ScalarEvolution: added tmp to avoid use-after-dtor in for loop.

[nmusgrave]

Summary

For loop destroyed current instance before invoking next.
Temporary variable added to prevent use-after-dtor when invoke
destructor on current instance.

[eugenis]

lib/Analysis/ScalarEvolution.cpp

8398

I think the name should start with a capital letter: Tmp.

[nmusgrave]

• Rename temp var.

[eugenis]

LGTM

lib/Analysis/ScalarEvolution.cpp

: F(Arg.F), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT), LI(Arg.LI),
       SCEVAllocator(std::move(Arg.SCEVAllocator)),
       FirstUnknown(Arg.FirstUnknown) {
   Arg.FirstUnknown = nullptr;
 }
 
 ScalarEvolution::~ScalarEvolution() {
   // Iterate through all the SCEVUnknown instances and call their
   // destructors, so that they release their references to their values.
-  for (SCEVUnknown *U = FirstUnknown; U; U = U->Next)
-    U->~SCEVUnknown();
+  for (SCEVUnknown *U = FirstUnknown; U;) {
+    SCEVUnknown *Tmp = U;
+    U = U->Next;
+    Tmp->~SCEVUnknown();
+  }
   FirstUnknown = nullptr;
 
   ValueExprMap.clear();
 
   // Free any extra memory created for ExitNotTakenInfo in the unlikely event
   // that a loop had multiple computable exits.
   for (DenseMap<const Loop*, BackedgeTakenInfo>::iterator I =
          BackedgeTakenCounts.begin(), E = BackedgeTakenCounts.end();