Richard Wei
e494df2ee6
[AutoDiff] Add differentiability kind to differentiability witnesses and mangle them.
...
Differentiability witnesses are now keyed by the original function name, the differentiability kind, and the autodiff config.
Updated SIL syntax:
```
differentiability-kind ::= 'forward' | 'reverse' | 'normal' | 'linear'
sil-differentiability-witness ::=
'sil_differentiability_witness'
sil-linkage?
'[' differentiability-kind ']'
'[' 'parameters' sil-differentiability-witness-function-index-list ']'
'[' 'results' sil-differentiability-witness-function-index-list ']'
generic-parameter-clause?
sil-function-name ':' sil-type
sil-differentiability-witness-body?
sil-instruction ::=
'differentiability_witness_function'
'[' sil-differentiability-witness-function-kind ']'
'[' differentiability-kind ']'
'[' 'parameters' sil-differentiability-witness-function-index-list ']'
'[' 'results' sil-differentiability-witness-function-index-list ']'
generic-parameter-clause?
sil-function-name ':' sil-type
```
```console
sil_differentiability_witness [reverse] [parameters 0 1] [results 0] <T where T: Differentiable> @foo : <T> $(T) -> T
differentiability_witness_function [vjp] [reverse] [parameters 0] [results 0] <T where T: Differentiable> @foo : $(T) -> T
```
New mangling:
```swift
global ::= global generic-signature? 'WJ' DIFFERENTIABILITY-KIND INDEX-SUBSET 'p' INDEX-SUBSET 'r' // differentiability witness
```
```console
$s13test_mangling3fooyS2f_S2ftFWJrSpSr ---> reverse differentiability witness for test_mangling.foo(Swift.Float, Swift.Float, Swift.Float) -> Swift.Float with respect to parameters {0} and results {0}
```
Resolves rdar://74380324.
2021-02-17 18:27:42 -05:00