pytorch

60ec53c7 - Fix copy kernel speed regression introduced in #29631 (#31279)

Fix copy kernel speed regression introduced in #29631 (#31279) Summary: Fixes https://github.com/pytorch/pytorch/issues/31271 This fixes copy kernel speed regression introduced in https://github.com/pytorch/pytorch/issues/29631. The previous implementation forces the compiler to instantiate `static_cast_with_inter_type` because it is passed as an argument of a function. This behavior makes it impossible for compilers to do optimizations like automatic vectorization, and, function call itself is expensive compared to a single casting instruction. To check the change, run ``` readelf -Ws /home/xgao/anaconda3/lib/python3.7/site-packages/torch/lib/libtorch_cpu.so | grep static_cast_with_inter_type ``` On nightly build, we have output ``` 168217: 0000000001852bf0 5 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIsdE5applyEd 168816: 0000000001852d30 33 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeISt7complexIfEaE5applyEa 168843: 00000000018531f0 7 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIblE5applyEl 168930: 0000000001852c20 3 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIslE5applyEl 168935: 00000000018528d0 124 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIfNS_4HalfEE5applyES1_ 169023: 0000000001852f30 17 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeISt7complexIdEhE5applyEh 169713: 00000000018525c0 3 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIahE5applyEh 170033: 0000000001852c10 3 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIsiE5applyEi 170105: 0000000001852bd0 5 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIshE5applyEh 170980: 0000000001852fc0 27 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeISt7complexIdES1_IfEE5applyES3_ 171398: 0000000001852810 13 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIdbE5applyEb 171574: 00000000018532e0 35 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIbNS_8BFloat16EE5applyES1_ 171734: 0000000001852b20 6 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIlSt7complexIdEE5applyES2_ 172422: 0000000001853350 54 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeINS_8BFloat16EaE5applyEa 172704: 00000000018533c0 38 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeINS_8BFloat16EfE5applyEf 172976: 0000000001852890 10 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIflE5applyEl 173038: 0000000001852f80 9 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeISt7complexIdEfE5applyEf 173329: 00000000018531c0 20 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIbfE5applyEf 173779: 00000000018524d0 3 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIhiE5applyEi 174032: 0000000001852960 14 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIfNS_8BFloat16EE5applyES1_ 174334: 0000000001852d60 29 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeISt7complexIfEdE5applyEd 174470: 0000000001852c60 124 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIsNS_4HalfEE5applyES1_ 174770: 0000000001852bc0 15 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIlNS_8BFloat16EE5applyES1_ 176408: 0000000001853980 144 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeINS_4HalfEbE5applyEb 176475: 0000000001852790 128 FUNC LOCAL DEFAULT 9 _ZN3c1027static_cast_with_inter_typeIdNS_4HalfEE5applyES1_ .... ``` And after this PR, we get empty output ``` ``` Pull Request resolved: https://github.com/pytorch/pytorch/pull/31279 Differential Revision: D19075587 Pulled By: ngimel fbshipit-source-id: c20088241f39fa40c1d055f0a46eb5b9ece52e71