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comparison gcc/jit/docs/topics/function-pointers.rst @ 111:04ced10e8804

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gcc 7
author kono
date Fri, 27 Oct 2017 22:46:09 +0900
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1 .. Copyright (C) 2017 Free Software Foundation, Inc.
2 Originally contributed by David Malcolm <dmalcolm@redhat.com>
3
4 This is free software: you can redistribute it and/or modify it
5 under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see
16 <http://www.gnu.org/licenses/>.
17
18 .. default-domain:: c
19
20 Function pointers
21 =================
22
23 You can generate calls that use a function pointer via
24 :c:func:`gcc_jit_context_new_call_through_ptr`.
25
26 To do requires a :c:type:`gcc_jit_rvalue` of the correct function pointer type.
27
28 Function pointers for a :c:type:`gcc_jit_function` can be obtained
29 via :c:func:`gcc_jit_function_get_address`.
30
31 .. function:: gcc_jit_rvalue *\
32 gcc_jit_function_get_address (gcc_jit_function *fn,\
33 gcc_jit_location *loc)
34
35 Get the address of a function as an rvalue, of function pointer
36 type.
37
38 This entrypoint was added in :ref:`LIBGCCJIT_ABI_9`; you can test
39 for its presence using
40
41 .. code-block:: c
42
43 #ifdef LIBGCCJIT_HAVE_gcc_jit_function_get_address
44
45 Alternatively, given an existing function, you can obtain a pointer
46 to it in :c:type:`gcc_jit_rvalue` form using
47 :c:func:`gcc_jit_context_new_rvalue_from_ptr`, using a function pointer
48 type obtained using :c:func:`gcc_jit_context_new_function_ptr_type`.
49
50 Here's an example of creating a function pointer type corresponding to C's
51 :c:type:`void (*) (int, int, int)`:
52
53 .. code-block:: c
54
55 gcc_jit_type *void_type =
56 gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_VOID);
57 gcc_jit_type *int_type =
58 gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_INT);
59
60 /* Build the function ptr type. */
61 gcc_jit_type *param_types[3];
62 param_types[0] = int_type;
63 param_types[1] = int_type;
64 param_types[2] = int_type;
65
66 gcc_jit_type *fn_ptr_type =
67 gcc_jit_context_new_function_ptr_type (ctxt, NULL,
68 void_type,
69 3, param_types, 0);
70
71 .. function:: gcc_jit_type *\
72 gcc_jit_context_new_function_ptr_type (gcc_jit_context *ctxt,\
73 gcc_jit_location *loc,\
74 gcc_jit_type *return_type,\
75 int num_params,\
76 gcc_jit_type **param_types,\
77 int is_variadic)
78
79 Generate a :c:type:`gcc_jit_type` for a function pointer with the
80 given return type and parameters.