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//===--- TangentBuilder.cpp - Tangent SIL builder ------------*- C++ -*----===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2019 - 2020 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
//
//===----------------------------------------------------------------------===//
//
// This file defines a helper class for emitting tangent code for automatic
// differentiation.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "differentiation"
#include "swift/SILOptimizer/Differentiation/TangentBuilder.h"
#include "swift/SILOptimizer/Differentiation/ADContext.h"
namespace swift {
namespace autodiff {
void TangentBuilder::emitZeroIntoBuffer(SILLocation loc, SILValue buffer,
IsInitialization_t isInit) {
if (!isInit)
emitDestroyAddr(loc, buffer);
if (auto tupleType = buffer->getType().getAs<TupleType>()) {
for (unsigned i : range(tupleType->getNumElements())) {
auto *eltAddr = createTupleElementAddr(loc, buffer, i);
emitZeroIntoBuffer(loc, eltAddr, IsInitialization);
}
return;
}
auto *swiftMod = getModule().getSwiftModule();
// Look up conformance to `AdditiveArithmetic`.
auto *additiveArithmeticProto = adContext.getAdditiveArithmeticProtocol();
auto astType = buffer->getType().getASTType();
auto confRef = swiftMod->lookupConformance(astType, additiveArithmeticProto);
assert(!confRef.isInvalid() && "Missing conformance to `AdditiveArithmetic`");
SILDeclRef accessorDeclRef(adContext.getAdditiveArithmeticZeroGetter(),
SILDeclRef::Kind::Func);
auto silFnType = getModule().Types.getConstantType(
getTypeExpansionContext(), accessorDeclRef);
// %wm = witness_method ...
auto *getter = createWitnessMethod(
loc, astType, confRef, accessorDeclRef, silFnType);
// %metatype = metatype $T
auto metatypeType = CanMetatypeType::get(astType,
MetatypeRepresentation::Thick);
auto metatype = createMetatype(
loc, SILType::getPrimitiveObjectType(metatypeType));
auto subMap = SubstitutionMap::getProtocolSubstitutions(
additiveArithmeticProto, astType, confRef);
createApply(loc, getter, subMap, {buffer, metatype});
emitDestroyValueOperation(loc, getter);
}
SILValue TangentBuilder::emitZero(SILLocation loc, CanType type) {
auto silType = getModule().Types.getLoweredLoadableType(
type, TypeExpansionContext::minimal(), getModule());
auto tempAllocLoc = RegularLocation::getAutoGeneratedLocation();
auto *alloc = createAllocStack(tempAllocLoc, silType);
emitZeroIntoBuffer(loc, alloc, IsInitialization);
auto zeroValue = emitLoadValueOperation(
loc, alloc, LoadOwnershipQualifier::Take);
createDeallocStack(loc, alloc);
return zeroValue;
}
void TangentBuilder::emitInPlaceAdd(
SILLocation loc, SILValue destinationBuffer, SILValue operand) {
assert(destinationBuffer->getType().isAddress());
auto type = destinationBuffer->getType();
if (auto tupleType = type.getAs<TupleType>()) {
for (unsigned i : range(tupleType->getNumElements())) {
auto *eltDestAddr = createTupleElementAddr(loc, destinationBuffer, i);
switch (operand->getType().getCategory()) {
case SILValueCategory::Address: {
auto *eltOperand = createTupleElementAddr(loc, operand, i);
emitInPlaceAdd(loc, eltDestAddr, eltOperand);
break;
}
case SILValueCategory::Object: {
auto borrowedOp = emitBeginBorrowOperation(loc, operand);
auto eltOperand = emitTupleExtract(loc, borrowedOp, i);
emitInPlaceAdd(loc, eltDestAddr, eltOperand);
emitEndBorrowOperation(loc, borrowedOp);
break;
}
}
}
return;
}
// Call the combiner function and return.
auto *swiftMod = getModule().getSwiftModule();
auto astType = type.getASTType();
auto confRef = swiftMod->lookupConformance(
astType, adContext.getAdditiveArithmeticProtocol());
assert(!confRef.isInvalid() &&
"Missing conformance to `AdditiveArithmetic`");
SILDeclRef declRef(adContext.getPlusEqualDecl(), SILDeclRef::Kind::Func);
auto silFnTy = getModule().Types.getConstantType(
getTypeExpansionContext(), declRef);
// %0 = witness_method @+=
auto witnessMethod =
createWitnessMethod(loc, astType, confRef, declRef, silFnTy);
auto subMap = SubstitutionMap::getProtocolSubstitutions(
adContext.getAdditiveArithmeticProtocol(), astType, confRef);
// %1 = metatype $T.Type
auto metatypeType =
CanMetatypeType::get(astType, MetatypeRepresentation::Thick);
auto metatypeSILType = SILType::getPrimitiveObjectType(metatypeType);
auto metatype = createMetatype(loc, metatypeSILType);
// %2 = apply $0(%lhs, %rhs, %1)
createApply(loc, witnessMethod, subMap,
{destinationBuffer, operand, metatype});
emitDestroyValueOperation(loc, witnessMethod);
}
void TangentBuilder::emitAddIntoBuffer(SILLocation loc,
SILValue destinationBuffer,
SILValue lhsAddress,
SILValue rhsAddress) {
assert(lhsAddress->getType().getASTType() ==
rhsAddress->getType().getASTType() &&
"Adjoint values must have same type!");
assert(lhsAddress->getType().isAddress() &&
rhsAddress->getType().isAddress() &&
"Adjoint values must both have address types!");
auto type = lhsAddress->getType();
if (auto tupleType = type.getAs<TupleType>()) {
for (unsigned i : range(tupleType->getNumElements())) {
auto *destAddr = createTupleElementAddr(loc, destinationBuffer, i);
auto *eltAddrLHS = createTupleElementAddr(loc, lhsAddress, i);
auto *eltAddrRHS = createTupleElementAddr(loc, rhsAddress, i);
emitAddIntoBuffer(loc, destAddr, eltAddrLHS, eltAddrRHS);
}
return;
}
auto astType = type.getASTType();
auto *proto = adContext.getAdditiveArithmeticProtocol();
auto *combinerFuncDecl = adContext.getPlusDecl();
// Call the combiner function and return.
auto *swiftMod = getModule().getSwiftModule();
auto confRef = swiftMod->lookupConformance(astType, proto);
assert(!confRef.isInvalid() &&
"Missing conformance to `AdditiveArithmetic`");
SILDeclRef declRef(combinerFuncDecl, SILDeclRef::Kind::Func);
auto silFnTy = getModule().Types.getConstantType(
getTypeExpansionContext(), declRef);
// %0 = witness_method @+
auto witnessMethod =
createWitnessMethod(loc, astType, confRef, declRef, silFnTy);
auto subMap =
SubstitutionMap::getProtocolSubstitutions(proto, astType, confRef);
// %1 = metatype $T.Type
auto metatypeType =
CanMetatypeType::get(astType, MetatypeRepresentation::Thick);
auto metatypeSILType = SILType::getPrimitiveObjectType(metatypeType);
auto metatype = createMetatype(loc, metatypeSILType);
// %2 = apply %0(%result, %new, %old, %1)
createApply(loc, witnessMethod, subMap,
{destinationBuffer, rhsAddress, lhsAddress, metatype});
emitDestroyValueOperation(loc, witnessMethod);
}
SILValue TangentBuilder::emitAdd(SILLocation loc, SILValue lhs, SILValue rhs) {
LLVM_DEBUG(getADDebugStream() << "Emitting adjoint accumulation for lhs: "
<< lhs << " and rhs: " << rhs);
assert(lhs->getType() == rhs->getType() && "Adjoints must have equal types!");
assert(lhs->getType().isObject() && rhs->getType().isObject() &&
"Adjoint types must be both object types!");
auto type = lhs->getType();
auto lhsCopy = emitCopyValueOperation(loc, lhs);
auto rhsCopy = emitCopyValueOperation(loc, rhs);
// Allocate buffers for inputs and output.
auto tempAllocLoc = RegularLocation::getAutoGeneratedLocation();
auto *resultBuf = createAllocStack(tempAllocLoc, type);
auto *lhsBuf = createAllocStack(tempAllocLoc, type);
auto *rhsBuf = createAllocStack(tempAllocLoc, type);
// Initialize input buffers.
emitStoreValueOperation(loc, lhsCopy, lhsBuf,
StoreOwnershipQualifier::Init);
emitStoreValueOperation(loc, rhsCopy, rhsBuf,
StoreOwnershipQualifier::Init);
emitAddIntoBuffer(loc, resultBuf, lhsBuf, rhsBuf);
emitDestroyAddr(loc, lhsBuf);
emitDestroyAddr(loc, rhsBuf);
// Deallocate input buffers.
createDeallocStack(loc, rhsBuf);
createDeallocStack(loc, lhsBuf);
auto val = emitLoadValueOperation(loc, resultBuf,
LoadOwnershipQualifier::Take);
// Deallocate result buffer.
createDeallocStack(loc, resultBuf);
return val;
}
} // end namespace autodiff
} // end namespace swift
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