annotate functions to blacklist MSAN

In these functions we are intentionally reading memory address
not owned by us.  These reads should not be diagnosed.

See also [Bug #8680]
See also https://travis-ci.org/ruby/ruby/jobs/451202718



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65564 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

gc.c

@@ -864,7 +864,7 @@ static void gc_sweep_continue(rb_objspace_t *objspace, rb_heap_t *heap);
 
 static inline void gc_mark(rb_objspace_t *objspace, VALUE ptr);
 static void gc_mark_ptr(rb_objspace_t *objspace, VALUE ptr);
-static void gc_mark_maybe(rb_objspace_t *objspace, VALUE ptr);
+NO_SANITIZE("memory", static void gc_mark_maybe(rb_objspace_t *objspace, VALUE ptr));
 static void gc_mark_children(rb_objspace_t *objspace, VALUE ptr);
 
 static int gc_mark_stacked_objects_incremental(rb_objspace_t *, size_t count);
@@ -872,7 +872,7 @@ static int gc_mark_stacked_objects_all(rb_objspace_t *);
 static void gc_grey(rb_objspace_t *objspace, VALUE ptr);
 
 static inline int gc_mark_set(rb_objspace_t *objspace, VALUE obj);
-static inline int is_pointer_to_heap(rb_objspace_t *objspace, void *ptr);
+NO_SANITIZE("memory", static inline int is_pointer_to_heap(rb_objspace_t *objspace, void *ptr));
 
 static void   push_mark_stack(mark_stack_t *, VALUE);
 static int    pop_mark_stack(mark_stack_t *, VALUE *);

internal.h

@@ -68,6 +68,10 @@ extern "C" {
 # define ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS(x) x
 #endif
 
+#ifndef NO_SANITIZE
+#define NO_SANITIZE(x, y)
+#endif
+
 #ifdef HAVE_VALGRIND_MEMCHECK_H
 # include <valgrind/memcheck.h>
 # ifndef VALGRIND_MAKE_MEM_DEFINED