* libguile/eval.c: So, ladies & gents, a new evaluator. It's similar to
the old one, in that we memoize and then evaluate, but in this
incarnation, memoization of an expression happens before evaluation,
not lazily as the expression is evaluated. This makes the evaluation
itself much cleaner, in addition to being threadsafe. In addition,
since this C evaluator will in the future just serve to bootstrap the
Scheme evaluator, we don't have to pay much concern for debugging
conveniences. So the environment is just a list of values, and the
memoizer pre-computes where it's going to find each individual value
in the environment.
Interface changes are commented below, with eval.h.
(scm_evaluator_traps): No need to reset the debug mode after rnning te
traps thing. But really, the whole traps system needs some love.
* libguile/memoize.h:
* libguile/memoize.c: New memoizer, which runs before evaluation,
checking all syntax before evaluation begins. Significantly, no
debugging information is left for lexical variables, which is not so
great for interactive debugging; perhaps we should change this to have
a var list in the future as per the classic interpreters. But it's
quite fast, and the resulting code is quite good. Also note that it
doesn't produce ilocs, memoized code is a smob whose type is in the
first word of the smob itself.
* libguile/eval.h (scm_sym_and, scm_sym_begin, scm_sym_case)
(scm_sym_cond, scm_sym_define, scm_sym_do, scm_sym_if, scm_sym_lambda)
(scm_sym_let, scm_sym_letstar, scm_sym_letrec, scm_sym_quote)
(scm_sym_quasiquote, scm_sym_unquote, scm_sym_uq_splicing, scm_sym_at)
(scm_sym_atat, scm_sym_atapply, scm_sym_atcall_cc)
(scm_sym_at_call_with_values, scm_sym_delay, scm_sym_eval_when)
(scm_sym_arrow, scm_sym_else, scm_sym_apply, scm_sym_set_x)
(scm_sym_args): Remove public declaration of these symbols.
(scm_ilookup, scm_lookupcar, scm_eval_car, scm_eval_body)
(scm_eval_args, scm_i_eval_x, scm_i_eval): Remove public declaration
of these functions.
(scm_ceval, scm_deval, scm_ceval_ptr): Remove declarations of these
deprecated functions.
(scm_i_print_iloc, scm_i_print_isym, scm_i_unmemocopy_expr)
(scm_i_unmemocopy_body): Remove declarations of these internal
functions.
(scm_primitive_eval_x, scm_eval_x): Redefine as macros for their less
destructive siblings.
* libguile/Makefile.am: Add memoize.[ch] to the build.
* libguile/debug.h (scm_debug_mode_p, scm_check_entry_p)
(scm_check_apply_p, scm_check_exit_p, scm_check_memoize_p)
(scm_debug_eframe_size): Remove these vars that were tied to the old
evaluator's execution model.
(SCM_RESET_DEBUG_MODE): Remove, no more need for this.
(SCM_MEMOIZEDP, SCM_MEMOIZED_EXP, SCM_MEMOIZED_ENV): Remove macros
referring to old memoized code representation.
(scm_local_eval, scm_procedure_environment, scm_memoized_environment)
(scm_make_memoized, scm_memoized_p): Remove functions operating on old
memoized code representation.
(scm_memcons, scm_mem_to_proc, scm_proc_to_mem): Remove debug-only
code for old evaluator.
* libguile/debug.c: Remove code to correspond with debug.h removals.
(scm_debug_options): No need to set the debug mode or frame limit
here, as we don't have C stack limits any more. Perhaps this is a bug,
but as long as we can compile eval.scm, we should be fine.
* libguile/init.c (scm_i_init_guile): Init memoize.c.
* libguile/modules.c (scm_top_level_env, scm_env_top_level)
(scm_env_module, scm_system_module_env_p): Remove these functions.
* libguile/print.c (iprin1): No more need to handle isyms. Adapt to new
form of interpreted procedures.
* libguile/procprop.c (scm_i_procedure_arity): Adapt to new form of
interpreted procedures.
* libguile/procs.c (scm_thunk_p): Adapt to new form of interpreted
procedures.
* libguile/procs.h (SCM_CLOSURE_FORMALS): Removed, this exists no more.
(SCM_CLOSURE_NUM_REQUIRED_ARGS, SCM_CLOSURE_HAS_REST_ARGS): New
accessors.
* libguile/srcprop.c (scm_source_properties, scm_source_property)
(scm_set_source_property_x): Remove special cases for memoized code.
* libguile/stacks.c (read_frame): Remove a source-property case for
interpreted code.
(NEXT_FRAME): Remove a case that I don't fully understand, that seems
to be designed to skip over apply frames. Will be obsolete in the
futures.
(read_frames): Default source value for interpreted frames to #f.
(narrow_stack): Don't pay attention to the system_module thing.
* libguile/tags.h: Remove isyms and ilocs. Whee!
* libguile/validate.h (SCM_VALIDATE_MEMOIZED): Fix to use the new
MEMOIZED_P formulation.
* module/ice-9/psyntax-pp.scm (do, quasiquote, case): Adapt for these no
longer being primitive macros.
* module/ice-9/boot-9.scm: Whitespace change, but just a poke to force a
rebuild due to and/or/cond/... not being primitives any more.
* module/ice-9/deprecated.scm (unmemoize-expr): Deprecate, it's
unmemoize-expression now.
* test-suite/tests/eval.test ("define set procedure-name"): XFAIL a
couple of tests here; I don't know what to do about them. I reckon the
expander should ensure that defined values are named.
* test-suite/tests/chars.test ("basic char handling"): Fix expected
exception when trying to apply a char.
I tried to split this one, and I know it's a bit disruptive, but this
stuff really is one big cobweb. So instead we'll pretend like these are
separate commits, by separating the changelog.
Applicable struct runtime support.
* libguile/debug.c (scm_procedure_source):
* libguile/eval.c (scm_trampoline_0, scm_trampoline_1)
(scm_trampoline_2):
* libguile/eval.i.c (CEVAL):
* libguile/goops.c (scm_class_of):
* libguile/procprop.c (scm_i_procedure_arity):
* libguile/procs.c (scm_procedure_p, scm_procedure, scm_setter): Allow
for applicable structs. Whee!
* libguile/deprecated.h (scm_vtable_index_vtable): Define as a synonym
for scm_vtable_index_self.
(scm_vtable_index_printer): Alias scm_vtable_index_instance_printer.
(scm_struct_i_free): Alias scm_vtable_index_instance_finalize.
(scm_struct_i_flags): Alias scm_vtable_index_flags.
(SCM_STRUCTF_FLAGS): Be a -1 mask, we have a whole word now.
(SCM_SET_VTABLE_DESTRUCTOR): Implement by hand.
Hidden slots.
* libguile/struct.c (scm_make_struct_layout): Add support for "hidden"
fields, writable fields that are not visible to make-struct. This
allows us to add fields to vtables and not break existing make-struct
invocations.
(scm_struct_ref, scm_struct_set_x): Always get struct length from the
vtable. Support hidden fields.
* libguile/goops.c (scm_class_hidden, scm_class_protected_hidden): New
slot classes, to correspond to the new vtable slots.
(scm_sys_prep_layout_x): Turn hidden slots into 'h'.
(build_class_class_slots): Reorder the class slots to account for
vtable fields coming out of negative-land, for name as a vtable slot,
and for hidden fields.
(create_standard_classes): Define <hidden-slot> and
<protected-hidden-slot>.
Clean up struct.h.
* libguile/struct.h: Lay things out cleaner. There are no more hidden
(negative) words. Names are nicer. The exposition is nicer. But the
basics are the same. The incompatibilities are that <vtable> has more
slots now, and that scm_alloc_struct's signature has changed. The
former is ameliorated by the "hidden" slots mentioned before, and the
latter, well, it was always a very internal thing...
(scm_t_struct_finalize): New type, a finalizer function to be run when
instances of a vtable are collected.
(scm_t_struct_free): Removed, structs' data is managed by the GC now,
and not freed by vtable functions.
* libguile/struct.c: (scm_vtable_p): Now we keep flags on
vtable-vtables, so this check is cheaper.
(scm_alloc_struct): No hidden words. Yippee.
(struct_finalizer_trampoline): Entersify.
(scm_make_struct): No need to babysit extra words, though now we have
to babysit flags. Propagate the vtable, applicable, and setter flags
appropriately.
(scm_make_vtable_vtable): Update for new simplicity.
(scm_print_struct): A better printer.
(scm_init_struct): Define <applicable-struct-vtable>, a magical vtable
like CL's funcallable-standard-class. Also define
<applicable-struct-with-setter-vtable>.
Remove foreign object implementation.
* libguile/goops.h:
* libguile/goops.c (scm_make_foreign_object, scm_make_class)
(scm_add_slot, scm_wrap_object, scm_wrap_component): Remove, these
were undocumented and unworking.
Clean up goops.h, a little.
* libguile/goops.h:
* libguile/goops.c: Also clean up.
* module/oop/goops/dispatch.scm (hashset-index): Adapt for new hashset
index.
Entities were meant to be a form of applicable struct. Unfortunately,
the implementation is intertwingled with generics. Removing them, for
now, will make it possible to cleanly re-add applicable struct support.
* libguile/struct.h (SCM_STRUCTF_ENTITY): Remove.
(SCM_STRUCTF_GOOPS_HACK): New flag; sigh.
* libguile/struct.c (scm_make_struct): We make "entity" structs if the
GOOPS_HACK flag is set. This will be fixed when we rework flags and
remove hidden words.
* libguile/goops.c (scm_class_of): Structs are not applicable, for now
at least.
(scm_sys_inherit_magic_x, scm_basic_basic_make_class)
(scm_sys_allocate_instance, scm_sys_set_object_setter_x):
(make_struct_class): Adapt for no more entities (and thus no entity
flag).
(create_standard_classes): For some reason, generic functions were
getting the LIGHT flag set, after the ENTITY flag was removed; so for
now explicitly clear that flag.
* libguile/goops.h (SCM_GENERIC_SETTER, SCM_SET_GENERIC_SETTER): New
macros.
* libguile/objects.h:
* libguile/objects.c: Remove code for entities.
* libguile/debug.c: (scm_procedure_source): Only work with generics.
* libguile/eval.c (scm_trampoline_0, scm_trampoline_1)
(scm_trampoline_2): Only handle generics.
* libguile/eval.i.c (CEVAL): #ifdef out the pieces about entities.
* libguile/procprop.c (scm_i_procedure_arity): Remove support for
entities.
* libguile/procs.c (scm_procedure_p, scm_procedure, scm_setter): Remove
entity support.
* libguile/objcodes.h (struct scm_objcode): Remove nargs, nrest, and
nlocs, as they are no longer needed. Also obviates the need for a
padding word.
* libguile/procs.c (scm_thunk_p): Use scm_i_program_arity for programs.
* libguile/procprop.c (scm_i_procedure_arity): Use scm_i_program_arity
for programs.
(scm_procedure_properties, scm_set_procedure_properties_x)
(scm_procedure_property, scm_set_procedure_property_x): Rework so that
non-closure properties are stored directly in a weak hash, instead of
needing a weak hash of "stand-in" closures to hold the properties. Fix
docstrings also.
* libguile/root.h (scm_stand_in_procs): Remove from the scm_sys_protects
set. Actually with libGC, we should be able to store the elements of
scm_sys_protects directly as global variables.
* libguile/gc.c (scm_init_storage): Remove scm_stand_in_procs
initialization.
* libguile/programs.c (scm_i_program_arity): New private accessor, tries
to determine the "minimum arity" of a program.
* libguile/vm.c (really_make_boot_program): Adapt to changes in
struct scm_objcode.
* module/language/assembly.scm (*program-header-len*, byte-length):
* module/language/assembly/compile-bytecode.scm (write-bytecode):
* module/language/assembly/decompile-bytecode.scm (decode-load-program):
* module/language/assembly/disassemble.scm (disassemble-load-program):
Adapt to changes in objcode.
* module/system/xref.scm (program-callee-rev-vars): Adapt to changes in
assembly.
* module/language/glil.scm: Remove nargs, nrest, and nlocs from
glil-program.
* module/language/glil/compile-assembly.scm (make-meta, glil->assembly):
* module/language/glil/decompile-assembly.scm (decompile-toplevel):
(decompile-load-program): Adapt to changes in GLIL and assembly.
* module/language/tree-il/compile-glil.scm (flatten-lambda): Adapt to
changes in GLIL.
* test-suite/tests/asm-to-bytecode.test: Adapt to assembly and bytecode
changes.
* test-suite/tests/tree-il.test: Adapt to GLIL changes.
* libguile/tags.h (scm_tc7_program):
* libguile/programs.h: Programs now have their own tc7 code. Fix up the
macros appropriately.
* libguile/programs.c: Remove smobby bits, leaving marking, printing,
and application for other parts of Guile.
* libguile/debug.c (scm_procedure_source):
* libguile/eval.c (scm_trampoline_0, scm_trampoline_1)
(scm_trampoline_2): Add cases for tc7_program.
* libguile/eval.i.c (CEVAL, SCM_APPLY):
* libguile/evalext.c (scm_self_evaluating_p):
* libguile/gc-card.c (scm_i_sweep_card, scm_i_tag_name):
* libguile/gc-mark.c (1):
* libguile/print.c (iprin1):
* libguile/procs.c (scm_procedure_p, scm_thunk_p)
* libguile/vm-i-system.c (make-closure): Adapt to new procedure
representation.
* libguile/procprop.c (scm_i_procedure_arity): Do the right thing for
programs.
* test-suite/tests/procprop.test ("procedure-arity"): Arity test now
succeeds.
* libguile/goops.c (scm_class_of): Programs now belong to the class
<procedure>, not a smob class.
* libguile/vm.h (struct vm, struct vm_cont):
* libguile/vm-engine.c (vm_engine):
* libguile/frames.h (SCM_FRAME_BYTE_CAST, struct vm_frame):
* libguile/frames.c (scm_c_make_vm_frame): Fix usages of scm_byte_t,
changing them to scm_t_uint8.
* libguile/procs.c (scm_c_make_subr): Fix a really tricky bug!!! If
scm_double_cell caused GC, the symbolic name wouldn't be marked. But
the symptom wouldn't appear until you accessed that symbol much later,
for example during tab completion / apropos grovelling. Not sure why we
didn't see this earlier.
The idea is to introduce `gsubrs' whose arity is encoded in their type
(more precisely in the sizeof (void *) - 8 MSBs). This removes the
indirection introduced by cclos and simplifies the code.
* libguile/__scm.h (CCLO): Remove.
* libguile/debug.c (scm_procedure_source, scm_procedure_environment):
Remove references to `scm_tc7_cclo'.
* libguile/eval.c (scm_trampoline_0, scm_trampoline_1,
scm_trampoline_2): Replace `scm_tc7_cclo' with `scm_tc7_gsubr'.
* libguile/eval.i.c (CEVAL): Likewise. No longer make PROC the first
argument. Directly invoke `scm_gsubr_apply ()' instead of jump to the
`evap(N+1)' label or call to `SCM_APPLY ()'.
* libguile/evalext.c (scm_self_evaluating_p): Remove reference to
`scm_tc7_cclo'.
* libguile/gc-card.c (scm_i_sweep_card, scm_i_tag_name): Likewise.
* libguile/gc-mark.c (scm_gc_mark_dependencies): Likewise.
* libguile/goops.c (scm_class_of): Likewise.
* libguile/print.c (iprin1): Likewise.
* libguile/gsubr.c (create_gsubr): Use `unsigned int's for REQ, OPT and
RST. Use `scm_tc7_gsubr' instead of `scm_makcclo ()' in the default
case.
(scm_gsubr_apply): Remove calls to `SCM_GSUBR_PROC ()'.
(scm_f_gsubr_apply): Remove.
* libguile/gsubr.h (SCM_GSUBR_TYPE): New definition.
(SCM_GSUBR_MAX): Changed to 33.
(SCM_SET_GSUBR_TYPE, SCM_GSUBR_PROC, SCM_SET_GSUBR_PROC,
scm_f_gsubr_apply): Remove.
* libguile/procprop.c (scm_i_procedure_arity): Remove reference to
`scm_tc7_cclo'; add proper handling of `scm_tc7_gsubr'.
* libguile/procs.c (scm_makcclo, scm_make_cclo): Remove.
(scm_procedure_p): Remove reference to `scm_tc7_cclo'.
(scm_thunk_p): Likewise, plus add proper `scm_tc7_gsubr' handling.
* libguile/procs.h (SCM_CCLO_LENGTH, SCM_MAKE_CCLO_TAG,
SCM_SET_CCLO_LENGTH, SCM_CCLO_BASE, SCM_SET_CCLO_BASE, SCM_CCLO_REF,
SCM_CCLO_SET, SCM_CCLO_SUBR, SCM_SET_CCLO_SUBR, scm_makcclo,
scm_make_cclo): Remove.
* libguile/stacks.c (read_frames): Remove reference to `scm_f_gsubr_apply'.
* libguile/tags.h (scm_tc7_cclo): Remove.
(scm_tc7_gsubr): New.
(scm_tcs_subrs): Add `scm_tc7_gsubr'.
* libguile/procs.c (scm_subr_table, scm_subr_table_size,
scm_subr_table_room, subr_table_gc_hint, scm_init_subr_table,
scm_mark_subr_table): Remove.
(scm_c_make_subr): Simply return a double-cell, with the procedure
name and properties stored in a two-element array.
(scm_free_subr_entry): Free the meta-info slot.
* libguile/init.c (scm_i_init_guile): Remove call to
`scm_init_subr_table ()'.
* libguile/procs.h (SCM_SUBR_META_INFO): New macro.
(SCM_SNAME, SCM_SUBR_PROPS): Use it.
(SCM_SUBR_GENERIC, SCM_SET_SUBR_GENERIC, SCM_SET_SUBR_GENERIC_LOC):
Update.
(scm_t_subr_entry, SCM_SUBR_ENTRY, SCM_SUBRNUM, scm_subr_table,
scm_mark_subr_table, scm_init_subr_table): Remove.
* libguile/goops.c (scm_c_extend_primitive_generic): Use
`SCM_SET_SUBR_GENERIC ()' instead of using `SCM_SUBR_GENERIC ()' as an
lvalue.
* libguile/procs.c (scm_c_make_subr_with_generic): Use `SCM_SET_SUBR_GENERIC_LOC ()'.
* libguile/procs.h (SCM_SET_SUBR_GENERIC, SCM_SET_SUBR_GENERIC_LOC): New macros.
* gdbinit: Untested attempts to get the stack fondling macros to deal
with the new program representation.
* libguile/frames.c (scm_vm_frame_arguments, scm_vm_frame_source)
(scm_vm_frame_local_ref, scm_vm_frame_local_set_x): SCM_PROGRAM_DATA is
a struct scm_objcode*.
* libguile/instructions.h:
* libguile/instructions.c: Hide the instruction table and the struct
scm_instruction structure; all access to instructions now goes through
procedures. This is because instructions are no longer in a packed
array indexed by opcode. Also, declare a mask that all instructions
should fit in.
* libguile/objcodes.h:
* libguile/objcodes.c: Rewrite so that object code directly maps its
arity and length from its bytecode. This makes it unnecessary to keep
this information in programs, allowing programs to be simple conses
between the code (objcodes) and data (the object table and the closure
variables).
* libguile/programs.c (scm_make_program): Rework so that make-program
takes objcode, an object table, and externals as arguments. It's much
clearer this way, and we avoid malloc().
* libguile/stacks.c (is_vm_bootstrap_frame): Update for program/objcode
changes.
* libguile/vm-engine.c (vm_run): Initialize the jump table on the first
run, with the opcodes declared in the instruction sources, and with bad
instructions raising an error instead of wandering off into the
Unknown.
* libguile/vm-engine.h (FETCH_LENGTH): Always represent lengths as 3
bytes. The old code was too error-prone.
(NEXT_JUMP): Mask the instruction with SCM_VM_INSTRUCTION_MASK.
(NEW_FRAME): Update for program/objcode changes.
* libguile/vm-expand.h (VM_DEFINE_FUNCTION, VM_DEFINE_INSTRUCTION)
(VM_DEFINE_LOADER): Update so that we explicitly specify opcodes, so
that we have a stable bytecode API.
* libguile/vm-i-loader.c: Update license to LGPLv2+. Explicitly declare
opcodes.
(load-integer): Use an int instead of a long as the accumulator; still
need to revisit this code at some point, I think.
(load-program): Simplify, thankfully!! Just creates the objcode slice
and rolls with it.
* libguile/vm-i-scheme.c: Number the opcodes explicitly.
* libguile/vm-i-system.c: Update license to LGPLv2+. Explicitly declare
opcodes.
(make-closure): Update for new program API.
* libguile/vm.c (vm_make_boot_program): Update for new program/objcode
API. Still a bit ugly.
(scm_load_compiled_with_vm): Update for new program/objcode API.
* module/language/assembly.scm (byte-length): Fix byte-length calculation
for loaders, and load-program.
(code-pack, code-unpack): Start to move things from (system vm conv)
here.
(object->code, code->object): More things from conv.scm.
* module/language/glil.scm (<glil-program>): Add a new field,
closure-level.
(make-glil-program, compute-closure-level): Calculate the "closure
level" when making a glil program. This is the maximum depth of
external binding refs in this closure.
(unparse-glil): Fix label serialization.
* module/language/glil/compile-assembly.scm (make-meta): Prepend #f for
the meta's object table, though maybe in the future we can avoid
creating assembly in the first place.
(assoc-ref-or-acons, object-index-and-alist): GRRR! Caught again by the
different sets of arguments to assoc and assoc-ref!
(glil->assembly): Attempt to make the <glil-program> case more
readable, and fix the bugs. Sorry I don't know how to comment this
change any more than this.
(glil->assembly): For <glil-module> serialize the whole key, not just
the name.
(dump-object): subprogram-code is already a list. Serialize integers as
strings, not u8vectors. Fix the order of lists and vectors.
* module/language/glil/spec.scm (glil): Switch orders, so we prefer glil
-> assembly -> objcode. Actually glil->objcode doesn't work any more,
needs to be removed I think.
* module/language/objcode/spec.scm (objcode->value):
s/objcode->program/make-program/.
* module/language/scheme/inline.scm: Add acons inline.
* module/system/vm/conv.scm (make-byte-decoder): Skip the first 8 bytes,
they are header. Handle subprograms properly. Still needs help though.
(decode-length): Lengths are always 3 bytes now.
* module/system/vm/disasm.scm: Superficial changes to keep things
working. I'd like to fix this better in the future.
* module/system/vm/frame.scm (bootstrap-frame?): Fixes for
program-bytecode.
* module/system/vm/program.scm: Export make-program. It's program-objcode
now, no more program-bytecode.
* module/system/vm/vm.scm (vm-load): Use make-program.
* test-suite/tests/asm-to-bytecode.test: New test, very minimal.
* module/system/vm/objcode.scm: Export word-size, byte-order, and
write-objcode.
* libguile/procs.c (subr_table_gc_hint): New.
(scm_c_make_subr): Use `scm_gc_realloc ()' instead of `scm_realloc ()'.
(scm_init_subr_table): Use `scm_gc_malloc ()' instead of `scm_malloc ()'.
* libguile/procs.c (scm_c_make_subr): Use `scm_cell ()' instead of
`scm_immutable_cell ()' since subr cells can be mutated, e.g., via
`SCM_SUBR_GENERIC ()' as in `scm_c_extend_primitive_generic ()' (this
doesn't make any difference in practice as of libgc 7.1, though).
* libguile/procs.c (scm_make_procedure_with_setter): Patch through the
getter's procedure name to the procedure-with-setter. Fixes part of the
srfi-17 test, as the VM doesn't set procedure-name on define -- but
perhaps that is the bug that should be fixed. In any case this patching
is cheap.
* test-suite/tests/eval.test: Change so that (define name pws) is
initially passed an anonymous procedure-with-setter, as was the case
before the procs.c change.
net_db.c, fports.c, filesys.c, eval.c, deprecation.c, dynl.c:
Replaced uses of SCM_STRING_CHARS with proper uses of
scm_to_locale_string. Replaced SCM_STRINGP with scm_is_string.
Replaced scm_mem2string with scm_from_locale_string.
* simpos.c, posix.c (allocate_string_pointers, environ_list_to_c):
Removed, replaced all uses with scm_i_allocate_string_pointers.
SCM_INUM): Deprecated by reenaming them to SCM_I_INUMP, SCM_I_NINUMP
and SCM_I_INUM, respectively and adding deprecated versions to
deprecated.h and deprecated.c. Changed all uses to either use the
SCM_I_ variants or scm_is_*, scm_to_*, or scm_from_*, as appropriate.
SCM_NEGATE_BOOL, SCM_BOOLP): Deprecated by moving into "deprecated.h".
Replaced all uses with scm_is_false, scm_is_true, scm_from_bool, and
scm_is_bool, respectively.
* gc-card.c ("sweep_card"): set scm_gc_running while sweeping.
* gc.c (scm_i_expensive_validation_check): separate expensive
validation checks from cheap ones.
