15.4.83  src/app/makelib/mythryl-compiler-compiler/backend-per-platform.pkg

## backend-per-platform.pkg
## (C) 1999 Lucent Technologies, Bell Laboratories
## Author: Matthias Blume (blume@kurims.kyoto-u.ac.jp)

# Compiled by:
#     src/app/makelib/makelib.sublib




# On-demand loading, caching and invocation
# of platform-specific compilers.
#
#
# In directory
#
#     src/lib/core/mythryl-compiler-compiler
#
# we define compiler-compilers for a number of platforms:
#
#     mythryl-compiler-compiler-for-pwrpc32-macos.lib
#     mythryl-compiler-compiler-for-pwrpc32-posix.lib
#     mythryl-compiler-compiler-for-sparc32-posix.lib
#     mythryl-compiler-compiler-for-intel32-posix.lib
#     mythryl-compiler-compiler-for-intel32-win32.lib
#
# Rather than have all of these in memory at all times
# in the compile servers, we load them one at a time in
# response to specific requests.
#
# Here we invoke a requested backend, first (compiling
# and thus loading) it if necessary.
#
# The net result of this chicanery is that backend compilations
# get invoked by the sequence (essentially) 
#
#     backend_per_platform::invoke    which calls               # backend_per_platform  is from   src/app/makelib/mythryl-compiler-compiler/backend-per-platform.pkg
#     backend_index::invoke           which calls               #
#     mythryl_compiler_compiler_g::make_mythryl_compiler        # mythryl_compiler_compiler_g   is from   src/app/makelib/mythryl-compiler-compiler/mythryl-compiler-compiler-g.pkg


stipulate
    package ss =  string_set;                                                                           # string_set            is from   src/lib/src/string-set.pkg
    package bi =  backend_index;                                                                        # backend_index         is from   src/app/makelib/mythryl-compiler-compiler/backend-index.pkg
herein
    package   backend_per_platform   {
        #     ====================
        stipulate
            # This is a set of strings like
            #     $ROOT/src/lib/core/mythryl-compiler-compiler/mythryl-compiler-compiler-for-intel32-posix.lib
            #
            loaded_platforms =  REF ss::empty;                                                          # Remember which target compilers we already have in memory.
        herein

            fun invoke
                    make                                                                                # This is the standard 'make' entrypoint into src/app/makelib/main/makelib-g.pkg
                    platform                                                                            # 'platform' string is architecture+OS, e.g. "intel32-linux" 
                    backend_request                                                                     # See Backend_Request comments in  src/app/makelib/mythryl-compiler-compiler/backend-index.pkg
                =
                {   platform_specific_backend_makefile
                        =
                        cat ["$ROOT/src/lib/core/mythryl-compiler-compiler/", platform, ".lib"];                        # Eg. intel32-posix -> $ROOT/src/lib/core/mythryl-compiler-compiler/mythryl-compiler-compiler-for-intel32-posix.lib


                    if (not (ss::member (*loaded_platforms, platform_specific_backend_makefile)))
                        #
                        if (make  platform_specific_backend_makefile)
                            #
                            loaded_platforms
                                :=
                                ss::add  (*loaded_platforms,  platform_specific_backend_makefile);
                        else
                            raise exception DIE (
                                 sprintf "dynamic linkage of %s platform-specific backend '%s' failed"
                                    platform
                                    platform_specific_backend_makefile
                            );
                        fi;
                    fi;



                    # The desired platform-specific backend is now
                    # in memory, and as part of the process of loading it,
                    #
                    #   src/app/makelib/mythryl-compiler-compiler/mythryl-compiler-compiler-g.pkg
                    #
                    # will have registered a compile function for it,
                    # which we now invoke:
                    #
                    bi::invoke  platform  backend_request;
                        #
                        # 'platform' string is architecture+OS, e.g. "intel32-linux" 
                        # For 'backend_request' see Backend_Request comments in  src/app/makelib/mythryl-compiler-compiler/backend-index.pkg
                };
        end;
    };
end;