annotate src/alloca.s @ 5366:f00192e1cd49

Examining the result of #'length: `eql', not `=', it's better style & cheaper 2011-03-08 Aidan Kehoe <kehoea@parhasard.net> * buff-menu.el (list-buffers-noselect): * byte-optimize.el (byte-optimize-identity): * byte-optimize.el (byte-optimize-if): * byte-optimize.el (byte-optimize-nth): * byte-optimize.el (byte-optimize-nthcdr): * bytecomp.el (byte-compile-warn-wrong-args): * bytecomp.el (byte-compile-two-args-19->20): * bytecomp.el (byte-compile-list): * bytecomp.el (byte-compile-beginning-of-line): * bytecomp.el (byte-compile-set): * bytecomp.el (byte-compile-set-default): * bytecomp.el (byte-compile-values): * bytecomp.el (byte-compile-values-list): * bytecomp.el (byte-compile-integerp): * bytecomp.el (byte-compile-multiple-value-list-internal): * bytecomp.el (byte-compile-throw): * cl-macs.el (cl-do-arglist): * cl-macs.el (cl-parse-loop-clause): * cl-macs.el (multiple-value-bind): * cl-macs.el (multiple-value-setq): * cl-macs.el (get-setf-method): * cmdloop.el (command-error): * cmdloop.el (y-or-n-p-minibuf): * cmdloop.el (yes-or-no-p-minibuf): * coding.el (unencodable-char-position): * cus-edit.el (custom-face-prompt): * cus-edit.el (custom-buffer-create-internal): * cus-edit.el (widget-face-action): * cus-edit.el (custom-group-value-create): * descr-text.el (describe-char-unicode-data): * dialog-gtk.el (popup-builtin-question-dialog): * dragdrop.el (experimental-dragdrop-drop-log-function): * dragdrop.el (experimental-dragdrop-drop-mime-default): * easymenu.el (easy-menu-add): * easymenu.el (easy-menu-remove): * faces.el (read-face-name): * faces.el (set-face-stipple): * files.el (file-name-non-special): * font.el (font-combine-fonts): * font.el (font-set-face-font): * font.el (font-parse-rgb-components): * font.el (font-rgb-color-p): * font.el (font-color-rgb-components): * gnuserv.el (gnuserv-edit-files): * help.el (key-or-menu-binding): * help.el (function-documentation-1): * help.el (function-documentation): * info.el (info): * isearch-mode.el (isearch-exit): * isearch-mode.el (isearch-edit-string): * isearch-mode.el (isearch-*-char): * isearch-mode.el (isearch-complete1): * ldap.el (ldap-encode-country-string): * ldap.el (ldap-decode-string): * minibuf.el (read-file-name-internal-1): * minibuf.el (read-non-nil-coding-system): * minibuf.el (get-user-response): * mouse.el (drag-window-divider): * mule/ccl.el: * mule/ccl.el (ccl-compile-if): * mule/ccl.el (ccl-compile-break): * mule/ccl.el (ccl-compile-repeat): * mule/ccl.el (ccl-compile-write-repeat): * mule/ccl.el (ccl-compile-call): * mule/ccl.el (ccl-compile-end): * mule/ccl.el (ccl-compile-read-multibyte-character): * mule/ccl.el (ccl-compile-write-multibyte-character): * mule/ccl.el (ccl-compile-translate-character): * mule/ccl.el (ccl-compile-mule-to-unicode): * mule/ccl.el (ccl-compile-unicode-to-mule): * mule/ccl.el (ccl-compile-lookup-integer): * mule/ccl.el (ccl-compile-lookup-character): * mule/ccl.el (ccl-compile-map-multiple): * mule/ccl.el (ccl-compile-map-single): * mule/devan-util.el (devanagari-compose-to-one-glyph): * mule/devan-util.el (devanagari-composition-component): * mule/mule-cmds.el (finish-set-language-environment): * mule/viet-util.el: * mule/viet-util.el (viet-encode-viscii-char): * multicast.el (open-multicast-group): * newcomment.el (comment-quote-nested): * newcomment.el (comment-region): * newcomment.el (comment-dwim): * regexp-opt.el (regexp-opt-group): * replace.el (map-query-replace-regexp): * specifier.el (derive-device-type-from-tag-set): * subr.el (skip-chars-quote): * test-harness.el (test-harness-from-buffer): * test-harness.el (batch-test-emacs): * wid-edit.el (widget-choice-action): * wid-edit.el (widget-symbol-prompt-internal): * wid-edit.el (widget-color-action): * window-xemacs.el (push-window-configuration): * window-xemacs.el (pop-window-configuration): * window.el (quit-window): * x-compose.el (electric-diacritic): It's better style, and cheaper (often one assembler instruction vs. a C funcall in the byte code), to use `eql' instead of `=' when it's clear what numerical type a given result will be. Change much of our code to do this, with the help of a byte-compiler change (not comitted) that looked for calls to #'length (which always returns an integer) in its args.
author Aidan Kehoe <kehoea@parhasard.net>
date Tue, 08 Mar 2011 23:41:52 +0000
parents aa5ed11f473b
children 308d34e9f07d
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1 /* `alloca' standard 4.2 subroutine for 68000's and 16000's and others.
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2 Copyright (C) 1985, 1986, 1988 Free Software Foundation, Inc.
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3
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4 This file is part of XEmacs.
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5
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6 XEmacs is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by the
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8 Free Software Foundation; either version 2, or (at your option) any
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9 later version.
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10
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11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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14 for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with XEmacs; see the file COPYING. If not, write to
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18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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19 Boston, MA 02111-1307, USA. */
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20
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21 /* Synched up with: FSF 19.30. */
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22
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23 /* Both 68000 systems I have run this on have had broken versions of alloca.
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24 Also, I am told that non-berkeley systems do not have it at all.
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25 So replace whatever system-provided alloca there may be
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26 on all 68000 systems. */
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27
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28 #define NOT_C_CODE
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29 #ifdef emacs
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30 #include <config.h>
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31 #else
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32 #include "config.h"
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33 #endif
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34
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35 #ifndef HAVE_ALLOCA /* define this to use system's alloca */
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36
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37 #ifndef m68k
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38 #ifndef m68000
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39 you
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40 lose!!
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41 #endif /* m68000 */
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42 #endif /* m68k */
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43
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44
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45 #ifdef m68k /* SGS assembler totally different */
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46 file "alloca.s"
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47 global alloca
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48 alloca:
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49 mov.l (%sp)+,%a1 # pop return addr from top of stack
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50 mov.l (%sp)+,%d0 # pop size in bytes from top of stack
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51 add.l &R%1,%d0 # round size up to long word
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52 and.l &-4,%d0 # mask out lower two bits of size
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53 sub.l %d0,%sp # allocate by moving stack pointer
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54 tst.b P%1(%sp) # stack probe to allocate pages
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55 mov.l %sp,%a0 # return pointer as pointer
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56 mov.l %sp,%d0 # return pointer as int to avoid disaster
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57 add.l &-4,%sp # new top of stack
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58 jmp (%a1) # not a normal return
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59 set S%1,64 # safety factor for C compiler scratch
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60 set R%1,3+S%1 # add to size for rounding
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61 set P%1,-132 # probe this far below current top of stack
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62
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63 #else /* not m68k */
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64
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65 #ifdef m68000
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66
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67 /* Some systems want the _, some do not. Win with both kinds. */
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68 .globl _alloca
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69 _alloca:
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70 .globl alloca
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71 alloca:
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72 movl sp@+,a0
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73 movl a7,d0
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74 subl sp@,d0
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75 andl #~3,d0
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76 movl d0,sp
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77 tstb sp@(0) /* Make stack pages exist */
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78 /* Needed on certain systems
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79 that lack true demand paging */
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80 addql #4,d0
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81 jmp a0@
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82
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83 #endif /* m68000 */
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84 #endif /* not m68k */
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85
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86 #endif /* not HAVE_ALLOCA */