[Runtime] Mangle the reference kind in the lower two bits of type references.

DougGregor · DougGregor · commit 310bd6be4854 · 2018-01-03T10:49:21.000-08:00
The separate section of type references uses the same type reference format
as in protocol conformance records. As with protocol conformance records,
mangle the type reference kind into the lower two bits. Then, eliminate the
separate "flags" field from the type metadata record. Finally, rename
the section because the Swift 5 stable format for this section is
different from prior formats, and the two runtimes need to be able to
coexist.
diff --git a/include/swift/Runtime/Metadata.h b/include/swift/Runtime/Metadata.h
@@ -2460,23 +2460,22 @@ struct TargetTypeMetadataRecord {
   // Some description of the type that is resolvable at runtime.
   union {
     /// A direct reference to the metadata.
-    RelativeDirectPointer<const TargetMetadata<Runtime>> DirectType;
+    RelativeDirectPointerIntPair<const TargetMetadata<Runtime>,
+                                 TypeMetadataRecordKind> DirectType;
 
     /// The nominal type descriptor for a resilient or generic type.
-    RelativeDirectPointer<TargetNominalTypeDescriptor<Runtime>>
+    RelativeDirectPointerIntPair<TargetNominalTypeDescriptor<Runtime>,
+                                 TypeMetadataRecordKind>
       TypeDescriptor;
   };
 
-  /// Flags describing the type metadata record.
-  TypeMetadataRecordFlags Flags;
-  
 public:
   TypeMetadataRecordKind getTypeKind() const {
-    return Flags.getTypeKind();
+    return DirectType.getInt();
   }
   
   const TargetMetadata<Runtime> *getDirectType() const {
-    switch (Flags.getTypeKind()) {
+    switch (getTypeKind()) {
     case TypeMetadataRecordKind::NonuniqueDirectType:
       break;
         
@@ -2486,12 +2485,12 @@ struct TargetTypeMetadataRecord {
       assert(false && "not direct type metadata");
     }
 
-    return this->DirectType;
+    return this->DirectType.getPointer();
   }
 
   const TargetNominalTypeDescriptor<Runtime> *
   getNominalTypeDescriptor() const {
-    switch (Flags.getTypeKind()) {
+    switch (getTypeKind()) {
     case TypeMetadataRecordKind::DirectNominalTypeDescriptor:
       break;
         
@@ -2501,7 +2500,7 @@ struct TargetTypeMetadataRecord {
       assert(false && "not generic metadata pattern");
     }
     
-    return this->TypeDescriptor;
+    return this->TypeDescriptor.getPointer();
   }
 
   /// Get the canonical metadata for the type referenced by this record, or
diff --git a/lib/IRGen/GenDecl.cpp b/lib/IRGen/GenDecl.cpp
@@ -2401,13 +2401,13 @@ llvm::Constant *IRGenModule::emitTypeMetadataRecords() {
   std::string sectionName;
   switch (TargetInfo.OutputObjectFormat) {
   case llvm::Triple::MachO:
-    sectionName = "__TEXT, __swift2_types, regular, no_dead_strip";
+    sectionName = "__TEXT, __swift5_types, regular, no_dead_strip";
     break;
   case llvm::Triple::ELF:
-    sectionName = "swift2_type_metadata";
+    sectionName = "swift5_type_metadata";
     break;
   case llvm::Triple::COFF:
-    sectionName = ".sw2tymd$B";
+    sectionName = ".sw5tymd$B";
     break;
   default:
     llvm_unreachable("Don't know how to emit type metadata table for "
@@ -2437,14 +2437,19 @@ llvm::Constant *IRGenModule::emitTypeMetadataRecords() {
     auto typeEntity = getTypeEntityInfo(*this, type);
     auto typeRef = getAddrOfLLVMVariableOrGOTEquivalent(
             typeEntity.entity, getPointerAlignment(), typeEntity.defaultTy);
+    typeEntity.adjustForKnownRef(typeRef);
 
+    // Form the relative address, with the type refernce kind in the low bits.
     unsigned arrayIdx = elts.size();
-    llvm::Constant *recordFields[] = {
-      emitRelativeReference(typeRef, var, { arrayIdx, 0 }),
-      llvm::ConstantInt::get(Int32Ty,
-                             static_cast<unsigned>(typeEntity.typeKind)),
-    };
+    llvm::Constant *relativeAddr =
+      emitDirectRelativeReference(typeRef.getValue(), var, { arrayIdx, 0 });
+    unsigned lowBits = static_cast<unsigned>(typeEntity.typeKind);
+    if (lowBits != 0) {
+      relativeAddr = llvm::ConstantExpr::getAdd(relativeAddr,
+                       llvm::ConstantInt::get(RelativeAddressTy, lowBits));
+    }
 
+    llvm::Constant *recordFields[] = { relativeAddr };
     auto record = llvm::ConstantStruct::get(TypeMetadataRecordTy,
                                             recordFields);
     elts.push_back(record);
@@ -2454,7 +2459,7 @@ llvm::Constant *IRGenModule::emitTypeMetadataRecords() {
 
   var->setInitializer(initializer);
   var->setSection(sectionName);
-  var->setAlignment(getPointerAlignment().getValue());
+  var->setAlignment(4);
   addUsedGlobal(var);
   return var;
 }
diff --git a/lib/IRGen/IRGenModule.cpp b/lib/IRGen/IRGenModule.cpp
@@ -304,8 +304,7 @@ IRGenModule::IRGenModule(IRGenerator &irgen,
 
   TypeMetadataRecordTy
     = createStructType(*this, "swift.type_metadata_record", {
-      RelativeAddressTy,
-      Int32Ty
+      RelativeAddressTy
     });
   TypeMetadataRecordPtrTy
     = TypeMetadataRecordTy->getPointerTo(DefaultAS);
diff --git a/stdlib/public/runtime/ImageInspectionCOFF.cpp b/stdlib/public/runtime/ImageInspectionCOFF.cpp
@@ -56,7 +56,7 @@ void swift::initializeTypeMetadataRecordLookup() {
   const swift::MetadataSections *sections = registered;
   while (true) {
     const swift::MetadataSections::Range &type_metadata =
-        sections->swift2_type_metadata;
+        sections->swift5_type_metadata;
     if (type_metadata.length)
       addImageTypeMetadataRecordBlockCallback(reinterpret_cast<void *>(type_metadata.start),
                                               type_metadata.length);
@@ -81,7 +81,7 @@ void swift_addNewDSOImage(const void *addr) {
     addImageProtocolConformanceBlockCallback(conformances,
                                              protocol_conformances.length);
 
-  const auto &type_metadata = sections->swift2_type_metadata;
+  const auto &type_metadata = sections->swift5_type_metadata;
   const void *metadata = reinterpret_cast<void *>(type_metadata.start);
   if (type_metadata.length)
     addImageTypeMetadataRecordBlockCallback(metadata, type_metadata.length);
diff --git a/stdlib/public/runtime/ImageInspectionCOFF.h b/stdlib/public/runtime/ImageInspectionCOFF.h
@@ -46,7 +46,7 @@ struct MetadataSections {
   };
 
   Range swift5_protocol_conformances;
-  Range swift2_type_metadata;
+  Range swift5_type_metadata;
   Range swift3_typeref;
   Range swift3_reflstr;
   Range swift3_fieldmd;
diff --git a/stdlib/public/runtime/ImageInspectionELF.cpp b/stdlib/public/runtime/ImageInspectionELF.cpp
@@ -61,7 +61,7 @@ void swift::initializeTypeMetadataRecordLookup() {
   const swift::MetadataSections *sections = registered;
   while (true) {
     const swift::MetadataSections::Range &type_metadata =
-        sections->swift2_type_metadata;
+        sections->swift5_type_metadata;
     if (type_metadata.length)
       addImageTypeMetadataRecordBlockCallback(reinterpret_cast<void *>(type_metadata.start),
                                               type_metadata.length);
@@ -90,7 +90,7 @@ void swift_addNewDSOImage(const void *addr) {
     addImageProtocolConformanceBlockCallback(conformances,
                                              protocol_conformances.length);
 
-  const auto &type_metadata = sections->swift2_type_metadata;
+  const auto &type_metadata = sections->swift5_type_metadata;
   const void *metadata = reinterpret_cast<void *>(type_metadata.start);
   if (type_metadata.length)
     addImageTypeMetadataRecordBlockCallback(metadata, type_metadata.length);
diff --git a/stdlib/public/runtime/ImageInspectionELF.h b/stdlib/public/runtime/ImageInspectionELF.h
@@ -46,7 +46,7 @@ struct MetadataSections {
   };
 
   Range swift5_protocol_conformances;
-  Range swift2_type_metadata;
+  Range swift5_type_metadata;
   Range swift3_typeref;
   Range swift3_reflstr;
   Range swift3_fieldmd;
diff --git a/stdlib/public/runtime/ImageInspectionMachO.cpp b/stdlib/public/runtime/ImageInspectionMachO.cpp
@@ -34,7 +34,7 @@ namespace {
 constexpr const char ProtocolConformancesSection[] = "__swift5_proto";
 /// The Mach-O section name for the section containing type references.
 /// This lives within SEG_TEXT.
-constexpr const char TypeMetadataRecordSection[] = "__swift2_types";
+constexpr const char TypeMetadataRecordSection[] = "__swift5_types";
 
 template<const char *SECTION_NAME,
          void CONSUME_BLOCK(const void *start, uintptr_t size)>
diff --git a/stdlib/public/runtime/SwiftRT-ELF.cpp b/stdlib/public/runtime/SwiftRT-ELF.cpp
@@ -25,7 +25,7 @@
 
 extern "C" {
 DECLARE_SWIFT_SECTION(swift5_protocol_conformances)
-DECLARE_SWIFT_SECTION(swift2_type_metadata)
+DECLARE_SWIFT_SECTION(swift5_type_metadata)
 
 DECLARE_SWIFT_SECTION(swift3_typeref)
 DECLARE_SWIFT_SECTION(swift3_reflstr)
@@ -53,7 +53,7 @@ static void swift_image_constructor() {
       nullptr,
 
       SWIFT_SECTION_RANGE(swift5_protocol_conformances),
-      SWIFT_SECTION_RANGE(swift2_type_metadata),
+      SWIFT_SECTION_RANGE(swift5_type_metadata),
 
       SWIFT_SECTION_RANGE(swift3_typeref),
       SWIFT_SECTION_RANGE(swift3_reflstr),
