int stk_offset = BCO_NEXT;
int o_itbl = BCO_NEXT;
void(*marshall_fn)(void*) = (void (*)(void*))BCO_LIT(o_itbl);
- StgTSO *tso = cap->r.rCurrentTSO;
+#ifdef RTS_SUPPORTS_THREADS
+ // Threaded RTS:
+ // Arguments on the TSO stack are not good, because garbage
+ // collection might move the TSO as soon as we call
+ // suspendThread below.
+
+ W_ arguments[stk_offset];
+
+ memcpy(arguments, Sp, sizeof(W_) * stk_offset);
+#endif
+
// There are a bunch of non-ptr words on the stack (the
// ccall args, the ccall fun address and space for the
// result), which we need to cover with an info table
SAVE_STACK_POINTERS;
tok = suspendThread(&cap->r,rtsFalse);
+#ifndef RTS_SUPPORTS_THREADS
// Careful:
// suspendThread might have shifted the stack
// around (stack squeezing), so we have to grab the real
// Sp out of the TSO to find the ccall args again.
- // We don't own the capability anymore, so we mustn't use it.
- // Instead, we have to save the TSO ptr beforehand.
- // Also note that GC may strike at any time now (from another thread).
- // FIXME - DANGER!! Can GC move our TSO?
- // If so, we have to copy the args elsewhere!
- marshall_fn ( (void*)(tso->sp + RET_DYN_SIZE + sizeofW(StgRetDyn)) );
-
+
+ marshall_fn ( (void*)(cap->r.rCurrentTSO->sp + RET_DYN_SIZE + sizeofW(StgRetDyn)) );
+#else
+ // Threaded RTS:
+ // We already made a malloced copy of the arguments above.
+
+ marshall_fn ( arguments );
+#endif
+
// And restart the thread again, popping the RET_DYN frame.
cap = (Capability *)((void *)resumeThread(tok,rtsFalse) - sizeof(StgFunTable));
LOAD_STACK_POINTERS;
Sp += RET_DYN_SIZE + sizeofW(StgRetDyn);
+
+
+#ifdef RTS_SUPPORTS_THREADS
+ // Threaded RTS:
+ // Copy the "arguments", which might include a return value,
+ // back to the TSO stack. It would of course be enough to
+ // just copy the return value, but we don't know the offset.
+ memcpy(Sp, arguments, sizeof(W_) * stk_offset);
+#endif
+
goto nextInsn;
}