2 * "Optimize" a list of dependencies as spit out by gcc -MD
4 * ===========================================================================
6 * Author Kai Germaschewski
7 * Copyright 2002 by Kai Germaschewski <kai.germaschewski@gmx.de>
9 * This software may be used and distributed according to the terms
10 * of the GNU General Public License, incorporated herein by reference.
15 * gcc produces a very nice and correct list of dependencies which
16 * tells make when to remake a file.
18 * To use this list as-is however has the drawback that virtually
19 * every file in the kernel includes <linux/config.h> which then again
20 * includes <linux/autoconf.h>
22 * If the user re-runs make *config, linux/autoconf.h will be
23 * regenerated. make notices that and will rebuild every file which
24 * includes autoconf.h, i.e. basically all files. This is extremely
25 * annoying if the user just changed CONFIG_HIS_DRIVER from n to m.
27 * So we play the same trick that "mkdep" played before. We replace
28 * the dependency on linux/autoconf.h by a dependency on every config
29 * option which is mentioned in any of the listed prequisites.
31 * To be exact, split-include populates a tree in include/config/,
32 * e.g. include/config/his/driver.h, which contains the #define/#undef
33 * for the CONFIG_HIS_DRIVER option.
35 * So if the user changes his CONFIG_HIS_DRIVER option, only the objects
36 * which depend on "include/linux/config/his/driver.h" will be rebuilt,
37 * so most likely only his driver ;-)
39 * The idea above dates, by the way, back to Michael E Chastain, AFAIK.
41 * So to get dependencies right, there are two issues:
42 * o if any of the files the compiler read changed, we need to rebuild
43 * o if the command line given to the compile the file changed, we
44 * better rebuild as well.
46 * The former is handled by using the -MD output, the later by saving
47 * the command line used to compile the old object and comparing it
48 * to the one we would now use.
50 * Again, also this idea is pretty old and has been discussed on
51 * kbuild-devel a long time ago. I don't have a sensibly working
52 * internet connection right now, so I rather don't mention names
53 * without double checking.
55 * This code here has been based partially based on mkdep.c, which
56 * says the following about its history:
58 * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>.
59 * This is a C version of syncdep.pl by Werner Almesberger.
64 * fixdep <depfile> <target> <cmdline>
66 * and will read the dependency file <depfile>
68 * The transformed dependency snipped is written to stdout.
70 * It first generates a line
72 * cmd_<target> = <cmdline>
74 * and then basically copies the .<target>.d file to stdout, in the
75 * process filtering out the dependency on linux/autoconf.h and adding
76 * dependencies on include/config/my/option.h for every
77 * CONFIG_MY_OPTION encountered in any of the prequisites.
79 * It will also filter out all the dependencies on *.ver. We need
80 * to make sure that the generated version checksum are globally up
81 * to date before even starting the recursive build, so it's too late
82 * at this point anyway.
84 * The algorithm to grep for "CONFIG_..." is bit unusual, but should
85 * be fast ;-) We don't even try to really parse the header files, but
86 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will
87 * be picked up as well. It's not a problem with respect to
88 * correctness, since that can only give too many dependencies, thus
89 * we cannot miss a rebuild. Since people tend to not mention totally
90 * unrelated CONFIG_ options all over the place, it's not an
91 * efficiency problem either.
93 * (Note: it'd be easy to port over the complete mkdep state machine,
94 * but I don't think the added complexity is worth it)
97 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto
98 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not
99 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as
100 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h,
101 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that
102 * those files will have correct dependencies.
105 #include <sys/types.h>
106 #include <sys/stat.h>
107 #include <sys/mman.h>
115 #include <arpa/inet.h>
117 #define INT_CONF ntohl(0x434f4e46)
118 #define INT_ONFI ntohl(0x4f4e4649)
119 #define INT_NFIG ntohl(0x4e464947)
120 #define INT_FIG_ ntohl(0x4649475f)
129 fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
134 * Print out the commandline prefixed with cmd_<target filename> :=
136 void print_cmdline(void)
138 printf("cmd_%s := %s\n\n", target, cmdline);
141 char * str_config = NULL;
146 * Grow the configuration string to a desired length.
147 * Usually the first growth is plenty.
149 void grow_config(int len)
151 while (len_config + len > size_config) {
152 if (size_config == 0)
154 str_config = realloc(str_config, size_config *= 2);
155 if (str_config == NULL)
156 { perror("fixdep:malloc"); exit(1); }
163 * Lookup a value in the configuration string.
165 int is_defined_config(const char * name, int len)
167 const char * pconfig;
168 const char * plast = str_config + len_config - len;
169 for ( pconfig = str_config + 1; pconfig < plast; pconfig++ ) {
170 if (pconfig[ -1] == '\n'
171 && pconfig[len] == '\n'
172 && !memcmp(pconfig, name, len))
179 * Add a new value to the configuration string.
181 void define_config(const char * name, int len)
183 grow_config(len + 1);
185 memcpy(str_config+len_config, name, len);
187 str_config[len_config++] = '\n';
191 * Clear the set of configuration strings.
193 void clear_config(void)
196 define_config("", 0);
200 * Record the use of a CONFIG_* word.
202 void use_config(char *m, int slen)
207 if (is_defined_config(m, slen))
210 define_config(m, slen);
212 memcpy(s, m, slen); s[slen] = 0;
214 for (p = s; p < s + slen; p++) {
218 *p = tolower((int)*p);
220 printf(" $(wildcard include/config/%s.h) \\\n", s);
223 void parse_config_file(char *map, size_t len)
225 int *end = (int *) (map + len);
226 /* start at +1, so that p can never be < map */
227 int *m = (int *) map + 1;
230 for (; m < end; m++) {
231 if (*m == INT_CONF) { p = (char *) m ; goto conf; }
232 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
233 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
234 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }
237 if (p > map + len - 7)
239 if (memcmp(p, "CONFIG_", 7))
241 for (q = p + 7; q < map + len; q++) {
242 if (!(isalnum(*q) || *q == '_'))
248 use_config(p+7, q-p-7);
252 /* test is s ends in sub */
253 int strrcmp(char *s, char *sub)
255 int slen = strlen(s);
256 int sublen = strlen(sub);
261 return memcmp(s + slen - sublen, sub, sublen);
264 void do_config_file(char *filename)
270 fd = open(filename, O_RDONLY);
272 fprintf(stderr, "fixdep: ");
277 if (st.st_size == 0) {
281 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
282 if ((long) map == -1) {
283 perror("fixdep: mmap");
288 parse_config_file(map, st.st_size);
290 munmap(map, st.st_size);
295 void parse_dep_file(void *map, size_t len)
304 fprintf(stderr, "fixdep: parse error\n");
307 memcpy(s, m, p-m); s[p-m] = 0;
308 printf("deps_%s := \\\n", target);
314 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
317 while (p < end && *p != ' ') p++;
319 do p--; while (!isalnum(*p));
322 memcpy(s, m, p-m); s[p-m] = 0;
323 if (strrcmp(s, "include/autoconf.h") &&
324 strrcmp(s, "arch/um/include/uml-config.h") &&
325 strrcmp(s, ".ver")) {
326 printf(" %s \\\n", s);
331 printf("\n%s: $(deps_%s)\n\n", target, target);
332 printf("$(deps_%s):\n", target);
335 void print_deps(void)
341 fd = open(depfile, O_RDONLY);
343 fprintf(stderr, "fixdep: ");
348 if (st.st_size == 0) {
349 fprintf(stderr,"fixdep: %s is empty\n",depfile);
353 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
354 if ((long) map == -1) {
355 perror("fixdep: mmap");
360 parse_dep_file(map, st.st_size);
362 munmap(map, st.st_size);
369 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
371 if (*(int *)test != INT_CONF) {
372 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
378 int main(int argc, char *argv[])