Readd the C++ ABI alignment handling logic

lib/CodeGen/CodeGenModule.cpp

 //===--- CodeGenModule.cpp - Emit LLVM Code from ASTs for a Module --------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This coordinates the per-module state used while generating code.
@@ skipping 775 matching lines @@
 
   if (isa<CXXConstructorDecl>(D) || isa<CXXDestructorDecl>(D))
     F->setUnnamedAddr(true);
   else if (const auto *MD = dyn_cast<CXXMethodDecl>(D))
     if (MD->isVirtual())
       F->setUnnamedAddr(true);
 
   unsigned alignment = D->getMaxAlignment() / Context.getCharWidth();
   if (alignment)
     F->setAlignment(alignment);
+
+  if (getTarget().getCXXABI().arePointersToMemberFunctionsAligned()) {
+    // C++ ABI requires 2-byte alignment for member functions.
+    if (F->getAlignment() < 2 && isa<CXXMethodDecl>(D))
+      F->setAlignment(2);
+  }
 }
 
 void CodeGenModule::SetCommonAttributes(const Decl *D,
                                         llvm::GlobalValue *GV) {
   if (const auto *ND = dyn_cast<NamedDecl>(D))
     setGlobalVisibility(GV, ND);
   else
     GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
 
   if (D->hasAttr<UsedAttr>())
@@ skipping 2857 matching lines @@
     bool PerformInit =
         VD->getAnyInitializer() &&
         !VD->getAnyInitializer()->isConstantInitializer(getContext(),
                                                         /*ForRef=*/false);
     if (auto InitFunction = getOpenMPRuntime().emitThreadPrivateVarDefinition(
             VD, GetAddrOfGlobalVar(VD), RefExpr->getLocStart(), PerformInit))
       CXXGlobalInits.push_back(InitFunction);
   }
 }