Hey,
Have you experienced any incompatibility between LLVM compiler and GCC compiler ?
I found one strange issue:
If you compile ParticleTests with GCC and if you try sub-test "issue 872", it works as expected: a particle system will emit particles.
But if you compile it with LLVM 1.5, you won't see any particle at all. I'm not sure what's the problem, but I'll investigate it a bit further.
I can only reproduce this bug on the simulator. It seems that this bug can't be reproduced on the devices.
I tested it both in Release & Debug mode using Xcode 3.2.3.