Bug 256425 - kcachegrind looses track of callers-callees, duplicating entries. (xdebug php profile)
Summary: kcachegrind looses track of callers-callees, duplicating entries. (xdebug php...
Status: RESOLVED NOT A BUG
Alias: None
Product: kcachegrind
Classification: Developer tools
Component: general (show other bugs)
Version: unspecified
Platform: Compiled Sources Linux
: NOR normal
Target Milestone: ---
Assignee: Josef Weidendorfer
URL:
Keywords:
: 265886 (view as bug list)
Depends on:
Blocks:
 
Reported: 2010-11-09 10:25 UTC by jay
Modified: 2011-03-22 11:26 UTC (History)
3 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
{main} selected (113.45 KB, image/png)
2010-11-09 10:25 UTC, jay
Details
Double clicked first callee (110.20 KB, image/png)
2010-11-09 10:26 UTC, jay
Details
twin without callers (112.27 KB, image/png)
2010-11-09 10:27 UTC, jay
Details
tested cachegrind file (73.23 KB, application/zip)
2010-11-09 10:28 UTC, jay
Details

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Description jay 2010-11-09 10:25:19 UTC
Created attachment 53267 [details]
{main} selected

Version:           unspecified (using KDE 4.5.1) 
OS:                Linux

Normaly (kcachegrind 0.5.1) I can follow application flow from {main} by going thru callees or source code.

In 0.6, clicking on a callee switches to one, without child callees.
Twin of it in left list, has Callees but no Callers.

Images attached tell more than text.

Reproducible: Always

Steps to Reproduce:
Open cachegrind file generated by xdebug (php).



kubuntu maverick.

Happens on system version and compiled version.
Happens also on ubuntu lucid with kde 4.5 from ppa.
Comment 1 jay 2010-11-09 10:26:43 UTC
Created attachment 53268 [details]
Double clicked first callee
Comment 2 jay 2010-11-09 10:27:25 UTC
Created attachment 53269 [details]
twin without callers
Comment 3 jay 2010-11-09 10:28:35 UTC
Created attachment 53270 [details]
tested cachegrind file
Comment 5 Josef Weidendorfer 2010-11-09 19:06:44 UTC
Thanks for the analysis.

Actually, the supplied cachegrind file seems buggy to me.
It only specifies the source file name for functions, but
not for call targets.

If you look up the format specification at
 http://kcachegrind.sourceforge.net/html/CallgrindFormat.html
in the example of chapter 1.4 (extended example),
you see something like
 ...
 cfl=file2.c
 cfn=func2
 calls=3 20
 16 400
 ...
which specifies a call to func2, which is defined in line 16 of
source file "file2.c".

In your file (supposedly written by xdebug), the are no lines
at all beginning with "cfl=", so actually, all calls target
functions with unknown source. Previously, functions with same
name but in different source files were merged, which made it
look like that the xdebug output is fine. But actually, this
merge behavior is broken because at least in C, you can define
distinct functions with the same name in different files, if
the definitions are "static" (ie. scope is file-local).

So, this should be a bug report for xdebug. I do not really
see a way to both have to old broken and the new correct
behavior.
Comment 6 jay 2010-11-10 09:55:33 UTC
thanks

http://bugs.xdebug.org/view.php?id=639
Comment 7 Josef Weidendorfer 2011-02-10 03:07:51 UTC
*** Bug 265886 has been marked as a duplicate of this bug. ***
Comment 8 jay 2011-02-10 09:23:20 UTC
xdebug bug is not moving.

Would it please be possible, at least, put a switch into settings, which behaviour to use ? - "correct new" :: "incorrect old - for xdebug"
Comment 9 Sebastian Bergmann 2011-02-10 13:28:01 UTC
(In reply to comment #8)
> xdebug bug is not moving.

I am discussing the issue with Derick Rethans at the moment. I am sure that it will "move" soon.
Comment 10 Josef Weidendorfer 2011-02-11 14:08:38 UTC
(In reply to comment #9)
> I am discussing the issue with Derick Rethans at the moment. I am sure that it
> will "move" soon.

Great! It was my suggestion to push xdebug about this.
I will add a paragraph to the Callgrind format specification about this.

(In reply to comment #8)
> Would it please be possible, at least, put a switch into settings,
> which behaviour to use ? - "correct new" :: "incorrect old - for xdebug"

As I said in a duplicate of this bug, it even should be possible to detect
xdebug output when seeing "version: 0.9.7". I am not sure what "0.9.7" here
should be, but it is definitely wrong. The field is supposed to provide
the version of the Callgrind format used in the file, and up to now, only
version "1" is valid. Can this issue be forwarded to the xdebug guys, also?
It would be very good to add a creator string, however. This can include
version information, e.g. "creator: xdebug 0.9.7", and would allow to easier
add workarounds for specific if needed.

If I find time, I can add the workaround via detection of "version: 0.9.7".
Neverless, this should be corrected in xdebug, also.
Comment 11 Sebastian Bergmann 2011-02-11 14:20:08 UTC
(In reply to comment #10)
> As I said in a duplicate of this bug, it even should be possible to detect
> xdebug output when seeing "version: 0.9.7". I am not sure what "0.9.7" here
> should be, but it is definitely wrong. The field is supposed to provide
> the version of the Callgrind format used in the file, and up to now, only
> version "1" is valid. Can this issue be forwarded to the xdebug guys, also?
> It would be very good to add a creator string, however. This can include
> version information, e.g. "creator: xdebug 0.9.7", and would allow to easier
> add workarounds for specific if needed.
> 
> If I find time, I can add the workaround via detection of "version: 0.9.7".
> Neverless, this should be corrected in xdebug, also.

Forwarded to Xdebug developer.
Comment 12 Francois Mazerolle 2011-02-14 20:28:10 UTC
I'm not sure if you need additional informations but I've some screenshots that might help:
http://img46.imageshack.us/img46/2226/kcachegrind123.png

Notice the location: (unknown)
Comment 13 Josef Weidendorfer 2011-02-15 17:10:10 UTC
(In reply to comment #12)
> Notice the location: (unknown)

Yes. That is the effect of Xdebug output not having any
lines starting with "cfl=", which would specify the source
location of a call target (see comment #5).

As I said, this is a misuse of too relaxed merging of symbols
in previous versions of KCachegrind. Making this more strict, which
actually fixed a real bug with Callgrind/C code (I will not revert
that fix for Xdebug), made this wrong Xdebug output to have this
visible side effect.
Comment 14 Derick Rethans 2011-03-22 10:42:10 UTC
Hi!

For your information, this is now fixed in Xdebug's SVN (and ready to go into 2.1.1).

cheers,
Derick
Comment 15 Josef Weidendorfer 2011-03-22 11:26:32 UTC
Cool, thanks!