Skip to content

[AD] struct_extract result is varied only if field isn't @noDerivative #21899

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Jan 16, 2019
Merged

[AD] struct_extract result is varied only if field isn't @noDerivative #21899

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
d9ab75e
[AD] struct_extract result is varied only if field isn't `@noDerivative`
jekbradbury Jan 16, 2019
2b6cb3d
Update lib/SILOptimizer/Mandatory/Differentiation.cpp
rxwei Jan 16, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 10 additions & 0 deletions lib/SILOptimizer/Mandatory/Differentiation.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1305,6 +1305,16 @@ void DifferentiableActivityInfo::analyze(DominanceInfo *di,
if (isVaried(cai->getSrc(), i))
recursivelySetVariedIfDifferentiable(cai->getDest(), i);
}
else if (auto *sei = dyn_cast<StructExtractInst>(&inst)) {
Copy link
Contributor

@rxwei rxwei Jan 16, 2019

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

You'll also want to check whether CotangentVector is @_fieldwiseProductSpace, because if it's not, we consider @noDerivative as having had no effect on conformance synthesis, so it could still have a VJP we would call when it's active.

It would be nice to move the code that checks for @_fieldwiseProductSpace into a helper.

if (isVaried(sei->getOperand(), i)) {
auto hasNoDeriv = sei->getField()->getAttrs()
.hasAttribute<NoDerivativeAttr>();
if (!hasNoDeriv) {
for (auto result: inst.getResults())
setVariedIfDifferentiable(result, i);
}
}
}
// Handle everything else.
else {
for (auto &op : inst.getAllOperands())
Expand Down