mgorny added a comment. In https://reviews.llvm.org/D28213#666269, @dim wrote:
> > What's the value of `__atomic_always_lock_free(sizeof(long long), 0)` for > > gcc and clang? > > For gcc, it is always 0, for clang (I tested 3.4.1 through 4.0.0) it is > always 1. Maybe that was always incorrect on 32-bit FreeBSD, then? That's what I suspected. Yeah, looks like clang always made the wrong assumption and possibly someone just swept it under the carpet. In https://reviews.llvm.org/D28213#666352, @dim wrote: > Hmm, I just noticed the following rather disappointing comment in > `tools/clang/lib/Basic/Targets.cpp`: > > X86_32TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts) > : X86TargetInfo(Triple, Opts) { > [...] > // x86-32 has atomics up to 8 bytes > // FIXME: Check that we actually have cmpxchg8b before setting > // MaxAtomicInlineWidth. (cmpxchg8b is an i586 instruction.) > MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64; > > > So this can never have worked properly for e.g. i486 and i586... Yep, looks like it. I see that the triple is passed there, so I guess making that conditional to `>=i586-*` should be relatively easy. However, I don't know how to make it properly respect `-march`. Repository: rL LLVM https://reviews.llvm.org/D28213 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
