//===- JITEmitter.cpp - Unit tests for the JIT code emitter ---------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "gtest/gtest.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/BasicBlock.h"
#include "llvm/Constant.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/ExecutionEngine/JIT.h"
#include "llvm/ExecutionEngine/JITMemoryManager.h"
#include "llvm/Function.h"
#include "llvm/GlobalValue.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Module.h"
#include "llvm/ModuleProvider.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Target/TargetSelect.h"
#include "llvm/Type.h"

using namespace llvm;

namespace {

Function *makeReturnGlobal(std::string Name, GlobalVariable *G, Module *M) {
  std::vector<const Type*> params;
  const FunctionType *FTy = FunctionType::get(G->getType()->getElementType(),
                                              params, false);
  Function *F = Function::Create(FTy, GlobalValue::ExternalLinkage, Name, M);
  BasicBlock *Entry = BasicBlock::Create("entry", F);
  IRBuilder<> builder(Entry);
  Value *Load = builder.CreateLoad(G);
  const Type *GTy = G->getType()->getElementType();
  Value *Add = builder.CreateAdd(Load, ConstantInt::get(GTy, 1LL));
  builder.CreateStore(Add, G);
  builder.CreateRet(Add);
  return F;
}

// Regression test for a bug.  The JIT used to allocate globals inside the same
// memory block used for the function, and when the function code was freed,
// the global was left in the same place.  This test allocates a function
// that uses and global, deallocates it, and then makes sure that the global
// stays alive after that.
TEST(JIT, GlobalInFunction) {
  LLVMContext context;
  Module *M = new Module("<main>", context);
  ExistingModuleProvider *MP = new ExistingModuleProvider(M);

  JITMemoryManager *MemMgr = JITMemoryManager::CreateDefaultMemManager();
  // Tell the memory manager to poison freed memory so that accessing freed
  // memory is more easily tested.
  MemMgr->setPoisonMemory(true);
  std::string Error;
  OwningPtr<ExecutionEngine> JIT(ExecutionEngine::createJIT(
      MP,
      &Error,
      MemMgr,
      CodeGenOpt::Default,
      false));  // This last argument enables the fix.
  ASSERT_EQ(Error, "");

  // Create a global variable.
  const Type *GTy = Type::Int32Ty;
  GlobalVariable *G = new GlobalVariable(
      *M,
      GTy,
      false,  // Not constant.
      GlobalValue::InternalLinkage,
      Constant::getNullValue(GTy),
      "myglobal");

  // Make a function that points to a global.
  Function *F1 = makeReturnGlobal("F1", G, M);

  // Get the pointer to the native code to force it to JIT the function and
  // allocate space for the global.
  void (*F1Ptr)();
  // Hack to avoid ISO C++ warning about casting function pointers.
  *(void**)(void*)&F1Ptr = JIT->getPointerToFunction(F1);

  // Since F1 was codegen'd, a pointer to G should be available.
  int32_t *GPtr = (int32_t*)JIT->getPointerToGlobalIfAvailable(G);
  ASSERT_NE((int32_t*)NULL, GPtr);
  EXPECT_EQ(0, *GPtr);

  // F1() should increment G.
  F1Ptr();
  EXPECT_EQ(1, *GPtr);

  // Make a second function identical to the first, referring to the same
  // global.
  Function *F2 = makeReturnGlobal("F2", G, M);
  // Hack to avoid ISO C++ warning about casting function pointers.
  void (*F2Ptr)();
  *(void**)(void*)&F2Ptr = JIT->getPointerToFunction(F2);

  // F2() should increment G.
  F2Ptr();
  EXPECT_EQ(2, *GPtr);

  // Deallocate F1.
  JIT->freeMachineCodeForFunction(F1);

  // F2() should *still* increment G.
  F2Ptr();
  EXPECT_EQ(3, *GPtr);
}

// TODO(rnk): This seems to only run once for both tests, which is unexpected.
// That works just fine, but we shouldn't duplicate the code.
class JITEnvironment : public testing::Environment {
  virtual void SetUp() {
    // Required for ExecutionEngine::createJIT to create a JIT.
    InitializeNativeTarget();
  }
};
testing::Environment* const jit_env =
  testing::AddGlobalTestEnvironment(new JITEnvironment);

}