It can already only accept values with none ownership and the merging of
ownership around ownership phis ensure that if we phi this with a partial_apply
or the like, we get the appropriate ownership on any such ownership phi values.
We are now out of SILGen emitting fewer destroy_value unnecessarily on
thin_to_thick functions. This changed some codegen and also forced me to update
some tests/fix AutoDiff.
I also deleted the DebugInfo test mandatoryinlining-wrongdebugscope.swift since:
1. It was depending on these destroys being there.
2. Given the need to improve the test @aprantl suggested I just eliminate it
solving the test failure for me.
`DifferentiableFunctionInst` now stores result indices.
`SILAutoDiffIndices` now stores result indices instead of a source index.
`@differentiable` SIL function types may now have multiple differentiability
result indices and `@noDerivative` resutls.
`@differentiable` AST function types do not have `@noDerivative` results (yet),
so this functionality is not exposed to users.
Resolves TF-689 and TF-1256.
Infrastructural support for TF-983: supporting differentiation of `apply`
instructions with multiple active semantic results.
Previously, two conditions were necessary to enable differentiable programming:
- Using the `-enable-experimental-differentiable-programming` frontend flag.
- Importing the `_Differentiation` module.
Importing the `_Differentiation` module is the true condition because it
contains the required compiler-known `Differentiable` protocol. The frontend
flag is redundant and cumbersome.
Now, the frontend flag is removed.
Importing `_Differentiation` is the only condition.
