/* * 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 # include "gc.h" /* For configuration */ # 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__ ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p); #else ptr_t GC_find_start(); #endif mse * GC_signal_mark_stack_overflow GC_PROTO((mse *msp)); # 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; \ } \ } /* 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); \ 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); \ \ 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. * Invoke FIXUP_POINTER(p) before any further processing. * 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. */ # if NEED_FIXUP_POINTER /* Try both the raw version and the fixed up one. */ # 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); \ } \ FIXUP_POINTER(p); \ 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); \ } # else /* !NEED_FIXUP_POINTER */ # 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); \ } # endif /* * As above, but interior pointer recognition as for * normal for heap pointers. */ # define GC_PUSH_ONE_HEAP(p,source) \ FIXUP_POINTER(p); \ 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 */