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 autoconf.h.
21 * If the user re-runs make *config, autoconf.h will be
22 * regenerated. make notices that and will rebuild every file which
23 * includes autoconf.h, i.e. basically all files. This is extremely
24 * annoying if the user just changed CONFIG_HIS_DRIVER from n to m.
26 * So we play the same trick that "mkdep" played before. We replace
27 * the dependency on autoconf.h by a dependency on every config
28 * option which is mentioned in any of the listed prequisites.
30 * kconfig populates a tree in include/config/ with an empty file
31 * for each config symbol and when the configuration is updated
32 * the files representing changed config options are touched
33 * which then let make pick up the changes and the files that use
34 * the config symbols are rebuilt.
36 * So if the user changes his CONFIG_HIS_DRIVER option, only the objects
37 * which depend on "include/linux/config/his/driver.h" will be rebuilt,
38 * so most likely only his driver ;-)
40 * The idea above dates, by the way, back to Michael E Chastain, AFAIK.
42 * So to get dependencies right, there are two issues:
43 * o if any of the files the compiler read changed, we need to rebuild
44 * o if the command line given to the compile the file changed, we
45 * better rebuild as well.
47 * The former is handled by using the -MD output, the later by saving
48 * the command line used to compile the old object and comparing it
49 * to the one we would now use.
51 * Again, also this idea is pretty old and has been discussed on
52 * kbuild-devel a long time ago. I don't have a sensibly working
53 * internet connection right now, so I rather don't mention names
54 * without double checking.
56 * This code here has been based partially based on mkdep.c, which
57 * says the following about its history:
59 * Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>.
60 * This is a C version of syncdep.pl by Werner Almesberger.
65 * fixdep <depfile> <target> <cmdline>
67 * and will read the dependency file <depfile>
69 * The transformed dependency snipped is written to stdout.
71 * It first generates a line
73 * cmd_<target> = <cmdline>
75 * and then basically copies the .<target>.d file to stdout, in the
76 * process filtering out the dependency on autoconf.h and adding
77 * dependencies on include/config/my/option.h for every
78 * CONFIG_MY_OPTION encountered in any of the prequisites.
80 * It will also filter out all the dependencies on *.ver. We need
81 * to make sure that the generated version checksum are globally up
82 * to date before even starting the recursive build, so it's too late
83 * at this point anyway.
85 * The algorithm to grep for "CONFIG_..." is bit unusual, but should
86 * be fast ;-) We don't even try to really parse the header files, but
87 * merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will
88 * be picked up as well. It's not a problem with respect to
89 * correctness, since that can only give too many dependencies, thus
90 * we cannot miss a rebuild. Since people tend to not mention totally
91 * unrelated CONFIG_ options all over the place, it's not an
92 * efficiency problem either.
94 * (Note: it'd be easy to port over the complete mkdep state machine,
95 * but I don't think the added complexity is worth it)
98 * Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto
99 * CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not
100 * fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as
101 * UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h,
102 * through arch/um/include/uml-config.h; this fixdep "bug" makes sure that
103 * those files will have correct dependencies.
106 #include <sys/types.h>
107 #include <sys/stat.h>
108 #include <sys/mman.h>
116 #include <arpa/inet.h>
118 #define INT_CONF ntohl(0x434f4e46)
119 #define INT_ONFI ntohl(0x4f4e4649)
120 #define INT_NFIG ntohl(0x4e464947)
121 #define INT_FIG_ ntohl(0x4649475f)
123 int insert_extra_deps;
128 static void usage(void)
130 fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n");
131 fprintf(stderr, " -e insert extra dependencies given on stdin\n");
136 * Print out the commandline prefixed with cmd_<target filename> :=
138 static void print_cmdline(void)
140 printf("cmd_%s := %s\n\n", target, cmdline);
144 * Print out a dependency path from a symbol name
146 static void print_config(const char *m, int slen)
150 printf(" $(wildcard include/config/");
151 for (i = 0; i < slen; i++) {
162 static void do_extra_deps(void)
164 if (insert_extra_deps) {
166 while(fgets(buf, sizeof(buf), stdin)) {
167 int len = strlen(buf);
168 if (len < 2 || buf[len-1] != '\n') {
169 fprintf(stderr, "fixdep: bad data on stdin\n");
172 print_config(buf, len-1);
185 static struct item *hashtab[HASHSZ];
187 static unsigned int strhash(const char *str, unsigned int sz)
190 unsigned int i, hash = 2166136261U;
192 for (i = 0; i < sz; i++)
193 hash = (hash ^ str[i]) * 0x01000193;
198 * Lookup a value in the configuration string.
200 static int is_defined_config(const char *name, int len, unsigned int hash)
204 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
205 if (aux->hash == hash && aux->len == len &&
206 memcmp(aux->name, name, len) == 0)
213 * Add a new value to the configuration string.
215 static void define_config(const char *name, int len, unsigned int hash)
217 struct item *aux = malloc(sizeof(*aux) + len);
220 perror("fixdep:malloc");
223 memcpy(aux->name, name, len);
226 aux->next = hashtab[hash % HASHSZ];
227 hashtab[hash % HASHSZ] = aux;
231 * Record the use of a CONFIG_* word.
233 static void use_config(const char *m, int slen)
235 unsigned int hash = strhash(m, slen);
237 if (is_defined_config(m, slen, hash))
240 define_config(m, slen, hash);
241 print_config(m, slen);
244 static void parse_config_file(const char *map, size_t len)
246 const int *end = (const int *) (map + len);
247 /* start at +1, so that p can never be < map */
248 const int *m = (const int *) map + 1;
251 for (; m < end; m++) {
252 if (*m == INT_CONF) { p = (char *) m ; goto conf; }
253 if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
254 if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
255 if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }
258 if (p > map + len - 7)
260 if (memcmp(p, "CONFIG_", 7))
263 for (q = p; q < map + len; q++) {
264 if (!(isalnum(*q) || *q == '_'))
270 if (!memcmp(q - 7, "_MODULE", 7))
274 use_config(p, q - p);
278 /* test if s ends in sub */
279 static int strrcmp(const char *s, const char *sub)
281 int slen = strlen(s);
282 int sublen = strlen(sub);
287 return memcmp(s + slen - sublen, sub, sublen);
290 static void do_config_file(const char *filename)
296 fd = open(filename, O_RDONLY);
298 fprintf(stderr, "fixdep: error opening config file: ");
302 if (fstat(fd, &st) < 0) {
303 fprintf(stderr, "fixdep: error fstat'ing config file: ");
307 if (st.st_size == 0) {
311 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
312 if ((long) map == -1) {
313 perror("fixdep: mmap");
318 parse_config_file(map, st.st_size);
320 munmap(map, st.st_size);
326 * Important: The below generated source_foo.o and deps_foo.o variable
327 * assignments are parsed not only by make, but also by the rather simple
328 * parser in scripts/mod/sumversion.c.
330 static void parse_dep_file(void *map, size_t len)
337 int saw_any_target = 0;
338 int is_first_dep = 0;
341 /* Skip any "white space" */
342 while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
344 /* Find next "white space" */
346 while (p < end && *p != ' ' && *p != '\\' && *p != '\n')
348 /* Is the token we found a target name? */
349 is_target = (*(p-1) == ':');
350 /* Don't write any target names into the dependency file */
352 /* The /next/ file is the first dependency */
355 /* Save this token/filename */
359 /* Ignore certain dependencies */
360 if (strrcmp(s, "include/generated/autoconf.h") &&
361 strrcmp(s, "include/generated/autoksyms.h") &&
362 strrcmp(s, "arch/um/include/uml-config.h") &&
363 strrcmp(s, "include/linux/kconfig.h") &&
364 strrcmp(s, ".ver")) {
366 * Do not list the source file as dependency,
367 * so that kbuild is not confused if a .c file
368 * is rewritten into .S or vice versa. Storing
369 * it in source_* is needed for modpost to
370 * compute srcversions.
374 * If processing the concatenation of
375 * multiple dependency files, only
376 * process the first target name, which
377 * will be the original source name,
378 * and ignore any other target names,
379 * which will be intermediate temporary
382 if (!saw_any_target) {
384 printf("source_%s := %s\n\n",
386 printf("deps_%s := \\\n",
391 printf(" %s \\\n", s);
396 * Start searching for next token immediately after the first
397 * "whitespace" character that follows this token.
402 if (!saw_any_target) {
403 fprintf(stderr, "fixdep: parse error; no targets found\n");
409 printf("\n%s: $(deps_%s)\n\n", target, target);
410 printf("$(deps_%s):\n", target);
413 static void print_deps(void)
419 fd = open(depfile, O_RDONLY);
421 fprintf(stderr, "fixdep: error opening depfile: ");
425 if (fstat(fd, &st) < 0) {
426 fprintf(stderr, "fixdep: error fstat'ing depfile: ");
430 if (st.st_size == 0) {
431 fprintf(stderr,"fixdep: %s is empty\n",depfile);
435 map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
436 if ((long) map == -1) {
437 perror("fixdep: mmap");
442 parse_dep_file(map, st.st_size);
444 munmap(map, st.st_size);
449 static void traps(void)
451 static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
452 int *p = (int *)test;
454 if (*p != INT_CONF) {
455 fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianness? %#x\n",
461 int main(int argc, char *argv[])
465 if (argc == 5 && !strcmp(argv[1], "-e")) {
466 insert_extra_deps = 1;
468 } else if (argc != 4)