449467 - Expose jsdIScript byte codes

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, enhancement)

Description

[John J. Barton]

As far as I know there is no way to print the byte code or other representation of the compiled Javascript matching a jsdIScript. Mostly this is a good thing, but some Firebug bugs are stuck because I can't tell what the method really should be doing.  For example, 
http://code.google.com/p/fbug/issues/detail?id=1008
is an example of a function that Firebug causes wrong execution when it single steps through the function. Why? I really don't have a way to work on this.  If I could look at the byte codes and the pc while single stepping may be I could get some hints.

Comment 1

[:Gijs (out for now; he/him)]

Moving to JSD, but it might be JS Engine. Talk to people who know more than me.

Comment 2

[timeless]

John: you can use windbg, http://developer.mozilla.org/en/How_to_get_a_stacktrace_with_WinDbg to examine the bytecode.

While it's theoretically possible to expose this, I'm not in a hurry to do so. Especially given that the bytecode is not guaranteed to mean anything and given that I don't know how JIT affects this.

Comment 3

[John J. Barton]

Apparently there is a program that gives the byte codes, see for example https://bugzilla.mozilla.org/show_bug.cgi?id=533298#c3

Comment 4

[John J. Barton]

See also Bug 533874 -  Implement ast_uneval()/eval_to_ast()

Comment 5

[David Mandelin [:dmandelin]]

I'm not aware of any current demand for a feature like this.