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authorCyrill Gorcunov <gorcunov@gmail.com>2018-02-25 17:09:11 +0300
committerCyrill Gorcunov <gorcunov@gmail.com>2018-02-25 17:09:11 +0300
commit8ba28e13ea4453a587d08e5533e60f4ff2b4781a (patch)
tree87650f9d9cc2e77579e6cafff8ece738d4cae72b
parentfb9e00a1c3c3ec89d385175baa6e66b15318bda8 (diff)
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compiler: Add fallthrough() helper
https://bugzilla.nasm.us/show_bug.cgi?id=3392465 Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
-rw-r--r--aclocal.m426
-rw-r--r--configure.ac5
-rw-r--r--include/compiler.h9
3 files changed, 40 insertions, 0 deletions
diff --git a/aclocal.m4 b/aclocal.m4
index 36d36cf8..43649e70 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -199,3 +199,29 @@ inline int foo(int x)
[Define to 1 if your compiler supports C99 extern inline])],
[AC_MSG_RESULT([no])
PA_ADD_CFLAGS([-fgnu89-inline])])])
+
+dnl --------------------------------------------------------------------------
+dnl PA_CHECK_FALLTHROUGH_ATTRIBUTE
+dnl --------------------------------------------------------------------------
+AC_DEFUN(PA_CHECK_FALLTHROUGH_ATTRIBUTE,
+[AC_MSG_CHECKING([if $CC supports fallthrough attribute])
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE([
+AC_INCLUDES_DEFAULT
+int main(int argc, char **argv)
+{
+ switch (argc) {
+ case 1:
+ (void)argc;
+ __attribute__((fallthrough));
+ default:
+ (void)argv;
+ break;
+ }
+ return argc;
+}
+ ])],
+ [AC_MSG_RESULT([yes])
+ AC_DEFINE([HAVE_FALLTHROUGH_ATTRIBUTE], 1,
+ [Define to 1 if your compiler supports __attribute__((fallthrough))])],
+ [AC_MSG_RESULT([no])])
+])
diff --git a/configure.ac b/configure.ac
index 44c9e179..2f4d26fa 100644
--- a/configure.ac
+++ b/configure.ac
@@ -294,6 +294,11 @@ dnl options.
dnl
PA_CHECK_BAD_STDC_INLINE
+dnl Figure out if we can use fallthrough attribute or
+dnl should provide simple comment instead.
+dnl
+PA_CHECK_FALLTHROUGH_ATTRIBUTE
+
dnl
dnl support ccache
dnl
diff --git a/include/compiler.h b/include/compiler.h
index fb146af4..f4393518 100644
--- a/include/compiler.h
+++ b/include/compiler.h
@@ -241,6 +241,15 @@ size_t strnlen(const char *s, size_t maxlen);
#endif
/*
+ * Fallthrough handling.
+ */
+#ifdef HAVE_FALLTHROUGH_ATTRIBUTE
+# define fallthrough() __attribute__((fallthrough))
+#else
+# define fallthrough() /* fall through */
+#endif
+
+/*
* Hints to the compiler that a particular branch of code is more or
* less likely to be taken.
*/