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# Copyright 2019 Google LLC
#
# 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
#
# https://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.
"""Module which adds and verifies attributes in Emboss IR.
The main entry point is normalize_and_verify(), which adds attributes and/or
verifies attributes which may have been manually entered.
"""
import re
from compiler.front_end import attributes
from compiler.front_end import type_check
from compiler.util import attribute_util
from compiler.util import error
from compiler.util import ir_pb2
from compiler.util import ir_util
from compiler.util import traverse_ir
# Default value for maximum_bits on an `enum`.
_DEFAULT_ENUM_MAXIMUM_BITS = 64
# Default value for expected_back_ends -- mostly for legacy
_DEFAULT_BACK_ENDS = "cpp"
# Attribute type checkers
_VALID_BYTE_ORDER = attribute_util.string_from_list(
{"BigEndian", "LittleEndian", "Null"})
_VALID_TEXT_OUTPUT = attribute_util.string_from_list({"Emit", "Skip"})
def _valid_back_ends(attr, module_source_file):
if not re.match(
r"^(?:\s*[a-z][a-z0-9_]*\s*(?:,\s*[a-z][a-z0-9_]*\s*)*,?)?\s*$",
attr.value.string_constant.text):
return [[error.error(
module_source_file,
attr.value.source_location,
"Attribute '{name}' must be a comma-delimited list of back end "
"specifiers (like \"cpp, proto\")), not \"{value}\".".format(
name=attr.name.text,
value=attr.value.string_constant.text))]]
return []
# Attributes must be the same type no matter where they occur.
_ATTRIBUTE_TYPES = {
attributes.ADDRESSABLE_UNIT_SIZE: attribute_util.INTEGER_CONSTANT,
attributes.BYTE_ORDER: _VALID_BYTE_ORDER,
attributes.ENUM_MAXIMUM_BITS: attribute_util.INTEGER_CONSTANT,
attributes.FIXED_SIZE: attribute_util.INTEGER_CONSTANT,
attributes.IS_INTEGER: attribute_util.BOOLEAN_CONSTANT,
attributes.IS_SIGNED: attribute_util.BOOLEAN_CONSTANT,
attributes.REQUIRES: attribute_util.BOOLEAN,
attributes.STATIC_REQUIREMENTS: attribute_util.BOOLEAN,
attributes.TEXT_OUTPUT: _VALID_TEXT_OUTPUT,
attributes.BACK_ENDS: _valid_back_ends,
}
_MODULE_ATTRIBUTES = {
(attributes.BYTE_ORDER, True),
(attributes.BACK_ENDS, False),
}
_BITS_ATTRIBUTES = {
(attributes.FIXED_SIZE, False),
(attributes.REQUIRES, False),
}
_STRUCT_ATTRIBUTES = {
(attributes.FIXED_SIZE, False),
(attributes.BYTE_ORDER, True),
(attributes.REQUIRES, False),
}
_ENUM_ATTRIBUTES = {
(attributes.ENUM_MAXIMUM_BITS, False),
(attributes.IS_SIGNED, False),
}
_EXTERNAL_ATTRIBUTES = {
(attributes.ADDRESSABLE_UNIT_SIZE, False),
(attributes.FIXED_SIZE, False),
(attributes.IS_INTEGER, False),
(attributes.STATIC_REQUIREMENTS, False),
}
_STRUCT_PHYSICAL_FIELD_ATTRIBUTES = {
(attributes.BYTE_ORDER, False),
(attributes.REQUIRES, False),
(attributes.TEXT_OUTPUT, False),
}
_STRUCT_VIRTUAL_FIELD_ATTRIBUTES = {
(attributes.REQUIRES, False),
(attributes.TEXT_OUTPUT, False),
}
def _construct_integer_attribute(name, value, source_location):
"""Constructs an integer Attribute with the given name and value."""
attr_value = ir_pb2.AttributeValue(
expression=ir_pb2.Expression(
constant=ir_pb2.NumericConstant(value=str(value),
source_location=source_location),
type=ir_pb2.ExpressionType(
integer=ir_pb2.IntegerType(modular_value=str(value),
modulus="infinity",
minimum_value=str(value),
maximum_value=str(value))),
source_location=source_location),
source_location=source_location)
return ir_pb2.Attribute(name=ir_pb2.Word(text=name,
source_location=source_location),
value=attr_value,
source_location=source_location)
def _construct_boolean_attribute(name, value, source_location):
"""Constructs a boolean Attribute with the given name and value."""
attr_value = ir_pb2.AttributeValue(
expression=ir_pb2.Expression(
boolean_constant=ir_pb2.BooleanConstant(
value=value, source_location=source_location),
type=ir_pb2.ExpressionType(boolean=ir_pb2.BooleanType(value=value)),
source_location=source_location),
source_location=source_location)
return ir_pb2.Attribute(name=ir_pb2.Word(text=name,
source_location=source_location),
value=attr_value,
source_location=source_location)
def _construct_string_attribute(name, value, source_location):
"""Constructs a string Attribute with the given name and value."""
attr_value = ir_pb2.AttributeValue(
string_constant=ir_pb2.String(text=value,
source_location=source_location),
source_location=source_location)
return ir_pb2.Attribute(name=ir_pb2.Word(text=name,
source_location=source_location),
value=attr_value,
source_location=source_location)
def _fixed_size_of_struct_or_bits(struct, unit_size):
"""Returns size of struct in bits or None, if struct is not fixed size."""
size = 0
for field in struct.field:
if not field.HasField("location"):
# Virtual fields do not contribute to the physical size of the struct.
continue
field_start = ir_util.constant_value(field.location.start)
field_size = ir_util.constant_value(field.location.size)
if field_start is None or field_size is None:
# Technically, start + size could be constant even if start and size are
# not; e.g. if start == x and size == 10 - x, but we don't handle that
# here.
return None
# TODO(bolms): knows_own_size
# TODO(bolms): compute min/max sizes for variable-sized arrays.
field_end = field_start + field_size
if field_end >= size:
size = field_end
return size * unit_size
def _verify_size_attributes_on_structure(struct, type_definition,
source_file_name, errors):
"""Verifies size attributes on a struct or bits."""
fixed_size = _fixed_size_of_struct_or_bits(struct,
type_definition.addressable_unit)
fixed_size_attr = ir_util.get_attribute(type_definition.attribute,
attributes.FIXED_SIZE)
if not fixed_size_attr:
return
if fixed_size is None:
errors.append([error.error(
source_file_name, fixed_size_attr.source_location,
"Struct is marked as fixed size, but contains variable-location "
"fields.")])
elif ir_util.constant_value(fixed_size_attr.expression) != fixed_size:
errors.append([error.error(
source_file_name, fixed_size_attr.source_location,
"Struct is {} bits, but is marked as {} bits.".format(
fixed_size, ir_util.constant_value(fixed_size_attr.expression)))])
# TODO(bolms): remove [fixed_size]; it is superseded by $size_in_{bits,bytes}
def _add_missing_size_attributes_on_structure(struct, type_definition):
"""Adds missing size attributes on a struct."""
fixed_size = _fixed_size_of_struct_or_bits(struct,
type_definition.addressable_unit)
if fixed_size is None:
return
fixed_size_attr = ir_util.get_attribute(type_definition.attribute,
attributes.FIXED_SIZE)
if not fixed_size_attr:
# TODO(bolms): Use the offset and length of the last field as the
# source_location of the fixed_size attribute?
type_definition.attribute.extend([
_construct_integer_attribute(attributes.FIXED_SIZE, fixed_size,
type_definition.source_location)])
def _field_needs_byte_order(field, type_definition, ir):
"""Returns true if the given field needs a byte_order attribute."""
if ir_util.field_is_virtual(field):
# Virtual fields have no physical type, and thus do not need a byte order.
return False
field_type = ir_util.find_object(
ir_util.get_base_type(field.type).atomic_type.reference.canonical_name,
ir)
assert field_type is not None
assert field_type.addressable_unit != ir_pb2.AddressableUnit.NONE
return field_type.addressable_unit != type_definition.addressable_unit
def _field_may_have_null_byte_order(field, type_definition, ir):
"""Returns true if "Null" is a valid byte order for the given field."""
# If the field is one unit in length, then byte order does not matter.
if (ir_util.is_constant(field.location.size) and
ir_util.constant_value(field.location.size) == 1):
return True
unit = type_definition.addressable_unit
# Otherwise, if the field's type is either a one-unit-sized type or an array
# of a one-unit-sized type, then byte order does not matter.
if (ir_util.fixed_size_of_type_in_bits(ir_util.get_base_type(field.type), ir)
== unit):
return True
# In all other cases, byte order does matter.
return False
def _add_missing_byte_order_attribute_on_field(field, type_definition, ir,
defaults):
"""Adds missing byte_order attributes to fields that need them."""
if _field_needs_byte_order(field, type_definition, ir):
byte_order_attr = ir_util.get_attribute(field.attribute,
attributes.BYTE_ORDER)
if byte_order_attr is None:
if attributes.BYTE_ORDER in defaults:
field.attribute.extend([defaults[attributes.BYTE_ORDER]])
elif _field_may_have_null_byte_order(field, type_definition, ir):
field.attribute.extend(
[_construct_string_attribute(attributes.BYTE_ORDER, "Null",
field.source_location)])
def _add_missing_back_ends_to_module(module):
"""Sets the expected_back_ends attribute for a module, if not already set."""
back_ends_attr = ir_util.get_attribute(module.attribute, attributes.BACK_ENDS)
if back_ends_attr is None:
module.attribute.extend(
[_construct_string_attribute(attributes.BACK_ENDS, _DEFAULT_BACK_ENDS,
module.source_location)])
def _gather_expected_back_ends(module):
"""Captures the expected_back_ends attribute for `module`."""
back_ends_attr = ir_util.get_attribute(module.attribute, attributes.BACK_ENDS)
back_ends_str = back_ends_attr.string_constant.text
return {
"expected_back_ends": {x.strip() for x in back_ends_str.split(",")} | {""}
}
def _add_addressable_unit_to_external(external, type_definition):
"""Sets the addressable_unit field for an external TypeDefinition."""
# Strictly speaking, addressable_unit isn't an "attribute," but it's close
# enough that it makes sense to handle it with attributes.
del external # Unused.
size = ir_util.get_integer_attribute(type_definition.attribute,
attributes.ADDRESSABLE_UNIT_SIZE)
if size == 1:
type_definition.addressable_unit = ir_pb2.AddressableUnit.BIT
elif size == 8:
type_definition.addressable_unit = ir_pb2.AddressableUnit.BYTE
# If the addressable_unit_size is not in (1, 8), it will be caught by
# _verify_addressable_unit_attribute_on_external, below.
def _add_missing_width_and_sign_attributes_on_enum(enum, type_definition):
"""Sets the maximum_bits and is_signed attributes for an enum, if needed."""
max_bits_attr = ir_util.get_integer_attribute(type_definition.attribute,
attributes.ENUM_MAXIMUM_BITS)
if max_bits_attr is None:
type_definition.attribute.extend([
_construct_integer_attribute(attributes.ENUM_MAXIMUM_BITS,
_DEFAULT_ENUM_MAXIMUM_BITS,
type_definition.source_location)])
signed_attr = ir_util.get_boolean_attribute(type_definition.attribute,
attributes.IS_SIGNED)
if signed_attr is None:
for value in enum.value:
numeric_value = ir_util.constant_value(value.value)
if numeric_value < 0:
is_signed = True
break
else:
is_signed = False
type_definition.attribute.extend([
_construct_boolean_attribute(attributes.IS_SIGNED, is_signed,
type_definition.source_location)])
def _verify_byte_order_attribute_on_field(field, type_definition,
source_file_name, ir, errors):
"""Verifies the byte_order attribute on the given field."""
byte_order_attr = ir_util.get_attribute(field.attribute,
attributes.BYTE_ORDER)
field_needs_byte_order = _field_needs_byte_order(field, type_definition, ir)
if byte_order_attr and not field_needs_byte_order:
errors.append([error.error(
source_file_name, byte_order_attr.source_location,
"Attribute 'byte_order' not allowed on field which is not byte order "
"dependent.")])
if not byte_order_attr and field_needs_byte_order:
errors.append([error.error(
source_file_name, field.source_location,
"Attribute 'byte_order' required on field which is byte order "
"dependent.")])
if (byte_order_attr and byte_order_attr.string_constant.text == "Null" and
not _field_may_have_null_byte_order(field, type_definition, ir)):
errors.append([error.error(
source_file_name, byte_order_attr.source_location,
"Attribute 'byte_order' may only be 'Null' for one-byte fields.")])
def _verify_requires_attribute_on_field(field, source_file_name, ir, errors):
"""Verifies that [requires] is valid on the given field."""
requires_attr = ir_util.get_attribute(field.attribute, attributes.REQUIRES)
if not requires_attr:
return
if ir_util.field_is_virtual(field):
field_expression_type = field.read_transform.type
else:
if not field.type.HasField("atomic_type"):
errors.append([
error.error(source_file_name, requires_attr.source_location,
"Attribute 'requires' is only allowed on integer, "
"enumeration, or boolean fields, not arrays."),
error.note(source_file_name, field.type.source_location,
"Field type."),
])
return
field_type = ir_util.find_object(field.type.atomic_type.reference, ir)
assert field_type, "Field type should be non-None after name resolution."
field_expression_type = (
type_check.unbounded_expression_type_for_physical_type(field_type))
if field_expression_type.WhichOneof("type") not in (
"integer", "enumeration", "boolean"):
errors.append([error.error(
source_file_name, requires_attr.source_location,
"Attribute 'requires' is only allowed on integer, enumeration, or "
"boolean fields.")])
def _verify_addressable_unit_attribute_on_external(external, type_definition,
source_file_name, errors):
"""Verifies the addressable_unit_size attribute on an external."""
del external # Unused.
addressable_unit_size_attr = ir_util.get_integer_attribute(
type_definition.attribute, attributes.ADDRESSABLE_UNIT_SIZE)
if addressable_unit_size_attr is None:
errors.append([error.error(
source_file_name, type_definition.source_location,
"Expected '{}' attribute for external type.".format(
attributes.ADDRESSABLE_UNIT_SIZE))])
elif addressable_unit_size_attr not in (1, 8):
errors.append([
error.error(source_file_name, type_definition.source_location,
"Only values '1' (bit) and '8' (byte) are allowed for the "
"'{}' attribute".format(attributes.ADDRESSABLE_UNIT_SIZE))
])
def _verify_width_attribute_on_enum(enum, type_definition, source_file_name,
errors):
"""Verifies the maximum_bits attribute for an enum TypeDefinition."""
max_bits_value = ir_util.get_integer_attribute(type_definition.attribute,
attributes.ENUM_MAXIMUM_BITS)
# The attribute should already have been defaulted, if not originally present.
assert max_bits_value is not None, "maximum_bits not set"
if max_bits_value > 64 or max_bits_value < 1:
max_bits_attr = ir_util.get_attribute(type_definition.attribute,
attributes.ENUM_MAXIMUM_BITS)
errors.append([
error.error(source_file_name, max_bits_attr.source_location,
"'maximum_bits' on an 'enum' must be between 1 and 64.")
])
def _add_missing_attributes_on_ir(ir):
"""Adds missing attributes in a complete IR."""
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Module], _add_missing_back_ends_to_module)
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.External], _add_addressable_unit_to_external)
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Enum], _add_missing_width_and_sign_attributes_on_enum)
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Structure], _add_missing_size_attributes_on_structure,
incidental_actions={
ir_pb2.Module: attribute_util.gather_default_attributes,
ir_pb2.TypeDefinition: attribute_util.gather_default_attributes,
ir_pb2.Field: attribute_util.gather_default_attributes,
},
parameters={"defaults": {}})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Field], _add_missing_byte_order_attribute_on_field,
incidental_actions={
ir_pb2.Module: attribute_util.gather_default_attributes,
ir_pb2.TypeDefinition: attribute_util.gather_default_attributes,
ir_pb2.Field: attribute_util.gather_default_attributes,
},
parameters={"defaults": {}})
return []
def _verify_field_attributes(field, type_definition, source_file_name, ir,
errors):
_verify_byte_order_attribute_on_field(field, type_definition,
source_file_name, ir, errors)
_verify_requires_attribute_on_field(field, source_file_name, ir, errors)
def _verify_back_end_attributes(attribute, expected_back_ends, source_file_name,
ir, errors):
back_end_text = attribute.back_end.text
if back_end_text not in expected_back_ends:
expected_back_ends_for_error = expected_back_ends - {""}
errors.append([error.error(
source_file_name, attribute.back_end.source_location,
"Back end specifier '{back_end}' does not match any expected back end "
"specifier for this file: '{expected_back_ends}'. Add or update the "
"'[expected_back_ends: \"{new_expected_back_ends}\"]' attribute at the "
"file level if this back end specifier is intentional.".format(
back_end=attribute.back_end.text,
expected_back_ends="', '".join(
sorted(expected_back_ends_for_error)),
new_expected_back_ends=", ".join(
sorted(expected_back_ends_for_error | {back_end_text})),
))])
def _verify_attributes_on_ir(ir):
"""Verifies attributes in a complete IR."""
errors = []
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Attribute], _verify_back_end_attributes,
incidental_actions={
ir_pb2.Module: _gather_expected_back_ends,
},
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Structure], _verify_size_attributes_on_structure,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Enum], _verify_width_attribute_on_enum,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.External], _verify_addressable_unit_attribute_on_external,
parameters={"errors": errors})
traverse_ir.fast_traverse_ir_top_down(
ir, [ir_pb2.Field], _verify_field_attributes,
parameters={"errors": errors})
return errors
def normalize_and_verify(ir):
"""Performs various normalizations and verifications on ir.
Checks for duplicate attributes.
Adds fixed_size_in_bits and addressable_unit_size attributes to types when
they are missing, and checks their correctness when they are not missing.
Arguments:
ir: The IR object to normalize.
Returns:
A list of validation errors, or an empty list if no errors were encountered.
"""
errors = attribute_util.check_attributes_in_ir(
ir,
types=_ATTRIBUTE_TYPES,
module_attributes=_MODULE_ATTRIBUTES,
struct_attributes=_STRUCT_ATTRIBUTES,
bits_attributes=_BITS_ATTRIBUTES,
enum_attributes=_ENUM_ATTRIBUTES,
external_attributes=_EXTERNAL_ATTRIBUTES,
structure_virtual_field_attributes=_STRUCT_VIRTUAL_FIELD_ATTRIBUTES,
structure_physical_field_attributes=_STRUCT_PHYSICAL_FIELD_ATTRIBUTES)
if errors:
return errors
_add_missing_attributes_on_ir(ir)
return _verify_attributes_on_ir(ir)