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implement breakpoints in the repl

* module/system/vm/trap-state.scm: New file, tracks a VM-specific set of
  traps.
* module/Makefile.am: Add trap-state.scm.

* module/system/repl/error-handling.scm: While in a with-error-handling
  block, bind a default trap handler that invokes a recursive prompt.

* module/system/repl/command.scm: Add a `break' repl meta-command.
This commit is contained in:
Andy Wingo 2010-09-19 11:16:32 +02:00
parent c939b1275b
commit b9badc35ab
4 changed files with 226 additions and 10 deletions

View file

@ -314,6 +314,7 @@ SYSTEM_SOURCES = \
system/vm/program.scm \
system/vm/trace.scm \
system/vm/traps.scm \
system/vm/trap-state.scm \
system/vm/vm.scm \
system/foreign.scm \
system/xref.scm \

View file

@ -27,6 +27,7 @@
#:use-module (system repl debug)
#:use-module (system vm objcode)
#:use-module (system vm program)
#:use-module (system vm trap-state)
#:use-module (system vm vm)
#:autoload (system base language) (lookup-language language-reader)
#:autoload (system vm trace) (vm-trace)
@ -55,7 +56,8 @@
(disassemble x) (disassemble-file xx))
(profile (time t) (profile pr) (trace tr))
(debug (backtrace bt) (up) (down) (frame fr)
(procedure proc) (locals) (error-message error))
(procedure proc) (locals) (error-message error)
(break br))
(inspect (inspect i) (pretty-print pp))
(system (gc) (statistics stat) (option o)
(quit q continue cont))))
@ -476,14 +478,6 @@ Trace execution."
body body* ...)
(format #t "Nothing to debug.~%"))))))))
(define-stack-command (error-message repl)
"error-message
Show error message.
Display the message associated with the error that started the current
debugging REPL."
(format #t "~a~%" (if (string? message) message "No error message")))
(define-stack-command (backtrace repl #:optional count
#:key (width 72) full?)
"backtrace [COUNT] [#:width W] [#:full? F]
@ -566,6 +560,26 @@ Show local variables.
Show locally-bound variables in the selected frame."
(print-locals cur))
(define-stack-command (error-message repl)
"error-message
Show error message.
Display the message associated with the error that started the current
debugging REPL."
(format #t "~a~%" (if (string? message) message "No error message")))
(define-meta-command (break repl (form))
"break PROCEDURE
Break on calls to PROCEDURE.
Starts a recursive prompt when PROCEDURE is called."
(let ((proc (repl-eval repl (repl-parse repl form))))
(if (not (procedure? proc))
(error "Not a procedure: ~a" proc)
(let ((idx (add-trap-at-procedure-call! proc)))
(format #t "Added breakpoint ~a at ~a.~%" idx proc)))))
;;;
;;; Inspection commands

View file

@ -21,6 +21,7 @@
(define-module (system repl error-handling)
#:use-module (system base pmatch)
#:use-module (system vm trap-state)
#:use-module (system repl debug)
#:export (call-with-error-handling
with-error-handling))
@ -56,8 +57,34 @@
(with-error-to-port err
thunk))))))
(define (debug-trap-handler frame trap-idx trap-name)
(let* ((tag (and (pair? (fluid-ref %stacks))
(cdar (fluid-ref %stacks))))
(stack (narrow-stack->vector
(make-stack frame)
;; Take the stack from the given frame, cutting 0
;; frames.
0
;; Narrow the end of the stack to the most recent
;; start-stack.
tag
;; And one more frame, because %start-stack
;; invoking the start-stack thunk has its own frame
;; too.
0 (and tag 1)))
(error-msg (format #f "Trap ~d: ~a" trap-idx trap-name))
(debug (make-debug stack 0 error-msg)))
(with-saved-ports
(lambda ()
(format #t "~a~%" error-msg)
(format #t "Entering a new prompt. ")
(format #t "Type `,bt' for a backtrace or `,q' to continue.\n")
((@ (system repl repl) start-repl) #:debug debug)))))
(catch #t
(lambda () (%start-stack #t thunk))
(lambda ()
(with-default-trap-handler debug-trap-handler
(lambda () (%start-stack #t thunk))))
(case post-error
((report)

View file

@ -0,0 +1,174 @@
;;; trap-state.scm: a set of traps
;; Copyright (C) 2010 Free Software Foundation, Inc.
;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
;;; License as published by the Free Software Foundation; either
;;; version 3 of the License, or (at your option) any later version.
;;;
;;; This library 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
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;; Commentary:
;;;
;;; Code:
(define-module (system vm trap-state)
#:use-module (system base syntax)
#:use-module (system vm vm)
#:use-module (system vm traps)
#:export (list-traps
trap-enabled?
enable-trap!
disable-trap!
delete-trap!
with-default-trap-handler
install-trap-handler!
add-trap-at-procedure-call!))
(define %default-trap-handler (make-fluid))
(define (with-default-trap-handler handler thunk)
(with-fluids ((%default-trap-handler handler))
(thunk)))
(define (default-trap-handler frame idx trap-name)
(if %default-trap-handler
((fluid-ref %default-trap-handler) frame idx trap-name)
(warn "Trap with no handler installed" frame idx trap-name)))
(define-record <trap-wrapper>
index
enabled?
trap
name)
(define-record <trap-state>
(handler default-trap-handler)
(next-idx 0)
(wrappers '()))
(define (trap-wrapper<? t1 t2)
(< (trap-wrapper-index t1) (trap-wrapper-index t2)))
;; The interface that a trap provides to the outside world is that of a
;; procedure, which when called disables the trap, and returns a
;; procedure to enable the trap. Perhaps this is a bit too odd and we
;; should fix this.
(define (enable-trap-wrapper! wrapper)
(if (trap-wrapper-enabled? wrapper)
(error "Trap already enabled" (trap-wrapper-index wrapper))
(let ((trap (trap-wrapper-trap wrapper)))
(set! (trap-wrapper-trap wrapper) (trap))
(set! (trap-wrapper-enabled? wrapper) #t))))
(define (disable-trap-wrapper! wrapper)
(if (not (trap-wrapper-enabled? wrapper))
(error "Trap already disabled" (trap-wrapper-index wrapper))
(let ((trap (trap-wrapper-trap wrapper)))
(set! (trap-wrapper-trap wrapper) (trap))
(set! (trap-wrapper-enabled? wrapper) #f))))
(define (add-trap-wrapper! trap-state wrapper)
(set! (trap-state-wrappers trap-state)
(append (trap-state-wrappers trap-state) (list wrapper)))
(trap-wrapper-index wrapper))
(define (remove-trap-wrapper! trap-state wrapper)
(delq wrapper (trap-state-wrappers trap-state)))
(define (wrapper-at-index trap-state idx)
(let lp ((wrappers (trap-state-wrappers trap-state)))
(cond
((null? wrappers)
(warn "no wrapper found with index in trap-state" idx)
#f)
((= (trap-wrapper-index (car wrappers)) idx)
(car wrappers))
(else
(lp (cdr wrappers))))))
(define (next-index! trap-state)
(let ((idx (trap-state-next-idx trap-state)))
(set! (trap-state-next-idx trap-state) (1+ idx))
idx))
(define (handler-for-index trap-state idx)
(lambda (frame)
(let ((wrapper (wrapper-at-index trap-state idx))
(handler (trap-state-handler trap-state)))
(if wrapper
(handler frame
(trap-wrapper-index wrapper)
(trap-wrapper-name wrapper))))))
;;;
;;; VM-local trap states
;;;
(define *trap-states* (make-weak-key-hash-table))
(define (trap-state-for-vm vm)
(or (hashq-ref *trap-states* vm)
(let ((ts (make-trap-state)))
(hashq-set! *trap-states* vm ts)
(trap-state-for-vm vm))))
(define (the-trap-state)
(trap-state-for-vm (the-vm)))
;;;
;;; API
;;;
(define* (list-traps #:optional (trap-state (the-trap-state)))
(map (lambda (wrapper)
(cons (trap-wrapper-index wrapper)
(trap-wrapper-name wrapper)))
(trap-state-wrappers trap-state)))
(define* (trap-enabled? idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
trap-wrapper-enabled?))
(define* (enable-trap! idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
enable-trap-wrapper!))
(define* (disable-trap! idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
disable-trap-wrapper!))
(define* (delete-trap! idx #:optional (trap-state (the-trap-state)))
(and=> (wrapper-at-index trap-state idx)
(lambda (wrapper)
(if (trap-wrapper-enabled? wrapper)
(disable-trap-wrapper! wrapper))
(remove-trap-wrapper! trap-state wrapper))))
(define* (install-trap-handler! handler #:optional (trap-state (the-trap-state)))
(set! (trap-state-handler trap-state) handler))
(define* (add-trap-at-procedure-call! proc #:optional (trap-state (the-trap-state)))
(let* ((idx (next-index! trap-state))
(trap (trap-at-procedure-call
proc
(handler-for-index trap-state idx))))
(add-trap-wrapper!
trap-state
(make-trap-wrapper
idx #t trap
(format #f "breakpoint at ~a" proc)))))