/* * Copyright (c) 1991-1994, 2000 by Xerox Corporation. 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. * */ /* Boehm, November 7, 1994 4:56 pm PST */ /* * Declarations of mark stack. Needed by marker and client supplied mark * routines. To be included after gc_priv.h. */ #ifndef GC_MARK_H # define GC_MARK_H # ifdef KEEP_BACK_PTRS # include "dbg_mlc.h" # endif /* A client supplied mark procedure. Returns new mark stack pointer. */ /* Primary effect should be to push new entries on the mark stack. */ /* Mark stack pointer values are passed and returned explicitly. */ /* Global variables decribing mark stack are not necessarily valid. */ /* (This usually saves a few cycles by keeping things in registers.) */ /* Assumed to scan about PROC_BYTES on average. If it needs to do */ /* much more work than that, it should do it in smaller pieces by */ /* pushing itself back on the mark stack. */ /* Note that it should always do some work (defined as marking some */ /* objects) before pushing more than one entry on the mark stack. */ /* This is required to ensure termination in the event of mark stack */ /* overflows. */ /* This procedure is always called with at least one empty entry on the */ /* mark stack. */ /* Currently we require that mark procedures look for pointers in a */ /* subset of the places the conservative marker would. It must be safe */ /* to invoke the normal mark procedure instead. */ # define PROC_BYTES 100 /* The real declarations of the following are in gc_priv.h, so that */ /* we can avoid scanning the following table. */ /* typedef struct ms_entry * (*mark_proc)( word * addr, struct ms_entry *mark_stack_ptr, struct ms_entry *mark_stack_limit, word env ); # define LOG_MAX_MARK_PROCS 6 # define MAX_MARK_PROCS (1 << LOG_MAX_MARK_PROCS) extern mark_proc GC_mark_procs[MAX_MARK_PROCS]; */ extern word GC_n_mark_procs; /* In a few cases it's necessary to assign statically known indices to */ /* certain mark procs. Thus we reserve a few for well known clients. */ /* (This is necessary if mark descriptors are compiler generated.) */ #define GC_RESERVED_MARK_PROCS 8 # define GCJ_RESERVED_MARK_PROC_INDEX 0 /* Object descriptors on mark stack or in objects. Low order two */ /* bits are tags distinguishing among the following 4 possibilities */ /* for the high order 30 bits. */ #define DS_TAG_BITS 2 #define DS_TAGS ((1 << DS_TAG_BITS) - 1) #define DS_LENGTH 0 /* The entire word is a length in bytes that */ /* must be a multiple of 4. */ #define DS_BITMAP 1 /* 30 bits are a bitmap describing pointer */ /* fields. The msb is 1 iff the first word */ /* is a pointer. */ /* (This unconventional ordering sometimes */ /* makes the marker slightly faster.) */ /* Zeroes indicate definite nonpointers. Ones */ /* indicate possible pointers. */ /* Only usable if pointers are word aligned. */ # define BITMAP_BITS (WORDSZ - DS_TAG_BITS) #define DS_PROC 2 /* The objects referenced by this object can be */ /* pushed on the mark stack by invoking */ /* PROC(descr). ENV(descr) is passed as the */ /* last argument. */ # define PROC(descr) \ (GC_mark_procs[((descr) >> DS_TAG_BITS) & (MAX_MARK_PROCS-1)]) # define ENV(descr) \ ((descr) >> (DS_TAG_BITS + LOG_MAX_MARK_PROCS)) # define MAX_ENV \ (((word)1 << (WORDSZ - DS_TAG_BITS - LOG_MAX_MARK_PROCS)) - 1) # define MAKE_PROC(proc_index, env) \ (((((env) << LOG_MAX_MARK_PROCS) | (proc_index)) << DS_TAG_BITS) \ | DS_PROC) #define DS_PER_OBJECT 3 /* The real descriptor is at the */ /* byte displacement from the beginning of the */ /* object given by descr & ~DS_TAGS */ /* If the descriptor is negative, the real */ /* descriptor is at (*<object_start>) - */ /* (descr & ~DS_TAGS) - INDIR_PER_OBJ_BIAS */ /* The latter alternative can be used if each */ /* object contains a type descriptor in the */ /* first word. */ #define INDIR_PER_OBJ_BIAS 0x10 typedef struct ms_entry { word * mse_start; /* First word of object */ 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_top; extern mse * GC_mark_stack; #ifdef PRINT_BLACK_LIST ptr_t GC_find_start(ptr_t, hdr*, word); #else ptr_t GC_find_start(ptr_t, hdr*); #endif mse * GC_signal_mark_stack_overflow(mse *); # 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, source) \ GC_find_start(current, hhdr, source) #else # define GC_FIND_START(current, hhdr, source) \ GC_find_start(current, hhdr) #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)) { \ my_current = GC_FIND_START(my_current, my_hhdr, (word)source); \ if (my_current == 0) goto exit_label; \ my_hhdr = GC_find_header(my_current); \ } \ 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: ; \ } /* As above, but deal with two pointers in interleaved fashion. */ # define HC_PUSH_CONTENTS2(current1, current2, mark_stack_top, \ mark_stack_limit, \ source1, source2, exit_label1, exit_label2) \ { \ hdr * hhdr1; \ ptr_t my_current1 = current1; \ hdr * hhdr2; \ ptr_t my_current2 = current2; \ \ HC_GET_HDR2(my_current1, hhdr1, source1, my_current2, hhdr2, source2); \ PUSH_CONTENTS_HDR(my_current1, mark_stack_top, mark_stack_limit, \ source1, exit_label1, hhdr1); \ exit_label1: ; \ if (0 != hhdr2) { \ PUSH_CONTENTS_HDR(my_current2, mark_stack_top, mark_stack_limit, \ source2, exit_label2, hhdr2); \ } \ exit_label2: ; \ } # define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \ source, exit_label, hhdr) \ { \ int displ; /* Displacement in block; first bytes, then words */ \ map_entry_type map_entry; \ \ displ = HBLKDISPL(current); \ map_entry = MAP_ENTRY((hhdr -> hb_map), displ); \ if (map_entry == OBJ_INVALID) { \ GC_ADD_TO_BLACK_LIST_NORMAL(current, source); goto exit_label; \ } \ displ = BYTES_TO_WORDS(displ); \ displ -= map_entry; \ \ { \ register word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(displ); \ register word mark_word = *mark_word_addr; \ register word mark_bit = (word)1 << modWORDSZ(displ); \ \ if (mark_word & mark_bit) { \ /* Mark bit is already set */ \ goto exit_label; \ } \ GC_STORE_BACK_PTR((ptr_t)source, (ptr_t)HBLKPTR(current) \ + WORDS_TO_BYTES(displ)); \ *mark_word_addr = mark_word | mark_bit; \ } \ 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(p, ip, source) \ GC_push_one_checked(p, ip, (ptr_t)(source)) #else # define PUSH_ONE_CHECKED(p, ip, source) \ GC_push_one_checked(p, ip) #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) >= GC_least_plausible_heap_addr \ && (ptr_t)(p) < GC_greatest_plausible_heap_addr) { \ PUSH_ONE_CHECKED(p, TRUE, source); \ } /* * As above, but interior pointer recognition as for * normal for heap pointers. */ # ifdef ALL_INTERIOR_POINTERS # define AIP TRUE # else # define AIP FALSE # endif # define GC_PUSH_ONE_HEAP(p,source) \ if ((ptr_t)(p) >= GC_least_plausible_heap_addr \ && (ptr_t)(p) < GC_greatest_plausible_heap_addr) { \ PUSH_ONE_CHECKED(p,AIP,source); \ } /* * 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()) GC_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_MARK_H */