[DebugInfo] Remove spare bits mask from LLVM IR and DWARF

llvm/include/llvm/BinaryFormat/Dwarf.def

@@ -636,7 +636,6 @@ HANDLE_DW_AT(0x3fee, APPLE_objc_direct, 0, APPLE)
 HANDLE_DW_AT(0x3fef, APPLE_sdk, 0, APPLE)
 HANDLE_DW_AT(0x3ff0, APPLE_origin, 0, APPLE)
 HANDLE_DW_AT(0x3ff1, APPLE_num_extra_inhabitants, 0, APPLE)
-HANDLE_DW_AT(0x3ff2, APPLE_spare_bits_mask, 0, APPLE)
 
 // Attribute form encodings.
 HANDLE_DW_FORM(0x01, addr, 2, DWARF)

llvm/include/llvm/IR/DIBuilder.h

@@ -533,17 +533,12 @@ namespace llvm {
     /// \param Discriminator Discriminant member
     /// \param Elements     Variant elements.
     /// \param UniqueIdentifier A unique identifier for the union.
-    /// \param OffsetInBits The offset of the variant payload in the variant
-    /// type.
-    /// \param SpareBitMask A mask of spare bits of the payload, spare bits are
-    /// bits that aren't used in any of the variant's cases.
     DICompositeType *
     createVariantPart(DIScope *Scope, StringRef Name, DIFile *File,
                       unsigned LineNumber, uint64_t SizeInBits,
                       uint32_t AlignInBits, DINode::DIFlags Flags,
                       DIDerivedType *Discriminator, DINodeArray Elements,
-                      StringRef UniqueIdentifier = "",
-                      uint64_t OffsetInBits = 0, APInt SpareBitsMask = APInt());
+                      StringRef UniqueIdentifier = "");
 
     /// Create debugging information for template
     /// type parameter.

llvm/include/llvm/IR/DebugInfoMetadata.h

@@ -1172,16 +1172,15 @@ class DICompositeType : public DIType {
   friend class MDNode;
 
   unsigned RuntimeLang;
-  llvm::APInt SpareBitsMask;
 
   DICompositeType(LLVMContext &C, StorageType Storage, unsigned Tag,
                   unsigned Line, unsigned RuntimeLang, uint64_t SizeInBits,
                   uint32_t AlignInBits, uint64_t OffsetInBits,
-                  uint32_t NumExtraInhabitants, APInt SpareBitsMask,
-                  DIFlags Flags, ArrayRef<Metadata *> Ops)
+                  uint32_t NumExtraInhabitants, DIFlags Flags,
+                  ArrayRef<Metadata *> Ops)
       : DIType(C, DICompositeTypeKind, Storage, Tag, Line, SizeInBits,
                AlignInBits, OffsetInBits, NumExtraInhabitants, Flags, Ops),
-        RuntimeLang(RuntimeLang), SpareBitsMask(SpareBitsMask) {}
+        RuntimeLang(RuntimeLang) {}
   ~DICompositeType() = default;
 
   /// Change fields in place.
@@ -1199,20 +1198,20 @@ class DICompositeType : public DIType {
   getImpl(LLVMContext &Context, unsigned Tag, StringRef Name, Metadata *File,
           unsigned Line, DIScope *Scope, DIType *BaseType, uint64_t SizeInBits,
           uint32_t AlignInBits, uint64_t OffsetInBits, DIType *SpecificationOf,
-          uint32_t NumExtraInhabitants, APInt SpareBitsMask, DIFlags Flags,
-          DINodeArray Elements, unsigned RuntimeLang, DIType *VTableHolder,
+          uint32_t NumExtraInhabitants, DIFlags Flags, DINodeArray Elements,
+          unsigned RuntimeLang, DIType *VTableHolder,
           DITemplateParameterArray TemplateParams, StringRef Identifier,
           DIDerivedType *Discriminator, Metadata *DataLocation,
           Metadata *Associated, Metadata *Allocated, Metadata *Rank,
           DINodeArray Annotations, StorageType Storage,
           bool ShouldCreate = true) {
-    return getImpl(
-        Context, Tag, getCanonicalMDString(Context, Name), File, Line, Scope,
-        BaseType, SizeInBits, AlignInBits, OffsetInBits, Flags, Elements.get(),
-        RuntimeLang, VTableHolder, TemplateParams.get(),
-        getCanonicalMDString(Context, Identifier), Discriminator, DataLocation,
-        Associated, Allocated, Rank, Annotations.get(), SpecificationOf,
-        NumExtraInhabitants, SpareBitsMask, Storage, ShouldCreate);
+    return getImpl(Context, Tag, getCanonicalMDString(Context, Name), File,
+                   Line, Scope, BaseType, SizeInBits, AlignInBits, OffsetInBits,
+                   Flags, Elements.get(), RuntimeLang, VTableHolder,
+                   TemplateParams.get(),
+                   getCanonicalMDString(Context, Identifier), Discriminator,
+                   DataLocation, Associated, Allocated, Rank, Annotations.get(),
+                   SpecificationOf, NumExtraInhabitants, Storage, ShouldCreate);
   }
   static DICompositeType *
   getImpl(LLVMContext &Context, unsigned Tag, MDString *Name, Metadata *File,
@@ -1223,8 +1222,8 @@ class DICompositeType : public DIType {
           MDString *Identifier, Metadata *Discriminator, Metadata *DataLocation,
           Metadata *Associated, Metadata *Allocated, Metadata *Rank,
           Metadata *Annotations, Metadata *SpecificationOf,
-          uint32_t NumExtraInhabitants, APInt SpareBitsMask,
-          StorageType Storage, bool ShouldCreate = true);
+          uint32_t NumExtraInhabitants, StorageType Storage,
+          bool ShouldCreate = true);
 
   TempDICompositeType cloneImpl() const {
     return getTemporary(
@@ -1234,7 +1233,7 @@ class DICompositeType : public DIType {
         getTemplateParams(), getIdentifier(), getDiscriminator(),
         getRawDataLocation(), getRawAssociated(), getRawAllocated(),
         getRawRank(), getAnnotations(), getSpecificationOf(),
-        getNumExtraInhabitants(), getSpareBitsMask());
+        getNumExtraInhabitants());
   }
 
 public:
@@ -1249,11 +1248,11 @@ class DICompositeType : public DIType {
        Metadata *DataLocation = nullptr, Metadata *Associated = nullptr,
        Metadata *Allocated = nullptr, Metadata *Rank = nullptr,
        DINodeArray Annotations = nullptr, DIType *SpecificationOf = nullptr,
-       uint32_t NumExtraInhabitants = 0, APInt SpareBitsMask = APInt()),
+       uint32_t NumExtraInhabitants = 0),
       (Tag, Name, File, Line, Scope, BaseType, SizeInBits, AlignInBits,
-       OffsetInBits, SpecificationOf, NumExtraInhabitants, SpareBitsMask, Flags,
-       Elements, RuntimeLang, VTableHolder, TemplateParams, Identifier,
-       Discriminator, DataLocation, Associated, Allocated, Rank, Annotations))
+       OffsetInBits, SpecificationOf, NumExtraInhabitants, Flags, Elements,
+       RuntimeLang, VTableHolder, TemplateParams, Identifier, Discriminator,
+       DataLocation, Associated, Allocated, Rank, Annotations))
   DEFINE_MDNODE_GET(
       DICompositeType,
       (unsigned Tag, MDString *Name, Metadata *File, unsigned Line,
@@ -1264,12 +1263,11 @@ class DICompositeType : public DIType {
        Metadata *Discriminator = nullptr, Metadata *DataLocation = nullptr,
        Metadata *Associated = nullptr, Metadata *Allocated = nullptr,
        Metadata *Rank = nullptr, Metadata *Annotations = nullptr,
-       Metadata *SpecificationOf = nullptr, uint32_t NumExtraInhabitants = 0,
-       APInt SpareBitsMask = APInt()),
+       Metadata *SpecificationOf = nullptr, uint32_t NumExtraInhabitants = 0),
       (Tag, Name, File, Line, Scope, BaseType, SizeInBits, AlignInBits,
        OffsetInBits, Flags, Elements, RuntimeLang, VTableHolder, TemplateParams,
        Identifier, Discriminator, DataLocation, Associated, Allocated, Rank,
-       Annotations, SpecificationOf, NumExtraInhabitants, SpareBitsMask))
+       Annotations, SpecificationOf, NumExtraInhabitants))
 
   TempDICompositeType clone() const { return cloneImpl(); }
 
@@ -1285,7 +1283,7 @@ class DICompositeType : public DIType {
              MDString *Name, Metadata *File, unsigned Line, Metadata *Scope,
              Metadata *BaseType, uint64_t SizeInBits, uint32_t AlignInBits,
              uint64_t OffsetInBits, Metadata *SpecificationOf,
-             uint32_t NumExtraInhabitants, APInt SpareBitsMask, DIFlags Flags,
+             uint32_t NumExtraInhabitants,  DIFlags Flags,
              Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
              Metadata *TemplateParams, Metadata *Discriminator,
              Metadata *DataLocation, Metadata *Associated, Metadata *Allocated,
@@ -1307,8 +1305,8 @@ class DICompositeType : public DIType {
                MDString *Name, Metadata *File, unsigned Line, Metadata *Scope,
                Metadata *BaseType, uint64_t SizeInBits, uint32_t AlignInBits,
                uint64_t OffsetInBits, Metadata *SpecificationOf,
-               uint32_t NumExtraInhabitants, APInt SpareBitsMask, DIFlags Flags,
-               Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
+               uint32_t NumExtraInhabitants, DIFlags Flags, Metadata *Elements,
+               unsigned RuntimeLang, Metadata *VTableHolder,
                Metadata *TemplateParams, Metadata *Discriminator,
                Metadata *DataLocation, Metadata *Associated,
                Metadata *Allocated, Metadata *Rank, Metadata *Annotations);
@@ -1325,7 +1323,6 @@ class DICompositeType : public DIType {
   }
   StringRef getIdentifier() const { return getStringOperand(7); }
   unsigned getRuntimeLang() const { return RuntimeLang; }
-  const APInt &getSpareBitsMask() const { return SpareBitsMask; }
 
   Metadata *getRawBaseType() const { return getOperand(3); }
   Metadata *getRawElements() const { return getOperand(4); }

llvm/lib/AsmParser/LLParser.cpp

@@ -5433,8 +5433,7 @@ bool LLParser::parseDICompositeType(MDNode *&Result, bool IsDistinct) {
   OPTIONAL(rank, MDSignedOrMDField, );                                         \
   OPTIONAL(annotations, MDField, );                                            \
   OPTIONAL(num_extra_inhabitants, MDUnsignedField, (0, UINT32_MAX));           \
-  OPTIONAL(specification_of, MDField, );                                       \
-  OPTIONAL(spare_bits_mask, MDAPSIntField, );                                  
+  OPTIONAL(specification_of, MDField, ); 
   PARSE_MD_FIELDS();
 #undef VISIT_MD_FIELDS
 
@@ -5450,11 +5449,10 @@ bool LLParser::parseDICompositeType(MDNode *&Result, bool IsDistinct) {
     if (auto *CT = DICompositeType::buildODRType(
             Context, *identifier.Val, tag.Val, name.Val, file.Val, line.Val,
             scope.Val, baseType.Val, size.Val, align.Val, offset.Val,
-            specification_of.Val, num_extra_inhabitants.Val,
-            spare_bits_mask.Val, flags.Val, elements.Val, runtimeLang.Val,
-            vtableHolder.Val, templateParams.Val, discriminator.Val,
-            dataLocation.Val, associated.Val, allocated.Val, Rank,
-            annotations.Val)) {
+            specification_of.Val, num_extra_inhabitants.Val, flags.Val,
+            elements.Val, runtimeLang.Val, vtableHolder.Val, templateParams.Val,
+            discriminator.Val, dataLocation.Val, associated.Val, allocated.Val,
+            Rank, annotations.Val)) {
       Result = CT;
       return false;
     }
@@ -5467,8 +5465,7 @@ bool LLParser::parseDICompositeType(MDNode *&Result, bool IsDistinct) {
        size.Val, align.Val, offset.Val, flags.Val, elements.Val,
        runtimeLang.Val, vtableHolder.Val, templateParams.Val, identifier.Val,
        discriminator.Val, dataLocation.Val, associated.Val, allocated.Val, Rank,
-       annotations.Val, specification_of.Val, num_extra_inhabitants.Val,
-       spare_bits_mask.Val));
+       annotations.Val, specification_of.Val, num_extra_inhabitants.Val));
   return false;
 }
 

llvm/lib/Bitcode/Reader/MetadataLoader.cpp

@@ -1602,13 +1602,10 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
     break;
   }
   case bitc::METADATA_COMPOSITE_TYPE: {
-    // The last field is a variable sized APInt, so the metadata loader can't
-    // reliably check the end for this record.
     if (Record.size() < 16)
       return error("Invalid record");
 
     IsDistinct = Record[0] & 1;
-    bool IsBigInt = (Record[0] >> 3) & 1;
     // If we have a UUID and this is not a forward declaration, lookup the
     // mapping.
     IsDistinct = Record[0] & 0x1;
@@ -1690,28 +1687,13 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
       }
     }
     DICompositeType *CT = nullptr;
-    APInt SpareBitsMask;
-    // SpareBitsMask is an optional field so the metadata loader has to check if
-    // it was emitted before accessing it.
-    if (Record.size() > 24) {
-      if (IsBigInt) {
-        const uint64_t BitWidth = Record[24];
-        const size_t NumWords = Record.size() - 3;
-        SpareBitsMask =
-            readWideAPInt(ArrayRef(&Record[25], NumWords), BitWidth);
-      } else {
-        const uint64_t IntValue = Record[24];
-        SpareBitsMask = APInt(64, IntValue);
-      }
-    }
-
     if (Identifier)
       CT = DICompositeType::buildODRType(
           Context, *Identifier, Tag, Name, File, Line, Scope, BaseType,
           SizeInBits, AlignInBits, OffsetInBits, SpecificationOf,
-          NumExtraInhabitants, SpareBitsMask, Flags, Elements, RuntimeLang,
-          VTableHolder, TemplateParams, Discriminator, DataLocation, Associated,
-          Allocated, Rank, Annotations);
+          NumExtraInhabitants, Flags, Elements, RuntimeLang, VTableHolder,
+          TemplateParams, Discriminator, DataLocation, Associated, Allocated,
+          Rank, Annotations);
 
     // Create a node if we didn't get a lazy ODR type.
     if (!CT)
@@ -1721,7 +1703,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
                             Elements, RuntimeLang, VTableHolder, TemplateParams,
                             Identifier, Discriminator, DataLocation, Associated,
                             Allocated, Rank, Annotations, SpecificationOf,
-                            NumExtraInhabitants, SpareBitsMask));
+                            NumExtraInhabitants));
     if (!IsNotUsedInTypeRef && Identifier)
       MetadataList.addTypeRef(*Identifier, *cast<DICompositeType>(CT));
 

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -1903,14 +1903,9 @@ void ModuleBitcodeWriter::writeDICompositeType(
     const DICompositeType *N, SmallVectorImpl<uint64_t> &Record,
     unsigned Abbrev) {
 
-  APInt SpareBitsMask = N->getSpareBitsMask();
-  unsigned IsWideAPInt = 0;;
-  if (!SpareBitsMask.isZero() && SpareBitsMask.getBitWidth() > 64) 
-    IsWideAPInt = 1 << 3;
 
   const unsigned IsNotUsedInOldTypeRef = 0x2;
-  Record.push_back(IsWideAPInt | IsNotUsedInOldTypeRef |
-                   (unsigned)N->isDistinct());
+  Record.push_back(IsNotUsedInOldTypeRef | (unsigned)N->isDistinct());
   Record.push_back(N->getTag());
   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
   Record.push_back(VE.getMetadataOrNullID(N->getFile()));
@@ -1935,17 +1930,6 @@ void ModuleBitcodeWriter::writeDICompositeType(
   Record.push_back(N->getNumExtraInhabitants());
   Record.push_back(VE.getMetadataOrNullID(N->getRawSpecificationOf()));
 
-
-  if (!SpareBitsMask.isZero()) {
-    if (IsWideAPInt) {
-      Record.push_back(SpareBitsMask.getBitWidth());
-      emitWideAPInt(Record, SpareBitsMask);
-    } else {
-        uint64_t V = SpareBitsMask.getZExtValue();
-        Record.push_back(V);
-    }
-  }
-
   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
   Record.clear();
 }

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -1103,14 +1103,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
       addUInt(Buffer, dwarf::DW_AT_APPLE_num_extra_inhabitants,
             std::nullopt, NumExtraInhabitants);
 
-  } else if (Tag == dwarf::DW_TAG_variant_part) {
-    auto SpareBitsMask = CTy->getSpareBitsMask();
-    if (!SpareBitsMask.isZero())
-      addConstantValue(Buffer, SpareBitsMask, false,
-                       dwarf::DW_AT_APPLE_spare_bits_mask);
-    if (auto OffsetInBits = CTy->getOffsetInBits()) 
-      addUInt(Buffer, dwarf::DW_AT_bit_offset, std::nullopt, OffsetInBits);
-  }
+  } 
 }
 
 void DwarfUnit::constructTemplateTypeParameterDIE(

llvm/lib/IR/AsmWriter.cpp

@@ -2202,8 +2202,6 @@ static void writeDICompositeType(raw_ostream &Out, const DICompositeType *N,
   Printer.printInt("align", N->getAlignInBits());
   Printer.printInt("offset", N->getOffsetInBits());
   Printer.printInt("num_extra_inhabitants", N->getNumExtraInhabitants());
-  if (!N->getSpareBitsMask().isZero())
-    Printer.printAPInt("spare_bits_mask", N->getSpareBitsMask(), true, false);
   Printer.printDIFlags("flags", N->getFlags());
   Printer.printMetadata("elements", N->getRawElements());
   Printer.printDwarfEnum("runtimeLang", N->getRuntimeLang(),

llvm/lib/IR/DIBuilder.cpp

@@ -546,17 +546,17 @@ DICompositeType *DIBuilder::createUnionType(
   return R;
 }
 
-DICompositeType *DIBuilder::createVariantPart(
-    DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNumber,
-    uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags,
-    DIDerivedType *Discriminator, DINodeArray Elements,
-    StringRef UniqueIdentifier, uint64_t OffsetInBits, APInt SpareBitsMask) {
+DICompositeType *
+DIBuilder::createVariantPart(DIScope *Scope, StringRef Name, DIFile *File,
+                             unsigned LineNumber, uint64_t SizeInBits,
+                             uint32_t AlignInBits, DINode::DIFlags Flags,
+                             DIDerivedType *Discriminator, DINodeArray Elements,
+                             StringRef UniqueIdentifier) {
   auto *R = DICompositeType::get(
       VMContext, dwarf::DW_TAG_variant_part, Name, File, LineNumber,
-      getNonCompileUnitScope(Scope), nullptr, SizeInBits, AlignInBits,
-      OffsetInBits, Flags, Elements, 0, nullptr, nullptr, UniqueIdentifier,
-      nullptr, 0, Discriminator, nullptr, nullptr, nullptr, {}, {},
-      SpareBitsMask);
+      getNonCompileUnitScope(Scope), nullptr, SizeInBits, AlignInBits, 0, Flags,
+      Elements, 0, nullptr, nullptr, UniqueIdentifier, nullptr, 0,
+      Discriminator, nullptr, nullptr, nullptr, {}, {});
   trackIfUnresolved(R);
   return R;
 }