Revert "PR19668, PR23034: Fix handling of move constructors and deleted copy constructors when deciding whether classes should be passed indirectly."

This reverts commit r310401 because it seems to have broken some ARM
bot(s).

llvm-svn: 310464

1 files changed, 30 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGCXXABI.cpp b/clang/lib/CodeGen/CGCXXABI.cpp
index 033258643dd..e29e525edd2 100644
--- a/clang/lib/CodeGen/CGCXXABI.cpp
+++ b/clang/lib/CodeGen/CGCXXABI.cpp
@@ -30,9 +30,38 @@ void CGCXXABI::ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S) {
 }
 
 bool CGCXXABI::canCopyArgument(const CXXRecordDecl *RD) const {
+  // If RD has a non-trivial move or copy constructor, we cannot copy the
+  // argument.
+  if (RD->hasNonTrivialCopyConstructor() || RD->hasNonTrivialMoveConstructor())
+    return false;
+
+  // If RD has a non-trivial destructor, we cannot copy the argument.
+  if (RD->hasNonTrivialDestructor())
+    return false;
+
   // We can only copy the argument if there exists at least one trivial,
   // non-deleted copy or move constructor.
-  return RD->canPassInRegisters();
+  // FIXME: This assumes that all lazily declared copy and move constructors are
+  // not deleted.  This assumption might not be true in some corner cases.
+  bool CopyDeleted = false;
+  bool MoveDeleted = false;
+  for (const CXXConstructorDecl *CD : RD->ctors()) {
+    if (CD->isCopyConstructor() || CD->isMoveConstructor()) {
+      assert(CD->isTrivial());
+      // We had at least one undeleted trivial copy or move ctor.  Return
+      // directly.
+      if (!CD->isDeleted())
+        return true;
+      if (CD->isCopyConstructor())
+        CopyDeleted = true;
+      else
+        MoveDeleted = true;
+    }
+  }
+
+  // If all trivial copy and move constructors are deleted, we cannot copy the
+  // argument.
+  return !(CopyDeleted && MoveDeleted);
 }
 
 llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) {