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abort always dispatches to VM bytecode, to detect same-invocation aborts

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* libguile/control.h:
* libguile/control.c (scm_c_make_prompt): Take an extra arg, a cookie.
  Continuations will be rewindable only if the abort has the same cookie
  as the prompt.
  (scm_at_abort): Redefine from scm_abort, and instead of taking rest
  args, take the abort values as a list directly. Also, don't allow
  rewinding, because we won't support rewinding the C stack with
  delimited continuations.

* libguile/eval.c (eval): Adapt to scm_c_make_prompt change.

* libguile/vm-engine.c (vm_engine): Use vp->cookie to get a unique value
  corresponding to this VM invocation.
* libguile/vm-i-system.c (prompt): Pass the cookie to scm_c_make_prompt.
  (abort): Take an additional tail arg.
* libguile/vm.c (vm_abort): Parse out the abort tail arg. This is for
  the @abort case, or the (apply abort ...) case.
  (make_vm): Initialize the cookie to 0.
* libguile/vm.h (struct scm_vm): Add cookie.

* module/ice-9/boot-9.scm (abort): Define here as a trampoline to
  @abort. Needed to make sure that a call to abort dispatches to a VM
  opcode, so the cookie will be the same.

* module/language/tree-il.scm (<tree-il>): Add a "tail" field to
  <abort>, for the (apply abort ...) case, or (@abort tag args). Should
  be #<const ()> in the normal case. Add support throughout.
* module/language/tree-il/analyze.scm (analyze-lexicals): Add abort-tail
  support here too.

* module/language/tree-il/compile-glil.scm (flatten): Compile the tail
  argument appropriately.
* module/language/tree-il/primitives.scm (*primitive-expand-table*): Fix
  @abort and abort cases to pass the tail arg to make-abort.
This commit is contained in:
Andy Wingo 2010-02-22 21:53:24 +01:00
parent f828ab4f30
commit 2d026f04cc
12 changed files with 71 additions and 50 deletions
Download patch file Download diff file Expand all files Collapse all files

28
libguile/control.c
View file

@ -27,7 +27,8 @@
SCM
scm_c_make_prompt (SCM vm, SCM k, scm_t_uint8 escape_only_p)
scm_c_make_prompt (SCM vm, SCM k, scm_t_uint8 escape_only_p,
scm_t_int64 vm_cookie)
{
scm_t_bits tag;
SCM ret;
@ -42,6 +43,7 @@ scm_c_make_prompt (SCM vm, SCM k, scm_t_uint8 escape_only_p)
regs->fp = SCM_VM_DATA (vm)->fp;
regs->sp = SCM_VM_DATA (vm)->sp;
regs->ip = SCM_VM_DATA (vm)->ip;
regs->cookie = vm_cookie;
SCM_SET_CELL_OBJECT (ret, 1, k);
SCM_SET_CELL_WORD (ret, 2, (scm_t_bits)regs);
@ -109,9 +111,9 @@ scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv)
abort ();
}
SCM_DEFINE (scm_abort, "abort", 1, 0, 1, (SCM tag, SCM args),
SCM_DEFINE (scm_at_abort, "@abort", 2, 0, 0, (SCM tag, SCM args),
"Abort to the nearest prompt with tag @var{tag}.")
#define FUNC_NAME s_scm_abort
#define FUNC_NAME s_scm_at_abort
{
SCM *argv;
size_t i, n;
@ -123,23 +125,11 @@ SCM_DEFINE (scm_abort, "abort", 1, 0, 1, (SCM tag, SCM args),
scm_c_abort (scm_the_vm (), tag, n, argv);
/* Oh, what, you're still here? The abort must have been reinstated. OK, pull
args back from the stack, and keep going... */
/* Oh, what, you're still here? The abort must have been reinstated. Actually,
that's quite impossible, given that we're already in C-land here, so...
abort! */
{
SCM vals = SCM_EOL;
struct scm_vm *vp = SCM_VM_DATA (scm_the_vm ());
n = scm_to_size_t (vp->sp[0]);
for (i = 0; i < n; i++)
vals = scm_cons (vp->sp[-(i + 1)], vals);
/* The continuation call did reset the VM's registers, but then these values
were pushed on; so we need to pop them ourselves. */
vp->sp -= n + 1;
/* FIXME NULLSTACK */
return (scm_is_pair (vals) && scm_is_null (scm_cdr (vals)))
? scm_car (vals) : scm_values (vals);
}
abort ();
}
#undef FUNC_NAME

5
libguile/control.h
View file

@ -37,12 +37,15 @@ struct scm_prompt_registers
scm_t_uint8 *ip;
SCM *sp;
SCM *fp;
scm_t_int64 cookie;
scm_i_jmp_buf regs;
};
SCM_INTERNAL SCM scm_c_make_prompt (SCM vm, SCM k, scm_t_uint8 escape_only_p);
SCM_INTERNAL SCM scm_c_make_prompt (SCM vm, SCM k, scm_t_uint8 escape_only_p,
scm_t_int64 cookie);
SCM_INTERNAL SCM scm_c_abort (SCM vm, SCM tag, size_t n, SCM *argv) SCM_NORETURN;
SCM_INTERNAL SCM scm_at_abort (SCM tag, SCM args) SCM_NORETURN;
SCM_INTERNAL void scm_init_control (void);

2
libguile/eval.c
View file

@ -429,7 +429,7 @@ eval (SCM x, SCM env)
{
SCM prompt, handler, res;
prompt = scm_c_make_prompt (scm_the_vm (), eval (CAR (mx), env), 0);
prompt = scm_c_make_prompt (scm_the_vm (), eval (CAR (mx), env), 0, -1);
handler = eval (CDDR (mx), env);
scm_i_set_dynwinds (scm_cons (prompt, scm_i_dynwinds ()));

2
libguile/vm-engine.c
View file

@ -47,7 +47,9 @@ VM_NAME (SCM vm, SCM program, SCM *argv, int nargs)
SCM *objects = NULL; /* constant objects */
size_t object_count = 0; /* length of OBJECTS */
SCM *stack_limit = vp->stack_limit; /* stack limit address */
SCM dynstate = SCM_I_CURRENT_THREAD->dynamic_state;
scm_t_int64 vm_cookie = vp->cookie++;
/* Internal variables */
int nvalues = 0;

4
libguile/vm-i-system.c
View file

@ -1464,7 +1464,7 @@ VM_DEFINE_INSTRUCTION (83, prompt, "prompt", 4, 2, 0)
/* Push the prompt onto the dynamic stack. The setjmp itself has to be local
to this procedure. */
/* FIXME: do more error checking */
prompt = scm_c_make_prompt (vm, k, escape_only_p);
prompt = scm_c_make_prompt (vm, k, escape_only_p, vm_cookie);
scm_i_set_dynwinds (scm_cons (prompt, scm_i_dynwinds ()));
if (SCM_PROMPT_SETJMP (prompt))
{
@ -1509,7 +1509,7 @@ VM_DEFINE_INSTRUCTION (86, abort, "abort", 1, -1, -1)
{
unsigned n = FETCH ();
SYNC_REGISTER ();
if (sp - n - 1 <= SCM_FRAME_UPPER_ADDRESS (fp))
if (sp - n - 2 <= SCM_FRAME_UPPER_ADDRESS (fp))
goto vm_error_stack_underflow;
vm_abort (vm, n);
/* vm_abort should not return */

17
libguile/vm.c
View file

@ -206,15 +206,25 @@ static void
vm_abort (SCM vm, size_t n)
{
size_t i;
SCM tag, *argv;
ssize_t tail_len;
SCM tag, tail, *argv;
/* FIXME: VM_ENABLE_STACK_NULLING */
tail = *(SCM_VM_DATA (vm)->sp--);
/* NULLSTACK (1) */
tail_len = scm_ilength (tail);
if (tail_len < 0)
abort ();
tag = SCM_VM_DATA (vm)->sp[-n];
argv = alloca (n * sizeof (SCM));
argv = alloca ((n + tail_len) * sizeof (SCM));
for (i = 0; i < n; i++)
argv[i] = SCM_VM_DATA (vm)->sp[-(n-1-i)];
for (; i < n + tail_len; i++, tail = scm_cdr (tail))
argv[i] = scm_car (tail);
/* NULLSTACK (n + 1) */
SCM_VM_DATA (vm)->sp -= n + 1;
scm_c_abort (vm, tag, n, argv);
scm_c_abort (vm, tag, n + tail_len, argv);
}
@ -386,6 +396,7 @@ make_vm (void)
vp->trace_level = 0;
for (i = 0; i < SCM_VM_NUM_HOOKS; i++)
vp->hooks[i] = SCM_BOOL_F;
vp->cookie = 0;
return scm_cell (scm_tc7_vm, (scm_t_bits)vp);
}
#undef FUNC_NAME

1
libguile/vm.h
View file

@ -51,6 +51,7 @@ struct scm_vm {
SCM hooks[SCM_VM_NUM_HOOKS]; /* hooks */
SCM options; /* options */
int trace_level; /* traces enabled if trace_level > 0 */
scm_t_int64 cookie; /* used to detect unrewindable continuations */
};
SCM_API SCM scm_the_vm_fluid;

2
module/ice-9/boot-9.scm
View file

@ -404,6 +404,8 @@
;;; Delimited continuations
(define (prompt tag thunk handler)
(@prompt tag (thunk) handler))
(define (abort tag . args)
(@abort tag args))
;;; apply-to-args is functionally redundant with apply and, worse,
;;; is less general than apply since it only takes two arguments.

39
module/language/tree-il.scm
View file

@ -50,7 +50,7 @@
<dynref> dynref? make-dynref dynref-src dynref-fluid
<dynset> dynset? make-dynset dynset-src dynset-fluid dynset-exp
<prompt> prompt? make-prompt prompt-src prompt-tag prompt-body prompt-handler
<abort> abort? make-abort abort-src abort-tag abort-args
<abort> abort? make-abort abort-src abort-tag abort-args abort-tail
parse-tree-il
unparse-tree-il
@ -86,7 +86,7 @@
(<dynref> fluid)
(<dynset> fluid exp)
(<prompt> tag body handler)
(<abort> tag args))
(<abort> tag args tail))
@ -192,8 +192,8 @@
((prompt ,tag ,body ,handler)
(make-prompt loc (retrans tag) (retrans body) (retrans handler)))
((abort ,tag ,type ,args)
(make-abort loc (retrans tag) type (map retrans args)))
((abort ,tag ,args ,tail)
(make-abort loc (retrans tag) (map retrans args) (retrans tail)))
(else
(error "unrecognized tree-il" exp)))))
@ -276,8 +276,9 @@
((<prompt> tag body handler)
`(prompt ,tag ,(unparse-tree-il body) ,(unparse-tree-il handler)))
((<abort> tag args)
`(abort ,(unparse-tree-il tag) ,(map unparse-tree-il args)))))
((<abort> tag args tail)
`(abort ,(unparse-tree-il tag) ,(map unparse-tree-il args)
,(unparse-tree-il tail)))))
(define (tree-il->scheme e)
(record-case e
@ -374,8 +375,9 @@
,(tree-il->scheme handler)))
((<abort> tag args)
`(@abort ,(tree-il->scheme tag) ,@(map tree-il->scheme args)))))
((<abort> tag args tail)
`(apply abort ,(tree-il->scheme tag) ,@(map tree-il->scheme args)
,(tree-il->scheme tail)))))
(define (tree-il-fold leaf down up seed tree)
@ -444,8 +446,8 @@ This is an implementation of `foldts' as described by Andy Wingo in
(up tree
(loop tag (loop body (loop handler
(down tree result))))))
((<abort> tag args)
(up tree (loop tag (loop args (down tree result)))))
((<abort> tag args tail)
(up tree (loop tail (loop args (loop tag (down tree result))))))
(else
(leaf tree result))))))
@ -518,9 +520,10 @@ This is an implementation of `foldts' as described by Andy Wingo in
(let*-values (((seed ...) (foldts tag seed ...))
((seed ...) (foldts body seed ...)))
(foldts handler seed ...)))
((<abort> tag args)
(let*-values (((seed ...) (foldts tag seed ...)))
(fold-values foldts args seed ...)))
((<abort> tag args tail)
(let*-values (((seed ...) (foldts tag seed ...))
((seed ...) (fold-values foldts args seed ...)))
(foldts tail seed ...)))
(else
(values seed ...)))))
(up tree seed ...)))))))
@ -599,9 +602,10 @@ This is an implementation of `foldts' as described by Andy Wingo in
(set! (prompt-body x) (lp body))
(set! (prompt-handler x) (lp handler)))
((<abort> tag args)
((<abort> tag args tail)
(set! (abort-tag x) (lp tag))
(set! (abort-args x) (map lp args)))
(set! (abort-args x) (map lp args))
(set! (abort-tail x) (lp tail)))
(else #f))
@ -681,9 +685,10 @@ This is an implementation of `foldts' as described by Andy Wingo in
(set! (prompt-body x) (lp body))
(set! (prompt-handler x) (lp handler)))
((<abort> tag args)
((<abort> tag args tail)
(set! (abort-tag x) (lp tag))
(set! (abort-args x) (map lp args)))
(set! (abort-args x) (map lp args))
(set! (abort-tail x) (lp tail)))
(else #f))
x)))

8
module/language/tree-il/analyze.scm
View file

@ -351,8 +351,8 @@
((<prompt> tag body handler)
(lset-union eq? (step tag) (step body) (step handler)))
((<abort> tag args)
(apply lset-union eq? (step tag) (map step args)))
((<abort> tag args tail)
(apply lset-union eq? (step tag) (step tail) (map step args)))
(else '())))
@ -525,8 +525,8 @@
(and cont-var (zero? (hashq-ref refcounts cont-var 0))))
(max (recur tag) (recur body) (recur handler))))
((<abort> tag args)
(apply max (recur tag) (map recur args)))
((<abort> tag args tail)
(apply max (recur tag) (recur tail) (map recur args)))
(else n)))

3
module/language/tree-il/compile-glil.scm
View file

@ -1111,9 +1111,10 @@
(and (eq? context 'drop) (not RA)))
(emit-label POST))))
((<abort> src tag args)
((<abort> src tag args tail)
(comp-push tag)
(for-each comp-push args)
(comp-push tail)
(emit-code src (make-glil-call 'abort (length args)))
;; so, the abort can actually return. if it does, the values will be on
;; the stack, then the MV marker, just as in an MV context.

10
module/language/tree-il/primitives.scm
View file

@ -63,7 +63,7 @@
fluid-ref fluid-set!
@prompt prompt abort
@prompt prompt @abort abort
struct? struct-vtable make-struct struct-ref struct-set!
@ -475,9 +475,15 @@
(else #f)))
(else #f)))
(hashq-set! *primitive-expand-table*
'@abort
(case-lambda
((src tag tail-args)
(make-abort src tag '() tail-args))
(else #f)))
(hashq-set! *primitive-expand-table*
'abort
(case-lambda
((src tag . args)
(make-abort src tag args))
(make-abort src tag args (make-const #f '())))
(else #f)))