Using own popcount where the compiler builtin is not available.

auto/clang

@@ -101,6 +101,19 @@ nxt_feature_test="int main() {
 . auto/feature
 
 
+nxt_feature="GCC __builtin_popcount()"
+nxt_feature_name=NXT_HAVE_BUILTIN_POPCOUNT
+nxt_feature_run=
+nxt_feature_incs=
+nxt_feature_libs=
+nxt_feature_test="int main() {
+                      if (__builtin_popcount(5) == 2)
+                          return 0;
+                      return 1;
+                  }"
+. auto/feature
+
+
 nxt_feature="GCC __attribute__ visibility"
 nxt_feature_name=NXT_HAVE_GCC_ATTRIBUTE_VISIBILITY
 nxt_feature_run=

src/nxt_clang.h

@@ -132,6 +132,27 @@ nxt_prefetch(a)
 #endif
 
 
+#if (NXT_HAVE_BUILTIN_POPCOUNT)
+
+#define nxt_popcount       __builtin_popcount
+
+#else
+
+nxt_inline int
+nxt_popcount(unsigned int x)
+{
+    int  count;
+
+    for (count = 0; x != 0; x >>= 1) {
+        count += (x & 1);
+    }
+
+    return count;
+}
+
+#endif
+
+
 #ifndef NXT_ALIGNMENT
 
 #if (NXT_SOLARIS)

src/nxt_conf_validation.c

@@ -331,7 +331,7 @@ nxt_conf_vldt_type(nxt_conf_validation_t *vldt, nxt_str_t *name,
 
     p = buf;
 
-    n = __builtin_popcount(type);
+    n = nxt_popcount(type);
 
     if (n > 1) {
         p = nxt_cpymem(p, "either ", 7);