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| -rw-r--r-- | gc/include/private/gc_pmark.h | 388 |
1 files changed, 388 insertions, 0 deletions
diff --git a/gc/include/private/gc_pmark.h b/gc/include/private/gc_pmark.h new file mode 100644 index 0000000..cf70706 --- /dev/null +++ b/gc/include/private/gc_pmark.h @@ -0,0 +1,388 @@ +/* + * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved. + * Copyright (c) 2001 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. + * + */ + +/* Private declarations of GC marker data structures and macros */ + +/* + * Declarations of mark stack. Needed by marker and client supplied mark + * routines. Transitively include gc_priv.h. + * (Note that gc_priv.h should not be included before this, since this + * includes dbg_mlc.h, which wants to include gc_priv.h AFTER defining + * I_HIDE_POINTERS.) + */ +#ifndef GC_PMARK_H +# define GC_PMARK_H + +# if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST) +# include "dbg_mlc.h" +# endif +# ifndef GC_MARK_H +# include "../gc_mark.h" +# endif +# ifndef GC_PRIVATE_H +# include "gc_priv.h" +# endif + +/* The real declarations of the following is in gc_priv.h, so that */ +/* we can avoid scanning the following table. */ +/* +extern mark_proc GC_mark_procs[MAX_MARK_PROCS]; +*/ + +/* + * Mark descriptor stuff that should remain private for now, mostly + * because it's hard to export WORDSZ without including gcconfig.h. + */ +# define BITMAP_BITS (WORDSZ - GC_DS_TAG_BITS) +# define PROC(descr) \ + (GC_mark_procs[((descr) >> GC_DS_TAG_BITS) & (GC_MAX_MARK_PROCS-1)]) +# define ENV(descr) \ + ((descr) >> (GC_DS_TAG_BITS + GC_LOG_MAX_MARK_PROCS)) +# define MAX_ENV \ + (((word)1 << (WORDSZ - GC_DS_TAG_BITS - GC_LOG_MAX_MARK_PROCS)) - 1) + + +extern word GC_n_mark_procs; + +/* Number of mark stack entries to discard on overflow. */ +#define GC_MARK_STACK_DISCARDS (INITIAL_MARK_STACK_SIZE/8) + +typedef struct GC_ms_entry { + GC_word * mse_start; /* First word of object */ + GC_word mse_descr; /* Descriptor; low order two bits are tags, */ + /* identifying the upper 30 bits as one of the */ + /* following: */ +} mse; + +extern word GC_mark_stack_size; + +extern mse * GC_mark_stack_limit; + +#ifdef PARALLEL_MARK + extern mse * VOLATILE GC_mark_stack_top; +#else + extern mse * GC_mark_stack_top; +#endif + +extern mse * GC_mark_stack; + +#ifdef PARALLEL_MARK + /* + * Allow multiple threads to participate in the marking process. + * This works roughly as follows: + * The main mark stack never shrinks, but it can grow. + * + * The initiating threads holds the GC lock, and sets GC_help_wanted. + * + * Other threads: + * 1) update helper_count (while holding mark_lock.) + * 2) allocate a local mark stack + * repeatedly: + * 3) Steal a global mark stack entry by atomically replacing + * its descriptor with 0. + * 4) Copy it to the local stack. + * 5) Mark on the local stack until it is empty, or + * it may be profitable to copy it back. + * 6) If necessary, copy local stack to global one, + * holding mark lock. + * 7) Stop when the global mark stack is empty. + * 8) decrement helper_count (holding mark_lock). + * + * This is an experiment to see if we can do something along the lines + * of the University of Tokyo SGC in a less intrusive, though probably + * also less performant, way. + */ + void GC_do_parallel_mark(); + /* inititate parallel marking. */ + + extern GC_bool GC_help_wanted; /* Protected by mark lock */ + extern unsigned GC_helper_count; /* Number of running helpers. */ + /* Protected by mark lock */ + extern unsigned GC_active_count; /* Number of active helpers. */ + /* Protected by mark lock */ + /* May increase and decrease */ + /* within each mark cycle. But */ + /* once it returns to 0, it */ + /* stays zero for the cycle. */ + /* GC_mark_stack_top is also protected by mark lock. */ + extern mse * VOLATILE GC_first_nonempty; + /* Lowest entry on mark stack */ + /* that may be nonempty. */ + /* Updated only by initiating */ + /* thread. */ + /* + * GC_notify_all_marker() is used when GC_help_wanted is first set, + * when the last helper becomes inactive, + * when something is added to the global mark stack, and just after + * GC_mark_no is incremented. + * This could be split into multiple CVs (and probably should be to + * scale to really large numbers of processors.) + */ +#endif /* PARALLEL_MARK */ + +/* Return a pointer to within 1st page of object. */ +/* Set *new_hdr_p to corr. hdr. */ +#ifdef __STDC__ +# ifdef PRINT_BLACK_LIST + ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p, word source); +# else + ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p); +# endif +#else + ptr_t GC_find_start(); +#endif + +mse * GC_signal_mark_stack_overflow(); + +# ifdef GATHERSTATS +# define ADD_TO_ATOMIC(sz) GC_atomic_in_use += (sz) +# define ADD_TO_COMPOSITE(sz) GC_composite_in_use += (sz) +# else +# define ADD_TO_ATOMIC(sz) +# define ADD_TO_COMPOSITE(sz) +# endif + +/* Push the object obj with corresponding heap block header hhdr onto */ +/* the mark stack. */ +# define PUSH_OBJ(obj, hhdr, mark_stack_top, mark_stack_limit) \ +{ \ + register word _descr = (hhdr) -> hb_descr; \ + \ + if (_descr == 0) { \ + ADD_TO_ATOMIC((hhdr) -> hb_sz); \ + } else { \ + ADD_TO_COMPOSITE((hhdr) -> hb_sz); \ + mark_stack_top++; \ + if (mark_stack_top >= mark_stack_limit) { \ + mark_stack_top = GC_signal_mark_stack_overflow(mark_stack_top); \ + } \ + mark_stack_top -> mse_start = (obj); \ + mark_stack_top -> mse_descr = _descr; \ + } \ +} + +#ifdef PRINT_BLACK_LIST +# define GC_FIND_START(current, hhdr, new_hdr_p, source) \ + GC_find_start(current, hhdr, new_hdr_p, source) +#else +# define GC_FIND_START(current, hhdr, new_hdr_p, source) \ + GC_find_start(current, hhdr, new_hdr_p) +#endif + +/* Push the contents of current onto the mark stack if it is a valid */ +/* ptr to a currently unmarked object. Mark it. */ +/* If we assumed a standard-conforming compiler, we could probably */ +/* generate the exit_label transparently. */ +# define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \ + source, exit_label) \ +{ \ + hdr * my_hhdr; \ + ptr_t my_current = current; \ + \ + GET_HDR(my_current, my_hhdr); \ + if (IS_FORWARDING_ADDR_OR_NIL(my_hhdr)) { \ + hdr * new_hdr = GC_invalid_header; \ + my_current = GC_FIND_START(my_current, my_hhdr, \ + &new_hdr, (word)source); \ + my_hhdr = new_hdr; \ + } \ + PUSH_CONTENTS_HDR(my_current, mark_stack_top, mark_stack_limit, \ + source, exit_label, my_hhdr); \ +exit_label: ; \ +} + +/* As above, but use header cache for header lookup. */ +# define HC_PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \ + source, exit_label) \ +{ \ + hdr * my_hhdr; \ + ptr_t my_current = current; \ + \ + HC_GET_HDR(my_current, my_hhdr, source); \ + PUSH_CONTENTS_HDR(my_current, mark_stack_top, mark_stack_limit, \ + source, exit_label, my_hhdr); \ +exit_label: ; \ +} + +/* Set mark bit, exit if it was already set. */ + +# ifdef USE_MARK_BYTES + /* Unlike the mark bit case, there is a race here, and we may set */ + /* the bit twice in the concurrent case. This can result in the */ + /* object being pushed twice. But that's only a performance issue. */ +# define SET_MARK_BIT_EXIT_IF_SET(hhdr,displ,exit_label) \ + { \ + register VOLATILE char * mark_byte_addr = \ + hhdr -> hb_marks + ((displ) >> 1); \ + register char mark_byte = *mark_byte_addr; \ + \ + if (mark_byte) goto exit_label; \ + *mark_byte_addr = 1; \ + } +# else +# define SET_MARK_BIT_EXIT_IF_SET(hhdr,displ,exit_label) \ + { \ + register word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(displ); \ + register word mark_word = *mark_word_addr; \ + \ + OR_WORD_EXIT_IF_SET(mark_word_addr, (word)1 << modWORDSZ(displ), \ + exit_label); \ + } +# endif /* USE_MARK_BYTES */ + +/* If the mark bit corresponding to current is not set, set it, and */ +/* push the contents of the object on the mark stack. For a small */ +/* object we assume that current is the (possibly interior) pointer */ +/* to the object. For large objects we assume that current points */ +/* to somewhere inside the first page of the object. If */ +/* GC_all_interior_pointers is set, it may have been previously */ +/* adjusted to make that true. */ +# define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \ + source, exit_label, hhdr) \ +{ \ + int displ; /* Displacement in block; first bytes, then words */ \ + int map_entry; \ + \ + displ = HBLKDISPL(current); \ + map_entry = MAP_ENTRY((hhdr -> hb_map), displ); \ + displ = BYTES_TO_WORDS(displ); \ + if (map_entry > CPP_MAX_OFFSET) { \ + if (map_entry == OFFSET_TOO_BIG) { \ + map_entry = displ % (hhdr -> hb_sz); \ + displ -= map_entry; \ + if (displ + (hhdr -> hb_sz) > BYTES_TO_WORDS(HBLKSIZE)) { \ + GC_ADD_TO_BLACK_LIST_NORMAL((word)current, source); \ + goto exit_label; \ + } \ + } else { \ + GC_ADD_TO_BLACK_LIST_NORMAL((word)current, source); goto exit_label; \ + } \ + } else { \ + displ -= map_entry; \ + } \ + GC_ASSERT(displ >= 0 && displ < MARK_BITS_PER_HBLK); \ + SET_MARK_BIT_EXIT_IF_SET(hhdr, displ, exit_label); \ + GC_STORE_BACK_PTR((ptr_t)source, (ptr_t)HBLKPTR(current) \ + + WORDS_TO_BYTES(displ)); \ + PUSH_OBJ(((word *)(HBLKPTR(current)) + displ), hhdr, \ + mark_stack_top, mark_stack_limit) \ +} + +#if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS) +# define PUSH_ONE_CHECKED_STACK(p, source) \ + GC_mark_and_push_stack(p, (ptr_t)(source)) +#else +# define PUSH_ONE_CHECKED_STACK(p, source) \ + GC_mark_and_push_stack(p) +#endif + +/* + * Push a single value onto mark stack. Mark from the object pointed to by p. + * P is considered valid even if it is an interior pointer. + * Previously marked objects are not pushed. Hence we make progress even + * if the mark stack overflows. + */ +# define GC_PUSH_ONE_STACK(p, source) \ + if ((ptr_t)(p) >= (ptr_t)GC_least_plausible_heap_addr \ + && (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) { \ + PUSH_ONE_CHECKED_STACK(p, source); \ + } + +/* + * As above, but interior pointer recognition as for + * normal for heap pointers. + */ +# define GC_PUSH_ONE_HEAP(p,source) \ + if ((ptr_t)(p) >= (ptr_t)GC_least_plausible_heap_addr \ + && (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) { \ + GC_mark_stack_top = GC_mark_and_push( \ + (GC_PTR)(p), GC_mark_stack_top, \ + GC_mark_stack_limit, (GC_PTR *)(source)); \ + } + +/* Mark starting at mark stack entry top (incl.) down to */ +/* mark stack entry bottom (incl.). Stop after performing */ +/* about one page worth of work. Return the new mark stack */ +/* top entry. */ +mse * GC_mark_from GC_PROTO((mse * top, mse * bottom, mse *limit)); + +#define MARK_FROM_MARK_STACK() \ + GC_mark_stack_top = GC_mark_from(GC_mark_stack_top, \ + GC_mark_stack, \ + GC_mark_stack + GC_mark_stack_size); + +/* + * Mark from one finalizable object using the specified + * mark proc. May not mark the object pointed to by + * real_ptr. That is the job of the caller, if appropriate + */ +# define GC_MARK_FO(real_ptr, mark_proc) \ +{ \ + (*(mark_proc))(real_ptr); \ + while (!GC_mark_stack_empty()) MARK_FROM_MARK_STACK(); \ + if (GC_mark_state != MS_NONE) { \ + GC_set_mark_bit(real_ptr); \ + while (!GC_mark_some((ptr_t)0)) {} \ + } \ +} + +extern GC_bool GC_mark_stack_too_small; + /* We need a larger mark stack. May be */ + /* set by client supplied mark routines.*/ + +typedef int mark_state_t; /* Current state of marking, as follows:*/ + /* Used to remember where we are during */ + /* concurrent marking. */ + + /* We say something is dirty if it was */ + /* written since the last time we */ + /* retrieved dirty bits. We say it's */ + /* grungy if it was marked dirty in the */ + /* last set of bits we retrieved. */ + + /* Invariant I: all roots and marked */ + /* objects p are either dirty, or point */ + /* to objects q that are either marked */ + /* or a pointer to q appears in a range */ + /* on the mark stack. */ + +# define MS_NONE 0 /* No marking in progress. I holds. */ + /* Mark stack is empty. */ + +# define MS_PUSH_RESCUERS 1 /* Rescuing objects are currently */ + /* being pushed. I holds, except */ + /* that grungy roots may point to */ + /* unmarked objects, as may marked */ + /* grungy objects above scan_ptr. */ + +# define MS_PUSH_UNCOLLECTABLE 2 + /* I holds, except that marked */ + /* uncollectable objects above scan_ptr */ + /* may point to unmarked objects. */ + /* Roots may point to unmarked objects */ + +# define MS_ROOTS_PUSHED 3 /* I holds, mark stack may be nonempty */ + +# define MS_PARTIALLY_INVALID 4 /* I may not hold, e.g. because of M.S. */ + /* overflow. However marked heap */ + /* objects below scan_ptr point to */ + /* marked or stacked objects. */ + +# define MS_INVALID 5 /* I may not hold. */ + +extern mark_state_t GC_mark_state; + +#endif /* GC_PMARK_H */ + |