From: Paul Eggert Date: Fri, 12 Jul 2019 06:06:22 +0000 (-0700) Subject: Tweak builtin symbol order for speed X-Git-Tag: emacs-27.0.90~1994 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=81a1088ee8b833cd30a3363782195d6c4d575672;p=emacs.git Tweak builtin symbol order for speed * lib-src/make-docfile.c (compare_globals): Make symbols 1 through 4 be t, unbound, error, lambda. This is in addition to symbol 0 being nil. This change improved ‘make compile-always’ performance by 0.6% on my platform. --- diff --git a/lib-src/make-docfile.c b/lib-src/make-docfile.c index 4d25b0a6b93..368150be067 100644 --- a/lib-src/make-docfile.c +++ b/lib-src/make-docfile.c @@ -641,13 +641,24 @@ compare_globals (const void *a, const void *b) return ga->type - gb->type; /* Consider "nil" to be the least, so that iQnil is zero. That - way, Qnil's internal representation is zero, which is a bit faster. */ + way, Qnil's internal representation is zero, which is a bit faster. + Similarly, consideer "t" to be the second-least, and so forth. */ if (ga->type == SYMBOL) { - bool a_nil = strcmp (ga->name, "Qnil") == 0; - bool b_nil = strcmp (gb->name, "Qnil") == 0; - if (a_nil | b_nil) - return b_nil - a_nil; + /* Common symbols in decreasing popularity order. */ + static char const commonsym[][8] + = { "nil", "t", "unbound", "error", "lambda" }; + int ncommonsym = sizeof commonsym / sizeof *commonsym; + int ai = ncommonsym, bi = ncommonsym; + for (int i = 0; i < ncommonsym; i++) + { + if (ga->name[0] == 'Q' && strcmp (ga->name + 1, commonsym[i]) == 0) + ai = i; + if (gb->name[0] == 'Q' && strcmp (gb->name + 1, commonsym[i]) == 0) + bi = i; + } + if (! (ai == ncommonsym && bi == ncommonsym)) + return ai - bi; } return strcmp (ga->name, gb->name);