[RemoveDIs] Handle DPValues in FastISel (#76952)

The change is fairly mechanical:
1. Factor code from `FastISel::selectIntrinsicCall`, which converts
debug intrinsics into debug instructions, into functions (NFC).
2. Call those functions for DPValues attached to instructions too.

The test updates look the same as other RemoveDIs changes: re-run the
tests with `--try-experimental-debuginfo-iterators`, which checks the
output is identical using the new debug info format (if it has been
enabled in the cmake configuration).

Depends on #76941 (otherwise some modified tests spuriously fail).

74 files changed, 398 insertions, 151 deletions

diff --git a/llvm/include/llvm/CodeGen/FastISel.h b/llvm/include/llvm/CodeGen/FastISel.h
index dc2931b40d35..0f17e51f0b7a 100644
--- a/llvm/include/llvm/CodeGen/FastISel.h
+++ b/llvm/include/llvm/CodeGen/FastISel.h
@@ -319,6 +319,10 @@ public:
   /// Reset InsertPt to the given old insert position.
   void leaveLocalValueArea(SavePoint Old);
 
+  /// Target-independent lowering of non-instruction debug info associated with
+  /// this instruction.
+  void handleDbgInfo(const Instruction *II);
+
 protected:
   explicit FastISel(FunctionLoweringInfo &FuncInfo,
                     const TargetLibraryInfo *LibInfo,
@@ -518,6 +522,16 @@ protected:
     return MF->getFunction().hasOptSize();
   }
 
+  /// Target-independent lowering of debug information. Returns false if the
+  /// debug information couldn't be lowered and was instead discarded.
+  virtual bool lowerDbgValue(const Value *V, DIExpression *Expr,
+                             DILocalVariable *Var, const DebugLoc &DL);
+
+  /// Target-independent lowering of debug information. Returns false if the
+  /// debug information couldn't be lowered and was instead discarded.
+  virtual bool lowerDbgDeclare(const Value *V, DIExpression *Expr,
+                               DILocalVariable *Var, const DebugLoc &DL);
+
 private:
   /// Handle PHI nodes in successor blocks.
   ///
diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index 09e260394262..6d80b282a1ed 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -1180,6 +1180,184 @@ bool FastISel::selectCall(const User *I) {
   return lowerCall(Call);
 }
 
+void FastISel::handleDbgInfo(const Instruction *II) {
+  if (!II->hasDbgValues())
+    return;
+
+  // Clear any metadata.
+  MIMD = MIMetadata();
+
+  // Reverse order of debug records, because fast-isel walks through backwards.
+  for (DPValue &DPV : llvm::reverse(II->getDbgValueRange())) {
+    flushLocalValueMap();
+    recomputeInsertPt();
+
+    Value *V = nullptr;
+    if (!DPV.hasArgList())
+      V = DPV.getVariableLocationOp(0);
+
+    bool Res = false;
+    if (DPV.getType() == DPValue::LocationType::Value) {
+      Res = lowerDbgValue(V, DPV.getExpression(), DPV.getVariable(),
+                          DPV.getDebugLoc());
+    } else {
+      assert(DPV.getType() == DPValue::LocationType::Declare);
+      if (FuncInfo.PreprocessedDPVDeclares.contains(&DPV))
+        continue;
+      Res = lowerDbgDeclare(V, DPV.getExpression(), DPV.getVariable(),
+                            DPV.getDebugLoc());
+    }
+
+    if (!Res)
+      LLVM_DEBUG(dbgs() << "Dropping debug-info for " << DPV << "\n";);
+  }
+}
+
+bool FastISel::lowerDbgValue(const Value *V, DIExpression *Expr,
+                             DILocalVariable *Var, const DebugLoc &DL) {
+  // This form of DBG_VALUE is target-independent.
+  const MCInstrDesc &II = TII.get(TargetOpcode::DBG_VALUE);
+  if (!V || isa<UndefValue>(V)) {
+    // DI is either undef or cannot produce a valid DBG_VALUE, so produce an
+    // undef DBG_VALUE to terminate any prior location.
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, false, 0U, Var, Expr);
+    return true;
+  }
+  if (const auto *CI = dyn_cast<ConstantInt>(V)) {
+    // See if there's an expression to constant-fold.
+    if (Expr)
+      std::tie(Expr, CI) = Expr->constantFold(CI);
+    if (CI->getBitWidth() > 64)
+      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
+          .addCImm(CI)
+          .addImm(0U)
+          .addMetadata(Var)
+          .addMetadata(Expr);
+    else
+      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
+          .addImm(CI->getZExtValue())
+          .addImm(0U)
+          .addMetadata(Var)
+          .addMetadata(Expr);
+    return true;
+  }
+  if (const auto *CF = dyn_cast<ConstantFP>(V)) {
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II)
+        .addFPImm(CF)
+        .addImm(0U)
+        .addMetadata(Var)
+        .addMetadata(Expr);
+    return true;
+  }
+  if (const auto *Arg = dyn_cast<Argument>(V);
+      Arg && Expr && Expr->isEntryValue()) {
+    // As per the Verifier, this case is only valid for swift async Args.
+    assert(Arg->hasAttribute(Attribute::AttrKind::SwiftAsync));
+
+    Register Reg = getRegForValue(Arg);
+    for (auto [PhysReg, VirtReg] : FuncInfo.RegInfo->liveins())
+      if (Reg == VirtReg || Reg == PhysReg) {
+        BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, false /*IsIndirect*/,
+                PhysReg, Var, Expr);
+        return true;
+      }
+
+    LLVM_DEBUG(dbgs() << "Dropping dbg.value: expression is entry_value but "
+                         "couldn't find a physical register\n");
+    return false;
+  }
+  if (auto SI = FuncInfo.StaticAllocaMap.find(dyn_cast<AllocaInst>(V));
+      SI != FuncInfo.StaticAllocaMap.end()) {
+    MachineOperand FrameIndexOp = MachineOperand::CreateFI(SI->second);
+    bool IsIndirect = false;
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, IsIndirect, FrameIndexOp,
+            Var, Expr);
+    return true;
+  }
+  if (Register Reg = lookUpRegForValue(V)) {
+    // FIXME: This does not handle register-indirect values at offset 0.
+    if (!FuncInfo.MF->useDebugInstrRef()) {
+      bool IsIndirect = false;
+      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, II, IsIndirect, Reg, Var,
+              Expr);
+      return true;
+    }
+    // If using instruction referencing, produce this as a DBG_INSTR_REF,
+    // to be later patched up by finalizeDebugInstrRefs.
+    SmallVector<MachineOperand, 1> MOs({MachineOperand::CreateReg(
+        /* Reg */ Reg, /* isDef */ false, /* isImp */ false,
+        /* isKill */ false, /* isDead */ false,
+        /* isUndef */ false, /* isEarlyClobber */ false,
+        /* SubReg */ 0, /* isDebug */ true)});
+    SmallVector<uint64_t, 2> Ops({dwarf::DW_OP_LLVM_arg, 0});
+    auto *NewExpr = DIExpression::prependOpcodes(Expr, Ops);
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+            TII.get(TargetOpcode::DBG_INSTR_REF), /*IsIndirect*/ false, MOs,
+            Var, NewExpr);
+    return true;
+  }
+  return false;
+}
+
+bool FastISel::lowerDbgDeclare(const Value *Address, DIExpression *Expr,
+                               DILocalVariable *Var, const DebugLoc &DL) {
+  if (!Address || isa<UndefValue>(Address)) {
+    LLVM_DEBUG(dbgs() << "Dropping debug info (bad/undef address)\n");
+    return false;
+  }
+
+  std::optional<MachineOperand> Op;
+  if (Register Reg = lookUpRegForValue(Address))
+    Op = MachineOperand::CreateReg(Reg, false);
+
+  // If we have a VLA that has a "use" in a metadata node that's then used
+  // here but it has no other uses, then we have a problem. E.g.,
+  //
+  //   int foo (const int *x) {
+  //     char a[*x];
+  //     return 0;
+  //   }
+  //
+  // If we assign 'a' a vreg and fast isel later on has to use the selection
+  // DAG isel, it will want to copy the value to the vreg. However, there are
+  // no uses, which goes counter to what selection DAG isel expects.
+  if (!Op && !Address->use_empty() && isa<Instruction>(Address) &&
+      (!isa<AllocaInst>(Address) ||
+       !FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(Address))))
+    Op = MachineOperand::CreateReg(FuncInfo.InitializeRegForValue(Address),
+                                   false);
+
+  if (Op) {
+    assert(Var->isValidLocationForIntrinsic(DL) &&
+           "Expected inlined-at fields to agree");
+    if (FuncInfo.MF->useDebugInstrRef() && Op->isReg()) {
+      // If using instruction referencing, produce this as a DBG_INSTR_REF,
+      // to be later patched up by finalizeDebugInstrRefs. Tack a deref onto
+      // the expression, we don't have an "indirect" flag in DBG_INSTR_REF.
+      SmallVector<uint64_t, 3> Ops(
+          {dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_deref});
+      auto *NewExpr = DIExpression::prependOpcodes(Expr, Ops);
+      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+              TII.get(TargetOpcode::DBG_INSTR_REF), /*IsIndirect*/ false, *Op,
+              Var, NewExpr);
+      return true;
+    }
+
+    // A dbg.declare describes the address of a source variable, so lower it
+    // into an indirect DBG_VALUE.
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+            TII.get(TargetOpcode::DBG_VALUE), /*IsIndirect*/ true, *Op, Var,
+            Expr);
+    return true;
+  }
+
+  // We can't yet handle anything else here because it would require
+  // generating code, thus altering codegen because of debug info.
+  LLVM_DEBUG(
+      dbgs() << "Dropping debug info (no materialized reg for address)\n");
+  return false;
+}
+
 bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
   switch (II->getIntrinsicID()) {
   default:
@@ -1209,153 +1387,28 @@ bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
       return true;
 
     const Value *Address = DI->getAddress();
-    if (!Address || isa<UndefValue>(Address)) {
-      LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI
-                        << " (bad/undef address)\n");
-      return true;
-    }
+    if (!lowerDbgDeclare(Address, DI->getExpression(), DI->getVariable(),
+                         MIMD.getDL()))
+      LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI);
 
-    std::optional<MachineOperand> Op;
-    if (Register Reg = lookUpRegForValue(Address))
-      Op = MachineOperand::CreateReg(Reg, false);
-
-    // If we have a VLA that has a "use" in a metadata node that's then used
-    // here but it has no other uses, then we have a problem. E.g.,
-    //
-    //   int foo (const int *x) {
-    //     char a[*x];
-    //     return 0;
-    //   }
-    //
-    // If we assign 'a' a vreg and fast isel later on has to use the selection
-    // DAG isel, it will want to copy the value to the vreg. However, there are
-    // no uses, which goes counter to what selection DAG isel expects.
-    if (!Op && !Address->use_empty() && isa<Instruction>(Address) &&
-        (!isa<AllocaInst>(Address) ||
-         !FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(Address))))
-      Op = MachineOperand::CreateReg(FuncInfo.InitializeRegForValue(Address),
-                                     false);
-
-    if (Op) {
-      assert(DI->getVariable()->isValidLocationForIntrinsic(MIMD.getDL()) &&
-             "Expected inlined-at fields to agree");
-      if (FuncInfo.MF->useDebugInstrRef() && Op->isReg()) {
-        // If using instruction referencing, produce this as a DBG_INSTR_REF,
-        // to be later patched up by finalizeDebugInstrRefs. Tack a deref onto
-        // the expression, we don't have an "indirect" flag in DBG_INSTR_REF.
-        SmallVector<uint64_t, 3> Ops(
-            {dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_deref});
-        auto *NewExpr = DIExpression::prependOpcodes(DI->getExpression(), Ops);
-        BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(),
-                TII.get(TargetOpcode::DBG_INSTR_REF), /*IsIndirect*/ false, *Op,
-                DI->getVariable(), NewExpr);
-      } else {
-        // A dbg.declare describes the address of a source variable, so lower it
-        // into an indirect DBG_VALUE.
-        BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(),
-                TII.get(TargetOpcode::DBG_VALUE), /*IsIndirect*/ true, *Op,
-                DI->getVariable(), DI->getExpression());
-      }
-    } else {
-      // We can't yet handle anything else here because it would require
-      // generating code, thus altering codegen because of debug info.
-      LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI
-                        << " (no materialized reg for address)\n");
-    }
     return true;
   }
   case Intrinsic::dbg_value: {
     // This form of DBG_VALUE is target-independent.
     const DbgValueInst *DI = cast<DbgValueInst>(II);
-    const MCInstrDesc &II = TII.get(TargetOpcode::DBG_VALUE);
     const Value *V = DI->getValue();
     DIExpression *Expr = DI->getExpression();
     DILocalVariable *Var = DI->getVariable();
+    if (DI->hasArgList())
+      // Signal that we don't have a location for this.
+      V = nullptr;
+
     assert(Var->isValidLocationForIntrinsic(MIMD.getDL()) &&
            "Expected inlined-at fields to agree");
-    if (!V || isa<UndefValue>(V) || DI->hasArgList()) {
-      // DI is either undef or cannot produce a valid DBG_VALUE, so produce an
-      // undef DBG_VALUE to terminate any prior location.
-      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(), II, false, 0U,
-              Var, Expr);
-      return true;
-    }
-    if (const auto *CI = dyn_cast<ConstantInt>(V)) {
-      // See if there's an expression to constant-fold.
-      if (Expr)
-        std::tie(Expr, CI) = Expr->constantFold(CI);
-      if (CI->getBitWidth() > 64)
-        BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD, II)
-            .addCImm(CI)
-            .addImm(0U)
-            .addMetadata(Var)
-            .addMetadata(Expr);
-      else
-        BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD, II)
-            .addImm(CI->getZExtValue())
-            .addImm(0U)
-            .addMetadata(Var)
-            .addMetadata(Expr);
-      return true;
-    }
-    if (const auto *CF = dyn_cast<ConstantFP>(V)) {
-      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD, II)
-          .addFPImm(CF)
-          .addImm(0U)
-          .addMetadata(Var)
-          .addMetadata(Expr);
-      return true;
-    }
-    if (const auto *Arg = dyn_cast<Argument>(V);
-        Arg && Expr && Expr->isEntryValue()) {
-      // As per the Verifier, this case is only valid for swift async Args.
-      assert(Arg->hasAttribute(Attribute::AttrKind::SwiftAsync));
-
-      Register Reg = getRegForValue(Arg);
-      for (auto [PhysReg, VirtReg] : FuncInfo.RegInfo->liveins())
-        if (Reg == VirtReg || Reg == PhysReg) {
-          BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(), II,
-                  false /*IsIndirect*/, PhysReg, Var, Expr);
-          return true;
-        }
 
-      LLVM_DEBUG(dbgs() << "Dropping dbg.value: expression is entry_value but "
-                           "couldn't find a physical register\n"
-                        << *DI << "\n");
-      return true;
-    }
-    if (auto SI = FuncInfo.StaticAllocaMap.find(dyn_cast<AllocaInst>(V));
-        SI != FuncInfo.StaticAllocaMap.end()) {
-      MachineOperand FrameIndexOp = MachineOperand::CreateFI(SI->second);
-      bool IsIndirect = false;
-      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(), II, IsIndirect,
-              FrameIndexOp, Var, Expr);
-      return true;
-    }
-    if (Register Reg = lookUpRegForValue(V)) {
-      // FIXME: This does not handle register-indirect values at offset 0.
-      if (!FuncInfo.MF->useDebugInstrRef()) {
-        bool IsIndirect = false;
-        BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(), II, IsIndirect,
-                Reg, Var, Expr);
-        return true;
-      }
-      // If using instruction referencing, produce this as a DBG_INSTR_REF,
-      // to be later patched up by finalizeDebugInstrRefs.
-      SmallVector<MachineOperand, 1> MOs({MachineOperand::CreateReg(
-          /* Reg */ Reg, /* isDef */ false, /* isImp */ false,
-          /* isKill */ false, /* isDead */ false,
-          /* isUndef */ false, /* isEarlyClobber */ false,
-          /* SubReg */ 0, /* isDebug */ true)});
-      SmallVector<uint64_t, 2> Ops({dwarf::DW_OP_LLVM_arg, 0});
-      auto *NewExpr = DIExpression::prependOpcodes(Expr, Ops);
-      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, MIMD.getDL(),
-              TII.get(TargetOpcode::DBG_INSTR_REF), /*IsIndirect*/ false, MOs,
-              Var, NewExpr);
-      return true;
-    }
-    // We don't know how to handle other cases, so we drop.
-    LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
+    if (!lowerDbgValue(V, Expr, Var, MIMD.getDL()))
+      LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
+
     return true;
   }
   case Intrinsic::dbg_label: {
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index f28211ac113c..99bb3d875d4f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -1614,6 +1614,7 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
         if (isFoldedOrDeadInstruction(Inst, *FuncInfo) ||
             ElidedArgCopyInstrs.count(Inst)) {
           --NumFastIselRemaining;
+          FastIS->handleDbgInfo(Inst);
           continue;
         }
 
@@ -1625,6 +1626,8 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
         if (FastIS->selectInstruction(Inst)) {
           --NumFastIselRemaining;
           ++NumFastIselSuccess;
+
+          FastIS->handleDbgInfo(Inst);
           // If fast isel succeeded, skip over all the folded instructions, and
           // then see if there is a load right before the selected instructions.
           // Try to fold the load if so.
@@ -1640,6 +1643,7 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
             // If we succeeded, don't re-select the load.
             LLVM_DEBUG(dbgs()
                        << "FastISel folded load: " << *BeforeInst << "\n");
+            FastIS->handleDbgInfo(BeforeInst);
             BI = std::next(BasicBlock::const_iterator(BeforeInst));
             --NumFastIselRemaining;
             ++NumFastIselSuccess;
diff --git a/llvm/test/CodeGen/AArch64/fast-isel-branch-uncond-debug.ll b/llvm/test/CodeGen/AArch64/fast-isel-branch-uncond-debug.ll
index 1d213945966a..e1614d322b93 100644
--- a/llvm/test/CodeGen/AArch64/fast-isel-branch-uncond-debug.ll
+++ b/llvm/test/CodeGen/AArch64/fast-isel-branch-uncond-debug.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -mtriple=aarch64 -O1 -opt-bisect-limit=2 -o - %s  2> /dev/null | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=aarch64 -O1 -opt-bisect-limit=2 -o - %s  2> /dev/null | FileCheck %s
 
 define dso_local i32 @a() #0 !dbg !7 {
 entry:
@@ -41,4 +42,4 @@ declare void @llvm.dbg.value(metadata, metadata, metadata) #2
 !18 = distinct !{!18, !19, !20}
 !19 = !DILocation(line: 3, column: 3, scope: !17)
 !20 = !DILocation(line: 4, column: 5, scope: !17)
- 
\ No newline at end of file
+
diff --git a/llvm/test/CodeGen/AArch64/fast-isel-dbg.ll b/llvm/test/CodeGen/AArch64/fast-isel-dbg.ll
index 602d454044d4..0c1a693089cb 100644
--- a/llvm/test/CodeGen/AArch64/fast-isel-dbg.ll
+++ b/llvm/test/CodeGen/AArch64/fast-isel-dbg.ll
@@ -1,4 +1,6 @@
 ; RUN: llc -o - %s -fast-isel -stop-before=finalize-isel | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -o - %s -fast-isel -stop-before=finalize-isel | FileCheck %s
+
 ; Make sure fast-isel produces DBG_VALUE instructions even if no debug printer
 ; is scheduled because of -stop-before.
 target triple="aarch64--"
diff --git a/llvm/test/CodeGen/AArch64/fastisel-debugvalue-undef.ll b/llvm/test/CodeGen/AArch64/fastisel-debugvalue-undef.ll
index cccede6a5045..c30a01baedaf 100644
--- a/llvm/test/CodeGen/AArch64/fastisel-debugvalue-undef.ll
+++ b/llvm/test/CodeGen/AArch64/fastisel-debugvalue-undef.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -O0 -fast-isel=1 -o - -print-after="finalize-isel" %s 2>&1 | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -fast-isel=1 -o - -print-after="finalize-isel" %s 2>&1 | FileCheck %s
 
 ; Check that we emit a DBG_VALUE for the `@llvm.dbg.value` which has `undef` has first arg.
 
diff --git a/llvm/test/CodeGen/ARM/debug-info-blocks.ll b/llvm/test/CodeGen/ARM/debug-info-blocks.ll
index 1c9ffb1775aa..8ef341faed6b 100644
--- a/llvm/test/CodeGen/ARM/debug-info-blocks.ll
+++ b/llvm/test/CodeGen/ARM/debug-info-blocks.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -filetype=obj -O0 < %s | llvm-dwarfdump -v - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -filetype=obj -O0 < %s | llvm-dwarfdump -v - | FileCheck %s
 
 ; debug_info content
 ; CHECK: DW_AT_name {{.*}} "foobar_func_block_invoke_0"
diff --git a/llvm/test/CodeGen/Generic/csw-debug-assert.ll b/llvm/test/CodeGen/Generic/csw-debug-assert.ll
index 084cbfa79679..85a8d8bb1d98 100644
--- a/llvm/test/CodeGen/Generic/csw-debug-assert.ll
+++ b/llvm/test/CodeGen/Generic/csw-debug-assert.ll
@@ -2,6 +2,7 @@
 ; REQUIRES: asserts
 ; REQUIRES: x86_64-linux
 ; RUN: llc -O1 -regalloc=pbqp < %s | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -O1 -regalloc=pbqp < %s | FileCheck %s
 
 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"
diff --git a/llvm/test/CodeGen/X86/2010-08-04-StackVariable.ll b/llvm/test/CodeGen/X86/2010-08-04-StackVariable.ll
index 198c0d4806c5..e95b3b4884b4 100644
--- a/llvm/test/CodeGen/X86/2010-08-04-StackVariable.ll
+++ b/llvm/test/CodeGen/X86/2010-08-04-StackVariable.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -O0 -mtriple=x86_64-apple-darwin < %s | grep DW_OP_breg7
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -mtriple=x86_64-apple-darwin < %s | grep DW_OP_breg7
 ; Use DW_OP_breg7 in variable's location expression if the variable is in a stack slot.
 
 %struct.SVal = type { ptr, i32 }
diff --git a/llvm/test/CodeGen/X86/DbgValueOtherTargets.test b/llvm/test/CodeGen/X86/DbgValueOtherTargets.test
index 02f56823fd1d..29497d33f075 100644
--- a/llvm/test/CodeGen/X86/DbgValueOtherTargets.test
+++ b/llvm/test/CodeGen/X86/DbgValueOtherTargets.test
@@ -1,2 +1,5 @@
 RUN: llc -O0 -mtriple=i686-- -asm-verbose < %S/../Inputs/DbgValueOtherTargets.ll | FileCheck %S/../Inputs/DbgValueOtherTargets.ll
 RUN: llc -O0 -mtriple=x86_64-- -asm-verbose < %S/../Inputs/DbgValueOtherTargets.ll | FileCheck %S/../Inputs/DbgValueOtherTargets.ll
+
+RUN: llc --try-experimental-debuginfo-iterators -O0 -mtriple=i686-- -asm-verbose < %S/../Inputs/DbgValueOtherTargets.ll | FileCheck %S/../Inputs/DbgValueOtherTargets.ll
+RUN: llc --try-experimental-debuginfo-iterators -O0 -mtriple=x86_64-- -asm-verbose < %S/../Inputs/DbgValueOtherTargets.ll | FileCheck %S/../Inputs/DbgValueOtherTargets.ll
\ No newline at end of file
diff --git a/llvm/test/CodeGen/X86/fast-isel-dbg-value-alloca.ll b/llvm/test/CodeGen/X86/fast-isel-dbg-value-alloca.ll
index 77f883ee9bd3..bdb5239d289e 100644
--- a/llvm/test/CodeGen/X86/fast-isel-dbg-value-alloca.ll
+++ b/llvm/test/CodeGen/X86/fast-isel-dbg-value-alloca.ll
@@ -1,6 +1,8 @@
 ; RUN: llc -fast-isel -fast-isel-abort=1 -mtriple=x86_64-unknown-unknown -stop-after=finalize-isel %s -o - | \
 ; RUN:    FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators -fast-isel -fast-isel-abort=1 -mtriple=x86_64-unknown-unknown -stop-after=finalize-isel %s -o - |  FileCheck %s
+
 define void @foo(ptr noalias nocapture %arg) !dbg !38 {
   %k.debug = alloca ptr, align 8
   store ptr %arg, ptr %k.debug, align 8, !dbg !70
diff --git a/llvm/test/CodeGen/X86/fold-sext-trunc.ll b/llvm/test/CodeGen/X86/fold-sext-trunc.ll
index c29ca2204a6a..9963bb7b030d 100644
--- a/llvm/test/CodeGen/X86/fold-sext-trunc.ll
+++ b/llvm/test/CodeGen/X86/fold-sext-trunc.ll
@@ -1,5 +1,9 @@
 ; RUN: llc < %s -mtriple=x86_64-- | FileCheck %s
 ; RUN: llc < %s -O0 -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -stop-after livedebugvalues -o - | FileCheck %s -check-prefix=MIR
+
+; RUN: llc --try-experimental-debuginfo-iterators < %s -mtriple=x86_64-- | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s -O0 -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -stop-after livedebugvalues -o - | FileCheck %s -check-prefix=MIR
+
 ; PR4050
 
 %0 = type { i64 }
diff --git a/llvm/test/CodeGen/X86/fold-zext-trunc.ll b/llvm/test/CodeGen/X86/fold-zext-trunc.ll
index 88713d0b553a..7a70b75a028a 100644
--- a/llvm/test/CodeGen/X86/fold-zext-trunc.ll
+++ b/llvm/test/CodeGen/X86/fold-zext-trunc.ll
@@ -1,5 +1,9 @@
 ; RUN: llc < %s | FileCheck %s -check-prefix=ASM
 ; RUN: llc < %s -O0 -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -stop-after livedebugvalues -o - | FileCheck %s -check-prefix=MIR
+
+; RUN: llc --try-experimental-debuginfo-iterators < %s | FileCheck %s -check-prefix=ASM
+; RUN: llc --try-experimental-debuginfo-iterators < %s -O0 -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -stop-after livedebugvalues -o - | FileCheck %s -check-prefix=MIR
+
 ; PR9055
 target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
 target triple = "i686-pc-linux-gnu"
diff --git a/llvm/test/CodeGen/X86/label-heapallocsite.ll b/llvm/test/CodeGen/X86/label-heapallocsite.ll
index 87225354d733..78bebc1fd174 100644
--- a/llvm/test/CodeGen/X86/label-heapallocsite.ll
+++ b/llvm/test/CodeGen/X86/label-heapallocsite.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s | FileCheck --check-prefixes=CHECK %s
 ; RUN: llc -O0 < %s | FileCheck --check-prefixes=CHECK %s
 
+; RUN: llc --try-experimental-debuginfo-iterators < %s | FileCheck --check-prefixes=CHECK %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 < %s | FileCheck --check-prefixes=CHECK %s
+
 ; Source to regenerate:
 ; $ clang -cc1 -triple x86_64-windows-msvc t.cpp -debug-info-kind=limited \
 ;      -gcodeview -O2 -fms-extensions -emit-llvm -o t.ll
diff --git a/llvm/test/CodeGen/X86/machine-outliner-disubprogram.ll b/llvm/test/CodeGen/X86/machine-outliner-disubprogram.ll
index c5b3c74653db..dc582b9c8746 100644
--- a/llvm/test/CodeGen/X86/machine-outliner-disubprogram.ll
+++ b/llvm/test/CodeGen/X86/machine-outliner-disubprogram.ll
@@ -3,6 +3,7 @@
 ; Also make sure that the DISubprograms reference the generated unit.
 ; make sure that if there are two outlined functions in the program, 
 ; RUN: llc %s -verify-machineinstrs -enable-machine-outliner -mtriple=x86_64-apple-darwin -o /dev/null -print-after=machine-outliner
+; RUN: llc --try-experimental-debuginfo-iterators %s -verify-machineinstrs -enable-machine-outliner -mtriple=x86_64-apple-darwin -o /dev/null -print-after=machine-outliner
 define void @f6() #0 !dbg !8 {
 entry:
   %dog = alloca i32, align 4
diff --git a/llvm/test/CodeGen/X86/pr53243-tail-call-fastisel.ll b/llvm/test/CodeGen/X86/pr53243-tail-call-fastisel.ll
index 333eff8fb008..f21e8df95a4f 100644
--- a/llvm/test/CodeGen/X86/pr53243-tail-call-fastisel.ll
+++ b/llvm/test/CodeGen/X86/pr53243-tail-call-fastisel.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -O0 -fast-isel -mtriple=x86_64-- < %s | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -fast-isel -mtriple=x86_64-- < %s | FileCheck %s
 
 define void @test() {
 ; CHECK-LABEL: test:
diff --git a/llvm/test/CodeGen/X86/sink-local-value.ll b/llvm/test/CodeGen/X86/sink-local-value.ll
index 4732fb48a922..0e956b00b984 100644
--- a/llvm/test/CodeGen/X86/sink-local-value.ll
+++ b/llvm/test/CodeGen/X86/sink-local-value.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -O0 < %s | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 < %s | FileCheck %s
 
 target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
 target triple = "i386-linux-gnu"
diff --git a/llvm/test/DebugInfo/AArch64/cfi-eof-prologue.ll b/llvm/test/DebugInfo/AArch64/cfi-eof-prologue.ll
index 0ee313d88866..a7c229456169 100644
--- a/llvm/test/DebugInfo/AArch64/cfi-eof-prologue.ll
+++ b/llvm/test/DebugInfo/AArch64/cfi-eof-prologue.ll
@@ -15,6 +15,7 @@
 ; of CFI instructions.
 
 ; RUN: llc -fast-isel -O0 -filetype=asm < %s | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -fast-isel -O0 -filetype=asm < %s | FileCheck %s
 
 ; ModuleID = 'test1.cpp'
 target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
diff --git a/llvm/test/DebugInfo/AArch64/frameindices.ll b/llvm/test/DebugInfo/AArch64/frameindices.ll
index 8f736a07034c..d0080afa9085 100644
--- a/llvm/test/DebugInfo/AArch64/frameindices.ll
+++ b/llvm/test/DebugInfo/AArch64/frameindices.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -frame-pointer=all -O0 -fast-isel -filetype=obj < %s | llvm-dwarfdump -v - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -frame-pointer=all -O0 -fast-isel -filetype=obj < %s | llvm-dwarfdump -v - | FileCheck %s
 ; Test that a variable with multiple entries in the MMI table makes it into the
 ; debug info.
 ;
diff --git a/llvm/test/DebugInfo/ARM/split-complex.ll b/llvm/test/DebugInfo/ARM/split-complex.ll
index 8ac5d4f0aaba..64de07ea61d6 100644
--- a/llvm/test/DebugInfo/ARM/split-complex.ll
+++ b/llvm/test/DebugInfo/ARM/split-complex.ll
@@ -1,5 +1,8 @@
-; RUN: llc -mtriple=thumbv7-apple-unknown-macho -O0 -filetype=obj -o %t.o %s
-; RUN: llvm-dwarfdump -v -debug-info %t.o | FileCheck %s
+; RUN: llc -mtriple=thumbv7-apple-unknown-macho -O0 -filetype=obj -o - %s \
+; RUN: | llvm-dwarfdump -v -debug-info - | FileCheck %s
+
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=thumbv7-apple-unknown-macho -O0 -filetype=obj -o - %s \
+; RUN: | llvm-dwarfdump -v -debug-info - | FileCheck %s
 
 ; generated from (-triple thumbv7-apple-unknown-macho -Os):
 ;   void f(_Complex double c) { c = 0; }
diff --git a/llvm/test/DebugInfo/COFF/class-options-common.ll b/llvm/test/DebugInfo/COFF/class-options-common.ll
index 903824722b0c..0c6e3a844b0f 100644
--- a/llvm/test/DebugInfo/COFF/class-options-common.ll
+++ b/llvm/test/DebugInfo/COFF/class-options-common.ll
@@ -2,6 +2,11 @@
 ; RUN: llc < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | FileCheck %s --check-prefix=ASM-INLINE-COMMENTS
 ;
+; Same as above, with experimental debuginfo iterators.
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | FileCheck %s --check-prefix=ASM-INLINE-COMMENTS
+;
 ; Command to generate function-options.ll
 ; $ clang++ class-options-common.cpp -S -emit-llvm -g -gcodeview -o class-options-common.ll
 
diff --git a/llvm/test/DebugInfo/COFF/cpp-mangling.ll b/llvm/test/DebugInfo/COFF/cpp-mangling.ll
index 09a0d92b610c..beb2180957d7 100644
--- a/llvm/test/DebugInfo/COFF/cpp-mangling.ll
+++ b/llvm/test/DebugInfo/COFF/cpp-mangling.ll
@@ -1,6 +1,9 @@
 ; RUN: llc -mcpu=core2 -mtriple=i686-pc-win32 -o - -O0 -filetype=obj < %s \
 ; RUN:   | llvm-readobj --codeview - | FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators -mcpu=core2 -mtriple=i686-pc-win32 -o - -O0 -filetype=obj < %s \
+; RUN:   | llvm-readobj --codeview - | FileCheck %s
+
 ; C++ source to regenerate:
 ; namespace foo {
 ; int bar(int x) { return x * 2; }
@@ -111,4 +114,4 @@ attributes #1 = { nounwind readnone }
 !29 = !{null, !30, !10}
 !30 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !25, size: 32, flags: DIFlagArtificial | DIFlagObjectPointer)
 !31 = distinct !DISubprogram(name: "operator<<", linkageName: "??6S@@QAEXH@Z", scope: !25, file: !1, line: 8, type: !28, scopeLine: 8, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, declaration: !27, retainedNodes: !2)
-!32 = !DILocation(line: 8, column: 27, scope: !31)
\ No newline at end of file
+!32 = !DILocation(line: 8, column: 27, scope: !31)
diff --git a/llvm/test/DebugInfo/COFF/enum-co.ll b/llvm/test/DebugInfo/COFF/enum-co.ll
index 4ccfaae511fc..6ac7445595e8 100644
--- a/llvm/test/DebugInfo/COFF/enum-co.ll
+++ b/llvm/test/DebugInfo/COFF/enum-co.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
+
 ; Command to generate enum-co.ll
 ; $ clang++ enum-co.cpp -S -emit-llvm -g -gcodeview -o enum-co.ll
 ;
diff --git a/llvm/test/DebugInfo/COFF/function-options.ll b/llvm/test/DebugInfo/COFF/function-options.ll
index 863994be1d5e..79658509398f 100644
--- a/llvm/test/DebugInfo/COFF/function-options.ll
+++ b/llvm/test/DebugInfo/COFF/function-options.ll
@@ -1,5 +1,8 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
+
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
 ;
 ; Command to generate function-options.ll
 ; $ clang++ function-options.cpp -S -emit-llvm -g -gcodeview -o function-options.ll
diff --git a/llvm/test/DebugInfo/COFF/global_visibility.ll b/llvm/test/DebugInfo/COFF/global_visibility.ll
index 8da374d3a075..191c2d935cfd 100644
--- a/llvm/test/DebugInfo/COFF/global_visibility.ll
+++ b/llvm/test/DebugInfo/COFF/global_visibility.ll
@@ -1,4 +1,5 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 ;
 ; This test verifies global variables are emitted within the correct scope.
 ;
diff --git a/llvm/test/DebugInfo/COFF/globals.ll b/llvm/test/DebugInfo/COFF/globals.ll
index 2724b99dc14b..9113f5fe87f8 100644
--- a/llvm/test/DebugInfo/COFF/globals.ll
+++ b/llvm/test/DebugInfo/COFF/globals.ll
@@ -5,6 +5,14 @@
 ; RUN: llc < %s -filetype=obj -o %t
 ; RUN: obj2yaml < %t | FileCheck %s --check-prefixes=YAML,YAML-FILE
 
+; Repeat with experimental debuginfo iterators:
+; RUN: llc --try-experimental-debuginfo-iterators < %s | FileCheck %s --check-prefix=ASM
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s --check-prefix=OBJ
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s --check-prefix=OBJ
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | obj2yaml | FileCheck %s --check-prefixes=YAML,YAML-STDOUT
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj -o %t
+; RUN: obj2yaml < %t | FileCheck %s --check-prefixes=YAML,YAML-FILE
+
 ; C++ source to regenerate:
 ; $ cat a.cpp
 ; int first;
diff --git a/llvm/test/DebugInfo/COFF/lambda.ll b/llvm/test/DebugInfo/COFF/lambda.ll
index 7b575a7b07aa..a171c85ba3c2 100644
--- a/llvm/test/DebugInfo/COFF/lambda.ll
+++ b/llvm/test/DebugInfo/COFF/lambda.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | llvm-mc -filetype=obj --triple=i686-windows | llvm-readobj - --codeview | FileCheck %s
 ;
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=i686-windows | llvm-readobj - --codeview | FileCheck %s
+;
 ; Verify lambda routines are emitted properly in CodeView.
 ;
 ; The original source code:
diff --git a/llvm/test/DebugInfo/COFF/lines-bb-start.ll b/llvm/test/DebugInfo/COFF/lines-bb-start.ll
index 70c96b368c9a..c8693b6f2d57 100644
--- a/llvm/test/DebugInfo/COFF/lines-bb-start.ll
+++ b/llvm/test/DebugInfo/COFF/lines-bb-start.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -O0 < %s | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 < %s | FileCheck %s
 
 source_filename = "t.c"
 target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
diff --git a/llvm/test/DebugInfo/COFF/nrvo.ll b/llvm/test/DebugInfo/COFF/nrvo.ll
index 7bd9d35b7a00..52b93ddf6bc3 100644
--- a/llvm/test/DebugInfo/COFF/nrvo.ll
+++ b/llvm/test/DebugInfo/COFF/nrvo.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s | FileCheck %s --check-prefix=ASM
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s --check-prefix=OBJ
 
+; RUN: llc --try-experimental-debuginfo-iterators < %s | FileCheck %s --check-prefix=ASM
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s --check-prefix=OBJ
+
 ; C++ source to regenerate:
 ; struct Foo {
 ;   Foo() = default;
diff --git a/llvm/test/DebugInfo/COFF/numeric-leaves.ll b/llvm/test/DebugInfo/COFF/numeric-leaves.ll
index 2b3f7ed495c6..68f6edc76e27 100644
--- a/llvm/test/DebugInfo/COFF/numeric-leaves.ll
+++ b/llvm/test/DebugInfo/COFF/numeric-leaves.ll
@@ -2,6 +2,11 @@
 ; RUN: llc < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | FileCheck %s --check-prefix=ASM
 
+; Repeat with experimental debuginfo iterators.
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | FileCheck %s --check-prefix=ASM
+
 ; C++ source to regenerate:
 ; $ cat numeric-leaves.cpp
 ; const long long Minus1 = -1;
diff --git a/llvm/test/DebugInfo/COFF/parent-type-scopes.ll b/llvm/test/DebugInfo/COFF/parent-type-scopes.ll
index 95c7a5589522..7d91e6538e31 100644
--- a/llvm/test/DebugInfo/COFF/parent-type-scopes.ll
+++ b/llvm/test/DebugInfo/COFF/parent-type-scopes.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s -filetype=obj -o %t.o
 ; RUN: llvm-pdbutil dump -types %t.o | FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj -o %t.o
+; RUN: llvm-pdbutil dump -types %t.o | FileCheck %s
+
 ; C++ source:
 ; // Note that MSVC doesn't emit anything about WrapTypedef or WrapTypedef::Inner!
 ; struct WrapTypedef {
diff --git a/llvm/test/DebugInfo/COFF/purge-typedef-udts.ll b/llvm/test/DebugInfo/COFF/purge-typedef-udts.ll
index 8118e0ca2ae8..64f97c106a4a 100644
--- a/llvm/test/DebugInfo/COFF/purge-typedef-udts.ll
+++ b/llvm/test/DebugInfo/COFF/purge-typedef-udts.ll
@@ -1,4 +1,5 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 source_filename = "test/DebugInfo/COFF/purge-typedef-udts.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-msvc19.11.25506"
diff --git a/llvm/test/DebugInfo/COFF/thunk.ll b/llvm/test/DebugInfo/COFF/thunk.ll
index 39abed580780..d6c15f595358 100644
--- a/llvm/test/DebugInfo/COFF/thunk.ll
+++ b/llvm/test/DebugInfo/COFF/thunk.ll
@@ -1,7 +1,12 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | FileCheck %s --check-prefix=ASM
 ; RUN: opt -S -debugger-tune=lldb %s | FileCheck -check-prefix=OPT %s
-;
+
+; Do the same for experimental debuginfo iterators.
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | FileCheck %s --check-prefix=ASM
+; RUN: opt --try-experimental-debuginfo-iterators -S -debugger-tune=lldb %s | FileCheck -check-prefix=OPT %s
+
 ; -- "thunk.cpp" begin --------------------------------------------------------
 ; class A { public: virtual bool MyMethod() { return true; } }; 
 ; class B { public: virtual bool MyMethod() { return true; } }; 
diff --git a/llvm/test/DebugInfo/COFF/type-quals.ll b/llvm/test/DebugInfo/COFF/type-quals.ll
index c5953d384d31..461266f72bdc 100644
--- a/llvm/test/DebugInfo/COFF/type-quals.ll
+++ b/llvm/test/DebugInfo/COFF/type-quals.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
+
 ; C++ source to regenerate:
 ; $ cat m.cpp
 ; union Union {
diff --git a/llvm/test/DebugInfo/COFF/types-cvarargs.ll b/llvm/test/DebugInfo/COFF/types-cvarargs.ll
index 68c7a7740b71..bd41d68669f6 100644
--- a/llvm/test/DebugInfo/COFF/types-cvarargs.ll
+++ b/llvm/test/DebugInfo/COFF/types-cvarargs.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
+
 ; C++ source to regenerate:
 ; $ cat t.cpp
 ; typedef void (*FuncTypedef)(int, float, ...);
diff --git a/llvm/test/DebugInfo/COFF/types-integer-old.ll b/llvm/test/DebugInfo/COFF/types-integer-old.ll
index 2ed36662a804..c1c18bca8ed4 100644
--- a/llvm/test/DebugInfo/COFF/types-integer-old.ll
+++ b/llvm/test/DebugInfo/COFF/types-integer-old.ll
@@ -1,4 +1,5 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 
 ; Tests that CodeView integer types are generated even when using Clang's old integer type names.
 
diff --git a/llvm/test/DebugInfo/COFF/types-method-ref-qualifiers.ll b/llvm/test/DebugInfo/COFF/types-method-ref-qualifiers.ll
index b7114b87ae5e..6f9987c33ab9 100644
--- a/llvm/test/DebugInfo/COFF/types-method-ref-qualifiers.ll
+++ b/llvm/test/DebugInfo/COFF/types-method-ref-qualifiers.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
 ; RUN: llc < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s | llvm-mc -filetype=obj --triple=x86_64-windows | llvm-readobj - --codeview | FileCheck %s
+
 ; C++ source to regenerate:
 ; struct A {
 ;   int NoRefQual();
diff --git a/llvm/test/DebugInfo/Generic/2010-10-01-crash.ll b/llvm/test/DebugInfo/Generic/2010-10-01-crash.ll
index 8f8d67173c1c..54c4c07f8c23 100644
--- a/llvm/test/DebugInfo/Generic/2010-10-01-crash.ll
+++ b/llvm/test/DebugInfo/Generic/2010-10-01-crash.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -O0 %s -o /dev/null
+; RUN: llc --try-experimental-debuginfo-iterators -O0 %s -o /dev/null
 
 define void @CGRectStandardize(ptr sret(i32) %agg.result, ptr byval(i32) %rect) nounwind ssp !dbg !0 {
 entry:
diff --git a/llvm/test/DebugInfo/Generic/PR20038.ll b/llvm/test/DebugInfo/Generic/PR20038.ll
index 024a6abf0591..d7fa11efab5d 100644
--- a/llvm/test/DebugInfo/Generic/PR20038.ll
+++ b/llvm/test/DebugInfo/Generic/PR20038.ll
@@ -2,6 +2,7 @@
 ; XFAIL: target=sparc{{.*}}
 
 ; RUN: %llc_dwarf -O0 -filetype=obj -dwarf-linkage-names=All < %s | llvm-dwarfdump -debug-info - | FileCheck %s --implicit-check-not=DW_TAG
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 -filetype=obj -dwarf-linkage-names=All < %s | llvm-dwarfdump -debug-info - | FileCheck %s --implicit-check-not=DW_TAG
 
 ; IR generated from clang -O0 with:
 ; struct C {
diff --git a/llvm/test/DebugInfo/Generic/dead-argument-order.ll b/llvm/test/DebugInfo/Generic/dead-argument-order.ll
index f6cd8092a48d..b2037b0590f2 100644
--- a/llvm/test/DebugInfo/Generic/dead-argument-order.ll
+++ b/llvm/test/DebugInfo/Generic/dead-argument-order.ll
@@ -1,4 +1,5 @@
 ; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-info - | FileCheck %s
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 -filetype=obj < %s | llvm-dwarfdump -debug-info - | FileCheck %s
 
 ; Built from the following source with clang -O1
 ; struct S { int i; };
diff --git a/llvm/test/DebugInfo/Generic/discriminated-union.ll b/llvm/test/DebugInfo/Generic/discriminated-union.ll
index 0acf478f653a..d267d9b029e9 100644
--- a/llvm/test/DebugInfo/Generic/discriminated-union.ll
+++ b/llvm/test/DebugInfo/Generic/discriminated-union.ll
@@ -1,6 +1,9 @@
 ; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t
 ; RUN: llvm-dwarfdump -v -debug-info %t | FileCheck %s
 
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump -v -debug-info %t | FileCheck %s
+
 ; Check for a variant part that has two members, one of which has a
 ; discriminant value.
 
diff --git a/llvm/test/DebugInfo/Generic/disubrange_vla.ll b/llvm/test/DebugInfo/Generic/disubrange_vla.ll
index 18dd128ee01f..6554cf46b0be 100644
--- a/llvm/test/DebugInfo/Generic/disubrange_vla.ll
+++ b/llvm/test/DebugInfo/Generic/disubrange_vla.ll
@@ -4,6 +4,13 @@
 ; RUN: llvm-dwarfdump -verbose %t >> %t2
 ; RUN: cat %t2 | FileCheck %s
 
+; Repeat the test with experimental debuginfo iterators.
+; RUN: rm -rf %t %t2
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump -name=vla_expr %t > %t2
+; RUN: llvm-dwarfdump -verbose %t >> %t2
+; RUN: cat %t2 | FileCheck %s
+
 ; This test runs llvm-dwarfdump twice:
 ; - First to get the debug entry for 'vla_expr'.
 ; - Second to check that this is the entry referenced in DW_AT_count.
diff --git a/llvm/test/DebugInfo/Generic/enum-types.ll b/llvm/test/DebugInfo/Generic/enum-types.ll
index 8af9b21bdaa4..288513468b06 100644
--- a/llvm/test/DebugInfo/Generic/enum-types.ll
+++ b/llvm/test/DebugInfo/Generic/enum-types.ll
@@ -1,5 +1,6 @@
 ;
 ; RUN: %llc_dwarf -filetype=obj -O0 -dwarf-linkage-names=All < %s | llvm-dwarfdump -v -debug-info - | FileCheck %s
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -filetype=obj -O0 -dwarf-linkage-names=All < %s | llvm-dwarfdump -v -debug-info - | FileCheck %s
 
 ; Make sure we can handle enums with the same identifier but in enum types of
 ; different compile units.
diff --git a/llvm/test/DebugInfo/Generic/enum.ll b/llvm/test/DebugInfo/Generic/enum.ll
index 63665e355edf..11d30d35f7cf 100644
--- a/llvm/test/DebugInfo/Generic/enum.ll
+++ b/llvm/test/DebugInfo/Generic/enum.ll
@@ -1,6 +1,9 @@
 ; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t
 ; RUN: llvm-dwarfdump -v %t | FileCheck %s
 
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump -v %t | FileCheck %s
+
 ; IR generated from the following code compiled with clang -g:
 ; enum e1 { I, J = 0xffffffffU, K = 0xf000000000000000ULL } a;
 ; enum e2 { X };
diff --git a/llvm/test/DebugInfo/Generic/import-inlined-declaration.ll b/llvm/test/DebugInfo/Generic/import-inlined-declaration.ll
index dc57127dae18..6870cfa81100 100644
--- a/llvm/test/DebugInfo/Generic/import-inlined-declaration.ll
+++ b/llvm/test/DebugInfo/Generic/import-inlined-declaration.ll
@@ -1,5 +1,7 @@
 ; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump - | FileCheck --implicit-check-not "{{DW_TAG|NULL}}" %s
 
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 -filetype=obj < %s | llvm-dwarfdump - | FileCheck --implicit-check-not "{{DW_TAG|NULL}}" %s
+
 ; namespace ns {
 ; inline __attribute__((always_inline))
 ; void foo() { int a = 4; }
diff --git a/llvm/test/DebugInfo/Generic/inlined-vars.ll b/llvm/test/DebugInfo/Generic/inlined-vars.ll
index 8a71f09ca01b..f2ef69b47401 100644
--- a/llvm/test/DebugInfo/Generic/inlined-vars.ll
+++ b/llvm/test/DebugInfo/Generic/inlined-vars.ll
@@ -1,5 +1,7 @@
 ; RUN: %llc_dwarf -O0 < %s | FileCheck %s -check-prefix ARGUMENT
 ; RUN: %llc_dwarf -O0 < %s | FileCheck %s -check-prefix VARIABLE
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 < %s | FileCheck %s -check-prefix ARGUMENT
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 < %s | FileCheck %s -check-prefix VARIABLE
 ; PR 13202
 
 define i32 @main() uwtable !dbg !5 {
diff --git a/llvm/test/DebugInfo/Generic/recursive_inlining.ll b/llvm/test/DebugInfo/Generic/recursive_inlining.ll
index 908e408401f8..4636a4d2b722 100644
--- a/llvm/test/DebugInfo/Generic/recursive_inlining.ll
+++ b/llvm/test/DebugInfo/Generic/recursive_inlining.ll
@@ -1,4 +1,5 @@
 ; RUN: %llc_dwarf -filetype=obj -O0 < %s | llvm-dwarfdump -debug-info - | FileCheck %s
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -filetype=obj -O0 < %s | llvm-dwarfdump -debug-info - | FileCheck %s
 
 ; This isn't a very pretty test case - I imagine there might be other ways to
 ; tickle the optimizers into producing the desired code, but I haven't found
diff --git a/llvm/test/DebugInfo/Generic/univariant-discriminated-union.ll b/llvm/test/DebugInfo/Generic/univariant-discriminated-union.ll
index 628c2f8b1dec..9514e6fa4db4 100644
--- a/llvm/test/DebugInfo/Generic/univariant-discriminated-union.ll
+++ b/llvm/test/DebugInfo/Generic/univariant-discriminated-union.ll
@@ -1,6 +1,9 @@
 ; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t
 ; RUN: llvm-dwarfdump -v -debug-info %t | FileCheck %s
 
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump -v -debug-info %t | FileCheck %s
+
 ; Check for a univariant discriminated union -- that is, a variant
 ; part without a discriminant and with just a single variant.
 
diff --git a/llvm/test/DebugInfo/Mips/delay-slot.ll b/llvm/test/DebugInfo/Mips/delay-slot.ll
index ed2769f33f4b..f966ac7c1ec5 100644
--- a/llvm/test/DebugInfo/Mips/delay-slot.ll
+++ b/llvm/test/DebugInfo/Mips/delay-slot.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -filetype=obj -O0 -relocation-model=pic < %s -mtriple mips-unknown-linux-gnu | llvm-dwarfdump -a - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -filetype=obj -O0 -relocation-model=pic < %s -mtriple mips-unknown-linux-gnu | llvm-dwarfdump -a - | FileCheck %s
 ; PR19815
 
 ; Generated using clang -target mips-linux-gnu -g test.c -S -o - -flto|opt -passes=sroa -S
diff --git a/llvm/test/DebugInfo/X86/aligned_stack_var.ll b/llvm/test/DebugInfo/X86/aligned_stack_var.ll
index 089b3ffab569..f8b5d4c1bdf5 100644
--- a/llvm/test/DebugInfo/X86/aligned_stack_var.ll
+++ b/llvm/test/DebugInfo/X86/aligned_stack_var.ll
@@ -1,6 +1,9 @@
 ; RUN: llc %s -mtriple=x86_64-pc-linux-gnu -O0 -filetype=obj -o %t
 ; RUN: llvm-dwarfdump -debug-info %t | FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators %s -mtriple=x86_64-pc-linux-gnu -O0 -filetype=obj -o %t
+; RUN: llvm-dwarfdump -debug-info %t | FileCheck %s
+
 ; If stack is realigned, we shouldn't describe locations of local
 ; variables by giving offset from the frame pointer (%rbp):
 ; push %rpb
diff --git a/llvm/test/DebugInfo/X86/arguments.ll b/llvm/test/DebugInfo/X86/arguments.ll
index 767c1385e77f..229a69696ce8 100644
--- a/llvm/test/DebugInfo/X86/arguments.ll
+++ b/llvm/test/DebugInfo/X86/arguments.ll
@@ -2,6 +2,9 @@
 ; RUN: llc -mtriple=x86_64-unknown-unknown -O0 -filetype=obj < %s > %t
 ; RUN: llvm-dwarfdump %t | FileCheck %s
 
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64-unknown-unknown -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump %t | FileCheck %s
+
 ; IR generated from clang -g with the following source:
 ; struct foo {
 ;   foo(const foo&);
diff --git a/llvm/test/DebugInfo/X86/asan_debug_info.ll b/llvm/test/DebugInfo/X86/asan_debug_info.ll
index 4a4743ee0df5..342e3c86f689 100644
--- a/llvm/test/DebugInfo/X86/asan_debug_info.ll
+++ b/llvm/test/DebugInfo/X86/asan_debug_info.ll
@@ -3,7 +3,7 @@
 ; RUN:   llvm-dwarfdump - | FileCheck %s
 
 ; RUN: opt --try-experimental-debuginfo-iterators < %s -passes=asan -asan-use-after-return=never -S | \
-; RUN:   llc -O0 -filetype=obj - -o - | \
+; RUN:   llc --try-experimental-debuginfo-iterators -O0 -filetype=obj - -o - | \
 ; RUN:   llvm-dwarfdump - | FileCheck %s
 
 ; For this test case, ASan used to produce IR which resulted in the following
diff --git a/llvm/test/DebugInfo/X86/byvalstruct.ll b/llvm/test/DebugInfo/X86/byvalstruct.ll
index d84e4753516b..a23a49d3145d 100644
--- a/llvm/test/DebugInfo/X86/byvalstruct.ll
+++ b/llvm/test/DebugInfo/X86/byvalstruct.ll
@@ -1,5 +1,7 @@
 ; RUN: llc  -mtriple=x86_64-apple-macosx10.8.0 -O0 -filetype=obj -o %t %s
 ; RUN: llvm-dwarfdump -v -debug-info %t | FileCheck %s
+; RUN: llc  --try-experimental-debuginfo-iterators -mtriple=x86_64-apple-macosx10.8.0 -O0 -filetype=obj -o %t %s
+; RUN: llvm-dwarfdump -v -debug-info %t | FileCheck %s
 ; Test that we generate debug info for by-value struct args that are not used.
 ;
 ; CHECK: DW_TAG_formal_parameter
diff --git a/llvm/test/DebugInfo/X86/convert-linked.ll b/llvm/test/DebugInfo/X86/convert-linked.ll
index 6a74a6310bc3..9a0d65b4ccd1 100644
--- a/llvm/test/DebugInfo/X86/convert-linked.ll
+++ b/llvm/test/DebugInfo/X86/convert-linked.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -mtriple=x86_64 -filetype=obj -O0 < %s | llvm-dwarfdump - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64 -filetype=obj -O0 < %s | llvm-dwarfdump - | FileCheck %s
 
 ; CHECK: DW_TAG_compile_unit
 ; CHECK: [[CU0BT0:0x[0-9a-f]+]]: DW_TAG_base_type
diff --git a/llvm/test/DebugInfo/X86/dbg-declare-arg.ll b/llvm/test/DebugInfo/X86/dbg-declare-arg.ll
index 8e5c117d16be..c206ab660d22 100644
--- a/llvm/test/DebugInfo/X86/dbg-declare-arg.ll
+++ b/llvm/test/DebugInfo/X86/dbg-declare-arg.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -O0 -fast-isel=true  -filetype=obj -o - %s | llvm-dwarfdump -v - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -fast-isel=true  -filetype=obj -o - %s | llvm-dwarfdump -v - | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-apple-macosx10.6.7"
diff --git a/llvm/test/DebugInfo/X86/dbg-declare-inalloca.ll b/llvm/test/DebugInfo/X86/dbg-declare-inalloca.ll
index 1de1d0b17b39..2afbf3d8255b 100644
--- a/llvm/test/DebugInfo/X86/dbg-declare-inalloca.ll
+++ b/llvm/test/DebugInfo/X86/dbg-declare-inalloca.ll
@@ -2,6 +2,11 @@
 ; RUN: llc < %s | FileCheck %s
 ; RUN: llc -filetype=obj -O0 < %s | llvm-readobj --codeview - | FileCheck %s --check-prefix=OBJ
 
+; Same checks, this time with experimental debuginfo iterators.
+; RUN: llc --try-experimental-debuginfo-iterators -O0 < %s | FileCheck %s --check-prefix=CHECK --check-prefix=DEBUG
+; RUN: llc --try-experimental-debuginfo-iterators < %s | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -filetype=obj -O0 < %s | llvm-readobj --codeview - | FileCheck %s --check-prefix=OBJ
+
 ; IR generated by the following source:
 ; struct NonTrivial {
 ;   NonTrivial();// : x(42) {}
diff --git a/llvm/test/DebugInfo/X86/dbg-declare.ll b/llvm/test/DebugInfo/X86/dbg-declare.ll
index f07ddbb639ec..4cf93c6be0ce 100644
--- a/llvm/test/DebugInfo/X86/dbg-declare.ll
+++ b/llvm/test/DebugInfo/X86/dbg-declare.ll
@@ -1,6 +1,11 @@
 ; RUN: llc < %s -O0 -mtriple x86_64-apple-darwin | FileCheck %s
 ; RUN: llc < %s -O0 -mtriple x86_64-apple-darwin -filetype=obj \
 ; RUN:     | llvm-dwarfdump -v - --debug-info | FileCheck %s --check-prefix=DWARF
+
+; RUN: llc --try-experimental-debuginfo-iterators < %s -O0 -mtriple x86_64-apple-darwin | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators < %s -O0 -mtriple x86_64-apple-darwin -filetype=obj \
+; RUN:     | llvm-dwarfdump -v - --debug-info | FileCheck %s --check-prefix=DWARF
+
 ; <rdar://problem/11134152>
 
 ; CHECK-LABEL: _foo:
diff --git a/llvm/test/DebugInfo/X86/dbg_value_direct.ll b/llvm/test/DebugInfo/X86/dbg_value_direct.ll
index 4ac25414f2a7..a1bdd8eab090 100644
--- a/llvm/test/DebugInfo/X86/dbg_value_direct.ll
+++ b/llvm/test/DebugInfo/X86/dbg_value_direct.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -filetype=obj -O0 < %s
+; RUN: llc --try-experimental-debuginfo-iterators -filetype=obj -O0 < %s
 ; Test that we handle DBG_VALUEs in a register without crashing.
 ;
 ; Generated from clang with -fsanitize=address:
diff --git a/llvm/test/DebugInfo/X86/debug-info-template-parameter.ll b/llvm/test/DebugInfo/X86/debug-info-template-parameter.ll
index 10f453e1f21f..e552bb02b03c 100644
--- a/llvm/test/DebugInfo/X86/debug-info-template-parameter.ll
+++ b/llvm/test/DebugInfo/X86/debug-info-template-parameter.ll
@@ -1,4 +1,5 @@
 ; RUN: llc  %s -filetype=obj -o - | llvm-dwarfdump -v - | FileCheck %s
+; RUN: llc  --try-experimental-debuginfo-iterators %s -filetype=obj -o - | llvm-dwarfdump -v - | FileCheck %s
 
 ; C++ source to regenerate:
 
diff --git a/llvm/test/DebugInfo/X86/debug_value_list_selectiondag.ll b/llvm/test/DebugInfo/X86/debug_value_list_selectiondag.ll
index c4b7b497fb7f..cd21b78487a7 100644
--- a/llvm/test/DebugInfo/X86/debug_value_list_selectiondag.ll
+++ b/llvm/test/DebugInfo/X86/debug_value_list_selectiondag.ll
@@ -2,6 +2,12 @@
 ; 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
 
+;; Run with experimental debuginfo iterators.
+; RUN: llc --try-experimental-debuginfo-iterators %s -start-after=codegenprepare -stop-before=finalize-isel -experimental-debug-variable-locations=false -o - | FileCheck --check-prefixes=CHECK,DAG %s
+; RUN: llc --try-experimental-debuginfo-iterators %s -fast-isel=true -start-after=codegenprepare -stop-before=finalize-isel -experimental-debug-variable-locations=false -o - | FileCheck --check-prefixes=CHECK,FAST %s
+;; FIXME: Disabled until global isel support is added.
+; run: llc --try-experimental-debuginfo-iterators %s -global-isel=true -start-after=codegenprepare -stop-before=finalize-isel -experimental-debug-variable-locations=false -o - | FileCheck --check-prefixes=CHECK,GLOBAL %s
+
 ;; Run with assignment tracking enabled (use sed to add the module flag).
 ; RUN: sed 's/;Uncomment-with-sed//g' < %s \
 ; RUN: | llc -global-isel=false -start-after=codegenprepare -stop-before=finalize-isel -experimental-debug-variable-locations=false -o - \
diff --git a/llvm/test/DebugInfo/X86/double-declare.ll b/llvm/test/DebugInfo/X86/double-declare.ll
index 6f273b142f99..5e422e171ae3 100644
--- a/llvm/test/DebugInfo/X86/double-declare.ll
+++ b/llvm/test/DebugInfo/X86/double-declare.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -mtriple=x86_64-apple-darwin -O0 -filetype=obj -o - < %s | llvm-dwarfdump -v -debug-info - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64-apple-darwin -O0 -filetype=obj -o - < %s | llvm-dwarfdump -v -debug-info - | FileCheck %s
 ; PR33157. Don't crash on duplicate dbg.declare.
 ; CHECK: DW_TAG_formal_parameter
 ; CHECK: DW_AT_location [DW_FORM_exprloc]
diff --git a/llvm/test/DebugInfo/X86/fi-piece.ll b/llvm/test/DebugInfo/X86/fi-piece.ll
index 30144d787555..e7b8afea9059 100644
--- a/llvm/test/DebugInfo/X86/fi-piece.ll
+++ b/llvm/test/DebugInfo/X86/fi-piece.ll
@@ -1,4 +1,5 @@
 ; RUN: llc %s -filetype=obj -o - | llvm-dwarfdump -v - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators %s -filetype=obj -o - | llvm-dwarfdump -v - | FileCheck %s
 ; Test that multi-DW_OP_piece expressions are emitted for FI variables.
 ;
 ; CHECK: .debug_info contents:
diff --git a/llvm/test/DebugInfo/X86/implicit_value-double.ll b/llvm/test/DebugInfo/X86/implicit_value-double.ll
index 03f7a018ebc4..e0d8e791839c 100644
--- a/llvm/test/DebugInfo/X86/implicit_value-double.ll
+++ b/llvm/test/DebugInfo/X86/implicit_value-double.ll
@@ -2,7 +2,10 @@
 ;; for double type.
 
 ; RUN: llc -O0 -debugger-tune=gdb -filetype=obj %s -o -  | llvm-dwarfdump - | FileCheck %s --check-prefixes=CHECK,BOTH
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -debugger-tune=gdb -filetype=obj %s -o -  | llvm-dwarfdump - | FileCheck %s --check-prefixes=CHECK,BOTH
+
 ; RUN: llc -O0 -debugger-tune=lldb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s --check-prefixes=CHECK,BOTH
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -debugger-tune=lldb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s --check-prefixes=CHECK,BOTH
 
 ; CHECK: .debug_info contents:
 ; CHECK: DW_TAG_variable
@@ -11,6 +14,7 @@
 ; CHECK-NEXT:  DW_AT_name    ("d")
 
 ; RUN: llc -O0 -debugger-tune=sce -filetype=obj %s -o -  | llvm-dwarfdump - | FileCheck %s -check-prefixes=SCE-CHECK,BOTH
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -debugger-tune=sce -filetype=obj %s -o -  | llvm-dwarfdump - | FileCheck %s -check-prefixes=SCE-CHECK,BOTH
 
 ; SCE-CHECK: .debug_info contents:
 ; SCE-CHECK: DW_TAG_variable
diff --git a/llvm/test/DebugInfo/X86/instr-ref-opt-levels.ll b/llvm/test/DebugInfo/X86/instr-ref-opt-levels.ll
index 23eaacac6a74..9313751a5c13 100644
--- a/llvm/test/DebugInfo/X86/instr-ref-opt-levels.ll
+++ b/llvm/test/DebugInfo/X86/instr-ref-opt-levels.ll
@@ -8,6 +8,17 @@
 ; RUN:      -fast-isel -experimental-debug-variable-locations \
 ; RUN:    | FileCheck %s --check-prefix=FASTISEL --implicit-check-not=DBG_VALUE
 
+;; Repeat the tests using experimental debuginfo iterators.
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64-- %s -o - -O0 -stop-before=finalize-isel \
+; RUN:      -experimental-debug-variable-locations \
+; RUN:    | FileCheck %s --check-prefix=O0 --implicit-check-not=DBG_INSTR_REF
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64-- %s -o - -O2 -stop-before=finalize-isel \
+; RUN:      -experimental-debug-variable-locations \
+; RUN:    | FileCheck %s --check-prefix=O2 --implicit-check-not=DBG_VALUE
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64-- %s -o - -stop-before=finalize-isel \
+; RUN:      -fast-isel -experimental-debug-variable-locations \
+; RUN:    | FileCheck %s --check-prefix=FASTISEL --implicit-check-not=DBG_VALUE
+
 ; Test that instruction-referencing variable locations are issued at -O2, but
 ; normal DBG_VALUEs are issued at -O0. This behaviour is desired as the former
 ; is slow when applied to unoptimized code.
diff --git a/llvm/test/DebugInfo/X86/instr-ref-selectiondag.ll b/llvm/test/DebugInfo/X86/instr-ref-selectiondag.ll
index dbbef2b39587..29f7d9353e0a 100644
--- a/llvm/test/DebugInfo/X86/instr-ref-selectiondag.ll
+++ b/llvm/test/DebugInfo/X86/instr-ref-selectiondag.ll
@@ -12,6 +12,21 @@
 ; RUN:   | FileCheck %s --check-prefix=FASTISEL-INSTRREF \
 ; RUN:     --implicit-check-not=DBG_VALUE
 
+;; Repeat tests using experimental debuginfo iterators.
+; RUN: llc --try-experimental-debuginfo-iterators %s -mtriple=x86_64-unknown-unknown -o - -stop-before=finalize-isel -experimental-debug-variable-locations=false \
+; RUN:   | FileCheck %s --check-prefix=NORMAL \
+; RUN:     --implicit-check-not=debug-instr-number \
+; RUN:     --implicit-check-not=DBG_INSTR_REF
+; RUN: llc --try-experimental-debuginfo-iterators %s -mtriple=x86_64-unknown-unknown -o - -stop-before=finalize-isel \
+; RUN:     -experimental-debug-variable-locations -verify-machineinstrs \
+; RUN:   | FileCheck %s --check-prefix=INSTRREF \
+; RUN:     --implicit-check-not=DBG_VALUE
+; RUN: llc --try-experimental-debuginfo-iterators %s -mtriple=x86_64-unknown-unknown -o - -stop-before=finalize-isel \
+; RUN:     -experimental-debug-variable-locations -verify-machineinstrs \
+; RUN:     -fast-isel \
+; RUN:   | FileCheck %s --check-prefix=FASTISEL-INSTRREF \
+; RUN:     --implicit-check-not=DBG_VALUE
+
 ; NORMAL: ![[SOCKS:[0-9]+]] = !DILocalVariable(name: "socks",
 ; NORMAL: ![[KNEES:[0-9]+]] = !DILocalVariable(name: "knees",
 ; INSTRREF: ![[SOCKS:[0-9]+]] = !DILocalVariable(name: "socks",
diff --git a/llvm/test/DebugInfo/X86/missing-abstract-variable.ll b/llvm/test/DebugInfo/X86/missing-abstract-variable.ll
index 175a306bdaf6..8d493e593b8b 100644
--- a/llvm/test/DebugInfo/X86/missing-abstract-variable.ll
+++ b/llvm/test/DebugInfo/X86/missing-abstract-variable.ll
@@ -1,5 +1,5 @@
 ; RUN: %llc_dwarf -mtriple x86_64-gnu-linux -O0 -filetype=obj < %s | llvm-dwarfdump -debug-info - | FileCheck %s
-
+; RUN: %llc_dwarf --try-experimental-debuginfo-iterators -mtriple x86_64-gnu-linux -O0 -filetype=obj < %s | llvm-dwarfdump -debug-info - | FileCheck %s
 ; Build from the following source with clang -O2.
 
 ; The important details are that 'x's abstract definition is first built during
diff --git a/llvm/test/DebugInfo/X86/parameters.ll b/llvm/test/DebugInfo/X86/parameters.ll
index 5254fadecbd7..cacdd571c91d 100644
--- a/llvm/test/DebugInfo/X86/parameters.ll
+++ b/llvm/test/DebugInfo/X86/parameters.ll
@@ -1,5 +1,6 @@
 ;
 ; RUN: llc -mtriple=x86_64-unknown-linux-gnu -O0 -filetype=obj %s -o - | llvm-dwarfdump -v -debug-info - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64-unknown-linux-gnu -O0 -filetype=obj %s -o - | llvm-dwarfdump -v -debug-info - | FileCheck %s
 
 ; Test case derived from compiling the following source with clang -g:
 ;
diff --git a/llvm/test/DebugInfo/X86/pieces-1.ll b/llvm/test/DebugInfo/X86/pieces-1.ll
index f614f78c6581..e0fcd083c7e8 100644
--- a/llvm/test/DebugInfo/X86/pieces-1.ll
+++ b/llvm/test/DebugInfo/X86/pieces-1.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -O0 %s -filetype=obj -o - | llvm-dwarfdump -debug-loc - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 %s -filetype=obj -o - | llvm-dwarfdump -debug-loc - | FileCheck %s
 ;
 ; rdar://problem/15928306
 ;
diff --git a/llvm/test/DebugInfo/X86/reference-argument.ll b/llvm/test/DebugInfo/X86/reference-argument.ll
index 8747da5071a8..803947ffeef6 100644
--- a/llvm/test/DebugInfo/X86/reference-argument.ll
+++ b/llvm/test/DebugInfo/X86/reference-argument.ll
@@ -1,5 +1,7 @@
 ; RUN: llc -mtriple=x86_64-apple-macosx10.9.0 -filetype=obj -O0 < %s \
 ; RUN:   | llvm-dwarfdump -v -debug-info - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64-apple-macosx10.9.0 -filetype=obj -O0 < %s \
+; RUN:   | llvm-dwarfdump -v -debug-info - | FileCheck %s
 ; ModuleID = 'aggregate-indirect-arg.cpp'
 ; extracted from debuginfo-tests/aggregate-indirect-arg.cpp
 
diff --git a/llvm/test/DebugInfo/X86/spill-indirect-nrvo.ll b/llvm/test/DebugInfo/X86/spill-indirect-nrvo.ll
index b9a504b9b7b6..4bcb08d675a4 100644
--- a/llvm/test/DebugInfo/X86/spill-indirect-nrvo.ll
+++ b/llvm/test/DebugInfo/X86/spill-indirect-nrvo.ll
@@ -4,11 +4,9 @@
 ; RUN: llc -O0 < %s -experimental-debug-variable-locations=true | FileCheck -check-prefixes=CHECK,OPTNONE %s
 
 ; RUN: llc --try-experimental-debuginfo-iterators < %s -experimental-debug-variable-locations=false | FileCheck -check-prefixes=CHECK,OPT %s
-;; FIXME: RemoveDIs - enable when FastISel support is added.
-; run: llc --try-experimental-debuginfo-iterators -O0 < %s -experimental-debug-variable-locations=false | FileCheck -check-prefixes=CHECK,OPTNONE %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 < %s -experimental-debug-variable-locations=false | FileCheck -check-prefixes=CHECK,OPTNONE %s
 ; RUN: llc --try-experimental-debuginfo-iterators < %s -experimental-debug-variable-locations=true | FileCheck -check-prefixes=CHECK,OPT %s
-;; FIXME: RemoveDIs - enable when FastISel support is added.
-; run: llc --try-experimental-debuginfo-iterators -O0 < %s -experimental-debug-variable-locations=true | FileCheck -check-prefixes=CHECK,OPTNONE %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 < %s -experimental-debug-variable-locations=true | FileCheck -check-prefixes=CHECK,OPTNONE %s
 
 ; Make sure we insert DW_OP_deref when spilling indirect DBG_VALUE instructions.
 
diff --git a/llvm/test/DebugInfo/X86/sret.ll b/llvm/test/DebugInfo/X86/sret.ll
index f06b097d07b9..222fb05b6df8 100644
--- a/llvm/test/DebugInfo/X86/sret.ll
+++ b/llvm/test/DebugInfo/X86/sret.ll
@@ -1,8 +1,7 @@
 ; RUN: llc -split-dwarf-file=foo.dwo -O0 %s -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o %t
 ; RUN: llvm-dwarfdump -debug-info %t | FileCheck %s --check-prefix=CHECK-DWO
-;; FIXME: RemoveDIs - enable when FastISel support is added.
-; run: llc --try-experimental-debuginfo-iterators -split-dwarf-file=foo.dwo -O0 %s -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o %t
-; run: llvm-dwarfdump -debug-info %t | FileCheck %s --check-prefix=CHECK-DWO
+; RUN: llc --try-experimental-debuginfo-iterators -split-dwarf-file=foo.dwo -O0 %s -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o %t
+; RUN: llvm-dwarfdump -debug-info %t | FileCheck %s --check-prefix=CHECK-DWO
 
 ; Based on the debuginfo-tests/sret.cpp code.
 
@@ -12,8 +11,7 @@
 ; RUN: llc -O0 -fast-isel=true -mtriple=x86_64-apple-darwin -filetype=obj -o - %s | llvm-dwarfdump -debug-info - | FileCheck -check-prefixes=CHECK,FASTISEL %s
 ; RUN: llc -O0 -fast-isel=false -mtriple=x86_64-apple-darwin -filetype=obj -o - %s | llvm-dwarfdump -debug-info - | FileCheck -check-prefixes=CHECK,SDAG %s
 
-;; FIXME: RemoveDIs - enable when FastISel support is added.
-; run: llc --try-experimental-debuginfo-iterators -O0 -fast-isel=true -mtriple=x86_64-apple-darwin -filetype=obj -o - %s | llvm-dwarfdump -debug-info - | FileCheck -check-prefixes=CHECK,FASTISEL %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -fast-isel=true -mtriple=x86_64-apple-darwin -filetype=obj -o - %s | llvm-dwarfdump -debug-info - | FileCheck -check-prefixes=CHECK,FASTISEL %s
 ; RUN: llc --try-experimental-debuginfo-iterators -O0 -fast-isel=false -mtriple=x86_64-apple-darwin -filetype=obj -o - %s | llvm-dwarfdump -debug-info - | FileCheck -check-prefixes=CHECK,SDAG %s
 
 ; CHECK: _ZN1B9AInstanceEv
diff --git a/llvm/test/DebugInfo/X86/subreg.ll b/llvm/test/DebugInfo/X86/subreg.ll
index 671af9e05fe2..f826cc5a9c93 100644
--- a/llvm/test/DebugInfo/X86/subreg.ll
+++ b/llvm/test/DebugInfo/X86/subreg.ll
@@ -1,4 +1,5 @@
 ; RUN: llc %s -mtriple=x86_64-pc-linux-gnu -O0 -o - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators %s -mtriple=x86_64-pc-linux-gnu -O0 -o - | FileCheck %s
 
 ; We are testing that a value in a 16 bit register gets reported as
 ; being in its superregister.
diff --git a/llvm/test/DebugInfo/X86/subregisters.ll b/llvm/test/DebugInfo/X86/subregisters.ll
index 4e279aba3d8b..5dc5a8033f1e 100644
--- a/llvm/test/DebugInfo/X86/subregisters.ll
+++ b/llvm/test/DebugInfo/X86/subregisters.ll
@@ -1,5 +1,8 @@
 ; RUN: llc -mtriple=x86_64-apple-darwin %s -o %t.o -filetype=obj -O0
 ; RUN: llvm-dwarfdump -v %t.o | FileCheck %s
+
+; RUN: llc --try-experimental-debuginfo-iterators -mtriple=x86_64-apple-darwin %s -o %t.o -filetype=obj -O0
+; RUN: llvm-dwarfdump -v %t.o | FileCheck %s
 ;
 ; Test that on x86_64, the 32-bit subregister esi is emitted as
 ; subregister of the 64-bit rsi.
diff --git a/llvm/test/DebugInfo/X86/vla.ll b/llvm/test/DebugInfo/X86/vla.ll
index 26322ec0fdd7..f90cf2aadc71 100644
--- a/llvm/test/DebugInfo/X86/vla.ll
+++ b/llvm/test/DebugInfo/X86/vla.ll
@@ -1,4 +1,5 @@
 ; RUN: llc -O0 -mtriple=x86_64-apple-darwin -filetype=asm %s -o - | FileCheck %s
+; RUN: llc --try-experimental-debuginfo-iterators -O0 -mtriple=x86_64-apple-darwin -filetype=asm %s -o - | FileCheck %s
 ; Ensure that we generate an indirect location for the variable length array a.
 ; CHECK: ##DEBUG_VALUE: vla:a <- [DW_OP_deref] [{{\$r[a-z]+}}+0]
 ; CHECK: DW_OP_breg{{[0-9]}}