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[AutoDiff] Unify adjoint entry block generation with the general logic. #25255

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Jun 5, 2019
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[AutoDiff] Unify adjoint entry block generation with the general logic. #25255

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[AutoDiff] Unify adjoint entry block generation with the general logic.
rxwei Jun 5, 2019
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Address comments.
rxwei Jun 5, 2019
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27 changes: 19 additions & 8 deletions lib/SILOptimizer/Mandatory/Differentiation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4130,6 +4130,10 @@ class AdjointEmitter final : public SILInstructionVisitor<AdjointEmitter> {
: nullptr;
Lowering::GenericContextScope genericContextScope(
getContext().getTypeConverter(), adjGenSig);
auto origExitIt = original.findReturnBB();
assert(origExitIt != original.end() &&
"Functions without returns must have been diagnosed");
auto *origExit = &*origExitIt;

// Get dominated active values in original blocks.
// Adjoint values of dominated active values are passed as adjoint block
Expand Down Expand Up @@ -4174,12 +4178,22 @@ class AdjointEmitter final : public SILInstructionVisitor<AdjointEmitter> {
for (auto *origBB : postOrderInfo->getPostOrder()) {
auto *adjointBB = adjoint.createBasicBlock();
adjointBBMap.insert({origBB, adjointBB});
// If adjoint block is the adjoint entry, continue.
if (adjointBB->isEntry())
continue;
// Otherwise, add a pullback struct argument to the adjoint block.
auto pbStructLoweredType =
remapType(getPullbackInfo().getPullbackStructLoweredType(origBB));
// If the BB is the original exit, then the adjoint block that we just
// created must be the adjoint function's entry. For the adjoint entry,
// create entry arguments and continue to the next block.
if (origBB == origExit) {
assert(adjointBB->isEntry());
createEntryArguments(&getAdjoint());
auto *lastArg = adjointBB->getArguments().back();
assert(lastArg->getType() == pbStructLoweredType);
adjointPullbackStructArguments[origBB] = lastArg;
continue;
}

// Otherwise, we create a phi argument for the corresponding pullback
// struct, and handle dominated active values/buffers.
auto *pbStructArg = adjointBB->createPhiArgument(
pbStructLoweredType, ValueOwnershipKind::Guaranteed);
adjointPullbackStructArguments[origBB] = pbStructArg;
Expand Down Expand Up @@ -4221,15 +4235,11 @@ class AdjointEmitter final : public SILInstructionVisitor<AdjointEmitter> {
}
}

auto *origEntry = original.getEntryBlock();
auto *origExit = &*original.findReturnBB();
auto *adjointEntry = adjoint.getEntryBlock();
createEntryArguments(&adjoint);
// The adjoint function has type (seed, exit_pbs) -> ([arg0], ..., [argn]).
auto adjParamArgs = adjoint.getArgumentsWithoutIndirectResults();
assert(adjParamArgs.size() == 2);
seed = adjParamArgs[0];
adjointPullbackStructArguments[origExit] = adjParamArgs[1];

// Assign adjoint for original result.
SmallVector<SILValue, 8> origFormalResults;
Expand Down Expand Up @@ -4433,6 +4443,7 @@ class AdjointEmitter final : public SILInstructionVisitor<AdjointEmitter> {
// Place the builder at the adjoint exit, i.e. the adjoint block
// corresponding to the original entry. Return the adjoints wrt parameters
// in the adjoint exit.
auto *origEntry = getOriginal().getEntryBlock();
builder.setInsertionPoint(getAdjointBlock(origEntry));

// This vector will contain all the materialized return elements.
Expand Down