Language/OS - Multiplatform Resource Library/LANGUAGE OS.iso/pcl/src-16f.lha/code/debug-int.lisp

Text File | 1992-08-02 | 146.5 KB | 3,899 lines

;;; -*- Mode: completion; Log: code.log; Package: debug-internals -*-
;;;
;;; **********************************************************************
;;; This code was written as part of the CMU Common Lisp project at
;;; Carnegie Mellon University, and has been placed in the public domain.
;;; If you want to use this code or any part of CMU Common Lisp, please contact
;;; Scott Fahlman or [e-mail].
;;;
(ext:file-comment
  "$Header: debug-int.lisp,v 1.50.1.1 92/08/02 12:02:53 ram Exp $")
;;;
;;; **********************************************************************
;;;
;;; This file contains the implementation of the programmer's interface
;;; to writing debugging tools.
;;;
;;; Written by Bill Chiles and Rob Maclachlan.
;;;

(in-package "DEBUG-INTERNALS" :nicknames '("DI"))


;;; The compiler's debug-source structure is almost exactly what we want, so
;;; just get these symbols and export them.
;;;
(import '(c::debug-source-from c::debug-source-name c::debug-source-created
      c::debug-source-compiled c::debug-source-start-positions
      c::make-debug-source c::debug-source c::debug-source-p))

(export '(debug-variable-name debug-variable-package debug-variable-symbol
      debug-variable-id debug-variable-value debug-variable-validity
      debug-variable-valid-value debug-variable debug-variable-p

      top-frame frame-down frame-up flush-frames-above frame-debug-function
      frame-code-location eval-in-frame return-from-frame frame-catches
      frame-number frame frame-p

      do-debug-function-blocks debug-function-lambda-list
      debug-variable-info-available do-debug-function-variables
      debug-function-symbol-variables ambiguous-debug-variables
      preprocess-for-eval function-debug-function debug-function-function
      debug-function-kind debug-function-name debug-function
      debug-function-p debug-function-start-location

      do-debug-block-locations debug-block-successors debug-block
      debug-block-p debug-block-elsewhere-p

      make-breakpoint activate-breakpoint deactivate-breakpoint
      breakpoint-active-p breakpoint-hook-function breakpoint-info
      breakpoint-kind breakpoint-what breakpoint breakpoint-p
      delete-breakpoint function-end-cookie-valid-p

      code-location-debug-function code-location-debug-block
      code-location-top-level-form-offset code-location-form-number
      code-location-debug-source code-location-kind
      code-location code-location-p code-location-unknown-p code-location=

      debug-source-from debug-source-name debug-source-created
      debug-source-compiled debug-source-root-number
      debug-source-start-positions form-number-translations
      source-path-context debug-source debug-source-p

      debug-condition no-debug-info no-debug-function-returns
      no-debug-blocks lambda-list-unavailable

      debug-error unhandled-condition invalid-control-stack-pointer
      unknown-code-location unknown-debug-variable invalid-value
      ambiguous-variable-name frame-function-mismatch

      set-breakpoint-for-editor set-location-breakpoint-for-editor
      delete-breakpoint-for-editor

      *debugging-interpreter*))



;;;; Conditions.

;;; The interface to building debugging tools signals conditions that prevent
;;; it from adhering to its contract.  These are serious-conditions because the
;;; program using the interface must handle them before it can correctly
;;; continue execution.  These debugging conditions are not errors since it is
;;; no fault of the programmers that the conditions occur.  The interface does
;;; not provide for programs to detect these situations other than calling a
;;; routine that detects them and signals a condition.  For example,
;;; programmers call A which may fail to return successfully due to a lack of
;;; debug information, and there is no B the they could have called to realize
;;; A would fail.  It is not an error to have called A, but it is an error for
;;; the program to then ignore the signal generated by A since it cannot
;;; continue without A's correctly returning a value or performing some
;;; operation.
;;;
;;; Use DEBUG-SIGNAL to signal these conditions.
;;;

(define-condition debug-condition (serious-condition)
  ()
  (:documentation
   "All debug-conditions inherit from this type.  These are serious conditions
    that must be handled, but they are not programmer errors."))

(define-condition no-debug-info (debug-condition)
  ()
  (:documentation "There is absolutely no debugging information available.")
  (:report (lambda (condition stream)
         (declare (ignore condition))
         (fresh-line stream)
         (write-line "No debugging information available." stream))))

(define-condition no-debug-function-returns (debug-condition)
  (debug-function)
  (:documentation
   "The system could not return values from a frame with debug-function since
    it lacked information about returning values.")
  (:report (lambda (condition stream)
         (let ((fun (debug-function-function
             (no-debug-function-returns-debug-function condition))))
           (format stream
               "~&Cannot return values from ~:[frame~;~:*~S~] since ~
            the debug information lacks details about returning ~
            values here."
               fun)))))

(define-condition no-debug-blocks (debug-condition)
  (debug-function)
  (:documentation "The debug-function has no debug-block information.")
  (:report (lambda (condition stream)
         (format stream "~&~S has no debug-block information."
             (no-debug-blocks-debug-function condition)))))

(define-condition no-debug-variables (debug-condition)
  (debug-function)
  (:documentation "The debug-function has no debug-variable information.")
  (:report (lambda (condition stream)
         (format stream "~&~S has no debug-variable information."
             (no-debug-variables-debug-function condition)))))

(define-condition lambda-list-unavailable (debug-condition)
  (debug-function)
  (:documentation
   "The debug-function has no lambda-list since argument debug-variables are
    unavailable.")
  (:report (lambda (condition stream)
         (format stream "~&~S has no lambda-list information available."
             (lambda-list-unavailable-debug-function condition)))))

(define-condition invalid-value (debug-condition)
  ((debug-variable)
   (frame))
  (:report (lambda (condition stream)
         (format stream "~&~S has :invalid or :unknown value in ~S."
             (invalid-value-debug-variable condition)
             (invalid-value-frame condition)))))

(define-condition ambiguous-variable-name (debug-condition)
  ((name)
   (frame))
  (:report (lambda (condition stream)
         (format stream "~&~S names more than one valid variable in ~S."
             (ambiguous-variable-name-name condition)
             (ambiguous-variable-name-frame condition)))))


;;;; Errors and DEBUG-SIGNAL.

;;; The debug-internals code tries to signal all programmer errors as subtypes
;;; of debug-error.  There are calls to ERROR signalling simple-errors, but
;;; these dummy checks in the code and shouldn't come up.
;;;
;;; While under development, this code also signals errors in code branches
;;; that remain unimplemented.
;;;

(define-condition debug-error (error) ()
  (:documentation
   "All programmer errors from using the interface for building debugging
    tools inherit from this type."))

(define-condition unhandled-condition (debug-error)
  ((condition))
  (:report (lambda (condition stream)
         (format stream "~&Unhandled debug-condition:~%~A"
             (unhandled-condition-condition condition)))))

(define-condition unknown-code-location (debug-error)
  ((code-location))
  (:report (lambda (condition stream)
         (format stream "~&Invalid use of an unknown code-location -- ~S."
             (unknown-code-location-code-location condition)))))

(define-condition unknown-debug-variable (debug-error)
  ((debug-variable)
   (debug-function))
  (:report (lambda (condition stream)
         (format stream "~&~S not in ~S."
             (unknown-debug-variable-debug-variable condition)
             (unknown-debug-variable-debug-function condition)))))

(define-condition invalid-control-stack-pointer (debug-error)
  ()
  (:report (lambda (condition stream)
         (declare (ignore condition))
         (fresh-line stream)
         (write-string "Invalid control stack pointer." stream))))

(define-condition frame-function-mismatch (debug-error)
  ((code-location)
   (frame)
   (form))
  (:report (lambda (condition stream)
         (format stream
             "~&Form was preprocessed for ~S,~% but called on ~S:~%  ~S"
             (frame-function-mismatch-code-location condition)
             (frame-function-mismatch-frame condition)
             (frame-function-mismatch-form condition)))))


;;; DEBUG-SIGNAL -- Internal.
;;;
;;; This signals debug-conditions.  If they go unhandled, then signal an
;;; unhandled-condition error.
;;;
;;; ??? Get SIGNAL in the right package!
;;;
(defmacro debug-signal (datum &rest arguments)
  `(let ((condition (make-condition ,datum ,@arguments)))
     (signal condition)
     (error 'unhandled-condition :condition condition)))



;;;; Structures.

;;; Most of these structures model information stored in internal data
;;; structures created by the compiler.  Whenever comments preface an object or
;;; type with "compiler", they refer to the internal compiler thing, not to the
;;; object or type with the same name in the "DI" package.
;;;


;;;
;;; Debug-variables
;;;

;;; These exist for caching data stored in packed binary form in compiler
;;; debug-functions.  Debug-functions store these.
;;;
(defstruct (debug-variable (:print-function print-debug-variable)
               (:constructor nil))
  ;;
  ;; String name of variable.
  (name nil :type simple-string)
  ;;
  ;; String name of package.  Nil when variable's name is uninterned.
  (package nil :type (or null simple-string))
  ;;
  ;; Unique integer identification relative to other variables with the same
  ;; name and package.
  (id 0 :type c::index)
  ;;
  ;; Whether the variable always has a valid value.
  (alive-p nil :type c::boolean))

(defun print-debug-variable (obj str n)
  (declare (ignore n))
  (format str "#<Debug-Variable ~A:~A:~A>"
      (debug-variable-package obj)
      (debug-variable-name obj)
      (debug-variable-id obj)))

(setf (documentation 'debug-variable-name 'function)
  "Returns the name of the debug-variable.  The name is the name of the symbol
   used as an identifier when writing the code.")

(setf (documentation 'debug-variable-package 'function)
  "Returns the package name of the debug-variable.  This is the package name of
   the symbol used as an identifier when writing the code.")

(setf (documentation 'debug-variable-id 'function)
  "Returns the integer that makes debug-variable's name and package name unique
   with respect to other debug-variable's in the same function.")


(defstruct (compiled-debug-variable
        (:include debug-variable)
        (:constructor make-compiled-debug-variable
              (name package id alive-p sc-offset save-sc-offset)))
  ;;
  ;; Storage class and offset.  (unexported).
  (sc-offset nil :type c::sc-offset)
  ;;
  ;; Storage class and offset when saved somewhere.
  (save-sc-offset nil :type (or c::sc-offset null)))

(defstruct (interpreted-debug-variable
        (:include debug-variable
              (alive-p t))
        (:constructor make-interpreted-debug-variable
              (name package ir1-var)))
  ;;
  ;; This is the IR1 structure that holds information about interpreted vars.
  (ir1-var nil :type c::lambda-var))

;;;
;;; Frames
;;;

;;; These represents call-frames on the stack.
;;;
(defstruct (frame (:constructor nil))
  ;;
  ;; Next frame up.  Null when top frame.
  (up nil :type (or frame null))
  ;;
  ;; Previous frame down.  Nil when the bottom frame.  Before computing the
  ;; next frame down, this slot holds the frame pointer to the control stack
  ;; for the given frame.  This lets us get the next frame down and the
  ;; return-pc for that frame.
  (%down :unparsed :type (or frame (member nil :unparsed)))
  ;;
  ;; Debug-function for function whose call this frame represents.
  (debug-function nil :type debug-function)
  ;;
  ;; Code-location to continue upon return to frame.
  (code-location nil :type code-location)
  ;;
  ;; A-list of catch-tags to code-locations.
  (%catches :unparsed :type (or list (member :unparsed)))
  ;;
  ;; Pointer to frame on control stack.  (unexported)
  ;; When is an interpreted-frame, this is an index into the interpreter's stack.
  pointer
  ;;
  ;; This is the frame's number for prompt printing.  Top is zero.
  number)

(setf (documentation 'frame-up 'function)
  "Returns the frame immediately above frame on the stack.  When frame is
   the top of the stack, this returns nil.")

(setf (documentation 'frame-debug-function 'function)
  "Returns the debug-function for the function whose call frame represents.")

(setf (documentation 'frame-code-location 'function)
  "Returns the code-location where the frame's debug-function will continue
   running when program execution returns to this frame.  If someone
   interrupted this frame, the result could be an unknown code-location.")


(defstruct (compiled-frame
        (:include frame)
        (:print-function print-compiled-frame)
        (:constructor make-compiled-frame
              (pointer up debug-function code-location number
               &optional escaped)))
  ;;
  ;; Indicates whether someone interrupted frame.  (unexported).
  ;; If escaped, this is a pointer to the escape frame on the control stack.
  escaped)

(defun print-compiled-frame (obj str n)
  (declare (ignore n))
  (format str "#<Compiled-Frame ~S~:[~;, interrupted~]>"
      (debug-function-name (frame-debug-function obj))
      (compiled-frame-escaped obj)))


(defstruct (interpreted-frame
        (:include frame)
        (:print-function print-interpreted-frame)
        (:constructor make-interpreted-frame
              (pointer up debug-function code-location number
               real-frame closure)))
  ;;
  ;; This points to the compiled-frame for EVAL:INTERNAL-APPLY-LOOP.
  (real-frame nil :type compiled-frame)
  ;;
  ;; This is the closed over data used by the interpreter.
  (closure nil :type simple-vector))

(defun print-interpreted-frame (obj str n)
  (declare (ignore n))
  (format str "#<Interpreted-Frame ~S>"
      (debug-function-name (frame-debug-function obj))))

;;;
;;; Debug-functions
;;;

;;; These exist for caching data stored in packed binary form in compiler
;;; debug-functions.  *compiled-debug-functions* maps a c::debug-function to a
;;; debug-function.  There should only be one debug-function in existence for
;;; any function; that is, all code-locations and other objects that reference
;;; debug-functions point to unique objects.  This is due to the overhead in
;;; cached information.
;;;
(defstruct (debug-function (:print-function print-debug-function))
  ;;
  ;; Some representation of the function arguments.  See
  ;; DEBUG-FUNCTION-LAMBDA-LIST.
  ;; NOTE: must parse vars before parsing arg list stuff.
  (%lambda-list :unparsed)
  ;;
  ;; Cached debug-variable information.  (unexported).
  ;; These are sorted by their name.
  (debug-vars :unparsed :type (or simple-vector null (member :unparsed)))
  ;;
  ;; Cached debug-block information.  This is nil when we have tried to parse
  ;; the packed binary info, but none is available.
  (blocks :unparsed :type (or simple-vector null (member :unparsed)))
  ;;
  ;; The actual function if available.
  (%function :unparsed :type (or null function (member :unparsed))))

(defun print-debug-function (obj str n)
  (declare (ignore n))
  (format str "#<~A-Debug-Function ~S>"
      (etypecase obj
        (compiled-debug-function "Compiled")
        (interpreted-debug-function "Interpreted")
        (bogus-debug-function "Bogus"))
      (debug-function-name obj)))


(defstruct (compiled-debug-function
        (:include debug-function)
        (:constructor %make-compiled-debug-function
              (compiler-debug-fun component)))
  ;;
  ;; Compiler's dumped debug-function information.  (unexported).
  (compiler-debug-fun nil :type c::compiled-debug-function)
  ;;
  ;; Code object.  (unexported).
  component
  ;;
  ;; The :function-start breakpoint (if any) used to facilitate function
  ;; end breakpoints.
  (end-starter nil :type (or null breakpoint)))

;;; This maps c::compiled-debug-functions to compiled-debug-functions, so we
;;; can get at cached stuff and not duplicate compiled-debug-function
;;; structures.
;;;
(defvar *compiled-debug-functions* (make-hash-table :test #'eq))

;;; MAKE-COMPILED-DEBUG-FUNCTION -- Internal.
;;;
;;; Makes a compiled-debug-function for a c::compiler-debug-function and its
;;; component.  This maps the latter to the former in
;;; *compiled-debug-functions*.  If there already is a compiled-debug-function,
;;; then this returns it from *compiled-debug-functions*.
;;;
(defun make-compiled-debug-function (compiler-debug-fun component)
  (or (gethash compiler-debug-fun *compiled-debug-functions*)
      (setf (gethash compiler-debug-fun *compiled-debug-functions*)
        (%make-compiled-debug-function compiler-debug-fun component))))


(defstruct (interpreted-debug-function
        (:include debug-function)
        (:constructor %make-interpreted-debug-function (ir1-lambda)))
  ;;
  ;; This is the ir1 lambda this debug-function represents.
  (ir1-lambda nil :type c::clambda))

(defstruct (bogus-debug-function
        (:include debug-function)
        (:constructor make-bogus-debug-function
              (%name &aux (%lambda-list nil) (debug-vars nil)
                 (blocks nil) (%function nil))))
  %name)

(defvar *ir1-lambda-debug-function* (make-hash-table :test #'eq))

(defun make-interpreted-debug-function (ir1-lambda)
  (let ((home-lambda (c::lambda-home ir1-lambda)))
    (or (gethash home-lambda *ir1-lambda-debug-function*)
    (setf (gethash home-lambda *ir1-lambda-debug-function*)
          (%make-interpreted-debug-function home-lambda)))))

;;;
;;; Debug-blocks.
;;;

;;; These exist for caching data stored in packed binary form in compiler
;;; debug-blocks.
;;;
(defstruct (debug-block (:print-function print-debug-block))
  ;;
  ;; Code-locations where execution continues after this block.
  (successors nil :type list)
  ;;
  ;; This indicates whether the block is a special glob of code shared by
  ;; various functions and tucked away elsewhere in a component.  This kind of
  ;; block has no start code-location.  In an interpreted-debug-block, this is
  ;; always nil.  This slot is in all debug-blocks since it is an exported
  ;; interface.
  (elsewhere-p nil :type c::boolean))

(defun print-debug-block (obj str n)
  (declare (ignore n))
  (format str "#<~A-Debug-Block ~S>"
      (etypecase obj
        (compiled-debug-block "Compiled")
        (interpreted-debug-block "Interpreted"))
      (debug-block-function-name obj)))

(setf (documentation 'debug-block-successors 'function)
  "Returns the list of possible code-locations where execution may continue
   when the basic-block represented by debug-block completes its execution.")

(setf (documentation 'debug-block-elsewhere-p 'function)
  "Returns whether debug-block represents elsewhere code.")


(defstruct (compiled-debug-block (:include debug-block)
                 (:constructor
                  make-compiled-debug-block
                  (code-locations successors elsewhere-p)))
  ;;
  ;; Code-location information for the block.
  (code-locations nil :type simple-vector))

(defstruct (interpreted-debug-block (:include debug-block
                          (elsewhere-p nil))
                    (:constructor %make-interpreted-debug-block
                          (ir1-block)))
  ;;
  ;; This is the IR1 block this debug-block represents.
  (ir1-block nil :type c::cblock)
  ;;
  ;; Code-location information for the block.
  (locations :unparsed :type (or (member :unparsed) simple-vector)))

(defvar *ir1-block-debug-block* (make-hash-table :test #'eq))

;;; MAKE-INTERPRETED-DEBUG-BLOCK -- Internal.
;;;
;;; This makes a debug-block for the interpreter's ir1-block.  If we have it in
;;; the cache, return it.  If we need to make it, then first make debug-blocks
;;; for all the ir1-blocks in ir1-block's home lambda; this makes sure all the
;;; successors of ir1-block have debug-blocks.  We need this to fill in the
;;; resulting debug-block's successors list with debug-blocks, not ir1-blocks.
;;; After making all the possible debug-blocks we'll need to reference, go back
;;; over the list of new debug-blocks and fill in their successor slots with
;;; lists of debug-blocks.  Then look up our argument ir1-block to find its
;;; debug-block since we know we have it now.
;;;
(defun make-interpreted-debug-block (ir1-block)
  (check-type ir1-block c::cblock)
  (let ((res (gethash ir1-block *ir1-block-debug-block*)))
    (or res
    (let ((lambda (c::block-home-lambda ir1-block)))
      (c::do-blocks (block (c::block-component ir1-block))
        (when (eq lambda (c::block-home-lambda block))
          (push (setf (gethash block *ir1-block-debug-block*)
              (%make-interpreted-debug-block block))
            res)))
      (dolist (block res)
        (let* ((successors nil)
           (cblock (interpreted-debug-block-ir1-block block))
           (succ (c::block-succ cblock))
           (valid-succ
            (if (and succ
                 (eq (car succ)
                 (c::component-tail
                  (c::block-component cblock))))
            ()
            succ)))
          (dolist (sblock valid-succ)
        (let ((dblock (gethash sblock *ir1-block-debug-block*)))
          (when dblock
            (push dblock successors))))
          (setf (debug-block-successors block) (nreverse successors))))
      (gethash ir1-block *ir1-block-debug-block*)))))

;;;
;;; Breakpoints.
;;;

;;; This is an internal structure that manages information about a breakpoint
;;; locations.  See *component-breakpoint-offsets*.
;;;
(defstruct (breakpoint-data (:print-function print-breakpoint-data)
                (:constructor make-breakpoint-data
                      (component offset)))
  ;;
  ;; This is the component in which the breakpoint lies.
  component
  ;;
  ;; This is the byte offset into the component.
  (offset nil :type c::index)
  ;;
  ;; The original instruction replaced by the breakpoint.
  (instruction nil :type (or null (unsigned-byte 32)))
  ;;
  ;; This saves the sigmask while we execute the instruction replaced by
  ;; a user break.  When we hit the after-breakpoint, we restore this mask.
  (sigmask nil :type (or null (unsigned-byte 32)))
  ;;
  ;; A list of user breakpoints at this location.
  (breakpoints nil :type list)
  ;;
  ;; An after-breakpoint might be at this location too.
  (after-breakpoint nil :type (or null after-breakpoint)))
;;;
(defun print-breakpoint-data (obj str n)
  (declare (ignore n))
  (format str "#<Breakpoint-Data ~S at ~S>"
      (debug-function-name
       (debug-function-from-pc (breakpoint-data-component obj)
                   (breakpoint-data-offset obj)))
      (breakpoint-data-offset obj)))

(defstruct (breakpoint (:print-function print-breakpoint)
               (:constructor %make-breakpoint
                     (hook-function what kind %info)))
  ;;
  ;; This is the function invoked when execution encounters the breakpoint.  It
  ;; takes a frame, the breakpoint, and optionally a list of values.  Values
  ;; are supplied for :function-end breakpoints as values to return for the
  ;; function containing the breakpoint.  :function-end breakpoint
  ;; hook-functions also take a cookie argument.  See cookie-fun slot.
  (hook-function nil :type function)
  ;;
  ;; Code-location or debug-function.
  (what nil :type (or code-location debug-function))
  ;;
  ;; :code-location, :function-start, or :function-end for that kind of
  ;; breakpoint.  :unknown-return-partner if this is the partner of a
  ;; :code-location breakpoint at an :unknown-return code-location.
  (kind nil :type (member :code-location :function-start :function-end
              :unknown-return-partner))
  ;;
  ;; Status helps the user and the implementation.
  (status :inactive :type (member :active :inactive :deleted))
  ;;
  ;; This is a backpointer to a breakpoint-data.
  (internal-data nil :type (or null breakpoint-data))
  ;;
  ;; With code-locations whose type is :unknown-return, there are really
  ;; two breakpoints: one at the multiple-value entry point, and one at
  ;; the single-value entry point.  This slot holds the breakpoint for the
  ;; other one, or NIL if this isn't at an :unknown-return code location.
  (unknown-return-partner nil :type (or null breakpoint))
  ;;
  ;; :function-end breakpoints use a breakpoint at the :function-start to
  ;; establish the end breakpoint upon function entry.  We do this by frobbing
  ;; the LRA to jump to a special piece of code that breaks and provides the
  ;; return values for the returnee.  This slot points to the start breakpoint,
  ;; so we can activate, deactivate, and delete it.
  (start-helper nil :type (or null breakpoint))
  ;;
  ;; This is a hook users supply to get a dynamically unique cookie for
  ;; identifying :function-end breakpoint executions.  That is, if there is one
  ;; :function-end breakpoint, but there may be multiple pending calls of its
  ;; function on the stack.  This function takes the cookie, and the
  ;; hook-function takes the cookie too.
  (cookie-fun nil :type (or null function))
  ;;
  ;; This slot users can set with whatever information they find useful.
  %info)
;;;
(defun print-breakpoint (obj str n)
  (declare (ignore n))
  (let ((what (breakpoint-what obj)))
    (format str "#<Breakpoint ~S~:[~;~:*~S~]>"
        (etypecase what
          (code-location what)
          (debug-function (debug-function-name what)))
        (etypecase what
          (code-location nil)
          (debug-function (breakpoint-kind obj))))))

(setf (documentation 'breakpoint-hook-function 'function)
  "Returns the breakpoint's function the system calls when execution encounters
   the breakpoint, and it is active.  This is SETF'able.")

(setf (documentation 'breakpoint-what 'function)
  "Returns the breakpoint's what specification.")

(setf (documentation 'breakpoint-kind 'function)
  "Returns the breakpoint's kind specification.")

;;; This is an internal structure.
;;;
(defstruct (after-breakpoint (:print-function print-after-breakpoint)
                 (:constructor
                  make-after-breakpoint
                  (previous-data internal-data &optional partner)))
  ;;
  ;; This is the data for the location which this after-breakpoint follows.
  ;; When execution flows through this after-breakpoint, the breakpoint
  ;; mechanism re-establishes the break instruction at this location, and
  ;; replaces the after-breakpoint's break instruction with the instruction
  ;; that should run as part of the original program.
  (previous-data nil :type breakpoint-data)
  ;;
  ;; This is a backpointer to a breakpoint-data.
  (internal-data nil :type (or null breakpoint-data))
  ;;
  ;; When breakpoint is where a branching instruction used to be, partner is an
  ;; after-breakpoint at the other code location at which execution could have
  ;; gone.  In addition to what is describe for the previous slot, the
  ;; breakpoint mechanism has to remove partner as well as this
  ;; after-breakpoint.
  (partner nil :type (or null after-breakpoint)))

(defun print-after-breakpoint (obj str n)
  (declare (ignore obj n))
  (format str "#<After-Breakpoint ...>"))

;;;
;;; Code-locations.
;;;

(defstruct (code-location (:print-function print-code-location)
              (:constructor nil))
  ;;
  ;; This is the debug-function containing code-location.
  (debug-function nil :type debug-function)
  ;;
  ;; This is initially :unsure.  Upon first trying to access an :unparsed slot,
  ;; if the data is unavailable, then this becomes t, and the code-location is
  ;; unknown.  If the data is available, this becomes nil, a known location.
  ;; We can't use a separate type code-location for this since we must return
  ;; code-locations before we can tell whether they're known or unknown.  For
  ;; example, when parsing the stack, we don't want to unpack all the variables
  ;; and blocks just to make frames.
  (%unknown-p :unsure :type (member t nil :unsure))
  ;;
  ;; This is the debug-block containing code-location.
  ;; Possibly toss this out and just find it in the blocks cache in
  ;; debug-function.
  (%debug-block :unparsed :type (or debug-block (member :unparsed)))
  ;;
  ;; This is the number of forms processed by the compiler or loader before
  ;; the top-level form containing this code-location.
  (%tlf-offset :unparsed :type (or c::index (member :unparsed)))
  ;;
  ;; This is the depth-first number of the node that begins code-location
  ;; within its top-level form.
  (%form-number :unparsed :type (or c::index (member :unparsed))))

(defun print-code-location (obj str n)
  (declare (ignore n))
  (format str "#<~A ~S>"
      (ecase (code-location-unknown-p obj)
        ((nil) (etypecase obj
             (compiled-code-location "Compiled-Code-Location")
             (interpreted-code-location "Interpreted-Code-Location")))
        ((t) "Unknown-Code-Location"))
      (debug-function-name (code-location-debug-function obj))))

(setf (documentation 'code-location-debug-function 'function)
  "Returns the debug-function representing information about the function
   corresponding to the code-location.")


(defstruct (compiled-code-location
        (:include code-location)
        (:constructor make-known-code-location
              (pc debug-function %tlf-offset %form-number
                  %live-set kind &aux (%unknown-p nil)))
        (:constructor make-compiled-code-location (pc debug-function)))
  ;;
  ;; This is an index into debug-function's component slot.
  (pc nil :type c::index)
  ;;
  ;; This is a bit-vector indexed by a variable's position in
  ;; DEBUG-FUNCTION-DEBUG-VARS indicating whether the variable has a valid
  ;; value at this code-location.  (unexported).
  (%live-set :unparsed :type (or simple-bit-vector (member :unparsed)))
  ;;
  ;; (unexported)
  ;; To see c::location-kind, do "(kernel:type-expand 'c::location-kind)".
  (kind :unparsed :type (or (member :unparsed) c::location-kind)))

(defstruct (interpreted-code-location
        (:include code-location
              (%unknown-p nil))
        (:constructor make-interpreted-code-location
              (ir1-node debug-function)))
  ;;
  ;; This is an index into debug-function's component slot.
  (ir1-node nil :type c::node))


;;;
;;; Debug-sources
;;;

(proclaim '(inline debug-source-root-number))
;;;
(defun debug-source-root-number (debug-source)
  "Returns the number of top-level forms processed by the compiler before
   compiling this source.  If this source is uncompiled, this is zero.  This
   may be zero even if the source is compiled since the first form in the first
   file compiled in one compilation, for example, must have a root number of
   zero -- the compiler saw no other top-level forms before it."
  (c::debug-source-source-root debug-source))

(setf (documentation 'c::debug-source-from 'function)
  "Returns an indication of the type of source.  The following are the possible
   values:
      :file    from a file (obtained by COMPILE-FILE if compiled).
      :lisp    from Lisp (obtained by COMPILE if compiled).
      :stream  from a non-file stream.")

(setf (documentation 'c::debug-source-name 'function)
  "Returns the actual source in some sense represented by debug-source, which
   is related to DEBUG-SOURCE-FROM:
      :file    the pathname of the file.
      :lisp    a lambda-expression.
      :stream  some descriptive string that's otherwise useless.")

(setf (documentation 'c::debug-source-created 'function)
  "Returns the universal time someone created the source.  This may be nil if
   it is unavailable.")

(setf (documentation 'c::debug-source-compiled 'function)
  "Returns the time someone compiled the source.  This is nil if the source
   is uncompiled.")

(setf (documentation 'c::debug-source-start-positions 'function)
  "This function returns the file position of each top-level form as an array
   if debug-source is from a :file.  If DEBUG-SOURCE-FROM is :lisp or :stream,
   this returns nil.")

(setf (documentation 'c::debug-source-p 'function)
  "Returns whether object is a debug-source.")



;;;; Frames.

;;; This is used in FIND-ESCAPE-FRAME and with the bogus components and LRAs
;;; used for :function-end breakpoints.  When a components debug-info slot is
;;; :bogus-lra, then the real-lra-slot contains the real component to continue
;;; executing, as opposed to the bogus component which appeared in some frame's
;;; LRA location.
;;;
(defconstant real-lra-slot vm:code-constants-offset)

;;; These are magically converted by the compiler.
;;;
(defun kernel:current-sp () (kernel:current-sp))
(defun kernel:current-fp () (kernel:current-fp))
(defun kernel:stack-ref (s n) (kernel:stack-ref s n))
(defun kernel:%set-stack-ref (s n value) (kernel:%set-stack-ref s n value))
(defun kernel:function-code-header (fun) (kernel:function-code-header fun))
(defun kernel:lra-code-header (lra) (kernel:lra-code-header lra))
(defun kernel:make-lisp-obj (value) (kernel:make-lisp-obj value))
(defun kernel:get-lisp-obj-address (thing) (kernel:get-lisp-obj-address thing))
(defun kernel:function-word-offset (fun) (kernel:function-word-offset fun))
;;;
(defsetf kernel:stack-ref kernel:%set-stack-ref)

(proclaim '(inline cstack-pointer-valid-p))
(defun cstack-pointer-valid-p (x)
  (declare (type system:system-area-pointer x))
  (and (system:sap< x (kernel:current-sp))
       (system:sap<= (alien:alien-sap (alien:extern-alien "control_stack"
                              (* t)))
             x)))

;;; TOP-FRAME -- Public.
;;;
(defun top-frame ()
  "Returns the top frame of the control stack as it was before calling this
   function."
  (multiple-value-bind (fp pc)
               (kernel:%caller-frame-and-pc)
    (possibly-an-interpreted-frame
     (compute-calling-frame (system:int-sap (* (ext:truly-the fixnum fp)
                           vm:word-bytes))
                pc nil)
     nil)))

;;; FLUSH-FRAMES-ABOVE -- public.
;;;
(defun flush-frames-above (frame)
  "Flush all of the frames above FRAME, and renumber all the frames below
   FRAME."
  (setf (frame-up frame) nil)
  (do ((number 0 (1+ number))
       (frame frame (frame-%down frame)))
      ((not (frame-p frame)))
    (setf (frame-number frame) number)))

;;; FRAME-DOWN -- Public.
;;;
;;; We have to access the old-fp and return-pc out of frame and pass them to
;;; COMPUTE-CALLING-FRAME.
;;;
(defun frame-down (frame)
  "Returns the frame immediately below frame on the stack.  When frame is
   the bottom of the stack, this returns nil."
  (let ((down (frame-%down frame)))
    (if (eq down :unparsed)
    (let* ((real (frame-real-frame frame))
           (debug-fun (frame-debug-function real)))
      (setf (frame-%down frame)
        (etypecase debug-fun
          (compiled-debug-function
           (let ((c-d-f (compiled-debug-function-compiler-debug-fun
                 debug-fun)))
             (possibly-an-interpreted-frame
              (compute-calling-frame
               (system:int-sap
            (* (get-context-value
                real vm::ocfp-save-offset
                (c::compiled-debug-function-old-fp c-d-f))
               vm:word-bytes))
               (get-context-value
            real vm::lra-save-offset
            (c::compiled-debug-function-return-pc c-d-f))
               frame)
              frame)))
          (bogus-debug-function
           (let ((fp (frame-pointer real)))
             (compute-calling-frame
              (system:sap-ref-sap fp (* vm::ocfp-save-offset
                        vm:word-bytes))
              (kernel:stack-ref fp vm::lra-save-offset)
              frame))))))
    down)))


;;; GET-CONTEXT-VALUE  --  Internal.
;;;
;;; Get the old FP or return PC out of frame.  Stack-slot is the standard save
;;; location offset on the stack.  Loc is the saved sc-offset describing the
;;; main location.
;;;
(defun get-context-value (frame stack-slot loc)
  (declare (type compiled-frame frame) (type unsigned-byte stack-slot)
       (type c::sc-offset loc))
  (let ((pointer (frame-pointer frame))
    (escaped (compiled-frame-escaped frame)))
    (if escaped
    (sub-access-debug-var-slot pointer loc escaped)
    (kernel:stack-ref pointer stack-slot))))
;;;
(defun (setf get-context-value) (value frame stack-slot loc)
  (declare (type compiled-frame frame) (type unsigned-byte stack-slot)
       (type c::sc-offset loc))
  (let ((pointer (frame-pointer frame))
    (escaped (compiled-frame-escaped frame)))
    (if escaped
    (sub-set-debug-var-slot pointer loc value escaped)
    (setf (kernel:stack-ref pointer stack-slot) value))))


(defvar *debugging-interpreter* nil
  "When set, the debugger foregoes making interpreted-frames, so you can
   debug the functions that manifest the interpreter.")

;;; POSSIBLY-AN-INTERPRETED-FRAME -- Internal.
;;;
;;; This takes a newly computed frame, frame, and the frame above it on the
;;; stack, up-frame, which is possibly nil.  Frame is nil when we hit the
;;; bottom of the control stack.  When frame represents a call to
;;; EVAL::INTERNAL-APPLY-LOOP, we make an interpreted frame to replace frame.
;;; The interpreted frame points to frame.
;;;
(defun possibly-an-interpreted-frame (frame up-frame)
  (if (or (not frame)
      (not (eq (debug-function-name (frame-debug-function frame))
           'eval::internal-apply-loop))
      *debugging-interpreter*
      (compiled-frame-escaped frame))
      frame
      (flet ((get-var (name location)
           (let ((vars (di:ambiguous-debug-variables
                (di:frame-debug-function frame) name)))
         (when (or (null vars) (> (length vars) 1))
           (error "Zero or more than one ~A variable in ~
               EVAL::INTERNAL-APPLY-LOOP?"
              (string-downcase name)))
         (if (eq (debug-variable-validity (car vars) location)
             :valid)
             (car vars)))))
    (let* ((code-loc (frame-code-location frame))
           (ptr-var (get-var "FRAME-PTR" code-loc))
           (node-var (get-var "NODE" code-loc))
           (closure-var (get-var "CLOSURE" code-loc)))
      (if (and ptr-var node-var closure-var)
          (let* ((node (debug-variable-value node-var frame))
             (d-fun (make-interpreted-debug-function
                 (c::block-home-lambda (c::node-block node)))))
        (make-interpreted-frame
         (debug-variable-value ptr-var frame)
         up-frame
         d-fun
         (make-interpreted-code-location node d-fun)
         (frame-number frame)
         frame
         (debug-variable-value closure-var frame)))
          frame)))))


;;; COMPUTE-CALLING-FRAME -- Internal.
;;;
;;; This returns a frame for the one existing in time immediately prior to the
;;; frame referenced by current-fp.  This is current-fp's caller or the next
;;; frame down the control stack.  If there is no down frame, this returns nil
;;; for the bottom of the stack.  Up-frame is the up link for the resulting
;;; frame object, and it is nil when we call this to get the top of the stack.
;;;
;;; The current frame contains the pointer to the temporally previous frame we
;;; want, and the current frame contains the pc at which we will continue
;;; executing upon returning to that previous frame.
;;;
;;; Note: Sometimes LRA is actually a fixnum.  This happens when lisp calls
;;; into C.  In this case, the code object is stored on the stack after the
;;; LRA, and the LRA is the word offset.
;;;
(defun compute-calling-frame (caller lra up-frame)
  (declare (type system:system-area-pointer caller))
  (when (cstack-pointer-valid-p caller)
    (multiple-value-bind
    (code pc-offset escaped)
    (if lra
        (multiple-value-bind
        (word-offset code)
        (if (ext:fixnump lra)
            (let ((fp (frame-pointer up-frame)))
              (values lra
                  (kernel:stack-ref fp (1+ vm::lra-save-offset))))
            (values (kernel:get-header-data lra)
                (kernel:lra-code-header lra)))
          (if code
          (values code
              (* (1+ (- word-offset (kernel:get-header-data code)))
                 vm:word-bytes)
              nil)
          (values :foreign-function
              0
              nil)))
        (find-escaped-frame caller))
      (if (eq (kernel:code-debug-info code) :bogus-lra)
      (let ((real-lra (kernel:code-header-ref code real-lra-slot)))
        (compute-calling-frame caller real-lra up-frame))
      (let ((d-fun (case code
             (:undefined-function
              (make-bogus-debug-function
               "The Undefined Function"))
             (:foreign-function
              (make-bogus-debug-function
               "Foreign function call land"))
             ((nil)
              (make-bogus-debug-function
               "Bogus stack frame"))
             (t
              (debug-function-from-pc code pc-offset)))))
        (make-compiled-frame caller up-frame d-fun
                 (code-location-from-pc d-fun pc-offset
                            escaped)
                 (if up-frame (1+ (frame-number up-frame)) 0)
                 escaped))))))

(defun find-escaped-frame (frame-pointer)
  (declare (type system:system-area-pointer frame-pointer))
  (dotimes (index lisp::*free-interrupt-context-index* (values nil 0 nil))
    (alien:with-alien
    ((lisp-interrupt-contexts (array (* unix:sigcontext) nil) :extern))
      (let ((scp (alien:deref lisp-interrupt-contexts index)))
    (when (= (system:sap-int frame-pointer)
         (vm:sigcontext-register scp vm::cfp-offset))
      (system:without-gcing
       (let ((code (code-object-from-bits
            (vm:sigcontext-register scp vm::code-offset))))
         (when (symbolp code)
           (return (values code 0 scp)))
         (let* ((code-header-len (* (kernel:get-header-data code)
                    vm:word-bytes))
            (pc-offset
             (- (system:sap-int (alien:slot scp 'unix:sc-pc))
            (- (kernel:get-lisp-obj-address code)
               vm:other-pointer-type)
            code-header-len)))
           ;; Check to see if we were executing in a branch delay slot.
           #+pmax  ; pmax only
           (when (logbitp 31 (alien:slot scp 'mips::sc-cause))
         (incf pc-offset vm:word-bytes))
           (unless (<= 0 pc-offset
               (* (kernel:code-header-ref code
                              vm:code-code-size-slot)
                  vm:word-bytes))
         ;; We were in an assembly routine.  Therefore, use the LRA as
         ;; the pc.
         (setf pc-offset
               (- (vm:sigcontext-register scp vm::lra-offset)
              (kernel:get-lisp-obj-address code)
              code-header-len)))
           (return
        (if (eq (kernel:code-debug-info code) :bogus-lra)
            (let ((real-lra (kernel:code-header-ref code
                                real-lra-slot)))
              (values (kernel:lra-code-header real-lra)
                  (kernel:get-header-data real-lra)
                  nil))
            (values code pc-offset scp)))))))))))

;;; CODE-OBJECT-FROM-BITS  --  internal.
;;;
;;; Find the code object corresponding to the object represented by bits and
;;; return it.  We assume bogus functions correspond to the
;;; undefined-function.
;;;
(defun code-object-from-bits (bits)
  (declare (type (unsigned-byte 32) bits))
  (let ((object (kernel:make-lisp-obj bits)))
    (if (functionp object)
    (or (kernel:function-code-header object)
        :undefined-function)
    (let ((lowtag (kernel:get-lowtag object)))
      (if (= lowtag vm:other-pointer-type)
          (let ((type (kernel:get-type object)))
        (cond ((= type vm:code-header-type)
               object)
              ((= type vm:return-pc-header-type)
               (kernel:lra-code-header object))
              (t
               nil))))))))

;;;
;;; Frame utilities.
;;;

;;; DEBUG-FUNCTION-FROM-PC -- Internal.
;;;
;;; This returns a compiled-debug-function for code and pc.  We fetch the
;;; c::debug-info and run down its function-map to get a
;;; c::compiled-debug-function from the pc.  The result only needs to reference
;;; the component, for function constants, and the c::compiled-debug-function.
;;;
(defun debug-function-from-pc (component pc)
  (let ((info (kernel:code-debug-info component)))
    (cond
     ((not info)
      (debug-signal 'no-debug-info))
     ((eq info :bogus-lra)
      (make-bogus-debug-function "Function End Breakpoint"))
     (t
      (let* ((function-map (get-debug-info-function-map info))
         (len (length function-map)))
    (declare (simple-vector function-map))
    (if (= len 1)
        (make-compiled-debug-function (svref function-map 0) component)
        (let ((i 1)
          (elsewhere-p
           (>= pc (c::compiled-debug-function-elsewhere-pc
               (svref function-map 0)))))
          (declare (type c::index i))
          (loop
        (when (or (= i len)
              (< pc (if elsewhere-p
                    (c::compiled-debug-function-elsewhere-pc
                     (svref function-map (1+ i)))
                    (svref function-map i))))
          (return (make-compiled-debug-function
               (svref function-map (1- i))
               component)))
        (incf i 2)))))))))

;;; CODE-LOCATION-FROM-PC -- Internal.
;;;
;;; This returns a code-location for the compiled-debug-function, debug-fun,
;;; and the pc into its code vector.  If we stopped at a breakpoint, find
;;; the code-location for that breakpoint.  Otherwise, make an :unsure code
;;; location, so it can be filled in when we figure out what is going on.
;;;
(defun code-location-from-pc (debug-fun pc escaped)
  (or (and (compiled-debug-function-p debug-fun)
       escaped
       (let ((data (breakpoint-data
            (compiled-debug-function-component debug-fun)
            pc nil)))
         (when (and data (breakpoint-data-breakpoints data))
           (let ((what (breakpoint-what
                (first (breakpoint-data-breakpoints data)))))
         (when (compiled-code-location-p what)
           what)))))
      (make-compiled-code-location pc debug-fun)))

;;; FRAME-CATCHES -- Public.
;;;
(defun frame-catches (frame)
  "Returns an a-list mapping catch tags to code-locations.  These are
   code-locations at which execution would continue with frame as the top
   frame if someone threw to the corresponding tag."
  (let ((catch (system:int-sap (* lisp::*current-catch-block* vm:word-bytes)))
    (res nil)
    (fp (frame-pointer (frame-real-frame frame))))
    (loop
      (when (zerop (sap-int catch)) (return (nreverse res)))
      (when (sap= fp
          (system:int-sap
           (* (kernel:stack-ref catch vm:catch-block-current-cont-slot)
              vm:word-bytes)))
    (let* ((lra (kernel:stack-ref catch vm:catch-block-entry-pc-slot))
           (component
        (kernel:stack-ref catch vm:catch-block-current-code-slot))
           (word-offset (- (1+ (kernel:get-header-data lra))
                   (kernel:get-header-data component))))
      (push (cons (kernel:stack-ref catch vm:catch-block-tag-slot)
              (make-compiled-code-location
               (* word-offset vm:word-bytes)
               (frame-debug-function frame)))
        res)))
      (setf catch
        (system:sap-ref-sap catch
                (* vm:catch-block-previous-catch-slot
                   vm:word-bytes))))))

;;; FRAME-REAL-FRAME -- Internal.
;;;
;;; If an interpreted frame, return the real frame, otherwise frame.
;;;
(defun frame-real-frame (frame)
  (etypecase frame
    (compiled-frame frame)
    (interpreted-frame (interpreted-frame-real-frame frame))))



;;;; Debug-functions.

;;; DO-DEBUG-FUNCTION-BLOCKS -- Public.
;;;
(defmacro do-debug-function-blocks ((block-var debug-function &optional result)
                    &body body)
  "Executes the forms in a context with block-var bound to each debug-block in
   debug-function successively.  Result is an optional form to execute for
   return values, and DO-DEBUG-FUNCTION-BLOCKS returns nil if there is no
   result form.  This signals a no-debug-blocks condition when the
   debug-function lacks debug-block information."
  (let ((blocks (gensym))
    (i (gensym)))
    `(let ((,blocks (debug-function-debug-blocks ,debug-function)))
       (declare (simple-vector ,blocks))
       (dotimes (,i (length ,blocks) ,result)
     (let ((,block-var (svref ,blocks ,i)))
       ,@body)))))

;;; DO-DEBUG-FUNCTION-VARIABLES -- Public.
;;;
(defmacro do-debug-function-variables ((var debug-function &optional result)
                       &body body)
  "Executes body in a context with var bound to each debug-variable in
   debug-function.  This returns the value of executing result (defaults to
   nil).  This may iterate over only some of debug-function's variables or none
   depending on debug policy; for example, possibly the compilation only
   preserved argument information."
  (let ((vars (gensym))
    (i (gensym)))
    `(let ((,vars (debug-function-debug-variables ,debug-function)))
       (declare (type (or null simple-vector) ,vars))
       (if ,vars
       (dotimes (,i (length ,vars) ,result)
         (let ((,var (svref ,vars ,i)))
           ,@body))
       ,result))))

;;; DEBUG-FUNCTION-FUNCTION -- Public.
;;;
(defun debug-function-function (debug-function)
  "Returns the Common Lisp function associated with the debug-function.  This
   returns nil if the function is unavailable or is non-existent as a user
   callable function object."
  (let ((cached-value (debug-function-%function debug-function)))
    (if (eq cached-value :unparsed)
    (setf (debug-function-%function debug-function)
          (etypecase debug-function
        (compiled-debug-function
         (let ((component
            (compiled-debug-function-component debug-function))
               (start-pc
            (c::compiled-debug-function-start-pc
             (compiled-debug-function-compiler-debug-fun
              debug-function))))
           (do ((entry (system:%primitive code-entry-points component)
                   (system:%primitive function-next entry)))
               ((null entry) nil)
             (when (= start-pc
                  (c::compiled-debug-function-start-pc
                   (compiled-debug-function-compiler-debug-fun
                (function-debug-function entry))))
               (return entry)))))
        (interpreted-debug-function
         (c::lambda-eval-info-function
          (c::leaf-info
           (interpreted-debug-function-ir1-lambda debug-function))))
        (bogus-debug-function nil)))
    cached-value)))


;;; DEBUG-FUNCTION-NAME -- Public.
;;;
(defun debug-function-name (debug-function)
  "Returns the name of the function represented by debug-function.  This may
   be a string or a cons; do not assume it is a symbol."
  (etypecase debug-function
    (compiled-debug-function
     (c::compiled-debug-function-name
      (compiled-debug-function-compiler-debug-fun debug-function)))
    (interpreted-debug-function
     (c::lambda-name (interpreted-debug-function-ir1-lambda debug-function)))
    (bogus-debug-function
     (bogus-debug-function-%name debug-function))))


;;; FUNCTION-DEBUG-FUNCTION -- Public.
;;;
(defun function-debug-function (fun)
  "Returns a debug-function that represents debug information for function."
  (if (eval:interpreted-function-p fun)
      (let ((eval-fun (eval::get-eval-function fun)))
    (make-interpreted-debug-function
     (or (eval::eval-function-definition eval-fun)
         (eval::convert-eval-fun eval-fun))))
      (let* ((name (system:%primitive c::function-name fun))
         (component (kernel:function-code-header fun))
         (res (find-if
           #'(lambda (x)
               (and (c::compiled-debug-function-p x)
                (eq (c::compiled-debug-function-name x) name)
                (eq (c::compiled-debug-function-kind x) nil)))
           (get-debug-info-function-map
            (kernel:code-debug-info component)))))
    (if res
        (make-compiled-debug-function res component)
        ;; This used to be the non-interpreted branch, but William wrote it
        ;; to return the debug-fun of fun's XEP instead of fun's debug-fun.
        ;; The above code does this more correctly, but it doesn't get or
        ;; eliminate all appropriate cases.  It mostly works, and probably
        ;; works for all named functions anyway.
        (debug-function-from-pc component
                    (* (- (kernel:function-word-offset fun)
                      (kernel:get-header-data component))
                       vm:word-bytes))))))


;;; DEBUG-FUNCTION-KIND -- Public.
;;;
(defun debug-function-kind (debug-function)
  "Returns the kind of the function which is one of :optional, :external,
   :top-level, :cleanup, nil."
  (etypecase debug-function
    (compiled-debug-function
     (c::compiled-debug-function-kind
      (compiled-debug-function-compiler-debug-fun debug-function)))
    (interpreted-debug-function
     (c::lambda-kind (interpreted-debug-function-ir1-lambda debug-function)))
    (bogus-debug-function
     nil)))

;;; DEBUG-VARIABLE-INFO-AVAILABLE -- Public.
;;;
(defun debug-variable-info-available (debug-function)
  "Returns whether there is any variable information for debug-function."
  (not (not (debug-function-debug-variables debug-function))))

;;; DEBUG-FUNCTION-SYMBOL-VARIABLES -- Public.
;;;
(defun debug-function-symbol-variables (debug-function symbol)
  "Returns a list of debug-variables in debug-function having the same name
   and package as symbol.  If symbol is uninterned, then this returns a list of
   debug-variables without package names and with the same name as symbol.  The
   result of this function is limited to the availability of variable
   information in debug-function; for example, possibly debug-function only
   knows about its arguments."
  (let ((vars (ambiguous-debug-variables debug-function (symbol-name symbol)))
    (package (if (symbol-package symbol)
             (package-name (symbol-package symbol)))))
    (delete-if (if (stringp package)
           #'(lambda (var)
               (let ((p (debug-variable-package var)))
             (or (not (stringp p))
                 (string/= p package))))
           #'(lambda (var)
               (stringp (debug-variable-package var))))
           vars)))

;;; AMBIGUOUS-DEBUG-VARIABLES -- Public.
;;;
(defun ambiguous-debug-variables (debug-function name-prefix-string)
   "Returns a list of debug-variables in debug-function whose names contain
    name-prefix-string as an intial substring.  The result of this function is
    limited to the availability of variable information in debug-function; for
    example, possibly debug-function only knows about its arguments."
  (declare (simple-string name-prefix-string))
  (let ((variables (debug-function-debug-variables debug-function)))
    (declare (type (or null simple-vector) variables))
    (if variables
    (let* ((len (length variables))
           (prefix-len (length name-prefix-string))
           (pos (find-variable name-prefix-string variables len))
           (res nil))
      (when pos
        ;; Find names from pos to variable's len that contain prefix.
        (do ((i pos (1+ i)))
        ((= i len))
          (let* ((var (svref variables i))
             (name (debug-variable-name var))
             (name-len (length name)))
        (declare (simple-string name))
        (when (/= (or (string/= name-prefix-string name
                    :end1 prefix-len :end2 name-len)
                  prefix-len)
              prefix-len)
          (return))
        (push var res)))
        (setq res (nreverse res)))
      res))))

;;; FIND-VARIABLE -- Internal.
;;;
;;; This returns a position in variables for one containing name as an initial
;;; substring.  End is the length of variables if supplied.
;;;
(defun find-variable (name variables &optional end)
  (declare (simple-vector variables)
       (simple-string name))
  (let ((name-len (length name)))
    (position name variables
          :test #'(lambda (x y)
            (let* ((y (debug-variable-name y))
                   (y-len (length y)))
              (declare (simple-string y))
              (and (>= y-len name-len)
                   (string= x y :end1 name-len :end2 name-len))))
          :end (or end (length variables)))))

;;; DEBUG-FUNCTION-LAMBDA-LIST -- Public.
;;;
(defun debug-function-lambda-list (debug-function)
  "Returns a list representing the lambda-list for debug-function.  The list
   has the following structure:
      (required-var1 required-var2
       ...
       (:optional var3 suppliedp-var4)
       (:optional var5)
       ...
       (:rest var6) (:rest var7)
       ...
       (:keyword keyword-symbol var8 suppliedp-var9)
       (:keyword keyword-symbol var10)
       ...
      )
   Each VARi is a debug-variable; however it may be the symbol :deleted it
   is unreferenced in debug-function.  This signals a lambda-list-unavaliable
   condition when there is no argument list information."
  (etypecase debug-function
    (compiled-debug-function
     (compiled-debug-function-lambda-list debug-function))
    (interpreted-debug-function
     (interpreted-debug-function-lambda-list debug-function))
    (bogus-debug-function
     nil)))

;;; INTERPRETED-DEBUG-FUNCTION-LAMBDA-LIST -- Internal.
;;;
;;; The hard part is when the lambda-list is unparsed.  If it is unparsed,
;;; and all the arguments are required, this is still pretty easy; just
;;; whip the appropriate debug-variables into a list.  Otherwise, we have
;;; to pick out the funny arguments including any suppliedp variables.  In
;;; this situation, the ir1-lambda is an external entry point that takes
;;; arguments users really pass in.  It looks at those and computes defaults
;;; and suppliedp variables, ultimately passing everything defined as a
;;; a parameter to the real function as final arguments.  If this has to
;;; compute the lambda list, it caches it in debug-function.
;;;
(defun interpreted-debug-function-lambda-list (debug-function)
  (let ((lambda-list (debug-function-%lambda-list debug-function))
    (debug-vars (debug-function-debug-variables debug-function))
    (ir1-lambda (interpreted-debug-function-ir1-lambda debug-function))
    (res nil))
    (if (eq lambda-list :unparsed)
    (flet ((frob (v debug-vars)
         (if (c::lambda-var-refs v)
             (find v debug-vars
               :key #'interpreted-debug-variable-ir1-var)
             :deleted)))
      (let ((xep-args (c::lambda-optional-dispatch ir1-lambda)))
        (if (and xep-args
             (eq (c::optional-dispatch-main-entry xep-args) ir1-lambda))
        ;;
        ;; There are rest, optional, keyword, and suppliedp vars.
        (let ((final-args (c::lambda-vars ir1-lambda)))
          (dolist (xep-arg (c::optional-dispatch-arglist xep-args))
            (let ((info (c::lambda-var-arg-info xep-arg))
              (final-arg (pop final-args)))
              (cond (info
                 (case (c::arg-info-kind info)
                   (:required
                (push (frob final-arg debug-vars) res))
                   (:keyword
                (push (list :keyword
                        (c::arg-info-keyword info)
                        (frob final-arg debug-vars))
                      res))
                   (:rest
                (push (list :rest (frob final-arg debug-vars))
                      res))
                   (:optional
                (push (list :optional
                        (frob final-arg debug-vars))
                      res)))
                 (when (c::arg-info-supplied-p info)
                   (nconc
                (car res)
                (list (frob (pop final-args) debug-vars)))))
                (t
                 (push (frob final-arg debug-vars) res)))))
          (setf (debug-function-%lambda-list debug-function)
            (nreverse res)))
        ;;
        ;; All required args, so return them in a list.
        (dolist (v (c::lambda-vars ir1-lambda)
               (setf (debug-function-%lambda-list debug-function)
                 (nreverse res)))
          (push (frob v debug-vars) res)))))
    ;;
    ;; Everything's unparsed and cached, so return it.
    lambda-list)))

;;; COMPILED-DEBUG-FUNCTION-LAMBDA-LIST -- Internal.
;;;
;;; If this has to compute the lambda list, it caches it in debug-function.
;;;
(defun compiled-debug-function-lambda-list (debug-function)
  (let ((lambda-list (debug-function-%lambda-list debug-function)))
    (cond ((eq lambda-list :unparsed)
       (multiple-value-bind
           (args argsp)
           (parse-compiled-debug-function-lambda-list debug-function)
         (setf (debug-function-%lambda-list debug-function) args)
         (if argsp
         args
         (debug-signal 'lambda-list-unavailable
                   :debug-function debug-function))))
      (lambda-list)
      ((bogus-debug-function-p debug-function)
       nil)
      ((c::compiled-debug-function-arguments
        (compiled-debug-function-compiler-debug-fun
         debug-function))
       ;; If the packed information is there (whether empty or not) as
       ;; opposed to being nil, then returned our cached value (nil).
       nil)
      (t
       ;; Our cached value is nil, and the packed lambda-list information
       ;; is nil, so we don't have anything available.
       (debug-signal 'lambda-list-unavailable
             :debug-function debug-function)))))

;;; PARSE-COMPILED-DEBUG-FUNCTION-LAMBDA-LIST -- Internal.
;;;
;;; COMPILED-DEBUG-FUNCTION-LAMBDA-LIST calls this when a
;;; compiled-debug-function has no lambda-list information cached.  It returns
;;; the lambda-list as the first value and whether there was any argument
;;; information as the second value.  Therefore, nil and t means there were no
;;; arguments, but nil and nil means there was no argument information.
;;;
(defun parse-compiled-debug-function-lambda-list (debug-function)
  (let ((args (c::compiled-debug-function-arguments
           (compiled-debug-function-compiler-debug-fun
        debug-function))))
    (cond
     ((not args)
      (values nil nil))
     ((eq args :minimal)
      (values (coerce (debug-function-debug-variables debug-function) 'list)
          t))
     (t
      (let ((vars (debug-function-debug-variables debug-function))
        (i 0)
        (len (length args))
        (res nil)
        (optionalp nil))
    (declare (type (or null simple-vector) vars))
    (loop
      (when (>= i len) (return))
      (let ((ele (aref args i)))
        (cond
         ((symbolp ele)
          (case ele
        (c::deleted
         ;; Deleted required arg at beginning of args array.
         (push :deleted res))
        (c::optional-args
         (setf optionalp t))
        (c::supplied-p
         ;; supplied-p var immediately following keyword or optional.
         ;; Stick the extra var in the result element representing
         ;; the keyword or optional, which is the previous one.
         (nconc (car res)
            (list (compiled-debug-function-lambda-list-var
                   args (incf i) vars))))
        (c::rest-arg
         (push (list :rest
                 (compiled-debug-function-lambda-list-var
                  args (incf i) vars))
               res))
        (c::more-arg
         (error "I thought I'd never see a more-arg?"))
        (t
         ;; Keyword arg.
         (push (list :keyword
                 ele
                 (compiled-debug-function-lambda-list-var
                  args (incf i) vars))
               res))))
         (optionalp
          ;; We saw an optional marker, so the following non-symbols are
          ;; indexes indicating optional variables.
          (push (list :optional (svref vars ele)) res))
         (t
          ;; Required arg at beginning of args array.
          (push (svref vars ele) res))))
      (incf i))
    (values (nreverse res) t))))))

;;; COMPILED-DEBUG-FUNCTION-LAMBDA-LIST-VAR -- Internal
;;;
;;; Used in COMPILED-DEBUG-FUNCTION-LAMBDA-LIST.
;;;
(defun compiled-debug-function-lambda-list-var (args i vars)
  (declare (type (simple-array * (*)) args)
       (simple-vector vars))
  (let ((ele (aref args i)))
    (cond ((not (symbolp ele)) (svref vars ele))
      ((eq ele 'c::deleted) :deleted)
      (t (error "Malformed arguments description.")))))

;;; COMPILED-DEBUG-FUNCTION-DEBUG-INFO -- Internal.
;;;
(defun compiled-debug-function-debug-info (debug-fun)
  (kernel:code-debug-info (compiled-debug-function-component debug-fun)))



;;;; Unpacking variable and basic block data.

(defvar *parsing-buffer*
  (make-array 20 :adjustable t :fill-pointer t))
(defvar *other-parsing-buffer*
  (make-array 20 :adjustable t :fill-pointer t))
;;;
;;; WITH-PARSING-BUFFER -- Internal.
;;;
;;; PARSE-DEBUG-BLOCKS, PARSE-DEBUG-VARIABLES and UNCOMPACT-FUNCTION-MAP use
;;; this to unpack binary encoded information.  It returns the values returned
;;; by the last form in body.
;;;
;;; This binds buffer-var to *parsing-buffer*, makes sure it starts at element
;;; zero, and makes sure if we unwind, we nil out any set elements for GC
;;; purposes.
;;;
;;; This also binds other-var to *other-parsing-buffer* when it is supplied,
;;; making sure it starts at element zero and that we nil out any elements if
;;; we unwind.
;;;
;;; This defines the local macro RESULT that takes a buffer, copies its
;;; elements to a resulting simple-vector, nil's out elements, and restarts
;;; the buffer at element zero.  RESULT returns the simple-vector.
;;;
(eval-when (compile eval)
(defmacro with-parsing-buffer ((buffer-var &optional other-var) &body body)
  (let ((len (gensym))
    (res (gensym)))
    `(unwind-protect
     (let ((,buffer-var *parsing-buffer*)
           ,@(if other-var `((,other-var *other-parsing-buffer*))))
       (setf (fill-pointer ,buffer-var) 0)
       ,@(if other-var `((setf (fill-pointer ,other-var) 0)))
       (macrolet ((result (buf)
            `(let* ((,',len (length ,buf))
                (,',res (make-array ,',len)))
               (replace ,',res ,buf :end1 ,',len :end2 ,',len)
               (fill ,buf nil :end ,',len)
               (setf (fill-pointer ,buf) 0)
               ,',res)))
         ,@body))
     (fill *parsing-buffer* nil)
     ,@(if other-var `((fill *other-parsing-buffer* nil))))))
) ;eval-when


;;; DEBUG-FUNCTION-DEBUG-BLOCKS -- Internal.
;;;
;;; The argument is a debug internals structure.  This returns the debug-blocks
;;; for debug-function, regardless of whether we have unpacked them yet.  It
;;; signals a no-debug-blocks condition if it can't return the blocks.
;;;
(defun debug-function-debug-blocks (debug-function)
  (let ((blocks (debug-function-blocks debug-function)))
    (cond ((eq blocks :unparsed)
       (setf (debug-function-blocks debug-function)
         (parse-debug-blocks debug-function))
       (unless (debug-function-blocks debug-function)
         (debug-signal 'no-debug-blocks
               :debug-function debug-function))
       (debug-function-blocks debug-function))
      (blocks)
      (t
       (debug-signal 'no-debug-blocks
             :debug-function debug-function)))))

;;; PARSE-DEBUG-BLOCKS -- Internal.
;;;
;;; This returns a simple-vector of debug-blocks or nil.  Nil indicates there
;;; was no basic block information.
;;;
(defun parse-debug-blocks (debug-function)
  (etypecase debug-function
    (compiled-debug-function
     (parse-compiled-debug-blocks debug-function))
    (bogus-debug-function
     (debug-signal 'no-debug-blocks :debug-function debug-function))
    (interpreted-debug-function
     (parse-interpreted-debug-blocks debug-function))))


;;; PARSE-COMPILED-DEBUG-BLOCKS -- Internal.
;;;
;;; This does some of the work of PARSE-DEBUG-BLOCKS.
;;;
(defun parse-compiled-debug-blocks (debug-function)
  (let* ((debug-fun (compiled-debug-function-compiler-debug-fun debug-function))
     (var-count (length (debug-function-debug-variables debug-function)))
     (blocks (c::compiled-debug-function-blocks debug-fun))
     ;; 8 is a hard-wired constant in the compiler for the element size of
     ;; the packed binary representation of the blocks data.
     (live-set-len (ceiling var-count 8))
     (tlf-number (c::compiled-debug-function-tlf-number debug-fun)))
    (unless blocks (return-from parse-compiled-debug-blocks nil))
    (macrolet ((aref+ (a i) `(prog1 (aref ,a ,i) (incf ,i))))
      (with-parsing-buffer (blocks-buffer locations-buffer)
    (let ((i 0)
          (len (length blocks))
          (last-pc 0))
      (loop
        (when (>= i len) (return))
        (let ((succ-and-flags (aref+ blocks i))
          (successors nil))
          (declare (type (unsigned-byte 8) succ-and-flags)
               (list successors))
          (dotimes (k (ldb c::compiled-debug-block-nsucc-byte
                   succ-and-flags))
        (push (c::read-var-integer blocks i) successors))
          (let* ((locations
              (dotimes (k (c::read-var-integer blocks i)
                  (result locations-buffer))
            (let ((kind (svref c::compiled-code-location-kinds
                       (aref+ blocks i)))
                  (pc (+ last-pc (c::read-var-integer blocks i)))
                  (tlf-offset (or tlf-number
                          (c::read-var-integer blocks i)))
                  (form-number (c::read-var-integer blocks i))
                  (live-set (c::read-packed-bit-vector
                     live-set-len blocks i)))
              (vector-push-extend (make-known-code-location
                           pc debug-function tlf-offset
                           form-number live-set kind)
                          locations-buffer)
              (setf last-pc pc))))
             (block (make-compiled-debug-block
                 locations successors
                 (not (zerop (logand
                      c::compiled-debug-block-elsewhere-p
                      succ-and-flags))))))
        (vector-push-extend block blocks-buffer)
        (dotimes (k (length locations))
          (setf (code-location-%debug-block (svref locations k))
            block))))))
    (let ((res (result blocks-buffer)))
      (declare (simple-vector res))
      (dotimes (i (length res))
        (let* ((block (svref res i))
           (succs nil))
          (dolist (ele (debug-block-successors block))
        (push (svref res ele) succs))
          (setf (debug-block-successors block) succs)))
      res)))))

;;; PARSE-INTERPRETED-DEBUG-BLOCKS -- Internal.
;;;
;;; This does some of the work of PARSE-DEBUG-BLOCKS.
;;;
(defun parse-interpreted-debug-blocks (debug-function)
  (let ((ir1-lambda (interpreted-debug-function-ir1-lambda debug-function)))
    (with-parsing-buffer (buffer)
      (c::do-blocks (block (c::block-component
                (c::node-block (c::lambda-bind ir1-lambda))))
    (when (eq ir1-lambda (c::block-home-lambda block))
      (vector-push-extend (make-interpreted-debug-block block) buffer)))
      (result buffer))))


;;; DEBUG-FUNCTION-DEBUG-VARIABLES -- Internal.
;;;
;;; The argument is a debug internals structure.  This returns nil if there is
;;; no variable information.  It returns an empty simple-vector if there were
;;; no locals in the function.  Otherwise it returns a simple-vector of
;;; debug-variables.
;;;
(defun debug-function-debug-variables (debug-function)
  (let ((vars (debug-function-debug-vars debug-function)))
    (if (eq vars :unparsed)
    (setf (debug-function-debug-vars debug-function)
          (etypecase debug-function
        (compiled-debug-function
         (parse-compiled-debug-variables debug-function))
        (bogus-debug-function nil)
        (interpreted-debug-function
         (parse-interpreted-debug-variables debug-function))))
    vars)))


;;; PARSE-INTERPRETED-DEBUG-VARIABLES -- Internal.
;;;
;;; This grabs all the variables from debug-fun's ir1-lambda, from the IR1
;;; lambda vars, and all of it's LET's.  Each LET is an IR1 lambda.  For each
;;; variable, we make an interpreted-debug-variable.  We then SORT all the
;;; variables by name.  Then we go through, and for any duplicated names we
;;; distinguish the interpreted-debug-variables by setting their id slots to a
;;; distinct number.
;;;
(defun parse-interpreted-debug-variables (debug-fun)
  (let* ((ir1-lambda (interpreted-debug-function-ir1-lambda debug-fun))
     (vars (flet ((frob (ir1-lambda buf)
            (dolist (v (c::lambda-vars ir1-lambda))
              (vector-push-extend
               (let* ((id (c::leaf-name v))
                  (pkg (symbol-package id)))
                 (make-interpreted-debug-variable
                  (symbol-name id)
                  (when pkg (package-name pkg))
                  v))
               buf))))
         (with-parsing-buffer (buf)
           (frob ir1-lambda buf)
           (dolist (let-lambda (c::lambda-lets ir1-lambda))
             (frob let-lambda buf))
           (result buf)))))
    (declare (simple-vector vars))
    (sort vars #'string< :key #'debug-variable-name)
    (let ((len (length vars)))
      (when (> len 1)
    (let ((i 0)
          (j 1))
      (block PUNT
        (loop
          (let* ((var-i (svref vars i))
             (var-j (svref vars j))
             (name (debug-variable-name var-i)))
        (when (string= name (debug-variable-name var-j))
          (let ((count 1))
            (loop
              (setf (debug-variable-id var-j) count)
              (when (= (incf j) len) (return-from PUNT))
              (setf var-j (svref vars j))
              (when (string/= name (debug-variable-name var-j))
            (return))
              (incf count))))
        (setf i j)
        (incf j)
        (when (= j len) (return))))))))
    vars))


;;; ASSIGN-MINIMAL-VAR-NAMES -- Internal.
;;;
;;; Vars is the parsed variables for a minimal debug function.  We need to
;;; assign names of the form ARG-NNN.  We must pad with leading zeros, since
;;; the arguments must be in alphabetical order.
;;;
(defun assign-minimal-var-names (vars)
  (declare (simple-vector vars))
  (let* ((len (length vars))
     (width (length (format nil "~D" (1- len)))))
    (dotimes (i len)
      (setf (compiled-debug-variable-name (svref vars i))
        (format nil "ARG-~V,'0D" width i)))))


;;; PARSE-COMPILED-DEBUG-VARIABLES -- Internal.
;;;
;;; This parses the packed binary representation of debug-variables from
;;; debug-function's c::compiled-debug-function.
;;;
(defun parse-compiled-debug-variables (debug-function)
  (let* ((debug-fun (compiled-debug-function-compiler-debug-fun debug-function))
     (packed-vars (c::compiled-debug-function-variables debug-fun))
     (default-package (c::compiled-debug-info-package
               (compiled-debug-function-debug-info debug-function)))
     (args-minimal (eq (c::compiled-debug-function-arguments debug-fun)
               :minimal)))
    (unless packed-vars
      (return-from parse-compiled-debug-variables nil))
    (when (zerop (length packed-vars))
      ;; Return a simple-vector not whatever packed-vars may be.
      (return-from parse-compiled-debug-variables '#()))
    (let ((i 0)
      (len (length packed-vars)))
      (with-parsing-buffer (buffer)
    (loop
      ;; The routines in the "C" package are macros that advance the
      ;; index.
      (let* ((flags (prog1 (aref packed-vars i) (incf i)))
         (minimal (logtest c::compiled-debug-variable-minimal-p flags))
         (deleted (logtest c::compiled-debug-variable-deleted-p flags))
         (name (if minimal "" (c::read-var-string packed-vars i)))
         (package (cond
               (minimal default-package)
               ((logtest c::compiled-debug-variable-packaged
                     flags)
                (c::read-var-string packed-vars i))
               ((logtest c::compiled-debug-variable-uninterned
                     flags)
                nil)
               (t
                default-package)))
          (id (if (logtest c::compiled-debug-variable-id-p flags)
              (c::read-var-integer packed-vars i)
              0))
          (sc-offset
           (if deleted 0 (c::read-var-integer packed-vars i)))
          (save-sc-offset
           (if (logtest c::compiled-debug-variable-save-loc-p flags)
               (c::read-var-integer packed-vars i)
               nil)))
        (assert (not (and args-minimal (not minimal))))
        (vector-push-extend
         (make-compiled-debug-variable
          name package id
          (logtest c::compiled-debug-variable-environment-live flags)
          sc-offset save-sc-offset)
         buffer))
      (when (>= i len) (return)))
    (let ((res (result buffer)))
      (when args-minimal
        (assign-minimal-var-names res))
      res)))))


;;;; Unpacking minimal debug functions.

(eval-when (compile eval)

;;; MAKE-UNCOMPACTED-DEBUG-FUN -- Internal.
;;;
;;; Sleazoid "macro" to keep our indentation sane in UNCOMPACT-FUNCTION-MAP.
;;;
(defmacro make-uncompacted-debug-fun ()
  '(c::make-compiled-debug-function
    :name
    (let ((base (ecase (ldb c::minimal-debug-function-name-style-byte
                options)
          (#.c::minimal-debug-function-name-symbol
           (intern (c::read-var-string map i)
               (c::compiled-debug-info-package info)))
          (#.c::minimal-debug-function-name-packaged
           (let ((pkg (c::read-var-string map i)))
             (intern (c::read-var-string map i) pkg)))
          (#.c::minimal-debug-function-name-uninterned
           (make-symbol (c::read-var-string map i)))
          (#.c::minimal-debug-function-name-component
           (c::compiled-debug-info-name info)))))
      (if (logtest flags c::minimal-debug-function-setf-bit)
      `(setf ,base)
      base))
    :kind (svref c::minimal-debug-function-kinds
         (ldb c::minimal-debug-function-kind-byte options))
    :variables
    (when vars-p
      (let ((len (c::read-var-integer map i)))
    (prog1 (subseq map i (+ i len))
      (incf i len))))
    :arguments (when vars-p :minimal)
    :returns
    (ecase (ldb c::minimal-debug-function-returns-byte options)
      (#.c::minimal-debug-function-returns-standard
       :standard)
      (#.c::minimal-debug-function-returns-fixed
       :fixed)
      (#.c::minimal-debug-function-returns-specified
       (with-parsing-buffer (buf)
     (dotimes (idx (c::read-var-integer map i))
       (vector-push-extend (c::read-var-integer map i) buf))
     (result buf))))
    :return-pc (c::read-var-integer map i)
    :old-fp (c::read-var-integer map i)
    :nfp (when (logtest flags c::minimal-debug-function-nfp-bit)
       (c::read-var-integer map i))
    :start-pc
    (progn
      (setq code-start-pc (+ code-start-pc (c::read-var-integer map i)))
      (+ code-start-pc (c::read-var-integer map i)))
    :elsewhere-pc
    (setq elsewhere-pc (+ elsewhere-pc (c::read-var-integer map i)))))

) ;EVAL-WHEN (compile eval)

;;; UNCOMPACT-FUNCTION-MAP  --  Internal
;;;
;;;    Return a normal function map derived from a minimal debug info function
;;; map.  This involves looping parsing minimal-debug-functions and then
;;; building a vector out of them.
;;;
(defun uncompact-function-map (info)
  (declare (type c::compiled-debug-info info))
  (let* ((map (c::compiled-debug-info-function-map info))
     (i 0)
     (len (length map))
     (code-start-pc 0)
     (elsewhere-pc 0))
    (declare (type (simple-array (unsigned-byte 8) (*)) map))
    (ext:collect ((res))
      (loop
    (when (= i len) (return))
    (let* ((options (prog1 (aref map i) (incf i)))
           (flags (prog1 (aref map i) (incf i)))
           (vars-p (logtest flags c::minimal-debug-function-variables-bit))
           (dfun (make-uncompacted-debug-fun)))
      (res code-start-pc)
      (res dfun)))

      (coerce (cdr (res)) 'simple-vector))))


;;; This variable maps minimal debug-info function maps to an unpacked version
;;; thereof.
;;;
(defvar *uncompacted-function-maps* (make-hash-table :test #'eq))

;;; GET-DEBUG-INFO-FUNCTION-MAP  --  Internal
;;;
;;;    Return a function-map for a given compiled-debug-info object.  If the
;;; info is minimal, and has not been parsed, then parse it.
;;;
(defun get-debug-info-function-map (info)
  (declare (type c::compiled-debug-info info))
  (let ((map (c::compiled-debug-info-function-map info)))
    (if (simple-vector-p map)
    map
    (or (gethash map *uncompacted-function-maps*)
        (setf (gethash map *uncompacted-function-maps*)
          (uncompact-function-map info))))))


;;;; Code-locations.

;;; CODE-LOCATION-UNKNOWN-P -- Public.
;;;
;;; If we're sure of whether code-location is known, return t or nil.  If we're
;;; :unsure, then try to fill in the code-location's slots.  This determines
;;; whether there is any debug-block information, and if code-location is
;;; known.
;;;
;;; ??? IF this conses closures every time it's called, then break off the
;;; :unsure part to get the HANDLER-CASE into another function.
;;;
(defun code-location-unknown-p (basic-code-location)
  "Returns whether basic-code-location is unknown.  It returns nil when the
   code-location is known."
  (ecase (code-location-%unknown-p basic-code-location)
    ((t) t)
    ((nil) nil)
    (:unsure
     (setf (code-location-%unknown-p basic-code-location)
       (handler-case (not (fill-in-code-location basic-code-location))
         (no-debug-blocks () t))))))

;;; CODE-LOCATION-DEBUG-BLOCK -- Public.
;;;
(defun code-location-debug-block (basic-code-location)
  "Returns the debug-block containing code-location if it is available.  Some
   debug policies inhibit debug-block information, and if none is available,
   then this signals a no-debug-blocks condition."
  (let ((block (code-location-%debug-block basic-code-location)))
    (if (eq block :unparsed)
    (etypecase basic-code-location
      (compiled-code-location
       (compute-compiled-code-location-debug-block basic-code-location))
      (interpreted-code-location
       (setf (code-location-%debug-block basic-code-location)
         (make-interpreted-debug-block
          (c::node-block
           (interpreted-code-location-ir1-node basic-code-location))))))
    block)))

;;; COMPUTE-COMPILED-CODE-LOCATION-DEBUG-BLOCK -- Internal.
;;;
;;; This stores and returns basic-code-location's debug-block.  It determines
;;; the correct one using the code-location's pc.  This uses
;;; DEBUG-FUNCTION-DEBUG-BLOCKS to return the cached block information or
;;; signal a 'no-debug-blocks condition.  The blocks are sorted by their first
;;; code-location's pc, in ascending order.  Therefore, as soon as we find a
;;; block that starts with a pc greater than basic-code-location's pc, we know
;;; the previous block contains the pc.  If we get to the last block, then the
;;; code-location is either in the second to last block or the last block, and
;;; we have to be careful in determining this since the last block could be
;;; random code at the end of the function.  We have to check for the last
;;; block being random code first to see how to compare the code-location's pc.
;;;
(defun compute-compiled-code-location-debug-block (basic-code-location)
  (let* ((pc (compiled-code-location-pc basic-code-location))
     (debug-function (code-location-debug-function
              basic-code-location))
     (blocks (debug-function-debug-blocks debug-function))
     (len (length blocks)))
    (declare (simple-vector blocks))
    (setf (code-location-%debug-block basic-code-location)
      (if (= len 1)
          (svref blocks 0)
          (do ((i 1 (1+ i))
           (end (1- len)))
          ((= i end)
           (let ((last (svref blocks end)))
             (cond
              ((debug-block-elsewhere-p last)
               (if (< pc
                  (c::compiled-debug-function-elsewhere-pc
                   (compiled-debug-function-compiler-debug-fun
                debug-function)))
               (svref blocks (1- end))
               last))
              ((< pc
              (compiled-code-location-pc
               (svref (compiled-debug-block-code-locations last)
                  0)))
               (svref blocks (1- end)))
              (t last))))
        (declare (type c::index i end))
        (when (< pc
             (compiled-code-location-pc
              (svref (compiled-debug-block-code-locations
                  (svref blocks i))
                 0)))
          (return (svref blocks (1- i)))))))))

;;; CODE-LOCATION-DEBUG-SOURCE -- Public.
;;;
(defun code-location-debug-source (code-location)
  "Returns the code-location's debug-source."
  (etypecase code-location
    (compiled-code-location
     (let* ((info (compiled-debug-function-debug-info
           (code-location-debug-function code-location)))
        (sources (c::compiled-debug-info-source info))
        (len (length sources)))
     (declare (list sources))
     (if (= len 1)
         (car sources)
         (do ((prev sources src)
          (src (cdr sources) (cdr src))
          (offset (code-location-top-level-form-offset code-location)))
         ((null src) (car prev))
           (when (< offset (c::debug-source-source-root (car src)))
         (return (car prev)))))))
    (interpreted-code-location
     (first
      (let ((c::*lexical-environment* (c::make-null-environment)))
    (c::debug-source-for-info
     (c::component-source-info
      (c::block-component
       (c::node-block
        (interpreted-code-location-ir1-node code-location))))))))))


;;; CODE-LOCATION-TOP-LEVEL-FORM-OFFSET -- Public.
;;;
(defun code-location-top-level-form-offset (code-location)
  "Returns the number of top-level forms before the one containing
   code-location as seen by the compiler in some compilation unit.  A
   compilation unit is not necessarily a single file, see the section on
   debug-sources."
  (when (code-location-unknown-p code-location)
    (error 'unknown-code-location :code-location code-location))
  (let ((tlf-offset (code-location-%tlf-offset code-location)))
    (cond ((eq tlf-offset :unparsed)
       (etypecase code-location
         (compiled-code-location
          (unless (fill-in-code-location code-location)
        ;; This check should be unnecessary.  We're missing debug info
        ;; the compiler should have dumped.
        (error "Unknown code location?  It should be known."))
          (code-location-%tlf-offset code-location))
         (interpreted-code-location
          (setf (code-location-%tlf-offset code-location)
            (c::source-path-tlf-number
             (c::node-source-path
              (interpreted-code-location-ir1-node code-location)))))))
      (t tlf-offset))))

;;; CODE-LOCATION-FORM-NUMBER -- Public.
;;;
(defun code-location-form-number (code-location)
  "Returns the number of the form corresponding to code-location.  The form
   number is derived by a walking the subforms of a top-level form in
   depth-first order."
  (when (code-location-unknown-p code-location)
    (error 'unknown-code-location :code-location code-location))
  (let ((form-num (code-location-%form-number code-location)))
    (cond ((eq form-num :unparsed)
       (etypecase code-location
         (compiled-code-location
          (unless (fill-in-code-location code-location)
        ;; This check should be unnecessary.  We're missing debug info
        ;; the compiler should have dumped.
        (error "Unknown code location?  It should be known."))
          (code-location-%form-number code-location))
         (interpreted-code-location
          (setf (code-location-%form-number code-location)
            (c::source-path-form-number
             (c::node-source-path
              (interpreted-code-location-ir1-node code-location)))))))
      (t form-num))))

;;; CODE-LOCATION-KIND -- Public
;;;
(defun code-location-kind (code-location)
  "Return the kind of CODE-LOCATION, one of:
     :interpreted, :unknown-return, :known-return, :internal-error,
     :non-local-exit, :block-start, :call-site, :single-value-return,
     :non-local-entry"
  (when (code-location-unknown-p code-location)
    (error 'unknown-code-location :code-location code-location))
  (etypecase code-location
    (compiled-code-location
     (let ((kind (compiled-code-location-kind code-location)))
       (cond ((not (eq kind :unparsed)) kind)
             ((not (fill-in-code-location code-location))
              ;; This check should be unnecessary.  We're missing
              ;; debug info the compiler should have dumped.
              (error "Unknown code location?  It should be known."))
             (t
              (compiled-code-location-kind code-location)))))
    (interpreted-code-location
     :interpreted)))


;;; COMPILED-CODE-LOCATION-LIVE-SET -- Internal.
;;;
;;; This returns the code-location's live-set if it is available.  If there
;;; is no debug-block information, this returns nil.
;;;
(defun compiled-code-location-live-set (code-location)
  (if (code-location-unknown-p code-location)
      nil
      (let ((live-set (compiled-code-location-%live-set code-location)))
    (cond ((eq live-set :unparsed)
           (unless (fill-in-code-location code-location)
         ;; This check should be unnecessary.  We're missing debug info
         ;; the compiler should have dumped.
         (error "Unknown code location?  It should be known."))
           (compiled-code-location-%live-set code-location))
          (t live-set)))))

;;; CODE-LOCATION= -- Public.
;;;
(defun code-location= (obj1 obj2)
  "Returns whether obj1 and obj2 are the same place in the code."
  (etypecase obj1
    (compiled-code-location
     (etypecase obj2
       (compiled-code-location
    (and (eq (code-location-debug-function obj1)
         (code-location-debug-function obj2))
         (sub-compiled-code-location= obj1 obj2)))
       (interpreted-code-location
    nil)))
    (interpreted-code-location
     (etypecase obj2
       (compiled-code-location
    nil)
       (interpreted-code-location
    (eq (interpreted-code-location-ir1-node obj1)
        (interpreted-code-location-ir1-node obj2)))))))
;;;
(defun sub-compiled-code-location= (obj1 obj2)
  (= (compiled-code-location-pc obj1)
     (compiled-code-location-pc obj2)))

;;; FILL-IN-CODE-LOCATION -- Internal.
;;;
;;; This fills in location's :unparsed slots.  It returns t or nil depending on
;;; whether the code-location was known in its debug-function's debug-block
;;; information.  This may signal a no-debug-blocks condition due to
;;; DEBUG-FUNCTION-DEBUG-BLOCKS, and it assumes the %unknown-p slot is already
;;; set or going to be set.
;;;
(defun fill-in-code-location (code-location)
  (declare (type compiled-code-location code-location))
  (let* ((debug-function (code-location-debug-function code-location))
     (blocks (debug-function-debug-blocks debug-function)))
    (declare (simple-vector blocks))
    (dotimes (i (length blocks) nil)
      (let* ((block (svref blocks i))
         (locations (compiled-debug-block-code-locations block)))
    (declare (simple-vector locations))
    (dotimes (j (length locations))
      (let ((loc (svref locations j)))
        (when (sub-compiled-code-location= code-location loc)
          (setf (code-location-%debug-block code-location) block)
          (setf (code-location-%tlf-offset code-location)
            (code-location-%tlf-offset loc))
          (setf (code-location-%form-number code-location)
            (code-location-%form-number loc))
          (setf (compiled-code-location-%live-set code-location)
            (compiled-code-location-%live-set loc))
          (setf (compiled-code-location-kind code-location)
            (compiled-code-location-kind loc))
          (return-from fill-in-code-location t))))))))



;;;; Debug-blocks.

;;; DO-DEBUG-BLOCK-LOCATIONS -- Public.
;;;
(defmacro do-debug-block-locations ((code-var debug-block &optional return)
                    &body body)
  "Executes forms in a context with code-var bound to each code-location in
   debug-block.  This returns the value of executing result (defaults to nil)."
  (let ((code-locations (gensym))
    (i (gensym)))
    `(let ((,code-locations (debug-block-code-locations ,debug-block)))
       (declare (simple-vector ,code-locations))
       (dotimes (,i (length ,code-locations) ,return)
     (let ((,code-var (svref ,code-locations ,i)))
       ,@body)))))

;;; DEBUG-BLOCK-FUNCTION-NAME -- Internal.
;;;
(defun debug-block-function-name (debug-block)
  "Returns the name of the function represented by debug-function.  This may
   be a string or a cons; do not assume it is a symbol."
  (etypecase debug-block
    (compiled-debug-block
     (let ((code-locs (compiled-debug-block-code-locations debug-block)))
       (declare (simple-vector code-locs))
       (if (zerop (length code-locs))
       "??? Can't get name of debug-block's function."
       (debug-function-name
        (code-location-debug-function (svref code-locs 0))))))
    (interpreted-debug-block
     (c::lambda-name (c::block-home-lambda
              (interpreted-debug-block-ir1-block debug-block))))))


;;; DEBUG-BLOCK-CODE-LOCATIONS -- Internal.
;;;
(defun debug-block-code-locations (debug-block)
  (etypecase debug-block
    (compiled-debug-block
     (compiled-debug-block-code-locations debug-block))
    (interpreted-debug-block
     (interpreted-debug-block-code-locations debug-block))))

;;; INTERPRETED-DEBUG-BLOCK-CODE-LOCATIONS -- Internal.
;;;
(defun interpreted-debug-block-code-locations (debug-block)
  (let ((code-locs (interpreted-debug-block-locations debug-block)))
    (if (eq code-locs :unparsed)
    (with-parsing-buffer (buf)
      (c::do-nodes (node cont (interpreted-debug-block-ir1-block
                   debug-block))
        (vector-push-extend (make-interpreted-code-location
                 node
                 (make-interpreted-debug-function
                  (c::block-home-lambda (c::node-block node))))
                buf))
      (setf (interpreted-debug-block-locations debug-block)
        (result buf)))
    code-locs)))



;;;; Variables.

;;; DEBUG-VARIABLE-SYMBOL -- Public.
;;;
(defun debug-variable-symbol (debug-var)
  "Returns the symbol from interning DEBUG-VARIABLE-NAME in the package named
   by DEBUG-VARIABLE-PACKAGE."
  (let ((package (debug-variable-package debug-var)))
    (if package
    (intern (debug-variable-name debug-var) package)
    (make-symbol (debug-variable-name debug-var)))))

;;; DEBUG-VARIABLE-VALID-VALUE -- Public.
;;;
(defun debug-variable-valid-value (debug-var frame)
  "Returns the value stored for debug-variable in frame.  If the value is not
   :valid, then this signals an invalid-value error."
  (unless (eq (debug-variable-validity debug-var (frame-code-location frame))
          :valid)
    (error 'invalid-value :debug-variable debug-var :frame frame))
  (debug-variable-value debug-var frame))

;;; DEBUG-VARIABLE-VALUE -- Public.
;;;
(defun debug-variable-value (debug-var frame)
  "Returns the value stored for debug-variable in frame.  The value may be
   invalid.  This is SETF'able."
  (etypecase debug-var
    (compiled-debug-variable
     (check-type frame compiled-frame)
     (let ((res (access-compiled-debug-var-slot debug-var frame)))
       (if (indirect-value-cell-p res)
       (system:%primitive c::value-cell-ref res)
       res)))
    (interpreted-debug-variable
     (check-type frame interpreted-frame)
     (eval::leaf-value-lambda-var
      (interpreted-code-location-ir1-node (frame-code-location frame))
      (interpreted-debug-variable-ir1-var debug-var)
      (frame-pointer frame)
      (interpreted-frame-closure frame)))))


;;; ACCESS-COMPILED-DEBUG-VAR-SLOT -- Internal.
;;;
;;; This returns what is stored for the variable represented by debug-var
;;; relative to the frame.  This may be an indirect value cell if the
;;; variable is both closed over and set.
;;;
(defun access-compiled-debug-var-slot (debug-var frame)
  (let ((escaped (compiled-frame-escaped frame)))
    (if escaped
    (sub-access-debug-var-slot
     (frame-pointer frame)
     (compiled-debug-variable-sc-offset debug-var)
     escaped)
    (sub-access-debug-var-slot
     (frame-pointer frame)
     (or (compiled-debug-variable-save-sc-offset debug-var)
         (compiled-debug-variable-sc-offset debug-var))))))

;;; SUB-ACCESS-DEBUG-VAR-SLOT -- Internal.
;;;
(defun sub-access-debug-var-slot (fp sc-offset &optional escaped)
  (macrolet ((with-escaped-value ((var) &body forms)
           `(if escaped
            (let ((,var (vm:sigcontext-register
                 escaped
                 (c::sc-offset-offset sc-offset))))
              ,@forms)
            :invalid-value-for-unescaped-register-storage))
         (escaped-float-value (format)
           `(if escaped
            (vm:sigcontext-float-register
             escaped
             (c::sc-offset-offset sc-offset)
             ',format)
            :invalid-value-for-unescaped-register-storage))
         (with-nfp ((var) &body body)
           `(let ((,var (if escaped
                (system:int-sap
                 (vm:sigcontext-register escaped
                             vm::nfp-offset))
                (system:sap-ref-sap fp (* vm::nfp-save-offset
                              vm:word-bytes)))))
          ,@body)))
    (ecase (c::sc-offset-scn sc-offset)
      ((#.vm:any-reg-sc-number
    #.vm:descriptor-reg-sc-number
    #+rt #.vm:word-pointer-reg-sc-number)
       (system:without-gcing
    (with-escaped-value (val)
      (kernel:make-lisp-obj val))))
      (#.vm:base-char-reg-sc-number
       (with-escaped-value (val)
     (code-char val)))
      (#.vm:sap-reg-sc-number
       (with-escaped-value (val)
     (system:int-sap val)))
      (#.vm:signed-reg-sc-number
       (with-escaped-value (val)
     (if (logbitp (1- vm:word-bits) val)
         (logior val (ash -1 vm:word-bits))
         val)))
      (#.vm:unsigned-reg-sc-number
       (with-escaped-value (val)
     val))
      (#.vm:non-descriptor-reg-sc-number
       (error "Local non-descriptor register access?"))
      (#.vm:interior-reg-sc-number
       (error "Local interior register access?"))
      (#.vm:single-reg-sc-number
       (escaped-float-value single-float))
      (#.vm:double-reg-sc-number
       (escaped-float-value double-float))
      (#.vm:single-stack-sc-number
       (with-nfp (nfp)
     (system:sap-ref-single nfp (* (vm::sc-offset-offset sc-offset)
                       vm:word-bytes))))
      (#.vm:double-stack-sc-number
       (with-nfp (nfp)
     (system:sap-ref-double nfp (* (c::sc-offset-offset sc-offset)
                       vm:word-bytes))))
      (#.vm:control-stack-sc-number
       (kernel:stack-ref fp (c::sc-offset-offset sc-offset)))
      (#.vm:base-char-stack-sc-number
       (with-nfp (nfp)
     (code-char (system:sap-ref-32 nfp (* (c::sc-offset-offset sc-offset)
                          vm:word-bytes)))))
      (#.vm:unsigned-stack-sc-number
       (with-nfp (nfp)
     (system:sap-ref-32 nfp (* (c::sc-offset-offset sc-offset)
                   vm:word-bytes))))
      (#.vm:signed-stack-sc-number
       (with-nfp (nfp)
     (system:signed-sap-ref-32 nfp (* (c::sc-offset-offset sc-offset)
                      vm:word-bytes))))
      (#.vm:sap-stack-sc-number
       (with-nfp (nfp)
     (system:sap-ref-sap nfp (* (c::sc-offset-offset sc-offset)
                    vm:word-bytes)))))))


;;; %SET-DEBUG-VARIABLE-VALUE -- Internal.
;;;
;;; This stores value as the value of debug-var in frame.  In the
;;; compiled-debug-variable case, access the current value to determine if it
;;; is an indirect value cell.  This occurs when the variable is both closed
;;; over and set.  For interpreted-debug-variables just call
;;; EVAL::SET-LEAF-VALUE-LAMBDA-VAR with the right interpreter objects.
;;;
(defun %set-debug-variable-value (debug-var frame value)
  (etypecase debug-var
    (compiled-debug-variable
     (check-type frame compiled-frame)
     (let ((current-value (access-compiled-debug-var-slot debug-var frame)))
       (if (indirect-value-cell-p current-value)
       (system:%primitive c::value-cell-set current-value value)
       (set-compiled-debug-variable-slot debug-var frame value))))
    (interpreted-debug-variable
     (check-type frame interpreted-frame)
     (eval::set-leaf-value-lambda-var
      (interpreted-code-location-ir1-node (frame-code-location frame))
      (interpreted-debug-variable-ir1-var debug-var)
      (frame-pointer frame)
      (interpreted-frame-closure frame)
      value)))
  value)
;;;
(defsetf debug-variable-value %set-debug-variable-value)

;;; SET-COMPILED-DEBUG-VARIABLE-SLOT -- Internal.
;;;
;;; This stores value for the variable represented by debug-var relative to the
;;; frame.  This assumes the location directly contains the variable's value;
;;; that is, there is no indirect value cell currently there in case the
;;; variable is both closed over and set.
;;;
(defun set-compiled-debug-variable-slot (debug-var frame value)
  (let ((escaped (compiled-frame-escaped frame)))
    (if escaped
    (sub-set-debug-var-slot (frame-pointer frame)
                (compiled-debug-variable-sc-offset debug-var)
                value escaped)
    (sub-set-debug-var-slot
     (frame-pointer frame)
     (or (compiled-debug-variable-save-sc-offset debug-var)
         (compiled-debug-variable-sc-offset debug-var))
     value))))

;;; SUB-SET-DEBUG-VAR-SLOT -- Internal.
;;;
(defun sub-set-debug-var-slot (fp sc-offset value &optional escaped)
  (macrolet ((set-escaped-value (val)
           `(if escaped
            (setf (vm:sigcontext-register
               escaped
               (c::sc-offset-offset sc-offset))
              ,val)
            value))
         (set-escaped-float-value (format val)
           `(if escaped
            (setf (vm:sigcontext-float-register
               escaped
               (c::sc-offset-offset sc-offset)
               ',format)
              ,val)
            value))
         (with-nfp ((var) &body body)
           `(let ((,var (if escaped
                (system:int-sap
                 (vm:sigcontext-register escaped
                             vm::nfp-offset))
                (system:sap-ref-sap fp
                            (* vm::nfp-save-offset
                               vm:word-bytes)))))
          ,@body)))
    (ecase (c::sc-offset-scn sc-offset)
      ((#.vm:any-reg-sc-number
    #.vm:descriptor-reg-sc-number
    #+rt #.vm:word-pointer-reg-sc-number)
       (system:without-gcing
    (set-escaped-value
      (kernel:get-lisp-obj-address value))))
      (#.vm:base-char-reg-sc-number
       (set-escaped-value (char-code value)))
      (#.vm:sap-reg-sc-number
       (set-escaped-value (system:sap-int value)))
      (#.vm:signed-reg-sc-number
       (set-escaped-value (logand value (1- (ash 1 vm:word-bits)))))
      (#.vm:unsigned-reg-sc-number
       (set-escaped-value value))
      (#.vm:non-descriptor-reg-sc-number
       (error "Local non-descriptor register access?"))
      (#.vm:interior-reg-sc-number
       (error "Local interior register access?"))
      (#.vm:single-reg-sc-number
       (set-escaped-float-value single-float value))
      (#.vm:double-reg-sc-number
       (set-escaped-float-value double-float value))
      (#.vm:single-stack-sc-number
       (with-nfp (nfp)
     (setf (system:sap-ref-single nfp (* (c::sc-offset-offset sc-offset)
                         vm:word-bytes))
           (the single-float value))))
      (#.vm:double-stack-sc-number
       (with-nfp (nfp)
     (setf (system:sap-ref-double nfp (* (c::sc-offset-offset sc-offset)
                         vm:word-bytes))
           (the double-float value))))
      (#.vm:control-stack-sc-number
       (setf (kernel:stack-ref fp (c::sc-offset-offset sc-offset)) value))
      (#.vm:base-char-stack-sc-number
       (with-nfp (nfp)
     (setf (system:sap-ref-32 nfp (* (c::sc-offset-offset sc-offset)
                     vm:word-bytes))
           (char-code (the character value)))))
      (#.vm:unsigned-stack-sc-number
       (with-nfp (nfp)
     (setf (system:sap-ref-32 nfp (* (c::sc-offset-offset sc-offset)
                     vm:word-bytes))
           (the (unsigned-byte 32) value))))
      (#.vm:signed-stack-sc-number
       (with-nfp (nfp)
     (setf (system:signed-sap-ref-32 nfp (* (c::sc-offset-offset sc-offset)
                        vm:word-bytes))
           (the (signed-byte 32) value))))
      (#.vm:sap-stack-sc-number
       (with-nfp (nfp)
     (setf (system:sap-ref-sap nfp (* (c::sc-offset-offset sc-offset)
                      vm:word-bytes))
           (the system:system-area-pointer value)))))))

(defsetf debug-variable-value %set-debug-variable-value)


;;; INDIRECT-VALUE-CELL-P -- Internal.
;;;
;;; The method for setting and accessing compiled-debug-variable values use
;;; this to determine if the value stored is the actual value or an indirection
;;; cell.
;;;
(defun indirect-value-cell-p (x)
  (and (= (kernel:get-lowtag x) vm:other-pointer-type)
       (= (kernel:get-type x) vm:value-cell-header-type)))


;;; DEBUG-VARIABLE-VALIDITY -- Public.
;;;
;;; If the variable is always alive, then it is valid.  If the code-location is
;;; unknown, then the variable's validity is :unknown.  Once we've called
;;; CODE-LOCATION-UNKNOWN-P, we know the live-set information has been cached
;;; in the code-location.
;;;
(defun debug-variable-validity (debug-var basic-code-loc)
  "Returns three values reflecting the validity of debug-variable's value
   at basic-code-location:
      :valid    The value is known to be available.
      :invalid  The value is known to be unavailable.
      :unknown  The value's availability is unknown."
  (etypecase debug-var
    (compiled-debug-variable
     (compiled-debug-variable-validity debug-var basic-code-loc))
    (interpreted-debug-variable
     (check-type basic-code-loc interpreted-code-location)
     (let ((validp (rassoc (interpreted-debug-variable-ir1-var debug-var)
               (c::lexenv-variables
                (c::node-lexenv
                 (interpreted-code-location-ir1-node
                  basic-code-loc))))))
       (if validp :valid :invalid)))))

;;; COMPILED-DEBUG-VARIABLE-VALIDITY -- Internal.
;;;
;;; This is the method for DEBUG-VARIABLE-VALIDITY for compiled-debug-variables.
;;; For safety, make sure basic-code-loc is what we think.
;;;
(defun compiled-debug-variable-validity (debug-var basic-code-loc)
  (check-type basic-code-loc compiled-code-location)
  (cond ((debug-variable-alive-p debug-var)
     (let ((debug-fun (code-location-debug-function basic-code-loc)))
       (if (>= (compiled-code-location-pc basic-code-loc)
           (c::compiled-debug-function-start-pc
            (compiled-debug-function-compiler-debug-fun debug-fun)))
           :valid
           :invalid)))
    ((code-location-unknown-p basic-code-loc) :unknown)
    (t
     (let ((pos (position debug-var
                  (debug-function-debug-variables
                   (code-location-debug-function basic-code-loc)))))
       (unless pos
         (error 'unknown-debug-variable
            :debug-variable debug-var
            :debug-function
            (code-location-debug-function basic-code-loc)))
       ;; There must be live-set info since basic-code-loc is known.
       (if (zerop (sbit (compiled-code-location-live-set basic-code-loc)
                pos))
           :invalid
           :valid)))))



;;;; Sources.

;;; Written by Rob Maclachlan.
;;; Documented by Bill Chiles.
;;;
;;; This code produces and uses what we call source-paths.  A source-path is a
;;; list whose first element is a form number as returned by
;;; CODE-LOCATION-FORM-NUMBER and whose last element is a top-level-form number
;;; as returned by CODE-LOCATION-TOP-LEVEL-FORM-NUMBER.  The elements from the
;;; last to the first, exclusively, are the numbered subforms into which to
;;; descend.  For example:
;;;    (defun foo (x)
;;;      (let ((a (aref x 3)))
;;;        (cons a 3)))
;;; The call to AREF in this example is form number 5.  Assuming this DEFUN is
;;; the 11'th top-level-form, the source-path for the AREF call is as follows:
;;;    (5 1 0 1 3 11)
;;; Given the DEFUN, 3 gets you the LET, 1 gets you the bindings, 0 gets the
;;; first binding, and 1 gets the AREF form.
;;;


;;; Temporary buffer used to build form-number => source-path translation in
;;; FORM-NUMBER-TRANSLATIONS.
;;;
(defvar *form-number-temp* (make-array 10 :fill-pointer 0 :adjustable t))

;;; Table used to detect CAR circularities in FORM-NUMBER-TRANSLATIONS.
;;;
(defvar *form-number-circularity-table* (make-hash-table :test #'eq))

;;; FORM-NUMBER-TRANSLATIONS  --  Public.
;;;
;;; The vector elements are in the same format as the compiler's
;;; NODE-SOUCE-PATH; that is, the first element is the form number and the last
;;; is the top-level-form number.
;;;
(defun form-number-translations (form tlf-number)
  "This returns a table mapping form numbers to source-paths.  A source-path
   indicates a descent into the top-level-form form, going directly to the
   subform corressponding to the form number."
  (clrhash *form-number-circularity-table*)
  (setf (fill-pointer *form-number-temp*) 0)
  (sub-translate-form-numbers form (list tlf-number))
  (coerce *form-number-temp* 'simple-vector))
;;;
(defun sub-translate-form-numbers (form path)
  (unless (gethash form *form-number-circularity-table*)
    (setf (gethash form *form-number-circularity-table*) t)
    (vector-push-extend (cons (fill-pointer *form-number-temp*) path)
            *form-number-temp*)
    (let ((pos 0)
      (subform form)
      (trail form))
      (declare (fixnum pos))
      (macrolet ((frob ()
           '(progn
              (when (atom subform) (return))
              (let ((fm (car subform)))
            (when (consp fm)
              (sub-translate-form-numbers fm (cons pos path)))
            (incf pos))
              (setq subform (cdr subform))
              (when (eq subform trail) (return)))))
    (loop
      (frob)
      (frob)
      (setq trail (cdr trail)))))))


;;; SOURCE-PATH-CONTEXT  --  Public.
;;;
(defun source-path-context (form path context)
  "Form is a top-level form, and path is a source-path into it.  This returns
   the form indicated by the source-path.  Context is the number of enclosing
   forms to return instead of directly returning the source-path form.  When
   context is non-zero, the form returned contains a marker, #:****HERE****,
   immediately before the form indicated by path."
  (declare (type unsigned-byte context))
  ;;
  ;; Get to the form indicated by path or the enclosing form indicated by
  ;; context and path.
  (let ((path (reverse (butlast (cdr path)))))
    (dotimes (i (- (length path) context))
      (setq form (elt form (first path)))
      (setq path (rest path)))
    ;;
    ;; Recursively rebuild the source form resulting from the above descent,
    ;; copying the beginning of each subform up to the next subform we descend
    ;; into according to path.  At the bottom of the recursion, we return the
    ;; form indicated by path preceded by our marker, and this gets spliced
    ;; into the resulting list structure on the way back up.
    (labels ((frob (form path level)
           (if (or (zerop level) (null path))
           (if (zerop context)
               form
               `(#:***here*** ,form))
           (let* ((n (first path))
              (res (frob (elt form n) (rest path) (1- level))))
             (nconc (subseq form 0 n)
                (cons res (nthcdr (1+ n) form)))))))
      (frob form path context))))


;;;; PREPROCESS-FOR-EVAL and EVAL-IN-FRAME.

;;; PREPROCESS-FOR-EVAL  --  Public.
;;;
;;; Create a SYMBOL-MACROLET for each variable valid at the location which
;;; accesses that variable from the frame argument.
;;;
(defun preprocess-for-eval (form loc)
  "Return a function of one argument that evaluates form in the lexical
   context of the basic-code-location loc.  PREPROCESS-FOR-EVAL signals a
   no-debug-variables condition when the loc's debug-function has no
   debug-variable information available.  The returned function takes the frame
   to get values from as its argument, and it returns the values of form.
   The returned function signals the following conditions: invalid-value,
   ambiguous-variable-name, and frame-function-mismatch"
  (declare (type code-location loc))
  (let ((n-frame (gensym))
    (fun (code-location-debug-function loc)))
    (unless (debug-variable-info-available fun)
      (debug-signal 'no-debug-variables :debug-function fun))
    (ext:collect ((binds)
          (specs))
      (do-debug-function-variables (var fun)
    (let ((validity (debug-variable-validity var loc)))
      (unless (eq validity :invalid)
        (let* ((sym (debug-variable-symbol var))
           (found (assoc sym (binds))))
          (if found
          (setf (second found) :ambiguous)
          (binds (list sym validity var)))))))
      (dolist (bind (binds))
    (let ((name (first bind))
          (var (third bind)))
      (ecase (second bind)
        (:valid
         (specs `(,name (debug-variable-value ',var ,n-frame))))
        (:unknown
         (specs `(,name (debug-signal 'invalid-value :debug-variable ',var
                      :frame ,n-frame))))
        (:ambiguous
         (specs `(,name (debug-signal 'ambiguous-variable-name :name ',name
                      :frame ,n-frame)))))))
      (let ((res (coerce `(lambda (,n-frame)
                (declare (ignorable ,n-frame))
                (symbol-macrolet ,(specs) ,form))
             'function)))
    #'(lambda (frame)
        ;; This prevents these functions from use in any location other
        ;; than a function return location, so maybe this should only
        ;; check whether frame's debug-function is the same as loc's.
        (unless (code-location= (frame-code-location frame) loc)
          (debug-signal 'frame-function-mismatch
                :code-location loc :form form :frame frame))
        (funcall res frame))))))


;;; EVAL-IN-FRAME  --  Public.
;;;
(defun eval-in-frame (frame form)
  (declare (type frame frame))
  "Evaluate Form in the lexical context of Frame's current code location,
   returning the results of the evaluation."
  (funcall (preprocess-for-eval form (frame-code-location frame)) frame))



;;;; Breakpoints.

;;;
;;; User visible interface.
;;;

(defun make-breakpoint (hook-function what
            &key (kind :code-location) info function-end-cookie)
  "This creates and returns a breakpoint.  When program execution encounters
   the breakpoint, the system calls hook-function.  Hook-function takes the
   current frame for the function in which the program is running and the
   breakpoint object.
      What and kind determine where in a function the system invokes
   hook-function.  What is either a code-location or a debug-function.  Kind is
   one of :code-location, :function-start, or :function-end.  Since the starts
   and ends of functions may not have code-locations representing them,
   designate these places by supplying what as a debug-function and kind
   indicating the :function-start or :function-end.  When what is a
   debug-function and kind is :function-end, then hook-function must take two
   additional arguments, a list of values returned by the function and a
   function-end-cookie.
      Info is information supplied by and used by the user.
      Function-end-cookie is a function.  To implement :function-end breakpoints,
   the system uses starter breakpoints to establish the :function-end breakpoint
   for each invocation of the function.  Upon each entry, the system creates a
   unique cookie to identify the invocation, and when the user supplies a
   function for this argument, the system invokes it on the frame and the
   cookie.  The system later invokes the :function-end breakpoint hook on the
   same cookie.  The user may save the cookie for comparison in the hook
   function.
      This signals an error if what is an unknown code-location."
  (etypecase what
    (code-location
     (when (code-location-unknown-p what)
       (error "Cannot make a breakpoint at an unknown code location -- ~S."
          what))
     (assert (eq kind :code-location))
     (let ((bpt (%make-breakpoint hook-function what kind info)))
       (etypecase what
     (interpreted-code-location
      (error "Breakpoints in interpreted code are currently unsupported."))
     (compiled-code-location
      ;; This slot is filled in due to calling CODE-LOCATION-UNKNOWN-P.
      (when (eq (compiled-code-location-kind what) :unknown-return)
        (let ((other-bpt (%make-breakpoint hook-function what
                           :unknown-return-partner
                           info)))
          (setf (breakpoint-unknown-return-partner bpt) other-bpt)
          (setf (breakpoint-unknown-return-partner other-bpt) bpt)))))
       bpt))
    (compiled-debug-function
     (ecase kind
       (:function-start
    (%make-breakpoint hook-function what kind info))
       (:function-end
    (unless (eq (c::compiled-debug-function-returns
             (compiled-debug-function-compiler-debug-fun what))
            :standard)
      (error ":FUNCTION-END breakpoints are currently unsupported ~
          for the known return convention."))

    (let* ((bpt (%make-breakpoint hook-function what kind info))
           (starter (compiled-debug-function-end-starter what)))
      (unless starter
        (setf starter (%make-breakpoint #'list what :function-start nil))
        (setf (breakpoint-hook-function starter)
          (function-end-starter-hook starter what))
        (setf (compiled-debug-function-end-starter what) starter))
      (setf (breakpoint-start-helper bpt) starter)
      (push bpt (breakpoint-%info starter))
      (setf (breakpoint-cookie-fun bpt) function-end-cookie)
      bpt))))
    (interpreted-debug-function
     (error ":function-end breakpoints are currently unsupported ~
         for interpreted-debug-functions."))))

;;; These are unique objects created upon entry into a function by a
;;; :function-end breakpoint's starter hook.  These are only created when users
;;; supply :function-end-cookie to MAKE-BREAKPOINT.  Also, the :function-end
;;; breakpoint's hook is called on the same cookie when it is created.
;;;
(defstruct (function-end-cookie
        (:print-function (lambda (obj str n)
                   (declare (ignore obj n))
                   (write-string "#<Function-End-Cookie>" str)))
        (:constructor make-function-end-cookie (bogus-lra debug-fun)))
  ;; This is a pointer to the bogus-lra created for :function-end bpts.
  bogus-lra
  ;; This is the debug-function associated with the cookie.
  debug-fun)

;;; This maps bogus-lra-components to cookies, so
;;; HANDLE-FUNCTION-END-BREAKPOINT can find the appropriate cookie for the
;;; breakpoint hook.
;;;
(defvar *function-end-cookies* (make-hash-table :test #'eq))

;;; FUNCTION-END-STARTER-HOOK -- Internal.
;;;
;;; This returns a hook function for the start helper breakpoint associated
;;; with a :function-end breakpoint.  The returned function makes a fake LRA
;;; that all returns go through, and this piece of fake code actually breaks.
;;; Upon return from the break, the code provides the returnee with any values.
;;; Since the returned function effectively activates fun-end-bpt on each entry
;;; to debug-fun's function, we must establish breakpoint-data about
;;; fun-end-bpt.
;;;
(defun function-end-starter-hook (starter-bpt debug-fun)
  (declare (type breakpoint starter-bpt)
       (type compiled-debug-function debug-fun))
  #'(lambda (frame breakpoint)
      (declare (ignore breakpoint)
           (type frame frame))
      (let ((lra-sc-offset
         (c::compiled-debug-function-return-pc
          (compiled-debug-function-compiler-debug-fun debug-fun))))
    (multiple-value-bind (lra component offset)
                 (make-bogus-lra
                  (get-context-value frame vm::lra-save-offset
                         lra-sc-offset))
      (setf (get-context-value frame vm::lra-save-offset lra-sc-offset)
        lra)
      (let ((end-bpts (breakpoint-%info starter-bpt)))
        (let ((data (breakpoint-data component offset)))
          (setf (breakpoint-data-breakpoints data) end-bpts)
          (dolist (bpt end-bpts)
        (setf (breakpoint-internal-data bpt) data)))
        (let ((cookie (make-function-end-cookie lra debug-fun)))
          (setf (gethash component *function-end-cookies*) cookie)
          (dolist (bpt end-bpts)
        (let ((fun (breakpoint-cookie-fun bpt)))
          (when fun (funcall fun frame cookie))))))))))

;;; FUNCTION-END-COOKIE-VALID-P -- Public.
;;;
(defun function-end-cookie-valid-p (frame cookie)
  "This takes a function-end-cookie and a frame, and it returns whether the
   cookie is still valid.  A cookie becomes invalid when the frame that
   established the cookie has exited.  Sometimes cookie holders are unaware
   of cookie invalidation because their :function-end breakpoint hooks didn't
   run due to THROW'ing.  This takes a frame as an efficiency hack since the
   user probably has a frame object in hand when using this routine, and it
   saves repeated parsing of the stack and consing when asking whether a
   series of cookies is valid."
  (let ((lra (function-end-cookie-bogus-lra cookie))
    (lra-sc-offset (c::compiled-debug-function-return-pc
            (compiled-debug-function-compiler-debug-fun
             (function-end-cookie-debug-fun cookie)))))
    (do ((frame frame (frame-down frame)))
    ((not frame) nil)
      (when (and (compiled-frame-p frame)
         (eq lra
             (get-context-value frame
                    vm::lra-save-offset
                    lra-sc-offset)))
    (return t)))))

;;;
;;; ACTIVATE-BREAKPOINT.
;;;

;;; ACTIVATE-BREAKPOINT -- Public.
;;;
(defun activate-breakpoint (breakpoint)
  "This causes the system to invoke the breakpoint's hook-function until the
   next call to DEACTIVATE-BREAKPOINT or DELETE-BREAKPOINT.  The system invokes
   breakpoint hook functions in the opposite order that you activate them."
  (when (eq (breakpoint-status breakpoint) :deleted)
    (error "Cannot activate a deleted breakpoint -- ~S." breakpoint))
  (unless (eq (breakpoint-status breakpoint) :active)
    (ecase (breakpoint-kind breakpoint)
      (:code-location
       (let ((loc (breakpoint-what breakpoint)))
     (etypecase loc
       (interpreted-code-location
        (error "Breakpoints in interpreted code are currently unsupported."))
       (compiled-code-location
        (activate-compiled-code-location-breakpoint breakpoint)
        (let ((other (breakpoint-unknown-return-partner breakpoint)))
          (when other
        (activate-compiled-code-location-breakpoint other)))))))
      (:function-start
       (etypecase (breakpoint-what breakpoint)
     (compiled-debug-function
      (activate-compiled-function-start-breakpoint breakpoint))
     (interpreted-debug-function
      (error "I don't know how you made this, but they're unsupported -- ~S"
         (breakpoint-what breakpoint)))))
      (:function-end
       (etypecase (breakpoint-what breakpoint)
     (compiled-debug-function
      (let ((starter (breakpoint-start-helper breakpoint)))
        (unless (eq (breakpoint-status starter) :active)
          ;; May already be active by some other :function-end breakpoint.
          (activate-compiled-function-start-breakpoint starter)))
      (setf (breakpoint-status breakpoint) :active))
     (interpreted-debug-function
      (error "I don't know how you made this, but they're unsupported -- ~S"
         (breakpoint-what breakpoint)))))))
  breakpoint)

;;; ACTIVATE-COMPILED-CODE-LOCATION-BREAKPOINT -- Internal.
;;;
(defun activate-compiled-code-location-breakpoint (breakpoint)
  (declare (type breakpoint breakpoint))
  (let ((loc (breakpoint-what breakpoint)))
    (declare (type compiled-code-location loc))
    (sub-activate-breakpoint
     breakpoint
     (breakpoint-data (compiled-debug-function-component
               (code-location-debug-function loc))
              (+ (compiled-code-location-pc loc)
             (if (or (eq (breakpoint-kind breakpoint)
                     :unknown-return-partner)
                 (eq (compiled-code-location-kind loc)
                     :single-value-return))
                 (error "Return location breakpoints NYI.")
                 0))))))

;;; ACTIVATE-COMPILED-FUNCTION-START-BREAKPOINT -- Internal.
;;;
(defun activate-compiled-function-start-breakpoint (breakpoint)
  (declare (type breakpoint breakpoint))
  (let ((debug-fun (breakpoint-what breakpoint)))
    (sub-activate-breakpoint
     breakpoint
     (breakpoint-data (compiled-debug-function-component debug-fun)
              (c::compiled-debug-function-start-pc
               (compiled-debug-function-compiler-debug-fun
            debug-fun))))))

;;; SUB-ACTIVATE-BREAKPOINT -- Internal.
;;;
(defun sub-activate-breakpoint (breakpoint data)
  (declare (type breakpoint breakpoint)
       (type breakpoint-data data))
  (setf (breakpoint-status breakpoint) :active)
  (system:without-interrupts
   (unless (breakpoint-data-breakpoints data)
     (setf (breakpoint-data-instruction data)
       (system:without-gcing
        (breakpoint-install (kernel:get-lisp-obj-address
                 (breakpoint-data-component data))
                (breakpoint-data-offset data)))))
   (setf (breakpoint-data-breakpoints data)
     (append (breakpoint-data-breakpoints data) (list breakpoint)))
   (setf (breakpoint-internal-data breakpoint) data)))

;;;
;;; DEACTIVATE-BREAKPOINT.
;;;

;;; DEACTIVATE-BREAKPOINT -- Public.
;;;
(defun deactivate-breakpoint (breakpoint)
  "This stops the system from invoking the breakpoint's hook-function."
  (when (eq (breakpoint-status breakpoint) :active)
    (system:without-interrupts
     (let ((loc (breakpoint-what breakpoint)))
       (etypecase loc
     ((or interpreted-code-location interpreted-debug-function)
      (error
       "Breakpoints in interpreted code are currently unsupported."))
     ((or compiled-code-location compiled-debug-function)
      (deactivate-compiled-breakpoint breakpoint)
      (let ((other (breakpoint-unknown-return-partner breakpoint)))
        (when other
          (deactivate-compiled-breakpoint other))))))))
  breakpoint)

(defun deactivate-compiled-breakpoint (breakpoint)
  (if (eq (breakpoint-kind breakpoint) :function-end)
      (let ((starter (breakpoint-start-helper breakpoint)))
    (unless (find-if #'(lambda (bpt)
                 (and (not (eq bpt breakpoint))
                  (eq (breakpoint-status bpt) :active)))
             (breakpoint-%info starter))
      (deactivate-compiled-breakpoint starter)))
      (let* ((data (breakpoint-internal-data breakpoint))
         (bpts (delete breakpoint (breakpoint-data-breakpoints data))))
    (setf (breakpoint-internal-data breakpoint) nil)
    (setf (breakpoint-data-breakpoints data) bpts)
    (unless bpts
      (system:without-gcing
       (breakpoint-remove (kernel:get-lisp-obj-address
                   (breakpoint-data-component data))
                  (breakpoint-data-offset data)
                  (breakpoint-data-instruction data)))
      (delete-breakpoint-data data))))
  (setf (breakpoint-status breakpoint) :inactive)
  breakpoint)

;;;
;;; BREAKPOINT-INFO.
;;;

;;; BREAKPOINT-INFO -- Public.
;;;
(defun breakpoint-info (breakpoint)
  "This returns the user maintained info associated with breakpoint.  This
   is SETF'able."
  (breakpoint-%info breakpoint))
;;;
(defun %set-breakpoint-info (breakpoint value)
  (setf (breakpoint-%info breakpoint) value)
  (let ((other (breakpoint-unknown-return-partner breakpoint)))
    (when other
      (setf (breakpoint-%info other) value))))
;;;
(defsetf breakpoint-info %set-breakpoint-info)

;;;
;;; BREAKPOINT-ACTIVE-P and DELETE-BREAKPOINT.
;;;

;;; BREAKPOINT-ACTIVE-P -- Public.
;;;
(defun breakpoint-active-p (breakpoint)
  "This returns whether breakpoint is currently active."
  (ecase (breakpoint-status breakpoint)
    (:active t)
    ((:inactive :deleted) nil)))

;;; DELETE-BREAKPOINT -- Public.
;;;
(defun delete-breakpoint (breakpoint)
  "This frees system storage and removes computational overhead associated with
   breakpoint.  After calling this, breakpoint is completely impotent and can
   never become active again."
  (let ((status (breakpoint-status breakpoint)))
    (unless (eq status :deleted)
      (when (eq status :active)
    (deactivate-breakpoint breakpoint))
      (setf (breakpoint-status breakpoint) :deleted)
      (let ((other (breakpoint-unknown-return-partner breakpoint)))
    (when other
      (setf (breakpoint-status other) :deleted)))
      (when (eq (breakpoint-kind breakpoint) :function-end)
    (let* ((starter (breakpoint-start-helper breakpoint))
           (breakpoints (delete breakpoint
                    (the list (breakpoint-info starter)))))
      (setf (breakpoint-info starter) breakpoints)
      (unless breakpoints
        (delete-breakpoint starter)
        (setf (compiled-debug-function-end-starter
           (breakpoint-what breakpoint))
          nil))))))
  breakpoint)

;;;
;;; C call out stubs.
;;;

;;; BREAKPOINT-INSTALL -- Internal.
;;;
;;; This actually installs the break instruction in the component.  It returns
;;; the overwritten bits.  You must call this in a context in which GC is
;;; disabled, so Lisp doesn't move objects around that C is pointing to.
;;;
(alien:def-alien-routine "breakpoint_install" c-call:unsigned-long
  (code-obj c-call:unsigned-long)
  (pc-offset c-call:int))

;;; BREAKPOINT-REMOVE -- Internal.
;;;
;;; This removes the break instruction and replaces the original instruction.
;;; You must call this in a context in which GC is disabled, so Lisp doesn't
;;; move objects around that C is pointing to.
;;;
(alien:def-alien-routine "breakpoint_remove" c-call:void
  (code-obj c-call:unsigned-long)
  (pc-offset c-call:int)
  (old-inst c-call:unsigned-long))

;;; BREAKPOINT-AFTER-OFFSET -- Internal.
;;;
;;; This returns the offset of the next instruction following the break that
;;; generated the signal context we supply as an argument to this routine.
;;;
(alien:def-alien-routine "breakpoint_after_offset" c-call:int
  (scp system:system-area-pointer))

;;;
;;; Breakpoint handlers (layer between C and exported interface).
;;;

;;; This maps components to a mapping of offsets to breakpoint-datas.
;;;
(defvar *component-breakpoint-offsets* (make-hash-table :test #'eq))

;;; BREAKPOINT-DATA -- Internal.
;;;
;;; This returns the breakpoint-data associated with component cross offset.
;;; If none exists, this makes one, installs it, and returns it.
;;;
(defun breakpoint-data (component offset &optional (create t))
  (flet ((install-breakpoint-data ()
       (when create
         (let ((data (make-breakpoint-data component offset)))
           (push (cons offset data)
             (gethash component *component-breakpoint-offsets*))
           data))))
    (let ((offsets (gethash component *component-breakpoint-offsets*)))
      (if offsets
      (let ((data (assoc offset offsets)))
        (if data
        (cdr data)
        (install-breakpoint-data)))
      (install-breakpoint-data)))))

;;; DELETE-BREAKPOINT-DATA -- Internal.
;;;
;;; We use this when there are no longer any active breakpoints corresponding
;;; to data.
;;;
(defun delete-breakpoint-data (data)
  (let* ((component (breakpoint-data-component data))
     (offsets (delete (breakpoint-data-offset data)
              (gethash component *component-breakpoint-offsets*)
              :key #'car)))
    (if offsets
    (setf (gethash component *component-breakpoint-offsets*) offsets)
    (remhash component *component-breakpoint-offsets*)))
  (ext:undefined-value))

;;; HANDLE-BREAKPOINT -- Internal Interface.
;;;
;;; The C handler for interrupts calls this when it has a debugging-tool break
;;; instruction.  This does NOT handle all breaks; for example, it does not
;;; handle breaks for internal errors.
;;;
(defun handle-breakpoint (offset component signal-context)
  (let ((data (breakpoint-data component offset)))
    (unless data
      (error "Unknown breakpoint in ~S at offset ~S."
          (debug-function-name (debug-function-from-pc component offset))
          offset))
    (let ((breakpoints (breakpoint-data-breakpoints data)))
      (if (and breakpoints
           (eq (breakpoint-kind (car breakpoints)) :function-end))
      (handle-function-end-breakpoint breakpoints data signal-context)
      (handle-breakpoint-aux breakpoints data
                 offset component signal-context)))))

;;; This holds breakpoint-datas while invoking the breakpoint hooks associated
;;; with that particular component and location.  While they are executing, if
;;; we hit the location again, we ignore the breakpoint to avoid infinite
;;; recursion.  Function-end breakpoints must work differently since the
;;; breakpoint-data is unique for each invocation.
;;;
(defvar *executing-breakpoint-hooks* nil)

;;; HANDLE-BREAKPOINT-AUX -- Internal.
;;;
;;; This handles code-location and debug-function :function-start breakpoints.
;;;
(defun handle-breakpoint-aux (breakpoints data offset component signal-context)
  (let ((after (breakpoint-data-after-breakpoint data)))
    (when after
      (handle-after-breakpoint after breakpoints data offset component)))

  (when breakpoints
    (unless (member data *executing-breakpoint-hooks*)
      (let ((*executing-breakpoint-hooks* (cons data
                        *executing-breakpoint-hooks*)))
    (invoke-breakpoint-hooks breakpoints component offset)))
    ;; At this point breakpoints may not hold the same list as
    ;; BREAKPOINT-DATA-BREAKPOINTS since invoking hooks may have allowed a
    ;; breakpoint deactivation.  In fact, if all breakpoints were deactivated
    ;; then data is invalid since it was deleted and so the correct one must be
    ;; looked up if it is to be used.  If there are no more breakpoints active
    ;; at this location, then the normal instruction has been put back, and we
    ;; do not need an after breakpoint to re-install a break instruction.
    (setf data (breakpoint-data component offset nil))
    (when (and data
           (breakpoint-data-breakpoints data))
      ;; Restore instruction.  Do this before SET-AFTER-BREAKPOINTS which
      ;; uses CALL-BREAKPOINT-AFTER-OFFSET.
      (system:without-gcing
       (breakpoint-remove (kernel:get-lisp-obj-address component) offset
              (breakpoint-data-instruction data)))
      (set-after-breakpoints component data signal-context)
      ;; Set the sigmask, to keep the system running until we can
      ;; remove the after breakpoints and re-install the user breakpoints.
      (setf (breakpoint-data-sigmask data)
        (unix:unix-sigblock (unix:sigmask :sigint :sigquit :sigtstp))))))

(defun handle-after-breakpoint (after breakpoints data offset component)
  (let ((previous-data (after-breakpoint-previous-data after)))
    (unless (breakpoint-data-breakpoints previous-data)
      (error "After-breakpoint found with no user breakpoints. -- ~s" after))
    ;; If there are no user breakpoints at this after location, remove the
    ;; break instruction.
    (unless breakpoints
      (system:without-gcing
       (breakpoint-remove (kernel:get-lisp-obj-address component) offset
              (breakpoint-data-instruction data)))
      (setf (breakpoint-data-after-breakpoint data) nil)
      (delete-breakpoint-data data))
    ;; Ditto for the partner of the after-breakpoint (if there were two).
    (let ((partner (after-breakpoint-partner after)))
      (when partner
    (let ((partner-data (after-breakpoint-internal-data partner)))
      (unless (breakpoint-data-breakpoints partner-data)
        (system:without-gcing
         (breakpoint-remove (kernel:get-lisp-obj-address
                 (breakpoint-data-component partner-data))
                (breakpoint-data-offset partner-data)
                (breakpoint-data-instruction partner-data)))
        (setf (breakpoint-data-after-breakpoint partner-data) nil)
        (delete-breakpoint-data partner-data)))))
    ;; Put back previous's break instruction.
    ;; We don't need to store the replaced instruction in the data since we
    ;; have it from installing the break instruction before.
    (system:without-gcing
     (breakpoint-install (kernel:get-lisp-obj-address
              (breakpoint-data-component previous-data))
             (breakpoint-data-offset previous-data)))
    ;; Restore sigmask that we saved before executing previous's inst.
    (unix:unix-sigsetmask (breakpoint-data-sigmask previous-data))))

(defun invoke-breakpoint-hooks (breakpoints component offset)
  (let* ((debug-fun (debug-function-from-pc component offset))
     (frame (do ((f (top-frame) (frame-down f)))
            ((eq debug-fun (frame-debug-function f)) f))))
    (dolist (bpt breakpoints)
      (funcall (breakpoint-hook-function bpt)
           frame
           ;; If this is an :unknown-return-partner, then pass the
           ;; hook function the original breakpoint, so that users
           ;; arn't forced to confront the fact that some breakpoints
           ;; really are two.
           (if (eq (breakpoint-kind bpt) :unknown-return-partner)
           (breakpoint-unknown-return-partner bpt)
           bpt)))))

(defun set-after-breakpoints (component data signal-context)
  (multiple-value-bind (after-1 after-2)
               (call-breakpoint-after-offset signal-context)
    (let* ((after-data-1 (breakpoint-data component after-1))
       (after-data-2 (if (not (zerop after-2))
                 (breakpoint-data component after-2)))
       (after-bpt-1 (make-after-breakpoint data after-data-1)))
      (setf (breakpoint-data-after-breakpoint after-data-1) after-bpt-1)
      (when after-data-2
    ;; Set after-bpt-1's partner to an after-breakpoint.
    (setf (after-breakpoint-partner after-bpt-1)
          ;; While making it, store it in the appropriate data obj.
          (setf (breakpoint-data-after-breakpoint after-data-2)
            (make-after-breakpoint data after-data-2 after-bpt-1))))
      (system:without-gcing
       (unless (breakpoint-data-breakpoints after-data-1)
     (setf (breakpoint-data-instruction after-data-1)
           (breakpoint-install (kernel:get-lisp-obj-address component)
                   after-1)))
       (when (and after-data-2 (not (breakpoint-data-breakpoints after-data-2)))
     (setf (breakpoint-data-instruction after-data-2)
           (breakpoint-install (kernel:get-lisp-obj-address component)
                   after-2)))))))

;;; HANDLE-FUNCTION-END-BREAKPOINT -- Internal.
;;;
;;; HANDLE-BREAKPOINT calls this for :function-end breakpoints.
;;;
(defun handle-function-end-breakpoint (breakpoints data signal-context)
  (delete-breakpoint-data data)
  (let* ((scp (alien:sap-alien signal-context (* unix:sigcontext)))
     (frame (do ((cfp (vm:sigcontext-register scp vm::cfp-offset))
             (f (top-frame) (frame-down f)))
            ((= cfp (system:sap-int (frame-pointer f))) f)
          (declare (type (unsigned-byte #.vm:word-bits) cfp))))
     (component (breakpoint-data-component data))
     (cookie (gethash component *function-end-cookies*)))
    (remhash component *function-end-cookies*)
    (dolist (bpt breakpoints)
      (funcall (breakpoint-hook-function bpt)
           frame bpt
           (get-function-end-breakpoint-values scp)
           cookie))))

(defun get-function-end-breakpoint-values (scp)
  (let ((ocfp (system:int-sap (vm:sigcontext-register scp vm::ocfp-offset)))
    (nargs (kernel:make-lisp-obj
        (vm:sigcontext-register scp vm::nargs-offset)))
    (reg-arg-offsets vm::register-arg-offsets)
    (results nil))
    (system:without-gcing
     (dotimes (arg-num nargs)
       (push (if reg-arg-offsets
         (kernel:make-lisp-obj
          (vm:sigcontext-register scp (pop reg-arg-offsets)))
         (kernel:stack-ref ocfp arg-num))
         results)))
    (nreverse results)))


;;; CALL-BREAKPOINT-AFTER-OFFSET -- Internal.
;;;
;;; This calls the C routine and massages its return values.  Originally the
;;; breakpoint code was designed for the C code to return multiple offsets when
;;; the break generating the argument signal-context had replaced a branch
;;; instruction.  The Lisp code would then set after-breakpoints at each
;;; location, cleaning up both when one was hit after continuing execution.
;;; Later the C code decided it could determine which way the branch would go,
;;; so BREAKPOINT-AFTER-OFFSET could just return one offset.  In case this
;;; won't be possible on all platforms, the Lisp code will stay with its
;;; support for multiple after-breakpoints.  Then we only need to change this
;;; routine to return all values of BREAKPOINT-AFTER-OFFSET.
;;;
(defun call-breakpoint-after-offset (signal-context)
  (values (breakpoint-after-offset signal-context) 0))

;;;
;;; MAKE-BOGUS-LRA (used for :function-end breakpoints)
;;;

(defconstant bogus-lra-constants 2)
(defconstant known-return-p-slot (+ vm:code-constants-offset 1))

;;; MAKE-BOGUS-LRA -- Interface.
;;;
(defun make-bogus-lra (real-lra &optional known-return-p)
  "Make a bogus LRA object that signals a breakpoint trap when returned to.  If
   the breakpoint trap handler returns, REAL-LRA is returned to.  Three values
   are returned: the bogus LRA object, the code component it is part of, and
   the PC offset for the trap instruction."
  (system:without-gcing
   (let* ((src-start (system:foreign-symbol-address
              "function_end_breakpoint_guts"))
      (src-end (system:foreign-symbol-address
            "function_end_breakpoint_end"))
      (trap-loc (system:foreign-symbol-address
             "function_end_breakpoint_trap"))
      (length (system:sap- src-end src-start))
      (code-object (system:%primitive c:allocate-code-object
                      (1+ bogus-lra-constants)
                      length))
      (dst-start (kernel:code-instructions code-object)))
     (declare (type system:system-area-pointer
            src-start src-end dst-start trap-loc)
          (type kernel:index length))
     (setf (kernel:code-header-ref code-object vm:code-debug-info-slot)
       :bogus-lra)
     (setf (kernel:code-header-ref code-object vm:code-trace-table-offset-slot)
       length)
     (setf (kernel:code-header-ref code-object real-lra-slot) real-lra)
     (setf (kernel:code-header-ref code-object known-return-p-slot)
       known-return-p)
     (kernel:system-area-copy src-start 0 dst-start 0 (* length vm:byte-bits))
     (let ((new-lra (kernel:make-lisp-obj (+ (system:sap-int dst-start)
                         vm:other-pointer-type))))
       (kernel:set-header-data
    new-lra
    (logandc2 (+ vm:code-constants-offset bogus-lra-constants 1)
          1))
       (values new-lra code-object (system:sap- trap-loc src-start))))))



;;;; Editor support.

;;; This holds breakpoints in the slave set on behalf of the editor.
;;;
;(defvar *editor-breakpoints* (make-hash-table :test #'equal))

;;;
;;; Setting breakpoints.
;;;

;;; SET-BREAKPOINT-FOR-EDITOR -- Internal Interface.
;;;
(defun set-breakpoint-for-editor (package name-str path)
  "The editor calls this remotely in the slave to set breakpoints.  Package is
   the string name of a package or nil, and name-str is a string representing a
   function name (for example, \"foo\" or \"(setf foo)\").  After finding
   package, this READs name-str with *package* bound appropriately.  Path is
   either a modified source-path or a symbol (:function-start or
   :function-end).  If it is a modified source-path, it has no top-level-form
   offset or form-number component, and it is in descent order from the root of
   the top-level form."
  (let* ((name (let ((*package* (if package
                    (lisp::package-or-lose package)
                    *package*)))
         (read-from-string name-str)))
     (debug-fun (function-debug-function (fdefinition name))))
    (etypecase path
      (symbol
       (let* ((bpt (di:make-breakpoint
            #'(lambda (frame bpt)
            (declare (ignore frame bpt))
            (break "Editor installed breakpoint."))
            debug-fun :kind path))
          (remote-bpt (wire:make-remote-object bpt)))
     (activate-breakpoint bpt)
     ;;(push remote-bpt (gethash name *editor-breakpoints*))
     remote-bpt))
      (cons
       (etypecase debug-fun
     (compiled-debug-function
      (compiled-debug-function-set-breakpoint-for-editor
       debug-fun #|name|# path))
     (interpreted-debug-function
      (error
       "We don't currently support breakpoints in interpreted code.")))))))

(defun compiled-debug-function-set-breakpoint-for-editor (debug-fun #|name|# path)
  (let* ((source-paths (generate-component-source-paths
            (compiled-debug-function-component debug-fun)))
     (matches nil)
     (matching-length 0))
    (declare (simple-vector source-paths)
         (list matches)
         (fixnum matching-length))
    ;; Build a list of paths that match path up to matching-length
    ;; elements.
    (macrolet ((maybe-store-match (path matched-len)
         `(cond ((> ,matched-len matching-length)
             (setf matches (list ,path))
             (setf matching-length ,matched-len))
            ((= ,matched-len matching-length)
             (cons ,path matches)))))
      (dotimes (i (length source-paths))
    (declare (fixnum i))
    (let ((sp (svref source-paths i)))
      ;; Remember, first element of sp is a code-location.
      (do ((path-ptr path (cdr path-ptr))
           (sp-ptr (cdr sp) (cdr sp-ptr))
           (count 0 (1+ count)))
          ((or (null path-ptr) (null sp-ptr))
           (when (null sp-ptr)
         (maybe-store-match sp count)))
        (declare (list sp-ptr path-ptr)
             (fixnum count))
        (unless (= (the fixnum (car path-ptr)) (the fixnum (car sp-ptr)))
          (maybe-store-match sp count))))))
    ;; If there's just one, set it; otherwise, return the conflict set.
    (cond ((and (= (length matches) 1) (equal path (cdar matches)))
       (let* ((bpt (make-breakpoint
            #'(lambda (frame bpt)
                (declare (ignore frame bpt))
                (break "Editor installed breakpoint."))
            (wire:remote-object-value (caar matches))))
          (remote-bpt (wire:make-remote-object bpt)))
         (activate-breakpoint bpt)
         ;;(push remote-bpt (gethash name *editor-breakpoints*))
         remote-bpt))
      (t matches))))

;;; This maps components to vectors of modified source-paths.  We assume users
;;; will set multiple breakpoints in a given function which entails computing
;;; this data repeatedly.  Possibly the GC hook should free this cache.  The
;;; source-paths are modified in the following ways:
;;;    1] The form number element (first) is clobbered with the code-location
;;;       corresponding to the source-path.
;;;    2] The top-level-form offset element (last) is thrown away.
;;;    3] Everything after the first element is reversed, so the modified
;;;       source-path actually portrays a descent into the form.
;;;
(defvar *component-source-locations* (make-hash-table :test #'eq))

;;; GENERATE-COMPONENT-SOURCE-PATHS -- Internal.
;;;
;;; This returns a vector of modified source-paths, one for every code-location
;;; in component.  The source-paths are modified as described for
;;; *component-source-locations*.
;;;
(defun generate-component-source-paths (component)
  (or (gethash component *component-source-locations*)
      (setf (gethash component *component-source-locations*)
        (sub-generate-component-source-paths component))))

;;; This maps source-infos to hashtables that map top-level-form offsets to
;;; modified form-number translations (as returned by
;;; FORM-NUMBER-TRANSLATIONS).  These are modified as described for
;;; *component-source-locations*.
;;;
(defvar *source-info-offset-translations* (make-hash-table :test #'eq))

;;; This is a hacking space for SUB-GENERATE-COMPONENT-SOURCE-PATHS.  We use
;;; this because we throw away many source-paths we accumulate in this buffer
;;; since they are not associated with code-locations.
;;;
(defvar *source-paths-buffer* (make-array 50 :fill-pointer t :adjustable t))

;;; SUB-GENERATE-COMPONENT-SOURCE-PATHS -- Internal.
;;;
;;; We iterate over the code-locations in component, fetching their
;;; source-infos and using the *source-info-offset-translations* cache.  This
;;; computation often repeatedly sees the same source-info/tlf-offset pair, so
;;; we see many source-paths from one form-number-translation table.  Because
;;; of this, when we add a form-number-translations table to this cache, we add
;;; all the source-paths in it to the result immediately.  Then later if we see
;;; the same (not EQ though) source-info/tlf-offset form-number-translations,
;;; we can simply check if one of the source-paths is already in the result,
;;; and if it is, then all of them already are.  We keep the cache around
;;; between invocations since we expect multiple breakpoints to be set in the
;;; same function, and this is why we must check if a form-number-translations
;;; has been added to the result; just its presence in the cache does not mean
;;; it is in the result vector.
;;;
(defun sub-generate-component-source-paths (component)
  (let ((info (kernel:code-debug-info component)))
    (unless info (debug-signal 'no-debug-info))
    (let* ((function-map (get-debug-info-function-map info))
       (result *source-paths-buffer*))
      (declare (simple-vector function-map)
           (vector result))
      (setf (fill-pointer result) 0)
      (flet ((copy-stuff (form-num-trans result)
           (declare (simple-vector form-num-trans)
            (vector result))
           (dotimes (i (length form-num-trans))
         (declare (fixnum i))
         (vector-push-extend (svref form-num-trans i) result)))
         (convert-paths (form-num-trans)
           (declare (simple-vector form-num-trans))
           (dotimes (i (length form-num-trans) form-num-trans)
         (declare (fixnum i))
         (let* ((source-path (svref form-num-trans i)))
           (declare (list source-path))
           ;; Make the first cons point to the reversal of everything
           ;; else, but throw away what was the last element before the
           ;; reversal.
           (setf (cdr source-path)
             ;; Must copy the rest of the list, so REVERSE, but
             ;; the first cons cell of each list is unique.
             (cdr (reverse (cdr source-path))))))))
    ;; Get all possible source-paths, modifying any new additions to the
    ;; cache.
    (do ((i 0 (+ i 2))
         (len (length function-map)))
        ((>= i len))
      (declare (type c::index i))
      (let ((d-fun (make-compiled-debug-function (svref function-map i)
                             component)))
        (do-debug-function-blocks (d-block d-fun)
          (do-debug-block-locations (loc d-block)
        (let* ((d-source (code-location-debug-source loc))
               (translations (gethash d-source
                          *source-info-offset-translations*))
               (tlf-offset (code-location-top-level-form-offset loc))
               (loc-num (code-location-form-number loc)))
          (cond
           (translations
            (let ((form-num-trans (gethash tlf-offset translations)))
              (declare (type (or simple-vector null) form-num-trans))
              (cond
               ((not form-num-trans)
            (let ((form-num-trans (get-form-number-translations
                           d-source tlf-offset)))
              (declare (simple-vector form-num-trans))
              (setf (gethash tlf-offset translations) form-num-trans)
              (copy-stuff (convert-paths form-num-trans) result)
              (setf (car (svref form-num-trans loc-num))
                (wire:make-remote-object loc))))
               ;; If one of these source-paths is in our result, then
               ;; they all are.
               ((find (svref form-num-trans 0) result :test #'eq)
            (setf (car (svref form-num-trans loc-num))
                  (wire:make-remote-object loc)))
               ;; Otherwise, store these source-paths in the result.
               (t
            (copy-stuff form-num-trans result)
            (setf (car (svref form-num-trans loc-num))
                  (wire:make-remote-object loc))))))
           (t
            (let ((translations (make-hash-table :test #'eq))
              (form-num-trans (get-form-number-translations
                       d-source tlf-offset)))
              (declare (simple-vector form-num-trans))
              (setf (gethash d-source *source-info-offset-translations*)
                translations)
              (setf (gethash tlf-offset translations) form-num-trans)
              (copy-stuff (convert-paths form-num-trans) result)
              (setf (car (svref form-num-trans loc-num))
                (wire:make-remote-object loc)))))))))))
      ;; Copy source-paths with code-locations from the result buffer to a
      ;; real result vector.
      (let* ((count (count-if #'(lambda (x) (wire:remote-object-p (car x)))
                  result))
         (the-real-thing (make-array count))
         (i -1))
    (declare (simple-vector the-real-thing)
         (fixnum i count))
    (dotimes (j count)
      (loop (when (wire:remote-object-p (car (aref result (incf i))))
          (return)))
      (setf (svref the-real-thing j) (aref result i)))
    the-real-thing))))

;;; GET-FORM-NUMBER-TRANSLATIONS -- Internal.
;;;
;;; This returns a vector of form-number translations to source-paths for
;;; d-source and the top-level-form indicated by the top-level-form offset.
;;;
(defun get-form-number-translations (d-source tlf-offset)
  (let ((name (debug-source-name d-source)))
    (ecase (debug-source-from d-source)
      (:file
       (cond
    ((not (probe-file name))
     (format t "~%Cannot set breakpoints for editor when source file no ~
            longer exists:~%  ~A."
         (namestring name)))
    (t
     (let* ((local-tlf-offset (- tlf-offset
                     (debug-source-root-number d-source)))
        (char-offset
         (aref (or (debug-source-start-positions d-source)
               (error "Cannot set breakpoints for editor when ~
                   there is no start positions map."))
               local-tlf-offset)))
       (with-open-file (f name)
         (cond
          ((= (debug-source-created d-source) (file-write-date name))
           (file-position f char-offset))
          (t
           (format t
               "~%While setting a breakpoint for the editor, noticed ~
            source file has been modified since compilation:~%  ~A~@
            Using form offset instead of character position.~%"
               (namestring name))
           (dotimes (i local-tlf-offset) (read f))))
         (form-number-translations (read f) tlf-offset))))))
      ((:lisp :stream)
       (form-number-translations (svref name tlf-offset) tlf-offset)))))

;;; SET-LOCATION-BREAKPOINT-FOR-EDITOR -- Internal Interface.
;;;
(defun set-location-breakpoint-for-editor (remote-obj-loc)
  "The editor calls this in the slave with a remote-object representing a
   code-location to set a breakpoint."
  (let ((loc (wire:remote-object-value remote-obj-loc)))
    (etypecase loc
      (interpreted-code-location
       (error "Breakpoints in interpreted code are currently unsupported."))
      (compiled-code-location
       (let* ((bpt (make-breakpoint #'(lambda (frame bpt)
                    (declare (ignore frame bpt))
                    (break "Editor installed breakpoint."))
                    loc))
          (remote-bpt (wire:make-remote-object bpt)))
     (activate-breakpoint bpt)
     ;;(push remote-bpt (gethash name *editor-breakpoints*))
     remote-bpt)))))

;;;
;;; Deleting breakpoints.
;;;

;;; DELETE-BREAKPOINT-FOR-EDITOR -- Internal Interface.
;;;
(defun delete-breakpoint-for-editor (remote-obj-bpt)
  "The editor calls this remotely in the slave to delete a breakpoint."
  (delete-breakpoint (wire:remote-object-value remote-obj-bpt))
  (wire:forget-remote-translation remote-obj-bpt))



;;;; Miscellaneous

;;; This appears here because it cannot go with the debug-function interface
;;; since DO-DEBUG-BLOCK-LOCATIONS isn't defined until after the debug-function
;;; routines.
;;;

;;; DEBUG-FUNCTION-START-LOCATION -- Public.
;;;
(defun debug-function-start-location (debug-fun)
  "This returns a code-location before the body of a function and after all
   the arguments are in place.  If this cannot determine that location due to
   a lack of debug information, it returns nil."
  (etypecase debug-fun
    (compiled-debug-function
     (code-location-from-pc debug-fun
                (c::compiled-debug-function-start-pc
                 (compiled-debug-function-compiler-debug-fun
                  debug-fun))
                nil))
    (interpreted-debug-function
     ;; Return the first location if there are any, otherwise nil.
     (handler-case (do-debug-function-blocks (block debug-fun nil)
             (do-debug-block-locations (loc block nil)
               (return-from debug-function-start-location loc)))
       (no-debug-blocks (condx)
     (declare (ignore condx))
     nil)))))



(defun print-code-locations (function)
  (let ((debug-fun (function-debug-function function)))
    (do-debug-function-blocks (block debug-fun)
      (do-debug-block-locations (loc block)
    (fill-in-code-location loc)
    (format t "~S code location at ~D"
        (compiled-code-location-kind loc)
        (compiled-code-location-pc loc))
    (debug::print-code-location-source-form loc 0)
    (terpri)))))