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f472dd8ea5
Ensure in cconv that let-bindings have the normal form (VAR EXPR) where VAR is a valid variable name, so that we don't need to keep re-checking this all the time in the optimiser. * lisp/emacs-lisp/byte-opt.el (byte-optimize-enable-variable-constprop) (byte-optimize-warn-eliminated-variable): Remove; these were mainly used for debugging. * lisp/emacs-lisp/byte-opt.el (byte-optimize-let-form): Assume normalised let-bindings (with lexical-binding). Stop using the variables removed above. * lisp/emacs-lisp/cconv.el (cconv-convert): Ensure normalised let-bindings. Malformed bindings are dropped after warning. remove byte-optimize-warn-eliminated-variable
807 lines
35 KiB
EmacsLisp
807 lines
35 KiB
EmacsLisp
;;; cconv.el --- Closure conversion for statically scoped Emacs Lisp. -*- lexical-binding: t -*-
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;; Copyright (C) 2011-2021 Free Software Foundation, Inc.
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;; Author: Igor Kuzmin <kzuminig@iro.umontreal.ca>
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;; Maintainer: emacs-devel@gnu.org
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;; Keywords: lisp
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;; Package: emacs
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; This takes a piece of Elisp code, and eliminates all free variables from
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;; lambda expressions. The user entry points are cconv-closure-convert and
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;; cconv-closure-convert-toplevel (for toplevel forms).
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;; All macros should be expanded beforehand.
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;;
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;; Here is a brief explanation how this code works.
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;; Firstly, we analyze the tree by calling cconv-analyze-form.
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;; This function finds all mutated variables, all functions that are suitable
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;; for lambda lifting and all variables captured by closure. It passes the tree
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;; once, returning a list of three lists.
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;;
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;; Then we calculate the intersection of the first and third lists returned by
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;; cconv-analyze form to find all mutated variables that are captured by
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;; closure.
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;; Armed with this data, we call cconv-closure-convert-rec, that rewrites the
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;; tree recursively, lifting lambdas where possible, building closures where it
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;; is needed and eliminating mutable variables used in closure.
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;;
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;; We do following replacements :
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;; (lambda (v1 ...) ... fv1 fv2 ...) => (lambda (v1 ... fv1 fv2 ) ... fv1 fv2 .)
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;; if the function is suitable for lambda lifting (if all calls are known)
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;;
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;; (lambda (v0 ...) ... fv0 .. fv1 ...) =>
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;; (internal-make-closure (v0 ...) (fv0 ...) <doc>
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;; ... (internal-get-closed-var 0) ... (internal-get-closed-var 1) ...)
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;;
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;; If the function has no free variables, we don't do anything.
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;;
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;; If a variable is mutated (updated by setq), and it is used in a closure
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;; we wrap its definition with list: (list val) and we also replace
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;; var => (car-safe var) wherever this variable is used, and also
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;; (setq var value) => (setcar var value) where it is updated.
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;;
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;; If defun argument is closure mutable, we letbind it and wrap it's
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;; definition with list.
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;; (defun foo (... mutable-arg ...) ...) =>
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;; (defun foo (... m-arg ...) (let ((m-arg (list m-arg))) ...))
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;;
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;;; Code:
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;; PROBLEM cases found during conversion to lexical binding.
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;; We should try and detect and warn about those cases, even
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;; for lexical-binding==nil to help prepare the migration.
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;; - Uses of run-hooks, and friends.
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;; - Cases where we want to apply the same code to different vars depending on
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;; some test. These sometimes use a (let ((foo (if bar 'a 'b)))
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;; ... (symbol-value foo) ... (set foo ...)).
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;; TODO: (not just for cconv but also for the lexbind changes in general)
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;; - let (e)debug find the value of lexical variables from the stack.
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;; - make eval-region do the eval-sexp-add-defvars dance.
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;; - byte-optimize-form should be applied before cconv.
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;; OTOH, the warnings emitted by cconv-analyze need to come before optimize
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;; since afterwards they can because obnoxious (warnings about an "unused
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;; variable" should not be emitted when the variable use has simply been
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;; optimized away).
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;; - let macros specify that some let-bindings come from the same source,
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;; so the unused warning takes all uses into account.
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;; - let interactive specs return a function to build the args (to stash into
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;; command-history).
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;; - canonize code in macro-expand so we don't have to handle (let (var) body)
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;; and other oddities.
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;; - new byte codes for unwind-protect so that closures aren't needed at all.
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;; - a reference to a var that is known statically to always hold a constant
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;; should be turned into a byte-constant rather than a byte-stack-ref.
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;; Hmm... right, that's called constant propagation and could be done here,
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;; but when that constant is a function, we have to be careful to make sure
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;; the bytecomp only compiles it once.
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;; - Since we know here when a variable is not mutated, we could pass that
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;; info to the byte-compiler, e.g. by using a new `immutable-let'.
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;; - call known non-escaping functions with `goto' rather than `call'.
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;; - optimize mapc to a dolist loop.
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;; (defmacro dlet (binders &rest body)
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;; ;; Works in both lexical and non-lexical mode.
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;; (declare (indent 1) (debug let))
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;; `(progn
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;; ,@(mapcar (lambda (binder)
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;; `(defvar ,(if (consp binder) (car binder) binder)))
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;; binders)
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;; (let ,binders ,@body)))
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;; (defmacro llet (binders &rest body)
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;; ;; Only works in lexical-binding mode.
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;; `(funcall
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;; (lambda ,(mapcar (lambda (binder) (if (consp binder) (car binder) binder))
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;; binders)
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;; ,@body)
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;; ,@(mapcar (lambda (binder) (if (consp binder) (cadr binder)))
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;; binders)))
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(eval-when-compile (require 'cl-lib))
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(defconst cconv-liftwhen 6
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"Try to do lambda lifting if the number of arguments + free variables
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is less than this number.")
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(defvar cconv-var-classification
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;; Alist mapping variables to a given class.
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;; The keys are of the form (BINDER . PARENTFORM) where BINDER
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;; is the (VAR VAL) that introduces it (or is just (VAR) for variables
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;; not introduced by let).
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;; The class can be one of:
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;; - :unused
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;; - :lambda-candidate
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;; - :captured+mutated
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;; - nil for "normal" variables, which would then just not appear
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;; in the alist at all.
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)
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(defvar cconv-freevars-alist
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;; Alist associating to each function body the list of its free variables.
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)
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;;;###autoload
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(defun cconv-closure-convert (form)
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"Main entry point for closure conversion.
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-- FORM is a piece of Elisp code after macroexpansion.
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-- TOPLEVEL(optional) is a boolean variable, true if we are at the root of AST
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Returns a form where all lambdas don't have any free variables."
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;; (message "Entering cconv-closure-convert...")
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(let ((cconv-freevars-alist '())
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(cconv-var-classification '()))
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;; Analyze form - fill these variables with new information.
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(cconv-analyze-form form '())
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(setq cconv-freevars-alist (nreverse cconv-freevars-alist))
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(prog1 (cconv-convert form nil nil) ; Env initially empty.
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(cl-assert (null cconv-freevars-alist)))))
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(defconst cconv--dummy-var (make-symbol "ignored"))
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(defun cconv--set-diff (s1 s2)
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"Return elements of set S1 that are not in set S2."
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(let ((res '()))
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(dolist (x s1)
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(unless (memq x s2) (push x res)))
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(nreverse res)))
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(defun cconv--set-diff-map (s m)
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"Return elements of set S that are not in Dom(M)."
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(let ((res '()))
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(dolist (x s)
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(unless (assq x m) (push x res)))
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(nreverse res)))
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(defun cconv--map-diff (m1 m2)
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"Return the submap of map M1 that has Dom(M2) removed."
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(let ((res '()))
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(dolist (x m1)
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(unless (assq (car x) m2) (push x res)))
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(nreverse res)))
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(defun cconv--map-diff-elem (m x)
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"Return the map M minus any mapping for X."
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;; Here we assume that X appears at most once in M.
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(let* ((b (assq x m))
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(res (if b (remq b m) m)))
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(cl-assert (null (assq x res))) ;; Check the assumption was warranted.
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res))
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(defun cconv--map-diff-set (m s)
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"Return the map M minus any mapping for elements of S."
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;; Here we assume that X appears at most once in M.
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(let ((res '()))
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(dolist (b m)
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(unless (memq (car b) s) (push b res)))
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(nreverse res)))
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(defun cconv--convert-function (args body env parentform &optional docstring)
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(cl-assert (equal body (caar cconv-freevars-alist)))
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(let* ((fvs (cdr (pop cconv-freevars-alist)))
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(body-new '())
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(envector ())
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(i 0)
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(new-env ()))
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;; Build the "formal and actual envs" for the closure-converted function.
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(dolist (fv fvs)
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(let ((exp (or (cdr (assq fv env)) fv)))
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(pcase exp
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;; If `fv' is a variable that's wrapped in a cons-cell,
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;; we want to put the cons-cell itself in the closure,
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;; rather than just a copy of its current content.
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(`(car-safe ,iexp . ,_)
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(push iexp envector)
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(push `(,fv . (car-safe (internal-get-closed-var ,i))) new-env))
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(_
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(push exp envector)
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(push `(,fv . (internal-get-closed-var ,i)) new-env))))
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(setq i (1+ i)))
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(setq envector (nreverse envector))
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(setq new-env (nreverse new-env))
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(setq body-new (cconv--convert-funcbody
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args body new-env parentform))
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(cond
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((not (or envector docstring)) ;If no freevars - do nothing.
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`(function (lambda ,args . ,body-new)))
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(t
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`(internal-make-closure
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,args ,envector ,docstring . ,body-new)))))
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(defun cconv--remap-llv (new-env var closedsym)
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;; In a case such as:
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;; (let* ((fun (lambda (x) (+ x y))) (y 1)) (funcall fun 1))
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;; A naive lambda-lifting would return
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;; (let* ((fun (lambda (y x) (+ x y))) (y 1)) (funcall fun y 1))
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;; Where the external `y' is mistakenly captured by the inner one.
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;; So when we detect that case, we rewrite it to:
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;; (let* ((closed-y y) (fun (lambda (y x) (+ x y))) (y 1))
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;; (funcall fun closed-y 1))
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;; We do that even if there's no `funcall' that uses `fun' in the scope
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;; where `y' is shadowed by another variable because, to treat
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;; this case better, we'd need to traverse the tree one more time to
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;; collect this data, and I think that it's not worth it.
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(mapcar (lambda (mapping)
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(if (not (eq (cadr mapping) 'apply-partially))
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mapping
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(cl-assert (eq (car mapping) (nth 2 mapping)))
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`(,(car mapping)
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apply-partially
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,(car mapping)
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,@(mapcar (lambda (arg)
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(if (eq var arg)
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closedsym arg))
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(nthcdr 3 mapping)))))
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new-env))
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(defun cconv--warn-unused-msg (var varkind)
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(unless (or ;; Uninterned symbols typically come from macro-expansion, so
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;; it is often non-trivial for the programmer to avoid such
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;; unused vars.
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(not (intern-soft var))
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(eq ?_ (aref (symbol-name var) 0))
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;; As a special exception, ignore "ignore".
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(eq var 'ignored))
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(let ((suggestions (help-uni-confusable-suggestions (symbol-name var))))
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(format "Unused lexical %s `%S'%s"
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varkind var
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(if suggestions (concat "\n " suggestions) "")))))
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(define-inline cconv--var-classification (binder form)
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(inline-quote
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(alist-get (cons ,binder ,form) cconv-var-classification
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nil nil #'equal)))
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(defun cconv--convert-funcbody (funargs funcbody env parentform)
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"Run `cconv-convert' on FUNCBODY, the forms of a lambda expression.
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PARENTFORM is the form containing the lambda expression. ENV is a
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lexical environment (same format as for `cconv-convert'), not
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including FUNARGS, the function's argument list. Return a list
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of converted forms."
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(let ((wrappers ()))
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(dolist (arg funargs)
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(pcase (cconv--var-classification (list arg) parentform)
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(:captured+mutated
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(push `(,arg . (car-safe ,arg)) env)
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(push (lambda (body) `(let ((,arg (list ,arg))) ,body)) wrappers))
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((and :unused
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(let (and (pred stringp) msg)
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(cconv--warn-unused-msg arg "argument")))
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(if (assq arg env) (push `(,arg . nil) env)) ;FIXME: Is it needed?
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(push (lambda (body) (macroexp--warn-wrap msg body 'lexical)) wrappers))
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(_
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(if (assq arg env) (push `(,arg . nil) env)))))
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(setq funcbody (mapcar (lambda (form)
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(cconv-convert form env nil))
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funcbody))
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(if wrappers
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(let ((special-forms '()))
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;; Keep special forms at the beginning of the body.
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(while (or (and (cdr funcbody) (stringp (car funcbody))) ;docstring.
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(memq (car-safe (car funcbody))
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'(interactive declare :documentation)))
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(push (pop funcbody) special-forms))
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(let ((body (macroexp-progn funcbody)))
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(dolist (wrapper wrappers) (setq body (funcall wrapper body)))
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`(,@(nreverse special-forms) ,@(macroexp-unprogn body))))
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funcbody)))
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(defun cconv-convert (form env extend)
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;; This function actually rewrites the tree.
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"Return FORM with all its lambdas changed so they are closed.
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ENV is a lexical environment mapping variables to the expression
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used to get its value. This is used for variables that are copied into
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closures, moved into cons cells, ...
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ENV is a list where each entry takes the shape either:
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(VAR . (car-safe EXP)): VAR has been moved into the car of a cons-cell, and EXP
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is an expression that evaluates to this cons-cell.
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(VAR . (internal-get-closed-var N)): VAR has been copied into the closure
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environment's Nth slot.
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(VAR . (apply-partially F ARG1 ARG2 ..)): VAR has been λ-lifted and takes
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additional arguments ARGs.
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(VAR . nil): VAR is accessed normally. This is the same as VAR
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being absent from ENV, but an explicit nil entry is useful
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for shadowing VAR for a specific scope.
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EXTEND is a list of variables which might need to be accessed even from places
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where they are shadowed, because some part of ENV causes them to be used at
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places where they originally did not directly appear."
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(cl-assert (not (delq nil (mapcar (lambda (mapping)
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(if (eq (cadr mapping) 'apply-partially)
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(cconv--set-diff (cdr (cddr mapping))
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extend)))
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env))))
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;; What's the difference between fvrs and envs?
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;; Suppose that we have the code
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;; (lambda (..) fvr (let ((fvr 1)) (+ fvr 1)))
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;; only the first occurrence of fvr should be replaced by
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;; (aref env ...).
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;; So initially envs and fvrs are the same thing, but when we descend to
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;; the 'let, we delete fvr from fvrs. Why we don't delete fvr from envs?
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;; Because in envs the order of variables is important. We use this list
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;; to find the number of a specific variable in the environment vector,
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;; so we never touch it(unless we enter to the other closure).
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;;(if (listp form) (print (car form)) form)
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(pcase form
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(`(,(and letsym (or 'let* 'let)) ,binders . ,body)
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; let and let* special forms
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(let ((binders-new '())
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(new-env env)
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(new-extend extend))
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(dolist (binder binders)
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(let* ((value nil)
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(var (if (not (consp binder))
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(prog1 binder (setq binder (list binder)))
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(when (cddr binder)
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(byte-compile-warn
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"Malformed `%S' binding: %S"
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letsym binder))
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(setq value (cadr binder))
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(car binder))))
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(cond
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;; Ignore bindings without a valid name.
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((not (symbolp var))
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(byte-compile-warn "attempt to let-bind nonvariable `%S'" var))
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((or (booleanp var) (keywordp var))
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(byte-compile-warn "attempt to let-bind constant `%S'" var))
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(t
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(let ((new-val
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(pcase (cconv--var-classification binder form)
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;; Check if var is a candidate for lambda lifting.
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((and :lambda-candidate
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(guard
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(progn
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(cl-assert (and (eq (car value) 'function)
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(eq (car (cadr value)) 'lambda)))
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(cl-assert (equal (cddr (cadr value))
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(caar cconv-freevars-alist)))
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;; Peek at the freevars to decide whether
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;; to λ-lift.
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(let* ((fvs (cdr (car cconv-freevars-alist)))
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(fun (cadr value))
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(funargs (cadr fun))
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(funcvars (append fvs funargs)))
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; lambda lifting condition
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(and fvs (>= cconv-liftwhen
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(length funcvars)))))))
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; Lift.
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(let* ((fvs (cdr (pop cconv-freevars-alist)))
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(fun (cadr value))
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(funargs (cadr fun))
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(funcvars (append fvs funargs))
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(funcbody (cddr fun))
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(funcbody-env ()))
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(push `(,var . (apply-partially ,var . ,fvs)) new-env)
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(dolist (fv fvs)
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(cl-pushnew fv new-extend)
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(if (and (eq 'car-safe (car-safe
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(cdr (assq fv env))))
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(not (memq fv funargs)))
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(push `(,fv . (car-safe ,fv)) funcbody-env)))
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`(function (lambda ,funcvars .
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,(cconv--convert-funcbody
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funargs funcbody funcbody-env value)))))
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;; Check if it needs to be turned into a "ref-cell".
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(:captured+mutated
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;; Declared variable is mutated and captured.
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(push `(,var . (car-safe ,var)) new-env)
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`(list ,(cconv-convert value env extend)))
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;; Check if it needs to be turned into a "ref-cell".
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(:unused
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;; Declared variable is unused.
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(if (assq var new-env)
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(push `(,var) new-env)) ;FIXME:Needed?
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(let ((newval
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`(ignore ,(cconv-convert value env extend)))
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(msg (cconv--warn-unused-msg var "variable")))
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(if (null msg) newval
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|
(macroexp--warn-wrap msg newval 'lexical))))
|
|
|
|
;; Normal default case.
|
|
(_
|
|
(if (assq var new-env) (push `(,var) new-env))
|
|
(cconv-convert value env extend)))))
|
|
|
|
(when (and (eq letsym 'let*) (memq var new-extend))
|
|
;; One of the lambda-lifted vars is shadowed, so add
|
|
;; a reference to the outside binding and arrange to use
|
|
;; that reference.
|
|
(let ((closedsym (make-symbol (format "closed-%s" var))))
|
|
(setq new-env (cconv--remap-llv new-env var closedsym))
|
|
(setq new-extend (cons closedsym (remq var new-extend)))
|
|
(push `(,closedsym ,var) binders-new)))
|
|
|
|
;; We push the element after redefined free variables are
|
|
;; processed. This is important to avoid the bug when free
|
|
;; variable and the function have the same name.
|
|
(push (list var new-val) binders-new)
|
|
|
|
(when (eq letsym 'let*)
|
|
(setq env new-env)
|
|
(setq extend new-extend))))))
|
|
) ; end of dolist over binders
|
|
|
|
(when (not (eq letsym 'let*))
|
|
;; We can't do the cconv--remap-llv at the same place for let and
|
|
;; let* because in the case of `let', the shadowing may occur
|
|
;; before we know that the var will be in `new-extend' (bug#24171).
|
|
(dolist (binder binders-new)
|
|
(when (memq (car-safe binder) new-extend)
|
|
;; One of the lambda-lifted vars is shadowed, so add
|
|
;; a reference to the outside binding and arrange to use
|
|
;; that reference.
|
|
(let* ((var (car-safe binder))
|
|
(closedsym (make-symbol (format "closed-%s" var))))
|
|
(setq new-env (cconv--remap-llv new-env var closedsym))
|
|
(setq new-extend (cons closedsym (remq var new-extend)))
|
|
(push `(,closedsym ,var) binders-new)))))
|
|
|
|
`(,letsym ,(nreverse binders-new)
|
|
. ,(mapcar (lambda (form)
|
|
(cconv-convert
|
|
form new-env new-extend))
|
|
body))))
|
|
;end of let let* forms
|
|
|
|
; first element is lambda expression
|
|
(`(,(and `(lambda . ,_) fun) . ,args)
|
|
;; FIXME: it's silly to create a closure just to call it.
|
|
;; Running byte-optimize-form earlier will resolve this.
|
|
`(funcall
|
|
,(cconv-convert `(function ,fun) env extend)
|
|
,@(mapcar (lambda (form)
|
|
(cconv-convert form env extend))
|
|
args)))
|
|
|
|
(`(cond . ,cond-forms) ; cond special form
|
|
`(cond . ,(mapcar (lambda (branch)
|
|
(mapcar (lambda (form)
|
|
(cconv-convert form env extend))
|
|
branch))
|
|
cond-forms)))
|
|
|
|
(`(function (lambda ,args . ,body) . ,_)
|
|
(let ((docstring (if (eq :documentation (car-safe (car body)))
|
|
(cconv-convert (cadr (pop body)) env extend))))
|
|
(cconv--convert-function args body env form docstring)))
|
|
|
|
(`(internal-make-closure . ,_)
|
|
(byte-compile-report-error
|
|
"Internal error in compiler: cconv called twice?"))
|
|
|
|
(`(quote . ,_) form)
|
|
(`(function . ,_) form)
|
|
|
|
;defconst, defvar
|
|
(`(,(and sym (or 'defconst 'defvar)) ,definedsymbol . ,forms)
|
|
`(,sym ,definedsymbol
|
|
. ,(when (consp forms)
|
|
(cons (cconv-convert (car forms) env extend)
|
|
;; The rest (i.e. docstring, of any) is not evaluated,
|
|
;; and may be an invalid expression (e.g. ($# . 678)).
|
|
(cdr forms)))))
|
|
|
|
; condition-case
|
|
(`(condition-case ,var ,protected-form . ,handlers)
|
|
(let* ((class (and var (cconv--var-classification (list var) form)))
|
|
(newenv
|
|
(cond ((eq class :captured+mutated)
|
|
(cons `(,var . (car-safe ,var)) env))
|
|
((assq var env) (cons `(,var) env))
|
|
(t env)))
|
|
(msg (when (eq class :unused)
|
|
(cconv--warn-unused-msg var "variable")))
|
|
(newprotform (cconv-convert protected-form env extend)))
|
|
`(condition-case ,var
|
|
,(if msg
|
|
(macroexp--warn-wrap msg newprotform 'lexical)
|
|
newprotform)
|
|
,@(mapcar
|
|
(lambda (handler)
|
|
`(,(car handler)
|
|
,@(let ((body
|
|
(mapcar (lambda (form)
|
|
(cconv-convert form newenv extend))
|
|
(cdr handler))))
|
|
(if (not (eq class :captured+mutated))
|
|
body
|
|
`((let ((,var (list ,var))) ,@body))))))
|
|
handlers))))
|
|
|
|
(`(unwind-protect ,form . ,body)
|
|
`(unwind-protect ,(cconv-convert form env extend)
|
|
:fun-body ,(cconv--convert-function () body env form)))
|
|
|
|
(`(setq . ,forms) ; setq special form
|
|
(if (= (logand (length forms) 1) 1)
|
|
;; With an odd number of args, let bytecomp.el handle the error.
|
|
form
|
|
(let ((prognlist ()))
|
|
(while forms
|
|
(let* ((sym (pop forms))
|
|
(sym-new (or (cdr (assq sym env)) sym))
|
|
(value (cconv-convert (pop forms) env extend)))
|
|
(push (pcase sym-new
|
|
((pred symbolp) `(setq ,sym-new ,value))
|
|
(`(car-safe ,iexp) `(setcar ,iexp ,value))
|
|
;; This "should never happen", but for variables which are
|
|
;; mutated+captured+unused, we may end up trying to `setq'
|
|
;; on a closed-over variable, so just drop the setq.
|
|
(_ ;; (byte-compile-report-error
|
|
;; (format "Internal error in cconv of (setq %s ..)"
|
|
;; sym-new))
|
|
value))
|
|
prognlist)))
|
|
(if (cdr prognlist)
|
|
`(progn . ,(nreverse prognlist))
|
|
(car prognlist)))))
|
|
|
|
(`(,(and (or 'funcall 'apply) callsym) ,fun . ,args)
|
|
;; These are not special forms but we treat them separately for the needs
|
|
;; of lambda lifting.
|
|
(let ((mapping (cdr (assq fun env))))
|
|
(pcase mapping
|
|
(`(apply-partially ,_ . ,(and fvs `(,_ . ,_)))
|
|
(cl-assert (eq (cadr mapping) fun))
|
|
`(,callsym ,fun
|
|
,@(mapcar (lambda (fv)
|
|
(let ((exp (or (cdr (assq fv env)) fv)))
|
|
(pcase exp
|
|
(`(car-safe ,iexp . ,_) iexp)
|
|
(_ exp))))
|
|
fvs)
|
|
,@(mapcar (lambda (arg)
|
|
(cconv-convert arg env extend))
|
|
args)))
|
|
(_ `(,callsym ,@(mapcar (lambda (arg)
|
|
(cconv-convert arg env extend))
|
|
(cons fun args)))))))
|
|
|
|
(`(interactive . ,forms)
|
|
`(interactive . ,(mapcar (lambda (form)
|
|
(cconv-convert form nil nil))
|
|
forms)))
|
|
|
|
(`(declare . ,_) form) ;The args don't contain code.
|
|
|
|
(`(,func . ,forms)
|
|
;; First element is function or whatever function-like forms are: or, and,
|
|
;; if, catch, progn, prog1, while, until
|
|
`(,func . ,(mapcar (lambda (form)
|
|
(cconv-convert form env extend))
|
|
forms)))
|
|
|
|
(_ (or (cdr (assq form env)) form))))
|
|
|
|
(defvar byte-compile-lexical-variables)
|
|
|
|
(defun cconv--analyze-use (vardata form varkind)
|
|
"Analyze the use of a variable.
|
|
VARDATA should be (BINDER READ MUTATED CAPTURED CALLED).
|
|
VARKIND is the name of the kind of variable.
|
|
FORM is the parent form that binds this var."
|
|
;; use = `(,binder ,read ,mutated ,captured ,called)
|
|
(pcase vardata
|
|
(`(,_ nil nil nil nil) nil)
|
|
(`((,(and var (guard (eq ?_ (aref (symbol-name var) 0)))) . ,_)
|
|
,_ ,_ ,_ ,_)
|
|
;; FIXME: Convert this warning to use `macroexp--warn-wrap'
|
|
;; so as to give better position information and obey
|
|
;; `byte-compile-warnings'.
|
|
(byte-compile-warn
|
|
"%s `%S' not left unused" varkind var))
|
|
((and (let (or 'let* 'let) (car form))
|
|
`((,var) ;; (or `(,var nil) : Too many false positives: bug#47080
|
|
t nil ,_ ,_))
|
|
;; FIXME: Convert this warning to use `macroexp--warn-wrap'
|
|
;; so as to give better position information and obey
|
|
;; `byte-compile-warnings'.
|
|
(unless (not (intern-soft var))
|
|
(byte-compile-warn "Variable `%S' left uninitialized" var))))
|
|
(pcase vardata
|
|
(`(,binder nil ,_ ,_ nil)
|
|
(push (cons (cons binder form) :unused) cconv-var-classification))
|
|
;; If it's unused, there's no point converting it into a cons-cell, even if
|
|
;; it's captured and mutated.
|
|
(`(,binder ,_ t t ,_)
|
|
(push (cons (cons binder form) :captured+mutated)
|
|
cconv-var-classification))
|
|
(`(,(and binder `(,_ (function (lambda . ,_)))) nil nil nil t)
|
|
(push (cons (cons binder form) :lambda-candidate)
|
|
cconv-var-classification))))
|
|
|
|
(defun cconv--analyze-function (args body env parentform)
|
|
(let* ((newvars nil)
|
|
(freevars (list body))
|
|
;; We analyze the body within a new environment where all uses are
|
|
;; nil, so we can distinguish uses within that function from uses
|
|
;; outside of it.
|
|
(envcopy
|
|
(mapcar (lambda (vdata) (list (car vdata) nil nil nil nil)) env))
|
|
(byte-compile-bound-variables byte-compile-bound-variables)
|
|
(newenv envcopy))
|
|
;; Push it before recursing, so cconv-freevars-alist contains entries in
|
|
;; the order they'll be used by closure-convert-rec.
|
|
(push freevars cconv-freevars-alist)
|
|
(dolist (arg args)
|
|
(cond
|
|
((byte-compile-not-lexical-var-p arg)
|
|
(byte-compile-warn
|
|
"Lexical argument shadows the dynamic variable %S"
|
|
arg))
|
|
((eq ?& (aref (symbol-name arg) 0)) nil) ;Ignore &rest, &optional, ...
|
|
(t (let ((varstruct (list arg nil nil nil nil)))
|
|
(cl-pushnew arg byte-compile-lexical-variables)
|
|
(push (cons (list arg) (cdr varstruct)) newvars)
|
|
(push varstruct newenv)))))
|
|
(dolist (form body) ;Analyze body forms.
|
|
(cconv-analyze-form form newenv))
|
|
;; Summarize resulting data about arguments.
|
|
(dolist (vardata newvars)
|
|
(cconv--analyze-use vardata parentform "argument"))
|
|
;; Transfer uses collected in `envcopy' (via `newenv') back to `env';
|
|
;; and compute free variables.
|
|
(while env
|
|
(cl-assert (and envcopy (eq (caar env) (caar envcopy))))
|
|
(let ((free nil)
|
|
(x (cdr (car env)))
|
|
(y (cdr (car envcopy))))
|
|
(while x
|
|
(when (car y) (setcar x t) (setq free t))
|
|
(setq x (cdr x) y (cdr y)))
|
|
(when free
|
|
(push (caar env) (cdr freevars))
|
|
(setf (nth 3 (car env)) t))
|
|
(setq env (cdr env) envcopy (cdr envcopy))))))
|
|
|
|
(defun cconv-analyze-form (form env)
|
|
"Find mutated variables and variables captured by closure.
|
|
Analyze lambdas if they are suitable for lambda lifting.
|
|
- FORM is a piece of Elisp code after macroexpansion.
|
|
- ENV is an alist mapping each enclosing lexical variable to its info.
|
|
I.e. each element has the form (VAR . (READ MUTATED CAPTURED CALLED)).
|
|
This function does not return anything but instead fills the
|
|
`cconv-var-classification' variable and updates the data stored in ENV."
|
|
(pcase form
|
|
; let special form
|
|
(`(,(and (or 'let* 'let) letsym) ,binders . ,body-forms)
|
|
|
|
(let ((orig-env env)
|
|
(newvars nil)
|
|
(var nil)
|
|
(byte-compile-bound-variables byte-compile-bound-variables)
|
|
(value nil))
|
|
(dolist (binder binders)
|
|
(if (not (consp binder))
|
|
(progn
|
|
(setq var binder) ; treat the form (let (x) ...) well
|
|
(setq binder (list binder))
|
|
(setq value nil))
|
|
(setq var (car binder))
|
|
(setq value (cadr binder))
|
|
|
|
(cconv-analyze-form value (if (eq letsym 'let*) env orig-env)))
|
|
|
|
(unless (byte-compile-not-lexical-var-p var)
|
|
(cl-pushnew var byte-compile-lexical-variables)
|
|
(let ((varstruct (list var nil nil nil nil)))
|
|
(push (cons binder (cdr varstruct)) newvars)
|
|
(push varstruct env))))
|
|
|
|
(dolist (form body-forms) ; Analyze body forms.
|
|
(cconv-analyze-form form env))
|
|
|
|
(dolist (vardata newvars)
|
|
(cconv--analyze-use vardata form "variable"))))
|
|
|
|
(`(function (lambda ,vrs . ,body-forms))
|
|
(when (eq :documentation (car-safe (car body-forms)))
|
|
(cconv-analyze-form (cadr (pop body-forms)) env))
|
|
(cconv--analyze-function vrs body-forms env form))
|
|
|
|
(`(setq . ,forms)
|
|
;; If a local variable (member of env) is modified by setq then
|
|
;; it is a mutated variable.
|
|
(while forms
|
|
(let ((v (assq (car forms) env))) ; v = non nil if visible
|
|
(when v (setf (nth 2 v) t)))
|
|
(cconv-analyze-form (cadr forms) env)
|
|
(setq forms (cddr forms))))
|
|
|
|
(`((lambda . ,_) . ,_) ; First element is lambda expression.
|
|
(byte-compile-warn
|
|
"Use of deprecated ((lambda %s ...) ...) form" (nth 1 (car form)))
|
|
(dolist (exp `((function ,(car form)) . ,(cdr form)))
|
|
(cconv-analyze-form exp env)))
|
|
|
|
(`(cond . ,cond-forms) ; cond special form
|
|
(dolist (forms cond-forms)
|
|
(dolist (form forms) (cconv-analyze-form form env))))
|
|
|
|
;; ((and `(quote ,v . ,_) (guard (assq v env)))
|
|
;; (byte-compile-warn
|
|
;; "Possible confusion variable/symbol for `%S'" v))
|
|
|
|
(`(quote . ,_) nil) ; quote form
|
|
(`(function . ,_) nil) ; same as quote
|
|
|
|
(`(condition-case ,var ,protected-form . ,handlers)
|
|
(cconv-analyze-form protected-form env)
|
|
(when (and var (symbolp var) (byte-compile-not-lexical-var-p var))
|
|
(byte-compile-warn
|
|
"Lexical variable shadows the dynamic variable %S" var))
|
|
(let* ((varstruct (list var nil nil nil nil)))
|
|
(if var (push varstruct env))
|
|
(dolist (handler handlers)
|
|
(dolist (form (cdr handler))
|
|
(cconv-analyze-form form env)))
|
|
(if var (cconv--analyze-use (cons (list var) (cdr varstruct))
|
|
form "variable"))))
|
|
|
|
;; FIXME: The bytecode for unwind-protect forces us to wrap the unwind.
|
|
(`(unwind-protect ,form . ,body)
|
|
(cconv-analyze-form form env)
|
|
(cconv--analyze-function () body env form))
|
|
|
|
(`(defvar ,var) (push var byte-compile-bound-variables))
|
|
(`(,(or 'defconst 'defvar) ,var ,value . ,_)
|
|
(push var byte-compile-bound-variables)
|
|
(cconv-analyze-form value env))
|
|
|
|
(`(,(or 'funcall 'apply) ,fun . ,args)
|
|
;; Here we ignore fun because funcall and apply are the only two
|
|
;; functions where we can pass a candidate for lambda lifting as
|
|
;; argument. So, if we see fun elsewhere, we'll delete it from
|
|
;; lambda candidate list.
|
|
(let ((fdata (and (symbolp fun) (assq fun env))))
|
|
(if fdata
|
|
(setf (nth 4 fdata) t)
|
|
(cconv-analyze-form fun env)))
|
|
(dolist (form args) (cconv-analyze-form form env)))
|
|
|
|
(`(interactive . ,forms)
|
|
;; These appear within the function body but they don't have access
|
|
;; to the function's arguments.
|
|
;; We could extend this to allow interactive specs to refer to
|
|
;; variables in the function's enclosing environment, but it doesn't
|
|
;; seem worth the trouble.
|
|
(dolist (form forms) (cconv-analyze-form form nil)))
|
|
|
|
;; `declare' should now be macro-expanded away (and if they're not, we're
|
|
;; in trouble because they *can* contain code nowadays).
|
|
;; (`(declare . ,_) nil) ;The args don't contain code.
|
|
|
|
(`(,_ . ,body-forms) ; First element is a function or whatever.
|
|
(dolist (form body-forms) (cconv-analyze-form form env)))
|
|
|
|
((pred symbolp)
|
|
(let ((dv (assq form env))) ; dv = declared and visible
|
|
(when dv
|
|
(setf (nth 1 dv) t))))))
|
|
(define-obsolete-function-alias 'cconv-analyse-form #'cconv-analyze-form "25.1")
|
|
|
|
(provide 'cconv)
|
|
;;; cconv.el ends here
|