I guess I should find the time to finish the CAS primop work I volunteered to do then. Ill look into in a few days.
On Friday, July 19, 2013, Simon Marlow wrote:
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:
https://github.com/rrnewton/haskell-lockfree-queue/blob/87e63b21b2a6c375e93c30b98c28c1d04f88781c/AtomicPrimops/cbits/primops.cmm
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.
Cheers,
Simon
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