Compiling with LLVM/Clang causes crash, not GCC 4.

I'm working on an iPhone app, and I'm having some compiler trouble. Here's the low-down:

I am compiling using Xcode 3.2.3, targeting iOS 4.0: my device is a 2nd Gen. iPod touch running iOS 4.0.
Compiling with GCC 4.2: works on both the simulator and the device
Compiling with LLVM compiler 1.5: works on simulator, but not on device.
Compiling with LLVM GCC 4.2: same problem as with LLVM compiler 1.5.

When it fails, the app never even finishes loading. This is what the log looks like:

run
Running…
[Switching to thread 11523]
[Switching to thread 11523]
sharedlibrary apply-load-rules all
continue
Program received signal:  “EXC_BAD_ACCESS”.
warning: check_safe_call: could not restore current frame

warning: Unable to restore previously selected frame.
warning: Unable to restore previously selected frame.
warning: Unable to restore previously selected frame.
warning: Unable to restore previously selected frame.
warning: Unable to restore previously selected frame.

I have no idea what is going on with this. I really want to update my code to use the latest features announced at WWDC (implicit @synthesize, the ability to add instance variables in categories, etc.), but Clang is necessary for that.

Looks like something pooped on memory. More specifically, on the stack.

There are some fairly significant, though entirely subtle, differences in code-gen between LLVM and GCC. Keep in mind that LLVM-GCC is really GCC->LLVM; that is, the GCC parser feeding the LLVM code generation engine.

Thus, I suspect you have hit a lovely edge case. Either a bug in LLVM's codegen or a bug in your program that manifests itself as this kind of a crash.

Off the top of my head, I could imagine that a failure to -copy a block and then execute that block on a different thread might manifest as a crash like this.

In any case, file a bug if you can.