Add preliminary lifetimebound support to APINotes

This patch adds the ability to mark function and method parameters as
lifetimebound. Unfortunately, this does not support lifetimebound
annotating 'this' (putting the annotation on the method type instead of
on the parameters), or annotating constructors. For the latter, we need
to support to annotate overloaded functions are ctors are always
overloaded.

Author: Gabor Horvath

clang/include/clang/APINotes/Types.h

@@ -425,14 +425,24 @@ class ParamInfo : public VariableInfo {
   LLVM_PREFERRED_TYPE(bool)
   unsigned NoEscape : 1;
 
+  /// Whether lifetimebound was specified.
+  LLVM_PREFERRED_TYPE(bool)
+  unsigned LifetimeboundSpecified : 1;
+
+  /// Whether the this parameter has the 'lifetimebound' attribute.
+  LLVM_PREFERRED_TYPE(bool)
+  unsigned Lifetimebound : 1;
+
   /// A biased RetainCountConventionKind, where 0 means "unspecified".
   ///
   /// Only relevant for out-parameters.
   unsigned RawRetainCountConvention : 3;
 
 public:
   ParamInfo()
-      : NoEscapeSpecified(false), NoEscape(false), RawRetainCountConvention() {}
+      : NoEscapeSpecified(false), NoEscape(false),
+        LifetimeboundSpecified(false), Lifetimebound(false),
+        RawRetainCountConvention() {}
 
   std::optional<bool> isNoEscape() const {
     if (!NoEscapeSpecified)
@@ -444,6 +454,16 @@ class ParamInfo : public VariableInfo {
     NoEscape = Value.value_or(false);
   }
 
+  std::optional<bool> isLifetimebound() const {
+    if (!LifetimeboundSpecified)
+      return std::nullopt;
+    return Lifetimebound;
+  }
+  void setLifetimebound(std::optional<bool> Value) {
+    LifetimeboundSpecified = Value.has_value();
+    Lifetimebound = Value.value_or(false);
+  }
+
   std::optional<RetainCountConventionKind> getRetainCountConvention() const {
     if (!RawRetainCountConvention)
       return std::nullopt;
@@ -463,6 +483,11 @@ class ParamInfo : public VariableInfo {
       NoEscape = RHS.NoEscape;
     }
 
+    if (!LifetimeboundSpecified && RHS.LifetimeboundSpecified) {
+      LifetimeboundSpecified = true;
+      Lifetimebound = RHS.Lifetimebound;
+    }
+
     if (!RawRetainCountConvention)
       RawRetainCountConvention = RHS.RawRetainCountConvention;
 
@@ -478,6 +503,8 @@ inline bool operator==(const ParamInfo &LHS, const ParamInfo &RHS) {
   return static_cast<const VariableInfo &>(LHS) == RHS &&
          LHS.NoEscapeSpecified == RHS.NoEscapeSpecified &&
          LHS.NoEscape == RHS.NoEscape &&
+         LHS.LifetimeboundSpecified == RHS.LifetimeboundSpecified &&
+         LHS.Lifetimebound == RHS.Lifetimebound &&
          LHS.RawRetainCountConvention == RHS.RawRetainCountConvention;
 }
 

clang/lib/APINotes/APINotesFormat.h

@@ -24,7 +24,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// API notes file minor version number.
 ///
 /// When the format changes IN ANY WAY, this number should be incremented.
-const uint16_t VERSION_MINOR = 30; // fields
+const uint16_t VERSION_MINOR = 31; // lifetimebound
 
 const uint8_t kSwiftCopyable = 1;
 const uint8_t kSwiftNonCopyable = 2;

clang/lib/APINotes/APINotesReader.cpp

@@ -331,6 +331,9 @@ void ReadParamInfo(const uint8_t *&Data, ParamInfo &Info) {
     Info.setRetainCountConvention(Convention);
   }
   Payload >>= 3;
+  if (Payload & 0x01)
+    Info.setLifetimebound(Payload & 0x02);
+  Payload >>= 2;
   if (Payload & 0x01)
     Info.setNoEscape(Payload & 0x02);
   Payload >>= 2;

clang/lib/APINotes/APINotesTypes.cpp

@@ -65,6 +65,8 @@ LLVM_DUMP_METHOD void ParamInfo::dump(llvm::raw_ostream &OS) const {
   static_cast<const VariableInfo &>(*this).dump(OS);
   if (NoEscapeSpecified)
     OS << (NoEscape ? "[NoEscape] " : "");
+  if (LifetimeboundSpecified)
+    OS << (Lifetimebound ? "[Lifetimebound] " : "");
   OS << "RawRetainCountConvention: " << RawRetainCountConvention << ' ';
   OS << '\n';
 }

clang/lib/APINotes/APINotesWriter.cpp

@@ -1052,6 +1052,12 @@ void emitParamInfo(raw_ostream &OS, const ParamInfo &PI) {
     if (*noescape)
       flags |= 0x02;
   }
+  flags <<= 2;
+  if (auto lifetimebound = PI.isLifetimebound()) {
+    flags |= 0x01;
+    if (*lifetimebound)
+      flags |= 0x02;
+  }
   flags <<= 3;
   if (auto RCC = PI.getRetainCountConvention())
     flags |= static_cast<uint8_t>(RCC.value()) + 1;

clang/lib/APINotes/APINotesYAMLCompiler.cpp

@@ -70,6 +70,7 @@ namespace {
 struct Param {
   unsigned Position;
   std::optional<bool> NoEscape = false;
+  std::optional<bool> Lifetimebound = false;
   std::optional<NullabilityKind> Nullability;
   std::optional<RetainCountConventionKind> RetainCountConvention;
   StringRef Type;
@@ -121,6 +122,7 @@ template <> struct MappingTraits<Param> {
     IO.mapOptional("Nullability", P.Nullability, std::nullopt);
     IO.mapOptional("RetainCountConvention", P.RetainCountConvention);
     IO.mapOptional("NoEscape", P.NoEscape);
+    IO.mapOptional("Lifetimebound", P.Lifetimebound);
     IO.mapOptional("Type", P.Type, StringRef(""));
   }
 };
@@ -734,6 +736,7 @@ class YAMLConverter {
       if (P.Nullability)
         PI.setNullabilityAudited(*P.Nullability);
       PI.setNoEscape(P.NoEscape);
+      PI.setLifetimebound(P.Lifetimebound);
       PI.setType(std::string(P.Type));
       PI.setRetainCountConvention(P.RetainCountConvention);
       if (OutInfo.Params.size() <= P.Position)

clang/lib/Sema/SemaAPINotes.cpp

@@ -12,6 +12,7 @@
 
 #include "clang/APINotes/APINotesReader.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Lex/Lexer.h"
@@ -415,6 +416,13 @@ static void ProcessAPINotes(Sema &S, ParmVarDecl *D,
       return new (S.Context) NoEscapeAttr(S.Context, getPlaceholderAttrInfo());
     });
 
+  if (auto Lifetimebound = Info.isLifetimebound())
+    handleAPINotedAttribute<LifetimeBoundAttr>(
+        S, D, *Lifetimebound, Metadata, [&] {
+          return new (S.Context)
+              LifetimeBoundAttr(S.Context, getPlaceholderAttrInfo());
+        });
+
   // Retain count convention
   handleAPINotedRetainCountConvention(S, D, Metadata,
                                       Info.getRetainCountConvention());
@@ -860,13 +868,12 @@ void Sema::ProcessAPINotes(Decl *D) {
   if (!D)
     return;
 
+  auto *DC = D->getDeclContext();
   // Globals.
-  if (D->getDeclContext()->isFileContext() ||
-      D->getDeclContext()->isNamespace() ||
-      D->getDeclContext()->isExternCContext() ||
-      D->getDeclContext()->isExternCXXContext()) {
+  if (DC->isFileContext() || DC->isNamespace() || DC->isExternCContext() ||
+      DC->isExternCXXContext()) {
     std::optional<api_notes::Context> APINotesContext =
-        UnwindNamespaceContext(D->getDeclContext(), APINotes);
+        UnwindNamespaceContext(DC, APINotes);
     // Global variables.
     if (auto VD = dyn_cast<VarDecl>(D)) {
       for (auto Reader : APINotes.findAPINotes(D->getLocation())) {
@@ -967,8 +974,8 @@ void Sema::ProcessAPINotes(Decl *D) {
   }
 
   // Enumerators.
-  if (D->getDeclContext()->getRedeclContext()->isFileContext() ||
-      D->getDeclContext()->getRedeclContext()->isExternCContext()) {
+  if (DC->getRedeclContext()->isFileContext() ||
+      DC->getRedeclContext()->isExternCContext()) {
     if (auto EnumConstant = dyn_cast<EnumConstantDecl>(D)) {
       for (auto Reader : APINotes.findAPINotes(D->getLocation())) {
         auto Info = Reader->lookupEnumConstant(EnumConstant->getName());
@@ -979,7 +986,7 @@ void Sema::ProcessAPINotes(Decl *D) {
     }
   }
 
-  if (auto ObjCContainer = dyn_cast<ObjCContainerDecl>(D->getDeclContext())) {
+  if (auto ObjCContainer = dyn_cast<ObjCContainerDecl>(DC)) {
     // Location function that looks up an Objective-C context.
     auto GetContext = [&](api_notes::APINotesReader *Reader)
         -> std::optional<api_notes::ContextID> {
@@ -1063,7 +1070,7 @@ void Sema::ProcessAPINotes(Decl *D) {
     }
   }
 
-  if (auto TagContext = dyn_cast<TagDecl>(D->getDeclContext())) {
+  if (auto TagContext = dyn_cast<TagDecl>(DC)) {
     if (auto CXXMethod = dyn_cast<CXXMethodDecl>(D)) {
       if (!isa<CXXConstructorDecl>(CXXMethod) &&
           !isa<CXXDestructorDecl>(CXXMethod) &&

clang/test/APINotes/Inputs/Headers/Lifetimebound.apinotes

@@ -0,0 +1,14 @@
+---
+Name: Lifetimebound
+Functions:
+  - Name:              funcToAnnotate
+    Parameters:
+      - Position:      0
+        Lifetimebound: true
+Tags:
+- Name: MyClass
+  Methods:
+    - Name: methodToAnnotate
+      Parameters:
+        - Position:      0
+          Lifetimebound: true

clang/test/APINotes/Inputs/Headers/Lifetimebound.h

@@ -0,0 +1,8 @@
+int *funcToAnnotate(int *p);
+
+// TODO: support annotating ctors and 'this'.
+struct MyClass {
+    MyClass(int*);
+    int *annotateThis();
+    int *methodToAnnotate(int *p);
+};

clang/test/APINotes/Inputs/Headers/module.modulemap

@@ -17,6 +17,11 @@ module Fields {
   export *
 }
 
+module Lifetimebound {
+  header "Lifetimebound.h"
+  export *
+}
+
 module HeaderLib {
   header "HeaderLib.h"
 }