MARK -Ds debugging

display the MARK arity and pointers with MARK macros.
assert on markptr underflow.

1 files changed, 2 insertions, 0 deletions

diff --git a/scope.c b/scope.c
index bdf299a9c4..037bbc00fd 100644
--- a/scope.c
+++ b/scope.c
@@ -131,6 +131,8 @@ Perl_markstack_grow(pTHX)
     Renew(PL_markstack, newmax, I32);
     PL_markstack_max = PL_markstack + newmax;
     PL_markstack_ptr = PL_markstack + oldmax;
+    DEBUG_s(PerlIO_printf(Perl_debug_log, "MARK grow %p %d by %d\n",
+            PL_markstack_ptr, *PL_markstack_ptr, oldmax));
     return PL_markstack_ptr;
 }