Replace all accesses to User::OperandList with getter and setter methods. NFC.

We don't want anyone to access OperandList directly as its going to be removed
and computed instead.  This uses getter's and setter's instead in which we
can later change the underlying implementation of OperandList.

Reviewed by Duncan Exon Smith.

llvm-svn: 239620
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 73b966f..dff31be 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -172,7 +172,8 @@
                   LP.getNumOperands()),
       ReservedSpace(LP.getNumOperands()) {
   allocHungoffUses(LP.getNumOperands());
-  Use *OL = OperandList, *InOL = LP.OperandList;
+  Use *OL = getOperandList();
+  const Use *InOL = LP.getOperandList();
   for (unsigned I = 0, E = ReservedSpace; I != E; ++I)
     OL[I] = InOL[I];
 
@@ -219,7 +220,7 @@
   growOperands(1);
   assert(OpNo < ReservedSpace && "Growing didn't work!");
   ++NumOperands;
-  OperandList[OpNo] = Val;
+  getOperandList()[OpNo] = Val;
 }
 
 //===----------------------------------------------------------------------===//
@@ -3295,7 +3296,8 @@
   : TerminatorInst(SI.getType(), Instruction::Switch, nullptr, 0) {
   init(SI.getCondition(), SI.getDefaultDest(), SI.getNumOperands());
   NumOperands = SI.getNumOperands();
-  Use *OL = OperandList, *InOL = SI.OperandList;
+  Use *OL = getOperandList();
+  const Use *InOL = SI.getOperandList();
   for (unsigned i = 2, E = SI.getNumOperands(); i != E; i += 2) {
     OL[i] = InOL[i];
     OL[i+1] = InOL[i+1];
@@ -3327,7 +3329,7 @@
   assert(2 + idx*2 < getNumOperands() && "Case index out of range!!!");
 
   unsigned NumOps = getNumOperands();
-  Use *OL = OperandList;
+  Use *OL = getOperandList();
 
   // Overwrite this case with the end of the list.
   if (2 + (idx + 1) * 2 != NumOps) {
@@ -3407,7 +3409,8 @@
     : TerminatorInst(Type::getVoidTy(IBI.getContext()), Instruction::IndirectBr,
                      nullptr, IBI.getNumOperands()) {
   allocHungoffUses(IBI.getNumOperands());
-  Use *OL = OperandList, *InOL = IBI.OperandList;
+  Use *OL = getOperandList();
+  const Use *InOL = IBI.getOperandList();
   for (unsigned i = 0, E = IBI.getNumOperands(); i != E; ++i)
     OL[i] = InOL[i];
   SubclassOptionalData = IBI.SubclassOptionalData;
@@ -3422,7 +3425,7 @@
   // Initialize some new operands.
   assert(OpNo < ReservedSpace && "Growing didn't work!");
   NumOperands = OpNo+1;
-  OperandList[OpNo] = DestBB;
+  getOperandList()[OpNo] = DestBB;
 }
 
 /// removeDestination - This method removes the specified successor from the
@@ -3431,7 +3434,7 @@
   assert(idx < getNumOperands()-1 && "Successor index out of range!");
   
   unsigned NumOps = getNumOperands();
-  Use *OL = OperandList;
+  Use *OL = getOperandList();
 
   // Replace this value with the last one.
   OL[idx+1] = OL[NumOps-1];