[Tinycc-devel] [PATCH 6/7] tcc: Draft suppoprt for -MD/-MF options

[Kirill Smelkov]

In build systems, this is used to automatically collect target
dependencies, e.g.

    ---- 8< (hello.c) ----
    #include "hello.h"
    #include <stdio.h>

    int main()
    {
        printf("Hello World!\n");
        return 0;
    }

$ tcc -MD -c hello.c    # -> hello.o, hello.d
$ cat hello.d
hello.o : \
        hello.c \
        hello.h \
        /usr/include/stdio.h \
        /usr/include/features.h \
        /usr/include/bits/predefs.h \
        /usr/include/sys/cdefs.h \
        /usr/include/bits/wordsize.h \
        /usr/include/gnu/stubs.h \
        /usr/include/bits/wordsize.h \
        /usr/include/gnu/stubs-32.h \
        /home/kirr/local/tcc/lib/tcc/include/stddef.h \
        /usr/include/bits/types.h \
        /usr/include/bits/wordsize.h \
        /usr/include/bits/typesizes.h \
        /usr/include/libio.h \
        /usr/include/_G_config.h \
        /usr/include/wchar.h \
        /home/kirr/local/tcc/lib/tcc/include/stdarg.h \
        /usr/include/bits/stdio_lim.h \
        /usr/include/bits/sys_errlist.h \

NOTE: gcc supports -MD only for .c -> .o, but in tcc, we generate
dependencies for whatever action is being taken. E.g. for .c -> exe, the
result will be:

$ tcc -MD -o hello hello.c  # -> hello, hello.d
hello: \
        /usr/lib/crt1.o \
        /usr/lib/crti.o \
        hello.c \
        hello.h \
        /usr/include/stdio.h \
        /usr/include/features.h \
        /usr/include/bits/predefs.h \
        /usr/include/sys/cdefs.h \
        /usr/include/bits/wordsize.h \
        /usr/include/gnu/stubs.h \
        /usr/include/bits/wordsize.h \
        /usr/include/gnu/stubs-32.h \
        /home/kirr/local/tcc/lib/tcc/include/stddef.h \
        /usr/include/bits/types.h \
        /usr/include/bits/wordsize.h \
        /usr/include/bits/typesizes.h \
        /usr/include/libio.h \
        /usr/include/_G_config.h \
        /usr/include/wchar.h \
        /home/kirr/local/tcc/lib/tcc/include/stdarg.h \
        /usr/include/bits/stdio_lim.h \
        /usr/include/bits/sys_errlist.h \
        /usr/lib/libc.so \
        /lib/libc.so.6 \
        /usr/lib/ld-linux.so.2 \
        /lib/ld-linux.so.2 \
        /usr/lib/libc_nonshared.a \
        /lib/libc.so.6 \
        /usr/lib/libc_nonshared.a \
        /home/kirr/local/tcc/lib/tcc/libtcc1.a \
        /usr/lib/crtn.o \

So tcc dependency generator is a bit more clever than one used in gcc :)

Also, I've updated TODO and Changelog (in not-yet-released section).
---
 Changelog |    4 ++++
 TODO      |    1 -
 libtcc.c  |    6 ++++++
 tcc.c     |   41 +++++++++++++++++++++++++++++++++++++++++
 tcc.h     |    3 +++
 tccpp.c   |    3 +++
 6 files changed, 57 insertions(+), 1 deletions(-)

diff --git a/Changelog b/Changelog
index b271054..528d927 100644
--- a/Changelog
+++ b/Changelog
@@ -1,3 +1,7 @@
+not released:
+
+- Add support for -MD/-MF (automatically generate dependencies for make)
+
 version 0.9.25:
 
 - first support for x86-64 target (Shinichiro Hamaji)
diff --git a/TODO b/TODO
index 6f49c5d..9d19153 100644
--- a/TODO
+++ b/TODO
@@ -46,7 +46,6 @@ Missing features:
 - disable-asm and disable-bcheck options
 - __builtin_expect()
 - improve '-E' option.
-- add '-MD' option
 - atexit (Nigel Horne)
 - packed attribute
 - C99: add variable size arrays (gcc 3.2 testsuite issue)
diff --git a/libtcc.c b/libtcc.c
index f0da4de..e2b4036 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -1038,6 +1038,8 @@ LIBTCCAPI void tcc_delete(TCCState *s1)
     dynarray_reset(&s1->sysinclude_paths, &s1->nb_sysinclude_paths);
 
     tcc_free(s1->tcc_lib_path);
+    dynarray_reset(&s1->target_deps, &s1->nb_target_deps);
+
 #ifdef HAVE_SELINUX
     munmap (s1->write_mem, s1->mem_size);
     munmap (s1->runtime_mem, s1->mem_size);    
@@ -1074,6 +1076,10 @@ ST_FUNC int tcc_add_file_internal(TCCState *s1, const 
char *filename, int flags)
 
     ret = -1;
 
+    /* update target deps */
+    dynarray_add((void ***)&s1->target_deps, &s1->nb_target_deps,
+            tcc_strdup(filename));
+
     /* find source file type with extension */
     ext = tcc_fileextension(filename);
     if (ext[0])
diff --git a/tcc.c b/tcc.c
index 5138937..a4b610d 100644
--- a/tcc.c
+++ b/tcc.c
@@ -32,6 +32,8 @@ static int output_type;
 static int reloc_output;
 static const char *outfile;
 static int do_bench = 0;
+static int gen_deps;
+static const char *deps_outfile;
 
 #define TCC_OPTION_HAS_ARG 0x0001
 #define TCC_OPTION_NOSEP   0x0002 /* cannot have space before option and arg */
@@ -74,6 +76,9 @@ static void help(void)
 #ifdef CONFIG_TCC_BACKTRACE
            "  -bt N       show N callers in stack traces\n"
 #endif
+           "Misc options:\n"
+           "  -MD         generate target dependencies for make\n"
+           "  -MF depfile put generated dependencies here\n"
            );
 }
 
@@ -115,6 +120,8 @@ enum {
     TCC_OPTION_w,
     TCC_OPTION_pipe,
     TCC_OPTION_E,
+    TCC_OPTION_MD,
+    TCC_OPTION_MF,
     TCC_OPTION_x,
 };
 
@@ -154,6 +161,8 @@ static const TCCOption tcc_options[] = {
     { "w", TCC_OPTION_w, 0 },
     { "pipe", TCC_OPTION_pipe, 0},
     { "E", TCC_OPTION_E, 0},
+    { "MD", TCC_OPTION_MD, 0},
+    { "MF", TCC_OPTION_MF, TCC_OPTION_HAS_ARG },
     { "x", TCC_OPTION_x, TCC_OPTION_HAS_ARG },
     { NULL },
 };
@@ -374,6 +383,12 @@ static int parse_args(TCCState *s, int argc, char **argv)
             case TCC_OPTION_E:
                 output_type = TCC_OUTPUT_PREPROCESS;
                 break;
+            case TCC_OPTION_MD:
+                gen_deps = 1;
+                break;
+            case TCC_OPTION_MF:
+                deps_outfile = optarg;
+                break;
             case TCC_OPTION_x:
                 break;
             default:
@@ -509,6 +524,32 @@ int main(int argc, char **argv)
             ret = tcc_run(s, argc - optind, argv + optind);
         else
             ret = tcc_output_file(s, outfile) ? 1 : 0;
+
+        /* dump collected dependencies */
+        if (gen_deps) {
+            FILE *depout;
+            char buf[1024], *ext;
+
+            if (!deps_outfile) {
+                /* compute deps_outfile automatically
+                 * dir/file.o -> dir/file.d             */
+                snprintf(buf, sizeof(buf), "%s", outfile ? outfile : 
outfile_default);
+                ext = strrchr(buf, '.');
+                ext = ext ? ext : strchr(buf, 0);
+                snprintf(ext, sizeof(buf) - (ext-buf), ".d");
+                deps_outfile = buf;
+            }
+
+            depout = fopen(deps_outfile, "w");
+            if (!depout)
+                error("could not open '%s'", deps_outfile);
+
+            fprintf(depout, "%s : \\\n", (outfile ? outfile : 
outfile_default));
+            for (i=0; i<s->nb_target_deps; ++i)
+                fprintf(depout, "\t%s \\\n", s->target_deps[i]);
+            fprintf(depout, "\n");
+            fclose(depout);
+        }
     }
 
     tcc_delete(s);
diff --git a/tcc.h b/tcc.h
index 29953a6..52f8825 100644
--- a/tcc.h
+++ b/tcc.h
@@ -517,6 +517,9 @@ struct TCCState {
 
     /* output file for preprocessing */
     FILE *outfile;
+    /* automatically collected dependencies for this compilation */
+    char **target_deps;
+    int nb_target_deps;
 
     /* for tcc_relocate */
     int runtime_added;
diff --git a/tccpp.c b/tccpp.c
index 9a4cbca..2b735d1 100644
--- a/tccpp.c
+++ b/tccpp.c
@@ -1491,6 +1491,9 @@ ST_FUNC void preprocess(int is_bof)
 #ifdef INC_DEBUG
             printf("%s: including %s\n", file->filename, buf1);
 #endif
+            /* update target deps */
+            dynarray_add((void ***)&s1->target_deps, &s1->nb_target_deps,
+                    tcc_strdup(buf1));
 
            /* XXX: fix current line init */
            /* push current file in stack */
-- 
1.7.1.334.gebb7bc.dirty