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- /* IFUNC generic definitions.
- This file is part of the GNU C Library.
- Copyright (C) 2017-2019 Free Software Foundation, Inc.
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
- /* These macros are used to implement ifunc selection in C. To implement
- an ifunc function, foo, which returns the address of __foo_impl1 or
- __foo_impl2:
- #define foo __redirect_foo
- #include <foo.h>
- #undef foo
- #define SYMBOL_NAME foo
- #include <ifunc-init.h>
- extern __typeof (REDIRECT_NAME) OPTIMIZE (impl1) attribute_hidden;
- extern __typeof (REDIRECT_NAME) OPTIMIZE (impl2) attribute_hidden;
- static inline void *
- foo_selector (void)
- {
- if (condition)
- return OPTIMIZE (impl2);
- return OPTIMIZE (impl1);
- }
- libc_ifunc_redirected (__redirect_foo, foo, IFUNC_SELECTOR ());
- */
- #define PASTER1(x,y) x##_##y
- #define EVALUATOR1(x,y) PASTER1 (x,y)
- #define PASTER2(x,y) __##x##_##y
- #define EVALUATOR2(x,y) PASTER2 (x,y)
- /* Basically set '__redirect_<symbol>' to use as type definition,
- '__<symbol>_<variant>' as the optimized implementation and
- '<symbol>_ifunc_selector' as the IFUNC selector. */
- #define REDIRECT_NAME EVALUATOR1 (__redirect, SYMBOL_NAME)
- #define OPTIMIZE(name) EVALUATOR2 (SYMBOL_NAME, name)
- #define IFUNC_SELECTOR EVALUATOR1 (SYMBOL_NAME, ifunc_selector)
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