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 7, 1998:
  10   The interface between toplev.c and the language front ends for opening the
  11   source file has changed:
  12
  13   o init_lex() has been renamed to init_parse (char *filename) where filename
  14     is the name of the source file.
  15   o The code in toplev.c which opened the source file should be moved to
  16     the new init_parse function.
  17   o toplev.c now calls finish_parse() instead of closing the source file
  18     using fclose(). This should now be done in finish_parse, if necessary.
  19
  20 Apr 1, 1998:
  21   Front-ends must now define lang_print_xnode.  It is safe for this
  22   function to do nothing.  See c-lang.c.
  23
  24 Feb 1, 1998:
  25
  26   GCC used to store structure sizes & offsets to elements as bitsize
  27   quantities.  This causes problems because a structure can only be
  28   (target memsize / 8) bytes long (this may effect arrays too).  This
  29   is particularly problematical on machines with small address spaces.
  30
  31   So:
  32
  33     All trees that represent sizes in bits should have a TREE_TYPE of
  34     bitsizetype (rather than sizetype).
  35
  36     Accordingly, when such values are computed / initialized, care has to
  37     be takes to use / compute the proper type.
  38
  39     When a size in bits is converted into a size in bytes, which is expressed
  40     in trees, care should be taken to change the tree's type again to sizetype.
  41
  42     We've updated C, C++, Fortran & Objective-C to work with the new
  43     scheme.  Other languages will need to be updated accordingly.
  44     Contact amylaar@cygnus.com for additional information.
  45
  46 ?? 1997:
  47
  48   In an effort to decrease cache thrashing and useless loads we've changed the
  49   third argument to the DEFTREECODE macro to be a single char.  This will
  50   effect languages that defined their own tree codes (usually in a .def file).
  51
  52   Old way:
  53
  54     DEFTREECODE (CLASS_METHOD_DECL, "class_method_decl", "d", 0)
  55
  56   New way:
  57
  58     DEFTREECODE (CLASS_METHOD_DECL, "class_method_decl", 'd', 0)