// Copyright (c) 2017 The Khronos Group Inc.

// Copyright (c) 2017 Valve Corporation

// Copyright (c) 2017 LunarG Inc.

//

// Licensed 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.

#include "source/opt/inline_opaque_pass.h"

#include <iterator>

#include <utility>

namespace spvtools {

namespace opt {

namespace {

constexpr uint32_t kTypePointerTypeIdInIdx = 1;

}  // namespace

bool InlineOpaquePass::IsOpaqueType(uint32_t typeId) {

  const Instruction* typeInst = get_def_use_mgr()->GetDef(typeId);

  switch (typeInst->opcode()) {

    case spv::Op::OpTypeSampler:

    case spv::Op::OpTypeImage:

    case spv::Op::OpTypeSampledImage:

      return true;

    case spv::Op::OpTypePointer:

      return IsOpaqueType(

          typeInst->GetSingleWordInOperand(kTypePointerTypeIdInIdx));

    default:

      break;

  }

  // TODO(greg-lunarg): Handle arrays containing opaque type

  if (typeInst->opcode() != spv::Op::OpTypeStruct) return false;

  // Return true if any member is opaque

  return !typeInst->WhileEachInId([this](const uint32_t* tid) {

    if (IsOpaqueType(*tid)) return false;

    return true;

  });

}

bool InlineOpaquePass::HasOpaqueArgsOrReturn(const Instruction* callInst) {

  // Check return type

  if (IsOpaqueType(callInst->type_id())) return true;

  // Check args

  int icnt = 0;

  return !callInst->WhileEachInId([&icnt, this](const uint32_t* iid) {

    if (icnt > 0) {

      const Instruction* argInst = get_def_use_mgr()->GetDef(*iid);

      if (IsOpaqueType(argInst->type_id())) return false;

    }

    ++icnt;

    return true;

  });

}

Pass::Status InlineOpaquePass::InlineOpaque(Function* func) {

  bool modified = false;

  // Using block iterators here because of block erasures and insertions.

  for (auto bi = func->begin(); bi != func->end(); ++bi) {

    for (auto ii = bi->begin(); ii != bi->end();) {

      if (IsInlinableFunctionCall(&*ii) && HasOpaqueArgsOrReturn(&*ii)) {

        // Save instruction before the call to avoid redundant re-scanning.

        Instruction* prev_inst =

            (ii == bi->begin()) ? nullptr : &*std::prev(ii);

        // Inline call.

        std::vector<std::unique_ptr<BasicBlock>> newBlocks;

        std::vector<std::unique_ptr<Instruction>> newVars;

        if (!GenInlineCode(&newBlocks, &newVars, ii, bi)) {

          return Status::Failure;

        }

        // If call block is replaced with more than one block, point

        // succeeding phis at new last block.

        if (newBlocks.size() > 1) UpdateSucceedingPhis(newBlocks);

        // Replace old calling block with new block(s).

        bi = bi.Erase();

        for (auto& bb : newBlocks) {

          bb->SetParent(func);

        }

        bi = bi.InsertBefore(&newBlocks);

        // Insert new function variables.

        if (newVars.size() > 0)

          func->begin()->begin().InsertBefore(std::move(newVars));

        // Restart inlining at the first instruction of the inlined code.

        ii = prev_inst ? ++InstructionList::iterator(prev_inst) : bi->begin();

        modified = true;

      } else {

        ++ii;

      }

    }

  }

  if (modified) {

    FixDebugDeclares(func);

  }

  return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);

}

void InlineOpaquePass::Initialize() { InitializeInline(); }

Pass::Status InlineOpaquePass::ProcessImpl() {

  Status status = Status::SuccessWithoutChange;

  // Do opaque inlining on each function in entry point call tree

  ProcessFunction pfn = [&status, this](Function* fp) {

    status = CombineStatus(status, InlineOpaque(fp));

    return false;

  };

  context()->ProcessReachableCallTree(pfn);

  return status;

}

InlineOpaquePass::InlineOpaquePass() = default;

Pass::Status InlineOpaquePass::Process() {

  Initialize();

  return ProcessImpl();

}

}  // namespace opt

}  // namespace spvtools