// SPDX-License-Identifier: GPL-3.0-or-later

#include "TableGenBackends.h"

#include <cstddef>
#include <cstdint>
#include <ostream>
#include <sstream>
#include <string>
#include <string_view>

namespace rcc::targetgen {
namespace {

[[nodiscard]] std::string_view typeKindName(NormalizedSelectionTypeKind Kind) noexcept {
  switch (Kind) {
  case NormalizedSelectionTypeKind::Any:
    return "Any";
  case NormalizedSelectionTypeKind::Scalar:
    return "Scalar";
  case NormalizedSelectionTypeKind::Pointer:
    return "Pointer";
  }
  return "Any";
}

void emitInstruction(std::ostream &Output, std::string_view Opcode, std::uint32_t OperandIndex,
                     std::uint32_t Value = 0, std::string_view Auxiliary = "0",
                     std::int64_t Immediate = 0) {
  Output << "    {GIMatchTableOpcode::" << Opcode << ", " << OperandIndex << ", " << Value << ", "
         << Auxiliary << ", " << Immediate << "},\n";
}

void emitTypePredicate(std::ostream &Output, std::uint32_t OperandIndex,
                       const NormalizedSelectionTypePredicate &Predicate) {
  emitInstruction(Output, "CheckOperandType", OperandIndex, Predicate.Bits,
                  "static_cast<std::uint32_t>(GIMatchTypeKind::" +
                      std::string(typeKindName(Predicate.Kind)) + ")");
}

[[nodiscard]] std::size_t instructionCount(const NormalizedSelectionRule &Rule) noexcept {
  return 3U + (Rule.ResultType ? 1U : 0U) + Rule.OperandTypes.size() + Rule.OperandBanks.size() +
         Rule.OperandClasses.size() + Rule.AppendedImmediates.size();
}

} // namespace

std::string emitGlobalISel(const NormalizedTargetModel &Model, std::string_view SourceName) {
  std::size_t InstructionCount = 0;
  for (const NormalizedSelectionRule &Rule : Model.SelectionRules)
    InstructionCount += instructionCount(Rule);

  std::ostringstream Output;
  Output << "// SPDX-License-Identifier: GPL-3.0-or-later\n\n";
  Output << "// This file is generated by rcc-tblgen from ";
  appendQuoted(Output, SourceName);
  Output << ". Do not edit it manually.\n\n";
  Output << "#ifdef GET_GLOBALISEL_MATCH_TABLE\n\n";
  Output << "constexpr std::array<GIMatchTableInstruction, " << InstructionCount
         << "> GeneratedGlobalISelInstructions = {{\n";
  for (const NormalizedSelectionRule &Rule : Model.SelectionRules) {
    emitInstruction(Output, "CheckOpcode", 0, Rule.MatchOpcode);
    if (Rule.ResultType)
      emitTypePredicate(Output, 0, *Rule.ResultType);
    for (const NormalizedSelectionOperandTypePredicate &Predicate : Rule.OperandTypes)
      emitTypePredicate(Output, Predicate.OperandIndex, Predicate.Type);
    for (const NormalizedSelectionOperandBankPredicate &Predicate : Rule.OperandBanks)
      emitInstruction(Output, "CheckOperandBank", Predicate.OperandIndex, Predicate.Bank);
    for (const NormalizedSelectionOperandClassPredicate &Predicate : Rule.OperandClasses)
      emitInstruction(Output, "CheckOperandClass", Predicate.OperandIndex, Predicate.RegClass);
    emitInstruction(Output, "MutateOpcode", 0, Rule.ResultOpcode);
    for (const std::int64_t Immediate : Rule.AppendedImmediates)
      emitInstruction(Output, "AppendImmediate", 0, 0, "0", Immediate);
    emitInstruction(Output, "Complete", 0);
  }
  Output << "}};\n\n";

  Output << "constexpr std::array<GIMatchTableRule, " << Model.SelectionRules.size()
         << "> GeneratedGlobalISelRules = {{\n";
  std::size_t FirstInstruction = 0;
  for (const NormalizedSelectionRule &Rule : Model.SelectionRules) {
    const std::size_t Count = instructionCount(Rule);
    Output << "    {";
    appendQuoted(Output, Rule.Symbol);
    Output << ", " << Rule.Priority << ", " << FirstInstruction << ", " << Count << "},\n";
    FirstInstruction += Count;
  }
  Output << "}};\n\n";
  Output << "[[nodiscard]] constexpr GIMatchTable generatedGlobalISelMatchTable() noexcept {\n"
            "  return {GeneratedGlobalISelInstructions, GeneratedGlobalISelRules};\n"
            "}\n\n";
  Output << "#endif // GET_GLOBALISEL_MATCH_TABLE\n";
  return Output.str();
}

} // namespace rcc::targetgen