//===-- Driver.cpp --------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Gollvm driver helper class Driver methods.
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Program.h"

#include "Action.h"
#include "Compilation.h"
#include "Driver.h"
#include "LinuxToolChain.h"
#include "ToolChain.h"

using namespace llvm;

namespace gollvm {
namespace driver {

Driver::Driver(opt::InputArgList &args,
               opt::OptTable *optTable,
               const char *argv0)
    : args_(args),
      opts_(optTable),
      progname_(argv0)
{
  if (const opt::Arg *arg = args.getLastArg(gollvm::options::OPT_sysroot_EQ))
    sysroot_ = arg->getValue();
}

Driver::~Driver()
{
}

// TODO: create a mechanism for capturing release tag/branch, and/or
// git/svn revision for LLVM, gollvm, and so on.

void Driver::emitVersion()
{
  // NB: the go build tool keys off the presence of the "experimental"
  // keyword (hashes compiler binary if detected).
  llvm::errs() << "gollvm version 1 (experimental)\n";
}

std::string Driver::getFilePath(llvm::StringRef name,
                                ToolChain &toolchain)
{
  // to be implemented in a later patch
  assert(false);
  return "";
}

std::string Driver::getProgramPath(llvm::StringRef name,
                                   ToolChain &toolchain)
{
  // TODO: add support for -Bprefix option.

  // Include target-prefixed name in search.
  SmallVector<std::string, 2> candidates;
  candidates.push_back((triple_.str() + "-" + name).str());
  candidates.push_back(name);

  // Examine toolchain program paths.
  for (auto &dir : toolchain.programPaths()) {
    for (auto &cand : candidates) {
      llvm::SmallString<256> candidate(dir);
      llvm::sys::path::append(candidate, cand);
      if (llvm::sys::fs::can_execute(llvm::Twine(candidate)))
        return candidate.str();
    }
  }

  // Search path.
  for (auto &cand : candidates) {
    llvm::ErrorOr<std::string> pcand =
      llvm::sys::findProgramByName(cand);
    if (pcand)
      return *pcand;
  }

  return name;
}

// FIXME: some  platforms have PIE enabled by default; we don't
// yet support auto-detection of such platforms.

bool Driver::isPIE()
{
  // Treat these options as trumping -pie.
  // FIXME: also handle -r here when supported
  if (args_.hasArg(gollvm::options::OPT_shared) ||
      args_.hasArg(gollvm::options::OPT_static))
    return false;

  opt::Arg *arg = args_.getLastArg(gollvm::options::OPT_pie,
                                   gollvm::options::OPT_no_pie,
                                   gollvm::options::OPT_nopie);
  return (arg ? arg->getOption().matches(options::OPT_pie) : false);
}

// Return any settings from the -fPIC/-fpic options, if present. The
// intent of the code below is to support "rightmost on the command
// line wins" (compatible with clang and other compilers), so if you
// specify "-fPIC -fpic" you get small PIC, whereas "-fPIC -fpic
// -fPIC" this will give you large PIC.
PICLevel::Level Driver::getPicLevel()
{
  opt::Arg *arg = args_.getLastArg(gollvm::options::OPT_fpic,
                                   gollvm::options::OPT_fno_pic,
                                   gollvm::options::OPT_fPIC,
                                   gollvm::options::OPT_fno_PIC);
  if (arg == nullptr)
    return PICLevel::NotPIC;
  if (arg->getOption().matches(gollvm::options::OPT_fpic))
    return PICLevel::SmallPIC;
  else if (arg->getOption().matches(gollvm::options::OPT_fPIC))
    return PICLevel::BigPIC;
  return PICLevel::NotPIC;
}

// Given a pair of llvm::opt options (presumably corresponding to
// -fXXX and -fno-XXX boolean flags), select the correct value for the
// option depending on the relative position of the options on the
// command line (rightmost wins). For example, given -fblah -fno-blah
// -fblah, we want the same semantics as a single -fblah.

bool
Driver::reconcileOptionPair(gollvm::options::ID yesOption,
                            gollvm::options::ID noOption,
                            bool defaultVal)
{
  opt::Arg *arg = args_.getLastArg(yesOption, noOption);
  if (arg == nullptr)
    return defaultVal;
  if (arg->getOption().matches(yesOption))
    return true;
  assert(arg->getOption().matches(noOption));
  return false;
}

Optional<Reloc::Model>
Driver::reconcileRelocModel()
{
  auto picLevel = getPicLevel();
  if (picLevel != PICLevel::NotPIC) {
    Reloc::Model R = Reloc::PIC_;
    return R;
  }
  return None;
}

Optional<FPOpFusion::FPOpFusionMode>
Driver::getFPOpFusionMode()
{
  opt::Arg *arg = args_.getLastArg(gollvm::options::OPT_ffp_contract_EQ);
  FPOpFusion::FPOpFusionMode res = FPOpFusion::Standard;
  if (arg != nullptr) {
    std::string val(arg->getValue());
    if (val == "off")
      res = FPOpFusion::Strict;
    else if (val == "on")
      res = FPOpFusion::Standard;
    else if (val == "fast")
      res = FPOpFusion::Fast;
    else {
      errs() << progname_ << ": invalid argument '"
             << arg->getValue() << "' to '"
             << arg->getAsString(args_) << "' option\n";
      return None;
    }
  }
  return res;
}

std::unique_ptr<Compilation> Driver::buildCompilation(ToolChain &tc)
{
  return std::unique_ptr<Compilation>(new Compilation(*this, tc));
}

ToolChain *Driver::setup()
{
   bool inputseen = false;

  if (args_.hasArg(gollvm::options::OPT_v) ||
      args_.hasArg(gollvm::options::OPT__HASH_HASH_HASH))
    emitVersion();

  // Check for existence of input files.
  for (opt::Arg *arg : args_) {
    if (arg->getOption().getKind() == opt::Option::InputClass) {

      // Special case for "-" (always assumed to exist)
      if (strcmp(arg->getValue(), "-")) {
        std::string fn(arg->getValue());

        // Check for existence of input file.
        if (!sys::fs::exists(fn)) {
          errs() << progname_ << ": error: input file '"
                 << fn << "' does not exist\n";
          return nullptr;
        }
      }
      inputseen = true;
    }
  }

  // Issue an error if no inputs.
  if (! inputseen) {
    errs() << progname_ << ": error: no inputs\n";
    return nullptr;
  }

  // Set triple.
  if (const opt::Arg *arg = args_.getLastArg(gollvm::options::OPT_target_EQ))
    triple_ = Triple(Triple::normalize(arg->getValue()));
  else
    triple_ = Triple(sys::getDefaultTargetTriple());

  // Support -march
  std::string archStr;
  opt::Arg *archarg = args_.getLastArg(gollvm::options::OPT_march_EQ);
  if (archarg != nullptr) {
    std::string val(archarg->getValue());
    if (val == "native")
      archStr = sys::getHostCPUName();
    else
      archStr = archarg->getValue();
    triple_.setArchName(archStr);
  }

  // Look up toolchain.
  auto &tc = toolchains_[triple_.str()];
  if (!tc) {
    switch (triple_.getOS()) {
      case Triple::Linux:
        tc = make_unique<toolchains::Linux>(*this, triple_);
        break;
      default:
        errs() << progname_ << ": error: unsupported target "
               << triple_.str() << ", unable to create toolchain\n";
        return nullptr;
    }
  }

  // FIXME: add code to weed out unknown architectures (ex:
  // SomethingWeird-unknown-linux-gnu).

  return tc.get();
}

ActionList Driver::createInputActions(const inarglist &ifargs,
                                      Compilation &compilation)
{
  ActionList result;
  for (auto ifarg : ifargs) {
    InputAction *ia = new InputAction(compilation.newArgArtifact(ifarg));
    compilation.recordAction(ia);
    result.push_back(ia);
  }
  return result;
}

bool Driver::buildActions(Compilation &compilation)
{
  inarglist gofiles;
  inarglist asmfiles;
  inarglist linkerinputs;

  // Examine inputs to see what sort of actions we need.
  for (opt::Arg *arg : args_) {
    if (arg->getOption().getKind() == opt::Option::InputClass) {
      std::string fn(arg->getValue());

      // At the moment the canonical "-" input (stdin) is assumed
      // to be Go source.
      if (!strcmp(arg->getValue(), "-")) {
        gofiles.push_back(arg);
        continue;
      }

      size_t dotindex = fn.find_last_of(".");
      if (dotindex != std::string::npos) {
        std::string extension = fn.substr(dotindex);
        if (extension.compare(".s") == 0) {
          asmfiles.push_back(arg);
          continue;
        } else if (extension.compare(".go") == 0) {
          gofiles.push_back(arg);
          continue;
        } else if (extension.compare(".S") == 0) {
          errs() << progname_ << ": warning: " << arg->getValue()
                 << ": .S files (preprocessed assembler) not supported; "
                 << "treating as linker input.\n";
        }
      }

      // everything else assumed to be a linker input
      linkerinputs.push_back(arg);
      continue;
    }
  }

  bool OPT_c = args_.hasArg(gollvm::options::OPT_c);
  bool OPT_S = args_.hasArg(gollvm::options::OPT_S);
  ActionList linkerInputs;

  // For -c/-S compiles, a mix of Go and assembly currently not allowed.
  if ((OPT_c || OPT_S) && !gofiles.empty() && !asmfiles.empty()) {
    errs() << progname_ << ": error: cannot specify mix of "
           << "Go and assembly inputs with -c/-S\n";
    return false;
  }

  // Handle Go compilation action if needed.
  if (!gofiles.empty()) {

    // Build a list of input actions for the go files.
    ActionList inacts = createInputActions(gofiles, compilation);

    // Create action
    Action *gocompact =
        new Action(Action::A_Compile, inacts);
    compilation.recordAction(gocompact);
    compilation.addAction(gocompact);

    // Schedule assemble action now if no -S.
    if (!OPT_S) {
      // Create action
      Action *asmact =
          new Action(Action::A_Assemble, gocompact);
      compilation.recordAction(asmact);
      compilation.addAction(asmact);
      if (!OPT_c)
        linkerInputs.push_back(asmact);
    }
  }

  // Create actions to assemble any asm files appearing on the cmd line.
  if (gofiles.empty() && !asmfiles.empty()) {

    // Issue an error if -c in combination with multiple files.
    if (OPT_c && asmfiles.size() > 1) {
      errs() << progname_ << ": error: cannot specify multiple inputs "
             << "in combination with -c\n";
      return false;
    }

    for (auto asmf : asmfiles) {

      // Input action.
      InputAction *ia = new InputAction(compilation.newArgArtifact(asmf));
      compilation.recordAction(ia);

      // Assemble action.
      Action *asmact =
          new Action(Action::A_Assemble, ia);
      compilation.recordAction(asmact);
      compilation.addAction(asmact);
      if (!OPT_c)
        linkerInputs.push_back(asmact);
    }
  }

  // If -S or -c, we are done at this point.
  if (OPT_c || OPT_S)
    return true;

  // Create a linker action.
  Action *linkact =
          new Action(Action::A_Link, linkerInputs);
  compilation.recordAction(linkact);
  compilation.addAction(linkact);

  return true;
}

ArtifactList Driver::collectInputArtifacts(Action *act, InternalTool *it)
{
  ArtifactList result;
  for (auto &input : act->inputs()) {
    InputAction *inact = input->castToInputAction();
    if (inact != nullptr) {
      result.push_back(inact->input());
      continue;
    }
    // It is an error if an internal-tool action is receiving a result
    // from an external tool (in the current model all internal-tool actions
    // have to take place before any external-tool actions).
    assert(it == nullptr);
    auto it = artmap_.find(input);
    assert(it != artmap_.end());
    result.push_back(it->second);
  }
  return result;
}

bool Driver::processAction(Action *act, Compilation &compilation, bool lastAct)
{
  // Select the result file for this action.
  Artifact *result = nullptr;
  if (!lastAct) {
    auto tfa = compilation.createTemporaryFileArtifact(act);
    if (!tfa)
      return false;
    result = *tfa;
    artmap_[act] = result;
  } else {
    result = compilation.createOutputFileArtifact(act);
  }

  // Select tool to process the action.
  Tool *tool = compilation.toolchain().getTool(act);
  assert(tool != nullptr);
  InternalTool *it = tool->castToInternalTool();

  // Collect input artifacts for this
  ArtifactList actionInputs = collectInputArtifacts(act, it);

  // If internal tool, perform now.
  if (it != nullptr) {
    if (! it->performAction(compilation, *act, actionInputs, *result))
      return false;
    return true;
  }

  // External tool: build command
  ExternalTool *et = tool->castToExternalTool();
  if (! et->constructCommand(compilation, *act, actionInputs, *result))
    return false;

  return true;
}

bool Driver::processActions(Compilation &compilation)
{
  SmallVector<Action*, 8> actv;
  for (Action *action : compilation.actions())
    actv.push_back(action);

  for (unsigned ai = 0; ai < actv.size(); ++ai) {
    Action *act = actv[ai];
    bool lastAction = (ai == actv.size()-1);
    if (!processAction(act, compilation, lastAction))
      return false;
  }

  return true;
}

} // end namespace driver
} // end namespace gollvm