[Emacs-diffs] /srv/bzr/emacs/trunk r108843: Fix block vector allocation code to allow VECTOR_BLOCK_SIZE

[Dmitry Antipov]

------------------------------------------------------------
revno: 108843
committer: Dmitry Antipov <address@hidden>
branch nick: trunk
timestamp: Tue 2012-07-03 20:35:53 +0400
message:
  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.
modified:
  src/ChangeLog
  src/alloc.c

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2012-07-03 14:37:55 +0000
+++ b/src/ChangeLog     2012-07-03 16:35:53 +0000
@@ -1,3 +1,11 @@
+2012-07-03  Dmitry Antipov  <address@hidden>
+
+       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  <address@hidden>
 
        * lisp.h (Lisp_Misc, Lisp_Fwd): Move around to group better.

=== modified file 'src/alloc.c'
--- a/src/alloc.c       2012-07-03 14:37:55 +0000
+++ b/src/alloc.c       2012-07-03 16:35:53 +0000
@@ -2869,6 +2869,12 @@
 
 #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 @@
 /* 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 @@
    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 @@
              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 @@
                    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 @@
          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