Remove some guard errors.

lib/coll.gd

@@ -580,7 +580,7 @@ BIND_GLOBAL( "InstallSubsetMaintenance",
     # (We must not call `SUBTR_SET' here because the lists types may be
     # not yet defined.)
     filtssub:= [];
-    atomic readwrite SUBSET_MAINTAINED_INFO do
+    atomic readwrite SUBSET_MAINTAINED_INFO, readonly FILTER_REGION do
     for flag in TRUES_FLAGS( FLAGS_FILTER( sub_req ) ) do
       if not INFO_FILTERS[flag] in FNUM_CATS_AND_REPS then
         ADD_LIST_DEFAULT( filtssub, flag );

lib/filter.g

@@ -509,8 +509,10 @@ BIND_GLOBAL( "RankFilter", function( filter )
     else
       all := WITH_IMPS_FLAGS(flags);
     fi;
-    for i  in TRUES_FLAGS(all)  do
-        rank := rank + RANK_FILTERS[i];
+    atomic readonly FILTER_REGION do
+      for i  in TRUES_FLAGS(all)  do
+	  rank := rank + RANK_FILTERS[i];
+      od;
     od;
     return rank;
 end );

lib/oper.g

@@ -292,6 +292,8 @@ BIND_GLOBAL( "INSTALL_IMMEDIATE_METHOD",
         Error( "no immediate methods for mutable objects!" );
     fi;
     relev := [];
+    atomic FILTER_REGION do
+
     for i  in flags  do
         if not INFO_FILTERS[i] in FNUM_CATS_AND_REPS  then
             ADD_LIST( relev, i );
@@ -305,8 +307,6 @@ BIND_GLOBAL( "INSTALL_IMMEDIATE_METHOD",
     fi;
     flags:= relev;
 
-    atomic FILTER_REGION do
-
     # Remove requirements that are implied by the remaining ones.
     # (Note that it is possible to have implications from a filter
     # to another one with a bigger number.)

src/opers.c

@@ -741,6 +741,9 @@ Obj FuncWITH_HIDDEN_IMPS_FLAGS(Obj self, Obj flags)
             "you can replace <flags> via 'return <flags>;'" );
     }
 
+#ifdef HPCGAP
+    RegionWriteLock(REGION(WITH_HIDDEN_IMPS_FLAGS_CACHE));
+#endif
     Int changed, i, lastand, stop;
     Int hidden_imps_length = LEN_PLIST(HIDDEN_IMPS) / 2;
     Int base_hash = INT_INTOBJ(FuncHASH_FLAGS(0, flags)) % HIDDEN_IMPS_CACHE_LENGTH;
@@ -751,9 +754,6 @@ Obj FuncWITH_HIDDEN_IMPS_FLAGS(Obj self, Obj flags)
     Int old_moving;
     Obj with = flags;
 
-#ifdef HPCGAP
-    RegionWriteLock(REGION(WITH_HIDDEN_IMPS_FLAGS_CACHE));
-#endif
     for(hash_loop = 0; hash_loop < 3; ++hash_loop)
     {
       cacheval = ELM_PLIST(WITH_HIDDEN_IMPS_FLAGS_CACHE, hash*2+1);