Class ConstantManager

lib/Bytecode/Writer/BytecodeWriter.cpp:465–574

//
namespace {
struct ConstantManager {
  LogicalResult addConstant(Attribute attr, uint64_t &index) {
    auto it = constantsMap.find(attr);
    if (it != constantsMap.end()) {
      index = std::distance(constantsMap.begin(), it);
      return success();
    }
    SmallVector<char> data;
    llvm::raw_svector_ostream dataStream(data);
    EncodingWriter writer(dataStream);
    if (failed(serializeAttribute(attr, writer)))
      return emitError(UnknownLoc::get(attr.getContext()),
                       "failed to serialize attribute");
    index = constantsMap.size();
    constantsMap[attr] = std::move(data);
    return success();
  }

  // Look up a constant by attribute without adding it
  LogicalResult getConstantIndex(Attribute attr, uint64_t &index) const {
    auto it = constantsMap.find(attr);
    if (it != constantsMap.end()) {
      index = std::distance(constantsMap.begin(), it);
      return success();
    }
    return failure();
  }

  // Provide access to the constant map
  const llvm::MapVector<Attribute, SmallVector<char>> &getConstantsMap() const {
    return constantsMap;
  }

  /// Serializes a single MLIR attribute into its raw byte representation.
  /// This function handles different attribute types, focusing on scalar
  /// and dense element attributes suitable for the constant pool.
  LogicalResult serializeAttribute(Attribute attr, EncodingWriter &writer) {
    if (auto denseAttr = dyn_cast<DenseElementsAttr>(attr)) {
      // Get the raw data buffer in little-endian format.
      ArrayRef<char> rawData = denseAttr.getRawData();
      // Write the size of the raw buffer.
      writer.writeVarInt(rawData.size());
      // Write the raw buffer content.
      writer.write(rawData.data(), rawData.size());
      return success();
    } else if (auto intAttr = dyn_cast<IntegerAttr>(attr)) {
      APInt value = intAttr.getValue();
      writer.writeLE<uint64_t>(value.getZExtValue());
      return success();
    } else if (auto boolAttr = dyn_cast<BoolAttr>(attr)) {
      uint8_t boolValue = boolAttr.getValue() ? 0x01 : 0x00;
      writer.writeByte(boolValue);
      return success();
    } else if (auto floatAttr = dyn_cast<FloatAttr>(attr)) {
      writeAPFloatRepresentation(floatAttr.getValue(), writer);
      return success();
    }
    return emitError(UnknownLoc::get(attr.getContext()),