2007-11-09 Richard Guenther <rguenther@suse.de>

	* bitmap.h (bitmap_single_bit_set_p): Declare.
	* bitmap.c (bitmap_single_bit_set_p): New function.
	* tree-ssa-alias.c (add_may_alias_for_new_tag): Use it.
	(maybe_create_global_var): Use bitmap_empty_p.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@130045 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 34 insertions, 0 deletions

diff --git a/gcc/bitmap.c b/gcc/bitmap.c
index 8b66548add9..c2a66f96a73 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