mirror of
https://github.com/apple/swift.git
synced 2025-12-21 12:14:44 +01:00
af8942d940
Compiler: - Add `Forward` and `Reverse` to `DifferentiabilityKind`. - Expand `DifferentiabilityMask` in `ExtInfo` to 3 bits so that it now holds all 4 cases of `DifferentiabilityKind`. - Parse `@differentiable(reverse)` and `@differentiable(_forward)` declaration attributes and type attributes. - Emit a warning for `@differentiable` without `reverse`. - Emit an error for `@differentiable(_forward)`. - Rename `@differentiable(linear)` to `@differentiable(_linear)`. - Make `@differentiable(reverse)` type lowering go through today's `@differentiable` code path. We will specialize it to reverse-mode in a follow-up patch. ABI: - Add `Forward` and `Reverse` to `FunctionMetadataDifferentiabilityKind`. - Extend `TargetFunctionTypeFlags` by 1 bit to store the highest bit of differentiability kind (linear). Note that there is a 2-bit gap in `DifferentiabilityMask` which is reserved for `AsyncMask` and `ConcurrentMask`; `AsyncMask` is ABI-stable so we cannot change that. _Differentiation module: - Replace all occurrences of `@differentiable` with `@differentiable(reverse)`. - Delete `_transpose(of:)`. Resolves rdar://69980056.
82 lines
2.8 KiB
Swift
82 lines
2.8 KiB
Swift
//===--- DifferentiationUtilities.swift -----------------------*- swift -*-===//
|
|
//
|
|
// This source file is part of the Swift.org open source project
|
|
//
|
|
// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
|
|
// Licensed under Apache License v2.0 with Runtime Library Exception
|
|
//
|
|
// See https://swift.org/LICENSE.txt for license information
|
|
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// Utilities for creating differentiable functions, debugging, and customizing
|
|
// derivatives.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
import Swift
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Derivative customization
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// Returns `x` like an identity function. When used in a context where `x` is
|
|
/// being differentiated with respect to, this function will not produce any
|
|
/// derivative at `x`.
|
|
@inlinable
|
|
@inline(__always)
|
|
@_semantics("autodiff.nonvarying")
|
|
public func withoutDerivative<T>(at x: T) -> T {
|
|
x
|
|
}
|
|
|
|
/// Applies the given closure `body` to `x`. When used in a context where `x` is
|
|
/// being differentiated with respect to, this function will not produce any
|
|
/// derivative at `x`.
|
|
// FIXME: Support throws-rethrows.
|
|
@inlinable
|
|
@inline(__always)
|
|
@_semantics("autodiff.nonvarying")
|
|
public func withoutDerivative<T, R>(at x: T, in body: (T) -> R) -> R {
|
|
body(x)
|
|
}
|
|
|
|
public extension Differentiable {
|
|
/// Applies the given closure to the derivative of `self`.
|
|
///
|
|
/// Returns `self` like an identity function. When the return value is used in
|
|
/// a context where it is differentiated with respect to, applies the given
|
|
/// closure to the derivative of the return value.
|
|
@inlinable
|
|
@differentiable(reverse, wrt: self)
|
|
func withDerivative(_ body: @escaping (inout TangentVector) -> Void) -> Self {
|
|
return self
|
|
}
|
|
|
|
@inlinable
|
|
@derivative(of: withDerivative)
|
|
internal func _vjpWithDerivative(
|
|
_ body: @escaping (inout TangentVector) -> Void
|
|
) -> (value: Self, pullback: (TangentVector) -> TangentVector) {
|
|
return (self, { grad in
|
|
var grad = grad
|
|
body(&grad)
|
|
return grad
|
|
})
|
|
}
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Diagnostics
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
@_silgen_name("_fatalErrorForwardModeDifferentiationDisabled")
|
|
public func _fatalErrorForwardModeDifferentiationDisabled() -> Never {
|
|
fatalError("""
|
|
JVP does not exist. Use \
|
|
'-Xfrontend -enable-experimental-forward-mode-differentiation' to enable \
|
|
differential-first differentiation APIs.
|
|
""")
|
|
}
|