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 prerequisites.
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/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 prerequisites.
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 * 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 #include <sys/types.h>
106 static void usage(void)
108 fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n");
109 fprintf(stderr, " -e insert extra dependencies given on stdin\n");
114 * Print out a dependency path from a symbol name
116 static void print_config(const char *m, int slen)
120 printf(" $(wildcard include/config/");
121 for (i = 0; i < slen; i++) {
132 static void do_extra_deps(void)
136 while (fgets(buf, sizeof(buf), stdin)) {
137 int len = strlen(buf);
139 if (len < 2 || buf[len - 1] != '\n') {
140 fprintf(stderr, "fixdep: bad data on stdin\n");
143 print_config(buf, len - 1);
155 static struct item *hashtab[HASHSZ];
157 static unsigned int strhash(const char *str, unsigned int sz)
160 unsigned int i, hash = 2166136261U;
162 for (i = 0; i < sz; i++)
163 hash = (hash ^ str[i]) * 0x01000193;
168 * Lookup a value in the configuration string.
170 static int is_defined_config(const char *name, int len, unsigned int hash)
174 for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
175 if (aux->hash == hash && aux->len == len &&
176 memcmp(aux->name, name, len) == 0)
183 * Add a new value to the configuration string.
185 static void define_config(const char *name, int len, unsigned int hash)
187 struct item *aux = malloc(sizeof(*aux) + len);
190 perror("fixdep:malloc");
193 memcpy(aux->name, name, len);
196 aux->next = hashtab[hash % HASHSZ];
197 hashtab[hash % HASHSZ] = aux;
201 * Record the use of a CONFIG_* word.
203 static void use_config(const char *m, int slen)
205 unsigned int hash = strhash(m, slen);
207 if (is_defined_config(m, slen, hash))
210 define_config(m, slen, hash);
211 print_config(m, slen);
214 /* test if s ends in sub */
215 static int str_ends_with(const char *s, int slen, const char *sub)
217 int sublen = strlen(sub);
222 return !memcmp(s + slen - sublen, sub, sublen);
225 static void parse_config_file(const char *p)
228 const char *start = p;
230 while ((p = strstr(p, "CONFIG_"))) {
231 if (p > start && (isalnum(p[-1]) || p[-1] == '_')) {
237 while (*q && (isalnum(*q) || *q == '_'))
239 if (str_ends_with(p, q - p, "_MODULE"))
244 use_config(p, r - p);
249 static void *read_file(const char *filename)
255 fd = open(filename, O_RDONLY);
257 fprintf(stderr, "fixdep: error opening file: ");
261 if (fstat(fd, &st) < 0) {
262 fprintf(stderr, "fixdep: error fstat'ing file: ");
266 buf = malloc(st.st_size + 1);
268 perror("fixdep: malloc");
271 if (read(fd, buf, st.st_size) != st.st_size) {
272 perror("fixdep: read");
275 buf[st.st_size] = '\0';
281 /* Ignore certain dependencies */
282 static int is_ignored_file(const char *s, int len)
284 return str_ends_with(s, len, "include/generated/autoconf.h") ||
285 str_ends_with(s, len, "include/generated/autoksyms.h") ||
286 str_ends_with(s, len, ".ver");
290 * Important: The below generated source_foo.o and deps_foo.o variable
291 * assignments are parsed not only by make, but also by the rather simple
292 * parser in scripts/mod/sumversion.c.
294 static void parse_dep_file(char *m, const char *target, int insert_extra_deps)
297 int is_last, is_target;
298 int saw_any_target = 0;
299 int is_first_dep = 0;
303 /* Skip any "white space" */
304 while (*m == ' ' || *m == '\\' || *m == '\n')
310 /* Find next "white space" */
312 while (*p && *p != ' ' && *p != '\\' && *p != '\n')
314 is_last = (*p == '\0');
315 /* Is the token we found a target name? */
316 is_target = (*(p-1) == ':');
317 /* Don't write any target names into the dependency file */
319 /* The /next/ file is the first dependency */
321 } else if (!is_ignored_file(m, p - m)) {
325 * Do not list the source file as dependency, so that
326 * kbuild is not confused if a .c file is rewritten
327 * into .S or vice versa. Storing it in source_* is
328 * needed for modpost to compute srcversions.
332 * If processing the concatenation of multiple
333 * dependency files, only process the first
334 * target name, which will be the original
335 * source name, and ignore any other target
336 * names, which will be intermediate temporary
339 if (!saw_any_target) {
341 printf("source_%s := %s\n\n",
343 printf("deps_%s := \\\n", target);
347 printf(" %s \\\n", m);
351 parse_config_file(buf);
359 * Start searching for next token immediately after the first
360 * "whitespace" character that follows this token.
365 if (!saw_any_target) {
366 fprintf(stderr, "fixdep: parse error; no targets found\n");
370 if (insert_extra_deps)
373 printf("\n%s: $(deps_%s)\n\n", target, target);
374 printf("$(deps_%s):\n", target);
377 int main(int argc, char *argv[])
379 const char *depfile, *target, *cmdline;
380 int insert_extra_deps = 0;
383 if (argc == 5 && !strcmp(argv[1], "-e")) {
384 insert_extra_deps = 1;
386 } else if (argc != 4)
393 printf("cmd_%s := %s\n\n", target, cmdline);
395 buf = read_file(depfile);
396 parse_dep_file(buf, target, insert_extra_deps);