[distcc] gcc bootstraps with distcc

[Neil Booth]

Alexandre Oliva wrote:-

> Here's a patch for GCC that I've just tested, that was enough to get
> GCC to bootstrap using distcc, using distccrel (attached) as per the
> instructions in it.
> 
> It seems like the other problem I had before, of getting different
> line numbers depending on whether separate or integrated preprocessing
> is done is no longer present.  Wheee!

Um.  Odd.  I hope we never revisit this then 8-)

> source and build trees.  The reasons -Mpwd is not enabled by default
> are backward compatibility (the <directory> directive might be
> unexpected, even though it's in a format that is entirely
> backward-compatible), efficiency and to enable ccache caches to be
> shared by multiple build trees.

Ignoring the other two, is this last reason a good reason still for
it not to be default?

> Index: gcc/c-lex.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/c-lex.c,v
> retrieving revision 1.206
> diff -u -p -r1.206 c-lex.c
> --- gcc/c-lex.c 30 Jun 2003 19:36:20 -0000 1.206
> +++ gcc/c-lex.c 2 Jul 2003 04:13:03 -0000
> @@ -242,6 +242,14 @@ fe_file_change (const struct line_map *n
>  
>        (*debug_hooks->end_source_file) (to_line);
>      }
> +  else if (new_map->reason == LC_RENAME)
> +    {
> +      if (strncmp (new_map->to_file, "<directory>",
> +		   strlen ("<directory>")) == 0)
> +	set_src_pwd (new_map->to_file + strlen ("<directory>"));
> +      if (input_filename == main_input_filename)
> +	main_input_filename = new_map->to_file;
> +    }
>  
>    update_header_times (new_map->to_file);
>    in_system_header = new_map->sysp != 0;

I don't like this.  If we're going to do this directory thing, and I
don't see why not if it's useful, we should provide a separate
callback and not overload this one (which is hairy enough as-is).

> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/cppinit.c,v
> retrieving revision 1.284
> diff -u -p -r1.284 cppinit.c
> --- gcc/cppinit.c 17 Jun 2003 06:17:42 -0000 1.284
> +++ gcc/cppinit.c 2 Jul 2003 04:13:05 -0000
> @@ -29,7 +29,8 @@ Foundation, 59 Temple Place - Suite 330,
>  
>  static void init_library (void);
>  static void mark_named_operators (cpp_reader *);
> -static void read_original_filename (cpp_reader *);
> +static bool read_original_filename (cpp_reader *);
> +static bool read_original_directory (cpp_reader *);
>  static void post_options (cpp_reader *);
>  
>  /* If we have designated initializers (GCC >2.7) these tables can be
> @@ -428,6 +429,8 @@ cpp_add_dependency_target (cpp_reader *p
>  const char *
>  cpp_read_main_file (cpp_reader *pfile, const char *fname)
>  {
> +  char *pwd;
> +
>    sanity_checks (pfile);
>  
>    post_options (pfile);
> @@ -457,8 +460,24 @@ cpp_read_main_file (cpp_reader *pfile, c
>  
>    /* For foo.i, read the original filename foo.c now, for the benefit
>       of the front ends.  */
> -  if (CPP_OPTION (pfile, preprocessed))
> -    read_original_filename (pfile);
> +  if (CPP_OPTION (pfile, preprocessed)
> +      && read_original_filename (pfile))
> +    pwd = NULL;
> +  else if (CPP_OPTION (pfile, current_directory))
> +    pwd = getpwd ();
> +  else
> +    pwd = NULL;
> +
> +  if (pwd)
> +    {
> +      char *dir = concat ("<directory>", pwd, NULL);
> +      const char *name = pfile->map->to_file;
> +      unsigned int line = pfile->line;
> +      int sysp = pfile->map->sysp;
> +      
> +      _cpp_do_file_change (pfile, LC_RENAME, dir, 1, 0);
> +      _cpp_do_file_change (pfile, LC_RENAME, name, line, sysp);
> +    }

My above suggestion would thankfully lose most of this, no?

> +/* For preprocessed files, if the tokens following the first filename
> +   line are of the form # NUM "<directory>...", handle the directive
> +   so we know the original current directory.  This will generate
> +   file_change callbacks, which the front ends must handle
> +   appropriately given their state of initialization.  */
> +static bool
> +read_original_directory (cpp_reader *pfile)
> +{
> +  const cpp_token *token, *token1, *token2;
> +
> +  /* Lex ahead; if the first tokens are of the form # NUM, then
> +     process the directive, otherwise back up.  */
> +  token = _cpp_lex_direct (pfile);
> +  if (token->type == CPP_HASH)
> +    {
> +      token1 = _cpp_lex_direct (pfile);
> +
> +      /* If it's a #line directive, handle it.  */
> +      if (token1->type == CPP_NUMBER)
> +	{
> +	  token2 = _cpp_lex_direct (pfile);
> +	  _cpp_backup_tokens (pfile, 2);
> +
> +	  if (token2->type == CPP_STRING
> +	      && strncmp ((const char *)token2->val.str.text, "<directory>",
> +			  strlen ("<directory>")) == 0)
> +	    {
> +	      const char *name = pfile->map->to_file;
> +	      unsigned int line = pfile->line;
> +	      int sysp = pfile->map->sysp;
> +
> +	      _cpp_handle_directive (pfile, token->flags & PREV_WHITE);
> +
> +	      _cpp_do_file_change (pfile, LC_RENAME, name, line, sysp);
> +	      return true;
> +	    }
>  	}
> +      else
> +	_cpp_backup_tokens (pfile, 1);
>      }
>  
>    /* Backup as if nothing happened.  */
>    _cpp_backup_tokens (pfile, 1);
> +
> +  return false;
>  }

Can you give me some time to think about where this information is
stored?  I'm not sure if I prefer something like this, or perhaps
somehow storing it in the first #line.  I'd also be interested in
Zack's thoughts (cc-ed in case he missed this post; I almost did).

Neil.