[DebugInfo] Allow non-stack_value variadic expressions and use in DBG_INSTR_REF

[StephenTozer]

Summary

Prior to this patch, variadic DIExpressions (i.e. ones that contain DW_OP_LLVM_arg) could only be created by salvaging debug values to create stack value expressions, resulting in a DBG_VALUE_LIST being created. As of the previous patch in this patch stack, DBG_INSTR_REF's syntax has been changed to match DBG_VALUE_LIST in preparation for supporting variadic expressions. This patch adds some minor changes needed to allow variadic expressions that aren't stack values to exist, and allows variadic expressions that are trivially reduceable to non-variadic expressions to be handled similarly to non-variadic expressions.

[StephenTozer]

Move test changes ahead into this patch.

[jmorse]

Generally looks good, I've got a couple of questions inline.

Are there any serious performance implications for, in the direction these patches are moving in, there being lots of non-empty DIExpressions compared to today when they're mostly empty? (I'm thinking we might need a static, pre-allocated one in LLVMContext, if every variable is going to allocate one).

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

1135–1140

Just to check -- this is purely for printing the informative comments on assembly output, it isn't actually functional, yes?

llvm/lib/IR/DebugInfoMetadata.cpp

1633–1641

Just to confirm, the reason why this wasn't present before was because all variadic expressions had to be stack_value, yes?

llvm/test/DebugInfo/MIR/InstrRef/dbg-phi-subregister-location.mir

13

Does this patch actually make some DBG_VALUEs become DBG_VALUE_LIST? I've missed that part, and see it's happening in various tests.

[jmorse]

(Lo and behold, I already asked that last question in D133929, never mind about that)

[StephenTozer]

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

1135–1140

Correct, this is just removing noise from the patch - even if it was an expression being used somewhere, it'd still have the same meaning either way, just formatted slightly differently.

llvm/lib/IR/DebugInfoMetadata.cpp

1633–1641

Correct - worth noting the only reason they "had" to be stack_value was because they're only naturally produced by salvaging operations that create stack_value expressions, not because there's some inherent incompatibility.

[StephenTozer]

Updated ISel and LDV to have very basic handling of "variadic" DBG_INSTR_REFs, and updated tests to use DW_OP_LLVM_arg.

[StephenTozer]

llvm/test/DebugInfo/MIR/InstrRef/dbg-phi-subregister-location.mir

13

Missed this question - this patch changes DBG_INSTR_REF to have the same syntax as a DBG_VALUE_LIST, which includes having the variadic flag set, hence LDV will output the debug value produced from a DBG_INSTR_REF as a DBG_VALUE_LIST.

[StephenTozer]

Move some changes from an earlier patch into this one: Make entry value expressions containing only a leading DW_OP_LLVM_arg, 0 valid, as the changes in this patch enable such expressions. Also add the convertToVariadicExpression function, as this is the first patch in which it is used.

[jmorse]

Looks good (leaning largely on my prior review).

[StephenTozer]

Rebased onto latest master, added unit tests for convertToVariadicExpression.

[fdeazeve]

Sorry to bump this review, but I'm currently investigating a couple of bugs which I believe are a result of this patch.

One thing that seems off here is that now the definition of isEntryValue is incorrect:

bool DIExpression::isEntryValue() const {
  return getNumElements() > 0 && getElement(0) == dwarf::DW_OP_LLVM_entry_value;
}

Also note that the CodeGen/AsmPrinter/DwarfExpression.cpp code for DwarfExpression::addExpression doesn't expect an EntryValue as anything but the first operand of the op list.

Still investigating how to handle those, but figured I'd give you a heads up in case you have ideas

[StephenTozer]

In D133926#4591953, @fdeazeve wrote:

Sorry to bump this review, but I'm currently investigating a couple of bugs which I believe are a result of this patch.

One thing that seems off here is that now the definition of isEntryValue is incorrect:

bool DIExpression::isEntryValue() const {
  return getNumElements() > 0 && getElement(0) == dwarf::DW_OP_LLVM_entry_value;
}

Also note that the CodeGen/AsmPrinter/DwarfExpression.cpp code for DwarfExpression::addExpression doesn't expect an EntryValue as anything but the first operand of the op list.

Still investigating how to handle those, but figured I'd give you a heads up in case you have ideas

I'll take a quick look - off the top of my head, there should be an interface to treat !DIExpression(DW_OP_LLVM_arg, 0, <ops>) identically to !DIExpression(<ops>), and if it either doesn't exist or is only applicable to specific cases then it should be created/generalized.

[fdeazeve]

I'll take a quick look - off the top of my head, there should be an interface to treat !DIExpression(DW_OP_LLVM_arg, 0, <ops>) identically to !DIExpression(<ops>), and if it either doesn't exist or is only applicable to specific cases then it should be created/generalized.

Thank you!

Also note that the CodeGen/AsmPrinter/DwarfExpression.cpp code for DwarfExpression::addExpression doesn't expect an EntryValue as anything but the first operand of the op list.

I think the problem here is that, inside DwarfCompileUnit::constructVariableDIEImpl, we are now taking the *variadic path* which ends up calling addExpression.
More concretely, inside that function we have:

if (auto *DVal = DV.getValueLoc()) {
  if (!DVal->isVariadic()) {

We are taking the else path of that second if, i.e., we are treating things as variadic where we before we wouldn't?

(lldb) p DV.getValueLoc()->isVariadic()
(bool) $2 = true
(lldb) p DV.getValueLoc()->dump()
Loc = { reg=134 } !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_entry_value, 1, DW_OP_plus_uconst, 16, DW_OP_plus_uconst, 16, DW_OP_deref, DW_OP_deref)

Because of this, we end up calling DwarfExpression::addExpression, which crashes for that example because it doesn't expect an entry value.

[StephenTozer]

In D133926#4592629, @fdeazeve wrote:

Because of this, we end up calling DwarfExpression::addExpression, which crashes for that example because it doesn't expect an entry value.

Thanks for the further details - in summary, as part of the changes to DBG_INSTR_REF, we started using the variadic syntax for debug values that would normally have been non-variadic - there's no fundamental problem with this, but clearly some edges weren't fully ironed out. I'll submit a patch shortly with a fix - do you have a reproducer for the issue?

[fdeazeve]

In D133926#4594914, @StephenTozer wrote:

In D133926#4592629, @fdeazeve wrote:

Because of this, we end up calling DwarfExpression::addExpression, which crashes for that example because it doesn't expect an entry value.

Thanks for the further details - in summary, as part of the changes to DBG_INSTR_REF, we started using the variadic syntax for debug values that would normally have been non-variadic - there's no fundamental problem with this, but clearly some edges weren't fully ironed out. I'll submit a patch shortly with a fix - do you have a reproducer for the issue?

Yup, that makes perfect sense. Let me see if I can conjure a min repro and I'll come back here shortly.

[fdeazeve]

Could you give this a try? It repros for me with a llc test.ll.

target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx12.1.0"

declare void @llvm.dbg.value(metadata, metadata, metadata) #0

define swifttailcc void @"blah"(ptr swiftasync %0) !dbg !26 {
  %use = getelementptr i8, ptr %0, i64 9
  call void @llvm.dbg.value(metadata ptr %0, metadata !30, metadata !DIExpression(DW_OP_LLVM_entry_value, 1, DW_OP_plus_uconst, 16, DW_OP_plus_uconst, 16, DW_OP_deref, DW_OP_deref)), !dbg !34
  %use1 = load i32, ptr null, !dbg !45
  %use2 = sext i32 %use1 to i64
  %use3 = getelementptr i8, ptr null, i64 %use2
  store ptr %use3, ptr %0
  ret void
}

attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }

!llvm.module.flags = !{!0}
!llvm.dbg.cu = !{!1}

!0 = !{i32 2, !"Debug Info Version", i32 3}
!1 = distinct !DICompileUnit(language: DW_LANG_Swift, file: !7, producer: "blah", isOptimized: true, flags: "blah", runtimeVersion: 5, emissionKind: FullDebug, globals: !3, imports: !10, sysroot: "blah", sdk: "blah")
!3 = !{!4, !11}
!4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
!5 = distinct !DIGlobalVariable(name: "blah", linkageName: "blah", scope: !6, file: !7, line: 49, type: !8, isLocal: true, isDefinition: true)
!6 = !DIModule(scope: null, name: "blah", includePath: "blah")
!7 = !DIFile(filename: "blah", directory: "blah")
!8 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !9)
!9 = !DICompositeType(tag: DW_TAG_structure_type, name: "blah", scope: !6, file: !7, size: 64, elements: !10, runtimeLang: DW_LANG_Swift, identifier: "blah")
!10 = !{}
!11 = !DIGlobalVariableExpression(var: !12, expr: !DIExpression())
!12 = distinct !DIGlobalVariable(name: "blah", linkageName: "blah", scope: !6, file: !7, line: 44, type: !14, isLocal: false, isDefinition: true)
!14 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !15)
!15 = !DICompositeType(tag: DW_TAG_structure_type, name: "blah", scope: !17, file: !7, size: 64, elements: !10, runtimeLang: DW_LANG_Swift, identifier: "blah")
!17 = !DIModule(scope: null, name: "blah", configMacros: "blah", includePath: "blah")
!26 = distinct !DISubprogram(name: "blah", linkageName: "blah", scope: !28, file: !7, line: 115, type: !29, scopeLine: 117, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !1, retainedNodes: !10, thrownTypes: !10)
!28 = !DICompositeType(tag: DW_TAG_structure_type, name: "blah", scope: !6, file: !7, elements: !10, runtimeLang: DW_LANG_Swift, identifier: "blah")
!29 = !DISubroutineType(types: !10)
!30 = !DILocalVariable(name: "blah", arg: 1, scope: !31, file: !7, line: 95, type: !33, flags: DIFlagArtificial)
!31 = distinct !DISubprogram(name: "blah", linkageName: "blah", scope: !28, file: !7, line: 95, type: !32, scopeLine: 95, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !1, retainedNodes: !10)
!32 = distinct !DISubroutineType(types: !10)
!33 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !28)
!34 = !DILocation(line: 95, column: 9, scope: !31, inlinedAt: !35)
!35 = distinct !DILocation(line: 0, scope: !36, inlinedAt: !38)
!36 = distinct !DISubprogram(name: "blah", linkageName: "blah", scope: !28, file: !7, type: !32, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !1)
!38 = distinct !DILocation(line: 121, column: 36, scope: !44)
!44 = distinct !DILexicalBlock(scope: !26, file: !7, line: 116, column: 7)
!45 = !DILocation(line: 0, scope: !46, inlinedAt: !35)
!46 = !DILexicalBlockFile(scope: !31, file: !7, discriminator: 0)

[StephenTozer]

In D133926#4595209, @fdeazeve wrote:

Could you give this a try? It repros for me with a llc test.ll.

Repro is good, review opened: D158185

llvm/docs/MIRLangRef.rst

 A debug instruction reference operand is a pair of indices, referring to an
 instruction and an operand within that instruction respectively; see
 :ref:`Instruction referencing locations <instruction-referencing-locations>`.
 
 The example below uses a reference to Instruction 1, Operand 0:
 
 .. code-block:: text
 
-    DBG_INSTR_REF !123, !DIExpression(), dbg-instr-ref(1, 0), debug-location !456
+    DBG_INSTR_REF !123, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !456
 
 CFIIndex Operands
 ^^^^^^^^^^^^^^^^^
 
 A CFI Index operand is holding an index into a per-function side-table,
 ``MachineFunction::getFrameInstructions()``, which references all the frame
 instructions in a ``MachineFunction``. A ``CFI_INSTRUCTION`` may look like it
 contains multiple operands, but the only operand it contains is the CFI Index.

 *values* from the program point where a variable takes on that value. Changes
 in variable value occur in the same manner as ``DBG_VALUE`` meta instructions
 but using ``DBG_INSTR_REF``. Variable values are identified by a pair of
 instruction number and operand number. Consider the example below:
 
 .. code-block:: text
 
     $rbp = MOV64ri 0, debug-instr-number 1, debug-location !12
-    DBG_INSTR_REF !123, !DIExpression(), dbg-instr-ref(1, 0), debug-location !456
+    DBG_INSTR_REF !123, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !456
 
 Instruction numbers are directly attached to machine instructions with an
 optional ``debug-instr-number`` attachment, before the optional
 ``debug-location`` attachment. The value defined in ``$rbp`` in the code
 above would be identified by the pair ``<1, 0>``.
 
 The 3rd operand of the ``DBG_INSTR_REF`` above records the instruction
 and operand number ``<1, 0>``, identifying the value defined by the ``MOV64ri``.
 The first two operands to ``DBG_INSTR_REF`` are identical to ``DBG_VALUE_LIST``,
 and the ``DBG_INSTR_REF`` s position records where the variable takes on the
 designated value in the same way.
 
 More information about how these constructs are used is available in
 :doc:`InstrRefDebugInfo`. The related documents :doc:`SourceLevelDebugging` and
 :doc:`HowToUpdateDebugInfo` may be useful as well.

llvm/include/llvm/IR/DebugInfoMetadata.h

public:
 
   /// Return whether this is an implicit location description.
   bool isImplicit() const;
 
   /// Return whether the location is computed on the expression stack, meaning
   /// it cannot be a simple register location.
   bool isComplex() const;
 
+  /// Return whether the evaluated expression makes use of a single location at
+  /// the start of the expression, i.e. if it contains only a single
+  /// DW_OP_LLVM_arg op as its first operand, or if it contains none.
+  bool isSingleLocationExpression() const;
+
+  /// If \p Expr is a non-variadic expression (i.e. one that does not contain
+  /// DW_OP_LLVM_arg), returns \p Expr converted to variadic form by adding a
+  /// leading [DW_OP_LLVM_arg, 0] to the expression; otherwise returns \p Expr.
+  static const DIExpression *
+  convertToVariadicExpression(const DIExpression *Expr);
+
   /// Inserts the elements of \p Expr into \p Ops modified to a canonical form,
   /// which uses DW_OP_LLVM_arg (i.e. is a variadic expression) and folds the
   /// implied derefence from the \p IsIndirect flag into the expression. This
   /// allows us to check equivalence between expressions with differing
   /// directness or variadicness.
   static void canonicalizeExpressionOps(SmallVectorImpl<uint64_t> &Ops,
                                         const DIExpression *Expr,
                                         bool IsIndirect);

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

if (auto *SP = dyn_cast<DISubprogram>(V->getScope())) {
     StringRef Name = SP->getName();
     if (!Name.empty())
       OS << Name << ":";
   }
   OS << V->getName();
   OS << " <- ";
 
   const DIExpression *Expr = MI->getDebugExpression();
+  if (Expr->getNumElements() && Expr->isSingleLocationExpression() &&
+      Expr->expr_op_begin()->getOp() == dwarf::DW_OP_LLVM_arg) {
+    SmallVector<uint64_t> Ops(
+        make_range(Expr->elements_begin() + 2, Expr->elements_end()));
+    Expr = DIExpression::get(Expr->getContext(), Ops);
+  }
   if (Expr->getNumElements()) {
     OS << '[';
     ListSeparator LS;
-    for (auto Op : Expr->expr_ops()) {
+    for (auto &Op : Expr->expr_ops()) {
       OS << LS << dwarf::OperationEncodingString(Op.getOp());
       for (unsigned I = 0; I < Op.getNumArgs(); ++I)
         OS << ' ' << Op.getArg(I);
     }
     OS << "] ";
   }
 
   // Register or immediate value. Register 0 means undef.

llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h

class DbgValueLoc {
 
   SmallVector<DbgValueLocEntry, 2> ValueLocEntries;
 
   bool IsVariadic;
 
 public:
   DbgValueLoc(const DIExpression *Expr, ArrayRef<DbgValueLocEntry> Locs)
       : Expression(Expr), ValueLocEntries(Locs.begin(), Locs.end()),
-        IsVariadic(true) {
-#ifndef NDEBUG
-    // Currently, DBG_VALUE_VAR expressions must use stack_value.
-    assert(Expr && Expr->isValid() &&
-           is_contained(Locs, dwarf::DW_OP_stack_value));
-#endif
-  }
+        IsVariadic(true) {}
 
   DbgValueLoc(const DIExpression *Expr, ArrayRef<DbgValueLocEntry> Locs,
               bool IsVariadic)
       : Expression(Expr), ValueLocEntries(Locs.begin(), Locs.end()),
         IsVariadic(IsVariadic) {
 #ifndef NDEBUG
     assert(cast<DIExpression>(Expr)->isValid() ||
            !any_of(Locs, [](auto LE) { return LE.isLocation(); }));
     if (!IsVariadic) {
       assert(ValueLocEntries.size() == 1);
-    } else {
-      // Currently, DBG_VALUE_VAR expressions must use stack_value.
-      assert(Expr && Expr->isValid() &&
-             is_contained(Expr->getElements(), dwarf::DW_OP_stack_value));
     }
 #endif
   }
 
   DbgValueLoc(const DIExpression *Expr, DbgValueLocEntry Loc)
       : Expression(Expr), ValueLocEntries(1, Loc), IsVariadic(false) {
     assert(((Expr && Expr->isValid()) || !Loc.isLocation()) &&
            "DBG_VALUE with a machine location must have a valid expression.");

llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp

if (LocID >= NumRegs) {
         bool StackValue = false;
 
         if (Properties.Indirect) {
           // This is something like an NRVO variable, where the pointer has been
           // spilt to the stack. It should end up being a memory location, with
           // the pointer to the variable loaded off the stack with a deref:
           assert(!Expr->isImplicit());
           OffsetOps.push_back(dwarf::DW_OP_deref);
-        } else if (UseDerefSize && !Properties.IsVariadic) {
+        } else if (UseDerefSize && Expr->isSingleLocationExpression()) {
           // TODO: Figure out how to handle deref size issues for variadic
           // values.
           // We're loading a value off the stack that's not the same size as the
           // variable. Add / subtract stack offset, explicitly deref with a
           // size, and add DW_OP_stack_value if not already present.
           OffsetOps.push_back(dwarf::DW_OP_deref_size);
           OffsetOps.push_back(DerefSizeInBytes);
           StackValue = true;
-        } else if (Expr->isComplex()) {
+        } else if (Expr->isComplex() || Properties.IsVariadic) {
           // A variable with no size ambiguity, but with extra elements in it's
           // expression. Manually dereference the stack location.
           OffsetOps.push_back(dwarf::DW_OP_deref);
         } else {
           // A plain value that has been spilt to the stack, with no further
           // context. Request a location expression, marking the DBG_VALUE as
           // IsIndirect.
           Indirect = true;
if (NewID && !MTracker->isSpill(L)) {
       NewID = std::nullopt;
     }
   }
 
   // We, we have a value number or std::nullopt. Tell the variable value tracker
   // about it. The rest of this LiveDebugValues implementation acts exactly the
   // same for DBG_INSTR_REFs as DBG_VALUEs (just, the former can refer to values
   // that aren't immediately available).
-  DbgValueProperties Properties(Expr, false, false);
+  DbgValueProperties Properties(Expr, false, true);
   SmallVector<DbgOpID> DbgOpIDs;
   if (NewID)
     DbgOpIDs.push_back(DbgOpStore.insert(*NewID));
   if (VTracker)
     VTracker->defVar(MI, Properties, DbgOpIDs);
 
   // If we're on the final pass through the function, decompose this INSTR_REF
   // into a plain DBG_VALUE.
bool InstrRefBasedLDV::transferDebugInstrRef(MachineInstr &MI,
   TTracker->redefVar(MI, Properties, NewLocs);
 
   // If there was a value with no location; but the value is defined in a
   // later instruction in this block, this is a block-local use-before-def.
   if (FoundLoc.isIllegal() && NewID && NewID->getBlock() == CurBB &&
       NewID->getInst() > CurInst) {
     SmallVector<DbgOp> UseBeforeDefLocs;
     UseBeforeDefLocs.push_back(*NewID);
-    TTracker->addUseBeforeDef(V, {MI.getDebugExpression(), false, false},
+    TTracker->addUseBeforeDef(V, {MI.getDebugExpression(), false, true},
                               UseBeforeDefLocs, NewID->getInst());
   }
 
   // Produce a DBG_VALUE representing what this DBG_INSTR_REF meant.
   // This DBG_VALUE is potentially a $noreg / undefined location, if
   // FoundLoc is illegal.
   // (XXX -- could morph the DBG_INSTR_REF in the future).
   MachineInstr *DbgMI = MTracker->emitLoc(NewLocs, V, Properties);

llvm/lib/CodeGen/LiveDebugVariables.cpp

if (LocNoVec.size() < 64) {
       }
     } else {
       LLVM_DEBUG(dbgs() << "Found debug value with 64+ unique machine "
                            "locations, dropping...\n");
       LocNoCount = 1;
       // Turn this into an undef debug value list; right now, the simplest form
       // of this is an expression with one arg, and an undef debug operand.
       Expression =
-          DIExpression::get(Expr.getContext(), {dwarf::DW_OP_LLVM_arg, 0,
-                                                dwarf::DW_OP_stack_value});
+          DIExpression::get(Expr.getContext(), {dwarf::DW_OP_LLVM_arg, 0});
       if (auto FragmentInfoOpt = Expr.getFragmentInfo())
         Expression = *DIExpression::createFragmentExpression(
             Expression, FragmentInfoOpt->OffsetInBits,
             FragmentInfoOpt->SizeInBits);
       LocNos = std::make_unique<unsigned[]>(LocNoCount);
       LocNos[0] = UndefLocNo;
     }
   }

llvm/lib/CodeGen/MachineFunction.cpp

 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/CodeGen/WasmEHFuncInfo.h"
 #include "llvm/CodeGen/WinEHFuncInfo.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/ModuleSlotTracker.h"
for (auto &MI : MBB) {
 
       // Some vregs can be deleted as redundant in the meantime. Mark those
       // as DBG_VALUE $noreg. Additionally, some normal instructions are
       // quickly deleted, leaving dangling references to vregs with no def.
       if (Reg == 0 || !RegInfo->hasOneDef(Reg)) {
         MakeUndefDbgValue(MI);
         continue;
       }
+      // Only convert Expr to variadic form when we're sure we're emitting a
+      // complete instruction reference.
+      MI.getDebugExpressionOp().setMetadata(
+          DIExpression::convertToVariadicExpression(MI.getDebugExpression()));
 
       assert(Reg.isVirtual());
       MachineInstr &DefMI = *RegInfo->def_instr_begin(Reg);
 
       // If we've found a copy-like instruction, follow it back to the
       // instruction that defines the source value, see salvageCopySSA docs
       // for why this is important.
       if (DefMI.isCopyLike() || TII->isCopyInstr(DefMI)) {

llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp

 }
 
 MachineInstr *
 InstrEmitter::EmitDbgInstrRef(SDDbgValue *SD,
                               DenseMap<SDValue, Register> &VRBaseMap) {
   assert(!SD->isVariadic());
   SDDbgOperand DbgOperand = SD->getLocationOps()[0];
   MDNode *Var = SD->getVariable();
-  DIExpression *Expr = (DIExpression*)SD->getExpression();
+  const DIExpression *Expr = (DIExpression *)SD->getExpression();
   DebugLoc DL = SD->getDebugLoc();
   const MCInstrDesc &RefII = TII->get(TargetOpcode::DBG_INSTR_REF);
 
   // Handle variable locations that don't actually depend on the instructions
   // in the program: constants and stack locations.
   if (DbgOperand.getKind() == SDDbgOperand::FRAMEIX ||
       DbgOperand.getKind() == SDDbgOperand::CONST)
     return EmitDbgValueFromSingleOp(SD, VRBaseMap);
InstrEmitter::EmitDbgInstrRef(SDDbgValue *SD,
   unsigned OperandIdx = 0;
   for (const auto &MO : DefMI->operands()) {
     if (MO.isReg() && MO.isDef() && MO.getReg() == VReg)
       break;
     ++OperandIdx;
   }
   assert(OperandIdx < DefMI->getNumOperands());
 
+  // Only convert Expr to variadic form when we're sure we're emitting a
+  // complete instruction reference.
+  if (!SD->isVariadic())
+    Expr = DIExpression::convertToVariadicExpression(Expr);
   // Make the DBG_INSTR_REF refer to that instruction, and that operand.
   unsigned InstrNum = DefMI->getDebugInstrNum();
   SmallVector<MachineOperand, 1> MOs(
       {MachineOperand::CreateDbgInstrRef(InstrNum, OperandIdx)});
   return BuildMI(*MF, DL, RefII, false, MOs, Var, Expr);
 }
 
 MachineInstr *InstrEmitter::EmitDbgNoLocation(SDDbgValue *SD) {

llvm/lib/IR/DebugInfoMetadata.cpp

case dwarf::DW_OP_swap: {
       // DW_LLVM_OP_implicit_location as a placeholder for the location this
       // DIExpression is attached to, or else pass the number of implicit stack
       // elements into isValid.
       if (getNumElements() == 1)
         return false;
       break;
     }
     case dwarf::DW_OP_LLVM_entry_value: {
-      // An entry value operator must appear at the beginning and the number of
-      // operations it cover can currently only be 1, because we support only
-      // entry values of a simple register location. One reason for this is that
-      // we currently can't calculate the size of the resulting DWARF block for
-      // other expressions.
-      return I->get() == expr_op_begin()->get() && I->getArg(0) == 1;
+      // An entry value operator must appear at the beginning or immediately
+      // following `DW_OP_LLVM_arg 0`, and the number of operations it cover can
+      // currently only be 1, because we support only entry values of a simple
+      // register location. One reason for this is that we currently can't
+      // calculate the size of the resulting DWARF block for other expressions.
+      auto FirstOp = expr_op_begin();
+      if (FirstOp->getOp() == dwarf::DW_OP_LLVM_arg && FirstOp->getArg(0) == 0)
+        ++FirstOp;
+      return I->get() == FirstOp->get() && I->getArg(0) == 1;
     }
     case dwarf::DW_OP_LLVM_implicit_pointer:
     case dwarf::DW_OP_LLVM_convert:
     case dwarf::DW_OP_LLVM_arg:
     case dwarf::DW_OP_LLVM_tag_offset:
     case dwarf::DW_OP_constu:
     case dwarf::DW_OP_plus_uconst:
     case dwarf::DW_OP_plus:
if (getNumElements() == 0)
     return false;
 
   // If there are any elements other than fragment or tag_offset, then some
   // kind of complex computation occurs.
   for (const auto &It : expr_ops()) {
     switch (It.getOp()) {
     case dwarf::DW_OP_LLVM_tag_offset:
     case dwarf::DW_OP_LLVM_fragment:
+    case dwarf::DW_OP_LLVM_arg:
       continue;
     default:
       return true;
     }
   }
 
   return false;
 }
 
+bool DIExpression::isSingleLocationExpression() const {
+  if (!isValid())
+    return false;
+
+  if (getNumElements() == 0)
+    return true;
+
+  auto ExprOpBegin = expr_ops().begin();
+  auto ExprOpEnd = expr_ops().end();
+  if (ExprOpBegin->getOp() == dwarf::DW_OP_LLVM_arg)
+    ++ExprOpBegin;
+
+  return !std::any_of(ExprOpBegin, ExprOpEnd, [](auto Op) {
+    return Op.getOp() == dwarf::DW_OP_LLVM_arg;
+  });
+}
+
+const DIExpression *
+DIExpression::convertToVariadicExpression(const DIExpression *Expr) {
+  if (any_of(Expr->expr_ops(), [](auto ExprOp) {
+        return ExprOp.getOp() == dwarf::DW_OP_LLVM_arg;
+      }))
+    return Expr;
+  SmallVector<uint64_t> NewOps;
+  NewOps.reserve(Expr->getNumElements() + 2);
+  NewOps.append({dwarf::DW_OP_LLVM_arg, 0});
+  NewOps.append(Expr->elements_begin(), Expr->elements_end());
+  return DIExpression::get(Expr->getContext(), NewOps);
+}
+
 void DIExpression::canonicalizeExpressionOps(SmallVectorImpl<uint64_t> &Ops,
                                              const DIExpression *Expr,
                                              bool IsIndirect) {
   // If Expr is not already variadic, insert the implied `DW_OP_LLVM_arg 0`
   // to the existing expression ops.
   if (none_of(Expr->expr_ops(), [](auto ExprOp) {
         return ExprOp.getOp() == dwarf::DW_OP_LLVM_arg;
       }))
if (!any_of(Expr->expr_ops(),
     assert(ArgNo == 0 &&
            "Location Index must be 0 for a non-variadic expression.");
     SmallVector<uint64_t, 8> NewOps(Ops.begin(), Ops.end());
     return DIExpression::prependOpcodes(Expr, NewOps, StackValue);
   }
 
   SmallVector<uint64_t, 8> NewOps;
   for (auto Op : Expr->expr_ops()) {
+    // A DW_OP_stack_value comes at the end, but before a DW_OP_LLVM_fragment.
+    if (StackValue) {
+      if (Op.getOp() == dwarf::DW_OP_stack_value)
+        StackValue = false;
+      else if (Op.getOp() == dwarf::DW_OP_LLVM_fragment) {
+        NewOps.push_back(dwarf::DW_OP_stack_value);
+        StackValue = false;
+      }
+    }
     Op.appendToVector(NewOps);
     if (Op.getOp() == dwarf::DW_OP_LLVM_arg && Op.getArg(0) == ArgNo)
       NewOps.insert(NewOps.end(), Ops.begin(), Ops.end());
   }
+  if (StackValue)
+    NewOps.push_back(dwarf::DW_OP_stack_value);
 
   return DIExpression::get(Expr->getContext(), NewOps);
 }
 
 DIExpression *DIExpression::replaceArg(const DIExpression *Expr,
                                        uint64_t OldArg, uint64_t NewArg) {
   assert(Expr && "Can't replace args in this expression");
 

llvm/lib/Transforms/Utils/Local.cpp

if (AdditionalValues.empty() && IsValidSalvageExpr) {
       DII->setExpression(SalvagedExpr);
     } else if (isa<DbgValueInst>(DII) && !isa<DbgAssignIntrinsic>(DII) &&
                IsValidSalvageExpr &&
                DII->getNumVariableLocationOps() + AdditionalValues.size() <=
                    MaxDebugArgs) {
       DII->addVariableLocationOps(AdditionalValues, SalvagedExpr);
     } else {
       // Do not salvage using DIArgList for dbg.addr/dbg.declare, as it is
-      // currently only valid for stack value expressions. Do not salvage
-      // using DIArgList for dbg.assign yet. FIXME: support this.
+      // not currently supported in those instructions. Do not salvage using
+      // DIArgList for dbg.assign yet. FIXME: support this.
       // Also do not salvage if the resulting DIArgList would contain an
       // unreasonably large number of values.
       DII->setKillLocation();
     }
     LLVM_DEBUG(dbgs() << "SALVAGE: " << *DII << '\n');
     Salvaged = true;
   }
 

llvm/test/CodeGen/X86/dbg-value-superreg-copy2.mir

 tracksRegLiveness: true
 debugValueSubstitutions:
   - { srcinst: 2, srcop: 0, dstinst: 1, dstop: 0, subreg: 2 }
 body:             |
   bb.0:
     %0:gr16_abcd = MOV16ri 1, debug-instr-number 1, debug-location !9
 
   bb.1:
-    DBG_INSTR_REF !7, !DIExpression(), dbg-instr-ref(2, 0), debug-location !9
+    DBG_INSTR_REF !7, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !9
     %1:gr16 = COPY %0, debug-location !9
     %2:gr16 = COPY %0
 
   bb.2:
     $ax = COPY %1, debug-location !9
     $dx = COPY %2
     RET64 killed $ax, killed $dx, debug-location !9
 ...

llvm/test/DebugInfo/COFF/pieces.ll

 ; ASM:         retq
 
 ; ASM-LABEL: bitpiece_spill: # @bitpiece_spill
 ; ASM:         #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_LLVM_fragment 0 32] 0
 ; ASM:         xorl    %ecx, %ecx
 ; ASM:         callq   g
 ; ASM:         movl    %eax, [[offset_o_x:[0-9]+]](%rsp)          # 4-byte Spill
 ; ASM: [[spill_o_x_start:\.Ltmp[0-9]+]]:
-; ASM:         #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_plus_uconst [[offset_o_x]], DW_OP_LLVM_fragment 32 32] [$rsp+0]
+; ASM:         #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_plus_uconst [[offset_o_x]], DW_OP_deref, DW_OP_LLVM_fragment 32 32] $rsp
 ; ASM:         #APP
 ; ASM:         #NO_APP
 ; ASM:         movl    [[offset_o_x]](%rsp), %eax          # 4-byte Reload
 ; ASM:         retq
 ; ASM: [[spill_o_x_end_func:\.Ltmp[0-9]+]]:
 ; ASM-NEXT: .Lfunc_end4:
 
 

llvm/test/DebugInfo/MIR/InstrRef/accept-nonlive-reg-phis.mir

 tracksDebugUserValues: true
 frameInfo:
   maxAlignment:    4
 machineFunctionInfo: {}
 body:             |
   bb.0.entry:
   
     DBG_PHI $fp0, 3
-    DBG_INSTR_REF !17, !DIExpression(), dbg-instr-ref(3, 0), debug-location !30
+    DBG_INSTR_REF !17, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(3, 0), debug-location !30
     $eax = MOV32ri 0
     RET 0, debug-location !36
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/dbg-phi-subregister-location.mir

 # RUN: llc %s -run-pass=livedebugvalues -experimental-debug-variable-locations\
 # RUN:   -o - | FileCheck %s
 #
 # In the MIR below, there's an argument in the lowest byte of $edi. The debug
 # intrinsics correctly identify the value and where it becomes the variables
 # value, however a bug in InstrRefBasedLDV meant that not all subregisters of
 # DBG_PHI operands are tracked. That leads to the wrong DBG_VALUE location
 # being produced, and a crash under asan.
 #
 # CHECK-LABEL: name: foo
 # CHECK:       DBG_PHI $edi
 # CHECK-NEXT:  DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-# CHECK-NEXT:  DBG_VALUE $dil
+# CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $dil
 --- |
   ; ModuleID = 'out.ll'
   source_filename = "out.ll"
   target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
   target triple = "x86_64-scei-ps4"
 
   @someglobal = external local_unnamed_addr global i8, align 1
 

 debugValueSubstitutions:
   - { srcinst: 2, srcop: 0, dstinst: 1, dstop: 0, subreg: 1 }
 machineFunctionInfo: {}
 body:             |
   bb.0.entry:
     liveins: $edi
 
     DBG_PHI $edi, 1
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(2, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !13
     renamable $rax = MOV64rm $rip, 1, $noreg, target-flags(x86-gotpcrel) @someglobal, $noreg, debug-location !13 :: (load (s64) from got)
     MOV8mr killed renamable $rax, 1, $noreg, 0, $noreg, renamable $dil, debug-location !13 :: (store (s8) into @someglobal)
     RET64 debug-location !13
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/dbg-phis-in-ldv.mir

bb.1.if.then:
     renamable $rbx = ADD64ri32 killed renamable $rbx, 1, implicit-def $eflags, debug-location !21
   
   bb.2.if.end:
     liveins: $rbx, $r14
   
     DBG_PHI $rbx, 1
     $rax = COPY $rbx
     $rbx = MOV64ri 0
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(1, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !13
 
     ; This sequence should mark the contents of rbx on block entry as being the
     ; value for the variable at this DBG_INSTR_REF. We've force it to be in
     ; $rax now, so we should see a DBG_VALUE for rax:
     ; CHECK:      DBG_PHI $rbx, 1
     ; CHECK-NEXT: $rax = COPY $rbx
     ; CHECK-NEXT: $rbx = MOV64ri 0
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-    ; CHECK-NEXT: DBG_VALUE $rax, $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}} $rax
 
     $rbx = COPY $rax
     renamable $rbx = ADD64rr killed renamable $rbx, killed renamable $r14, implicit-def $eflags, debug-location !23
     DBG_VALUE $rbx, $noreg, !12, !DIExpression(), debug-location !13
     $rdi = MOV64rr $rbx, debug-location !24
     CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, debug-location !24
     $eax = MOV32rr $ebx, implicit killed $rbx, debug-location !26
     $rsp = frame-destroy ADD64ri8 $rsp, 8, implicit-def dead $eflags, debug-location !26
     CFI_INSTRUCTION def_cfa_offset 24, debug-location !26
     $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !26
     CFI_INSTRUCTION def_cfa_offset 16, debug-location !26
     $r14 = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !26
     CFI_INSTRUCTION def_cfa_offset 8, debug-location !26
     RET64 implicit $eax, debug-location !26
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/dbg-phis-in-ldv2.mir

bb.0:
     ;; A DBG_PHI of the stack should resolve to the stack location.
     DBG_PHI %stack.0, 1, 64
 
     ;; Reload value, clobber stack location.
     $rcx = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rax :: (store 8 into %stack.0)
 
     ;; This should resolve to the loaded register.
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(1, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !13
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-    ; CHECK-NEXT: DBG_VALUE $rcx
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}} $rcx
 
     ;; And if we say it's a smaller size, we should be able to pick out smaller
     ;; subregisters within the stack slot.
     DBG_PHI %stack.0, 2, 32
     $rax = MOV64ri 0
     $rcx = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rax :: (store 8 into %stack.0)
 
     ;; This should pick out the 32 bit value.
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(2, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !13
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-    ; CHECK-NEXT: DBG_VALUE $ecx
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}} $ecx
 
     ;; Try all the other subregs.
     DBG_PHI %stack.0, 3, 16
     $rax = MOV64ri 0
     $rcx = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rax :: (store 8 into %stack.0)
 
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(3, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(3, 0), debug-location !13
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(3, 0)
-    ; CHECK-NEXT: DBG_VALUE $cx
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}} $cx
 
     DBG_PHI %stack.0, 4, 8
     $rax = MOV64ri 0
     $rcx = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rax :: (store 8 into %stack.0)
 
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(4, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(4, 0), debug-location !13
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(4, 0)
-    ; CHECK-NEXT: DBG_VALUE $cl
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}} $cl
 
     ;; We can't, at this time, describe subregister fields with nonzero offset.
     ;; It's easily achieved by attaching more data to stack DBG_PHIs, but it's
     ;; not clear that LLVM will ever merge registers to generate such locations.
 
     RET64 implicit $eax, debug-location !26
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/dbg-phis-merging-in-ldv.mir

bb.1.if.then:
     renamable $rbx = ADD64ri32 killed renamable $rbx, 1, implicit-def $eflags, debug-location !22
     DBG_PHI $r14, 1
     DBG_PHI $rbx, 2
     DBG_PHI $rax, 3
 
   bb.3.if.end:
     liveins: $rbx, $r14
   
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(1, 0), debug-location !13
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(2, 0), debug-location !13
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(3, 0), debug-location !13
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(3, 0), debug-location !13
 
     ; Value number 1 is live-through the above control flow from the two
     ; DBG_PHIs:
     ; CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-    ; CHECK-NEXT:  DBG_VALUE $r14
+    ; CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $r14
     ;
     ; While value number 2 has different defs that merge on entry to bb.3.
     ; These are both in $rbx though, and we should find its location:
     ; CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-    ; CHECK-NEXT:  DBG_VALUE $rbx
+    ; CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $rbx
     ;
     ; Value number 3 cannot be resolved because $rax is clobbered in bb.2,
     ; meaning the merged value in bb.3 is incorrect. It should produce a
     ; DBG_VALUE $noreg.
     ; CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(3, 0)
-    ; CHECK-NEXT:  DBG_VALUE $noreg
+    ; CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $noreg
 
     renamable $rbx = ADD64rr killed renamable $rbx, killed renamable $r14, implicit-def $eflags, debug-location !28
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(2, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !13
 
     ; After clobbering rbx, the variable location should not be available.
     ; CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-    ; CHECK-NEXT:  DBG_VALUE $noreg
+    ; CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $noreg
 
     $rdi = MOV64rr $rbx, debug-location !29
     CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, debug-location !29
     $eax = MOV32rr $ebx, implicit killed $rbx, debug-location !31
     $rsp = frame-destroy ADD64ri8 $rsp, 8, implicit-def dead $eflags, debug-location !31
     CFI_INSTRUCTION def_cfa_offset 24, debug-location !31
     $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !31
     CFI_INSTRUCTION def_cfa_offset 16, debug-location !31
     $r14 = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !31
     CFI_INSTRUCTION def_cfa_offset 8, debug-location !31
     RET64 implicit $eax, debug-location !31
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/dbg-phis-with-loops.mir

body:             |
   bb.3:
     $r15 = MOV64ri 0
     CMP64ri8 $r15, 0, implicit-def $eflags, debug-location !19
     JCC_1 %bb.3, 5, implicit $eflags, debug-location !21
 
   bb.4:
     liveins: $rbx, $r14
   
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(1, 0), debug-location !13
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(2, 0), debug-location !13
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(3, 0), debug-location !13
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(3, 0), debug-location !13
 
     ; Value number 1 is live-through the above control flow from the two
     ; DBG_PHIs:
     ; CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-    ; CHECK-NEXT:  DBG_VALUE $r14
+    ; CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $r14
     ;
     ; While value number 2 has different defs that merge on entry to bb.3.
     ; These are both in $rbx though, and we should find its location:
     ; CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-    ; CHECK-NEXT:  DBG_VALUE $rbx
+    ; CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $rbx
     ;
     ; Value number 3 cannot be resolved because $rax is clobbered in bb.2,
     ; meaning the merged value in bb.3 is incorrect. It should produce a
     ; DBG_VALUE $noreg.
     ; CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(3, 0)
-    ; CHECK-NEXT:  DBG_VALUE $noreg
+    ; CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $noreg
 
     renamable $rbx = ADD64rr killed renamable $rbx, killed renamable $r14, implicit-def $eflags, debug-location !28
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(2, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !13
 
     ; After clobbering rbx, the variable location should not be available.
     ; CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-    ; CHECK-NEXT:  DBG_VALUE $noreg
+    ; CHECK-NEXT:  DBG_VALUE_LIST {{.+}} $noreg
 
     $rdi = MOV64rr $rbx, debug-location !29
     CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, debug-location !29
     $eax = MOV32rr $ebx, implicit killed $rbx, debug-location !31
     $rsp = frame-destroy ADD64ri8 $rsp, 8, implicit-def dead $eflags, debug-location !31
     CFI_INSTRUCTION def_cfa_offset 24, debug-location !31
     $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !31
     CFI_INSTRUCTION def_cfa_offset 16, debug-location !31
     $r14 = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !31
     CFI_INSTRUCTION def_cfa_offset 8, debug-location !31
     RET64 implicit $eax, debug-location !31
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/deref-spills-with-size.mir

bb.0.entry:
     liveins: $rdi, $rdx, $rsi, $rbp, $r15, $r14, $r13, $r12, $rbx
   
     ; CHECK-LABEL: bb.0.entry:
 
     ;; PART ONE: For this first block of tests, check that information about
     ;; the size of the value on the stack makes it through to the expression.
 
     $al = MOV8ri 0, debug-instr-number 1, debug-location !7
-    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_convert, 8, DW_ATE_signed, DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value), dbg-instr-ref(1, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $al, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_convert, 8, DW_ATE_signed,
-    ; CHECK-SAME     : DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value)
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_convert, 8, DW_ATE_signed, DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value), dbg-instr-ref(1, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_convert, 8, DW_ATE_signed,
+    ; CHECK-SAME     : DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value), $al
 
     MOV8mr $rsp, 1, $noreg, -8, $noreg, renamable $al :: (store 1 into %stack.0)
     ;; Clobber to force variable location onto stack. We should use a
     ;; deref_size 1 because the value is smaller than the variable.
     $al = MOV8ri 0, debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, 
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, 
     ; CHECK-SAME:     DW_OP_deref_size, 1, DW_OP_LLVM_convert, 8, DW_ATE_signed,
-    ; CHECK-SAME:     DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value),
+    ; CHECK-SAME:     DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value), $rsp
 
     ; Terminate the current variable location,
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg, ![[VARNUM]], !DIExpression()
 
     ;; Try again, but with the value originating on the stack, to ensure that
     ;; we can find its size. It should be deref_size 1 again.
     INC8m $rsp, 1, $noreg, 4, $noreg, implicit-def dead $eflags, debug-instr-number 2, debug-location !7 :: (store (s8) into %stack.0)
-    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_convert, 8, DW_ATE_signed, DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value), dbg-instr-ref(2, 1000000), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus,
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_convert, 8, DW_ATE_signed, DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value), dbg-instr-ref(2, 1000000), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus,
     ; CHECK-SAME:     DW_OP_deref_size, 1, DW_OP_LLVM_convert, 8, DW_ATE_signed,
-    ; CHECK-SAME:     DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value),
+    ; CHECK-SAME:     DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value), $rsp
 
     $eax = MOV32ri 0, debug-location !7
 
     ;; How about DBG_PHIs? The size of the value is communicated by the register
     ;; size, or an extra DBG_PHI operand, and that should feed through into the
     ;; decision of whether to deref_size or not.
 
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg
 
     $al = MOV8ri 0, debug-location !7
     DBG_PHI $al, 7
 
     MOV32mr $rsp, 1, $noreg, -8, $noreg, renamable $eax :: (store 4 into %stack.0)
     $eax = MOV32ri 0, debug-location !7
-    DBG_INSTR_REF !8, !DIExpression(), dbg-instr-ref(7, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_stack_value)
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(7, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_stack_value), $rsp
 
     $eax = MOV32ri 0, debug-location !7
 
     ;; And for when the DBG_PHI specifies a stack size...
     DBG_PHI %stack.0, 8, 16
-    DBG_INSTR_REF !8, !DIExpression(), dbg-instr-ref(8, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 2, DW_OP_stack_value)
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(8, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 2, DW_OP_stack_value), $rsp
 
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
     DBG_VALUE $noreg, $noreg, !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; PART TWO: test the twelve kinds of location expression mentioned in the
     ;; opening comment of this test, in that order. Please update the opening
     ;; comment, these lines and the DWARF check lines at the same time.
     ;; In each test we'll state a location, give it an instruction to cover,
     ;; and then terminate it.
 
     ;; Scalar (32), Large value (64), no stack value,
     $rax = MOV64ri 0, debug-instr-number 10, debug-location !7
     MOV64mr $rsp, 1, $noreg, -8, $noreg, renamable $rax :: (store 8 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !8, !DIExpression(), dbg-instr-ref(10, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 8, DW_OP_stack_value),
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(10, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 8, DW_OP_stack_value), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Scalar (32), Same value size (32), no stack value,
     $eax = MOV32ri 0, debug-instr-number 11, debug-location !7
     MOV32mr $rsp, 1, $noreg, -8, $noreg, renamable $eax :: (store 4 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !8, !DIExpression(), dbg-instr-ref(11, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, 0, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus),
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(11, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Scalar (32), Smaller value (8), no stack value,
     $al = MOV8ri 0, debug-instr-number 12, debug-location !7
     MOV8mr $rsp, 1, $noreg, -8, $noreg, renamable $al :: (store 1 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !8, !DIExpression(), dbg-instr-ref(12, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_stack_value),
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(12, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_stack_value), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Fragment (32), Larger value (64), no stack value,
     $rax = MOV64ri 0, debug-instr-number 13, debug-location !7
     MOV64mr $rsp, 1, $noreg, -8, $noreg, renamable $rax :: (store 8 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(13, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM2]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 8, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32),
+    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(13, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM2]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 8, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Fragment (32), Same value size (32), no stack value,
     $eax = MOV32ri 0, debug-instr-number 14, debug-location !7
     MOV32mr $rsp, 1, $noreg, -8, $noreg, renamable $eax :: (store 4 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(14, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, 0, ![[VARNUM2]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_LLVM_fragment, 0, 32),
+    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(14, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM2]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref, DW_OP_LLVM_fragment, 0, 32), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Fragment (32), Smaller value (8), no stack value,
     $al = MOV8ri 0, debug-instr-number 15, debug-location !7
     MOV8mr $rsp, 1, $noreg, -8, $noreg, renamable $al :: (store 1 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(15, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM2]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32),
+    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(15, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM2]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
 
 
     ;; Scalar (32), Large value (64), with stack value,
     $rax = MOV64ri 0, debug-instr-number 16, debug-location !7
     MOV64mr $rsp, 1, $noreg, -8, $noreg, renamable $rax :: (store 8 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !8, !DIExpression(DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), dbg-instr-ref(16, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 8, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value),
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), dbg-instr-ref(16, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 8, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Scalar (32), Same value size (32), no stack value,
     $eax = MOV32ri 0, debug-instr-number 17, debug-location !7
     MOV32mr $rsp, 1, $noreg, -8, $noreg, renamable $eax :: (store 4 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !8, !DIExpression(DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), dbg-instr-ref(17, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value),
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), dbg-instr-ref(17, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Scalar (32), Smaller value (8), no stack value,
     $al = MOV8ri 0, debug-instr-number 18, debug-location !7
     MOV8mr $rsp, 1, $noreg, -8, $noreg, renamable $al :: (store 1 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !8, !DIExpression(DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), dbg-instr-ref(18, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value),
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), dbg-instr-ref(18, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !8, !DIExpression(), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Fragment (32), Larger value (64), no stack value,
     $rax = MOV64ri 0, debug-instr-number 19, debug-location !7
     MOV64mr $rsp, 1, $noreg, -8, $noreg, renamable $rax :: (store 8 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !10, !DIExpression(DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(19, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM2]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 8, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32),
+    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(19, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM2]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 8, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Fragment (32), Same value size (32), no stack value,
     $eax = MOV32ri 0, debug-instr-number 20, debug-location !7
     MOV32mr $rsp, 1, $noreg, -8, $noreg, renamable $eax :: (store 4 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !10, !DIExpression(DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(20, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM2]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 4, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32),
+    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(20, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM2]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 4, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     ;; Fragment (32), Smaller value (8), no stack value,
     $al = MOV8ri 0, debug-instr-number 21, debug-location !7
     MOV8mr $rsp, 1, $noreg, -8, $noreg, renamable $al :: (store 1 into %stack.0)
     $rax = MOV64ri 0, debug-location !7
-    DBG_INSTR_REF !10, !DIExpression(DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(21, 0), debug-location !7
-    ; CHECK:      DBG_VALUE $rsp, $noreg, ![[VARNUM2]],
-    ; CHECK-SAME: !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32),
+    DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(21, 0), debug-location !7
+    ; CHECK:      DBG_VALUE_LIST ![[VARNUM2]],
+    ; CHECK-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref_size, 1, DW_OP_constu, 1, DW_OP_plus, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32), $rsp
     $eax = MOV32ri 0, debug-location !7
     DBG_VALUE $noreg, $noreg, !10, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !7
     ; CHECK: DBG_VALUE $noreg, $noreg
 
     RET64 0, debug-location !7
 ...

llvm/test/DebugInfo/MIR/InstrRef/follow-spill-of-live-value.mir

 # 8 and used for a comparison and a DBG_INSTR_REF. A valid variable location
 # should be emitted -- it's not too important what the location is, this test
 # is that LiveDebugValues can track the value, not where it puts it.
 #
 ## Capture variable num,
 # CHECK: ![[VARNUM:[0-9]+]] = !DILocalVariable
 #
 # CHECK-LABEL: bb.8:
-# CHECK:       DBG_VALUE $rsp, 0, ![[VARNUM]], !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_LLVM_fragment, 64, 64),
+# CHECK:       DBG_VALUE_LIST ![[VARNUM]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref, DW_OP_LLVM_fragment, 64, 64), $rsp,
 # CHECK-LABEL:  bb.9:
-# CHECK:       DBG_VALUE $rsp, 0, ![[VARNUM]], !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_LLVM_fragment, 64, 64),
+# CHECK:       DBG_VALUE_LIST ![[VARNUM]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref, DW_OP_LLVM_fragment, 64, 64), $rsp,
 
 --- |
   ; ModuleID = 'missingvar.ll'
   source_filename = "/fast/fs/llvm34/lib/Analysis/LoopPass.cpp"
   target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
   target triple = "x86_64-unknown-linux-gnu"
   
   %"class.std::deque" = type { %"class.std::_Deque_base" }
bb.8:
     liveins: $rax, $rdi, $rdx, $rsi, $r8, $r9, $r10, $r11, $r14
   
     MOV64mr renamable $rdi, 1, $noreg, 16, $noreg, killed renamable $rax, debug-location !7 :: (store 8 into %ir.22)
     renamable $rax = MOV64rm $rsp, 1, $noreg, -8, $noreg :: (load 8 from %stack.0)
     MOV64mr undef renamable $rax, 1, $noreg, 0, $noreg, killed renamable $rax, debug-location !7 :: (store 8 into `%"class.llvm::Loop"*** undef`)
     MOV64mr undef renamable $rax, 1, $noreg, 0, $noreg, killed renamable $r10, debug-location !7 :: (store 8 into `%"class.llvm::Loop"*** undef`)
     MOV64mr killed renamable $rdi, 1, $noreg, 40, $noreg, killed renamable $r9, debug-location !7 :: (store 8 into %ir.24)
     renamable $rax = MOV64rm killed renamable $rsi, 1, $noreg, 24, $noreg, debug-location !7 :: (load 8 from %ir.26)
-    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(1, 0), debug-location !7
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(1, 0), debug-location !7
     renamable $rax = SUB64rr killed renamable $rax, killed renamable $r11, implicit-def dead $eflags, debug-location !7
     renamable $r8 = SUB64rr killed renamable $r8, killed renamable $r14, implicit-def dead $eflags, debug-location !7
     renamable $r8 = exact SAR64ri killed renamable $r8, 3, implicit-def dead $eflags, debug-location !7
     renamable $rax = LEA64r killed renamable $r8, 8, killed renamable $rax, -64, $noreg, debug-location !7
     TEST64rr killed renamable $rax, renamable $rax, implicit-def $eflags, debug-location !7
     JCC_1 %bb.10, 15, implicit $eflags, debug-location !7
   
   bb.9:

llvm/test/DebugInfo/MIR/InstrRef/livedebugvalues_illegal_locs.mir

 debugValueSubstitutions:
   - { srcinst: 4, srcop: 0, dstinst: 3, dstop: 0, subreg: 0 }
 body:  |
   bb.0.entry:
     successors: %bb.1, %bb.2
     ; CHECK-LABE: bb.0.entry:
 
     $rax = MOV64ri 1, debug-instr-number 1, debug-location !17
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(1, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !17
     ;; First check that picking out location works as usual.
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-    ; CHECK-NEXT: DBG_VALUE $rax
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $rax
 
     $rax = MOV64ri 1, debug-instr-number 2, debug-location !17
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(2, 999), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 999), debug-location !17
     ;; Test out of bounds operand number.
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 999)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     $rax = MOV64ri 1, debug-instr-number 3, debug-location !17
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(3, 1), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(3, 1), debug-location !17
     ;; Test non-register operand
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(3, 1)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     ;; FIXME: We should test what happens when this meta-instruction is seen
     ;; by livedbugvalues with an instruction number. However, right now it's
     ;; impossible to turn the machine-code verifier off when loading MIR?
     ;KILL implicit killed $eflags, debug-instr-number 4, debug-location !17
-    ;DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(4, 0), debug-location !17
+    ;DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(4, 0), debug-location !17
     ;;; Test non-def operand
     ;; check:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(4, 0)
-    ;; check-next: DBG_VALUE $noreg
+    ;; check-next: DBG_VALUE_LIST {{.+}}, $noreg
 
     $noreg = MOV32ri 1, debug-instr-number 5, debug-location !17
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(5, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(5, 0), debug-location !17
     ;; Def of $noreg?
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(5, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     JCC_1 %bb.1, 1, implicit $eflags
     JMP_1 %bb.2
 
   bb.1:
     successors: %bb.3
     ; CHECK-LABEL: bb.1:
 
     DBG_PHI $rax, 6
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(6, 1), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(6, 1), debug-location !17
     ;; Test out-of-bounds reference to a DBG_PHI.
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(6, 1)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     DBG_PHI $noreg, 7
     JMP_1 %bb.3
 
   bb.2:
     successors: %bb.3
     ; CHECK-LABEL: bb.2:
     DBG_PHI 1, 6
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(6, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(6, 0), debug-location !17
     ;; Test non-reg operand to DBG_PHI. It's not clear if this can ever happen
     ;; as the result of an optimisation, but lets test for it anyway.
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(6, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     DBG_PHI 1, 7
     JMP_1 %bb.3
 
   bb.3:
     ; CHECK-LABEL: bb.3:
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(7, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(7, 0), debug-location !17
     ;; PHI resolution of illegal inputs shouldn't crash either. It should also
     ;; come out as a $noreg location.
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(7, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     RET 0, debug-location !17
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/livedebugvalues_instrref_tolocs.mir

 ---
 name: _Z8bb_to_bb
 debugValueSubstitutions:
   - { srcinst: 4, srcop: 0, dstinst: 3, dstop: 0, subreg: 0 }
 body:  |
   bb.0.entry:
     $rax = MOV64ri 1, debug-instr-number 1, debug-location !17
     ; This debug instruction should identify the value as being in $rax.
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(1, 0), debug-location !17
-    ; CHECK: DBG_VALUE $rax, $noreg
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !17
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rax
 
     $rbx = COPY killed $rax, debug-location !17
     $rax = MOV64ri 1, debug-location !17
-    ; CHECK: DBG_VALUE $rbx, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rbx
 
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(2, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !17
     ; No instruction is labelled with the number "2". This should produce an
     ; empty variable location.
-    ; CHECK: DBG_VALUE $noreg, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $noreg
 
     $rbx = MOV64ri 1, debug-instr-number 3, debug-location !17
     JMP_1 %bb.1
 
 
     ; CHECK-LABEL: bb.1:
   bb.1:
 
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(3, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(3, 0), debug-location !17
     ; This refers to a value def'd in a parent block -- but it should be
     ; tracked into this block.
-    ; CHECK: DBG_VALUE $rbx, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rbx
     JMP_1 %bb.2
 
     ; CHECK-LABEL: bb.2:
   bb.2:
     ; Just like any other variable location, live-ins should be created for
     ; any successor blocks.
-    ; CHECK: DBG_VALUE $rbx, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rbx
 
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(5, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(5, 0), debug-location !17
     ; This is a debug use-before-def: the value appears a few instructions
     ; later. Any earlier value should be terminated here, _and_ we should
     ; emit a DBG_VALUE when the value becomes available.
-    ; CHECK: DBG_VALUE $noreg, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $noreg
 
     $rax = MOV64ri 1, debug-location !17
     $rax = MOV64ri 1, debug-location !17
     $rcx = MOV64ri 1, debug-instr-number 5, debug-location !17
-    ; CHECK: DBG_VALUE $rcx, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rcx
     $rax = MOV64ri 1, debug-location !17
 
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(6, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(6, 0), debug-location !17
     ; Another debug use-before-def, but across block boundaries.
-    ; CHECK: DBG_VALUE $noreg, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $noreg
     JMP_1 %bb.3
 
     ; CHECK-LABEL: bb.3:
   bb.3:
     $rax = MOV64ri 1, debug-location !17
     $rdx = MOV64ri 1, debug-instr-number 6, debug-location !17
-    ; CHECK: DBG_VALUE $rdx, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rdx
 
     ; Terminate variable location for next few blocks,
     DBG_VALUE $noreg, $noreg, !16, !DIExpression(), debug-location !17
     ; CHECK: DBG_VALUE $noreg, $noreg
     JMP_1 %bb.4
 
   bb.4:
     ; The next three blocks form a debug use-before-def modelling a scenario
     ; where an instruction is sunk (debug inst in bb5, value in bb6). However,
     ; because a different path joins bb.6, we should _not_ add any DBG_VALUE.
     ; A different variable value may enter the block via the other path.
     $rdx = MOV64ri 1, implicit-def $eflags, debug-location !17
     JCC_1 %bb.6, 4, implicit $eflags, debug-location !17
   bb.5:
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(7, 0), debug-location !17
-    ; CHECK: DBG_VALUE $noreg, $noreg
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(7, 0), debug-location !17
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $noreg
     JMP_1 %bb.6, debug-location !17
   bb.6:
     $rsi = MOV64ri 1, debug-instr-number 7, debug-location !17
     JMP_1 %bb.7, debug-location !17
 
   ; A use-before-def shouldn't pass another definition of the variable location
   ; or value.
   bb.7:
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(8, 0), debug-location !17
-    ; CHECK: DBG_VALUE $noreg, $noreg
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(8, 0), debug-location !17
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $noreg
     DBG_VALUE $rax, $noreg, !16, !DIExpression(), debug-location !17
     ; CHECK: DBG_VALUE $rax, $noreg,
     $rdi = MOV64ri 1, debug-instr-number 8, debug-location !17
 
   ; Loops: use-before-defs should be live-through loops, assuming that nothing
   ; in that loop modifies the variable location.
   bb.8:
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(9, 0), debug-location !17
-    ; CHECK: DBG_VALUE $noreg, $noreg
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(9, 0), debug-location !17
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $noreg
     JCC_1 %bb.8, 4, implicit $eflags
   bb.9:
     $rax = MOV64ri 11, debug-instr-number 9, debug-location !17
-    ; CHECK: DBG_VALUE $rax, $noreg,
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rax
 
   ; Likewise, use-before-defs where anything changes the variable location
   ; or value in the loop, should be discarded.
   bb.10:
     ; live-in,
-    ; CHECK: DBG_VALUE $rax, $noreg,
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(10, 0), debug-location !17
-    ; CHECK: DBG_VALUE $noreg, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rax
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(10, 0), debug-location !17
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $noreg
 
   bb.11:
     $rbx = MOV64ri 1, debug-location !17
 
   bb.12:
-    DBG_INSTR_REF !16, !DIExpression(), dbg-instr-ref(9, 0), debug-location !17
+    DBG_INSTR_REF !16, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(9, 0), debug-location !17
     ; This still has a value in $rax,
-    ; CHECK: DBG_VALUE $rax, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rax
     JCC_1 %bb.11, 4, implicit $eflags
 
   bb.13:
     ; Live in,
-    ; CHECK: DBG_VALUE $rax, $noreg
+    ; CHECK: DBG_VALUE_LIST {{.+}}, $rax
     $rbx = MOV64ri 11, debug-instr-number 10, debug-location !17
     ; This is instruction 10 referred to in bb.10. However, as the variable
     ; location/value has been modified in the meantime, no DBG_VALUE should be
     ; generated here.
     RET64 $eax, debug-location !17
 ...

llvm/test/DebugInfo/MIR/InstrRef/livedebugvalues_stackslot_subregs.mir

liveins: $rdi, $rax, $rbx
     $rsi = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
 
     ; Store a random value onto stack, forces value to be in one place only.
     ; Clobber other registers that contain the value we're to track.
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rbx :: (store 8 into %stack.0)
     $rax = MOV64ri 0
     $rdi = MOV64ri 0
 
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; CHECK:      DBG_INSTR_REF
-    ; CHECK-NEXT: DBG_VALUE $esi
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $esi
     RET64 $rsi, debug-location !12
 ...

llvm/test/DebugInfo/MIR/InstrRef/livedebugvalues_subreg_substitutions.mir

stack:
   - { id: 0, name: '', type: spill-slot, offset: -16, size: 8, alignment: 8,
       stack-id: default, callee-saved-register: '', callee-saved-restored: true,
       debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
 body:  |
   bb.0:
   liveins: $rdi, $rax
     CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $edi, implicit-def $rax, debug-instr-number 4, debug-location !12
     ; CHECK:      CALL64pcrel32
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-    ; CHECK-NEXT: DBG_VALUE $al
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(5, 0), debug-location !12
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $al
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(5, 0), debug-location !12
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(5, 0)
-    ; CHECK-NEXT: DBG_VALUE $ah
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(8, 0), debug-location !12
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $ah
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(8, 0), debug-location !12
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(8, 0)
-    ; CHECK-NEXT: DBG_VALUE $ah
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(13, 0), debug-location !12
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $ah
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(13, 0), debug-location !12
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(13, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rax :: (store 8 into %stack.0)
     $rax = MOV64ri 0, debug-location !12
     ; CHECK:      $rax = MOV64ri 0
     ; The value is now located in a spill slot, as a subregister within the
     ; slot, which InstrRefBasedLDV should be able to find.
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-    ; CHECK-NEXT: DBG_VALUE $rsp, 0, !{{[0-9]*}}, !DIExpression(DW_OP_constu, 8, DW_OP_minus)
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(5, 0), debug-location !12
+    ; CHECK-NEXT: DBG_VALUE_LIST !{{[0-9]*}}, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 8, DW_OP_minus, DW_OP_deref), $rsp
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(5, 0), debug-location !12
     ; This and the next DBG_INSTR_REF refer to a value that is on the stack, but
     ; is located at a non-zero offset from the start of the slot -- $ah within
     ; $rax is 8 bits in. Today, InstrRefBasedLDV can't express this. It also
     ; doesn't seem likely to be profitable.
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(5, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(8, 0), debug-location !12
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(8, 0), debug-location !12
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(8, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(13, 0), debug-location !12
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(13, 0), debug-location !12
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(13, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
     $rax = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
     RET64 $rax, debug-location !12
 ...

llvm/test/DebugInfo/MIR/InstrRef/memory-operand-folding-tieddef.mir

bb.5:
     MOV64mr %33, 1, $noreg, 0, $noreg, %12, debug-location !13 :: (store (s64) into `i64* undef`)
     %11:gr32 = MOV32rm %34, 1, $noreg, 0, $noreg, debug-location !13 :: (load (s32) from `i32* undef`, align 8)
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !13
     $rdi = COPY %35, debug-location !13
     $rsi = COPY %36, debug-location !13
     CALL64r %37, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit $rsi, implicit-def $rsp, implicit-def $ssp, implicit-def $al, debug-location !13
     ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !13
     %13:gr32 = INC32r %6, implicit-def dead $eflags, debug-instr-number 1, debug-location !13
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(1, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !13
     JMP_1 %bb.1, debug-location !13
 ...

llvm/test/DebugInfo/MIR/InstrRef/memory-operand-load-folding.mir

bb.0.if.then:
     JCC_1 %bb.3, 5, implicit killed $eflags
     JMP_1 %bb.1
   
   bb.1.sw.bb:
     successors: %bb.2(0x30000000), %bb.3(0x50000000)
   
     %7:gr32 = nofpexcept CVTTSS2SIrr killed %1, implicit $mxcsr, debug-instr-number 1
     %8:gr8 = COPY killed %7.sub_8bit
-    DBG_INSTR_REF !6, !DIExpression(), dbg-instr-ref(2, 0), debug-location !17
+    DBG_INSTR_REF !6, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !17
     TEST8rr killed %8, %8, implicit-def $eflags
     JCC_1 %bb.3, 5, implicit killed $eflags
     JMP_1 %bb.2
   
   bb.2.if.end:
     successors: %bb.3(0x80000000)
   
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp

llvm/test/DebugInfo/MIR/InstrRef/memory-operand-tracking.mir

- { id: 0, name: '', type: spill-slot, offset: -16, size: 8, alignment: 8,
       debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
 body:  |
   bb.0:
   liveins: $rdi, $rax
     DBG_PHI $rax, 1
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rdi :: (store 8 into %stack.0)
     $rax = MOV64ri 0, debug-location !12
     INC32m $rsp, 1, $noreg, 4, $noreg, implicit-def dead $eflags, debug-instr-number 3, debug-location !DILocation(line: 0, scope: !7) :: (store (s32) into %stack.0)
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(2, 0), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !12
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-    ; CHECK-NEXT: DBG_VALUE $rsp
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $rsp
     ;; Test that the old value (from the DBG_PHI) is not tracked anywhere. It
     ;; should not be considered as being on the stack any more.
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
     INC32m $rsp, 1, $noreg, 4, $noreg, implicit-def dead $eflags, debug-location !12 :: (store (s32) into %stack.0)
     ;; The above INC32m should be detected as clobbering the stack location,
     ;; even though it isn't debug labelled.
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(2, 0), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !12
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     ;; Store another debug-labelled value to the stack,
     INC32m $rsp, 1, $noreg, 4, $noreg, implicit-def dead $eflags, debug-instr-number 5, debug-location !DILocation(line: 0, scope: !7) :: (store (s32) into %stack.0)
     ;; Point the variable at that value.
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(4, 0), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(4, 0), debug-location !12
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(4, 0),
-    ; CHECK-NEXT: DBG_VALUE $rsp
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $rsp
     ;; Overwrite the stack: LiveDebugValues should explicitly undef the stack
-    ;; location with DBG_VALUE $noreg, as DbgEntityHistoryCalculator doesn't
+    ;; location with DBG_VALUE_LIST $noreg, as DbgEntityHistoryCalculator doesn't
     ;; look at the stack.
     INC32m $rsp, 1, $noreg, 4, $noreg, implicit-def dead $eflags, debug-location !DILocation(line: 0, scope: !7) :: (store (s32) into %stack.0)
     ; CHECK:      INC32m $rsp
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     $rax = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
     RET64 $rax, debug-location !12
 ...

llvm/test/DebugInfo/MIR/InstrRef/out-of-scope-blocks.mir

 # RUN: llc %s -o - -run-pass=livedebugvalues -march=x86-64 \
 # RUN:     -experimental-debug-variable-locations=true \
 # RUN: | FileCheck %s
 #
 ## This test used to crash InstrRefBasedLDV, due to fragment information going
 ## missing; test for that, and also check what happens when we have assignments
 ## outside of lexical scope. In the IR below, "_First" is only in scope in the
 ## entry block, but is assigned in every block. Under current behaviour, that
 ## means that InstrRefBasedLDV will propagate its location through all blocks.
 #
 # CHECK:       ![[FIRSTVAR:[0-9]+]] = !DILocalVariable(name: "_First",
 #
 # CHECK-LABEL: bb.0.entry:
-# CHECK:       DBG_VALUE $rbx, $noreg, ![[FIRSTVAR]],
-# CHECK-SAME:        !DIExpression(DW_OP_LLVM_fragment, 64, 64)
+# CHECK:       DBG_VALUE_LIST ![[FIRSTVAR]],
+# CHECK-SAME:        !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), $rbx
 #
 # CHECK-LABEL: bb.1.if.then.i.i.i.i.i:
-# CHECK:       DBG_VALUE $rbx, $noreg, ![[FIRSTVAR]],
-# CHECK-SAME:        !DIExpression(DW_OP_LLVM_fragment, 64, 64)
+# CHECK:       DBG_VALUE_LIST ![[FIRSTVAR]],
+# CHECK-SAME:        !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), $rbx
 # CHECK:       DBG_INSTR_REF ![[FIRSTVAR]],
-# CHECK:       DBG_VALUE $rbx, $noreg, ![[FIRSTVAR]],
-# CHECK-SAME:        !DIExpression(DW_OP_LLVM_fragment, 64, 64)
+# CHECK:       DBG_VALUE_LIST ![[FIRSTVAR]],
+# CHECK-SAME:        !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), $rbx
 
 # CHECK-LABEL: bb.2._Z17do_insert_cv_testI5_TreeEvv.exit:
-# CHECK:       DBG_VALUE $rbx, $noreg, ![[FIRSTVAR]],
-# CHECK-SAME:        !DIExpression(DW_OP_LLVM_fragment, 64, 64)
+# CHECK:       DBG_VALUE_LIST ![[FIRSTVAR]],
+# CHECK-SAME:        !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), $rbx
 # CHECK:       DBG_INSTR_REF ![[FIRSTVAR]],
-# CHECK:       DBG_VALUE $rbx, $noreg, ![[FIRSTVAR]],
-# CHECK-SAME:        !DIExpression(DW_OP_LLVM_fragment, 64, 64)
+# CHECK:       DBG_VALUE_LIST ![[FIRSTVAR]],
+# CHECK-SAME:        !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), $rbx
 
 --- |
   source_filename = "reduced.ll"
   target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
   
   %class._Tree = type { i8 }
   %class._Tree_const_iterator = type { %class._Tree_unchecked_const_iterator }
   %class._Tree_unchecked_const_iterator = type { %struct._Iterator_base0, i32* }
bb.0.entry:
     CFI_INSTRUCTION offset $rbx, -24
     CFI_INSTRUCTION offset $r14, -16
     DBG_PHI $rsi, 2
     $rbx = MOV64rr $rsi
     DBG_VALUE 2, $noreg, !10, !DIExpression(), debug-location !12
     renamable $r14d = XOR32rr undef $r14d, undef $r14d, implicit-def dead $eflags, implicit-def $r14
     dead $edi = XOR32rr undef $edi, undef $edi, implicit-def dead $eflags, implicit-def $rdi
     CALL64r undef renamable $rax, csr_64, implicit $rsp, implicit $ssp, implicit killed $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def dead $eax, implicit-def dead $rdx
-    DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(2, 0), debug-location !15
+    DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(2, 0), debug-location !15
     dead $edi = XOR32rr undef $edi, undef $edi, implicit-def dead $eflags, implicit-def $rdi, debug-location !15
     CALL64r undef renamable $rax, csr_64, implicit $rsp, implicit $ssp, implicit killed $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def dead $al, debug-location !15
     TEST8rr renamable $r14b, renamable $r14b, implicit-def $eflags, implicit killed $r14
     JCC_1 %bb.2, 5, implicit $eflags
   
   bb.1.if.then.i.i.i.i.i:
     dead $edi = XOR32rr undef $edi, undef $edi, implicit-def dead $eflags, implicit-def $rdi
     CALL64r undef renamable $rax, csr_64, implicit $rsp, implicit $ssp, implicit killed $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $rax, debug-instr-number 3
     $rbx = MOV64rr killed $rax
-    DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(3, 7), debug-location !15
+    DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(3, 7), debug-location !15
   
   bb.2._Z17do_insert_cv_testI5_TreeEvv.exit:
     liveins: $rbx
   
     DBG_PHI $rbx, 1
-    DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(1, 0), debug-location !15
+    DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(1, 0), debug-location !15
     dead $edi = XOR32rr undef $edi, undef $edi, implicit-def dead $eflags, implicit-def $rdi, debug-location !16
     $esi = XOR32rr undef $esi, undef $esi, implicit-def dead $eflags, debug-location !16
     $rdx = MOV64rr killed $rbx, debug-location !16
     CALL64r undef renamable $rax, csr_64, implicit $rsp, implicit $ssp, implicit killed $rdi, implicit $esi, implicit killed $rdx, implicit-def $rsp, implicit-def $ssp, debug-location !16
     $eax = XOR32rr undef $eax, undef $eax, implicit-def dead $eflags
     $rsp = frame-destroy ADD64ri8 $rsp, 8, implicit-def dead $eflags
     CFI_INSTRUCTION def_cfa_offset 24
     $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp
     CFI_INSTRUCTION def_cfa_offset 16
     $r14 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
     CFI_INSTRUCTION def_cfa_offset 8
     RET64 killed $eax
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/phi-coalesce-subreg.mir

body:             |
   ; Verify those registers land in $bx
   ; CHECK:              renamable $ebp = ADD32ri8
 
   ; DOESCOALESCE-LABEL: bb.2.if.end:
   ; CHECK-LABEL:        bb.2.if.end:
   bb.2.if.end:
     %2:gr16 = PHI %11, %bb.0, %17, %bb.1, debug-instr-number 1, debug-location !13
   ; CHECK:              DBG_PHI $bp, 1
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(1, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !13
     %31:gr32 = MOVSX32rr16 %6, debug-location !13
     %30:gr32 = MOVSX32rr16 killed %2, debug-location !13
     %29:gr32 = ADD32rr killed %30, killed %31, implicit-def $eflags, debug-location !13
     %26:gr16 = COPY killed %29.sub_16bit, debug-location !13
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
     %24:gr32 = MOVSX32rr16 %26, debug-location !13
     $edi = COPY %24, debug-location !13
     CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $edi, debug-location !13
     ADJCALLSTACKUP64 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
     %23:gr32 = MOVSX32rr16 %26, debug-location !13
     $eax = COPY %23, debug-location !13
     RET64 implicit $eax, debug-location !13
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/phi-coalescing.mir

body:             |
   ; Verify that all these registers land in r14.
   ; CHECK:              renamable $r14 = ADD64ri32 killed renamable $r14
   
   ; DOESCOALESCE-LABEL: bb.2.if.end:
   ; CHECK-LABEL:        bb.2.if.end:
   bb.2.if.end:
     %2:gr64 = PHI %9, %bb.0, %10, %bb.1, debug-instr-number 1, debug-location !13
   ; CHECK:              DBG_PHI $r14, 1
-    DBG_INSTR_REF !12, !DIExpression(), dbg-instr-ref(1, 0), debug-location !13
+    DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !13
     %2:gr64 = ADD64rr killed %2, %6, implicit-def $eflags, debug-location !13
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
     $rdi = COPY %2, debug-location !13
     CALL64pcrel32 @ext, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, debug-location !13
     ADJCALLSTACKUP64 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !13
     %13:gr32 = COPY %2.sub_32bit, debug-location !13
     $eax = COPY %13, debug-location !13
     RET64 implicit $eax, debug-location !13
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/phi-on-stack-coalesced.mir

bb.2:
     %59:gr32 = PHI %19, %bb.0, %39, %bb.1, debug-location !18
     %60:gr32 = PHI %20, %bb.0, %40, %bb.1, debug-location !18
     %61:gr32 = PHI %21, %bb.0, %41, %bb.1, debug-location !18
     %62:gr32 = PHI %22, %bb.0, %42, %bb.1, debug-location !18
     %63:gr32 = PHI %23, %bb.0, %43, %bb.1, debug-location !18
     %64:gr32 = PHI %24, %bb.0, %44, %bb.1, debug-location !18
 
     INLINEASM &"", 1, 12, %50, 12, %51, 12, %52, 12, %53, 12, %54, 12, %55, 12, %56, 12, %57, 12, %58, 12, %59, 12, %60, 12, %61, 12, %62, 12, %63, 12, %64
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; CHECK:      DBG_PHI %stack.0, 1, 16
     ; CHECK:      DBG_INSTR_REF {{.+}} dbg-instr-ref(1, 0)
     ; CHECK:      renamable $eax = MOV32rm %stack.0,
     $eax = COPY killed %0, debug-location !19
     RET 0, killed $eax, debug-location !19
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/phi-on-stack-coalesced2.mir

bb.2:
     %59:gr32 = PHI %19, %bb.0, %39, %bb.1, debug-location !18
     %60:gr32 = PHI %20, %bb.0, %40, %bb.1, debug-location !18
     %61:gr32 = PHI %21, %bb.0, %41, %bb.1, debug-location !18
     %62:gr32 = PHI %22, %bb.0, %42, %bb.1, debug-location !18
     %63:gr32 = PHI %23, %bb.0, %43, %bb.1, debug-location !18
     %64:gr32 = PHI %24, %bb.0, %44, %bb.1, debug-location !18
 
     INLINEASM &"", 1, 12, %50, 12, %51, 12, %52, 12, %53, 12, %54, 12, %55, 12, %56, 12, %57, 12, %58, 12, %59, 12, %60, 12, %61, 12, %62, 12, %63, 12, %64
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; CHECK-NOT:  DBG_PHI
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
     ; CHECK-NOT:  DBG_PHI
     $eax = COPY killed %0, debug-location !19
     RET 0, killed $eax, debug-location !19
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/phi-regallocd-to-stack.mir

bb.2:
     %58:gr32 = PHI %18, %bb.0, %38, %bb.1, debug-location !18
     %59:gr32 = PHI %19, %bb.0, %39, %bb.1, debug-location !18
     %60:gr32 = PHI %20, %bb.0, %40, %bb.1, debug-location !18
     %61:gr32 = PHI %21, %bb.0, %41, %bb.1, debug-location !18
     %62:gr32 = PHI %22, %bb.0, %42, %bb.1, debug-location !18
     %63:gr32 = PHI %23, %bb.0, %43, %bb.1, debug-location !18
     %64:gr32 = PHI %24, %bb.0, %44, %bb.1, debug-location !18
 
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; CHECK:      DBG_PHI %stack.1, 1, 32
     ; CHECK:      renamable $eax = MOV32rm %stack.1,
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
     $eax = COPY killed %0, debug-location !19
     RET 0, killed $eax, debug-location !19
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/phi-through-regalloc.mir

bb.0.entry:
     JCC_1 %bb.2, 5, implicit killed $eflags, debug-location !17
     JMP_1 %bb.1, debug-location !17
 
   bb.1.if.else:
 
     ; CHECK-LABEL: bb.2.if.end:
   bb.2.if.end:
     %0:gr32 = PHI %1, %bb.0, %2, %bb.1, debug-instr-number 1, debug-location !18
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; CHECK:      DBG_PHI $ebp, 1
     ; CHECK:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
     $eax = COPY killed %0, debug-location !19
     ; Confirm that %0 is allocated in $ebp,
     ; CHECK:      $eax = COPY killed renamable $ebp
     RET 0, killed $eax, debug-location !19
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/pick-vphi-in-shifting-loop.mir

 # RUN: llc %s -o - -run-pass=livedebugvalues \
 # RUN:     -experimental-debug-variable-locations \
 # RUN: | FileCheck %s
 #
 # This test used to cause an infinite loop in InstrRefBasedLDV. Observe block
 # five: on the first entry the desired variable value is in $rdx and $rcx, on
 # both paths to the block. However, the block rotates values between those
 # registers, and feeds a zero-value in too. Ultimately, there is no correct
 # location for the variable in that block.
 # This caused an infinite loop in a previous implementation of LiveDebugValues.
 # Keep this around as a regression test, and check that no location is picked
 # in block 5.
 #
 # CHECK-LABEL: bb.3:
-# CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(7, 0)
-# CHECK-NEXT:  DBG_VALUE $rdx
+# CHECK:       DBG_INSTR_REF {{.+}}, dbg-instr-ref(7, 0)
+# CHECK-NEXT:  DBG_VALUE_LIST {{.+}}, $rdx
 # CHECK-NEXT:  $rcx = MOV64rr $rdx
 # CHECK-LABEL: bb.4:
-# CHECK:       DBG_VALUE $rcx
+# CHECK:       DBG_VALUE_LIST {{.+}}, $rcx
 # CHECK-NEXT:  $rdx = MOV64rr killed $rcx
 # CHECK-LABEL: bb.5:
 # CHECK-NOT:   DBG_VALUE
 --- |
   target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
   target triple = "x86_64-unknown-linux-gnu"
   
   ; Function Attrs: nofree norecurse nosync nounwind readonly uwtable
bb.0:
     $rdx = MOV64ri 0, implicit-def $eflags
     $esi = MOV32ri 0, implicit-def $eflags
   
   bb.1:
     successors: %bb.2(0x03e0f83e), %bb.1(0x7c1f07c2)
     liveins: $rcx, $rdi, $rdx, $eflags
   
     DBG_PHI $rcx, 2
-    DBG_INSTR_REF !18, !DIExpression(), dbg-instr-ref(2, 0), debug-location !22
+    DBG_INSTR_REF !18, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !22
     JCC_1 %bb.1, 4, implicit $eflags, debug-location !22
   
   bb.2:
     successors: %bb.4(0x30000000), %bb.3(0x50000000)
     liveins: $rcx, $rdi, $eflags
   
     JCC_1 %bb.4, 4, implicit $eflags, debug-location !22
   
   bb.3:
     successors: %bb.5(0x04000000)
     liveins: $rcx, $rdi, $eflags
   
     $rdx = MOV64ri 0, debug-instr-number 7, debug-location !22
-    DBG_INSTR_REF !18, !DIExpression(), dbg-instr-ref(7, 0), debug-location !22
+    DBG_INSTR_REF !18, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(7, 0), debug-location !22
     $rcx = MOV64rr $rdx
     JMP_1 %bb.5, debug-location !22
   
   bb.4:
     liveins: $rcx, $rdi, $eflags
   
     $rdx = MOV64rr killed $rcx, debug-location !22
   

llvm/test/DebugInfo/MIR/InstrRef/spill-slot-limits.mir

 #
 # This is a copy of livedebugvalues_stackslot_subregs.mir, here the stack slot
 #  limit is set to zero, meaning the spill shouldn't be tracked.
 #
 ## Capture variable num,
 # CHECK: ![[VARNUM:[0-9]+]] = !DILocalVariable
 #
 ## There should be no variable location, just a single DBG_VALUE $noreg.
-# CHECK:     DBG_VALUE $noreg
+# CHECK:     DBG_VALUE_LIST {{.+}} $noreg
 #
 ## And then another.
-# CHECK:     DBG_VALUE $noreg
+# CHECK:     DBG_VALUE_LIST {{.+}} $noreg
 #
 ## Test that if there's no limit, we _do_ get some locations.
 # NOLIMIT:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-# NOLIMIT-NEXT: DBG_VALUE $esi
+# NOLIMIT-NEXT: DBG_VALUE_LIST {{.+}} $esi
 #
 # NOLIMIT:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(5,
-# NOLIMIT-NEXT: DBG_VALUE $rsp
+# NOLIMIT-NEXT: DBG_VALUE_LIST {{.+}} $rsp
 --- |
   define i8 @test(i32 %bar) local_unnamed_addr !dbg !7 {
   entry:
     ret i8 0, !dbg !12
   }
 
   declare dso_local void @ext(i64)
 
liveins: $rdi, $rax, $rbx
     $edi = COPY $eax
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rdi :: (store 8 into %stack.0)
     $rsi = MOV64rm $rsp, 1, $noreg, 8, $noreg :: (load 8 from %stack.0)
 
     MOV64mr $rsp, 1, $noreg, 16, $noreg, $rbx :: (store 8 into %stack.0)
     $rax = MOV64ri 0
     $rdi = MOV64ri 0
 
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(1, 0), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !12
     ; This shouldn't find anything -- we have disabled tracking of spills.
 
     ; In addition to plain spills, spills that are folded into instructions
     ; shouldn't be tracked either.
     INC32m $rsp, 1, $noreg, 4, $noreg, implicit-def dead $eflags, debug-instr-number 5, debug-location !12 :: (store (s32) into %stack.0)
 
 
-    DBG_INSTR_REF !11, !DIExpression(), dbg-instr-ref(5, 1000000), debug-location !12
+    DBG_INSTR_REF !11, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(5, 1000000), debug-location !12
     ; Shouldn't be able to find the reference to instr 5's memory operand.
 
     RET64 $rsi, debug-location !12
 ...

llvm/test/DebugInfo/MIR/InstrRef/stack-coloring-dbg-phi.mir

body:             |
   bb.13:
     successors: %bb.18(0x2aaaaaab), %bb.14(0x55555555)
   
     %2:gr32 = PHI undef %35:gr32, %bb.11, %14, %bb.21
     %3:gr64 = PHI %36, %bb.11, %13, %bb.21
     ;AAAAAA %4:gr32 = PHI %0, %bb.11, %10, %bb.21, debug-instr-number 1
     ;BBBBBB %4:gr32 = PHI %0, %bb.11, %10, %bb.21
     %5:gr32 = PHI undef %35:gr32, %bb.11, %9, %bb.21
-    ;AAAAAA DBG_INSTR_REF !10, !DIExpression(), dbg-instr-ref(1, 0), debug-location !9
+    ;AAAAAA DBG_INSTR_REF !10, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !9
     ;BBBBBB DBG_VALUE %4, 0, !10, !DIExpression(), debug-location !9
     %39:gr8 = COPY %27.sub_8bit
     TEST8rr killed %39, %39, implicit-def $eflags, debug-location !9
     JCC_1 %bb.18, 5, implicit killed $eflags, debug-location !9
     JMP_1 %bb.14, debug-location !9
   
   bb.14:
     successors: %bb.17(0x40000001), %bb.15(0x3fffffff)

llvm/test/DebugInfo/MIR/InstrRef/survives-livedebugvars.mir

 body:             |
   bb.0:
     liveins: $rdi, $esi
 
     %4:gr32 = COPY $esi
     %2:gr64 = COPY $rdi
     %3:gr64 = COPY killed %2
     %5:gr32 = COPY killed %4
-    DBG_INSTR_REF !9, !DIExpression(), dbg-instr-ref(1, 0), debug-location !16
+    DBG_INSTR_REF !9, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !16
     JMP_1 %bb.3
 
   bb.1:
-    DBG_INSTR_REF !9, !DIExpression(), dbg-instr-ref(2, 0), debug-location !16
+    DBG_INSTR_REF !9, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(2, 0), debug-location !16
     JMP_1 %bb.4
 
   bb.2:
     ADJCALLSTACKDOWN64 0, 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !19
     $edi = COPY %6, debug-location !19
     $al = MOV8ri 0, debug-location !19
-    DBG_INSTR_REF !9, !DIExpression(), dbg-instr-ref(3, 0), debug-location !16
+    DBG_INSTR_REF !9, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(3, 0), debug-location !16
     CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit $al, implicit $edi, implicit-def $eax, debug-location !19
     ADJCALLSTACKUP64 0, 0, implicit-def $rsp, implicit-def $eflags, implicit-def $ssp, implicit $rsp, implicit $ssp, debug-location !19
     %7:gr32 = COPY $eax, debug-location !19
     JMP_1 %bb.1
 
   bb.3:
     %6:gr32 = MOV32rm %3, 1, $noreg, 0, $noreg, debug-location !17
-    DBG_INSTR_REF !9, !DIExpression(), dbg-instr-ref(4, 0), debug-location !16
+    DBG_INSTR_REF !9, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(4, 0), debug-location !16
     JMP_1 %bb.2
 
   bb.4:
     $eax = COPY %5, debug-location !18
-    DBG_INSTR_REF !9, !DIExpression(), dbg-instr-ref(5, 0), debug-location !16
+    DBG_INSTR_REF !9, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(5, 0), debug-location !16
     RET64 implicit $eax, debug-location !18
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/win32-chkctk-modifies-esp.mir

bb.0.entry:
     frame-setup SEH_StackAlloc 4
     frame-setup SEH_EndPrologue
     renamable $eax = MOV32rm $ebp, 1, $noreg, 8, $noreg, debug-location !40 :: (dereferenceable load (s32) from %ir.x.addr)
     MOV32mr $ebp, 1, $noreg, -4, $noreg, $esp, debug-location !41 :: (store (s32) into %ir.saved_stack)
     renamable $eax = SHL32ri killed renamable $eax, 2, implicit-def dead $eflags, debug-location !41
     CALLpcrel32 &_chkstk, implicit $esp, implicit $ssp, implicit $eax, implicit $esp, implicit-def dead $eax, implicit-def $esp, implicit-def dead $eflags, debug-instr-number 2, debug-location !41
     $ebx = MOV32rr $esp, debug-location !41
     $eax = MOV32ri 0
-    DBG_INSTR_REF !42, !DIExpression(DW_OP_deref), dbg-instr-ref(2, 6), debug-location !46
+    DBG_INSTR_REF !42, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_deref), dbg-instr-ref(2, 6), debug-location !46
     ; CHECK-LABEL: DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 6)
-    ; CHECK:       DBG_VALUE $esp
+    ; CHECK:       DBG_VALUE_LIST {{.+}}, $esp
 
     ;; Variable value is $esp / $ebx, will be based on $esp initially. We'll now
     ;; allocate more stack space, and several things should happen:
     ;;  * We recognise it as modifying $esp, and move the variable location to
     ;;    be based on $ebx,
     ;;  * We recognise the modified $esp as a new value, and if we assign it to
     ;;    the variable location, will base the variable on $esp,
     ;;  * Clobbering the second modified $esp won't re-locate the variable to
     ;;    $ebx, which comes from the first modified $esp.
     CALLpcrel32 &_chkstk, implicit $esp, implicit $ssp, implicit $eax, implicit $esp, implicit-def dead $eax, implicit-def $esp, implicit-def dead $eflags, debug-instr-number 3, debug-location !41
     ; CHECK-NEXT: CALLpcrel32
-    ; CHECK-NEXT: DBG_VALUE $ebx
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $ebx
 
-    DBG_INSTR_REF !42, !DIExpression(DW_OP_deref), dbg-instr-ref(3, 6), debug-location !46
+    DBG_INSTR_REF !42, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_deref), dbg-instr-ref(3, 6), debug-location !46
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(3, 6)
-    ; CHECK-NEXT: DBG_VALUE $esp
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $esp
 
     $esp = ADD32ri killed $esp, 0, implicit-def dead $eflags
     ; CHECK-NEXT: ADD32ri
 
-    DBG_INSTR_REF !42, !DIExpression(DW_OP_deref), dbg-instr-ref(3, 6), debug-location !46
+    DBG_INSTR_REF !42, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_deref), dbg-instr-ref(3, 6), debug-location !46
     ; CHECK-NEXT: DBG_INSTR_REF {{.+}}, dbg-instr-ref(3, 6)
-    ; CHECK-NEXT: DBG_VALUE $noreg
+    ; CHECK-NEXT: DBG_VALUE_LIST {{.+}}, $noreg
 
     $esp = MOV32rr $ebp, debug-location !49
     $ebp = frame-destroy POP32r implicit-def $esp, implicit $esp, debug-location !49
     RET32 debug-location !49
 
 ...

llvm/test/DebugInfo/MIR/InstrRef/x86-drop-compare-inst.mir

 body:             |
   bb.0._ZN4llvm11raw_ostreamlsEPKc.exit2752:
     successors: %bb.1(0x30000000), %bb.2(0x50000000)
   
     %1:gr64 = IMPLICIT_DEF
     %0:gr64 = MOV64rm killed %1, 1, $noreg, 0, $noreg, debug-location !7 :: (load (s64) from `i8** undef`)
     %2:gr32 = COPY %0.sub_32bit, debug-location !7
     %3:gr32 = SUB32rm %2, %0, 1, $noreg, 0, $noreg, implicit-def $eflags, debug-instr-number 1, debug-location !7 :: (load (s32) from %ir._M_start.i2756, align 8)
-    DBG_INSTR_REF !8, !DIExpression(), dbg-instr-ref(1, 0), debug-location !7
+    DBG_INSTR_REF !8, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0), debug-location !7
     JCC_1 %bb.2, 5, implicit $eflags, debug-location !7
     JMP_1 %bb.1, debug-location !7
   
   bb.1.for.cond.cleanup376:
     RET 0
   
   bb.2.for.body377:
     RET 0
 
 ...

llvm/test/DebugInfo/MIR/X86/instr-ref-join-def-vphi.mir

 # RUN: llc -run-pass=livedebugvalues %s -o - -experimental-debug-variable-locations | FileCheck %s --check-prefixes=CHECK
 
 # Test that we do not drop debug values when joining a VPHI and a Def that use
 # the same value.
 # In this test case, the live out value for "a" from bb.4 is a VPHI with a
 # defined value, the value live-in register $esi at bb.3. In bb.5, we also have
 # a DBG_INSTR_REF that explicitly defines "a" as holding that same value. When
 # joining these values to determine the live-in value of "a" at bb.6, we should
 # recognize that these values are identical and produce a valid live-in debug
 # value.
 
 # CHECK: ![[VAR:[0-9]+]] = !DILocalVariable(name: "a"
 
 # CHECK-LABEL: bb.6
-# CHECK: DBG_VALUE $esi, $noreg, ![[VAR]], !DIExpression()
+# CHECK: DBG_VALUE_LIST ![[VAR]], !DIExpression(DW_OP_LLVM_arg, 0), $esi
 
 --- |
   target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
   target triple = "x86_64-unknown-linux-gnu"
 
   ; Function Attrs: mustprogress uwtable
   define dso_local noundef i32 @"?foo@@YAHH@Z"(i32 noundef %0) local_unnamed_addr #0 !dbg !8 {
     call void @llvm.dbg.value(metadata i32 %0, metadata !14, metadata !DIExpression()), !dbg !16
bb.3 (%ir-block.13, align 16):
     JCC_1 %bb.4, 14, implicit $eflags, debug-location !26
 
   bb.1 (%ir-block.3):
     successors: %bb.2(0x30000000), %bb.3(0x50000000)
     liveins: $edi, $esi
 
     DBG_PHI $esi, 3
     DBG_PHI $edi, 2
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(3, 0), debug-location !16
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(3, 0), debug-location !16
     CALL64pcrel32 @"?bar@@YAHXZ", csr_win64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !19
     renamable $edi = nsw SUB32rr killed renamable $edi, killed renamable $eax, implicit-def dead $eflags, debug-instr-number 1, debug-location !19
     renamable $eax = IMUL32rri renamable $edi, -1431655765, implicit-def dead $eflags, debug-location !21
     renamable $eax = ADD32ri killed renamable $eax, 715827882, implicit-def dead $eflags, debug-location !21
     CMP32ri killed renamable $eax, 1431655764, implicit-def $eflags, debug-location !21
     JCC_1 %bb.3, 7, implicit $eflags, debug-location !21
 
   bb.2 (%ir-block.10):
     successors: %bb.3(0x80000000)
     liveins: $edi, $esi
 
     CALL64pcrel32 @"?bar@@YAHXZ", csr_win64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !22
     renamable $esi = nsw ADD32rr killed renamable $esi, killed renamable $eax, implicit-def dead $eflags, debug-instr-number 4, debug-location !22
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(4, 0), debug-location !16
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(4, 0), debug-location !16
     JMP_1 %bb.3
 
   bb.4 (%ir-block.16):
     successors: %bb.5(0x40000000), %bb.6(0x40000000)
     liveins: $edi, $esi
 
     TEST8ri renamable $dil, 1, implicit-def $eflags, implicit killed $edi, debug-location !30
     JCC_1 %bb.6, 5, implicit $eflags, debug-location !30
 
   bb.5 (%ir-block.19):
     successors: %bb.6(0x80000000)
     liveins: $esi
 
     CALL64pcrel32 @"?bar@@YAHXZ", csr_win64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !31
-    DBG_INSTR_REF !14, !DIExpression(), dbg-instr-ref(5, 0), debug-location !16
+    DBG_INSTR_REF !14, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(5, 0), debug-location !16
 
   bb.6 (%ir-block.22):
     liveins: $esi
 
     $eax = MOV32rr killed $esi, debug-location !35
     SEH_Epilogue debug-location !35
     $rsp = frame-destroy ADD64ri8 $rsp, 40, implicit-def dead $eflags, debug-location !35
     $rdi = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !35
     $rsi = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !35
     RET64 $eax, debug-location !35
 
 ...

llvm/test/DebugInfo/X86/dbg-value-funcarg.ll

 ; INSTRREF-LABEL: name:            foo_local
 ; INSTRREF-NOT: DBG_
 ; INSTRREF:      DBG_PHI $edi, 1
 ; INSTRREF:      DBG_VALUE $edi, $noreg, ![[T1A]], !DIExpression(),
 ; INSTRREF-NEXT: %0:gr32 = COPY $edi
 ; INSTRREF-NEXT: DBG_VALUE 123, $noreg, ![[LOCAL]], !DIExpression(),
 ; INSTRREF:      CALL64pcrel32 @bar,
 ; INSTRREF-NEXT: ADJCALLSTACKUP64
-; INSTRREF:      DBG_INSTR_REF ![[LOCAL]], !DIExpression(), dbg-instr-ref(1, 0),
+; INSTRREF:      DBG_INSTR_REF ![[LOCAL]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0),
 ; INSTRREF-NOT: DBG_
 ; INSTRREF:    TCRETURNdi64 @bar,
 
 entry:
   call void @llvm.dbg.value(metadata i32 %t1a, metadata !12, metadata !DIExpression()), !dbg !14
   call void @llvm.dbg.value(metadata i32 123, metadata !13, metadata !DIExpression()), !dbg !15
   tail call void @bar(i32 123) #3, !dbg !16
   call void @llvm.dbg.value(metadata i32 %t1a, metadata !13, metadata !DIExpression()), !dbg !15

 ; CHECK: TCRETURNdi64 @bar,
 ; INSTRREF-LABEL: name:            foo_other_param
 ; INSTRREF: DBG_PHI $edi, 1
 ; INSTRREF: DBG_VALUE $edi, $noreg, ![[T2A]], !DIExpression(),
 ; INSTRREF: DBG_VALUE $esi, $noreg, ![[T2B]], !DIExpression(),
 ; INSTRREF: CALL64pcrel32 @bar,
 ; INSTRREF: DBG_VALUE 123, $noreg, ![[T2B]], !DIExpression(),
 ; INSTRREF: CALL64pcrel32 @bar,
-; INSTRREF: DBG_INSTR_REF ![[T2B]], !DIExpression(), dbg-instr-ref(1, 0),
+; INSTRREF: DBG_INSTR_REF ![[T2B]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0),
 ; INSTRREF: TCRETURNdi64 @bar,
 
 entry:
   call void @llvm.dbg.value(metadata i32 %t2a, metadata !23, metadata !DIExpression()), !dbg !25
   call void @llvm.dbg.value(metadata i32 %t2b, metadata !24, metadata !DIExpression()), !dbg !26
   tail call void @bar(i32 %t2b) #3, !dbg !27
   call void @llvm.dbg.value(metadata i32 123, metadata !24, metadata !DIExpression()), !dbg !26
   tail call void @bar(i32 123) #3, !dbg !28

 ; CHECK: DBG_VALUE 123, $noreg, ![[T3A]], !DIExpression(),
 ; CHECK: CALL64pcrel32 @bar,
 ; CHECK: DBG_VALUE %0, $noreg, ![[T3A]], !DIExpression(),
 ; CHECK: TCRETURNdi64 @bar,
 ; INSTRREF-LABEL: name:            foo_same_param
 ; INSTRREF: DBG_PHI $edi, 1
 ; INSTRREF: DBG_VALUE $edi, $noreg, ![[T3A]], !DIExpression(),
 ; INSTRREF: CALL64pcrel32 @bar,
-; INSTRREF: DBG_INSTR_REF ![[TMP]], !DIExpression(), dbg-instr-ref(1, 0),
+; INSTRREF: DBG_INSTR_REF ![[TMP]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0),
 ; INSTRREF: DBG_VALUE 123, $noreg, ![[T3A]], !DIExpression(),
 ; INSTRREF: CALL64pcrel32 @bar,
-; INSTRREF: DBG_INSTR_REF ![[T3A]], !DIExpression(), dbg-instr-ref(1, 0),
+; INSTRREF: DBG_INSTR_REF ![[T3A]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0),
 ; INSTRREF: TCRETURNdi64 @bar,
 entry:
   call void @llvm.dbg.value(metadata i32 %t3a, metadata !33, metadata !DIExpression()), !dbg !35
   tail call void @bar(i32 %t3a) #3, !dbg !36
   call void @llvm.dbg.value(metadata i32 %t3a, metadata !34, metadata !DIExpression()), !dbg !37
   call void @llvm.dbg.value(metadata i32 123, metadata !33, metadata !DIExpression()), !dbg !35
   tail call void @bar(i32 123) #3, !dbg !38
   call void @llvm.dbg.value(metadata i32 %t3a, metadata !33, metadata !DIExpression()), !dbg !35

llvm/test/DebugInfo/X86/dbg-value-funcarg2.ll

 ; CHECK-NOT: DBG_VALUE
 ; CHECK-DAG: DBG_VALUE %[[R2]], $noreg, ![[S1]], !DIExpression(DW_OP_LLVM_fragment, 0, 64)
 ; CHECK-DAG: DBG_VALUE %[[R1]], $noreg, ![[S1]], !DIExpression(DW_OP_LLVM_fragment, 64, 64)
 
 ;; In instruction referencing mode, we should refer to the instruction number
 ;; of the earlier DBG_PHIs.
 ; INSTRREF:     ADJCALLSTACKUP
 ; INSTRREF-NOT: DBG_
-; INSTRREF-DAG: DBG_INSTR_REF ![[S1]], !DIExpression(DW_OP_LLVM_fragment, 0, 64), dbg-instr-ref(1, 0)
-; INSTRREF-DAG: DBG_INSTR_REF ![[S1]], !DIExpression(DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(2, 0)
+; INSTRREF-DAG: DBG_INSTR_REF ![[S1]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 64), dbg-instr-ref(1, 0)
+; INSTRREF-DAG: DBG_INSTR_REF ![[S1]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(2, 0)
 
 ; And then no more DBG_ instructions before the add.
 ; COMMON-NOT: DBG_
 ; COMMON:     ADD32rr
 
 entry:
   %tmp.sroa.0 = alloca i64, align 8
   %tmp.sroa.4 = alloca i64, align 8

llvm/test/DebugInfo/X86/dbg-value-funcarg4.ll

 ; RUN: llc -mtriple=x86_64-unknown-linux-gnu -start-after=codegenprepare -stop-before=finalize-isel -o - %s -experimental-debug-variable-locations=true | FileCheck %s --implicit-check-not=DBG_PHI
 
 ; Test that for multiple dbg.values referring to the same argument, we emit a
 ; single DBG_PHI and refer to it twice. (Using more than one DBG_PHI is fine,
 ; but inefficient).
 
 ; CHECK-DAG: ![[LOCAL:.*]] = !DILocalVariable(name: "local"
 ; CHECK-DAG: ![[LOCAL2:.*]] = !DILocalVariable(name: "local2"
 
 ; CHECK: DBG_PHI $edi, 1
 
-; CHECK: DBG_INSTR_REF ![[LOCAL]], !DIExpression(), dbg-instr-ref(1, 0)
-; CHECK: DBG_INSTR_REF ![[LOCAL2]], !DIExpression(), dbg-instr-ref(1, 0)
+; CHECK: DBG_INSTR_REF ![[LOCAL]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
+; CHECK: DBG_INSTR_REF ![[LOCAL2]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 
 declare void @bar(i32)
 declare void @llvm.dbg.value(metadata, metadata, metadata)
 
 define dso_local void @foo_local(i32 %t1a) local_unnamed_addr !dbg !7 {
 entry:
   tail call void @bar(i32 %t1a) #3, !dbg !17
   %bees = add i32 %t1a, 3

llvm/test/DebugInfo/X86/dbg-value-list-selectiondag-salvage.ll

-; RUN: llc %s -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck %s
+; RUN: llc %s -start-after=codegenprepare -stop-before=finalize-isel -experimental-debug-variable-locations=false -o - | FileCheck %s
 
 ;; Generated from clang -O2 -emit-llvm -S -g reduce.c -o -
 ;; $ cat reduce.c
 ;; struct {
 ;;   int a;
 ;; } * b;
 ;; int c;
 ;; void d() {

llvm/test/DebugInfo/X86/debug_value_list_selectiondag.ll

-; RUN: llc %s -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck --check-prefixes=CHECK,DAG %s
-; RUN: llc %s -fast-isel=true -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck --check-prefixes=CHECK,FAST %s
-; RUN: llc %s -global-isel=true -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck --check-prefixes=CHECK,GLOBAL %s
+; RUN: llc %s -start-after=codegenprepare -stop-before=finalize-isel -experimental-debug-variable-locations=false -o - | FileCheck --check-prefixes=CHECK,DAG %s
+; RUN: llc %s -fast-isel=true -start-after=codegenprepare -stop-before=finalize-isel -experimental-debug-variable-locations=false -o - | FileCheck --check-prefixes=CHECK,FAST %s
+; RUN: llc %s -global-isel=true -start-after=codegenprepare -stop-before=finalize-isel -experimental-debug-variable-locations=false -o - | FileCheck --check-prefixes=CHECK,GLOBAL %s
 
 ;; Test that a dbg.value that uses a DIArgList is correctly converted to a
 ;; DBG_VALUE_LIST that uses the registers corresponding to its operands.
 
 ; CHECK-DAG: [[A_VAR:![0-9]+]] = !DILocalVariable(name: "a"
 ; CHECK-DAG: [[B_VAR:![0-9]+]] = !DILocalVariable(name: "b"
 ; CHECK-DAG: [[C_VAR:![0-9]+]] = !DILocalVariable(name: "c"
-; CHECK-LABEL: bb.{{(0|1)}}.entry
-; DAG-DAG: DBG_VALUE_LIST [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), %0, debug-location
-; DAG-DAG: DBG_VALUE_LIST [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), %1, debug-location
-; DAG: DBG_VALUE_LIST [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), %0, %1, debug-location
-; FAST-DAG: DBG_VALUE $noreg, $noreg, [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
-; FAST-DAG: DBG_VALUE $noreg, $noreg, [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
-; FAST: DBG_VALUE $noreg, $noreg, [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), debug-location
-; GLOBAL-DAG: DBG_VALUE $noreg, 0, [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
-; GLOBAL-DAG: DBG_VALUE $noreg, 0, [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
-; GLOBAL: DBG_VALUE $noreg, 0, [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), debug-location
+; CHECK-LABEL: bb.{{(0|1)}}.entry
+; DAG-DAG: DBG_VALUE_LIST [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), %0, debug-location
+; DAG-DAG: DBG_VALUE_LIST [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), %1, debug-location
+; DAG: DBG_VALUE_LIST [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), %0, %1, debug-location
+; FAST-DAG: DBG_VALUE $noreg, $noreg, [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
+; FAST-DAG: DBG_VALUE $noreg, $noreg, [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
+; FAST: DBG_VALUE $noreg, $noreg, [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), debug-location
+; GLOBAL-DAG: DBG_VALUE $noreg, 0, [[A_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
+; GLOBAL-DAG: DBG_VALUE $noreg, 0, [[B_VAR]], !DIExpression(DW_OP_LLVM_arg, 0), debug-location
+; GLOBAL: DBG_VALUE $noreg, 0, [[C_VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus), debug-location
 
 target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-pc-windows-msvc19.16.27034"
 
 define dso_local i32 @"?foo@@YAHHH@Z"(i32 %a, i32 %b) local_unnamed_addr !dbg !8 {
 entry:
   call void @llvm.dbg.value(metadata !DIArgList(i32 %b), metadata !14, metadata !DIExpression(DW_OP_LLVM_arg, 0)), !dbg !17
   call void @llvm.dbg.value(metadata !DIArgList(i32 %a), metadata !15, metadata !DIExpression(DW_OP_LLVM_arg, 0)), !dbg !17

llvm/test/DebugInfo/X86/instr-ref-dbg-declare.ll

 ; RUN: llc %s -stop-before=finalize-isel -o - \
 ; RUN:     -experimental-debug-variable-locations=true \
 ; RUN:  | FileCheck %s
 
 ;; Copy of DebugInfo/COFF/types-array-advanced.ll. This features a dbg.declare 
 ;; of something (dynamic alloca) that isn't an argument, causing a SDDbgValue
 ;; with the indirect flag set to be emitted. Test that it's preserved in
 ;; instruction referencing mode -- we don't have an IsIndirect flag on
 ;; DBG_INSTR_REF, so it gets encoded as an additional DW_OP_deref.
 ;;
 ;; NB: the original test has an additional spurious DW_OP_deref in the
 ;; dbg.declare's arguments, which is preserved here, translating to two derefs.
 
-; CHECK: DBG_INSTR_REF !{{[0-9]+}}, !DIExpression(DW_OP_deref, DW_OP_deref), dbg-instr-ref(1, 2)
+; CHECK: DBG_INSTR_REF !{{[0-9]+}}, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_deref, DW_OP_deref), dbg-instr-ref(1, 2)
 
 source_filename = "test/DebugInfo/COFF/types-array-advanced.ll"
 target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
 target triple = "i686-pc-windows-msvc18.0.31101"
 
 %struct.incomplete_struct = type { i32 }
 
 @"\01?multi_dim_arr@@3PAY146DA" = global [2 x [5 x [7 x i8]]] zeroinitializer, align 1, !dbg !0

llvm/test/DebugInfo/X86/instr-ref-selectiondag.ll

 ;; In instruction referencing mode, the "real" argument becomes a DBG_VALUE,
 ;; but the hoisted variable location from the inlined scope is a DBG_INSTR_REF.
 
 ; INSTRREF-LABEL: name: qux
 
 ; INSTRREF:      DBG_PHI $rdi, 1
 ; INSTRREF-NEXT: DBG_VALUE $rdi, 0, ![[SOCKS]], !DIExpression(),
 ; INSTRREF-NEXT: %0:gr64 = COPY $rdi
-; INSTRREF-NEXT: DBG_INSTR_REF ![[KNEES]], !DIExpression(DW_OP_deref), dbg-instr-ref(1, 0),
+; INSTRREF-NEXT: DBG_INSTR_REF ![[KNEES]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_deref), dbg-instr-ref(1, 0),
 
 ; In fast-isel mode, neither variable are hoisted or forwarded to a physreg.
 
 ; FASTISEL-INSTRREF-LABEL: name: qux
 
 ; FASTISEL-INSTRREF:      DBG_PHI $rdi, 1
-; FASTISEL-INSTRREF:      DBG_INSTR_REF ![[SOCKS]], !DIExpression(DW_OP_deref), dbg-instr-ref(1, 0),
+; FASTISEL-INSTRREF:      DBG_INSTR_REF ![[SOCKS]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_deref), dbg-instr-ref(1, 0),
 
 ; FASTISEL-INSTRREF-LABEL: bb.1.lala:
-; FASTISEL-INSTRREF:      DBG_INSTR_REF ![[KNEES]], !DIExpression(DW_OP_deref), dbg-instr-ref(1, 0),
+; FASTISEL-INSTRREF:      DBG_INSTR_REF ![[KNEES]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_deref), dbg-instr-ref(1, 0),
 declare i64 @cheddar(ptr %arg)
 
 define void @qux(ptr noalias sret(i32) %agg.result) !dbg !40 {
 entry:
   call void @llvm.dbg.declare(metadata ptr %agg.result, metadata !41, metadata !DIExpression()), !dbg !42
   %foo = call i64 @cheddar(ptr %agg.result), !dbg !42
   br label %lala
 

llvm/test/DebugInfo/X86/live-debug-values-expr-conflict.ll

 ; 
 ;   return bar;
 ; }
 ;
 ; We should get a plain DBG_VALUE in the entry block, a plain one then complex
 ; one in the block two, and none in block three.
 ; CHECK:       ![[BAZVAR:[0-9]+]] = !DILocalVariable(name: "baz",
 ; CHECK-LABEL: bb.0.entry:
-; CHECK:       DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
+; CHECK:       DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]], 
 ; CHECK-SAME:     !DIExpression()
 ; CHECK-LABEL: bb.1.if.then:
 ; CHECK-LABEL: bb.2.if.else:
-; CHECK:       DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
+; CHECK:       DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]], 
 ; CHECK-SAME:     !DIExpression()
-; CHECK:       DBG_VALUE {{[0-9a-zA-Z$%_]*}}, $noreg, ![[BAZVAR]],
-; CHECK-SAME:     !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value)
+; CHECK:       DBG_VALUE_LIST ![[BAZVAR]], 
+; CHECK-SAME:     !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 1, DW_OP_stack_value)
+; CHECK-SAME:     {{[0-9a-zA-Z$%_]*}}
 ; CHECK-LABEL: bb.3.if.end:
 ; CHECK-NOT:   DBG_VALUE
+; CHECK-NOT:   DBG_VALUE_LIST
 
 declare void @escape1(i32)
 declare void @escape2(i32)
 declare void @llvm.dbg.value(metadata, metadata, metadata)
 
 define i32 @foo(i32 returned %bar) !dbg !7 {
 entry:
   call void @llvm.dbg.value(metadata i32 %bar, metadata !13, metadata !DIExpression()), !dbg !14

llvm/test/DebugInfo/X86/live-debug-vars-loc-limit.ll

-; RUN: llc --stop-after=virtregrewriter -o - %s | FileCheck %s
+; RUN: llc --stop-after=virtregrewriter -experimental-debug-variable-locations=false -o - %s | FileCheck %s
 
 ; Check that any debug value with 64+ unique machine location operands is set
 ; undef by LiveDebugVariables.
 ; This test uses constant i32 values in the DIArgList instead of SSA values, as
 ; it allows the test case to be much simpler. If at some point we are able to
 ; simplify such constant expressions, this test will fail; if that happens,
 ; there is another version of this test that uses SSA values at:
 ; https://reviews.llvm.org/D101373?id=340953
 
 ; CHECK: ![[VAR_A:[0-9]+]] = !DILocalVariable(name: "a"
 
 ; CHECK-NOT: DBG_VALUE
-; CHECK: DBG_VALUE_LIST ![[VAR_A]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_stack_value), $noreg
+; CHECK: DBG_VALUE_LIST ![[VAR_A]], !DIExpression(DW_OP_LLVM_arg, 0), $noreg
 ; CHECK-NOT: DBG_VALUE
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 define dso_local i32 @_Z3fooi(i32 returned %b) local_unnamed_addr !dbg !8 {
 entry:
   call void @llvm.dbg.value(metadata !DIArgList(i32 1, i32 126, i32 124, i32 122, i32 120, i32 118, i32 116, i32 114, i32 112, i32 110, i32 108, i32 106, i32 104, i32 102, i32 100, i32 98, i32 96, i32 94, i32 92, i32 90, i32 88, i32 86, i32 84, i32 82, i32 80, i32 78, i32 76, i32 74, i32 72, i32 70, i32 68, i32 66, i32 64, i32 62, i32 60, i32 58, i32 56, i32 54, i32 52, i32 50, i32 48, i32 46, i32 44, i32 42, i32 40, i32 38, i32 36, i32 34, i32 32, i32 30, i32 28, i32 26, i32 24, i32 22, i32 20, i32 18, i32 16, i32 14, i32 12, i32 10, i32 8, i32 6, i32 4, i32 2), metadata !14, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 63, DW_OP_plus, DW_OP_LLVM_arg, 62, DW_OP_plus, DW_OP_LLVM_arg, 61, DW_OP_plus, DW_OP_LLVM_arg, 60, DW_OP_plus, DW_OP_LLVM_arg, 59, DW_OP_plus, DW_OP_LLVM_arg, 58, DW_OP_plus, DW_OP_LLVM_arg, 57, DW_OP_plus, DW_OP_LLVM_arg, 56, DW_OP_plus, DW_OP_LLVM_arg, 55, DW_OP_plus, DW_OP_LLVM_arg, 54, DW_OP_plus, DW_OP_LLVM_arg, 53, DW_OP_plus, DW_OP_LLVM_arg, 52, DW_OP_plus, DW_OP_LLVM_arg, 51, DW_OP_plus, DW_OP_LLVM_arg, 50, DW_OP_plus, DW_OP_LLVM_arg, 49, DW_OP_plus, DW_OP_LLVM_arg, 48, DW_OP_plus, DW_OP_LLVM_arg, 47, DW_OP_plus, DW_OP_LLVM_arg, 46, DW_OP_plus, DW_OP_LLVM_arg, 45, DW_OP_plus, DW_OP_LLVM_arg, 44, DW_OP_plus, DW_OP_LLVM_arg, 43, DW_OP_plus, DW_OP_LLVM_arg, 42, DW_OP_plus, DW_OP_LLVM_arg, 41, DW_OP_plus, DW_OP_LLVM_arg, 40, DW_OP_plus, DW_OP_LLVM_arg, 39, DW_OP_plus, DW_OP_LLVM_arg, 38, DW_OP_plus, DW_OP_LLVM_arg, 37, DW_OP_plus, DW_OP_LLVM_arg, 36, DW_OP_plus, DW_OP_LLVM_arg, 35, DW_OP_plus, DW_OP_LLVM_arg, 34, DW_OP_plus, DW_OP_LLVM_arg, 33, DW_OP_plus, DW_OP_LLVM_arg, 32, DW_OP_plus, DW_OP_LLVM_arg, 31, DW_OP_plus, DW_OP_LLVM_arg, 30, DW_OP_plus, DW_OP_LLVM_arg, 29, DW_OP_plus, DW_OP_LLVM_arg, 28, DW_OP_plus, DW_OP_LLVM_arg, 27, DW_OP_plus, DW_OP_LLVM_arg, 26, DW_OP_plus, DW_OP_LLVM_arg, 25, DW_OP_plus, DW_OP_LLVM_arg, 24, DW_OP_plus, DW_OP_LLVM_arg, 23, DW_OP_plus, DW_OP_LLVM_arg, 22, DW_OP_plus, DW_OP_LLVM_arg, 21, DW_OP_plus, DW_OP_LLVM_arg, 20, DW_OP_plus, DW_OP_LLVM_arg, 19, DW_OP_plus, DW_OP_LLVM_arg, 18, DW_OP_plus, DW_OP_LLVM_arg, 17, DW_OP_plus, DW_OP_LLVM_arg, 16, DW_OP_plus, DW_OP_LLVM_arg, 15, DW_OP_plus, DW_OP_LLVM_arg, 14, DW_OP_plus, DW_OP_LLVM_arg, 13, DW_OP_plus, DW_OP_LLVM_arg, 12, DW_OP_plus, DW_OP_LLVM_arg, 11, DW_OP_plus, DW_OP_LLVM_arg, 10, DW_OP_plus, DW_OP_LLVM_arg, 9, DW_OP_plus, DW_OP_LLVM_arg, 8, DW_OP_plus, DW_OP_LLVM_arg, 7, DW_OP_plus, DW_OP_LLVM_arg, 6, DW_OP_plus, DW_OP_LLVM_arg, 5, DW_OP_plus, DW_OP_LLVM_arg, 4, DW_OP_plus, DW_OP_LLVM_arg, 3, DW_OP_plus, DW_OP_LLVM_arg, 2, DW_OP_plus, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_stack_value)), !dbg !15

llvm/test/DebugInfo/X86/pieces-4.ll

 ;   asm volatile("" : : : "rax", "rbx", "rcx", "rdx", "rsi", "rdi", "rbp",
 ;                "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15");
 ;   return o.x;
 ; }
 
 ; CHECK-LABEL: bitpiece_spill:                         # @bitpiece_spill
 ; CHECK:               callq   g
 ; CHECK:               movl    %eax, [[offs:[0-9]+]](%rsp)          # 4-byte Spill
-; CHECK:               #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_plus_uconst [[offs]], DW_OP_LLVM_fragment 0 32] [$rsp+0]
+; CHECK:               #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_plus_uconst [[offs]], DW_OP_deref, DW_OP_LLVM_fragment 0 32] $rsp
 ; CHECK:               #DEBUG_VALUE: bitpiece_spill:o <- [DW_OP_LLVM_fragment 32 32] 0
 ; CHECK:               #APP
 ; CHECK:               #NO_APP
 ; CHECK:               movl    [[offs]](%rsp), %eax          # 4-byte Reload
 ; CHECK:               retq
 
 ; DWARF: .debug_loc contents:
 ; DWARF-NEXT: 0x00000000:

llvm/test/DebugInfo/X86/pr34545.ll

 ; RUN: llc -O1 -filetype=asm -mtriple x86_64-unknown-linux-gnu -mcpu=x86-64 \
 ; RUN:    -o - %s -stop-after=livedebugvars \
 ; RUN:    -experimental-debug-variable-locations=false \
 ; RUN: | FileCheck %s --check-prefixes=CHECK,VARLOCS
 ; RUN: llc -O1 -filetype=asm -mtriple x86_64-unknown-linux-gnu -mcpu=x86-64 \
 ; RUN:    -o - %s -stop-after=livedebugvars \
 ; RUN:    -experimental-debug-variable-locations=true \
 ; RUN: | FileCheck %s --check-prefixes=CHECK,INSTRREF
 
 ; CHECK:         $eax = MOV32rm
 ; INSTRREF-SAME:      debug-instr-number 1
 ; INSTRREF:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(1, 0)
-; CHECK:         DBG_VALUE $eax
+; VARLOCS:         DBG_VALUE $eax
+; INSTRREF:        DBG_VALUE_LIST {{.+}} $eax
 ; CHECK:         $eax = SHL32rCL killed renamable $eax,
 ; INSTRREF-SAME:      debug-instr-number 2
 ; INSTRREF:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(2, 0)
-; CHECK:         DBG_VALUE $eax
-; CHECK:         DBG_VALUE $rsp, 0, !{{[0-9]+}}, !DIExpression(DW_OP_constu, 4, DW_OP_minus)
+; VARLOCS:       DBG_VALUE $eax
+; INSTRREF:      DBG_VALUE_LIST {{.+}} $eax
+; VARLOCS:       DBG_VALUE $rsp, 0, !{{[0-9]+}}, !DIExpression(DW_OP_constu, 4, DW_OP_minus)
+; INSTRREF:      DBG_VALUE_LIST !{{[0-9]+}}, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_constu, 4, DW_OP_minus, DW_OP_deref), $rsp
 ; VARLOCS:       DBG_VALUE $eax
 ; CHECK:         $eax = SHL32rCL killed renamable $eax,
 ; INSTRREF-SAME:      debug-instr-number 3
 ; INSTRREF:      DBG_INSTR_REF {{.+}}, dbg-instr-ref(3, 0)
-; CHECK:         DBG_VALUE $eax
+; VARLOCS:       DBG_VALUE $eax
+; INSTRREF:      DBG_VALUE_LIST {{.+}} $eax
 ; CHECK:         RET64 $eax
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 @var = local_unnamed_addr global i32 8, !dbg !0
 @sc = local_unnamed_addr global i32 1, !dbg !6
 

llvm/test/DebugInfo/X86/sdag-combine.ll

 declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
 
 ; Function Attrs: nounwind readnone speculatable
 define swiftcc void @g() #0 !dbg !5 {
 entry:
   %0 = alloca %TSb, align 1
   %1 = call swiftcc i1 @f(), !dbg !7
   ; CHECK: DBG_VALUE $rcx, $noreg, !8, !DIExpression(),
-  ; INSTRREF: DBG_VALUE $ecx, $noreg, !8, !DIExpression(),
+  ; INSTRREF: DBG_VALUE_LIST !8, !DIExpression(DW_OP_LLVM_arg, 0), $ecx
   call void @llvm.dbg.value(metadata i1 %1, metadata !8, metadata !DIExpression()), !dbg !7
   store i1 %1, ptr %0, align 1, !dbg !7
   %2 = zext i1 %1 to i64, !dbg !7
   call void asm sideeffect "", "r"(i64 %2), !dbg !7
   ret void, !dbg !7
 }
 
 ; Function Attrs: nounwind readnone speculatable

llvm/test/DebugInfo/X86/sdag-dangling-dbgvalue.ll

 @S = global %struct.SS { i32 23, i32 -17 }, align 4, !dbg !0
 
 ; Verify that the def comes before the for foo1.
 define i32 @test1() local_unnamed_addr #0 !dbg !17 {
 ; CHECK-LABEL: bb.0.entry1
 ; CHECK-NEXT:    DBG_VALUE 0, $noreg, ![[BAR1]], !DIExpression()
 ; CHECK-NEXT:    [[REG1:%[0-9]+]]:gr64 = LEA64r 
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT:  DBG_INSTR_REF ![[FOO1]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT:  DBG_INSTR_REF ![[FOO1]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT:  DBG_VALUE [[REG1]], $noreg, ![[FOO1]], !DIExpression()
 entry1:
   call void @llvm.dbg.value(metadata ptr @S, metadata !20, metadata !DIExpression()), !dbg !23
   call void @llvm.dbg.value(metadata ptr null, metadata !22, metadata !DIExpression()), !dbg !24
   ret i32 ptrtoint (ptr @S to i32), !dbg !25
 }
 
 ; Verify that the def comes before the for foo2 and bar2.
 define i32 @test2() local_unnamed_addr #0 !dbg !26 {
 ; CHECK-LABEL: bb.0.entry2
 ; CHECK-NEXT:    [[REG2:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[FOO2]], !DIExpression(), dbg-instr-ref(1, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR2]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[FOO2]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR2]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG2]], $noreg, ![[FOO2]], !DIExpression
 ; DBGVALUE-NEXT: DBG_VALUE [[REG2]], $noreg, ![[BAR2]], !DIExpression
 entry2:
   call void @llvm.dbg.value(metadata ptr @S, metadata !28, metadata !DIExpression()), !dbg !30
   call void @llvm.dbg.value(metadata ptr @S, metadata !29, metadata !DIExpression()), !dbg !31
   ret i32 add (i32 ptrtoint (ptr @S to i32), i32 ptrtoint (ptr @S to i32)), !dbg !32
 }
 
 ; Verify that the def comes before the for foo3 and bar3.
 define i32 @test3() local_unnamed_addr #0 !dbg !33 {
 ; CHECK-LABEL: bb.0.entry3
 ; CHECK-NEXT:    [[REG3:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR3]], !DIExpression(), dbg-instr-ref(1, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF ![[FOO3]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR3]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[FOO3]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG3]], $noreg, ![[BAR3]], !DIExpression()
 ; DBGVALUE-NEXT: DBG_VALUE [[REG3]], $noreg, ![[FOO3]], !DIExpression()
 entry3:
   call void @llvm.dbg.value(metadata ptr @S, metadata !36, metadata !DIExpression()), !dbg !38
   call void @llvm.dbg.value(metadata ptr @S, metadata !35, metadata !DIExpression()), !dbg !37
   ret i32 add (i32 ptrtoint (ptr @S to i32), i32 ptrtoint (ptr @S to i32)), !dbg !39
 }
 
 ; Verify that the def comes before the for bar4.
 define i32 @test4() local_unnamed_addr #0 !dbg !40 {
 ; CHECK-LABEL: bb.0.entry4
 ; CHECK-NEXT:    DBG_VALUE $noreg, $noreg, ![[FOO4]], !DIExpression()
 ; CHECK-NEXT:    DBG_VALUE 0, $noreg, ![[FOO4]], !DIExpression()
 ; CHECK-NEXT:    [[REG4:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR4]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR4]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG4]], $noreg, ![[BAR4]], !DIExpression()
 entry4:
   call void @llvm.dbg.value(metadata ptr @S, metadata !42, metadata !DIExpression()), !dbg !44
   call void @llvm.dbg.value(metadata ptr @S, metadata !43, metadata !DIExpression()), !dbg !45
   call void @llvm.dbg.value(metadata ptr null, metadata !42, metadata !DIExpression()), !dbg !44
   ret i32 ptrtoint (ptr @S to i32), !dbg !46
 }
 
 ; Verify that we do not get a DBG_VALUE that maps foo5 to @S here.
 define i32 @test5() local_unnamed_addr #0 !dbg !47 {
 ; CHECK-LABEL: bb.0.entry5:
 ; CHECK-NEXT:    DBG_VALUE $noreg, $noreg, ![[FOO5]], !DIExpression()
 ; CHECK-NEXT:    DBG_VALUE 0, $noreg, ![[FOO5]], !DIExpression()
 ; CHECK-NEXT:    [[REG5:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR5]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR5]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG5]], $noreg, ![[BAR5]], !DIExpression()
 ; CHECK-NOT:     DBG_{{.*}} ![[FOO5]], !DIExpression()
 ; CHECK:         RET
 entry5:
   call void @llvm.dbg.value(metadata ptr @S, metadata !49, metadata !DIExpression()), !dbg !51
   call void @llvm.dbg.value(metadata ptr @S, metadata !50, metadata !DIExpression()), !dbg !52
   call void @llvm.dbg.value(metadata ptr null, metadata !50, metadata !DIExpression()), !dbg !52
   ret i32 ptrtoint (ptr @S to i32), !dbg !53

llvm/test/DebugInfo/X86/sdag-dbgvalue-phi-use-3.ll

 ; CHECK-NEXT:    [[REG4:%[0-9]+]]:gr32 = PHI
 ; INSTRREF-SAME:    debug-instr-number 7
 ; CHECK-NEXT:    [[REG5:%[0-9]+]]:gr32_nosp = PHI
 ; INSTRREF-SAME:    debug-instr-number 8
 ; CHECK-NEXT:    [[REG6:%[0-9]+]]:gr32 = PHI
 ; INSTRREF-SAME:    debug-instr-number 9
 ; CHECK-NEXT:    [[REG7:%[0-9]+]]:gr32 = PHI
 ; INSTRREF-SAME:    debug-instr-number 10
-; INSTRREF-NEXT: DBG_INSTR_REF !19, !DIExpression(DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(5, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !19, !DIExpression(DW_OP_LLVM_fragment, 32, 32), dbg-instr-ref(6, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !18, !DIExpression(DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(7, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !18, !DIExpression(DW_OP_LLVM_fragment, 32, 32), dbg-instr-ref(8, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !17, !DIExpression(DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(9, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !17, !DIExpression(DW_OP_LLVM_fragment, 32, 32), dbg-instr-ref(10, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !19, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(5, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !19, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 32, 32), dbg-instr-ref(6, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !18, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(7, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !18, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 32, 32), dbg-instr-ref(8, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !17, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(9, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !17, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 32, 32), dbg-instr-ref(10, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG2]], $noreg, !19, !DIExpression(DW_OP_LLVM_fragment, 0, 32)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG3]], $noreg, !19, !DIExpression(DW_OP_LLVM_fragment, 32, 32)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG4]], $noreg, !18, !DIExpression(DW_OP_LLVM_fragment, 0, 32)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG5]], $noreg, !18, !DIExpression(DW_OP_LLVM_fragment, 32, 32)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG6]], $noreg, !17, !DIExpression(DW_OP_LLVM_fragment, 0, 32)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG7]], $noreg, !17, !DIExpression(DW_OP_LLVM_fragment, 32, 32)
   %u.023 = phi i64 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
   %y.022 = phi i64 [ 13, %for.body.lr.ph ], [ %mul, %for.body ]

llvm/test/DebugInfo/X86/sdag-dbgvalue-phi-use-4.ll

 
 ; CHECK-LABEL: bb.{{.*}}.if.end36:
 ; CHECK:         [[REG1:%[0-9]+]]:gr32 = PHI
 ; INSTRREF-SAME:    debug-instr-number 1
 ; CHECK-NEXT:    [[REG2:%[0-9]+]]:gr32 = PHI
 ; INSTRREF-SAME:    debug-instr-number 2
 ; CHECK-NEXT:    [[REG3:%[0-9]+]]:gr32 = PHI
 ; INSTRREF-SAME:    debug-instr-number 3
-; INSTRREF-NEXT: DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(1, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_fragment, 32, 32), dbg-instr-ref(2, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_fragment, 64, 16), dbg-instr-ref(3, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_fragment, 10, 32), dbg-instr-ref(1, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_fragment, 42, 13), dbg-instr-ref(2, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 32), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 32, 32), dbg-instr-ref(2, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 16), dbg-instr-ref(3, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 10, 32), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF !12, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 42, 13), dbg-instr-ref(2, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG1]], $noreg,  !13, !DIExpression(DW_OP_LLVM_fragment, 0, 32)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG2]], $noreg,  !13, !DIExpression(DW_OP_LLVM_fragment, 32, 32)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG3]], $noreg,  !13, !DIExpression(DW_OP_LLVM_fragment, 64, 16)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG1]], $noreg,  !12, !DIExpression(DW_OP_LLVM_fragment, 10, 32)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG2]], $noreg,  !12, !DIExpression(DW_OP_LLVM_fragment, 42, 13)
 ; CHECK-NOT:  DBG_
 
 target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"

llvm/test/DebugInfo/X86/sdag-salvage-add.ll

 ; different order.
 ;
 ; CHECK:         ![[S4:.*]] = !DILocalVariable(name: "s4", 
 ; CHECK:         ![[MYVAR:.*]] = !DILocalVariable(name: "myVar", 
 ; CHECK:         $rax = MOV64rm
 ; INSTRREF-SAME: debug-instr-number 2,
 ; INSTRREF-NEXT: DBG_INSTR_REF ![[S4]],
 ; DBGVALUE-NEXT: DBG_VALUE $rax, $noreg, ![[MYVAR]],
-; CHECK-SAME:       !DIExpression(DW_OP_plus_uconst, 4096, DW_OP_stack_value)
+; DBGVALUE-SAME:       !DIExpression(DW_OP_plus_uconst, 4096, DW_OP_stack_value)
+; INSTRREF-SAME:       !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 4096, DW_OP_stack_value)
 ; INSTRREF-SAME: dbg-instr-ref(2, 0)
 
 ; INSTRREF:      DBG_INSTR_REF ![[MYVAR]],
 ; DBGVALUE:      DBG_VALUE $rax, $noreg, ![[S4]],
-; CHECK-SAME:           !DIExpression(DW_OP_plus_uconst, 4096, DW_OP_stack_value)
+; DBGVALUE-SAME:           !DIExpression(DW_OP_plus_uconst, 4096, DW_OP_stack_value)
+; INSTRREF-SAME:           !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 4096, DW_OP_stack_value)
 ; INSTRREF-SAME: dbg-instr-ref(2, 0)
 ; CHECK-NEXT: $rdi = MOV64rm killed renamable $rax, 1, $noreg, 4096, $noreg,
 
 source_filename = "test.c"
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.13.0"
 
 %struct.S3 = type { i64 }

llvm/test/DebugInfo/X86/sdagsplit-1.ll

 ; RUN: llc %s -stop-after=livedebugvars -o %t -experimental-debug-variable-locations=true
 ; RUN: cat %t | FileCheck %s
 ;
 ; Test that we can emit debug info for large values that are split
 ; up across multiple registers by the SelectionDAG type legalizer.
 ;
 ;    // Compile with -O1 -m32.
 ;    long long foo (long long a, long long b)
 ;    {
 ;      long long res = b+1;
 ;      if ( a == b )
 ;        return res;
 ;      return 0;
 ;    }
 ;
-; CHECK-DAG: DBG_VALUE ${{[a-z]+}}, $noreg, !{{[0-9]+}}, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location
-; CHECK-DAG: DBG_VALUE ${{[a-z]+}}, $noreg, !{{[0-9]+}}, !DIExpression(DW_OP_LLVM_fragment, 32, 32), debug-location
+; CHECK-DAG: DBG_VALUE_LIST !{{[0-9]+}}, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 0, 32), ${{[a-z]+}}, debug-location
+; CHECK-DAG: DBG_VALUE_LIST !{{[0-9]+}}, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 32, 32), ${{[a-z]+}}, debug-location
 
 ; ModuleID = 'sdagsplit-1.c'
 target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
 target triple = "i386"
 
 ; Function Attrs: nounwind readnone
 define i64 @foo(i64 %a, i64 %b) local_unnamed_addr #0 !dbg !8 {
 entry:

llvm/test/DebugInfo/X86/spill-nospill.ll

 ;   g(y);
 ;   g(y);
 ;   return x + y;
 ; }
 
 ; CHECK-LABEL: f: # @f
 ; CHECK: callq   g
 ; CHECK: movl    %eax, [[X_OFFS:[0-9]+]](%rsp)          # 4-byte Spill
-; CHECK: #DEBUG_VALUE: f:x <- [DW_OP_plus_uconst [[X_OFFS]]] [$rsp+0]
+; CHECK: #DEBUG_VALUE: f:x <- [DW_OP_plus_uconst [[X_OFFS]], DW_OP_deref] $rsp
 ; CHECK: #APP
 ; CHECK: #NO_APP
 ; CHECK: callq   g
 ; CHECK: movl    %eax, %[[CSR:[^ ]*]]
 ; CHECK: #DEBUG_VALUE: f:y <- $esi
 ; CHECK: movl    %eax, %ecx
 ; CHECK: callq   g
 ; CHECK: movl    %[[CSR]], %ecx

llvm/test/DebugInfo/assignment-tracking/X86/loop-sink.ll

 
 ; CHECK-DAG: ![[A:[0-9]+]] = !DILocalVariable(name: "a",
 
 ; CHECK-LABEL: bb.0.entry:
 ; CHECK: DBG_VALUE $edi, $noreg, ![[A]], !DIExpression()
 ; CHECK: CALL64pcrel32 @getInt{{.*}}debug-instr-number 1
 
 ; CHECK-LABEL: bb.2.while.body:
-; CHECK: DBG_INSTR_REF ![[A]], !DIExpression(), dbg-instr-ref(1, 6)
+; CHECK: DBG_INSTR_REF ![[A]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 6)
 
 ; CHECK-LABEL: bb.3.while.end:
 ; CHECK: MOV32mr %stack.0.a.addr, 1, $noreg, 0, $noreg, %1
 ; CHECK-NEXT: DBG_VALUE %stack.0.a.addr, $noreg, ![[A]], !DIExpression(DW_OP_deref)
 
 target triple = "x86_64-unknown-linux-gnu"
 
 @g = dso_local local_unnamed_addr global ptr null, align 8, !dbg !0

llvm/test/DebugInfo/assignment-tracking/X86/lower-to-value.ll

 ; CHECK-NEXT: DBG_VALUE %stack.0.X, $noreg, ![[VAR]], !DIExpression(DW_OP_deref, DW_OP_LLVM_fragment, 0, 64)
 ; CHECK-NEXT: DBG_VALUE %stack.0.X, $noreg, ![[VAR]], !DIExpression(DW_OP_plus_uconst, 8, DW_OP_deref, DW_OP_LLVM_fragment, 64, 64), debug-location
 
 ;; The final assignment (X.B += 2) doesn't get stored back to the alloca. This
 ;; means that that the stack location isn't valid for the entire lifetime of X.
 ; DBGVALUE: %2:gr64 = nsw ADD64ri8 %1, 2, implicit-def dead $eflags, debug-location
 ; DBGVALUE-NEXT: DBG_VALUE %2, $noreg, ![[VAR]], !DIExpression(DW_OP_LLVM_fragment, 64, 64), debug-location
 ; INSTRREF: %2:gr64 = nsw ADD64ri8 %1, 2, implicit-def dead $eflags, debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[VAR]], !DIExpression(DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(1, 0), debug-location
+; INSTRREF-NEXT: DBG_INSTR_REF ![[VAR]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_fragment, 64, 64), dbg-instr-ref(1, 0), debug-location
 
 source_filename = "test.cpp"
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 %struct.Ex = type { i64, i64 }
 
 define dso_local i64 @_Z3funv() local_unnamed_addr !dbg !7 {

llvm/test/DebugInfo/assignment-tracking/X86/remove-undef-fragment.ll

 ;; The test
 ;; --------
 ;; We expect to see two DBG instructions, one for each non-undef fragment. We
 ;; don't bother checking the operands because it doesn't matter if either of
 ;; these have become undef as a result of SelectionDAG dropping the values
 ;; (which happens to be the case here). It's just important that SelectionDAG
 ;; was fed these fragments.
 
-; CHECK: DBG{{.*}}DIExpression(DW_OP_LLVM_fragment, 0, 32)
-; CHECK: DBG{{.*}}DIExpression(DW_OP_LLVM_fragment, 64, 32)
+; CHECK: DBG{{.*}}DIExpression({{(DW_OP_LLVM_arg, 0, )?}}DW_OP_LLVM_fragment, 0, 32)
+; CHECK: DBG{{.*}}DIExpression({{(DW_OP_LLVM_arg, 0, )?}}DW_OP_LLVM_fragment, 64, 32)
 
 ;; Source
 ;; ------
 ;; IR llvm-reduced from optimized IR generated from, itself reduced from
 ;; CTMark's bullet source file btScaledBvhTriangleMeshShape.cpp:
 ;; class a {
 ;; public:
 ;;   float b[4];

llvm/test/DebugInfo/assignment-tracking/X86/sdag-dangling-dbgassign.ll

 @S = global %struct.SS { i32 23, i32 -17 }, align 4, !dbg !0
 
 ; Verify that the def comes before the for foo1.
 define i32 @test1() local_unnamed_addr #0 !dbg !17 {
 ; CHECK-LABEL: bb.0.entry1
 ; CHECK-NEXT:    DBG_VALUE 0, $noreg, ![[BAR1]], !DIExpression()
 ; CHECK-NEXT:    [[REG1:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT:  DBG_INSTR_REF ![[FOO1]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT:  DBG_INSTR_REF ![[FOO1]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT:  DBG_VALUE [[REG1]], $noreg, ![[FOO1]], !DIExpression()
 entry1:
   call void @llvm.dbg.assign(metadata ptr @S, metadata !20, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !23
   call void @llvm.dbg.assign(metadata ptr null, metadata !22, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !24
   ret i32 ptrtoint (ptr @S to i32), !dbg !25
 }
 
 ; Verify that the def comes before the for foo2 and bar2.
 define i32 @test2() local_unnamed_addr #0 !dbg !26 {
 ; CHECK-LABEL: bb.0.entry2
 ; CHECK-NEXT:    [[REG2:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[FOO2]], !DIExpression(), dbg-instr-ref(1, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR2]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[FOO2]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR2]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG2]], $noreg, ![[FOO2]], !DIExpression
 ; DBGVALUE-NEXT: DBG_VALUE [[REG2]], $noreg, ![[BAR2]], !DIExpression
 entry2:
   call void @llvm.dbg.assign(metadata ptr @S, metadata !28, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !30
   call void @llvm.dbg.assign(metadata ptr @S, metadata !29, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !31
   ret i32 add (i32 ptrtoint (ptr @S to i32), i32 ptrtoint (ptr @S to i32)), !dbg !32
 }
 
 ; Verify that the def comes before the for foo3 and bar3.
 define i32 @test3() local_unnamed_addr #0 !dbg !33 {
 ; CHECK-LABEL: bb.0.entry3
 ; CHECK-NEXT:    [[REG3:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR3]], !DIExpression(), dbg-instr-ref(1, 0)
-; INSTRREF-NEXT: DBG_INSTR_REF ![[FOO3]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR3]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[FOO3]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG3]], $noreg, ![[BAR3]], !DIExpression()
 ; DBGVALUE-NEXT: DBG_VALUE [[REG3]], $noreg, ![[FOO3]], !DIExpression()
 entry3:
   call void @llvm.dbg.assign(metadata ptr @S, metadata !36, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !38
   call void @llvm.dbg.assign(metadata ptr @S, metadata !35, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !37
   ret i32 add (i32 ptrtoint (ptr @S to i32), i32 ptrtoint (ptr @S to i32)), !dbg !39
 }
 
 ; Verify that the def comes before the for bar4.
 define i32 @test4() local_unnamed_addr #0 !dbg !40 {
 ; CHECK-LABEL: bb.0.entry4
 ;; NOTE: The check for `DBG_VALUE $noreg, $noreg, ![[FOO4]], !DIExpression()`
 ;; has been removed because AT lowering removes redundant debug intrinsics.
 ; CHECK-NEXT:    DBG_VALUE 0, $noreg, ![[FOO4]], !DIExpression()
 ; CHECK-NEXT:    [[REG4:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR4]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR4]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG4]], $noreg, ![[BAR4]], !DIExpression()
 entry4:
   call void @llvm.dbg.assign(metadata ptr @S, metadata !42, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !44
   call void @llvm.dbg.assign(metadata ptr @S, metadata !43, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !45
   call void @llvm.dbg.assign(metadata ptr null, metadata !42, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !44
   ret i32 ptrtoint (ptr @S to i32), !dbg !46
 }
 
 ; Verify that we do not get a DBG_VALUE that maps foo5 to @S here.
 define i32 @test5() local_unnamed_addr #0 !dbg !47 {
 ; CHECK-LABEL: bb.0.entry5:
 ; cHECK-NEXT:    DBG_VALUE $noreg, $noreg, ![[FOO5]], !DIExpression()
 ; CHECK-NEXT:    DBG_VALUE 0, $noreg, ![[FOO5]], !DIExpression()
 ; CHECK-NEXT:    [[REG5:%[0-9]+]]:gr64 = LEA64r
 ; INSTRREF-SAME:    debug-instr-number 1
-; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR5]], !DIExpression(), dbg-instr-ref(1, 0)
+; INSTRREF-NEXT: DBG_INSTR_REF ![[BAR5]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 ; DBGVALUE-NEXT: DBG_VALUE [[REG5]], $noreg, ![[BAR5]], !DIExpression()
 ; CHECK-NOT:     DBG_{{.*}} ![[FOO5]], !DIExpression()
 ; CHECK:         RET
 entry5:
   call void @llvm.dbg.assign(metadata ptr @S, metadata !49, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !51
   call void @llvm.dbg.assign(metadata ptr @S, metadata !50, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !52
   call void @llvm.dbg.assign(metadata ptr null, metadata !50, metadata !DIExpression(), metadata !54, metadata ptr undef, metadata !DIExpression()), !dbg !52
   ret i32 ptrtoint (ptr @S to i32), !dbg !53

llvm/unittests/IR/MetadataTest.cpp

#define EXPECT_VALID(...)                                                      \
   } while (false)
 #define EXPECT_INVALID(...)                                                    \
   do {                                                                         \
     uint64_t Elements[] = {__VA_ARGS__};                                       \
     EXPECT_FALSE(DIExpression::get(Context, Elements)->isValid());             \
   } while (false)
 
   // Empty expression should be valid.
-  EXPECT_TRUE(DIExpression::get(Context, std::nullopt));
+  EXPECT_TRUE(DIExpression::get(Context, std::nullopt)->isValid());
 
   // Valid constructions.
   EXPECT_VALID(dwarf::DW_OP_plus_uconst, 6);
   EXPECT_VALID(dwarf::DW_OP_constu, 6, dwarf::DW_OP_plus);
   EXPECT_VALID(dwarf::DW_OP_deref);
   EXPECT_VALID(dwarf::DW_OP_LLVM_fragment, 3, 7);
   EXPECT_VALID(dwarf::DW_OP_plus_uconst, 6, dwarf::DW_OP_deref);
   EXPECT_VALID(dwarf::DW_OP_deref, dwarf::DW_OP_plus_uconst, 6);
   EXPECT_VALID(dwarf::DW_OP_deref, dwarf::DW_OP_LLVM_fragment, 3, 7);
   EXPECT_VALID(dwarf::DW_OP_deref, dwarf::DW_OP_plus_uconst, 6,
                dwarf::DW_OP_LLVM_fragment, 3, 7);
+  EXPECT_VALID(dwarf::DW_OP_LLVM_entry_value, 1);
+  EXPECT_VALID(dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_LLVM_entry_value, 1);
 
   // Invalid constructions.
   EXPECT_INVALID(~0u);
   EXPECT_INVALID(dwarf::DW_OP_plus, 0);
   EXPECT_INVALID(dwarf::DW_OP_plus_uconst);
   EXPECT_INVALID(dwarf::DW_OP_LLVM_fragment);
   EXPECT_INVALID(dwarf::DW_OP_LLVM_fragment, 3);
   EXPECT_INVALID(dwarf::DW_OP_LLVM_fragment, 3, 7, dwarf::DW_OP_plus_uconst, 3);
   EXPECT_INVALID(dwarf::DW_OP_LLVM_fragment, 3, 7, dwarf::DW_OP_deref);
+  EXPECT_INVALID(dwarf::DW_OP_LLVM_entry_value, 2);
+  EXPECT_INVALID(dwarf::DW_OP_plus_uconst, 5, dwarf::DW_OP_LLVM_entry_value, 1);
+  EXPECT_INVALID(dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_plus_uconst, 5,
+                 dwarf::DW_OP_LLVM_entry_value, 1);
+  EXPECT_INVALID(dwarf::DW_OP_LLVM_arg, 1, dwarf::DW_OP_LLVM_entry_value, 1);
 
 #undef EXPECT_VALID
 #undef EXPECT_INVALID
 }
 
 TEST_F(DIExpressionTest, createFragmentExpression) {
 #define EXPECT_VALID_FRAGMENT(Offset, Size, ...)                               \
   do {                                                                         \
#define EXPECT_INVALID_FRAGMENT(Offset, Size, ...)                             \
   // deref in the expression).
   EXPECT_INVALID_FRAGMENT(0, 32, dwarf::DW_OP_deref, dwarf::DW_OP_plus_uconst,
                           2, dwarf::DW_OP_stack_value);
 
 #undef EXPECT_VALID_FRAGMENT
 #undef EXPECT_INVALID_FRAGMENT
 }
 
+TEST_F(DIExpressionTest, convertToVariadicExpression) {
+#define EXPECT_CONVERT_IS_NOOP(TestExpr)                                       \
+  do {                                                                         \
+    const DIExpression *Variadic =                                             \
+        DIExpression::convertToVariadicExpression(TestExpr);                   \
+    EXPECT_EQ(Variadic, TestExpr);                                             \
+  } while (false)
+#define EXPECT_VARIADIC_OPS_EQUAL(TestExpr, Expected)                          \
+  do {                                                                         \
+    const DIExpression *Variadic =                                             \
+        DIExpression::convertToVariadicExpression(TestExpr);                   \
+    EXPECT_EQ(Variadic, Expected);                                             \
+  } while (false)
+#define GET_EXPR(...) DIExpression::get(Context, {__VA_ARGS__})
+
+  // Expressions which are already variadic should be unaffected.
+  EXPECT_CONVERT_IS_NOOP(
+      GET_EXPR(dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_stack_value));
+  EXPECT_CONVERT_IS_NOOP(GET_EXPR(dwarf::DW_OP_LLVM_arg, 0,
+                                  dwarf::DW_OP_LLVM_arg, 1, dwarf::DW_OP_plus,
+                                  dwarf::DW_OP_stack_value));
+  EXPECT_CONVERT_IS_NOOP(GET_EXPR(dwarf::DW_OP_constu, 5, dwarf::DW_OP_LLVM_arg,
+                                  0, dwarf::DW_OP_plus,
+                                  dwarf::DW_OP_stack_value));
+  EXPECT_CONVERT_IS_NOOP(GET_EXPR(dwarf::DW_OP_LLVM_arg, 0,
+                                  dwarf::DW_OP_stack_value,
+                                  dwarf::DW_OP_LLVM_fragment, 0, 32));
+
+  // Other expressions should receive a leading `LLVM_arg 0`.
+  EXPECT_VARIADIC_OPS_EQUAL(GET_EXPR(), GET_EXPR(dwarf::DW_OP_LLVM_arg, 0));
+  EXPECT_VARIADIC_OPS_EQUAL(
+      GET_EXPR(dwarf::DW_OP_plus_uconst, 4),
+      GET_EXPR(dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_plus_uconst, 4));
+  EXPECT_VARIADIC_OPS_EQUAL(
+      GET_EXPR(dwarf::DW_OP_plus_uconst, 4, dwarf::DW_OP_stack_value),
+      GET_EXPR(dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_plus_uconst, 4,
+               dwarf::DW_OP_stack_value));
+  EXPECT_VARIADIC_OPS_EQUAL(
+      GET_EXPR(dwarf::DW_OP_plus_uconst, 6, dwarf::DW_OP_stack_value,
+               dwarf::DW_OP_LLVM_fragment, 32, 32),
+      GET_EXPR(dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_plus_uconst, 6,
+               dwarf::DW_OP_stack_value, dwarf::DW_OP_LLVM_fragment, 32, 32));
+  EXPECT_VARIADIC_OPS_EQUAL(GET_EXPR(dwarf::DW_OP_plus_uconst, 14,
+                                     dwarf::DW_OP_LLVM_fragment, 32, 32),
+                            GET_EXPR(dwarf::DW_OP_LLVM_arg, 0,
+                                     dwarf::DW_OP_plus_uconst, 14,
+                                     dwarf::DW_OP_LLVM_fragment, 32, 32));
+
+#undef EXPECT_CONVERT_IS_NOOP
+#undef EXPECT_VARIADIC_OPS_EQUAL
+#undef GET_EXPR
+}
+
 TEST_F(DIExpressionTest, replaceArg) {
 #define EXPECT_REPLACE_ARG_EQ(Expr, OldArg, NewArg, ...)                       \
   do {                                                                         \
     uint64_t Elements[] = {__VA_ARGS__};                                       \
     ArrayRef<uint64_t> Expected = Elements;                                    \
     DIExpression *Expression = DIExpression::replaceArg(Expr, OldArg, NewArg); \
     EXPECT_EQ(Expression->getElements(), Expected);                            \
   } while (false)