saw commit of vapier@busybox.net (thanks!),

decided to stop doing FOUR memcmp's per each input character.
I should have fixed this much earlier...

diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index 2fa78ee6aab9d235c7419bc32cbba5331463c2b0..65bae4dac46bf7f5448240e01df2f7c889175c45 100644 (file)
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -225,31 +225,36 @@ void use_config(char *m, int slen)
 void parse_config_file(char *map, size_t len)
 {
        /* modified for bbox */
-       char *end = map + len;
+       char *end_4 = map + len - 4; /* 4 == length of "USE_" */
+       char *end_7 = map + len - 7;
        char *p = map;
        char *q;
        int off;
 
-       for (; p < end; p++) {
-               if (p<end-7 && !memcmp(p, "CONFIG_", 7)) goto conf7;
-               if (p<end-7 && !memcmp(p, "ENABLE_", 7)) goto conf7;
-               if (p<end-4 && !memcmp(p, "USE_", 4)) goto conf4;
-               if (p<end-5 && !memcmp(p, "SKIP_", 5)) goto conf5;
+       for (; p < end_4; p++) {
+               if (p < end_7 && p[6] == '_') {
+                       if (!memcmp(p, "CONFIG", 6)) goto conf7;
+                       if (!memcmp(p, "ENABLE", 6)) goto conf7;
+               }
+               /* We have at least 5 chars: for() has
+                * "p < end-4", not "p <= end-4"
+                * therefore we don't need to check p <= end-5 here */
+               if (p[4] == '_') {
+                       if (!memcmp(p, "SKIP", 4)) goto conf5;
+               }
+               /* Ehhh, gcc is too stupid to just compare it as 32bit int */
+               if (!memcmp(p, "USE_", 4)) goto conf4;
                continue;
-       conf4:  off = 4; goto conf;
-       conf5:  off = 5; goto conf;
+
+       conf4:  off = 4;
+       conf5:  off = 5;
        conf7:  off = 7;
-       conf:
-               if (p > map + len - off)
-                       continue;
-               for (q = p + off; q < map + len; q++) {
+               p += off;
+               for (q = p; q < end_4+4; q++) {
                        if (!(isalnum(*q) || *q == '_'))
-                               goto found;
+                               break;
                }
-               continue;
-
-       found:
-               use_config(p+off, q-p-off);
+               use_config(p, q-p);
        }
 }