Split DWARFFormValue::getReference into four functions

llvm/include/llvm/DebugInfo/DWARF/DWARFFormValue.h

@@ -107,12 +107,10 @@ class DWARFFormValue {
 
   /// getAsFoo functions below return the extracted value as Foo if only
   /// DWARFFormValue has form class is suitable for representing Foo.
-  std::optional<uint64_t> getAsReference() const;
-  struct UnitOffset {
-    DWARFUnit *Unit;
-    uint64_t Offset;
-  };
-  std::optional<UnitOffset> getAsRelativeReference() const;
+  std::optional<uint64_t> getAsRelativeReference() const;
+  std::optional<uint64_t> getAsDebugInfoReference() const;
+  std::optional<uint64_t> getAsSignatureReference() const;
+  std::optional<uint64_t> getAsSupplementaryReference() const;
   std::optional<uint64_t> getAsUnsignedConstant() const;
   std::optional<int64_t> getAsSignedConstant() const;
   Expected<const char *> getAsCString() const;
@@ -242,27 +240,102 @@ inline uint64_t toUnsigned(const std::optional<DWARFFormValue> &V,
   return toUnsigned(V).value_or(Default);
 }
 
-/// Take an optional DWARFFormValue and try to extract an reference.
+/// Take an optional DWARFFormValue and try to extract a relative offset
+/// reference.
 ///
-/// \param V and optional DWARFFormValue to attempt to extract the value from.
+/// \param V an optional DWARFFormValue to attempt to extract the value from.
 /// \returns an optional value that contains a value if the form value
-/// was valid and has a reference form.
+/// was valid and has a relative reference form.
 inline std::optional<uint64_t>
-toReference(const std::optional<DWARFFormValue> &V) {
+toRelativeReference(const std::optional<DWARFFormValue> &V) {
   if (V)
-    return V->getAsReference();
+    return V->getAsRelativeReference();
   return std::nullopt;
 }
 
-/// Take an optional DWARFFormValue and extract a reference.
+/// Take an optional DWARFFormValue and extract a relative offset reference.
 ///
-/// \param V and optional DWARFFormValue to attempt to extract the value from.
+/// \param V an optional DWARFFormValue to attempt to extract the value from.
+/// \param Default the default value to return in case of failure.
+/// \returns the extracted reference value or Default if the V doesn't have a
+/// value or the form value's encoding wasn't a relative offset reference form.
+inline uint64_t toRelativeReference(const std::optional<DWARFFormValue> &V,
+                                    uint64_t Default) {
+  return toRelativeReference(V).value_or(Default);
+}
+
+/// Take an optional DWARFFormValue and try to extract an absolute debug info
+/// offset reference.
+///
+/// \param V an optional DWARFFormValue to attempt to extract the value from.
+/// \returns an optional value that contains a value if the form value
+/// was valid and has an (absolute) debug info offset reference form.
+inline std::optional<uint64_t>
+toDebugInfoReference(const std::optional<DWARFFormValue> &V) {
+  if (V)
+    return V->getAsDebugInfoReference();
+  return std::nullopt;
+}
+
+/// Take an optional DWARFFormValue and extract an absolute debug info offset
+/// reference.
+///
+/// \param V an optional DWARFFormValue to attempt to extract the value from.
+/// \param Default the default value to return in case of failure.
+/// \returns the extracted reference value or Default if the V doesn't have a
+/// value or the form value's encoding wasn't an absolute debug info offset
+/// reference form.
+inline uint64_t toDebugInfoReference(const std::optional<DWARFFormValue> &V,
+                                     uint64_t Default) {
+  return toDebugInfoReference(V).value_or(Default);
+}
+
+/// Take an optional DWARFFormValue and try to extract a signature reference.
+///
+/// \param V an optional DWARFFormValue to attempt to extract the value from.
+/// \returns an optional value that contains a value if the form value
+/// was valid and has a signature reference form.
+inline std::optional<uint64_t>
+toSignatureReference(const std::optional<DWARFFormValue> &V) {
+  if (V)
+    return V->getAsSignatureReference();
+  return std::nullopt;
+}
+
+/// Take an optional DWARFFormValue and extract a signature reference.
+///
+/// \param V an optional DWARFFormValue to attempt to extract the value from.
+/// \param Default the default value to return in case of failure.
+/// \returns the extracted reference value or Default if the V doesn't have a
+/// value or the form value's encoding wasn't a signature reference form.
+inline uint64_t toSignatureReference(const std::optional<DWARFFormValue> &V,
+                                     uint64_t Default) {
+  return toSignatureReference(V).value_or(Default);
+}
+
+/// Take an optional DWARFFormValue and try to extract a supplementary debug
+/// info reference.
+///
+/// \param V an optional DWARFFormValue to attempt to extract the value from.
+/// \returns an optional value that contains a value if the form value
+/// was valid and has a supplementary reference form.
+inline std::optional<uint64_t>
+toSupplementaryReference(const std::optional<DWARFFormValue> &V) {
+  if (V)
+    return V->getAsSupplementaryReference();
+  return std::nullopt;
+}
+
+/// Take an optional DWARFFormValue and extract a supplementary debug info
+/// reference.
+///
+/// \param V an optional DWARFFormValue to attempt to extract the value from.
 /// \param Default the default value to return in case of failure.
 /// \returns the extracted reference value or Default if the V doesn't have a
-/// value or the form value's encoding wasn't a reference form.
-inline uint64_t toReference(const std::optional<DWARFFormValue> &V,
-                            uint64_t Default) {
-  return toReference(V).value_or(Default);
+/// value or the form value's encoding wasn't a supplementary reference form.
+inline uint64_t toSupplementaryReference(const std::optional<DWARFFormValue> &V,
+                                         uint64_t Default) {
+  return toSupplementaryReference(V).value_or(Default);
 }
 
 /// Take an optional DWARFFormValue and try to extract an signed constant.

llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp

@@ -77,7 +77,15 @@ DWARFDie DWARFLinker::resolveDIEReference(const DWARFFile &File,
                                           const DWARFDie &DIE,
                                           CompileUnit *&RefCU) {
   assert(RefValue.isFormClass(DWARFFormValue::FC_Reference));
-  uint64_t RefOffset = *RefValue.getAsReference();
+  uint64_t RefOffset;
+  if (std::optional<uint64_t> Off = RefValue.getAsRelativeReference()) {
+    RefOffset = RefValue.getUnit()->getOffset() + *Off;
+  } else if (Off = RefValue.getAsDebugInfoReference(); Off) {
+    RefOffset = *Off;
+  } else {
+    reportWarning("Unsupported reference type", File, &DIE);
+    return DWARFDie();
+  }
   if ((RefCU = getUnitForOffset(Units, RefOffset)))
     if (const auto RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset)) {
       // In a file with broken references, an attribute might point to a NULL
@@ -1073,7 +1081,13 @@ unsigned DWARFLinker::DIECloner::cloneDieReferenceAttribute(
     unsigned AttrSize, const DWARFFormValue &Val, const DWARFFile &File,
     CompileUnit &Unit) {
   const DWARFUnit &U = Unit.getOrigUnit();
-  uint64_t Ref = *Val.getAsReference();
+  uint64_t Ref;
+  if (std::optional<uint64_t> Off = Val.getAsRelativeReference())
+    Ref = Val.getUnit()->getOffset() + *Off;
+  else if (Off = Val.getAsDebugInfoReference(); Off)
+    Ref = *Off;
+  else
+    return 0;
 
   DIE *NewRefDie = nullptr;
   CompileUnit *RefUnit = nullptr;

llvm/lib/DWARFLinker/Parallel/DWARFLinkerCompileUnit.cpp

@@ -381,38 +381,36 @@ void CompileUnit::updateDieRefPatchesWithClonedOffsets() {
 std::optional<UnitEntryPairTy> CompileUnit::resolveDIEReference(
     const DWARFFormValue &RefValue,
     ResolveInterCUReferencesMode CanResolveInterCUReferences) {
-  if (std::optional<DWARFFormValue::UnitOffset> Ref =
-          *RefValue.getAsRelativeReference()) {
-    if (Ref->Unit == OrigUnit) {
-      // Referenced DIE is in current compile unit.
-      if (std::optional<uint32_t> RefDieIdx =
-              getDIEIndexForOffset(OrigUnit->getOffset() + Ref->Offset))
-        return UnitEntryPairTy{this, OrigUnit->getDebugInfoEntry(*RefDieIdx)};
-    }
-    uint64_t RefDIEOffset =
-        Ref->Unit ? Ref->Unit->getOffset() + Ref->Offset : Ref->Offset;
-    if (CompileUnit *RefCU = getUnitFromOffset(RefDIEOffset)) {
-      if (RefCU == this) {
-        // Referenced DIE is in current compile unit.
-        if (std::optional<uint32_t> RefDieIdx =
-                getDIEIndexForOffset(RefDIEOffset))
-          return UnitEntryPairTy{this, getDebugInfoEntry(*RefDieIdx)};
-      } else if (CanResolveInterCUReferences) {
-        // Referenced DIE is in other compile unit.
-
-        // Check whether DIEs are loaded for that compile unit.
-        enum Stage ReferredCUStage = RefCU->getStage();
-        if (ReferredCUStage < Stage::Loaded || ReferredCUStage > Stage::Cloned)
-          return UnitEntryPairTy{RefCU, nullptr};
-
-        if (std::optional<uint32_t> RefDieIdx =
-                RefCU->getDIEIndexForOffset(RefDIEOffset))
-          return UnitEntryPairTy{RefCU, RefCU->getDebugInfoEntry(*RefDieIdx)};
-      } else
-        return UnitEntryPairTy{RefCU, nullptr};
-    }
+  CompileUnit *RefCU;
+  uint64_t RefDIEOffset;
+  if (std::optional<uint64_t> Offset = RefValue.getAsRelativeReference()) {
+    RefCU = this;
+    RefDIEOffset = RefValue.getUnit()->getOffset() + *Offset;
+  } else if (Offset = RefValue.getAsDebugInfoReference(); Offset) {
+    RefCU = getUnitFromOffset(*Offset);
+    RefDIEOffset = *Offset;
+  } else {
+    return std::nullopt;
   }
 
+  if (RefCU == this) {
+    // Referenced DIE is in current compile unit.
+    if (std::optional<uint32_t> RefDieIdx = getDIEIndexForOffset(RefDIEOffset))
+      return UnitEntryPairTy{this, getDebugInfoEntry(*RefDieIdx)};
+  } else if (RefCU && CanResolveInterCUReferences) {
+    // Referenced DIE is in other compile unit.
+
+    // Check whether DIEs are loaded for that compile unit.
+    enum Stage ReferredCUStage = RefCU->getStage();
+    if (ReferredCUStage < Stage::Loaded || ReferredCUStage > Stage::Cloned)
+      return UnitEntryPairTy{RefCU, nullptr};
+
+    if (std::optional<uint32_t> RefDieIdx =
+            RefCU->getDIEIndexForOffset(RefDIEOffset))
+      return UnitEntryPairTy{RefCU, RefCU->getDebugInfoEntry(*RefDieIdx)};
+  } else {
+    return UnitEntryPairTy{RefCU, nullptr};
+  }
   return std::nullopt;
 }
 

llvm/lib/DebugInfo/DWARF/DWARFDie.cpp

@@ -313,13 +313,12 @@ DWARFDie::getAttributeValueAsReferencedDie(dwarf::Attribute Attr) const {
 DWARFDie
 DWARFDie::getAttributeValueAsReferencedDie(const DWARFFormValue &V) const {
   DWARFDie Result;
-  if (auto SpecRef = V.getAsRelativeReference()) {
-    if (SpecRef->Unit)
-      Result = SpecRef->Unit->getDIEForOffset(SpecRef->Unit->getOffset() +
-                                              SpecRef->Offset);
-    else if (auto SpecUnit =
-                 U->getUnitVector().getUnitForOffset(SpecRef->Offset))
-      Result = SpecUnit->getDIEForOffset(SpecRef->Offset);
+  if (std::optional<uint64_t> Offset = V.getAsRelativeReference()) {
+    Result = const_cast<DWARFUnit *>(V.getUnit())
+                 ->getDIEForOffset(V.getUnit()->getOffset() + *Offset);
+  } else if (Offset = V.getAsDebugInfoReference(); Offset) {
+    if (DWARFUnit *SpecUnit = U->getUnitVector().getUnitForOffset(*Offset))
+      Result = SpecUnit->getDIEForOffset(*Offset);
   }
   return Result;
 }

llvm/lib/DebugInfo/DWARF/DWARFFormValue.cpp

@@ -665,16 +665,7 @@ DWARFFormValue::getAsSectionedAddress() const {
   return getAsSectionedAddress(Value, Form, U);
 }
 
-std::optional<uint64_t> DWARFFormValue::getAsReference() const {
-  if (auto R = getAsRelativeReference())
-    return R->Unit ? R->Unit->getOffset() + R->Offset : R->Offset;
-  return std::nullopt;
-}
-
-std::optional<DWARFFormValue::UnitOffset>
-DWARFFormValue::getAsRelativeReference() const {
-  if (!isFormClass(FC_Reference))
-    return std::nullopt;
+std::optional<uint64_t> DWARFFormValue::getAsRelativeReference() const {
   switch (Form) {
   case DW_FORM_ref1:
   case DW_FORM_ref2:
@@ -683,11 +674,30 @@ DWARFFormValue::getAsRelativeReference() const {
   case DW_FORM_ref_udata:
     if (!U)
       return std::nullopt;
-    return UnitOffset{const_cast<DWARFUnit*>(U), Value.uval};
-  case DW_FORM_ref_addr:
-  case DW_FORM_ref_sig8:
+    return Value.uval;
+  default:
+    return std::nullopt;
+  }
+}
+
+std::optional<uint64_t> DWARFFormValue::getAsDebugInfoReference() const {
+  if (Form == DW_FORM_ref_addr)
+    return Value.uval;
+  return std::nullopt;
+}
+
+std::optional<uint64_t> DWARFFormValue::getAsSignatureReference() const {
+  if (Form == DW_FORM_ref_sig8)
+    return Value.uval;
+  return std::nullopt;
+}
+
+std::optional<uint64_t> DWARFFormValue::getAsSupplementaryReference() const {
+  switch (Form) {
   case DW_FORM_GNU_ref_alt:
-    return UnitOffset{nullptr, Value.uval};
+  case DW_FORM_ref_sup4:
+  case DW_FORM_ref_sup8:
+    return Value.uval;
   default:
     return std::nullopt;
   }

llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp

@@ -836,7 +836,7 @@ unsigned DWARFVerifier::verifyDebugInfoForm(const DWARFDie &Die,
   case DW_FORM_ref8:
   case DW_FORM_ref_udata: {
     // Verify all CU relative references are valid CU offsets.
-    std::optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
+    std::optional<uint64_t> RefVal = AttrValue.Value.getAsRelativeReference();
     assert(RefVal);
     if (RefVal) {
       auto CUSize = DieCU->getNextUnitOffset() - DieCU->getOffset();
@@ -854,15 +854,16 @@ unsigned DWARFVerifier::verifyDebugInfoForm(const DWARFDie &Die,
       } else {
         // Valid reference, but we will verify it points to an actual
         // DIE later.
-        LocalReferences[*RefVal].insert(Die.getOffset());
+        LocalReferences[AttrValue.Value.getUnit()->getOffset() + *RefVal]
+            .insert(Die.getOffset());
       }
     }
     break;
   }
   case DW_FORM_ref_addr: {
     // Verify all absolute DIE references have valid offsets in the
     // .debug_info section.
-    std::optional<uint64_t> RefVal = AttrValue.Value.getAsReference();
+    std::optional<uint64_t> RefVal = AttrValue.Value.getAsDebugInfoReference();
     assert(RefVal);
     if (RefVal) {
       if (*RefVal >= DieCU->getInfoSection().Data.size()) {

llvm/lib/DebugInfo/LogicalView/Readers/LVDWARFReader.cpp

@@ -1082,21 +1082,28 @@ void LVDWARFReader::updateReference(dwarf::Attribute Attr,
   // FIXME: We are assuming that at most one Reference (DW_AT_specification,
   // DW_AT_abstract_origin, ...) and at most one Type (DW_AT_import, DW_AT_type)
   // appear in any single DIE, but this may not be true.
-  uint64_t Reference = *FormValue.getAsReference();
+  uint64_t Offset;
+  if (std::optional<uint64_t> Off = FormValue.getAsRelativeReference())
+    Offset = FormValue.getUnit()->getOffset() + *Off;
+  else if (Off = FormValue.getAsDebugInfoReference(); Off)
+    Offset = *Off;
+  else
+    llvm_unreachable("Unsupported reference type");
+
   // Get target for the given reference, if already created.
   LVElement *Target = getElementForOffset(
-      Reference, CurrentElement,
+      Offset, CurrentElement,
       /*IsType=*/Attr == dwarf::DW_AT_import || Attr == dwarf::DW_AT_type);
   // Check if we are dealing with cross CU references.
   if (FormValue.getForm() == dwarf::DW_FORM_ref_addr) {
     if (Target) {
       // The global reference is ready. Mark it as global.
       Target->setIsGlobalReference();
       // Remove global reference from the unseen list.
-      removeGlobalOffset(Reference);
+      removeGlobalOffset(Offset);
     } else
       // Record the unseen cross CU reference.
-      addGlobalOffset(Reference);
+      addGlobalOffset(Offset);
   }
 
   // At this point, 'Target' can be null, in the case of the target element