/* * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers * Copyright (c) 1991-1994 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. */ # include # include "private/gc_priv.h" /* Data structure for list of root sets. */ /* We keep a hash table, so that we can filter out duplicate additions. */ /* Under Win32, we need to do a better job of filtering overlaps, so */ /* we resort to sequential search, and pay the price. */ /* This is really declared in gc_priv.h: struct roots { ptr_t r_start; ptr_t r_end; # if !defined(MSWIN32) && !defined(MSWINCE) struct roots * r_next; # endif GC_bool r_tmp; -- Delete before registering new dynamic libraries }; struct roots GC_static_roots[MAX_ROOT_SETS]; */ int GC_no_dls = 0; /* Register dynamic library data segments. */ static int n_root_sets = 0; /* GC_static_roots[0..n_root_sets) contains the valid root sets. */ # if !defined(NO_DEBUGGING) /* For debugging: */ void GC_print_static_roots(void) { register int i; size_t total = 0; for (i = 0; i < n_root_sets; i++) { GC_printf("From %p to %p%s\n", GC_static_roots[i].r_start, GC_static_roots[i].r_end, GC_static_roots[i].r_tmp ? " (temporary)" : ""); total += GC_static_roots[i].r_end - GC_static_roots[i].r_start; } GC_printf("Total size: %ld\n", (unsigned long) total); if (GC_root_size != total) { GC_printf("GC_root_size incorrect: %ld!!\n", (unsigned long) GC_root_size); } } # endif /* NO_DEBUGGING */ /* Primarily for debugging support: */ /* Is the address p in one of the registered static */ /* root sections? */ GC_bool GC_is_static_root(ptr_t p) { static int last_root_set = MAX_ROOT_SETS; register int i; if (last_root_set < n_root_sets && p >= GC_static_roots[last_root_set].r_start && p < GC_static_roots[last_root_set].r_end) return(TRUE); for (i = 0; i < n_root_sets; i++) { if (p >= GC_static_roots[i].r_start && p < GC_static_roots[i].r_end) { last_root_set = i; return(TRUE); } } return(FALSE); } #if !defined(MSWIN32) && !defined(MSWINCE) /* # define LOG_RT_SIZE 6 # define RT_SIZE (1 << LOG_RT_SIZE) -- Power of 2, may be != MAX_ROOT_SETS struct roots * GC_root_index[RT_SIZE]; -- Hash table header. Used only to check whether a range is -- already present. -- really defined in gc_priv.h */ static INLINE int rt_hash(ptr_t addr) { word result = (word) addr; # if CPP_WORDSZ > 8*LOG_RT_SIZE result ^= result >> 8*LOG_RT_SIZE; # endif # if CPP_WORDSZ > 4*LOG_RT_SIZE result ^= result >> 4*LOG_RT_SIZE; # endif result ^= result >> 2*LOG_RT_SIZE; result ^= result >> LOG_RT_SIZE; result &= (RT_SIZE-1); return(result); } /* Is a range starting at b already in the table? If so return a */ /* pointer to it, else NIL. */ struct roots * GC_roots_present(ptr_t b) { int h = rt_hash(b); struct roots *p = GC_root_index[h]; while (p != 0) { if (p -> r_start == (ptr_t)b) return(p); p = p -> r_next; } return(FALSE); } /* Add the given root structure to the index. */ static void add_roots_to_index(struct roots *p) { int h = rt_hash(p -> r_start); p -> r_next = GC_root_index[h]; GC_root_index[h] = p; } # endif word GC_root_size = 0; GC_API void GC_CALL GC_add_roots(void *b, void *e) { DCL_LOCK_STATE; if (!GC_is_initialized) GC_init(); LOCK(); GC_add_roots_inner((ptr_t)b, (ptr_t)e, FALSE); UNLOCK(); } /* Add [b,e) to the root set. Adding the same interval a second time */ /* is a moderately fast no-op, and hence benign. We do not handle */ /* different but overlapping intervals efficiently. (We do handle */ /* them correctly.) */ /* Tmp specifies that the interval may be deleted before */ /* re-registering dynamic libraries. */ void GC_add_roots_inner(ptr_t b, ptr_t e, GC_bool tmp) { struct roots * old; # if defined(MSWIN32) || defined(MSWINCE) /* Spend the time to ensure that there are no overlapping */ /* or adjacent intervals. */ /* This could be done faster with e.g. a */ /* balanced tree. But the execution time here is */ /* virtually guaranteed to be dominated by the time it */ /* takes to scan the roots. */ { register int i; old = 0; /* initialized to prevent warning. */ for (i = 0; i < n_root_sets; i++) { old = GC_static_roots + i; if (b <= old -> r_end && e >= old -> r_start) { if (b < old -> r_start) { old -> r_start = b; GC_root_size += (old -> r_start - b); } if (e > old -> r_end) { old -> r_end = e; GC_root_size += (e - old -> r_end); } old -> r_tmp &= tmp; break; } } if (i < n_root_sets) { /* merge other overlapping intervals */ struct roots *other; for (i++; i < n_root_sets; i++) { other = GC_static_roots + i; b = other -> r_start; e = other -> r_end; if (b <= old -> r_end && e >= old -> r_start) { if (b < old -> r_start) { old -> r_start = b; GC_root_size += (old -> r_start - b); } if (e > old -> r_end) { old -> r_end = e; GC_root_size += (e - old -> r_end); } old -> r_tmp &= other -> r_tmp; /* Delete this entry. */ GC_root_size -= (other -> r_end - other -> r_start); other -> r_start = GC_static_roots[n_root_sets-1].r_start; other -> r_end = GC_static_roots[n_root_sets-1].r_end; n_root_sets--; } } return; } } # else old = GC_roots_present(b); if (old != 0) { if (e <= old -> r_end) /* already there */ return; /* else extend */ GC_root_size += e - old -> r_end; old -> r_end = e; return; } # endif if (n_root_sets == MAX_ROOT_SETS) { ABORT("Too many root sets\n"); } GC_static_roots[n_root_sets].r_start = (ptr_t)b; GC_static_roots[n_root_sets].r_end = (ptr_t)e; GC_static_roots[n_root_sets].r_tmp = tmp; # if !defined(MSWIN32) && !defined(MSWINCE) GC_static_roots[n_root_sets].r_next = 0; add_roots_to_index(GC_static_roots + n_root_sets); # endif GC_root_size += e - b; n_root_sets++; } static GC_bool roots_were_cleared = FALSE; GC_API void GC_CALL GC_clear_roots (void) { DCL_LOCK_STATE; if (!GC_is_initialized) GC_init(); LOCK(); roots_were_cleared = TRUE; n_root_sets = 0; GC_root_size = 0; # if !defined(MSWIN32) && !defined(MSWINCE) { register int i; for (i = 0; i < RT_SIZE; i++) GC_root_index[i] = 0; } # endif UNLOCK(); } /* Internal use only; lock held. */ static void GC_remove_root_at_pos(int i) { GC_root_size -= (GC_static_roots[i].r_end - GC_static_roots[i].r_start); GC_static_roots[i].r_start = GC_static_roots[n_root_sets-1].r_start; GC_static_roots[i].r_end = GC_static_roots[n_root_sets-1].r_end; GC_static_roots[i].r_tmp = GC_static_roots[n_root_sets-1].r_tmp; n_root_sets--; } #if !defined(MSWIN32) && !defined(MSWINCE) static void GC_rebuild_root_index(void) { int i; for (i = 0; i < RT_SIZE; i++) GC_root_index[i] = 0; for (i = 0; i < n_root_sets; i++) add_roots_to_index(GC_static_roots + i); } #endif #if defined(DYNAMIC_LOADING) || defined(MSWIN32) || defined(MSWINCE) \ || defined(PCR) /* Internal use only; lock held. */ STATIC void GC_remove_tmp_roots(void) { int i; for (i = 0; i < n_root_sets; ) { if (GC_static_roots[i].r_tmp) { GC_remove_root_at_pos(i); } else { i++; } } # if !defined(MSWIN32) && !defined(MSWINCE) GC_rebuild_root_index(); # endif } #endif #if !defined(MSWIN32) && !defined(MSWINCE) GC_API void GC_CALL GC_remove_roots(void *b, void *e) { DCL_LOCK_STATE; LOCK(); GC_remove_roots_inner((ptr_t)b, (ptr_t)e); UNLOCK(); } /* Should only be called when the lock is held */ void GC_remove_roots_inner(ptr_t b, ptr_t e) { int i; for (i = 0; i < n_root_sets; ) { if (GC_static_roots[i].r_start >= b && GC_static_roots[i].r_end <= e) { GC_remove_root_at_pos(i); } else { i++; } } GC_rebuild_root_index(); } #endif /* !defined(MSWIN32) && !defined(MSWINCE) */ #if defined(MSWIN32) || defined(_WIN32_WCE_EMULATION) /* Workaround for the OS mapping and unmapping behind our back: */ /* Is the address p in one of the temporary static root sections? */ GC_bool GC_is_tmp_root(ptr_t p) { static int last_root_set = MAX_ROOT_SETS; register int i; if (last_root_set < n_root_sets && p >= GC_static_roots[last_root_set].r_start && p < GC_static_roots[last_root_set].r_end) return GC_static_roots[last_root_set].r_tmp; for (i = 0; i < n_root_sets; i++) { if (p >= GC_static_roots[i].r_start && p < GC_static_roots[i].r_end) { last_root_set = i; return GC_static_roots[i].r_tmp; } } return(FALSE); } #endif /* MSWIN32 || _WIN32_WCE_EMULATION */ ptr_t GC_approx_sp(void) { volatile word sp; sp = (word)&sp; /* Also force stack to grow if necessary. Otherwise the */ /* later accesses might cause the kernel to think we're */ /* doing something wrong. */ return((ptr_t)sp); } /* * Data structure for excluded static roots. * Real declaration is in gc_priv.h. struct exclusion { ptr_t e_start; ptr_t e_end; }; struct exclusion GC_excl_table[MAX_EXCLUSIONS]; -- Array of exclusions, ascending -- address order. */ STATIC size_t GC_excl_table_entries = 0;/* Number of entries in use. */ /* Return the first exclusion range that includes an address >= start_addr */ /* Assumes the exclusion table contains at least one entry (namely the */ /* GC data structures). */ STATIC struct exclusion * GC_next_exclusion(ptr_t start_addr) { size_t low = 0; size_t high = GC_excl_table_entries - 1; size_t mid; while (high > low) { mid = (low + high) >> 1; /* low <= mid < high */ if ((word) GC_excl_table[mid].e_end <= (word) start_addr) { low = mid + 1; } else { high = mid; } } if ((word) GC_excl_table[low].e_end <= (word) start_addr) return 0; return GC_excl_table + low; } GC_API void GC_CALL GC_exclude_static_roots(void *start, void *finish) { struct exclusion * next; size_t next_index, i; if (0 == GC_excl_table_entries) { next = 0; } else { next = GC_next_exclusion(start); } if (0 != next) { if ((word)(next -> e_start) < (word) finish) { /* incomplete error check. */ ABORT("exclusion ranges overlap"); } if ((word)(next -> e_start) == (word) finish) { /* extend old range backwards */ next -> e_start = (ptr_t)start; return; } next_index = next - GC_excl_table; for (i = GC_excl_table_entries; i > next_index; --i) { GC_excl_table[i] = GC_excl_table[i-1]; } } else { next_index = GC_excl_table_entries; } if (GC_excl_table_entries == MAX_EXCLUSIONS) ABORT("Too many exclusions"); GC_excl_table[next_index].e_start = (ptr_t)start; GC_excl_table[next_index].e_end = (ptr_t)finish; ++GC_excl_table_entries; } /* Invoke push_conditional on ranges that are not excluded. */ /*ARGSUSED*/ STATIC void GC_push_conditional_with_exclusions(ptr_t bottom, ptr_t top, GC_bool all) { struct exclusion * next; ptr_t excl_start; while (bottom < top) { next = GC_next_exclusion(bottom); if (0 == next || (excl_start = next -> e_start) >= top) { GC_push_conditional(bottom, top, all); return; } if (excl_start > bottom) GC_push_conditional(bottom, excl_start, all); bottom = next -> e_end; } } /* Push enough of the current stack eagerly to */ /* ensure that callee-save registers saved in */ /* GC frames are scanned. */ /* In the non-threads case, schedule entire */ /* stack for scanning. */ /* The second argument is a pointer to the */ /* (possibly null) thread context, for */ /* (currently hypothetical) more precise */ /* stack scanning. */ /* * In the absence of threads, push the stack contents. * In the presence of threads, push enough of the current stack * to ensure that callee-save registers saved in collector frames have been * seen. * FIXME: Merge with per-thread stuff. */ /*ARGSUSED*/ STATIC void GC_push_current_stack(ptr_t cold_gc_frame, void * context) { # if defined(THREADS) if (0 == cold_gc_frame) return; # ifdef STACK_GROWS_DOWN GC_push_all_eager(GC_approx_sp(), cold_gc_frame); /* For IA64, the register stack backing store is handled */ /* in the thread-specific code. */ # else GC_push_all_eager( cold_gc_frame, GC_approx_sp() ); # endif # else # ifdef STACK_GROWS_DOWN GC_push_all_stack_partially_eager( GC_approx_sp(), GC_stackbottom, cold_gc_frame ); # ifdef IA64 /* We also need to push the register stack backing store. */ /* This should really be done in the same way as the */ /* regular stack. For now we fudge it a bit. */ /* Note that the backing store grows up, so we can't use */ /* GC_push_all_stack_partially_eager. */ { extern word GC_save_regs_ret_val; /* Previously set to backing store pointer. */ ptr_t bsp = (ptr_t) GC_save_regs_ret_val; ptr_t cold_gc_bs_pointer; if (GC_all_interior_pointers) { cold_gc_bs_pointer = bsp - 2048; if (cold_gc_bs_pointer < BACKING_STORE_BASE) { cold_gc_bs_pointer = BACKING_STORE_BASE; } else { GC_push_all_stack(BACKING_STORE_BASE, cold_gc_bs_pointer); } } else { cold_gc_bs_pointer = BACKING_STORE_BASE; } GC_push_all_eager(cold_gc_bs_pointer, bsp); /* All values should be sufficiently aligned that we */ /* dont have to worry about the boundary. */ } # endif # else GC_push_all_stack_partially_eager( GC_stackbottom, GC_approx_sp(), cold_gc_frame ); # endif # endif /* !THREADS */ } void (*GC_push_typed_structures) (void) = NULL; /* Push GC internal roots. These are normally */ /* included in the static data segment, and */ /* Thus implicitly pushed. But we must do this */ /* explicitly if normal root processing is */ /* disabled. */ /* * Push GC internal roots. Only called if there is some reason to believe * these would not otherwise get registered. */ STATIC void GC_push_gc_structures(void) { GC_push_finalizer_structures(); # if defined(THREADS) GC_push_thread_structures(); # endif if( GC_push_typed_structures ) GC_push_typed_structures(); } #ifdef THREAD_LOCAL_ALLOC void GC_mark_thread_local_free_lists(void); #endif void GC_cond_register_dynamic_libraries(void) { # if defined(DYNAMIC_LOADING) || defined(MSWIN32) || defined(MSWINCE) \ || defined(PCR) GC_remove_tmp_roots(); if (!GC_no_dls) GC_register_dynamic_libraries(); # else GC_no_dls = TRUE; # endif } STATIC void GC_push_regs_and_stack(ptr_t cold_gc_frame) { GC_with_callee_saves_pushed(GC_push_current_stack, cold_gc_frame); } /* * Call the mark routines (GC_tl_push for a single pointer, GC_push_conditional * on groups of pointers) on every top level accessible pointer. * If all is FALSE, arrange to push only possibly altered values. * 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. */ void GC_push_roots(GC_bool all, ptr_t cold_gc_frame) { int i; unsigned kind; /* * Next push static data. This must happen early on, since it's * not robust against mark stack overflow. */ /* Re-register dynamic libraries, in case one got added. */ /* There is some argument for doing this as late as possible, */ /* especially on win32, where it can change asynchronously. */ /* In those cases, we do it here. But on other platforms, it's */ /* not safe with the world stopped, so we do it earlier. */ # if !defined(REGISTER_LIBRARIES_EARLY) GC_cond_register_dynamic_libraries(); # endif /* Mark everything in static data areas */ for (i = 0; i < n_root_sets; i++) { GC_push_conditional_with_exclusions( GC_static_roots[i].r_start, GC_static_roots[i].r_end, all); } /* Mark all free list header blocks, if those were allocated from */ /* the garbage collected heap. This makes sure they don't */ /* disappear if we are not marking from static data. It also */ /* saves us the trouble of scanning them, and possibly that of */ /* marking the freelists. */ for (kind = 0; kind < GC_n_kinds; kind++) { void *base = GC_base(GC_obj_kinds[kind].ok_freelist); if (0 != base) { GC_set_mark_bit(base); } } /* Mark from GC internal roots if those might otherwise have */ /* been excluded. */ if (GC_no_dls || roots_were_cleared) { GC_push_gc_structures(); } /* Mark thread local free lists, even if their mark */ /* descriptor excludes the link field. */ /* If the world is not stopped, this is unsafe. It is */ /* also unnecessary, since we will do this again with the */ /* world stopped. */ # if defined(THREAD_LOCAL_ALLOC) if (GC_world_stopped) GC_mark_thread_local_free_lists(); # endif /* * Now traverse stacks, and mark from register contents. * These must be done last, since they can legitimately overflow * the mark stack. * This is usually done by saving the current context on the * stack, and then just tracing from the stack. */ GC_push_regs_and_stack(cold_gc_frame); if (GC_push_other_roots != 0) (*GC_push_other_roots)(); /* In the threads case, this also pushes thread stacks. */ /* Note that without interior pointer recognition lots */ /* of stuff may have been pushed already, and this */ /* should be careful about mark stack overflows. */ }