1 files changed, 60 insertions, 0 deletions
diff --git a/js/src/gdb/mozilla/jsop.py b/js/src/gdb/mozilla/jsop.py
new file mode 100644
index 0000000000..635acb7528
--- /dev/null
+++ b/js/src/gdb/mozilla/jsop.py
@@ -0,0 +1,60 @@
+# 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 JSOp and jsbytecode values.
+
+import gdb
+import gdb.types
+
+import mozilla.prettyprinters
+from mozilla.prettyprinters import pretty_printer, ptr_pretty_printer
+
+# Forget any printers from previous loads of this module.
+mozilla.prettyprinters.clear_module_printers(__name__)
+
+
+class JSOpTypeCache(object):
+    # Cache information about the JSOp type for this objfile.
+    def __init__(self, cache):
+        self.tJSOp = gdb.lookup_type("JSOp")
+
+    @classmethod
+    def get_or_create(cls, cache):
+        if not cache.mod_JSOp:
+            cache.mod_JSOp = cls(cache)
+        return cache.mod_JSOp
+
+
+@pretty_printer("JSOp")
+class JSOp(object):
+    def __init__(self, value, cache):
+        self.value = value
+        self.cache = cache
+        self.jotc = JSOpTypeCache.get_or_create(cache)
+
+    def to_string(self):
+        # JSOp's storage type is |uint8_t|, but gdb uses a signed value.
+        # Manually convert it to an unsigned value.
+        #
+        # https://sourceware.org/bugzilla/show_bug.cgi?id=25325
+        idx = int(self.value.cast(self.jotc.tJSOp.target()))
+        assert 0 <= idx and idx <= 255
+        fields = self.jotc.tJSOp.fields()
+        if idx < len(fields):
+            return fields[idx].name
+        return "(JSOp) {:d}".format(idx)
+
+
+@ptr_pretty_printer("jsbytecode")
+class JSBytecodePtr(mozilla.prettyprinters.Pointer):
+    def __init__(self, value, cache):
+        super(JSBytecodePtr, self).__init__(value, cache)
+        self.jotc = JSOpTypeCache.get_or_create(cache)
+
+    def to_string(self):
+        try:
+            opcode = str(self.value.dereference().cast(self.jotc.tJSOp))
+        except Exception:
+            opcode = "bad pc"
+        return "{} ({})".format(self.value.cast(self.cache.void_ptr_t), opcode)