nonblocking/nonallocating attributes: 2nd pass caller/callee analysis

clang/include/clang/AST/Type.h

@@ -4699,7 +4699,7 @@ class FunctionEffect {
 
 private:
   LLVM_PREFERRED_TYPE(Kind)
-  unsigned FKind : 3;
+  uint8_t FKind : 3;
 
   // Expansion: for hypothetical TCB+types, there could be one Kind for TCB,
   // then ~16(?) bits "SubKind" to map to a specific named TCB. SubKind would

clang/include/clang/Basic/DiagnosticGroups.td

@@ -1557,6 +1557,7 @@ def UnsafeBufferUsage : DiagGroup<"unsafe-buffer-usage", [UnsafeBufferUsageInCon
 // Warnings and notes related to the function effects system underlying
 // the nonblocking and nonallocating attributes.
 def FunctionEffects : DiagGroup<"function-effects">;
+def PerfConstraintImpliesNoexcept : DiagGroup<"perf-constraint-implies-noexcept">;
 
 // Warnings and notes InstallAPI verification.
 def InstallAPIViolation : DiagGroup<"installapi-violation">;

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -10928,6 +10928,55 @@ def warn_imp_cast_drops_unaligned : Warning<
   InGroup<DiagGroup<"unaligned-qualifier-implicit-cast">>;
 
 // Function effects
+def warn_func_effect_allocates : Warning<
+  "'%0' function must not allocate or deallocate memory">,
+  InGroup<FunctionEffects>;
+def note_func_effect_allocates : Note<
+  "function cannot be inferred '%0' because it allocates/deallocates memory">;
+def warn_func_effect_throws_or_catches : Warning<
+  "'%0' function must not throw or catch exceptions">,
+  InGroup<FunctionEffects>;
+def note_func_effect_throws_or_catches : Note<
+  "function cannot be inferred '%0' because it throws or catches exceptions">;
+def warn_func_effect_has_static_local : Warning<
+  "'%0' function must not have static locals">,
+  InGroup<FunctionEffects>;
+def note_func_effect_has_static_local : Note<
+  "function cannot be inferred '%0' because it has a static local">;
+def warn_func_effect_uses_thread_local : Warning<
+  "'%0' function must not use thread-local variables">,
+  InGroup<FunctionEffects>;
+def note_func_effect_uses_thread_local : Note<
+  "function cannot be inferred '%0' because it uses a thread-local variable">;
+def warn_func_effect_calls_objc : Warning<
+  "'%0' function must not access an ObjC method or property">,
+  InGroup<FunctionEffects>;
+def note_func_effect_calls_objc : Note<
+  "function cannot be inferred '%0' because it accesses an ObjC method or property">;
+def warn_func_effect_calls_func_without_effect : Warning<
+  "'%0' function must not call non-'%0' function '%1'">,
+  InGroup<FunctionEffects>;
+def warn_func_effect_calls_expr_without_effect : Warning<
+  "'%0' function must not call non-'%0' expression">,
+  InGroup<FunctionEffects>;
+def note_func_effect_calls_func_without_effect : Note<
+  "function cannot be inferred '%0' because it calls non-'%0' function '%1'">;
+def note_func_effect_call_extern : Note<
+  "function cannot be inferred '%0' because it has no definition in this translation unit">;
+def note_func_effect_call_disallows_inference : Note<
+  "function does not permit inference of '%0'">;
+def note_func_effect_call_virtual : Note<
+  "virtual method cannot be inferred '%0'">;
+def note_func_effect_call_func_ptr : Note<
+  "function pointer cannot be inferred '%0'">;
+def warn_perf_constraint_implies_noexcept : Warning<
+  "'%0' function should be declared noexcept">,
+  InGroup<PerfConstraintImpliesNoexcept>;
+
+// FIXME: It would be nice if we could provide fuller template expansion notes.
+def note_func_effect_from_template : Note<
+  "in template expansion here">;
+
 // spoofing nonblocking/nonallocating
 def warn_invalid_add_func_effects : Warning<
   "attribute '%0' should not be added via type conversion">,

clang/include/clang/Sema/Sema.h

@@ -873,30 +873,17 @@ class Sema final : public SemaBase {
   /// Warn when implicitly casting 0 to nullptr.
   void diagnoseZeroToNullptrConversion(CastKind Kind, const Expr *E);
 
-  // ----- function effects ---
+  /// All functions/lambdas/blocks which have bodies and which have a non-empty
+  /// FunctionEffectsRef to be verified.
+  SmallVector<const Decl *> DeclsWithEffectsToVerify;
+  /// The union of all effects present on DeclsWithEffectsToVerify. Conditions
+  /// are all null.
+  FunctionEffectSet AllEffectsToVerify;
 
   /// Warn when implicitly changing function effects.
   void diagnoseFunctionEffectConversion(QualType DstType, QualType SrcType,
                                         SourceLocation Loc);
 
-  /// Warn and return true if adding an effect to a set would create a conflict.
-  bool diagnoseConflictingFunctionEffect(const FunctionEffectsRef &FX,
-                                         const FunctionEffectWithCondition &EC,
-                                         SourceLocation NewAttrLoc);
-
-  // Report a failure to merge function effects between declarations due to a
-  // conflict.
-  void
-  diagnoseFunctionEffectMergeConflicts(const FunctionEffectSet::Conflicts &Errs,
-                                       SourceLocation NewLoc,
-                                       SourceLocation OldLoc);
-
-  /// Try to parse the conditional expression attached to an effect attribute
-  /// (e.g. 'nonblocking'). (c.f. Sema::ActOnNoexceptSpec). Return an empty
-  /// optional on error.
-  std::optional<FunctionEffectMode>
-  ActOnEffectExpression(Expr *CondExpr, StringRef AttributeName);
-
   /// makeUnavailableInSystemHeader - There is an error in the current
   /// context.  If we're still in a system header, and we can plausibly
   /// make the relevant declaration unavailable instead of erroring, do
@@ -4330,6 +4317,25 @@ class Sema final : public SemaBase {
   // Whether the callee should be ignored in CUDA/HIP/OpenMP host/device check.
   bool shouldIgnoreInHostDeviceCheck(FunctionDecl *Callee);
 
+  /// Warn and return true if adding a function effect to a set would create a
+  /// conflict.
+  bool diagnoseConflictingFunctionEffect(const FunctionEffectsRef &FX,
+                                         const FunctionEffectWithCondition &EC,
+                                         SourceLocation NewAttrLoc);
+
+  // Report a failure to merge function effects between declarations due to a
+  // conflict.
+  void
+  diagnoseFunctionEffectMergeConflicts(const FunctionEffectSet::Conflicts &Errs,
+                                       SourceLocation NewLoc,
+                                       SourceLocation OldLoc);
+
+  /// Potentially add a FunctionDecl or BlockDecl to DeclsWithEffectsToVerify.
+  void maybeAddDeclWithEffects(const Decl *D, const FunctionEffectsRef &FX);
+
+  /// Unconditionally add a Decl to DeclsWithEfffectsToVerify.
+  void addDeclWithEffects(const Decl *D, const FunctionEffectsRef &FX);
+
 private:
   /// Function or variable declarations to be checked for whether the deferred
   /// diagnostics should be emitted.
@@ -15002,6 +15008,12 @@ class Sema final : public SemaBase {
     return hasAcceptableDefinition(D, &Hidden, Kind);
   }
 
+  /// Try to parse the conditional expression attached to an effect attribute
+  /// (e.g. 'nonblocking'). (c.f. Sema::ActOnNoexceptSpec). Return an empty
+  /// optional on error.
+  std::optional<FunctionEffectMode>
+  ActOnEffectExpression(Expr *CondExpr, StringRef AttributeName);
+
 private:
   /// The implementation of RequireCompleteType
   bool RequireCompleteTypeImpl(SourceLocation Loc, QualType T,

clang/include/clang/Serialization/ASTBitCodes.h

@@ -721,6 +721,10 @@ enum ASTRecordTypes {
 
   /// Record code for \#pragma clang unsafe_buffer_usage begin/end
   PP_UNSAFE_BUFFER_USAGE = 69,
+
+  /// Record code for Sema's vector of functions/blocks with effects to
+  /// be verified.
+  DECLS_WITH_EFFECTS_TO_VERIFY = 70,
 };
 
 /// Record types used within a source manager block.

clang/include/clang/Serialization/ASTReader.h

@@ -948,6 +948,9 @@ class ASTReader
   /// Sema tracks these to emit deferred diags.
   llvm::SmallSetVector<GlobalDeclID, 4> DeclsToCheckForDeferredDiags;
 
+  /// The IDs of all decls with function effects to be checked.
+  SmallVector<GlobalDeclID, 0> DeclsWithEffectsToVerify;
+
 private:
   struct ImportedSubmodule {
     serialization::SubmoduleID ID;

clang/include/clang/Serialization/ASTWriter.h

@@ -592,6 +592,7 @@ class ASTWriter : public ASTDeserializationListener,
   void WriteMSPointersToMembersPragmaOptions(Sema &SemaRef);
   void WritePackPragmaOptions(Sema &SemaRef);
   void WriteFloatControlPragmaOptions(Sema &SemaRef);
+  void WriteDeclsWithEffectsToVerify(Sema &SemaRef);
   void WriteModuleFileExtension(Sema &SemaRef,
                                 ModuleFileExtensionWriter &Writer);