rjmccall wrote: > > On the target hook, it's a shame we can't easily get this information from > > LLVM. I believe it's already there — `TargetLowering` has an > > `allowsMisalignedMemoryAccesses` method that includes some approximation of > > how fast a particular access would be. In practice, it seems to be quite > > complex and often specific to the type and subtarget. Maybe it'd be worth > > starting a conversation with LLVM folks to see if this could reasonably be > > lifted somewhere we could use it? > > Agreed, I did look at that, and AFAICT the allowsMisalignedMemoryAccess is a > property of the llvm subtarget, which can, IIUC, change on a per-function > basis? One at least needs a function codegen context around? And, clang needs > to generate the llvm-structure in non-function contexts (eg namespace-scope > variables). I'd really like to not tangle this particular change with a > complex reorg.
Yeah, LLVM supports changing subtarget options on a per-function basis. We would presumably make the query based on the global setting. Anyway, getting this information from LLVM doesn't seem tractable in the short-to-medium term; it's just unfortunate. https://github.com/llvm/llvm-project/pull/65742 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
