X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/aa14a4cddcb96b681d5c19a2ec8bad382f43b264..9ec578d9fe450b7e7f9030dc9d930185593aa991:/src/codegen-proto.lisp diff --git a/src/codegen-proto.lisp b/src/codegen-proto.lisp index 24b8c38..b8206fa 100644 --- a/src/codegen-proto.lisp +++ b/src/codegen-proto.lisp @@ -38,13 +38,14 @@ (export 'var-in-use-p) (defgeneric var-in-use-p (var) (:documentation - "Answer whether VAR is currently being used. See WITH-TEMPORARY-VAR.") + "Answer whether VAR is currently being used. See `with-temporary-var'.") (:method (var) "Non-temporary variables are always in use." + (declare (ignore var)) t)) (defgeneric (setf var-in-use-p) (value var) (:documentation - "Record whether VAR is currently being used. See WITH-TEMPORARY-VAR.")) + "Record whether VAR is currently being used. See `with-temporary-var'.")) ;; Root class. @@ -61,10 +62,10 @@ 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." - ;; FIXME: this is currently a lie. Need some protocol to ensure that this - ;; happens. -) + file is always produced from the same input.") + +(define-clear-the-decks reset-codegen-index + (setf *temporary-index* 0)) ;; Important temporary names. @@ -85,12 +86,12 @@ "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. + generator. Both statements and expressions 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. + 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.")) @@ -100,14 +101,21 @@ (: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. + 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)) + (:method ((inst t)) + (declare (ignore inst)) + 1) + (:method ((inst null)) + (declare (ignore inst)) + 1) + (:method ((inst list)) + (reduce #'+ inst :key #'inst-metric))) ;; Instruction definition. @@ -115,19 +123,19 @@ (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: + 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. + * A class `CODE-inst' to represent the instruction. * Instance slots named after the ARGS, with matching keyword initargs, - and INST-ARG readers. + and `inst-ARG' readers. - * A constructor MAKE-CODE-INST which accepts the ARGS (in order, not + * 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 + * 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." @@ -184,7 +192,7 @@ ;; Formatting utilities. (defun format-compound-statement* (stream child morep thunk) - "Underlying function for FORMAT-COMPOUND-STATEMENT." + "Underlying function for `format-compound-statement'." (cond ((typep child 'block-inst) (funcall thunk stream) (write-char #\space stream) @@ -211,7 +219,7 @@ "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 + 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))) @@ -224,16 +232,16 @@ (export 'codegen-functions) (defgeneric codegen-functions (codegen) (:documentation - "Return the list of FUNCTION-INSTs of completed functions.")) + "Return the list of `function-inst's of completed functions.")) (export 'ensure-var) (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 + 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 + non-nil it is an expression `inst' used to provide the variable with an initial value.")) (export '(emit-inst emit-insts)) @@ -267,7 +275,7 @@ "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.")) + willing to find in the list returned by `codegen-functions'.")) (export 'temporary-var) (defgeneric temporary-var (codegen type) @@ -276,8 +284,8 @@ 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.")) + with the variable -- or, better, use `with-temporary-var' to do the + cleanup automatically.")) (export 'codegen-build-function) (defun codegen-build-function (codegen name type vars insts) @@ -292,7 +300,7 @@ (export 'codegen-pop-block) (defgeneric codegen-pop-block (codegen) (:documentation - "Makes a block (BLOCK-INST) out of the completed code in CODEGEN.") + "Makes a block (`block-inst') out of the completed code in CODEGEN.") (:method (codegen) (multiple-value-bind (vars insts) (codegen-pop codegen) (make-block-inst vars insts)))) @@ -313,7 +321,7 @@ "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." + available for re-use." `(let ((,var (temporary-var ,codegen ,type))) (unwind-protect (progn ,@body) @@ -328,22 +336,22 @@ The TARGET may be one of the following. - * :VOID, indicating that the value is to be discarded. The expression + * `: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. + * `: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. + * `: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." + 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))) @@ -354,24 +362,24 @@ (export 'convert-stmts) (defun convert-stmts (codegen target type func) - "Invoke FUNC to deliver a value to a non-:RETURN target. + "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 + 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...)) + (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." + The `convert-stmts' function 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)