//===- toyc.cpp - The Toy Compiler ----------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the entry point for the Toy compiler.
//
//===----------------------------------------------------------------------===//

#include "toy/Dialect.h"
#include "toy/MLIRGen.h"
#include "toy/Parser.h"
#include "toy/Passes.h"

#include "mlir/ExecutionEngine/ExecutionEngine.h"
#include "mlir/ExecutionEngine/OptUtils.h"
#include "mlir/IR/AsmState.h"
#include "mlir/IR/MLIRContext.h"
#include "mlir/IR/Module.h"
#include "mlir/IR/Verifier.h"
#include "mlir/InitAllDialects.h"
#include "mlir/Parser.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Pass/PassManager.h"
#include "mlir/Target/LLVMIR.h"
#include "mlir/Transforms/Passes.h"

#include "llvm/ADT/StringRef.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/raw_ostream.h"

using namespace toy;
namespace cl = llvm::cl;

static cl::opt<std::string> inputFilename(cl::Positional,
                                          cl::desc("<input toy file>"),
                                          cl::init("-"),
                                          cl::value_desc("filename"));

namespace {
enum InputType { Toy, MLIR };
}
static cl::opt<enum InputType> inputType(
    "x", cl::init(Toy), cl::desc("Decided the kind of output desired"),
    cl::values(clEnumValN(Toy, "toy", "load the input file as a Toy source.")),
    cl::values(clEnumValN(MLIR, "mlir",
                          "load the input file as an MLIR file")));

namespace {
enum Action {
  None,
  DumpAST,
  DumpMLIR,
  DumpMLIRAffine,
  DumpMLIRLLVM,
  DumpLLVMIR,
  RunJIT
};
}
static cl::opt<enum Action> emitAction(
    "emit", cl::desc("Select the kind of output desired"),
    cl::values(clEnumValN(DumpAST, "ast", "output the AST dump")),
    cl::values(clEnumValN(DumpMLIR, "mlir", "output the MLIR dump")),
    cl::values(clEnumValN(DumpMLIRAffine, "mlir-affine",
                          "output the MLIR dump after affine lowering")),
    cl::values(clEnumValN(DumpMLIRLLVM, "mlir-llvm",
                          "output the MLIR dump after llvm lowering")),
    cl::values(clEnumValN(DumpLLVMIR, "llvm", "output the LLVM IR dump")),
    cl::values(
        clEnumValN(RunJIT, "jit",
                   "JIT the code and run it by invoking the main function")));

static cl::opt<bool> enableOpt("opt", cl::desc("Enable optimizations"));

/// Returns a Toy AST resulting from parsing the file or a nullptr on error.
std::unique_ptr<toy::ModuleAST> parseInputFile(llvm::StringRef filename) {
  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> fileOrErr =
      llvm::MemoryBuffer::getFileOrSTDIN(filename);
  if (std::error_code ec = fileOrErr.getError()) {
    llvm::errs() << "Could not open input file: " << ec.message() << "\n";
    return nullptr;
  }
  auto buffer = fileOrErr.get()->getBuffer();
  LexerBuffer lexer(buffer.begin(), buffer.end(), std::string(filename));
  Parser parser(lexer);
  return parser.parseModule();
}

int loadMLIR(mlir::MLIRContext &context, mlir::OwningModuleRef &module) {
  // Handle '.toy' input to the compiler.
  if (inputType != InputType::MLIR &&
      !llvm::StringRef(inputFilename).endswith(".mlir")) {
    auto moduleAST = parseInputFile(inputFilename);
    if (!moduleAST)
      return 6;
    module = mlirGen(context, *moduleAST);
    return !module ? 1 : 0;
  }

  // Otherwise, the input is '.mlir'.
  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> fileOrErr =
      llvm::MemoryBuffer::getFileOrSTDIN(inputFilename);
  if (std::error_code EC = fileOrErr.getError()) {
    llvm::errs() << "Could not open input file: " << EC.message() << "\n";
    return -1;
  }

  // Parse the input mlir.
  llvm::SourceMgr sourceMgr;
  sourceMgr.AddNewSourceBuffer(std::move(*fileOrErr), llvm::SMLoc());
  module = mlir::parseSourceFile(sourceMgr, &context);
  if (!module) {
    llvm::errs() << "Error can't load file " << inputFilename << "\n";
    return 3;
  }
  return 0;
}

int loadAndProcessMLIR(mlir::MLIRContext &context,
                       mlir::OwningModuleRef &module) {
  if (int error = loadMLIR(context, module))
    return error;

  mlir::PassManager pm(&context);
  // Apply any generic pass manager command line options and run the pipeline.
  applyPassManagerCLOptions(pm);

  // Check to see what granularity of MLIR we are compiling to.
  bool isLoweringToAffine = emitAction >= Action::DumpMLIRAffine;
  bool isLoweringToLLVM = emitAction >= Action::DumpMLIRLLVM;

  if (enableOpt || isLoweringToAffine) {
    // Inline all functions into main and then delete them.
    pm.addPass(mlir::createInlinerPass());

    // Now that there is only one function, we can infer the shapes of each of
    // the operations.
    mlir::OpPassManager &optPM = pm.nest<mlir::FuncOp>();
    optPM.addPass(mlir::createCanonicalizerPass());
    optPM.addPass(mlir::toy::createShapeInferencePass());
    optPM.addPass(mlir::createCanonicalizerPass());
    optPM.addPass(mlir::createCSEPass());
  }

  if (isLoweringToAffine) {
    // Partially lower the toy dialect with a few cleanups afterwards.
    pm.addPass(mlir::toy::createLowerToAffinePass());

    mlir::OpPassManager &optPM = pm.nest<mlir::FuncOp>();
    optPM.addPass(mlir::createCanonicalizerPass());
    optPM.addPass(mlir::createCSEPass());

    // Add optimizations if enabled.
    if (enableOpt) {
      optPM.addPass(mlir::createLoopFusionPass());
      optPM.addPass(mlir::createMemRefDataFlowOptPass());
    }
  }

  if (isLoweringToLLVM) {
    // Finish lowering the toy IR to the LLVM dialect.
    pm.addPass(mlir::toy::createLowerToLLVMPass());
  }

  if (mlir::failed(pm.run(*module)))
    return 4;
  return 0;
}

int dumpAST() {
  if (inputType == InputType::MLIR) {
    llvm::errs() << "Can't dump a Toy AST when the input is MLIR\n";
    return 5;
  }

  auto moduleAST = parseInputFile(inputFilename);
  if (!moduleAST)
    return 1;

  dump(*moduleAST);
  return 0;
}

int dumpLLVMIR(mlir::ModuleOp module) {
  // Convert the module to LLVM IR in a new LLVM IR context.
  llvm::LLVMContext llvmContext;
  auto llvmModule = mlir::translateModuleToLLVMIR(module, llvmContext);
  if (!llvmModule) {
    llvm::errs() << "Failed to emit LLVM IR\n";
    return -1;
  }

  // Initialize LLVM targets.
  llvm::InitializeNativeTarget();
  llvm::InitializeNativeTargetAsmPrinter();
  mlir::ExecutionEngine::setupTargetTriple(llvmModule.get());

  /// Optionally run an optimization pipeline over the llvm module.
  auto optPipeline = mlir::makeOptimizingTransformer(
      /*optLevel=*/enableOpt ? 3 : 0, /*sizeLevel=*/0,
      /*targetMachine=*/nullptr);
  if (auto err = optPipeline(llvmModule.get())) {
    llvm::errs() << "Failed to optimize LLVM IR " << err << "\n";
    return -1;
  }
  llvm::errs() << *llvmModule << "\n";
  return 0;
}

int runJit(mlir::ModuleOp module) {
  // Initialize LLVM targets.
  llvm::InitializeNativeTarget();
  llvm::InitializeNativeTargetAsmPrinter();

  // An optimization pipeline to use within the execution engine.
  auto optPipeline = mlir::makeOptimizingTransformer(
      /*optLevel=*/enableOpt ? 3 : 0, /*sizeLevel=*/0,
      /*targetMachine=*/nullptr);

  // Create an MLIR execution engine. The execution engine eagerly JIT-compiles
  // the module.
  auto maybeEngine = mlir::ExecutionEngine::create(module, optPipeline);
  assert(maybeEngine && "failed to construct an execution engine");
  auto &engine = maybeEngine.get();

  // Invoke the JIT-compiled function.
  auto invocationResult = engine->invoke("main");
  if (invocationResult) {
    llvm::errs() << "JIT invocation failed\n";
    return -1;
  }

  return 0;
}

int main(int argc, char **argv) {
  mlir::registerAllDialects();

  // Register any command line options.
  mlir::registerAsmPrinterCLOptions();
  mlir::registerMLIRContextCLOptions();
  mlir::registerPassManagerCLOptions();

  cl::ParseCommandLineOptions(argc, argv, "toy compiler\n");

  if (emitAction == Action::DumpAST)
    return dumpAST();

  // If we aren't dumping the AST, then we are compiling with/to MLIR.

  mlir::MLIRContext context(/*loadAllDialects=*/false);
  // Load our Dialect in this MLIR Context.
  context.getOrLoadDialect<mlir::toy::ToyDialect>();

  mlir::OwningModuleRef module;
  if (int error = loadAndProcessMLIR(context, module))
    return error;

  // If we aren't exporting to non-mlir, then we are done.
  bool isOutputingMLIR = emitAction <= Action::DumpMLIRLLVM;
  if (isOutputingMLIR) {
    module->dump();
    return 0;
  }

  // Check to see if we are compiling to LLVM IR.
  if (emitAction == Action::DumpLLVMIR)
    return dumpLLVMIR(*module);

  // Otherwise, we must be running the jit.
  if (emitAction == Action::RunJIT)
    return runJit(*module);

  llvm::errs() << "No action specified (parsing only?), use -emit=<action>\n";
  return -1;
}