cx->stackLimit = stackSizeLimit ? (jsuword)&stackDummy + stackSizeLimit
cx->stackLimit = (stackAddr + stackSizeLimit > stackAddr) ? stackAddr + stackSizeLimit
js_SetStackSizeLimit(JSContext *cx, jsuword stackSizeLimit){    int stackDummy;#ifdef DEBUG    CheckStackGrowthDirection(&stackDummy);#endif#if JS_STACK_GROWTH_DIRECTION > 0    cx->stackLimit = stackSizeLimit                     ? (jsuword)&stackDummy + stackSizeLimit                     : (jsuword)-1;#else    cx->stackLimit = stackSizeLimit                     ? (jsuword)&stackDummy - stackSizeLimit                     : 0;#endif}