[Static Runtime] Simplify out variant overload implementations (#65384)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65384
The following pattern appears frequently in `ops.cpp`:
```
if (!n->matches(schema_1) && !n->matches(schema_2) && ... && !n->matches(schema_n)) {
LogAndDumpSchema(n);
return nullptr;
}
return [](ProcessedNode* p_node) {
if (p_node->Output(0).isNone()) {
if (p_node->Input(i).isSomeType()) {
// special logic for schema 1
} else if (p_node->Input(i).isSomeOtherType()) {
// special logic for schema 2
} else if (...) {
// special logic for schema3
}
// and so on
} else {
// another complicated type checking chain
}
};
```
A much cleaner way to implement operator overloads is like this:
```
if (n->matches(schema_1)) {
return schema_1_impl;
} else if (n->matches(schema_2)) {
return schema_2_impl;
}
// and so on
```
This has a few advantages:
* Significantly reduces complexity of the out variant implementations, especially for ops with more than 2 overloads. One implementation corresponds to one schema. This makes the implementation more readable/maintainable.
* Adhering to this convention makes it easier to add a new overload. Just add a new `n->matches(...)` case instead of working the schema into existing complicated logic.
* Ops are marginally faster since we don't have to check types at runtime.
Note: there are a few cases where this actually made the code less concise (`aten::div`), so I left those ops untouched.
Thanks for pointing this out in another diff d1jang
Test Plan: `buck test caffe2/benchmarks/static_runtime:static_runtime_cpptest`
Reviewed By: hlu1
Differential Revision: D31072328
fbshipit-source-id: c40a4f7e6a79881e94c9ec49e9008ed75cfc8688
pytorch
c975ca43 - [Static Runtime] Simplify out variant overload implementations (#65384)
