Re: [distcc] gcc bootstraps with distcc

[Neil Booth <neil at daikokuya dot co dot uk>]

Alexandre Oliva wrote:-

> After some further discussion on IRC, I ended up having to go with a
> different format to implement the directory line markers.  Here's the
> implementation.  Ok to install?

It's worth noting that there was never a consensus on what to do.
I dislike this approach as 1) it's ugly, and 2) it gives us a wart
we can't lose, so I probably won't approve the patch.  You know
what I like, but dismissed it as "unacceptable".

That said, there are things I'd like improved if we go down this
route.

> +  if (CPP_OPTION (pfile, current_directory))
> +    {
> +      const char *name = pfile->map->to_file;
> +      const char *dir = getpwd ();
> +      char *dir_with_slashes = alloca (strlen (dir) + 3);
> +
> +      memcpy (dir_with_slashes, dir, strlen (dir));
> +      memcpy (dir_with_slashes + strlen (dir), "//", 3);
> +
> +      if (pfile->cb.dir_change)
> +	pfile->cb.dir_change (pfile, dir);
> +      /* Emit file renames that will be recognized by
> +	 read_directory_filename, since dir_change doesn't output
> +	 anything.  */
> +      _cpp_do_file_change (pfile, LC_RENAME, dir_with_slashes, 1, 0);
> +      _cpp_do_file_change (pfile, LC_RENAME, name, 1, 0);
> +    }

Is the second rename necessary?  I don't see why it should be;
if not let's not do it.

> +read_original_directory (cpp_reader *pfile)
> +{
> +  const cpp_token *hash, *token;
> +
> +  /* Lex ahead; if the first tokens are of the form # NUM, then
> +     process the directive, otherwise back up.  */
> +  hash = _cpp_lex_direct (pfile);
> +  if (hash->type != CPP_HASH)
> +    {
> +      _cpp_backup_tokens (pfile, 1);
> +      return;
> +    }
> +
> +  token = _cpp_lex_direct (pfile);
> +
> +  if (token->type != CPP_NUMBER)
> +    {
> +      _cpp_backup_tokens (pfile, 2);
> +      return;
> +    }
> +
> +  token = _cpp_lex_direct (pfile);
> +
> +  if (token->type != CPP_STRING
> +      || ! (token->val.str.len >= 5
> +	    && token->val.str.text[token->val.str.len-2] == '/'
> +	    && token->val.str.text[token->val.str.len-3] == '/'))
> +    {
> +      _cpp_backup_tokens (pfile, 3);
> +      return;
> +    }
> +
> +  if (pfile->cb.dir_change)
> +    {
> +      char *debugdir = alloca (token->val.str.len - 3);
> +
> +      memcpy (debugdir, (const char *) token->val.str.text + 1,
> +	      token->val.str.len - 4);
> +      debugdir[token->val.str.len - 4] = '\0';
> +
> +      if (! pfile->cb.dir_change (pfile, debugdir))
> +	cpp_error (pfile, DL_ERROR,
> +		   "too late to set debug directory");
> +    }      
> +
> +  /* We want to process the fake line changes as regular changes, to
> +     get them output.  */
> +  _cpp_backup_tokens (pfile, 3);
> +
> +  CPP_OPTION (pfile, current_directory) = 0;
>  }

This is really horrible.  cb.dir_change should return void, things about
"too late" are no concern of cpplib.

>    void (*line_change) (cpp_reader *, const cpp_token *, int);
>    void (*file_change) (cpp_reader *, const struct line_map *);
> +  bool (*dir_change) (cpp_reader *, const char *);
>    void (*include) (cpp_reader *, unsigned int, const unsigned char *,
>  		   const char *, int);
>    void (*define) (cpp_reader *, unsigned int, cpp_hashnode *);

See above.

> @@ -743,7 +743,7 @@ static const char *cpp_unique_options =
>   %{!Q:-quiet} %{nostdinc*} %{C} %{CC} %{v} %{I*} %{P} %I\
>   %{MD:-MD %{!o:%b.d}%{o*:%.d%*}}\
>   %{MMD:-MMD %{!o:%b.d}%{o*:%.d%*}}\
> - %{M} %{MM} %{MF*} %{MG} %{MP} %{MQ*} %{MT*}\
> + %{M} %{MM} %{MF*} %{MG} %{MP} %{Mpwd} %{MQ*} %{MT*}\
>   %{!E:%{!M:%{!MM:%{MD|MMD:%{o*:-MQ %*}}}}}\
>   %{trigraphs} %{remap} %{g3:-dD} %{H} %C %{D*&U*&A*} %{i*} %Z %i\
>   %{E|M|MM:%W{o*}}";

Is there a good reason for this?  If not, let's go with -fpwd as
default and -fno-pwd.

Neil.