Add support for attribute 'trivial_abi'.

The 'trivial_abi' attribute can be applied to a C++ class, struct, or
union. It makes special functions of the annotated class (the destructor
and copy/move constructors) to be trivial for the purpose of calls and,
as a result, enables the annotated class or containing classes to be
passed or returned using the C ABI for the underlying type.

When a type that is considered trivial for the purpose of calls despite
having a non-trivial destructor (which happens only when the class type
or one of its subobjects is a 'trivial_abi' class) is passed to a
function, the callee is responsible for destroying the object.

For more background, see the discussions that took place on the mailing
list:

http://lists.llvm.org/pipermail/cfe-dev/2017-November/055955.html
http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20180101/thread.html#214043

rdar://problem/35204524

Differential Revision: https://reviews.llvm.org/D41039

llvm-svn: 324269

1 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index f3eab2e6d78..84da3ab6e70 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -786,6 +786,7 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
   FD->HasWrittenPrototype = Record.readInt();
   FD->IsDeleted = Record.readInt();
   FD->IsTrivial = Record.readInt();
+  FD->IsTrivialForCall = Record.readInt();
   FD->IsDefaulted = Record.readInt();
   FD->IsExplicitlyDefaulted = Record.readInt();
   FD->HasImplicitReturnZero = Record.readInt();
@@ -1577,7 +1578,9 @@ void ASTDeclReader::ReadCXXDefinitionData(
   Data.DefaultedMoveAssignmentIsDeleted = Record.readInt();
   Data.DefaultedDestructorIsDeleted = Record.readInt();
   Data.HasTrivialSpecialMembers = Record.readInt();
+  Data.HasTrivialSpecialMembersForCall = Record.readInt();
   Data.DeclaredNonTrivialSpecialMembers = Record.readInt();
+  Data.DeclaredNonTrivialSpecialMembersForCall = Record.readInt();
   Data.HasIrrelevantDestructor = Record.readInt();
   Data.HasConstexprNonCopyMoveConstructor = Record.readInt();
   Data.HasDefaultedDefaultConstructor = Record.readInt();
@@ -1715,7 +1718,9 @@ void ASTDeclReader::MergeDefinitionData(
   MATCH_FIELD(DefaultedMoveAssignmentIsDeleted)
   MATCH_FIELD(DefaultedDestructorIsDeleted)
   OR_FIELD(HasTrivialSpecialMembers)
+  OR_FIELD(HasTrivialSpecialMembersForCall)
   OR_FIELD(DeclaredNonTrivialSpecialMembers)
+  OR_FIELD(DeclaredNonTrivialSpecialMembersForCall)
   MATCH_FIELD(HasIrrelevantDestructor)
   OR_FIELD(HasConstexprNonCopyMoveConstructor)
   OR_FIELD(HasDefaultedDefaultConstructor)