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;
  };

This patch adds two new (DI)flags to LLVM metadata: TypePassByValue
and TypePassByReference.

<rdar://problem/36034922>
Differential Revision: https://reviews.llvm.org/D41743

llvm-svn: 321844

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 1754f7d4501..ab93b855776 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -905,9 +905,12 @@ void Verifier::visitDIDerivedType(const DIDerivedType &N) {
   }
 }
 
+/// Detect mutually exclusive flags.
 static bool hasConflictingReferenceFlags(unsigned Flags) {
-  return (Flags & DINode::FlagLValueReference) &&
-         (Flags & DINode::FlagRValueReference);
+  return ((Flags & DINode::FlagLValueReference) &&
+          (Flags & DINode::FlagRValueReference)) ||
+         ((Flags & DINode::FlagTypePassByValue) &&
+          (Flags & DINode::FlagTypePassByReference));
 }
 
 void Verifier::visitTemplateParams(const MDNode &N, const Metadata &RawParams) {