rnk accepted this revision. rnk added a comment. This revision is now accepted and ready to land.
lgtm ================ Comment at: lib/CodeGen/CGBuiltin.cpp:570 + llvm::AtomicOrdering::SequentiallyConsistent); + llvm::Value *Shifted = Builder.CreateLShr(RMWI, Bit); + llvm::Value *Truncated = ---------------- hans wrote: > rnk wrote: > > Can you comment that this shifts the relevant bit into the low bit, > > truncates to i8, and then tests the low bit? At first I was thinking "of > > course, we just do AND %old, $constant to test the bit". > > > > Do we successfully pattern match this idiom to `lock bts`? Is there a > > pattern match we should target? > Added the comment. > > No, we generate horrible code for this, but it's the same as we did for the > inline version in intrin.h. We have BTS instructions in the .td file, but no > patterns for them. > > I thought a bit about adding a pattern match for this, but I'm not sure it > would be worth the effort. Let's file a bug for it and call it a day. https://reviews.llvm.org/D31736 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
