From: Rosen Penev <rosenp@gmail.com>
Date: Tue, 28 May 2019 17:49:21 +0000 (-0700)
Subject: Check if -latomic is needed instead of hardcoding
X-Git-Tag: dnsdist-1.4.0-beta1~9^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1735eb98cd295c0aec2c2cd4cff436a786dbc70f;p=thirdparty%2Fpdns.git

Check if -latomic is needed instead of hardcoding

This avoids having a huge list of platforms which can change over time.
---

diff --git a/m4/pdns_check_os.m4 b/m4/pdns_check_os.m4
index 40d266a91d..da4bc8fd11 100644
--- a/m4/pdns_check_os.m4
+++ b/m4/pdns_check_os.m4
@@ -35,16 +35,21 @@ AC_DEFUN([PDNS_CHECK_OS],[
   AM_CONDITIONAL([HAVE_LINUX], [test "x$have_linux" = "xyes"])
   AM_CONDITIONAL([HAVE_SOLARIS], [test "x$have_solaris" = "xyes"])
 
-  case "$host" in
-  arc-* | mips* | powerpc-* )
-    AC_MSG_CHECKING([whether the linker accepts -latomic])
-    LDFLAGS="-latomic $LDFLAGS"
-    AC_LINK_IFELSE([m4_default([],[AC_LANG_PROGRAM()])],
-      [AC_MSG_RESULT([yes])],
-      [AC_MSG_ERROR([Unable to link against libatomic, cannot continue])]
-    )
-    ;;
-  esac
+  AC_MSG_CHECKING([whether -latomic is needed for __atomic builtins])
+  AC_LINK_IFELSE(
+    [AC_LANG_PROGRAM([[#include <stdint.h>]],
+       [[uint64_t val = 0; __atomic_add_fetch(&val, 1, __ATOMIC_RELAXED);]]
+    )],
+    [AC_MSG_RESULT([no])],
+    [LIBS="$LIBS -latomic"
+     AC_LINK_IFELSE(
+       [AC_LANG_PROGRAM([[#include <stdint.h>]],
+               [[uint64_t val = 0; __atomic_add_fetch(&val, 1, __ATOMIC_RELAXED);]]
+       )],
+       [AC_MSG_RESULT([yes])],
+       [AC_MSG_FAILURE([libatomic needed, but linking with -latomic failed, cannot continue])]
+    )]
+  )
 
   AC_SUBST(THREADFLAGS)
   AC_SUBST([DYNLINKFLAGS], [-export-dynamic])