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-rw-r--r--m4/builtin-expect.m449
1 files changed, 49 insertions, 0 deletions
diff --git a/m4/builtin-expect.m4 b/m4/builtin-expect.m4
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+dnl Check for __builtin_expect.
+
+dnl Copyright 2016-2022 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Written by Paul Eggert.
+
+AC_DEFUN([gl___BUILTIN_EXPECT],
+[
+ AC_CACHE_CHECK([for __builtin_expect],
+ [gl_cv___builtin_expect],
+ [AC_LINK_IFELSE(
+ [AC_LANG_SOURCE([[
+ int
+ main (int argc, char **argv)
+ {
+ argc = __builtin_expect (argc, 100);
+ return argv[argc != 100][0];
+ }]])],
+ [gl_cv___builtin_expect=yes],
+ [AC_LINK_IFELSE(
+ [AC_LANG_SOURCE([[
+ #include <builtins.h>
+ int
+ main (int argc, char **argv)
+ {
+ argc = __builtin_expect (argc, 100);
+ return argv[argc != 100][0];
+ }]])],
+ [gl_cv___builtin_expect="in <builtins.h>"],
+ [gl_cv___builtin_expect=no])])])
+ if test "$gl_cv___builtin_expect" = yes; then
+ AC_DEFINE([HAVE___BUILTIN_EXPECT], [1])
+ elif test "$gl_cv___builtin_expect" = "in <builtins.h>"; then
+ AC_DEFINE([HAVE___BUILTIN_EXPECT], [2])
+ fi
+ AH_VERBATIM([HAVE___BUILTIN_EXPECT],
+ [/* Define to 1 if the compiler supports __builtin_expect,
+ and to 2 if <builtins.h> does. */
+#undef HAVE___BUILTIN_EXPECT
+#ifndef HAVE___BUILTIN_EXPECT
+# define __builtin_expect(e, c) (e)
+#elif HAVE___BUILTIN_EXPECT == 2
+# include <builtins.h>
+#endif
+ ])
+])