/*
* Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
* Copyright (c) 1999-2000 by Hewlett-Packard Company.  All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose,  provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*
*/

#include "private/gc_pmark.h"
#include "gc_inline.h" /* for GC_malloc_kind */

/*
* Some simple primitives for allocation with explicit type information.
* Simple objects are allocated such that they contain a GC_descr at the
* end (in the last allocated word).  This descriptor may be a procedure
* which then examines an extended descriptor passed as its environment.
*
* Arrays are treated as simple objects if they have sufficiently simple
* structure.  Otherwise they are allocated from an array kind that supplies
* a special mark procedure.  These arrays contain a pointer to a
* complex_descriptor as their last word.
* This is done because the environment field is too small, and the collector
* must trace the complex_descriptor.
*
* Note that descriptors inside objects may appear cleared, if we encounter a
* false reference to an object on a free list.  In the GC_descr case, this
* is OK, since a 0 descriptor corresponds to examining no fields.
* In the complex_descriptor case, we explicitly check for that case.
*
* MAJOR PARTS OF THIS CODE HAVE NOT BEEN TESTED AT ALL and are not testable,
* since they are not accessible through the current interface.
*/

#include "gc_typed.h"

#define TYPD_EXTRA_BYTES (sizeof(word) - EXTRA_BYTES)

STATIC int GC_explicit_kind = 0;
                       /* Object kind for objects with indirect        */
                       /* (possibly extended) descriptors.             */

STATIC int GC_array_kind = 0;
                       /* Object kind for objects with complex         */
                       /* descriptors and GC_array_mark_proc.          */

/* Array descriptors.  GC_array_mark_proc understands these.    */
/* We may eventually need to add provisions for headers and     */
/* trailers.  Hence we provide for tree structured descriptors, */
/* though we don't really use them currently.                   */

struct LeafDescriptor {         /* Describes simple array.      */
       word ld_tag;
#       define LEAF_TAG 1
       size_t ld_size;         /* bytes per element            */
                               /* multiple of ALIGNMENT.       */
       size_t ld_nelements;    /* Number of elements.          */
       GC_descr ld_descriptor; /* A simple length, bitmap,     */
                               /* or procedure descriptor.     */
};

struct ComplexArrayDescriptor {
       word ad_tag;
#       define ARRAY_TAG 2
       size_t ad_nelements;
       union ComplexDescriptor * ad_element_descr;
};

struct SequenceDescriptor {
       word sd_tag;
#       define SEQUENCE_TAG 3
       union ComplexDescriptor * sd_first;
       union ComplexDescriptor * sd_second;
};

typedef union ComplexDescriptor {
   struct LeafDescriptor ld;
   struct ComplexArrayDescriptor ad;
   struct SequenceDescriptor sd;
} complex_descriptor;
#define TAG ad.ad_tag

#define ED_INITIAL_SIZE 100

STATIC int GC_typed_mark_proc_index = 0; /* Indices of my mark          */
STATIC int GC_array_mark_proc_index = 0; /* procedures.                 */

STATIC void GC_push_typed_structures_proc(void)
{
 GC_PUSH_ALL_SYM(GC_ext_descriptors);
}

/* Add a multiword bitmap to GC_ext_descriptors arrays.  Return */
/* starting index.                                              */
/* Returns -1 on failure.                                       */
/* Caller does not hold allocation lock.                        */
STATIC signed_word GC_add_ext_descriptor(const word * bm, word nbits)
{
   size_t nwords = divWORDSZ(nbits + WORDSZ-1);
   signed_word result;
   size_t i;
   word last_part;
   size_t extra_bits;
   DCL_LOCK_STATE;

   LOCK();
   while (GC_avail_descr + nwords >= GC_ed_size) {
       typed_ext_descr_t *newExtD;
       size_t new_size;
       word ed_size = GC_ed_size;

       if (ed_size == 0) {
           GC_ASSERT((word)(&GC_ext_descriptors) % sizeof(word) == 0);
           GC_push_typed_structures = GC_push_typed_structures_proc;
           UNLOCK();
           new_size = ED_INITIAL_SIZE;
       } else {
           UNLOCK();
           new_size = 2 * ed_size;
           if (new_size > MAX_ENV) return(-1);
       }
       newExtD = (typed_ext_descr_t*)GC_malloc_atomic(new_size
                                               * sizeof(typed_ext_descr_t));
       if (NULL == newExtD)
           return -1;
       LOCK();
       if (ed_size == GC_ed_size) {
           if (GC_avail_descr != 0) {
               BCOPY(GC_ext_descriptors, newExtD,
                     GC_avail_descr * sizeof(typed_ext_descr_t));
           }
           GC_ed_size = new_size;
           GC_ext_descriptors = newExtD;
       }  /* else another thread already resized it in the meantime */
   }
   result = GC_avail_descr;
   for (i = 0; i < nwords-1; i++) {
       GC_ext_descriptors[result + i].ed_bitmap = bm[i];
       GC_ext_descriptors[result + i].ed_continued = TRUE;
   }
   last_part = bm[i];
   /* Clear irrelevant bits. */
   extra_bits = nwords * WORDSZ - nbits;
   last_part <<= extra_bits;
   last_part >>= extra_bits;
   GC_ext_descriptors[result + i].ed_bitmap = last_part;
   GC_ext_descriptors[result + i].ed_continued = FALSE;
   GC_avail_descr += nwords;
   UNLOCK();
   return(result);
}

/* Table of bitmap descriptors for n word long all pointer objects.     */
STATIC GC_descr GC_bm_table[WORDSZ/2];

/* Return a descriptor for the concatenation of 2 nwords long objects,  */
/* each of which is described by descriptor.                            */
/* The result is known to be short enough to fit into a bitmap          */
/* descriptor.                                                          */
/* Descriptor is a GC_DS_LENGTH or GC_DS_BITMAP descriptor.             */
STATIC GC_descr GC_double_descr(GC_descr descriptor, word nwords)
{
   if ((descriptor & GC_DS_TAGS) == GC_DS_LENGTH) {
       descriptor = GC_bm_table[BYTES_TO_WORDS((word)descriptor)];
   }
   descriptor |= (descriptor & ~(GC_descr)GC_DS_TAGS) >> nwords;
   return(descriptor);
}

STATIC complex_descriptor *
GC_make_sequence_descriptor(complex_descriptor *first,
                           complex_descriptor *second);

/* Build a descriptor for an array with nelements elements,     */
/* each of which can be described by a simple descriptor.       */
/* We try to optimize some common cases.                        */
/* If the result is COMPLEX, then a complex_descr* is returned  */
/* in *complex_d.                                               */
/* If the result is LEAF, then we built a LeafDescriptor in     */
/* the structure pointed to by leaf.                            */
/* The tag in the leaf structure is not set.                    */
/* If the result is SIMPLE, then a GC_descr                     */
/* is returned in *simple_d.                                    */
/* If the result is NO_MEM, then                                */
/* we failed to allocate the descriptor.                        */
/* The implementation knows that GC_DS_LENGTH is 0.             */
/* *leaf, *complex_d, and *simple_d may be used as temporaries  */
/* during the construction.                                     */
#define COMPLEX 2
#define LEAF    1
#define SIMPLE  0
#define NO_MEM  (-1)
STATIC int GC_make_array_descriptor(size_t nelements, size_t size,
                                   GC_descr descriptor, GC_descr *simple_d,
                                   complex_descriptor **complex_d,
                                   struct LeafDescriptor * leaf)
{
#   define OPT_THRESHOLD 50
       /* For larger arrays, we try to combine descriptors of adjacent */
       /* descriptors to speed up marking, and to reduce the amount    */
       /* of space needed on the mark stack.                           */
   if ((descriptor & GC_DS_TAGS) == GC_DS_LENGTH) {
     if (descriptor == (GC_descr)size) {
       *simple_d = nelements * descriptor; /* no overflow */
       return(SIMPLE);
     } else if ((word)descriptor == 0) {
       *simple_d = (GC_descr)0;
       return(SIMPLE);
     }
   }
   if (nelements <= OPT_THRESHOLD) {
     if (nelements <= 1) {
       if (nelements == 1) {
           *simple_d = descriptor;
           return(SIMPLE);
       } else {
           *simple_d = (GC_descr)0;
           return(SIMPLE);
       }
     }
   } else if (size <= BITMAP_BITS/2
              && (descriptor & GC_DS_TAGS) != GC_DS_PROC
              && (size & (sizeof(word)-1)) == 0) {
     int result =
         GC_make_array_descriptor(nelements/2, 2*size,
                                  GC_double_descr(descriptor,
                                                  BYTES_TO_WORDS(size)),
                                  simple_d, complex_d, leaf);
     if ((nelements & 1) == 0) {
         return(result);
     } else {
         struct LeafDescriptor * one_element =
             (struct LeafDescriptor *)
               GC_malloc_atomic(sizeof(struct LeafDescriptor));

         if (result == NO_MEM || one_element == 0) return(NO_MEM);
         one_element -> ld_tag = LEAF_TAG;
         one_element -> ld_size = size;
         one_element -> ld_nelements = 1;
         one_element -> ld_descriptor = descriptor;
         switch(result) {
           case SIMPLE:
           {
             struct LeafDescriptor * beginning =
               (struct LeafDescriptor *)
                 GC_malloc_atomic(sizeof(struct LeafDescriptor));
             if (beginning == 0) return(NO_MEM);
             beginning -> ld_tag = LEAF_TAG;
             beginning -> ld_size = size;
             beginning -> ld_nelements = 1;
             beginning -> ld_descriptor = *simple_d;
             *complex_d = GC_make_sequence_descriptor(
                               (complex_descriptor *)beginning,
                               (complex_descriptor *)one_element);
             break;
           }
           case LEAF:
           {
             struct LeafDescriptor * beginning =
               (struct LeafDescriptor *)
                 GC_malloc_atomic(sizeof(struct LeafDescriptor));
             if (beginning == 0) return(NO_MEM);
             beginning -> ld_tag = LEAF_TAG;
             beginning -> ld_size = leaf -> ld_size;
             beginning -> ld_nelements = leaf -> ld_nelements;
             beginning -> ld_descriptor = leaf -> ld_descriptor;
             *complex_d = GC_make_sequence_descriptor(
                               (complex_descriptor *)beginning,
                               (complex_descriptor *)one_element);
             break;
           }
           case COMPLEX:
             *complex_d = GC_make_sequence_descriptor(
                               *complex_d,
                               (complex_descriptor *)one_element);
             break;
         }
         if (EXPECT(NULL == *complex_d, FALSE)) return NO_MEM;

         return(COMPLEX);
     }
   }

   leaf -> ld_size = size;
   leaf -> ld_nelements = nelements;
   leaf -> ld_descriptor = descriptor;
   return(LEAF);
}

STATIC complex_descriptor *
GC_make_sequence_descriptor(complex_descriptor *first,
                           complex_descriptor *second)
{
   struct SequenceDescriptor * result =
       (struct SequenceDescriptor *)
               GC_malloc(sizeof(struct SequenceDescriptor));
   /* Can't result in overly conservative marking, since tags are      */
   /* very small integers. Probably faster than maintaining type       */
   /* info.                                                            */
   if (result != 0) {
       result -> sd_tag = SEQUENCE_TAG;
       result -> sd_first = first;
       result -> sd_second = second;
       GC_dirty(result);
       REACHABLE_AFTER_DIRTY(first);
       REACHABLE_AFTER_DIRTY(second);
   }
   return((complex_descriptor *)result);
}

STATIC mse * GC_typed_mark_proc(word * addr, mse * mark_stack_ptr,
                               mse * mark_stack_limit, word env);

STATIC mse * GC_array_mark_proc(word * addr, mse * mark_stack_ptr,
                               mse * mark_stack_limit, word env);

STATIC void GC_init_explicit_typing(void)
{
   unsigned i;

   GC_STATIC_ASSERT(sizeof(struct LeafDescriptor) % sizeof(word) == 0);
   /* Set up object kind with simple indirect descriptor. */
     GC_explicit_kind = GC_new_kind_inner(GC_new_free_list_inner(),
                           (WORDS_TO_BYTES((word)-1) | GC_DS_PER_OBJECT),
                           TRUE, TRUE);
               /* Descriptors are in the last word of the object. */
     GC_typed_mark_proc_index = GC_new_proc_inner(GC_typed_mark_proc);
   /* Set up object kind with array descriptor. */
     GC_array_mark_proc_index = GC_new_proc_inner(GC_array_mark_proc);
     GC_array_kind = GC_new_kind_inner(GC_new_free_list_inner(),
                           GC_MAKE_PROC(GC_array_mark_proc_index, 0),
                           FALSE, TRUE);
     GC_bm_table[0] = GC_DS_BITMAP;
     for (i = 1; i < WORDSZ/2; i++) {
         GC_bm_table[i] = (((word)-1) << (WORDSZ - i)) | GC_DS_BITMAP;
     }
}

STATIC mse * GC_typed_mark_proc(word * addr, mse * mark_stack_ptr,
                               mse * mark_stack_limit, word env)
{
   word bm = GC_ext_descriptors[env].ed_bitmap;
   word * current_p = addr;
   word current;
   ptr_t greatest_ha = (ptr_t)GC_greatest_plausible_heap_addr;
   ptr_t least_ha = (ptr_t)GC_least_plausible_heap_addr;
   DECLARE_HDR_CACHE;

   INIT_HDR_CACHE;
   for (; bm != 0; bm >>= 1, current_p++) {
       if (bm & 1) {
           current = *current_p;
           FIXUP_POINTER(current);
           if (current >= (word)least_ha && current <= (word)greatest_ha) {
               PUSH_CONTENTS((ptr_t)current, mark_stack_ptr,
                             mark_stack_limit, (ptr_t)current_p);
           }
       }
   }
   if (GC_ext_descriptors[env].ed_continued) {
       /* Push an entry with the rest of the descriptor back onto the  */
       /* stack.  Thus we never do too much work at once.  Note that   */
       /* we also can't overflow the mark stack unless we actually     */
       /* mark something.                                              */
       mark_stack_ptr++;
       if ((word)mark_stack_ptr >= (word)mark_stack_limit) {
           mark_stack_ptr = GC_signal_mark_stack_overflow(mark_stack_ptr);
       }
       mark_stack_ptr -> mse_start = (ptr_t)(addr + WORDSZ);
       mark_stack_ptr -> mse_descr.w =
                       GC_MAKE_PROC(GC_typed_mark_proc_index, env + 1);
   }
   return(mark_stack_ptr);
}

/* Return the size of the object described by d.  It would be faster to */
/* store this directly, or to compute it as part of                     */
/* GC_push_complex_descriptor, but hopefully it doesn't matter.         */
STATIC word GC_descr_obj_size(complex_descriptor *d)
{
   switch(d -> TAG) {
     case LEAF_TAG:
       return(d -> ld.ld_nelements * d -> ld.ld_size);
     case ARRAY_TAG:
       return(d -> ad.ad_nelements
              * GC_descr_obj_size(d -> ad.ad_element_descr));
     case SEQUENCE_TAG:
       return(GC_descr_obj_size(d -> sd.sd_first)
              + GC_descr_obj_size(d -> sd.sd_second));
     default:
       ABORT_RET("Bad complex descriptor");
       return 0;
   }
}

/* Push descriptors for the object at addr with complex descriptor d    */
/* onto the mark stack.  Return 0 if the mark stack overflowed.         */
STATIC mse * GC_push_complex_descriptor(word *addr, complex_descriptor *d,
                                       mse *msp, mse *msl)
{
   ptr_t current = (ptr_t)addr;
   word nelements;
   word sz;
   word i;

   switch(d -> TAG) {
     case LEAF_TAG:
       {
         GC_descr descr = d -> ld.ld_descriptor;

         nelements = d -> ld.ld_nelements;
         if (msl - msp <= (ptrdiff_t)nelements) return(0);
         sz = d -> ld.ld_size;
         for (i = 0; i < nelements; i++) {
             msp++;
             msp -> mse_start = current;
             msp -> mse_descr.w = descr;
             current += sz;
         }
         return(msp);
       }
     case ARRAY_TAG:
       {
         complex_descriptor *descr = d -> ad.ad_element_descr;

         nelements = d -> ad.ad_nelements;
         sz = GC_descr_obj_size(descr);
         for (i = 0; i < nelements; i++) {
             msp = GC_push_complex_descriptor((word *)current, descr,
                                               msp, msl);
             if (msp == 0) return(0);
             current += sz;
         }
         return(msp);
       }
     case SEQUENCE_TAG:
       {
         sz = GC_descr_obj_size(d -> sd.sd_first);
         msp = GC_push_complex_descriptor((word *)current, d -> sd.sd_first,
                                          msp, msl);
         if (msp == 0) return(0);
         current += sz;
         msp = GC_push_complex_descriptor((word *)current, d -> sd.sd_second,
                                          msp, msl);
         return(msp);
       }
     default:
       ABORT_RET("Bad complex descriptor");
       return 0;
  }
}

GC_ATTR_NO_SANITIZE_THREAD
static complex_descriptor *get_complex_descr(word *addr, word nwords)
{
 return (complex_descriptor *)addr[nwords - 1];
}

#ifdef AO_HAVE_store_release
# define set_obj_descr(op, nwords, d) \
       AO_store_release((volatile AO_t *)(op) + (nwords) - 1, (AO_t)(d))
#else
# define set_obj_descr(op, nwords, d) \
       (void)(((word *)(op))[(nwords) - 1] = (word)(d))
#endif

STATIC mse * GC_array_mark_proc(word * addr, mse * mark_stack_ptr,
                               mse * mark_stack_limit,
                               word env GC_ATTR_UNUSED)
{
   hdr * hhdr = HDR(addr);
   word sz = hhdr -> hb_sz;
   word nwords = BYTES_TO_WORDS(sz);
   complex_descriptor *descr = get_complex_descr(addr, nwords);
   mse * orig_mark_stack_ptr = mark_stack_ptr;
   mse * new_mark_stack_ptr;

   if (descr == 0) {
       /* Found a reference to a free list entry.  Ignore it. */
       return(orig_mark_stack_ptr);
   }
   /* In use counts were already updated when array descriptor was     */
   /* pushed.  Here we only replace it by subobject descriptors, so    */
   /* no update is necessary.                                          */
   new_mark_stack_ptr = GC_push_complex_descriptor(addr, descr,
                                                   mark_stack_ptr,
                                                   mark_stack_limit-1);
   if (new_mark_stack_ptr == 0) {
       /* Explicitly instruct Clang Static Analyzer that ptr is non-null. */
       if (NULL == mark_stack_ptr) ABORT("Bad mark_stack_ptr");

       /* Doesn't fit.  Conservatively push the whole array as a unit  */
       /* and request a mark stack expansion.                          */
       /* This cannot cause a mark stack overflow, since it replaces   */
       /* the original array entry.                                    */
#       ifdef PARALLEL_MARK
           /* We might be using a local_mark_stack in parallel mode.   */
           if (GC_mark_stack + GC_mark_stack_size == mark_stack_limit)
#       endif
       {
           GC_mark_stack_too_small = TRUE;
       }
       new_mark_stack_ptr = orig_mark_stack_ptr + 1;
       new_mark_stack_ptr -> mse_start = (ptr_t)addr;
       new_mark_stack_ptr -> mse_descr.w = sz | GC_DS_LENGTH;
   } else {
       /* Push descriptor itself */
       new_mark_stack_ptr++;
       new_mark_stack_ptr -> mse_start = (ptr_t)(addr + nwords - 1);
       new_mark_stack_ptr -> mse_descr.w = sizeof(word) | GC_DS_LENGTH;
   }
   return new_mark_stack_ptr;
}

GC_API GC_descr GC_CALL GC_make_descriptor(const GC_word * bm, size_t len)
{
   signed_word last_set_bit = (signed_word)len - 1;
   GC_descr result;
   DCL_LOCK_STATE;

#   if defined(AO_HAVE_load_acquire) && defined(AO_HAVE_store_release)
     if (!EXPECT(AO_load_acquire(&GC_explicit_typing_initialized), TRUE)) {
       LOCK();
       if (!GC_explicit_typing_initialized) {
         GC_init_explicit_typing();
         AO_store_release(&GC_explicit_typing_initialized, TRUE);
       }
       UNLOCK();
     }
#   else
     LOCK();
     if (!EXPECT(GC_explicit_typing_initialized, TRUE)) {
       GC_init_explicit_typing();
       GC_explicit_typing_initialized = TRUE;
     }
     UNLOCK();
#   endif

   while (last_set_bit >= 0 && !GC_get_bit(bm, last_set_bit))
     last_set_bit--;
   if (last_set_bit < 0) return(0 /* no pointers */);

#   if ALIGNMENT == CPP_WORDSZ/8
   {
     signed_word i;

     for (i = 0; i < last_set_bit; i++) {
       if (!GC_get_bit(bm, i)) {
         break;
       }
     }
     if (i == last_set_bit) {
       /* An initial section contains all pointers.  Use length descriptor. */
       return (WORDS_TO_BYTES(last_set_bit+1) | GC_DS_LENGTH);
     }
   }
#   endif
   if ((word)last_set_bit < BITMAP_BITS) {
       signed_word i;

       /* Hopefully the common case.                   */
       /* Build bitmap descriptor (with bits reversed) */
       result = SIGNB;
       for (i = last_set_bit - 1; i >= 0; i--) {
           result >>= 1;
           if (GC_get_bit(bm, i)) result |= SIGNB;
       }
       result |= GC_DS_BITMAP;
   } else {
       signed_word index = GC_add_ext_descriptor(bm, (word)last_set_bit + 1);
       if (index == -1) return(WORDS_TO_BYTES(last_set_bit+1) | GC_DS_LENGTH);
                               /* Out of memory: use conservative      */
                               /* approximation.                       */
       result = GC_MAKE_PROC(GC_typed_mark_proc_index, index);
   }
   return result;
}

GC_API GC_ATTR_MALLOC void * GC_CALL GC_malloc_explicitly_typed(size_t lb,
                                                               GC_descr d)
{
   word *op;
   size_t lg;

   GC_ASSERT(GC_explicit_typing_initialized);
   if (EXPECT(0 == lb, FALSE)) lb = 1; /* ensure nwords > 1 */
   lb = SIZET_SAT_ADD(lb, TYPD_EXTRA_BYTES);
   op = (word *)GC_malloc_kind(lb, GC_explicit_kind);
   if (EXPECT(NULL == op, FALSE))
       return NULL;
   /* It is not safe to use GC_size_map[lb] to compute lg here as      */
   /* the former might be updated asynchronously.                      */
   lg = BYTES_TO_GRANULES(GC_size(op));
   set_obj_descr(op, GRANULES_TO_WORDS(lg), d);
   return op;
}

/* We make the GC_clear_stack() call a tail one, hoping to get more of  */
/* the stack.                                                           */
#define GENERAL_MALLOC_IOP(lb, k) \
               GC_clear_stack(GC_generic_malloc_ignore_off_page(lb, k))

GC_API GC_ATTR_MALLOC void * GC_CALL
   GC_malloc_explicitly_typed_ignore_off_page(size_t lb, GC_descr d)
{
   ptr_t op;
   size_t lg;
   DCL_LOCK_STATE;

   GC_ASSERT(GC_explicit_typing_initialized);
   if (EXPECT(0 == lb, FALSE)) lb = 1;
   lb = SIZET_SAT_ADD(lb, TYPD_EXTRA_BYTES);
   if (SMALL_OBJ(lb)) {
       void **opp;

       GC_DBG_COLLECT_AT_MALLOC(lb);
       LOCK();
       lg = GC_size_map[lb];
       opp = &GC_obj_kinds[GC_explicit_kind].ok_freelist[lg];
       op = (ptr_t)(*opp);
       if (EXPECT(0 == op, FALSE)) {
           UNLOCK();
           op = (ptr_t)GENERAL_MALLOC_IOP(lb, GC_explicit_kind);
           if (0 == op) return 0;
           /* See the comment in GC_malloc_explicitly_typed.   */
           lg = BYTES_TO_GRANULES(GC_size(op));
       } else {
           *opp = obj_link(op);
           obj_link(op) = 0;
           GC_bytes_allocd += GRANULES_TO_BYTES((word)lg);
           UNLOCK();
       }
   } else {
       op = (ptr_t)GENERAL_MALLOC_IOP(lb, GC_explicit_kind);
       if (NULL == op) return NULL;
       lg = BYTES_TO_GRANULES(GC_size(op));
   }
   set_obj_descr(op, GRANULES_TO_WORDS(lg), d);
   return op;
}

GC_API GC_ATTR_MALLOC void * GC_CALL GC_calloc_explicitly_typed(size_t n,
                                                       size_t lb, GC_descr d)
{
   word *op;
   size_t lg;
   GC_descr simple_descr;
   complex_descriptor *complex_descr;
   int descr_type;
   struct LeafDescriptor leaf;
   DCL_LOCK_STATE;

   GC_ASSERT(GC_explicit_typing_initialized);
   if (EXPECT(0 == lb || 0 == n, FALSE)) lb = n = 1;
   if ((lb | n) > GC_SQRT_SIZE_MAX /* fast initial check */
       && n > GC_SIZE_MAX / lb)
     return (*GC_get_oom_fn())(GC_SIZE_MAX); /* n*lb overflow */

   descr_type = GC_make_array_descriptor((word)n, (word)lb, d, &simple_descr,
                                         &complex_descr, &leaf);
   lb *= n;
   switch(descr_type) {
       case NO_MEM:
           return (*GC_get_oom_fn())(lb);
       case SIMPLE:
           return GC_malloc_explicitly_typed(lb, simple_descr);
       case LEAF:
           lb = SIZET_SAT_ADD(lb,
                       sizeof(struct LeafDescriptor) + TYPD_EXTRA_BYTES);
           break;
       case COMPLEX:
           lb = SIZET_SAT_ADD(lb, TYPD_EXTRA_BYTES);
           break;
   }
   op = (word *)GC_malloc_kind(lb, GC_array_kind);
   if (EXPECT(NULL == op, FALSE))
       return NULL;
   lg = BYTES_TO_GRANULES(GC_size(op));
   if (descr_type == LEAF) {
       /* Set up the descriptor inside the object itself.      */
       struct LeafDescriptor * lp =
           (struct LeafDescriptor *)
               (op + GRANULES_TO_WORDS(lg)
                   - (BYTES_TO_WORDS(sizeof(struct LeafDescriptor)) + 1));

       lp -> ld_tag = LEAF_TAG;
       lp -> ld_size = leaf.ld_size;
       lp -> ld_nelements = leaf.ld_nelements;
       lp -> ld_descriptor = leaf.ld_descriptor;
       /* Hold the allocation lock while writing the descriptor word   */
       /* to the object to ensure that the descriptor contents are     */
       /* seen by GC_array_mark_proc as expected.                      */
       /* TODO: It should be possible to replace locking with the      */
       /* atomic operations (with the release barrier here) but, in    */
       /* this case, avoiding the acquire barrier in                   */
       /* GC_array_mark_proc seems to be tricky as GC_mark_some might  */
       /* be invoked with the world running.                           */
       LOCK();
       op[GRANULES_TO_WORDS(lg) - 1] = (word)lp;
       UNLOCK();
   } else {
#     ifndef GC_NO_FINALIZATION
       size_t lw = GRANULES_TO_WORDS(lg);

       LOCK();
       op[lw - 1] = (word)complex_descr;
       UNLOCK();

       GC_dirty(op + lw - 1);
       REACHABLE_AFTER_DIRTY(complex_descr);

       /* Make sure the descriptor is cleared once there is any danger */
       /* it may have been collected.                                  */
       if (EXPECT(GC_general_register_disappearing_link(
                                               (void **)(op + lw - 1), op)
                 == GC_NO_MEMORY, FALSE))
#     endif
       {
           /* Couldn't register it due to lack of memory.  Punt.       */
           return (*GC_get_oom_fn())(lb);
       }
   }
   return op;
}

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