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guile/module/system/vm/frame.scm
Andy Wingo b1b942b74c remove heap links in VM frames, incorporate vm frames into normal backtraces
* doc/ref/vm.texi (Stack Layout): Update to remove references to the
  "heap link".

* gdbinit: Update for "heap link" removal.

* libguile/frames.c:
* libguile/frames.h: Update macros and diagram for removal of "heap
  link". As part of this, we also remove "heap frames", replacing them
  with "vm frames", which are much like the interpreter's debug objects,
  but for VM stacks. That is to say, they don't actually hold the stack
  themselves, just the pointers into stack that's held by a continuation
  (either captured or current).

* libguile/stacks.c (stack_depth, read_frames): Since a "stack" object is
  really a copy of information that comes from somewhere else, it makes
  sense to copy over info from the VM, just as `make-stack' does from the
  evaluator. The tricky bit is to figure out how to interleave VM and
  interpreter frames. We do that by starting in the interpreter, and
  whenever the current frame's procedure is actually a program, we switch
  to the VM stack, switching back when we reach a "bootstrap frame". The
  last bit is hacky, but it does work...
  (is_vm_bootstrap_frame): Hacky predicate to see if a VM frame is a
  bootstrap frame.
  (scm_make_stack): Accept a VM frame in addition to debug frames.
  Probably has some bugs in this case. But in the case that the arg is
  #t (a common case), do the right thing, capturing the top VM frame as
  well, and interleaving those frames appropriately on the stack.

  As an accident, we lost the ability to limit the number of frames in
  the backtrace. We could add that back, but personally I always want
  *all* frames in the trace... Narrowing still works fine, though there
  are some hiccups sometimes -- e.g. an outer cut to a procedure that
  does a tail-call in VM code will never find the cut, as it no longer
  exists in the continuation.

* libguile/vm.h (struct scm_vm): So! Now that we have switched to save
  stacks in the normal make-stack, there's no more need for `this_frame'
  or `last_frame'. On the other hand, we can take this opportunity to fix
  tracing: when we're in a trace hook, we set `trace_frame' on the VM,
  so we know not to fire hooks when we're already in a hook.
  (struct scm_vm_cont): Expose this, as make-stack needs it to make VM
  frames from VM continuations.

* libguile/vm.c (scm_vm_trace_frame): New function, gets the current
  trace frame.
  (vm_mark, make_vm): Hook up the trace frame.
  (vm_dispatch_hook): New hook dispatcher, with a dynwind so it does the
  right thing if the hook exits nonlocally.

* libguile/vm-engine.c (vm_run): No more this_frame in the wind data.

* libguile/vm-engine.h (RUN_HOOK): Run hooks through the dispatcher.
  (ALIGN_AS_NON_IMMEDIATE, POP_LIST_ON_STACK): Remove unused code.
  (NEW_FRAME): Adapt for no HL in the frame.

* libguile/vm-i-system.c (goto/args, mv-call, return, return/values):
  Adapt for no HL in the frame.

* module/system/vm/frame.scm:
* module/system/vm/vm.scm: Beginnings of some reworkings, needs more
  thought.
2008-12-26 18:07:20 +01:00

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;;; Guile VM frame functions
;;; Copyright (C) 2001 Free Software Foundation, Inc.
;;; Copyright (C) 2005 Ludovic Courtès <ludovic.courtes@laas.fr>
;;;
;;; This program is free software; you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 2 of the License, or
;;; (at your option) any later version.
;;;
;;; This program is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
;;; Code:
(define-module (system vm frame)
#:use-module (system vm program)
#:use-module (system vm instruction)
#:use-module ((srfi srfi-1) #:select (fold))
#:export (vm-frame?
vm-frame-program
vm-frame-local-ref vm-frame-local-set!
vm-frame-return-address vm-frame-mv-return-address
vm-frame-dynamic-link vm-frame-external-link
vm-frame-stack
vm-frame-number vm-frame-address
make-frame-chain
print-frame print-frame-chain-as-backtrace
frame-arguments frame-local-variables frame-external-variables
frame-environment
frame-variable-exists? frame-variable-ref frame-variable-set!
frame-object-name
frame-local-ref frame-external-link frame-local-set!
frame-return-address frame-program
frame-dynamic-link heap-frame?))
;; fixme: avoid the dynamic-call?
(dynamic-call "scm_init_frames" (dynamic-link "libguile"))
;;;
;;; Frame chain
;;;
(define vm-frame-number (make-object-property))
(define vm-frame-address (make-object-property))
(define (bootstrap-frame? frame)
(let ((code (program-bytecode (frame-program frame))))
(and (= (uniform-vector-length code) 6)
(= (uniform-vector-ref code 5)
(instruction->opcode 'halt)))))
(define (make-frame-chain frame addr)
(define (make-rest)
(make-frame-chain (frame-dynamic-link frame)
(frame-return-address frame)))
(cond
((or (eq? frame #t) (eq? frame #f))
;; handle #f or #t dynamic links
'())
((bootstrap-frame? frame)
(make-rest))
(else
(let ((chain (make-rest)))
(set! (frame-number frame) (length chain))
(set! (frame-address frame)
(- addr (program-base (frame-program frame))))
(cons frame chain)))))
;;;
;;; Pretty printing
;;;
(define (frame-line-number frame)
(let ((addr (frame-address frame)))
(cond ((assv addr (program-sources (frame-program frame)))
=> source:line)
(else (format #f "@~a" addr)))))
(define (frame-file frame prev)
(let ((sources (program-sources (frame-program frame))))
(if (null? sources)
prev
(or (source:file (car sources))
"current input"))))
(define (print-frame frame)
(format #t "~4@a: ~a ~s\n" (frame-line-number frame) (frame-number frame)
(frame-call-representation frame)))
(define (frame-call-representation frame)
(define (abbrev x)
(cond ((list? x)
(if (> (length x) 4)
(list (abbrev (car x)) (abbrev (cadr x)) '...)
(map abbrev x)))
((pair? x)
(cons (abbrev (car x)) (abbrev (cdr x))))
((vector? x)
(case (vector-length x)
((0) x)
((1) (vector (abbrev (vector-ref x 0))))
(else (vector (abbrev (vector-ref x 0)) '...))))
(else x)))
(abbrev (cons (frame-program-name frame) (frame-arguments frame))))
(define (print-frame-chain-as-backtrace frames)
(if (null? frames)
(format #t "No backtrace available.\n")
(begin
(format #t "VM backtrace:\n")
(fold (lambda (frame file)
(let ((new-file (frame-file frame file)))
(if (not (equal? new-file file))
(format #t "In ~a:\n" new-file))
(print-frame frame)
new-file))
'no-file
frames))))
(define (frame-program-name frame)
(let ((prog (frame-program frame))
(link (frame-dynamic-link frame)))
(or (program-name prog)
(object-property prog 'name)
(and (heap-frame? link) (frame-address link)
(frame-object-name link (1- (frame-address link)) prog))
(hash-fold (lambda (s v d) (if (and (variable-bound? v)
(eq? prog (variable-ref v)))
s d))
prog (module-obarray (current-module))))))
;;;
;;; Frames
;;;
(define (frame-arguments frame)
(let* ((prog (frame-program frame))
(arity (program-arity prog)))
(do ((n (+ (arity:nargs arity) -1) (1- n))
(l '() (cons (frame-local-ref frame n) l)))
((< n 0) l))))
(define (frame-local-variables frame)
(let* ((prog (frame-program frame))
(arity (program-arity prog)))
(do ((n (+ (arity:nargs arity) (arity:nlocs arity) -1) (1- n))
(l '() (cons (frame-local-ref frame n) l)))
((< n 0) l))))
(define (frame-external-variables frame)
(frame-external-link frame))
(define (frame-external-ref frame index)
(list-ref (frame-external-link frame) index))
(define (frame-external-set! frame index val)
(list-set! (frame-external-link frame) index val))
(define (frame-binding-ref frame binding)
(if (binding:extp binding)
(frame-external-ref frame (binding:index binding))
(frame-local-ref frame (binding:index binding))))
(define (frame-binding-set! frame binding val)
(if (binding:extp binding)
(frame-external-set! frame (binding:index binding) val)
(frame-local-set! frame (binding:index binding) val)))
;; FIXME handle #f program-bindings return
(define (frame-bindings frame addr)
(filter (lambda (b) (and (>= addr (binding:start b))
(<= addr (binding:end b))))
(program-bindings (frame-program frame))))
(define (frame-lookup-binding frame addr sym)
(assq sym (reverse (frame-bindings frame addr))))
(define (frame-object-binding frame addr obj)
(do ((bs (frame-bindings frame addr) (cdr bs)))
((or (null? bs) (eq? obj (frame-binding-ref frame (car bs))))
(and (pair? bs) (car bs)))))
(define (frame-environment frame addr)
(map (lambda (binding)
(cons (binding:name binding) (frame-binding-ref frame binding)))
(frame-bindings frame addr)))
(define (frame-variable-exists? frame addr sym)
(if (frame-lookup-binding frame addr sym) #t #f))
(define (frame-variable-ref frame addr sym)
(cond ((frame-lookup-binding frame addr sym) =>
(lambda (binding) (frame-binding-ref frame binding)))
(else (error "Unknown variable:" sym))))
(define (frame-variable-set! frame addr sym val)
(cond ((frame-lookup-binding frame addr sym) =>
(lambda (binding) (frame-binding-set! frame binding val)))
(else (error "Unknown variable:" sym))))
(define (frame-object-name frame addr obj)
(cond ((frame-object-binding frame addr obj) => binding:name)
(else #f)))