From 89e43f04ba87a0da6e94863db149669c7536486b Mon Sep 17 00:00:00 2001
From: Vladimir Vereschaka <vvereschaka@accesssoftek.com>
Date: Tue, 21 Jan 2020 13:03:11 -0800
Subject: [PATCH] Revert "List implicit operator== after implicit destructors
 in a vtable."

This reverts commit add2b7e44ada46f30715b5c48823a9e9e317e0c3.

Failed "Clang::virtual-compare.cpp" test on the arm builders.
See
http://lab.llvm.org:8011/builders/llvm-clang-win-x-armv7l/builds/3169
for details.
---
 clang/lib/AST/VTableBuilder.cpp           | 46 ++++++++++++---------------
 clang/test/CodeGenCXX/virtual-compare.cpp | 53 -------------------------------
 2 files changed, 20 insertions(+), 79 deletions(-)
 delete mode 100644 clang/test/CodeGenCXX/virtual-compare.cpp

diff --git a/clang/lib/AST/VTableBuilder.cpp b/clang/lib/AST/VTableBuilder.cpp
index 0bff976905f..2b5b74be596 100644
--- a/clang/lib/AST/VTableBuilder.cpp
+++ b/clang/lib/AST/VTableBuilder.cpp
@@ -1474,11 +1474,11 @@ void ItaniumVTableBuilder::AddMethods(
       llvm_unreachable("Found a duplicate primary base!");
   }
 
+  const CXXDestructorDecl *ImplicitVirtualDtor = nullptr;
+
   typedef llvm::SmallVector<const CXXMethodDecl *, 8> NewVirtualFunctionsTy;
   NewVirtualFunctionsTy NewVirtualFunctions;
 
-  llvm::SmallVector<const CXXMethodDecl*, 4> NewImplicitVirtualFunctions;
-
   // Now go through all virtual member functions and add them.
   for (const auto *MD : RD->methods()) {
     if (!MD->isVirtual())
@@ -1542,30 +1542,24 @@ void ItaniumVTableBuilder::AddMethods(
       }
     }
 
-    if (MD->isImplicit())
-      NewImplicitVirtualFunctions.push_back(MD);
-    else
-      NewVirtualFunctions.push_back(MD);
-  }
-
-  std::stable_sort(
-      NewImplicitVirtualFunctions.begin(), NewImplicitVirtualFunctions.end(),
-      [](const CXXMethodDecl *A, const CXXMethodDecl *B) {
-        if (A->isCopyAssignmentOperator() != B->isCopyAssignmentOperator())
-          return A->isCopyAssignmentOperator();
-        if (A->isMoveAssignmentOperator() != B->isMoveAssignmentOperator())
-          return A->isMoveAssignmentOperator();
-        if (isa<CXXDestructorDecl>(A) != isa<CXXDestructorDecl>(B))
-          return isa<CXXDestructorDecl>(A);
-        assert(A->getOverloadedOperator() == OO_EqualEqual &&
-               B->getOverloadedOperator() == OO_EqualEqual &&
-               "unexpected or duplicate implicit virtual function");
-        // We rely on Sema to have declared the operator== members in the
-        // same order as the corresponding operator<=> members.
-        return false;
-      });
-  NewVirtualFunctions.append(NewImplicitVirtualFunctions.begin(),
-                             NewImplicitVirtualFunctions.end());
+    if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
+      if (MD->isImplicit()) {
+        // Itanium C++ ABI 2.5.2:
+        //   If a class has an implicitly-defined virtual destructor,
+        //   its entries come after the declared virtual function pointers.
+
+        assert(!ImplicitVirtualDtor &&
+               "Did already see an implicit virtual dtor!");
+        ImplicitVirtualDtor = DD;
+        continue;
+      }
+    }
+
+    NewVirtualFunctions.push_back(MD);
+  }
+
+  if (ImplicitVirtualDtor)
+    NewVirtualFunctions.push_back(ImplicitVirtualDtor);
 
   for (const CXXMethodDecl *MD : NewVirtualFunctions) {
     // Get the final overrider.
diff --git a/clang/test/CodeGenCXX/virtual-compare.cpp b/clang/test/CodeGenCXX/virtual-compare.cpp
deleted file mode 100644
index 6ffbe8eb86a..00000000000
--- a/clang/test/CodeGenCXX/virtual-compare.cpp
+++ /dev/null
@@ -1,53 +0,0 @@
-// RUN: %clang_cc1 -std=c++2a -triple %itanium_abi_triple -emit-llvm %s -o - | FileCheck %s
-
-#include "Inputs/std-compare.h"
-
-// CHECK: @_ZTV1A =
-struct A;
-struct X {
-  // CHECK-SAME: @_ZN1X1xEv
-  virtual void x();
-  friend auto operator<=>(X, X) = default;
-};
-struct Y {
-  virtual ~Y();
-  virtual A &operator=(const A &);
-  friend auto operator<=>(Y, Y) = default;
-};
-struct A : X, Y {
-  // CHECK-SAME: @_ZN1A1fEv
-  virtual void f();
-  // CHECK-SAME: @_ZNKR1AssERKS_
-  virtual std::strong_ordering operator<=>(const A &) const & = default;
-  // CHECK-SAME: @_ZN1A1gEv
-  virtual void g();
-  // CHECK-SAME: @_ZNKO1AssERKS_
-  virtual std::strong_ordering operator<=>(const A &) const && = default;
-  // CHECK-SAME: @_ZN1A1hEv
-  virtual void h();
-
-  // CHECK-SAME: @_ZN1AaSERKS_
-  // implicit virtual A &operator=(const A&) = default;
-
-  // CHECK-SAME: @_ZN1AD1Ev
-  // CHECK-SAME: @_ZN1AD0Ev
-  // implicit virtual ~A();
-
-  // CHECK-SAME: @_ZNKR1AeqERKS_
-  // implicit virtual A &operator==(const A&) const & = default;
-
-  // CHECK-SAME: @_ZNKO1AeqERKS_
-  // implicit virtual A &operator==(const A&) const && = default;
-};
-
-// For Y:
-// CHECK-SAME: @_ZTI1A
-
-// CHECK-SAME: @_ZThn8_N1AD1Ev
-// CHECK-SAME: @_ZThn8_N1AD0Ev
-// virtual ~Y();
-
-// CHECK-SAME: @_ZThn8_N1AaSERKS_
-// virtual A &operator=(const A &);
-
-void A::f() {}
-- 
2.11.0