283 lines
10 KiB
C++
283 lines
10 KiB
C++
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//====- lower_frontend_to_krnl.cpp - Frontend dialects to Krnl lowering ---===//
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//
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// Copyright 2019 The DLC Authors.
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//
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// =============================================================================
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//
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// This file implements the lowering of frontend operations to a combination of
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// Krnl IR and standard operations.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/Sequence.h"
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#include "mlir/Dialect/AffineOps/AffineOps.h"
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#include "mlir/Dialect/StandardOps/Ops.h"
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#include "mlir/Pass/Pass.h"
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#include "mlir/Transforms/DialectConversion.h"
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#include "src/compiler/dialect/krnl/krnl_ops.hpp"
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#include "src/compiler/dialect/onnx/onnx_ops.hpp"
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#include "src/compiler/pass/passes.hpp"
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using namespace mlir;
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//===----------------------------------------------------------------------===//
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// FrontendToAffine RewritePatterns
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//===----------------------------------------------------------------------===//
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/// Check is all dimensions are known at compile time.
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static bool hasAllConstantDimensions(MemRefType type) {
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auto memRefShape = type.getShape();
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for (int i = 0; i < memRefShape.size(); ++i)
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if (memRefShape[i] < 0)
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return false;
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return true;
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}
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/// Convert the given TensorType into the corresponding MemRefType.
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static MemRefType convertTensorToMemRef(TensorType type) {
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assert(type.hasRank() && "expected only ranked shapes");
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return MemRefType::get(type.getShape(), type.getElementType());
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}
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/// Insert an allocation and deallocation for the given MemRefType.
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static Value* insertAllocAndDealloc(
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MemRefType type, Location loc, PatternRewriter& rewriter,
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Value *oldMemRef = nullptr) {
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// Put together alloc operands for any dynamic dimensions of the memref.
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AllocOp alloc;
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if (oldMemRef) {
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SmallVector<Value *, 4> allocOperands;
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auto memRefShape = type.getShape();
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for (int i = 0; i < memRefShape.size(); ++i)
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if (memRefShape[i] < 0)
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allocOperands.push_back(rewriter.create<DimOp>(loc, oldMemRef, i));
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alloc = rewriter.create<AllocOp>(loc, type, allocOperands);
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} else {
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alloc = rewriter.create<AllocOp>(loc, type);
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}
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// Make sure to allocate at the beginning of the block if
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// all dimensions are known.
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auto* parentBlock = alloc.getOperation()->getBlock();
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if (hasAllConstantDimensions(type))
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alloc.getOperation()->moveBefore(&parentBlock->front());
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return alloc;
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}
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namespace {
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//===----------------------------------------------------------------------===//
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// AddOp lowering to Krnl dialect.
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//===----------------------------------------------------------------------===//
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struct ONNXAddOpLowering : public ConversionPattern {
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ONNXAddOpLowering(MLIRContext* ctx)
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: ConversionPattern(mlir::ONNXAddOp::getOperationName(), 1, ctx) {}
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PatternMatchResult matchAndRewrite(Operation* op, ArrayRef<Value*> operands,
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ConversionPatternRewriter& rewriter) const final {
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// TODO: Check that the types are valid.
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// Add is an operation that must have all operands and the result of
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// the same type. This should have been verified by the verifier.
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auto tensorType = (*op->result_type_begin()).cast<TensorType>();
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auto loc = op->getLoc();
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// Insert an allocation and deallocation for the result of this operation.
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auto memRefType = convertTensorToMemRef(tensorType);
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// If the output has a dynamic dimension, pass the operands required for
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// each dynamic dimension to the AllocOp. The first operand of the Add
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// operation is used. The operands of the Add need to match in terms of
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// dimensions with the result at this pre-optimization phase.
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// TODO: verify that dimensions match.
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// TODO: can the dimension of the result differ after optimizations?
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Value *alloc;
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if (hasAllConstantDimensions(memRefType))
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alloc = insertAllocAndDealloc(memRefType, loc, rewriter);
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else
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alloc = insertAllocAndDealloc(memRefType, loc, rewriter, operands[0]);
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// Number of loops
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auto memRefShape = memRefType.getShape();
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int64_t rank = memRefShape.size();
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// Define loops.
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auto loopsOp = rewriter.create<KrnlDefineLoopsOp>(loc, rank);
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std::vector<Value*> originalLoops;
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originalLoops.reserve(rank);
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for (auto result : loopsOp.getResults()) {
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originalLoops.push_back(result);
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}
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// Define loop optimization.
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auto optimizedLoopsOp = rewriter.create<KrnlOptimizeLoopsOp>(loc, rank);
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std::vector<Value*> optimizedLoops;
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optimizedLoops.reserve(rank);
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for (auto result : optimizedLoopsOp.getResults()) {
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optimizedLoops.push_back(result);
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}
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Block& optimizationBlock = optimizedLoopsOp.region().front();
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// Iterate over the loop nest.
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// TODO (Tian): move this logic inside KrnlIterateOp. Pass MemRefShape
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// to KrnlIterateOp instead.
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SmallVector<Value*, 8> operandBounds;
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SmallVector<int64_t, 8> constBounds;
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SmallVector<int, 16> boundTypes;
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for (int i = 0; i < rank; ++i) {
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if (memRefShape[i] < 0) {
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// This is a dynamic value, hence use operands.
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// Lower bound
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constBounds.push_back(0);
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boundTypes.push_back(0);
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// Upper bound
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operandBounds.push_back(
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rewriter.create<DimOp>(loc, operands[0], i).getResult());
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boundTypes.push_back(1);
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} else {
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// Lower bound
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constBounds.push_back(0);
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boundTypes.push_back(0);
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// Upper bound
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constBounds.push_back(memRefShape[i]);
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boundTypes.push_back(0);
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}
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}
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auto iterateOp = rewriter.create<KrnlIterateOp>(loc, originalLoops,
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optimizedLoops, operandBounds, constBounds, boundTypes);
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Block& iterationBlock = iterateOp.bodyRegion().front();
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// Now perform the insertions into the body of the
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// just generated instructions:
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// 1. Insert any optimizations in the KrnlOptimizeLoopsOp body.
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rewriter.setInsertionPointToEnd(&optimizationBlock);
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// Return from KrnlOptimizeLoopsOp body.
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// When no optimizations are present we just return the loops
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// unchaged.
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rewriter.create<KrnlReturnLoopsOp>(loc, originalLoops);
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rewriter.setInsertionPoint(optimizedLoopsOp);
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// 2. Insert instructions inside the KernelIterateOp body.
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rewriter.setInsertionPointToStart(&iterationBlock);
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// Handle AddOp:
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SmallVector<Value*, 4> loopIVs;
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for (auto arg : iterationBlock.getArguments())
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loopIVs.push_back(arg);
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auto loadedFirstVal =
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rewriter.create<LoadOp>(loc, operands[0], loopIVs);
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auto loadedSecondVal =
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rewriter.create<LoadOp>(loc, operands[1], loopIVs);
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// TODO: Choose type of the Add for now use the Float Add.
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auto addOpResult = rewriter.create<AddFOp>(
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loc, loadedFirstVal, loadedSecondVal);
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// Store result in the resulting array.
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rewriter.create<StoreOp>(loc, addOpResult, alloc, loopIVs);
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rewriter.replaceOp(op, alloc);
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return matchSuccess();
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}
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};
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//===----------------------------------------------------------------------===//
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// Conversion from Tensor type to the Standard dialect MemRef type.
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//===----------------------------------------------------------------------===//
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struct TensorTypeConverter : public TypeConverter {
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using TypeConverter::TypeConverter;
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LogicalResult convertType(Type t, SmallVectorImpl<Type>& results) override {
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if (auto tensor_type = t.dyn_cast<TensorType>()) {
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results.push_back(convertTensorToMemRef(tensor_type));
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return success();
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}
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results.push_back(t);
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return success();
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}
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/// Return true if the inputs and outputs of the given function type are
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/// legal. [Taken from MLIR and adapted to only check the legality of the
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/// inputs. Once unranked results can be handled gracefully this
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/// override needs to be removed in favour of the original MLIR one.]
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bool isSignatureLegal(FunctionType funcType) {
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return llvm::all_of(funcType.getInputs(),
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[this](Type type) { return isLegal(type); });
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}
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};
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} // end anonymous namespace.
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//===----------------------------------------------------------------------===//
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// Frontend to Krnl Dialect lowering pass
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//===----------------------------------------------------------------------===//
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/// This is a partial lowering to Krnl loops of the ONNX operations.
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namespace {
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struct FrontendToKrnlLoweringPass
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: public ModulePass<FrontendToKrnlLoweringPass> {
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void runOnModule() final;
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};
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} // end anonymous namespace.
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void FrontendToKrnlLoweringPass::runOnModule() {
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auto module = getModule();
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// The first thing to define is the conversion target. This will define the
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// final target for this lowering.
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ConversionTarget target(getContext());
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// We define the specific operations, or dialects, that are legal targets for
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// this lowering.
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target
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.addLegalDialect<KrnlOpsDialect, AffineOpsDialect, StandardOpsDialect>();
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// TODO: enable this once more ops are supported.
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// We also define the ONNX dialect as Illegal so that the conversion will fail
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// if any of these operations are *not* converted.
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// target.addIllegalDialect<mlir::ONNXOpsDialect>();
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// TODO: add any other ops which are considered legal.
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// Some operations can be marked as being still legal.
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// Example: target.addLegalOp<mlir::OpName>();
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// Now that the conversion target has been defined, we just need to provide
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// the set of patterns that will lower the frontend operations.
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OwningRewritePatternList patterns;
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// Convert TensorType to MemRef
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TensorTypeConverter tensor_to_memref_converter;
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target.addDynamicallyLegalOp<FuncOp>([&](FuncOp op) {
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// FuncOp is legal only if types have been converted to Std types.
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return tensor_to_memref_converter.isSignatureLegal(op.getType());
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});
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// Type conversion for function signatures.
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// Call MLIR FuncOp signature conversion when result type is
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// a ranked tensor.
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populateFuncOpTypeConversionPattern(
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patterns, &getContext(), tensor_to_memref_converter);
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// Frontent operation lowering.
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patterns.insert<ONNXAddOpLowering>(&getContext());
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// With the target and rewrite patterns defined, we can now attempt the
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// conversion. The conversion will signal failure if any of our `illegal`
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// operations were not converted successfully.
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if (failed(applyPartialConversion(
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module, target, patterns)))
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signalPassFailure();
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}
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std::unique_ptr<Pass> mlir::createLowerToKrnlPass() {
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return std::make_unique<FrontendToKrnlLoweringPass>();
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}
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