Make OrderedInstructions and OrderedBasicBlock use AssertingVH, to try and catch mistakes

[trentxintong]

Summary

Make OrderedInstructions and OrderedBasicBlock use AssertingVH to try and catch mistakes

[trentxintong]

Cosmetic Change

[efriedma]

LGTM.

include/llvm/Analysis/OrderedBasicBlock.h

 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_ANALYSIS_ORDEREDBASICBLOCK_H
 #define LLVM_ANALYSIS_ORDEREDBASICBLOCK_H
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/ValueHandle.h"
 
 namespace llvm {
 
 class Instruction;
 class BasicBlock;
 
 class OrderedBasicBlock {
 private:
   /// \brief Map a instruction to its position in a BasicBlock.
-  SmallDenseMap<const Instruction *, unsigned, 32> NumberedInsts;
+  SmallDenseMap<AssertingVH<const Instruction>, unsigned, 32> NumberedInsts;
 
   /// \brief Keep track of last instruction inserted into \p NumberedInsts.
   /// It speeds up queries for uncached instructions by providing a start point
   /// for new queries in OrderedBasicBlock::comesBefore.
   BasicBlock::const_iterator LastInstFound;
 
   /// \brief The position/number to tag the next instruction to be found.
   unsigned NextInstPos;

include/llvm/Transforms/Utils/OrderedInstructions.h

 
 #ifndef LLVM_TRANSFORMS_UTILS_ORDEREDINSTRUCTIONS_H
 #define LLVM_TRANSFORMS_UTILS_ORDEREDINSTRUCTIONS_H
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/Analysis/OrderedBasicBlock.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Operator.h"
+#include "llvm/IR/ValueHandle.h"
 
 namespace llvm {
 
 class OrderedInstructions {
   /// Used to check dominance for instructions in same basic block.
-  mutable DenseMap<const BasicBlock *, std::unique_ptr<OrderedBasicBlock>>
+  mutable DenseMap<AssertingVH<const BasicBlock>,
+                   std::unique_ptr<OrderedBasicBlock>>
       OBBMap;
 
   /// The dominator tree of the parent function.
   DominatorTree *DT;
 
 public:
   /// Constructor.
   OrderedInstructions(DominatorTree *DT) : DT(DT) {}