[Assignment Tracking][21/*] Account for assignment tracking in inliner

[Orlando]

Summary

The inliner requires two additions:

fixupAssignments - Update inlined instructions' DIAssignID metadata so that inlined DIAssignID attachments are unique to the inlined instance.

trackInlinedStores - Treat inlined stores to caller-local variables (i.e. callee stores to argument pointers that point to the caller's allocas) as assignments. Track them using trackAssignments, which is the same method as is used by the AssignmentTrackingPass. This means that we're able to detect stale memory locations due to DSE after inlining. Because the stores are only tracked _after_ inlining, any DSE or movement of stores _before_ inlining will not be accounted for. This is an accepted limitation mentioned in the RFC.

One change is also required:

Update CloneBlock to preserve debug use-before-defs. Otherwise the assignments will be dropped due to having the intrinsic operands replaced with empty metadata (see use-before-def.ll in this patch and this related discourse post.

[jmorse]

Looks good, with the caveat that I think you need to explicitly check for DIAssignID nodes in the output of tests to make FileCheck notice if something is merged / distinct (see inline comments).

llvm/lib/Transforms/Utils/CloneFunction.cpp

385–389

I'd suggest not mentioning assignment tracking at all here, that won't be a consideration of the "average" reader. IMO it should be alright to curtly mention that debug intrinsics are handled later, and shift any commentary on use-before-def to wherever the debug intrinsics are maintained. (This is purely for the purpose of not burdening the reader with too much information).

719–720

Just so that I understand, vmap is a mapping from the old function to the duplicated instructions in the new -- so we're only remapping those debug intrinsics that survived the inlining?

(This seems fine to me).

llvm/lib/Transforms/Utils/InlineFunction.cpp

1564

I feel the reader will be happier if there's a typedef for this return type (visually easier to parse too).

1630

It feels like a slightly abnormal usage that Map.lookup is going to default-allocate the NewID as nullptr, so lookup also initializes. AFAIUI there's nothing wrong with this though.

llvm/test/DebugInfo/Generic/assignment-tracking/inline/id.ll

4–6

The inlined (_Z3funv) function is in the output as well -- IMO there's value in testing that it's distinct from the other IDs.

Also, unless you check at the end for the existence of two DIAssignID nodes with dedicated numbers, I think ID_0 and ID_1 can end up having the same value, and this isn't an error as far as FileCheck is concerned.

llvm/test/DebugInfo/Generic/assignment-tracking/inline/inline-stores.ll

176

As there are two variables !88 !89 in this function, shouldn't we check for both variables in the CHECK lines?

215

As with earlier, you'll need to check for DIAssignID nodes to ensure that none are merged / duplicated accidentally.

llvm/test/DebugInfo/Generic/assignment-tracking/inline/use-before-def.ll

20–23

SGTM -- having a well defined meaning for this kind of scenario is exactly the outcome we should see from treating assignments as assignments in the compiler.

[jmorse]

(Sending back to "revise" queue given review above)

[Orlando]

+ Address review comments
+ Remove tbaa from tests

Should I move the preservation of use-before-defs to separate patch since it affects dbg.values too?

llvm/lib/Transforms/Utils/CloneFunction.cpp

385–389

Is this OK?

719–720

Just so that I understand, vmap is a mapping from the old function to the duplicated instructions in the new

I believe so.

so we're only remapping those debug intrinsics that survived the inlining?

What do you mean by survived the inlining?

llvm/lib/Transforms/Utils/InlineFunction.cpp

1564

Added StorageToVarsMap in D132225 but hadn't gotten round to updating this yet. Done.

1630

The DenseMap::lookup docu-comment says Return the entry for the specified key, or a default constructed value if no such entry exists so I figured it was ok.

llvm/test/DebugInfo/Generic/assignment-tracking/inline/id.ll

4–6

Good point, done.

llvm/test/DebugInfo/Generic/assignment-tracking/inline/inline-stores.ll

176

This test is just checking that the inlined stores are tracked correctly (e.g. the dbg.assign for f5_param that already exists in f5 prior to inlining isn't checked for here either). I think there's value in keeping this test targeted - wdyt?

[jmorse]

LGTM with a couple of suggestions. The bigger comment is me asking "have you considered what happens when the inliner deletes random elements of assignment tracking due to pruning" -- I don't think there's anything that would be broken, just checking that we have a common understanding.

llvm/lib/Transforms/Utils/CloneFunction.cpp

719–720

What do you mean by survived the inlining?

Blocks that are determined to be unreachable during inlining are pruned away and, presumably, their debug intrinsics don't get cloned into the new function, hence it's possible for the lookup of DVI in VMap to be null. I think I wrote this comment to see if that was a code path you'd considered, in case dbg.assigns need to behave differently when things are pruned.

It's possible for blocks containing dbg.assigns to be pruned, but that should act the same as any old dead code elimination. It's probably not possible for blocks containing allocas with DIAssignIDs to be pruned but corresponding dbg.assigns not be pruned -- the dbg.assigns will be in blocks dominated by the alloca. Presumably nothing goes wrong if there are dbg.assigns with linked stores that don't get cloned, or vice versa.

llvm/lib/Transforms/Utils/InlineFunction.cpp

1602–1604

Would a clearer test be !DAI->getDebugLoc().getInlinedAt()? (I think they're basically the same thing, doesn't really matter)

llvm/test/DebugInfo/Generic/assignment-tracking/inline/inline-stores.ll

223

Check for existence of "inlinedAt" too, even if we don't really care about the node?

[Orlando]

Thanks!

llvm/lib/Transforms/Utils/CloneFunction.cpp

719–720

Yeah, that should all be okay.

llvm/lib/Transforms/Utils/InlineFunction.cpp

1602–1604

That looks right (well, inverted) - done.

llvm/test/DebugInfo/Generic/assignment-tracking/inline/inline-stores.ll

223

We actually don't want inlinedAt here - the dbg.assign that is inserted is for the caller's variable (and the variable and dbg intrinsic scopes need to match). I've updated the CHECK line to explicitly check against seeing an inlinedAt field.

llvm/lib/Transforms/Utils/CloneFunction.cpp

void PruningFunctionCloner::CloneBlock(
   // Loop over all instructions, and copy them over, DCE'ing as we go.  This
   // loop doesn't include the terminator.
   for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end(); II != IE;
        ++II) {
 
     Instruction *NewInst = II->clone();
 
     // Eagerly remap operands to the newly cloned instruction, except for PHI
-    // nodes for which we defer processing until we update the CFG.
-    if (!isa<PHINode>(NewInst)) {
+    // nodes for which we defer processing until we update the CFG. Also skip
+    // debug intrinsics because we should preserve use-before-defs, which are
+    // well(-ish) defined and explicitly well defined for assignment
+    // tracking. To preserve use-before-defs we must remap debug intrinsic
+    // operands after all values have been mapped.
+    if (!isa<PHINode>(NewInst) && !isa<DbgVariableIntrinsic>(NewInst)) {
       RemapInstruction(NewInst, VMap,
                        ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
 
       // If we can simplify this instruction to some other value, simply add
       // a mapping to that value rather than inserting a new instruction into
       // the basic block.
       if (Value *V =
               SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) {
#endif
   const BasicBlock *StartingBB;
   if (StartingInst)
     StartingBB = StartingInst->getParent();
   else {
     StartingBB = &OldFunc->getEntryBlock();
     StartingInst = &StartingBB->front();
   }
 
+  // Collect debug intrinsics for remapping later.
+  SmallVector<const DbgVariableIntrinsic *, 8> DbgIntrinsics;
+  for (const auto &BB : *OldFunc) {
+    for (const auto &I : BB) {
+      if (const auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I))
+        DbgIntrinsics.push_back(DVI);
+    }
+  }
+
   // Clone the entry block, and anything recursively reachable from it.
   std::vector<const BasicBlock *> CloneWorklist;
   PFC.CloneBlock(StartingBB, StartingInst->getIterator(), CloneWorklist);
   while (!CloneWorklist.empty()) {
     const BasicBlock *BB = CloneWorklist.back();
     CloneWorklist.pop_back();
     PFC.CloneBlock(BB, BB->begin(), CloneWorklist);
   }
for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
 
     // If the original instruction had no side effects, remove it.
     if (isInstructionTriviallyDead(I))
       I->eraseFromParent();
     else
       VMap[OrigV] = I;
   }
 
+  // Remap debug intrinsic operands now that all values have been mapped.
+  // Doing this now (late) preserves use-before-defs in debug intrinsics. If
+  // we didn't do this, ValueAsMetadata(use-before-def) operands would be
+  // replaced by empty metadata. This would signal later cleanup passes to
+  // remove the debug intrinsics, potentially causing incorrect locations.
+  for (const auto *DVI : DbgIntrinsics) {
+    if (DbgVariableIntrinsic *NewDVI =
+            cast_or_null<DbgVariableIntrinsic>(VMap.lookup(DVI)))
+      RemapInstruction(NewDVI, VMap,
+                       ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
+                       TypeMapper, Materializer);
+  }
+
   // Simplify conditional branches and switches with a constant operand. We try
   // to prune these out when cloning, but if the simplification required
   // looking through PHI nodes, those are only available after forming the full
   // basic block. That may leave some here, and we still want to prune the dead
   // code as early as possible.
   Function::iterator Begin = cast<BasicBlock>(VMap[StartingBB])->getIterator();
   for (BasicBlock &BB : make_range(Begin, NewFunc->end()))
     ConstantFoldTerminator(&BB);

llvm/lib/Transforms/Utils/InlineFunction.cpp

if (NoInlineLineTables) {
         }
         ++BI;
       }
     }
 
   }
 }
 
+
+#define DEBUG_TYPE "assignment-tracking"
+/// Find Alloca and linked DbgAssignIntrinsic for locals escaped by \p CB.
+static DenseMap<const AllocaInst *, SmallSet<at::VarRecord, 2>>
+collectEscapedLocals(const DataLayout &DL, const CallBase &CB) {
+  DenseMap<const AllocaInst *, SmallSet<at::VarRecord, 2>> EscapedLocals;
+  SmallPtrSet<const Value *, 4> SeenBases;
+
+  LLVM_DEBUG(
+      errs() << "# Finding caller local variables escaped by callee\n");
+  for (const Value *Arg : CB.args()) {
+    LLVM_DEBUG(errs() << "INSPECT: " << *Arg << "\n");
+    if (!Arg->getType()->isPointerTy()) {
+      LLVM_DEBUG(errs() << " | SKIP: Not a pointer\n");
+      continue;
+    }
+
+    const Instruction *I = dyn_cast<Instruction>(Arg);
+    if (!I) {
+      LLVM_DEBUG(errs() << " | SKIP: Not result of instruction\n");
+      continue;
+    }
+
+    // Walk back to the base storage.
+    assert(Arg->getType()->isPtrOrPtrVectorTy());
+    APInt TmpOffset(DL.getIndexTypeSizeInBits(Arg->getType()), 0, false);
+    const AllocaInst *Base = dyn_cast<AllocaInst>(
+        Arg->stripAndAccumulateConstantOffsets(DL, TmpOffset, true));
+    if (!Base) {
+      LLVM_DEBUG(errs() << " | SKIP: Couldn't walk back to base storage\n");
+      continue;
+    }
+
+    assert(Base);
+    LLVM_DEBUG(errs() << " | BASE: " << *Base << "\n");
+    // We only need to process each base address once - skip any duplicates.
+    if (!SeenBases.insert(Base).second)
+      continue;
+
+    // Find all local variables associated with the backing storage.
+    for (auto *DAI : at::getAssignmentMarkers(Base)) {
+      // Skip variables from inlined functions - they are not local variables.
+      if (DAI->getVariable()->getScope()->getSubprogram() !=
+          CB.getFunction()->getSubprogram())
+        continue;
+      LLVM_DEBUG(errs() << " > DEF : " << *DAI << "\n");
+      EscapedLocals[Base].insert(at::VarRecord(DAI));
+    }
+  }
+  return EscapedLocals;
+}
+
+static void trackInlinedStores(Function::iterator Start, Function::iterator End,
+                               const CallBase &CB) {
+  LLVM_DEBUG(errs() << "trackInlinedStores into "
+                    << Start->getParent()->getName() << " from "
+                    << CB.getCalledFunction()->getName() << "\n");
+  std::unique_ptr<DataLayout> DL = std::make_unique<DataLayout>(CB.getModule());
+  at::trackAssignments(Start, End, collectEscapedLocals(*DL, CB), *DL);
+}
+
+/// Update inlined instructions' DIAssignID metadata. We need to do this
+/// otherwise a function inlined more than once into the same function
+/// will cause DIAssignID to be shared by many instructions.
+static void fixupAssignments(Function::iterator Start, Function::iterator End) {
+  // Map {Old, New} metadata. Not used directly - use GetNewID.
+  DenseMap<DIAssignID *, DIAssignID *> Map;
+  auto GetNewID = [&Map](Metadata *Old) {
+    DIAssignID *OldID = cast<DIAssignID>(Old);
+    if (DIAssignID *NewID = Map.lookup(OldID))
+      return NewID;
+    DIAssignID *NewID = DIAssignID::getDistinct(OldID->getContext());
+    Map[OldID] = NewID;
+    return NewID;
+  };
+  // Loop over all the inlined instructions. If we find a DIAssignID
+  // attachment or use, replace it with a new version.
+  for (auto BBI = Start; BBI != End; ++BBI) {
+    for (Instruction &I : *BBI) {
+      if (auto *ID = I.getMetadata(LLVMContext::MD_DIAssignID))
+        I.setMetadata(LLVMContext::MD_DIAssignID, GetNewID(ID));
+      else if (auto *DAI = dyn_cast<DbgAssignIntrinsic>(&I))
+        DAI->setAssignId(GetNewID(DAI->getAssignId()));
+    }
+  }
+}
+#undef DEBUG_TYPE
+
 /// Update the block frequencies of the caller after a callee has been inlined.
 ///
 /// Each block cloned into the caller has its block frequency scaled by the
 /// ratio of CallSiteFreq/CalleeEntryFreq. This ensures that the cloned copy of
 /// callee's entry block gets the same frequency as the callsite block and the
 /// relative frequencies of all cloned blocks remain the same after cloning.
 static void updateCallerBFI(BasicBlock *CallSiteBlock,
                             const ValueToValueMapTy &VMap,
if (IFI.CG)
       UpdateCallGraphAfterInlining(CB, FirstNewBlock, VMap, IFI);
 
     // For 'nodebug' functions, the associated DISubprogram is always null.
     // Conservatively avoid propagating the callsite debug location to
     // instructions inlined from a function whose DISubprogram is not null.
     fixupLineNumbers(Caller, FirstNewBlock, &CB,
                      CalledFunc->getSubprogram() != nullptr);
 
+    if (getEnableAssignmentTracking()) {
+      // Interpret inlined stores to caller-local variables as assignments.
+      trackInlinedStores(FirstNewBlock, Caller->end(), CB);
+
+      // Update DIAssignID metadata attachments and uses so that they are
+      // unique to this inlined instance.
+      fixupAssignments(FirstNewBlock, Caller->end());
+    }
+
     // Now clone the inlined noalias scope metadata.
     SAMetadataCloner.clone();
     SAMetadataCloner.remap(FirstNewBlock, Caller->end());
 
     // Add noalias metadata if necessary.
     AddAliasScopeMetadata(CB, VMap, DL, CalleeAAR, InlinedFunctionInfo);
 
     // Clone return attributes on the callsite into the calls within the inlined

llvm/test/DebugInfo/Generic/assignment-tracking/inline/id.ll

+; RUN: opt %s -S -passes=inline -o - -experimental-assignment-tracking \
+; RUN: | FileCheck %s
+
+;; Check that all DIAssignID metadata that are inlined are replaced with new
+;; versions. Otherwise two inlined instances of an assignment will be considered
+;; to be the same assignment.
+;;
+;; $cat test.cpp
+;; __attribute__((always_inline))
+;; int get() { int val = 5; return val; }
+;; void fun() {
+;;   get();
+;;   get();
+;; }
+
+; CHECK-LABEL: _Z3funv
+;
+; CHECK: store i32 5, i32* %val.i, align 4{{.*}}, !DIAssignID [[ID_0:![0-9]+]]
+; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 5, metadata [[val:![0-9]+]], metadata !DIExpression(), metadata [[ID_0]], metadata i32* %val.i, metadata !DIExpression()), !dbg [[dl_inline_0:![0-9]+]]
+;
+; CHECK: store i32 5, i32* %val.i1, align 4{{.*}}, !DIAssignID [[ID_1:![0-9]+]]
+; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 5, metadata [[val]], metadata !DIExpression(), metadata [[ID_1]], metadata i32* %val.i1, metadata !DIExpression()), !dbg [[dl_inline_1:![0-9]+]]
+;
+; CHECK-DAG: [[val]] = !DILocalVariable(name: "val",
+; CHECK-DAG: [[dl_inline_0]] = !DILocation({{.*}}inlinedAt
+; CHECK-DAG: [[dl_inline_1]] = !DILocation({{.*}}inlinedAt
+
+define dso_local i32 @_Z3getv() !dbg !7 {
+entry:
+  %val = alloca i32, align 4, !DIAssignID !13
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !12, metadata !DIExpression(), metadata !13, metadata i32* %val, metadata !DIExpression()), !dbg !14
+  %0 = bitcast i32* %val to i8*, !dbg !15
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0), !dbg !15
+  store i32 5, i32* %val, align 4, !dbg !16, !tbaa !17, !DIAssignID !21
+  call void @llvm.dbg.assign(metadata i32 5, metadata !12, metadata !DIExpression(), metadata !21, metadata i32* %val, metadata !DIExpression()), !dbg !14
+  %1 = load i32, i32* %val, align 4, !dbg !22, !tbaa !17
+  %2 = bitcast i32* %val to i8*, !dbg !23
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %2), !dbg !23
+  ret i32 %1, !dbg !24
+}
+
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture)
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture)
+declare void @llvm.dbg.assign(metadata, metadata, metadata, metadata, metadata, metadata)
+
+; Function Attrs: nounwind uwtable mustprogress
+define dso_local void @_Z3funv() !dbg !25 {
+entry:
+  %call = call i32 @_Z3getv(), !dbg !28
+  %call1 = call i32 @_Z3getv(), !dbg !29
+  ret void, !dbg !30
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 12.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 12.0.0"}
+!7 = distinct !DISubprogram(name: "get", linkageName: "_Z3getv", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !{!12}
+!12 = !DILocalVariable(name: "val", scope: !7, file: !1, line: 2, type: !10)
+!13 = distinct !DIAssignID()
+!14 = !DILocation(line: 0, scope: !7)
+!15 = !DILocation(line: 2, column: 13, scope: !7)
+!16 = !DILocation(line: 2, column: 17, scope: !7)
+!17 = !{!18, !18, i64 0}
+!18 = !{!"int", !19, i64 0}
+!19 = !{!"omnipotent char", !20, i64 0}
+!20 = !{!"Simple C++ TBAA"}
+!21 = distinct !DIAssignID()
+!22 = !DILocation(line: 2, column: 33, scope: !7)
+!23 = !DILocation(line: 2, column: 38, scope: !7)
+!24 = !DILocation(line: 2, column: 26, scope: !7)
+!25 = distinct !DISubprogram(name: "fun", linkageName: "_Z3funv", scope: !1, file: !1, line: 3, type: !26, scopeLine: 3, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!26 = !DISubroutineType(types: !27)
+!27 = !{null}
+!28 = !DILocation(line: 4, column: 3, scope: !25)
+!29 = !DILocation(line: 5, column: 3, scope: !25)
+!30 = !DILocation(line: 6, column: 1, scope: !25)

llvm/test/DebugInfo/Generic/assignment-tracking/inline/inline-stores.ll

+; RUN: opt -passes=inline %s -S -o - -experimental-assignment-tracking \
+; RUN: | FileCheck %s
+
+;; $ cat test.cpp
+;; __attribute__((always_inline))
+;; static void a(int* p2, int v2) { *p2 = v2; }
+;;
+;; __attribute__((always_inline))
+;; void b(int* p1, int v1) { a(p1, v1); }
+;;
+;; int f1() {
+;;   int f1_local;
+;;   a(&f1_local, 1);
+;;   return f1_local;
+;; }
+;;
+;; int f2() {
+;;   int f2_local[2];
+;;   a(f2_local, 2);
+;;   return f2_local[0];
+;; }
+;;
+;; int f3() {
+;;   int f3_local[2];
+;;   a(f3_local + 1, 3);
+;;   return f3_local[1];
+;; }
+;;
+;; int f4(int f4_param) {
+;;   a(&f4_param, 4);
+;;   return f4_param;
+;; }
+;;
+;; int f5(int f5_param) {
+;;   int &f5_alias = f5_param;
+;;   a(&f5_alias, 5);
+;;   return f5_param;
+;; }
+;;
+;; int f6() {
+;;   int f6_local;
+;;   b(&f6_local, 6);
+;;   return f6_local;
+;; }
+;;
+;; IR generated with:
+;; $ clang++ -Xclang -disable-llvm-passes test.cpp -g -O2 -o - -S -emit-llvm \
+;;   | opt -passes=declare-to-assign,sroa -o - -S
+;;
+;; Check that inlined stores are tracked as assignments. FileCheck directives
+;; inline.
+
+source_filename = "test.cpp"
+define dso_local void @_Z1bPii(i32* %p1, i32 %v1) #0 !dbg !7 {
+entry:
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !13, metadata !DIExpression(), metadata !15, metadata i32** undef, metadata !DIExpression()), !dbg !16
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !14, metadata !DIExpression(), metadata !17, metadata i32* undef, metadata !DIExpression()), !dbg !16
+  call void @llvm.dbg.assign(metadata i32* %p1, metadata !13, metadata !DIExpression(), metadata !18, metadata i32** undef, metadata !DIExpression()), !dbg !16
+  call void @llvm.dbg.assign(metadata i32 %v1, metadata !14, metadata !DIExpression(), metadata !19, metadata i32* undef, metadata !DIExpression()), !dbg !16
+  call void @_ZL1aPii(i32* %p1, i32 %v1), !dbg !20
+  ret void, !dbg !21
+}
+
+define internal void @_ZL1aPii(i32* %p2, i32 %v2) #2 !dbg !22 {
+entry:
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !24, metadata !DIExpression(), metadata !26, metadata i32** undef, metadata !DIExpression()), !dbg !27
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !25, metadata !DIExpression(), metadata !28, metadata i32* undef, metadata !DIExpression()), !dbg !27
+  call void @llvm.dbg.assign(metadata i32* %p2, metadata !24, metadata !DIExpression(), metadata !29, metadata i32** undef, metadata !DIExpression()), !dbg !27
+  call void @llvm.dbg.assign(metadata i32 %v2, metadata !25, metadata !DIExpression(), metadata !30, metadata i32* undef, metadata !DIExpression()), !dbg !27
+  store i32 %v2, i32* %p2, align 4, !dbg !31, !tbaa !32
+  ret void, !dbg !36
+}
+
+;; Store directly to local with one level of inlining. Also record f1_dbg to
+;; check that the dbg.assign gets the correct scope after inlining. This check
+;; isn't repeated for the other functions.
+;; int f1() {
+;;   int f1_local;
+;;   a(&f1_local, 1);
+;;   return f1_local;
+;; }
+;;
+; CHECK-LABEL: define dso_local i32 @_Z2f1v()
+; CHECK:       store i32 1, i32* %f1_local, align 4,{{.*}} !DIAssignID ![[ID_1:[0-9]+]]
+; CHECK-NEXT:  call void @llvm.dbg.assign(metadata i32 1, metadata ![[f1_local:[0-9]+]], metadata !DIExpression(), metadata ![[ID_1]], metadata i32* %f1_local, metadata !DIExpression()), !dbg ![[f1_dbg:[0-9]+]]
+define dso_local i32 @_Z2f1v() #3 !dbg !37 {
+entry:
+  %f1_local = alloca i32, align 4, !DIAssignID !42
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !41, metadata !DIExpression(), metadata !42, metadata i32* %f1_local, metadata !DIExpression()), !dbg !43
+  %0 = bitcast i32* %f1_local to i8*, !dbg !44
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #5, !dbg !44
+  call void @_ZL1aPii(i32* %f1_local, i32 1), !dbg !45
+  %1 = load i32, i32* %f1_local, align 4, !dbg !46, !tbaa !32
+  %2 = bitcast i32* %f1_local to i8*, !dbg !47
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %2) #5, !dbg !47
+  ret i32 %1, !dbg !48
+}
+
+;; Store directly to fragment of local at its base address.
+;; int f2() {
+;;   int f2_local[2];
+;;   a(f2_local, 2);
+;;   return f2_local[0];
+;; }
+;;
+; CHECK-LABEL: define dso_local i32 @_Z2f2v()
+; CHECK:       store i32 2, i32* %arraydecay, align 4,{{.*}} !DIAssignID ![[ID_2:[0-9]+]]
+; CHECK-NEXT:  call void @llvm.dbg.assign(metadata i32 2, metadata ![[f2_local:[0-9]+]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32), metadata ![[ID_2]], metadata i32* %arraydecay, metadata !DIExpression())
+define dso_local i32 @_Z2f2v() #3 !dbg !49 {
+entry:
+  %f2_local = alloca [2 x i32], align 4, !DIAssignID !55
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !51, metadata !DIExpression(), metadata !55, metadata [2 x i32]* %f2_local, metadata !DIExpression()), !dbg !56
+  %0 = bitcast [2 x i32]* %f2_local to i8*, !dbg !57
+  call void @llvm.lifetime.start.p0i8(i64 8, i8* %0) #5, !dbg !57
+  %arraydecay = getelementptr inbounds [2 x i32], [2 x i32]* %f2_local, i64 0, i64 0, !dbg !58
+  call void @_ZL1aPii(i32* %arraydecay, i32 2), !dbg !59
+  %arrayidx = getelementptr inbounds [2 x i32], [2 x i32]* %f2_local, i64 0, i64 0, !dbg !60
+  %1 = load i32, i32* %arrayidx, align 4, !dbg !60, !tbaa !32
+  %2 = bitcast [2 x i32]* %f2_local to i8*, !dbg !61
+  call void @llvm.lifetime.end.p0i8(i64 8, i8* %2) #5, !dbg !61
+  ret i32 %1, !dbg !62
+}
+
+;; Store to fragment of local using rvalue offset as argument.
+;; int f3() {
+;;   int f3_local[2];
+;;   a(f3_local + 1, 3);
+;;   return f3_local[1];
+;; }
+; CHECK-LABEL: define dso_local i32 @_Z2f3v()
+; CHECK:       store i32 3, i32* %add.ptr, align 4,{{.*}} !DIAssignID ![[ID_3:[0-9]+]]
+; CHECK-NEXT:  call void @llvm.dbg.assign(metadata i32 3, metadata ![[f3_local:[0-9]+]], metadata !DIExpression(DW_OP_LLVM_fragment, 32, 32), metadata ![[ID_3]], metadata i32* %add.ptr, metadata !DIExpression())
+define dso_local i32 @_Z2f3v() #3 !dbg !63 {
+entry:
+  %f3_local = alloca [2 x i32], align 4, !DIAssignID !66
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !65, metadata !DIExpression(), metadata !66, metadata [2 x i32]* %f3_local, metadata !DIExpression()), !dbg !67
+  %0 = bitcast [2 x i32]* %f3_local to i8*, !dbg !68
+  call void @llvm.lifetime.start.p0i8(i64 8, i8* %0) #5, !dbg !68
+  %arraydecay = getelementptr inbounds [2 x i32], [2 x i32]* %f3_local, i64 0, i64 0, !dbg !69
+  %add.ptr = getelementptr inbounds i32, i32* %arraydecay, i64 1, !dbg !70
+  call void @_ZL1aPii(i32* %add.ptr, i32 3), !dbg !71
+  %arrayidx = getelementptr inbounds [2 x i32], [2 x i32]* %f3_local, i64 0, i64 1, !dbg !72
+  %1 = load i32, i32* %arrayidx, align 4, !dbg !72, !tbaa !32
+  %2 = bitcast [2 x i32]* %f3_local to i8*, !dbg !73
+  call void @llvm.lifetime.end.p0i8(i64 8, i8* %2) #5, !dbg !73
+  ret i32 %1, !dbg !74
+}
+
+;; Store to parameter directly.
+;; int f4(int f4_param) {
+;;   a(&f4_param, 4);
+;;   return f4_param;
+;; }
+; CHECK-LABEL: define dso_local i32 @_Z2f4i(i32 %f4_param)
+; CHECK:       store i32 4, i32* %f4_param.addr, align 4,{{.*}} !DIAssignID ![[ID_4:[0-9]+]]
+; CHECK-NEXT:  call void @llvm.dbg.assign(metadata i32 4, metadata ![[f4_param:[0-9]+]], metadata !DIExpression(), metadata ![[ID_4]], metadata i32* %f4_param.addr, metadata !DIExpression())
+define dso_local i32 @_Z2f4i(i32 %f4_param) #3 !dbg !75 {
+entry:
+  %f4_param.addr = alloca i32, align 4, !DIAssignID !80
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !79, metadata !DIExpression(), metadata !80, metadata i32* %f4_param.addr, metadata !DIExpression()), !dbg !81
+  store i32 %f4_param, i32* %f4_param.addr, align 4, !tbaa !32, !DIAssignID !82
+  call void @llvm.dbg.assign(metadata i32 %f4_param, metadata !79, metadata !DIExpression(), metadata !82, metadata i32* %f4_param.addr, metadata !DIExpression()), !dbg !81
+  call void @_ZL1aPii(i32* %f4_param.addr, i32 4), !dbg !83
+  %0 = load i32, i32* %f4_param.addr, align 4, !dbg !84, !tbaa !32
+  ret i32 %0, !dbg !85
+}
+
+;; Store through an alias.
+;; int f5(int f5_param) {
+;;   int &f5_alias = f5_param;
+;;   a(&f5_alias, 5);
+;;   return f5_param;
+;; }
+; CHECK-LABEL: define dso_local i32 @_Z2f5i(i32 %f5_param)
+; CHECK:       store i32 5, i32* %f5_param.addr, align 4,{{.*}}!DIAssignID ![[ID_5:[0-9]+]]
+; CHECK-NEXT:  call void @llvm.dbg.assign(metadata i32 5, metadata ![[f5_param:[0-9]+]], metadata !DIExpression(), metadata ![[ID_5]], metadata i32* %f5_param.addr, metadata !DIExpression())
+define dso_local i32 @_Z2f5i(i32 %f5_param) #3 !dbg !86 {
+entry:
+  %f5_param.addr = alloca i32, align 4, !DIAssignID !91
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !88, metadata !DIExpression(), metadata !91, metadata i32* %f5_param.addr, metadata !DIExpression()), !dbg !92
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !89, metadata !DIExpression(), metadata !93, metadata i32** undef, metadata !DIExpression()), !dbg !92
+  store i32 %f5_param, i32* %f5_param.addr, align 4, !tbaa !32, !DIAssignID !94
+  call void @llvm.dbg.assign(metadata i32 %f5_param, metadata !88, metadata !DIExpression(), metadata !94, metadata i32* %f5_param.addr, metadata !DIExpression()), !dbg !92
+  call void @llvm.dbg.assign(metadata i32* %f5_param.addr, metadata !89, metadata !DIExpression(), metadata !95, metadata i32** undef, metadata !DIExpression()), !dbg !92
+  call void @_ZL1aPii(i32* %f5_param.addr, i32 5), !dbg !96
+  %0 = load i32, i32* %f5_param.addr, align 4, !dbg !97, !tbaa !32
+  ret i32 %0, !dbg !98
+}
+
+;; int f6() {
+;;   int f6_local;
+;;   b(&f6_local, 6);
+;;   return f6_local;
+;; }
+; CHECK-LABEL: define dso_local i32 @_Z2f6v()
+; CHECK:       store i32 6, i32* %f6_local, align 4,{{.*}} !DIAssignID ![[ID_6:[0-9]+]]
+; CHECK-NEXT:  call void @llvm.dbg.assign(metadata i32 6, metadata ![[f6_local:[0-9]+]], metadata !DIExpression(), metadata ![[ID_6]], metadata i32* %f6_local, metadata !DIExpression())
+define dso_local i32 @_Z2f6v() #3 !dbg !99 {
+entry:
+  %f6_local = alloca i32, align 4, !DIAssignID !102
+  call void @llvm.dbg.assign(metadata i1 undef, metadata !101, metadata !DIExpression(), metadata !102, metadata i32* %f6_local, metadata !DIExpression()), !dbg !103
+  %0 = bitcast i32* %f6_local to i8*, !dbg !104
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #5, !dbg !104
+  call void @_Z1bPii(i32* %f6_local, i32 6), !dbg !105
+  %1 = load i32, i32* %f6_local, align 4, !dbg !106, !tbaa !32
+  %2 = bitcast i32* %f6_local to i8*, !dbg !107
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %2) #5, !dbg !107
+  ret i32 %1, !dbg !108
+}
+
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture)
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture)
+declare void @llvm.dbg.assign(metadata, metadata, metadata, metadata, metadata, metadata)
+
+; CHECK-DAG: ![[f1_local]] = !DILocalVariable(name: "f1_local",
+; CHECK-DAG: ![[f2_local]] = !DILocalVariable(name: "f2_local",
+; CHECK-DAG: ![[f3_local]] = !DILocalVariable(name: "f3_local",
+; CHECK-DAG: ![[f4_param]] = !DILocalVariable(name: "f4_param",
+; CHECK-DAG: ![[f5_param]] = !DILocalVariable(name: "f5_param",
+; CHECK-DAG: ![[f6_local]] = !DILocalVariable(name: "f6_local",
+
+; CHECK-DAG: ![[f1_dbg]] = !DILocation({{.*}}scope: ![[f1_scope:[0-9]+]]{{.*}})
+; CHECK-DAG: ![[f1_scope]] = distinct !DISubprogram(name: "f1",
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 12.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 12.0.0)"}
+!7 = distinct !DISubprogram(name: "b", linkageName: "_Z1bPii", scope: !1, file: !1, line: 5, type: !8, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null, !10, !11}
+!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64)
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !{!13, !14}
+!13 = !DILocalVariable(name: "p1", arg: 1, scope: !7, file: !1, line: 5, type: !10)
+!14 = !DILocalVariable(name: "v1", arg: 2, scope: !7, file: !1, line: 5, type: !11)
+!15 = distinct !DIAssignID()
+!16 = !DILocation(line: 0, scope: !7)
+!17 = distinct !DIAssignID()
+!18 = distinct !DIAssignID()
+!19 = distinct !DIAssignID()
+!20 = !DILocation(line: 5, column: 27, scope: !7)
+!21 = !DILocation(line: 5, column: 38, scope: !7)
+!22 = distinct !DISubprogram(name: "a", linkageName: "_ZL1aPii", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !23)
+!23 = !{!24, !25}
+!24 = !DILocalVariable(name: "p2", arg: 1, scope: !22, file: !1, line: 2, type: !10)
+!25 = !DILocalVariable(name: "v2", arg: 2, scope: !22, file: !1, line: 2, type: !11)
+!26 = distinct !DIAssignID()
+!27 = !DILocation(line: 0, scope: !22)
+!28 = distinct !DIAssignID()
+!29 = distinct !DIAssignID()
+!30 = distinct !DIAssignID()
+!31 = !DILocation(line: 2, column: 38, scope: !22)
+!32 = !{!33, !33, i64 0}
+!33 = !{!"int", !34, i64 0}
+!34 = !{!"omnipotent char", !35, i64 0}
+!35 = !{!"Simple C++ TBAA"}
+!36 = !DILocation(line: 2, column: 44, scope: !22)
+!37 = distinct !DISubprogram(name: "f1", linkageName: "_Z2f1v", scope: !1, file: !1, line: 7, type: !38, scopeLine: 7, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !40)
+!38 = !DISubroutineType(types: !39)
+!39 = !{!11}
+!40 = !{!41}
+!41 = !DILocalVariable(name: "f1_local", scope: !37, file: !1, line: 8, type: !11)
+!42 = distinct !DIAssignID()
+!43 = !DILocation(line: 0, scope: !37)
+!44 = !DILocation(line: 8, column: 3, scope: !37)
+!45 = !DILocation(line: 9, column: 3, scope: !37)
+!46 = !DILocation(line: 10, column: 10, scope: !37)
+!47 = !DILocation(line: 11, column: 1, scope: !37)
+!48 = !DILocation(line: 10, column: 3, scope: !37)
+!49 = distinct !DISubprogram(name: "f2", linkageName: "_Z2f2v", scope: !1, file: !1, line: 13, type: !38, scopeLine: 13, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !50)
+!50 = !{!51}
+!51 = !DILocalVariable(name: "f2_local", scope: !49, file: !1, line: 14, type: !52)
+!52 = !DICompositeType(tag: DW_TAG_array_type, baseType: !11, size: 64, elements: !53)
+!53 = !{!54}
+!54 = !DISubrange(count: 2)
+!55 = distinct !DIAssignID()
+!56 = !DILocation(line: 0, scope: !49)
+!57 = !DILocation(line: 14, column: 3, scope: !49)
+!58 = !DILocation(line: 15, column: 5, scope: !49)
+!59 = !DILocation(line: 15, column: 3, scope: !49)
+!60 = !DILocation(line: 16, column: 10, scope: !49)
+!61 = !DILocation(line: 17, column: 1, scope: !49)
+!62 = !DILocation(line: 16, column: 3, scope: !49)
+!63 = distinct !DISubprogram(name: "f3", linkageName: "_Z2f3v", scope: !1, file: !1, line: 19, type: !38, scopeLine: 19, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !64)
+!64 = !{!65}
+!65 = !DILocalVariable(name: "f3_local", scope: !63, file: !1, line: 20, type: !52)
+!66 = distinct !DIAssignID()
+!67 = !DILocation(line: 0, scope: !63)
+!68 = !DILocation(line: 20, column: 3, scope: !63)
+!69 = !DILocation(line: 21, column: 5, scope: !63)
+!70 = !DILocation(line: 21, column: 14, scope: !63)
+!71 = !DILocation(line: 21, column: 3, scope: !63)
+!72 = !DILocation(line: 22, column: 10, scope: !63)
+!73 = !DILocation(line: 23, column: 1, scope: !63)
+!74 = !DILocation(line: 22, column: 3, scope: !63)
+!75 = distinct !DISubprogram(name: "f4", linkageName: "_Z2f4i", scope: !1, file: !1, line: 25, type: !76, scopeLine: 25, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !78)
+!76 = !DISubroutineType(types: !77)
+!77 = !{!11, !11}
+!78 = !{!79}
+!79 = !DILocalVariable(name: "f4_param", arg: 1, scope: !75, file: !1, line: 25, type: !11)
+!80 = distinct !DIAssignID()
+!81 = !DILocation(line: 0, scope: !75)
+!82 = distinct !DIAssignID()
+!83 = !DILocation(line: 26, column: 3, scope: !75)
+!84 = !DILocation(line: 27, column: 10, scope: !75)
+!85 = !DILocation(line: 27, column: 3, scope: !75)
+!86 = distinct !DISubprogram(name: "f5", linkageName: "_Z2f5i", scope: !1, file: !1, line: 30, type: !76, scopeLine: 30, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !87)
+!87 = !{!88, !89}
+!88 = !DILocalVariable(name: "f5_param", arg: 1, scope: !86, file: !1, line: 30, type: !11)
+!89 = !DILocalVariable(name: "f5_alias", scope: !86, file: !1, line: 31, type: !90)
+!90 = !DIDerivedType(tag: DW_TAG_reference_type, baseType: !11, size: 64)
+!91 = distinct !DIAssignID()
+!92 = !DILocation(line: 0, scope: !86)
+!93 = distinct !DIAssignID()
+!94 = distinct !DIAssignID()
+!95 = distinct !DIAssignID()
+!96 = !DILocation(line: 32, column: 3, scope: !86)
+!97 = !DILocation(line: 33, column: 10, scope: !86)
+!98 = !DILocation(line: 33, column: 3, scope: !86)
+!99 = distinct !DISubprogram(name: "f6", linkageName: "_Z2f6v", scope: !1, file: !1, line: 36, type: !38, scopeLine: 36, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !100)
+!100 = !{!101}
+!101 = !DILocalVariable(name: "f6_local", scope: !99, file: !1, line: 37, type: !11)
+!102 = distinct !DIAssignID()
+!103 = !DILocation(line: 0, scope: !99)
+!104 = !DILocation(line: 37, column: 3, scope: !99)
+!105 = !DILocation(line: 38, column: 3, scope: !99)
+!106 = !DILocation(line: 39, column: 10, scope: !99)
+!107 = !DILocation(line: 40, column: 1, scope: !99)
+!108 = !DILocation(line: 39, column: 3, scope: !99)

llvm/test/DebugInfo/Generic/assignment-tracking/inline/use-before-def.ll

+; RUN: opt -passes=inline %s -S -o - -experimental-assignment-tracking \
+; RUN: | FileCheck %s
+
+;; Hand modified from:
+;; $ cat test.c
+;; int g = 5;
+;; static int callee() {
+;;   int local = g;
+;;   return local;
+;; }
+;;
+;; int fun() {
+;;   return callee();
+;; }
+;;
+;; IR grabbed before inlining in:
+;;     $ clang++ -O2 -g
+;; Then modified (see comment in body).
+
+;; NOTE: Although this reproducer is contrived, this has been observed in real
+;; builds with assignment tracking (dbg.assign intrinsics) - in fact, it caused
+;; verifier failures in some cases using assignment tracking (good). This is
+;; the simplest test I could write.
+
+;; use-before-defs in debug intrinsics should be preserved through inlining,
+;; or at the very least should be converted to undefs. The previous behaviour
+;; was to replace the use-before-def operand with empty metadata, which signals
+;; cleanup passes that it's okay to remove the debug intrinsic (bad). Check
+;; that this no longer happens.
+
+; CHECK: define dso_local i32 @fun()
+; CHECK-NEXT: entry
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 %0
+
+@g = dso_local local_unnamed_addr global i32 5, align 4, !dbg !0
+
+define dso_local i32 @fun() local_unnamed_addr #0 !dbg !11 {
+entry:
+  %call = call fastcc i32 @callee(), !dbg !14
+  ret i32 %call, !dbg !15
+}
+
+define internal fastcc i32 @callee() unnamed_addr #1 !dbg !16 {
+entry:
+  ;; dbg.value moved here from after %0 def.
+  call void @llvm.dbg.value(metadata i32 %0, metadata !18, metadata !DIExpression()), !dbg !24
+  %0 = load i32, i32* @g, align 4, !dbg !19, !tbaa !20
+  ret i32 %0, !dbg !25
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!7, !8, !9}
+!llvm.ident = !{!10}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "g", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 12.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, splitDebugInlining: false, nameTableKind: None)
+!3 = !DIFile(filename: "test.c", directory: "/")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = !{i32 7, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{!"clang version 12.0.0"}
+!11 = distinct !DISubprogram(name: "fun", scope: !3, file: !3, line: 7, type: !12, scopeLine: 7, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4)
+!12 = !DISubroutineType(types: !13)
+!13 = !{!6}
+!14 = !DILocation(line: 8, column: 10, scope: !11)
+!15 = !DILocation(line: 8, column: 3, scope: !11)
+!16 = distinct !DISubprogram(name: "callee", scope: !3, file: !3, line: 2, type: !12, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !17)
+!17 = !{!18}
+!18 = !DILocalVariable(name: "local", scope: !16, file: !3, line: 3, type: !6)
+!19 = !DILocation(line: 3, column: 15, scope: !16)
+!20 = !{!21, !21, i64 0}
+!21 = !{!"int", !22, i64 0}
+!22 = !{!"omnipotent char", !23, i64 0}
+!23 = !{!"Simple C/C++ TBAA"}
+!24 = !DILocation(line: 0, scope: !16)
+!25 = !DILocation(line: 4, column: 3, scope: !16)