[inductor] no-side-effect codegen (#107617)
Inductor kernel codegen previously have the following side effect:
- in `Kernel.__exit__ `, we add local used buffers in graph.removed_buffers
- during codegen, we do memory allocation/free.
These cause doing multiple versions of codegen for the same kernel hard. The PR refactor the code to make kernel codegen not changing graph level states. After codegening a kernel, the graph level state is not changed so we can go on to codegen another version of the kernel if we want.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107617
Approved by: https://github.com/jansel
