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<h3 class="section">29.1 JIT Declarations</h3>

<p>These are the relevant struct declarations that a C program should include to
implement the interface:

<pre class="smallexample">     typedef enum
     {
       JIT_NOACTION = 0,
       JIT_REGISTER_FN,
       JIT_UNREGISTER_FN
     } jit_actions_t;
     
     struct jit_code_entry
     {
       struct jit_code_entry *next_entry;
       struct jit_code_entry *prev_entry;
       const char *symfile_addr;
       uint64_t symfile_size;
     };
     
     struct jit_descriptor
     {
       uint32_t version;
       /* This type should be jit_actions_t, but we use uint32_t
          to be explicit about the bitwidth.  */
       uint32_t action_flag;
       struct jit_code_entry *relevant_entry;
       struct jit_code_entry *first_entry;
     };
     
     /* GDB puts a breakpoint in this function.  */
     void __attribute__((noinline)) __jit_debug_register_code() { };
     
     /* Make sure to specify the version statically, because the
        debugger may check the version before we can set it.  */
     struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
</pre>
   <p>If the JIT is multi-threaded, then it is important that the JIT synchronize any
modifications to this global data properly, which can easily be done by putting
a global mutex around modifications to these structures.

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