JIT with mulle clang

JIT compilation should be easy, if you have the proper mulle-objc-runtime.h header accessible. Your JIT code should import it, which it usually does by virtue of including Foundation.h, MulleObjC.h or some such header.

The resulting compiled object will contain a function __load_mulle_objc that is an __attribute__(( constructor)) function, meaning that it should execute as soon as loaded. Depending on the JIT setup you may have to call this yourself, to get classes, categories, strings, selectors etc. added to the runtime.

Compiling without mulle-objc-runtime.h

The lldb debugger does some funky JIT stuff, as the mulle-objc-runtime.h header is not readily available. To support such scenarios, your code must define a top level variable __mulle_objc_objccompilerinfo like so:

static const 
struct mulle_clang_objccompilerinfo
{
  unsigned int   load_version;
  unsigned int   runtime_version;
} __mulle_objc_objccompilerinfo =
{
  12, // load version must match!
      // check with: mulle-clang --version
  0   // 0 to not emit __load_mulle_objc 
      // otherwise provide the current runtime version
      // as: ((0 << 20) | (13 << 8) | 1) for 0.13.1
};