Index: include/sthread.h
===================================================================
RCS file: /homes/gws/rick/cvs/cse451/simplethreads/include/sthread.h,v
retrieving revision 1.3
retrieving revision 1.4
diff -c -r1.3 -r1.4
*** include/sthread.h	17 Jan 2004 21:21:35 -0000	1.3
--- include/sthread.h	29 Jan 2004 03:45:34 -0000	1.4
***************
*** 26,34 ****
  /* Return the implementation that was selected at compile time. */
  sthread_impl_t sthread_get_impl(void);
  
! /* Choose the implementation to use: pthreads or user-level threads.
!  * Perform any initialization needed. Should be called before any
!  * other sthread functions (sthread_print_impl is excepted).
   */
  void sthread_init();
  
--- 26,35 ----
  /* Return the implementation that was selected at compile time. */
  sthread_impl_t sthread_get_impl(void);
  
! /* 
!  * Perform any initialization needed. Should be called exactly
!  * once, before any other sthread functions (sthread_get_impl 
!  * excepted).
   */
  void sthread_init();
  
Index: lib/sthread_ctx.c
===================================================================
RCS file: /homes/gws/rick/cvs/cse451/simplethreads/lib/sthread_ctx.c,v
retrieving revision 1.8
retrieving revision 1.9
diff -c -r1.8 -r1.9
*** lib/sthread_ctx.c	17 Jan 2004 21:17:34 -0000	1.8
--- lib/sthread_ctx.c	29 Jan 2004 03:45:04 -0000	1.9
***************
*** 88,104 ****
      free(ctx);
  }
  
  /* Save the currently running thread context into old, and
   * start running the context new. Old may be uninitialized,
   * but new must contain a valid saved context. */
  void sthread_switch(sthread_ctx_t *old, sthread_ctx_t *new) {
      /* Call the assembly */
!     Xsthread_switch(&(old->sp), new->sp);
!     
!     /* Do not put anything here. In some cases (namely, the
       * first time a new thread is run), _sthread_switch does
       * not return to this line. (It instead returns to the
       * start function set when the stack was initialized.)
       */
  }
- 
--- 88,114 ----
      free(ctx);
  }
  
+ /* Avoid allowing the compiler to optimize the call to
+  * Xsthread_switch as a tail-call on architectures that support
+  * that (powerpc). */
+ void sthread_anti_optimize(void) __attribute__ ((noinline));
+ void sthread_anti_optimize() {
+ }
+ 
  /* Save the currently running thread context into old, and
   * start running the context new. Old may be uninitialized,
   * but new must contain a valid saved context. */
  void sthread_switch(sthread_ctx_t *old, sthread_ctx_t *new) {
      /* Call the assembly */
!     if (old != new)
! 	Xsthread_switch(&(old->sp), new->sp);
!     /* Do not put anything useful here. In some cases (namely, the
       * first time a new thread is run), _sthread_switch does
       * not return to this line. (It instead returns to the
       * start function set when the stack was initialized.)
+      *
+      * sthread_anti_optimize just forces gcc not to optimize
+      * the call to Xsthread_switch.
       */
+     sthread_anti_optimize();
  }