diff options
Diffstat (limited to 'gcc/sbitmap.c')
| -rw-r--r-- | gcc/sbitmap.c | 53 |
1 files changed, 52 insertions, 1 deletions
diff --git a/gcc/sbitmap.c b/gcc/sbitmap.c index d8b8d6c..cab4ec0 100644 --- a/gcc/sbitmap.c +++ b/gcc/sbitmap.c @@ -1,5 +1,5 @@ /* Simple bitmaps. - Copyright (C) 1999, 2000, 2002, 2003, 2004, 2006, 2007 + Copyright (C) 1999, 2000, 2002, 2003, 2004, 2006, 2007, 2008 Free Software Foundation, Inc. This file is part of GCC. @@ -273,6 +273,57 @@ sbitmap_empty_p (const_sbitmap bmap) return true; } +/* Return false if any of the N bits are set in MAP starting at + START. */ + +bool +sbitmap_range_empty_p (const_sbitmap bmap, unsigned int start, unsigned int n) +{ + unsigned int i = start / SBITMAP_ELT_BITS; + SBITMAP_ELT_TYPE elm; + unsigned int shift = start % SBITMAP_ELT_BITS; + + gcc_assert (bmap->n_bits >= start + n); + + elm = bmap->elms[i]; + elm = elm >> shift; + + if (shift + n <= SBITMAP_ELT_BITS) + { + /* The bits are totally contained in a single element. */ + if (shift + n < SBITMAP_ELT_BITS) + elm &= ((1 << n) - 1); + return (elm == 0); + } + + if (elm) + return false; + + n -= SBITMAP_ELT_BITS - shift; + i++; + + /* Deal with full elts. */ + while (n >= SBITMAP_ELT_BITS) + { + if (bmap->elms[i]) + return false; + i++; + n -= SBITMAP_ELT_BITS; + } + + /* The leftover bits. */ + if (n) + { + elm = bmap->elms[i]; + elm &= ((1 << n) - 1); + return (elm == 0); + } + + return true; +} + + + /* Zero all elements in a bitmap. */ void |