Proposal: provide cas and barriers symbols even without -threaded

Simon Marlow marlowsd at
Fri Jul 19 09:51:07 CEST 2013

On 18/07/13 14:17, Ryan Newton wrote:
> The "atomic-primops" library depends on symbols such as
> store_load_barrier and "cas", which are defined in SMP.h.  Thus the
> result is that if the program is linked WITHOUT "-threaded", the user
> gets a linker error about undefined symbols.
> The specific place it's used is in the 'foreign "C"' bits of this .cmm code:
> I'm trying to explore hacks that will enable me to pull in those
> functions during compile time, without duplicating a whole bunch of code
> from the RTS.  But it's a fragile business.
> It seems to me that some of these routines have general utility.  In
> future versions of GHC, could we consider linking in those routines
> irrespective of "-threaded"?

We should make the non-THREADED versions EXTERN_INLINE too, so that 
there will be (empty) functions to call in rts/Inlines.c.  Want to 
submit a patch?

A better solution would be to make them into primops.  You don't really 
want to be calling out to a C function to implement a memory barrier. 
We have this for write_barrier(), but none of the others so far.  Of 
couse that's a larger change.


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