+# Check to see if -pthread or -lpthread is needed. Prefer the former.
+# In case the pthread.h system header is not found, this test will fail.
+XPCFLAGS=""
+CFLAGS="$CFLAGS -pthread"
+AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#include <pthread.h>
+ void *g(void *d) { return NULL; }],
+ [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
+ [XPCFLAGS=" -Wc,-pthread"],
+ [CFLAGS="$save_CFLAGS" LIBS="-lpthread $LIBS"
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#include <pthread.h>
+ void *g(void *d) { return NULL; }],
+ [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
+ [],
+ [AC_MSG_ERROR([Pthreads are required to build libcilkrts])])])
+