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/*

 * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.

 * opyright (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.

 *

 */

/*

 * 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 refrence 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 "private/gc_pmark.h"

#include "gc_typed.h"

# define TYPD_EXTRA_BYTES (sizeof(word) - EXTRA_BYTES)

GC_bool GC_explicit_typing_initialized = FALSE;

int GC_explicit_kind;   /* Object kind for objects with indirect        */

                        /* (possibly extended) descriptors.             */

int GC_array_kind;      /* Object kind for objects with complex         */

                        /* descriptors and GC_array_mark_proc.          */

/* Extended descriptors.  GC_typed_mark_proc understands these. */

/* These are used for simple objects that are larger than what  */

/* can be described by a BITMAP_BITS sized bitmap.              */

typedef struct {

        word ed_bitmap; /* lsb corresponds to first word.       */

        GC_bool ed_continued;   /* next entry is continuation.  */

} ext_descr;

/* 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.                   */

typedef union ComplexDescriptor {

    struct LeafDescriptor {     /* Describes simple array       */

        word ld_tag;

#       define LEAF_TAG 1

        word ld_size;           /* bytes per element    */

                                /* multiple of ALIGNMENT        */

        word ld_nelements;      /* Number of elements.  */

        GC_descr ld_descriptor; /* A simple length, bitmap,     */

                                /* or procedure descriptor.     */

    } ld;

    struct ComplexArrayDescriptor {

        word ad_tag;

#       define ARRAY_TAG 2

        word ad_nelements;

        union ComplexDescriptor * ad_element_descr;

    } ad;

    struct SequenceDescriptor {

        word sd_tag;

#       define SEQUENCE_TAG 3

        union ComplexDescriptor * sd_first;

        union ComplexDescriptor * sd_second;

    } sd;

} complex_descriptor;

#define TAG ld.ld_tag

ext_descr * GC_ext_descriptors; /* Points to array of extended  */

                                /* descriptors.                 */

word GC_ed_size = 0;     /* Current size of above arrays.        */

# define ED_INITIAL_SIZE 100;

word GC_avail_descr = 0; /* Next available slot.         */

int GC_typed_mark_proc_index;   /* Indices of my mark           */

int GC_array_mark_proc_index;   /* procedures.                  */

/* Add a multiword bitmap to GC_ext_descriptors arrays.  Return */

/* starting index.                                              */

/* Returns -1 on failure.                                       */

/* Caller does not hold allocation lock.                        */

signed_word GC_add_ext_descriptor(bm, nbits)

GC_bitmap bm;

word nbits;

{

    register size_t nwords = divWORDSZ(nbits + WORDSZ-1);

    register signed_word result;

    register word i;

    register word last_part;

    register int extra_bits;

    DCL_LOCK_STATE;

    DISABLE_SIGNALS();

    LOCK();

    while (GC_avail_descr + nwords >= GC_ed_size) {

        ext_descr * new;

        size_t new_size;

        word ed_size = GC_ed_size;

        UNLOCK();

        ENABLE_SIGNALS();

        if (ed_size == 0) {

            new_size = ED_INITIAL_SIZE;

        } else {

            new_size = 2 * ed_size;

            if (new_size > MAX_ENV) return(-1);

        }

        new = (ext_descr *) GC_malloc_atomic(new_size * sizeof(ext_descr));

        if (new == 0) return(-1);

        DISABLE_SIGNALS();

        LOCK();

        if (ed_size == GC_ed_size) {

            if (GC_avail_descr != 0) {

                BCOPY(GC_ext_descriptors, new,

                      GC_avail_descr * sizeof(ext_descr));

            }

            GC_ed_size = new_size;

            GC_ext_descriptors = new;

        }  /* 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();

    ENABLE_SIGNALS();

    return(result);

}

/* Table of bitmap descriptors for n word long all pointer objects.     */

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.             */

GC_descr GC_double_descr(descriptor, nwords)

register GC_descr descriptor;

register word nwords;

{

    if ((descriptor & GC_DS_TAGS) == GC_DS_LENGTH) {

        descriptor = GC_bm_table[BYTES_TO_WORDS((word)descriptor)];

    };

    descriptor |= (descriptor & ~GC_DS_TAGS) >> nwords;

    return(descriptor);

}

complex_descriptor * GC_make_sequence_descriptor();

/* 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)

int GC_make_array_descriptor(nelements, size, descriptor,

                             simple_d, complex_d, leaf)

word size;

word nelements;

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 ((word)descriptor == size) {

        *simple_d = nelements * descriptor;

        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;

          }

          return(COMPLEX);

      }

    }

    {

        leaf -> ld_size = size;

        leaf -> ld_nelements = nelements;

        leaf -> ld_descriptor = descriptor;

        return(LEAF);

    }

}

complex_descriptor * GC_make_sequence_descriptor(first, second)

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;

    }

    return((complex_descriptor *)result);

}

#ifdef UNDEFINED

complex_descriptor * GC_make_complex_array_descriptor(nelements, descr)

word nelements;

complex_descriptor * descr;

{

    struct ComplexArrayDescriptor * result =

        (struct ComplexArrayDescriptor *)

                GC_malloc(sizeof(struct ComplexArrayDescriptor));

    if (result != 0) {

        result -> ad_tag = ARRAY_TAG;

        result -> ad_nelements = nelements;

        result -> ad_element_descr = descr;

    }

    return((complex_descriptor *)result);

}

#endif

ptr_t * GC_eobjfreelist;

ptr_t * GC_arobjfreelist;

mse * GC_typed_mark_proc GC_PROTO((register word * addr,

                                   register mse * mark_stack_ptr,

                                   mse * mark_stack_limit,

                                   word env));

mse * GC_array_mark_proc GC_PROTO((register word * addr,

                                   register mse * mark_stack_ptr,

                                   mse * mark_stack_limit,

                                   word env));

/* Caller does not hold allocation lock. */

void GC_init_explicit_typing()

{

    register int i;

    DCL_LOCK_STATE;

#   ifdef PRINTSTATS

        if (sizeof(struct LeafDescriptor) % sizeof(word) != 0)

            ABORT("Bad leaf descriptor size");

#   endif

    DISABLE_SIGNALS();

    LOCK();

    if (GC_explicit_typing_initialized) {

      UNLOCK();

      ENABLE_SIGNALS();

      return;

    }

    GC_explicit_typing_initialized = TRUE;

    /* Set up object kind with simple indirect descriptor. */

      GC_eobjfreelist = (ptr_t *)GC_new_free_list_inner();

      GC_explicit_kind = GC_new_kind_inner(

                            (void **)GC_eobjfreelist,

                            (((word)WORDS_TO_BYTES(-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_arobjfreelist = (ptr_t *)GC_new_free_list_inner();

      GC_array_mark_proc_index = GC_new_proc_inner(GC_array_mark_proc);

      GC_array_kind = GC_new_kind_inner(

                            (void **)GC_arobjfreelist,

                            GC_MAKE_PROC(GC_array_mark_proc_index, 0),

                            FALSE, TRUE);

      for (i = 0; i < WORDSZ/2; i++) {

          GC_descr d = (((word)(-1)) >> (WORDSZ - i)) << (WORDSZ - i);

          d |= GC_DS_BITMAP;

          GC_bm_table[i] = d;

      }

    UNLOCK();

    ENABLE_SIGNALS();

}

# if defined(__STDC__) || defined(__cplusplus)

    mse * GC_typed_mark_proc(register word * addr,

                             register mse * mark_stack_ptr,

                             mse * mark_stack_limit,

                             word env)

# else

    mse * GC_typed_mark_proc(addr, mark_stack_ptr, mark_stack_limit, env)

    register word * addr;

    register mse * mark_stack_ptr;

    mse * mark_stack_limit;

    word env;

# endif

{

    register word bm = GC_ext_descriptors[env].ed_bitmap;

    register word * current_p = addr;

    register word current;

    register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;

    register ptr_t least_ha = GC_least_plausible_heap_addr;

    for (; bm != 0; bm >>= 1, current_p++) {

        if (bm & 1) {

            current = *current_p;

            FIXUP_POINTER(current);

            if ((ptr_t)current >= least_ha && (ptr_t)current <= greatest_ha) {

                PUSH_CONTENTS((ptr_t)current, mark_stack_ptr,

                              mark_stack_limit, current_p, exit1);

            }

        }

    }

    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 (mark_stack_ptr >= mark_stack_limit) {

            mark_stack_ptr = GC_signal_mark_stack_overflow(mark_stack_ptr);

        }

        mark_stack_ptr -> mse_start = addr + WORDSZ;

        mark_stack_ptr -> mse_descr =

                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.         */

word GC_descr_obj_size(d)

register 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("Bad complex descriptor");

        /*NOTREACHED*/ return 0; /*NOTREACHED*/

    }

}

/* Push descriptors for the object at addr with complex descriptor d    */

/* onto the mark stack.  Return 0 if the mark stack overflowed.         */

mse * GC_push_complex_descriptor(addr, d, msp, msl)

word * addr;

register complex_descriptor *d;

register mse * msp;

mse * msl;

{

    register ptr_t current = (ptr_t) addr;

    register word nelements;

    register word sz;

    register word i;

    switch(d -> TAG) {

      case LEAF_TAG:

        {

          register 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 = (word *)current;

              msp -> mse_descr = descr;

              current += sz;

          }

          return(msp);

        }

      case ARRAY_TAG:

        {

          register 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("Bad complex descriptor");

        /*NOTREACHED*/ return 0; /*NOTREACHED*/

   }

}

/*ARGSUSED*/

# if defined(__STDC__) || defined(__cplusplus)

    mse * GC_array_mark_proc(register word * addr,

                             register mse * mark_stack_ptr,

                             mse * mark_stack_limit,

                             word env)

# else

    mse * GC_array_mark_proc(addr, mark_stack_ptr, mark_stack_limit, env)

    register word * addr;

    register mse * mark_stack_ptr;

    mse * mark_stack_limit;

    word env;

# endif

{

    register hdr * hhdr = HDR(addr);

    register word sz = hhdr -> hb_sz;

    register complex_descriptor * descr = (complex_descriptor *)(addr[sz-1]);

    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) {

        /* 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.                                    */

        GC_mark_stack_too_small = TRUE;

        new_mark_stack_ptr = orig_mark_stack_ptr + 1;

        new_mark_stack_ptr -> mse_start = addr;

        new_mark_stack_ptr -> mse_descr = WORDS_TO_BYTES(sz) | GC_DS_LENGTH;

    } else {

        /* Push descriptor itself */

        new_mark_stack_ptr++;

        new_mark_stack_ptr -> mse_start = addr + sz - 1;

        new_mark_stack_ptr -> mse_descr = sizeof(word) | GC_DS_LENGTH;

    }

    return(new_mark_stack_ptr);

}

#if defined(__STDC__) || defined(__cplusplus)

  GC_descr GC_make_descriptor(GC_bitmap bm, size_t len)

#else

  GC_descr GC_make_descriptor(bm, len)

  GC_bitmap bm;

  size_t len;

#endif

{

    register signed_word last_set_bit = len - 1;

    register word result;

    register int i;

#   define HIGH_BIT (((word)1) << (WORDSZ - 1))

    if (!GC_explicit_typing_initialized) GC_init_explicit_typing();

    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

    {

      register GC_bool all_bits_set = TRUE;

      for (i = 0; i < last_set_bit; i++) {

        if (!GC_get_bit(bm, i)) {

            all_bits_set = FALSE;

            break;

        }

      }

      if (all_bits_set) {

        /* An initial section contains all pointers.  Use length descriptor. */

        return(WORDS_TO_BYTES(last_set_bit+1) | GC_DS_LENGTH);

      }

    }

#   endif

    if (last_set_bit < BITMAP_BITS) {

        /* Hopefully the common case.                   */

        /* Build bitmap descriptor (with bits reversed) */

        result = HIGH_BIT;

        for (i = last_set_bit - 1; i >= 0; i--) {

            result >>= 1;

            if (GC_get_bit(bm, i)) result |= HIGH_BIT;

        }

        result |= GC_DS_BITMAP;

        return(result);

    } else {

        signed_word index;

        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, (word)index);

        return(result);

    }

}

ptr_t GC_clear_stack();

#define GENERAL_MALLOC(lb,k) \

    (GC_PTR)GC_clear_stack(GC_generic_malloc((word)lb, k))

#define GENERAL_MALLOC_IOP(lb,k) \

    (GC_PTR)GC_clear_stack(GC_generic_malloc_ignore_off_page(lb, k))

#if defined(__STDC__) || defined(__cplusplus)

  void * GC_malloc_explicitly_typed(size_t lb, GC_descr d)

#else

  char * GC_malloc_explicitly_typed(lb, d)

  size_t lb;

  GC_descr d;

#endif

{

register ptr_t op;

register ptr_t * opp;

register word lw;

DCL_LOCK_STATE;

    lb += TYPD_EXTRA_BYTES;

    if( SMALL_OBJ(lb) ) {

#       ifdef MERGE_SIZES

          lw = GC_size_map[lb];

#       else

          lw = ALIGNED_WORDS(lb);

#       endif

        opp = &(GC_eobjfreelist[lw]);

        FASTLOCK();

        if( !FASTLOCK_SUCCEEDED() || (op = *opp) == 0 ) {

            FASTUNLOCK();

            op = (ptr_t)GENERAL_MALLOC((word)lb, GC_explicit_kind);

            if (0 == op) return 0;

#           ifdef MERGE_SIZES

                lw = GC_size_map[lb];   /* May have been uninitialized. */

#           endif

        } else {

            *opp = obj_link(op);

            obj_link(op) = 0;

            GC_words_allocd += lw;

            FASTUNLOCK();

        }

   } else {

       op = (ptr_t)GENERAL_MALLOC((word)lb, GC_explicit_kind);

       if (op != NULL)

            lw = BYTES_TO_WORDS(GC_size(op));

   }