1 files changed, 49 insertions, 0 deletions
diff --git a/js/src/gdb/mozilla/GCCellPtr.py b/js/src/gdb/mozilla/GCCellPtr.py
new file mode 100644
index 000000000..87dcf73da
--- /dev/null
+++ b/js/src/gdb/mozilla/GCCellPtr.py
@@ -0,0 +1,49 @@
+# Pretty-printers for GCCellPtr values.
+
+import gdb
+import mozilla.prettyprinters
+
+from mozilla.prettyprinters import pretty_printer
+
+# Forget any printers from previous loads of this module.
+mozilla.prettyprinters.clear_module_printers(__name__)
+
+# Cache information about the JS::TraceKind type for this objfile.
+class GCCellPtrTypeCache(object):
+    def __init__(self, cache):
+        self.TraceKind_t = gdb.lookup_type('JS::TraceKind')
+
+        # Build a mapping from TraceKind enum values to the types they denote.
+        e = gdb.types.make_enum_dict(self.TraceKind_t)
+        kind_to_type = {}
+        def kind(k, t):
+            kind_to_type[e['JS::TraceKind::' + k]] = gdb.lookup_type(t)
+        kind('Object',      'JSObject')
+        kind('String',      'JSString')
+        kind('Symbol',      'JS::Symbol')
+        kind('Script',      'JSScript')
+        kind('Shape',       'js::Shape')
+        kind('ObjectGroup', 'js::ObjectGroup')
+        kind('BaseShape',   'js::BaseShape')
+        kind('JitCode',     'js::jit::JitCode')
+        kind('LazyScript',  'js::LazyScript')
+        self.kind_to_type = kind_to_type
+
+        self.Null = e['JS::TraceKind::Null']
+        self.mask = gdb.parse_and_eval('JS::OutOfLineTraceKindMask')
+
+@pretty_printer('JS::GCCellPtr')
+class GCCellPtr(object):
+    def __init__(self, value, cache):
+        self.value = value
+        if not cache.mod_GCCellPtr:
+            cache.mod_GCCellPtr = GCCellPtrTypeCache(cache)
+        self.cache = cache
+
+    def to_string(self):
+        ptr = self.value['ptr']
+        kind = ptr & self.cache.mod_GCCellPtr.mask
+        if kind == self.cache.mod_GCCellPtr.Null:
+            return "JS::GCCellPtr(nullptr)"
+        tipe = self.cache.mod_GCCellPtr.kind_to_type[int(kind)]
+        return "JS::GCCellPtr(({}*) {})".format(tipe, ptr.cast(self.cache.void_ptr_t))