[DebugInfo] Add a specification attribute to LLVM DebugInfo (llvm#115362)

Add a specification attribute to LLVM DebugInfo, which is analogous
to DWARF's DW_AT_specification. According to the DWARF spec:
"A debugging information entry that represents a declaration that
completes another (earlier) non-defining declaration may have a
DW_AT_specification attribute whose value is a reference to the
debugging information entry representing the non-defining declaration."

This patch allows types to be specifications of other types. This is
used by Swift to represent generic types. For example, given this Swift
program:

```
struct MyStruct<T> {
    let t: T
}

let variable = MyStruct<Int>(t: 43)
```

The Swift compiler emits (roughly) an unsubtituted type for MyStruct<T>:
```
DW_TAG_structure_type
    DW_AT_name	("MyStruct")
    // "$s1w8MyStructVyxGD" is a Swift mangled name roughly equivalent to
    // MyStruct<T>
    DW_AT_linkage_name	("$s1w8MyStructVyxGD")
    // other attributes here
```
And a specification for MyStruct<Int>:
```
DW_TAG_structure_type
    DW_AT_specification	(<link to "MyStruct">)
    // "$s1w8MyStructVySiGD" is a Swift mangled name equivalent to
    // MyStruct<Int>
    DW_AT_linkage_name	("$s1w8MyStructVySiGD")
    DW_AT_byte_size	(0x08)
    // other attributes here
```

(cherry picked from commit 67fb268)

Author: augusto2112

llvm/include/llvm/IR/DIBuilder.h

@@ -488,9 +488,8 @@ namespace llvm {
     /// \param Elements     Struct elements.
     /// \param RunTimeLang  Optional parameter, Objective-C runtime version.
     /// \param UniqueIdentifier A unique identifier for the struct.
-    /// \param SpecificationOf The type that this type completes (is a
-    /// specification of). For example, this could be a templated type whose
-    /// template parameters have been substituted in.
+    /// \param Specification The type that this type completes. This is used by
+    /// Swift to represent generic types.
     /// \param NumExtraInhabitants The number of extra inhabitants of the type.
     /// An extra inhabitant is a bit pattern that does not represent a valid
     /// value for instances of a given type.
@@ -499,7 +498,7 @@ namespace llvm {
         uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags,
         DIType *DerivedFrom, DINodeArray Elements, unsigned RunTimeLang = 0,
         DIType *VTableHolder = nullptr, StringRef UniqueIdentifier = "",
-        DIType *SpecificationOf = nullptr, uint32_t NumExtraInhabitants = 0);
+        DIType *Specification = nullptr, uint32_t NumExtraInhabitants = 0);
 
     /// Create debugging information entry for an union.
     /// \param Scope        Scope in which this union is defined.

llvm/include/llvm/IR/DebugInfoMetadata.h

@@ -1205,7 +1205,7 @@ class DICompositeType : public DIType {
   static DICompositeType *
   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 AlignInBits, uint64_t OffsetInBits, DIType *Specification,
           uint32_t NumExtraInhabitants, DIFlags Flags, DINodeArray Elements,
           unsigned RuntimeLang, DIType *VTableHolder,
           DITemplateParameterArray TemplateParams, StringRef Identifier,
@@ -1219,7 +1219,7 @@ class DICompositeType : public DIType {
                    TemplateParams.get(),
                    getCanonicalMDString(Context, Identifier), Discriminator,
                    DataLocation, Associated, Allocated, Rank, Annotations.get(),
-                   SpecificationOf, NumExtraInhabitants, Storage, ShouldCreate);
+                   Specification, NumExtraInhabitants, Storage, ShouldCreate);
   }
   static DICompositeType *
   getImpl(LLVMContext &Context, unsigned Tag, MDString *Name, Metadata *File,
@@ -1229,7 +1229,7 @@ class DICompositeType : public DIType {
           Metadata *VTableHolder, Metadata *TemplateParams,
           MDString *Identifier, Metadata *Discriminator, Metadata *DataLocation,
           Metadata *Associated, Metadata *Allocated, Metadata *Rank,
-          Metadata *Annotations, Metadata *SpecificationOf,
+          Metadata *Annotations, Metadata *Specification,
           uint32_t NumExtraInhabitants, StorageType Storage,
           bool ShouldCreate = true);
 
@@ -1240,7 +1240,7 @@ class DICompositeType : public DIType {
         getFlags(), getElements(), getRuntimeLang(), getVTableHolder(),
         getTemplateParams(), getIdentifier(), getDiscriminator(),
         getRawDataLocation(), getRawAssociated(), getRawAllocated(),
-        getRawRank(), getAnnotations(), getSpecificationOf(),
+        getRawRank(), getAnnotations(), getSpecification(),
         getNumExtraInhabitants());
   }
 
@@ -1255,10 +1255,10 @@ class DICompositeType : public DIType {
        StringRef Identifier = "", DIDerivedType *Discriminator = nullptr,
        Metadata *DataLocation = nullptr, Metadata *Associated = nullptr,
        Metadata *Allocated = nullptr, Metadata *Rank = nullptr,
-       DINodeArray Annotations = nullptr, DIType *SpecificationOf = nullptr,
+       DINodeArray Annotations = nullptr, DIType *Specification = nullptr,
        uint32_t NumExtraInhabitants = 0),
       (Tag, Name, File, Line, Scope, BaseType, SizeInBits, AlignInBits,
-       OffsetInBits, SpecificationOf, NumExtraInhabitants, Flags, Elements,
+       OffsetInBits, Specification, NumExtraInhabitants, Flags, Elements,
        RuntimeLang, VTableHolder, TemplateParams, Identifier, Discriminator,
        DataLocation, Associated, Allocated, Rank, Annotations))
   DEFINE_MDNODE_GET(
@@ -1271,11 +1271,11 @@ 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),
+       Metadata *Specification = 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))
+       Annotations, Specification, NumExtraInhabitants))
 
   TempDICompositeType clone() const { return cloneImpl(); }
 
@@ -1290,9 +1290,9 @@ class DICompositeType : public DIType {
   getODRType(LLVMContext &Context, MDString &Identifier, unsigned Tag,
              MDString *Name, Metadata *File, unsigned Line, Metadata *Scope,
              Metadata *BaseType, uint64_t SizeInBits, uint32_t AlignInBits,
-             uint64_t OffsetInBits, Metadata *SpecificationOf,
-             uint32_t NumExtraInhabitants,  DIFlags Flags,
-             Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
+             uint64_t OffsetInBits, Metadata *Specification,
+             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);
@@ -1312,7 +1312,7 @@ class DICompositeType : public DIType {
   buildODRType(LLVMContext &Context, MDString &Identifier, unsigned Tag,
                MDString *Name, Metadata *File, unsigned Line, Metadata *Scope,
                Metadata *BaseType, uint64_t SizeInBits, uint32_t AlignInBits,
-               uint64_t OffsetInBits, Metadata *SpecificationOf,
+               uint64_t OffsetInBits, Metadata *Specification,
                uint32_t NumExtraInhabitants, DIFlags Flags, Metadata *Elements,
                unsigned RuntimeLang, Metadata *VTableHolder,
                Metadata *TemplateParams, Metadata *Discriminator,
@@ -1377,11 +1377,10 @@ class DICompositeType : public DIType {
     return cast_or_null<MDTuple>(getRawAnnotations());
   }
 
-  Metadata *getRawSpecificationOf() const { return getOperand(14); }
-  DIType *getSpecificationOf() const {
-    return cast_or_null<DIType>(getRawSpecificationOf());
+  Metadata *getRawSpecification() const { return getOperand(14); }
+  DIType *getSpecification() const {
+    return cast_or_null<DIType>(getRawSpecification());
   }
-
   /// Replace operands.
   ///
   /// If this \a isUniqued() and not \a isResolved(), on a uniquing collision

llvm/lib/AsmParser/LLParser.cpp

@@ -5433,7 +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(specification, MDField, );
   PARSE_MD_FIELDS();
 #undef VISIT_MD_FIELDS
 
@@ -5449,7 +5449,7 @@ 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, flags.Val,
+            specification.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)) {
@@ -5465,7 +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));
+       annotations.Val, specification.Val, num_extra_inhabitants.Val));
   return false;
 }
 

llvm/lib/Bitcode/Reader/MetadataLoader.cpp

@@ -1633,7 +1633,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
     Metadata *Allocated = nullptr;
     Metadata *Rank = nullptr;
     Metadata *Annotations = nullptr;
-    Metadata *SpecificationOf = nullptr;
+    Metadata *Specification = nullptr;
     auto *Identifier = getMDString(Record[15]);
     // If this module is being parsed so that it can be ThinLTO imported
     // into another module, composite types only need to be imported as
@@ -1683,14 +1683,14 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
         Annotations = getMDOrNull(Record[21]);
       }
       if (Record.size() > 23) {
-        SpecificationOf = getMDOrNull(Record[23]);
+        Specification = getMDOrNull(Record[23]);
       }
     }
     DICompositeType *CT = nullptr;
     if (Identifier)
       CT = DICompositeType::buildODRType(
           Context, *Identifier, Tag, Name, File, Line, Scope, BaseType,
-          SizeInBits, AlignInBits, OffsetInBits, SpecificationOf,
+          SizeInBits, AlignInBits, OffsetInBits, Specification,
           NumExtraInhabitants, Flags, Elements, RuntimeLang, VTableHolder,
           TemplateParams, Discriminator, DataLocation, Associated, Allocated,
           Rank, Annotations);
@@ -1702,7 +1702,7 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
                             SizeInBits, AlignInBits, OffsetInBits, Flags,
                             Elements, RuntimeLang, VTableHolder, TemplateParams,
                             Identifier, Discriminator, DataLocation, Associated,
-                            Allocated, Rank, Annotations, SpecificationOf,
+                            Allocated, Rank, Annotations, Specification,
                             NumExtraInhabitants));
     if (!IsNotUsedInTypeRef && Identifier)
       MetadataList.addTypeRef(*Identifier, *cast<DICompositeType>(CT));

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -1928,7 +1928,7 @@ void ModuleBitcodeWriter::writeDICompositeType(
   Record.push_back(VE.getMetadataOrNullID(N->getRawRank()));
   Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
   Record.push_back(N->getNumExtraInhabitants());
-  Record.push_back(VE.getMetadataOrNullID(N->getRawSpecificationOf()));
+  Record.push_back(VE.getMetadataOrNullID(N->getRawSpecification()));
 
   Stream.EmitRecord(bitc::METADATA_COMPOSITE_TYPE, Record, Abbrev);
   Record.clear();

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -1045,7 +1045,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
                 CC);
     }
 
-    if (auto *SpecifiedFrom = CTy->getSpecificationOf())
+    if (auto *SpecifiedFrom = CTy->getSpecification())
       addDIEEntry(Buffer, dwarf::DW_AT_specification,
                   *getOrCreateContextDIE(SpecifiedFrom));
 

llvm/lib/IR/AsmWriter.cpp

@@ -2219,8 +2219,8 @@ static void writeDICompositeType(raw_ostream &Out, const DICompositeType *N,
   else
     Printer.printMetadata("rank", N->getRawRank(), /*ShouldSkipNull */ true);
   Printer.printMetadata("annotations", N->getRawAnnotations());
-  if (auto *SpecificationOf = N->getRawSpecificationOf())
-    Printer.printMetadata("specification_of", SpecificationOf);
+  if (auto *Specification = N->getRawSpecification())
+    Printer.printMetadata("specification", Specification);
   Out << ")";
 }
 

llvm/lib/IR/DIBuilder.cpp

@@ -522,13 +522,13 @@ DICompositeType *DIBuilder::createStructType(
     DIScope *Context, StringRef Name, DIFile *File, unsigned LineNumber,
     uint64_t SizeInBits, uint32_t AlignInBits, DINode::DIFlags Flags,
     DIType *DerivedFrom, DINodeArray Elements, unsigned RunTimeLang,
-    DIType *VTableHolder, StringRef UniqueIdentifier, DIType *SpecificationOf,
+    DIType *VTableHolder, StringRef UniqueIdentifier, DIType *Specification,
     uint32_t NumExtraInhabitants) {
   auto *R = DICompositeType::get(
       VMContext, dwarf::DW_TAG_structure_type, Name, File, LineNumber,
       getNonCompileUnitScope(Context), DerivedFrom, SizeInBits, AlignInBits, 0,
       Flags, Elements, RunTimeLang, VTableHolder, nullptr, UniqueIdentifier,
-      nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, SpecificationOf,
+      nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, Specification,
       NumExtraInhabitants);
   trackIfUnresolved(R);
   return R;

llvm/lib/IR/DebugInfoMetadata.cpp

@@ -770,9 +770,8 @@ DICompositeType *DICompositeType::getImpl(
     Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
     Metadata *TemplateParams, MDString *Identifier, Metadata *Discriminator,
     Metadata *DataLocation, Metadata *Associated, Metadata *Allocated,
-    Metadata *Rank, Metadata *Annotations, Metadata *SpecificationOf,
-    uint32_t NumExtraInhabitants,  StorageType Storage,
-    bool ShouldCreate) {
+    Metadata *Rank, Metadata *Annotations, Metadata *Specification,
+    uint32_t NumExtraInhabitants, StorageType Storage, bool ShouldCreate) {
   assert(isCanonical(Name) && "Expected canonical MDString");
 
   // Keep this in sync with buildODRType.
@@ -781,11 +780,11 @@ DICompositeType *DICompositeType::getImpl(
       (Tag, Name, File, Line, Scope, BaseType, SizeInBits, AlignInBits,
        OffsetInBits, Flags, Elements, RuntimeLang, VTableHolder, TemplateParams,
        Identifier, Discriminator, DataLocation, Associated, Allocated, Rank,
-       Annotations, SpecificationOf, NumExtraInhabitants));
+       Annotations, Specification, NumExtraInhabitants));
   Metadata *Ops[] = {File,          Scope,        Name,           BaseType,
                      Elements,      VTableHolder, TemplateParams, Identifier,
                      Discriminator, DataLocation, Associated,     Allocated,
-                     Rank,          Annotations,  SpecificationOf};
+                     Rank,          Annotations,  Specification};
   DEFINE_GETIMPL_STORE(DICompositeType,
                        (Tag, Line, RuntimeLang, SizeInBits, AlignInBits,
                         OffsetInBits, NumExtraInhabitants, Flags),
@@ -796,7 +795,7 @@ DICompositeType *DICompositeType::buildODRType(
     LLVMContext &Context, MDString &Identifier, unsigned Tag, MDString *Name,
     Metadata *File, unsigned Line, Metadata *Scope, Metadata *BaseType,
     uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
-    Metadata *SpecificationOf, uint32_t NumExtraInhabitants, DIFlags Flags,
+    Metadata *Specification, uint32_t NumExtraInhabitants, DIFlags Flags,
     Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
     Metadata *TemplateParams, Metadata *Discriminator, Metadata *DataLocation,
     Metadata *Associated, Metadata *Allocated, Metadata *Rank,
@@ -811,8 +810,7 @@ DICompositeType *DICompositeType::buildODRType(
                AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang,
                VTableHolder, TemplateParams, &Identifier, Discriminator,
                DataLocation, Associated, Allocated, Rank, Annotations,
-               SpecificationOf, NumExtraInhabitants);
-
+               Specification, NumExtraInhabitants);
   if (CT->getTag() != Tag)
     return nullptr;
 
@@ -827,7 +825,7 @@ DICompositeType *DICompositeType::buildODRType(
   Metadata *Ops[] = {File,          Scope,        Name,           BaseType,
                      Elements,      VTableHolder, TemplateParams, &Identifier,
                      Discriminator, DataLocation, Associated,     Allocated,
-                     Rank,          Annotations,  SpecificationOf};
+                     Rank,          Annotations,  Specification};
   assert((std::end(Ops) - std::begin(Ops)) == (int)CT->getNumOperands() &&
          "Mismatched number of operands");
   for (unsigned I = 0, E = CT->getNumOperands(); I != E; ++I)
@@ -840,7 +838,7 @@ DICompositeType *DICompositeType::getODRType(
     LLVMContext &Context, MDString &Identifier, unsigned Tag, MDString *Name,
     Metadata *File, unsigned Line, Metadata *Scope, Metadata *BaseType,
     uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
-    Metadata *SpecificationOf, uint32_t NumExtraInhabitants, DIFlags Flags,
+    Metadata *Specification, uint32_t NumExtraInhabitants, DIFlags Flags,
     Metadata *Elements, unsigned RuntimeLang, Metadata *VTableHolder,
     Metadata *TemplateParams, Metadata *Discriminator, Metadata *DataLocation,
     Metadata *Associated, Metadata *Allocated, Metadata *Rank,
@@ -854,7 +852,7 @@ DICompositeType *DICompositeType::getODRType(
         Context, Tag, Name, File, Line, Scope, BaseType, SizeInBits,
         AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang, VTableHolder,
         TemplateParams, &Identifier, Discriminator, DataLocation, Associated,
-        Allocated, Rank, Annotations, SpecificationOf, NumExtraInhabitants);
+        Allocated, Rank, Annotations, Specification, NumExtraInhabitants);
   } else {
     if (CT->getTag() != Tag)
       return nullptr;

llvm/lib/IR/LLVMContextImpl.h

@@ -655,7 +655,7 @@ template <> struct MDNodeKeyImpl<DICompositeType> {
   Metadata *Allocated;
   Metadata *Rank;
   Metadata *Annotations;
-  Metadata *SpecificationOf;
+  Metadata *Specification;
   uint32_t NumExtraInhabitants;
 
   MDNodeKeyImpl(unsigned Tag, MDString *Name, Metadata *File, unsigned Line,
@@ -666,17 +666,16 @@ template <> struct MDNodeKeyImpl<DICompositeType> {
                 MDString *Identifier, Metadata *Discriminator,
                 Metadata *DataLocation, Metadata *Associated,
                 Metadata *Allocated, Metadata *Rank, Metadata *Annotations,
-                Metadata *SpecificationOf, uint32_t NumExtraInhabitants) 
+                Metadata *Specification, uint32_t NumExtraInhabitants)
       : Tag(Tag), Name(Name), File(File), Line(Line), Scope(Scope),
         BaseType(BaseType), SizeInBits(SizeInBits), OffsetInBits(OffsetInBits),
         AlignInBits(AlignInBits), Flags(Flags), Elements(Elements),
         RuntimeLang(RuntimeLang), VTableHolder(VTableHolder),
         TemplateParams(TemplateParams), Identifier(Identifier),
         Discriminator(Discriminator), DataLocation(DataLocation),
         Associated(Associated), Allocated(Allocated), Rank(Rank),
-        Annotations(Annotations), SpecificationOf(SpecificationOf),
-        NumExtraInhabitants(NumExtraInhabitants) {
-  }
+        Annotations(Annotations), Specification(Specification),
+        NumExtraInhabitants(NumExtraInhabitants) {}
   MDNodeKeyImpl(const DICompositeType *N)
       : Tag(N->getTag()), Name(N->getRawName()), File(N->getRawFile()),
         Line(N->getLine()), Scope(N->getRawScope()),
@@ -690,7 +689,7 @@ template <> struct MDNodeKeyImpl<DICompositeType> {
         DataLocation(N->getRawDataLocation()),
         Associated(N->getRawAssociated()), Allocated(N->getRawAllocated()),
         Rank(N->getRawRank()), Annotations(N->getRawAnnotations()),
-        SpecificationOf(N->getSpecificationOf()),
+        Specification(N->getSpecification()),
         NumExtraInhabitants(N->getNumExtraInhabitants()) {}
 
   bool isKeyOf(const DICompositeType *RHS) const {
@@ -710,7 +709,7 @@ template <> struct MDNodeKeyImpl<DICompositeType> {
            Associated == RHS->getRawAssociated() &&
            Allocated == RHS->getRawAllocated() && Rank == RHS->getRawRank() &&
            Annotations == RHS->getRawAnnotations() &&
-           SpecificationOf == RHS->getSpecificationOf() &&
+           Specification == RHS->getSpecification() &&
            NumExtraInhabitants == RHS->getNumExtraInhabitants();
   }