4 files changed, 22 insertions, 14 deletions
diff --git a/gcc/bitmap.c b/gcc/bitmap.c
index 98c6d0b..1aa8e4b 100644
--- a/gcc/bitmap.c
+++ b/gcc/bitmap.c
@@ -983,7 +983,7 @@ bitmap_set_bit (bitmap head, int bit)
 
 /* Return whether a bit is set within a bitmap.  */
 
-int
+bool
 bitmap_bit_p (const_bitmap head, int bit)
 {
   unsigned int indx = bit / BITMAP_ELEMENT_ALL_BITS;
diff --git a/gcc/bitmap.h b/gcc/bitmap.h
index 1bddcdb..fc33877 100644
--- a/gcc/bitmap.h
+++ b/gcc/bitmap.h
@@ -436,7 +436,7 @@ extern bool bitmap_clear_bit (bitmap, int);
 extern bool bitmap_set_bit (bitmap, int);
 
 /* Return true if a bit is set in a bitmap.  */
-extern int bitmap_bit_p (const_bitmap, int);
+extern bool bitmap_bit_p (const_bitmap, int);
 
 /* Set and get multiple bit values in a sparse bitmap.  This allows a bitmap to
    function as a sparse array of bit patterns where the patterns are
diff --git a/gcc/sbitmap.h b/gcc/sbitmap.h
index 17660e5..5fb0e00 100644
--- a/gcc/sbitmap.h
+++ b/gcc/sbitmap.h
@@ -114,7 +114,7 @@ bitmap_check_sizes (const_sbitmap a, const_sbitmap b)
 }
 
 /* Test if bit number bitno in the bitmap is set.  */
-static inline SBITMAP_ELT_TYPE
+static inline bool
 bitmap_bit_p (const_sbitmap map, int bitno)
 {
   bitmap_check_index (map, bitno);
@@ -124,26 +124,36 @@ bitmap_bit_p (const_sbitmap map, int bitno)
   return (map->elms[i] >> s) & (SBITMAP_ELT_TYPE) 1;
 }
 
-/* Set bit number BITNO in the sbitmap MAP.  */
+/* Set bit number BITNO in the sbitmap MAP.
+   Return true if the bit changed.  */
 
-static inline void
+static inline bool
 bitmap_set_bit (sbitmap map, int bitno)
 {
   bitmap_check_index (map, bitno);
 
-  map->elms[bitno / SBITMAP_ELT_BITS]
-    |= (SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS;
+  size_t i = bitno / SBITMAP_ELT_BITS;
+  unsigned int s = bitno % SBITMAP_ELT_BITS;
+  if (map->elms[i] & ((SBITMAP_ELT_TYPE) 1 << s))
+    return false;
+  map->elms[i] |= (SBITMAP_ELT_TYPE) 1 << s;
+  return true;
 }
 
-/* Reset bit number BITNO in the sbitmap MAP.  */
+/* Reset bit number BITNO in the sbitmap MAP.
+   Return true if the bit changed.  */
 
-static inline void
+static inline bool
 bitmap_clear_bit (sbitmap map, int bitno)
 {
   bitmap_check_index (map, bitno);
 
-  map->elms[bitno / SBITMAP_ELT_BITS]
-    &= ~((SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS);
+  size_t i = bitno / SBITMAP_ELT_BITS;
+  unsigned int s = bitno % SBITMAP_ELT_BITS;
+  if (!(map->elms[i] & ((SBITMAP_ELT_TYPE) 1 << s)))
+    return false;
+  map->elms[i] &= ~((SBITMAP_ELT_TYPE) 1 << s);
+  return true;
 }
 
 /* The iterator for sbitmap.  */
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index fde13de..3f25d65 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -649,11 +649,9 @@ verify_vssa (basic_block bb, tree current_vdef, sbitmap visited)
 {
   bool err = false;
 
-  if (bitmap_bit_p (visited, bb->index))
+  if (!bitmap_set_bit (visited, bb->index))
     return false;
 
-  bitmap_set_bit (visited, bb->index);
-
   /* Pick up the single virtual PHI def.  */
   gphi *phi = NULL;
   for (gphi_iterator si = gsi_start_phis (bb); !gsi_end_p (si);