+
+ case OP_SASSIGN: {
+ OP *rv2gv;
+ UNOP *refgen, *rv2cv;
+ LISTOP *exlist;
+
+ /* I do not understand this, but if o->op_opt isn't set to 1,
+ various tests in ext/B/t/bytecode.t fail with no readily
+ apparent cause. */
+
+ o->op_opt = 1;
+
+
+ if ((o->op_flags && OPf_WANT) != OPf_WANT_VOID)
+ break;
+
+ if ((o->op_private & ~OPpASSIGN_BACKWARDS) != 2)
+ break;
+
+ rv2gv = ((BINOP *)o)->op_last;
+ if (!rv2gv || rv2gv->op_type != OP_RV2GV)
+ break;
+
+ refgen = (UNOP *)((BINOP *)o)->op_first;
+
+ if (!refgen || refgen->op_type != OP_REFGEN)
+ break;
+
+ exlist = (LISTOP *)refgen->op_first;
+ if (!exlist || exlist->op_type != OP_NULL
+ || exlist->op_targ != OP_LIST)
+ break;
+
+ if (exlist->op_first->op_type != OP_PUSHMARK)
+ break;
+
+ rv2cv = (UNOP*)exlist->op_last;
+
+ if (rv2cv->op_type != OP_RV2CV)
+ break;
+
+ assert ((rv2gv->op_private & OPpDONT_INIT_GV) == 0);
+ assert ((o->op_private & OPpASSIGN_CV_TO_GV) == 0);
+ assert ((rv2cv->op_private & OPpMAY_RETURN_CONSTANT) == 0);
+
+ o->op_private |= OPpASSIGN_CV_TO_GV;
+ rv2gv->op_private |= OPpDONT_INIT_GV;
+ rv2cv->op_private |= OPpMAY_RETURN_CONSTANT;
+
+ break;
+ }
+