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[AutoDiff] Fix autodiff_function instruction worklist. #24941

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Merged
merged 1 commit into from
May 21, 2019
Merged

[AutoDiff] Fix autodiff_function instruction worklist. #24941

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26 changes: 20 additions & 6 deletions lib/SILOptimizer/Mandatory/Differentiation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3181,6 +3181,14 @@ class VJPEmitter final
recursivelyDeleteTriviallyDeadInstructions(
getOpValue(origCallee)->getDefiningInstruction());
}

void visitAutoDiffFunctionInst(AutoDiffFunctionInst *adfi) {
// Clone `autodiff_function` from original to VJP, then add the cloned
// instruction to the `autodiff_function` worklist.
SILClonerWithScopes::visitAutoDiffFunctionInst(adfi);
auto *newADFI = cast<AutoDiffFunctionInst>(getOpValue(adfi));
context.getAutoDiffFunctionInsts().push_back(newADFI);
}
};
} // end anonymous namespace

Expand Down Expand Up @@ -5948,7 +5956,8 @@ SILValue ADContext::promoteToDifferentiableFunction(
///
/// Folding can be disabled by the `SkipFoldingAutoDiffFunctionExtraction` flag
/// for SIL testing purposes.
static void foldAutoDiffFunctionExtraction(AutoDiffFunctionInst *source) {
static void foldAutoDiffFunctionExtraction(
ADContext &context, AutoDiffFunctionInst *source) {
// Iterate through all `autodiff_function` instruction uses.
for (auto use : source->getUses()) {
auto *adfei = dyn_cast<AutoDiffFunctionExtractInst>(use->getUser());
Expand All @@ -5970,8 +5979,14 @@ static void foldAutoDiffFunctionExtraction(AutoDiffFunctionInst *source) {
adfei->eraseFromParent();
}
// If the `autodiff_function` instruction has no remaining uses, erase it.
if (isInstructionTriviallyDead(source))
source->eraseFromParent();
if (!isInstructionTriviallyDead(source))
return;
source->eraseFromParent();
// Delete all worklist occurrences of `source` by setting them to nullptr.
// This is more efficient than APIs like `llvm::erase_if`.
for (auto &inst : context.getAutoDiffFunctionInsts())
if (inst == source)
inst = nullptr;
}

bool ADContext::processAutoDiffFunctionInst(AutoDiffFunctionInst *adfi) {
Expand Down Expand Up @@ -6000,11 +6015,10 @@ bool ADContext::processAutoDiffFunctionInst(AutoDiffFunctionInst *adfi) {
adfi->eraseFromParent();
// If the promoted `@differentiable` function-typed value is an
// `autodiff_function` instruction, fold `autodiff_function_extract`
// instructions.
// If `autodiff_function_extract` folding is disabled, return.
// instructions. If `autodiff_function_extract` folding is disabled, return.
if (!SkipFoldingAutoDiffFunctionExtraction)
if (auto *newADFI = dyn_cast<AutoDiffFunctionInst>(differentiableFnValue))
foldAutoDiffFunctionExtraction(newADFI);
foldAutoDiffFunctionExtraction(*this, newADFI);
transform.invalidateAnalysis(
parent, SILAnalysis::InvalidationKind::FunctionBody);
return false;
Expand Down