//===- TargetUtils.cpp - utils for obtaining generic target backend 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
//
//===----------------------------------------------------------------------===//

#include "mlir/Target/LLVMIR/Transforms/Passes.h"

#include "mlir/Dialect/DLTI/DLTI.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Target/LLVMIR/Import.h"

#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/DebugLog.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Target/TargetMachine.h"

#define DEBUG_TYPE "mlir-llvm-target-utils"

namespace mlir {
namespace LLVM {
namespace detail {
void initializeBackendsOnce() {
  static const auto initOnce = [] {
    // Ensure that the targets, that LLVM has been configured to support,
    // are loaded into the TargetRegistry.
    llvm::InitializeAllTargets();
    llvm::InitializeAllTargetMCs();
    return true;
  }();
  (void)initOnce; // Dummy usage.
}

FailureOr<std::unique_ptr<llvm::TargetMachine>>
getTargetMachine(mlir::LLVM::TargetAttrInterface attr) {
  StringRef triple = attr.getTriple();
  StringRef chipAKAcpu = attr.getChip();
  // NB: `TargetAttrInterface::getFeatures()` is coarsely typed to work around
  // cyclic dependency issue in tablegen files.
  auto featuresAttr =
      llvm::cast_if_present<LLVM::TargetFeaturesAttr>(attr.getFeatures());
  std::string features = featuresAttr ? featuresAttr.getFeaturesString() : "";

  std::string error;
  const llvm::Target *target =
      llvm::TargetRegistry::lookupTarget(triple, error);
  if (!target || !error.empty()) {
    LDBG() << "Looking up target '" << triple << "' failed: " << error << "\n";
    return failure();
  }

  return std::unique_ptr<llvm::TargetMachine>(target->createTargetMachine(
      llvm::Triple(triple), chipAKAcpu, features, {}, {}));
}

FailureOr<llvm::DataLayout>
getDataLayout(mlir::LLVM::TargetAttrInterface attr) {
  FailureOr<std::unique_ptr<llvm::TargetMachine>> targetMachine =
      getTargetMachine(attr);
  if (failed(targetMachine)) {
    LDBG() << "Failed to retrieve the target machine for data layout.\n";
    return failure();
  }
  return (targetMachine.value())->createDataLayout();
}

} // namespace detail
} // namespace LLVM
} // namespace mlir