//===- llvm/unittest/Bitcode/BitReaderTest.cpp - Tests for BitReader ------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"

using namespace llvm;

namespace {

std::unique_ptr<Module> parseAssembly(LLVMContext &Context,
                                      const char *Assembly) {
  SMDiagnostic Error;
  std::unique_ptr<Module> M = parseAssemblyString(Assembly, Error, Context);

  std::string ErrMsg;
  raw_string_ostream OS(ErrMsg);
  Error.print("", OS);

  // A failure here means that the test itself is buggy.
  if (!M)
    report_fatal_error(OS.str().c_str());

  return M;
}

static void writeModuleToBuffer(std::unique_ptr<Module> Mod,
                                SmallVectorImpl<char> &Buffer) {
  raw_svector_ostream OS(Buffer);
  WriteBitcodeToFile(*Mod, OS);
}

static std::unique_ptr<Module> getLazyModuleFromAssembly(LLVMContext &Context,
                                                         SmallString<1024> &Mem,
                                                         const char *Assembly) {
  writeModuleToBuffer(parseAssembly(Context, Assembly), Mem);
  Expected<std::unique_ptr<Module>> ModuleOrErr =
      getLazyBitcodeModule(MemoryBufferRef(Mem.str(), "test"), Context);
  if (!ModuleOrErr)
    report_fatal_error("Could not parse bitcode module");
  return std::move(ModuleOrErr.get());
}

// Tests that lazy evaluation can parse functions out of order.
TEST(BitReaderTest, MaterializeFunctionsOutOfOrder) {
  SmallString<1024> Mem;
  LLVMContext Context;
  std::unique_ptr<Module> M = getLazyModuleFromAssembly(
      Context, Mem, "define void @f() {\n"
                    "  unreachable\n"
                    "}\n"
                    "define void @g() {\n"
                    "  unreachable\n"
                    "}\n"
                    "define void @h() {\n"
                    "  unreachable\n"
                    "}\n"
                    "define void @j() {\n"
                    "  unreachable\n"
                    "}\n");
  EXPECT_FALSE(verifyModule(*M, &dbgs()));

  Function *F = M->getFunction("f");
  Function *G = M->getFunction("g");
  Function *H = M->getFunction("h");
  Function *J = M->getFunction("j");

  // Initially all functions are not materialized (no basic blocks).
  EXPECT_TRUE(F->empty());
  EXPECT_TRUE(G->empty());
  EXPECT_TRUE(H->empty());
  EXPECT_TRUE(J->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));

  // Materialize h.
  ASSERT_FALSE(H->materialize());
  EXPECT_TRUE(F->empty());
  EXPECT_TRUE(G->empty());
  EXPECT_FALSE(H->empty());
  EXPECT_TRUE(J->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));

  // Materialize g.
  ASSERT_FALSE(G->materialize());
  EXPECT_TRUE(F->empty());
  EXPECT_FALSE(G->empty());
  EXPECT_FALSE(H->empty());
  EXPECT_TRUE(J->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));

  // Materialize j.
  ASSERT_FALSE(J->materialize());
  EXPECT_TRUE(F->empty());
  EXPECT_FALSE(G->empty());
  EXPECT_FALSE(H->empty());
  EXPECT_FALSE(J->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));

  // Materialize f.
  ASSERT_FALSE(F->materialize());
  EXPECT_FALSE(F->empty());
  EXPECT_FALSE(G->empty());
  EXPECT_FALSE(H->empty());
  EXPECT_FALSE(J->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));
}

TEST(BitReaderTest, MaterializeFunctionsForBlockAddr) { // PR11677
  SmallString<1024> Mem;

  LLVMContext Context;
  std::unique_ptr<Module> M = getLazyModuleFromAssembly(
      Context, Mem, "@table = constant i8* blockaddress(@func, %bb)\n"
                    "define void @func() {\n"
                    "  unreachable\n"
                    "bb:\n"
                    "  unreachable\n"
                    "}\n");
  EXPECT_FALSE(verifyModule(*M, &dbgs()));
  EXPECT_FALSE(M->getFunction("func")->empty());
}

TEST(BitReaderTest, MaterializeFunctionsForBlockAddrInFunctionBefore) {
  SmallString<1024> Mem;

  LLVMContext Context;
  std::unique_ptr<Module> M = getLazyModuleFromAssembly(
      Context, Mem, "define i8* @before() {\n"
                    "  ret i8* blockaddress(@func, %bb)\n"
                    "}\n"
                    "define void @other() {\n"
                    "  unreachable\n"
                    "}\n"
                    "define void @func() {\n"
                    "  unreachable\n"
                    "bb:\n"
                    "  unreachable\n"
                    "}\n");
  EXPECT_TRUE(M->getFunction("before")->empty());
  EXPECT_TRUE(M->getFunction("func")->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));

  // Materialize @before, pulling in @func.
  EXPECT_FALSE(M->getFunction("before")->materialize());
  EXPECT_FALSE(M->getFunction("func")->empty());
  EXPECT_TRUE(M->getFunction("other")->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));
}

TEST(BitReaderTest, MaterializeFunctionsForBlockAddrInFunctionAfter) {
  SmallString<1024> Mem;

  LLVMContext Context;
  std::unique_ptr<Module> M = getLazyModuleFromAssembly(
      Context, Mem, "define void @func() {\n"
                    "  unreachable\n"
                    "bb:\n"
                    "  unreachable\n"
                    "}\n"
                    "define void @other() {\n"
                    "  unreachable\n"
                    "}\n"
                    "define i8* @after() {\n"
                    "  ret i8* blockaddress(@func, %bb)\n"
                    "}\n");
  EXPECT_TRUE(M->getFunction("after")->empty());
  EXPECT_TRUE(M->getFunction("func")->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));

  // Materialize @after, pulling in @func.
  EXPECT_FALSE(M->getFunction("after")->materialize());
  EXPECT_FALSE(M->getFunction("func")->empty());
  EXPECT_TRUE(M->getFunction("other")->empty());
  EXPECT_FALSE(verifyModule(*M, &dbgs()));
}

} // end namespace