Imported Upstream version 6.10.0.49

Former-commit-id: 1d6753294b2993e1fbf92de9366bb9544db4189b

external/llvm-project/polly/lib/External/isl/isl_ffs.c

@@ -0,0 +1,24 @@
+#include <isl_config.h>
+
+#if !HAVE_DECL_FFS && !HAVE_DECL___BUILTIN_FFS && HAVE_DECL__BITSCANFORWARD
+#include <intrin.h>
+
+/* Implementation of ffs in terms of _BitScanForward.
+ *
+ * ffs returns the position of the least significant bit set in i,
+ * with the least significant bit is position 1, or 0 if not bits are set.
+ *
+ * _BitScanForward returns 1 if mask is non-zero and sets index
+ * to the position of the least significant bit set in i,
+ * with the least significant bit is position 0.
+ */
+int isl_ffs(int i)
+{
+	unsigned char non_zero;
+	unsigned long index, mask = i;
+
+	non_zero = _BitScanForward(&index, mask);
+
+	return non_zero ? 1 + index : 0;
+}
+#endif