unittests/ExecutionEngine/JIT/JITTest.cpp

//===- JITTest.cpp - Unit tests for the JIT -------------------------------===//
//
//                     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/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/ModuleProvider.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/TypeBuilder.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(M->getContext(), "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;
}

class JITTest : public testing::Test {
 protected:
  virtual void SetUp() {
    M = new Module("<main>", Context);
    std::string Error;
    TheJIT.reset(EngineBuilder(M).setEngineKind(EngineKind::JIT)
                 .setErrorStr(&Error).create());
    ASSERT_TRUE(TheJIT.get() != NULL) << Error;
  }

  LLVMContext Context;
  Module *M;  // Owned by ExecutionEngine.
  OwningPtr<ExecutionEngine> TheJIT;
};

// 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(EngineBuilder(MP)
                                 .setEngineKind(EngineKind::JIT)
                                 .setErrorStr(&Error)
                                 .setJITMemoryManager(MemMgr)
                                 // The next line enables the fix:
                                 .setAllocateGVsWithCode(false)
                                 .create());
  ASSERT_EQ(Error, "");

  // Create a global variable.
  const Type *GTy = Type::getInt32Ty(context);
  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);
}

int PlusOne(int arg) {
  return arg + 1;
}

TEST_F(JITTest, FarCallToKnownFunction) {
  // x86-64 can only make direct calls to functions within 32 bits of
  // the current PC.  To call anything farther away, we have to load
  // the address into a register and call through the register.  The
  // current JIT does this by allocating a stub for any far call.
  // There was a bug in which the JIT tried to emit a direct call when
  // the target was already in the JIT's global mappings and lazy
  // compilation was disabled.

  Function *KnownFunction = Function::Create(
      TypeBuilder<int(int), false>::get(Context),
      GlobalValue::ExternalLinkage, "known", M);
  TheJIT->addGlobalMapping(KnownFunction, (void*)(intptr_t)PlusOne);

  // int test() { return known(7); }
  Function *TestFunction = Function::Create(
      TypeBuilder<int(), false>::get(Context),
      GlobalValue::ExternalLinkage, "test", M);
  BasicBlock *Entry = BasicBlock::Create(Context, "entry", TestFunction);
  IRBuilder<> Builder(Entry);
  Value *result = Builder.CreateCall(
      KnownFunction,
      ConstantInt::get(TypeBuilder<int, false>::get(Context), 7));
  Builder.CreateRet(result);

  TheJIT->EnableDlsymStubs(false);
  TheJIT->DisableLazyCompilation();
  int (*TestFunctionPtr)() = reinterpret_cast<int(*)()>(
      (intptr_t)TheJIT->getPointerToFunction(TestFunction));
  // This used to crash in trying to call PlusOne().
  EXPECT_EQ(8, TestFunctionPtr());
}

// This code is copied from JITEventListenerTest, but it only runs once for all
// the tests in this directory.  Everything seems fine, but that's strange
// behavior.
class JITEnvironment : public testing::Environment {
  virtual void SetUp() {
    // Required to create a JIT.
    InitializeNativeTarget();
  }
};
testing::Environment* const jit_env =
  testing::AddGlobalTestEnvironment(new JITEnvironment);

}