llvm · SLTozer · Jun 12, 2025 · Sep 4, 2024 · May 1, 2025 · Jun 10, 2025
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h b/llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h
@@ -100,8 +100,8 @@ class LegalizationArtifactCombiner {
       const LLT DstTy = MRI.getType(DstReg);
       if (isInstLegal({TargetOpcode::G_CONSTANT, {DstTy}})) {
         auto &CstVal = SrcMI->getOperand(1);
-        auto *MergedLocation = DILocation::getMergedLocation(
-            MI.getDebugLoc().get(), SrcMI->getDebugLoc().get());
+        auto MergedLocation =
+            DebugLoc::getMergedLocation(MI.getDebugLoc(), SrcMI->getDebugLoc());
         // Set the debug location to the merged location of the SrcMI and the MI
         // if the aext fold is successful.
         Builder.setDebugLoc(MergedLocation);

diff --git a/llvm/include/llvm/IR/DebugLoc.h b/llvm/include/llvm/IR/DebugLoc.h
@@ -142,6 +142,31 @@ namespace llvm {
     static inline DebugLoc getDropped() { return DebugLoc(); }
 #endif // LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
 
+    static DebugLoc getMergedLocations(ArrayRef<DebugLoc> Locs);
+    static DebugLoc getMergedLocation(DebugLoc LocA, DebugLoc LocB);
+
+    /// If this DebugLoc is non-empty, returns this DebugLoc; otherwise, selects
+    /// \p Other.
+    /// In coverage-tracking builds, this also accounts for whether this or
+    /// \p Other have an annotative DebugLocKind applied, such that if both are
+    /// empty but exactly one has an annotation, we prefer that annotated
+    /// location.
+    DebugLoc orElse(DebugLoc Other) const {
+      if (*this)
+        return *this;
+#if LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
+      if (Other)
+        return Other;
+      if (getKind() != DebugLocKind::Normal)
+        return *this;
+      if (Other.getKind() != DebugLocKind::Normal)
+        return Other;
+      return *this;
+#else
+      return Other;
+#endif // LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
+    }
+
     /// Get the underlying \a DILocation.
     ///
     /// \pre !*this or \c isa<DILocation>(getAsMDNode()).

diff --git a/llvm/include/llvm/IR/IRBuilder.h b/llvm/include/llvm/IR/IRBuilder.h
@@ -113,12 +113,19 @@ class FMFSource {
 /// Common base class shared among various IRBuilders.
 class IRBuilderBase {
   /// Pairs of (metadata kind, MDNode *) that should be added to all newly
-  /// created instructions, like !dbg metadata.
+  /// created instructions, excluding !dbg metadata, which is stored in the
+  /// StoredDL field.
   SmallVector<std::pair<unsigned, MDNode *>, 2> MetadataToCopy;
+  /// The DebugLoc that will be applied to instructions inserted by this
+  /// builder.
+  DebugLoc StoredDL;
 
   /// Add or update the an entry (Kind, MD) to MetadataToCopy, if \p MD is not
   /// null. If \p MD is null, remove the entry with \p Kind.
   void AddOrRemoveMetadataToCopy(unsigned Kind, MDNode *MD) {
+    assert(Kind != LLVMContext::MD_dbg &&
+           "MD_dbg metadata must be stored in StoredDL");
+
     if (!MD) {
       erase_if(MetadataToCopy, [Kind](const std::pair<unsigned, MDNode *> &KV) {
         return KV.first == Kind;
@@ -238,7 +245,9 @@ class IRBuilderBase {
 
   /// Set location information used by debugging information.
   void SetCurrentDebugLocation(DebugLoc L) {
-    AddOrRemoveMetadataToCopy(LLVMContext::MD_dbg, L.getAsMDNode());
+    // For !dbg metadata attachments, we use DebugLoc instead of the raw MDNode
+    // to include optional introspection data for use in Debugify.
+    StoredDL = std::move(L);
   }
 
   /// Set nosanitize metadata.
@@ -252,8 +261,12 @@ class IRBuilderBase {
   /// not on \p Src will be dropped from MetadataToCopy.
   void CollectMetadataToCopy(Instruction *Src,
                              ArrayRef<unsigned> MetadataKinds) {
-    for (unsigned K : MetadataKinds)
-      AddOrRemoveMetadataToCopy(K, Src->getMetadata(K));
+    for (unsigned K : MetadataKinds) {
+      if (K == LLVMContext::MD_dbg)
+        SetCurrentDebugLocation(Src->getDebugLoc());
+      else
+        AddOrRemoveMetadataToCopy(K, Src->getMetadata(K));
+    }
   }
 
   /// Get location information used by debugging information.
@@ -267,6 +280,7 @@ class IRBuilderBase {
   void AddMetadataToInst(Instruction *I) const {
     for (const auto &KV : MetadataToCopy)
       I->setMetadata(KV.first, KV.second);
+    SetInstDebugLocation(I);
   }
 
   /// Get the return type of the current function that we're emitting

diff --git a/llvm/include/llvm/IR/Instruction.h b/llvm/include/llvm/IR/Instruction.h
@@ -698,7 +698,7 @@ class Instruction : public User,
   ///     applications, thus the N-way merging should be in code path.
   /// The DebugLoc attached to this instruction will be overwritten by the
   /// merged DebugLoc.
-  LLVM_ABI void applyMergedLocation(DILocation *LocA, DILocation *LocB);
+  LLVM_ABI void applyMergedLocation(DebugLoc LocA, DebugLoc LocB);
 
   /// Updates the debug location given that the instruction has been hoisted
   /// from a block to a predecessor of that block.

diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -862,7 +862,7 @@ void BranchFolder::mergeCommonTails(unsigned commonTailIndex) {
             "Reached BB end within common tail");
       }
       assert(MI.isIdenticalTo(*Pos) && "Expected matching MIIs!");
-      DL = DILocation::getMergedLocation(DL, Pos->getDebugLoc());
+      DL = DebugLoc::getMergedLocation(DL, Pos->getDebugLoc());
       NextCommonInsts[i] = ++Pos;
     }
     MI.setDebugLoc(DL);

diff --git a/llvm/lib/CodeGen/GlobalISel/CSEMIRBuilder.cpp b/llvm/lib/CodeGen/GlobalISel/CSEMIRBuilder.cpp
@@ -53,8 +53,7 @@ CSEMIRBuilder::getDominatingInstrForID(FoldingSetNodeID &ID,
     } else if (!dominates(MI, CurrPos)) {
       // Update the spliced machineinstr's debug location by merging it with the
       // debug location of the instruction at the insertion point.
-      auto *Loc = DILocation::getMergedLocation(getDebugLoc().get(),
-                                                MI->getDebugLoc().get());
+      auto Loc = DebugLoc::getMergedLocation(getDebugLoc(), MI->getDebugLoc());
       MI->setDebugLoc(Loc);
       CurMBB->splice(CurrPos, CurMBB, MI);
     }
@@ -170,7 +169,7 @@ CSEMIRBuilder::generateCopiesIfRequired(ArrayRef<DstOp> DstOps,
     if (Observer)
       Observer->changingInstr(*MIB);
     MIB->setDebugLoc(
-        DILocation::getMergedLocation(MIB->getDebugLoc(), getDebugLoc()));
+        DebugLoc::getMergedLocation(MIB->getDebugLoc(), getDebugLoc()));
     if (Observer)
       Observer->changedInstr(*MIB);
   }

diff --git a/llvm/lib/CodeGen/GlobalISel/LoadStoreOpt.cpp b/llvm/lib/CodeGen/GlobalISel/LoadStoreOpt.cpp
@@ -370,7 +370,7 @@ bool LoadStoreOpt::doSingleStoreMerge(SmallVectorImpl<GStore *> &Stores) {
   // For each store, compute pairwise merged debug locs.
   DebugLoc MergedLoc = Stores.front()->getDebugLoc();
   for (auto *Store : drop_begin(Stores))
-    MergedLoc = DILocation::getMergedLocation(MergedLoc, Store->getDebugLoc());
+    MergedLoc = DebugLoc::getMergedLocation(MergedLoc, Store->getDebugLoc());
 
   Builder.setInstr(*Stores.back());
   Builder.setDebugLoc(MergedLoc);

diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -1574,7 +1574,7 @@ MachineBasicBlock::findBranchDebugLoc() {
     DL = TI->getDebugLoc();
     for (++TI ; TI != end() ; ++TI)
       if (TI->isBranch())
-        DL = DILocation::getMergedLocation(DL, TI->getDebugLoc());
+        DL = DebugLoc::getMergedLocation(DL, TI->getDebugLoc());
   }
   return DL;
 }

diff --git a/llvm/lib/CodeGen/MachineSink.cpp b/llvm/lib/CodeGen/MachineSink.cpp
@@ -1611,8 +1611,8 @@ static void performSink(MachineInstr &MI, MachineBasicBlock &SuccToSinkTo,
   // location to prevent debug-info driven tools from potentially reporting
   // wrong location information.
   if (!SuccToSinkTo.empty() && InsertPos != SuccToSinkTo.end())
-    MI.setDebugLoc(DILocation::getMergedLocation(MI.getDebugLoc(),
-                                                 InsertPos->getDebugLoc()));
+    MI.setDebugLoc(DebugLoc::getMergedLocation(MI.getDebugLoc(),
+                                               InsertPos->getDebugLoc()));
   else
     MI.setDebugLoc(DebugLoc());
 

diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
@@ -960,8 +960,8 @@ unsigned llvm::getDebugMetadataVersionFromModule(const Module &M) {
   return 0;
 }
 
-void Instruction::applyMergedLocation(DILocation *LocA, DILocation *LocB) {
-  setDebugLoc(DILocation::getMergedLocation(LocA, LocB));
+void Instruction::applyMergedLocation(DebugLoc LocA, DebugLoc LocB) {
+  setDebugLoc(DebugLoc::getMergedLocation(LocA, LocB));
 }
 
 void Instruction::mergeDIAssignID(

diff --git a/llvm/lib/IR/DebugLoc.cpp b/llvm/lib/IR/DebugLoc.cpp
@@ -143,6 +143,27 @@ DebugLoc DebugLoc::appendInlinedAt(const DebugLoc &DL, DILocation *InlinedAt,
   return Last;
 }
 
+DebugLoc DebugLoc::getMergedLocations(ArrayRef<DebugLoc> Locs) {
+  if (Locs.empty())
+    return DebugLoc();
+  if (Locs.size() == 1)
+    return Locs[0];
+  DebugLoc Merged = Locs[0];
+  for (const DebugLoc &DL : llvm::drop_begin(Locs)) {
+    Merged = getMergedLocation(Merged, DL);
+    if (!Merged)
+      break;
+  }
+  return Merged;
+}
+DebugLoc DebugLoc::getMergedLocation(DebugLoc LocA, DebugLoc LocB) {
+  if (!LocA)
+    return LocA;
+  if (!LocB)
+    return LocB;
+  return DILocation::getMergedLocation(LocA, LocB);
+}
+
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 LLVM_DUMP_METHOD void DebugLoc::dump() const { print(dbgs()); }
 #endif

diff --git a/llvm/lib/IR/IRBuilder.cpp b/llvm/lib/IR/IRBuilder.cpp
@@ -61,19 +61,12 @@ Type *IRBuilderBase::getCurrentFunctionReturnType() const {
   return BB->getParent()->getReturnType();
 }
 
-DebugLoc IRBuilderBase::getCurrentDebugLocation() const {
-  for (auto &KV : MetadataToCopy)
-    if (KV.first == LLVMContext::MD_dbg)
-      return {cast<DILocation>(KV.second)};
-
-  return {};
-}
+DebugLoc IRBuilderBase::getCurrentDebugLocation() const { return StoredDL; }
 void IRBuilderBase::SetInstDebugLocation(Instruction *I) const {
-  for (const auto &KV : MetadataToCopy)
-    if (KV.first == LLVMContext::MD_dbg) {
-      I->setDebugLoc(DebugLoc(KV.second));
-      return;
-    }
+  // We prefer to set our current debug location if any has been set, but if
+  // our debug location is empty and I has a valid location, we shouldn't
+  // overwrite it.
+  I->setDebugLoc(StoredDL.orElse(I->getDebugLoc()));
 }
 
 Value *IRBuilderBase::CreateAggregateCast(Value *V, Type *DestTy) {

diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
@@ -1363,6 +1363,9 @@ void Instruction::swapProfMetadata() {
 
 void Instruction::copyMetadata(const Instruction &SrcInst,
                                ArrayRef<unsigned> WL) {
+  if (WL.empty() || is_contained(WL, LLVMContext::MD_dbg))
+    setDebugLoc(SrcInst.getDebugLoc().orElse(getDebugLoc()));
+
   if (!SrcInst.hasMetadata())
     return;
 
@@ -1376,8 +1379,6 @@ void Instruction::copyMetadata(const Instruction &SrcInst,
     if (WL.empty() || WLS.count(MD.first))
       setMetadata(MD.first, MD.second);
   }
-  if (WL.empty() || WLS.count(LLVMContext::MD_dbg))
-    setDebugLoc(SrcInst.getDebugLoc());
 }
 
 Instruction *Instruction::clone() const {

diff --git a/llvm/lib/Target/BPF/BPFPreserveStaticOffset.cpp b/llvm/lib/Target/BPF/BPFPreserveStaticOffset.cpp
@@ -150,10 +150,10 @@ static CallInst *isGEPAndStore(Value *I) {
 }
 
 template <class T = Instruction>
-static DILocation *mergeDILocations(SmallVector<T *> &Insns) {
-  DILocation *Merged = (*Insns.begin())->getDebugLoc();
+static DebugLoc mergeDebugLocs(SmallVector<T *> &Insns) {
+  DebugLoc Merged = (*Insns.begin())->getDebugLoc();
   for (T *I : Insns)
-    Merged = DILocation::getMergedLocation(Merged, I->getDebugLoc());
+    Merged = DebugLoc::getMergedLocation(Merged, I->getDebugLoc());
   return Merged;
 }
 
@@ -227,7 +227,7 @@ static Instruction *makeGEPAndLoad(Module *M, GEPChainInfo &GEP,
   CallInst *Call = makeIntrinsicCall(M, Intrinsic::bpf_getelementptr_and_load,
                                      {Load->getType()}, Args);
   setParamElementType(Call, 0, GEP.SourceElementType);
-  Call->applyMergedLocation(mergeDILocations(GEP.Members), Load->getDebugLoc());
+  Call->applyMergedLocation(mergeDebugLocs(GEP.Members), Load->getDebugLoc());
   Call->setName((*GEP.Members.rbegin())->getName());
   if (Load->isUnordered()) {
     Call->setOnlyReadsMemory();
@@ -251,8 +251,7 @@ static Instruction *makeGEPAndStore(Module *M, GEPChainInfo &GEP,
   setParamElementType(Call, 1, GEP.SourceElementType);
   if (Store->getValueOperand()->getType()->isPointerTy())
     setParamReadNone(Call, 0);
-  Call->applyMergedLocation(mergeDILocations(GEP.Members),
-                            Store->getDebugLoc());
+  Call->applyMergedLocation(mergeDebugLocs(GEP.Members), Store->getDebugLoc());
   if (Store->isUnordered()) {
     Call->setOnlyWritesMemory();
     Call->setOnlyAccessesArgMemory();

@@ -1581,8 +1581,8 @@ bool InstCombinerImpl::mergeStoreIntoSuccessor(StoreInst &SI) {
   // Insert a PHI node now if we need it.
   Value *MergedVal = OtherStore->getValueOperand();
   // The debug locations of the original instructions might differ. Merge them.
-  DebugLoc MergedLoc = DILocation::getMergedLocation(SI.getDebugLoc(),
-                                                     OtherStore->getDebugLoc());
+  DebugLoc MergedLoc =
+      DebugLoc::getMergedLocation(SI.getDebugLoc(), OtherStore->getDebugLoc());
   if (MergedVal != SI.getValueOperand()) {
     PHINode *PN =
         PHINode::Create(SI.getValueOperand()->getType(), 2, "storemerge");

@@ -5340,8 +5340,7 @@ bool InstCombinerImpl::run() {
         // We copy the old instruction's DebugLoc to the new instruction, unless
         // InstCombine already assigned a DebugLoc to it, in which case we
         // should trust the more specifically selected DebugLoc.
-        if (!Result->getDebugLoc())
-          Result->setDebugLoc(I->getDebugLoc());
+        Result->setDebugLoc(Result->getDebugLoc().orElse(I->getDebugLoc()));
         // We also copy annotation metadata to the new instruction.
         Result->copyMetadata(*I, LLVMContext::MD_annotation);
         // Everything uses the new instruction now.

diff --git a/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp b/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
@@ -883,7 +883,7 @@ bool ConstantHoistingPass::emitBaseConstants(GlobalVariable *BaseGV) {
         emitBaseConstants(Base, &R);
         ReBasesNum++;
         // Use the same debug location as the last user of the constant.
-        Base->setDebugLoc(DILocation::getMergedLocation(
+        Base->setDebugLoc(DebugLoc::getMergedLocation(
             Base->getDebugLoc(), R.User.Inst->getDebugLoc()));
       }
       assert(!Base->use_empty() && "The use list is empty!?");

diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -2224,10 +2224,10 @@ bool llvm::promoteLoopAccessesToScalars(
   });
 
   // Look at all the loop uses, and try to merge their locations.
-  std::vector<DILocation *> LoopUsesLocs;
-  for (auto *U : LoopUses)
-    LoopUsesLocs.push_back(U->getDebugLoc().get());
-  auto DL = DebugLoc(DILocation::getMergedLocations(LoopUsesLocs));
+  std::vector<DebugLoc> LoopUsesLocs;
+  for (auto U : LoopUses)
+    LoopUsesLocs.push_back(U->getDebugLoc());
+  auto DL = DebugLoc::getMergedLocations(LoopUsesLocs);
 
   // We use the SSAUpdater interface to insert phi nodes as required.
   SmallVector<PHINode *, 16> NewPHIs;

diff --git a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -128,7 +128,7 @@ performBlockTailMerging(Function &F, ArrayRef<BasicBlock *> BBs,
 
   // Now, go through each block (with the current terminator type)
   // we've recorded, and rewrite it to branch to the new common block.
-  DILocation *CommonDebugLoc = nullptr;
+  DebugLoc CommonDebugLoc;
   for (BasicBlock *BB : BBs) {
     auto *Term = BB->getTerminator();
     assert(Term->getOpcode() == CanonicalTerm->getOpcode() &&
@@ -145,7 +145,7 @@ performBlockTailMerging(Function &F, ArrayRef<BasicBlock *> BBs,
       CommonDebugLoc = Term->getDebugLoc();
     else
       CommonDebugLoc =
-          DILocation::getMergedLocation(CommonDebugLoc, Term->getDebugLoc());
+          DebugLoc::getMergedLocation(CommonDebugLoc, Term->getDebugLoc());
 
     // And turn BB into a block that just unconditionally branches
     // to the canonical block.

diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2095,11 +2095,11 @@ bool SimplifyCFGOpt::hoistSuccIdenticalTerminatorToSwitchOrIf(
 
   // Ensure terminator gets a debug location, even an unknown one, in case
   // it involves inlinable calls.
-  SmallVector<DILocation *, 4> Locs;
+  SmallVector<DebugLoc, 4> Locs;
   Locs.push_back(I1->getDebugLoc());
   for (auto *OtherSuccTI : OtherSuccTIs)
     Locs.push_back(OtherSuccTI->getDebugLoc());
-  NT->setDebugLoc(DILocation::getMergedLocations(Locs));
+  NT->setDebugLoc(DebugLoc::getMergedLocations(Locs));
 
   // PHIs created below will adopt NT's merged DebugLoc.
   IRBuilder<NoFolder> Builder(NT);
@@ -2895,7 +2895,7 @@ static void mergeCompatibleInvokesImpl(ArrayRef<InvokeInst *> Invokes,
       MergedDebugLoc = II->getDebugLoc();
     else
       MergedDebugLoc =
-          DILocation::getMergedLocation(MergedDebugLoc, II->getDebugLoc());
+          DebugLoc::getMergedLocation(MergedDebugLoc, II->getDebugLoc());
 
     // And replace the old `invoke` with an unconditionally branch
     // to the block with the merged `invoke`.

diff --git a/llvm/lib/Transforms/Vectorize/VPlan.cpp b/llvm/lib/Transforms/Vectorize/VPlan.cpp
@@ -395,7 +395,7 @@ void VPTransformState::setDebugLocFrom(DebugLoc DL) {
       LLVM_DEBUG(dbgs() << "Failed to create new discriminator: "
                         << DIL->getFilename() << " Line: " << DIL->getLine());
   } else
-    Builder.SetCurrentDebugLocation(DIL);
+    Builder.SetCurrentDebugLocation(DL);
 }
 
 void VPTransformState::packScalarIntoVectorizedValue(const VPValue *Def,