# for debugging of the garbage collector itself, but could also
# occasionally be useful for debugging of client code. Slows down the
# collector somewhat, but not drastically.
+# -DKEEP_BACK_PTRS Add code to save back pointers in debugging headers
+# for objects allocated with the debugging allocator. If all objects
+# through GC_MALLOC with GC_DEBUG defined, this allows the client
+# to determine how particular or randomly chosen objects are reachable
+# for debugging/profiling purposes. The backptr.h interface is
+# implemented only if this is defined.
#
-
LIBGC_CFLAGS= -O -DNO_SIGNALS -DSILENT \
-DREDIRECT_MALLOC=GC_malloc_uncollectable \
-DDONT_ADD_BYTE_AT_END -DALL_INTERIOR_POINTERS
threadlibs.c if_mach.c if_not_there.c gc_cpp.cc gc_cpp.h weakpointer.h \
gcc_support.c mips_ultrix_mach_dep.s include/gc_alloc.h gc_alloc.h \
include/new_gc_alloc.h include/javaxfc.h sparc_sunos4_mach_dep.s \
- solaris_threads.h $(CORD_SRCS)
+ solaris_threads.h backptr.h $(CORD_SRCS)
OTHER_FILES= Makefile PCR-Makefile OS2_MAKEFILE NT_MAKEFILE BCC_MAKEFILE \
README test.c test_cpp.cc setjmp_t.c SMakefile.amiga \
cord/gc.h include/gc.h include/gc_typed.h include/cord.h \
include/ec.h include/private/cord_pos.h include/private/gcconfig.h \
include/private/gc_hdrs.h include/private/gc_priv.h \
- include/gc_cpp.h README.rs6000 \
+ include/gc_cpp.h README.rs6000 include/backptr.h \
include/weakpointer.h README.QUICK callprocs pc_excludes \
barrett_diagram README.OS2 README.Mac MacProjects.sit.hqx \
MacOS.c EMX_MAKEFILE makefile.depend README.debugging \
provided the above notices are retained, and a notice that the code was
modified is included with the above copyright notice.
-This is version 5.0alpha1 of a conservative garbage collector for C and C++.
+This is version 5.0alpha2 of a conservative garbage collector for C and C++.
You might find a more recent version of this at
Since 4.14alpha2
- changed STACKBOTTOM for DJGPP (Thanks to Salvador Eduardo Tropea).
-
+
Since 4.14
- Reworked large block allocator. Now uses multiple doubly linked free
lists to approximate best fit.
in such large stacks. And the dirty bit implementation does not
guarantee that none of them will be accessed.
- Integrated Martin Tauchmann's Amiga changes.
- - Inetgrated James Dominy's OpenBSD/SPARC port.
+ - Integrated James Dominy's OpenBSD/SPARC port.
+
+Since 5.0alpha1
+ - Fixed bugs introduced in alpha1 (OpenBSD & large block initialization).
+
+ - Added -DKEEP_BACK_PTRS and backptr.h interface. (The implementation
+ idea came from Al Demers.)
To do:
- Very large root set sizes (> 16 MB or so) could cause the collector
/* Clear block if necessary */
if (GC_debugging_started
|| sz > MAXOBJSZ && GC_obj_kinds[kind].ok_init) {
- BZERO(thishbp + HDR_BYTES, size_needed - HDR_BYTES);
+ BZERO(hbp + HDR_BYTES, size_needed - HDR_BYTES);
}
/* We just successfully allocated a block. Restart count of */
--- /dev/null
+/*
+ * This is a simple API to implement pointer back tracing, i.e.
+ * to answer questions such as "who is pointing to this" or
+ * "why is this object being retained by the collector"
+ *
+ * This API assumes that we have an ANSI C compiler.
+ *
+ * Most of these calls yield useful information on only after
+ * a garbage collection. Usually the client will first force
+ * a full collection and then gather information, preferably
+ * before much intervening allocation.
+ *
+ * The implementation of the interface is only about 99.9999%
+ * correct. It is intended to be good enough for profiling,
+ * but is not intended to be used with production code.
+ *
+ * Results are likely to be much more useful if all allocation is
+ * accomplished through the debugging allocators.
+ *
+ * The implementation idea is due to A. Demers.
+ */
+
+/* Store information about the object referencing dest in *base_p */
+/* and *offset_p. */
+/* If multiple objects or roots point to dest, the one reported */
+/* will be the last on used by the garbage collector to trace the */
+/* object. */
+/* source is root ==> *base_p = address, *offset_p = 0 */
+/* source is heap object ==> *base_p != 0, *offset_p = offset */
+/* Returns 1 on success, 0 if source couldn't be determined. */
+/* Dest can be any address within a heap object. */
+typedef enum { GC_UNREFERENCED, /* No refence info available. */
+ GC_NO_SPACE, /* Dest not allocated with debug alloc */
+ GC_REFD_FROM_ROOT, /* Referenced directly by root *base_p */
+ GC_REFD_FROM_HEAP, /* Referenced from another heap obj. */
+ GC_FINALIZER_REFD /* Finalizable and hence accessible. */
+} GC_ref_kind;
+
+GC_ref_kind GC_get_back_ptr_info(void *dest, void **base_p, size_t *offset_p);
+
+/* Generate a random heap address. */
+/* The resulting address is in the heap, but */
+/* not necessarily inside a valid object. */
+void * GC_generate_random_heap_address(void);
+
+/* Generate a random address inside a valid marked heap object. */
+void * GC_generate_random_valid_address(void);
+
+/* Force a garbage collection and generate a backtrace from a */
+/* random heap address. */
+/* This uses the GC logging mechanism (GC_printf) to produce */
+/* output. It can often be called from a debugger. The */
+/* source in dbg_mlc.c also serves as a sample client. */
+void GC_generate_random_backtrace(void);
+
+
/* This returns a list of objects, linked through their first */
/* word. Its use can greatly reduce lock contention problems, since */
/* the allocation lock can be acquired and released many fewer times. */
+/* lb must be large enough to hold the pointer field. */
GC_PTR GC_malloc_many(size_t lb);
#define GC_NEXT(p) (*(GC_PTR *)(p)) /* Retrieve the next element */
/* in returned list. */
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
-/* Boehm, October 9, 1995 1:16 pm PDT */
+# define I_HIDE_POINTERS
# include "gc_priv.h"
+# ifdef KEEP_BACK_PTRS
+# include "backptr.h"
+# endif
void GC_default_print_heap_obj_proc();
GC_API void GC_register_finalizer_no_order
/* Object header */
typedef struct {
+# ifdef KEEP_BACK_PTRS
+ ptr_t oh_back_ptr;
+# define MARKED_FOR_FINALIZATION (ptr_t)(-1)
+ /* Object was marked because it is finalizable. */
+# ifdef ALIGN_DOUBLE
+ word oh_dummy;
+# endif
+# endif
char * oh_string; /* object descriptor string */
word oh_int; /* object descriptor integers */
# ifdef NEED_CALLINFO
return(FALSE);
}
+#ifdef KEEP_BACK_PTRS
+ /* Store back pointer to source in dest, if that appears to be possible. */
+ /* This is not completely safe, since we may mistakenly conclude that */
+ /* dest has a debugging wrapper. But the error probability is very */
+ /* small, and this shouldn't be used in production code. */
+ /* We assume that dest is the real base pointer. Source will usually */
+ /* be a pointer to the interior of an object. */
+ void GC_store_back_pointer(ptr_t source, ptr_t dest)
+ {
+ if (GC_has_debug_info(dest)) {
+ ((oh *)dest) -> oh_back_ptr = (ptr_t)HIDE_POINTER(source);
+ }
+ }
+
+ void GC_marked_for_finalization(ptr_t dest) {
+ GC_store_back_pointer(MARKED_FOR_FINALIZATION, dest);
+ }
+
+ /* Store information about the object referencing dest in *base_p */
+ /* and *offset_p. */
+ /* source is root ==> *base_p = 0, *offset_p = address */
+ /* source is heap object ==> *base_p != 0, *offset_p = offset */
+ /* Returns 1 on success, 0 if source couldn't be determined. */
+ /* Dest can be any address within a heap object. */
+ GC_ref_kind GC_get_back_ptr_info(void *dest, void **base_p, size_t *offset_p)
+ {
+ oh * hdr = (oh *)GC_base(dest);
+ ptr_t bp;
+ ptr_t bp_base;
+ if (!GC_has_debug_info((ptr_t) hdr)) return GC_NO_SPACE;
+ bp = hdr -> oh_back_ptr;
+ if (MARKED_FOR_FINALIZATION == bp) return GC_FINALIZER_REFD;
+ if (0 == bp) return GC_UNREFERENCED;
+ bp = REVEAL_POINTER(bp);
+ bp_base = GC_base(bp);
+ if (0 == bp_base) {
+ *base_p = bp;
+ *offset_p = 0;
+ return GC_REFD_FROM_ROOT;
+ } else {
+ if (GC_has_debug_info(bp_base)) bp_base += sizeof(oh);
+ *base_p = bp_base;
+ *offset_p = bp - bp_base;
+ return GC_REFD_FROM_HEAP;
+ }
+ }
+
+ /* Generate a random heap address. */
+ /* The resulting address is in the heap, but */
+ /* not necessarily inside a valid object. */
+ void *GC_generate_random_heap_address(void)
+ {
+ int i;
+ int heap_offset = random() % GC_heapsize;
+ for (i = 0; i < GC_n_heap_sects; ++ i) {
+ int size = GC_heap_sects[i].hs_bytes;
+ if (heap_offset < size) {
+ return GC_heap_sects[i].hs_start + heap_offset;
+ } else {
+ heap_offset -= size;
+ }
+ }
+ ABORT("GC_generate_random_heap_address: size inconsistency");
+ /*NOTREACHED*/
+ return 0;
+ }
+
+ /* Generate a random address inside a valid marked heap object. */
+ void *GC_generate_random_valid_address(void)
+ {
+ ptr_t result;
+ ptr_t base;
+ for (;;) {
+ result = GC_generate_random_heap_address();
+ base = GC_base(result);
+ if (0 == base) continue;
+ if (!GC_is_marked(base)) continue;
+ return result;
+ }
+ }
+
+ /* Force a garbage collection and generate a backtrace from a */
+ /* random heap address. */
+ void GC_generate_random_backtrace(void)
+ {
+ void * current;
+ int i;
+ void * base;
+ size_t offset;
+ GC_ref_kind source;
+ GC_gcollect();
+ current = GC_generate_random_valid_address();
+ GC_printf1("Chose address 0x%lx in object\n", (unsigned long)current);
+ GC_print_heap_obj(GC_base(current));
+ GC_err_printf0("\n");
+ for (i = 0; ; ++i) {
+ source = GC_get_back_ptr_info(current, &base, &offset);
+ if (GC_UNREFERENCED == source) {
+ GC_err_printf0("Reference could not be found\n");
+ goto out;
+ }
+ if (GC_NO_SPACE == source) {
+ GC_err_printf0("No debug info in object: Can't find reference\n");
+ goto out;
+ }
+ GC_err_printf1("Reachable via %d levels of pointers from ",
+ (unsigned long)i);
+ switch(source) {
+ case GC_REFD_FROM_ROOT:
+ GC_err_printf1("root at 0x%lx\n", (unsigned long)base);
+ goto out;
+ case GC_FINALIZER_REFD:
+ GC_err_printf0("list of finalizable objects\n");
+ goto out;
+ case GC_REFD_FROM_HEAP:
+ GC_err_printf1("offset %ld in object:\n", (unsigned long)offset);
+ /* Take GC_base(base) to get real base, i.e. header. */
+ GC_print_heap_obj(GC_base(base));
+ GC_err_printf0("\n");
+ break;
+ }
+ current = base;
+ }
+ out:;
+ }
+
+#endif /* KEEP_BACK_PTRS */
+
/* Store debugging info into p. Return displaced pointer. */
/* Assumes we don't hold allocation lock. */
ptr_t GC_store_debug_info(p, sz, string, integer)
/* But that's expensive. And this way things should only appear */
/* inconsistent while we're in the handler. */
LOCK();
+# ifdef KEEP_BACK_PTRS
+ ((oh *)p) -> oh_back_ptr = 0;
+# endif
((oh *)p) -> oh_string = string;
((oh *)p) -> oh_int = integer;
((oh *)p) -> oh_sz = sz;
for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
if (!GC_is_marked(real_ptr)) {
+ GC_MARKED_FOR_FINALIZATION(real_ptr);
GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
if (GC_is_marked(real_ptr)) {
WARN("Finalization cycle involving %lx\n", real_ptr);
/* This returns a list of objects, linked through their first */
/* word. Its use can greatly reduce lock contention problems, since */
/* the allocation lock can be acquired and released many fewer times. */
+/* lb must be large enough to hold the pointer field. */
GC_PTR GC_malloc_many(size_t lb);
#define GC_NEXT(p) (*(GC_PTR *)(p)) /* Retrieve the next element */
/* in returned list. */
/* 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, \
void GC_print_static_roots();
void GC_dump();
+#ifdef KEEP_BACK_PTRS
+ void GC_store_back_pointer(ptr_t source, ptr_t dest);
+ void GC_marked_for_finalization(ptr_t dest);
+# define GC_STORE_BACK_PTR(source, dest) GC_store_back_pointer(source, dest)
+# define GC_MARKED_FOR_FINALIZATION(dest) GC_marked_for_finalization(dest)
+#else
+# define GC_STORE_BACK_PTR(source, dest)
+# define GC_MARKED_FOR_FINALIZATION(dest)
+#endif
+
/* Make arguments appear live to compiler */
# ifdef __WATCOMC__
void GC_noop(void*, ...);
# define OPENBSD
# define mach_type_known
# endif
-# if defined(__OpenBSD__) && defined(sparc)
+# if defined(__OpenBSD__) && defined(__sparc__)
# define SPARC
# define OPENBSD
# define mach_type_known
--- /dev/null
+/*
+ * This is a simple API to implement pointer back tracing, i.e.
+ * to answer questions such as "who is pointing to this" or
+ * "why is this object being retained by the collector"
+ *
+ * This API assumes that we have an ANSI C compiler.
+ *
+ * Most of these calls yield useful information on only after
+ * a garbage collection. Usually the client will first force
+ * a full collection and then gather information, preferably
+ * before much intervening allocation.
+ *
+ * The implementation of the interface is only about 99.9999%
+ * correct. It is intended to be good enough for profiling,
+ * but is not intended to be used with production code.
+ *
+ * Results are likely to be much more useful if all allocation is
+ * accomplished through the debugging allocators.
+ *
+ * The implementation idea is due to A. Demers.
+ */
+
+/* Store information about the object referencing dest in *base_p */
+/* and *offset_p. */
+/* If multiple objects or roots point to dest, the one reported */
+/* will be the last on used by the garbage collector to trace the */
+/* object. */
+/* source is root ==> *base_p = address, *offset_p = 0 */
+/* source is heap object ==> *base_p != 0, *offset_p = offset */
+/* Returns 1 on success, 0 if source couldn't be determined. */
+/* Dest can be any address within a heap object. */
+typedef enum { GC_UNREFERENCED, /* No refence info available. */
+ GC_NO_SPACE, /* Dest not allocated with debug alloc */
+ GC_REFD_FROM_ROOT, /* Referenced directly by root *base_p */
+ GC_REFD_FROM_HEAP, /* Referenced from another heap obj. */
+ GC_FINALIZER_REFD /* Finalizable and hence accessible. */
+} GC_ref_kind;
+
+GC_ref_kind GC_get_back_ptr_info(void *dest, void **base_p, size_t *offset_p);
+
+/* Generate a random heap address. */
+/* The resulting address is in the heap, but */
+/* not necessarily inside a valid object. */
+void * GC_generate_random_heap_address(void);
+
+/* Generate a random address inside a valid marked heap object. */
+void * GC_generate_random_valid_address(void);
+
+/* Force a garbage collection and generate a backtrace from a */
+/* random heap address. */
+/* This uses the GC logging mechanism (GC_printf) to produce */
+/* output. It can often be called from a debugger. The */
+/* source in dbg_mlc.c also serves as a sample client. */
+void GC_generate_random_backtrace(void);
+
+
/* This returns a list of objects, linked through their first */
/* word. Its use can greatly reduce lock contention problems, since */
/* the allocation lock can be acquired and released many fewer times. */
+/* lb must be large enough to hold the pointer field. */
GC_PTR GC_malloc_many(size_t lb);
#define GC_NEXT(p) (*(GC_PTR *)(p)) /* Retrieve the next element */
/* in returned list. */
void GC_print_static_roots();
void GC_dump();
+#ifdef KEEP_BACK_PTRS
+ void GC_store_back_pointer(ptr_t source, ptr_t dest);
+ void GC_marked_for_finalization(ptr_t dest);
+# define GC_STORE_BACK_PTR(source, dest) GC_store_back_pointer(source, dest)
+# define GC_MARKED_FOR_FINALIZATION(dest) GC_marked_for_finalization(dest)
+#else
+# define GC_STORE_BACK_PTR(source, dest)
+# define GC_MARKED_FOR_FINALIZATION(dest)
+#endif
+
/* Make arguments appear live to compiler */
# ifdef __WATCOMC__
void GC_noop(void*, ...);
# define OPENBSD
# define mach_type_known
# endif
-# if defined(__OpenBSD__) && defined(sparc)
+# if defined(__OpenBSD__) && defined(__sparc__)
# define SPARC
# define OPENBSD
# define mach_type_known
# endif
/* As above, but argument passed preliminary test. */
-# ifdef PRINT_BLACK_LIST
+# if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
void GC_push_one_checked(p, interior_ptrs, source)
ptr_t source;
# else
} 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[GC_mark_stack_size]));
}
# define NEED_FIND_LIMIT
# endif
-# if defined(LINUX) && (defined(POWERPC) || defined(SPARC))
+# if defined(LINUX) && (defined(POWERPC) || defined(SPARC) || defined(ALPHA))
# define NEED_FIND_LIMIT
# endif
# else
# include <sys/frame.h>
# endif
-# include <sys/frame.h>
# endif
# endif
# if NARGS > 6
int late_finalize_count = 0;
if (sizeof(char *) > 4) {
- max_heap_sz = 13000000;
+ max_heap_sz = 15000000;
} else {
max_heap_sz = 11000000;
}
#define GC_VERSION_MAJOR 5
#define GC_VERSION_MINOR 0
-#define GC_ALPHA_VERSION 1
+#define GC_ALPHA_VERSION 2
# define GC_NOT_ALPHA 0xff
projects / gc / commitdiff