2.6 Function pointers ¶

You can generate calls that use a function pointer via gcc_jit_context_new_call_through_ptr().

To do requires a gcc_jit_rvalue of the correct function pointer type.

Function pointers for a gcc_jit_function can be obtained via gcc_jit_function_get_address().

C Function: gcc_jit_rvalue * gcc_jit_function_get_address (gcc_jit_function *fn, gcc_jit_location *loc) ¶

Get the address of a function as an rvalue, of function pointer type.

This entrypoint was added in LIBGCCJIT_ABI_9; you can test for its presence using

#ifdef LIBGCCJIT_HAVE_gcc_jit_function_get_address

Alternatively, given an existing function, you can obtain a pointer to it in gcc_jit_rvalue form using gcc_jit_context_new_rvalue_from_ptr(), using a function pointer type obtained using gcc_jit_context_new_function_ptr_type().

Here’s an example of creating a function pointer type corresponding to C’s void (*) (int, int, int):

gcc_jit_type *void_type =
  gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_VOID);
gcc_jit_type *int_type =
  gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_INT);

/* Build the function ptr type.  */
gcc_jit_type *param_types[3];
param_types[0] = int_type;
param_types[1] = int_type;
param_types[2] = int_type;

gcc_jit_type *fn_ptr_type =
  gcc_jit_context_new_function_ptr_type (ctxt, NULL,
                                         void_type,
                                         3, param_types, 0);

C Function: gcc_jit_type * gcc_jit_context_new_function_ptr_type (gcc_jit_context *ctxt, gcc_jit_location *loc, gcc_jit_type *return_type, int num_params, gcc_jit_type **param_types, int is_variadic) ¶

Generate a gcc_jit_type for a function pointer with the given return type and parameters.

Each of param_types must be non-void; return_type may be void.