Add comment for DVU RAUW fn, remove Instruction *InsertBefore

Author: SLTozer

llvm/include/llvm/IR/DebugProgramInstruction.h

@@ -129,12 +129,11 @@ class DPValue : public ilist_node<DPValue>, private DebugValueUser {
           DIAssignID *AssignID, Metadata *Address,
           DIExpression *AddressExpression, const DILocation *DI);
 
-  static DPValue *createDPVAssign(Metadata *Value, DILocalVariable *Variable,
+  static DPValue *createDPVAssign(Value *Val, DILocalVariable *Variable,
                                   DIExpression *Expression,
-                                  DIAssignID *AssignID, Metadata *Address,
+                                  DIAssignID *AssignID, Value *Address,
                                   DIExpression *AddressExpression,
-                                  const DILocation *DI,
-                                  Instruction *InsertBefore = nullptr);
+                                  const DILocation *DI);
   static DPValue *createLinkedDPVAssign(Instruction *LinkedInstr, Value *Val,
                                         DILocalVariable *Variable,
                                         DIExpression *Expression,

llvm/include/llvm/IR/Metadata.h

@@ -222,6 +222,12 @@ class DebugValueUser {
 public:
   DPValue *getUser();
   const DPValue *getUser() const;
+  /// To be called by ReplaceableMetadataImpl::replaceAllUsesWith, where `Old`
+  /// is a pointer to one of the pointers in `DebugValues` (so should be type
+  /// Metadata**), and `NewDebugValue` is the new Metadata* that is replacing
+  /// *Old.
+  /// For manually replacing elements of DebugValues,
+  /// `resetDebugValue(Idx, NewDebugValue)` should be used instead.
   void handleChangedValue(void *Old, Metadata *NewDebugValue);
   DebugValueUser() = default;
   explicit DebugValueUser(std::array<Metadata *, 3> DebugValues)

llvm/lib/IR/DebugProgramInstruction.cpp

@@ -87,19 +87,13 @@ DPValue *DPValue::createDPVDeclare(Value *Address, DILocalVariable *DV,
   return NewDPVDeclare;
 }
 
-DPValue *DPValue::createDPVAssign(Metadata *Value, DILocalVariable *Variable,
+DPValue *DPValue::createDPVAssign(Value *Val, DILocalVariable *Variable,
                                   DIExpression *Expression,
-                                  DIAssignID *AssignID, Metadata *Address,
+                                  DIAssignID *AssignID, Value *Address,
                                   DIExpression *AddressExpression,
-                                  const DILocation *DI,
-                                  Instruction *InsertBefore) {
-  auto *NewDPVAssign = new DPValue(Value, Variable, Expression, AssignID,
-                                   Address, AddressExpression, DI);
-  if (InsertBefore) {
-    InsertBefore->getParent()->insertDPValueBefore(NewDPVAssign,
-                                                   InsertBefore->getIterator());
-  }
-  return NewDPVAssign;
+                                  const DILocation *DI) {
+  return new DPValue(ValueAsMetadata::get(Val), Variable, Expression, AssignID,
+                     ValueAsMetadata::get(Address), AddressExpression, DI);
 }
 
 DPValue *DPValue::createLinkedDPVAssign(Instruction *LinkedInstr, Value *Val,
@@ -110,9 +104,9 @@ DPValue *DPValue::createLinkedDPVAssign(Instruction *LinkedInstr, Value *Val,
                                         const DILocation *DI) {
   auto *Link = LinkedInstr->getMetadata(LLVMContext::MD_DIAssignID);
   assert(Link && "Linked instruction must have DIAssign metadata attached");
-  auto *NewDPVAssign = new DPValue(
-      ValueAsMetadata::get(Val), Variable, Expression, cast<DIAssignID>(Link),
-      ValueAsMetadata::get(Address), AddressExpression, DI);
+  auto *NewDPVAssign = DPValue::createDPVAssign(Val, Variable, Expression,
+                                                cast<DIAssignID>(Link), Address,
+                                                AddressExpression, DI);
   LinkedInstr->getParent()->insertDPValueAfter(NewDPVAssign, LinkedInstr);
   return NewDPVAssign;
 }