MFC 261991:

Upgrade our copy of llvm/clang to 3.4 release.  This version supports
all of the features in the current working draft of the upcoming C++
standard, provisionally named C++1y.

The code generator's performance is greatly increased, and the loop
auto-vectorizer is now enabled at -Os and -O2 in addition to -O3.  The
PowerPC backend has made several major improvements to code generation
quality and compile time, and the X86, SPARC, ARM32, Aarch64 and SystemZ
backends have all seen major feature work.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.4/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html>

MFC 262121 (by emaste):

Update lldb for clang/llvm 3.4 import

This commit largely restores the lldb source to the upstream r196259
snapshot with the addition of threaded inferior support and a few bug
fixes.

Specific upstream lldb revisions restored include:
   SVN      git
  181387  779e6ac
  181703  7bef4e2
  182099  b31044e
  182650  f2dcf35
  182683  0d91b80
  183862  15c1774
  183929  99447a6
  184177  0b2934b
  184948  4dc3761
  184954  007e7bc
  186990  eebd175

Sponsored by:	DARPA, AFRL

MFC 262186 (by emaste):

Fix mismerge in r262121

A break statement was lost in the merge.  The error had no functional
impact, but restore it to reduce the diff against upstream.

MFC 262303:

Pull in r197521 from upstream clang trunk (by rdivacky):

  Use the integrated assembler by default on FreeBSD/ppc and ppc64.

Requested by:	jhibbits

MFC 262611:

Pull in r196874 from upstream llvm trunk:

  Fix a crash that occurs when PWD is invalid.

  MCJIT needs to be able to run in hostile environments, even when PWD
  is invalid. There's no need to crash MCJIT in this case.

  The obvious fix is to simply leave MCContext's CompilationDir empty
  when PWD can't be determined. This way, MCJIT clients,
  and other clients that link with LLVM don't need a valid working directory.

  If we do want to guarantee valid CompilationDir, that should be done
  only for clients of getCompilationDir(). This is as simple as checking
  for an empty string.

  The only current use of getCompilationDir is EmitGenDwarfInfo, which
  won't conceivably run with an invalid working dir. However, in the
  purely hypothetically and untestable case that this happens, the
  AT_comp_dir will be omitted from the compilation_unit DIE.

This should help fix assertions occurring with ports-mgmt/tinderbox,
when it is using jails, and sometimes invalidates clang's current
working directory.

Reported by:	decke

MFC 262809:

Pull in r203007 from upstream clang trunk:

  Don't produce an alias between destructors with different calling conventions.

  Fixes pr19007.

(Please note that is an LLVM PR identifier, not a FreeBSD one.)

This should fix Firefox and/or libxul crashes (due to problems with
regparm/stdcall calling conventions) on i386.

Reported by:	multiple users on freebsd-current
PR:		bin/187103

MFC 263048:

Repair recognition of "CC" as an alias for the C++ compiler, since it
was silently broken by upstream for a Windows-specific use-case.

Apparently some versions of CMake still rely on this archaic feature...

Reported by:	rakuco

MFC 263049:

Garbage collect the old way of adding the libstdc++ include directories
in clang's InitHeaderSearch.cpp.  This has been superseded by David
Chisnall's commit in r255321.

Moreover, if libc++ is used, the libstdc++ include directories should
not be in the search path at all.  These directories are now only used
if you pass -stdlib=libstdc++.

1 files changed, 226 insertions, 26 deletions

diff --git a/contrib/llvm/lib/Transforms/Scalar/GVN.cpp b/contrib/llvm/lib/Transforms/Scalar/GVN.cpp
index f350b9b..6af269d 100644
--- a/contrib/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/contrib/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -21,8 +21,10 @@
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/CFG.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/Dominators.h"
 #include "llvm/Analysis/InstructionSimplify.h"
@@ -45,6 +47,7 @@
 #include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
+#include <vector>
 using namespace llvm;
 using namespace PatternMatch;
 
@@ -505,7 +508,9 @@ namespace {
     enum ValType {
       SimpleVal,  // A simple offsetted value that is accessed.
       LoadVal,    // A value produced by a load.
-      MemIntrin   // A memory intrinsic which is loaded from.
+      MemIntrin,  // A memory intrinsic which is loaded from.
+      UndefVal    // A UndefValue representing a value from dead block (which
+                  // is not yet physically removed from the CFG). 
     };
   
     /// V - The value that is live out of the block.
@@ -543,10 +548,20 @@ namespace {
       Res.Offset = Offset;
       return Res;
     }
-  
+
+    static AvailableValueInBlock getUndef(BasicBlock *BB) {
+      AvailableValueInBlock Res;
+      Res.BB = BB;
+      Res.Val.setPointer(0);
+      Res.Val.setInt(UndefVal);
+      Res.Offset = 0;
+      return Res;
+    }
+
     bool isSimpleValue() const { return Val.getInt() == SimpleVal; }
     bool isCoercedLoadValue() const { return Val.getInt() == LoadVal; }
     bool isMemIntrinValue() const { return Val.getInt() == MemIntrin; }
+    bool isUndefValue() const { return Val.getInt() == UndefVal; }
   
     Value *getSimpleValue() const {
       assert(isSimpleValue() && "Wrong accessor");
@@ -574,6 +589,7 @@ namespace {
     DominatorTree *DT;
     const DataLayout *TD;
     const TargetLibraryInfo *TLI;
+    SetVector<BasicBlock *> DeadBlocks;
 
     ValueTable VN;
 
@@ -692,9 +708,13 @@ namespace {
     void cleanupGlobalSets();
     void verifyRemoved(const Instruction *I) const;
     bool splitCriticalEdges();
+    BasicBlock *splitCriticalEdges(BasicBlock *Pred, BasicBlock *Succ);
     unsigned replaceAllDominatedUsesWith(Value *From, Value *To,
                                          const BasicBlockEdge &Root);
     bool propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root);
+    bool processFoldableCondBr(BranchInst *BI);
+    void addDeadBlock(BasicBlock *BB);
+    void assignValNumForDeadCode();
   };
 
   char GVN::ID = 0;
@@ -1068,14 +1088,15 @@ static int AnalyzeLoadFromClobberingMemInst(Type *LoadTy, Value *LoadPtr,
   if (Offset == -1)
     return Offset;
 
+  unsigned AS = Src->getType()->getPointerAddressSpace();
   // Otherwise, see if we can constant fold a load from the constant with the
   // offset applied as appropriate.
   Src = ConstantExpr::getBitCast(Src,
-                                 llvm::Type::getInt8PtrTy(Src->getContext()));
+                                 Type::getInt8PtrTy(Src->getContext(), AS));
   Constant *OffsetCst =
     ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
   Src = ConstantExpr::getGetElementPtr(Src, OffsetCst);
-  Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
+  Src = ConstantExpr::getBitCast(Src, PointerType::get(LoadTy, AS));
   if (ConstantFoldLoadFromConstPtr(Src, &TD))
     return Offset;
   return -1;
@@ -1152,7 +1173,7 @@ static Value *GetLoadValueForLoad(LoadInst *SrcVal, unsigned Offset,
     Type *DestPTy =
       IntegerType::get(LoadTy->getContext(), NewLoadSize*8);
     DestPTy = PointerType::get(DestPTy,
-                       cast<PointerType>(PtrVal->getType())->getAddressSpace());
+                               PtrVal->getType()->getPointerAddressSpace());
     Builder.SetCurrentDebugLocation(SrcVal->getDebugLoc());
     PtrVal = Builder.CreateBitCast(PtrVal, DestPTy);
     LoadInst *NewLoad = Builder.CreateLoad(PtrVal);
@@ -1227,15 +1248,16 @@ static Value *GetMemInstValueForLoad(MemIntrinsic *SrcInst, unsigned Offset,
   // Otherwise, this is a memcpy/memmove from a constant global.
   MemTransferInst *MTI = cast<MemTransferInst>(SrcInst);
   Constant *Src = cast<Constant>(MTI->getSource());
+  unsigned AS = Src->getType()->getPointerAddressSpace();
 
   // Otherwise, see if we can constant fold a load from the constant with the
   // offset applied as appropriate.
   Src = ConstantExpr::getBitCast(Src,
-                                 llvm::Type::getInt8PtrTy(Src->getContext()));
+                                 Type::getInt8PtrTy(Src->getContext(), AS));
   Constant *OffsetCst =
-  ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
+    ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
   Src = ConstantExpr::getGetElementPtr(Src, OffsetCst);
-  Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
+  Src = ConstantExpr::getBitCast(Src, PointerType::get(LoadTy, AS));
   return ConstantFoldLoadFromConstPtr(Src, &TD);
 }
 
@@ -1250,8 +1272,10 @@ static Value *ConstructSSAForLoadSet(LoadInst *LI,
   // just use the dominating value directly.
   if (ValuesPerBlock.size() == 1 &&
       gvn.getDominatorTree().properlyDominates(ValuesPerBlock[0].BB,
-                                               LI->getParent()))
+                                               LI->getParent())) {
+    assert(!ValuesPerBlock[0].isUndefValue() && "Dead BB dominate this block");
     return ValuesPerBlock[0].MaterializeAdjustedValue(LI->getType(), gvn);
+  }
 
   // Otherwise, we have to construct SSA form.
   SmallVector<PHINode*, 8> NewPHIs;
@@ -1321,7 +1345,7 @@ Value *AvailableValueInBlock::MaterializeAdjustedValue(Type *LoadTy, GVN &gvn) c
                    << *getCoercedLoadValue() << '\n'
                    << *Res << '\n' << "\n\n\n");
     }
-  } else {
+  } else if (isMemIntrinValue()) {
     const DataLayout *TD = gvn.getDataLayout();
     assert(TD && "Need target data to handle type mismatch case");
     Res = GetMemInstValueForLoad(getMemIntrinValue(), Offset,
@@ -1329,6 +1353,10 @@ Value *AvailableValueInBlock::MaterializeAdjustedValue(Type *LoadTy, GVN &gvn) c
     DEBUG(dbgs() << "GVN COERCED NONLOCAL MEM INTRIN:\nOffset: " << Offset
                  << "  " << *getMemIntrinValue() << '\n'
                  << *Res << '\n' << "\n\n\n");
+  } else {
+    assert(isUndefValue() && "Should be UndefVal");
+    DEBUG(dbgs() << "GVN COERCED NONLOCAL Undef:\n";);
+    return UndefValue::get(LoadTy);
   }
   return Res;
 }
@@ -1352,6 +1380,13 @@ void GVN::AnalyzeLoadAvailability(LoadInst *LI, LoadDepVect &Deps,
     BasicBlock *DepBB = Deps[i].getBB();
     MemDepResult DepInfo = Deps[i].getResult();
 
+    if (DeadBlocks.count(DepBB)) {
+      // Dead dependent mem-op disguise as a load evaluating the same value
+      // as the load in question.
+      ValuesPerBlock.push_back(AvailableValueInBlock::getUndef(DepBB));
+      continue;
+    }
+
     if (!DepInfo.isDef() && !DepInfo.isClobber()) {
       UnavailableBlocks.push_back(DepBB);
       continue;
@@ -1513,7 +1548,7 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
   for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
     FullyAvailableBlocks[UnavailableBlocks[i]] = false;
 
-  SmallVector<std::pair<TerminatorInst*, unsigned>, 4> NeedToSplit;
+  SmallVector<BasicBlock *, 4> CriticalEdgePred;
   for (pred_iterator PI = pred_begin(LoadBB), E = pred_end(LoadBB);
        PI != E; ++PI) {
     BasicBlock *Pred = *PI;
@@ -1536,20 +1571,14 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
         return false;
       }
 
-      unsigned SuccNum = GetSuccessorNumber(Pred, LoadBB);
-      NeedToSplit.push_back(std::make_pair(Pred->getTerminator(), SuccNum));
+      CriticalEdgePred.push_back(Pred);
     }
   }
 
-  if (!NeedToSplit.empty()) {
-    toSplit.append(NeedToSplit.begin(), NeedToSplit.end());
-    return false;
-  }
-
   // Decide whether PRE is profitable for this load.
   unsigned NumUnavailablePreds = PredLoads.size();
   assert(NumUnavailablePreds != 0 &&
-         "Fully available value should be eliminated above!");
+         "Fully available value should already be eliminated!");
 
   // If this load is unavailable in multiple predecessors, reject it.
   // FIXME: If we could restructure the CFG, we could make a common pred with
@@ -1558,6 +1587,17 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
   if (NumUnavailablePreds != 1)
       return false;
 
+  // Split critical edges, and update the unavailable predecessors accordingly.
+  for (SmallVectorImpl<BasicBlock *>::iterator I = CriticalEdgePred.begin(),
+         E = CriticalEdgePred.end(); I != E; I++) {
+    BasicBlock *OrigPred = *I;
+    BasicBlock *NewPred = splitCriticalEdges(OrigPred, LoadBB);
+    PredLoads.erase(OrigPred);
+    PredLoads[NewPred] = 0;
+    DEBUG(dbgs() << "Split critical edge " << OrigPred->getName() << "->"
+                 << LoadBB->getName() << '\n');
+  }
+
   // Check if the load can safely be moved to all the unavailable predecessors.
   bool CanDoPRE = true;
   SmallVector<Instruction*, 8> NewInsts;
@@ -1594,7 +1634,9 @@ bool GVN::PerformLoadPRE(LoadInst *LI, AvailValInBlkVect &ValuesPerBlock,
       if (MD) MD->removeInstruction(I);
       I->eraseFromParent();
     }
-    return false;
+    // HINT:Don't revert the edge-splitting as following transformation may 
+    // also need to split these critial edges.
+    return !CriticalEdgePred.empty();
   }
 
   // Okay, we can eliminate this load by inserting a reload in the predecessor
@@ -2181,11 +2223,13 @@ bool GVN::processInstruction(Instruction *I) {
   // For conditional branches, we can perform simple conditional propagation on
   // the condition value itself.
   if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
-    if (!BI->isConditional() || isa<Constant>(BI->getCondition()))
+    if (!BI->isConditional())
       return false;
 
-    Value *BranchCond = BI->getCondition();
+    if (isa<Constant>(BI->getCondition()))
+      return processFoldableCondBr(BI);
 
+    Value *BranchCond = BI->getCondition();
     BasicBlock *TrueSucc = BI->getSuccessor(0);
     BasicBlock *FalseSucc = BI->getSuccessor(1);
     // Avoid multiple edges early.
@@ -2297,25 +2341,30 @@ bool GVN::runOnFunction(Function& F) {
   while (ShouldContinue) {
     DEBUG(dbgs() << "GVN iteration: " << Iteration << "\n");
     ShouldContinue = iterateOnFunction(F);
-    if (splitCriticalEdges())
-      ShouldContinue = true;
     Changed |= ShouldContinue;
     ++Iteration;
   }
 
   if (EnablePRE) {
+    // Fabricate val-num for dead-code in order to suppress assertion in
+    // performPRE().
+    assignValNumForDeadCode();
     bool PREChanged = true;
     while (PREChanged) {
       PREChanged = performPRE(F);
       Changed |= PREChanged;
     }
   }
+
   // FIXME: Should perform GVN again after PRE does something.  PRE can move
   // computations into blocks where they become fully redundant.  Note that
   // we can't do this until PRE's critical edge splitting updates memdep.
   // Actually, when this happens, we should just fully integrate PRE into GVN.
 
   cleanupGlobalSets();
+  // Do not cleanup DeadBlocks in cleanupGlobalSets() as it's called for each
+  // iteration. 
+  DeadBlocks.clear();
 
   return Changed;
 }
@@ -2326,6 +2375,9 @@ bool GVN::processBlock(BasicBlock *BB) {
   // (and incrementing BI before processing an instruction).
   assert(InstrsToErase.empty() &&
          "We expect InstrsToErase to be empty across iterations");
+  if (DeadBlocks.count(BB))
+    return false;
+
   bool ChangedFunction = false;
 
   for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
@@ -2344,7 +2396,7 @@ bool GVN::processBlock(BasicBlock *BB) {
     if (!AtStart)
       --BI;
 
-    for (SmallVector<Instruction*, 4>::iterator I = InstrsToErase.begin(),
+    for (SmallVectorImpl<Instruction *>::iterator I = InstrsToErase.begin(),
          E = InstrsToErase.end(); I != E; ++I) {
       DEBUG(dbgs() << "GVN removed: " << **I << '\n');
       if (MD) MD->removeInstruction(*I);
@@ -2543,6 +2595,15 @@ bool GVN::performPRE(Function &F) {
   return Changed;
 }
 
+/// Split the critical edge connecting the given two blocks, and return
+/// the block inserted to the critical edge.
+BasicBlock *GVN::splitCriticalEdges(BasicBlock *Pred, BasicBlock *Succ) {
+  BasicBlock *BB = SplitCriticalEdge(Pred, Succ, this);
+  if (MD)
+    MD->invalidateCachedPredecessors();
+  return BB;
+}
+
 /// splitCriticalEdges - Split critical edges found during the previous
 /// iteration that may enable further optimization.
 bool GVN::splitCriticalEdges() {
@@ -2569,9 +2630,18 @@ bool GVN::iterateOnFunction(Function &F) {
        RE = RPOT.end(); RI != RE; ++RI)
     Changed |= processBlock(*RI);
 #else
+  // Save the blocks this function have before transformation begins. GVN may
+  // split critical edge, and hence may invalidate the RPO/DT iterator.
+  //
+  std::vector<BasicBlock *> BBVect;
+  BBVect.reserve(256);
   for (df_iterator<DomTreeNode*> DI = df_begin(DT->getRootNode()),
        DE = df_end(DT->getRootNode()); DI != DE; ++DI)
-    Changed |= processBlock(DI->getBlock());
+    BBVect.push_back(DI->getBlock());
+
+  for (std::vector<BasicBlock *>::iterator I = BBVect.begin(), E = BBVect.end();
+       I != E; I++)
+    Changed |= processBlock(*I);
 #endif
 
   return Changed;
@@ -2601,3 +2671,133 @@ void GVN::verifyRemoved(const Instruction *Inst) const {
     }
   }
 }
+
+// BB is declared dead, which implied other blocks become dead as well. This
+// function is to add all these blocks to "DeadBlocks". For the dead blocks'
+// live successors, update their phi nodes by replacing the operands
+// corresponding to dead blocks with UndefVal.
+//
+void GVN::addDeadBlock(BasicBlock *BB) {
+  SmallVector<BasicBlock *, 4> NewDead;
+  SmallSetVector<BasicBlock *, 4> DF;
+
+  NewDead.push_back(BB);
+  while (!NewDead.empty()) {
+    BasicBlock *D = NewDead.pop_back_val();
+    if (DeadBlocks.count(D))
+      continue;
+
+    // All blocks dominated by D are dead.
+    SmallVector<BasicBlock *, 8> Dom;
+    DT->getDescendants(D, Dom);
+    DeadBlocks.insert(Dom.begin(), Dom.end());
+    
+    // Figure out the dominance-frontier(D).
+    for (SmallVectorImpl<BasicBlock *>::iterator I = Dom.begin(),
+           E = Dom.end(); I != E; I++) {
+      BasicBlock *B = *I;
+      for (succ_iterator SI = succ_begin(B), SE = succ_end(B); SI != SE; SI++) {
+        BasicBlock *S = *SI;
+        if (DeadBlocks.count(S))
+          continue;
+
+        bool AllPredDead = true;
+        for (pred_iterator PI = pred_begin(S), PE = pred_end(S); PI != PE; PI++)
+          if (!DeadBlocks.count(*PI)) {
+            AllPredDead = false;
+            break;
+          }
+
+        if (!AllPredDead) {
+          // S could be proved dead later on. That is why we don't update phi
+          // operands at this moment.
+          DF.insert(S);
+        } else {
+          // While S is not dominated by D, it is dead by now. This could take
+          // place if S already have a dead predecessor before D is declared
+          // dead.
+          NewDead.push_back(S);
+        }
+      }
+    }
+  }
+
+  // For the dead blocks' live successors, update their phi nodes by replacing
+  // the operands corresponding to dead blocks with UndefVal.
+  for(SmallSetVector<BasicBlock *, 4>::iterator I = DF.begin(), E = DF.end();
+        I != E; I++) {
+    BasicBlock *B = *I;
+    if (DeadBlocks.count(B))
+      continue;
+
+    SmallVector<BasicBlock *, 4> Preds(pred_begin(B), pred_end(B));
+    for (SmallVectorImpl<BasicBlock *>::iterator PI = Preds.begin(),
+           PE = Preds.end(); PI != PE; PI++) {
+      BasicBlock *P = *PI;
+
+      if (!DeadBlocks.count(P))
+        continue;
+
+      if (isCriticalEdge(P->getTerminator(), GetSuccessorNumber(P, B))) {
+        if (BasicBlock *S = splitCriticalEdges(P, B))
+          DeadBlocks.insert(P = S);
+      }
+
+      for (BasicBlock::iterator II = B->begin(); isa<PHINode>(II); ++II) {
+        PHINode &Phi = cast<PHINode>(*II);
+        Phi.setIncomingValue(Phi.getBasicBlockIndex(P),
+                             UndefValue::get(Phi.getType()));
+      }
+    }
+  }
+}
+
+// If the given branch is recognized as a foldable branch (i.e. conditional
+// branch with constant condition), it will perform following analyses and
+// transformation.
+//  1) If the dead out-coming edge is a critical-edge, split it. Let 
+//     R be the target of the dead out-coming edge.
+//  1) Identify the set of dead blocks implied by the branch's dead outcoming
+//     edge. The result of this step will be {X| X is dominated by R}
+//  2) Identify those blocks which haves at least one dead prodecessor. The
+//     result of this step will be dominance-frontier(R).
+//  3) Update the PHIs in DF(R) by replacing the operands corresponding to 
+//     dead blocks with "UndefVal" in an hope these PHIs will optimized away.
+//
+// Return true iff *NEW* dead code are found.
+bool GVN::processFoldableCondBr(BranchInst *BI) {
+  if (!BI || BI->isUnconditional())
+    return false;
+
+  ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
+  if (!Cond)
+    return false;
+
+  BasicBlock *DeadRoot = Cond->getZExtValue() ? 
+                         BI->getSuccessor(1) : BI->getSuccessor(0);
+  if (DeadBlocks.count(DeadRoot))
+    return false;
+
+  if (!DeadRoot->getSinglePredecessor())
+    DeadRoot = splitCriticalEdges(BI->getParent(), DeadRoot);
+
+  addDeadBlock(DeadRoot);
+  return true;
+}
+
+// performPRE() will trigger assert if it come across an instruciton without
+// associated val-num. As it normally has far more live instructions than dead
+// instructions, it makes more sense just to "fabricate" a val-number for the
+// dead code than checking if instruction involved is dead or not.
+void GVN::assignValNumForDeadCode() {
+  for (SetVector<BasicBlock *>::iterator I = DeadBlocks.begin(),
+        E = DeadBlocks.end(); I != E; I++) {
+    BasicBlock *BB = *I;
+    for (BasicBlock::iterator II = BB->begin(), EE = BB->end();
+          II != EE; II++) {
+      Instruction *Inst = &*II;
+      unsigned ValNum = VN.lookup_or_add(Inst);
+      addToLeaderTable(ValNum, Inst, BB);
+    }
+  }
+}