pytorch

7671c15d - Make VariableVersion::DISABLED the default constructor for VariableVersion. (#55572)

Make VariableVersion::DISABLED the default constructor for VariableVersion. (#55572) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/55572 We used to have VariableVersion default constructor `VariableVersion(uint32_t version=0)`. But sometimes we override the version_counter right after it's constructed. E.g in SavedVariable/TensorImpl. Thus we should make DISABLED the default constructor and else where using explicit `VariableVersion(uint32_t)` constructor. Note this PR effectively changes SavedVariable constructor (which overrides version_counter_ inside) to use the DISABLED constructor and we can see the gains in reduced instruction counts. ``` // benchmark code timer = Timer( "y = x * x", """ x = torch.rand((3, 3)).requires_grad_() """, language=Language.PYTHON, ) λ ~ python compare.py No CUDA runtime is found, using CUDA_HOME='/public/apps/cuda/10.2' <torch.utils.benchmark.utils.valgrind_wrapper.timer_interface.FunctionCounts object at 0x7f06c48b3a50> 7236 lookdict_unicode_nodummy 2600 torch::autograd::VariableType::(...) 100 0x0000000017751750 -5 unlink_chunk.isra.0 -100 0x000000001773e750 -402 _int_malloc -1600 operator delete(...) -1600 c10::intrusive_ptr_target::release_resources() -2400 c10::VariableVersion::VersionCounter::~VersionCounter() -3600 torch::autograd::SavedVariable::operator=(...) -4800 operator new(...) -6400 torch::autograd::SavedVariable::SavedVariable(...) -7200 torch::autograd::SavedVariable::SavedVariable() -8400 free -16800 malloc -24400 _int_free Total: -67771 ``` Note there're for other callsites(esp. view related) we just keep it unchanged by explicitly calling `VariableVersion(uint32_t)` but we should be able to optimize those in the followup PRs. Test Plan: Imported from OSS Reviewed By: navahgar Differential Revision: D27669074 Pulled By: ailzhang fbshipit-source-id: a4deb297cc89142ae8bd683284516c881ddf3c87