[GCOV] Skip artificial functions from being emitted

This is a patch to support  D66328, which was reverted until this lands.

Enable a compiler-rt test that used to fail previously with D66328.

Differential Revision: https://reviews.llvm.org/D67283

Author: aganea

compiler-rt/test/asan/TestCases/asan_and_llvm_coverage_test.cpp

@@ -1,9 +1,6 @@
 // RUN: %clangxx_asan -coverage -O0 %s -o %t
 // RUN: %env_asan_opts=check_initialization_order=1 %run %t 2>&1 | FileCheck %s
 
-// We don't really support running tests using profile runtime on Windows.
-// UNSUPPORTED: windows-msvc
-
 #include <stdio.h>
 int foo() { return 1; }
 int XXX = foo();

llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp

@@ -714,7 +714,10 @@ void GCOVProfiler::emitProfileNotes() {
       // to have a counter for the function definition.
       uint32_t Line = SP->getLine();
       auto Filename = getFilename(SP);
-      Func.getBlock(&EntryBlock).getFile(Filename).addLine(Line);
+
+      // Artificial functions such as global initializers
+      if (!SP->isArtificial())
+        Func.getBlock(&EntryBlock).getFile(Filename).addLine(Line);
 
       for (auto &BB : F) {
         GCOVBlock &Block = Func.getBlock(&BB);