Guard Getcpu in test.

Summary:Guarding this the same way it is done in
detail/CacheLocality.cpp

Reviewed By: yfeldblum

Differential Revision: D3013288

fb-gh-sync-id: a1cc65cccc5cdf32339a739853c27a11ecd98ba0
shipit-source-id: a1cc65cccc5cdf32339a739853c27a11ecd98ba0

folly/configure.ac

@@ -252,6 +252,28 @@ if test "$folly_cv_lib_libatomic" = no; then
                   [Please install the GNU Atomic library])])
 fi
 
+AC_CACHE_CHECK(
+  [for liblinux-vdso support],
+  [folly_cv_lib_liblinux_vdso],
+  [AC_RUN_IFELSE(
+    [AC_LANG_PROGRAM[
+      #include <dlfcn.h>
+      int main() {
+        void *h = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+        if (h == nullptr) {
+          return -1;
+        }
+        dlclose(h);
+        return 0;
+      }
+    ]],
+    [folly_cv_lib_liblinux_vdso=yes],
+    [folly_cv_lib_liblinux_vdso=no])])
+
+if test "$folly_cv_lib_liblinux_vdso" = yes; then
+  AC_DEFINE([HAVE_LINUX_VDSO], [1], [Define to 1 if liblinux-vdso is available])
+fi
+
 AC_CACHE_CHECK(
   [for usable std::is_trivially_copyable],
   [folly_cv_decl_std_is_trivially_copyable],

folly/detail/CacheLocality.cpp

@@ -210,7 +210,7 @@ CacheLocality CacheLocality::uniform(size_t numCpus) {
 ////////////// Getcpu
 
 Getcpu::Func Getcpu::resolveVdsoFunc() {
-#if defined(_MSC_VER) || defined(__BIONIC__)
+#if !FOLLY_HAVE_LINUX_VDSO
   return nullptr;
 #else
   void* h = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);

folly/test/CacheLocalityTest.cpp

@@ -351,12 +351,14 @@ TEST(CacheLocality, FakeSysfs) {
   EXPECT_EQ(expected.localityIndexByCpu, parsed.localityIndexByCpu);
 }
 
+#if FOLLY_HAVE_LINUX_VDSO
 TEST(Getcpu, VdsoGetcpu) {
   unsigned cpu;
   Getcpu::resolveVdsoFunc()(&cpu, nullptr, nullptr);
 
   EXPECT_TRUE(cpu < CPU_SETSIZE);
 }
+#endif
 
 #ifdef FOLLY_TLS
 TEST(ThreadId, SimpleTls) {