Refactors shape logic out of code generation, fixes possible segfault (#15750)
Summary:
This PR:
- Removes shape logic from the code generator, which was previously relied on to return chunk and concat information
- Copies the logic to detect if a kernel has a rand_like node to the executor, making its pass independent of the code generator
- Fixes a possible segfault where references to a vector still being modified were relied upon
The actual shape logic is unchanged.
The possible segfault is in the handling of the former "flat_inputs" in codegen.cpp. This vector holds pairs, and the second element of these pairs is a reference. In some cases these would be references to items in the vector chunk_desc, which could be added to later, possibly invalidating any references to items in it. I hit a similar segfault in testing when naively making parallel code for "flat_outputs."
I'm submitting this small PR because it's separable, self-contained, has a fix, and I am trying to actively get away from large PRs to encourage more stability and incremental change in the fuser.
ngimel zou3519
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15750
Differential Revision: D13597451
Pulled By: zou3519
fbshipit-source-id: 0d48b365779b42849b044ba0286258aacc7b0332
