I dont understand the whole Clang and llvm thingy. I asked myself if the code is running in a VM while runtime on the iOS device or wether it is going through a "VM" while compile time, for compile-time optimization and so on?
LLVM is not a virtual machine in that sense of the word. The thing is that LLVM is a code generator that helps unifying compilers, languages and target processors/OSes. LLVM is useful for compiler developers only. In fact, in the Clang compiler, it plays a major role, but that's entirely internal - what comes out of Clang is pure, native ARM/iOS machine code.