//===- OpenACCToLLVMIRTranslation.cpp -------------------------------------===//
//
// 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 a translation between the MLIR OpenACC dialect and LLVM
// IR.
//
//===----------------------------------------------------------------------===//

#include "mlir/Target/LLVMIR/Dialect/OpenACC/OpenACCToLLVMIRTranslation.h"
#include "mlir/Conversion/OpenACCToLLVM/ConvertOpenACCToLLVM.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/OpenACC/OpenACC.h"
#include "mlir/IR/BuiltinOps.h"
#include "mlir/IR/Operation.h"
#include "mlir/Support/LLVM.h"
#include "mlir/Target/LLVMIR/ModuleTranslation.h"

#include "llvm/ADT/TypeSwitch.h"
#include "llvm/Frontend/OpenMP/OMPConstants.h"
#include "llvm/Support/FormatVariadic.h"

using namespace mlir;

using OpenACCIRBuilder = llvm::OpenMPIRBuilder;

//===----------------------------------------------------------------------===//
// Utility functions
//===----------------------------------------------------------------------===//

/// 0 = alloc/create
static constexpr uint64_t kCreateFlag = 0;
/// 1 = to/device/copyin
static constexpr uint64_t kDeviceCopyinFlag = 1;
/// 2 = from/copyout
static constexpr uint64_t kHostCopyoutFlag = 2;
/// 8 = delete
static constexpr uint64_t kDeleteFlag = 8;

/// Default value for the device id
static constexpr int64_t kDefaultDevice = -1;

/// Create a constant string location from the MLIR Location information.
static llvm::Constant *createSourceLocStrFromLocation(Location loc,
                                                      OpenACCIRBuilder &builder,
                                                      StringRef name) {
  if (auto fileLoc = loc.dyn_cast<FileLineColLoc>()) {
    StringRef fileName = fileLoc.getFilename();
    unsigned lineNo = fileLoc.getLine();
    unsigned colNo = fileLoc.getColumn();
    return builder.getOrCreateSrcLocStr(name, fileName, lineNo, colNo);
  } else {
    std::string locStr;
    llvm::raw_string_ostream locOS(locStr);
    locOS << loc;
    return builder.getOrCreateSrcLocStr(locOS.str());
  }
}

/// Create the location struct from the operation location information.
static llvm::Value *createSourceLocationInfo(OpenACCIRBuilder &builder,
                                             Operation *op) {
  auto loc = op->getLoc();
  auto funcOp = op->getParentOfType<LLVM::LLVMFuncOp>();
  StringRef funcName = funcOp ? funcOp.getName() : "unknown";
  llvm::Constant *locStr =
      createSourceLocStrFromLocation(loc, builder, funcName);
  return builder.getOrCreateIdent(locStr);
}

/// Create a constant string representing the mapping information extracted from
/// the MLIR location information.
static llvm::Constant *createMappingInformation(Location loc,
                                                OpenACCIRBuilder &builder) {
  if (auto nameLoc = loc.dyn_cast<NameLoc>()) {
    StringRef name = nameLoc.getName();
    return createSourceLocStrFromLocation(nameLoc.getChildLoc(), builder, name);
  } else {
    return createSourceLocStrFromLocation(loc, builder, "unknown");
  }
}

/// Return the runtime function used to lower the given operation.
static llvm::Function *getAssociatedFunction(OpenACCIRBuilder &builder,
                                             Operation *op) {
  return llvm::TypeSwitch<Operation *, llvm::Function *>(op)
      .Case([&](acc::EnterDataOp) {
        return builder.getOrCreateRuntimeFunctionPtr(
            llvm::omp::OMPRTL___tgt_target_data_begin_mapper);
      })
      .Case([&](acc::ExitDataOp) {
        return builder.getOrCreateRuntimeFunctionPtr(
            llvm::omp::OMPRTL___tgt_target_data_end_mapper);
      })
      .Case([&](acc::UpdateOp) {
        return builder.getOrCreateRuntimeFunctionPtr(
            llvm::omp::OMPRTL___tgt_target_data_update_mapper);
      });
  llvm_unreachable("Unknown OpenACC operation");
}

/// Computes the size of type in bytes.
static llvm::Value *getSizeInBytes(llvm::IRBuilderBase &builder,
                                   llvm::Value *basePtr) {
  llvm::LLVMContext &ctx = builder.getContext();
  llvm::Value *null =
      llvm::Constant::getNullValue(basePtr->getType()->getPointerTo());
  llvm::Value *sizeGep =
      builder.CreateGEP(basePtr->getType(), null, builder.getInt32(1));
  llvm::Value *sizePtrToInt =
      builder.CreatePtrToInt(sizeGep, llvm::Type::getInt64Ty(ctx));
  return sizePtrToInt;
}

/// Extract pointer, size and mapping information from operands
/// to populate the future functions arguments.
static LogicalResult
processOperands(llvm::IRBuilderBase &builder,
                LLVM::ModuleTranslation &moduleTranslation, Operation *op,
                ValueRange operands, unsigned totalNbOperand,
                uint64_t operandFlag, SmallVector<uint64_t> &flags,
                SmallVector<llvm::Constant *> &names, unsigned &index,
                llvm::AllocaInst *argsBase, llvm::AllocaInst *args,
                llvm::AllocaInst *argSizes) {
  OpenACCIRBuilder *accBuilder = moduleTranslation.getOpenMPBuilder();
  llvm::LLVMContext &ctx = builder.getContext();
  auto *i8PtrTy = llvm::Type::getInt8PtrTy(ctx);
  auto *arrI8PtrTy = llvm::ArrayType::get(i8PtrTy, totalNbOperand);
  auto *i64Ty = llvm::Type::getInt64Ty(ctx);
  auto *arrI64Ty = llvm::ArrayType::get(i64Ty, totalNbOperand);

  for (Value data : operands) {
    llvm::Value *dataValue = moduleTranslation.lookupValue(data);

    llvm::Value *dataPtrBase;
    llvm::Value *dataPtr;
    llvm::Value *dataSize;

    // Handle operands that were converted to DataDescriptor.
    if (DataDescriptor::isValid(data)) {
      dataPtrBase =
          builder.CreateExtractValue(dataValue, kPtrBasePosInDataDescriptor);
      dataPtr = builder.CreateExtractValue(dataValue, kPtrPosInDataDescriptor);
      dataSize =
          builder.CreateExtractValue(dataValue, kSizePosInDataDescriptor);
    } else if (data.getType().isa<LLVM::LLVMPointerType>()) {
      dataPtrBase = dataValue;
      dataPtr = dataValue;
      dataSize = getSizeInBytes(builder, dataValue);
    } else {
      return op->emitOpError()
             << "Data operand must be legalized before translation."
             << "Unsupported type: " << data.getType();
    }

    // Store base pointer extracted from operand into the i-th position of
    // argBase.
    llvm::Value *ptrBaseGEP = builder.CreateInBoundsGEP(
        arrI8PtrTy, argsBase, {builder.getInt32(0), builder.getInt32(index)});
    llvm::Value *ptrBaseCast = builder.CreateBitCast(
        ptrBaseGEP, dataPtrBase->getType()->getPointerTo());
    builder.CreateStore(dataPtrBase, ptrBaseCast);

    // Store pointer extracted from operand into the i-th position of args.
    llvm::Value *ptrGEP = builder.CreateInBoundsGEP(
        arrI8PtrTy, args, {builder.getInt32(0), builder.getInt32(index)});
    llvm::Value *ptrCast =
        builder.CreateBitCast(ptrGEP, dataPtr->getType()->getPointerTo());
    builder.CreateStore(dataPtr, ptrCast);

    // Store size extracted from operand into the i-th position of argSizes.
    llvm::Value *sizeGEP = builder.CreateInBoundsGEP(
        arrI64Ty, argSizes, {builder.getInt32(0), builder.getInt32(index)});
    builder.CreateStore(dataSize, sizeGEP);

    flags.push_back(operandFlag);
    llvm::Constant *mapName =
        createMappingInformation(data.getLoc(), *accBuilder);
    names.push_back(mapName);
    ++index;
  }
  return success();
}

/// Process data operands from acc::EnterDataOp
static LogicalResult processDataOperands(
    llvm::IRBuilderBase &builder, LLVM::ModuleTranslation &moduleTranslation,
    acc::EnterDataOp op, SmallVector<uint64_t> &flags,
    SmallVector<llvm::Constant *> &names, llvm::AllocaInst *argsBase,
    llvm::AllocaInst *args, llvm::AllocaInst *argSizes) {
  // TODO add `create_zero` and `attach` operands

  unsigned index = 0;

  // Create operands are handled as `alloc` call.
  if (failed(processOperands(builder, moduleTranslation, op,
                             op.createOperands(), op.getNumDataOperands(),
                             kCreateFlag, flags, names, index, argsBase, args,
                             argSizes)))
    return failure();

  // Copyin operands are handled as `to` call.
  if (failed(processOperands(builder, moduleTranslation, op,
                             op.copyinOperands(), op.getNumDataOperands(),
                             kDeviceCopyinFlag, flags, names, index, argsBase,
                             args, argSizes)))
    return failure();

  return success();
}

/// Process data operands from acc::ExitDataOp
static LogicalResult processDataOperands(
    llvm::IRBuilderBase &builder, LLVM::ModuleTranslation &moduleTranslation,
    acc::ExitDataOp op, SmallVector<uint64_t> &flags,
    SmallVector<llvm::Constant *> &names, llvm::AllocaInst *argsBase,
    llvm::AllocaInst *args, llvm::AllocaInst *argSizes) {
  // TODO add `detach` operands

  unsigned index = 0;

  // Delete operands are handled as `delete` call.
  if (failed(processOperands(builder, moduleTranslation, op,
                             op.deleteOperands(), op.getNumDataOperands(),
                             kDeleteFlag, flags, names, index, argsBase, args,
                             argSizes)))
    return failure();

  // Copyout operands are handled as `from` call.
  if (failed(processOperands(builder, moduleTranslation, op,
                             op.copyoutOperands(), op.getNumDataOperands(),
                             kHostCopyoutFlag, flags, names, index, argsBase,
                             args, argSizes)))
    return failure();

  return success();
}

/// Process data operands from acc::UpdateOp
static LogicalResult processDataOperands(
    llvm::IRBuilderBase &builder, LLVM::ModuleTranslation &moduleTranslation,
    acc::UpdateOp op, SmallVector<uint64_t> &flags,
    SmallVector<llvm::Constant *> &names, llvm::AllocaInst *argsBase,
    llvm::AllocaInst *args, llvm::AllocaInst *argSizes) {
  unsigned index = 0;

  // Host operands are handled as `from` call.
  if (failed(processOperands(builder, moduleTranslation, op, op.hostOperands(),
                             op.getNumDataOperands(), kHostCopyoutFlag, flags,
                             names, index, argsBase, args, argSizes)))
    return failure();

  // Device operands are handled as `to` call.
  if (failed(processOperands(builder, moduleTranslation, op,
                             op.deviceOperands(), op.getNumDataOperands(),
                             kDeviceCopyinFlag, flags, names, index, argsBase,
                             args, argSizes)))
    return failure();

  return success();
}

//===----------------------------------------------------------------------===//
// Conversion functions
//===----------------------------------------------------------------------===//

/// Converts an OpenACC standalone data operation into LLVM IR.
template <typename OpTy>
static LogicalResult
convertStandaloneDataOp(OpTy &op, llvm::IRBuilderBase &builder,
                        LLVM::ModuleTranslation &moduleTranslation) {
  auto enclosingFuncOp =
      op.getOperation()->template getParentOfType<LLVM::LLVMFuncOp>();
  llvm::Function *enclosingFunction =
      moduleTranslation.lookupFunction(enclosingFuncOp.getName());

  OpenACCIRBuilder *accBuilder = moduleTranslation.getOpenMPBuilder();

  auto *srcLocInfo = createSourceLocationInfo(*accBuilder, op);
  auto *mapperFunc = getAssociatedFunction(*accBuilder, op);

  // Number of arguments in the enter_data operation.
  unsigned totalNbOperand = op.getNumDataOperands();

  // TODO could be moved to OpenXXIRBuilder?
  llvm::LLVMContext &ctx = builder.getContext();
  auto *i8PtrTy = llvm::Type::getInt8PtrTy(ctx);
  auto *arrI8PtrTy = llvm::ArrayType::get(i8PtrTy, totalNbOperand);
  auto *i64Ty = llvm::Type::getInt64Ty(ctx);
  auto *arrI64Ty = llvm::ArrayType::get(i64Ty, totalNbOperand);
  llvm::IRBuilder<>::InsertPoint allocaIP(
      &enclosingFunction->getEntryBlock(),
      enclosingFunction->getEntryBlock().getFirstInsertionPt());
  llvm::IRBuilder<>::InsertPoint currentIP = builder.saveIP();
  builder.restoreIP(allocaIP);
  llvm::AllocaInst *argsBase = builder.CreateAlloca(arrI8PtrTy);
  llvm::AllocaInst *args = builder.CreateAlloca(arrI8PtrTy);
  llvm::AllocaInst *argSizes = builder.CreateAlloca(arrI64Ty);
  builder.restoreIP(currentIP);

  SmallVector<uint64_t> flags;
  SmallVector<llvm::Constant *> names;

  if (failed(processDataOperands(builder, moduleTranslation, op, flags, names,
                                 argsBase, args, argSizes)))
    return failure();

  llvm::GlobalVariable *maptypes =
      accBuilder->createOffloadMaptypes(flags, ".offload_maptypes");
  llvm::Value *maptypesArg = builder.CreateConstInBoundsGEP2_32(
      llvm::ArrayType::get(llvm::Type::getInt64Ty(ctx), totalNbOperand),
      maptypes, /*Idx0=*/0, /*Idx1=*/0);

  llvm::GlobalVariable *mapnames =
      accBuilder->createOffloadMapnames(names, ".offload_mapnames");
  llvm::Value *mapnamesArg = builder.CreateConstInBoundsGEP2_32(
      llvm::ArrayType::get(llvm::Type::getInt8PtrTy(ctx), totalNbOperand),
      mapnames, /*Idx0=*/0, /*Idx1=*/0);

  llvm::Value *argsBaseGEP = builder.CreateInBoundsGEP(
      arrI8PtrTy, argsBase, {builder.getInt32(0), builder.getInt32(0)});
  llvm::Value *argsGEP = builder.CreateInBoundsGEP(
      arrI8PtrTy, args, {builder.getInt32(0), builder.getInt32(0)});
  llvm::Value *argSizesGEP = builder.CreateInBoundsGEP(
      arrI64Ty, argSizes, {builder.getInt32(0), builder.getInt32(0)});
  llvm::Value *nullPtr = llvm::Constant::getNullValue(
      llvm::Type::getInt8PtrTy(ctx)->getPointerTo());

  builder.CreateCall(mapperFunc,
                     {srcLocInfo, builder.getInt64(kDefaultDevice),
                      builder.getInt32(totalNbOperand), argsBaseGEP, argsGEP,
                      argSizesGEP, maptypesArg, mapnamesArg, nullPtr});

  return success();
}

namespace {

/// Implementation of the dialect interface that converts operations belonging
/// to the OpenACC dialect to LLVM IR.
class OpenACCDialectLLVMIRTranslationInterface
    : public LLVMTranslationDialectInterface {
public:
  using LLVMTranslationDialectInterface::LLVMTranslationDialectInterface;

  /// Translates the given operation to LLVM IR using the provided IR builder
  /// and saving the state in `moduleTranslation`.
  LogicalResult
  convertOperation(Operation *op, llvm::IRBuilderBase &builder,
                   LLVM::ModuleTranslation &moduleTranslation) const final;
};

} // end namespace

/// Given an OpenACC MLIR operation, create the corresponding LLVM IR
/// (including OpenACC runtime calls).
LogicalResult OpenACCDialectLLVMIRTranslationInterface::convertOperation(
    Operation *op, llvm::IRBuilderBase &builder,
    LLVM::ModuleTranslation &moduleTranslation) const {

  return llvm::TypeSwitch<Operation *, LogicalResult>(op)
      .Case([&](acc::EnterDataOp enterDataOp) {
        return convertStandaloneDataOp<acc::EnterDataOp>(enterDataOp, builder,
                                                         moduleTranslation);
      })
      .Case([&](acc::ExitDataOp exitDataOp) {
        return convertStandaloneDataOp<acc::ExitDataOp>(exitDataOp, builder,
                                                        moduleTranslation);
      })
      .Case([&](acc::UpdateOp updateOp) {
        return convertStandaloneDataOp<acc::UpdateOp>(updateOp, builder,
                                                      moduleTranslation);
      })
      .Default([&](Operation *op) {
        return op->emitError("unsupported OpenACC operation: ")
               << op->getName();
      });
}

void mlir::registerOpenACCDialectTranslation(DialectRegistry &registry) {
  registry.insert<acc::OpenACCDialect>();
  registry.addDialectInterface<acc::OpenACCDialect,
                               OpenACCDialectLLVMIRTranslationInterface>();
}

void mlir::registerOpenACCDialectTranslation(MLIRContext &context) {
  DialectRegistry registry;
  registerOpenACCDialectTranslation(registry);
  context.appendDialectRegistry(registry);
}