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[AutoDiff] Use @_fieldwiseDifferentiable on struct decls and deprecate @_fieldwiseProductSpace. #22009

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Merged
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Jan 20, 2019
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[AutoDiff] Use @_fieldwiseDifferentiable on struct decls and deprecate @_fieldwiseProductSpace. #22009

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4 changes: 2 additions & 2 deletions include/swift/AST/Attr.def
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Original file line number Diff line number Diff line change
Expand Up @@ -395,8 +395,8 @@ SIMPLE_DECL_ATTR(TensorFlowGraph, TensorFlowGraph,
OnFunc, 82)
SIMPLE_DECL_ATTR(TFParameter, TFParameter,
OnVar, 83)
SIMPLE_DECL_ATTR(_fieldwiseProductSpace, FieldwiseProductSpace,
OnTypeAlias | OnNominalType | UserInaccessible, 84)
SIMPLE_DECL_ATTR(_fieldwiseDifferentiable, FieldwiseDifferentiable,
OnNominalType | UserInaccessible, 84)
SIMPLE_DECL_ATTR(noDerivative, NoDerivative,
OnVar, 85)

Expand Down
15 changes: 12 additions & 3 deletions include/swift/AST/DiagnosticsSema.def
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Original file line number Diff line number Diff line change
Expand Up @@ -2742,6 +2742,11 @@ ERROR(noderivative_only_on_stored_properties_in_differentiable_structs,none,
"@noDerivative is only allowed on stored properties in structure types "
"that declare a conformance to 'Differentiable'", ())

// @_fieldwiseDifferentiable attribute
ERROR(fieldwise_differentiable_only_on_differentiable_structs,none,
"@_fieldwiseDifferentiable is only allowed on structure types that "
"conform to 'Differentiable'", ())

//------------------------------------------------------------------------------
// MARK: Type Check Expressions
//------------------------------------------------------------------------------
Expand Down Expand Up @@ -3655,11 +3660,15 @@ ERROR(unreferenced_generic_parameter,none,
// SWIFT_ENABLE_TENSORFLOW
// Function differentiability
ERROR(autodiff_attr_argument_not_differentiable,none,
"argument is not differentiable, but the enclosing function type is marked '@autodiff'; did you want to add '@nondiff' to this argument?", ())
"argument is not differentiable, but the enclosing function type is "
"marked '@autodiff'; did you want to add '@nondiff' to this argument?",
())
ERROR(autodiff_attr_result_not_differentiable,none,
"result is not differentiable, but the function type is marked '@autodiff'", ())
"result is not differentiable, but the function type is marked "
"'@autodiff'", ())
ERROR(nondiff_attr_invalid_on_nondifferentiable_function,none,
"'nondiff' cannot be applied to arguments of a non-differentiable function", ())
"'nondiff' cannot be applied to arguments of a non-differentiable "
"function", ())

// SIL
ERROR(opened_non_protocol,none,
Expand Down
183 changes: 60 additions & 123 deletions lib/SILOptimizer/Mandatory/Differentiation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -99,16 +99,6 @@ static void createEntryArguments(SILFunction *f) {
}
}

/// Looks up a function in the current module. If it exists, returns it.
/// Otherwise, attempt to link it from imported modules. Returns null if such
/// function name does not exist.
static SILFunction *lookUpOrLinkFunction(StringRef name, SILModule &module) {
assert(!name.empty());
if (auto *localFn = module.lookUpFunction(name))
return localFn;
return module.findFunction(name, SILLinkage::PublicExternal);
}

/// Computes the correct linkage for functions generated by the AD pass
/// associated with a function with linkage `originalLinkage`.
static SILLinkage getAutoDiffFunctionLinkage(SILLinkage originalLinkage) {
Expand Down Expand Up @@ -528,7 +518,7 @@ enum class StructExtractDifferentiationStrategy {
// that is zero except along the direction of the corresponding field.
//
// Fields correspond by matching name.
FieldwiseProductSpace,
Fieldwise,

// Differentiate the `struct_extract` by looking up the corresponding getter
// and using its VJP.
Expand Down Expand Up @@ -1291,6 +1281,7 @@ void DifferentiableActivityInfo::analyze(DominanceInfo *di,
if (isVaried(cai->getSrc(), i))
recursivelySetVariedIfDifferentiable(cai->getDest(), i);
}
// Handle `struct_extract`.
else if (auto *sei = dyn_cast<StructExtractInst>(&inst)) {
if (isVaried(sei->getOperand(), i)) {
auto hasNoDeriv = sei->getField()->getAttrs()
Expand Down Expand Up @@ -2091,46 +2082,30 @@ class PrimalGenCloner final : public SILClonerWithScopes<PrimalGenCloner> {
}

void visitStructExtractInst(StructExtractInst *sei) {
auto &astCtx = getContext().getASTContext();
auto &structExtractDifferentiationStrategies =
auto &strategies =
getDifferentiationTask()->getStructExtractDifferentiationStrategies();

// Special handling logic only applies when the `struct_extract` is active.
// If not, just do standard cloning.
if (!activityInfo.isActive(sei, synthesis.indices)) {
LLVM_DEBUG(getADDebugStream() << "Not active:\n" << *sei << '\n');
structExtractDifferentiationStrategies.insert(
strategies.insert(
{sei, StructExtractDifferentiationStrategy::Inactive});
SILClonerWithScopes::visitStructExtractInst(sei);
return;
}

// This instruction is active. Determine the appropriate differentiation
// strategy, and use it.

// Use the FieldwiseProductSpace strategy, if appropriate.
auto *structDecl = sei->getStructDecl();
auto cotangentDeclLookup =
structDecl->lookupDirect(astCtx.Id_CotangentVector);
if (cotangentDeclLookup.size() >= 1) {
assert(cotangentDeclLookup.size() == 1);
auto cotangentTypeDecl = cotangentDeclLookup.front();
assert(isa<TypeAliasDecl>(cotangentTypeDecl) ||
isa<StructDecl>(cotangentTypeDecl));
if (cotangentTypeDecl->getAttrs()
.hasAttribute<FieldwiseProductSpaceAttr>()) {
structExtractDifferentiationStrategies.insert(
{sei, StructExtractDifferentiationStrategy::FieldwiseProductSpace});
SILClonerWithScopes::visitStructExtractInst(sei);
return;
}
if (structDecl->getAttrs().hasAttribute<FieldwiseDifferentiableAttr>()) {
strategies.insert(
{sei, StructExtractDifferentiationStrategy::Fieldwise});
SILClonerWithScopes::visitStructExtractInst(sei);
return;
}

// The FieldwiseProductSpace strategy is not appropriate, so use the Getter
// strategy.
structExtractDifferentiationStrategies.insert(
strategies.insert(
{sei, StructExtractDifferentiationStrategy::Getter});

// Find the corresponding getter and its VJP.
auto *getterDecl = sei->getField()->getGetter();
assert(getterDecl);
Expand All @@ -2142,42 +2117,29 @@ class PrimalGenCloner final : public SILClonerWithScopes<PrimalGenCloner> {
errorOccurred = true;
return;
}
auto getterDiffAttrs = getterFn->getDifferentiableAttrs();
if (getterDiffAttrs.size() < 1) {
getContext().emitNondifferentiabilityError(
sei, synthesis.task, diag::autodiff_property_not_differentiable);
errorOccurred = true;
return;
}
auto *getterDiffAttr = getterDiffAttrs[0];
if (!getterDiffAttr->hasVJP()) {
SILAutoDiffIndices indices(/*source*/ 0, /*parameters*/ {0});
auto *task = getContext().lookUpDifferentiationTask(getterFn, indices);
if (!task) {
getContext().emitNondifferentiabilityError(
sei, synthesis.task, diag::autodiff_property_not_differentiable);
errorOccurred = true;
return;
}
assert(getterDiffAttr->getIndices() ==
SILAutoDiffIndices(/*source*/ 0, /*parameters*/{0}));
auto *getterVJP = lookUpOrLinkFunction(getterDiffAttr->getVJPName(),
getContext().getModule());

// Reference and apply the VJP.
auto loc = sei->getLoc();
auto *getterVJPRef = getBuilder().createFunctionRef(loc, getterVJP);
auto *getterVJPRef = getBuilder().createFunctionRef(loc, task->getVJP());
auto *getterVJPApply = getBuilder().createApply(
loc, getterVJPRef, /*substitutionMap*/ {},
/*args*/ {getMappedValue(sei->getOperand())}, /*isNonThrowing*/ false);
SmallVector<SILValue, 8> vjpDirectResults;
extractAllElements(getterVJPApply, getBuilder(), vjpDirectResults);
ArrayRef<SILValue> originalDirectResults =
ArrayRef<SILValue>(vjpDirectResults).drop_back(1);

// Map original results.
auto originalDirectResults =
ArrayRef<SILValue>(vjpDirectResults).drop_back(1);
SILValue originalDirectResult = joinElements(originalDirectResults,
getBuilder(),
getterVJPApply->getLoc());
mapValue(sei, originalDirectResult);

// Checkpoint the pullback.
SILValue pullback = vjpDirectResults.back();
getPrimalInfo().addPullbackDecl(sei, pullback->getType().getASTType());
Expand Down Expand Up @@ -3079,60 +3041,41 @@ class AdjointEmitter final : public SILInstructionVisitor<AdjointEmitter> {
auto loc = remapLocation(sei->getLoc());
auto &differentiationStrategies =
getDifferentiationTask()->getStructExtractDifferentiationStrategies();
auto differentiationStrategyLookUp = differentiationStrategies.find(sei);
assert(differentiationStrategyLookUp != differentiationStrategies.end());
auto differentiationStrategy = differentiationStrategyLookUp->second;

if (differentiationStrategy ==
StructExtractDifferentiationStrategy::Inactive) {
auto strategy = differentiationStrategies.lookup(sei);
switch (strategy) {
case StructExtractDifferentiationStrategy::Inactive:
assert(!activityInfo.isActive(sei, synthesis.indices));
return;
}

if (differentiationStrategy ==
StructExtractDifferentiationStrategy::FieldwiseProductSpace) {
case StructExtractDifferentiationStrategy::Fieldwise: {
// Compute adjoint as follows:
// y = struct_extract <key>, x
// adj[x] = struct (0, ..., key': adj[y], ..., 0)
// where `key'` is the field in the cotangent space corresponding to
// `key`.

// Find the decl of the cotangent space type.
auto structTy = sei->getOperand()->getType().getASTType();
auto cotangentVectorTy = structTy->getAutoDiffAssociatedVectorSpace(
AutoDiffAssociatedVectorSpaceKind::Cotangent,
LookUpConformanceInModule(getModule().getSwiftModule()))
->getType()->getCanonicalType();
assert(!getModule()
.Types.getTypeLowering(cotangentVectorTy)
.isAddressOnly());
->getType()->getCanonicalType();
assert(!getModule().Types.getTypeLowering(cotangentVectorTy)
.isAddressOnly());
auto cotangentVectorSILTy =
SILType::getPrimitiveObjectType(cotangentVectorTy);
auto *cotangentVectorDecl =
cotangentVectorTy->getStructOrBoundGenericStruct();
assert(cotangentVectorDecl);

// Find the corresponding field in the cotangent space.
VarDecl *correspondingField = nullptr;
// If the cotangent space is the original sapce, then it's the same field.
if (cotangentVectorDecl == sei->getStructDecl())
correspondingField = sei->getField();
// Otherwise we just look it up by name.
else {
auto correspondingFieldLookup =
cotangentVectorDecl->lookupDirect(sei->getField()->getName());
assert(correspondingFieldLookup.size() == 1);
assert(isa<VarDecl>(correspondingFieldLookup[0]));
correspondingField = cast<VarDecl>(correspondingFieldLookup[0]);
correspondingField = cast<VarDecl>(correspondingFieldLookup.front());
}
assert(correspondingField);

#ifndef NDEBUG
unsigned numMatchingStoredProperties = 0;
for (auto *storedProperty : cotangentVectorDecl->getStoredProperties())
if (storedProperty == correspondingField)
numMatchingStoredProperties += 1;
assert(numMatchingStoredProperties == 1);
#endif

// Compute adjoint.
auto av = getAdjointValue(sei);
switch (av.getKind()) {
Expand All @@ -3148,44 +3091,41 @@ class AdjointEmitter final : public SILInstructionVisitor<AdjointEmitter> {
eltVals.push_back(av);
else
eltVals.push_back(AdjointValue::getZero(
SILType::getPrimitiveObjectType(field->getType()
->getCanonicalType())));
SILType::getPrimitiveObjectType(
field->getType()->getCanonicalType())));
}
addAdjointValue(sei->getOperand(),
AdjointValue::getAggregate(cotangentVectorSILTy,
eltVals, allocator));
}
}

return;
}

// The only remaining strategy is the getter strategy.
// Replace the `struct_extract` with a call to its pullback.
assert(differentiationStrategy ==
StructExtractDifferentiationStrategy::Getter);

// Get the pullback.
auto *pullbackField = getPrimalInfo().lookUpPullbackDecl(sei);
assert(pullbackField);
SILValue pullback = builder.createStructExtract(loc,
primalValueAggregateInAdj,
pullbackField);

// Construct the pullback arguments.
SmallVector<SILValue, 8> args;
auto seed = getAdjointValue(sei);
assert(seed.getType().isObject());
args.push_back(materializeAdjointDirect(seed, loc));

// Call the pullback.
auto *pullbackCall = builder.createApply(loc, pullback, SubstitutionMap(),
args, /*isNonThrowing*/ false);
assert(!pullbackCall->hasIndirectResults());

// Set adjoint for the `struct_extract` operand.
addAdjointValue(sei->getOperand(),
AdjointValue::getMaterialized(pullbackCall));
case StructExtractDifferentiationStrategy::Getter: {
// Get the pullback.
auto *pullbackField = getPrimalInfo().lookUpPullbackDecl(sei);
assert(pullbackField);
SILValue pullback = builder.createStructExtract(loc,
primalValueAggregateInAdj,
pullbackField);

// Construct the pullback arguments.
SmallVector<SILValue, 8> args;
auto seed = getAdjointValue(sei);
assert(seed.getType().isObject());
args.push_back(materializeAdjointDirect(seed, loc));

// Call the pullback.
auto *pullbackCall = builder.createApply(loc, pullback, SubstitutionMap(),
args, /*isNonThrowing*/ false);
assert(!pullbackCall->hasIndirectResults());

// Set adjoint for the `struct_extract` operand.
addAdjointValue(sei->getOperand(),
AdjointValue::getMaterialized(pullbackCall));
break;
}
}
}

/// Handle `tuple` instruction.
Expand Down Expand Up @@ -4236,25 +4176,22 @@ void DifferentiationTask::createVJP() {
loc, adjointRef, vjpSubstMap, partialAdjointArgs,
ParameterConvention::Direct_Guaranteed);

// === Clean up the stack allocations. ===
// Clean up the stack allocations.
for (auto alloc : reversed(stackAllocsToCleanUp))
builder.createDeallocStack(loc, alloc);

// === Return the direct results. ===
// (Note that indirect results have already been filled in by the application
// of the primal).
// Return the direct results. Note that indirect results have already been
// filled in by the application of the primal.
SmallVector<SILValue, 8> directResults;
auto originalDirectResults = ArrayRef<SILValue>(primalDirectResults)
.take_back(originalConv.getNumDirectSILResults());
for (auto originalDirectResult : originalDirectResults)
directResults.push_back(originalDirectResult);
directResults.push_back(adjointPartialApply);
if (directResults.size() > 1) {
auto tupleRet = builder.createTuple(loc, directResults);
builder.createReturn(loc, tupleRet);
} else {
builder.createReturn(loc, directResults[0]);
}
if (directResults.size() > 1)
builder.createReturn(loc, builder.createTuple(loc, directResults));
else
builder.createReturn(loc, directResults.front());
}

//===----------------------------------------------------------------------===//
Expand Down
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