• Paul Eggert's avatar
    Simplify stack-allocated Lisp objects, and make them more portable. · dc452569
    Paul Eggert authored
    The build_local_string macro was used in two ways: (1) string
    literals for which scoped allocation suffices, and (2) file name
    components, where it's not safe in general to assume bounded-size
    ASCII data.  Simplify by defining a new macro SCOPED_STRING that
    allocates a block-scope string, and by using SCOPED_STRING for (1)
    and build_string for (2).  Furthermore, actually use stack
    allocation only for objects known to have sufficient alignment.
    This simpler implementation means Emacs can make
    USE_STACK_LISP_OBJECTS the default unless GC_MARK_STACK !=
    GC_MAKE_GCPROS_NOOPS.
    * lisp.h (GCALIGNED): Align even if !USE_STACK_LISP_OBJECTS,
    for fewer differences among implementations.
    (struct Lisp_String): Now GCALIGNED.
    (USE_STACK_LISP_OBJECTS): Default to true, since the
    implementation no longer insists on a nonempty GCALIGNED.
    But make it false if GC_MARK_STACK != GC_MAKE_GCPROS_NOOPS.
    (SCOPED_CONS_INITIALIZER): Remove, since it's no longer needed
    separately.  Move definiens to scoped_cons.  The old definition
    was incorrect when GCALIGNED was defined to be empty.
    (union Aligned_String): New type.
    (USE_STACK_CONS, USE_STACK_STRING): New constants, so that the
    implementation ports to compilers that don't align strictly enough.
    Don't worry about the union sizes; it's not worth bothering about.
    (scoped_cons, scoped_list1, scoped_list3, scoped_list4):
    Rewrite using USE_STACK_CONS.
    (scoped_cons): Assume the use of union Aligned_Cons.
    (lisp_string_size, make_local_string, build_local_string): Remove.
    Unless otherwise specified, all callers of build_local_string
    changed to use SCOPED_STRING.
    (SCOPED_STRING): New macro.
    * data.c (wrong_choice):
    * menu.c (single_menu_item):
    * process.c (Fformat_network_address):
    Hoist use of SCOPED_STRING out of a scope, so that its returned
    object lives long enough.
    * fileio.c (Fexpand_file_name): Use build_string, not SCOPED_STRING,
    as the string might be long or might not be ASCII.
    dc452569
process.c 213 KB