[Openmcl-devel] New (070512) OpenMCL snapshots available

Gary Byers gb at clozure.com
Sun May 13 00:57:49 UTC 2007


There are new (1.1-pre-070512) OpenMCL snapshot tarballs available in
<ftp://clozure.com/pub/testing>.

>From the release notes (which are also available in that directory and
in the tarballs):

OpenMCL 1.1-pre-070512
- The FASL version changed (old FASL files won't work with this
   lisp version), as did the version information which tries to
   keep the kernel in sync with heap images.  Note that it's generally
   a lot easier to recompile recent sources with recent images, e.g.,
   trying to compile 070512 sources with an 070408 image is unlikely
   to work without tricky bootstrapping.
- Most of the changes in this release involve the calling sequence
   used on x86-64.  In very general terms, some kinds of function-call
   intensive code may see a significant performance boost, most code
   should see a slight improvement, some code might see a (hopefully
   very slight) degradation, and anything significantly slower than
   previous releases should be reported as a bug.
   It is -possible- that some of these changes may cause errors to
   be reported differently (the function reported as the function
   executing when the error ocurred might be different/wrong).  I
   have not seen as many cases of this as I expected to when making
   the change, but am also not sure that I fixed all possible cases.
- The FFI-related reader macros #_, #$, and #& all read a case-sensitive
   foreign function, constant, or variable name from the input stream
   and try to find the corresponding definition in the interface files.
   If the name is prefixed with a #\? - as in #_?foo - the macros
   return true if the definition could be found and false otherwise.
   (The general idea is that this might be useful for conditionalizing
   code in some cases, and there should be -some- way of quietly testing
   that something's defined.)
- There is now support for making the contents of (possibly very large)
   files accessible as lisp vectors.  (This may be many times faster
   than something like

   (let* ((stream (open pathname :direction :input :element-type 'whatever))
          (vector (make-array (file-size-to-vector-size stream)
                              :element-type 'whatever)))
     (read-sequence vector stream))

   but has the similar effect of making the contents of VECTOR match the
   contents of the file.)

   CCL:MAP-FILE-TO-IVECTOR pathname element-type [Function]

   "element-type" should be a type specifier such that
   (UPGRADED-ARRAY-ELEMENT-TYPE element-type) is a subtype
   of either SIGNED-BYTE or UNSIGNED-BYTE.

   Tries to open the file named by "pathname" for reading and to
   map its contents into the process's address space via #_mmap;
   if successful, returns a lisp vector of element-type
   (UPGRADED-ARRAY-ELEMENT-TYPE element-type) which is displaced
   to an underlying (SIMPLE-ARRAY element-type (*)) whose contents
   match the mapped file's.

   Because of alignment issues, the mapped file's contents will
   start a few bytes (4 bytes on 32-bit platforms, 8 bytes on 64-bit
   platforms) "into" the vector; the displaced array returned by
   CCL:MAP-FILE-TO-IVECTOR hides this overhead, but its usually
   more efficient to operate on the underlying simple 1-dimensional
   array.  Given a displaced array (like the value returned by
   CCL:MAP-FILE-TO-IVECTOR), the CL function ARRAY-DISPLACEMENT
   returns the underlying array and the displacement index in elements.

   Currently, only read-only file mapping is supported; the underlying
   vector will be allocated in read-only memory, and attempts to use
   (e.g.) (SETF (AREF ...) ...) to modify the mapped vector's contents
   will result in memory faults.

   CCL:MAP-FILE-TO-OCTET-VECTOR pathname [Function]

   Equivalent to (CCL:MAP-FILE-TO-IVECTOR pathname '(UNSIGNED-BYTE 8)).

   CCL:UNMAP-IVECTOR displaced-vector

   If the argument is a mapped vector (as returned by
   MAP-FILE-TO-IVECTOR) that has not yet been "unmapped" by this
   function, undoes the memory mapping, closes the mapped file, and
   adjusts its argument so that it's displaced to a 0-length vector.

   CCL:UNMAP-OCTET-VECTOR is an alias for CCL:UNMAP-IVECTOR

   Note that whether a vector's created by MAKE-ARRAY or by mapping
   a file's contents, it can't have ARRAY-TOTAL-SIZE-LIMIT or more
   elements.  (ARRAY-TOTAL-SIZE-LIMIT is (EXPT 2 24) in 32-bit OpenMCL
   and (EXPT 2 56) in 64-bit versions.

- The lisp kernel now tries to signal memory faults that occur when
   running lisp code as lisp errors.  As a silly example:

   ? (defun foo (x)
      "Crash and burn if X is not a list"
      (declare (optimize (speed 3) (safety 0)) (list x))
      (car x))
   FOO
   ? (foo 0)
   > Error: Fault during read of memory address #x4
   > While executing: FOO, in process listener(1).

   The fact that things are handled this way (rather than going
   into the kernel debugger with no easy way of recovering) makes
   it possible to continue a session without losing work in many
   cases.  In a trivial example like the one above, it's relatively
   easy to see that no harm has been done and the error should
   not be hard to recover from.  In some other cases, it may be
   true that a buggy function has been scribbling ofer memory for
   a while before that scribbling resulted in a machine exception.

   Moral: if you get an unexpected "memory fault" error (the
   condition type is actually CCL::INVALID-MEMORY-ACCESS) and
   don't understand why the fault occurred and the consequences
   of continuing in the lisp session where the fault occurred,
   you should view the state of that session with some suspicion.

   Faults in foreign code (should) still trap into the kernel
   debugger.  (It'd be nice to be able to treat these as lisp
   errors with the same caveats as described above, but that
   is more complicated in some cases and isn't yet implemented.)

- An obscure kernel debugger command - (A), which tries to advance
   the program counter by one instruction - is now disabled on x86-64.
   (On the PPC, "one instruction" always meant "4 bytes"; implementing
   this correctly on x86-64 would require the ability to at least
   partially disassemble arbitrary x86-64 instructions.)

   On the other hand, the kernel debugger should be able to show
   FPU registers on x86-64.





More information about the Openmcl-devel mailing list