[Sbcl-commits] CVS: sbcl/tests foreign-stack-alignment.impure.lisp,NONE,1.1 stack-alignment-offset.c,NONE,1.1

[Nikodemus S. <de...@us...>]

Update of /cvsroot/sbcl/sbcl/tests
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv26445/tests

Added Files:
	foreign-stack-alignment.impure.lisp stack-alignment-offset.c 
Log Message:
0.9.6.26: preserve stack alignment in callbacks on ppc
 * Merge patch from Cyrus Harmon (sbcl-devel 2005-11-04), plus slightly
   twisted tests.

 Note: This has been tested on ppc/darwin and x86/linux, but the new tests
 are active on all platforms -- using alignment requirements I've essentially
 guessed.



--- NEW FILE: foreign-stack-alignment.impure.lisp ---
;;;; Testing the stack alignment of foreign calls. Uses stack-alignment-offset.c.

;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
;;;;
;;;; While most of SBCL is derived from the CMU CL system, the test
;;;; files (like this one) were written from scratch after the fork
;;;; from CMU CL.
;;;;
;;;; This software is in the public domain and is provided with
;;;; absolutely no warranty. See the COPYING and CREDITS files for
;;;; more information.

(use-package :sb-alien)

;;; Callbacks are not part of the exported interface yet -- when they are this can
;;; go away.
(import 'sb-alien::alien-lambda)

(defun run (program &rest arguments)
  (let* ((proc nil)
         (output
          (with-output-to-string (s)
            (setf proc (run-program program arguments
                                    :search (not (eql #\. (char program 0)))
                                    :output s)))))
    (unless (zerop (process-exit-code proc))
      (error "Bad exit code: ~S~%Output:~% ~S"
             (process-exit-code proc)
             output))
    output))

(defvar *required-alignment*
  #+(and ppc darwin) 16
  #+(and ppc linux) 16
  #+(or mips x86-64) 8
  #+x86 4
  #-(or x86 x86-64 mips (and ppc (or darwin linux))) (error "Unknown platform"))

;;;; Build the offset-tool as regular excutable, and run it with
;;;; fork/exec, so that no lisp is on the stack. This is our known-good
;;;; number.

(run "cc" "stack-alignment-offset.c" "-o" "stack-alignment-offset")

(defparameter *good-offset*
  (parse-integer (run "./stack-alignment-offset"
                      (princ-to-string *required-alignment*))))

;;;; Build the tool again, this time as a shared object, and load it

(run "cc" "stack-alignment-offset.c"
     #+darwin "-bundle" #-darwin "-shared"
     "-o" "stack-alignment-offset.so")

(load-shared-object "stack-alignment-offset.so")

(define-alien-routine stack-alignment-offset int (alignment int))
(define-alien-routine trampoline int (callback (function int)))

;;;; Now get the offset by calling from lisp, first with a regular foreign function
;;;; call, then with an intervening callback.

(assert (= *good-offset* (stack-alignment-offset *required-alignment*)))

(assert (= *good-offset* (trampoline (alien-lambda int ()
                                       (stack-alignment-offset *required-alignment*)))))

;;;; success!

--- NEW FILE: stack-alignment-offset.c ---
/* Compiled and run by foreign-stack-alignment.lisp
 *
 * stack_alignment_offset(int) returns the offset of the first argument from a
 * given alignment. run (1) from main, to obtain the good value with no
 * lisp involved (2) from lisp both with and without callbacks to see that
 * we have not messed the alignment.
 *
 * trampoline(int(*)()) is here so that we can get callbacks on the
 * stack too.
 */

/* This software is part of the SBCL system. See the README file for
 * more information.
 *
 * While most of SBCL is derived from the CMU CL system, the test
 * files (like this one) were written from scratch after the fork
 * from CMU CL.
 *
 * This software is in the public domain and is provided with
 * absolutely no warranty. See the COPYING and CREDITS files for
 * more information.
 */

#include <stdio.h>
#include <stdlib.h>

/* <nikodemus> bwahahahaaa!
 * <Xophe> oh dear.  He's finally flipped
 * <lisppaste> nikodemus pasted "stack_alignment_offset" at
 *             http://paste.lisp.org/display/13231
 * <Xophe> heh
 * <Xophe> along with a big / * This code is really twisted * / comment :-)
 * <antifuchs> gods.
 */
extern int
stack_alignment_offset (int alignment)
{
    return ((unsigned int)&alignment) % alignment;
}

extern int
trampoline (int(*callback)())
{
    return callback();
}

int main (int argc, char** argv)
{
    if (argc != 2) {
        printf("wrong number of arguments: %d\n", argc-1);
        return 1;
    }

    printf("%d\n", stack_alignment_offset(atoi(argv[1])));
    return 0;
}