Refine comparisons to GC_greatest_plausible_heap_addr

GC_greatest_plausible_heap_addr should always be greater (strictly)
than any address of a heap object.

* backgraph.c (add_back_edges): Check that pointer is strictly less
than GC_greatest_plausible_heap_addr (instead of less or equal).
* dbg_mlc.c [KEEP_BACK_PTRS && ALIGNMENT==1] (GC_get_back_ptr_info):
Likewise.
* include/gc/gc_mark.h (GC_MARK_AND_PUSH): Likewise.
* malloc.c (GC_malloc_kind_global): Likewise.
* typd_mlc.c (GC_typed_mark_proc): Likewise.
* include/gc/gc_mark.h (GC_greatest_plausible_heap_addr): Refine
comment (that any object address is strictly less).
* mark.c (GC_mark_from): Allow descr in assertions to be equal to
GC_greatest_plausible_heap_addr-GC_least_plausible_heap_addr; reformat
comment.

1 files changed, 2 insertions, 2 deletions

diff --git a/dbg_mlc.c b/dbg_mlc.c
index c290f81a..7c528739 100644
--- a/dbg_mlc.c
+++ b/dbg_mlc.c
@@ -134,9 +134,9 @@
         ptr_t alternate_target = *(ptr_t *)alternate_ptr;
 
         if ((word)alternate_target >= (word)GC_least_plausible_heap_addr
-            && (word)alternate_target <= (word)GC_greatest_plausible_heap_addr
+            && (word)alternate_target < (word)GC_greatest_plausible_heap_addr
             && ((word)target < (word)GC_least_plausible_heap_addr
-                || (word)target > (word)GC_greatest_plausible_heap_addr)) {
+                || (word)target >= (word)GC_greatest_plausible_heap_addr)) {
             bp = alternate_ptr;
         }
       }