83 lines
2.8 KiB
ReStructuredText
83 lines
2.8 KiB
ReStructuredText
.. Copyright (C) 2017-2021 Free Software Foundation, Inc.
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Originally contributed by David Malcolm <dmalcolm@redhat.com>
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This is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see
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<http://www.gnu.org/licenses/>.
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.. default-domain:: c
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Function pointers
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=================
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You can generate calls that use a function pointer via
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:c:func:`gcc_jit_context_new_call_through_ptr`.
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To do requires a :c:type:`gcc_jit_rvalue` of the correct function pointer type.
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Function pointers for a :c:type:`gcc_jit_function` can be obtained
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via :c:func:`gcc_jit_function_get_address`.
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.. function:: gcc_jit_rvalue *\
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gcc_jit_function_get_address (gcc_jit_function *fn,\
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gcc_jit_location *loc)
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Get the address of a function as an rvalue, of function pointer
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type.
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This entrypoint was added in :ref:`LIBGCCJIT_ABI_9`; you can test
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for its presence using
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.. code-block:: c
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#ifdef LIBGCCJIT_HAVE_gcc_jit_function_get_address
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Alternatively, given an existing function, you can obtain a pointer
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to it in :c:type:`gcc_jit_rvalue` form using
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:c:func:`gcc_jit_context_new_rvalue_from_ptr`, using a function pointer
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type obtained using :c:func:`gcc_jit_context_new_function_ptr_type`.
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Here's an example of creating a function pointer type corresponding to C's
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:c:type:`void (*) (int, int, int)`:
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.. code-block:: c
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gcc_jit_type *void_type =
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gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_VOID);
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gcc_jit_type *int_type =
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gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_INT);
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/* Build the function ptr type. */
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gcc_jit_type *param_types[3];
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param_types[0] = int_type;
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param_types[1] = int_type;
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param_types[2] = int_type;
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gcc_jit_type *fn_ptr_type =
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gcc_jit_context_new_function_ptr_type (ctxt, NULL,
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void_type,
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3, param_types, 0);
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.. function:: gcc_jit_type *\
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gcc_jit_context_new_function_ptr_type (gcc_jit_context *ctxt,\
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gcc_jit_location *loc,\
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gcc_jit_type *return_type,\
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int num_params,\
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gcc_jit_type **param_types,\
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int is_variadic)
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Generate a :c:type:`gcc_jit_type` for a function pointer with the
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given return type and parameters.
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Each of `param_types` must be non-`void`; `return_type` may be `void`.
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