[DebugInfo] Emit a MultiPayloadEnum's spare bits mask in DWARF

Author: augusto2112

lib/IRGen/IRGenDebugInfo.cpp

@@ -1066,6 +1066,9 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
     for (VarDecl *VD : Decl->getStoredProperties()) {
       auto memberTy = BaseTy->getTypeOfMember(IGM.getSwiftModule(), VD);
 
+      auto &TI = IGM.getTypeInfoForUnlowered(
+          IGM.getSILTypes().getAbstractionPattern(VD), memberTy);
+
       if (auto DbgTy = CompletedDebugTypeInfo::getFromTypeInfo(
               VD->getInterfaceType(),
               IGM.getTypeInfoForUnlowered(
@@ -1186,6 +1189,7 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
   llvm::DICompositeType *createVariantType(CompletedDebugTypeInfo DbgTy,
                                            EnumDecl *Decl,
                                            StringRef MangledName,
+                                           unsigned AlignInBits,
                                            llvm::DIScope *Scope,
                                            llvm::DIFile *File, unsigned Line,
                                            llvm::DINode::DIFlags Flags) {
@@ -1195,7 +1199,6 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
     StringRef Name = Decl->getName().str();
     unsigned SizeInBits = DbgTy.getSizeInBits();
     // Default, since Swift doesn't allow specifying a custom alignment.
-    unsigned AlignInBits = 0;
     auto NumExtraInhabitants = DbgTy.getNumExtraInhabitants();
 
     // A variant part should actually be a child to a DW_TAG_structure_type
@@ -1235,27 +1238,42 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
         Elements.push_back(MTy);
       }
     }
-    auto VPTy = DBuilder.createVariantPart(Scope, {}, File, Line, SizeInBits,
-                                           AlignInBits, Flags, nullptr,
-                                           DBuilder.getOrCreateArray(Elements));
+
+    APInt SpareBitsMask;
+    auto &EnumStrategy =
+        getEnumImplStrategy(IGM, DbgTy.getType()->getCanonicalType());
+
+    auto VariantOffsetInBits = 0;
+    if (auto SpareBitsMaskInfo = EnumStrategy.calculateSpareBitsMask()) {
+      SpareBitsMask = SpareBitsMaskInfo->bits;
+      // The offset of the variant mask in the overall enum.
+      VariantOffsetInBits = SpareBitsMaskInfo->byteOffset * 8;
+    }
+
+    auto VPTy = DBuilder.createVariantPart(
+        Scope, {}, File, Line, SizeInBits, AlignInBits, Flags, nullptr,
+        DBuilder.getOrCreateArray(Elements), /*UniqueIdentifier=*/"",
+        VariantOffsetInBits, SpareBitsMask);
+
     auto DITy = DBuilder.createStructType(
         Scope, Name, File, Line, SizeInBits, AlignInBits, Flags, nullptr,
         DBuilder.getOrCreateArray(VPTy), llvm::dwarf::DW_LANG_Swift, nullptr,
-        MangledName, NumExtraInhabitants ? *NumExtraInhabitants : 0);
+        MangledName, NumExtraInhabitants.value_or(0));
     DBuilder.replaceTemporary(std::move(FwdDecl), DITy);
     return DITy;
   }
 
   llvm::DICompositeType *createEnumType(CompletedDebugTypeInfo DbgTy,
                                         EnumDecl *Decl, StringRef MangledName,
+                                        unsigned AlignInBits,
                                         llvm::DIScope *Scope,
                                         llvm::DIFile *File, unsigned Line,
                                         llvm::DINode::DIFlags Flags) {
     if (Decl->hasRawType())
       return createRawEnumType(DbgTy, Decl, MangledName, Scope, File, Line,
                                Flags);
-    return createVariantType(DbgTy, Decl, MangledName, Scope, File, Line,
-                             Flags);
+    return createVariantType(DbgTy, Decl, MangledName, AlignInBits, Scope, File,
+                             Line, Flags);
   }
 
   llvm::DIType *getOrCreateDesugaredType(Type Ty, DebugTypeInfo DbgTy) {
@@ -1868,8 +1886,8 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
       unsigned FwdDeclLine = 0;
       if (Opts.DebugInfoLevel > IRGenDebugInfoLevel::ASTTypes)
         if (auto CompletedDbgTy = CompletedDebugTypeInfo::get(DbgTy))
-          return createEnumType(*CompletedDbgTy, Decl, MangledName, Scope,
-                                L.File, L.Line, Flags);
+          return createEnumType(*CompletedDbgTy, Decl, MangledName, AlignInBits,
+                                Scope, L.File, L.Line, Flags);
       return createOpaqueStruct(Scope, Decl->getName().str(), L.File,
                                 FwdDeclLine, SizeInBits, AlignInBits, Flags,
                                 MangledName);

test/DebugInfo/enum.swift

@@ -28,6 +28,22 @@ enum Either {
 // CHECK: ![[EMPTY:.*]] = !{}
 let E : Either = .Neither;
 
+class C {}
+enum EitherWithSpareBits {
+  case Left(C), Right(Int32)
+// DWARF: !DICompositeType(tag: DW_TAG_structure_type, name: "EitherWithSpareBits", 
+// DWARF-SAME:             size: 64,
+// DWARF-SAME:             runtimeLang: DW_LANG_Swift, identifier: "$s4enum19EitherWithSpareBitsOD")
+
+// DWARF: !DICompositeType(tag: DW_TAG_variant_part,
+// DWARF-SAME:             size: 64, offset: 56, spare_bits_mask: {{240|255}}
+
+// DWARF: !DIDerivedType(tag: DW_TAG_member, name: "Left"
+
+// DWARF: !DIDerivedType(tag: DW_TAG_member, name: "Right"
+}
+let Right: EitherWithSpareBits = .Right(32)
+
 // CHECK: !DICompositeType({{.*}}name: "Color",
 // CHECK-SAME:             size: 8,
 // CHECK-SAME:             identifier: "$s4enum5ColorOD"
@@ -102,3 +118,6 @@ public enum List<T> {
 // CHECK-DAG: ![[LIST_MEMBER]] = !DIDerivedType(tag: DW_TAG_member, {{.*}} baseType: ![[LIST:[0-9]+]]
 // CHECK-DAG: ![[LIST]] = !DICompositeType({{.*}}name: "$s4enum4ListOyxGD",{{.*}}DIFlagFwdDecl
 }
+
+
+