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Diffstat (limited to 'boehm-gc/mark.c')
| -rw-r--r-- | boehm-gc/mark.c | 1817 |
1 files changed, 1817 insertions, 0 deletions
diff --git a/boehm-gc/mark.c b/boehm-gc/mark.c new file mode 100644 index 000000000..09dfe92af --- /dev/null +++ b/boehm-gc/mark.c @@ -0,0 +1,1817 @@ + +/* + * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers + * Copyright (c) 1991-1995 by Xerox Corporation. All rights reserved. + * Copyright (c) 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 <stdio.h> +# include "private/gc_pmark.h" + +#if defined(MSWIN32) && defined(__GNUC__) +# include <excpt.h> +#endif + +/* We put this here to minimize the risk of inlining. */ +/*VARARGS*/ +#ifdef __WATCOMC__ + void GC_noop(void *p, ...) {} +#else + void GC_noop() {} +#endif + +/* Single argument version, robust against whole program analysis. */ +void GC_noop1(x) +word x; +{ + static VOLATILE word sink; + + sink = x; +} + +/* mark_proc GC_mark_procs[MAX_MARK_PROCS] = {0} -- declared in gc_priv.h */ + +word GC_n_mark_procs = GC_RESERVED_MARK_PROCS; + +/* Initialize GC_obj_kinds properly and standard free lists properly. */ +/* This must be done statically since they may be accessed before */ +/* GC_init is called. */ +/* It's done here, since we need to deal with mark descriptors. */ +struct obj_kind GC_obj_kinds[MAXOBJKINDS] = { +/* PTRFREE */ { &GC_aobjfreelist[0], 0 /* filled in dynamically */, + 0 | GC_DS_LENGTH, FALSE, FALSE }, +/* NORMAL */ { &GC_objfreelist[0], 0, + 0 | GC_DS_LENGTH, /* Adjusted in GC_init_inner for EXTRA_BYTES */ + TRUE /* add length to descr */, TRUE }, +/* UNCOLLECTABLE */ + { &GC_uobjfreelist[0], 0, + 0 | GC_DS_LENGTH, TRUE /* add length to descr */, TRUE }, +# ifdef ATOMIC_UNCOLLECTABLE + /* AUNCOLLECTABLE */ + { &GC_auobjfreelist[0], 0, + 0 | GC_DS_LENGTH, FALSE /* add length to descr */, FALSE }, +# endif +# ifdef STUBBORN_ALLOC +/*STUBBORN*/ { &GC_sobjfreelist[0], 0, + 0 | GC_DS_LENGTH, TRUE /* add length to descr */, TRUE }, +# endif +}; + +# ifdef ATOMIC_UNCOLLECTABLE +# ifdef STUBBORN_ALLOC + int GC_n_kinds = 5; +# else + int GC_n_kinds = 4; +# endif +# else +# ifdef STUBBORN_ALLOC + int GC_n_kinds = 4; +# else + int GC_n_kinds = 3; +# endif +# endif + + +# ifndef INITIAL_MARK_STACK_SIZE +# define INITIAL_MARK_STACK_SIZE (1*HBLKSIZE) + /* INITIAL_MARK_STACK_SIZE * sizeof(mse) should be a */ + /* multiple of HBLKSIZE. */ + /* The incremental collector actually likes a larger */ + /* size, since it want to push all marked dirty objs */ + /* before marking anything new. Currently we let it */ + /* grow dynamically. */ +# endif + +/* + * Limits of stack for GC_mark routine. + * All ranges between GC_mark_stack(incl.) and GC_mark_stack_top(incl.) still + * need to be marked from. + */ + +word GC_n_rescuing_pages; /* Number of dirty pages we marked from */ + /* excludes ptrfree pages, etc. */ + +mse * GC_mark_stack; + +mse * GC_mark_stack_limit; + +word GC_mark_stack_size = 0; + +#ifdef PARALLEL_MARK + mse * VOLATILE GC_mark_stack_top; +#else + mse * GC_mark_stack_top; +#endif + +static struct hblk * scan_ptr; + +mark_state_t GC_mark_state = MS_NONE; + +GC_bool GC_mark_stack_too_small = FALSE; + +GC_bool GC_objects_are_marked = FALSE; /* Are there collectable marked */ + /* objects in the heap? */ + +/* Is a collection in progress? Note that this can return true in the */ +/* nonincremental case, if a collection has been abandoned and the */ +/* mark state is now MS_INVALID. */ +GC_bool GC_collection_in_progress() +{ + return(GC_mark_state != MS_NONE); +} + +/* clear all mark bits in the header */ +void GC_clear_hdr_marks(hhdr) +register hdr * hhdr; +{ +# ifdef USE_MARK_BYTES + BZERO(hhdr -> hb_marks, MARK_BITS_SZ); +# else + BZERO(hhdr -> hb_marks, MARK_BITS_SZ*sizeof(word)); +# endif +} + +/* Set all mark bits in the header. Used for uncollectable blocks. */ +void GC_set_hdr_marks(hhdr) +register hdr * hhdr; +{ + register int i; + + for (i = 0; i < MARK_BITS_SZ; ++i) { +# ifdef USE_MARK_BYTES + hhdr -> hb_marks[i] = 1; +# else + hhdr -> hb_marks[i] = ONES; +# endif + } +} + +/* + * Clear all mark bits associated with block h. + */ +/*ARGSUSED*/ +# if defined(__STDC__) || defined(__cplusplus) + static void clear_marks_for_block(struct hblk *h, word dummy) +# else + static void clear_marks_for_block(h, dummy) + struct hblk *h; + word dummy; +# endif +{ + register hdr * hhdr = HDR(h); + + if (IS_UNCOLLECTABLE(hhdr -> hb_obj_kind)) return; + /* Mark bit for these is cleared only once the object is */ + /* explicitly deallocated. This either frees the block, or */ + /* the bit is cleared once the object is on the free list. */ + GC_clear_hdr_marks(hhdr); +} + +/* Slow but general routines for setting/clearing/asking about mark bits */ +void GC_set_mark_bit(p) +ptr_t p; +{ + register struct hblk *h = HBLKPTR(p); + register hdr * hhdr = HDR(h); + register int word_no = (word *)p - (word *)h; + + set_mark_bit_from_hdr(hhdr, word_no); +} + +void GC_clear_mark_bit(p) +ptr_t p; +{ + register struct hblk *h = HBLKPTR(p); + register hdr * hhdr = HDR(h); + register int word_no = (word *)p - (word *)h; + + clear_mark_bit_from_hdr(hhdr, word_no); +} + +GC_bool GC_is_marked(p) +ptr_t p; +{ + register struct hblk *h = HBLKPTR(p); + register hdr * hhdr = HDR(h); + register int word_no = (word *)p - (word *)h; + + return(mark_bit_from_hdr(hhdr, word_no)); +} + + +/* + * Clear mark bits in all allocated heap blocks. This invalidates + * the marker invariant, and sets GC_mark_state to reflect this. + * (This implicitly starts marking to reestablish the invariant.) + */ +void GC_clear_marks() +{ + GC_apply_to_all_blocks(clear_marks_for_block, (word)0); + GC_objects_are_marked = FALSE; + GC_mark_state = MS_INVALID; + scan_ptr = 0; +# ifdef GATHERSTATS + /* Counters reflect currently marked objects: reset here */ + GC_composite_in_use = 0; + GC_atomic_in_use = 0; +# endif + +} + +/* Initiate a garbage collection. Initiates a full collection if the */ +/* mark state is invalid. */ +/*ARGSUSED*/ +void GC_initiate_gc() +{ + if (GC_dirty_maintained) GC_read_dirty(); +# ifdef STUBBORN_ALLOC + GC_read_changed(); +# endif +# ifdef CHECKSUMS + { + extern void GC_check_dirty(); + + if (GC_dirty_maintained) GC_check_dirty(); + } +# endif + GC_n_rescuing_pages = 0; + if (GC_mark_state == MS_NONE) { + GC_mark_state = MS_PUSH_RESCUERS; + } else if (GC_mark_state != MS_INVALID) { + ABORT("unexpected state"); + } /* else this is really a full collection, and mark */ + /* bits are invalid. */ + scan_ptr = 0; +} + + +static void alloc_mark_stack(); + +/* Perform a small amount of marking. */ +/* We try to touch roughly a page of memory. */ +/* Return TRUE if we just finished a mark phase. */ +/* Cold_gc_frame is an address inside a GC frame that */ +/* remains valid until all marking is complete. */ +/* A zero value indicates that it's OK to miss some */ +/* register values. */ +/* We hold the allocation lock. In the case of */ +/* incremental collection, the world may not be stopped.*/ +#ifdef MSWIN32 + /* For win32, this is called after we establish a structured */ + /* exception handler, in case Windows unmaps one of our root */ + /* segments. See below. In either case, we acquire the */ + /* allocator lock long before we get here. */ + GC_bool GC_mark_some_inner(cold_gc_frame) + ptr_t cold_gc_frame; +#else + GC_bool GC_mark_some(cold_gc_frame) + ptr_t cold_gc_frame; +#endif +{ + switch(GC_mark_state) { + case MS_NONE: + return(FALSE); + + case MS_PUSH_RESCUERS: + if (GC_mark_stack_top + >= GC_mark_stack_limit - INITIAL_MARK_STACK_SIZE/2) { + /* Go ahead and mark, even though that might cause us to */ + /* see more marked dirty objects later on. Avoid this */ + /* in the future. */ + GC_mark_stack_too_small = TRUE; + MARK_FROM_MARK_STACK(); + return(FALSE); + } else { + scan_ptr = GC_push_next_marked_dirty(scan_ptr); + if (scan_ptr == 0) { +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf1("Marked from %lu dirty pages\n", + (unsigned long)GC_n_rescuing_pages); + } +# endif + GC_push_roots(FALSE, cold_gc_frame); + GC_objects_are_marked = TRUE; + if (GC_mark_state != MS_INVALID) { + GC_mark_state = MS_ROOTS_PUSHED; + } + } + } + return(FALSE); + + case MS_PUSH_UNCOLLECTABLE: + if (GC_mark_stack_top + >= GC_mark_stack + GC_mark_stack_size/4) { +# ifdef PARALLEL_MARK + /* Avoid this, since we don't parallelize the marker */ + /* here. */ + if (GC_parallel) GC_mark_stack_too_small = TRUE; +# endif + MARK_FROM_MARK_STACK(); + return(FALSE); + } else { + scan_ptr = GC_push_next_marked_uncollectable(scan_ptr); + if (scan_ptr == 0) { + GC_push_roots(TRUE, cold_gc_frame); + GC_objects_are_marked = TRUE; + if (GC_mark_state != MS_INVALID) { + GC_mark_state = MS_ROOTS_PUSHED; + } + } + } + return(FALSE); + + case MS_ROOTS_PUSHED: +# ifdef PARALLEL_MARK + /* In the incremental GC case, this currently doesn't */ + /* quite do the right thing, since it runs to */ + /* completion. On the other hand, starting a */ + /* parallel marker is expensive, so perhaps it is */ + /* the right thing? */ + /* Eventually, incremental marking should run */ + /* asynchronously in multiple threads, without grabbing */ + /* the allocation lock. */ + if (GC_parallel) { + GC_do_parallel_mark(); + GC_ASSERT(GC_mark_stack_top < GC_first_nonempty); + GC_mark_stack_top = GC_mark_stack - 1; + if (GC_mark_stack_too_small) { + alloc_mark_stack(2*GC_mark_stack_size); + } + if (GC_mark_state == MS_ROOTS_PUSHED) { + GC_mark_state = MS_NONE; + return(TRUE); + } else { + return(FALSE); + } + } +# endif + if (GC_mark_stack_top >= GC_mark_stack) { + MARK_FROM_MARK_STACK(); + return(FALSE); + } else { + GC_mark_state = MS_NONE; + if (GC_mark_stack_too_small) { + alloc_mark_stack(2*GC_mark_stack_size); + } + return(TRUE); + } + + case MS_INVALID: + case MS_PARTIALLY_INVALID: + if (!GC_objects_are_marked) { + GC_mark_state = MS_PUSH_UNCOLLECTABLE; + return(FALSE); + } + if (GC_mark_stack_top >= GC_mark_stack) { + MARK_FROM_MARK_STACK(); + return(FALSE); + } + if (scan_ptr == 0 && GC_mark_state == MS_INVALID) { + /* About to start a heap scan for marked objects. */ + /* Mark stack is empty. OK to reallocate. */ + if (GC_mark_stack_too_small) { + alloc_mark_stack(2*GC_mark_stack_size); + } + GC_mark_state = MS_PARTIALLY_INVALID; + } + scan_ptr = GC_push_next_marked(scan_ptr); + if (scan_ptr == 0 && GC_mark_state == MS_PARTIALLY_INVALID) { + GC_push_roots(TRUE, cold_gc_frame); + GC_objects_are_marked = TRUE; + if (GC_mark_state != MS_INVALID) { + GC_mark_state = MS_ROOTS_PUSHED; + } + } + return(FALSE); + default: + ABORT("GC_mark_some: bad state"); + return(FALSE); + } +} + + +#ifdef MSWIN32 + +# ifdef __GNUC__ + + typedef struct { + EXCEPTION_REGISTRATION ex_reg; + void *alt_path; + } ext_ex_regn; + + + static EXCEPTION_DISPOSITION mark_ex_handler( + struct _EXCEPTION_RECORD *ex_rec, + void *est_frame, + struct _CONTEXT *context, + void *disp_ctxt) + { + if (ex_rec->ExceptionCode == STATUS_ACCESS_VIOLATION) { + ext_ex_regn *xer = (ext_ex_regn *)est_frame; + + /* Unwind from the inner function assuming the standard */ + /* function prologue. */ + /* Assumes code has not been compiled with */ + /* -fomit-frame-pointer. */ + context->Esp = context->Ebp; + context->Ebp = *((DWORD *)context->Esp); + context->Esp = context->Esp - 8; + + /* Resume execution at the "real" handler within the */ + /* wrapper function. */ + context->Eip = (DWORD )(xer->alt_path); + + return ExceptionContinueExecution; + + } else { + return ExceptionContinueSearch; + } + } +# endif /* __GNUC__ */ + + + GC_bool GC_mark_some(cold_gc_frame) + ptr_t cold_gc_frame; + { + GC_bool ret_val; + +# ifndef __GNUC__ + /* Windows 98 appears to asynchronously create and remove */ + /* writable memory mappings, for reasons we haven't yet */ + /* understood. Since we look for writable regions to */ + /* determine the root set, we may try to mark from an */ + /* address range that disappeared since we started the */ + /* collection. Thus we have to recover from faults here. */ + /* This code does not appear to be necessary for Windows */ + /* 95/NT/2000. Note that this code should never generate */ + /* an incremental GC write fault. */ + + __try { + +# else /* __GNUC__ */ + + /* Manually install an exception handler since GCC does */ + /* not yet support Structured Exception Handling (SEH) on */ + /* Win32. */ + + ext_ex_regn er; + + er.alt_path = &&handle_ex; + er.ex_reg.handler = mark_ex_handler; + asm volatile ("movl %%fs:0, %0" : "=r" (er.ex_reg.prev)); + asm volatile ("movl %0, %%fs:0" : : "r" (&er)); + +# endif /* __GNUC__ */ + + ret_val = GC_mark_some_inner(cold_gc_frame); + +# ifndef __GNUC__ + + } __except (GetExceptionCode() == EXCEPTION_ACCESS_VIOLATION ? + EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH) { + +# else /* __GNUC__ */ + + /* Prevent GCC from considering the following code unreachable */ + /* and thus eliminating it. */ + if (er.alt_path != 0) + goto rm_handler; + +handle_ex: + /* Execution resumes from here on an access violation. */ + +# endif /* __GNUC__ */ + +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf0("Caught ACCESS_VIOLATION in marker. " + "Memory mapping disappeared.\n"); + } +# endif /* CONDPRINT */ + + /* We have bad roots on the stack. Discard mark stack. */ + /* Rescan from marked objects. Redetermine roots. */ + GC_invalidate_mark_state(); + scan_ptr = 0; + + ret_val = FALSE; + +# ifndef __GNUC__ + + } + +# else /* __GNUC__ */ + +rm_handler: + /* Uninstall the exception handler */ + asm volatile ("mov %0, %%fs:0" : : "r" (er.ex_reg.prev)); + +# endif /* __GNUC__ */ + + return ret_val; + } +#endif /* MSWIN32 */ + + +GC_bool GC_mark_stack_empty() +{ + return(GC_mark_stack_top < GC_mark_stack); +} + +#ifdef PROF_MARKER + word GC_prof_array[10]; +# define PROF(n) GC_prof_array[n]++ +#else +# define PROF(n) +#endif + +/* Given a pointer to someplace other than a small object page or the */ +/* first page of a large object, either: */ +/* - return a pointer to somewhere in the first page of the large */ +/* object, if current points to a large object. */ +/* In this case *hhdr is replaced with a pointer to the header */ +/* for the large object. */ +/* - just return current if it does not point to a large object. */ +/*ARGSUSED*/ +ptr_t GC_find_start(current, hhdr, new_hdr_p) +register ptr_t current; +register hdr *hhdr, **new_hdr_p; +{ + if (GC_all_interior_pointers) { + if (hhdr != 0) { + register ptr_t orig = current; + + current = (ptr_t)HBLKPTR(current); + do { + current = current - HBLKSIZE*(word)hhdr; + hhdr = HDR(current); + } while(IS_FORWARDING_ADDR_OR_NIL(hhdr)); + /* current points to near the start of the large object */ + if (hhdr -> hb_flags & IGNORE_OFF_PAGE) return(orig); + if ((word *)orig - (word *)current + >= (ptrdiff_t)(hhdr->hb_sz)) { + /* Pointer past the end of the block */ + return(orig); + } + *new_hdr_p = hhdr; + return(current); + } else { + return(current); + } + } else { + return(current); + } +} + +void GC_invalidate_mark_state() +{ + GC_mark_state = MS_INVALID; + GC_mark_stack_top = GC_mark_stack-1; +} + +mse * GC_signal_mark_stack_overflow(msp) +mse * msp; +{ + GC_mark_state = MS_INVALID; + GC_mark_stack_too_small = TRUE; +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf1("Mark stack overflow; current size = %lu entries\n", + GC_mark_stack_size); + } +# endif + return(msp - GC_MARK_STACK_DISCARDS); +} + +/* + * Mark objects pointed to by the regions described by + * mark stack entries between GC_mark_stack and GC_mark_stack_top, + * inclusive. Assumes the upper limit of a mark stack entry + * is never 0. A mark stack entry never has size 0. + * We try to traverse on the order of a hblk of memory before we return. + * Caller is responsible for calling this until the mark stack is empty. + * Note that this is the most performance critical routine in the + * collector. Hence it contains all sorts of ugly hacks to speed + * things up. In particular, we avoid procedure calls on the common + * path, we take advantage of peculiarities of the mark descriptor + * encoding, we optionally maintain a cache for the block address to + * header mapping, we prefetch when an object is "grayed", etc. + */ +mse * GC_mark_from(mark_stack_top, mark_stack, mark_stack_limit) +mse * mark_stack_top; +mse * mark_stack; +mse * mark_stack_limit; +{ + int credit = HBLKSIZE; /* Remaining credit for marking work */ + register word * current_p; /* Pointer to current candidate ptr. */ + register word current; /* Candidate pointer. */ + register word * limit; /* (Incl) limit of current candidate */ + /* range */ + register word descr; + register ptr_t greatest_ha = GC_greatest_plausible_heap_addr; + register ptr_t least_ha = GC_least_plausible_heap_addr; + DECLARE_HDR_CACHE; + +# define SPLIT_RANGE_WORDS 128 /* Must be power of 2. */ + + GC_objects_are_marked = TRUE; + INIT_HDR_CACHE; +# ifdef OS2 /* Use untweaked version to circumvent compiler problem */ + while (mark_stack_top >= mark_stack && credit >= 0) { +# else + while ((((ptr_t)mark_stack_top - (ptr_t)mark_stack) | credit) + >= 0) { +# endif + current_p = mark_stack_top -> mse_start; + descr = mark_stack_top -> mse_descr; + retry: + /* current_p and descr describe the current object. */ + /* *mark_stack_top is vacant. */ + /* The following is 0 only for small objects described by a simple */ + /* length descriptor. For many applications this is the common */ + /* case, so we try to detect it quickly. */ + if (descr & ((~(WORDS_TO_BYTES(SPLIT_RANGE_WORDS) - 1)) | GC_DS_TAGS)) { + word tag = descr & GC_DS_TAGS; + + switch(tag) { + case GC_DS_LENGTH: + /* Large length. */ + /* Process part of the range to avoid pushing too much on the */ + /* stack. */ + GC_ASSERT(descr < (word)GC_greatest_plausible_heap_addr + - (word)GC_least_plausible_heap_addr); +# ifdef PARALLEL_MARK +# define SHARE_BYTES 2048 + if (descr > SHARE_BYTES && GC_parallel + && mark_stack_top < mark_stack_limit - 1) { + int new_size = (descr/2) & ~(sizeof(word)-1); + mark_stack_top -> mse_start = current_p; + mark_stack_top -> mse_descr = new_size + sizeof(word); + /* makes sure we handle */ + /* misaligned pointers. */ + mark_stack_top++; + current_p = (word *) ((char *)current_p + new_size); + descr -= new_size; + goto retry; + } +# endif /* PARALLEL_MARK */ + mark_stack_top -> mse_start = + limit = current_p + SPLIT_RANGE_WORDS-1; + mark_stack_top -> mse_descr = + descr - WORDS_TO_BYTES(SPLIT_RANGE_WORDS-1); + /* Make sure that pointers overlapping the two ranges are */ + /* considered. */ + limit = (word *)((char *)limit + sizeof(word) - ALIGNMENT); + break; + case GC_DS_BITMAP: + mark_stack_top--; + descr &= ~GC_DS_TAGS; + credit -= WORDS_TO_BYTES(WORDSZ/2); /* guess */ + while (descr != 0) { + if ((signed_word)descr < 0) { + current = *current_p; + FIXUP_POINTER(current); + if ((ptr_t)current >= least_ha && (ptr_t)current < greatest_ha) { + PREFETCH((ptr_t)current); + HC_PUSH_CONTENTS((ptr_t)current, mark_stack_top, + mark_stack_limit, current_p, exit1); + } + } + descr <<= 1; + ++ current_p; + } + continue; + case GC_DS_PROC: + mark_stack_top--; + credit -= GC_PROC_BYTES; + mark_stack_top = + (*PROC(descr)) + (current_p, mark_stack_top, + mark_stack_limit, ENV(descr)); + continue; + case GC_DS_PER_OBJECT: + if ((signed_word)descr >= 0) { + /* Descriptor is in the object. */ + descr = *(word *)((ptr_t)current_p + descr - GC_DS_PER_OBJECT); + } else { + /* Descriptor is in type descriptor pointed to by first */ + /* word in object. */ + ptr_t type_descr = *(ptr_t *)current_p; + /* type_descr is either a valid pointer to the descriptor */ + /* structure, or this object was on a free list. If it */ + /* it was anything but the last object on the free list, */ + /* we will misinterpret the next object on the free list as */ + /* the type descriptor, and get a 0 GC descriptor, which */ + /* is ideal. Unfortunately, we need to check for the last */ + /* object case explicitly. */ + if (0 == type_descr) { + /* Rarely executed. */ + mark_stack_top--; + continue; + } + descr = *(word *)(type_descr + - (descr - (GC_DS_PER_OBJECT + - GC_INDIR_PER_OBJ_BIAS))); + } + if (0 == descr) { + /* Can happen either because we generated a 0 descriptor */ + /* or we saw a pointer to a free object. */ + mark_stack_top--; + continue; + } + goto retry; + } + } else /* Small object with length descriptor */ { + mark_stack_top--; + limit = (word *)(((ptr_t)current_p) + (word)descr); + } + /* The simple case in which we're scanning a range. */ + GC_ASSERT(!((word)current_p & (ALIGNMENT-1))); + credit -= (ptr_t)limit - (ptr_t)current_p; + limit -= 1; + { +# define PREF_DIST 4 + +# ifndef SMALL_CONFIG + word deferred; + + /* Try to prefetch the next pointer to be examined asap. */ + /* Empirically, this also seems to help slightly without */ + /* prefetches, at least on linux/X86. Presumably this loop */ + /* ends up with less register pressure, and gcc thus ends up */ + /* generating slightly better code. Overall gcc code quality */ + /* for this loop is still not great. */ + for(;;) { + PREFETCH((ptr_t)limit - PREF_DIST*CACHE_LINE_SIZE); + GC_ASSERT(limit >= current_p); + deferred = *limit; + FIXUP_POINTER(deferred); + limit = (word *)((char *)limit - ALIGNMENT); + if ((ptr_t)deferred >= least_ha && (ptr_t)deferred < greatest_ha) { + PREFETCH((ptr_t)deferred); + break; + } + if (current_p > limit) goto next_object; + /* Unroll once, so we don't do too many of the prefetches */ + /* based on limit. */ + deferred = *limit; + FIXUP_POINTER(deferred); + limit = (word *)((char *)limit - ALIGNMENT); + if ((ptr_t)deferred >= least_ha && (ptr_t)deferred < greatest_ha) { + PREFETCH((ptr_t)deferred); + break; + } + if (current_p > limit) goto next_object; + } +# endif + + while (current_p <= limit) { + /* Empirically, unrolling this loop doesn't help a lot. */ + /* Since HC_PUSH_CONTENTS expands to a lot of code, */ + /* we don't. */ + current = *current_p; + FIXUP_POINTER(current); + PREFETCH((ptr_t)current_p + PREF_DIST*CACHE_LINE_SIZE); + if ((ptr_t)current >= least_ha && (ptr_t)current < greatest_ha) { + /* Prefetch the contents of the object we just pushed. It's */ + /* likely we will need them soon. */ + PREFETCH((ptr_t)current); + HC_PUSH_CONTENTS((ptr_t)current, mark_stack_top, + mark_stack_limit, current_p, exit2); + } + current_p = (word *)((char *)current_p + ALIGNMENT); + } + +# ifndef SMALL_CONFIG + /* We still need to mark the entry we previously prefetched. */ + /* We alrady know that it passes the preliminary pointer */ + /* validity test. */ + HC_PUSH_CONTENTS((ptr_t)deferred, mark_stack_top, + mark_stack_limit, current_p, exit4); + next_object:; +# endif + } + } + return mark_stack_top; +} + +#ifdef PARALLEL_MARK + +/* We assume we have an ANSI C Compiler. */ +GC_bool GC_help_wanted = FALSE; +unsigned GC_helper_count = 0; +unsigned GC_active_count = 0; +mse * VOLATILE GC_first_nonempty; +word GC_mark_no = 0; + +#define LOCAL_MARK_STACK_SIZE HBLKSIZE + /* Under normal circumstances, this is big enough to guarantee */ + /* We don't overflow half of it in a single call to */ + /* GC_mark_from. */ + + +/* Steal mark stack entries starting at mse low into mark stack local */ +/* until we either steal mse high, or we have max entries. */ +/* Return a pointer to the top of the local mark stack. */ +/* *next is replaced by a pointer to the next unscanned mark stack */ +/* entry. */ +mse * GC_steal_mark_stack(mse * low, mse * high, mse * local, + unsigned max, mse **next) +{ + mse *p; + mse *top = local - 1; + unsigned i = 0; + + /* Make sure that prior writes to the mark stack are visible. */ + /* On some architectures, the fact that the reads are */ + /* volatile should suffice. */ +# if !defined(IA64) && !defined(HP_PA) && !defined(I386) + GC_memory_barrier(); +# endif + GC_ASSERT(high >= low-1 && high - low + 1 <= GC_mark_stack_size); + for (p = low; p <= high && i <= max; ++p) { + word descr = *(volatile word *) &(p -> mse_descr); + /* In the IA64 memory model, the following volatile store is */ + /* ordered after this read of descr. Thus a thread must read */ + /* the original nonzero value. HP_PA appears to be similar, */ + /* and if I'm reading the P4 spec correctly, X86 is probably */ + /* also OK. In some other cases we need a barrier. */ +# if !defined(IA64) && !defined(HP_PA) && !defined(I386) + GC_memory_barrier(); +# endif + if (descr != 0) { + *(volatile word *) &(p -> mse_descr) = 0; + /* More than one thread may get this entry, but that's only */ + /* a minor performance problem. */ + ++top; + top -> mse_descr = descr; + top -> mse_start = p -> mse_start; + GC_ASSERT( (top -> mse_descr & GC_DS_TAGS) != GC_DS_LENGTH || + top -> mse_descr < (ptr_t)GC_greatest_plausible_heap_addr + - (ptr_t)GC_least_plausible_heap_addr); + /* If this is a big object, count it as */ + /* size/256 + 1 objects. */ + ++i; + if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) i += (descr >> 8); + } + } + *next = p; + return top; +} + +/* Copy back a local mark stack. */ +/* low and high are inclusive bounds. */ +void GC_return_mark_stack(mse * low, mse * high) +{ + mse * my_top; + mse * my_start; + size_t stack_size; + + if (high < low) return; + stack_size = high - low + 1; + GC_acquire_mark_lock(); + my_top = GC_mark_stack_top; + my_start = my_top + 1; + if (my_start - GC_mark_stack + stack_size > GC_mark_stack_size) { +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf0("No room to copy back mark stack."); + } +# endif + GC_mark_state = MS_INVALID; + GC_mark_stack_too_small = TRUE; + /* We drop the local mark stack. We'll fix things later. */ + } else { + BCOPY(low, my_start, stack_size * sizeof(mse)); + GC_ASSERT(GC_mark_stack_top = my_top); +# if !defined(IA64) && !defined(HP_PA) + GC_memory_barrier(); +# endif + /* On IA64, the volatile write acts as a release barrier. */ + GC_mark_stack_top = my_top + stack_size; + } + GC_release_mark_lock(); + GC_notify_all_marker(); +} + +/* Mark from the local mark stack. */ +/* On return, the local mark stack is empty. */ +/* But this may be achieved by copying the */ +/* local mark stack back into the global one. */ +void GC_do_local_mark(mse *local_mark_stack, mse *local_top) +{ + unsigned n; +# define N_LOCAL_ITERS 1 + +# ifdef GC_ASSERTIONS + /* Make sure we don't hold mark lock. */ + GC_acquire_mark_lock(); + GC_release_mark_lock(); +# endif + for (;;) { + for (n = 0; n < N_LOCAL_ITERS; ++n) { + local_top = GC_mark_from(local_top, local_mark_stack, + local_mark_stack + LOCAL_MARK_STACK_SIZE); + if (local_top < local_mark_stack) return; + if (local_top - local_mark_stack >= LOCAL_MARK_STACK_SIZE/2) { + GC_return_mark_stack(local_mark_stack, local_top); + return; + } + } + if (GC_mark_stack_top < GC_first_nonempty && + GC_active_count < GC_helper_count + && local_top > local_mark_stack + 1) { + /* Try to share the load, since the main stack is empty, */ + /* and helper threads are waiting for a refill. */ + /* The entries near the bottom of the stack are likely */ + /* to require more work. Thus we return those, eventhough */ + /* it's harder. */ + mse * p; + mse * new_bottom = local_mark_stack + + (local_top - local_mark_stack)/2; + GC_ASSERT(new_bottom > local_mark_stack + && new_bottom < local_top); + GC_return_mark_stack(local_mark_stack, new_bottom - 1); + memmove(local_mark_stack, new_bottom, + (local_top - new_bottom + 1) * sizeof(mse)); + local_top -= (new_bottom - local_mark_stack); + } + } +} + +#define ENTRIES_TO_GET 5 + +long GC_markers = 2; /* Normally changed by thread-library- */ + /* -specific code. */ + +/* Mark using the local mark stack until the global mark stack is empty */ +/* and there are no active workers. Update GC_first_nonempty to reflect */ +/* progress. */ +/* Caller does not hold mark lock. */ +/* Caller has already incremented GC_helper_count. We decrement it, */ +/* and maintain GC_active_count. */ +void GC_mark_local(mse *local_mark_stack, int id) +{ + mse * my_first_nonempty; + + GC_acquire_mark_lock(); + GC_active_count++; + my_first_nonempty = GC_first_nonempty; + GC_ASSERT(GC_first_nonempty >= GC_mark_stack && + GC_first_nonempty <= GC_mark_stack_top + 1); +# ifdef PRINTSTATS + GC_printf1("Starting mark helper %lu\n", (unsigned long)id); +# endif + GC_release_mark_lock(); + for (;;) { + size_t n_on_stack; + size_t n_to_get; + mse *next; + mse * my_top; + mse * local_top; + mse * global_first_nonempty = GC_first_nonempty; + + GC_ASSERT(my_first_nonempty >= GC_mark_stack && + my_first_nonempty <= GC_mark_stack_top + 1); + GC_ASSERT(global_first_nonempty >= GC_mark_stack && + global_first_nonempty <= GC_mark_stack_top + 1); + if (my_first_nonempty < global_first_nonempty) { + my_first_nonempty = global_first_nonempty; + } else if (global_first_nonempty < my_first_nonempty) { + GC_compare_and_exchange((word *)(&GC_first_nonempty), + (word) global_first_nonempty, + (word) my_first_nonempty); + /* If this fails, we just go ahead, without updating */ + /* GC_first_nonempty. */ + } + /* Perhaps we should also update GC_first_nonempty, if it */ + /* is less. But that would require using atomic updates. */ + my_top = GC_mark_stack_top; + n_on_stack = my_top - my_first_nonempty + 1; + if (0 == n_on_stack) { + GC_acquire_mark_lock(); + my_top = GC_mark_stack_top; + n_on_stack = my_top - my_first_nonempty + 1; + if (0 == n_on_stack) { + GC_active_count--; + GC_ASSERT(GC_active_count <= GC_helper_count); + /* Other markers may redeposit objects */ + /* on the stack. */ + if (0 == GC_active_count) GC_notify_all_marker(); + while (GC_active_count > 0 + && GC_first_nonempty > GC_mark_stack_top) { + /* We will be notified if either GC_active_count */ + /* reaches zero, or if more objects are pushed on */ + /* the global mark stack. */ + GC_wait_marker(); + } + if (GC_active_count == 0 && + GC_first_nonempty > GC_mark_stack_top) { + GC_bool need_to_notify = FALSE; + /* The above conditions can't be falsified while we */ + /* hold the mark lock, since neither */ + /* GC_active_count nor GC_mark_stack_top can */ + /* change. GC_first_nonempty can only be */ + /* incremented asynchronously. Thus we know that */ + /* both conditions actually held simultaneously. */ + GC_helper_count--; + if (0 == GC_helper_count) need_to_notify = TRUE; +# ifdef PRINTSTATS + GC_printf1( + "Finished mark helper %lu\n", (unsigned long)id); +# endif + GC_release_mark_lock(); + if (need_to_notify) GC_notify_all_marker(); + return; + } + /* else there's something on the stack again, or */ + /* another helper may push something. */ + GC_active_count++; + GC_ASSERT(GC_active_count > 0); + GC_release_mark_lock(); + continue; + } else { + GC_release_mark_lock(); + } + } + n_to_get = ENTRIES_TO_GET; + if (n_on_stack < 2 * ENTRIES_TO_GET) n_to_get = 1; + local_top = GC_steal_mark_stack(my_first_nonempty, my_top, + local_mark_stack, n_to_get, + &my_first_nonempty); + GC_ASSERT(my_first_nonempty >= GC_mark_stack && + my_first_nonempty <= GC_mark_stack_top + 1); + GC_do_local_mark(local_mark_stack, local_top); + } +} + +/* Perform Parallel mark. */ +/* We hold the GC lock, not the mark lock. */ +/* Currently runs until the mark stack is */ +/* empty. */ +void GC_do_parallel_mark() +{ + mse local_mark_stack[LOCAL_MARK_STACK_SIZE]; + mse * local_top; + mse * my_top; + + GC_acquire_mark_lock(); + GC_ASSERT(I_HOLD_LOCK()); + /* This could be a GC_ASSERT, but it seems safer to keep it on */ + /* all the time, especially since it's cheap. */ + if (GC_help_wanted || GC_active_count != 0 || GC_helper_count != 0) + ABORT("Tried to start parallel mark in bad state"); +# ifdef PRINTSTATS + GC_printf1("Starting marking for mark phase number %lu\n", + (unsigned long)GC_mark_no); +# endif + GC_first_nonempty = GC_mark_stack; + GC_active_count = 0; + GC_helper_count = 1; + GC_help_wanted = TRUE; + GC_release_mark_lock(); + GC_notify_all_marker(); + /* Wake up potential helpers. */ + GC_mark_local(local_mark_stack, 0); + GC_acquire_mark_lock(); + GC_help_wanted = FALSE; + /* Done; clean up. */ + while (GC_helper_count > 0) GC_wait_marker(); + /* GC_helper_count cannot be incremented while GC_help_wanted == FALSE */ +# ifdef PRINTSTATS + GC_printf1( + "Finished marking for mark phase number %lu\n", + (unsigned long)GC_mark_no); +# endif + GC_mark_no++; + GC_release_mark_lock(); + GC_notify_all_marker(); +} + + +/* Try to help out the marker, if it's running. */ +/* We do not hold the GC lock, but the requestor does. */ +void GC_help_marker(word my_mark_no) +{ + mse local_mark_stack[LOCAL_MARK_STACK_SIZE]; + unsigned my_id; + mse * my_first_nonempty; + + if (!GC_parallel) return; + GC_acquire_mark_lock(); + while (GC_mark_no < my_mark_no + || !GC_help_wanted && GC_mark_no == my_mark_no) { + GC_wait_marker(); + } + my_id = GC_helper_count; + if (GC_mark_no != my_mark_no || my_id >= GC_markers) { + /* Second test is useful only if original threads can also */ + /* act as helpers. Under Linux they can't. */ + GC_release_mark_lock(); + return; + } + GC_helper_count = my_id + 1; + GC_release_mark_lock(); + GC_mark_local(local_mark_stack, my_id); + /* GC_mark_local decrements GC_helper_count. */ +} + +#endif /* PARALLEL_MARK */ + +/* Allocate or reallocate space for mark stack of size s words */ +/* May silently fail. */ +static void alloc_mark_stack(n) +word n; +{ + mse * new_stack = (mse *)GC_scratch_alloc(n * sizeof(struct GC_ms_entry)); + + GC_mark_stack_too_small = FALSE; + if (GC_mark_stack_size != 0) { + if (new_stack != 0) { + word displ = (word)GC_mark_stack & (GC_page_size - 1); + signed_word size = GC_mark_stack_size * sizeof(struct GC_ms_entry); + + /* Recycle old space */ + if (0 != displ) displ = GC_page_size - displ; + size = (size - displ) & ~(GC_page_size - 1); + if (size > 0) { + GC_add_to_heap((struct hblk *) + ((word)GC_mark_stack + displ), (word)size); + } + GC_mark_stack = new_stack; + GC_mark_stack_size = n; + GC_mark_stack_limit = new_stack + n; +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf1("Grew mark stack to %lu frames\n", + (unsigned long) GC_mark_stack_size); + } +# endif + } else { +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf1("Failed to grow mark stack to %lu frames\n", + (unsigned long) n); + } +# endif + } + } else { + if (new_stack == 0) { + GC_err_printf0("No space for mark stack\n"); + EXIT(); + } + GC_mark_stack = new_stack; + GC_mark_stack_size = n; + GC_mark_stack_limit = new_stack + n; + } + GC_mark_stack_top = GC_mark_stack-1; +} + +void GC_mark_init() +{ + alloc_mark_stack(INITIAL_MARK_STACK_SIZE); +} + +/* + * Push all locations between b and t onto the mark stack. + * b is the first location to be checked. t is one past the last + * location to be checked. + * Should only be used if there is no possibility of mark stack + * overflow. + */ +void GC_push_all(bottom, top) +ptr_t bottom; +ptr_t top; +{ + register word length; + + bottom = (ptr_t)(((word) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1)); + top = (ptr_t)(((word) top) & ~(ALIGNMENT-1)); + if (top == 0 || bottom == top) return; + GC_mark_stack_top++; + if (GC_mark_stack_top >= GC_mark_stack_limit) { + ABORT("unexpected mark stack overflow"); + } + length = top - bottom; +# if GC_DS_TAGS > ALIGNMENT - 1 + length += GC_DS_TAGS; + length &= ~GC_DS_TAGS; +# endif + GC_mark_stack_top -> mse_start = (word *)bottom; + GC_mark_stack_top -> mse_descr = length; +} + +/* + * Analogous to the above, but push only those pages h with dirty_fn(h) != 0. + * We use push_fn to actually push the block. + * Used both to selectively push dirty pages, or to push a block + * in piecemeal fashion, to allow for more marking concurrency. + * Will not overflow mark stack if push_fn pushes a small fixed number + * of entries. (This is invoked only if push_fn pushes a single entry, + * or if it marks each object before pushing it, thus ensuring progress + * in the event of a stack overflow.) + */ +void GC_push_selected(bottom, top, dirty_fn, push_fn) +ptr_t bottom; +ptr_t top; +int (*dirty_fn) GC_PROTO((struct hblk * h)); +void (*push_fn) GC_PROTO((ptr_t bottom, ptr_t top)); +{ + register struct hblk * h; + + bottom = (ptr_t)(((long) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1)); + top = (ptr_t)(((long) top) & ~(ALIGNMENT-1)); + + if (top == 0 || bottom == top) return; + h = HBLKPTR(bottom + HBLKSIZE); + if (top <= (ptr_t) h) { + if ((*dirty_fn)(h-1)) { + (*push_fn)(bottom, top); + } + return; + } + if ((*dirty_fn)(h-1)) { + (*push_fn)(bottom, (ptr_t)h); + } + while ((ptr_t)(h+1) <= top) { + if ((*dirty_fn)(h)) { + if ((word)(GC_mark_stack_top - GC_mark_stack) + > 3 * GC_mark_stack_size / 4) { + /* Danger of mark stack overflow */ + (*push_fn)((ptr_t)h, top); + return; + } else { + (*push_fn)((ptr_t)h, (ptr_t)(h+1)); + } + } + h++; + } + if ((ptr_t)h != top) { + if ((*dirty_fn)(h)) { + (*push_fn)((ptr_t)h, top); + } + } + if (GC_mark_stack_top >= GC_mark_stack_limit) { + ABORT("unexpected mark stack overflow"); + } +} + +# ifndef SMALL_CONFIG + +#ifdef PARALLEL_MARK + /* Break up root sections into page size chunks to better spread */ + /* out work. */ + GC_bool GC_true_func(struct hblk *h) { return TRUE; } +# define GC_PUSH_ALL(b,t) GC_push_selected(b,t,GC_true_func,GC_push_all); +#else +# define GC_PUSH_ALL(b,t) GC_push_all(b,t); +#endif + + +void GC_push_conditional(bottom, top, all) +ptr_t bottom; +ptr_t top; +int all; +{ + if (all) { + if (GC_dirty_maintained) { +# ifdef PROC_VDB + /* Pages that were never dirtied cannot contain pointers */ + GC_push_selected(bottom, top, GC_page_was_ever_dirty, GC_push_all); +# else + GC_push_all(bottom, top); +# endif + } else { + GC_push_all(bottom, top); + } + } else { + GC_push_selected(bottom, top, GC_page_was_dirty, GC_push_all); + } +} +#endif + +# if defined(MSWIN32) || defined(MSWINCE) + void __cdecl GC_push_one(p) +# else + void GC_push_one(p) +# endif +word p; +{ + GC_PUSH_ONE_STACK(p, MARKED_FROM_REGISTER); +} + +struct GC_ms_entry *GC_mark_and_push(obj, mark_stack_ptr, mark_stack_limit, src) +GC_PTR obj; +struct GC_ms_entry * mark_stack_ptr; +struct GC_ms_entry * mark_stack_limit; +GC_PTR *src; +{ + PREFETCH(obj); + PUSH_CONTENTS(obj, mark_stack_ptr /* modified */, mark_stack_limit, src, + was_marked /* internally generated exit label */); + return mark_stack_ptr; +} + +# ifdef __STDC__ +# define BASE(p) (word)GC_base((void *)(p)) +# else +# define BASE(p) (word)GC_base((char *)(p)) +# endif + +/* Mark and push (i.e. gray) a single object p onto the main */ +/* mark stack. Consider p to be valid if it is an interior */ +/* pointer. */ +/* The object p has passed a preliminary pointer validity */ +/* test, but we do not definitely know whether it is valid. */ +/* Mark bits are NOT atomically updated. Thus this must be the */ +/* only thread setting them. */ +# if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS) + void GC_mark_and_push_stack(p, source) + ptr_t source; +# else + void GC_mark_and_push_stack(p) +# define source 0 +# endif +register word p; +{ + register word r; + register hdr * hhdr; + register int displ; + + GET_HDR(p, hhdr); + if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { + if (hhdr != 0) { + r = BASE(p); + hhdr = HDR(r); + displ = BYTES_TO_WORDS(HBLKDISPL(r)); + } + } else { + register map_entry_type map_entry; + + displ = HBLKDISPL(p); + map_entry = MAP_ENTRY((hhdr -> hb_map), displ); + if (map_entry >= MAX_OFFSET) { + if (map_entry == OFFSET_TOO_BIG || !GC_all_interior_pointers) { + r = BASE(p); + displ = BYTES_TO_WORDS(HBLKDISPL(r)); + if (r == 0) hhdr = 0; + } else { + /* Offset invalid, but map reflects interior pointers */ + hhdr = 0; + } + } else { + displ = BYTES_TO_WORDS(displ); + displ -= map_entry; + r = (word)((word *)(HBLKPTR(p)) + displ); + } + } + /* If hhdr != 0 then r == GC_base(p), only we did it faster. */ + /* displ is the word index within the block. */ + if (hhdr == 0) { +# ifdef PRINT_BLACK_LIST + GC_add_to_black_list_stack(p, source); +# else + GC_add_to_black_list_stack(p); +# endif +# undef source /* In case we had to define it. */ + } else { + if (!mark_bit_from_hdr(hhdr, displ)) { + set_mark_bit_from_hdr(hhdr, displ); + GC_STORE_BACK_PTR(source, (ptr_t)r); + PUSH_OBJ((word *)r, hhdr, GC_mark_stack_top, + GC_mark_stack_limit); + } + } +} + +# ifdef TRACE_BUF + +# define TRACE_ENTRIES 1000 + +struct trace_entry { + char * kind; + word gc_no; + word words_allocd; + word arg1; + word arg2; +} GC_trace_buf[TRACE_ENTRIES]; + +int GC_trace_buf_ptr = 0; + +void GC_add_trace_entry(char *kind, word arg1, word arg2) +{ + GC_trace_buf[GC_trace_buf_ptr].kind = kind; + GC_trace_buf[GC_trace_buf_ptr].gc_no = GC_gc_no; + GC_trace_buf[GC_trace_buf_ptr].words_allocd = GC_words_allocd; + GC_trace_buf[GC_trace_buf_ptr].arg1 = arg1 ^ 0x80000000; + GC_trace_buf[GC_trace_buf_ptr].arg2 = arg2 ^ 0x80000000; + GC_trace_buf_ptr++; + if (GC_trace_buf_ptr >= TRACE_ENTRIES) GC_trace_buf_ptr = 0; +} + +void GC_print_trace(word gc_no, GC_bool lock) +{ + int i; + struct trace_entry *p; + + if (lock) LOCK(); + for (i = GC_trace_buf_ptr-1; i != GC_trace_buf_ptr; i--) { + if (i < 0) i = TRACE_ENTRIES-1; + p = GC_trace_buf + i; + if (p -> gc_no < gc_no || p -> kind == 0) return; + printf("Trace:%s (gc:%d,words:%d) 0x%X, 0x%X\n", + p -> kind, p -> gc_no, p -> words_allocd, + (p -> arg1) ^ 0x80000000, (p -> arg2) ^ 0x80000000); + } + printf("Trace incomplete\n"); + if (lock) UNLOCK(); +} + +# endif /* TRACE_BUF */ + +/* + * A version of GC_push_all that treats all interior pointers as valid + * and scans the entire region immediately, in case the contents + * change. + */ +void GC_push_all_eager(bottom, top) +ptr_t bottom; +ptr_t top; +{ + word * b = (word *)(((word) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1)); + word * t = (word *)(((word) top) & ~(ALIGNMENT-1)); + register word *p; + register word q; + register word *lim; + register ptr_t greatest_ha = GC_greatest_plausible_heap_addr; + register ptr_t least_ha = GC_least_plausible_heap_addr; +# define GC_greatest_plausible_heap_addr greatest_ha +# define GC_least_plausible_heap_addr least_ha + + if (top == 0) return; + /* check all pointers in range and push if they appear */ + /* to be valid. */ + lim = t - 1 /* longword */; + for (p = b; p <= lim; p = (word *)(((char *)p) + ALIGNMENT)) { + q = *p; + GC_PUSH_ONE_STACK(q, p); + } +# undef GC_greatest_plausible_heap_addr +# undef GC_least_plausible_heap_addr +} + +#ifndef THREADS +/* + * A version of GC_push_all that treats all interior pointers as valid + * and scans part of the area immediately, to make sure that saved + * register values are not lost. + * Cold_gc_frame delimits the stack section that must be scanned + * eagerly. A zero value indicates that no eager scanning is needed. + */ +void GC_push_all_stack_partially_eager(bottom, top, cold_gc_frame) +ptr_t bottom; +ptr_t top; +ptr_t cold_gc_frame; +{ + if (!NEED_FIXUP_POINTER && GC_all_interior_pointers) { +# define EAGER_BYTES 1024 + /* Push the hot end of the stack eagerly, so that register values */ + /* saved inside GC frames are marked before they disappear. */ + /* The rest of the marking can be deferred until later. */ + if (0 == cold_gc_frame) { + GC_push_all_stack(bottom, top); + return; + } + GC_ASSERT(bottom <= cold_gc_frame && cold_gc_frame <= top); +# ifdef STACK_GROWS_DOWN + GC_push_all(cold_gc_frame - sizeof(ptr_t), top); + GC_push_all_eager(bottom, cold_gc_frame); +# else /* STACK_GROWS_UP */ + GC_push_all(bottom, cold_gc_frame + sizeof(ptr_t)); + GC_push_all_eager(cold_gc_frame, top); +# endif /* STACK_GROWS_UP */ + } else { + GC_push_all_eager(bottom, top); + } +# ifdef TRACE_BUF + GC_add_trace_entry("GC_push_all_stack", bottom, top); +# endif +} +#endif /* !THREADS */ + +void GC_push_all_stack(bottom, top) +ptr_t bottom; +ptr_t top; +{ + if (!NEED_FIXUP_POINTER && GC_all_interior_pointers) { + GC_push_all(bottom, top); + } else { + GC_push_all_eager(bottom, top); + } +} + +#if !defined(SMALL_CONFIG) && !defined(USE_MARK_BYTES) +/* Push all objects reachable from marked objects in the given block */ +/* of size 1 objects. */ +void GC_push_marked1(h, hhdr) +struct hblk *h; +register hdr * hhdr; +{ + word * mark_word_addr = &(hhdr->hb_marks[0]); + register word *p; + word *plim; + register int i; + register word q; + register word mark_word; + register ptr_t greatest_ha = GC_greatest_plausible_heap_addr; + register ptr_t least_ha = GC_least_plausible_heap_addr; + register mse * mark_stack_top = GC_mark_stack_top; + register mse * mark_stack_limit = GC_mark_stack_limit; +# define GC_mark_stack_top mark_stack_top +# define GC_mark_stack_limit mark_stack_limit +# define GC_greatest_plausible_heap_addr greatest_ha +# define GC_least_plausible_heap_addr least_ha + + p = (word *)(h->hb_body); + plim = (word *)(((word)h) + HBLKSIZE); + + /* go through all words in block */ + while( p < plim ) { + mark_word = *mark_word_addr++; + i = 0; + while(mark_word != 0) { + if (mark_word & 1) { + q = p[i]; + GC_PUSH_ONE_HEAP(q, p + i); + } + i++; + mark_word >>= 1; + } + p += WORDSZ; + } +# undef GC_greatest_plausible_heap_addr +# undef GC_least_plausible_heap_addr +# undef GC_mark_stack_top +# undef GC_mark_stack_limit + GC_mark_stack_top = mark_stack_top; +} + + +#ifndef UNALIGNED + +/* Push all objects reachable from marked objects in the given block */ +/* of size 2 objects. */ +void GC_push_marked2(h, hhdr) +struct hblk *h; +register hdr * hhdr; +{ + word * mark_word_addr = &(hhdr->hb_marks[0]); + register word *p; + word *plim; + register int i; + register word q; + register word mark_word; + register ptr_t greatest_ha = GC_greatest_plausible_heap_addr; + register ptr_t least_ha = GC_least_plausible_heap_addr; + register mse * mark_stack_top = GC_mark_stack_top; + register mse * mark_stack_limit = GC_mark_stack_limit; +# define GC_mark_stack_top mark_stack_top +# define GC_mark_stack_limit mark_stack_limit +# define GC_greatest_plausible_heap_addr greatest_ha +# define GC_least_plausible_heap_addr least_ha + + p = (word *)(h->hb_body); + plim = (word *)(((word)h) + HBLKSIZE); + + /* go through all words in block */ + while( p < plim ) { + mark_word = *mark_word_addr++; + i = 0; + while(mark_word != 0) { + if (mark_word & 1) { + q = p[i]; + GC_PUSH_ONE_HEAP(q, p + i); + q = p[i+1]; + GC_PUSH_ONE_HEAP(q, p + i); + } + i += 2; + mark_word >>= 2; + } + p += WORDSZ; + } +# undef GC_greatest_plausible_heap_addr +# undef GC_least_plausible_heap_addr +# undef GC_mark_stack_top +# undef GC_mark_stack_limit + GC_mark_stack_top = mark_stack_top; +} + +/* Push all objects reachable from marked objects in the given block */ +/* of size 4 objects. */ +/* There is a risk of mark stack overflow here. But we handle that. */ +/* And only unmarked objects get pushed, so it's not very likely. */ +void GC_push_marked4(h, hhdr) +struct hblk *h; +register hdr * hhdr; +{ + word * mark_word_addr = &(hhdr->hb_marks[0]); + register word *p; + word *plim; + register int i; + register word q; + register word mark_word; + register ptr_t greatest_ha = GC_greatest_plausible_heap_addr; + register ptr_t least_ha = GC_least_plausible_heap_addr; + register mse * mark_stack_top = GC_mark_stack_top; + register mse * mark_stack_limit = GC_mark_stack_limit; +# define GC_mark_stack_top mark_stack_top +# define GC_mark_stack_limit mark_stack_limit +# define GC_greatest_plausible_heap_addr greatest_ha +# define GC_least_plausible_heap_addr least_ha + + p = (word *)(h->hb_body); + plim = (word *)(((word)h) + HBLKSIZE); + + /* go through all words in block */ + while( p < plim ) { + mark_word = *mark_word_addr++; + i = 0; + while(mark_word != 0) { + if (mark_word & 1) { + q = p[i]; + GC_PUSH_ONE_HEAP(q, p + i); + q = p[i+1]; + GC_PUSH_ONE_HEAP(q, p + i + 1); + q = p[i+2]; + GC_PUSH_ONE_HEAP(q, p + i + 2); + q = p[i+3]; + GC_PUSH_ONE_HEAP(q, p + i + 3); + } + i += 4; + mark_word >>= 4; + } + p += WORDSZ; + } +# undef GC_greatest_plausible_heap_addr +# undef GC_least_plausible_heap_addr +# undef GC_mark_stack_top +# undef GC_mark_stack_limit + GC_mark_stack_top = mark_stack_top; +} + +#endif /* UNALIGNED */ + +#endif /* SMALL_CONFIG */ + +/* Push all objects reachable from marked objects in the given block */ +void GC_push_marked(h, hhdr) +struct hblk *h; +register hdr * hhdr; +{ + register int sz = hhdr -> hb_sz; + register int descr = hhdr -> hb_descr; + register word * p; + register int word_no; + register word * lim; + register mse * GC_mark_stack_top_reg; + register mse * mark_stack_limit = GC_mark_stack_limit; + + /* Some quick shortcuts: */ + if ((0 | GC_DS_LENGTH) == descr) return; + if (GC_block_empty(hhdr)/* nothing marked */) return; + GC_n_rescuing_pages++; + GC_objects_are_marked = TRUE; + if (sz > MAXOBJSZ) { + lim = (word *)h; + } else { + lim = (word *)(h + 1) - sz; + } + + switch(sz) { +# if !defined(SMALL_CONFIG) && !defined(USE_MARK_BYTES) + case 1: + GC_push_marked1(h, hhdr); + break; +# endif +# if !defined(SMALL_CONFIG) && !defined(UNALIGNED) && \ + !defined(USE_MARK_BYTES) + case 2: + GC_push_marked2(h, hhdr); + break; + case 4: + GC_push_marked4(h, hhdr); + break; +# endif + default: + GC_mark_stack_top_reg = GC_mark_stack_top; + for (p = (word *)h, word_no = 0; p <= lim; p += sz, word_no += sz) { + if (mark_bit_from_hdr(hhdr, word_no)) { + /* Mark from fields inside the object */ + PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top_reg, mark_stack_limit); +# ifdef GATHERSTATS + /* Subtract this object from total, since it was */ + /* added in twice. */ + GC_composite_in_use -= sz; +# endif + } + } + GC_mark_stack_top = GC_mark_stack_top_reg; + } +} + +#ifndef SMALL_CONFIG +/* Test whether any page in the given block is dirty */ +GC_bool GC_block_was_dirty(h, hhdr) +struct hblk *h; +register hdr * hhdr; +{ + register int sz = hhdr -> hb_sz; + + if (sz <= MAXOBJSZ) { + return(GC_page_was_dirty(h)); + } else { + register ptr_t p = (ptr_t)h; + sz = WORDS_TO_BYTES(sz); + while (p < (ptr_t)h + sz) { + if (GC_page_was_dirty((struct hblk *)p)) return(TRUE); + p += HBLKSIZE; + } + return(FALSE); + } +} +#endif /* SMALL_CONFIG */ + +/* Similar to GC_push_next_marked, but return address of next block */ +struct hblk * GC_push_next_marked(h) +struct hblk *h; +{ + register hdr * hhdr; + + h = GC_next_used_block(h); + if (h == 0) return(0); + hhdr = HDR(h); + GC_push_marked(h, hhdr); + return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz)); +} + +#ifndef SMALL_CONFIG +/* Identical to above, but mark only from dirty pages */ +struct hblk * GC_push_next_marked_dirty(h) +struct hblk *h; +{ + register hdr * hhdr; + + if (!GC_dirty_maintained) { ABORT("dirty bits not set up"); } + for (;;) { + h = GC_next_used_block(h); + if (h == 0) return(0); + hhdr = HDR(h); +# ifdef STUBBORN_ALLOC + if (hhdr -> hb_obj_kind == STUBBORN) { + if (GC_page_was_changed(h) && GC_block_was_dirty(h, hhdr)) { + break; + } + } else { + if (GC_block_was_dirty(h, hhdr)) break; + } +# else + if (GC_block_was_dirty(h, hhdr)) break; +# endif + h += OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz); + } + GC_push_marked(h, hhdr); + return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz)); +} +#endif + +/* Similar to above, but for uncollectable pages. Needed since we */ +/* do not clear marks for such pages, even for full collections. */ +struct hblk * GC_push_next_marked_uncollectable(h) +struct hblk *h; +{ + register hdr * hhdr = HDR(h); + + for (;;) { + h = GC_next_used_block(h); + if (h == 0) return(0); + hhdr = HDR(h); + if (hhdr -> hb_obj_kind == UNCOLLECTABLE) break; + h += OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz); + } + GC_push_marked(h, hhdr); + return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz)); +} + + |