# Copyright 2023 the V8 project authors. All rights reserved. # Use of this source code is governed by a BSD-style license that can be # found in the LICENSE file. # Load this file by adding this to your ~/.lldbinit or your launch.json: # command script import /lldb_visualizers.py # for py2/py3 compatibility from __future__ import print_function import collections import functools import re import traceback import lldb ###################### # custom visualizers # ###################### def lazy_unsigned_expression(expr): sb_value = None uint_value = 0 def getter(fromValue): nonlocal sb_value nonlocal uint_value if sb_value is None: sb_value = fromValue.CreateValueFromExpression(expr, expr) uint_value = sb_value.GetValueAsUnsigned() return uint_value return getter def lazy_unsigned_constant(name): return lazy_unsigned_expression('v8::internal::' + name) # Values to only evaluate once FrameSummary_Kind_JAVA_SCRIPT = lazy_unsigned_constant( 'FrameSummary::Kind::JAVA_SCRIPT') def field_from_address(parent_value, offset_getter, name, typename=None): addr = parent_value.GetValueAsUnsigned() try: tag_mask = kHeapObjectTagMask(parent_value) if (addr & tag_mask) == kHeapObjectTag(parent_value): heap_base = V8HeapCompressionScheme_base_(parent_value) if (addr & ~(kPtrComprCageBaseAlignment(parent_value) - 1)) == heap_base: field_address = (addr & ~tag_mask) + offset_getter(parent_value) if typename is None: return parent_value.CreateValueFromExpression( name, '(%s | (unsigned long)(*(int*)(%s)))' % (heap_base, field_address)) else: return parent_value.CreateValueFromExpression( name, '*(%s *)%s' % (typename, field_address)) except: print(traceback.format_exc()) return None class DictProvider: updating_for_formatter = False def __init__(self): self.children = None self.name_to_index = None self.update_only_for_formatter = False def populate_children(self, mapping): raise "Not implemented" def update(self): if self.update_only_for_formatter and not DictProvider.updating_for_formatter: return if DictProvider.updating_for_formatter: # in the future, only update when updating for formatter self.update_only_for_formatter = True # update only once DictProvider.updating_for_formatter = False self.children = None self.name_to_index = None def ensure_populated(self): if self.children is None: try: new_dict = collections.OrderedDict() self.populate_children(new_dict) self.children = list(new_dict.values()) self.name_to_index = {k: v for (v, k) in enumerate(new_dict.keys())} except: print(traceback.format_exc()) def num_children(self): self.ensure_populated() return len(self.children) def has_children(self): return True def get_child_index(self, name): self.ensure_populated() return self.name_to_index.get(name, None) def get_child_at_index(self, index): self.ensure_populated() return self.children[index]() # Parse printed properties. May be a named property (rendered like " - name: val") # or a list index (rendered like " 0: val"). If line ends with '{', it is a # multiline property expected to continue until a line ends with '}'. CHILD_RE = re.compile( r'((?<=^ - )[^:]+|(?<=\n ) *[0-9]+): (.*(?:[^\{]|\{\n(?:.*\n)+.*\}))$', re.MULTILINE) # Parse an address out of a value, so we can create an object that can be further # expanded. Note that some things like Oddballs aren't worth trying to expand. ADDRESS_RE = re.compile( r'^(?:\[[^\]]+\] )?(0x[0-9a-fA-F]{8,16})(?: (?!\[(?:Oddball|String)\]|\<(?:Symbol:|Code BUILTIN) .+\>).*)?$' ) NUMERIC_RE = re.compile(r'^-?[0-9\.]+([eE][+\-]?[0-9]+)?$') PROPERTY_RE = re.compile(r' (0x(?:[^:]|:(?! 0x))+): (.+)$') OBJECT_DUMP_NAME = '[Dump]' def make_string(parent, pystring, name): # Planning on python string representations being valid C/C++ # However, python repr usually gives single quoted reprs and we need double quotes converted = '"%s"' % repr(pystring)[1:-1].replace('"', '\\"') return parent.CreateValueFromExpression(name, converted) def get_string_value(valobj): # Count on existing std::string visualizer to give us a summary so we don't # need to do valobj.__r_.__value_.__l.__data_ summary = valobj.GetSummary() if summary and len(summary) >= 2 and summary[0] == '"' and summary[-1] == '"': # Also count on the std::string summary being a valid python string # representation. return eval(summary) return None def make_synthetic_field(parent, summary, name): m = ADDRESS_RE.match(summary) if m: return parent.CreateValueFromExpression( name, '_v8_internal_Get_Object((void *)%s)' % m.group(1)) elif NUMERIC_RE.match(summary): return parent.CreateValueFromExpression(name, summary) else: # Fallback to creating a C string of the dumped text return make_string(parent, summary, name) class HeapObjectChildrenProvider(DictProvider): def __init__(self, valobj, internal_dict): self.valueobject = valobj super().__init__() def populate_children(self, mapping): expression = ('_v8_internal_Print_Object_To_String((void *)%s)' % self.valueobject.GetValueAsUnsigned()) dump = self.valueobject.CreateValueFromExpression(OBJECT_DUMP_NAME, expression) stringdump = get_string_value(dump) if stringdump: for (name, val) in CHILD_RE.findall(stringdump): if val.startswith('{\n') and val.endswith('\n }') and name.find( 'properties') >= 0: for index, line in enumerate(val.splitlines()[1:-1]): m = PROPERTY_RE.match(line) if m: mapping[m.group(1)] = functools.partial(make_synthetic_field, self.valueobject, m.group(2), m.group(1)) else: mapping[name] = functools.partial(make_synthetic_field, self.valueobject, val, name) mapping[OBJECT_DUMP_NAME] = lambda: dump def summarize_heap_object_internal(valueobject, inner_getter): # By indicating that this synthentic child provider is called from an object # with a formatter, we can ensure it is updated only when that formatter is # called, preventing it from being reevaluated multiple times on a single step DictProvider.updating_for_formatter = True dumpobj = valueobject.GetChildMemberWithName(OBJECT_DUMP_NAME) DictProvider.updating_for_formatter = False if dumpobj and dumpobj.GetError().Success(): dump = get_string_value(dumpobj) if dump: oneline = dump.splitlines()[0] if oneline: return oneline return '%s: Address=0x%x' % (valueobject.GetDisplayTypeName(), inner_getter().GetValueAsUnsigned()) class HandleChildrenProvider(HeapObjectChildrenProvider): def __init__(self, valobj, internal_dict): super().__init__( valobj.GetChildMemberWithName('location_').Dereference(), internal_dict) def summarize_handle(valueobject, unused_dict): return summarize_heap_object_internal( valueobject, lambda: valueobject.GetNonSyntheticValue(). GetChildMemberWithName('location_').Dereference()) class TaggedChildrenProvider(HeapObjectChildrenProvider): def __init__(self, valobj, internal_dict): super().__init__(valobj.GetChildMemberWithName('ptr_'), internal_dict) def summarize_tagged(valueobject, unused_dict): return summarize_heap_object_internal( valueobject, lambda: valueobject.GetNonSyntheticValue().GetChildMemberWithName('ptr_')) def read_pointer(ptrobject): if not ptrobject.TypeIsPointerType(): ptrobject = ptrobject.AddressOf() ptr = ptrobject.GetValueAsUnsigned() # If it's not 8 byte aligned, assume it's uninitialized and return 0 instead. # Could we do more validation? if (ptr & 7) == 0: return ptr return 0 def summarize_stack_frame(valueobject, unused_dict): ptr = read_pointer(valueobject) if ptr: typeval = valueobject.CreateValueFromExpression( '[Type]', '((v8::internal::StackFrame *)%s)->type()' % ptr) return 'StackFrame: %s' % typeval.GetValue() # Is it worth getting more here? def summarize_stack_trace_debug_details(valueobject, unused_dict): summary = get_string_value(valueobject.GetChildMemberWithName('summary')) frametype = valueobject.GetChildMemberWithName('type').GetValue() firstline, _, _ = summary.partition('\n') _, _, result = firstline.partition(':') return frametype + result class IsolateChildrenProvider(DictProvider): def __init__(self, valobj, internal_dict): self.valueobject = valobj super().__init__() def populate_children(self, mapping): ptr = read_pointer(self.valueobject) if ptr: mapping[ '[Stack Trace]'] = lambda: self.valueobject.CreateValueFromExpression( '[Stack Trace]', '_v8_internal_Expand_StackTrace((v8::internal::Isolate *)%s)' % ptr) class FrameSummaryChildrenProvider(DictProvider): def __init__(self, valobj, internal_dict): self.valueobject = valobj super().__init__() def populate_children(self, mapping): unionelement = 'base_' kind = self.valueobject.GetChildMemberWithName( unionelement).GetChildMemberWithName('kind_').GetValueAsUnsigned() if kind == FrameSummary_Kind_JAVA_SCRIPT(self.valueobject): unionelement = 'java_script_summary_' # TODO: Add other summary kinds mapping[unionelement] = lambda: self.valueobject.GetChildMemberWithName( unionelement) def __lldb_init_module(debugger, unused_dict): debugger.HandleCommand( 'type summary add -p --summary-string "Address=0x${var%x}" v8::internal::Address' ) debugger.HandleCommand( 'type synthetic add -p -l lldb_visualizers.HandleChildrenProvider -x "^v8::internal::Handle<"' ) debugger.HandleCommand( 'type synthetic add -p -l lldb_visualizers.TaggedChildrenProvider -x "^v8::internal::Tagged<"' ) debugger.HandleCommand( 'type summary add -p -F lldb_visualizers.summarize_handle -x "^v8::internal::Handle<"' ) debugger.HandleCommand( 'type summary add -p -F lldb_visualizers.summarize_tagged -x "^v8::internal::Tagged<"' ) debugger.HandleCommand( 'type summary add -F lldb_visualizers.summarize_stack_frame v8::internal::StackFrame' ) debugger.HandleCommand( 'type summary add -F lldb_visualizers.summarize_stack_trace_debug_details _v8_internal_debugonly::StackTraceDebugDetails' ) debugger.HandleCommand( 'type synthetic add -l lldb_visualizers.IsolateChildrenProvider v8::internal::Isolate' ) debugger.HandleCommand( 'type synthetic add -l lldb_visualizers.FrameSummaryChildrenProvider v8::internal::FrameSummary' )