mirror of https://github.com/llvm/torch-mlir
299 lines
12 KiB
C++
299 lines
12 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This is the base file for npcomp's "reference backend".
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//
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// The input to this backend is a layer that we call "TCP" + a mix of scalar
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// ops. TCP is currently a concrete dialect, but more generally it refers to a
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// layer of the compilation stack consisting of named ops on entire tensors,
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// with their preconditions checked. For example, a "matmul" op that assumes
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// that the contracting ("k") dimensions of both operands are equal. Earlier
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// code in the compilation stack should ensure that these preconditions are met
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// (such as during TCF->TCP lowering).
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//
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// The output of this backend is LLVM IR suitable for JITing.
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//
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// We expect that other backends will appear that have a similar kind of
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// interface (TCP + scalar ops ---> LLVM IR / other "executable").
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//
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//===----------------------------------------------------------------------===//
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#include "npcomp/RefBackend/RefBackend.h"
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#include "PassDetail.h"
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#include "mlir/Conversion/SCFToStandard/SCFToStandard.h"
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#include "mlir/Conversion/ShapeToStandard/ShapeToStandard.h"
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#include "mlir/Dialect/Linalg/IR/LinalgOps.h"
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#include "mlir/Dialect/Linalg/IR/LinalgTypes.h"
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#include "mlir/Dialect/Linalg/Passes.h"
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#include "mlir/Dialect/Shape/IR/Shape.h"
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#include "mlir/Dialect/StandardOps/IR/Ops.h"
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#include "mlir/Pass/Pass.h"
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#include "mlir/Pass/PassRegistry.h"
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#include "mlir/Transforms/DialectConversion.h"
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#include "mlir/Transforms/Passes.h"
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#include "npcomp/Conversion/TCFToTCP/TCFToTCP.h"
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#include "npcomp/Dialect/Refback/IR/RefbackOps.h"
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#include "npcomp/Dialect/TCP/IR/TCPDialect.h"
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#include "npcomp/Dialect/TCP/IR/TCPOps.h"
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#include "npcomp/Dialect/TCP/Transforms/Passes.h"
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using namespace mlir;
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using namespace mlir::NPCOMP;
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//===----------------------------------------------------------------------===//
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// Pass registration
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//===----------------------------------------------------------------------===//
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namespace {
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#define GEN_PASS_REGISTRATION
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#include "npcomp/RefBackend/Passes.h.inc"
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} // end namespace
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void mlir::NPCOMP::registerRefBackendPasses() {
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::registerPasses();
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mlir::PassPipelineRegistration<RefBackendLoweringPipelineOptions>(
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"refback-lowering-pipeline", "RefBackend lowering pipeline.",
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mlir::NPCOMP::createRefBackendLoweringPipeline);
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mlir::PassPipelineRegistration<RefBackendLoweringPipelineOptions>(
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"tcf-refback-lowering-pipeline",
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"RefBackend lowering pipeline, starting from TCF.",
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mlir::NPCOMP::createTCFRefBackendLoweringPipeline);
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}
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//===----------------------------------------------------------------------===//
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// LowerAllocMemRefOps
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//===----------------------------------------------------------------------===//
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namespace {
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class LowerAllocMemRefOp : public OpRewritePattern<refback::AllocMemRefOp> {
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public:
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using OpRewritePattern::OpRewritePattern;
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LogicalResult matchAndRewrite(refback::AllocMemRefOp op,
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PatternRewriter &rewriter) const override {
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auto memrefType = op.getType().cast<MemRefType>();
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auto shape = op.getOperand();
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// std.alloc only accepts the dynamic extents as operands, so only
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// collect those.
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SmallVector<Value, 6> dynamicExtents;
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for (int i = 0, e = memrefType.getRank(); i < e; i++) {
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if (memrefType.isDynamicDim(i)) {
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auto extent =
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rewriter.create<shape::GetExtentOp>(op.getLoc(), shape, i);
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dynamicExtents.push_back(extent);
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}
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}
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rewriter.replaceOpWithNewOp<AllocOp>(op, memrefType, dynamicExtents);
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return success();
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}
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};
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} // namespace
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namespace {
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class LowerAllocMemRefOps
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: public LowerAllocMemRefOpsBase<LowerAllocMemRefOps> {
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void getDependentDialects(DialectRegistry ®istry) const override {
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registry.insert<shape::ShapeDialect>();
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}
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void runOnOperation() override {
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auto func = getOperation();
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auto *context = &getContext();
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OwningRewritePatternList patterns;
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patterns.insert<LowerAllocMemRefOp>(context);
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ConversionTarget target(*context);
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target.addIllegalOp<refback::AllocMemRefOp>();
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target.addLegalOp<shape::GetExtentOp>();
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target.addLegalOp<AllocOp>();
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target.addLegalOp<ConstantOp>();
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if (failed(applyPartialConversion(func, target, patterns))) {
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return signalPassFailure();
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}
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}
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};
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} // namespace
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std::unique_ptr<OperationPass<FuncOp>>
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mlir::NPCOMP::createLowerAllocMemRefOpsPass() {
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return std::make_unique<LowerAllocMemRefOps>();
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}
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//===----------------------------------------------------------------------===//
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// RestrictedCanonicalizer
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//===----------------------------------------------------------------------===//
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namespace {
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struct RestrictedCanonicalizer
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: public RestrictedCanonicalizerBase<RestrictedCanonicalizer> {
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void runOnOperation() override {
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auto *context = &getContext();
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// Find the dialects from their names.
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DenseSet<StringRef> neededDialects;
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for (const std::string &dialectName : includedDialects)
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neededDialects.insert(dialectName);
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DenseSet<Dialect *> dialectsToCanonicalize;
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for (Dialect *dialect : context->getLoadedDialects()) {
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if (neededDialects.count(dialect->getNamespace())) {
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dialectsToCanonicalize.insert(dialect);
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// Erase the dialect so that we can report an error below for any
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// dialect names that are not loaded.
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neededDialects.erase(dialect->getNamespace());
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}
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}
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// Report a helpful error if a dialect is not found.
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auto missingDialects = llvm::to_vector<6>(neededDialects);
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if (!missingDialects.empty()) {
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llvm::sort(missingDialects);
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std::string buf;
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llvm::raw_string_ostream os(buf);
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llvm::interleaveComma(missingDialects, os);
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llvm::report_fatal_error("restricted-canonicalize: unknown dialects: " +
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os.str());
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}
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// Collect all canonicalization patterns from ops in the included dialects.
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OwningRewritePatternList patterns;
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for (AbstractOperation *op : context->getRegisteredOperations())
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if (dialectsToCanonicalize.count(&op->dialect))
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op->getCanonicalizationPatterns(patterns, context);
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Operation *op = getOperation();
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applyPatternsAndFoldGreedily(op->getRegions(), patterns);
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}
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};
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} // end anonymous namespace
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std::unique_ptr<Pass> mlir::NPCOMP::createRestrictedCanonicalizerPass() {
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return std::make_unique<RestrictedCanonicalizer>();
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}
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//===----------------------------------------------------------------------===//
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// createRefBackendLoweringPipeline
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//===----------------------------------------------------------------------===//
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void mlir::NPCOMP::createRefBackendLoweringPipeline(
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OpPassManager &pm, const RefBackendLoweringPipelineOptions &options) {
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// Lower shape constraints before we enter tensor->memref conversion.
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// That is, we expand shape.cstr_* ops to eager error handling code.
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pm.addPass(createConvertShapeConstraintsPass());
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// Run shape canonicalizations. In particular, this erases shape.assuming,
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// now that we have converted shape constraints.
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// TODO: This is kind of ugly. Either we use pass options or a constructor
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// that takes C++ data structures. The former makes the pass usable on the
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// command line (including reproducers), the latter makes the pass more
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// convenient.
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std::unique_ptr<Pass> shapeCanonicalizer =
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createRestrictedCanonicalizerPass();
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if (failed(shapeCanonicalizer->initializeOptions("included-dialects=shape")))
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llvm::report_fatal_error("couldn't initialize restricted-canonicalize");
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pm.addPass(std::move(shapeCanonicalizer));
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// --------------------------------------------------------------------------
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// Lower the `tensor` type to `memref`.
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// --------------------------------------------------------------------------
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// We make a conscious effort here to do this as a sequence of separate passes
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// rather than a single mega dialect conversion pass.
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//
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// This means that intermediate steps have source/target materializations
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// (tensor_load / tensor_to_memref) in the IR.
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// Bufferize the TCP dialect.
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pm.addPass(createTCPBufferizePass());
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// Lower tensor-valued constants to refback.global.
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pm.addPass(createLowerConstantTensorsToMemrefPass());
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// refback::AllocMemRefOp takes a shape (i.e. extent tensor) as an argument.
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// We need to resolve this to std.alloc which takes individual extents.
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pm.addPass(createLowerAllocMemRefOpsPass());
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// Lower shape ops to std.
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// TODO: This should in principle be moved before tensor->memref conversion.
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// But some of the tensor->memref lowerings above use shape.get_extent. For
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// example, when lowering a broadcast, we need to get an extent from its shape
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// operand to allocate the output.
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pm.addPass(createConvertShapeToStandardPass());
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// Lower std ops to memref.
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// This includes ops like extract_element.
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pm.addPass(createLowerStdToMemrefPass());
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// Lower control flow and other "structural" ops.
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//
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// These ops are generally not sensitive to the types that they operate on
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// (e.g. the types of block operands, function arguments, etc.). But they all
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// need to be converted consistently. So it makes sense to do this as the
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// final step of conversion, which also finalizes the elimination of all
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// stray source/target materializations introduced by the incremental
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// tensor->memref lowering.
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//
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// This completes conversion to memref. There are no `tensor`'s after
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// this point.
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pm.addPass(createLowerStructuralToMemrefPass());
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// TODO: Do buffer assignment. We should be able to just drop in the upstream
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// pass?
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// At this point, we have lots of loose stuff floating around from lowering,
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// so it's a good time to do some general cleanups.
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if (options.optimize) {
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pm.addPass(createCanonicalizerPass());
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pm.addPass(createCSEPass());
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}
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// --------------------------------------------------------------------------
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// Preparation for converting to an LLVM module.
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// --------------------------------------------------------------------------
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// Now, we begin the process of lowering to LLVM's level of abstraction
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// (after which LLVM will take over lowering to machine code).
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// Lower linalg ops to loops.
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// TODO: Do some linalg optimizations like tiling here.
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pm.addPass(createConvertLinalgToLoopsPass());
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// Run a some cleanups.
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if (options.optimize) {
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pm.addPass(createCanonicalizerPass());
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pm.addPass(createCSEPass());
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}
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// --------------------------------------------------------------------------
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// Final conversion to an LLVM module.
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// --------------------------------------------------------------------------
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// Convert scf to std control flow in preparation for going to LLVM.
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pm.addPass(createLowerToCFGPass());
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// Convert functions signatures and other constructs that interface with the
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// runtime to the `refbackrt` dialect.
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pm.addPass(createLowerToRefbackrtABIPass());
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// Finally, convert to LLVM dialect using our custom LowerToLLVM pass
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// which reuses the upstream patterns and gives us a place to add our own
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// patterns for our own custom ops like the refbackrt ops.
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pm.addPass(createLowerToLLVMPass());
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// Although LLVM will clean everything up eventually, for the sake of IR
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// clarity while still in MLIR, run some cleanups.
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if (options.optimize) {
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pm.addPass(createCanonicalizerPass());
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pm.addPass(createCSEPass());
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}
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}
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void mlir::NPCOMP::createTCFRefBackendLoweringPipeline(
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OpPassManager &pm, const RefBackendLoweringPipelineOptions &options) {
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// Convert from TCF to TCP.
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//
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// TCF has implicit broadcasting, and issues errors "inside the ops" in the
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// case of invalid broadcasts.
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//
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// TCP does not. So we need to reify the broadcasting and error checking.
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pm.addPass(createConvertTCFToTCPPass());
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createRefBackendLoweringPipeline(pm, options);
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}
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