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9b0be04)
There was already a check to avoid updating an IND, but it was
originally there to avoid a bug which doesn't exist now. Furthermore
the test and update are not atomic, so another thread could be
updating this thunk while we are. We have to just go ahead and update
anyway - it might waste a little work, but this is a very rare case.
// printObj((StgClosure *)ap);
// );
// printObj((StgClosure *)ap);
// );
- // Replace the updatee with an indirection
- //
- // Warning: if we're in a loop, more than one update frame on
- // the stack may point to the same object. Be careful not to
- // overwrite an IND_OLDGEN in this case, because we'll screw
- // up the mutable lists. To be on the safe side, don't
- // overwrite any kind of indirection at all. See also
- // threadSqueezeStack in GC.c, where we have to make a similar
- // check.
- //
- if (!closure_IND(((StgUpdateFrame *)frame)->updatee)) {
- // revert the black hole
- UPD_IND_NOLOCK(((StgUpdateFrame *)frame)->updatee,
- (StgClosure *)ap);
- }
+ // Perform the update
+ // TODO: this may waste some work, if the thunk has
+ // already been updated by another thread.
+ UPD_IND_NOLOCK(((StgUpdateFrame *)frame)->updatee,
+ (StgClosure *)ap);
+
sp += sizeofW(StgUpdateFrame) - 1;
sp[0] = (W_)ap; // push onto stack
frame = sp + 1;
sp += sizeofW(StgUpdateFrame) - 1;
sp[0] = (W_)ap; // push onto stack
frame = sp + 1;
- /* cas(p1, 0, &stg_WHITEHOLE_info); */ \
- ASSERT( (P_)p1 != (P_)p2 && !closure_IND(p1) ); \
+ ASSERT( (P_)p1 != (P_)p2 ); \
+ /* not necessarily true: ASSERT( !closure_IND(p1) ); */ \
+ /* occurs in RaiseAsync.c:raiseAsync() */ \
DEBUG_FILL_SLOP(p1); \
LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(p1); \
((StgInd *)p1)->indirectee = p2; \
DEBUG_FILL_SLOP(p1); \
LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(p1); \
((StgInd *)p1)->indirectee = p2; \