FILL_SLOP: don't fill slop for BLACKHOLE/CAF_BLACKHOLE

This affects -debug only, avoids crash with test conc012.

diff --git a/rts/Updates.h b/rts/Updates.h
index 2456f12..abca788 100644 (file)
--- a/rts/Updates.h
+++ b/rts/Updates.h
@@ -233,6 +233,10 @@ FILL_SLOP(StgClosure *p)
     switch (inf->type) {
     case BLACKHOLE:
     case CAF_BLACKHOLE:
+       goto no_slop;
+       // we already filled in the slop when we overwrote the thunk
+       // with BLACKHOLE, and also an evacuated BLACKHOLE is only the
+       // size of an IND.
     case THUNK_SELECTOR:
        sz = sizeofW(StgSelector) - sizeofW(StgThunkHeader);
        break;
@@ -249,6 +253,8 @@ FILL_SLOP(StgClosure *p)
     for (i = 0; i < sz; i++) {
        ((StgThunk *)p)->payload[i] = 0;
     }
+no_slop:
+    ;
 }
 
 #endif /* CMINUSMINUS */