;;; compiler.lisp ---
-;; copyright (C) 2013 David Vazquez
+;; Copyright (C) 2013 David Vazquez
;; JSCL is free software: you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
(in-package :jscl)
-;;;; Utils
+;;;; Utilities
+;;;;
+;;;; Random Common Lisp code useful to use here and there.
(defmacro with-gensyms ((&rest vars) &body body)
- `(let ,(mapcar (lambda (var) `(,var (gensym ,(string var)))) vars)
+ `(let ,(mapcar (lambda (var) `(,var (gensym ,(concatenate 'string (string var) "-")))) vars)
,@body))
(defun singlep (x)
(assert (singlep x))
(first x))
-;;;; Lexical environment
-;;;;
-;;;; The Lexical environment is compromised of a list of bindings,
-;;;; which associates information to symbols. It tracks lexical
-;;;; variables, tags, local declarations and many other information in
-;;;; order to guide the compiler.
+(defun generic-printer (x stream)
+ (print-unreadable-object (x stream :type t :identity t)))
-(defstruct binding
- name type value declarations)
+;;; A generic counter mechanism. IDs are used generally for debugging
+;;; purposes. You can bind *counter-alist* to NIL to reset the
+;;; counters in a dynamic extent.
+(defvar *counter-alist* nil)
+(defun generate-id (class)
+ (let ((e (assoc class *counter-alist*)))
+ (if e
+ (incf (cdr e))
+ (prog1 1
+ (push (cons class 1) *counter-alist*)))))
-(defstruct lexenv
- bindings)
-
-;;;; Intermediate representation
+;;;; Intermediate representation structures
;;;;
;;;; This intermediate representation (IR) is a simplified version of
-;;;; first intermediate representation what you will find if you have
-;;;; a you have the source code of SBCL. Some terminology is also
+;;;; the first intermediate representation what you will find if you
+;;;; have a look to the source code of SBCL. Some terminology is also
;;;; used, but other is changed, so be careful if you assume you know
;;;; what it is because you know the name.
;;;;
+;;;; Computations are represented by `node'. Nodes are grouped
+;;;; sequencially into `basic-block'. It is a plain representation
+;;;; rather than a nested one. Computations take data and produce a
+;;;; value. Both data transfer are represented by `lvar'.
-;;; A leaf stands for leaf in the tree of computations. Lexical
-;;; variables, constants and literal functions are leafs. Leafs are
-;;; not nodes itself, a `ref' node will stands for putting a leaf into
-;;; a lvar, which can be used in computations.
(defstruct leaf)
-;;; Reference a lexical variable. Special variables have not a
-;;; representation in IR. They are handled via the primitive functions
-;;; `%symbol-function' and `%symbol-value'.
+;;; A (lexical) variable. Special variables has not a special
+;;; representation in the IR. They are handled by the primitive
+;;; functions `%symbol-function' and `%symbol-value'.
(defstruct (var (:include leaf))
- ;; Name is the symbol used to identify this variable in the lexical
- ;; environment.
+ ;; The symbol which names this variable in the source code.
name)
-;;; A constant value, mostly from a quoted form, but maybe introduced
-;;; in some pass of the compiler.
+;;; A literal Lisp object. It usually comes from a quoted expression.
(defstruct (constant (:include leaf))
+ ;; The object itself.
value)
-;;; A literal function. Why do we use `functional' as name? Well,
-;;; function is taken, isn't it?
-(defstruct (functional (:include leaf))
- ;; The symbol which names this function in the source code.
+;;; A lambda expression. Why do we name it `functional'? Well,
+;;; function is reserved by the ANSI, isn't it?
+(defstruct (functional (:include leaf) (:print-object generic-printer))
+ ;; The symbol which names this function in the source code or null
+ ;; if we do not know or it is an anonymous function.
name
- ;; A list of lvars which are bound to the argument values in a call
- ;; to this function.
arguments
- ;; LVAR which contains the return values of the function.
return-lvar
- ;; The basic block which contain the code which be executed firstly
- ;; when you call this function.
- entry-point)
-
+ component)
-;;; Used to transfer data between the computations in the intermediate
-;;; representation. Each node is valued into a LVar. And nodes which
-;;; use resulting values from other nodes use such LVar.
+;;; An abstract place where the result of a computation is stored and
+;;; it can be referenced from other nodes, so lvars are responsible
+;;; for keeping the necessary information of the nested structure of
+;;; the code in this plain representation.
(defstruct lvar
- (id (gensym "$")))
-
-;;; A computation node. It represents a simple computation in the
-;;; intermediate representation. Nodes are grouped in basic blocks,
-;;; which are delimited by the special nodes `block-entry' and
-;;; `block-exit'. Resulting value of the node is stored in LVAR, which it
-;;; could be null if the value is discarded.
-(defstruct node
- next
- prev
+ (id (generate-id 'lvar)))
+
+;;; A base structure for every single computation. Most of the
+;;; computations are valued.
+(defstruct (node (:print-object generic-printer))
+ ;; The next and the prev slots are the next nodes and the previous
+ ;; node in the basic block sequence respectively.
+ next prev
+ ;; Lvar which stands for the result of the computation of this node.
lvar)
-;;; Sentinel nodes. No computation really, but they make easier to
-;;; manipulate the doubly linked-list.
+;;; Sentinel nodes in the basic block sequence of nodes.
(defstruct (block-entry (:include node)))
(defstruct (block-exit (:include node)))
-;;; A reference to a leaf.
+;;; A reference to a leaf (variable, constant and functions). The
+;;; meaning of this node is leaving the leaf into the lvar of the
+;;; node.
(defstruct (ref (:include node))
leaf)
variable
value)
-;;; Call the lvar FUNCTION with a list of lvars as ARGUMENTS.
-(defstruct (call (:include node))
- function
+;;; A base node to function calls with a list of lvar as ARGUMENTS.
+(defstruct (combination (:include node) (:constructor))
arguments)
+;;; A function call to the ordinary Lisp function in the lvar FUNCTION.
+(defstruct (call (:include combination))
+ function)
+
+;;; A function call to the primitive FUNCTION.
+(defstruct (primitive-call (:include combination))
+ function)
+
+
;;; A conditional branch. If the LVAR is not NIL, then we will jump to
;;; the basic block CONSEQUENT, jumping to ALTERNATIVE otherwise. By
;;; definition, a conditional must appear at the end of a basic block.
consequent
alternative)
-;;; Blocks are `basic block', which is a maximal sequence of nodes
-;;; with an entry point and an exit. Basic blocks are organized as a
-;;; control flow graph with some more information in omponents.
+
+
+;;; Blocks are `basic block`. Basic blocks are organized as a control
+;;; flow graph with some more information in omponents.
(defstruct (basic-block
(:conc-name "BLOCK-")
(:constructor make-block)
- (:predicate block-p))
- (id (gensym "L"))
- succ
- pred
- entry
- exit)
-
+ (:predicate block-p)
+ (:print-object generic-printer))
+ (id (generate-id 'basic-block))
+ ;; List of successors and predecessors of this basic block. They are
+ ;; null only for deleted blocks and component's entry and exit.
+ succ pred
+ ;; The sentinel nodes of the sequence.
+ entry exit
+ ;; The component where the basic block belongs to.
+ component
+ ;; The order in the reverse post ordering of the blocks.
+ order
+ ;; A bit-vector representing the set of dominators. See the function
+ ;; `compute-dominators' to know how to use it properly.
+ dominators%
+ ;; Arbitrary data which could be necessary to keep during IR
+ ;; processing.
+ data)
+
+;;; Sentinel nodes in the control flow graph of basic blocks.
(defstruct (component-entry (:include basic-block)))
(defstruct (component-exit (:include basic-block)))
-(defun make-empty-block ()
- (let ((entry (make-block-entry))
- (exit (make-block-exit)))
- (setf (node-next entry) exit
- (node-prev exit) entry)
- (make-block :entry entry :exit exit)))
-
+;;; Return T if B is an empty basic block and NIL otherwise.
(defun empty-block-p (b)
- (block-exit-p (node-next (block-entry b))))
+ (or (boundary-block-p b)
+ (block-exit-p (node-next (block-entry b)))))
+
+(defun boundary-block-p (block)
+ (or (component-entry-p block)
+ (component-exit-p block)))
+;;; Iterate across the nodes in a basic block forward.
(defmacro do-nodes
((node block &optional result &key include-sentinel-p) &body body)
`(do ((,node ,(if include-sentinel-p
,result)
,@body))
+;;; Iterate across the nodes in a basic block backward.
(defmacro do-nodes-backward
((node block &optional result &key include-sentinel-p) &body body)
`(do ((,node ,(if include-sentinel-p
(node-prev to) from)
(values))
-;;; Components are connected pieces of the control flow graph with
-;;; some additional information. Components have well-defined entry
-;;; and exit nodes. They also track what basic blocks we have and
-;;; other useful information. It is the toplevel organizational entity
-;;; in the compiler. The IR translation result is accumulated into
-;;; components incrementally.
-(defstruct (component #-jscl (:print-object print-component))
- entry
- exit)
-
-;;; Create a new component, compromised of the sentinel nodes and a
-;;; empty basic block, ready to start conversion to IR. It returnes
-;;; the component and the basic block as multiple values.
-(defun make-empty-component ()
- (let ((entry (make-component-entry))
- (block (make-empty-block))
- (exit (make-component-exit)))
- (setf (block-succ entry) (list block)
- (block-pred exit) (list block)
- (block-succ block) (list exit)
- (block-pred block) (list entry))
- (values (make-component :entry entry :exit exit) block)))
-
-;;; Return the list of blocks in COMPONENT.
-(defun component-blocks (component)
- (let ((output nil))
- (labels ((compute-rdfo-from (block)
- (unless (or (component-exit-p block) (find block output))
- (dolist (successor (block-succ block))
- (unless (component-exit-p block)
- (compute-rdfo-from successor)))
- (push block output))))
- (compute-rdfo-from (unlist (block-succ (component-entry component))))
- output)))
-
-;;; Iterate across different blocks in COMPONENT.
-(defmacro do-blocks ((block component &optional result) &body body)
- `(dolist (,block (component-blocks ,component) ,result)
- ,@body))
-(defun delete-empty-block (block)
- (when (or (component-entry-p block) (component-exit-p block))
- (error "Cannot delete entry or exit basic blocks."))
- (unless (empty-block-p block)
- (error "Block `~S' is not empty!" (block-id block)))
- (let ((succ (unlist (block-succ block))))
- (setf (block-pred succ) (remove block (block-pred succ)))
- (dolist (pred (block-pred block))
- (setf (block-succ pred) (substitute succ block (block-succ pred)))
- (pushnew pred (block-pred succ)))))
-
-(defun finish-component (component)
- (do-blocks (block component)
- (when (empty-block-p block)
- (delete-empty-block block))))
-
-;;; IR Translation
-
-;;; The current component. We accumulate the results of the IR
-;;; conversion in this component.
+;;; Components are connected pieces of the control flow graph of
+;;; basic blocks with some additional information. Components have
+;;; well-defined entry and exit nodes. It is the toplevel
+;;; organizational entity in the compiler. The IR translation result
+;;; is accumulated into components incrementally.
+(defstruct (component (:print-object generic-printer))
+ (id (generate-id 'component))
+ name
+ entry
+ exit
+ functions
+ ;; TODO: Replace with a flags slot for indicate what
+ ;; analysis/transformations have been carried out.
+ reverse-post-order-p
+ blocks)
+
+;;; The current component.
(defvar *component*)
+;;; Create a new fresh empty basic block in the current component.
+(defun make-empty-block ()
+ (let ((entry (make-block-entry))
+ (exit (make-block-exit)))
+ (link-nodes entry exit)
+ (let ((block (make-block :entry entry :exit exit :component *component*)))
+ (push block (component-blocks *component*))
+ block)))
+
+;;; Create a new component with an empty basic block, ready to start
+;;; conversion to IR. It returns the component and the basic block as
+;;; multiple values.
+(defun make-empty-component (&optional name)
+ (let ((*component* (make-component :name name)))
+ (let ((entry (make-component-entry :component *component*))
+ (exit (make-component-exit :component *component*))
+ (block (make-empty-block)))
+ (push entry (component-blocks *component*))
+ (push exit (component-blocks *component*))
+ (setf (block-succ entry) (list block)
+ (block-pred exit) (list block)
+ (block-succ block) (list exit)
+ (block-pred block) (list entry)
+ (component-entry *component*) entry
+ (component-exit *component*) exit)
+ (values *component* block))))
+
+;;; A few consistency checks in the IR useful for catching bugs.
+(defun check-ir-consistency (&optional (component *component*))
+ (with-simple-restart (continue "Continue execution")
+ (dolist (block (component-blocks component))
+ (dolist (succ (block-succ block))
+ (unless (find block (block-pred succ))
+ (error "The block `~S' does not belong to the predecessors list of the its successor `~S'"
+ block succ))
+ (unless (or (boundary-block-p succ) (find succ (component-blocks component)))
+ (error "Block `~S' is reachable from its predecessor `~S' but it is not in the component `~S'"
+ succ block component)))
+ (dolist (pred (block-pred block))
+ (unless (find block (block-succ pred))
+ (error "The block `~S' does not belong to the successors' list of its predecessor `~S'"
+ block pred))
+ (unless (or (boundary-block-p pred) (find pred (component-blocks component)))
+ (error "Block `~S' is reachable from its sucessor `~S' but it is not in the component `~S'"
+ pred block component))))))
+
;;; Prepare a new component with a current empty block ready to start
;;; IR conversion bound in the current cursor. BODY is evaluated and
;;; the value of the last form is returned.
-(defmacro with-component-compilation (&body body)
- (let ((block (gensym)))
+(defmacro with-component-compilation ((&optional name) &body body)
+ (with-gensyms (block)
`(multiple-value-bind (*component* ,block)
- (make-empty-component)
- (with-cursor (:block ,block)
+ (make-empty-component ,name)
+ (let ((*cursor* (cursor :block ,block)))
,@body))))
-;;; A cursor stands for a point between two nodes in some basic block
-;;; in the IR representation where manipulations can take place,
-;;; similarly to the cursors in text editing.
+;;; Call function for each reachable block in component in
+;;; post-order. The consequences are unspecified if a block is
+;;; FUNCTION modifies a block which has not been processed yet.
+(defun map-postorder-blocks (function component)
+ (let ((seen nil))
+ (labels ((compute-from (block)
+ (unless (find block seen)
+ (push block seen)
+ (dolist (successor (block-succ block))
+ (unless (component-exit-p block)
+ (compute-from successor)))
+ (funcall function block))))
+ (compute-from (component-entry component))
+ nil)))
+
+;;; Change all the predecessors of BLOCK to precede NEW-BLOCK
+;;; instead. As consequence, BLOCK becomes unreachable.
+(defun replace-block (block new-block)
+ (let ((predecessors (block-pred block)))
+ (setf (block-pred block) nil)
+ (dolist (pred predecessors)
+ (pushnew pred (block-pred new-block))
+ (setf (block-succ pred) (substitute new-block block (block-succ pred)))
+ (unless (component-entry-p pred)
+ (let ((last-node (node-prev (block-exit pred))))
+ (when (conditional-p last-node)
+ (macrolet ((replacef (place)
+ `(setf ,place (if (eq block ,place) new-block ,place))))
+ (replacef (conditional-consequent last-node))
+ (replacef (conditional-alternative last-node)))))))))
+
+(defun delete-block (block)
+ (when (boundary-block-p block)
+ (error "Cannot delete entry or exit basic blocks."))
+ (unless (null (cdr (block-succ block)))
+ (error "Cannot delete a basic block with multiple successors."))
+ ;; If the block has not successors, then it is already deleted. So
+ ;; just skip it.
+ (when (block-succ block)
+ (let ((successor (unlist (block-succ block))))
+ (replace-block block successor)
+ ;; At this point, block is unreachable, however we could have
+ ;; backreferences to it from its successors. Let's get rid of
+ ;; them.
+ (setf (block-pred successor) (remove block (block-pred successor)))
+ (setf (block-succ block) nil))))
+
+
+;;;; Cursors
+;;;;
+;;;; A cursor is a point between two nodes in some basic block in the
+;;;; IR representation where manipulations can take place, similarly
+;;;; to the cursors in text editing.
+;;;;
+;;;; Cursors cannot point to special component's entry and exit basic
+;;;; blocks or after a conditional node. Conveniently, the `cursor'
+;;;; function will signal an error if the cursor is not positioned
+;;;; correctly, so the rest of the code does not need to check once
+;;;; and again.
+
(defstruct cursor
block next)
-;;; The current cursor. It is the point where IR manipulations act by
-;;; default. Particularly, newly converted IR code is inserted here.
+;;; The current cursor. It is the default cursor for many functions
+;;; which work on cursors.
(defvar *cursor*)
-;;; Create a cursor which pointsto the basic block BLOCK. If omitted,
+;;; Return the current basic block. It is to say, the basic block
+;;; where the current cursor is pointint.
+(defun current-block ()
+ (cursor-block *cursor*))
+
+;;; Create a cursor which points to the basic block BLOCK. If omitted,
;;; then the current block is used.
;;;
-;;; The keywords AFTER and BEFORE specify the cursor will point after
-;;; or before that node respectively. If none is specified, the cursor
-;;; is created before the exit node in BLOCK. An error is signaled if
-;;; both keywords are specified inconsistently, or if the nodes do not
-;;; belong to BLOCK.
+;;; The keywords AFTER and BEFORE specify the cursor will point after (or
+;;; before) that node respectively. If none is specified, the cursor is
+;;; created before the exit node in BLOCK. An error is signaled if both
+;;; keywords are specified inconsistently, or if the nodes do not belong
+;;; to BLOCK.
;;;
-;;; The special values :ENTRY and :EXIT stands for the entry and exit
-;;; nodes of the block respectively.
-(defun cursor (&key (block (cursor-block *cursor*))
+;;; AFTER and BEFORE could also be the special values :ENTRY and :EXIT,
+;;; which stand for the entry and exit nodes of the block respectively.
+(defun cursor (&key (block (current-block))
(before nil before-p)
(after nil after-p))
+ (when (boundary-block-p block)
+ (error "Invalid cursor on special entry/exit basic block."))
;; Handle special values :ENTRY and :EXIT.
(flet ((node-designator (x)
(case x
(error "Out of range cursor."))
(ambiguous-cursor ()
(error "Ambiguous cursor specified between two non-adjacent nodes.")))
+ (when (conditional-p (node-prev next))
+ (error "Invalid cursor after conditional node."))
(when (or (null next) (block-entry-p next))
(out-of-range-cursor))
(when (and before-p after-p (not (eq after before)))
(when (eq next node) (return))))
cursor))
+;;; Accept a cursor specification just as described in `cursor'
+;;; describing a position in the IR and modify destructively the
+;;; current cursor to point there.
(defun set-cursor (&rest cursor-spec)
(let ((newcursor (apply #'cursor cursor-spec)))
(setf (cursor-block *cursor*) (cursor-block newcursor))
(setf (cursor-next *cursor*) (cursor-next newcursor))
*cursor*))
-;;; Create and bind the current cursor. The cursor specification is
-;;; the same as described in the function `create-cursor'.
-(defmacro with-cursor ((&rest cursor-spec) &body body)
- `(let* ((*cursor* (cursor ,@cursor-spec)))
- ,@body))
-
-(defun end-of-block-p (&optional (cursor *cursor*))
- (block-exit-p (cursor-next cursor)))
-
;;; Insert NODE at cursor.
(defun insert-node (node &optional (cursor *cursor*))
(link-nodes (node-prev (cursor-next cursor)) node)
(link-nodes node (cursor-next cursor))
t)
-;;; Split the block CURSOR points in two basic blocks, returning the
-;;; new basic block. The cursor is kept to point at the end of shrunk
-;;; basic block.
+;;; Split the block at CURSOR. The cursor will point to the end of the
+;;; first basic block. Return the three basic blocks as multiple
+;;; values.
(defun split-block (&optional (cursor *cursor*))
+ ;; <aaaaa|zzzzz> ==> <aaaaa|>--<zzzzz>
(let* ((block (cursor-block cursor))
- (exit (block-exit block))
- newblock
(newexit (make-block-exit))
- (newentry (make-block-entry)))
+ (newentry (make-block-entry))
+ (exit (block-exit block))
+ (newblock (make-block :entry newentry
+ :exit exit
+ :pred (list block)
+ :succ (block-succ block)
+ :component *component*)))
(insert-node newexit)
(insert-node newentry)
(setf (node-next newexit) nil)
(setf (node-prev newentry) nil)
(setf (block-exit block) newexit)
- (setq newblock (make-block :entry newentry :exit exit))
- (shiftf (block-succ newblock) (block-succ block) (list newblock))
+ (setf (block-succ block) (list newblock))
+ (dolist (succ (block-succ newblock))
+ (setf (block-pred succ) (substitute newblock block (block-pred succ))))
+ (set-cursor :block block :before newexit)
+ (push newblock (component-blocks *component*))
newblock))
+;;; Split the block at CURSOR if it is in the middle of it. The cursor
+;;; will point to the end of the first basic block. Return the three
+;;; basic blocks as multiple values.
+(defun maybe-split-block (&optional (cursor *cursor*))
+ ;; If we are converting IR into the end of the basic block, it's
+ ;; fine, we don't need to do anything.
+ (unless (block-exit-p (cursor-next cursor))
+ (split-block cursor)))
+
+
+;;;; Lexical environment
+;;;;
+;;;; It keeps an association between names and the IR entities. It is
+;;;; used to guide the translation from the Lisp source code to the
+;;;; intermediate representation.
+
+(defstruct binding
+ name namespace type value)
+
+(defvar *lexenv* nil)
+
+(defun find-binding (name namespace)
+ (find-if (lambda (b)
+ (and (eq (binding-name b) name)
+ (eq (binding-namespace b) namespace)))
+ *lexenv*))
+
+(defun push-binding (name namespace value &optional type)
+ (push (make-binding :name name
+ :namespace namespace
+ :type type
+ :value value)
+ *lexenv*))
+
+
+;;;; IR Translation
+;;;;
+;;;; This code covers the translation from Lisp source code to the
+;;;; intermediate representation. The main entry point function to do
+;;;; that is the `ir-convert' function, which dispatches to IR
+;;;; translators. This function ss intended to do the initial
+;;;; conversion as well as insert new IR code during optimizations.
;;; A alist of IR translator functions.
(defvar *ir-translator* nil)
-;;; Define a IR translator for NAME.
+;;; Define a IR translator for NAME. LAMBDA-LIST is used to
+;;; destructure the arguments of the form. Calling the local function
+;;; `result-lvar' you can get the LVAR where the compilation of the
+;;; expression should store the result of the evaluation.
+;;;
+;;; The cursor is granted to be at the end of a basic block with a
+;;; unique successor, and so it should be when the translator returns.
(defmacro define-ir-translator (name lambda-list &body body)
(check-type name symbol)
- (let ((fname (intern (format nil "IR-CONVERT-~a" (string name))))
- (result (gensym))
- (form (gensym)))
- `(progn
- (defun ,fname (,form ,result)
- (flet ((result-lvar () ,result))
- (destructuring-bind ,lambda-list ,form
- ,@body)))
- (push (cons ',name #',fname) *ir-translator*))))
+ (let ((fname (intern (format nil "IR-CONVERT-~a" (string name)))))
+ (with-gensyms (result form)
+ `(progn
+ (defun ,fname (,form ,result)
+ (flet ((result-lvar () ,result))
+ (declare (ignorable (function result-lvar)))
+ (destructuring-bind ,lambda-list ,form
+ ,@body)))
+ (push (cons ',name #',fname) *ir-translator*)))))
+
+;;; Return the unique successor of the current block. If it is not
+;;; unique signal an error.
+(defun next-block ()
+ (unlist (block-succ (current-block))))
+
+;;; Set the next block of the current one.
+(defun (setf next-block) (new-value)
+ (let ((block (current-block)))
+ (dolist (succ (block-succ block))
+ (setf (block-pred succ) (remove block (block-pred succ))))
+ (setf (block-succ block) (list new-value))
+ (push block (block-pred new-value))
+ new-value))
(defun ir-convert-constant (form result)
(let* ((leaf (make-constant :value form)))
(ir-convert-constant form (result-lvar)))
(define-ir-translator setq (variable value)
- (let ((var (make-var :name variable))
- (value-lvar (make-lvar)))
- (ir-convert value value-lvar)
- (let ((assign (make-assignment :variable var :value value-lvar :lvar (result-lvar))))
- (insert-node assign))))
+ (let ((b (find-binding variable 'variable)))
+ (cond
+ (b
+ (let ((var (make-var :name variable))
+ (value-lvar (make-lvar)))
+ (ir-convert value value-lvar)
+ (let ((assign (make-assignment :variable var :value value-lvar :lvar (result-lvar))))
+ (insert-node assign))))
+ (t
+ (ir-convert `(set ',variable ,value) (result-lvar))))))
(define-ir-translator progn (&body body)
- (dolist (form (butlast body))
- (ir-convert form))
+ (mapc #'ir-convert (butlast body))
(ir-convert (car (last body)) (result-lvar)))
(define-ir-translator if (test then &optional else)
- (when (conditional-p (cursor-next *cursor*))
- (error "Impossible to insert a conditional after another conditional."))
- ;; Split the basic block if we are in the middle of one.
- (unless (end-of-block-p) (split-block))
+ ;; It is the schema of how the basic blocks will look like
+ ;;
+ ;; / ..then.. \
+ ;; <aaaaXX> --< >-- <|> -- <zzzz>
+ ;; \ ..else.. /
+ ;;
+ ;; Note that is important to leave the cursor in an empty basic
+ ;; block, as zzz could be the exit basic block of the component,
+ ;; which is an invalid position for a cursor.
(let ((test-lvar (make-lvar))
- (then-block (make-empty-block))
- (else-block (make-empty-block))
- (join-block (make-empty-block)))
+ (then-block (make-empty-block))
+ (else-block (make-empty-block))
+ (join-block (make-empty-block)))
(ir-convert test test-lvar)
(insert-node (make-conditional :test test-lvar :consequent then-block :alternative else-block))
- (let* ((block (cursor-block *cursor*))
- (tail-block (unlist (block-succ block))))
+ (let* ((block (current-block))
+ (tail-block (next-block)))
;; Link together the different created basic blocks.
(setf (block-succ block) (list else-block then-block)
(block-pred else-block) (list block)
(ir-convert else (result-lvar) (cursor :block else-block))
(set-cursor :block join-block)))
+(define-ir-translator block (name &body body)
+ (let ((new (split-block)))
+ (push-binding name 'block (cons (next-block) (result-lvar)))
+ (ir-convert `(progn ,@body) (result-lvar))
+ (set-cursor :block new)))
+
+(define-ir-translator return-from (name &optional value)
+ (let ((binding
+ (or (find-binding name 'block)
+ (error "Tried to return from unknown block `~S' name" name))))
+ (destructuring-bind (jump-block . lvar)
+ (binding-value binding)
+ (ir-convert value lvar)
+ (setf (next-block) jump-block)
+ ;; This block is really unreachable, even if the following code
+ ;; is labelled in a tagbody, as tagbody will create a new block
+ ;; for each label. However, we have to leave the cursor
+ ;; somewhere to convert new input.
+ (let ((dummy (make-empty-block)))
+ (set-cursor :block dummy)))))
+
+(define-ir-translator tagbody (&rest statements)
+ (flet ((go-tag-p (x)
+ (or (integerp x) (symbolp x))))
+ (let* ((tags (remove-if-not #'go-tag-p statements))
+ (tag-blocks nil))
+ ;; Create a chain of basic blocks for the tags, recording each
+ ;; block in a alist in TAG-BLOCKS.
+ (let ((*cursor* *cursor*))
+ (dolist (tag tags)
+ (setq *cursor* (cursor :block (split-block)))
+ (push-binding tag 'tag (current-block))
+ (if (assoc tag tag-blocks)
+ (error "Duplicated tag `~S' in tagbody." tag)
+ (push (cons tag (current-block)) tag-blocks))))
+ ;; Convert the statements into the correct block.
+ (dolist (stmt statements)
+ (if (go-tag-p stmt)
+ (set-cursor :block (cdr (assoc stmt tag-blocks)))
+ (ir-convert stmt))))))
+
+(define-ir-translator go (label)
+ (let ((tag-binding
+ (or (find-binding label 'tag)
+ (error "Unable to jump to the label `~S'" label))))
+ (setf (next-block) (binding-value tag-binding))
+ ;; Unreachable block.
+ (let ((dummy (make-empty-block)))
+ (set-cursor :block dummy))))
+
+
+(defun ir-convert-functoid (result name arguments &rest body)
+ (let ((component)
+ (return-lvar (make-lvar)))
+ (with-component-compilation (name)
+ (ir-convert `(progn ,@body) return-lvar)
+ (ir-normalize)
+ (setq component *component*))
+ (let ((functional
+ (make-functional
+ :name name
+ :arguments arguments
+ :component component
+ :return-lvar return-lvar)))
+ (push functional (component-functions *component*))
+ (insert-node (make-ref :leaf functional :lvar result)))))
+
+(define-ir-translator function (name)
+ (if (atom name)
+ (ir-convert `(symbol-function ,name) (result-lvar))
+ (ecase (car name)
+ ((lambda named-lambda)
+ (let ((desc (cdr name)))
+ (when (eq 'lambda (car name))
+ (push nil desc))
+ (apply #'ir-convert-functoid (result-lvar) desc)))
+ (setf))))
(defun ir-convert-var (form result)
- (let* ((leaf (make-var :name form))
- (ref (make-ref :leaf leaf :lvar result)))
- (insert-node ref)))
+ (let ((binds (find-binding form 'variable)))
+ (if binds
+ (insert-node (make-ref :leaf (binding-value binds) :lvar result))
+ (ir-convert `(symbol-value ',form) result))))
(defun ir-convert-call (form result)
(destructuring-bind (function &rest args) form
(let ((func-lvar (make-lvar))
(args-lvars nil))
- (when (symbolp function)
- (ir-convert `(%symbol-function ,function) func-lvar))
+ ;; Argument list
(dolist (arg args)
(let ((arg-lvar (make-lvar)))
(push arg-lvar args-lvars)
(ir-convert arg arg-lvar)))
(setq args-lvars (reverse args-lvars))
- (let ((call (make-call :function func-lvar :arguments args-lvars :lvar result)))
- (insert-node call)))))
-
-;;; Convert the Lisp expression FORM into IR before the NEXT node, it
-;;; may create new basic blocks into the current component. During the
-;;; initial IR conversion, The NEXT node is the EXIT node of the
-;;; current basic block, but optimizations could call it to insert IR
-;;; code somewhere.
+ ;; Funcall
+ (if (find-primitive function)
+ (insert-node (make-primitive-call
+ :function (find-primitive function)
+ :arguments args-lvars
+ :lvar result))
+ (progn
+ (ir-convert `(symbol-function ,function) func-lvar)
+ (insert-node (make-call :function func-lvar
+ :arguments args-lvars
+ :lvar result)))))))
+
+;;; Convert the Lisp expression FORM, it may create new basic
+;;; blocks. RESULT is the lvar representing the result of the
+;;; computation or null if the value should be discarded. The IR is
+;;; inserted at *CURSOR*.
(defun ir-convert (form &optional result (*cursor* *cursor*))
+ ;; Rebinding the lexical environment here we make sure that the
+ ;; lexical information introduced by FORM is just available for
+ ;; subforms.
+ (let ((*lexenv* *lexenv*))
+ ;; Possibly create additional blocks in order to make sure the
+ ;; cursor is at end the end of a basic block.
+ (maybe-split-block)
+ (cond
+ ((atom form)
+ (cond
+ ((symbolp form)
+ (ir-convert-var form result))
+ (t
+ (ir-convert-constant form result))))
+ (t
+ (destructuring-bind (op &rest args) form
+ (let ((translator (cdr (assoc op *ir-translator*))))
+ (if translator
+ (funcall translator args result)
+ (ir-convert-call form result))))))
+ (values)))
+
+
+;;;; IR Normalization
+;;;;
+;;;; IR as generated by `ir-convert' or after some transformations is
+;;;; not appropiated. Here, we remove unreachable and empty blocks and
+;;;; coallesce blocks when it is possible.
+
+;;; Try to coalesce BLOCK with the successor if it is unique and block
+;;; is its unique predecessor.
+(defun maybe-coalesce-block (block)
+ (when (and (singlep (block-succ block)) (not (component-entry-p block)))
+ (let ((succ (first (block-succ block))))
+ (when (and (not (component-exit-p succ)) (singlep (block-pred succ)))
+ (link-nodes (node-prev (block-exit block))
+ (node-next (block-entry succ)))
+ (setf (block-exit block) (block-exit succ))
+ (setf (block-succ block) (block-succ succ))
+ (dolist (next (block-succ succ))
+ (setf (block-pred next) (substitute block succ (block-pred next))))
+ (setf (block-succ succ) nil
+ (block-pred succ) nil)
+ t))))
+
+;;; Normalize a component. This function must be called after a batch
+;;; of modifications to the flowgraph of the component to make sure it
+;;; is a valid input for the possible optimizations and the backend.
+(defun ir-normalize (&optional (component *component*))
+ ;; Initialize blocks as unreachables and remove empty basic blocks.
+ (dolist (block (component-blocks component))
+ (setf (block-data block) 'unreachable))
+ ;; Coalesce and mark blocks as reachable.
+ (map-postorder-blocks #'maybe-coalesce-block component)
+ (map-postorder-blocks (lambda (block)
+ (setf (block-data block) 'reachable))
+ component)
+ (let ((block-list nil))
+ (dolist (block (component-blocks component))
+ (cond
+ ;; If the block is unreachable, but it is predeces a reachable
+ ;; one, then break the link between them. So we discard it
+ ;; from the flowgraph.
+ ((eq (block-data block) 'unreachable)
+ (dolist (succ (block-succ block))
+ (when (eq (block-data succ) 'reachable)
+ (setf (block-pred succ) (remove block (block-pred succ)))))
+ (setf (block-succ block) nil))
+ ;; Delete empty blocks
+ ((and (empty-block-p block)
+ (not (boundary-block-p block))
+ ;; We cannot delete a block if it is its own successor,
+ ;; even thought it is empty.
+ (not (member block (block-succ block))))
+ (delete-block block))
+ ;; The rest of blocks remain in the component.
+ (t
+ (push block block-list))))
+ (setf (component-blocks component) block-list))
+ (check-ir-consistency))
+
+
+;;;; IR Analysis
+;;;;
+;;;; Once IR conversion has been finished. We do some analysis of the
+;;;; component to produce information which is useful for both
+;;;; optimizations and code generation. Indeed, we provide some
+;;;; abstractions to use this information.
+
+(defun compute-reverse-post-order (component)
+ (let ((output nil)
+ (index (length (component-blocks component))))
+ (flet ((add-block-to-list (block)
+ (push block output)
+ (setf (block-order block) (decf index))))
+ (map-postorder-blocks #'add-block-to-list component))
+ (setf (component-reverse-post-order-p component) t)
+ (setf (component-blocks component) output)))
+
+
+(defmacro do-blocks% ((block component &optional reverse ends result) &body body)
+ (with-gensyms (g!component g!blocks)
+ `(let* ((,g!component ,component)
+ (,g!blocks ,(if reverse
+ `(reverse (component-blocks ,g!component))
+ `(component-blocks ,g!component))))
+ ;; Do we have the information available?
+ (unless (component-reverse-post-order-p ,g!component)
+ (error "Reverse post order was not computed yet."))
+ (dolist (,block ,(if (member ends '(:head :both))
+ `,g!blocks
+ `(cdr ,g!blocks))
+ ,result)
+ ,@(if (member ends '(:tail :both))
+ nil
+ `((if (component-exit-p ,block) (return))))
+ ,@body))))
+
+;;; Iterate across blocks in COMPONENT in reverse post order.
+(defmacro do-blocks-forward ((block component &optional ends result) &body body)
+ `(do-blocks% (,block ,component nil ,ends ,result)
+ ,@body))
+
+;;; Iterate across blocks in COMPONENT in reverse post order.
+(defmacro do-blocks-backward ((block component &optional ends result) &body body)
+ `(do-blocks% (,block (reverse ,component) t ,ends ,result)
+ ,@body))
+
+
+(defun compute-dominators (component)
+ ;; Initialize the dominators of the entry to the component to be
+ ;; empty and the power set of the set of blocks for proper basic
+ ;; blocks in the component.
+ (let ((n (length (component-blocks component))))
+ ;; The component entry special block has not predecessors in the
+ ;; set of (proper) basic blocks.
+ (setf (block-dominators% (component-entry component))
+ (make-array n :element-type 'bit :initial-element 0))
+ (setf (aref (block-dominators% (component-entry component)) 0) 1)
+ (do-blocks-forward (block component :tail)
+ (setf (block-dominators% block) (make-array n :element-type 'bit :initial-element 1))))
+ ;; Iterate across the blocks in the component removing non domintors
+ ;; until it reaches a fixed point.
+ (do ((i 1 1)
+ (changes t))
+ ((not changes))
+ (setf changes nil)
+ (do-blocks-forward (block component :tail)
+ ;; We compute the new set of dominators for this iteration in a
+ ;; fresh set NEW-DOMINATORS. So we do NOT modify the old
+ ;; dominators. It is important because the block could predeces
+ ;; itself. Indeed, it allows us to check if the set of
+ ;; dominators changed.
+ (let* ((predecessors (block-pred block))
+ (new-dominators (copy-seq (block-dominators% (first predecessors)))))
+ (dolist (pred (rest predecessors))
+ (bit-and new-dominators (block-dominators% pred) t))
+ (setf (aref new-dominators i) 1)
+ (unless changes
+ (setq changes (not (equal (block-dominators% block) new-dominators))))
+ (setf (block-dominators% block) new-dominators)
+ (incf i)))))
+
+;;; Return T if BLOCK1 dominates BLOCK2, else return NIL.
+(defun dominate-p (block1 block2)
+ (let ((order (block-order block1)))
+ (= 1 (aref (block-dominators% block2) order))))
+
+;;; Check if BLOCK is a loop header. It is to say if it dominates one
+;;; of its predecessors.
+(defun loop-header-p (block)
+ (some (lambda (pred) (dominate-p block pred))
+ (block-pred block)))
+
+;;; This function duplicates the block in component for each input
+;;; edge. A technique useful to make a general flowgraph reducible.
+(defun node-splitting (block)
+ (let ((predecessors (block-pred block)))
+ (when predecessors
+ (setf (block-pred block) (list (car predecessors)))
+ (dolist (pred (cdr predecessors))
+ (let ((newblock (copy-basic-block block)))
+ (setf (block-id newblock) (generate-id 'basic-block))
+ (push newblock (component-blocks (block-component block)))
+ (setf (block-pred newblock) (list pred))
+ (setf (block-succ pred) (substitute newblock block (block-succ pred))))))))
+
+
+
+;;;; IR Debugging
+;;;;
+;;;; This section provides a function `/print' which write a textual
+;;;; representation of a component to the standard output. Also, a
+;;;; `/ir' macro is provided, which takes a form, convert it to IR and
+;;;; then print the component as above. They are useful commands if
+;;;; you are hacking the front-end of the compiler.
+;;;;
+
+(defun format-block-name (block)
(cond
- ((atom form)
- (cond
- ((symbolp form)
- (ir-convert-var form result))
- (t
- (ir-convert-constant form result))))
+ ((eq block (unlist (block-succ (component-entry (block-component block)))))
+ (format nil "ENTRY-~a" (component-id (block-component block))))
+ ((component-exit-p block)
+ (format nil "EXIT-~a" (component-id (block-component block))))
(t
- (destructuring-bind (op &rest args) form
- (let ((translator (cdr (assoc op *ir-translator*))))
- (if translator
- (funcall translator args result)
- (ir-convert-call form result))))))
- (values))
-
+ (format nil "BLOCK ~a" (block-id block)))))
-;;; IR Debugging
(defun print-node (node)
(when (node-lvar node)
- (format t "~a = " (lvar-id (node-lvar node))))
+ (format t "$~a = " (lvar-id (node-lvar node))))
(cond
((ref-p node)
(let ((leaf (ref-leaf node)))
((var-p leaf)
(format t "~a" (var-name leaf)))
((constant-p leaf)
- (format t "'~a" (constant-value leaf)))
+ (format t "'~s" (constant-value leaf)))
((functional-p leaf)
- (format t "#<function ~a at ~a>"
- (functional-name leaf)
- (functional-entry-point leaf))))))
+ (format t "#<function ~a>" (functional-name leaf))))))
((assignment-p node)
- (format t "set ~a ~a"
+ (format t "set ~a $~a"
(var-name (assignment-variable node))
(lvar-id (assignment-value node))))
+ ((primitive-call-p node)
+ (format t "primitive ~a" (primitive-name (primitive-call-function node)))
+ (dolist (arg (primitive-call-arguments node))
+ (format t " $~a" (lvar-id arg))))
((call-p node)
- (format t "call ~a" (lvar-id (call-function node)))
+ (format t "call $~a" (lvar-id (call-function node)))
(dolist (arg (call-arguments node))
- (format t " ~a" (lvar-id arg))))
+ (format t " $~a" (lvar-id arg))))
((conditional-p node)
- (format t "if ~a ~a ~a"
+ (format t "if $~a then ~a else ~a~%"
(lvar-id (conditional-test node))
- (block-id (conditional-consequent node))
- (block-id (conditional-alternative node))))
+ (format-block-name (conditional-consequent node))
+ (format-block-name (conditional-alternative node))))
(t
(error "`print-node' does not support printing ~S as a node." node)))
(terpri))
(defun print-block (block)
- (flet ((block-name (block)
- (cond
- ((and (singlep (block-pred block))
- (component-entry-p (block-pred block)))
- "ENTRY")
- ((component-exit-p block)
- "EXIT")
- (t (string (block-id block))))))
- (format t "BLOCK ~a:~%" (block-name block))
- (do-nodes (node block)
- (print-node node))
- (when (singlep (block-succ block))
- (format t "GO ~a~%" (block-name (first (block-succ block)))))
- (terpri)))
-
-(defun print-component (component &optional (stream *standard-output*))
+ (write-string (format-block-name block))
+ (if (loop-header-p block)
+ (write-line " [LOOP_HEADER]")
+ (terpri))
+ (do-nodes (node block)
+ (print-node node))
+ (when (singlep (block-succ block))
+ (format t "GO ~a~%~%" (format-block-name (unlist (block-succ block))))))
+
+(defun /print (component &optional (stream *standard-output*))
+ (format t ";;; COMPONENT ~a (~a) ~%~%" (component-name component) (component-id component))
(let ((*standard-output* stream))
- (do-blocks (block component)
- (print-block block))))
-
-;;; A few consistency checks in the IR useful for catching bugs.
-(defun check-ir-consistency (&optional (component *component*))
- (with-simple-restart (continue "Continue execution")
- (do-blocks (block component)
- (dolist (succ (block-succ block))
- (unless (find block (block-pred succ))
- (error "The block `~S' does not belong to the predecessors list of the its successor `~S'"
- (block-id block)
- (block-id succ))))
- (dolist (pred (block-pred block))
- (unless (find block (block-succ pred))
- (error "The block `~S' does not belong to the successors' list of its predecessor `~S'"
- (block-id block)
- (block-id pred)))))))
+ (do-blocks-forward (block component)
+ (print-block block)))
+ (format t ";;; END COMPONENT ~a ~%~%" (component-name component))
+ (let ((*standard-output* stream))
+ (dolist (func (component-functions component))
+ (/print (functional-component func)))))
;;; Translate FORM into IR and print a textual repreresentation of the
;;; component.
-(defun describe-ir (form)
- (with-component-compilation
- (ir-convert form (make-lvar :id "$out"))
- (finish-component *component*)
- (check-ir-consistency)
- (print-component *component*)))
+(defun convert-toplevel-and-print (form)
+ (let ((*counter-alist* nil))
+ (with-component-compilation ('toplevel)
+ (ir-convert form (make-lvar :id "out"))
+ (ir-normalize)
+ (compute-reverse-post-order *component*)
+ (compute-dominators *component*)
+ (/print *component*)
+ *component*)))
+
+(defmacro /ir (form)
+ `(convert-toplevel-and-print ',form))
+
+
+
+;;;; Primitives
+;;;;
+;;;; Primitive functions are a set of functions provided by the
+;;;; compiler. They cannot usually be written in terms of other
+;;;; functions. When the compiler tries to compile a function call, it
+;;;; looks for a primitive function firstly, and if it is found and
+;;;; the declarations allow it, a primitive call is inserted in the
+;;;; IR. The back-end of the compiler knows how to compile primitive
+;;;; calls.
+;;;;
+
+(defvar *primitive-function-table* nil)
+
+(defstruct primitive
+ name)
+
+(defmacro define-primitive (name args &body body)
+ (declare (ignore args body))
+ `(push (make-primitive :name ',name)
+ *primitive-function-table*))
+
+(defun find-primitive (name)
+ (find name *primitive-function-table* :key #'primitive-name))
+
+(define-primitive symbol-function (symbol))
+(define-primitive symbol-value (symbol))
+(define-primitive set (symbol value))
+(define-primitive fset (symbol value))
+
+(define-primitive + (&rest numbers))
+(define-primitive - (number &rest other-numbers))
+
+(define-primitive consp (x))
+(define-primitive cons (x y))
+(define-primitive car (x))
+(define-primitive cdr (x))
;;; compiler.lisp ends here
projects / jscl.git / blobdiff