Fix GCC 12 compilation on riscv64

Close GH-11321

Author: danog

NEWS

@@ -2,6 +2,9 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 8.1.21
 
+- Core:
+  . Fixed build for the riscv64 architecture/GCC 12. (Daniil Gentili)
+
 - DOM:
   . Fixed bugs GH-11288 and GH-11289 and GH-11290 and GH-9142 (DOMExceptions
     and segfaults with replaceWith). (nielsdos)

configure.ac

@@ -365,6 +365,16 @@ if test "$ac_cv_func_dlopen" = "yes"; then
 fi
 AC_CHECK_LIB(m, sin)
 
+case $host_alias in
+  riscv64*)
+    AC_CHECK_LIB(atomic, __atomic_exchange_1, [
+      PHP_ADD_LIBRARY(atomic)
+    ], [
+      AC_MSG_ERROR([Problem with enabling atomic. Please check config.log for details.])
+    ])
+    ;;
+esac
+
 dnl Check for inet_aton in -lc, -lbind and -lresolv.
 PHP_CHECK_FUNC(inet_aton, resolv, bind)