tcc: Draft suppoprt for -MD/-MF options

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).

v2:

(Taking inputs from grischka and me myself)

- put code to generate deps file into a function.
- used tcc_fileextension() instead of open-coding
- generate deps only when compilation/preprocessing was successful

v3:

- use pstrcpy instead of snprintf(buf, sizeof(buf), "%s", ...)

7 files changed, 84 insertions, 7 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 1c963b5..92c7cad 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -1041,6 +1041,7 @@ LIBTCCAPI void tcc_delete(TCCState *s1)
 
     dynarray_reset(&s1->input_files, &s1->nb_input_files);
     dynarray_reset(&s1->input_libs, &s1->nb_input_libs);
+    dynarray_reset(&s1->target_deps, &s1->nb_target_deps);
 
 #ifdef HAVE_SELINUX
     munmap (s1->write_mem, s1->mem_size);
@@ -1092,6 +1093,10 @@ ST_FUNC int tcc_add_file_internal(TCCState *s1, const char *filename, int flags)
         goto the_end;
     }
 
+    /* update target deps */
+    dynarray_add((void ***)&s1->target_deps, &s1->nb_target_deps,
+            tcc_strdup(filename));
+
     if (flags & AFF_PREPROCESS) {
         ret = tcc_preprocess(s1);
         goto the_end;
@@ -1585,3 +1590,37 @@ LIBTCCAPI const char *tcc_default_target(TCCState *s)
 
     return outfile_default;
 }
+
+
+LIBTCCAPI void tcc_gen_makedeps(TCCState *s, const char *target, const char *filename)
+{
+    FILE *depout;
+    char buf[1024], *ext;
+    int i;
+
+    if (!target)
+        target = tcc_default_target(s);
+
+    if (!filename) {
+        /* compute filename automatically
+         * dir/file.o -> dir/file.d             */
+        pstrcpy(buf, sizeof(buf), target);
+        ext = tcc_fileextension(buf);
+        pstrcpy(ext, sizeof(buf) - (ext-buf), ".d");
+        filename = buf;
+    }
+
+    if (s->verbose)
+        printf("<- %s\n", filename);
+
+    /* XXX return err codes instead of error() ? */
+    depout = fopen(filename, "w");
+    if (!depout)
+        error("could not open '%s'", filename);
+
+    fprintf(depout, "%s : \\\n", target);
+    for (i=0; i<s->nb_target_deps; ++i)
+        fprintf(depout, "\t%s \\\n", s->target_deps[i]);
+    fprintf(depout, "\n");
+    fclose(depout);
+}
diff --git a/libtcc.h b/libtcc.h
index 13efcd2..bf328d3 100644
--- a/libtcc.h
+++ b/libtcc.h
@@ -110,6 +110,13 @@ LIBTCCAPI void tcc_set_lib_path(TCCState *s, const char *path);
 /* Get default target filename for this compilation */
 LIBTCCAPI const char *tcc_default_target(TCCState *s);
 
+/* Generate make dependencies for target and store them into file
+ *
+ * !target    - use default target name
+ * !filename  - use (target.o -> target.d)
+ */
+LIBTCCAPI void tcc_gen_makedeps(TCCState *s, const char *target, const char *filename);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/tcc.c b/tcc.c
index 705f5e2..b9478d9 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:
@@ -479,14 +494,20 @@ int main(int argc, char **argv)
         if (do_bench)
             tcc_print_stats(s, getclock_us() - start_time);
 
-        if (s->output_type == TCC_OUTPUT_PREPROCESS) {
-            if (outfile)
-                fclose(s->outfile);
-        } else if (s->output_type == TCC_OUTPUT_MEMORY)
+        if (s->output_type == TCC_OUTPUT_MEMORY)
             ret = tcc_run(s, argc - optind, argv + optind);
         else {
-            ret = tcc_output_file(s, outfile ? outfile : tcc_default_target(s));
-            ret = ret ? 1 : 0;
+            if (s->output_type == TCC_OUTPUT_PREPROCESS) {
+                if (outfile)
+                    fclose(s->outfile);
+            } else {
+                ret = tcc_output_file(s, outfile ? outfile : tcc_default_target(s));
+                ret = ret ? 1 : 0;
+            }
+
+            /* dump collected dependencies */
+            if (gen_deps && !ret)
+                tcc_gen_makedeps(s, outfile, deps_outfile);
         }
     }
 
diff --git a/tcc.h b/tcc.h
index 8fd4408..bb3eb9f 100644
--- a/tcc.h
+++ b/tcc.h
@@ -525,6 +525,10 @@ struct TCCState {
     char **input_libs;
     int nb_input_libs;
 
+    /* automatically collected dependencies for this compilation */
+    char **target_deps;
+    int nb_target_deps;
+
     /* for tcc_relocate */
     int runtime_added;
     void *runtime_mem;
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 */