Merge pull request llvm#11298 from swiftlang/lldb/func-call-labels-to-21.x

🍒[lldb] Cherry-pick FunctionCallLabel support to 21.x

Author: Michael137

clang/include/clang/Basic/Attr.td

@@ -1084,22 +1084,13 @@ def AVRSignal : InheritableAttr, TargetSpecificAttr<TargetAVR> {
 def AsmLabel : InheritableAttr {
   let Spellings = [CustomKeyword<"asm">, CustomKeyword<"__asm__">];
   let Args = [
-    // Label specifies the mangled name for the decl.
-    StringArgument<"Label">,
-
-    // IsLiteralLabel specifies whether the label is literal (i.e. suppresses
-    // the global C symbol prefix) or not. If not, the mangle-suppression prefix
-    // ('\01') is omitted from the decl name at the LLVM IR level.
-    //
-    // Non-literal labels are used by some external AST sources like LLDB.
-    BoolArgument<"IsLiteralLabel", /*optional=*/0, /*fake=*/1>
-  ];
+      // Label specifies the mangled name for the decl.
+      StringArgument<"Label">, ];
   let SemaHandler = 0;
   let Documentation = [AsmLabelDocs];
-  let AdditionalMembers =
-[{
+  let AdditionalMembers = [{
 bool isEquivalent(AsmLabelAttr *Other) const {
-  return getLabel() == Other->getLabel() && getIsLiteralLabel() == Other->getIsLiteralLabel();
+  return getLabel() == Other->getLabel();
 }
 }];
 }

clang/lib/AST/Mangle.cpp

@@ -161,9 +161,9 @@ void MangleContext::mangleName(GlobalDecl GD, raw_ostream &Out) {
   if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
     // If we have an asm name, then we use it as the mangling.
 
-    // If the label isn't literal, or if this is an alias for an LLVM intrinsic,
+    // If the label is an alias for an LLVM intrinsic,
     // do not add a "\01" prefix.
-    if (!ALA->getIsLiteralLabel() || ALA->getLabel().starts_with("llvm.")) {
+    if (ALA->getLabel().starts_with("llvm.")) {
       Out << ALA->getLabel();
       return;
     }

clang/lib/Sema/SemaDecl.cpp

@@ -8951,9 +8951,7 @@ NamedDecl *Sema::ActOnVariableDeclarator(
       }
     }
 
-    NewVD->addAttr(AsmLabelAttr::Create(Context, Label,
-                                        /*IsLiteralLabel=*/true,
-                                        SE->getStrTokenLoc(0)));
+    NewVD->addAttr(AsmLabelAttr::Create(Context, Label, SE->getStrTokenLoc(0)));
   } else if (!ExtnameUndeclaredIdentifiers.empty()) {
     llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*>::iterator I =
       ExtnameUndeclaredIdentifiers.find(NewVD->getIdentifier());
@@ -11254,9 +11252,8 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
   if (Expr *E = D.getAsmLabel()) {
     // The parser guarantees this is a string.
     StringLiteral *SE = cast<StringLiteral>(E);
-    NewFD->addAttr(AsmLabelAttr::Create(Context, SE->getString(),
-                                        /*IsLiteralLabel=*/true,
-                                        SE->getStrTokenLoc(0)));
+    NewFD->addAttr(
+        AsmLabelAttr::Create(Context, SE->getString(), SE->getStrTokenLoc(0)));
   } else if (!ExtnameUndeclaredIdentifiers.empty()) {
     llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*>::iterator I =
       ExtnameUndeclaredIdentifiers.find(NewFD->getIdentifier());
@@ -21737,8 +21734,8 @@ void Sema::ActOnPragmaRedefineExtname(IdentifierInfo* Name,
                                          LookupOrdinaryName);
   AttributeCommonInfo Info(AliasName, SourceRange(AliasNameLoc),
                            AttributeCommonInfo::Form::Pragma());
-  AsmLabelAttr *Attr = AsmLabelAttr::CreateImplicit(
-      Context, AliasName->getName(), /*IsLiteralLabel=*/true, Info);
+  AsmLabelAttr *Attr =
+      AsmLabelAttr::CreateImplicit(Context, AliasName->getName(), Info);
 
   // If a declaration that:
   // 1) declares a function or a variable

clang/unittests/AST/DeclTest.cpp

@@ -131,7 +131,6 @@ TEST(Decl, AsmLabelAttr) {
   StringRef Code = R"(
     struct S {
       void f() {}
-      void g() {}
     };
   )";
   auto AST =
@@ -144,26 +143,20 @@ TEST(Decl, AsmLabelAttr) {
   const auto *DeclS =
       selectFirst<CXXRecordDecl>("d", match(cxxRecordDecl().bind("d"), Ctx));
   NamedDecl *DeclF = *DeclS->method_begin();
-  NamedDecl *DeclG = *(++DeclS->method_begin());
 
-  // Attach asm labels to the decls: one literal, and one not.
-  DeclF->addAttr(AsmLabelAttr::Create(Ctx, "foo", /*LiteralLabel=*/true));
-  DeclG->addAttr(AsmLabelAttr::Create(Ctx, "goo", /*LiteralLabel=*/false));
+  DeclF->addAttr(AsmLabelAttr::Create(Ctx, "foo"));
 
   // Mangle the decl names.
   std::string MangleF, MangleG;
   std::unique_ptr<ItaniumMangleContext> MC(
       ItaniumMangleContext::create(Ctx, Diags));
   {
     llvm::raw_string_ostream OS_F(MangleF);
-    llvm::raw_string_ostream OS_G(MangleG);
     MC->mangleName(DeclF, OS_F);
-    MC->mangleName(DeclG, OS_G);
   }
 
   ASSERT_EQ(MangleF, "\x01"
                      "foo");
-  ASSERT_EQ(MangleG, "goo");
 }
 
 TEST(Decl, MangleDependentSizedArray) {

lldb/include/lldb/Core/Module.h

@@ -88,7 +88,8 @@ struct ModuleFunctionSearchOptions {
 ///
 /// The module will parse more detailed information as more queries are made.
 class Module : public std::enable_shared_from_this<Module>,
-               public SymbolContextScope {
+               public SymbolContextScope,
+               public UserID {
 public:
   class LookupInfo;
   // Static functions that can track the lifetime of module objects. This is

lldb/include/lldb/Core/ModuleList.h

@@ -18,6 +18,7 @@
 #include "lldb/Utility/Status.h"
 #include "lldb/lldb-enumerations.h"
 #include "lldb/lldb-forward.h"
+#include "lldb/lldb-private-enumerations.h"
 #include "lldb/lldb-types.h"
 
 #include "llvm/ADT/DenseSet.h"
@@ -374,6 +375,14 @@ class ModuleList {
   // UUID values is very efficient and accurate.
   lldb::ModuleSP FindModule(const UUID &uuid) const;
 
+  /// Find a module by LLDB-specific unique identifier.
+  ///
+  /// \param[in] uid The UID of the module assigned to it on construction.
+  ///
+  /// \returns ModuleSP of module with \c uid. Returns nullptr if no such
+  /// module could be found.
+  lldb::ModuleSP FindModule(lldb::user_id_t uid) const;
+
   /// Finds the first module whose file specification matches \a module_spec.
   lldb::ModuleSP FindFirstModule(const ModuleSpec &module_spec) const;
 
@@ -530,8 +539,9 @@ class ModuleList {
   /// be non-null.
   ///
   /// This function is thread-safe.
-  void ForEach(std::function<bool(const lldb::ModuleSP &module_sp)> const
-                   &callback) const;
+  void
+  ForEach(std::function<IterationAction(const lldb::ModuleSP &module_sp)> const
+              &callback) const;
 
   void ClearModuleDependentCaches();
 

lldb/include/lldb/Expression/Expression.h

@@ -13,6 +13,7 @@
 #include <string>
 #include <vector>
 
+#include "llvm/Support/FormatProviders.h"
 
 #include "lldb/Expression/ExpressionTypeSystemHelper.h"
 #include "lldb/lldb-forward.h"
@@ -96,6 +97,62 @@ class Expression {
                                  ///invalid.
 };
 
+/// Holds parsed information about a function call label that
+/// LLDB attaches as an AsmLabel to function AST nodes it parses
+/// from debug-info.
+///
+/// The format being:
+///
+///   <prefix>:<module uid>:<symbol uid>:<name>
+///
+/// The label string needs to stay valid for the entire lifetime
+/// of this object.
+struct FunctionCallLabel {
+  /// Unique identifier of the lldb_private::Module
+  /// which contains the symbol identified by \c symbol_id.
+  lldb::user_id_t module_id;
+
+  /// Unique identifier of the function symbol on which to
+  /// perform the function call. For example, for DWARF this would
+  /// be the DIE UID.
+  lldb::user_id_t symbol_id;
+
+  /// Name to use when searching for the function symbol in
+  /// \c module_id. For most function calls this will be a
+  /// mangled name. In cases where a mangled name can't be used,
+  /// this will be the function name.
+  ///
+  /// NOTE: kept as last element so we don't have to worry about
+  /// ':' in the mangled name when parsing the label.
+  llvm::StringRef lookup_name;
+
+  /// Decodes the specified function \c label into a \c FunctionCallLabel.
+  static llvm::Expected<FunctionCallLabel> fromString(llvm::StringRef label);
+
+  /// Encode this FunctionCallLabel into its string representation.
+  ///
+  /// The representation roundtrips through \c fromString:
+  /// \code{.cpp}
+  /// llvm::StringRef encoded = "$__lldb_func:0x0:0x0:_Z3foov";
+  /// FunctionCallLabel label = *fromString(label);
+  ///
+  /// assert (label.toString() == encoded);
+  /// assert (*fromString(label.toString()) == label);
+  /// \endcode
+  std::string toString() const;
+};
+
+/// LLDB attaches this prefix to mangled names of functions that get called
+/// from JITted expressions.
+inline constexpr llvm::StringRef FunctionCallLabelPrefix = "$__lldb_func";
+
 } // namespace lldb_private
 
+namespace llvm {
+template <> struct format_provider<lldb_private::FunctionCallLabel> {
+  static void format(const lldb_private::FunctionCallLabel &label,
+                     raw_ostream &OS, StringRef Style);
+};
+} // namespace llvm
+
 #endif // LLDB_EXPRESSION_EXPRESSION_H

lldb/include/lldb/Symbol/SymbolFile.h

@@ -349,6 +349,18 @@ class SymbolFile : public PluginInterface {
   GetMangledNamesForFunction(const std::string &scope_qualified_name,
                              std::vector<ConstString> &mangled_names);
 
+  /// Resolves the function corresponding to the specified LLDB function
+  /// call \c label.
+  ///
+  /// \param[in] label The FunctionCallLabel to be resolved.
+  ///
+  /// \returns An llvm::Error if the specified \c label couldn't be resolved.
+  ///          Returns the resolved function (as a SymbolContext) otherwise.
+  virtual llvm::Expected<SymbolContext>
+  ResolveFunctionCallLabel(const FunctionCallLabel &label) {
+    return llvm::createStringError("Not implemented");
+  }
+
   virtual void GetTypes(lldb_private::SymbolContextScope *sc_scope,
                         lldb::TypeClass type_mask,
                         lldb_private::TypeList &type_list) = 0;

lldb/source/Commands/CommandCompletions.cpp

@@ -570,7 +570,7 @@ void CommandCompletions::ModuleUUIDs(CommandInterpreter &interpreter,
                                lldb::eDescriptionLevelInitial);
         request.TryCompleteCurrentArg(module->GetUUID().GetAsString(),
                                       strm.GetString());
-        return true;
+        return IterationAction::Continue;
       });
 }
 

lldb/source/Core/Module.cpp

@@ -135,8 +135,10 @@ Module *Module::GetAllocatedModuleAtIndex(size_t idx) {
   return nullptr;
 }
 
+static std::atomic<lldb::user_id_t> g_unique_id = 1;
+
 Module::Module(const ModuleSpec &module_spec)
-    : m_unwind_table(*this), m_file_has_changed(false),
+    : UserID(g_unique_id++), m_unwind_table(*this), m_file_has_changed(false),
       m_first_file_changed_log(false) {
   // Scope for locker below...
   {
@@ -241,7 +243,8 @@ Module::Module(const ModuleSpec &module_spec)
 Module::Module(const FileSpec &file_spec, const ArchSpec &arch,
                ConstString object_name, lldb::offset_t object_offset,
                const llvm::sys::TimePoint<> &object_mod_time)
-    : m_mod_time(FileSystem::Instance().GetModificationTime(file_spec)),
+    : UserID(g_unique_id++),
+      m_mod_time(FileSystem::Instance().GetModificationTime(file_spec)),
       m_arch(arch), m_file(file_spec), m_object_name(object_name),
       m_object_offset(object_offset), m_object_mod_time(object_mod_time),
       m_unwind_table(*this), m_file_has_changed(false),
@@ -262,7 +265,7 @@ Module::Module(const FileSpec &file_spec, const ArchSpec &arch,
 }
 
 Module::Module()
-    : m_unwind_table(*this), m_file_has_changed(false),
+    : UserID(g_unique_id++), m_unwind_table(*this), m_file_has_changed(false),
       m_first_file_changed_log(false) {
   std::lock_guard<std::recursive_mutex> guard(
       GetAllocationModuleCollectionMutex());