Register the gcov "writeout" at init time. Don't list this as a d'tor. Instead,
inject some code in that will run via the "__mod_init_func" method that
registers the gcov "writeout" function to execute at exit time.

The problem is that the "__mod_term_func" method of specifying d'tors is
deprecated on Darwin. And it can lead to some ambiguities when dealing with
multiple libraries.
<rdar://problem/11110106>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157852 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Instrumentation/GCOVProfiling.cpp b/lib/Transforms/Instrumentation/GCOVProfiling.cpp
index 4cbdb9f..6c42137 100644
--- a/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+++ b/lib/Transforms/Instrumentation/GCOVProfiling.cpp
@@ -22,6 +22,7 @@
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Instructions.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/DebugLoc.h"
@@ -57,7 +58,6 @@
     virtual const char *getPassName() const {
       return "GCOV Profiler";
     }
-
   private:
     bool runOnModule(Module &M);
 
@@ -517,6 +517,7 @@
         }
       }
     }
+
     insertCounterWriteout(CountersBySP);
   }
 
@@ -672,7 +673,26 @@
   }
   Builder.CreateRetVoid();
 
-  InsertProfilingShutdownCall(WriteoutF, M);
+  // Create a small bit of code that registers the "__llvm_gcov_writeout"
+  // function to be executed at exit.
+  FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
+  Function *F = Function::Create(FTy, GlobalValue::InternalLinkage,
+                                 "__llvm_gcov_init", M);
+  F->setUnnamedAddr(true);
+  F->setLinkage(GlobalValue::InternalLinkage);
+  F->addFnAttr(Attribute::NoInline);
+
+  BB = BasicBlock::Create(*Ctx, "entry", F);
+  Builder.SetInsertPoint(BB);
+
+  FTy = FunctionType::get(Type::getInt32Ty(*Ctx),
+                          PointerType::get(FTy, 0), false);
+  Function *AtExitFn =
+    Function::Create(FTy, GlobalValue::ExternalLinkage, "atexit", M);
+  Builder.CreateCall(AtExitFn, WriteoutF);
+  Builder.CreateRetVoid();
+
+  appendToGlobalCtors(*M, F, 0);
 }
 
 void GCOVProfiler::insertIndirectCounterIncrement() {