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...

1 files changed, 22 insertions, 17 deletions

diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index 2fa78ee6a..65bae4dac 100644
--- 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);
         }
 }