+#if SU_HAS_PERL(5, 8, 9)
+# define SU_SKIP_DB_MAX 2
+#else
+# define SU_SKIP_DB_MAX 3
+#endif
+
+/* Skip context sequences of 1 to SU_SKIP_DB_MAX (included) block contexts
+ * followed by a DB sub */
+
+#define SU_SKIP_DB(C) \
+ STMT_START { \
+ I32 i = 1; \
+ PERL_CONTEXT *cx = cxstack + (C); \
+ do { \
+ if (CxTYPE(cx) == CXt_BLOCK && (C) >= i) { \
+ --cx; \
+ if (CxTYPE(cx) == CXt_SUB && cx->blk_sub.cv == GvCV(PL_DBsub)) { \
+ (C) -= i + 1; \
+ break; \
+ } \
+ } else \
+ break; \
+ } while (++i <= SU_SKIP_DB_MAX); \
+ } STMT_END
+
+#define SU_GET_CONTEXT(A, B) \
+ STMT_START { \
+ if (items > A) { \
+ SV *csv = ST(B); \
+ if (SvOK(csv)) \
+ cxix = SvIV(csv); \
+ if (cxix < 0) \
+ cxix = 0; \
+ else if (cxix > cxstack_ix) \
+ cxix = cxstack_ix; \
+ } else { \
+ cxix = cxstack_ix; \
+ if (PL_DBsub) \
+ SU_SKIP_DB(cxix); \
+ } \
+ } STMT_END
+
+#define SU_GET_LEVEL(A, B) \
+ STMT_START { \
+ if (items > 0) { \
+ SV *lsv = ST(B); \
+ if (SvOK(lsv)) \
+ level = SvIV(lsv); \
+ if (level < 0) \
+ level = 0; \
+ } else \
+ level = 0; \
+ } STMT_END
+
+XS(XS_Scope__Upper_unwind); /* prototype to pass -Wmissing-prototypes */
+
+XS(XS_Scope__Upper_unwind) {
+#ifdef dVAR
+ dVAR; dXSARGS;
+#else
+ dXSARGS;
+#endif
+ dMY_CXT;
+ I32 cxix;
+
+ PERL_UNUSED_VAR(cv); /* -W */
+ PERL_UNUSED_VAR(ax); /* -Wall */
+
+ SU_GET_CONTEXT(0, items - 1);
+ do {
+ PERL_CONTEXT *cx = cxstack + cxix;
+ switch (CxTYPE(cx)) {
+ case CXt_SUB:
+ if (PL_DBsub && cx->blk_sub.cv == GvCV(PL_DBsub))
+ continue;
+ case CXt_EVAL:
+ case CXt_FORMAT:
+ MY_CXT.cxix = cxix;
+ MY_CXT.items = items;
+ /* pp_entersub will want to sanitize the stack after returning from there
+ * Screw that, we're insane */
+ if (GIMME_V == G_SCALAR) {
+ MY_CXT.savesp = PL_stack_sp;
+ /* dXSARGS calls POPMARK, so we need to match PL_markstack_ptr[1] */
+ PL_stack_sp = PL_stack_base + PL_markstack_ptr[1] + 1;
+ } else {
+ MY_CXT.savesp = NULL;
+ }
+ SAVEDESTRUCTOR_X(su_unwind, NULL);
+ return;
+ default:
+ break;
+ }
+ } while (--cxix >= 0);
+ croak("Can't return outside a subroutine");
+}
+