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).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@310464 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 27 insertions, 25 deletions

diff --git a/lib/CodeGen/MicrosoftCXXABI.cpp b/lib/CodeGen/MicrosoftCXXABI.cpp
index 0a3cc30665..409bad72ee 100644
--- a/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -819,44 +819,46 @@ MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
     return RAA_Default;
 
   case llvm::Triple::x86_64:
-    // If a class has a destructor, we'd really like to pass it indirectly
+    // 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
     // 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 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;
-        }
+    // 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;
       }
     }
 
-    // We have no trivial, non-deleted copy constructor.
+    // The trivial copy constructor was deleted.  Return indirectly.
     return RAA_Indirect;
   }