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fixdep: avoid parsing the same file over again

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The dep files (*.d files) emitted by C compilers usually contain the
deduplicated list of included files.

One exceptional case is when a header is included by the -include
command line option, and also by #include directive.

For example, the top Makefile adds the command line option,
"-include $(srctree)/include/linux/kconfig.h". You do not need to
include <linux/kconfig.h> in every source file.

In fact, include/linux/kconfig.h is listed twice in many .*.cmd files
due to include/linux/xarray.h having "#include <linux/kconfig.h>".
I did not fix that since it is a small redundancy.

However, this is more annoying for rustc. rustc emits the dependency
for each emission type.

For example, cmd_rustc_library emits dep-info, obj, and metadata.
So, the emitted *.d file contains the dependency for those 3 targets,
which makes fixdep parse the same file 3 times.

  $ grep rust/alloc/raw_vec.rs rust/.alloc.o.cmd
    rust/alloc/raw_vec.rs \
    rust/alloc/raw_vec.rs \
    rust/alloc/raw_vec.rs \

To skip the second parsing, this commit adds a hash table for parsed
files, just like we did for CONFIG options.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Tested-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
This commit is contained in:
Masahiro Yamada 2023-01-07 18:18:19 +09:00
parent 871d657385
commit faa91c472b
1 changed files with 7 additions and 2 deletions
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9
scripts/basic/fixdep.c
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@ -113,7 +113,7 @@ struct item {
};
#define HASHSZ 256
static struct item *config_hashtab[HASHSZ];
static struct item *config_hashtab[HASHSZ], *file_hashtab[HASHSZ];
static unsigned int strhash(const char *str, unsigned int sz)
{
@ -365,6 +365,10 @@ static void parse_dep_file(char *p, const char *target)
* name, which will be the original one, and ignore any
* other source names, which will be intermediate
* temporary files.
*
* rustc emits the same dependency list for each
* emission type. It is enough to list the source name
* just once.
*/
if (!saw_any_target) {
saw_any_target = true;
@ -372,7 +376,8 @@ static void parse_dep_file(char *p, const char *target)
printf("deps_%s := \\\n", target);
need_parse = true;
}
} else if (!is_ignored_file(p, q - p)) {
} else if (!is_ignored_file(p, q - p) &&
!in_hashtable(p, q - p, file_hashtab)) {
printf(" %s \\\n", p);
need_parse = true;
}