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Diffstat (limited to 'js/src/gdb/mozilla/prettyprinters.py')
| -rw-r--r-- | js/src/gdb/mozilla/prettyprinters.py | 368 |
1 files changed, 368 insertions, 0 deletions
diff --git a/js/src/gdb/mozilla/prettyprinters.py b/js/src/gdb/mozilla/prettyprinters.py new file mode 100644 index 000000000..87035d0ef --- /dev/null +++ b/js/src/gdb/mozilla/prettyprinters.py @@ -0,0 +1,368 @@ +# mozilla/prettyprinters.py --- infrastructure for SpiderMonkey's auto-loaded pretty-printers. + +import gdb +import re + +# Decorators for declaring pretty-printers. +# +# In each case, the decoratee should be a SpiderMonkey-style pretty-printer +# factory, taking both a gdb.Value instance and a TypeCache instance as +# arguments; see TypeCache, below. + +# Check that |fn| hasn't been registered as a pretty-printer under some +# other name already. (The 'enabled' flags used by GDB's +# 'enable/disable/info pretty-printer' commands are simply stored as +# properties of the function objects themselves, so a single function +# object can't carry the 'enabled' flags for two different printers.) +def check_for_reused_pretty_printer(fn): + if hasattr(fn, 'enabled'): + raise RuntimeError("pretty-printer function %r registered more than once" % fn) + +# a dictionary mapping gdb.Type tags to pretty-printer functions. +printers_by_tag = {} + +# A decorator: add the decoratee as a pretty-printer lookup function for types +# named |type_name|. +def pretty_printer(type_name): + def add(fn): + check_for_reused_pretty_printer(fn) + add_to_subprinter_list(fn, type_name) + printers_by_tag[type_name] = fn + return fn + return add + +# a dictionary mapping gdb.Type tags to pretty-printer functions for pointers to +# that type. +ptr_printers_by_tag = {} + +# A decorator: add the decoratee as a pretty-printer lookup function for +# pointers to types named |type_name|. +def ptr_pretty_printer(type_name): + def add(fn): + check_for_reused_pretty_printer(fn) + add_to_subprinter_list(fn, "ptr-to-" + type_name) + ptr_printers_by_tag[type_name] = fn + return fn + return add + +# a dictionary mapping gdb.Type tags to pretty-printer functions for +# references to that type. +ref_printers_by_tag = {} + +# A decorator: add the decoratee as a pretty-printer lookup function for +# references to instances of types named |type_name|. +def ref_pretty_printer(type_name): + def add(fn): + check_for_reused_pretty_printer(fn) + add_to_subprinter_list(fn, "ref-to-" + type_name) + ref_printers_by_tag[type_name] = fn + return fn + return add + +# a dictionary mapping the template name portion of gdb.Type tags to +# pretty-printer functions for instantiations of that template. +template_printers_by_tag = {} + +# A decorator: add the decoratee as a pretty-printer lookup function for +# instantiations of templates named |template_name|. +def template_pretty_printer(template_name): + def add(fn): + check_for_reused_pretty_printer(fn) + add_to_subprinter_list(fn, 'instantiations-of-' + template_name) + template_printers_by_tag[template_name] = fn + return fn + return add + +# A list of (REGEXP, PRINTER) pairs, such that if REGEXP (a RegexObject) +# matches the result of converting a gdb.Value's type to a string, then +# PRINTER is a pretty-printer lookup function that will probably like that +# value. +printers_by_regexp = [] + +# A decorator: add the decoratee as a pretty-printer factory for types +# that, when converted to a string, match |pattern|. Use |name| as the +# pretty-printer's name, when listing, enabling and disabling. +def pretty_printer_for_regexp(pattern, name): + compiled = re.compile(pattern) + def add(fn): + check_for_reused_pretty_printer(fn) + add_to_subprinter_list(fn, name) + printers_by_regexp.append((compiled, fn)) + return fn + return add + +# Forget all pretty-printer lookup functions defined in the module name +# |module_name|, if any exist. Use this at the top of each pretty-printer +# module like this: +# +# clear_module_printers(__name__) +def clear_module_printers(module_name): + global printers_by_tag, ptr_printers_by_tag, ref_printers_by_tag + global template_printers_by_tag, printers_by_regexp + + # Remove all pretty-printers defined in the module named |module_name| + # from d. + def clear_dictionary(d): + # Walk the dictionary, building a list of keys whose entries we + # should remove. (It's not safe to delete entries from a dictionary + # while we're iterating over it.) + to_delete = [] + for (k, v) in d.items(): + if v.__module__ == module_name: + to_delete.append(k) + remove_from_subprinter_list(v) + for k in to_delete: + del d[k] + + clear_dictionary(printers_by_tag) + clear_dictionary(ptr_printers_by_tag) + clear_dictionary(ref_printers_by_tag) + clear_dictionary(template_printers_by_tag) + + # Iterate over printers_by_regexp, deleting entries from the given module. + new_list = [] + for p in printers_by_regexp: + if p.__module__ == module_name: + remove_from_subprinter_list(p) + else: + new_list.append(p) + printers_by_regexp = new_list + +# Our subprinters array. The 'subprinters' attributes of all lookup +# functions returned by lookup_for_objfile point to this array instance, +# which we mutate as subprinters are added and removed. +subprinters = [] + +# Set up the 'name' and 'enabled' attributes on |subprinter|, and add it to our +# list of all SpiderMonkey subprinters. +def add_to_subprinter_list(subprinter, name): + subprinter.name = name + subprinter.enabled = True + subprinters.append(subprinter) + +# Remove |subprinter| from our list of all SpiderMonkey subprinters. +def remove_from_subprinter_list(subprinter): + subprinters.remove(subprinter) + +# An exception class meaning, "This objfile has no SpiderMonkey in it." +class NotSpiderMonkeyObjfileError(TypeError): + pass + +# TypeCache: a cache for frequently used information about an objfile. +# +# When a new SpiderMonkey objfile is loaded, we construct an instance of +# this class for it. Then, whenever we construct a pretty-printer for some +# gdb.Value, we also pass, as a second argument, the TypeCache for the +# objfile to which that value's type belongs. +# +# if objfile doesn't seem to have SpiderMonkey code in it, the constructor +# raises NotSpiderMonkeyObjfileError. +# +# Pretty-printer modules may add attributes to this to hold their own +# cached values. Such attributes should be named mod_NAME, where the module +# is named mozilla.NAME; for example, mozilla.JSString should store its +# metadata in the TypeCache's mod_JSString attribute. +class TypeCache(object): + def __init__(self, objfile): + self.objfile = objfile + + # Unfortunately, the Python interface doesn't allow us to specify + # the objfile in whose scope lookups should occur. But simply + # knowing that we need to lookup the types afresh is probably + # enough. + self.void_t = gdb.lookup_type('void') + self.void_ptr_t = self.void_t.pointer() + try: + self.JSString_ptr_t = gdb.lookup_type('JSString').pointer() + self.JSSymbol_ptr_t = gdb.lookup_type('JS::Symbol').pointer() + self.JSObject_ptr_t = gdb.lookup_type('JSObject').pointer() + except gdb.error: + raise NotSpiderMonkeyObjfileError + + self.mod_GCCellPtr = None + self.mod_Interpreter = None + self.mod_JSObject = None + self.mod_JSString = None + self.mod_jsval = None + self.mod_ExecutableAllocator = None + self.mod_IonGraph = None + +# Yield a series of all the types that |t| implements, by following typedefs +# and iterating over base classes. Specifically: +# - |t| itself is the first value yielded. +# - If we yield a typedef, we later yield its definition. +# - If we yield a type with base classes, we later yield those base classes. +# - If we yield a type with some base classes that are typedefs, +# we yield all the type's base classes before following the typedefs. +# (Actually, this never happens, because G++ doesn't preserve the typedefs in +# the DWARF.) +# +# This is a hokey attempt to order the implemented types by meaningfulness when +# pretty-printed. Perhaps it is entirely misguided, and we should actually +# collect all applicable pretty-printers, and then use some ordering on the +# pretty-printers themselves. +# +# We may yield a type more than once (say, if it appears more than once in the +# class hierarchy). +def implemented_types(t): + + # Yield all types that follow |t|. + def followers(t): + if t.code == gdb.TYPE_CODE_TYPEDEF: + yield t.target() + for t2 in followers(t.target()): yield t2 + elif t.code == gdb.TYPE_CODE_STRUCT: + base_classes = [] + for f in t.fields(): + if f.is_base_class: + yield f.type + base_classes.append(f.type) + for b in base_classes: + for t2 in followers(b): yield t2 + + yield t + for t2 in followers(t): yield t2 + +template_regexp = re.compile("([\w_:]+)<") + +# Construct and return a pretty-printer lookup function for objfile, or +# return None if the objfile doesn't contain SpiderMonkey code +# (specifically, definitions for SpiderMonkey types). +def lookup_for_objfile(objfile): + # Create a type cache for this objfile. + try: + cache = TypeCache(objfile) + except NotSpiderMonkeyObjfileError: + if gdb.parameter("verbose"): + gdb.write("objfile '%s' has no SpiderMonkey code; not registering pretty-printers\n" + % (objfile.filename,)) + return None + + # Return a pretty-printer for |value|, if we have one. This is the lookup + # function object we place in each gdb.Objfile's pretty-printers list, so it + # carries |name|, |enabled|, and |subprinters| attributes. + def lookup(value): + # If |table| has a pretty-printer for |tag|, apply it to |value|. + def check_table(table, tag): + if tag in table: + f = table[tag] + if f.enabled: + return f(value, cache) + return None + + def check_table_by_type_name(table, t): + if t.code == gdb.TYPE_CODE_TYPEDEF: + return check_table(table, str(t)) + elif t.code == gdb.TYPE_CODE_STRUCT and t.tag: + return check_table(table, t.tag) + else: + return None + + for t in implemented_types(value.type): + if t.code == gdb.TYPE_CODE_PTR: + for t2 in implemented_types(t.target()): + p = check_table_by_type_name(ptr_printers_by_tag, t2) + if p: return p + elif t.code == gdb.TYPE_CODE_REF: + for t2 in implemented_types(t.target()): + p = check_table_by_type_name(ref_printers_by_tag, t2) + if p: return p + else: + p = check_table_by_type_name(printers_by_tag, t) + if p: return p + if t.code == gdb.TYPE_CODE_STRUCT and t.tag: + m = template_regexp.match(t.tag) + if m: + p = check_table(template_printers_by_tag, m.group(1)) + if p: return p + + # Failing that, look for a printer in printers_by_regexp. We have + # to scan the whole list, so regexp printers should be used + # sparingly. + s = str(value.type) + for (r, f) in printers_by_regexp: + if f.enabled: + m = r.match(s) + if m: + p = f(value, cache) + if p: return p + + # No luck. + return None + + # Give |lookup| the attributes expected of a pretty-printer with + # subprinters, for enabling and disabling. + lookup.name = "SpiderMonkey" + lookup.enabled = True + lookup.subprinters = subprinters + + return lookup + +# A base class for pretty-printers for pointer values that handles null +# pointers, by declining to construct a pretty-printer for them at all. +# Derived classes may simply assume that self.value is non-null. +# +# To help share code, this class can also be used with reference types. +# +# This class provides the following methods, which subclasses are free to +# override: +# +# __init__(self, value, cache): Save value and cache as properties by those names +# on the instance. +# +# to_string(self): format the type's name and address, as GDB would, and then +# call a 'summary' method (which the subclass must define) to produce a +# description of the referent. +# +# Note that pretty-printers returning a 'string' display hint must not use +# this default 'to_string' method, as GDB will take everything it returns, +# including the type name and address, as string contents. +class Pointer(object): + def __new__(cls, value, cache): + # Don't try to provide pretty-printers for NULL pointers. + if value.type.strip_typedefs().code == gdb.TYPE_CODE_PTR and value == 0: + return None + return super(Pointer, cls).__new__(cls) + + def __init__(self, value, cache): + self.value = value + self.cache = cache + + def to_string(self): + # See comment above. + assert not hasattr(self, 'display_hint') or self.display_hint() != 'string' + concrete_type = self.value.type.strip_typedefs() + if concrete_type.code == gdb.TYPE_CODE_PTR: + address = self.value.cast(self.cache.void_ptr_t) + elif concrete_type.code == gdb.TYPE_CODE_REF: + address = '@' + str(self.value.address.cast(self.cache.void_ptr_t)) + else: + assert not "mozilla.prettyprinters.Pointer applied to bad value type" + try: + summary = self.summary() + except gdb.MemoryError as r: + summary = str(r) + v = '(%s) %s %s' % (self.value.type, address, summary) + return v + + def summary(self): + raise NotImplementedError + +field_enum_value = None + +# Given |t|, a gdb.Type instance representing an enum type, return the +# numeric value of the enum value named |name|. +# +# Pre-2012-4-18 versions of GDB store the value of an enum member on the +# gdb.Field's 'bitpos' attribute; later versions store it on the 'enumval' +# attribute. This function retrieves the value from either. +def enum_value(t, name): + global field_enum_value + f = t[name] + # Monkey-patching is a-okay in polyfills! Just because. + if not field_enum_value: + if hasattr(f, 'enumval'): + field_enum_value = lambda f: f.enumval + else: + field_enum_value = lambda f: f.bitpos + return field_enum_value(f) |