1 files changed, 118 insertions, 0 deletions
diff --git a/js/src/gdb/mozilla/JSObject.py b/js/src/gdb/mozilla/JSObject.py
new file mode 100644
index 0000000000..006f93a897
--- /dev/null
+++ b/js/src/gdb/mozilla/JSObject.py
@@ -0,0 +1,118 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Pretty-printers for SpiderMonkey JSObjects.
+
+import re
+
+import gdb
+import mozilla.prettyprinters as prettyprinters
+from mozilla.CellHeader import get_header_ptr
+from mozilla.jsval import JSValue
+from mozilla.prettyprinters import ptr_pretty_printer, ref_pretty_printer
+
+prettyprinters.clear_module_printers(__name__)
+
+
+class JSObjectTypeCache(object):
+    def __init__(self):
+        object_flag = gdb.lookup_type("js::ObjectFlag")
+        self.objectflag_IsUsedAsPrototype = prettyprinters.enum_value(
+            object_flag, "js::ObjectFlag::IsUsedAsPrototype"
+        )
+        self.value_ptr_t = gdb.lookup_type("JS::Value").pointer()
+        self.func_ptr_t = gdb.lookup_type("JSFunction").pointer()
+        self.class_NON_NATIVE = gdb.parse_and_eval("JSClass::NON_NATIVE")
+        self.BaseShape_ptr_t = gdb.lookup_type("js::BaseShape").pointer()
+        self.Shape_ptr_t = gdb.lookup_type("js::Shape").pointer()
+        self.JSClass_ptr_t = gdb.lookup_type("JSClass").pointer()
+        self.JSScript_ptr_t = gdb.lookup_type("JSScript").pointer()
+        self.JSFunction_AtomSlot = gdb.parse_and_eval("JSFunction::AtomSlot")
+        self.JSFunction_NativeJitInfoOrInterpretedScriptSlot = gdb.parse_and_eval(
+            "JSFunction::NativeJitInfoOrInterpretedScriptSlot"
+        )
+
+
+# There should be no need to register this for JSFunction as well, since we
+# search for pretty-printers under the names of base classes, and
+# JSFunction has JSObject as a base class.
+
+
+gdb_string_regexp = re.compile(r'(?:0x[0-9a-z]+ )?(?:<.*> )?"(.*)"', re.I)
+
+
+@ptr_pretty_printer("JSObject")
+class JSObjectPtrOrRef(prettyprinters.Pointer):
+    def __init__(self, value, cache):
+        super(JSObjectPtrOrRef, self).__init__(value, cache)
+        if not cache.mod_JSObject:
+            cache.mod_JSObject = JSObjectTypeCache()
+        self.otc = cache.mod_JSObject
+
+    def summary(self):
+        shape = get_header_ptr(self.value, self.otc.Shape_ptr_t)
+        baseshape = get_header_ptr(shape, self.otc.BaseShape_ptr_t)
+        classp = get_header_ptr(baseshape, self.otc.JSClass_ptr_t)
+        non_native = classp["flags"] & self.otc.class_NON_NATIVE
+
+        # Use GDB to format the class name, but then strip off the address
+        # and the quotes.
+        class_name = str(classp["name"])
+        m = gdb_string_regexp.match(class_name)
+        if m:
+            class_name = m.group(1)
+
+        if non_native:
+            return "[object {}]".format(class_name)
+        else:
+            flags = shape["objectFlags_"]["flags_"]
+            used_as_prototype = bool(flags & self.otc.objectflag_IsUsedAsPrototype)
+            name = None
+            if class_name == "Function":
+                function = self.value
+                concrete_type = function.type.strip_typedefs()
+                if concrete_type.code == gdb.TYPE_CODE_REF:
+                    function = function.address
+                name = get_function_name(function, self.cache)
+            return "[object {}{}]{}".format(
+                class_name,
+                " " + name if name else "",
+                " used_as_prototype" if used_as_prototype else "",
+            )
+
+
+def get_function_name(function, cache):
+    if not cache.mod_JSObject:
+        cache.mod_JSObject = JSObjectTypeCache()
+    otc = cache.mod_JSObject
+
+    function = function.cast(otc.func_ptr_t)
+    fixed_slots = (function + 1).cast(otc.value_ptr_t)
+    atom_value = JSValue(fixed_slots[otc.JSFunction_AtomSlot], cache)
+
+    if atom_value.is_undefined():
+        return "<unnamed>"
+
+    return str(atom_value.get_string())
+
+
+def get_function_script(function, cache):
+    if not cache.mod_JSObject:
+        cache.mod_JSObject = JSObjectTypeCache()
+    otc = cache.mod_JSObject
+
+    function = function.cast(otc.func_ptr_t)
+    fixed_slots = (function + 1).cast(otc.value_ptr_t)
+    slot = otc.JSFunction_NativeJitInfoOrInterpretedScriptSlot
+    script_value = JSValue(fixed_slots[slot], cache)
+
+    if script_value.is_undefined():
+        return 0
+
+    return script_value.get_private()
+
+
+@ref_pretty_printer("JSObject")
+def JSObjectRef(value, cache):
+    return JSObjectPtrOrRef(value, cache)