LoopVectorize: Make Value pointers that could be RAUW'ed a VH

The Value pointers we store in the induction variable list can be RAUW'ed by a
call to SCEVExpander::expandCodeFor, use a TrackingVH instead. Do the same thing
in some other places where we store pointers that could potentially be RAUW'ed.

Fixes PR16073.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182485 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -80,6 +80,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/PatternMatch.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/ValueHandle.h"
 #include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
@@ -458,7 +459,7 @@ public:
 
     // The starting value of the reduction.
     // It does not have to be zero!
-    Value *StartValue;
+    TrackingVH<Value> StartValue;
     // The instruction who's value is used outside the loop.
     Instruction *LoopExitInstr;
     // The kind of the reduction.
@@ -503,7 +504,7 @@ public:
     /// This flag indicates if we need to add the runtime check.
     bool Need;
     /// Holds the pointers that we need to check.
-    SmallVector<Value*, 2> Pointers;
+    SmallVector<TrackingVH<Value>, 2> Pointers;
     /// Holds the pointer value at the beginning of the loop.
     SmallVector<const SCEV*, 2> Starts;
     /// Holds the pointer value at the end of the loop.
@@ -517,7 +518,7 @@ public:
     InductionInfo(Value *Start, InductionKind K) : StartValue(Start), IK(K) {}
     InductionInfo() : StartValue(0), IK(IK_NoInduction) {}
     /// Start value.
-    Value *StartValue;
+    TrackingVH<Value> StartValue;
     /// Induction kind.
     InductionKind IK;
   };