cocos2d for iPhone

A fast, easy to use, free, and community supported 2D game engine

1. 

   redsky
   Member

   i did a search and didn't find any posts on this topic so i thought i would share an experience to help other newbie.

   i'm sure these types of tools are old news to long time developers. however, being a newbie this was new territory for me.

   for those who dont know, a static analysis tool examines your code at a deeper level than the compiler typically can. it is capable of finding, leaks, usages of objects after they've been released, and a lot more. in my example, not only did it tell me where it was leaking but why.

   i finally looked into this tool after my retain count was increasing every single draw cycle (oops!). i had read the rules of objective-c memory management but clearly i was still missing something. the static analysis tool found the leak i was looking for plus a few more that i didn't even know were problems (yet).

   it generates a pretty html report that can open automatically with links to each suspected defect. on a minor downside, it can detect false positives.

   i was stuck for days on this issue and now i can go to sleep a happy dude :)

   here is the tool i used: http://clang-analyzer.llvm.org/

   i apologize if this sounds like a commercial. i am just very relieved to put a very frustrating issue behind me. now I can resume work on my tower defense game :)

   * edit - oh yeah, its free. so you really have no excuse to run it before you submit your game to the app store!

   Posted 2 years ago #
2. 

   shivaz
   Member

   Fun if you can get it to work. I used the info here:
   http://www.fruitstandsoftware.com/blog/index.php/2008/08/finding-memory-leaks-with-the-llvmclang-static-analyzer/

   Especially Brian's comment. I created a copy of the debug config set not to code sign and set as default commandline config.

   Using: scan-build -k -V xcodebuild -sdk iphonesimulator3.0
   Works for me.

   Except that it doesn't check any of my .mm files - so basically doesn't check any of my files. Just the cocos2d stuff :D

   Justin

   Posted 2 years ago #
3. 

   jd
   Member

   I just ran it. It found issues in the cocos2d code - almost all CocosDenshion. One bug was my code. Did anybody else get cocos2d leaks in 8.1?
   

   All Bugs	27
   Dead store
   Dead assignment	3
   Dead initialization	3
   Dead nested assignment	8	
   
   Logic errors
   Null dereference	3
   Memory (Core Foundation/Objective-C)
   Bad release	1
   Leak	1
   Leak of returned object	7
   Method should return an owned object	1

   Posted 2 years ago #
4. 

   shivaz
   Member

   My results. Same about the CocosDenshion. I am not quite up to the latest version of Cocos2d yet.

   All Bugs 18
   Dead store
   Dead assignment 3
   Dead initialization 3
   Logic errors
   Null dereference 3
   Memory (Core Foundation/Objective-C)
   Bad release 1
   Leak 1
   Leak of returned object 7

   Posted 2 years ago #
5. 

   Codemattic
   Moderator

   Here is an ars technica explanation (as part of a bigger article on Snow Leopard) re Clang and LLVM which I found very interesting:

   http://arstechnica.com/apple/reviews/2009/08/mac-os-x-10-6.ars/9

   Posted 2 years ago #
6. 

   ob1
   Member

   Nice stuff.

   Does any one know if we can easily compile our iPhone games with Clang and if there is any performance increase ?

   Posted 2 years ago #
7. 

   redsky
   Member

   I noticed the errors with CocosDenshion as well, but I didn't want to come in here saying "look at all the errors!". I don't know enough about the codebase to know if they are false positives or not.

   I was using 0.8.1.

   Posted 2 years ago #
8. 

   jd
   Member

   @redsky I definitely am not finger pointing, I was just pointing out and hoping somebody would tell me it's OK or I have old code or something. In fact, I believe riq uses the same tool to compile the the trunk so I think he would have seen these by now.

   Posted 2 years ago #
9. 

   redsky
   Member

   I wasn't implying that anyone was finger pointing, sorry if i came off that way. just wanted to mention that i saw the same results as others.

   on an unrelated note, how do you guys set your avatar graphic. i don't see anywhere to do that.

   Posted 2 years ago #
10. 

    tjweir
    Member

    @redsky - gravatar.com

    Posted 2 years ago #
11. 

    jd
    Member

    It's cool redsky. I should have phrased my post better because it probably came off that way a little.

    Posted 2 years ago #
12. 

    Steve Oldmeadow
    Administrator

    Use of clang is standard operating procedure for cocos2d.

    http://www.cocos2d-iphone.org/wiki/doku.php/developers:how_to_release

    I fixed two "issues" with CocosDenshion. A memory leak and a null pointer reference. If both ever occurred your program would have been fubar anyway.

    For the rest of the CocosDenshion issues I see no problem with them. The dead nested assignment code is straight from Apple and the dead assignments I keep so I can debug a return value if I need to. Then there are a bunch of leaks reported where clang doesn't seem to understand how singletons are being handled. I'm no Objective C expert though, so if someone can give me a valid reason why the code should be changed I'll do it.

    @codemattic - thanks for that article. Very interesting. That explains why clang doesn't currently work with C++ and .mm files - at least they are working on it.

    Posted 2 years ago #
13. 

    TD
    Member

    The static analyzer is included in Xcode 3.2:

    http://developer.apple.com/mac/library/featuredarticles/StaticAnalysis/index.html

    It is really nice. I guess the errors/warnings it finds in cocos2D are false positives?

    Posted 2 years ago #
14. 

    Mitch Lindgren
    Member

    They're not false positives per se, but they're not something to worry about either. It reports singletons as memory leaks, which technically they are, but it doesn't matter because you don't really need to ever deallocate a singleton anyway.

    Posted 2 years ago #
15. 

    Steve Oldmeadow
    Administrator

    It doesn't report Singletons as memory leaks, for example it is quite happy with Director. It doesn't like the style of coding used in SimpleAudioEngine because the set up is spread across alloc and init and the static analyzer can not cross function boundaries.

    The static analyzer is nice but it is worthwhile getting familiar with the (pretty major) limitations. Once it is working as Apple intend it will be awesome but it will still be impossible to detect all problems through static analysis.

    Posted 2 years ago #
16. 

    Mitch Lindgren
    Member

    Really? I'll go back and check, but I'm fairly certain I got warnings about possible leaks for every singleton in Cocos2D.

    Posted 2 years ago #
17. 

    Poltras
    Member

    Submitted a couple of patches and issue #613 for this. It will be solved (milestone is currently set to 0.8.3).

    Posted 2 years ago #
18. 

    PhilM
    Member

    Just wanted to check before I take the plunge on setting this up...

    Will Clang still work with the objective-c code in .mm files, and just not the c++?

    I'm still running OSX 10.5 & xcode 3.1.4, so would need to set it up manually. Don't really want to upgrade to 10.6 until I've got this box2d based project out the door, unless it makes this step much easier?

    Posted 2 years ago #

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