Minor speed improvements to defun.

- EncodeArg in C instead of python.
- Also caches parsed device specs, and device spec hashes
- Adds a common way to register python types in C.
- Fastpath canonicalize function inputs when no kwargs are passed
- Set the func name attr directly instead of creating an op to wrap it.
- Rewrite IsAttrsHelper without caching

Before:
entry {
  name: "MicroBenchmarks.benchmark_defun_matmul_2_by_2_CPU"
  iters: 30000
  wall_time: 101.803263028
  extras {
    key: "examples_per_sec"
    value {
      double_value: 9822.86785562
    }
  }
}

After:
entry {
  name: "MicroBenchmarks.benchmark_defun_matmul_2_by_2_CPU"
  iters: 30000
  wall_time: 47.2899993261
  extras {
    key: "examples_per_sec"
    value {
      double_value: 21146.1199884
    }
  }
}
PiperOrigin-RevId: 215272962

0 files changed, 0 insertions, 0 deletions