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https://github.com/pytorch/pytorch.git
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2d5fbe6e0d
* Improve Variable interface * Address comments from @apaszke and @colesbury * string ::operator= is not noexcept * Remove ir.h from tracer_state.h to improve build times * Make Variable a struct and pack SavedVariable fields * Implement as_variable_ref * grad_fn_ptr() -> grad_fn_unsafe() * Reduce hackiness of set_type hack * Include variable.h and edge.h in tracer_state.h because it uses them * class Variable -> struct Variable because Windows cant even * Make Variable::output_nr uint32_t instead of int * Add comment about tracing state * Replaced more static_cast<Variable&> and improve docs * Remove SavedVariable destructor and construct members in init list * Clarify docs for Variable * Variable::set_version -> set_version_counter
39 lines
1.2 KiB
C++
39 lines
1.2 KiB
C++
#pragma once
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#include <atomic>
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#include <cstdint>
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#include <memory>
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// Every Variable has a version counter. Version counters are incremented
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// whenever the data or shape of a tensor changes through Variable operations.
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// These are typicallly in-place operations. Version counters are used to
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// detect modifications to saved variables which would result in incorrect
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// gradient calculations. Version counters may be shared between Variables:
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//
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// 1. A view shares the version counter of the base Variable,
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// 2. Detached variables share the version counter of the source,
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// 3. Unpacked saved variables share the version counter of the source.
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namespace torch { namespace autograd {
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struct VariableVersion {
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public:
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// NOTE: As of C++11 and 14, default-constructing a std::atomic variable
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// leaves it in a persistently undefined state. See
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// https://cplusplus.github.io/LWG/issue2334.
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VariableVersion(uint32_t version = 0)
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: version_block_(std::make_shared<std::atomic<uint32_t>>(version)) {}
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void bump() noexcept {
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version_block_->fetch_add(1);
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}
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uint32_t current_version() const noexcept {
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return version_block_->load();
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}
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private:
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std::shared_ptr<std::atomic<uint32_t>> version_block_;
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};
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}} // namespace torch::autograd
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