--- /dev/null
+;;; -*-lisp-*-
+;;;
+;;; Code generator for effective methods
+;;;
+;;; (c) 2009 Straylight/Edgeware
+;;;
+
+;;;----- Licensing notice ---------------------------------------------------
+;;;
+;;; This file is part of the Simple Object Definition system.
+;;;
+;;; SOD is free software; you can redistribute it and/or modify
+;;; it under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 2 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; SOD is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with SOD; if not, write to the Free Software Foundation,
+;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+(cl:in-package #:sod)
+
+;;;--------------------------------------------------------------------------
+;;; Temporary names.
+
+(defclass temporary-name ()
+ ((tag :initarg :tag :reader temp-tag))
+ (:documentation
+ "Base class for temporary variable and argument names."))
+
+(defclass temporary-argument (temporary-name) ())
+(defclass temporary-function (temporary-name) ())
+
+(defclass temporary-variable (temporary-name)
+ ((in-use-p :initarg :in-use-p
+ :initform nil
+ :type boolean
+ :accessor var-in-use-p)))
+
+(defmethod var-in-use-p ((var t))
+ "Non-temporary variables are always in use."
+ t)
+
+(defmethod commentify-argument-name ((name temporary-name))
+ nil)
+
+(defparameter *temporary-index* 0
+ "Index for temporary name generation.
+
+ This is automatically reset to zero before the output functions are
+ invoked to write a file. This way, we can ensure that the same output
+ file is always produced from the same input.")
+
+(defun temporary-function ()
+ "Return a temporary function name."
+ (make-instance 'temporary-function
+ :tag (prog1 *temporary-index* (incf *temporary-index*))))
+
+(defgeneric format-temporary-name (var stream)
+ (:method ((var temporary-name) stream)
+ (format stream "~A" (temp-tag var)))
+ (:method ((var temporary-argument) stream)
+ (format stream "sod__a~A" (temp-tag var)))
+ (:method ((var temporary-variable) stream)
+ (format stream "sod__v~A" (temp-tag var)))
+ (:method ((var temporary-function) stream)
+ (format stream "sod__f~A" (temp-tag var))))
+
+(defmethod print-object ((var temporary-name) stream)
+ (if *print-escape*
+ (print-unreadable-object (var stream :type t)
+ (prin1 (temp-tag var) stream))
+ (format-temporary-name var stream)))
+
+(defparameter *sod-ap*
+ (make-instance 'temporary-name :tag "sod__ap"))
+(defparameter *sod-master-ap*
+ (make-instance 'temporary-name :tag "sod__master_ap"))
+
+;;;--------------------------------------------------------------------------
+;;; Instructions.
+
+(defclass inst () ()
+ (:documentation
+ "A base class for instructions.
+
+ An `instruction' is anything which might be useful to string into a code
+ generator. Both statements and expressions map can be represented by
+ trees of instructions. The DEFINST macro is a convenient way of defining
+ new instructions.
+
+ The only important protocol for instructions is output, which is achieved
+ by calling PRINT-OBJECT with *PRINT-ESCAPE* nil.
+
+ This doesn't really do very much, but it acts as a handy marker for
+ instruction subclasses."))
+
+(defgeneric inst-metric (inst)
+ (:documentation
+ "Returns a `metric' describing how complicated INST is.
+
+ The default metric of an inst node is simply 1; INST subclasses generated
+ by DEFINST (q.v.) have an automatically generated method which returns one
+ plus the sum of the metrics of the node's children.
+
+ This isn't intended to be a particularly rigorous definition. Its purpose
+ is to allow code generators to make decisions about inlining or calling
+ code fairly simply.")
+ (:method (inst) 1))
+
+(defmacro definst (code (streamvar) args &body body)
+ "Define an instruction type and describe how to output it.
+
+ An INST can represent any structured piece of output syntax: a statement,
+ expression or declaration, for example. This macro defines the following
+ things:
+
+ * A class CODE-INST to represent the instruction.
+
+ * Instance slots named after the ARGS, with matching keyword initargs,
+ and INST-ARG readers.
+
+ * A constructor MAKE-CODE-INST which accepts the ARGS (in order, not
+ with keywords) as arguments and returns a fresh instance.
+
+ * A print method, which prints a diagnostic dump if *PRINT-ESCAPE* is
+ set, or invokes the BODY (with STREAMVAR bound to the output stream)
+ otherwise. The BODY is expected to produce target code at this
+ point."
+
+ (let ((inst-var (gensym "INST"))
+ (class-name (symbolicate code '-inst))
+ (keys (mapcar (lambda (arg) (intern (symbol-name arg) :keyword))
+ args)))
+ `(progn
+ (defclass ,class-name (inst)
+ ,(mapcar (lambda (arg key)
+ `(,arg :initarg ,key :reader ,(symbolicate 'inst- arg)))
+ args keys))
+ (defun ,(symbolicate 'make- code '-inst) (,@args)
+ (make-instance ',class-name ,@(mappend #'list keys args)))
+ (defmethod inst-metric ((,inst-var ,class-name))
+ (with-slots (,@args) ,inst-var
+ (+ 1 ,@(mapcar (lambda (arg) `(inst-metric ,arg)) args))))
+ (defmethod print-object ((,inst-var ,class-name) ,streamvar)
+ (with-slots (,@args) ,inst-var
+ (if *print-escape*
+ (print-unreadable-object (,inst-var ,streamvar :type t)
+ (format stream "~@<~@{~S ~@_~S~^ ~_~}~:>"
+ ,@(mappend #'list keys args)))
+ (progn ,@body)))))))
+
+(defun format-compound-statement* (stream child morep thunk)
+ "Underlying function for FORMAT-COMPOUND-STATEMENT."
+ (cond ((typep child 'block-inst)
+ (funcall thunk stream)
+ (write-char #\space stream)
+ (princ child stream)
+ (when morep (write-char #\space stream)))
+ (t
+ (pprint-logical-block (stream nil)
+ (funcall thunk stream)
+ (write-char #\space stream)
+ (pprint-indent :block 2 stream)
+ (pprint-newline :linear stream)
+ (princ child stream)
+ (pprint-indent :block 0 stream)
+ (case morep
+ (:space
+ (write-char #\space stream)
+ (pprint-newline :linear stream))
+ (t
+ (pprint-newline :mandatory stream)))))))
+
+(defmacro format-compound-statement
+ ((stream child &optional morep) &body body)
+ "Format a compound statement to STREAM.
+
+ The introductory material is printed by BODY. The CHILD is formatted
+ properly according to whether it's a BLOCK-INST. If MOREP is true, then
+ allow for more stuff following the child."
+ `(format-compound-statement* ,stream ,child ,morep
+ (lambda (,stream) ,@body)))
+
+;;;--------------------------------------------------------------------------
+;;; Instruction types.
+
+;; Compound statements.
+
+(definst block (stream) (decls body)
+ (format stream "{~:@_~@< ~2I~@[~{~A;~:@_~}~:@_~]~{~A~^~:@_~}~:>~:@_}"
+ decls body))
+
+(definst if (stream) (condition consequent alternative)
+ (format-compound-statement (stream consequent alternative)
+ (format stream "if (~A)" condition))
+ (when alternative
+ (format-compound-statement (stream alternative)
+ (write-string "else" stream))))
+
+(definst while (stream) (condition body)
+ (format-compound-statement (stream body)
+ (format stream "while (~A)" condition)))
+
+(definst do-while (stream) (body condition)
+ (format-compound-statement (stream body :space)
+ (write-string "do" stream))
+ (format stream "while (~A);" condition))
+
+;; Simple statements.
+
+(definst set (stream) (var expr)
+ (format stream "~@<~A = ~@_~2I~A;~:>" var expr))
+
+(definst return (stream) (expr)
+ (format stream "return~@[ (~A)~];" expr))
+
+(definst expr (stream) (expr)
+ (format stream "~A;" expr))
+
+;; Special varargs hacks.
+
+(definst va-start (stream) (ap arg)
+ (format stream "va_start(~@<~A, ~_~A~:>);" ap arg))
+
+(definst va-copy (stream) (to from)
+ (format stream "va_copy(~@<~A, ~_~A~:>);" to from))
+
+(definst va-end (stream) (ap)
+ (format stream "va_end(~A);" ap))
+
+;; Declarations. These should appear at the heads of BLOCK-INSTs.
+
+(definst var (stream) (name type init)
+ (pprint-c-type type stream name)
+ (when init
+ (format stream " = ~A" init)))
+
+;; Expressions.
+
+(definst call (stream) (func args)
+ (format stream "~A(~@<~{~A~^, ~_~}~:>)" func args))
+
+;; Top level things.
+
+(definst function (stream) (name type body)
+ (pprint-logical-block (stream nil)
+ (pprint-c-type type stream name)
+ (format stream "~:@_~A~:@_~:@_" body)))
+
+;;;--------------------------------------------------------------------------
+;;; Code generator objects.
+
+(defclass basic-codegen ()
+ ((vars :initarg :vars :initform nil :type list :accessor codegen-vars)
+ (insts :initarg :insts :initform nil :type list :accessor codegen-insts)
+ (temp-index :initarg :temp-index
+ :initform 0
+ :type fixnum
+ :accessor codegen-temp-index))
+ (:documentation
+ "Base class for code generator state.
+
+ This contains the bare essentials for supporting the EMIT-INST and
+ ENSURE-VAR protocols; see the documentation for those generic functions
+ for more details.
+
+ This class isn't abstract. A full CODEGEN object uses instances of this
+ to keep track of pending functions which haven't been completed yet.
+
+ Just in case that wasn't clear enough: this is nothing to do with the
+ BASIC language."))
+
+(defgeneric emit-inst (codegen inst)
+ (:documentation
+ "Add INST to the end of CODEGEN's list of instructions.")
+ (:method ((codegen basic-codegen) inst)
+ (push inst (codegen-insts codegen))))
+
+(defgeneric emit-insts (codegen insts)
+ (:documentation
+ "Add a list of INSTS to the end of CODEGEN's list of instructions.")
+ (:method ((codegen basic-codegen) insts)
+ (setf (codegen-insts codegen)
+ (revappend insts (codegen-insts codegen)))))
+
+(defgeneric ensure-var (codegen name type &optional init)
+ (:documentation
+ "Add a variable to CODEGEN's list.
+
+ The variable is called NAME (which should be comparable using EQUAL and
+ print to an identifier) and has the given TYPE. If INIT is present and
+ non-nil it is an expression INST used to provide the variable with an
+ initial value.")
+ (:method ((codegen basic-codegen) name type &optional init)
+ (let* ((vars (codegen-vars codegen))
+ (var (find name vars :key #'inst-name :test #'equal)))
+ (cond ((not var)
+ (setf (codegen-vars codegen)
+ (cons (make-var-inst name type init) vars)))
+ ((not (c-type-equal-p type (inst-type var)))
+ (error "(Internal) Redefining type for variable ~A." name)))
+ name)))
+
+(defclass codegen (basic-codegen)
+ ((functions :initform nil :type list :accessor codegen-functions)
+ (stack :initform nil :type list :accessor codegen-stack))
+ (:documentation
+ "A full-fat code generator which can generate and track functions.
+
+ This is the real deal. Subclasses may which to attach additional state
+ for convenience's sake, but this class is self-contained. It supports the
+ CODEGEN-PUSH, CODEGEN-POP and CODEGEN-POP-FUNCTION protocols."))
+
+(defgeneric codegen-push (codegen)
+ (:documentation
+ "Pushes the current code generation state onto a stack.
+
+ The state consists of the accumulated variables and instructions, i.e.,
+ what is representable by a BASIC-CODEGEN.")
+ (:method ((codegen codegen))
+ (with-slots (vars insts temp-index stack) codegen
+ (push (make-instance 'basic-codegen
+ :vars vars
+ :insts insts
+ :temp-index temp-index)
+ stack)
+ (setf vars nil insts nil temp-index 0))))
+
+(defgeneric codegen-pop (codegen)
+ (:documentation
+ "Pops a saved state off of the CODEGEN's stack.
+
+ Returns the newly accumulated variables and instructions as lists, as
+ separate values.")
+ (:method ((codegen codegen))
+ (with-slots (vars insts temp-index stack) codegen
+ (multiple-value-prog1
+ (values (nreverse vars) (nreverse insts))
+ (let ((sub (pop stack)))
+ (setf vars (codegen-vars sub)
+ insts (codegen-insts sub)
+ temp-index (codegen-temp-index sub)))))))
+
+(defgeneric codegen-add-function (codegen function)
+ (:documentation
+ "Adds a function to CODEGEN's list.
+
+ Actually, we're not picky: FUNCTION can be any kind of object that you're
+ willing to find in the list returned by CODEGEN-FUNCTIONS.")
+ (:method ((codegen codegen) function)
+ (with-slots (functions) codegen
+ (setf functions (nconc functions (list function))))))
+
+(defun codegen-build-function (codegen name type vars insts)
+ "Build a function and add it to CODEGEN's list.
+
+ Returns the function's name."
+ (codegen-add-function codegen
+ (make-function-inst name type
+ (make-block-inst vars insts)))
+ name)
+
+(defgeneric codegen-pop-function (codegen name type)
+ (:documentation
+ "Makes a function out of the completed code in CODEGEN.
+
+ The NAME can be any object you like. The TYPE should be a function type
+ object which includes argument names. The return value is the NAME.")
+ (:method ((codegen codegen) name type)
+ (multiple-value-bind (vars insts) (codegen-pop codegen)
+ (codegen-build-function codegen name type vars insts))))
+
+(defgeneric temporary-var (codegen type)
+ (:documentation
+ "Return the name of a temporary variable.
+
+ The temporary variable will have the given TYPE, and will be marked
+ in-use. You should clear the in-use flag explicitly when you've finished
+ with the variable -- or, better, use WITH-TEMPORARY-VAR to do the cleanup
+ automatically."))
+
+(defmethod temporary-var ((codegen basic-codegen) type)
+ (with-slots (vars temp-index) codegen
+ (or (find-if (lambda (var)
+ (and (not (var-in-use-p (inst-name var)))
+ (c-type-equal-p type (inst-type var))))
+ vars)
+ (let* ((name (make-instance 'temporary-variable
+ :tag (prog1 temp-index
+ (incf temp-index)))))
+ (push (make-var-inst name type nil) vars)
+ name))))
+
+(defmacro with-temporary-var ((codegen var type) &body body)
+ "Evaluate BODY with VAR bound to a temporary variable name.
+
+ During BODY, VAR will be marked in-use; when BODY ends, VAR will be marked
+ available for re-use."
+ `(let ((,var (temporary-var ,codegen ,type)))
+ (unwind-protect
+ (progn ,@body)
+ (setf (var-in-use-p ,var) nil))))
+
+;;;--------------------------------------------------------------------------
+;;; Code generation idioms.
+
+(defun deliver-expr (codegen target expr)
+ "Emit code to deliver the value of EXPR to the TARGET.
+
+ The TARGET may be one of the following.
+
+ * :VOID, indicating that the value is to be discarded. The expression
+ will still be evaluated.
+
+ * :VOID-RETURN, indicating that the value is to be discarded (as for
+ :VOID) and furthermore a `return' from the current function should be
+ forced after computing the value.
+
+ * :RETURN, indicating that the value is to be returned from the current
+ function.
+
+ * A variable name, indicating that the value is to be stored in the
+ variable.
+
+ In the cases of :RETURN, :VOID and :VOID-RETURN targets, it is valid for
+ EXPR to be nil; this signifies that no computation needs to be performed.
+ Variable-name targets require an expression."
+
+ (case target
+ (:return (emit-inst codegen (make-return-inst expr)))
+ (:void (when expr (emit-inst codegen (make-expr-inst expr))))
+ (:void-return (when expr (emit-inst codegen (make-expr-inst expr)))
+ (emit-inst codegen (make-return-inst nil)))
+ (t (emit-inst codegen (make-set-inst target expr)))))
+
+(defun convert-stmts (codegen target type func)
+ "Invoke FUNC to deliver a value to a non-:RETURN target.
+
+ FUNC is a function which accepts a single argument, a non-:RETURN target,
+ and generates statements which deliver a value (see DELIVER-EXPR) of the
+ specified TYPE to this target. In general, the generated code will have
+ the form
+
+ setup instructions...
+ (DELIVER-EXPR CODEGEN TARGET (compute value...))
+ cleanup instructions...
+
+ where the cleanup instructions are essential to the proper working of the
+ generated program.
+
+ CONVERT-STMTS will call FUNC to generate code, and arrange that its value
+ is correctly delivered to TARGET, regardless of what the TARGET is --
+ i.e., it lifts the restriction to non-:RETURN targets. It does this by
+ inventing a new temporary variable."
+
+ (case target
+ (:return (with-temporary-var (codegen var type)
+ (funcall func var)
+ (deliver-expr codegen target var)))
+ (:void-return (funcall func :void)
+ (emit-inst codegen (make-return-inst nil)))
+ (t (funcall func target))))
+
+;;;----- That's all, folks --------------------------------------------------
~mdw / sod / blobdiff