1100335 - JS debug helper functions should use OutputDebugString on Windows

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[(not currently active) Ted Mielczarek]

The JS engine has some handy debug helpers like js_DumpAtom and js_DumpBacktrace. Unfortunately these seem to always dump to stdout or stderr, which can be hard or impossible to find when debugging a Windows opt build (like a nightly or release).

We should make these functions call OutputDebugString on Windows, since they're intended for use under a debugger anyway.

Comment 1

[(not currently active) Ted Mielczarek]

Attachment: Use OutputDebugString on Windows in js_DumpBacktrace

This fixes js_DumpBacktrace because that was easy and it's the thing I usually want when I'm poking at my Nightly in a debugger and the C++ stack shows we're executing JS. The other debugging methods could be similarly fixed, but right now they contain a bunch of fprintfs and I didn't feel like rewriting them all. They could use the Sprinter class that js_DumpBacktrace does, or some other abstraction.

Comment 2

[(not currently active) Ted Mielczarek]

Attachment: Use OutputDebugString on Windows in js_DumpBacktrace

Posted the outdated broken version of my patch (like a boss). Here's the working one.

Comment 3

[Jason Orendorff [:jorendorff]]

Comment on attachment 8540721 [details] [diff] [review]
Use OutputDebugString on Windows in js_DumpBacktrace

Review of attachment 8540721 [details] [diff] [review]:
-----------------------------------------------------------------

OK.

Comment 4

[(not currently active) Ted Mielczarek]

https://hg.mozilla.org/integration/mozilla-inbound/rev/dffb39f03222

Comment 5

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/dffb39f03222

Comment 6

[Yuan Pengfei]

Comment on attachment 8540721 [details] [diff] [review]
Use OutputDebugString on Windows in js_DumpBacktrace

Review of attachment 8540721 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/jsobj.cpp
@@ +4033,5 @@
> +#ifdef XP_WIN32
> +    if (IsDebuggerPresent()) {
> +        OutputDebugStringA(sprinter.string());
> +    }
> +#endif

Missing:
#ifdef XP_WIN
#include <windows.h>
#endif

Comment 7

[David Teller [:Yoric] - still alive but not very active]

Fwiw, filed bug 1399777 as a followup.