Rename WeakVH to WeakTrackingVH; NFC

Summary:
I plan to use WeakVH to mean "nulls itself out on deletion, but does
not track RAUW" in a subsequent commit.

Reviewers: dblaikie, davide

Reviewed By: davide

Subscribers: arsenm, mehdi_amini, mcrosier, mzolotukhin, jfb, llvm-commits, nhaehnle

Differential Revision: https://reviews.llvm.org/D32266

llvm-svn: 301424
diff --git a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
index dcb2a4a..3953198 100644
--- a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -97,7 +97,7 @@
   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 @@
                                       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 @@
   //
   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 @@
   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 @@
   }
 
 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/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index 5042fc1..0f4a1b4 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -499,7 +499,7 @@
     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 a5a81c3..35c05e8 100644
--- a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
@@ -40,7 +40,7 @@
   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 af137f6..ccedb98 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -900,7 +900,7 @@
 /// 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 @@
   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 @@
                                   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 @@
 /// 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 @@
 
 /// 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 @@
 /// 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 @@
 /// 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 @@
     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 @@
   // 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 8fa806a..dbec0c0 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -1231,11 +1231,11 @@
   LoopProcessWorklist.push_back(NewLoop);
   redoLoop = true;
 
-  // Keep a WeakVH 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);
+  // 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.
+  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 c5bf2f2..3d947dd 100644
--- a/llvm/lib/Transforms/Scalar/NaryReassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/NaryReassociate.cpp
@@ -211,15 +211,15 @@
           Changed = true;
           SE->forgetValue(&*I);
           I->replaceAllUsesWith(NewI);
-          // If SeenExprs constains I's WeakVH, that entry will be replaced with
-          // nullptr.
+          // If SeenExprs constains I's WeakTrackingVH, that entry will be
+          // replaced with nullptr.
           RecursivelyDeleteTriviallyDeadInstructions(&*I, TLI);
           I = NewI->getIterator();
         }
         // 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 +239,7 @@
         //
         // 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));
       }
     }
   }
@@ -494,8 +494,8 @@
   // 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
-    // during rewriting.
+    // 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);
       if (DT->dominates(CandidateInstruction, Dominatee))
diff --git a/llvm/lib/Transforms/Scalar/Reassociate.cpp b/llvm/lib/Transforms/Scalar/Reassociate.cpp
index 3dcab60..ef29d41 100644
--- a/llvm/lib/Transforms/Scalar/Reassociate.cpp
+++ b/llvm/lib/Transforms/Scalar/Reassociate.cpp
@@ -982,7 +982,7 @@
 /// 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 @@
             ? 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 =