rust/src/etc/debugger_pretty_printers_common.py
2015-07-17 10:43:58 -07:00

327 lines
12 KiB
Python

# Copyright 2015 The Rust Project Developers. See the COPYRIGHT
# file at the top-level directory of this distribution and at
# http://rust-lang.org/COPYRIGHT.
#
# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
# option. This file may not be copied, modified, or distributed
# except according to those terms.
"""
This module provides an abstraction layer over common Rust pretty printing
functionality needed by both GDB and LLDB.
"""
import re
# Type codes that indicate the kind of type as it appears in DWARF debug
# information. This code alone is not sufficient to determine the Rust type.
# For example structs, tuples, fat pointers, or enum variants will all have
# DWARF_TYPE_CODE_STRUCT.
DWARF_TYPE_CODE_STRUCT = 1
DWARF_TYPE_CODE_UNION = 2
DWARF_TYPE_CODE_PTR = 3
DWARF_TYPE_CODE_ARRAY = 4
DWARF_TYPE_CODE_ENUM = 5
# These constants specify the most specific kind of type that could be
# determined for a given value.
TYPE_KIND_UNKNOWN = -1
TYPE_KIND_EMPTY = 0
TYPE_KIND_SLICE = 1
TYPE_KIND_REGULAR_STRUCT = 2
TYPE_KIND_TUPLE = 3
TYPE_KIND_TUPLE_STRUCT = 4
TYPE_KIND_CSTYLE_VARIANT = 5
TYPE_KIND_TUPLE_VARIANT = 6
TYPE_KIND_STRUCT_VARIANT = 7
TYPE_KIND_STR_SLICE = 8
TYPE_KIND_STD_VEC = 9
TYPE_KIND_STD_STRING = 10
TYPE_KIND_REGULAR_ENUM = 11
TYPE_KIND_COMPRESSED_ENUM = 12
TYPE_KIND_SINGLETON_ENUM = 13
TYPE_KIND_CSTYLE_ENUM = 14
TYPE_KIND_PTR = 15
TYPE_KIND_FIXED_SIZE_VEC = 16
ENCODED_ENUM_PREFIX = "RUST$ENCODED$ENUM$"
ENUM_DISR_FIELD_NAME = "RUST$ENUM$DISR"
# Slice related constants
SLICE_FIELD_NAME_DATA_PTR = "data_ptr"
SLICE_FIELD_NAME_LENGTH = "length"
SLICE_FIELD_NAMES = [SLICE_FIELD_NAME_DATA_PTR, SLICE_FIELD_NAME_LENGTH]
# std::Vec<> related constants
STD_VEC_FIELD_NAME_LENGTH = "len"
STD_VEC_FIELD_NAME_BUF = "buf"
STD_VEC_FIELD_NAMES = [STD_VEC_FIELD_NAME_BUF,
STD_VEC_FIELD_NAME_LENGTH]
# std::String related constants
STD_STRING_FIELD_NAMES = ["vec"]
class Type(object):
"""
This class provides a common interface for type-oriented operations.
Sub-classes are supposed to wrap a debugger-specific type-object and
provide implementations for the abstract methods in this class.
"""
def __init__(self):
self.__type_kind = None
def get_unqualified_type_name(self):
"""
Implementations of this method should return the unqualified name of the
type-object they are wrapping. Some examples:
'int' -> 'int'
'std::vec::Vec<std::string::String>' -> 'Vec<std::string::String>'
'&std::option::Option<std::string::String>' -> '&std::option::Option<std::string::String>'
As you can see, type arguments stay fully qualified.
"""
raise NotImplementedError("Override this method")
def get_dwarf_type_kind(self):
"""
Implementations of this method should return the correct
DWARF_TYPE_CODE_* value for the wrapped type-object.
"""
raise NotImplementedError("Override this method")
def get_fields(self):
"""
Implementations of this method should return a list of field-objects of
this type. For Rust-enums (i.e. with DWARF_TYPE_CODE_UNION) these field-
objects represent the variants of the enum. Field-objects must have a
`name` attribute that gives their name as specified in DWARF.
"""
assert ((self.get_dwarf_type_kind() == DWARF_TYPE_CODE_STRUCT) or
(self.get_dwarf_type_kind() == DWARF_TYPE_CODE_UNION))
raise NotImplementedError("Override this method")
def get_wrapped_value(self):
"""
Returns the debugger-specific type-object wrapped by this object. This
is sometimes needed for doing things like pointer-arithmetic in GDB.
"""
raise NotImplementedError("Override this method")
def get_type_kind(self):
"""This method returns the TYPE_KIND_* value for this type-object."""
if self.__type_kind is None:
dwarf_type_code = self.get_dwarf_type_kind()
if dwarf_type_code == DWARF_TYPE_CODE_STRUCT:
self.__type_kind = self.__classify_struct()
elif dwarf_type_code == DWARF_TYPE_CODE_UNION:
self.__type_kind = self.__classify_union()
elif dwarf_type_code == DWARF_TYPE_CODE_PTR:
self.__type_kind = TYPE_KIND_PTR
elif dwarf_type_code == DWARF_TYPE_CODE_ARRAY:
self.__type_kind = TYPE_KIND_FIXED_SIZE_VEC
else:
self.__type_kind = TYPE_KIND_UNKNOWN
return self.__type_kind
def __classify_struct(self):
assert self.get_dwarf_type_kind() == DWARF_TYPE_CODE_STRUCT
unqualified_type_name = self.get_unqualified_type_name()
# STR SLICE
if unqualified_type_name == "&str":
return TYPE_KIND_STR_SLICE
# REGULAR SLICE
if (unqualified_type_name.startswith("&[") and
unqualified_type_name.endswith("]") and
self.__conforms_to_field_layout(SLICE_FIELD_NAMES)):
return TYPE_KIND_SLICE
fields = self.get_fields()
field_count = len(fields)
# EMPTY STRUCT
if field_count == 0:
return TYPE_KIND_EMPTY
# STD VEC
if (unqualified_type_name.startswith("Vec<") and
self.__conforms_to_field_layout(STD_VEC_FIELD_NAMES)):
return TYPE_KIND_STD_VEC
# STD STRING
if (unqualified_type_name.startswith("String") and
self.__conforms_to_field_layout(STD_STRING_FIELD_NAMES)):
return TYPE_KIND_STD_STRING
# ENUM VARIANTS
if fields[0].name == ENUM_DISR_FIELD_NAME:
if field_count == 1:
return TYPE_KIND_CSTYLE_VARIANT
elif self.__all_fields_conform_to_tuple_field_naming(1):
return TYPE_KIND_TUPLE_VARIANT
else:
return TYPE_KIND_STRUCT_VARIANT
# TUPLE
if self.__all_fields_conform_to_tuple_field_naming(0):
if unqualified_type_name.startswith("("):
return TYPE_KIND_TUPLE
else:
return TYPE_KIND_TUPLE_STRUCT
# REGULAR STRUCT
return TYPE_KIND_REGULAR_STRUCT
def __classify_union(self):
assert self.get_dwarf_type_kind() == DWARF_TYPE_CODE_UNION
union_members = self.get_fields()
union_member_count = len(union_members)
if union_member_count == 0:
return TYPE_KIND_EMPTY
elif union_member_count == 1:
first_variant_name = union_members[0].name
if first_variant_name is None:
return TYPE_KIND_SINGLETON_ENUM
else:
assert first_variant_name.startswith(ENCODED_ENUM_PREFIX)
return TYPE_KIND_COMPRESSED_ENUM
else:
return TYPE_KIND_REGULAR_ENUM
def __conforms_to_field_layout(self, expected_fields):
actual_fields = self.get_fields()
actual_field_count = len(actual_fields)
if actual_field_count != len(expected_fields):
return False
for i in range(0, actual_field_count):
if actual_fields[i].name != expected_fields[i]:
return False
return True
def __all_fields_conform_to_tuple_field_naming(self, start_index):
fields = self.get_fields()
field_count = len(fields)
for i in range(start_index, field_count):
field_name = fields[i].name
if (field_name is None) or (re.match(r"__\d+$", field_name) is None):
return False
return True
class Value(object):
"""
This class provides a common interface for value-oriented operations.
Sub-classes are supposed to wrap a debugger-specific value-object and
provide implementations for the abstract methods in this class.
"""
def __init__(self, ty):
self.type = ty
def get_child_at_index(self, index):
"""Returns the value of the field, array element or variant at the given index"""
raise NotImplementedError("Override this method")
def as_integer(self):
"""
Try to convert the wrapped value into a Python integer. This should
always succeed for values that are pointers or actual integers.
"""
raise NotImplementedError("Override this method")
def get_wrapped_value(self):
"""
Returns the debugger-specific value-object wrapped by this object. This
is sometimes needed for doing things like pointer-arithmetic in GDB.
"""
raise NotImplementedError("Override this method")
class EncodedEnumInfo(object):
"""
This class provides facilities for handling enum values with compressed
encoding where a non-null field in one variant doubles as the discriminant.
"""
def __init__(self, enum_val):
assert enum_val.type.get_type_kind() == TYPE_KIND_COMPRESSED_ENUM
variant_name = enum_val.type.get_fields()[0].name
last_separator_index = variant_name.rfind("$")
start_index = len(ENCODED_ENUM_PREFIX)
indices_substring = variant_name[start_index:last_separator_index].split("$")
self.__enum_val = enum_val
self.__disr_field_indices = [int(index) for index in indices_substring]
self.__null_variant_name = variant_name[last_separator_index + 1:]
def is_null_variant(self):
ty = self.__enum_val.type
sole_variant_val = self.__enum_val.get_child_at_index(0)
discriminant_val = sole_variant_val
for disr_field_index in self.__disr_field_indices:
discriminant_val = discriminant_val.get_child_at_index(disr_field_index)
# If the discriminant field is a fat pointer we have to consider the
# first word as the true discriminant
if discriminant_val.type.get_dwarf_type_kind() == DWARF_TYPE_CODE_STRUCT:
discriminant_val = discriminant_val.get_child_at_index(0)
return discriminant_val.as_integer() == 0
def get_non_null_variant_val(self):
return self.__enum_val.get_child_at_index(0)
def get_null_variant_name(self):
return self.__null_variant_name
def get_discriminant_value_as_integer(enum_val):
assert enum_val.type.get_dwarf_type_kind() == DWARF_TYPE_CODE_UNION
# we can take any variant here because the discriminant has to be the same
# for all of them.
variant_val = enum_val.get_child_at_index(0)
disr_val = variant_val.get_child_at_index(0)
return disr_val.as_integer()
def extract_length_ptr_and_cap_from_std_vec(vec_val):
assert vec_val.type.get_type_kind() == TYPE_KIND_STD_VEC
length_field_index = STD_VEC_FIELD_NAMES.index(STD_VEC_FIELD_NAME_LENGTH)
buf_field_index = STD_VEC_FIELD_NAMES.index(STD_VEC_FIELD_NAME_BUF)
length = vec_val.get_child_at_index(length_field_index).as_integer()
buf = vec_val.get_child_at_index(buf_field_index)
vec_ptr_val = buf.get_child_at_index(0)
capacity = buf.get_child_at_index(1).as_integer()
unique_ptr_val = vec_ptr_val.get_child_at_index(0)
data_ptr = unique_ptr_val.get_child_at_index(0)
assert data_ptr.type.get_dwarf_type_kind() == DWARF_TYPE_CODE_PTR
return (length, data_ptr, capacity)
def extract_length_and_ptr_from_slice(slice_val):
assert (slice_val.type.get_type_kind() == TYPE_KIND_SLICE or
slice_val.type.get_type_kind() == TYPE_KIND_STR_SLICE)
length_field_index = SLICE_FIELD_NAMES.index(SLICE_FIELD_NAME_LENGTH)
ptr_field_index = SLICE_FIELD_NAMES.index(SLICE_FIELD_NAME_DATA_PTR)
length = slice_val.get_child_at_index(length_field_index).as_integer()
data_ptr = slice_val.get_child_at_index(ptr_field_index)
assert data_ptr.type.get_dwarf_type_kind() == DWARF_TYPE_CODE_PTR
return (length, data_ptr)