diff options
Diffstat (limited to 'compiler/codeGen')
| -rw-r--r-- | compiler/codeGen/StgCmmClosure.hs | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/compiler/codeGen/StgCmmClosure.hs b/compiler/codeGen/StgCmmClosure.hs index b65d56bae2..984e704e3a 100644 --- a/compiler/codeGen/StgCmmClosure.hs +++ b/compiler/codeGen/StgCmmClosure.hs @@ -754,6 +754,16 @@ mkClosureInfo dflags is_static id lf_info tot_wds ptr_wds val_descr -- was on. But it didn't work, and it wasn't strictly necessary -- to bring back minimal ticky-ticky, so now EAGER_BLACKHOLING -- is unconditionally disabled. -- krc 1/2007 +-- +-- +-- A single-entry (non-updatable) thunk can actually be entered +-- more than once in a parallel program, if work is duplicated +-- by two threads both entering the same updatable thunk before +-- the other has blackholed it. So, we must not eagerly +-- blackhole non-updatable thunks, or the second thread to +-- enter one will become blocked indefinitely. (They are not +-- blackholed by lazy blackholing either, since they have no +-- associated update frame.) See Trac #10414. -- Static closures are never themselves black-holed. @@ -766,7 +776,7 @@ blackHoleOnEntry cl_info = case closureLFInfo cl_info of LFReEntrant _ _ _ _ -> False LFLetNoEscape -> False - LFThunk _ _no_fvs _updatable _ _ -> True + LFThunk _ _no_fvs updatable _ _ -> updatable _other -> panic "blackHoleOnEntry" -- Should never happen isStaticClosure :: ClosureInfo -> Bool |