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[AutoDiff] fix array subscript lookup when there are multiple #31723

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Merged
merged 1 commit into from
May 12, 2020
Merged

[AutoDiff] fix array subscript lookup when there are multiple #31723

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16 changes: 14 additions & 2 deletions lib/SILOptimizer/Differentiation/PullbackEmitter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1331,6 +1331,7 @@ void PullbackEmitter::visitSILInstruction(SILInstruction *inst) {
AllocStackInst *
PullbackEmitter::getArrayAdjointElementBuffer(SILValue arrayAdjoint,
int eltIndex, SILLocation loc) {
auto &ctx = builder.getASTContext();
auto arrayTanType = cast<StructType>(arrayAdjoint->getType().getASTType());
auto arrayType = arrayTanType->getParent()->castTo<BoundGenericStructType>();
auto eltTanType = arrayType->getGenericArgs().front()->getCanonicalType();
Expand All @@ -1340,7 +1341,19 @@ PullbackEmitter::getArrayAdjointElementBuffer(SILValue arrayAdjoint,
auto *arrayTanStructDecl = arrayTanType->getStructOrBoundGenericStruct();
auto subscriptLookup =
arrayTanStructDecl->lookupDirect(DeclBaseName::createSubscript());
auto *subscriptDecl = cast<SubscriptDecl>(subscriptLookup.front());
SubscriptDecl *subscriptDecl = nullptr;
for (auto *candidate : subscriptLookup) {
auto candidateModule = candidate->getModuleContext();
if (candidateModule->getName() == ctx.Id_Differentiation ||
candidateModule->isStdlibModule()) {
assert(!subscriptDecl && "Multiple `Array.TangentVector.subscript`s");
subscriptDecl = cast<SubscriptDecl>(candidate);
#ifdef NDEBUG
break;
#endif
}
}
assert(subscriptDecl && "No `Array.TangentVector.subscript`");
auto *subscriptGetterDecl = subscriptDecl->getAccessor(AccessorKind::Get);
assert(subscriptGetterDecl && "No `Array.TangentVector.subscript` getter");
SILOptFunctionBuilder fb(getContext().getTransform());
Expand All @@ -1352,7 +1365,6 @@ PullbackEmitter::getArrayAdjointElementBuffer(SILValue arrayAdjoint,
subscriptGetterFn->getLoweredFunctionType()->getSubstGenericSignature();
// Apply `Array.TangentVector.subscript.getter` to get array element adjoint
// buffer.
auto &ctx = builder.getASTContext();
// %index_literal = integer_literal $Builtin.IntXX, <index>
auto builtinIntType =
SILType::getPrimitiveObjectType(ctx.getIntDecl()
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9 changes: 9 additions & 0 deletions test/AutoDiff/stdlib/array.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,15 @@ var ArrayAutoDiffTests = TestSuite("ArrayAutoDiff")

typealias FloatArrayTan = Array<Float>.TangentVector

extension Array.DifferentiableView {
/// A subscript that always fatal errors.
///
/// The differentiation transform should never emit calls to this.
subscript(alwaysFatalError: Int) -> Element {
fatalError("wrong subscript")
}
}

ArrayAutoDiffTests.test("ArrayIdentity") {
func arrayIdentity(_ x: [Float]) -> [Float] {
return x
Expand Down