On Thu, 15 Jun 2023, Ken Matsui via Libstdc++ wrote: > Hi, > > For those curious about the performance improvements of this patch, I > conducted a benchmark that instantiates 256k specializations of > is_object_v based on Patrick's code. You can find the benchmark code > at this link: > > https://github.com/ken-matsui/gcc-benches/blob/main/is_object_benchmark.cc > > On my computer, using the gcc HEAD of this patch for a release build, > the patch with -DUSE_BUILTIN took 64% less time and used 44-47% less > memory compared to not using it.
That's more like it :D Though the benchmark should also invoke the trait on non-object types too, e.g. Instantiator& or Instantiator(int). > > Sincerely, > Ken Matsui > > On Mon, Jun 12, 2023 at 3:49 PM Ken Matsui <kmat...@cs.washington.edu> wrote: > > > > Hi, > > > > This patch series gets std::is_object to dispatch to built-in traits and > > implements the following built-in traits, on which std::object depends. > > > > * __is_reference > > * __is_function > > * __is_void > > > > std::is_object was depending on them with disjunction and negation. > > > > __not_<__or_<is_function<_Tp>, is_reference<_Tp>, is_void<_Tp>>>::type > > > > Therefore, this patch uses them directly instead of implementing an > > additional > > built-in trait __is_object, which makes the compiler slightly bigger and > > slower. > > > > __bool_constant<!(__is_function(_Tp) || __is_reference(_Tp) || > > __is_void(_Tp))> > > > > This would instantiate only __bool_constant<true> and > > __bool_constant<false>, > > which can be mostly shared. That is, the purpose of built-in traits is > > considered as achieved. > > > > Changes in v7 > > > > * Removed an unnecessary new line. > > > > Ken Matsui (6): > > c++: implement __is_reference built-in trait > > libstdc++: use new built-in trait __is_reference for std::is_reference > > c++: implement __is_function built-in trait > > libstdc++: use new built-in trait __is_function for std::is_function > > c++, libstdc++: implement __is_void built-in trait > > libstdc++: make std::is_object dispatch to new built-in traits > > > > gcc/cp/constraint.cc | 9 +++ > > gcc/cp/cp-trait.def | 3 + > > gcc/cp/semantics.cc | 12 ++++ > > gcc/testsuite/g++.dg/ext/has-builtin-1.C | 9 +++ > > gcc/testsuite/g++.dg/ext/is_function.C | 58 +++++++++++++++++++ > > gcc/testsuite/g++.dg/ext/is_reference.C | 34 +++++++++++ > > gcc/testsuite/g++.dg/ext/is_void.C | 35 +++++++++++ > > gcc/testsuite/g++.dg/tm/pr46567.C | 6 +- > > libstdc++-v3/include/bits/cpp_type_traits.h | 15 ----- > > libstdc++-v3/include/debug/helper_functions.h | 5 +- > > libstdc++-v3/include/std/type_traits | 51 ++++++++++++++++ > > 11 files changed, 216 insertions(+), 21 deletions(-) > > create mode 100644 gcc/testsuite/g++.dg/ext/is_function.C > > create mode 100644 gcc/testsuite/g++.dg/ext/is_reference.C > > create mode 100644 gcc/testsuite/g++.dg/ext/is_void.C > > > > -- > > 2.41.0 > > > >
