Module: MilkTea::Layout

Included in:
ConstEval::Evaluator
Defined in:
lib/milk_tea/core/types/layout.rb

Constant Summary collapse

POINTER_SIZE = 
Fiddle::SIZEOF_VOIDP

Class Method Summary collapse

Class Method Details

.align_up(value, alignment) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 227

def align_up(value, alignment)
  return value if alignment <= 1

  remainder = value % alignment
  remainder.zero? ? value : value + alignment - remainder
end

.alignment_of(type) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 16

def alignment_of(type)
  size_and_alignment(type, {})&.last
end

.array_type?(type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/types/layout.rb', line 196

def array_type?(type)
  type.arguments.length == 2 && type.arguments[1].is_a?(Types::LiteralTypeArg) && type.arguments[1].value.is_a?(Integer)
end

.explicit_alignment(type) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 192

def explicit_alignment(type)
  type.respond_to?(:alignment) ? type.alignment : nil
end

.generic_layout(type, stack) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 95

def generic_layout(type, stack)
  case type.name
  when "ptr", "const_ptr", "own", "ref"
    [POINTER_SIZE, POINTER_SIZE]
  when "array"
    return unless array_type?(type)

    element_layout = size_and_alignment(type.arguments.first, stack)
    return unless element_layout

    [element_layout.first * type.arguments[1].value, element_layout.last]
  when "str_buffer"
    return unless str_buffer_type?(type)

    with_stack(type, stack) do
      layout = struct_layout(str_buffer_fields(type), packed: false, alignment: nil, stack:)
      [layout[:size], layout[:alignment]]
    end
  end
end

.layout_pointer_like_nullable_base?(base) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/types/layout.rb', line 213

def layout_pointer_like_nullable_base?(base)
  return true if base.is_a?(Types::Function) || base.is_a?(Types::Proc) || base.is_a?(Types::Opaque)
  return true if base.is_a?(Types::Primitive) && base.name == "cstr"

  base.is_a?(Types::GenericInstance) && %w[ptr const_ptr own ref].include?(base.name)
end

.nullable_opt_layout_fields(base) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 220

def nullable_opt_layout_fields(base)
  {
    "has_value" => Types::Registry.primitive("bool"),
    "value" => base,
  }
end

.offset_of(type, field_name) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 20

def offset_of(type, field_name)
  case type
  when Types::Struct, Types::StructInstance, Types::Span, Types::StringView, Types::Task
    fields = ordered_fields(type)
    return unless fields.key?(field_name)

    struct_layout(fields, packed: packed_layout?(type), alignment: explicit_alignment(type), stack: {})[:offsets][field_name]
  when Types::Union
    type.field(field_name) ? 0 : nil
  when Types::GenericInstance
    return unless str_buffer_type?(type)

    fields = str_buffer_fields(type)
    return unless fields.key?(field_name)

    struct_layout(fields, packed: false, alignment: nil, stack: {})[:offsets][field_name]
  else
    nil
  end
end

.ordered_fields(type) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 184

def ordered_fields(type)
  type.fields
end

.packed_layout?(type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/types/layout.rb', line 188

def packed_layout?(type)
  type.respond_to?(:packed) && type.packed
end

.primitive_layout(type) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 78

def primitive_layout(type)
  case type.name
  when "bool", "byte", "ubyte", "char"
    [1, 1]
  when "short", "ushort"
    [2, 2]
  when "int", "uint", "float"
    [4, 4]
  when "long", "ulong", "double"
    [8, 8]
  when "ptr_int", "ptr_uint", "cstr"
    [POINTER_SIZE, POINTER_SIZE]
  else
    nil
  end
end

.size_and_alignment(type, stack) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 41

def size_and_alignment(type, stack)
  case type
  when Types::Primitive
    primitive_layout(type)
  when Types::EnumBase
    size_and_alignment(type.backing_type, stack)
  when Types::Nullable, Types::Function
    if type.is_a?(Types::Function) || layout_pointer_like_nullable_base?(type.base)
      [POINTER_SIZE, POINTER_SIZE]
    else
      with_stack(type, stack) do
        layout = struct_layout(nullable_opt_layout_fields(type.base), packed: false, alignment: nil, stack:)
        [layout[:size], layout[:alignment]]
      end
    end
  when Types::StringView, Types::Span, Types::Task, Types::Struct, Types::StructInstance
    with_stack(type, stack) do
      layout = struct_layout(ordered_fields(type), packed: packed_layout?(type), alignment: explicit_alignment(type), stack:)
      [layout[:size], layout[:alignment]]
    end
  when Types::Union
    with_stack(type, stack) do
      layout = union_layout(ordered_fields(type), packed: packed_layout?(type), alignment: explicit_alignment(type), stack:)
      [layout[:size], layout[:alignment]]
    end
  when Types::Variant, Types::VariantInstance
    with_stack(type, stack) do
      layout = variant_layout(type, stack:)
      [layout[:size], layout[:alignment]]
    end
  when Types::GenericInstance
    generic_layout(type, stack)
  else
    nil
  end
end

.size_of(type) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 12

def size_of(type)
  size_and_alignment(type, {})&.first
end

.str_buffer_fields(type) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 204

def str_buffer_fields(type)
  storage_capacity = type.arguments.first.value + 1
  {
    "data" => Types::Registry.generic_instance("array", [Types::Registry.primitive("char"), Types::LiteralTypeArg.new(storage_capacity)]),
    "len" => Types::Registry.primitive("ptr_uint"),
    "dirty" => Types::Registry.primitive("bool"),
  }
end

.str_buffer_type?(type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/types/layout.rb', line 200

def str_buffer_type?(type)
  type.arguments.length == 1 && type.arguments.first.is_a?(Types::LiteralTypeArg) && type.arguments.first.value.is_a?(Integer)
end

.struct_layout(fields, packed:, alignment:, stack:) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 130

def struct_layout(fields, packed:, alignment:, stack:)
  field_infos = fields.map do |field_name, field_type|
    field_layout = size_and_alignment(field_type, stack)
    return nil unless field_layout

    [field_name, field_layout.first, field_layout.last]
  end

  struct_layout_from_infos(field_infos, packed:, alignment:)
end

.struct_layout_from_infos(field_infos, packed:, alignment:) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 152

def struct_layout_from_infos(field_infos, packed:, alignment:)
  offsets = {}
  offset = 0
  natural_alignment = 1

  field_infos.each do |field_name, field_size, field_alignment|
    effective_alignment = packed ? 1 : field_alignment
    natural_alignment = [natural_alignment, effective_alignment].max
    offset = align_up(offset, effective_alignment) unless packed
    offsets[field_name] = offset
    offset += field_size
  end

  overall_alignment = [natural_alignment, alignment || 1].max
  {
    size: align_up(offset, overall_alignment),
    alignment: overall_alignment,
    offsets:,
  }
end

.union_layout(fields, packed:, alignment:, stack:) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 141

def union_layout(fields, packed:, alignment:, stack:)
  field_infos = fields.map do |_field_name, field_type|
    field_layout = size_and_alignment(field_type, stack)
    return nil unless field_layout

    field_layout
  end

  union_layout_from_layouts(field_infos.map { |size, field_alignment| { size:, alignment: field_alignment } }, packed:, alignment:)
end

.union_layout_from_layouts(layouts, packed:, alignment:) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 173

def union_layout_from_layouts(layouts, packed:, alignment:)
  natural_alignment = packed ? 1 : (layouts.map { |layout| layout[:alignment] }.max || 1)
  overall_alignment = [natural_alignment, alignment || 1].max
  size = layouts.map { |layout| layout[:size] }.max || 0

  {
    size: align_up(size, overall_alignment),
    alignment: overall_alignment,
  }
end

.variant_layout(type, stack:) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 116

def variant_layout(type, stack:)
  payload_layouts = type.arm_names.filter_map do |arm_name|
    fields = type.arm(arm_name)
    next if fields.nil? || fields.empty?

    struct_layout(fields, packed: false, alignment: nil, stack:)
  end

  data_layout = union_layout_from_layouts(payload_layouts, packed: false, alignment: nil)
  field_infos = [["kind", 4, 4]]
  field_infos << ["data", data_layout[:size], data_layout[:alignment]] if data_layout[:size].positive?
  struct_layout_from_infos(field_infos, packed: false, alignment: nil)
end

.with_stack(type, stack) ⇒ Object 



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# File 'lib/milk_tea/core/types/layout.rb', line 234

def with_stack(type, stack)
  return if stack[type]

  stack[type] = true
  yield
ensure
  stack.delete(type)
end