Add a function for profiling to run at shutdown. Unlike the existing API, this

can be used even when main() isn't present in the Module, but it means that you
don't get to read argv[].

llvm-svn: 129163

llvm/lib/Transforms/Instrumentation/ProfilingUtils.cpp

@@ -121,8 +121,7 @@ void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
   Indices[0] = Constant::getNullValue(Type::getInt32Ty(Context));
   Indices[1] = ConstantInt::get(Type::getInt32Ty(Context), CounterNum);
   Constant *ElementPtr =
-    ConstantExpr::getGetElementPtr(CounterArray, &Indices[0],
-                                          Indices.size());
+    ConstantExpr::getGetElementPtr(CounterArray, &Indices[0], Indices.size());
 
   // Load, increment and store the value back.
   Value *OldVal = new LoadInst(ElementPtr, "OldFuncCounter", InsertPos);
@@ -131,3 +130,39 @@ void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
                                          "NewFuncCounter", InsertPos);
   new StoreInst(NewVal, ElementPtr, InsertPos);
 }
+
+void llvm::InsertProfilingShutdownCall(Function *Callee, Module *Mod) {
+  // llvm.global_dtors is an array of type { i32, void ()* }. Prepare those
+  // types.
+  const Type *GlobalDtorElems[2] = {
+    Type::getInt32Ty(Mod->getContext()),
+    FunctionType::get(Type::getVoidTy(Mod->getContext()), false)->getPointerTo()
+  };
+  const StructType *GlobalDtorElemTy =
+      StructType::get(Mod->getContext(), GlobalDtorElems, false);
+
+  // Construct the new element we'll be adding.
+  Constant *Elem[2] = {
+    ConstantInt::get(Type::getInt32Ty(Mod->getContext()), 65535),
+    ConstantExpr::getBitCast(Callee, GlobalDtorElems[1])
+  };
+
+  // If llvm.global_dtors exists, make a copy of the things in its list and
+  // delete it, to replace it with one that has a larger array type.
+  std::vector<Constant *> dtors;
+  if (GlobalVariable *GlobalDtors = Mod->getNamedGlobal("llvm.global_dtors")) {
+    ConstantArray *InitList =
+        cast<ConstantArray>(GlobalDtors->getInitializer());
+    for (unsigned i = 0, e = InitList->getType()->getNumElements(); i != e; ++i)
+      dtors.push_back(cast<Constant>(InitList->getOperand(i)));
+    GlobalDtors->eraseFromParent();
+  }
+
+  // Build up llvm.global_dtors with our new item in it.
+  GlobalVariable *GlobalDtors = new GlobalVariable(
+      *Mod, ArrayType::get(GlobalDtorElemTy, 1), false,
+      GlobalValue::AppendingLinkage, NULL, "llvm.global_dtors");
+  dtors.push_back(ConstantStruct::get(Mod->getContext(), Elem, 2, false));
+  GlobalDtors->setInitializer(ConstantArray::get(
+      cast<ArrayType>(GlobalDtors->getType()->getElementType()), dtors));
+}

llvm/lib/Transforms/Instrumentation/ProfilingUtils.h

@@ -18,9 +18,10 @@
 #define PROFILINGUTILS_H
 
 namespace llvm {
+  class BasicBlock;
   class Function;
   class GlobalValue;
-  class BasicBlock;
+  class Module;
   class PointerType;
 
   void InsertProfilingInitCall(Function *MainFn, const char *FnName,
@@ -29,6 +30,7 @@ namespace llvm {
   void IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
                                GlobalValue *CounterArray,
                                bool beginning = true);
+  void InsertProfilingShutdownCall(Function *Callee, Module *Mod);
 }
 
 #endif