/*
 * Copyright 2010-2012, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "bcc/Compiler.h"

#include <llvm/Analysis/Passes.h>
#include <llvm/CodeGen/RegAllocRegistry.h>
#include <llvm/IR/Module.h>
#include <llvm/PassManager.h>
#include <llvm/Support/TargetRegistry.h>
#include <llvm/Support/raw_ostream.h>
#include <llvm/IR/DataLayout.h>
#include <llvm/Target/TargetMachine.h>
#include <llvm/Transforms/IPO.h>
#include <llvm/Transforms/IPO/PassManagerBuilder.h>
#include <llvm/Transforms/Scalar.h>

#include "bcc/Script.h"
#include "bcc/Source.h"
#include "bcc/Support/CompilerConfig.h"
#include "bcc/Support/Log.h"
#include "bcc/Support/OutputFile.h"

#include <string>

using namespace bcc;

const char *Compiler::GetErrorString(enum ErrorCode pErrCode) {
  switch (pErrCode) {
  case kSuccess:
    return "Successfully compiled.";
  case kInvalidConfigNoTarget:
    return "Invalid compiler config supplied (getTarget() returns NULL.) "
           "(missing call to CompilerConfig::initialize()?)";
  case kErrCreateTargetMachine:
    return "Failed to create llvm::TargetMachine.";
  case kErrSwitchTargetMachine:
    return  "Failed to switch llvm::TargetMachine.";
  case kErrNoTargetMachine:
    return "Failed to compile the script since there's no available "
           "TargetMachine. (missing call to Compiler::config()?)";
  case kErrDataLayoutNoMemory:
    return "Out of memory when create DataLayout during compilation.";
  case kErrMaterialization:
    return "Failed to materialize the module.";
  case kErrInvalidOutputFileState:
    return "Supplied output file was invalid (in the error state.)";
  case kErrPrepareOutput:
    return "Failed to prepare file for output.";
  case kPrepareCodeGenPass:
    return "Failed to construct pass list for code-generation.";
  case kErrHookBeforeAddLTOPasses:
    return "Error occurred during beforeAddLTOPasses() in subclass.";
  case kErrHookAfterAddLTOPasses:
    return "Error occurred during afterAddLTOPasses() in subclass.";
  case kErrHookAfterExecuteLTOPasses:
    return "Error occurred during afterExecuteLTOPasses() in subclass.";
  case kErrHookBeforeAddCodeGenPasses:
    return "Error occurred during beforeAddCodeGenPasses() in subclass.";
  case kErrHookAfterAddCodeGenPasses:
    return "Error occurred during afterAddCodeGenPasses() in subclass.";
  case kErrHookBeforeExecuteCodeGenPasses:
    return "Error occurred during beforeExecuteCodeGenPasses() in subclass.";
  case kErrHookAfterExecuteCodeGenPasses:
    return "Error occurred during afterExecuteCodeGenPasses() in subclass.";
  case kErrInvalidSource:
    return "Error loading input bitcode";
  }

  // This assert should never be reached as the compiler verifies that the
  // above switch coveres all enum values.
  assert(false && "Unknown error code encountered");
  return  "";
}

//===----------------------------------------------------------------------===//
// Instance Methods
//===----------------------------------------------------------------------===//
Compiler::Compiler() : mTarget(NULL), mEnableLTO(true) {
  return;
}

Compiler::Compiler(const CompilerConfig &pConfig) : mTarget(NULL),
                                                    mEnableLTO(true) {
  const std::string &triple = pConfig.getTriple();

  enum ErrorCode err = config(pConfig);
  if (err != kSuccess) {
    ALOGE("%s (%s, features: %s)", GetErrorString(err),
          triple.c_str(), pConfig.getFeatureString().c_str());
    return;
  }

  return;
}

enum Compiler::ErrorCode Compiler::config(const CompilerConfig &pConfig) {
  if (pConfig.getTarget() == NULL) {
    return kInvalidConfigNoTarget;
  }

  llvm::TargetMachine *new_target =
      (pConfig.getTarget())->createTargetMachine(pConfig.getTriple(),
                                                 pConfig.getCPU(),
                                                 pConfig.getFeatureString(),
                                                 pConfig.getTargetOptions(),
                                                 pConfig.getRelocationModel(),
                                                 pConfig.getCodeModel(),
                                                 pConfig.getOptimizationLevel());

  if (new_target == NULL) {
    return ((mTarget != NULL) ? kErrSwitchTargetMachine :
                                kErrCreateTargetMachine);
  }

  // Replace the old TargetMachine.
  delete mTarget;
  mTarget = new_target;

  // Adjust register allocation policy according to the optimization level.
  //  createFastRegisterAllocator: fast but bad quality
  //  createLinearScanRegisterAllocator: not so fast but good quality
  if ((pConfig.getOptimizationLevel() == llvm::CodeGenOpt::None)) {
    llvm::RegisterRegAlloc::setDefault(llvm::createFastRegisterAllocator);
  } else {
    llvm::RegisterRegAlloc::setDefault(llvm::createGreedyRegisterAllocator);
  }

  return kSuccess;
}

Compiler::~Compiler() {
  delete mTarget;
}

enum Compiler::ErrorCode Compiler::runLTO(Script &pScript) {
  llvm::DataLayoutPass *data_layout_pass = NULL;

  // Pass manager for link-time optimization
  llvm::PassManager lto_passes;

  // Prepare DataLayout target data from Module
  data_layout_pass = new (std::nothrow) llvm::DataLayoutPass(*mTarget->getDataLayout());
  if (data_layout_pass == NULL) {
    return kErrDataLayoutNoMemory;
  }

  // Add DataLayout to the pass manager.
  lto_passes.add(data_layout_pass);

  // Invoke "beforeAddLTOPasses" before adding the first pass.
  if (!beforeAddLTOPasses(pScript, lto_passes)) {
    return kErrHookBeforeAddLTOPasses;
  }

  if (mTarget->getOptLevel() == llvm::CodeGenOpt::None) {
    lto_passes.add(llvm::createGlobalOptimizerPass());
    lto_passes.add(llvm::createConstantMergePass());
  } else {
    // FIXME: Figure out which passes should be executed.
    llvm::PassManagerBuilder Builder;
    Builder.populateLTOPassManager(lto_passes, /*Internalize*/false,
                                   /*RunInliner*/true);
  }

  // Invoke "afterAddLTOPasses" after pass manager finished its
  // construction.
  if (!afterAddLTOPasses(pScript, lto_passes)) {
    return kErrHookAfterAddLTOPasses;
  }

  lto_passes.run(pScript.getSource().getModule());

  // Invoke "afterExecuteLTOPasses" before returning.
  if (!afterExecuteLTOPasses(pScript)) {
    return kErrHookAfterExecuteLTOPasses;
  }

  return kSuccess;
}

enum Compiler::ErrorCode Compiler::runCodeGen(Script &pScript,
                                              llvm::raw_ostream &pResult) {
  llvm::DataLayoutPass *data_layout_pass;
  llvm::MCContext *mc_context = NULL;

  // Create pass manager for MC code generation.
  llvm::PassManager codegen_passes;

  // Prepare DataLayout target data from Module
  data_layout_pass = new (std::nothrow) llvm::DataLayoutPass(*mTarget->getDataLayout());
  if (data_layout_pass == NULL) {
    return kErrDataLayoutNoMemory;
  }

  // Add DataLayout to the pass manager.
  codegen_passes.add(data_layout_pass);

  // Invokde "beforeAddCodeGenPasses" before adding the first pass.
  if (!beforeAddCodeGenPasses(pScript, codegen_passes)) {
    return kErrHookBeforeAddCodeGenPasses;
  }

  // Add passes to the pass manager to emit machine code through MC layer.
  if (mTarget->addPassesToEmitMC(codegen_passes, mc_context, pResult,
                                 /* DisableVerify */false)) {
    return kPrepareCodeGenPass;
  }

  // Invokde "afterAddCodeGenPasses" after pass manager finished its
  // construction.
  if (!afterAddCodeGenPasses(pScript, codegen_passes)) {
    return kErrHookAfterAddCodeGenPasses;
  }

  // Invokde "beforeExecuteCodeGenPasses" before executing the passes.
  if (!beforeExecuteCodeGenPasses(pScript, codegen_passes)) {
    return kErrHookBeforeExecuteCodeGenPasses;
  }

  // Execute the pass.
  codegen_passes.run(pScript.getSource().getModule());

  // Invokde "afterExecuteCodeGenPasses" before returning.
  if (!afterExecuteCodeGenPasses(pScript)) {
    return kErrHookAfterExecuteCodeGenPasses;
  }

  return kSuccess;
}

enum Compiler::ErrorCode Compiler::compile(Script &pScript,
                                           llvm::raw_ostream &pResult,
                                           llvm::raw_ostream *IRStream) {
  llvm::Module &module = pScript.getSource().getModule();
  enum ErrorCode err;

  if (mTarget == NULL) {
    return kErrNoTargetMachine;
  }

  const std::string &triple = module.getTargetTriple();
  const llvm::DataLayout *dl = getTargetMachine().getDataLayout();
  unsigned int pointerSize = dl->getPointerSizeInBits();
  if (triple == "armv7-none-linux-gnueabi") {
    if (pointerSize != 32) {
      return kErrInvalidSource;
    }
  } else if (triple == "aarch64-none-linux-gnueabi") {
    if (pointerSize != 64) {
      return kErrInvalidSource;
    }
  } else {
    return kErrInvalidSource;
  }

  // Materialize the bitcode module.
  if (module.getMaterializer() != NULL) {
    // A module with non-null materializer means that it is a lazy-load module.
    // Materialize it now via invoking MaterializeAllPermanently(). This
    // function returns false when the materialization is successful.
    std::error_code ec = module.materializeAllPermanently();
    if (ec) {
      ALOGE("Failed to materialize the module `%s'! (%s)",
            module.getModuleIdentifier().c_str(), ec.message().c_str());
      return kErrMaterialization;
    }
  }

  if (mEnableLTO && ((err = runLTO(pScript)) != kSuccess)) {
    return err;
  }

  if (IRStream)
    *IRStream << module;

  if ((err = runCodeGen(pScript, pResult)) != kSuccess) {
    return err;
  }

  return kSuccess;
}

enum Compiler::ErrorCode Compiler::compile(Script &pScript,
                                           OutputFile &pResult,
                                           llvm::raw_ostream *IRStream) {
  // Check the state of the specified output file.
  if (pResult.hasError()) {
    return kErrInvalidOutputFileState;
  }

  // Open the output file decorated in llvm::raw_ostream.
  llvm::raw_ostream *out = pResult.dup();
  if (out == NULL) {
    return kErrPrepareOutput;
  }

  // Delegate the request.
  enum Compiler::ErrorCode err = compile(pScript, *out, IRStream);

  // Close the output before return.
  delete out;

  return err;
}