pytorch

56440594 - [inductor] Lower torch.exp2 and use it for torch.pow(2, x) (#92632)

[inductor] Lower torch.exp2 and use it for torch.pow(2, x) (#92632) Before ```python tmp0 = 2.0 tmp2 = tl.libdevice.pow(tmp0, tmp1) ``` After ```python tmp1 = tl.libdevice.exp2(tmp0) ``` I've benchmarked on CPU and CUDA with the following examples ``` @torch._dynamo.optimize() def exp2(x): return torch.pow(2, x) @torch._dynamo.optimize() def logaddexp2(a, b): m = torch.maximum(a, b) return m + torch.log2(1 + torch.pow(2, -torch.abs(a-b))) ``` triton is able to specialize `pow(2, x)` such that this makes no difference, but on CPU I see a surprisingly large speedup. | device | Function | Master (us) | This PR (us) | Speedup | |--------|-----------|-------------|--------------|---------| | CUDA | exp2 | 64 | 63 | 1.0 | | | logaddexp | 109 | 107 | 1.0 | | CPU | exp2 | 220 | 40 | 5.5 | | | logaddexp | 282 | 140 | 2.0 | Pull Request resolved: https://github.com/pytorch/pytorch/pull/92632 Approved by: https://github.com/lezcano, https://github.com/ngimel