Debug Info: Support DW_AT_calling_convention on composite types.

This implements the DWARF 5 feature described at
http://www.dwarfstd.org/ShowIssue.php?issue=141215.1

This allows a consumer to understand whether a composite data type is
trivially copyable and thus should be passed by value instead of by
reference. The canonical example is being able to distinguish the
following two types:

  // S is not trivially copyable because of the explicit destructor.
  struct S {
     ~S() {}
  };

  // T is a POD type.
  struct T {
    ~T() = default;
  };

<rdar://problem/36034993>
Differential Revision: https://reviews.llvm.org/D41039

llvm-svn: 321845

1 files changed, 10 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index aeed4d658a4..cb15c76122c 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -2803,9 +2803,18 @@ llvm::DICompositeType *CGDebugInfo::CreateLimitedType(const RecordType *Ty) {
 
   SmallString<256> FullName = getUniqueTagTypeName(Ty, CGM, TheCU);
 
+  // Explicitly record the calling convention for C++ records.
+  auto Flags = llvm::DINode::FlagZero;
+  if (auto CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
+    if (CGM.getCXXABI().getRecordArgABI(CXXRD) == CGCXXABI::RAA_Indirect)
+      Flags |= llvm::DINode::FlagTypePassByReference;
+    else
+      Flags |= llvm::DINode::FlagTypePassByValue;
+  }
+
   llvm::DICompositeType *RealDecl = DBuilder.createReplaceableCompositeType(
       getTagForRecord(RD), RDName, RDContext, DefUnit, Line, 0, Size, Align,
-      llvm::DINode::FlagZero, FullName);
+      Flags, FullName);
 
   // Elements of composite types usually have back to the type, creating
   // uniquing cycles.  Distinct nodes are more efficient.