devin.jeanpierre updated this revision to Diff 392606.
devin.jeanpierre added a comment.

Use `PCK_ARCStrong` to check for ObjC strong pointers, marking them as 
trivially relocatable as well.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D114732/new/

https://reviews.llvm.org/D114732

Files:
  clang/docs/LanguageExtensions.rst
  clang/include/clang/AST/Type.h
  clang/include/clang/Basic/AttrDocs.td
  clang/include/clang/Basic/TokenKinds.def
  clang/lib/AST/Type.cpp
  clang/lib/Sema/SemaExprCXX.cpp
  clang/test/SemaCXX/attr-trivial-abi.cpp
  clang/test/SemaCXX/type-traits.cpp
  clang/test/SemaObjCXX/arc-type-traits.mm
  clang/test/SemaObjCXX/objc-weak-type-traits.mm

Index: clang/test/SemaObjCXX/objc-weak-type-traits.mm
===================================================================
--- clang/test/SemaObjCXX/objc-weak-type-traits.mm
+++ clang/test/SemaObjCXX/objc-weak-type-traits.mm
@@ -8,7 +8,7 @@
 #define TRAIT_IS_FALSE(Trait, Type) static_assert(!Trait(Type), "")
 #define TRAIT_IS_TRUE_2(Trait, Type1, Type2) static_assert(Trait(Type1, Type2), "")
 #define TRAIT_IS_FALSE_2(Trait, Type1, Type2) static_assert(!Trait(Type1, Type2), "")
-  
+
 struct HasStrong { id obj; };
 struct HasWeak { __weak id obj; };
 struct HasUnsafeUnretained { __unsafe_unretained id obj; };
@@ -208,3 +208,12 @@
 TRAIT_IS_FALSE_2(__is_trivially_constructible, HasWeak, HasWeak&&);
 TRAIT_IS_TRUE_2(__is_trivially_constructible, HasUnsafeUnretained, HasUnsafeUnretained);
 TRAIT_IS_TRUE_2(__is_trivially_constructible, HasUnsafeUnretained, HasUnsafeUnretained&&);
+
+// __is_trivially_relocatable
+TRAIT_IS_TRUE(__is_trivially_relocatable, __strong id);
+TRAIT_IS_FALSE(__is_trivially_relocatable, __weak id);
+TRAIT_IS_TRUE(__is_trivially_relocatable, __autoreleasing id);
+TRAIT_IS_TRUE(__is_trivially_relocatable, __unsafe_unretained id);
+TRAIT_IS_TRUE(__is_trivially_relocatable, HasStrong);
+TRAIT_IS_FALSE(__is_trivially_relocatable, HasWeak);
+TRAIT_IS_TRUE(__is_trivially_relocatable, HasUnsafeUnretained);
Index: clang/test/SemaObjCXX/arc-type-traits.mm
===================================================================
--- clang/test/SemaObjCXX/arc-type-traits.mm
+++ clang/test/SemaObjCXX/arc-type-traits.mm
@@ -12,7 +12,7 @@
 #define TRAIT_IS_FALSE(Trait, Type) char JOIN2(Trait,__LINE__)[Trait(Type)? -1 : 1]
 #define TRAIT_IS_TRUE_2(Trait, Type1, Type2) char JOIN2(Trait,__LINE__)[Trait(Type1, Type2)? 1 : -1]
 #define TRAIT_IS_FALSE_2(Trait, Type1, Type2) char JOIN2(Trait,__LINE__)[Trait(Type1, Type2)? -1 : 1]
-  
+
 struct HasStrong { id obj; };
 struct HasWeak { __weak id obj; };
 struct HasUnsafeUnretained { __unsafe_unretained id obj; };
@@ -213,3 +213,11 @@
 TRAIT_IS_TRUE_2(__is_trivially_constructible, HasUnsafeUnretained, HasUnsafeUnretained);
 TRAIT_IS_TRUE_2(__is_trivially_constructible, HasUnsafeUnretained, HasUnsafeUnretained&&);
 
+// __is_trivially_relocatable
+TRAIT_IS_TRUE(__is_trivially_relocatable, __strong id);
+TRAIT_IS_FALSE(__is_trivially_relocatable, __weak id);
+TRAIT_IS_TRUE(__is_trivially_relocatable, __autoreleasing id);
+TRAIT_IS_TRUE(__is_trivially_relocatable, __unsafe_unretained id);
+TRAIT_IS_TRUE(__is_trivially_relocatable, HasStrong);
+TRAIT_IS_FALSE(__is_trivially_relocatable, HasWeak);
+TRAIT_IS_TRUE(__is_trivially_relocatable, HasUnsafeUnretained);
Index: clang/test/SemaCXX/type-traits.cpp
===================================================================
--- clang/test/SemaCXX/type-traits.cpp
+++ clang/test/SemaCXX/type-traits.cpp
@@ -2854,3 +2854,64 @@
 #undef T16384
 #undef T32768
 } // namespace type_trait_expr_numargs_overflow
+
+namespace is_trivially_relocatable {
+
+static_assert(!__is_trivially_relocatable(void), "");
+static_assert(__is_trivially_relocatable(int), "");
+static_assert(__is_trivially_relocatable(int[]), "");
+
+enum Enum {};
+static_assert(__is_trivially_relocatable(Enum), "");
+static_assert(__is_trivially_relocatable(Enum[]), "");
+
+union Union {int x;};
+static_assert(__is_trivially_relocatable(Union), "");
+static_assert(__is_trivially_relocatable(Union[]), "");
+
+struct Trivial {};
+static_assert(__is_trivially_relocatable(Trivial), "");
+static_assert(__is_trivially_relocatable(Trivial[]), "");
+
+struct Incomplete; // expected-note {{forward declaration of 'is_trivially_relocatable::Incomplete'}}
+bool unused = __is_trivially_relocatable(Incomplete); // expected-error {{incomplete type}}
+
+struct NontrivialDtor {
+  ~NontrivialDtor() {}
+};
+static_assert(!__is_trivially_relocatable(NontrivialDtor), "");
+static_assert(!__is_trivially_relocatable(NontrivialDtor[]), "");
+
+struct NontrivialCopyCtor {
+  NontrivialCopyCtor(const NontrivialCopyCtor&) {}
+};
+static_assert(!__is_trivially_relocatable(NontrivialCopyCtor), "");
+static_assert(!__is_trivially_relocatable(NontrivialCopyCtor[]), "");
+
+struct NontrivialMoveCtor {
+  NontrivialMoveCtor(NontrivialMoveCtor&&) {}
+};
+static_assert(!__is_trivially_relocatable(NontrivialMoveCtor), "");
+static_assert(!__is_trivially_relocatable(NontrivialMoveCtor[]), "");
+
+struct [[clang::trivial_abi]] TrivialAbiNontrivialDtor {
+  ~TrivialAbiNontrivialDtor() {}
+};
+static_assert(__is_trivially_relocatable(TrivialAbiNontrivialDtor), "");
+static_assert(__is_trivially_relocatable(TrivialAbiNontrivialDtor[]), "");
+
+struct [[clang::trivial_abi]] TrivialAbiNontrivialCopyCtor {
+  TrivialAbiNontrivialCopyCtor(const TrivialAbiNontrivialCopyCtor&) {}
+};
+static_assert(__is_trivially_relocatable(TrivialAbiNontrivialCopyCtor), "");
+static_assert(__is_trivially_relocatable(TrivialAbiNontrivialCopyCtor[]), "");
+
+// A more complete set of tests for the behavior of trivial_abi can be found in
+// clang/test/SemaCXX/attr-trivial-abi.cpp
+struct [[clang::trivial_abi]] TrivialAbiNontrivialMoveCtor {
+  TrivialAbiNontrivialMoveCtor(TrivialAbiNontrivialMoveCtor&&) {}
+};
+static_assert(__is_trivially_relocatable(TrivialAbiNontrivialMoveCtor), "");
+static_assert(__is_trivially_relocatable(TrivialAbiNontrivialMoveCtor[]), "");
+
+} // namespace is_trivially_relocatable
Index: clang/test/SemaCXX/attr-trivial-abi.cpp
===================================================================
--- clang/test/SemaCXX/attr-trivial-abi.cpp
+++ clang/test/SemaCXX/attr-trivial-abi.cpp
@@ -5,27 +5,33 @@
 // Should not crash.
 template <class>
 class __attribute__((trivial_abi)) a { a(a &&); };
+static_assert(__is_trivially_relocatable(a<int>), "");
 
 struct [[clang::trivial_abi]] S0 {
   int a;
 };
+static_assert(__is_trivially_relocatable(S0), "");
 
 struct __attribute__((trivial_abi)) S1 {
   int a;
 };
+static_assert(__is_trivially_relocatable(S1), "");
 
 struct __attribute__((trivial_abi)) S3 { // expected-warning {{'trivial_abi' cannot be applied to 'S3'}} expected-note {{is polymorphic}}
   virtual void m();
 };
+static_assert(!__is_trivially_relocatable(S3), "");
 
 struct S3_2 {
   virtual void m();
 } __attribute__((trivial_abi)); // expected-warning {{'trivial_abi' cannot be applied to 'S3_2'}} expected-note {{is polymorphic}}
+static_assert(!__is_trivially_relocatable(S3_2), "");
 
 struct __attribute__((trivial_abi)) S3_3 { // expected-warning {{'trivial_abi' cannot be applied to 'S3_3'}} expected-note {{has a field of a non-trivial class type}}
   S3_3(S3_3 &&);
   S3_2 s32;
 };
+static_assert(!__is_trivially_relocatable(S3_3), "");
 
 // Diagnose invalid trivial_abi even when the type is templated because it has a non-trivial field.
 template <class T>
@@ -33,16 +39,20 @@
   S3_4(S3_4 &&);
   S3_2 s32;
 };
+static_assert(!__is_trivially_relocatable(S3_4<int>), "");
 
 struct S4 {
   int a;
 };
+static_assert(__is_trivially_relocatable(S4), "");
 
 struct __attribute__((trivial_abi)) S5 : public virtual S4 { // expected-warning {{'trivial_abi' cannot be applied to 'S5'}} expected-note {{has a virtual base}}
 };
+static_assert(!__is_trivially_relocatable(S5), "");
 
 struct __attribute__((trivial_abi)) S9 : public S4 {
 };
+static_assert(__is_trivially_relocatable(S9), "");
 
 struct __attribute__((trivial_abi(1))) S8 { // expected-error {{'trivial_abi' attribute takes no arguments}}
   int a;
@@ -55,6 +65,8 @@
 };
 
 S10<int *> p1;
+static_assert(__is_trivially_relocatable(S10<int>), "");
+static_assert(!__is_trivially_relocatable(S10<S3>), "");
 
 template <class T>
 struct S14 {
@@ -66,11 +78,15 @@
 };
 
 S15<int> s15;
+static_assert(__is_trivially_relocatable(S15<int>), "");
+static_assert(!__is_trivially_relocatable(S15<S3>), "");
 
 template <class T>
 struct __attribute__((trivial_abi)) S16 {
   S14<T> a;
 };
+static_assert(__is_trivially_relocatable(S16<int>), "");
+static_assert(!__is_trivially_relocatable(S16<S3>), "");
 
 S16<int> s16;
 
@@ -79,34 +95,42 @@
 };
 
 S17<int> s17;
+static_assert(__is_trivially_relocatable(S17<int>), "");
+static_assert(__is_trivially_relocatable(S17<S3>), "");
 
 namespace deletedCopyMoveConstructor {
 struct __attribute__((trivial_abi)) CopyMoveDeleted { // expected-warning {{'trivial_abi' cannot be applied to 'CopyMoveDeleted'}} expected-note {{copy constructors and move constructors are all deleted}}
   CopyMoveDeleted(const CopyMoveDeleted &) = delete;
   CopyMoveDeleted(CopyMoveDeleted &&) = delete;
 };
+static_assert(!__is_trivially_relocatable(CopyMoveDeleted), "");
 
 struct __attribute__((trivial_abi)) S18 { // expected-warning {{'trivial_abi' cannot be applied to 'S18'}} expected-note {{copy constructors and move constructors are all deleted}}
   CopyMoveDeleted a;
 };
+static_assert(!__is_trivially_relocatable(S18), "");
 
 struct __attribute__((trivial_abi)) CopyDeleted {
   CopyDeleted(const CopyDeleted &) = delete;
   CopyDeleted(CopyDeleted &&) = default;
 };
+static_assert(__is_trivially_relocatable(CopyDeleted), "");
 
 struct __attribute__((trivial_abi)) MoveDeleted {
   MoveDeleted(const MoveDeleted &) = default;
   MoveDeleted(MoveDeleted &&) = delete;
 };
+static_assert(__is_trivially_relocatable(MoveDeleted), "");
 
 struct __attribute__((trivial_abi)) S19 { // expected-warning {{'trivial_abi' cannot be applied to 'S19'}} expected-note {{copy constructors and move constructors are all deleted}}
   CopyDeleted a;
   MoveDeleted b;
 };
+static_assert(!__is_trivially_relocatable(S19), "");
 
 // This is fine since the move constructor isn't deleted.
 struct __attribute__((trivial_abi)) S20 {
   int &&a; // a member of rvalue reference type deletes the copy constructor.
 };
+static_assert(__is_trivially_relocatable(S20), "");
 } // namespace deletedCopyMoveConstructor
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -11,8 +11,6 @@
 ///
 //===----------------------------------------------------------------------===//
 
-#include "clang/Sema/Template.h"
-#include "clang/Sema/SemaInternal.h"
 #include "TreeTransform.h"
 #include "TypeLocBuilder.h"
 #include "clang/AST/ASTContext.h"
@@ -27,6 +25,7 @@
 #include "clang/Basic/AlignedAllocation.h"
 #include "clang/Basic/PartialDiagnostic.h"
 #include "clang/Basic/TargetInfo.h"
+#include "clang/Basic/TypeTraits.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/Initialization.h"
@@ -34,7 +33,9 @@
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
+#include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/SemaLambda.h"
+#include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateDeduction.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/STLExtras.h"
@@ -4745,6 +4746,8 @@
   case UTT_IsStandardLayout:
   case UTT_IsPOD:
   case UTT_IsLiteral:
+  // By analogy, is_trivially_relocatable imposes the same constraints.
+  case UTT_IsTriviallyRelocatable:
   // Per the GCC type traits documentation, T shall be a complete type, cv void,
   // or an array of unknown bound. But GCC actually imposes the same constraints
   // as above.
@@ -5209,6 +5212,8 @@
     return !T->isIncompleteType();
   case UTT_HasUniqueObjectRepresentations:
     return C.hasUniqueObjectRepresentations(T);
+  case UTT_IsTriviallyRelocatable:
+    return T.isTriviallyRelocatableType(C);
   }
 }
 
Index: clang/lib/AST/Type.cpp
===================================================================
--- clang/lib/AST/Type.cpp
+++ clang/lib/AST/Type.cpp
@@ -2488,6 +2488,25 @@
   return false;
 }
 
+bool QualType::isTriviallyRelocatableType(const ASTContext &Context) const {
+  QualType BaseElementType = Context.getBaseElementType(*this);
+
+  if (BaseElementType->isIncompleteType()) {
+    return false;
+  } else if (const auto *RD = BaseElementType->getAsRecordDecl()) {
+    return RD->canPassInRegisters();
+  } else {
+    switch (isNonTrivialToPrimitiveDestructiveMove()) {
+    case PCK_Trivial:
+      return !isDestructedType();
+    case PCK_ARCStrong:
+      return true;
+    default:
+      return false;
+    }
+  }
+}
+
 bool QualType::isNonWeakInMRRWithObjCWeak(const ASTContext &Context) const {
   return !Context.getLangOpts().ObjCAutoRefCount &&
          Context.getLangOpts().ObjCWeak &&
Index: clang/include/clang/Basic/TokenKinds.def
===================================================================
--- clang/include/clang/Basic/TokenKinds.def
+++ clang/include/clang/Basic/TokenKinds.def
@@ -509,6 +509,7 @@
 KEYWORD(__underlying_type           , KEYCXX)
 
 // Clang-only C++ Type Traits
+TYPE_TRAIT_1(__is_trivially_relocatable, IsTriviallyRelocatable, KEYCXX)
 TYPE_TRAIT_2(__reference_binds_to_temporary, ReferenceBindsToTemporary, KEYCXX)
 
 // Embarcadero Expression Traits
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -3226,6 +3226,9 @@
 and is passed as an argument by value, the convention is that the callee will
 destroy the object before returning.
 
+If a type is trivial for the purpose of calls, it is assumed to be trivially
+relocatable for the purpose of ``__is_trivially_relocatable``.
+
 Attribute ``trivial_abi`` has no effect in the following cases:
 
 - The class directly declares a virtual base or virtual methods.
Index: clang/include/clang/AST/Type.h
===================================================================
--- clang/include/clang/AST/Type.h
+++ clang/include/clang/AST/Type.h
@@ -828,6 +828,8 @@
   /// Return true if this is a trivially copyable type (C++0x [basic.types]p9)
   bool isTriviallyCopyableType(const ASTContext &Context) const;
 
+  /// Return true if this is a trivially relocatable type.
+  bool isTriviallyRelocatableType(const ASTContext &Context) const;
 
   /// Returns true if it is a class and it might be dynamic.
   bool mayBeDynamicClass() const;
Index: clang/docs/LanguageExtensions.rst
===================================================================
--- clang/docs/LanguageExtensions.rst
+++ clang/docs/LanguageExtensions.rst
@@ -1365,6 +1365,11 @@
 * ``__is_trivially_constructible`` (C++, GNU, Microsoft)
 * ``__is_trivially_copyable`` (C++, GNU, Microsoft)
 * ``__is_trivially_destructible`` (C++, MSVC 2013)
+* ``__is_trivially_relocatable`` (Clang): Returns true if moving an object
+  of the given type, and then destroying the source object, is known to be
+  functionally equivalent to copying the underlying bytes and then dropping the
+  source object on the floor. This is true of trivial types and types which
+  were made trivially relocatable via the ``clang::trivial_abi`` attribute.
 * ``__is_union`` (C++, GNU, Microsoft, Embarcadero)
 * ``__is_unsigned`` (C++, Embarcadero):
   Returns false for enumeration types. Note, before Clang 13, returned true for
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