Revert "[DebugInfo][RemoveDIs] Add prototype storage classes for "new" debug-info"

And some intervening fixups. There are two remaining problems:
 * A memory leak via https://lab.llvm.org/buildbot/#/builders/236/builds/7120/steps/10/logs/stdio
 * A performance slowdown with -g where I'm not completely sure what the cause it

These might be fairly straightforwards to fix, but it's the end of the day
hear, so I figure I'll clear the buildbots til tomorrow.

This reverts commit 7d77bbef4ad9230f6f427649373fe46a668aa909.
This reverts commit 9026f35afe6ffdc5e55b6615efcbd36f25b11558.
This reverts commit d97b2b389a0e511c65af6845119eb08b8a2cb473.

10 files changed, 6 insertions, 676 deletions

diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index 0aba608..46b1a3b 100644
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -20,171 +20,12 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Type.h"
-#include "llvm/Support/CommandLine.h"
-
-#include "LLVMContextImpl.h"
 
 using namespace llvm;
 
 #define DEBUG_TYPE "ir"
 STATISTIC(NumInstrRenumberings, "Number of renumberings across all blocks");
 
-cl::opt<bool>
-    UseNewDbgInfoFormat("experimental-debuginfo-iterators",
-                        cl::desc("Enable communicating debuginfo positions "
-                                 "through iterators, eliminating intrinsics"),
-                        cl::init(false));
-
-DPMarker *BasicBlock::createMarker(Instruction *I) {
-  assert(IsNewDbgInfoFormat &&
-         "Tried to create a marker in a non new debug-info block!");
-  assert(I->DbgMarker == nullptr &&
-         "Tried to create marker for instuction that already has one!");
-  DPMarker *Marker = new DPMarker();
-  Marker->MarkedInstr = I;
-  I->DbgMarker = Marker;
-  return Marker;
-}
-
-DPMarker *BasicBlock::createMarker(InstListType::iterator It) {
-  assert(IsNewDbgInfoFormat &&
-         "Tried to create a marker in a non new debug-info block!");
-  if (It != end())
-    return createMarker(&*It);
-  DPMarker *DPM = getTrailingDPValues();
-  if (DPM)
-    return DPM;
-  DPM = new DPMarker();
-  setTrailingDPValues(DPM);
-  return DPM;
-}
-
-void BasicBlock::convertToNewDbgValues() {
-  // Is the command line option set?
-  if (!UseNewDbgInfoFormat)
-    return;
-
-  IsNewDbgInfoFormat = true;
-
-  // Iterate over all instructions in the instruction list, collecting dbg.value
-  // instructions and converting them to DPValues. Once we find a "real"
-  // instruction, attach all those DPValues to a DPMarker in that instruction.
-  SmallVector<DPValue *, 4> DPVals;
-  for (Instruction &I : make_early_inc_range(InstList)) {
-    assert(!I.DbgMarker && "DbgMarker already set on old-format instrs?");
-    if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(&I)) {
-      // Convert this dbg.value to a DPValue.
-      DPValue *Value = new DPValue(DVI);
-      DPVals.push_back(Value);
-      DVI->eraseFromParent();
-      continue;
-    }
-
-    // Create a marker to store DPValues in. Technically we don't need to store
-    // one marker per instruction, but that's a future optimisation.
-    createMarker(&I);
-    DPMarker *Marker = I.DbgMarker;
-
-    for (DPValue *DPV : DPVals)
-      Marker->insertDPValue(DPV, false);
-
-    DPVals.clear();
-  }
-}
-
-void BasicBlock::convertFromNewDbgValues() {
-  invalidateOrders();
-  IsNewDbgInfoFormat = false;
-
-  // Iterate over the block, finding instructions annotated with DPMarkers.
-  // Convert any attached DPValues to dbg.values and insert ahead of the
-  // instruction.
-  for (auto &Inst : *this) {
-    if (!Inst.DbgMarker)
-      continue;
-
-    DPMarker &Marker = *Inst.DbgMarker;
-    for (DPValue &DPV : Marker.getDbgValueRange())
-      InstList.insert(Inst.getIterator(),
-                      DPV.createDebugIntrinsic(getModule(), nullptr));
-
-    Marker.eraseFromParent();
-  };
-
-  // Assume no trailing DPValues: we could technically create them at the end
-  // of the block, after a terminator, but this would be non-cannonical and
-  // indicates that something else is broken somewhere.
-  assert(!getTrailingDPValues());
-}
-
-bool BasicBlock::validateDbgValues(bool Assert, bool Msg, raw_ostream *OS) {
-  bool RetVal = false;
-  if (!OS)
-    OS = &errs();
-
-  // Helper lambda for reporting failures: via assertion, printing, and return
-  // value.
-  auto TestFailure = [Assert, Msg, &RetVal, OS](bool Val, const char *Text) {
-    // Did the test fail?
-    if (Val)
-      return;
-
-    // If we're asserting, then fire off an assertion.
-    if (Assert)
-      llvm_unreachable(Text);
-
-    if (Msg)
-      *OS << Text << "\n";
-    RetVal = true;
-  };
-
-  // We should have the same debug-format as the parent function.
-  TestFailure(getParent()->IsNewDbgInfoFormat == IsNewDbgInfoFormat,
-              "Parent function doesn't have the same debug-info format");
-
-  // Only validate if we are using the new format.
-  if (!IsNewDbgInfoFormat)
-    return RetVal;
-
-  // Match every DPMarker to every Instruction and vice versa, and
-  // verify that there are no invalid DPValues.
-  for (auto It = begin(); It != end(); ++It) {
-    if (!It->DbgMarker)
-      continue;
-
-    // Validate DebugProgramMarkers.
-    DPMarker *CurrentDebugMarker = It->DbgMarker;
-
-    // If this is a marker, it should match the instruction and vice versa.
-    TestFailure(CurrentDebugMarker->MarkedInstr == &*It,
-                "Debug Marker points to incorrect instruction?");
-
-    // Now validate any DPValues in the marker.
-    for (DPValue &DPV : CurrentDebugMarker->getDbgValueRange()) {
-      // Validate DebugProgramValues.
-      TestFailure(DPV.getMarker() == CurrentDebugMarker,
-                  "Not pointing at correct next marker!");
-
-      // Verify that no DbgValues appear prior to PHIs.
-      TestFailure(
-          !isa<PHINode>(It),
-          "DebugProgramValues must not appear before PHI nodes in a block!");
-    }
-  }
-
-  // Except transiently when removing + re-inserting the block terminator, there
-  // should be no trailing DPValues.
-  TestFailure(!getTrailingDPValues(), "Trailing DPValues in block");
-  return RetVal;
-}
-
-void BasicBlock::setIsNewDbgInfoFormat(bool NewFlag) {
-  if (NewFlag && !IsNewDbgInfoFormat)
-    convertToNewDbgValues();
-  else if (!NewFlag && IsNewDbgInfoFormat)
-    convertFromNewDbgValues();
-}
-
 ValueSymbolTable *BasicBlock::getValueSymbolTable() {
   if (Function *F = getParent())
     return F->getValueSymbolTable();
@@ -206,8 +47,7 @@ template class llvm::SymbolTableListTraits<Instruction,
 
 BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent,
                        BasicBlock *InsertBefore)
-    : Value(Type::getLabelTy(C), Value::BasicBlockVal),
-      IsNewDbgInfoFormat(false), Parent(nullptr) {
+  : Value(Type::getLabelTy(C), Value::BasicBlockVal), Parent(nullptr) {
 
   if (NewParent)
     insertInto(NewParent, InsertBefore);
@@ -216,16 +56,12 @@ BasicBlock::BasicBlock(LLVMContext &C, const Twine &Name, Function *NewParent,
            "Cannot insert block before another block with no function!");
 
   setName(Name);
-  if (NewParent)
-    setIsNewDbgInfoFormat(NewParent->IsNewDbgInfoFormat);
 }
 
 void BasicBlock::insertInto(Function *NewParent, BasicBlock *InsertBefore) {
   assert(NewParent && "Expected a parent");
   assert(!Parent && "Already has a parent");
 
-  setIsNewDbgInfoFormat(NewParent->IsNewDbgInfoFormat);
-
   if (InsertBefore)
     NewParent->insert(InsertBefore->getIterator(), this);
   else
@@ -255,11 +91,6 @@ BasicBlock::~BasicBlock() {
 
   assert(getParent() == nullptr && "BasicBlock still linked into the program!");
   dropAllReferences();
-  for (auto &Inst : *this) {
-    if (!Inst.DbgMarker)
-      continue;
-    Inst.DbgMarker->eraseFromParent();
-  }
   InstList.clear();
 }
 
@@ -757,16 +588,3 @@ void BasicBlock::validateInstrOrdering() const {
   }
 }
 #endif
-
-void BasicBlock::setTrailingDPValues(DPMarker *foo) {
-  getContext().pImpl->setTrailingDPValues(this, foo);
-}
-
-DPMarker *BasicBlock::getTrailingDPValues() {
-  return getContext().pImpl->getTrailingDPValues(this);
-}
-
-void BasicBlock::deleteTrailingDPValues() {
-  getContext().pImpl->deleteTrailingDPValues(this);
-}
-
diff --git a/llvm/lib/IR/CMakeLists.txt b/llvm/lib/IR/CMakeLists.txt
index 5fe3d80..d9656a2 100644
--- a/llvm/lib/IR/CMakeLists.txt
+++ b/llvm/lib/IR/CMakeLists.txt
@@ -17,7 +17,6 @@ add_llvm_component_library(LLVMCore
   DataLayout.cpp
   DebugInfo.cpp
   DebugInfoMetadata.cpp
-  DebugProgramInstruction.cpp
   DebugLoc.cpp
   DiagnosticHandler.cpp
   DiagnosticInfo.cpp
diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index e05fd29d..f7f3612 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -2135,14 +2135,8 @@ void DIArgList::handleChangedOperand(void *Ref, Metadata *New) {
     }
   }
   if (Uniq) {
-    MDNode *UniqueArgList = uniquify();
-    if (UniqueArgList != this) {
-      replaceAllUsesWith(UniqueArgList);
-      // Clear this here so we don't try to untrack in the destructor.
-      Args.clear();
-      delete this;
-      return;
-    }
+    if (uniquify() != this)
+      storeDistinctInContext();
   }
   track();
 }
diff --git a/llvm/lib/IR/DebugProgramInstruction.cpp b/llvm/lib/IR/DebugProgramInstruction.cpp
deleted file mode 100644
index 3f39bae..0000000
--- a/llvm/lib/IR/DebugProgramInstruction.cpp
+++ /dev/null
@@ -1,353 +0,0 @@
-//======-- DebugProgramInstruction.cpp - Implement DPValues/DPMarkers --======//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/IR/DebugProgramInstruction.h"
-#include "llvm/IR/DIBuilder.h"
-#include "llvm/IR/IntrinsicInst.h"
-
-namespace llvm {
-
-DPValue::DPValue(const DbgVariableIntrinsic *DVI)
-    : DebugValueUser(DVI->getRawLocation()), Variable(DVI->getVariable()),
-      Expression(DVI->getExpression()), DbgLoc(DVI->getDebugLoc()) {
-  switch (DVI->getIntrinsicID()) {
-  case Intrinsic::dbg_value:
-    Type = LocationType::Value;
-    break;
-  case Intrinsic::dbg_declare:
-    Type = LocationType::Declare;
-    break;
-  default:
-    llvm_unreachable(
-        "Trying to create a DPValue with an invalid intrinsic type!");
-  }
-}
-
-DPValue::DPValue(const DPValue &DPV)
-    : DebugValueUser(DPV.getRawLocation()),
-      Variable(DPV.getVariable()), Expression(DPV.getExpression()),
-      DbgLoc(DPV.getDebugLoc()), Type(DPV.getType()) {}
-
-DPValue::DPValue(Metadata *Location, DILocalVariable *DV, DIExpression *Expr,
-                 const DILocation *DI)
-    : DebugValueUser(Location), Variable(DV), Expression(Expr), DbgLoc(DI),
-      Type(LocationType::Value) {
-}
-
-void DPValue::deleteInstr() { delete this; }
-
-iterator_range<DPValue::location_op_iterator> DPValue::location_ops() const {
-  auto *MD = getRawLocation();
-  // If a Value has been deleted, the "location" for this DPValue will be
-  // replaced by nullptr. Return an empty range.
-  if (!MD)
-    return {location_op_iterator(static_cast<ValueAsMetadata *>(nullptr)),
-            location_op_iterator(static_cast<ValueAsMetadata *>(nullptr))};
-
-  // If operand is ValueAsMetadata, return a range over just that operand.
-  if (auto *VAM = dyn_cast<ValueAsMetadata>(MD))
-    return {location_op_iterator(VAM), location_op_iterator(VAM + 1)};
-
-  // If operand is DIArgList, return a range over its args.
-  if (auto *AL = dyn_cast<DIArgList>(MD))
-    return {location_op_iterator(AL->args_begin()),
-            location_op_iterator(AL->args_end())};
-
-  // Operand is an empty metadata tuple, so return empty iterator.
-  assert(cast<MDNode>(MD)->getNumOperands() == 0);
-  return {location_op_iterator(static_cast<ValueAsMetadata *>(nullptr)),
-          location_op_iterator(static_cast<ValueAsMetadata *>(nullptr))};
-}
-
-Value *DPValue::getVariableLocationOp(unsigned OpIdx) const {
-  auto *MD = getRawLocation();
-  if (!MD)
-    return nullptr;
-
-  if (auto *AL = dyn_cast<DIArgList>(MD))
-    return AL->getArgs()[OpIdx]->getValue();
-  if (isa<MDNode>(MD))
-    return nullptr;
-  assert(isa<ValueAsMetadata>(MD) &&
-         "Attempted to get location operand from DPValue with none.");
-  auto *V = cast<ValueAsMetadata>(MD);
-  assert(OpIdx == 0 && "Operand Index must be 0 for a debug intrinsic with a "
-                       "single location operand.");
-  return V->getValue();
-}
-
-static ValueAsMetadata *getAsMetadata(Value *V) {
-  return isa<MetadataAsValue>(V) ? dyn_cast<ValueAsMetadata>(
-                                       cast<MetadataAsValue>(V)->getMetadata())
-                                 : ValueAsMetadata::get(V);
-}
-
-void DPValue::replaceVariableLocationOp(Value *OldValue, Value *NewValue,
-                                        bool AllowEmpty) {
-  assert(NewValue && "Values must be non-null");
-  auto Locations = location_ops();
-  auto OldIt = find(Locations, OldValue);
-  if (OldIt == Locations.end()) {
-    if (AllowEmpty)
-      return;
-    llvm_unreachable("OldValue must be a current location");
-  }
-
-  if (!hasArgList()) {
-    // Set our location to be the MAV wrapping the new Value.
-    setRawLocation(isa<MetadataAsValue>(NewValue)
-                       ? cast<MetadataAsValue>(NewValue)->getMetadata()
-                       : ValueAsMetadata::get(NewValue));
-    return;
-  }
-
-  // We must be referring to a DIArgList, produce a new operands vector with the
-  // old value replaced, generate a new DIArgList and set it as our location.
-  SmallVector<ValueAsMetadata *, 4> MDs;
-  ValueAsMetadata *NewOperand = getAsMetadata(NewValue);
-  for (auto *VMD : Locations)
-    MDs.push_back(VMD == *OldIt ? NewOperand : getAsMetadata(VMD));
-  setRawLocation(DIArgList::get(getVariableLocationOp(0)->getContext(), MDs));
-}
-
-void DPValue::replaceVariableLocationOp(unsigned OpIdx, Value *NewValue) {
-  assert(OpIdx < getNumVariableLocationOps() && "Invalid Operand Index");
-
-  if (!hasArgList()) {
-    setRawLocation(isa<MetadataAsValue>(NewValue)
-                       ? cast<MetadataAsValue>(NewValue)->getMetadata()
-                       : ValueAsMetadata::get(NewValue));
-    return;
-  }
-
-  SmallVector<ValueAsMetadata *, 4> MDs;
-  ValueAsMetadata *NewOperand = getAsMetadata(NewValue);
-  for (unsigned Idx = 0; Idx < getNumVariableLocationOps(); ++Idx)
-    MDs.push_back(Idx == OpIdx ? NewOperand
-                               : getAsMetadata(getVariableLocationOp(Idx)));
-
-  setRawLocation(DIArgList::get(getVariableLocationOp(0)->getContext(), MDs));
-}
-
-void DPValue::addVariableLocationOps(ArrayRef<Value *> NewValues,
-                                     DIExpression *NewExpr) {
-  assert(NewExpr->hasAllLocationOps(getNumVariableLocationOps() +
-                                    NewValues.size()) &&
-         "NewExpr for debug variable intrinsic does not reference every "
-         "location operand.");
-  assert(!is_contained(NewValues, nullptr) && "New values must be non-null");
-  setExpression(NewExpr);
-  SmallVector<ValueAsMetadata *, 4> MDs;
-  for (auto *VMD : location_ops())
-    MDs.push_back(getAsMetadata(VMD));
-  for (auto *VMD : NewValues)
-    MDs.push_back(getAsMetadata(VMD));
-  setRawLocation(DIArgList::get(getVariableLocationOp(0)->getContext(), MDs));
-}
-
-std::optional<uint64_t> DPValue::getFragmentSizeInBits() const {
-  if (auto Fragment = getExpression()->getFragmentInfo())
-    return Fragment->SizeInBits;
-  return getVariable()->getSizeInBits();
-}
-
-DPValue *DPValue::clone() const { return new DPValue(*this); }
-
-DbgVariableIntrinsic *
-DPValue::createDebugIntrinsic(Module *M, Instruction *InsertBefore) const {
-  [[maybe_unused]] DICompileUnit *Unit =
-      getDebugLoc().get()->getScope()->getSubprogram()->getUnit();
-  assert(M && Unit &&
-         "Cannot clone from BasicBlock that is not part of a Module or "
-         "DICompileUnit!");
-  LLVMContext &Context = getDebugLoc()->getContext();
-  Value *Args[] = {MetadataAsValue::get(Context, getRawLocation()),
-                   MetadataAsValue::get(Context, getVariable()),
-                   MetadataAsValue::get(Context, getExpression())};
-  Function *IntrinsicFn;
-
-  // Work out what sort of intrinsic we're going to produce.
-  switch (getType()) {
-  case DPValue::LocationType::Declare:
-    IntrinsicFn = Intrinsic::getDeclaration(M, Intrinsic::dbg_declare);
-    break;
-  case DPValue::LocationType::Value:
-    IntrinsicFn = Intrinsic::getDeclaration(M, Intrinsic::dbg_value);
-    break;
-  }
-
-  // Create the intrinsic from this DPValue's information, optionally insert
-  // into the target location.
-  DbgVariableIntrinsic *DVI = cast<DbgVariableIntrinsic>(
-      CallInst::Create(IntrinsicFn->getFunctionType(), IntrinsicFn, Args));
-  DVI->setTailCall();
-  DVI->setDebugLoc(getDebugLoc());
-  if (InsertBefore)
-    DVI->insertBefore(InsertBefore);
-
-  return DVI;
-}
-
-void DPValue::handleChangedLocation(Metadata *NewLocation) {
-  resetDebugValue(NewLocation);
-}
-
-const BasicBlock *DPValue::getParent() const {
-  return Marker->MarkedInstr->getParent();
-}
-
-BasicBlock *DPValue::getParent() { return Marker->MarkedInstr->getParent(); }
-
-BasicBlock *DPValue::getBlock() { return Marker->getParent(); }
-
-const BasicBlock *DPValue::getBlock() const { return Marker->getParent(); }
-
-Function *DPValue::getFunction() { return getBlock()->getParent(); }
-
-const Function *DPValue::getFunction() const { return getBlock()->getParent(); }
-
-Module *DPValue::getModule() { return getFunction()->getParent(); }
-
-const Module *DPValue::getModule() const { return getFunction()->getParent(); }
-
-LLVMContext &DPValue::getContext() { return getBlock()->getContext(); }
-
-const LLVMContext &DPValue::getContext() const {
-  return getBlock()->getContext();
-}
-
-///////////////////////////////////////////////////////////////////////////////
-
-// An empty, global, DPMarker for the purpose of describing empty ranges of
-// DPValues.
-DPMarker DPMarker::EmptyDPMarker;
-
-void DPMarker::dropDPValues() {
-  while (!StoredDPValues.empty()) {
-    auto It = StoredDPValues.begin();
-    DPValue *DPV = &*It;
-    StoredDPValues.erase(It);
-    DPV->deleteInstr();
-  }
-}
-
-void DPMarker::dropOneDPValue(DPValue *DPV) {
-  assert(DPV->getMarker() == this);
-  StoredDPValues.erase(DPV->getIterator());
-  DPV->deleteInstr();
-}
-
-const BasicBlock *DPMarker::getParent() const {
-  return MarkedInstr->getParent();
-}
-
-BasicBlock *DPMarker::getParent() { return MarkedInstr->getParent(); }
-
-void DPMarker::removeMarker() {
-  // Are there any DPValues in this DPMarker? If not, nothing to preserve.
-  Instruction *Owner = MarkedInstr;
-  if (StoredDPValues.empty()) {
-    eraseFromParent();
-    Owner->DbgMarker = nullptr;
-    return;
-  }
-
-  // The attached DPValues need to be preserved; attach them to the next
-  // instruction. If there isn't a next instruction, put them on the
-  // "trailing" list.
-  // (This logic gets refactored in a future patch, needed to break some
-  //  dependencies here).
-  BasicBlock::iterator NextInst = std::next(Owner->getIterator());
-  DPMarker *NextMarker;
-  if (NextInst == Owner->getParent()->end()) {
-    NextMarker = new DPMarker();
-    Owner->getParent()->setTrailingDPValues(NextMarker);
-  } else {
-    NextMarker = NextInst->DbgMarker;
-  }
-  NextMarker->absorbDebugValues(*this, true);
-
-  eraseFromParent();
-}
-
-void DPMarker::removeFromParent() {
-  MarkedInstr->DbgMarker = nullptr;
-  MarkedInstr = nullptr;
-}
-
-void DPMarker::eraseFromParent() {
-  if (MarkedInstr)
-    removeFromParent();
-  dropDPValues();
-  delete this;
-}
-
-iterator_range<DPValue::self_iterator> DPMarker::getDbgValueRange() {
-  return make_range(StoredDPValues.begin(), StoredDPValues.end());
-}
-
-void DPValue::removeFromParent() {
-  getMarker()->StoredDPValues.erase(getIterator());
-}
-
-void DPValue::eraseFromParent() {
-  removeFromParent();
-  deleteInstr();
-}
-
-void DPMarker::insertDPValue(DPValue *New, bool InsertAtHead) {
-  auto It = InsertAtHead ? StoredDPValues.begin() : StoredDPValues.end();
-  StoredDPValues.insert(It, *New);
-  New->setMarker(this);
-}
-
-void DPMarker::absorbDebugValues(DPMarker &Src, bool InsertAtHead) {
-  auto It = InsertAtHead ? StoredDPValues.begin() : StoredDPValues.end();
-  for (DPValue &DPV : Src.StoredDPValues)
-    DPV.setMarker(this);
-
-  StoredDPValues.splice(It, Src.StoredDPValues);
-}
-
-iterator_range<simple_ilist<DPValue>::iterator> DPMarker::cloneDebugInfoFrom(
-    DPMarker *From, std::optional<simple_ilist<DPValue>::iterator> from_here,
-    bool InsertAtHead) {
-  DPValue *First = nullptr;
-  // Work out what range of DPValues to clone: normally all the contents of the
-  // "From" marker, optionally we can start from the from_here position down to
-  // end().
-  auto Range =
-      make_range(From->StoredDPValues.begin(), From->StoredDPValues.end());
-  if (from_here.has_value())
-    Range = make_range(*from_here, From->StoredDPValues.end());
-
-  // Clone each DPValue and insert into StoreDPValues; optionally place them at
-  // the start or the end of the list.
-  auto Pos = (InsertAtHead) ? StoredDPValues.begin() : StoredDPValues.end();
-  for (DPValue &DPV : Range) {
-    DPValue *New = DPV.clone();
-    New->setMarker(this);
-    StoredDPValues.insert(Pos, *New);
-    if (!First)
-      First = New;
-  }
-
-  if (!First)
-    return {StoredDPValues.end(), StoredDPValues.end()};
-
-  if (InsertAtHead)
-    // If InsertAtHead is set, we cloned a range onto the front of of the
-    // StoredDPValues collection, return that range.
-    return {StoredDPValues.begin(), Pos};
-  else
-    // We inserted a block at the end, return that range.
-    return {First->getIterator(), StoredDPValues.end()};
-}
-
-} // end namespace llvm
-
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 49e0c1c..658aa67 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -81,27 +81,6 @@ static cl::opt<unsigned> NonGlobalValueMaxNameSize(
     "non-global-value-max-name-size", cl::Hidden, cl::init(1024),
     cl::desc("Maximum size for the name of non-global values."));
 
-void Function::convertToNewDbgValues() {
-  IsNewDbgInfoFormat = true;
-  for (auto &BB : *this) {
-    BB.convertToNewDbgValues();
-  }
-}
-
-void Function::convertFromNewDbgValues() {
-  IsNewDbgInfoFormat = false;
-  for (auto &BB : *this) {
-    BB.convertFromNewDbgValues();
-  }
-}
-
-void Function::setIsNewDbgInfoFormat(bool NewFlag) {
-  if (NewFlag && !IsNewDbgInfoFormat)
-    convertToNewDbgValues();
-  else if (!NewFlag && IsNewDbgInfoFormat)
-    convertFromNewDbgValues();
-}
-
 //===----------------------------------------------------------------------===//
 // Argument Implementation
 //===----------------------------------------------------------------------===//
@@ -423,7 +402,7 @@ Function::Function(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace,
     : GlobalObject(Ty, Value::FunctionVal,
                    OperandTraits<Function>::op_begin(this), 0, Linkage, name,
                    computeAddrSpace(AddrSpace, ParentModule)),
-      NumArgs(Ty->getNumParams()), IsNewDbgInfoFormat(false) {
+      NumArgs(Ty->getNumParams()) {
   assert(FunctionType::isValidReturnType(getReturnType()) &&
          "invalid return type");
   setGlobalObjectSubClassData(0);
diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index 406850b..2076eee 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -45,14 +45,6 @@ LLVMContextImpl::LLVMContextImpl(LLVMContext &C)
       Int16Ty(C, 16), Int32Ty(C, 32), Int64Ty(C, 64), Int128Ty(C, 128) {}
 
 LLVMContextImpl::~LLVMContextImpl() {
-#ifndef NDEBUG
-  // Check that any variable location records that fell off the end of a block
-  // when it's terminator was removed were eventually replaced. This assertion
-  // firing indicates that DPValues went missing during the lifetime of the
-  // LLVMContext.
-  assert(TrailingDPValues.empty() && "DPValue records in blocks not cleaned");
-#endif
-
   // NOTE: We need to delete the contents of OwnedModules, but Module's dtor
   // will call LLVMContextImpl::removeModule, thus invalidating iterators into
   // the container. Avoid iterators during this operation:
diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index ebc444f..4cc3f8d 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -57,7 +57,6 @@ class AttributeListImpl;
 class AttributeSetNode;
 class BasicBlock;
 struct DiagnosticHandler;
-class DPMarker;
 class ElementCount;
 class Function;
 class GlobalObject;
@@ -1634,36 +1633,6 @@ public:
   /// The lifetime of the object must be guaranteed to extend as long as the
   /// LLVMContext is used by compilation.
   void setOptPassGate(OptPassGate &);
-
-  /// Mapping of blocks to collections of "trailing" DPValues. As part of the
-  /// "RemoveDIs" project, debug-info variable location records are going to
-  /// cease being instructions... which raises the problem of where should they
-  /// be recorded when we remove the terminator of a blocks, such as:
-  ///
-  ///    %foo = add i32 0, 0
-  ///    br label %bar
-  ///
-  /// If the branch is removed, a legitimate transient state while editing a
-  /// block, any debug-records between those two instructions will not have a
-  /// location. Each block thus records any DPValue records that "trail" in
-  /// such a way. These are stored in LLVMContext because typically LLVM only
-  /// edits a small number of blocks at a time, so there's no need to bloat
-  /// BasicBlock with such a data structure.
-  SmallDenseMap<BasicBlock *, DPMarker *> TrailingDPValues;
-
-  // Set, get and delete operations for TrailingDPValues.
-  void setTrailingDPValues(BasicBlock *B, DPMarker *M) {
-    assert(!TrailingDPValues.count(B));
-    TrailingDPValues[B] = M;
-  }
-
-  DPMarker *getTrailingDPValues(BasicBlock *B) {
-    return TrailingDPValues.lookup(B);
-  }
-
-  void deleteTrailingDPValues(BasicBlock *B) {
-    TrailingDPValues.erase(B);
-  }
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/IR/Metadata.cpp b/llvm/lib/IR/Metadata.cpp
index 5d0cd33..7860280 100644
--- a/llvm/lib/IR/Metadata.cpp
+++ b/llvm/lib/IR/Metadata.cpp
@@ -147,32 +147,6 @@ void MetadataAsValue::untrack() {
     MetadataTracking::untrack(MD);
 }
 
-DPValue *DebugValueUser::getUser() { return static_cast<DPValue *>(this); }
-const DPValue *DebugValueUser::getUser() const {
-  return static_cast<const DPValue *>(this);
-}
-void DebugValueUser::handleChangedValue(Metadata *NewMD) {
-  getUser()->handleChangedLocation(NewMD);
-}
-
-void DebugValueUser::trackDebugValue() {
-  if (DebugValue)
-    MetadataTracking::track(&DebugValue, *DebugValue, *this);
-}
-
-void DebugValueUser::untrackDebugValue() {
-  if (DebugValue)
-    MetadataTracking::untrack(DebugValue);
-}
-
-void DebugValueUser::retrackDebugValue(DebugValueUser &X) {
-  assert(DebugValue == X.DebugValue && "Expected values to match");
-  if (X.DebugValue) {
-    MetadataTracking::retrack(X.DebugValue, DebugValue);
-    X.DebugValue = nullptr;
-  }
-}
-
 bool MetadataTracking::track(void *Ref, Metadata &MD, OwnerTy Owner) {
   assert(Ref && "Expected live reference");
   assert((Owner || *static_cast<Metadata **>(Ref) == &MD) &&
@@ -221,8 +195,6 @@ SmallVector<Metadata *> ReplaceableMetadataImpl::getAllArgListUsers() {
   SmallVector<std::pair<OwnerTy, uint64_t> *> MDUsersWithID;
   for (auto Pair : UseMap) {
     OwnerTy Owner = Pair.second.first;
-    if (Owner.isNull())
-      continue;
     if (!isa<Metadata *>(Owner))
       continue;
     Metadata *OwnerMD = cast<Metadata *>(Owner);
@@ -238,25 +210,6 @@ SmallVector<Metadata *> ReplaceableMetadataImpl::getAllArgListUsers() {
   return MDUsers;
 }
 
-SmallVector<DPValue *> ReplaceableMetadataImpl::getAllDPValueUsers() {
-  SmallVector<std::pair<OwnerTy, uint64_t> *> DPVUsersWithID;
-  for (auto Pair : UseMap) {
-    OwnerTy Owner = Pair.second.first;
-    if (Owner.isNull())
-      continue;
-    if (!Owner.is<DebugValueUser *>())
-      continue;
-    DPVUsersWithID.push_back(&UseMap[Pair.first]);
-  }
-  llvm::sort(DPVUsersWithID, [](auto UserA, auto UserB) {
-    return UserA->second < UserB->second;
-  });
-  SmallVector<DPValue *> DPVUsers;
-  for (auto UserWithID : DPVUsersWithID)
-    DPVUsers.push_back(UserWithID->first.get<DebugValueUser *>()->getUser());
-  return DPVUsers;
-}
-
 void ReplaceableMetadataImpl::addRef(void *Ref, OwnerTy Owner) {
   bool WasInserted =
       UseMap.insert(std::make_pair(Ref, std::make_pair(Owner, NextIndex)))
@@ -355,11 +308,6 @@ void ReplaceableMetadataImpl::replaceAllUsesWith(Metadata *MD) {
       continue;
     }
 
-    if (Owner.is<DebugValueUser *>()) {
-      Owner.get<DebugValueUser *>()->getUser()->handleChangedLocation(MD);
-      continue;
-    }
-
     // There's a Metadata owner -- dispatch.
     Metadata *OwnerMD = cast<Metadata *>(Owner);
     switch (OwnerMD->getMetadataID()) {
@@ -395,7 +343,7 @@ void ReplaceableMetadataImpl::resolveAllUses(bool ResolveUsers) {
     auto Owner = Pair.second.first;
     if (!Owner)
       continue;
-    if (!Owner.is<Metadata *>())
+    if (isa<MetadataAsValue *>(Owner))
       continue;
 
     // Resolve MDNodes that point at this.
@@ -409,25 +357,18 @@ void ReplaceableMetadataImpl::resolveAllUses(bool ResolveUsers) {
 }
 
 ReplaceableMetadataImpl *ReplaceableMetadataImpl::getOrCreate(Metadata &MD) {
-  if (auto ArgList = dyn_cast<DIArgList>(&MD))
-    return ArgList->Context.getOrCreateReplaceableUses();
   if (auto *N = dyn_cast<MDNode>(&MD))
     return N->isResolved() ? nullptr : N->Context.getOrCreateReplaceableUses();
   return dyn_cast<ValueAsMetadata>(&MD);
 }
 
 ReplaceableMetadataImpl *ReplaceableMetadataImpl::getIfExists(Metadata &MD) {
-  if (auto ArgList = dyn_cast<DIArgList>(&MD)) {
-    return ArgList->Context.getOrCreateReplaceableUses();
-  }
   if (auto *N = dyn_cast<MDNode>(&MD))
     return N->isResolved() ? nullptr : N->Context.getReplaceableUses();
   return dyn_cast<ValueAsMetadata>(&MD);
 }
 
 bool ReplaceableMetadataImpl::isReplaceable(const Metadata &MD) {
-  if (isa<DIArgList>(&MD))
-    return true;
   if (auto *N = dyn_cast<MDNode>(&MD))
     return !N->isResolved();
   return isa<ValueAsMetadata>(&MD);
diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp
index 17efe79..dba660b 100644
--- a/llvm/lib/IR/Module.cpp
+++ b/llvm/lib/IR/Module.cpp
@@ -71,8 +71,7 @@ template class llvm::SymbolTableListTraits<GlobalIFunc>;
 
 Module::Module(StringRef MID, LLVMContext &C)
     : Context(C), ValSymTab(std::make_unique<ValueSymbolTable>(-1)),
-      ModuleID(std::string(MID)), SourceFileName(std::string(MID)), DL(""),
-      IsNewDbgInfoFormat(false) {
+      ModuleID(std::string(MID)), SourceFileName(std::string(MID)), DL("") {
   Context.addModule(this);
 }
 
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index e35f9fb..d3db7a1 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -2941,14 +2941,6 @@ void Verifier::visitBasicBlock(BasicBlock &BB) {
   {
     Check(I.getParent() == &BB, "Instruction has bogus parent pointer!");
   }
-
-  // Confirm that no issues arise from the debug program.
-  if (BB.IsNewDbgInfoFormat) {
-    // Configure the validate function to not fire assertions, instead print
-    // errors and return true if there's a problem.
-    bool RetVal = BB.validateDbgValues(false, true, OS);
-    Check(!RetVal, "Invalid configuration of new-debug-info data found");
-  }
 }
 
 void Verifier::visitTerminator(Instruction &I) {