On Jun 17, 2011, at 3:48 PM, Laurent Daudelin wrote: > On Jun 17, 2011, at 15:22, Greg Parker wrote: > >> On Jun 17, 2011, at 2:40 PM, Laurent Daudelin wrote: >>> One of my user sent me a crash log with an excerpt here: >>> >>> ... >>> Exception Type: EXC_BAD_ACCESS (SIGSEGV) >>> Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000027 >>> ... >>> Thread 4 Crashed: Dispatch queue: com.apple.root.default-priority >>> 0 libobjc.A.dylib 0x00007fff85ea115c objc_msgSend_vtable2 >>> + 12 >>> 1 com.apple.Foundation 0x00007fff827f79a5 -[NSCFString >>> isEqualToString:] + 63 >>> ... >>> >>> It's a part of my code that compares NSStrings. Of course, nobody besides >>> him are able to reproduce this. >>> >>> My question: what could cause a crash in function 'objc_msgSend_vtable2'? >> >> Short answer: for any of the same reasons that cause a crash in >> objc_msgSend(). >> >> The vtable versions of objc_msgSend() are specialized optimizations for a >> few of the most frequently-called methods. objc_msgSend_vtable2 is currently >> optimizing the -class method. Presumably one of the two string objects was >> invalid and -isEqualToString: was trying to check which class the bad object >> belonged to. > > Thanks for the speedy reply, Greg. What do you mean exactly by "invalid"? Bad > pointers? Pointers on instances of different classes? Or both?
Pointer to anything that is not a valid object. Merely being an instance of the wrong class would not cause that crash. -- Greg Parker gpar...@apple.com Runtime Wrangler _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
