50 lines
1.5 KiB
Text
50 lines
1.5 KiB
Text
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dnl Check for __builtin_expect.
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dnl Copyright 2016-2021 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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dnl Written by Paul Eggert.
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AC_DEFUN([gl___BUILTIN_EXPECT],
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[
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AC_CACHE_CHECK([for __builtin_expect],
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[gl_cv___builtin_expect],
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[AC_LINK_IFELSE(
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[AC_LANG_SOURCE([[
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int
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main (int argc, char **argv)
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{
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argc = __builtin_expect (argc, 100);
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return argv[argc != 100][0];
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}]])],
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[gl_cv___builtin_expect=yes],
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[AC_LINK_IFELSE(
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[AC_LANG_SOURCE([[
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#include <builtins.h>
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int
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main (int argc, char **argv)
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{
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argc = __builtin_expect (argc, 100);
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return argv[argc != 100][0];
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}]])],
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[gl_cv___builtin_expect="in <builtins.h>"],
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[gl_cv___builtin_expect=no])])])
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if test "$gl_cv___builtin_expect" = yes; then
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AC_DEFINE([HAVE___BUILTIN_EXPECT], [1])
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elif test "$gl_cv___builtin_expect" = "in <builtins.h>"; then
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AC_DEFINE([HAVE___BUILTIN_EXPECT], [2])
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fi
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AH_VERBATIM([HAVE___BUILTIN_EXPECT],
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[/* Define to 1 if the compiler supports __builtin_expect,
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and to 2 if <builtins.h> does. */
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#undef HAVE___BUILTIN_EXPECT
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#ifndef HAVE___BUILTIN_EXPECT
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# define __builtin_expect(e, c) (e)
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#elif HAVE___BUILTIN_EXPECT == 2
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# include <builtins.h>
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#endif
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])
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])
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