[MS] Pass non-trivially-copyable objects indirectly on Windows ARM

This isn't exactly what MSVC does, unfortunately. MSVC does not pass
objects with destructors but no copy constructors by address. More ARM
expertise is required to really understand what should be done here.

Fixes PR29136.

llvm-svn: 279764

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 28312fce774..d6e86a8ecb2 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -794,6 +794,12 @@ MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
     // FIXME: Implement for other architectures.
     return RAA_Default;
 
+  case llvm::Triple::thumb:
+    // Use the simple Itanium rules for now.
+    // FIXME: This is incompatible with MSVC for arguments with a dtor and no
+    // copy ctor.
+    return !canCopyArgument(RD) ? RAA_Indirect : RAA_Default;
+
   case llvm::Triple::x86:
     // All record arguments are passed in memory on x86.  Decide whether to
     // construct the object directly in argument memory, or to construct the