/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

/*!
 * \file force_narrow_index_to_i32.cc
 * \brief Force narrow down indexing expressions and integer buffers to int32 dtype.
 * \note This pass is not used in default cases.
 */

#include <tvm/ffi/cast.h>
#include <tvm/ffi/reflection/registry.h>
#include <tvm/tirx/op.h>
#include <tvm/tirx/transform.h>

#include "../ir/data_type_rewriter.h"

namespace tvm {
namespace tirx {

class Int32DTypeNarrower : public IndexDataTypeNormalizer {
 public:
  static PrimFunc RewriteDataType(PrimFunc func) {
    // Check if the integer parameter buffers have dtype other than int32.
    for (const Var& param : func->params) {
      if (auto buffer = param.as<BufferVar>();
          buffer && buffer.value()->dtype.MatchesCode(DLDataTypeCode::kDLInt) &&
          buffer.value()->dtype.bits() > 32) {
        TVM_FFI_THROW(InternalError) << "The buffer parameter " << buffer.value() << " has dtype "
                                     << buffer.value()->dtype << ". The function is " << func;
      }
    }

    Int32DTypeNarrower narrower(func);
    return narrower.Rewrite(func);
  }

 private:
  explicit Int32DTypeNarrower(PrimFunc func)
      : IndexDataTypeNormalizer(PrimType::Int(32)), func_(std::move(func)) {}

  Expr VisitExpr_(const IntImmNode* op) final {
    // ignore the enabled condition and always rewrite i64
    if (op->ty.as_or_throw<PrimType>() == PrimType::Int(64)) {
      TVM_FFI_ICHECK_LE(op->value, max_value(target_data_type_).as_or_throw<IntImm>()->value);
      return IntImm::Int32(op->value);
    }
    return ffi::GetRef<IntImm>(op);
  }

  Stmt VisitStmt_(const SBlockNode* block) final {
    SBlock block_ = IndexDataTypeNormalizer::VisitStmt_(block).as_or_throw<SBlock>();
    // Check if the allocated integer buffers have dtype other than int32.
    for (const BufferVar& buf : block_->alloc_buffers) {
      if (buf->dtype.MatchesCode(DLDataTypeCode::kDLInt) && buf->dtype.bits() > 32) {
        TVM_FFI_THROW(InternalError)
            << "The buffer " << buf << " allocated in the function has dtype " << buf->dtype
            << ". The function is " << func_;
      }
    }
    return block_;
  }

  PrimFunc func_;
};

PrimFunc ForceNarrowIndexToInt32(PrimFunc func) {
  return Int32DTypeNarrower::RewriteDataType(func);
}

namespace transform {

Pass ForceNarrowIndexToInt32() {
  auto pass_func = [](PrimFunc f, IRModule m, PassContext ctx) {
    return ForceNarrowIndexToInt32(f);
  };
  return CreatePrimFuncPass(pass_func, 0, "tirx.NarrowDataType", {});
}

TVM_FFI_STATIC_INIT_BLOCK() {
  namespace refl = tvm::ffi::reflection;
  refl::GlobalDef().def("tirx.transform.ForceNarrowIndexToInt32", ForceNarrowIndexToInt32);
}

}  // namespace transform
}  // namespace tirx
}  // namespace tvm
