Rename WeakVH to WeakTrackingVH; NFC

This relands r301424.

llvm-svn: 301812

8 files changed, 57 insertions, 72 deletions

diff --git a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
index dcb2a4a0c6e..3953198fe60 100644
--- a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -97,7 +97,7 @@ class IndVarSimplify {
   TargetLibraryInfo *TLI;
   const TargetTransformInfo *TTI;
 
-  SmallVector<WeakVH, 16> DeadInsts;
+  SmallVector<WeakTrackingVH, 16> DeadInsts;
   bool Changed = false;
 
   bool isValidRewrite(Value *FromVal, Value *ToVal);
@@ -415,8 +415,8 @@ void IndVarSimplify::handleFloatingPointIV(Loop *L, PHINode *PN) {
                                       Compare->getName());
 
   // In the following deletions, PN may become dead and may be deleted.
-  // Use a WeakVH to observe whether this happens.
-  WeakVH WeakPH = PN;
+  // Use a WeakTrackingVH to observe whether this happens.
+  WeakTrackingVH WeakPH = PN;
 
   // Delete the old floating point exit comparison.  The branch starts using the
   // new comparison.
@@ -451,7 +451,7 @@ void IndVarSimplify::rewriteNonIntegerIVs(Loop *L) {
   //
   BasicBlock *Header = L->getHeader();
 
-  SmallVector<WeakVH, 8> PHIs;
+  SmallVector<WeakTrackingVH, 8> PHIs;
   for (BasicBlock::iterator I = Header->begin();
        PHINode *PN = dyn_cast<PHINode>(I); ++I)
     PHIs.push_back(PN);
@@ -901,7 +901,7 @@ class WidenIV {
   PHINode *WidePhi;
   Instruction *WideInc;
   const SCEV *WideIncExpr;
-  SmallVectorImpl<WeakVH> &DeadInsts;
+  SmallVectorImpl<WeakTrackingVH> &DeadInsts;
 
   SmallPtrSet<Instruction *,16> Widened;
   SmallVector<NarrowIVDefUse, 8> NarrowIVUsers;
@@ -941,20 +941,13 @@ class WidenIV {
   }
 
 public:
-  WidenIV(const WideIVInfo &WI, LoopInfo *LInfo,
-          ScalarEvolution *SEv, DominatorTree *DTree,
-          SmallVectorImpl<WeakVH> &DI, bool HasGuards) :
-    OrigPhi(WI.NarrowIV),
-    WideType(WI.WidestNativeType),
-    LI(LInfo),
-    L(LI->getLoopFor(OrigPhi->getParent())),
-    SE(SEv),
-    DT(DTree),
-    HasGuards(HasGuards),
-    WidePhi(nullptr),
-    WideInc(nullptr),
-    WideIncExpr(nullptr),
-    DeadInsts(DI) {
+  WidenIV(const WideIVInfo &WI, LoopInfo *LInfo, ScalarEvolution *SEv,
+          DominatorTree *DTree, SmallVectorImpl<WeakTrackingVH> &DI,
+          bool HasGuards)
+      : OrigPhi(WI.NarrowIV), WideType(WI.WidestNativeType), LI(LInfo),
+        L(LI->getLoopFor(OrigPhi->getParent())), SE(SEv), DT(DTree),
+        HasGuards(HasGuards), WidePhi(nullptr), WideInc(nullptr),
+        WideIncExpr(nullptr), DeadInsts(DI) {
     assert(L->getHeader() == OrigPhi->getParent() && "Phi must be an IV");
     ExtendKindMap[OrigPhi] = WI.IsSigned ? SignExtended : ZeroExtended;
   }
diff --git a/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp b/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
index e6994896d3a..5e116ef2fe7 100644
--- a/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
+++ b/llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
@@ -138,7 +138,7 @@ private:
 
   // Tries to infer the specific address space of each address expression in
   // Postorder.
-  void inferAddressSpaces(ArrayRef<WeakVH> Postorder,
+  void inferAddressSpaces(ArrayRef<WeakTrackingVH> Postorder,
                           ValueToAddrSpaceMapTy *InferredAddrSpace) const;
 
   bool isSafeToCastConstAddrSpace(Constant *C, unsigned NewAS) const;
@@ -147,7 +147,7 @@ private:
   // address spaces if InferredAddrSpace says so. Postorder is the postorder of
   // all flat expressions in the use-def graph of function F.
   bool
-  rewriteWithNewAddressSpaces(ArrayRef<WeakVH> Postorder,
+  rewriteWithNewAddressSpaces(ArrayRef<WeakTrackingVH> Postorder,
                               const ValueToAddrSpaceMapTy &InferredAddrSpace,
                               Function *F) const;
 
@@ -162,7 +162,7 @@ private:
     std::vector<std::pair<Value *, bool>> &PostorderStack,
     DenseSet<Value *> &Visited) const;
 
-  std::vector<WeakVH> collectFlatAddressExpressions(Function &F) const;
+  std::vector<WeakTrackingVH> collectFlatAddressExpressions(Function &F) const;
 
   Value *cloneValueWithNewAddressSpace(
     Value *V, unsigned NewAddrSpace,
@@ -303,7 +303,7 @@ void InferAddressSpaces::appendsFlatAddressExpressionToPostorderStack(
 
 // Returns all flat address expressions in function F. The elements are ordered
 // ordered in postorder.
-std::vector<WeakVH>
+std::vector<WeakTrackingVH>
 InferAddressSpaces::collectFlatAddressExpressions(Function &F) const {
   // This function implements a non-recursive postorder traversal of a partial
   // use-def graph of function F.
@@ -352,7 +352,7 @@ InferAddressSpaces::collectFlatAddressExpressions(Function &F) const {
     }
   }
 
-  std::vector<WeakVH> Postorder; // The resultant postorder.
+  std::vector<WeakTrackingVH> Postorder; // The resultant postorder.
   while (!PostorderStack.empty()) {
     Value *TopVal = PostorderStack.back().first;
     // If the operands of the expression on the top are already explored,
@@ -583,7 +583,7 @@ bool InferAddressSpaces::runOnFunction(Function &F) {
     return false;
 
   // Collects all flat address expressions in postorder.
-  std::vector<WeakVH> Postorder = collectFlatAddressExpressions(F);
+  std::vector<WeakTrackingVH> Postorder = collectFlatAddressExpressions(F);
 
   // Runs a data-flow analysis to refine the address spaces of every expression
   // in Postorder.
@@ -596,9 +596,9 @@ bool InferAddressSpaces::runOnFunction(Function &F) {
 }
 
 // Constants need to be tracked through RAUW to handle cases with nested
-// constant expressions, so wrap values in WeakVH.
+// constant expressions, so wrap values in WeakTrackingVH.
 void InferAddressSpaces::inferAddressSpaces(
-    ArrayRef<WeakVH> Postorder,
+    ArrayRef<WeakTrackingVH> Postorder,
     ValueToAddrSpaceMapTy *InferredAddrSpace) const {
   SetVector<Value *> Worklist(Postorder.begin(), Postorder.end());
   // Initially, all expressions are in the uninitialized address space.
@@ -810,8 +810,8 @@ static Value::use_iterator skipToNextUser(Value::use_iterator I,
 }
 
 bool InferAddressSpaces::rewriteWithNewAddressSpaces(
-  ArrayRef<WeakVH> Postorder,
-  const ValueToAddrSpaceMapTy &InferredAddrSpace, Function *F) const {
+    ArrayRef<WeakTrackingVH> Postorder,
+    const ValueToAddrSpaceMapTy &InferredAddrSpace, Function *F) const {
   // For each address expression to be modified, creates a clone of it with its
   // pointer operands converted to the new address space. Since the pointer
   // operands are converted, the clone is naturally in the new address space by
@@ -841,7 +841,7 @@ bool InferAddressSpaces::rewriteWithNewAddressSpaces(
   SmallVector<Instruction *, 16> DeadInstructions;
 
   // Replaces the uses of the old address expressions with the new ones.
-  for (const WeakVH &WVH : Postorder) {
+  for (const WeakTrackingVH &WVH : Postorder) {
     assert(WVH && "value was unexpectedly deleted");
     Value *V = WVH;
     Value *NewV = ValueWithNewAddrSpace.lookup(V);
diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index 5042fc18d7c..0f4a1b436ea 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -499,7 +499,7 @@ bool LoopIdiomRecognize::runOnLoopBlock(
     Instruction *Inst = &*I++;
     // Look for memset instructions, which may be optimized to a larger memset.
     if (MemSetInst *MSI = dyn_cast<MemSetInst>(Inst)) {
-      WeakVH InstPtr(&*I);
+      WeakTrackingVH InstPtr(&*I);
       if (!processLoopMemSet(MSI, BECount))
         continue;
       MadeChange = true;
diff --git a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
index a5a81c33a8e..35c05e84fd6 100644
--- a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
@@ -40,7 +40,7 @@ static bool simplifyLoopCFG(Loop &L, DominatorTree &DT, LoopInfo &LI) {
   bool Changed = false;
   // Copy blocks into a temporary array to avoid iterator invalidation issues
   // as we remove them.
-  SmallVector<WeakVH, 16> Blocks(L.blocks());
+  SmallVector<WeakTrackingVH, 16> Blocks(L.blocks());
 
   for (auto &Block : Blocks) {
     // Attempt to merge blocks in the trivial case. Don't modify blocks which
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index af137f6faa6..ccedb98d7fa 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -900,7 +900,7 @@ static bool isHighCostExpansion(const SCEV *S,
 /// If any of the instructions is the specified set are trivially dead, delete
 /// them and see if this makes any of their operands subsequently dead.
 static bool
-DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakVH> &DeadInsts) {
+DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakTrackingVH> &DeadInsts) {
   bool Changed = false;
 
   while (!DeadInsts.empty()) {
@@ -1845,7 +1845,7 @@ class LSRInstance {
   void FinalizeChain(IVChain &Chain);
   void CollectChains();
   void GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,
-                       SmallVectorImpl<WeakVH> &DeadInsts);
+                       SmallVectorImpl<WeakTrackingVH> &DeadInsts);
 
   void CollectInterestingTypesAndFactors();
   void CollectFixupsAndInitialFormulae();
@@ -1920,19 +1920,15 @@ class LSRInstance {
                                   const LSRUse &LU,
                                   SCEVExpander &Rewriter) const;
 
-  Value *Expand(const LSRUse &LU, const LSRFixup &LF,
-                const Formula &F,
-                BasicBlock::iterator IP,
-                SCEVExpander &Rewriter,
-                SmallVectorImpl<WeakVH> &DeadInsts) const;
+  Value *Expand(const LSRUse &LU, const LSRFixup &LF, const Formula &F,
+                BasicBlock::iterator IP, SCEVExpander &Rewriter,
+                SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
   void RewriteForPHI(PHINode *PN, const LSRUse &LU, const LSRFixup &LF,
-                     const Formula &F,
-                     SCEVExpander &Rewriter,
-                     SmallVectorImpl<WeakVH> &DeadInsts) const;
-  void Rewrite(const LSRUse &LU, const LSRFixup &LF,
-               const Formula &F,
+                     const Formula &F, SCEVExpander &Rewriter,
+                     SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
+  void Rewrite(const LSRUse &LU, const LSRFixup &LF, const Formula &F,
                SCEVExpander &Rewriter,
-               SmallVectorImpl<WeakVH> &DeadInsts) const;
+               SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
   void ImplementSolution(const SmallVectorImpl<const Formula *> &Solution);
 
 public:
@@ -3014,7 +3010,7 @@ static bool canFoldIVIncExpr(const SCEV *IncExpr, Instruction *UserInst,
 /// Generate an add or subtract for each IVInc in a chain to materialize the IV
 /// user's operand from the previous IV user's operand.
 void LSRInstance::GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,
-                                  SmallVectorImpl<WeakVH> &DeadInsts) {
+                                  SmallVectorImpl<WeakTrackingVH> &DeadInsts) {
   // Find the new IVOperand for the head of the chain. It may have been replaced
   // by LSR.
   const IVInc &Head = Chain.Incs[0];
@@ -4759,12 +4755,10 @@ LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP,
 
 /// Emit instructions for the leading candidate expression for this LSRUse (this
 /// is called "expanding").
-Value *LSRInstance::Expand(const LSRUse &LU,
-                           const LSRFixup &LF,
-                           const Formula &F,
-                           BasicBlock::iterator IP,
+Value *LSRInstance::Expand(const LSRUse &LU, const LSRFixup &LF,
+                           const Formula &F, BasicBlock::iterator IP,
                            SCEVExpander &Rewriter,
-                           SmallVectorImpl<WeakVH> &DeadInsts) const {
+                           SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
   if (LU.RigidFormula)
     return LF.OperandValToReplace;
 
@@ -4939,12 +4933,9 @@ Value *LSRInstance::Expand(const LSRUse &LU,
 /// Helper for Rewrite. PHI nodes are special because the use of their operands
 /// effectively happens in their predecessor blocks, so the expression may need
 /// to be expanded in multiple places.
-void LSRInstance::RewriteForPHI(PHINode *PN,
-                                const LSRUse &LU,
-                                const LSRFixup &LF,
-                                const Formula &F,
-                                SCEVExpander &Rewriter,
-                                SmallVectorImpl<WeakVH> &DeadInsts) const {
+void LSRInstance::RewriteForPHI(
+    PHINode *PN, const LSRUse &LU, const LSRFixup &LF, const Formula &F,
+    SCEVExpander &Rewriter, SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
   DenseMap<BasicBlock *, Value *> Inserted;
   for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
     if (PN->getIncomingValue(i) == LF.OperandValToReplace) {
@@ -5016,11 +5007,9 @@ void LSRInstance::RewriteForPHI(PHINode *PN,
 /// Emit instructions for the leading candidate expression for this LSRUse (this
 /// is called "expanding"), and update the UserInst to reference the newly
 /// expanded value.
-void LSRInstance::Rewrite(const LSRUse &LU,
-                          const LSRFixup &LF,
-                          const Formula &F,
-                          SCEVExpander &Rewriter,
-                          SmallVectorImpl<WeakVH> &DeadInsts) const {
+void LSRInstance::Rewrite(const LSRUse &LU, const LSRFixup &LF,
+                          const Formula &F, SCEVExpander &Rewriter,
+                          SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
   // First, find an insertion point that dominates UserInst. For PHI nodes,
   // find the nearest block which dominates all the relevant uses.
   if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) {
@@ -5058,7 +5047,7 @@ void LSRInstance::ImplementSolution(
     const SmallVectorImpl<const Formula *> &Solution) {
   // Keep track of instructions we may have made dead, so that
   // we can remove them after we are done working.
-  SmallVector<WeakVH, 16> DeadInsts;
+  SmallVector<WeakTrackingVH, 16> DeadInsts;
 
   SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(),
                         "lsr");
@@ -5308,7 +5297,7 @@ static bool ReduceLoopStrength(Loop *L, IVUsers &IU, ScalarEvolution &SE,
   // Remove any extra phis created by processing inner loops.
   Changed |= DeleteDeadPHIs(L->getHeader());
   if (EnablePhiElim && L->isLoopSimplifyForm()) {
-    SmallVector<WeakVH, 16> DeadInsts;
+    SmallVector<WeakTrackingVH, 16> DeadInsts;
     const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
     SCEVExpander Rewriter(SE, DL, "lsr");
 #ifndef NDEBUG
diff --git a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
index 39289340e03..6ef1464e933 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -1231,11 +1231,12 @@ void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val,
   LoopProcessWorklist.push_back(NewLoop);
   redoLoop = true;
 
-  // Keep a WeakVH holding onto LIC.  If the first call to RewriteLoopBody
+  // Keep a WeakTrackingVH holding onto LIC.  If the first call to
+  // RewriteLoopBody
   // deletes the instruction (for example by simplifying a PHI that feeds into
   // the condition that we're unswitching on), we don't rewrite the second
   // iteration.
-  WeakVH LICHandle(LIC);
+  WeakTrackingVH LICHandle(LIC);
 
   // Now we rewrite the original code to know that the condition is true and the
   // new code to know that the condition is false.
diff --git a/llvm/lib/Transforms/Scalar/NaryReassociate.cpp b/llvm/lib/Transforms/Scalar/NaryReassociate.cpp
index c5bf2f28d18..d0bfe360389 100644
--- a/llvm/lib/Transforms/Scalar/NaryReassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/NaryReassociate.cpp
@@ -211,7 +211,8 @@ bool NaryReassociatePass::doOneIteration(Function &F) {
           Changed = true;
           SE->forgetValue(&*I);
           I->replaceAllUsesWith(NewI);
-          // If SeenExprs constains I's WeakVH, that entry will be replaced with
+          // If SeenExprs constains I's WeakTrackingVH, that entry will be
+          // replaced with
           // nullptr.
           RecursivelyDeleteTriviallyDeadInstructions(&*I, TLI);
           I = NewI->getIterator();
@@ -219,7 +220,7 @@ bool NaryReassociatePass::doOneIteration(Function &F) {
         // Add the rewritten instruction to SeenExprs; the original instruction
         // is deleted.
         const SCEV *NewSCEV = SE->getSCEV(&*I);
-        SeenExprs[NewSCEV].push_back(WeakVH(&*I));
+        SeenExprs[NewSCEV].push_back(WeakTrackingVH(&*I));
         // Ideally, NewSCEV should equal OldSCEV because tryReassociate(I)
         // is equivalent to I. However, ScalarEvolution::getSCEV may
         // weaken nsw causing NewSCEV not to equal OldSCEV. For example, suppose
@@ -239,7 +240,7 @@ bool NaryReassociatePass::doOneIteration(Function &F) {
         //
         // This improvement is exercised in @reassociate_gep_nsw in nary-gep.ll.
         if (NewSCEV != OldSCEV)
-          SeenExprs[OldSCEV].push_back(WeakVH(&*I));
+          SeenExprs[OldSCEV].push_back(WeakTrackingVH(&*I));
       }
     }
   }
@@ -494,7 +495,8 @@ NaryReassociatePass::findClosestMatchingDominator(const SCEV *CandidateExpr,
   // future instruction either. Therefore, we pop it out of the stack. This
   // optimization makes the algorithm O(n).
   while (!Candidates.empty()) {
-    // Candidates stores WeakVHs, so a candidate can be nullptr if it's removed
+    // Candidates stores WeakTrackingVHs, so a candidate can be nullptr if it's
+    // removed
     // during rewriting.
     if (Value *Candidate = Candidates.back()) {
       Instruction *CandidateInstruction = cast<Instruction>(Candidate);
diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 3dcab609078..ef29d414160 100644
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -982,7 +982,7 @@ static unsigned FindInOperandList(SmallVectorImpl<ValueEntry> &Ops, unsigned i,
 /// Emit a tree of add instructions, summing Ops together
 /// and returning the result.  Insert the tree before I.
 static Value *EmitAddTreeOfValues(Instruction *I,
-                                  SmallVectorImpl<WeakVH> &Ops){
+                                  SmallVectorImpl<WeakTrackingVH> &Ops) {
   if (Ops.size() == 1) return Ops.back();
 
   Value *V1 = Ops.back();
@@ -1559,7 +1559,7 @@ Value *ReassociatePass::OptimizeAdd(Instruction *I,
             ? BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal)
             : BinaryOperator::CreateFAdd(MaxOccVal, MaxOccVal);
 
-    SmallVector<WeakVH, 4> NewMulOps;
+    SmallVector<WeakTrackingVH, 4> NewMulOps;
     for (unsigned i = 0; i != Ops.size(); ++i) {
       // Only try to remove factors from expressions we're allowed to.
       BinaryOperator *BOp =