[clang][DebugInfo] Revert "emit definitions for constant-initialized static data-members"

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -69,29 +69,6 @@ static uint32_t getDeclAlignIfRequired(const Decl *D, const ASTContext &Ctx) {
   return D->hasAttr<AlignedAttr>() ? D->getMaxAlignment() : 0;
 }
 
-/// Given a VarDecl corresponding to either the definition or
-/// declaration of a C++ static data member, if it has a constant
-/// initializer and is evaluatable, return the evaluated value.
-/// Returns std::nullopt otherwise.
-static std::optional<APValue>
-evaluateConstantInitializer(const clang::VarDecl *VD,
-                            const clang::ASTContext &Ctx) {
-  assert(VD != nullptr);
-
-  if (!VD->isStaticDataMember())
-    return std::nullopt;
-
-  if (!VD->isUsableInConstantExpressions(Ctx))
-    return std::nullopt;
-
-  auto const *InitExpr = VD->getAnyInitializer();
-  Expr::EvalResult Result;
-  if (!InitExpr->EvaluateAsConstantExpr(Result, Ctx))
-    return std::nullopt;
-
-  return Result.Val;
-}
-
 CGDebugInfo::CGDebugInfo(CodeGenModule &CGM)
     : CGM(CGM), DebugKind(CGM.getCodeGenOpts().getDebugInfo()),
       DebugTypeExtRefs(CGM.getCodeGenOpts().DebugTypeExtRefs),
@@ -1724,7 +1701,6 @@ CGDebugInfo::CreateRecordStaticField(const VarDecl *Var, llvm::DIType *RecordTy,
   llvm::DIDerivedType *GV = DBuilder.createStaticMemberType(
       RecordTy, VName, VUnit, LineNumber, VTy, Flags, C, Tag, Align);
   StaticDataMemberCache[Var->getCanonicalDecl()].reset(GV);
-  StaticDataMemberDefinitionsToEmit.push_back(Var->getCanonicalDecl());
   return GV;
 }
 
@@ -5628,41 +5604,6 @@ void CGDebugInfo::EmitGlobalVariable(const ValueDecl *VD, const APValue &Init) {
       TemplateParameters, Align));
 }
 
-void CGDebugInfo::EmitGlobalVariable(const VarDecl *VD) {
-  assert(CGM.getCodeGenOpts().hasReducedDebugInfo());
-  if (VD->hasAttr<NoDebugAttr>())
-    return;
-
-  const auto CacheIt = DeclCache.find(VD);
-  if (CacheIt != DeclCache.end())
-    return;
-
-  const auto InitVal = evaluateConstantInitializer(VD, CGM.getContext());
-  if (!InitVal)
-    return;
-
-  llvm::DIFile *Unit = nullptr;
-  llvm::DIScope *DContext = nullptr;
-  unsigned LineNo;
-  StringRef DeclName, LinkageName;
-  QualType T;
-  llvm::MDTuple *TemplateParameters = nullptr;
-  collectVarDeclProps(VD, Unit, LineNo, T, DeclName, LinkageName,
-                      TemplateParameters, DContext);
-
-  auto Align = getDeclAlignIfRequired(VD, CGM.getContext());
-  llvm::DINodeArray Annotations = CollectBTFDeclTagAnnotations(VD);
-  llvm::DIExpression *InitExpr = createConstantValueExpression(VD, *InitVal);
-
-  // Omit linkage name for variable definitions that represent constants.
-  // There hasn't been a need from consumers yet to have it attached.
-  DeclCache[VD].reset(DBuilder.createGlobalVariableExpression(
-      TheCU, DeclName, /* LinkageName */ {}, Unit, LineNo,
-      getOrCreateType(T, Unit), true, true, InitExpr,
-      getOrCreateStaticDataMemberDeclarationOrNull(VD), TemplateParameters,
-      Align, Annotations));
-}
-
 void CGDebugInfo::EmitExternalVariable(llvm::GlobalVariable *Var,
                                        const VarDecl *D) {
   assert(CGM.getCodeGenOpts().hasReducedDebugInfo());
@@ -5867,20 +5808,6 @@ void CGDebugInfo::setDwoId(uint64_t Signature) {
 }
 
 void CGDebugInfo::finalize() {
-  // We can't use a for-each here because `EmitGlobalVariable`
-  // may push new decls into `StaticDataMemberDefinitionsToEmit`,
-  // which would invalidate any iterator.
-  for (size_t i = 0; i < StaticDataMemberDefinitionsToEmit.size(); ++i) {
-    auto const *VD = StaticDataMemberDefinitionsToEmit[i];
-
-    assert(VD && VD->isStaticDataMember());
-
-    if (DeclCache.contains(VD))
-      continue;
-
-    EmitGlobalVariable(VD);
-  }
-
   // Creating types might create further types - invalidating the current
   // element and the size(), so don't cache/reference them.
   for (size_t i = 0; i != ObjCInterfaceCache.size(); ++i) {

clang/lib/CodeGen/CGDebugInfo.h

@@ -161,9 +161,6 @@ class CGDebugInfo {
   llvm::DenseMap<const Decl *, llvm::TypedTrackingMDRef<llvm::DIDerivedType>>
       StaticDataMemberCache;
 
-  /// Keeps track of static data members for which we should emit a definition.
-  std::vector<const VarDecl *> StaticDataMemberDefinitionsToEmit;
-
   using ParamDecl2StmtTy = llvm::DenseMap<const ParmVarDecl *, const Stmt *>;
   using Param2DILocTy =
       llvm::DenseMap<const ParmVarDecl *, llvm::DILocalVariable *>;
@@ -529,9 +526,6 @@ class CGDebugInfo {
   /// Emit a constant global variable's debug info.
   void EmitGlobalVariable(const ValueDecl *VD, const APValue &Init);
 
-  /// Emit debug-info for a variable with a constant initializer.
-  void EmitGlobalVariable(const VarDecl *VD);
-
   /// Emit information about an external variable.
   void EmitExternalVariable(llvm::GlobalVariable *GV, const VarDecl *Decl);
 

clang/test/CodeGenCXX/debug-info-class.cpp

@@ -117,18 +117,11 @@ int main(int argc, char **argv) {
 // CHECK-NOT:                             identifier:
 // CHECK-SAME:                            ){{$}}
 
-// CHECK:      !DIGlobalVariableExpression(var: ![[HDR_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, 52, DW_OP_stack_value))
-// CHECK:      ![[HDR_VAR]] = distinct !DIGlobalVariable(name: "HdrSize",
-// CHECK-SAME:                isLocal: true, isDefinition: true, declaration: ![[HDR_VAR_DECL:[0-9]+]])
-// CHECK:      ![[INT:[0-9]+]] = !DIBasicType(name: "int"
-// CHECK:      ![[HDR_VAR_DECL]] = !DIDerivedType(tag: DW_TAG_member, name: "HdrSize"
-
-// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "A"
-
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "I"
 // CHECK-NOT:              DIFlagFwdDecl
 // CHECK-SAME:             ){{$}}
 
+// CHECK:      ![[INT:[0-9]+]] = !DIBasicType(name: "int"
 // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "foo"
 // CHECK: !DICompositeType(tag: DW_TAG_class_type, name: "bar"
 // CHECK: !DICompositeType(tag: DW_TAG_union_type, name: "baz"
@@ -194,5 +187,8 @@ int main(int argc, char **argv) {
 // CHECK: [[G_INNER_I]] = !DIDerivedType(tag: DW_TAG_member, name: "j"
 // CHECK-SAME:                           baseType: ![[INT]]
 
+// CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "A"
+// CHECK: !DIDerivedType(tag: DW_TAG_member, name: "HdrSize"
+
 // CHECK: ![[EXCEPTLOC]] = !DILocation(line: 100,
 // CHECK: ![[RETLOC]] = !DILocation(line: 99,

clang/test/CodeGenCXX/debug-info-static-member.cpp

@@ -1,8 +1,8 @@
-// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,CPP11,NOT-MS %s
+// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,NOT-MS %s
 // RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 -std=c++98 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,NOT-MS %s
-// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 -std=c++11 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,CPP11,NOT-MS %s
-// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-5 -std=c++11 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF5,CPP11 %s
-// RUN: %clangxx -target x86_64-windows-msvc -g -gdwarf-4 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,CPP11 %s
+// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-4 -std=c++11 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4,NOT-MS %s
+// RUN: %clangxx -target x86_64-unknown-unknown -g -gdwarf-5 -std=c++11 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF5 %s
+// RUN: %clangxx -target x86_64-windows-msvc -g -gdwarf-4 %s -emit-llvm -S -o - | FileCheck --check-prefixes=CHECK,DWARF4 %s
 // PR14471
 
 // CHECK: @{{.*}}a{{.*}} = dso_local global i32 4, align 4, !dbg [[A:![0-9]+]]
@@ -166,15 +166,3 @@ struct y {
 };
 int y::z;
 }
-
-// CHECK:      !DIGlobalVariableExpression(var: ![[CONST_A_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, 1, DW_OP_stack_value))
-// CHECK:      ![[CONST_A_VAR]] = distinct !DIGlobalVariable(name: "const_a"
-// CHECK-SAME:                    isLocal: true, isDefinition: true, declaration: ![[CONST_A_DECL]])
-
-// CPP11:      !DIGlobalVariableExpression(var: ![[CONST_B_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, {{.*}}, DW_OP_stack_value))
-// CPP11:      ![[CONST_B_VAR]] = distinct !DIGlobalVariable(name: "const_b"
-// CPP11-SAME:                    isLocal: true, isDefinition: true, declaration: ![[CONST_B_DECL]])
-
-// CHECK:      !DIGlobalVariableExpression(var: ![[CONST_C_VAR:[0-9]+]], expr: !DIExpression(DW_OP_constu, 18, DW_OP_stack_value))
-// CHECK:      ![[CONST_C_VAR]] = distinct !DIGlobalVariable(name: "const_c"
-// CHECK-SAME:                    isLocal: true, isDefinition: true, declaration: ![[CONST_C_DECL]])

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

@@ -142,54 +142,6 @@ static bool ShouldIgnoreArtificialField(llvm::StringRef FieldName) {
          || FieldName.starts_with("_vptr.");
 }
 
-std::optional<DWARFFormValue>
-DWARFASTParserClang::FindConstantOnVariableDefinition(DWARFDIE die) {
-  assert(die.Tag() == DW_TAG_member || die.Tag() == DW_TAG_variable);
-
-  auto *dwarf = die.GetDWARF();
-  if (!dwarf)
-    return {};
-
-  ConstString name{die.GetName()};
-  if (!name)
-    return {};
-
-  auto *CU = die.GetCU();
-  if (!CU)
-    return {};
-
-  DWARFASTParser *dwarf_ast = dwarf->GetDWARFParser(*CU);
-  auto parent_decl_ctx = dwarf_ast->GetDeclContextContainingUIDFromDWARF(die);
-
-  // Make sure we populate the GetDieToVariable cache.
-  VariableList variables;
-  dwarf->FindGlobalVariables(name, parent_decl_ctx, UINT_MAX, variables);
-
-  // The cache contains the variable definition whose DW_AT_specification
-  // points to our declaration DIE. Look up that definition using our
-  // declaration.
-  auto const &die_to_var = dwarf->GetDIEToVariable();
-  auto it = die_to_var.find(die.GetDIE());
-  if (it == die_to_var.end())
-    return {};
-
-  auto var_sp = it->getSecond();
-  assert(var_sp != nullptr);
-
-  if (!var_sp->GetLocationIsConstantValueData())
-    return {};
-
-  auto def = dwarf->GetDIE(var_sp->GetID());
-  auto def_attrs = def.GetAttributes();
-  DWARFFormValue form_value;
-  if (!def_attrs.ExtractFormValueAtIndex(
-          def_attrs.FindAttributeIndex(llvm::dwarf::DW_AT_const_value),
-          form_value))
-    return {};
-
-  return form_value;
-}
-
 TypeSP DWARFASTParserClang::ParseTypeFromClangModule(const SymbolContext &sc,
                                                      const DWARFDIE &die,
                                                      Log *log) {
@@ -2916,23 +2868,11 @@ void DWARFASTParserClang::CreateStaticMemberVariable(
 
   bool unused;
   // TODO: Support float/double static members as well.
-  if (!ct.IsIntegerOrEnumerationType(unused))
+  if (!ct.IsIntegerOrEnumerationType(unused) || !attrs.const_value_form)
     return;
 
-  auto maybe_const_form_value = attrs.const_value_form;
-
-  // Newer versions of Clang don't emit the DW_AT_const_value
-  // on the declaration of an inline static data member. Instead
-  // it's attached to the definition DIE. If that's the case,
-  // try and fetch it.
-  if (!maybe_const_form_value) {
-    maybe_const_form_value = FindConstantOnVariableDefinition(die);
-    if (!maybe_const_form_value)
-      return;
-  }
-
   llvm::Expected<llvm::APInt> const_value_or_err =
-      ExtractIntFromFormValue(ct, *maybe_const_form_value);
+      ExtractIntFromFormValue(ct, *attrs.const_value_form);
   if (!const_value_or_err) {
     LLDB_LOG_ERROR(log, const_value_or_err.takeError(),
                    "Failed to add const value to variable {1}: {0}",

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h

@@ -413,17 +413,6 @@ class DWARFASTParserClang : public lldb_private::plugin::dwarf::DWARFASTParser {
                        lldb_private::CompilerType &class_clang_type,
                        const lldb::AccessType default_accesibility,
                        lldb_private::ClangASTImporter::LayoutInfo &layout_info);
-
-  /// Tries to find the definition DW_TAG_variable DIE of the the specified
-  /// DW_TAG_member 'die'. If such definition exists, returns the
-  /// DW_AT_const_value of that definition if available. Returns std::nullopt
-  /// otherwise.
-  ///
-  /// In newer versions of clang, DW_AT_const_value attributes are not attached
-  /// to the declaration of a inline static data-member anymore, but rather on
-  /// its definition. This function is used to locate said constant.
-  std::optional<lldb_private::plugin::dwarf::DWARFFormValue>
-  FindConstantOnVariableDefinition(lldb_private::plugin::dwarf::DWARFDIE die);
 };
 
 /// Parsed form of all attributes that are relevant for type reconstruction.