diff options
Diffstat (limited to '')
| -rw-r--r-- | gc/include/private/dbg_mlc.h | 53 |
1 files changed, 34 insertions, 19 deletions
diff --git a/gc/include/private/dbg_mlc.h b/gc/include/private/dbg_mlc.h index 6f5b3c8..5378835 100644 --- a/gc/include/private/dbg_mlc.h +++ b/gc/include/private/dbg_mlc.h @@ -46,7 +46,8 @@ /* Stored both one past the end of user object, and one before */ /* the end of the object as seen by the allocator. */ -# if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST) +# if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST) \ + || defined(MAKE_BACK_GRAPH) /* Pointer "source"s that aren't real locations. */ /* Used in oh_back_ptr fields and as "source" */ /* argument to some marking functions. */ @@ -60,28 +61,42 @@ /* Object header */ typedef struct { -# ifdef KEEP_BACK_PTRS - GC_hidden_pointer oh_back_ptr; - /* We make sure that we only store even valued */ - /* pointers here, so that the hidden version has */ - /* the least significant bit set. We never */ - /* overwrite a value with the least significant */ - /* bit clear, thus ensuring that we never overwrite */ - /* a free list link field. */ - /* Note that blocks dropped by black-listing will */ - /* also have the lsb clear once debugging has */ - /* started. */ - /* The following are special back pointer values. */ - /* Note that the "hidden" (i.e. bitwise */ - /* complemented version) of these is actually */ - /* stored. */ +# if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH) + /* We potentially keep two different kinds of back */ + /* pointers. KEEP_BACK_PTRS stores a single back */ + /* pointer in each reachable object to allow reporting */ + /* of why an object was retained. MAKE_BACK_GRAPH */ + /* builds a graph containing the inverse of all */ + /* "points-to" edges including those involving */ + /* objects that have just become unreachable. This */ + /* allows detection of growing chains of unreachable */ + /* objects. It may be possible to eventually combine */ + /* both, but for now we keep them separate. Both */ + /* kinds of back pointers are hidden using the */ + /* following macros. In both cases, the plain version */ + /* is constrained to have an least significant bit of 1,*/ + /* to allow it to be distinguished from a free list */ + /* link. This means the plain version must have an */ + /* lsb of 0. */ + /* Note that blocks dropped by black-listing will */ + /* also have the lsb clear once debugging has */ + /* started. */ + /* We're careful never to overwrite a value with lsb 0. */ # if ALIGNMENT == 1 /* Fudge back pointer to be even. */ # define HIDE_BACK_PTR(p) HIDE_POINTER(~1 & (GC_word)(p)) # else # define HIDE_BACK_PTR(p) HIDE_POINTER(p) # endif -# ifdef ALIGN_DOUBLE + +# ifdef KEEP_BACK_PTRS + GC_hidden_pointer oh_back_ptr; +# endif +# ifdef MAKE_BACK_GRAPH + GC_hidden_pointer oh_bg_ptr; +# endif +# if defined(ALIGN_DOUBLE) && \ + (defined(KEEP_BACK_PTRS) != defined(MAKE_BACK_GRAPH)) word oh_dummy; # endif # endif @@ -139,9 +154,9 @@ typedef struct { GC_bool GC_has_other_debug_info(/* p */); #endif -#ifdef KEEP_BACK_PTRS +#if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH) # define GC_HAS_DEBUG_INFO(p) \ - ((((oh *)p)->oh_back_ptr & 1) && GC_has_other_debug_info(p)) + ((*((word *)p) & 1) && GC_has_other_debug_info(p)) #else # define GC_HAS_DEBUG_INFO(p) GC_has_other_debug_info(p) #endif |