duktape-1.5.2/src-separate/duk_hthread_builtins.c

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/*
 *  Initialize built-in objects.  Current thread must have a valstack
 *  and initialization errors may longjmp, so a setjmp() catch point
 *  must exist.
 */
 
#include "duk_internal.h"
 
/*
 *  Encoding constants, must match genbuiltins.py
 */
 
#define DUK__CLASS_BITS                  5
#define DUK__BIDX_BITS                   7
#define DUK__STRIDX_BITS                 9  /* XXX: try to optimize to 8 (would now be possible, <200 used) */
#define DUK__NATIDX_BITS                 8
#define DUK__NUM_NORMAL_PROPS_BITS       6
#define DUK__NUM_FUNC_PROPS_BITS         6
#define DUK__PROP_FLAGS_BITS             3
#define DUK__STRING_LENGTH_BITS          8
#define DUK__STRING_CHAR_BITS            7
#define DUK__LENGTH_PROP_BITS            3
#define DUK__NARGS_BITS                  3
#define DUK__PROP_TYPE_BITS              3
#define DUK__MAGIC_BITS                  16
 
#define DUK__NARGS_VARARGS_MARKER        0x07
#define DUK__NO_CLASS_MARKER             0x00   /* 0 = DUK_HOBJECT_CLASS_UNUSED */
#define DUK__NO_BIDX_MARKER              0x7f
#define DUK__NO_STRIDX_MARKER            0xff
 
#define DUK__PROP_TYPE_DOUBLE            0
#define DUK__PROP_TYPE_STRING            1
#define DUK__PROP_TYPE_STRIDX            2
#define DUK__PROP_TYPE_BUILTIN           3
#define DUK__PROP_TYPE_UNDEFINED         4
#define DUK__PROP_TYPE_BOOLEAN_TRUE      5
#define DUK__PROP_TYPE_BOOLEAN_FALSE     6
#define DUK__PROP_TYPE_ACCESSOR          7
 
/*
 *  Create built-in objects by parsing an init bitstream generated
 *  by genbuiltins.py.
 */
 
#if defined(DUK_USE_ROM_OBJECTS)
#if defined(DUK_USE_ROM_GLOBAL_CLONE) || defined(DUK_USE_ROM_GLOBAL_INHERIT)
DUK_LOCAL void duk__duplicate_ram_global_object(duk_hthread *thr) {
    duk_context *ctx;
    duk_hobject *h1;
#if defined(DUK_USE_ROM_GLOBAL_CLONE)
    duk_hobject *h2;
    duk_uint8_t *props;
    duk_size_t alloc_size;
#endif
 
    ctx = (duk_context *) thr;
 
    /* XXX: refactor into internal helper, duk_clone_hobject() */
 
#if defined(DUK_USE_ROM_GLOBAL_INHERIT)
    /* Inherit from ROM-based global object: less RAM usage, less transparent. */
    duk_push_object_helper(ctx,
                           DUK_HOBJECT_FLAG_EXTENSIBLE |
                           DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_GLOBAL),
                           DUK_BIDX_GLOBAL);
    h1 = duk_get_hobject(ctx, -1);
    DUK_ASSERT(h1 != NULL);
#elif defined(DUK_USE_ROM_GLOBAL_CLONE)
    /* Clone the properties of the ROM-based global object to create a
     * fully RAM-based global object.  Uses more memory than the inherit
     * model but more compliant.
     */
    duk_push_object_helper(ctx,
                           DUK_HOBJECT_FLAG_EXTENSIBLE |
                           DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_GLOBAL),
                           DUK_BIDX_OBJECT_PROTOTYPE);
    h1 = duk_get_hobject(ctx, -1);
    DUK_ASSERT(h1 != NULL);
    h2 = thr->builtins[DUK_BIDX_GLOBAL];
    DUK_ASSERT(h2 != NULL);
 
    /* Copy the property table verbatim; this handles attributes etc.
     * For ROM objects it's not necessary (or possible) to update
     * refcounts so leave them as is.
     */
    alloc_size = DUK_HOBJECT_P_ALLOC_SIZE(h2);
    DUK_ASSERT(alloc_size > 0);
    props = DUK_ALLOC(thr->heap, alloc_size);
    if (!props) {
        DUK_ERROR_ALLOC_DEFMSG(thr);
        return;
    }
    DUK_ASSERT(DUK_HOBJECT_GET_PROPS(thr->heap, h2) != NULL);
    DUK_MEMCPY((void *) props, (const void *) DUK_HOBJECT_GET_PROPS(thr->heap, h2), alloc_size);
 
    /* XXX: keep property attributes or tweak them here?
     * Properties will now be non-configurable even when they're
     * normally configurable for the global object.
     */
 
    DUK_ASSERT(DUK_HOBJECT_GET_PROPS(thr->heap, h1) == NULL);
    DUK_HOBJECT_SET_PROPS(thr->heap, h1, props);
    DUK_HOBJECT_SET_ESIZE(h1, DUK_HOBJECT_GET_ESIZE(h2));
    DUK_HOBJECT_SET_ENEXT(h1, DUK_HOBJECT_GET_ENEXT(h2));
    DUK_HOBJECT_SET_ASIZE(h1, DUK_HOBJECT_GET_ASIZE(h2));
    DUK_HOBJECT_SET_HSIZE(h1, DUK_HOBJECT_GET_HSIZE(h2));
#else
#error internal error in defines
#endif
 
    duk_hobject_compact_props(thr, h1);
    DUK_ASSERT(thr->builtins[DUK_BIDX_GLOBAL] != NULL);
    DUK_ASSERT(!DUK_HEAPHDR_NEEDS_REFCOUNT_UPDATE((duk_heaphdr *) thr->builtins[DUK_BIDX_GLOBAL]));  /* no need to decref */
    thr->builtins[DUK_BIDX_GLOBAL] = h1;
    DUK_HOBJECT_INCREF(thr, h1);
    DUK_D(DUK_DPRINT("duplicated global object: %!O", h1));
 
 
    /* Create a fresh object environment for the global scope.  This is
     * needed so that the global scope points to the newly created RAM-based
     * global object.
     */
    duk_push_object_helper(ctx,
                           DUK_HOBJECT_FLAG_EXTENSIBLE |
                           DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_OBJENV),
                           -1);  /* no prototype */
    h1 = duk_get_hobject(ctx, -1);
    DUK_ASSERT(h1 != NULL);
    duk_dup(ctx, -2);
    duk_dup(ctx, -1);  /* -> [ ... new_global new_globalenv new_global new_global ] */
    duk_xdef_prop_stridx(thr, -3, DUK_STRIDX_INT_TARGET, DUK_PROPDESC_FLAGS_NONE);
    duk_xdef_prop_stridx(thr, -2, DUK_STRIDX_INT_THIS, DUK_PROPDESC_FLAGS_NONE);  /* always provideThis=true */
 
    duk_hobject_compact_props(thr, h1);
    DUK_ASSERT(thr->builtins[DUK_BIDX_GLOBAL_ENV] != NULL);
    DUK_ASSERT(!DUK_HEAPHDR_NEEDS_REFCOUNT_UPDATE((duk_heaphdr *) thr->builtins[DUK_BIDX_GLOBAL_ENV]));  /* no need to decref */
    thr->builtins[DUK_BIDX_GLOBAL_ENV] = h1;
    DUK_HOBJECT_INCREF(thr, h1);
    DUK_D(DUK_DPRINT("duplicated global env: %!O", h1));
 
    duk_pop_2(ctx);
}
#endif  /* DUK_USE_ROM_GLOBAL_CLONE || DUK_USE_ROM_GLOBAL_INHERIT */
 
DUK_INTERNAL void duk_hthread_create_builtin_objects(duk_hthread *thr) {
    /* Setup builtins from ROM objects.  All heaps/threads will share
     * the same readonly objects.
     */
    duk_small_uint_t i;
 
    for (i = 0; i < DUK_NUM_BUILTINS; i++) {
        duk_hobject *h;
        h = (duk_hobject *) DUK_LOSE_CONST(duk_rom_builtins_bidx[i]);
        DUK_ASSERT(h != NULL);
        thr->builtins[i] = h;
    }
 
#if defined(DUK_USE_ROM_GLOBAL_CLONE) || defined(DUK_USE_ROM_GLOBAL_INHERIT)
    /* By default the global object is read-only which is often much
     * more of an issue than having read-only built-in objects (like
     * RegExp, Date, etc).  Use a RAM-based copy of the global object
     * and the global environment object for convenience.
     */
    duk__duplicate_ram_global_object(thr);
#endif
}
#else  /* DUK_USE_ROM_OBJECTS */
DUK_LOCAL void duk__push_stridx(duk_context *ctx, duk_bitdecoder_ctx *bd) {
    duk_small_uint_t n;
 
    n = (duk_small_uint_t) duk_bd_decode(bd, DUK__STRIDX_BITS);
    DUK_ASSERT_DISABLE(n >= 0);  /* unsigned */
    DUK_ASSERT(n < DUK_HEAP_NUM_STRINGS);
    duk_push_hstring_stridx(ctx, n);
}
DUK_LOCAL void duk__push_string(duk_context *ctx, duk_bitdecoder_ctx *bd) {
    duk_small_uint_t n;
    duk_small_uint_t i;
    duk_uint8_t *p;
 
    n = (duk_small_uint_t) duk_bd_decode(bd, DUK__STRING_LENGTH_BITS);
    p = (duk_uint8_t *) duk_push_fixed_buffer(ctx, n);
    for (i = 0; i < n; i++) {
        *p++ = (duk_uint8_t) duk_bd_decode(bd, DUK__STRING_CHAR_BITS);
    }
    duk_to_string(ctx, -1);
}
DUK_LOCAL void duk__push_stridx_or_string(duk_context *ctx, duk_bitdecoder_ctx *bd) {
    if (duk_bd_decode_flag(bd)) {
        duk__push_string(ctx, bd);
    } else {
        duk__push_stridx(ctx, bd);
    }
}
DUK_LOCAL void duk__push_double(duk_context *ctx, duk_bitdecoder_ctx *bd) {
    duk_double_union du;
    duk_small_uint_t i;
 
    for (i = 0; i < 8; i++) {
        /* Encoding endianness must match target memory layout,
         * build scripts and genbuiltins.py must ensure this.
         */
        du.uc[i] = (duk_uint8_t) duk_bd_decode(bd, 8);
    }
 
    duk_push_number(ctx, du.d);  /* push operation normalizes NaNs */
}
 
DUK_INTERNAL void duk_hthread_create_builtin_objects(duk_hthread *thr) {
    duk_context *ctx = (duk_context *) thr;
    duk_bitdecoder_ctx bd_ctx;
    duk_bitdecoder_ctx *bd = &bd_ctx;  /* convenience */
    duk_hobject *h;
    duk_small_uint_t i, j;
 
    DUK_D(DUK_DPRINT("INITBUILTINS BEGIN: DUK_NUM_BUILTINS=%d, DUK_NUM_BUILTINS_ALL=%d", (int) DUK_NUM_BUILTINS, (int) DUK_NUM_ALL_BUILTINS));
 
    DUK_MEMZERO(&bd_ctx, sizeof(bd_ctx));
    bd->data = (const duk_uint8_t *) duk_builtins_data;
    bd->length = (duk_size_t) DUK_BUILTINS_DATA_LENGTH;
 
    /*
     *  First create all built-in bare objects on the empty valstack.
     *
     *  Built-ins in the index range [0,DUK_NUM_BUILTINS-1] have value
     *  stack indices matching their eventual thr->builtins[] index.
     *
     *  Built-ins in the index range [DUK_NUM_BUILTINS,DUK_NUM_ALL_BUILTINS]
     *  will exist on the value stack during init but won't be placed
     *  into thr->builtins[].  These are objects referenced in some way
     *  from thr->builtins[] roots but which don't need to be indexed by
     *  Duktape through thr->builtins[] (e.g. user custom objects).
     */
 
    duk_require_stack(ctx, DUK_NUM_ALL_BUILTINS);
 
    DUK_DD(DUK_DDPRINT("create empty built-ins"));
    DUK_ASSERT_TOP(ctx, 0);
    for (i = 0; i < DUK_NUM_ALL_BUILTINS; i++) {
        duk_small_uint_t class_num;
        duk_small_int_t len = -1;  /* must be signed */
 
        class_num = (duk_small_uint_t) duk_bd_decode(bd, DUK__CLASS_BITS);
        len = (duk_small_int_t) duk_bd_decode_flagged(bd, DUK__LENGTH_PROP_BITS, (duk_int32_t) -1 /*def_value*/);
 
        if (class_num == DUK_HOBJECT_CLASS_FUNCTION) {
            duk_small_uint_t natidx;
            duk_int_t c_nargs;  /* must hold DUK_VARARGS */
            duk_c_function c_func;
            duk_int16_t magic;
 
            DUK_DDD(DUK_DDDPRINT("len=%ld", (long) len));
            DUK_ASSERT(len >= 0);
 
            natidx = (duk_small_uint_t) duk_bd_decode(bd, DUK__NATIDX_BITS);
            c_func = duk_bi_native_functions[natidx];
 
            c_nargs = (duk_small_uint_t) duk_bd_decode_flagged(bd, DUK__NARGS_BITS, len /*def_value*/);
            if (c_nargs == DUK__NARGS_VARARGS_MARKER) {
                c_nargs = DUK_VARARGS;
            }
 
            /* XXX: set magic directly here? (it could share the c_nargs arg) */
            duk_push_c_function_noexotic(ctx, c_func, c_nargs);
 
            h = duk_require_hobject(ctx, -1);
            DUK_ASSERT(h != NULL);
 
            /* Currently all built-in native functions are strict.
             * duk_push_c_function() now sets strict flag, so
             * assert for it.
             */
            DUK_ASSERT(DUK_HOBJECT_HAS_STRICT(h));
 
            /* XXX: function properties */
 
            /* Built-in 'name' is not writable by default.  Function '.name'
             * is writable to allow user code to set a '.name' on a native
             * function.
             */
            duk__push_stridx_or_string(ctx, bd);
            duk_xdef_prop_stridx(ctx,
                                 -2,
                                 DUK_STRIDX_NAME,
                                 (i == DUK_BIDX_FUNCTION_PROTOTYPE) ?
                                     DUK_PROPDESC_FLAGS_W : DUK_PROPDESC_FLAGS_NONE);
 
            /* Almost all global level Function objects are constructable
             * but not all: Function.prototype is a non-constructable,
             * callable Function.
             */
            if (duk_bd_decode_flag(bd)) {
                DUK_ASSERT(DUK_HOBJECT_HAS_CONSTRUCTABLE(h));
            } else {
                DUK_HOBJECT_CLEAR_CONSTRUCTABLE(h);
            }
 
            /* Cast converts magic to 16-bit signed value */
            magic = (duk_int16_t) duk_bd_decode_flagged(bd, DUK__MAGIC_BITS, 0 /*def_value*/);
            ((duk_hnativefunction *) h)->magic = magic;
        } else {
            /* XXX: ARRAY_PART for Array prototype? */
 
            duk_push_object_helper(ctx,
                                   DUK_HOBJECT_FLAG_EXTENSIBLE,
                                   -1);  /* no prototype or class yet */
 
            h = duk_require_hobject(ctx, -1);
            DUK_ASSERT(h != NULL);
        }
 
        DUK_HOBJECT_SET_CLASS_NUMBER(h, class_num);
 
        if (i < DUK_NUM_BUILTINS) {
            thr->builtins[i] = h;
            DUK_HOBJECT_INCREF(thr, &h->hdr);
        }
 
        if (len >= 0) {
            /*
             *  For top-level objects, 'length' property has the following
             *  default attributes: non-writable, non-enumerable, non-configurable
             *  (E5 Section 15).
             *
             *  However, 'length' property for Array.prototype has attributes
             *  expected of an Array instance which are different: writable,
             *  non-enumerable, non-configurable (E5 Section 15.4.5.2).
             *
             *  This is currently determined implicitly based on class; there are
             *  no attribute flags in the init data.
             */
 
            duk_push_int(ctx, len);
            duk_xdef_prop_stridx(ctx,
                                 -2,
                                 DUK_STRIDX_LENGTH,
                                 (class_num == DUK_HOBJECT_CLASS_ARRAY ?  /* only Array.prototype matches */
                                  DUK_PROPDESC_FLAGS_W : DUK_PROPDESC_FLAGS_NONE));
        }
 
        /* enable exotic behaviors last */
 
        if (class_num == DUK_HOBJECT_CLASS_ARRAY) {
            DUK_HOBJECT_SET_EXOTIC_ARRAY(h);
        }
        if (class_num == DUK_HOBJECT_CLASS_STRING) {
            DUK_HOBJECT_SET_EXOTIC_STRINGOBJ(h);
        }
 
        /* some assertions */
 
        DUK_ASSERT(DUK_HOBJECT_HAS_EXTENSIBLE(h));
        /* DUK_HOBJECT_FLAG_CONSTRUCTABLE varies */
        DUK_ASSERT(!DUK_HOBJECT_HAS_BOUND(h));
        DUK_ASSERT(!DUK_HOBJECT_HAS_COMPILEDFUNCTION(h));
        /* DUK_HOBJECT_FLAG_NATIVEFUNCTION varies */
        DUK_ASSERT(!DUK_HOBJECT_HAS_THREAD(h));
        DUK_ASSERT(!DUK_HOBJECT_HAS_ARRAY_PART(h));       /* currently, even for Array.prototype */
        /* DUK_HOBJECT_FLAG_STRICT varies */
        DUK_ASSERT(!DUK_HOBJECT_HAS_NATIVEFUNCTION(h) ||  /* all native functions have NEWENV */
                   DUK_HOBJECT_HAS_NEWENV(h));
        DUK_ASSERT(!DUK_HOBJECT_HAS_NAMEBINDING(h));
        DUK_ASSERT(!DUK_HOBJECT_HAS_CREATEARGS(h));
        DUK_ASSERT(!DUK_HOBJECT_HAS_ENVRECCLOSED(h));
        /* DUK_HOBJECT_FLAG_EXOTIC_ARRAY varies */
        /* DUK_HOBJECT_FLAG_EXOTIC_STRINGOBJ varies */
        DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARGUMENTS(h));
 
        DUK_DDD(DUK_DDDPRINT("created built-in %ld, class=%ld, length=%ld", (long) i, (long) class_num, (long) len));
    }
 
    /*
     *  Then decode the builtins init data (see genbuiltins.py) to
     *  init objects
     */
 
    DUK_DD(DUK_DDPRINT("initialize built-in object properties"));
    for (i = 0; i < DUK_NUM_ALL_BUILTINS; i++) {
        duk_small_uint_t t;
        duk_small_uint_t num;
 
        DUK_DDD(DUK_DDDPRINT("initializing built-in object at index %ld", (long) i));
        h = duk_require_hobject(ctx, i);
        DUK_ASSERT(h != NULL);
 
        t = (duk_small_uint_t) duk_bd_decode(bd, DUK__BIDX_BITS);
        if (t != DUK__NO_BIDX_MARKER) {
            DUK_DDD(DUK_DDDPRINT("set internal prototype: built-in %ld", (long) t));
            DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, h, duk_require_hobject(ctx, t));
        }
 
        t = (duk_small_uint_t) duk_bd_decode(bd, DUK__BIDX_BITS);
        if (t != DUK__NO_BIDX_MARKER) {
            /* 'prototype' property for all built-in objects (which have it) has attributes:
             *  [[Writable]] = false,
             *  [[Enumerable]] = false,
             *  [[Configurable]] = false
             */
            DUK_DDD(DUK_DDDPRINT("set external prototype: built-in %ld", (long) t));
            duk_xdef_prop_stridx_builtin(ctx, i, DUK_STRIDX_PROTOTYPE, t, DUK_PROPDESC_FLAGS_NONE);
        }
 
        t = (duk_small_uint_t) duk_bd_decode(bd, DUK__BIDX_BITS);
        if (t != DUK__NO_BIDX_MARKER) {
            /* 'constructor' property for all built-in objects (which have it) has attributes:
             *  [[Writable]] = true,
             *  [[Enumerable]] = false,
             *  [[Configurable]] = true
             */
            DUK_DDD(DUK_DDDPRINT("set external constructor: built-in %ld", (long) t));
            duk_xdef_prop_stridx_builtin(ctx, i, DUK_STRIDX_CONSTRUCTOR, t, DUK_PROPDESC_FLAGS_WC);
        }
 
        /* normal valued properties */
        num = (duk_small_uint_t) duk_bd_decode(bd, DUK__NUM_NORMAL_PROPS_BITS);
        DUK_DDD(DUK_DDDPRINT("built-in object %ld, %ld normal valued properties", (long) i, (long) num));
        for (j = 0; j < num; j++) {
            duk_small_uint_t prop_flags;
 
            duk__push_stridx_or_string(ctx, bd);
 
            /*
             *  Property attribute defaults are defined in E5 Section 15 (first
             *  few pages); there is a default for all properties and a special
             *  default for 'length' properties.  Variation from the defaults is
             *  signaled using a single flag bit in the bitstream.
             */
 
            if (duk_bd_decode_flag(bd)) {
                prop_flags = (duk_small_uint_t) duk_bd_decode(bd, DUK__PROP_FLAGS_BITS);
            } else {
                prop_flags = DUK_PROPDESC_FLAGS_WC;
            }
 
            t = (duk_small_uint_t) duk_bd_decode(bd, DUK__PROP_TYPE_BITS);
 
            DUK_DDD(DUK_DDDPRINT("built-in %ld, normal-valued property %ld, key %!T, flags 0x%02lx, type %ld",
                                 (long) i, (long) j, duk_get_tval(ctx, -1), (unsigned long) prop_flags, (long) t));
 
            switch (t) {
            case DUK__PROP_TYPE_DOUBLE: {
                duk__push_double(ctx, bd);
                break;
            }
            case DUK__PROP_TYPE_STRING: {
                duk__push_string(ctx, bd);
                break;
            }
            case DUK__PROP_TYPE_STRIDX: {
                duk__push_stridx(ctx, bd);
                break;
            }
            case DUK__PROP_TYPE_BUILTIN: {
                duk_small_uint_t bidx;
 
                bidx = (duk_small_uint_t) duk_bd_decode(bd, DUK__BIDX_BITS);
                DUK_ASSERT(bidx != DUK__NO_BIDX_MARKER);
                duk_dup(ctx, (duk_idx_t) bidx);
                break;
            }
            case DUK__PROP_TYPE_UNDEFINED: {
                duk_push_undefined(ctx);
                break;
            }
            case DUK__PROP_TYPE_BOOLEAN_TRUE: {
                duk_push_true(ctx);
                break;
            }
            case DUK__PROP_TYPE_BOOLEAN_FALSE: {
                duk_push_false(ctx);
                break;
            }
            case DUK__PROP_TYPE_ACCESSOR: {
                duk_small_uint_t natidx_getter = (duk_small_uint_t) duk_bd_decode(bd, DUK__NATIDX_BITS);
                duk_small_uint_t natidx_setter = (duk_small_uint_t) duk_bd_decode(bd, DUK__NATIDX_BITS);
                duk_c_function c_func_getter;
                duk_c_function c_func_setter;
 
                /* XXX: this is a bit awkward because there is no exposed helper
                 * in the API style, only this internal helper.
                 */
                DUK_DDD(DUK_DDDPRINT("built-in accessor property: objidx=%ld, key=%!T, getteridx=%ld, setteridx=%ld, flags=0x%04lx",
                                     (long) i, duk_get_tval(ctx, -1), (long) natidx_getter, (long) natidx_setter, (unsigned long) prop_flags));
 
                c_func_getter = duk_bi_native_functions[natidx_getter];
                c_func_setter = duk_bi_native_functions[natidx_setter];
                duk_push_c_function_noconstruct_noexotic(ctx, c_func_getter, 0);  /* always 0 args */
                duk_push_c_function_noconstruct_noexotic(ctx, c_func_setter, 1);  /* always 1 arg */
 
                /* XXX: magic for getter/setter? use duk_def_prop()? */
 
                DUK_ASSERT((prop_flags & DUK_PROPDESC_FLAG_WRITABLE) == 0);  /* genbuiltins.py ensures */
 
                prop_flags |= DUK_PROPDESC_FLAG_ACCESSOR;  /* accessor flag not encoded explicitly */
                duk_hobject_define_accessor_internal(thr,
                                                     duk_require_hobject(ctx, i),
                                                     duk_get_hstring(ctx, -3),
                                                     duk_require_hobject(ctx, -2),
                                                     duk_require_hobject(ctx, -1),
                                                     prop_flags);
                duk_pop_3(ctx);  /* key, getter and setter, now reachable through object */
                goto skip_value;
            }
            default: {
                /* exhaustive */
                DUK_UNREACHABLE();
            }
            }
 
            DUK_ASSERT((prop_flags & DUK_PROPDESC_FLAG_ACCESSOR) == 0);
            duk_xdef_prop(ctx, i, prop_flags);
 
         skip_value:
            continue;  /* avoid empty label at the end of a compound statement */
        }
 
        /* native function properties */
        num = (duk_small_uint_t) duk_bd_decode(bd, DUK__NUM_FUNC_PROPS_BITS);
        DUK_DDD(DUK_DDDPRINT("built-in object %ld, %ld function valued properties", (long) i, (long) num));
        for (j = 0; j < num; j++) {
            duk_hstring *h_key;
            duk_small_uint_t natidx;
            duk_int_t c_nargs;  /* must hold DUK_VARARGS */
            duk_small_uint_t c_length;
            duk_int16_t magic;
            duk_c_function c_func;
            duk_hnativefunction *h_func;
#if defined(DUK_USE_LIGHTFUNC_BUILTINS)
            duk_small_int_t lightfunc_eligible;
#endif
 
            duk__push_stridx_or_string(ctx, bd);
            h_key = duk_get_hstring(ctx, -1);
            DUK_ASSERT(h_key != NULL);
            DUK_UNREF(h_key);
            natidx = (duk_small_uint_t) duk_bd_decode(bd, DUK__NATIDX_BITS);
 
            c_length = (duk_small_uint_t) duk_bd_decode(bd, DUK__LENGTH_PROP_BITS);
            c_nargs = (duk_int_t) duk_bd_decode_flagged(bd, DUK__NARGS_BITS, (duk_int32_t) c_length /*def_value*/);
            if (c_nargs == DUK__NARGS_VARARGS_MARKER) {
                c_nargs = DUK_VARARGS;
            }
 
            c_func = duk_bi_native_functions[natidx];
 
            DUK_DDD(DUK_DDDPRINT("built-in %ld, function-valued property %ld, key %!O, natidx %ld, length %ld, nargs %ld",
                                 (long) i, (long) j, (duk_heaphdr *) h_key, (long) natidx, (long) c_length,
                                 (c_nargs == DUK_VARARGS ? (long) -1 : (long) c_nargs)));
 
            /* Cast converts magic to 16-bit signed value */
            magic = (duk_int16_t) duk_bd_decode_flagged(bd, DUK__MAGIC_BITS, 0);
 
#if defined(DUK_USE_LIGHTFUNC_BUILTINS)
            lightfunc_eligible =
                ((c_nargs >= DUK_LFUNC_NARGS_MIN && c_nargs <= DUK_LFUNC_NARGS_MAX) || (c_nargs == DUK_VARARGS)) &&
                (c_length <= DUK_LFUNC_LENGTH_MAX) &&
                (magic >= DUK_LFUNC_MAGIC_MIN && magic <= DUK_LFUNC_MAGIC_MAX);
 
            if (h_key == DUK_HTHREAD_STRING_EVAL(thr) ||
                h_key == DUK_HTHREAD_STRING_YIELD(thr) ||
                h_key == DUK_HTHREAD_STRING_RESUME(thr) ||
                h_key == DUK_HTHREAD_STRING_REQUIRE(thr)) {
                /* These functions have trouble working as lightfuncs.
                 * Some of them have specific asserts and some may have
                     * additional properties (e.g. 'require.id' may be written).
                 */
                DUK_D(DUK_DPRINT("reject as lightfunc: key=%!O, i=%d, j=%d", (duk_heaphdr *) h_key, (int) i, (int) j));
                lightfunc_eligible = 0;
            }
 
            if (lightfunc_eligible) {
                duk_tval tv_lfunc;
                duk_small_uint_t lf_nargs = (c_nargs == DUK_VARARGS ? DUK_LFUNC_NARGS_VARARGS : c_nargs);
                duk_small_uint_t lf_flags = DUK_LFUNC_FLAGS_PACK(magic, c_length, lf_nargs);
                DUK_TVAL_SET_LIGHTFUNC(&tv_lfunc, c_func, lf_flags);
                duk_push_tval(ctx, &tv_lfunc);
                DUK_D(DUK_DPRINT("built-in function eligible as light function: i=%d, j=%d c_length=%ld, c_nargs=%ld, magic=%ld -> %!iT", (int) i, (int) j, (long) c_length, (long) c_nargs, (long) magic, duk_get_tval(ctx, -1)));
                goto lightfunc_skip;
            }
 
            DUK_D(DUK_DPRINT("built-in function NOT ELIGIBLE as light function: i=%d, j=%d c_length=%ld, c_nargs=%ld, magic=%ld", (int) i, (int) j, (long) c_length, (long) c_nargs, (long) magic));
#endif  /* DUK_USE_LIGHTFUNC_BUILTINS */
 
            /* [ (builtin objects) name ] */
 
            duk_push_c_function_noconstruct_noexotic(ctx, c_func, c_nargs);
            h_func = duk_require_hnativefunction(ctx, -1);
            DUK_UNREF(h_func);
 
            /* Currently all built-in native functions are strict.
             * This doesn't matter for many functions, but e.g.
             * String.prototype.charAt (and other string functions)
             * rely on being strict so that their 'this' binding is
             * not automatically coerced.
             */
            DUK_HOBJECT_SET_STRICT((duk_hobject *) h_func);
 
            /* No built-in functions are constructable except the top
             * level ones (Number, etc).
             */
            DUK_ASSERT(!DUK_HOBJECT_HAS_CONSTRUCTABLE((duk_hobject *) h_func));
 
            /* XXX: any way to avoid decoding magic bit; there are quite
             * many function properties and relatively few with magic values.
             */
            h_func->magic = magic;
 
            /* [ (builtin objects) name func ] */
 
            duk_push_int(ctx, c_length);
            duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_LENGTH, DUK_PROPDESC_FLAGS_NONE);
 
            duk_dup(ctx, -2);
            duk_xdef_prop_stridx(ctx, -2, DUK_STRIDX_NAME, DUK_PROPDESC_FLAGS_NONE);
 
            /* XXX: other properties of function instances; 'arguments', 'caller'. */
 
            DUK_DD(DUK_DDPRINT("built-in object %ld, function property %ld -> %!T",
                               (long) i, (long) j, (duk_tval *) duk_get_tval(ctx, -1)));
 
            /* [ (builtin objects) name func ] */
 
            /*
             *  The default property attributes are correct for all
             *  function valued properties of built-in objects now.
             */
 
#if defined(DUK_USE_LIGHTFUNC_BUILTINS)
         lightfunc_skip:
#endif
 
            duk_xdef_prop(ctx, i, DUK_PROPDESC_FLAGS_WC);
 
            /* [ (builtin objects) ] */
        }
    }
 
    /*
     *  Special post-tweaks, for cases not covered by the init data format.
     *
     *  - Set Date.prototype.toGMTString to Date.prototype.toUTCString.
     *    toGMTString is required to have the same Function object as
     *    toUTCString in E5 Section B.2.6.  Note that while Smjs respects
     *    this, V8 does not (the Function objects are distinct).
     *
     *  - Make DoubleError non-extensible.
     *
     *  - Add info about most important effective compile options to Duktape.
     *
     *  - Possibly remove some properties (values or methods) which are not
     *    desirable with current feature options but are not currently
     *    conditional in init data.
     */
 
    duk_get_prop_stridx(ctx, DUK_BIDX_DATE_PROTOTYPE, DUK_STRIDX_TO_UTC_STRING);
    duk_xdef_prop_stridx(ctx, DUK_BIDX_DATE_PROTOTYPE, DUK_STRIDX_TO_GMT_STRING, DUK_PROPDESC_FLAGS_WC);
 
    h = duk_require_hobject(ctx, DUK_BIDX_DOUBLE_ERROR);
    DUK_ASSERT(h != NULL);
    DUK_HOBJECT_CLEAR_EXTENSIBLE(h);
 
#if !defined(DUK_USE_ES6_OBJECT_PROTO_PROPERTY)
    DUK_DD(DUK_DDPRINT("delete Object.prototype.__proto__ built-in which is not enabled in features"));
    (void) duk_hobject_delprop_raw(thr, thr->builtins[DUK_BIDX_OBJECT_PROTOTYPE], DUK_HTHREAD_STRING___PROTO__(thr), DUK_DELPROP_FLAG_THROW);
#endif
 
#if !defined(DUK_USE_ES6_OBJECT_SETPROTOTYPEOF)
    DUK_DD(DUK_DDPRINT("delete Object.setPrototypeOf built-in which is not enabled in features"));
    (void) duk_hobject_delprop_raw(thr, thr->builtins[DUK_BIDX_OBJECT_CONSTRUCTOR], DUK_HTHREAD_STRING_SET_PROTOTYPE_OF(thr), DUK_DELPROP_FLAG_THROW);
#endif
 
    /* XXX: relocate */
    duk_push_string(ctx,
            /* Endianness indicator */
#if defined(DUK_USE_INTEGER_LE)
                    "l"
#elif defined(DUK_USE_INTEGER_BE)
                    "b"
#elif defined(DUK_USE_INTEGER_ME)  /* integer mixed endian not really used now */
                    "m"
#else
                    "?"
#endif
#if defined(DUK_USE_DOUBLE_LE)
                    "l"
#elif defined(DUK_USE_DOUBLE_BE)
                    "b"
#elif defined(DUK_USE_DOUBLE_ME)
                    "m"
#else
                    "?"
#endif
                    " "
            /* Packed or unpacked tval */
#if defined(DUK_USE_PACKED_TVAL)
                    "p"
#else
                    "u"
#endif
#if defined(DUK_USE_FASTINT)
            "f"
#endif
            " "
            /* Low memory options */
#if defined(DUK_USE_STRTAB_CHAIN)
            "c"  /* chain */
#elif defined(DUK_USE_STRTAB_PROBE)
            "p"  /* probe */
#else
            "?"
#endif
#if !defined(DUK_USE_HEAPPTR16) && !defined(DUK_DATAPTR16) && !defined(DUK_FUNCPTR16)
            "n"
#endif
#if defined(DUK_USE_HEAPPTR16)
            "h"
#endif
#if defined(DUK_USE_DATAPTR16)
            "d"
#endif
#if defined(DUK_USE_FUNCPTR16)
            "f"
#endif
#if defined(DUK_USE_REFCOUNT16)
            "R"
#endif
#if defined(DUK_USE_STRHASH16)
            "H"
#endif
#if defined(DUK_USE_STRLEN16)
            "S"
#endif
#if defined(DUK_USE_BUFLEN16)
            "B"
#endif
#if defined(DUK_USE_OBJSIZES16)
            "O"
#endif
#if defined(DUK_USE_LIGHTFUNC_BUILTINS)
            "L"
#endif
#if defined(DUK_USE_ROM_STRINGS) || defined(DUK_USE_ROM_OBJECTS)
            /* XXX: This won't be shown in practice now
             * because this code is not run when builtins
             * are in ROM.
             */
            "Z"
#endif
                    " "
            /* Object property allocation layout */
#if defined(DUK_USE_HOBJECT_LAYOUT_1)
            "p1"
#elif defined(DUK_USE_HOBJECT_LAYOUT_2)
            "p2"
#elif defined(DUK_USE_HOBJECT_LAYOUT_3)
            "p3"
#else
            "p?"
#endif
            " "
            /* Alignment guarantee */
#if (DUK_USE_ALIGN_BY == 4)
            "a4"
#elif (DUK_USE_ALIGN_BY == 8)
            "a8"
#elif (DUK_USE_ALIGN_BY == 1)
            "a1"
#else
#error invalid DUK_USE_ALIGN_BY
#endif
            " "
            /* Architecture, OS, and compiler strings */
                    DUK_USE_ARCH_STRING
            " "
                    DUK_USE_OS_STRING
            " "
                    DUK_USE_COMPILER_STRING);
    duk_xdef_prop_stridx(ctx, DUK_BIDX_DUKTAPE, DUK_STRIDX_ENV, DUK_PROPDESC_FLAGS_WC);
 
    /*
     *  InitJS code - Ecmascript code evaluated from a built-in source
     *  which provides e.g. backward compatibility.  User can also provide
     *  JS code to be evaluated at startup.
     */
 
#ifdef DUK_USE_BUILTIN_INITJS
    /* XXX: compression */
    DUK_DD(DUK_DDPRINT("running built-in initjs"));
    duk_eval_string(ctx, (const char *) duk_initjs_data);  /* initjs data is NUL terminated */
    duk_pop(ctx);
#endif  /* DUK_USE_BUILTIN_INITJS */
 
#ifdef DUK_USE_USER_INITJS
    /* XXX: compression (as an option) */
    DUK_DD(DUK_DDPRINT("running user initjs"));
    duk_eval_string_noresult(ctx, (const char *) DUK_USE_USER_INITJS);
#endif  /* DUK_USE_USER_INITJS */
 
    /*
     *  Since built-ins are not often extended, compact them.
     */
 
    DUK_DD(DUK_DDPRINT("compact built-ins"));
    for (i = 0; i < DUK_NUM_ALL_BUILTINS; i++) {
        duk_hobject_compact_props(thr, duk_require_hobject(ctx, i));
    }
 
    DUK_D(DUK_DPRINT("INITBUILTINS END"));
 
#ifdef DUK_USE_DDPRINT
    for (i = 0; i < DUK_NUM_ALL_BUILTINS; i++) {
        DUK_DD(DUK_DDPRINT("built-in object %ld after initialization and compacting: %!@iO",
                           (long) i, (duk_heaphdr *) duk_require_hobject(ctx, i)));
    }
#endif
 
    /*
     *  Pop built-ins from stack: they are now INCREF'd and
     *  reachable from the builtins[] array or indirectly
     *  through builtins[].
     */
 
    duk_set_top(ctx, 0);
    DUK_ASSERT_TOP(ctx, 0);
}
#endif  /* DUK_USE_ROM_OBJECTS */
 
DUK_INTERNAL void duk_hthread_copy_builtin_objects(duk_hthread *thr_from, duk_hthread *thr_to) {
    duk_small_uint_t i;
 
    for (i = 0; i < DUK_NUM_BUILTINS; i++) {
        thr_to->builtins[i] = thr_from->builtins[i];
        DUK_HOBJECT_INCREF_ALLOWNULL(thr_to, thr_to->builtins[i]);  /* side effect free */
    }
}