- // Check for stack overflow.
- STK_CHK_GEN(Words+sizeofW(StgUpdateFrame), R1_PTR, stg_AP_entry);
+ // Check for stack overflow. IMPORTANT: use a _NP check here,
+ // because if the check fails, we might end up blackholing this very
+ // closure, in which case we must enter the blackhole on return rather
+ // than continuing to evaluate the now-defunct closure.
+ STK_CHK_NP(Words+sizeofW(StgUpdateFrame),);