text: //===- InlineFunction.cpp - Code to perform function inlining -------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file implements inlining of a function into a call site, resolving
  // parameters and the return value as appropriate.
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/Transforms/Utils/Cloning.h"
  #include "llvm/Constants.h"
  #include "llvm/DerivedTypes.h"
  #include "llvm/Module.h"
  #include "llvm/Instructions.h"
  #include "llvm/IntrinsicInst.h"
  #include "llvm/Intrinsics.h"
  #include "llvm/Attributes.h"
  #include "llvm/Analysis/CallGraph.h"
  #include "llvm/Analysis/DebugInfo.h"
  #include "llvm/Analysis/InstructionSimplify.h"
  #include "llvm/Target/TargetData.h"
  #include "llvm/Transforms/Utils/Local.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringExtras.h"
  #include "llvm/Support/CallSite.h"
  #include "llvm/Support/IRBuilder.h"
  using namespace llvm;
  
  bool llvm::InlineFunction(CallInst *CI, InlineFunctionInfo &IFI,
                            bool InsertLifetime) {
    return InlineFunction(CallSite(CI), IFI, InsertLifetime);
  }
  bool llvm::InlineFunction(InvokeInst *II, InlineFunctionInfo &IFI,
                            bool InsertLifetime) {
    return InlineFunction(CallSite(II), IFI, InsertLifetime);
  }
  
  namespace {
    /// A class for recording information about inlining through an invoke.
    class InvokeInliningInfo {
      BasicBlock *OuterResumeDest; //< Destination of the invoke's unwind.
      BasicBlock *InnerResumeDest; //< Destination for the callee's resume.
      LandingPadInst *CallerLPad;  //< LandingPadInst associated with the invoke.
      PHINode *InnerEHValuesPHI;   //< PHI for EH values from landingpad insts.
      SmallVector<Value*, 8> UnwindDestPHIValues;
  
    public:
      InvokeInliningInfo(InvokeInst *II)
        : OuterResumeDest(II->getUnwindDest()), InnerResumeDest(0),
          CallerLPad(0), InnerEHValuesPHI(0) {
        // If there are PHI nodes in the unwind destination block, we need to keep
        // track of which values came into them from the invoke before removing
        // the edge from this block.
        llvm::BasicBlock *InvokeBB = II->getParent();
        BasicBlock::iterator I = OuterResumeDest->begin();
        for (; isa<PHINode>(I); ++I) {
          // Save the value to use for this edge.
          PHINode *PHI = cast<PHINode>(I);
          UnwindDestPHIValues.push_back(PHI->getIncomingValueForBlock(InvokeBB));
        }
  
        CallerLPad = cast<LandingPadInst>(I);
      }
  
      /// getOuterResumeDest - The outer unwind destination is the target of
      /// unwind edges introduced for calls within the inlined function.
      BasicBlock *getOuterResumeDest() const {
        return OuterResumeDest;
      }
  
      BasicBlock *getInnerResumeDest();
  
      LandingPadInst *getLandingPadInst() const { return CallerLPad; }
  
      /// forwardResume - Forward the 'resume' instruction to the caller's landing
      /// pad block. When the landing pad block has only one predecessor, this is
      /// a simple branch. When there is more than one predecessor, we need to
      /// split the landing pad block after the landingpad instruction and jump
      /// to there.
      void forwardResume(ResumeInst *RI);
  
      /// addIncomingPHIValuesFor - Add incoming-PHI values to the unwind
      /// destination block for the given basic block, using the values for the
      /// original invoke's source block.
      void addIncomingPHIValuesFor(BasicBlock *BB) const {
        addIncomingPHIValuesForInto(BB, OuterResumeDest);
      }
  
      void addIncomingPHIValuesForInto(BasicBlock *src, BasicBlock *dest) const {
        BasicBlock::iterator I = dest->begin();
        for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
          PHINode *phi = cast<PHINode>(I);
          phi->addIncoming(UnwindDestPHIValues[i], src);
        }
      }
    };
  }
  
  /// getInnerResumeDest - Get or create a target for the branch from ResumeInsts.
  BasicBlock *InvokeInliningInfo::getInnerResumeDest() {
    if (InnerResumeDest) return InnerResumeDest;
  
    // Split the landing pad.
    BasicBlock::iterator SplitPoint = CallerLPad; ++SplitPoint;
    InnerResumeDest =
      OuterResumeDest->splitBasicBlock(SplitPoint,
                                       OuterResumeDest->getName() + ".body");
  
    // The number of incoming edges we expect to the inner landing pad.
    const unsigned PHICapacity = 2;
  
    // Create corresponding new PHIs for all the PHIs in the outer landing pad.
    BasicBlock::iterator InsertPoint = InnerResumeDest->begin();
    BasicBlock::iterator I = OuterResumeDest->begin();
    for (unsigned i = 0, e = UnwindDestPHIValues.size(); i != e; ++i, ++I) {
      PHINode *OuterPHI = cast<PHINode>(I);
      PHINode *InnerPHI = PHINode::Create(OuterPHI->getType(), PHICapacity,
                                          OuterPHI->getName() + ".lpad-body",
                                          InsertPoint);
      OuterPHI->replaceAllUsesWith(InnerPHI);
      InnerPHI->addIncoming(OuterPHI, OuterResumeDest);
    }
  
    // Create a PHI for the exception values.
    InnerEHValuesPHI = PHINode::Create(CallerLPad->getType(), PHICapacity,
                                       "eh.lpad-body", InsertPoint);
    CallerLPad->replaceAllUsesWith(InnerEHValuesPHI);
    InnerEHValuesPHI->addIncoming(CallerLPad, OuterResumeDest);
  
    // All done.
    return InnerResumeDest;
  }
  
  /// forwardResume - Forward the 'resume' instruction to the caller's landing pad
  /// block. When the landing pad block has only one predecessor, this is a simple
  /// branch. When there is more than one predecessor, we need to split the
  /// landing pad block after the landingpad instruction and jump to there.
  void InvokeInliningInfo::forwardResume(ResumeInst *RI) {
    BasicBlock *Dest = getInnerResumeDest();
    BasicBlock *Src = RI->getParent();
  
    BranchInst::Create(Dest, Src);
  
    // Update the PHIs in the destination. They were inserted in an order which
    // makes this work.
    addIncomingPHIValuesForInto(Src, Dest);
  
    InnerEHValuesPHI->addIncoming(RI->getOperand(0), Src);
    RI->eraseFromParent();
  }
  
  /// HandleCallsInBlockInlinedThroughInvoke - When we inline a basic block into
  /// an invoke, we have to turn all of the calls that can throw into
  /// invokes.  This function analyze BB to see if there are any calls, and if so,
  /// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI
  /// nodes in that block with the values specified in InvokeDestPHIValues.
  ///
  /// Returns true to indicate that the next block should be skipped.
  static bool HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB,
                                                     InvokeInliningInfo &Invoke) {
    LandingPadInst *LPI = Invoke.getLandingPadInst();
  
    for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
      Instruction *I = BBI++;
  
      if (LandingPadInst *L = dyn_cast<LandingPadInst>(I)) {
        unsigned NumClauses = LPI->getNumClauses();
        L->reserveClauses(NumClauses);
        for (unsigned i = 0; i != NumClauses; ++i)
          L->addClause(LPI->getClause(i));
      }
  
      // We only need to check for function calls: inlined invoke
      // instructions require no special handling.
      CallInst *CI = dyn_cast<CallInst>(I);
  
      // If this call cannot unwind, don't convert it to an invoke.
      if (!CI || CI->doesNotThrow())
        continue;
  
      // Convert this function call into an invoke instruction.  First, split the
      // basic block.
      BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
  
      // Delete the unconditional branch inserted by splitBasicBlock
      BB->getInstList().pop_back();
  
      // Create the new invoke instruction.
      ImmutableCallSite CS(CI);
      SmallVector<Value*, 8> InvokeArgs(CS.arg_begin(), CS.arg_end());
      InvokeInst *II = InvokeInst::Create(CI->getCalledValue(), Split,
                                          Invoke.getOuterResumeDest(),
                                          InvokeArgs, CI->getName(), BB);
      II->setCallingConv(CI->getCallingConv());
      II->setAttributes(CI->getAttributes());
      
      // Make sure that anything using the call now uses the invoke!  This also
      // updates the CallGraph if present, because it uses a WeakVH.
      CI->replaceAllUsesWith(II);
  
      // Delete the original call
      Split->getInstList().pop_front();
  
      // Update any PHI nodes in the exceptional block to indicate that there is
      // now a new entry in them.
      Invoke.addIncomingPHIValuesFor(BB);
      return false;
    }
  
    return false;
  }
  
  /// HandleInlinedInvoke - If we inlined an invoke site, we need to convert calls
  /// in the body of the inlined function into invokes.
  ///
  /// II is the invoke instruction being inlined.  FirstNewBlock is the first
  /// block of the inlined code (the last block is the end of the function),
  /// and InlineCodeInfo is information about the code that got inlined.
  static void HandleInlinedInvoke(InvokeInst *II, BasicBlock *FirstNewBlock,
                                  ClonedCodeInfo &InlinedCodeInfo) {
    BasicBlock *InvokeDest = II->getUnwindDest();
  
    Function *Caller = FirstNewBlock->getParent();
  
    // The inlined code is currently at the end of the function, scan from the
    // start of the inlined code to its end, checking for stuff we need to
    // rewrite.  If the code doesn't have calls or unwinds, we know there is
    // nothing to rewrite.
    if (!InlinedCodeInfo.ContainsCalls) {
      // Now that everything is happy, we have one final detail.  The PHI nodes in
      // the exception destination block still have entries due to the original
      // invoke instruction.  Eliminate these entries (which might even delete the
      // PHI node) now.
      InvokeDest->removePredecessor(II->getParent());
      return;
    }
  
    InvokeInliningInfo Invoke(II);
    
    for (Function::iterator BB = FirstNewBlock, E = Caller->end(); BB != E; ++BB){
      if (InlinedCodeInfo.ContainsCalls)
        if (HandleCallsInBlockInlinedThroughInvoke(BB, Invoke)) {
          // Honor a request to skip the next block.
          ++BB;
          continue;
        }
  
      if (ResumeInst *RI = dyn_cast<ResumeInst>(BB->getTerminator()))
        Invoke.forwardResume(RI);
    }
  
    // Now that everything is happy, we have one final detail.  The PHI nodes in
    // the exception destination block still have entries due to the original
    // invoke instruction.  Eliminate these entries (which might even delete the
    // PHI node) now.
    InvokeDest->removePredecessor(II->getParent());
  }
  
  /// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee
  /// into the caller, update the specified callgraph to reflect the changes we
  /// made.  Note that it's possible that not all code was copied over, so only
  /// some edges of the callgraph may remain.
  static void UpdateCallGraphAfterInlining(CallSite CS,
                                           Function::iterator FirstNewBlock,
                                           ValueToValueMapTy &VMap,
                                           InlineFunctionInfo &IFI) {
    CallGraph &CG = *IFI.CG;
    const Function *Caller = CS.getInstruction()->getParent()->getParent();
    const Function *Callee = CS.getCalledFunction();
    CallGraphNode *CalleeNode = CG[Callee];
    CallGraphNode *CallerNode = CG[Caller];
  
    // Since we inlined some uninlined call sites in the callee into the caller,
    // add edges from the caller to all of the callees of the callee.
    CallGraphNode::iterator I = CalleeNode->begin(), E = CalleeNode->end();
  
    // Consider the case where CalleeNode == CallerNode.
    CallGraphNode::CalledFunctionsVector CallCache;
    if (CalleeNode == CallerNode) {
      CallCache.assign(I, E);
      I = CallCache.begin();
      E = CallCache.end();
    }
  
    for (; I != E; ++I) {
      const Value *OrigCall = I->first;
  
      ValueToValueMapTy::iterator VMI = VMap.find(OrigCall);
      // Only copy the edge if the call was inlined!
      if (VMI == VMap.end() || VMI->second == 0)
        continue;
      
      // If the call was inlined, but then constant folded, there is no edge to
      // add.  Check for this case.
      Instruction *NewCall = dyn_cast<Instruction>(VMI->second);
      if (NewCall == 0) continue;
  
      // Remember that this call site got inlined for the client of
      // InlineFunction.
      IFI.InlinedCalls.push_back(NewCall);
  
      // It's possible that inlining the callsite will cause it to go from an
      // indirect to a direct call by resolving a function pointer.  If this
      // happens, set the callee of the new call site to a more precise
      // destination.  This can also happen if the call graph node of the caller
      // was just unnecessarily imprecise.
      if (I->second->getFunction() == 0)
        if (Function *F = CallSite(NewCall).getCalledFunction()) {
          // Indirect call site resolved to direct call.
          CallerNode->addCalledFunction(CallSite(NewCall), CG[F]);
  
          continue;
        }
  
      CallerNode->addCalledFunction(CallSite(NewCall), I->second);
    }
    
    // Update the call graph by deleting the edge from Callee to Caller.  We must
    // do this after the loop above in case Caller and Callee are the same.
    CallerNode->removeCallEdgeFor(CS);
  }
  
  /// HandleByValArgument - When inlining a call site that has a byval argument,
  /// we have to make the implicit memcpy explicit by adding it.
  static Value *HandleByValArgument(Value *Arg, Instruction *TheCall,
                                    const Function *CalledFunc,
                                    InlineFunctionInfo &IFI,
                                    unsigned ByValAlignment) {
    Type *AggTy = cast<PointerType>(Arg->getType())->getElementType();
  
    // If the called function is readonly, then it could not mutate the caller's
    // copy of the byval'd memory.  In this case, it is safe to elide the copy and
    // temporary.
    if (CalledFunc->onlyReadsMemory()) {
      // If the byval argument has a specified alignment that is greater than the
      // passed in pointer, then we either have to round up the input pointer or
      // give up on this transformation.
      if (ByValAlignment <= 1)  // 0 = unspecified, 1 = no particular alignment.
        return Arg;
  
      // If the pointer is already known to be sufficiently aligned, or if we can
      // round it up to a larger alignment, then we don't need a temporary.
      if (getOrEnforceKnownAlignment(Arg, ByValAlignment,
                                     IFI.TD) >= ByValAlignment)
        return Arg;
      
      // Otherwise, we have to make a memcpy to get a safe alignment.  This is bad
      // for code quality, but rarely happens and is required for correctness.
    }
    
    LLVMContext &Context = Arg->getContext();
  
    Type *VoidPtrTy = Type::getInt8PtrTy(Context);
    
    // Create the alloca.  If we have TargetData, use nice alignment.
    unsigned Align = 1;
    if (IFI.TD)
      Align = IFI.TD->getPrefTypeAlignment(AggTy);
    
    // If the byval had an alignment specified, we *must* use at least that
    // alignment, as it is required by the byval argument (and uses of the
    // pointer inside the callee).
    Align = std::max(Align, ByValAlignment);
    
    Function *Caller = TheCall->getParent()->getParent(); 
    
    Value *NewAlloca = new AllocaInst(AggTy, 0, Align, Arg->getName(), 
                                      &*Caller->begin()->begin());
    // Emit a memcpy.
    Type *Tys[3] = {VoidPtrTy, VoidPtrTy, Type::getInt64Ty(Context)};
    Function *MemCpyFn = Intrinsic::getDeclaration(Caller->getParent(),
                                                   Intrinsic::memcpy, 
                                                   Tys);
    Value *DestCast = new BitCastInst(NewAlloca, VoidPtrTy, "tmp", TheCall);
    Value *SrcCast = new BitCastInst(Arg, VoidPtrTy, "tmp", TheCall);
    
    Value *Size;
    if (IFI.TD == 0)
      Size = ConstantExpr::getSizeOf(AggTy);
    else
      Size = ConstantInt::get(Type::getInt64Ty(Context),
                              IFI.TD->getTypeStoreSize(AggTy));
    
    // Always generate a memcpy of alignment 1 here because we don't know
    // the alignment of the src pointer.  Other optimizations can infer
    // better alignment.
    Value *CallArgs[] = {
      DestCast, SrcCast, Size,
      ConstantInt::get(Type::getInt32Ty(Context), 1),
      ConstantInt::getFalse(Context) // isVolatile
    };
    IRBuilder<>(TheCall).CreateCall(MemCpyFn, CallArgs);
    
    // Uses of the argument in the function should use our new alloca
    // instead.
    return NewAlloca;
  }
  
  // isUsedByLifetimeMarker - Check whether this Value is used by a lifetime
  // intrinsic.
  static bool isUsedByLifetimeMarker(Value *V) {
    for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
         ++UI) {
      if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI)) {
        switch (II->getIntrinsicID()) {
        default: break;
        case Intrinsic::lifetime_start:
        case Intrinsic::lifetime_end:
          return true;
        }
      }
    }
    return false;
  }
  
  // hasLifetimeMarkers - Check whether the given alloca already has
  // lifetime.start or lifetime.end intrinsics.
  static bool hasLifetimeMarkers(AllocaInst *AI) {
    Type *Int8PtrTy = Type::getInt8PtrTy(AI->getType()->getContext());
    if (AI->getType() == Int8PtrTy)
      return isUsedByLifetimeMarker(AI);
  
    // Do a scan to find all the casts to i8*.
    for (Value::use_iterator I = AI->use_begin(), E = AI->use_end(); I != E;
         ++I) {
      if (I->getType() != Int8PtrTy) continue;
      if (I->stripPointerCasts() != AI) continue;
      if (isUsedByLifetimeMarker(*I))
        return true;
    }
    return false;
  }
  
  /// updateInlinedAtInfo - Helper function used by fixupLineNumbers to
  /// recursively update InlinedAtEntry of a DebugLoc.
  static DebugLoc updateInlinedAtInfo(const DebugLoc &DL, 
                                      const DebugLoc &InlinedAtDL,
                                      LLVMContext &Ctx) {
    if (MDNode *IA = DL.getInlinedAt(Ctx)) {
      DebugLoc NewInlinedAtDL 
        = updateInlinedAtInfo(DebugLoc::getFromDILocation(IA), InlinedAtDL, Ctx);
      return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx),
                           NewInlinedAtDL.getAsMDNode(Ctx));
    }
  
    return DebugLoc::get(DL.getLine(), DL.getCol(), DL.getScope(Ctx),
                         InlinedAtDL.getAsMDNode(Ctx));
  }
  
  /// fixupLineNumbers - Update inlined instructions' line numbers to 
  /// to encode location where these instructions are inlined.
  static void fixupLineNumbers(Function *Fn, Function::iterator FI,
                               Instruction *TheCall) {
    DebugLoc TheCallDL = TheCall->getDebugLoc();
    if (TheCallDL.isUnknown())
      return;
  
    for (; FI != Fn->end(); ++FI) {
      for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
           BI != BE; ++BI) {
        DebugLoc DL = BI->getDebugLoc();
        if (!DL.isUnknown()) {
          BI->setDebugLoc(updateInlinedAtInfo(DL, TheCallDL, BI->getContext()));
          if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI)) {
            LLVMContext &Ctx = BI->getContext();
            MDNode *InlinedAt = BI->getDebugLoc().getInlinedAt(Ctx);
            DVI->setOperand(2, createInlinedVariable(DVI->getVariable(), 
                                                     InlinedAt, Ctx));
          }
        }
      }
    }
  }
  
  /// 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) {
        Value *ActualArg = *AI;
  
        // When byval arguments actually inlined, we need to make the copy implied
        // by them explicit.  However, we don't do this if the callee is readonly
        // or readnone, because the copy would be unneeded: the callee doesn't
        // modify the struct.
        if (CS.isByValArgument(ArgNo)) {
          ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI,
                                          CalledFunc->getParamAlignment(ArgNo+1));
   
          // Calls that we inline may use the new alloca, so we need to clear
          // their 'tail' flags if HandleByValArgument introduced a new alloca and
          // the callee has calls.
          MustClearTailCallFlags |= ActualArg != *AI;
        }
  
        VMap[I] = ActualArg;
      }
  
      // We want the inliner to prune the code as it copies.  We would LOVE to
      // have no dead or constant instructions leftover after inlining occurs
      // (which can happen, e.g., because an argument was constant), but we'll be
      // happy with whatever the cloner can do.
      CloneAndPruneFunctionInto(Caller, CalledFunc, VMap, 
                                /*ModuleLevelChanges=*/false, Returns, ".i",
                                &InlinedFunctionInfo, IFI.TD, TheCall);
  
      // Remember the first block that is newly cloned over.
      FirstNewBlock = LastBlock; ++FirstNewBlock;
  
      // Update the callgraph if requested.
      if (IFI.CG)
        UpdateCallGraphAfterInlining(CS, FirstNewBlock, VMap, IFI);
  
      // Update inlined instructions' line number information.
      fixupLineNumbers(Caller, FirstNewBlock, TheCall);
    }
  
    // If there are any alloca instructions in the block that used to be the entry
    // block for the callee, move them to the entry block of the caller.  First
    // calculate which instruction they should be inserted before.  We insert the
    // instructions at the end of the current alloca list.
    {
      BasicBlock::iterator InsertPoint = Caller->begin()->begin();
      for (BasicBlock::iterator I = FirstNewBlock->begin(),
           E = FirstNewBlock->end(); I != E; ) {
        AllocaInst *AI = dyn_cast<AllocaInst>(I++);
        if (AI == 0) continue;
        
        // If the alloca is now dead, remove it.  This often occurs due to code
        // specialization.
        if (AI->use_empty()) {
          AI->eraseFromParent();
          continue;
        }
  
        if (!isa<Constant>(AI->getArraySize()))
          continue;
        
        // Keep track of the static allocas that we inline into the caller.
        IFI.StaticAllocas.push_back(AI);
        
        // Scan for the block of allocas that we can move over, and move them
        // all at once.
        while (isa<AllocaInst>(I) &&
               isa<Constant>(cast<AllocaInst>(I)->getArraySize())) {
          IFI.StaticAllocas.push_back(cast<AllocaInst>(I));
          ++I;
        }
  
        // Transfer all of the allocas over in a block.  Using splice means
        // that the instructions aren't removed from the symbol table, then
        // reinserted.
        Caller->getEntryBlock().getInstList().splice(InsertPoint,
                                                     FirstNewBlock->getInstList(),
                                                     AI, I);
      }
    }
  
    // Leave lifetime markers for the static alloca's, scoping them to the
    // function we just inlined.
    if (InsertLifetime && !IFI.StaticAllocas.empty()) {
      IRBuilder<> builder(FirstNewBlock->begin());
      for (unsigned ai = 0, ae = IFI.StaticAllocas.size(); ai != ae; ++ai) {
        AllocaInst *AI = IFI.StaticAllocas[ai];
  
        // If the alloca is already scoped to something smaller than the whole
        // function then there's no need to add redundant, less accurate markers.
        if (hasLifetimeMarkers(AI))
          continue;
  
        builder.CreateLifetimeStart(AI);
        for (unsigned ri = 0, re = Returns.size(); ri != re; ++ri) {
          IRBuilder<> builder(Returns[ri]);
          builder.CreateLifetimeEnd(AI);
        }
      }
    }
  
    // If the inlined code contained dynamic alloca instructions, wrap the inlined
    // code with llvm.stacksave/llvm.stackrestore intrinsics.
    if (InlinedFunctionInfo.ContainsDynamicAllocas) {
      Module *M = Caller->getParent();
      // Get the two intrinsics we care about.
      Function *StackSave = Intrinsic::getDeclaration(M, Intrinsic::stacksave);
      Function *StackRestore=Intrinsic::getDeclaration(M,Intrinsic::stackrestore);
  
      // Insert the llvm.stacksave.
      CallInst *SavedPtr = IRBuilder<>(FirstNewBlock, FirstNewBlock->begin())
        .CreateCall(StackSave, "savedstack");
  
      // Insert a call to llvm.stackrestore before any return instructions in the
      // inlined function.
      for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
        IRBuilder<>(Returns[i]).CreateCall(StackRestore, SavedPtr);
      }
    }
  
    // If we are inlining tail call instruction through a call site that isn't
    // marked 'tail', we must remove the tail marker for any calls in the inlined
    // code.  Also, calls inlined through a 'nounwind' call site should be marked
    // 'nounwind'.
    if (InlinedFunctionInfo.ContainsCalls &&
        (MustClearTailCallFlags || MarkNoUnwind)) {
      for (Function::iterator BB = FirstNewBlock, E = Caller->end();
           BB != E; ++BB)
        for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
          if (CallInst *CI = dyn_cast<CallInst>(I)) {
            if (MustClearTailCallFlags)
              CI->setTailCall(false);
            if (MarkNoUnwind)
              CI->setDoesNotThrow();
          }
    }
  
    // If we are inlining for an invoke instruction, we must make sure to rewrite
    // any call instructions into invoke instructions.
    if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
      HandleInlinedInvoke(II, FirstNewBlock, InlinedFunctionInfo);
  
    // If we cloned in _exactly one_ basic block, and if that block ends in a
    // return instruction, we splice the body of the inlined callee directly into
    // the calling basic block.
    if (Returns.size() == 1 && std::distance(FirstNewBlock, Caller->end()) == 1) {
      // Move all of the instructions right before the call.
      OrigBB->getInstList().splice(TheCall, FirstNewBlock->getInstList(),
                                   FirstNewBlock->begin(), FirstNewBlock->end());
      // Remove the cloned basic block.
      Caller->getBasicBlockList().pop_back();
  
      // If the call site was an invoke instruction, add a branch to the normal
      // destination.
      if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall))
        BranchInst::Create(II->getNormalDest(), TheCall);
  
      // If the return instruction returned a value, replace uses of the call with
      // uses of the returned value.
      if (!TheCall->use_empty()) {
        ReturnInst *R = Returns[0];
        if (TheCall == R->getReturnValue())
          TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
        else
          TheCall->replaceAllUsesWith(R->getReturnValue());
      }
      // Since we are now done with the Call/Invoke, we can delete it.
      TheCall->eraseFromParent();
  
      // Since we are now done with the return instruction, delete it also.
      Returns[0]->eraseFromParent();
  
      // We are now done with the inlining.
      return true;
    }
  
    // Otherwise, we have the normal case, of more than one block to inline or
    // multiple return sites.
  
    // We want to clone the entire callee function into the hole between the
    // "starter" and "ender" blocks.  How we accomplish this depends on whether
    // this is an invoke instruction or a call instruction.
    BasicBlock *AfterCallBB;
    if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
  
      // Add an unconditional branch to make this look like the CallInst case...
      BranchInst *NewBr = BranchInst::Create(II->getNormalDest(), TheCall);
  
      // Split the basic block.  This guarantees that no PHI nodes will have to be
      // updated due to new incoming edges, and make the invoke case more
      // symmetric to the call case.
      AfterCallBB = OrigBB->splitBasicBlock(NewBr,
                                            CalledFunc->getName()+".exit");
  
    } else {  // It's a call
      // If this is a call instruction, we need to split the basic block that
      // the call lives in.
      //
      AfterCallBB = OrigBB->splitBasicBlock(TheCall,
                                            CalledFunc->getName()+".exit");
    }
  
    // Change the branch that used to go to AfterCallBB to branch to the first
    // basic block of the inlined function.
    //
    TerminatorInst *Br = OrigBB->getTerminator();
    assert(Br && Br->getOpcode() == Instruction::Br &&
           "splitBasicBlock broken!");
    Br->setOperand(0, FirstNewBlock);
  
  
    // Now that the function is correct, make it a little bit nicer.  In
    // particular, move the basic blocks inserted from the end of the function
    // into the space made by splitting the source basic block.
    Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(),
                                       FirstNewBlock, Caller->end());
  
    // Handle all of the return instructions that we just cloned in, and eliminate
    // any users of the original call/invoke instruction.
    Type *RTy = CalledFunc->getReturnType();
  
    PHINode *PHI = 0;
    if (Returns.size() > 1) {
      // The PHI node should go at the front of the new basic block to merge all
      // possible incoming values.
      if (!TheCall->use_empty()) {
        PHI = PHINode::Create(RTy, Returns.size(), TheCall->getName(),
                              AfterCallBB->begin());
        // Anything that used the result of the function call should now use the
        // PHI node as their operand.
        TheCall->replaceAllUsesWith(PHI);
      }
  
      // Loop over all of the return instructions adding entries to the PHI node
      // as appropriate.
      if (PHI) {
        for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
          ReturnInst *RI = Returns[i];
          assert(RI->getReturnValue()->getType() == PHI->getType() &&
                 "Ret value not consistent in function!");
          PHI->addIncoming(RI->getReturnValue(), RI->getParent());
        }
      }
  
  
      // Add a branch to the merge points and remove return instructions.
      for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
        ReturnInst *RI = Returns[i];
        BranchInst::Create(AfterCallBB, RI);
        RI->eraseFromParent();
      }
    } else if (!Returns.empty()) {
      // Otherwise, if there is exactly one return value, just replace anything
      // using the return value of the call with the computed value.
      if (!TheCall->use_empty()) {
        if (TheCall == Returns[0]->getReturnValue())
          TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
        else
          TheCall->replaceAllUsesWith(Returns[0]->getReturnValue());
      }
  
      // Update PHI nodes that use the ReturnBB to use the AfterCallBB.
      BasicBlock *ReturnBB = Returns[0]->getParent();
      ReturnBB->replaceAllUsesWith(AfterCallBB);
  
      // Splice the code from the return block into the block that it will return
      // to, which contains the code that was after the call.
      AfterCallBB->getInstList().splice(AfterCallBB->begin(),
                                        ReturnBB->getInstList());
  
      // Delete the return instruction now and empty ReturnBB now.
      Returns[0]->eraseFromParent();
      ReturnBB->eraseFromParent();
    } else if (!TheCall->use_empty()) {
      // No returns, but something is using the return value of the call.  Just
      // nuke the result.
      TheCall->replaceAllUsesWith(UndefValue::get(TheCall->getType()));
    }
  
    // Since we are now done with the Call/Invoke, we can delete it.
    TheCall->eraseFromParent();
  
    // We should always be able to fold the entry block of the function into the
    // single predecessor of the block...
    assert(cast<BranchInst>(Br)->isUnconditional() && "splitBasicBlock broken!");
    BasicBlock *CalleeEntry = cast<BranchInst>(Br)->getSuccessor(0);
  
    // Splice the code entry block into calling block, right before the
    // unconditional branch.
    CalleeEntry->replaceAllUsesWith(OrigBB);  // Update PHI nodes
    OrigBB->getInstList().splice(Br, CalleeEntry->getInstList());
  
    // Remove the unconditional branch.
    OrigBB->getInstList().erase(Br);
  
    // Now we can remove the CalleeEntry block, which is now empty.
    Caller->getBasicBlockList().erase(CalleeEntry);
  
    // If we inserted a phi node, check to see if it has a single value (e.g. all
    // the entries are the same or undef).  If so, remove the PHI so it doesn't
    // block other optimizations.
    if (PHI) {
      if (Value *V = SimplifyInstruction(PHI, IFI.TD)) {
        PHI->replaceAllUsesWith(V);
        PHI->eraseFromParent();
      }
    }
  
    return true;
  }
  