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1 .. Copyright (C) 2017-2018 Free Software Foundation, Inc.
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2 Originally contributed by David Malcolm <dmalcolm@redhat.com>
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3
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4 This is free software: you can redistribute it and/or modify it
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5 under the terms of the GNU General Public License as published by
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6 the Free Software Foundation, either version 3 of the License, or
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7 (at your option) any later version.
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8
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9 This program is distributed in the hope that it will be useful, but
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10 WITHOUT ANY WARRANTY; without even the implied warranty of
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11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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12 General Public License for more details.
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13
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14 You should have received a copy of the GNU General Public License
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15 along with this program. If not, see
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16 <http://www.gnu.org/licenses/>.
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17
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18 .. default-domain:: c
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19
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20 Function pointers
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21 =================
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22
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23 You can generate calls that use a function pointer via
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24 :c:func:`gcc_jit_context_new_call_through_ptr`.
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25
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26 To do requires a :c:type:`gcc_jit_rvalue` of the correct function pointer type.
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27
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28 Function pointers for a :c:type:`gcc_jit_function` can be obtained
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29 via :c:func:`gcc_jit_function_get_address`.
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30
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31 .. function:: gcc_jit_rvalue *\
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32 gcc_jit_function_get_address (gcc_jit_function *fn,\
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33 gcc_jit_location *loc)
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34
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35 Get the address of a function as an rvalue, of function pointer
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36 type.
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37
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38 This entrypoint was added in :ref:`LIBGCCJIT_ABI_9`; you can test
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39 for its presence using
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40
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41 .. code-block:: c
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42
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43 #ifdef LIBGCCJIT_HAVE_gcc_jit_function_get_address
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44
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45 Alternatively, given an existing function, you can obtain a pointer
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46 to it in :c:type:`gcc_jit_rvalue` form using
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47 :c:func:`gcc_jit_context_new_rvalue_from_ptr`, using a function pointer
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48 type obtained using :c:func:`gcc_jit_context_new_function_ptr_type`.
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49
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50 Here's an example of creating a function pointer type corresponding to C's
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51 :c:type:`void (*) (int, int, int)`:
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52
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53 .. code-block:: c
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54
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55 gcc_jit_type *void_type =
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56 gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_VOID);
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57 gcc_jit_type *int_type =
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58 gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_INT);
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59
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60 /* Build the function ptr type. */
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61 gcc_jit_type *param_types[3];
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62 param_types[0] = int_type;
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63 param_types[1] = int_type;
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64 param_types[2] = int_type;
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65
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66 gcc_jit_type *fn_ptr_type =
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67 gcc_jit_context_new_function_ptr_type (ctxt, NULL,
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68 void_type,
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69 3, param_types, 0);
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70
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71 .. function:: gcc_jit_type *\
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72 gcc_jit_context_new_function_ptr_type (gcc_jit_context *ctxt,\
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73 gcc_jit_location *loc,\
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74 gcc_jit_type *return_type,\
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75 int num_params,\
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76 gcc_jit_type **param_types,\
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77 int is_variadic)
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78
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79 Generate a :c:type:`gcc_jit_type` for a function pointer with the
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80 given return type and parameters.
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