• apt's avatar
    [project @ 2001-08-17 17:18:51 by apt] · 1dfaee31
    apt authored
    How I spent my summer vacation.
    
    Primops
    -------
    
    The format of the primops.txt.pp file has been enhanced to allow
    (latex-style) primop descriptions to be included.  There is a new flag
    to genprimopcode that generates documentation including these
    descriptions. A first cut at descriptions of the more interesting
    primops has been made, and the file has been reordered a bit.
    
    31-bit words
    ------------
    
    The front end now can cope with the possibility of 31-bit (or even 30-bit)
    Int# and Word# types.  The only current use of this is to generate
    external .core files that can be translated into OCAML source files
    (OCAML uses a one-bit tag to distinguish integers from pointers).
    The only way to get this right now is by hand-defining the preprocessor
    symbol WORD_SIZE_IN_BITS, which is normally set automatically from
    the familiar WORD_SIZE_IN_BYTES.
    
    Just in case 31-bit words are used, we now have Int32# and Word32# primitive types
    and an associated family of operators, paralleling the existing 64-bit
    stuff.  Of course, none of the operators actually need to be implemented
    in the absence of a 31-bit backend.
    There has also been some minor re-jigging of the 32 vs. 64 bit stuff.
    See the description at the top of primops.txt.pp file for more details.
    Note that, for the first time, the *type* of a primop can now depend
    on the target word size.
    
    Also, the family of primops intToInt8#, intToInt16#, etc.
    have been renamed narrow8Int#, narrow16Int#, etc., to emphasize
    that they work on Int#'s and don't actually convert between types.
    
    Addresses
    ---------
    
    As another part of coping with the possibility of 31-bit ints,
    the addr2Int# and int2Addr# primops are now thoroughly deprecated
    (and not even defined in the 31-bit case) and all uses
    of them have been removed except from the (deprecated) module
    hslibs/lang/Addr
    
    Addr# should now be treated as a proper abstract type, and has these suitable operators:
    
    nullAddr# : Int# -> Addr# (ignores its argument; nullary primops cause problems at various places)
    plusAddr# :  Addr# -> Int# -> Addr#
    minusAddr : Addr# -> Addr# -> Int#
    remAddr# : Addr# -> Int# -> Int#
    
    Obviously, these don't allow completely arbitrary offsets if 31-bit ints are
    in use, but they should do for all practical purposes.
    
    It is also still possible to generate an address constant, and there is a built-in rule
    that makes use of this to remove the nullAddr# calls.
    
    Misc
    ----
    There is a new compile flag -fno-code that causes GHC to quit after generating .hi files
    and .core files (if requested) but before generating STG.
    
    Z-encoded names for tuples have been rationalized; e.g.,
    Z3H now means an unboxed 3-tuple, rather than an unboxed
    tuple with 3 commas (i.e., a 4-tuple)!
    
    Removed misc. litlits in hslibs/lang
    
    Misc. small changes to external core format.  The external core description
    has also been substantially updated, and incorporates the automatically-generated
    primop documentation; its in the repository at /papers/ext-core/core.tex.
    
    A little make-system addition to allow passing CPP options to compiler and
    library builds.
    1dfaee31
MkExternalCore.lhs 7.74 KB