Fix block vector allocation code to allow VECTOR_BLOCK_SIZE

values which aren't power of 2.
* alloc.c (VECTOR_FREE_LIST_SIZE_MASK): New macro.  Verify
it's value and the value of VECTOR_BLOCK_SIZE.  Adjust users
accordingly.

2 files changed, 23 insertions, 4 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index aca64a79961..e3993981317 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2012-07-03  Dmitry Antipov  <dmantipov@yandex.ru>
+
+        Fix block vector allocation code to allow VECTOR_BLOCK_SIZE
+        values which aren't power of 2.
+        * alloc.c (VECTOR_FREE_LIST_SIZE_MASK): New macro.  Verify
+        it's value and the value of VECTOR_BLOCK_SIZE.  Adjust users
+        accordingly.
+
 2012-07-03  Stefan Monnier  <monnier@iro.umontreal.ca>
 
         * lisp.h (Lisp_Misc, Lisp_Fwd): Move around to group better.
diff --git a/src/alloc.c b/src/alloc.c
index 19972d54670..b1e2ed0a2ed 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -2869,6 +2869,12 @@ DEFUN ("make-list", Fmake_list, Smake_list, 2, 2, 0,
 
 #define VECTOR_BLOCK_SIZE 4096
 
+/* This special value is used to calculate vector size when the vector is
+   on a free list.  It should be VECTOR_BLOCK_SIZE rounded up to nearest
+   power of two, minus one.  */
+
+#define VECTOR_FREE_LIST_SIZE_MASK 4095
+
 /* Handy constants for vectorlike objects.  */
 enum
   {
@@ -2881,6 +2887,11 @@ enum
 /* ROUNDUP_SIZE must be a power of 2.  */
 verify ((roundup_size & (roundup_size - 1)) == 0);
 
+/* Verify assumptions described above.  */
+verify ((VECTOR_BLOCK_SIZE % roundup_size) == 0);
+verify ((VECTOR_FREE_LIST_SIZE_MASK + 1) >= VECTOR_BLOCK_SIZE);
+verify ((VECTOR_FREE_LIST_SIZE_MASK & (VECTOR_FREE_LIST_SIZE_MASK + 1)) == 0);
+
 /* Round up X to nearest mult-of-ROUNDUP_SIZE.  */
 
 #define vroundup(x) (((x) + (roundup_size - 1)) & ~(roundup_size - 1))
@@ -2908,7 +2919,7 @@ verify ((roundup_size & (roundup_size - 1)) == 0);
    this special value ORed with vector's memory footprint size.  */
 
 #define VECTOR_FREE_LIST_FLAG (~(ARRAY_MARK_FLAG | PSEUDOVECTOR_FLAG    \
-                                 | (VECTOR_BLOCK_SIZE - 1)))
+                                 | VECTOR_FREE_LIST_SIZE_MASK))
 
 /* Common shortcut to advance vector pointer over a block data.  */
 
@@ -3087,7 +3098,7 @@ sweep_vectors (void)
               if ((vector->header.size & VECTOR_FREE_LIST_FLAG)
                   == VECTOR_FREE_LIST_FLAG)
                 vector->header.next.nbytes =
-                  vector->header.size & (VECTOR_BLOCK_SIZE - 1);
+                  vector->header.size & VECTOR_FREE_LIST_SIZE_MASK;
 
               next = ADVANCE (vector, vector->header.next.nbytes);
 
@@ -3100,7 +3111,7 @@ sweep_vectors (void)
                     break;
                   if ((next->header.size & VECTOR_FREE_LIST_FLAG)
                       == VECTOR_FREE_LIST_FLAG)
-                    nbytes = next->header.size & (VECTOR_BLOCK_SIZE - 1);
+                    nbytes = next->header.size & VECTOR_FREE_LIST_SIZE_MASK;
                   else
                     nbytes = next->header.next.nbytes;
                   vector->header.next.nbytes += nbytes;
@@ -4334,7 +4345,7 @@ live_vector_p (struct mem_node *m, void *p)
           if ((vector->header.size & VECTOR_FREE_LIST_FLAG)
               == VECTOR_FREE_LIST_FLAG)
             vector = ADVANCE (vector, (vector->header.size
-                                       & (VECTOR_BLOCK_SIZE - 1)));
+                                       & VECTOR_FREE_LIST_SIZE_MASK));
           else if (vector == p)
             return 1;
           else