gcc/LANGUAGES

   1 Right now there is no documentation for the GCC tree -> rtl interfaces
   2 (or more generally the interfaces for adding new languages).
   3
   4 Such documentation would be of great benefit to the project.  Until such
   5 time as we can formally start documenting the interface this file will
   6 serve as a repository for information on these interface and any incompatable
   7 changes we've made.
   8
   9 Apr 21, 1998:
  10   Front ends which link with c-common or other files from the C/C++
  11   front-ends may need to handle TI types.  Look for references to
  12   [unsigned]int_DI_type_node in your front end.  If you have references
  13   to these variables, you'll need up update the front end.
  14
  15   To update the front end you must mirror all the code which currently
  16   deals with intDI_type_node to also handle intTI_type_node.
  17
  18
  19 Apr 7, 1998:
  20   The interface between toplev.c and the language front ends for opening the
  21   source file has changed:
  22
  23   o init_lex() has been renamed to init_parse (char *filename) where filename
  24     is the name of the source file.
  25   o The code in toplev.c which opened the source file should be moved to
  26     the new init_parse function.
  27   o toplev.c now calls finish_parse() instead of closing the source file
  28     using fclose(). This should now be done in finish_parse, if necessary.
  29
  30 Apr 1, 1998:
  31   Front-ends must now define lang_print_xnode.  It is safe for this
  32   function to do nothing.  See c-lang.c.
  33
  34 Feb 1, 1998:
  35
  36   GCC used to store structure sizes & offsets to elements as bitsize
  37   quantities.  This causes problems because a structure can only be
  38   (target memsize / 8) bytes long (this may effect arrays too).  This
  39   is particularly problematical on machines with small address spaces.
  40
  41   So:
  42
  43     All trees that represent sizes in bits should have a TREE_TYPE of
  44     bitsizetype (rather than sizetype).
  45
  46     Accordingly, when such values are computed / initialized, care has to
  47     be takes to use / compute the proper type.
  48
  49     When a size in bits is converted into a size in bytes, which is expressed
  50     in trees, care should be taken to change the tree's type again to sizetype.
  51
  52     We've updated C, C++, Fortran & Objective-C to work with the new
  53     scheme.  Other languages will need to be updated accordingly.
  54     Contact amylaar@cygnus.com for additional information.
  55
  56 ?? 1997:
  57
  58   In an effort to decrease cache thrashing and useless loads we've changed the
  59   third argument to the DEFTREECODE macro to be a single char.  This will
  60   effect languages that defined their own tree codes (usually in a .def file).
  61
  62   Old way:
  63
  64     DEFTREECODE (CLASS_METHOD_DECL, "class_method_decl", "d", 0)
  65
  66   New way:
  67
  68     DEFTREECODE (CLASS_METHOD_DECL, "class_method_decl", 'd', 0)