[llvm] r320737 - Fix isPodLike for MSVC and use it in TypeHashing.

[Hans Wennborg via llvm-commits]

Thanks!

On Thu, Dec 14, 2017 at 12:01 PM, Zachary Turner <zturner at google.com> wrote:
> I reverted the static_assert and went back to the MSVC only check for now.
> I believe the static_assert holds, but isPodLike can't be correctly
> implemented everywhere so it's failing.
>
> On Thu, Dec 14, 2017 at 11:59 AM Hans Wennborg <hans at chromium.org> wrote:
>>
>> The static_assert doesn't hold in Chromium's Linux build:
>>
>>
>> https://logs.chromium.org/v/?s=chromium%2Fbb%2Fchromium.clang%2FToTLinuxThinLTO%2F933%2F%2B%2Frecipes%2Fsteps%2Fgclient_runhooks%2F0%2Fstdout
>>
>> Looks like some LLVM bots are sad too, e.g.
>>
>> http://lab.llvm.org:8011/builders/clang-atom-d525-fedora-rel/builds/12386/steps/build%20stage%201/logs/stdio
>>
>> On Thu, Dec 14, 2017 at 11:41 AM, Zachary Turner via llvm-commits
>> <llvm-commits at lists.llvm.org> wrote:
>> > Author: zturner
>> > Date: Thu Dec 14 11:41:28 2017
>> > New Revision: 320737
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=320737&view=rev
>> > Log:
>> > Fix isPodLike for MSVC and use it in TypeHashing.
>> >
>> > This should be a better check than using is_trivially_copyable
>> > behind an #ifdef _MSC_VER.
>> >
>> > Modified:
>> >     llvm/trunk/include/llvm/DebugInfo/CodeView/TypeHashing.h
>> >     llvm/trunk/include/llvm/Support/type_traits.h
>> >
>> > Modified: llvm/trunk/include/llvm/DebugInfo/CodeView/TypeHashing.h
>> > URL:
>> > http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/DebugInfo/CodeView/TypeHashing.h?rev=320737&r1=320736&r2=320737&view=diff
>> >
>> > ==============================================================================
>> > --- llvm/trunk/include/llvm/DebugInfo/CodeView/TypeHashing.h (original)
>> > +++ llvm/trunk/include/llvm/DebugInfo/CodeView/TypeHashing.h Thu Dec 14
>> > 11:41:28 2017
>> > @@ -132,15 +132,10 @@ struct GloballyHashedType {
>> >      return Hashes;
>> >    }
>> >  };
>> > -#if defined(_MSC_VER)
>> > -// is_trivially_copyable is not available in older versions of libc++,
>> > but it is
>> > -// available in all supported versions of MSVC, so at least this gives
>> > us some
>> > -// coverage.
>> > -static_assert(std::is_trivially_copyable<GloballyHashedType>::value,
>> > +static_assert(isPodLike<GloballyHashedType>::value,
>> >                "GloballyHashedType must be trivially copyable so that we
>> > can "
>> >                "reinterpret_cast arrays of hash data to arrays of "
>> >                "GloballyHashedType");
>> > -#endif
>> >  } // namespace codeview
>> >
>> >  template <> struct DenseMapInfo<codeview::LocallyHashedType> {
>> >
>> > Modified: llvm/trunk/include/llvm/Support/type_traits.h
>> > URL:
>> > http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/type_traits.h?rev=320737&r1=320736&r2=320737&view=diff
>> >
>> > ==============================================================================
>> > --- llvm/trunk/include/llvm/Support/type_traits.h (original)
>> > +++ llvm/trunk/include/llvm/Support/type_traits.h Thu Dec 14 11:41:28
>> > 2017
>> > @@ -30,9 +30,9 @@ namespace llvm {
>> >  template <typename T>
>> >  struct isPodLike {
>> >    // std::is_trivially_copyable is available in libc++ with clang,
>> > libstdc++
>> > -  // that comes with GCC 5.
>> > +  // that comes with GCC 5, and MSVC.
>> >  #if (__has_feature(is_trivially_copyable) && defined(_LIBCPP_VERSION))
>> > ||      \
>> > -    (defined(__GNUC__) && __GNUC__ >= 5)
>> > +    (defined(__GNUC__) && __GNUC__ >= 5) || defined(_MSC_VER)
>> >    // If the compiler supports the is_trivially_copyable trait use it,
>> > as it
>> >    // matches the definition of isPodLike closely.
>> >    static const bool value = std::is_trivially_copyable<T>::value;
>> >
>> >
>> > _______________________________________________
>> > llvm-commits mailing list
>> > llvm-commits at lists.llvm.org
>> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits