jfb added a comment. In D71600#1816834 <https://reviews.llvm.org/D71600#1816834>, @adalava wrote:
> In D71600#1816160 <https://reviews.llvm.org/D71600#1816160>, @MaskRay wrote: > > > I am still confused why you need the special rule for > > `__atomic_is_lock_free` (GCC/clang) and `__c11_atomic_is_lock_free` (clang). > > > > https://github.com/gcc-mirror/gcc/blob/master/gcc/builtins.c#L7300-L7314 > > GCC `__atomic_is_lock_free` expands to either 1 or a library call to > > `__atomic_is_lock_free`, never 0. How did FreeBSD get around libatomic when > > it was still using GCC? In clang, We can probably extend the semantics of > > `__c11_atomic_is_lock_free` and use > > `clang::TargetInfo::getMaxAtomicPromoteWidth`, but I'll make more research > > in this area. > > > > Can you be elaborate how do > > `__atomic_is_lock_free`/`__c11_atomic_is_lock_free` pull in > > libatomic.{a,so} dependency on FreeBSD powerpc? > > > On FreeBSD 11.x/12.x (GCC4), libatomic can be installed by user through > "gcc9" ports package. The library is not shipped with the base system and > it's not required to compile the base system (world + kernel) since nothing > depends on 64 bit atomics an external call so `__atomic_is_lock_free` is > never made. > > The problem appeared when I switched to clang in a new ISO, this added an > undesired external libatomic dependency to build FreeBSD base sources > (world): clang was emitting a call to external `__atomic_is_lock_free` > implementation when building clang itself from base sources. (user would need > to install gcc9 to be able to build FreeBSD base source using clang, it's not > acceptable. I'm curious about this: what part of clang makes it emit a call to `is_lock_free`? clang itself probably shouldn't be doing this, so maybe we should fix that issue as well. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D71600/new/ https://reviews.llvm.org/D71600 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
