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<a name="Declarations"></a>
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<p>
Next: <a href="Registering-Code.html#Registering-Code" accesskey="n" rel="next">Registering Code</a>, Up: <a href="JIT-Interface.html#JIT-Interface" accesskey="u" rel="up">JIT Interface</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<a name="JIT-Declarations"></a>
<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:
</p>
<div class="smallexample">
<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></div>

<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.
</p>


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