//===-------------- AddDebugInfo.cpp -- add debug info -------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

//===----------------------------------------------------------------------===//
/// \file
/// This pass populates some debug information for the module and functions.
//===----------------------------------------------------------------------===//

#include "flang/Common/Version.h"
#include "flang/Optimizer/Builder/FIRBuilder.h"
#include "flang/Optimizer/Builder/Todo.h"
#include "flang/Optimizer/Dialect/FIRDialect.h"
#include "flang/Optimizer/Dialect/FIROps.h"
#include "flang/Optimizer/Dialect/FIRType.h"
#include "flang/Optimizer/Dialect/Support/FIRContext.h"
#include "flang/Optimizer/Support/InternalNames.h"
#include "flang/Optimizer/Transforms/Passes.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/IR/Matchers.h"
#include "mlir/IR/TypeUtilities.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Transforms/DialectConversion.h"
#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
#include "mlir/Transforms/RegionUtils.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"

namespace fir {
#define GEN_PASS_DEF_ADDDEBUGINFO
#include "flang/Optimizer/Transforms/Passes.h.inc"
} // namespace fir

#define DEBUG_TYPE "flang-add-debug-info"

namespace {

class AddDebugInfoPass : public fir::impl::AddDebugInfoBase<AddDebugInfoPass> {
public:
  AddDebugInfoPass(fir::AddDebugInfoOptions options) : Base(options) {}
  void runOnOperation() override;
};

} // namespace

void AddDebugInfoPass::runOnOperation() {
  mlir::ModuleOp module = getOperation();
  mlir::MLIRContext *context = &getContext();
  mlir::OpBuilder builder(context);
  llvm::StringRef fileName;
  std::string filePath;
  // We need 2 type of file paths here.
  // 1. Name of the file as was presented to compiler. This can be absolute
  // or relative to 2.
  // 2. Current working directory
  //
  // We are also dealing with 2 different situations below. One is normal
  // compilation where we will have a value in 'inputFilename' and we can
  // obtain the current directory using 'current_path'.
  // The 2nd case is when this pass is invoked directly from 'fir-opt' tool.
  // In that case, 'inputFilename' may be empty. Location embedded in the
  // module will be used to get file name and its directory.
  if (inputFilename.empty()) {
    if (auto fileLoc = mlir::dyn_cast<mlir::FileLineColLoc>(module.getLoc())) {
      fileName = llvm::sys::path::filename(fileLoc.getFilename().getValue());
      filePath = llvm::sys::path::parent_path(fileLoc.getFilename().getValue());
    } else
      fileName = "-";
  } else {
    fileName = inputFilename;
    llvm::SmallString<256> cwd;
    if (!llvm::sys::fs::current_path(cwd))
      filePath = cwd.str();
  }

  mlir::LLVM::DIFileAttr fileAttr =
      mlir::LLVM::DIFileAttr::get(context, fileName, filePath);
  mlir::StringAttr producer =
      mlir::StringAttr::get(context, Fortran::common::getFlangFullVersion());
  mlir::LLVM::DICompileUnitAttr cuAttr = mlir::LLVM::DICompileUnitAttr::get(
      mlir::DistinctAttr::create(mlir::UnitAttr::get(context)),
      llvm::dwarf::getLanguage("DW_LANG_Fortran95"), fileAttr, producer,
      isOptimized, debugLevel);

  module.walk([&](mlir::func::FuncOp funcOp) {
    mlir::Location l = funcOp->getLoc();
    // If fused location has already been created then nothing to do
    // Otherwise, create a fused location.
    if (mlir::dyn_cast<mlir::FusedLoc>(l))
      return;

    unsigned int CC = (funcOp.getName() == fir::NameUniquer::doProgramEntry())
                          ? llvm::dwarf::getCallingConvention("DW_CC_program")
                          : llvm::dwarf::getCallingConvention("DW_CC_normal");

    if (auto funcLoc = mlir::dyn_cast<mlir::FileLineColLoc>(l)) {
      fileName = llvm::sys::path::filename(funcLoc.getFilename().getValue());
      filePath = llvm::sys::path::parent_path(funcLoc.getFilename().getValue());
    }

    mlir::StringAttr funcName =
        mlir::StringAttr::get(context, funcOp.getName());
    mlir::LLVM::DIBasicTypeAttr bT = mlir::LLVM::DIBasicTypeAttr::get(
        context, llvm::dwarf::DW_TAG_base_type, "void", /*sizeInBits=*/0,
        /*encoding=*/1);
    // FIXME: Provide proper type for subroutine
    mlir::LLVM::DISubroutineTypeAttr subTypeAttr =
        mlir::LLVM::DISubroutineTypeAttr::get(context, CC, {bT, bT});
    mlir::LLVM::DIFileAttr funcFileAttr =
        mlir::LLVM::DIFileAttr::get(context, fileName, filePath);

    // Only definitions need a distinct identifier and a compilation unit.
    mlir::DistinctAttr id;
    mlir::LLVM::DICompileUnitAttr compilationUnit;
    mlir::LLVM::DISubprogramFlags subprogramFlags =
        mlir::LLVM::DISubprogramFlags{};
    if (isOptimized)
      subprogramFlags = mlir::LLVM::DISubprogramFlags::Optimized;
    if (!funcOp.isExternal()) {
      id = mlir::DistinctAttr::create(mlir::UnitAttr::get(context));
      compilationUnit = cuAttr;
      subprogramFlags =
          subprogramFlags | mlir::LLVM::DISubprogramFlags::Definition;
    }
    // FIXME: Provide proper line and scopeline.
    auto spAttr = mlir::LLVM::DISubprogramAttr::get(
        context, id, compilationUnit, fileAttr, funcName, funcName,
        funcFileAttr, /*line=*/1, /*scopeline=*/1, subprogramFlags,
        subTypeAttr);
    funcOp->setLoc(builder.getFusedLoc({funcOp->getLoc()}, spAttr));
  });
}

std::unique_ptr<mlir::Pass>
fir::createAddDebugInfoPass(fir::AddDebugInfoOptions options) {
  return std::make_unique<AddDebugInfoPass>(options);
}