The thing is, the code is already full of data races. I think the std::atomic is actually used incorrectly and is not even doing anything.
That said, consider darwin on 32-bit, where I believe each stack frame is 4-byte aligned. I dont' think there's any way the compiler can guarantee that a function parameter is 8-byte aligned without allocating from the heap, which is obviously impossible for a stack variable. On Fri, Aug 26, 2016 at 11:29 AM Greg Clayton <gclay...@apple.com> wrote: > > > On Aug 26, 2016, at 11:24 AM, Greg Clayton via lldb-dev < > lldb-dev@lists.llvm.org> wrote: > > > >> > >> On Aug 26, 2016, at 10:51 AM, Zachary Turner via lldb-dev < > lldb-dev@lists.llvm.org> wrote: > >> > >> I recently updated to Visual Studio 2015 Update 3, which has improved > its diagnostics. As a result of this, LLDB is uncompilable due to a slew > of errors of the following nature: > >> > >> D:\src\llvm\tools\lldb\include\lldb/Target/Process.h(3256): error > C2719: 'default_stop_addr': formal parameter with requested alignment of 8 > won't be aligned > >> > >> The issue comes down to the fact that lldb::Address contains a > std::atomic<uint64_t>, and is being passed by value pervasively throughout > the codebase. There is no way to guarantee that this value is 8 byte > aligned. This has always been a bug, but until now the compiler just > hasn't been reporting it. > >> > >> Someone correct me if I'm wrong, but I believe this is a problem on any > 32-bit platform, and MSVC is just the only one erroring. > >> > >> I'm not really sure what to do about this. Passing > std::atomic<uint64>'s by value seems wrong to me. > >> > >> Looking at the code, I don't even know why it needs to be atomic. It's > not even being used safely. We'll have a single function write the value > and later read the value, even though it could have been used in the > meantime. Maybe what is really intended is a mutex. Or maybe it doesn't > need to be atomic in the first place. > >> > >> Does anyone have a suggestion on what to do about this? I'm currently > blocked on this as I can't compile LLDB. > > > > Feel free to #ifdef around the m_offset member of Address and you can > have the data race and compile. This seems like a compiler bug to me. If a > struct/classe by value argument has alignment requirements, then the > compiler should handle this correctly IMHO. Am I wrong???? > > Or if this isn't a compiler bug, feel free to modify anything that was > passing Address by value and make it a "const Address &".
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