Move cauchy to Aten(CPU) (#31824)
Summary:
Fix https://github.com/pytorch/pytorch/issues/24684.
Benchmark script :
```
import torch
import torch.nn as nn
import time
torch.manual_seed(0)
def _time():
return time.time()
device = "cpu"
#warm up
for n in [10, 100, 1000]:
input = torch.randn(128, n, requires_grad=False, device=device)
for i in range(1000):
input.cauchy_()
for n in [1, 10, 100, 1000]:
fwd_t = 0
input = torch.randn(128, n, requires_grad=False, device=device)
for i in range(10000):
t1 = _time()
input.cauchy_()
t2 = _time()
fwd_t = fwd_t + (t2 -t1)
fwd_avg = fwd_t / 10000 * 1000
print("input size(128, %d) forward time is %.4f (ms)." % (n, fwd_avg))
```
Test device: **skx-8180**.
Before:
```
input size(128, 1) forward time is 0.0071 (ms).
input size(128, 10) forward time is 0.0596 (ms).
input size(128, 100) forward time is 0.5798 (ms).
input size(128, 1000) forward time is 5.8395 (ms).
```
After:
```
input size(128, 1) forward time is 0.0070 (ms).
input size(128, 10) forward time is 0.0583 (ms).
input size(128, 100) forward time is 0.5714 (ms).
input size(128, 1000) forward time is 5.7674 (ms).
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31824
Differential Revision: D19314411
Pulled By: ezyang
fbshipit-source-id: 58098546face3e5971b023f702cfe44ff1cccfbc
