; i != NumRegisters; ++i)
                    BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
                PHIReg += NumRegisters;
            }
        }
    }

    // Mark landing pad blocks.
    for (BB = Fn->begin(); BB != EB; ++BB)
        if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
            MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
}

/// InlineFunction - This function inlines the called function into the basic
/// block of the caller.  This returns false if it is not possible to inline
/// this call.  The program is still in a well defined state if this occurs
/// though.
///
/// Note that this only does one level of inlining.  For example, if the
/// instruction 'call B' is inlined, and 'B' calls 'C', then the call to 'C' now
/// exists in the instruction stream.  Similarly this will inline a recursive
/// function by one level.
bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
                          bool InsertLifetime) {
  Instruction *TheCall = CS.getInstruction();
  assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
         "Instruction not in function!");

  // If IFI has any state in it, zap it before we fill it in.
  IFI.reset();
  
  const Function *CalledFunc = CS.getCalledFunction();
  if (CalledFunc == 0 ||          // Can't inline external function or indirect
      CalledFunc->isDeclaration() || // call, or call to a vararg function!
      CalledFunc->getFunctionType()->isVarArg()) return false;

  // If the call to the callee is not a tail call, we must clear the 'tail'
  // flags on any calls that we inline.
  bool MustClearTailCallFlags =
    !(isa<CallInst>(TheCall) && cast<CallInst>(TheCall)->isTailCall());

  // If the call to the callee cannot throw, set the 'nounwind' flag on any
  // calls that we inline.
  bool MarkNoUnwind = CS.doesNotThrow();

  BasicBlock *OrigBB = TheCall->getParent();
  Function *Caller = OrigBB->getParent();

  // GC poses two hazards to inlining, which only occur when the callee has GC:
  //  1. If the caller has no GC, then the callee's GC must be propagated to the
  //     caller.
  //  2. If the caller has a differing GC, it is invalid to inline.
  if (CalledFunc->hasGC()) {
    if (!Caller->hasGC())
      Caller->setGC(CalledFunc->getGC());
    else if (CalledFunc->getGC() != Caller->getGC())
      return false;
  }

  // Get the personality function from the callee if it contains a landing pad.
  Value *CalleePersonality = 0;
  for (Function::const_iterator I = CalledFunc->begin(), E = CalledFunc->end();
       I != E; ++I)
    if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
      const BasicBlock *BB = II->getUnwindDest();
      const LandingPadInst *LP = BB->getLandingPadInst();
      CalleePersonality = LP->getPersonalityFn();
      break;
    }

  // Find the personality function used by the landing pads of the caller. If it
  // exists, then check to see that it matches the personality function used in
  // the callee.
  if (CalleePersonality) {
    for (Function::const_iterator I = Caller->begin(), E = Caller->end();
         I != E; ++I)
      if (const InvokeInst *II = dyn_cast<InvokeInst>(I->getTerminator())) {
        const BasicBlock *BB = II->getUnwindDest();
        const LandingPadInst *LP = BB->getLandingPadInst();

        // If the personality functions match, then we can perform the
        // inlining. Otherwise, we can't inline.
        // TODO: This isn't 100% true. Some personality functions are proper
        //       supersets of others and can be used in place of the other.
        if (LP->getPersonalityFn() != CalleePersonality)
          return false;

        break;
      }
  }

  // Get an iterator to the last basic block in the function, which will have
  // the new function inlined after it.
  Function::iterator LastBlock = &Caller->back();

  // Make sure to capture all of the return instructions from the cloned
  // function.
  SmallVector<ReturnInst*, 8> Returns;
  ClonedCodeInfo InlinedFunctionInfo;
  Function::iterator FirstNewBlock;

  { // Scope to destroy VMap after cloning.
    ValueToValueMapTy VMap;

    assert(CalledFunc->arg_size() == CS.arg_size() &&
           "No varargs calls can be inlined!");

    // Calculate the vector of arguments to pass into the function cloner, which
    // matches up the formal to the actual argument values.
    CallSite::arg_iterator AI = CS.arg_begin();
    unsigned ArgNo = 0;
    for (Function::const_arg_iterator I = CalledFunc->arg_begin(),
         E = CalledFunc->arg_end(); I != E; ++I, ++AI, ++ArgNo) {
//.........这里部分代码省略.........

//.........这里部分代码省略.........
                   AI->getAlignment());

        TySize *= CUI->getZExtValue();   // Get total allocated size.
        if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.

        // The object may need to be placed onto the stack near the stack
        // protector if one exists. Determine here if this object is a suitable
        // candidate. I.e., it would trigger the creation of a stack protector.
        bool MayNeedSP =
          (AI->isArrayAllocation() ||
           (TySize > 8 && isa<ArrayType>(Ty) &&
            cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
        StaticAllocaMap[AI] =
          MF->getFrameInfo()->CreateStackObject(TySize, Align, false, MayNeedSP);
      }

  for (; BB != EB; ++BB)
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
      // Mark values used outside their block as exported, by allocating
      // a virtual register for them.
      if (isUsedOutsideOfDefiningBlock(I))
        if (!isa<AllocaInst>(I) ||
            !StaticAllocaMap.count(cast<AllocaInst>(I)))
          InitializeRegForValue(I);

      // Collect llvm.dbg.declare information. This is done now instead of
      // during the initial isel pass through the IR so that it is done
      // in a predictable order.
      if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
        MachineModuleInfo &MMI = MF->getMMI();
        if (MMI.hasDebugInfo() &&
            DIVariable(DI->getVariable()).Verify() &&
            !DI->getDebugLoc().isUnknown()) {
          // Don't handle byval struct arguments or VLAs, for example.
          // Non-byval arguments are handled here (they refer to the stack
          // temporary alloca at this point).
          const Value *Address = DI->getAddress();
          if (Address) {
            if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
              Address = BCI->getOperand(0);
            if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
              DenseMap<const AllocaInst *, int>::iterator SI =
                StaticAllocaMap.find(AI);
              if (SI != StaticAllocaMap.end()) { // Check for VLAs.
                int FI = SI->second;
                MMI.setVariableDbgInfo(DI->getVariable(),
                                       FI, DI->getDebugLoc());
              }
            }
          }
        }
      }
    }

  // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
  // also creates the initial PHI MachineInstrs, though none of the input
  // operands are populated.
  for (BB = Fn->begin(); BB != EB; ++BB) {
    MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
    MBBMap[BB] = MBB;
    MF->push_back(MBB);

    // Transfer the address-taken flag. This is necessary because there could
    // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
    // the first one should be marked.
    if (BB->hasAddressTaken())
      MBB->setHasAddressTaken();

    // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
    // appropriate.
    for (BasicBlock::const_iterator I = BB->begin();
         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
      if (PN->use_empty()) continue;

      // Skip empty types
      if (PN->getType()->isEmptyTy())
        continue;

      DebugLoc DL = PN->getDebugLoc();
      unsigned PHIReg = ValueMap[PN];
      assert(PHIReg && "PHI node does not have an assigned virtual register!");

      SmallVector<EVT, 4> ValueVTs;
      ComputeValueVTs(TLI, PN->getType(), ValueVTs);
      for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
        EVT VT = ValueVTs[vti];
        unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
        const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
        for (unsigned i = 0; i != NumRegisters; ++i)
          BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
        PHIReg += NumRegisters;
      }
    }
  }

  // Mark landing pad blocks.
  for (BB = Fn->begin(); BB != EB; ++BB)
    if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
      MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
}

void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
  Fn = &fn;
  MF = &mf;
  RegInfo = &MF->getRegInfo();

  // Create a vreg for each argument register that is not dead and is used
  // outside of the entry block for the function.
  for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
       AI != E; ++AI)
    if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
      InitializeRegForValue(AI);

  // Initialize the mapping of values to registers.  This is only set up for
  // instruction values that are used outside of the block that defines
  // them.
  Function::const_iterator BB = Fn->begin(), EB = Fn->end();
  for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
    if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
      if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
        const Type *Ty = AI->getAllocatedType();
        uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
        unsigned Align =
          std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
                   AI->getAlignment());

        TySize *= CUI->getZExtValue();   // Get total allocated size.
        if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
        StaticAllocaMap[AI] =
          MF->getFrameInfo()->CreateStackObject(TySize, Align, false);
      }

  for (; BB != EB; ++BB)
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
      if (isUsedOutsideOfDefiningBlock(I))
        if (!isa<AllocaInst>(I) ||
            !StaticAllocaMap.count(cast<AllocaInst>(I)))
          InitializeRegForValue(I);

  // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
  // also creates the initial PHI MachineInstrs, though none of the input
  // operands are populated.
  for (BB = Fn->begin(); BB != EB; ++BB) {
    MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
    MBBMap[BB] = MBB;
    MF->push_back(MBB);

    // Transfer the address-taken flag. This is necessary because there could
    // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
    // the first one should be marked.
    if (BB->hasAddressTaken())
      MBB->setHasAddressTaken();

    // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
    // appropriate.
    for (BasicBlock::const_iterator I = BB->begin();
         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
      if (PN->use_empty()) continue;

      DebugLoc DL = PN->getDebugLoc();
      unsigned PHIReg = ValueMap[PN];
      assert(PHIReg && "PHI node does not have an assigned virtual register!");

      SmallVector<EVT, 4> ValueVTs;
      ComputeValueVTs(TLI, PN->getType(), ValueVTs);
      for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
        EVT VT = ValueVTs[vti];
        unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
        const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
        for (unsigned i = 0; i != NumRegisters; ++i)
          BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
        PHIReg += NumRegisters;
      }
    }
  }

  // Mark landing pad blocks.
  for (BB = Fn->begin(); BB != EB; ++BB)
    if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
      MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
}