bdiff: don't check border condition in loop
This is pretty much a copy of d500ddae7494, just to a different loop.
The condition `p == plast` (`plast == a + len - 1`) was only true on
the final iteration of the loop. So it was wasteful to check for it
on every iteration. We decrease the iteration count by 1 and add an
explicit check for `p == plast` after the loop.
Again, we see modest wins.
From the mozilla-unified repository:
$ perfbdiff -m 3041e4d59df2
! wall 0.035502 comb 0.040000 user 0.040000 sys 0.000000 (best of 100)
! wall 0.030480 comb 0.030000 user 0.030000 sys 0.000000 (best of 100)
$ perfbdiff 0e9928989e9c --alldata --count 100
! wall 4.097394 comb 4.100000 user 4.100000 sys 0.000000 (best of 3)
! wall 3.597798 comb 3.600000 user 3.600000 sys 0.000000 (best of 3)
The 2nd example throws a total of ~3.3GB of data at bdiff. This
change increases the throughput from ~811 MB/s to ~924 MB/s.
;; hg-test-mode.el - Major mode for editing Mercurial tests
;;
;; Copyright 2014 Matt Mackall <mpm@selenic.com>
;; "I have no idea what I'm doing"
;;
;; This software may be used and distributed according to the terms of the
;; GNU General Public License version 2 or any later version.
;;
;; To enable, add something like the following to your .emacs:
;;
;; (if (file-exists-p "~/hg/contrib/hg-test-mode.el")
;; (load "~/hg/contrib/hg-test-mode.el"))
(defvar hg-test-mode-hook nil)
(defvar hg-test-mode-map
(let ((map (make-keymap)))
(define-key map "\C-j" 'newline-and-indent)
map)
"Keymap for hg test major mode")
(add-to-list 'auto-mode-alist '("\\.t\\'" . hg-test-mode))
(defconst hg-test-font-lock-keywords-1
(list
'("^ \\(\\$\\|>>>\\) " 1 font-lock-builtin-face)
'("^ \\(>\\|\\.\\.\\.\\) " 1 font-lock-constant-face)
'("^ \\([[][0-9]+[]]\\)$" 1 font-lock-warning-face)
'("^ \\(.*?\\)\\(\\( [(][-a-z]+[)]\\)*\\)$" 1 font-lock-string-face)
'("\\$?\\(HG\\|TEST\\)\\w+=?" . font-lock-variable-name-face)
'("^ \\(.*?\\)\\(\\( [(][-a-z]+[)]\\)+\\)$" 2 font-lock-type-face)
'("^#.*" . font-lock-preprocessor-face)
'("^\\([^ ].*\\)$" 1 font-lock-comment-face)
)
"Minimal highlighting expressions for hg-test mode")
(defvar hg-test-font-lock-keywords hg-test-font-lock-keywords-1
"Default highlighting expressions for hg-test mode")
(defvar hg-test-mode-syntax-table
(let ((st (make-syntax-table)))
(modify-syntax-entry ?\" "w" st) ;; disable standard quoting
st)
"Syntax table for hg-test mode")
(defun hg-test-mode ()
(interactive)
(kill-all-local-variables)
(use-local-map hg-test-mode-map)
(set-syntax-table hg-test-mode-syntax-table)
(set (make-local-variable 'font-lock-defaults) '(hg-test-font-lock-keywords))
(setq major-mode 'hg-test-mode)
(setq mode-name "hg-test")
(run-hooks 'hg-test-mode-hook))
(provide 'hg-test-mode)