3 files changed, 30 insertions, 66 deletions

diff --git a/lib/CodeGen/CGCXXABI.cpp b/lib/CodeGen/CGCXXABI.cpp
index e29e525edd249..033258643ddf9 100644
--- a/lib/CodeGen/CGCXXABI.cpp
+++ b/lib/CodeGen/CGCXXABI.cpp
@@ -30,38 +30,9 @@ 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.
-  // 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);
+  return RD->canPassInRegisters();
 }
 
 llvm::Constant *CGCXXABI::GetBogusMemberPointer(QualType T) {
diff --git a/lib/CodeGen/ItaniumCXXABI.cpp b/lib/CodeGen/ItaniumCXXABI.cpp
index c82b9677eacfd..e7963674fc292 100644
--- a/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/lib/CodeGen/ItaniumCXXABI.cpp
@@ -63,11 +63,8 @@ public:
   bool classifyReturnType(CGFunctionInfo &FI) const override;
 
   RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override {
-    // Structures with either a non-trivial destructor or a non-trivial
-    // copy constructor are always indirect.
-    // FIXME: Use canCopyArgument() when it is fixed to handle lazily declared
-    // special members.
-    if (RD->hasNonTrivialDestructor() || RD->hasNonTrivialCopyConstructor())
+    // If C++ prohibits us from making a copy, pass by address.
+    if (!canCopyArgument(RD))
       return RAA_Indirect;
     return RAA_Default;
   }
@@ -998,10 +995,8 @@ bool ItaniumCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
   if (!RD)
     return false;
 
-  // Return indirectly if we have a non-trivial copy ctor or non-trivial dtor.
-  // FIXME: Use canCopyArgument() when it is fixed to handle lazily declared
-  // special members.
-  if (RD->hasNonTrivialDestructor() || RD->hasNonTrivialCopyConstructor()) {
+  // If C++ prohibits us from making a copy, return by address.
+  if (!canCopyArgument(RD)) {
     auto Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
     FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
     return true;
diff --git a/lib/CodeGen/MicrosoftCXXABI.cpp b/lib/CodeGen/MicrosoftCXXABI.cpp
index 78b510bb46650..1bd2937e47477 100644
--- a/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -819,46 +819,44 @@ MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
     return RAA_Default;
 
   case llvm::Triple::x86_64:
-    // Win64 passes objects with non-trivial copy ctors indirectly.
-    if (RD->hasNonTrivialCopyConstructor())
-      return RAA_Indirect;
-
-    // If an object has a destructor, we'd really like to pass it indirectly
+    // If a class has a destructor, we'd really like to pass it indirectly
     // because it allows us to elide copies.  Unfortunately, MSVC makes that
     // impossible for small types, which it will pass in a single register or
     // stack slot. Most objects with dtors are large-ish, so handle that early.
     // We can't call out all large objects as being indirect because there are
     // multiple x64 calling conventions and the C++ ABI code shouldn't dictate
     // how we pass large POD types.
+    //
+    // Note: This permits small classes with nontrivial destructors to be
+    // passed in registers, which is non-conforming.
     if (RD->hasNonTrivialDestructor() &&
         getContext().getTypeSize(RD->getTypeForDecl()) > 64)
       return RAA_Indirect;
 
-    // If this is true, the implicit copy constructor that Sema would have
-    // created would not be deleted. FIXME: We should provide a more direct way
-    // for CodeGen to ask whether the constructor was deleted.
-    if (!RD->hasUserDeclaredCopyConstructor() &&
-        !RD->hasUserDeclaredMoveConstructor() &&
-        !RD->needsOverloadResolutionForMoveConstructor() &&
-        !RD->hasUserDeclaredMoveAssignment() &&
-        !RD->needsOverloadResolutionForMoveAssignment())
-      return RAA_Default;
-
-    // Otherwise, Sema should have created an implicit copy constructor if
-    // needed.
-    assert(!RD->needsImplicitCopyConstructor());
-
-    // We have to make sure the trivial copy constructor isn't deleted.
-    for (const CXXConstructorDecl *CD : RD->ctors()) {
-      if (CD->isCopyConstructor()) {
-        assert(CD->isTrivial());
-        // We had at least one undeleted trivial copy ctor.  Return directly.
-        if (!CD->isDeleted())
-          return RAA_Default;
+    // If a class has at least one non-deleted, trivial copy constructor, it
+    // is passed according to the C ABI. Otherwise, it is passed indirectly.
+    //
+    // Note: This permits classes with non-trivial copy or move ctors to be
+    // passed in registers, so long as they *also* have a trivial copy ctor,
+    // which is non-conforming.
+    if (RD->needsImplicitCopyConstructor()) {
+      // If the copy ctor has not yet been declared, we can read its triviality
+      // off the AST.
+      if (!RD->defaultedCopyConstructorIsDeleted() &&
+          RD->hasTrivialCopyConstructor())
+        return RAA_Default;
+    } else {
+      // Otherwise, we need to find the copy constructor(s) and ask.
+      for (const CXXConstructorDecl *CD : RD->ctors()) {
+        if (CD->isCopyConstructor()) {
+          // We had at least one nondeleted trivial copy ctor.  Return directly.
+          if (!CD->isDeleted() && CD->isTrivial())
+            return RAA_Default;
+        }
       }
     }
 
-    // The trivial copy constructor was deleted.  Return indirectly.
+    // We have no trivial, non-deleted copy constructor.
     return RAA_Indirect;
   }