jyknight added a comment. In D71726#2165445 <https://reviews.llvm.org/D71726#2165445>, @yaxunl wrote:
> In D71726#2165424 <https://reviews.llvm.org/D71726#2165424>, @jyknight wrote: > > > Why not have clang always emit atomicrmw for floats, and let > > AtomicExpandPass handle legalizing that into integer atomics if necessary, > > rather than adding a target hook in clang? > > > Not all targets can legalize fp atomics by AtomicExpandPass. Some targets > need library support. That isn't true, because you can do so generically with a cmpxchg loop, assuming that size of atomic is supported by the target. This might not be the most efficient lowering choice, but it's always possible as a fallback. (And if the size is too large, then AtomicExpandPass will lower the cmpxchg to the libatomic call.) If a target wants to tell AtomicExpandPass that fp add/sub are supported, and then lower the resulting ATOMIC_LOAD_FSUB sdag node into a libcall of its choice, that's also ok (as long as the libcall is lock-free). CHANGES SINCE LAST ACTION https://reviews.llvm.org/D71726/new/ https://reviews.llvm.org/D71726 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
