70 lines
1.7 KiB
C
70 lines
1.7 KiB
C
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#pragma once
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#include <ATen/native/DispatchStub.h>
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namespace c10 {
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class Scalar;
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}
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namespace at {
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struct TensorIterator;
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struct TensorIteratorBase;
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namespace native {
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#if defined(__CUDACC__) || defined(__HIPCC__)
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#define HOST_DEVICE __host__ __device__
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#else
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#define HOST_DEVICE
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#endif
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// integral power in pytorch allows for negative exponents, giving truncated integral results.
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// e.g. since 2**-1==0.5, the truncated integral result is zero. 1**negative_exponent is the
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// only non-zero result.
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template <class T,
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typename std::enable_if<std::is_integral<T>::value, T>::type* = nullptr>
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static inline HOST_DEVICE __ubsan_ignore_signed_int_overflow__ T powi_impl(T a, T b) {
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T result = 1;
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while (b) {
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if (b & 1) {
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result *= a;
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}
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b /= 2;
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a *= a;
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}
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return result;
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}
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template <class T,
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typename std::enable_if<std::is_integral<T>::value && !std::is_signed<T>::value, T>::type* = nullptr>
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static inline HOST_DEVICE T powi(T a, T b) {
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return powi_impl(a, b);
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}
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template <class T,
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typename std::enable_if<std::is_integral<T>::value && std::is_signed<T>::value, T>::type* = nullptr>
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static inline HOST_DEVICE T powi(T a, T b) {
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if ( b < 0 ) {
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if ( a == 1 ) {
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return 1;
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} else if ( a == -1 ) {
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auto negative = (-b) % static_cast<T>(2);
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return negative ? -1 : 1;
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} else {
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return 0;
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}
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}
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return powi_impl(a, b);
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}
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using pow_tensor_tensor_fn = void (*)(TensorIteratorBase&);
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using pow_tensor_scalar_fn = void (*)(TensorIteratorBase&, const c10::Scalar&);
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DECLARE_DISPATCH(pow_tensor_tensor_fn, pow_tensor_tensor_stub);
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DECLARE_DISPATCH(pow_tensor_scalar_fn, pow_tensor_scalar_stub);
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} // namespace native
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} // namespace at
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