[AutoDiff] Don't propagate activity through '@noDerivative' projections. #27472
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Reads or writes to `@noDerivative` properties of struct should not be differentiated. At the implementation level, this amounts to not propagating activity through `@noDerivative` projections. This has been done in some of usefulness propagation, but there are two places where this has not been done: * In `DifferentiableActivityInfo::propagateUsefulThroughBuffer`, usefulness was being propagated arbitrarily regardless of the instruction. * In `DifferentiableActivityInfo::recursivelySetVaried`, variedness was set regardless of whether the proejction is a `@noDerivative` one. This patch changes activity analysis to not propagate activity through `@noDerivative` field projections from a struct, covering both previously uncovered places discussed above. As a result, `PullbackEmitter::getAdjointBuffer` no longer needs to check for `@noDerivative` or emit any diagnostics. Resolves [TF-865](https://bugs.swift.org/browse/TF-865).
dan-zheng
approved these changes
Oct 1, 2019
| var tmp = s | ||
| // expected-note @+1 {{cannot differentiate through a '@noDerivative' stored property; do you want to use 'withoutDerivative(at:)'?}} | ||
| tmp.y = tmp.x | ||
| tmp.y = tmp.x // No diagnostics expected. |
|
@swift-ci please test tensorflow |
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Reads or writes to
@noDerivativeproperties of struct should not be differentiated. At the implementation level, this amounts to not propagating activity through@noDerivativeprojections. This has been done in some of usefulness propagation, but there are two places where this has not been done:DifferentiableActivityInfo::propagateUsefulThroughBuffer, usefulness was being propagated arbitrarily regardless of the instruction.DifferentiableActivityInfo::recursivelySetVaried, variedness was set regardless of whether the proejction is a@noDerivativeone.This patch changes activity analysis to not propagate activity through
@noDerivativefield projections from a struct, covering both previously uncovered places discussed above. As a result,PullbackEmitter::getAdjointBufferno longer needs to check for@noDerivativeor emit any diagnostics.Resolves TF-865.