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//===--- DifferentiabilityWitnessDevirtualizer.cpp ------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 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
//
//===----------------------------------------------------------------------===//
//
// Devirtualizes `differentiability_witness_function` instructions into
// `function_ref` instructions for differentiability witness definitions.
//
//===----------------------------------------------------------------------===//
#include "swift/SIL/SILBuilder.h"
#include "swift/SIL/SILFunction.h"
#include "swift/SIL/SILInstruction.h"
#include "swift/SILOptimizer/PassManager/Transforms.h"
using namespace swift;
namespace {
class DifferentiabilityWitnessDevirtualizer : public SILFunctionTransform {
/// Returns true if any changes were made.
bool devirtualizeDifferentiabilityWitnessesInFunction(SILFunction &f);
/// The entry point to the transformation.
void run() override {
if (devirtualizeDifferentiabilityWitnessesInFunction(*getFunction()))
invalidateAnalysis(SILAnalysis::InvalidationKind::CallsAndInstructions);
}
};
} // end anonymous namespace
bool DifferentiabilityWitnessDevirtualizer::
devirtualizeDifferentiabilityWitnessesInFunction(SILFunction &f) {
bool changed = false;
llvm::SmallVector<DifferentiabilityWitnessFunctionInst *, 8> insts;
for (auto &bb : f) {
for (auto &inst : bb) {
auto *dfwi = dyn_cast<DifferentiabilityWitnessFunctionInst>(&inst);
if (!dfwi)
continue;
insts.push_back(dfwi);
}
}
for (auto *inst : insts) {
auto *witness = inst->getWitness();
if (witness->isDeclaration())
f.getModule().loadDifferentiabilityWitness(witness);
if (witness->isDeclaration())
continue;
changed = true;
SILBuilderWithScope builder(inst);
auto kind = inst->getWitnessKind().getAsDerivativeFunctionKind();
assert(kind.has_value());
auto *newInst = builder.createFunctionRefFor(inst->getLoc(),
witness->getDerivative(*kind));
inst->replaceAllUsesWith(newInst);
inst->getParent()->erase(inst);
}
return changed;
}
SILTransform *swift::createDifferentiabilityWitnessDevirtualizer() {
return new DifferentiabilityWitnessDevirtualizer();
}
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