[CodeGen] Keep track of eagerly emitted globals

An inline virtual function must be emitted, but we need to remember
it and emit the same definition again in the future in case later
LLVM optimizations stripped it from the Module. The added test case
shows the problem; before this patch, it would fail with:
    Symbols not found: [ _ZN1AD0Ev, _ZN1AD1Ev ]

This reapplies commit f8dadef, reverted in commit 0e17372, but
disables RTTI in the test to avoid problems on Windows.

Differential Revision: https://reviews.llvm.org/D156537

(cherry picked from commit c861d32)

Author: hahnjo

clang/lib/CodeGen/CodeGenModule.cpp

@@ -3645,6 +3645,7 @@ void CodeGenModule::EmitGlobal(GlobalDecl GD) {
   if (MustBeEmitted(Global) && MayBeEmittedEagerly(Global)) {
     // Emit the definition if it can't be deferred.
     EmitGlobalDefinition(GD);
+    addEmittedDeferredDecl(GD);
     return;
   }
 

clang/test/Interpreter/inline-virtual.cpp

@@ -0,0 +1,24 @@
+// REQUIRES: host-supports-jit
+// UNSUPPORTED: system-aix
+//
+// We disable RTTI to avoid problems on Windows for non-RTTI builds of LLVM
+// where the JIT cannot find ??_7type_info@@6B@.
+// RUN: cat %s | clang-repl -Xcc -fno-rtti | FileCheck %s
+// RUN: cat %s | clang-repl -Xcc -fno-rtti -Xcc -O2 | FileCheck %s
+
+extern "C" int printf(const char *, ...);
+
+struct A { int a; A(int a) : a(a) {} virtual ~A(); };
+
+// Then define the virtual destructor as inline out-of-line, in a separate
+// PartialTranslationUnit.
+inline A::~A() { printf("~A(%d)\n", a); }
+
+// Create one instance with new and delete it.
+A *a1 = new A(1);
+delete a1;
+// CHECK: ~A(1)
+
+// Also create one global that will be auto-destructed.
+A a2(2);
+// CHECK: ~A(2)