mgorny added a comment. In https://reviews.llvm.org/D29542#666831, @jlebar wrote:
> > Could someone help me figure out what is the cause and correct solution to > > that failure? @jlebar? > > You can see in NVPTXTargetInfo that we read properties from the host > targetinfo so that we export the same macros. The problem here seems to be > that we're mutating the x86 targetinfo after the nvptx targetinfo reads its > properties. > > Does that give you enough context to fix the problem? Thanks. I'll try to find a reasonably sane solution ;-). ================ Comment at: lib/Basic/Targets.cpp:4244 + } else // allow locked atomics up to 4 bytes + MaxAtomicPromoteWidth = 32; + } ---------------- dim wrote: > Are you purposefully not setting `MaxAtomicInlineWidth` here? (It seems from > `TargetInfo` that the default value is zero.) > Yes. I've based this on what's done for ARM. Unless I misunderstood something, this means that on 'plain' i386 there is no inline atomics support but we still want to do atomics-via-locking up to 32-bit types. I'm not sure about 32/64 here to match i486. ================ Comment at: lib/Basic/Targets.cpp:4265 - // 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; + setAtomic(); } ---------------- dim wrote: > As far as I can see, in the constructor this call is _always_ made with `CPU` > set to `CK_Generic`, i.e. zero. Therefore, the "allow locked atomics up to 4 > bytes" path in `setAtomic` is always chosen. Maybe it is clearer to just > initialize `MaxAtomicPromoteWidth` to 32 directly here, instead? > Well, I just copied the idea from ARM. I thought of it more like 'make sure it is initialized to some value, possibly update it later when setting CPU'. I'm fine either way. Repository: rL LLVM https://reviews.llvm.org/D29542 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
