1 files changed, 34 insertions, 0 deletions
diff --git a/gcc/bitmap.c b/gcc/bitmap.c
index 8b66548..c2a66f9 100644
--- a/gcc/bitmap.c
+++ b/gcc/bitmap.c
@@ -693,6 +693,40 @@ bitmap_count_bits (const_bitmap a)
   return count;
 }
 
+/* Return true if the bitmap has a single bit set.  Otherwise return
+   false.  */
+
+bool
+bitmap_single_bit_set_p (const_bitmap a)
+{
+  unsigned long count = 0;
+  const bitmap_element *elt;
+  unsigned ix;
+
+  if (bitmap_empty_p (a))
+    return false;
+
+  elt = a->first;
+  /* As there are no completely empty bitmap elements, a second one
+     means we have more than one bit set.  */
+  if (elt->next != NULL)
+    return false;
+
+  for (ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
+    {
+#if GCC_VERSION >= 3400
+      /* Note that popcountl matches BITMAP_WORD in type, so the actual size
+	 of BITMAP_WORD is not material.  */
+      count += __builtin_popcountl (elt->bits[ix]);
+#else
+      count += bitmap_popcount (elt->bits[ix]);
+#endif
+      if (count > 1)
+	return false;
+    }
+
+  return count == 1;
+}
 
 
 /* Return the bit number of the first set bit in the bitmap.  The