110 lines · cpp
1//===- ParallelLoopCollapsing.cpp - Pass collapsing parallel loop indices -===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "mlir/Dialect/SCF/Transforms/Passes.h"10 11#include "mlir/Dialect/Affine/IR/AffineOps.h"12#include "mlir/Dialect/SCF/IR/SCF.h"13#include "mlir/Dialect/SCF/Utils/Utils.h"14#include "llvm/ADT/SmallSet.h"15#include "llvm/Support/Debug.h"16 17namespace mlir {18#define GEN_PASS_DEF_TESTSCFPARALLELLOOPCOLLAPSING19#include "mlir/Dialect/SCF/Transforms/Passes.h.inc"20} // namespace mlir21 22#define DEBUG_TYPE "parallel-loop-collapsing"23 24using namespace mlir;25 26namespace {27struct TestSCFParallelLoopCollapsing28 : public impl::TestSCFParallelLoopCollapsingBase<29 TestSCFParallelLoopCollapsing> {30 31 void runOnOperation() override {32 Operation *module = getOperation();33 34 // The common case for GPU dialect will be simplifying the ParallelOp to 335 // arguments, so we do that here to simplify things.36 llvm::SmallVector<std::vector<unsigned>, 3> combinedLoops;37 38 // Gather the input args into the format required by39 // `collapseParallelLoops`.40 if (!clCollapsedIndices0.empty())41 combinedLoops.push_back(clCollapsedIndices0);42 if (!clCollapsedIndices1.empty()) {43 if (clCollapsedIndices0.empty()) {44 llvm::errs()45 << "collapsed-indices-1 specified but not collapsed-indices-0";46 signalPassFailure();47 return;48 }49 combinedLoops.push_back(clCollapsedIndices1);50 }51 if (!clCollapsedIndices2.empty()) {52 if (clCollapsedIndices1.empty()) {53 llvm::errs()54 << "collapsed-indices-2 specified but not collapsed-indices-1";55 signalPassFailure();56 return;57 }58 combinedLoops.push_back(clCollapsedIndices2);59 }60 61 if (combinedLoops.empty()) {62 llvm::errs() << "No collapsed-indices were specified. This pass is only "63 "for testing and does not automatically collapse all "64 "parallel loops or similar.";65 signalPassFailure();66 return;67 }68 69 // Confirm that the specified loops are [0,N) by testing that N values exist70 // with the maximum value being N-1.71 llvm::SmallSet<unsigned, 8> flattenedCombinedLoops;72 unsigned maxCollapsedIndex = 0;73 for (auto &loops : combinedLoops) {74 for (auto &loop : loops) {75 flattenedCombinedLoops.insert(loop);76 maxCollapsedIndex = std::max(maxCollapsedIndex, loop);77 }78 }79 80 if (maxCollapsedIndex != flattenedCombinedLoops.size() - 1 ||81 !flattenedCombinedLoops.contains(maxCollapsedIndex)) {82 llvm::errs()83 << "collapsed-indices arguments must include all values [0,N).";84 signalPassFailure();85 return;86 }87 88 // Only apply the transformation on parallel loops where the specified89 // transformation is valid, but do NOT early abort in the case of invalid90 // loops.91 IRRewriter rewriter(&getContext());92 module->walk([&](scf::ParallelOp op) {93 if (flattenedCombinedLoops.size() != op.getNumLoops()) {94 op.emitOpError("has ")95 << op.getNumLoops()96 << " iter args while this limited functionality testing pass was "97 "configured only for loops with exactly "98 << flattenedCombinedLoops.size() << " iter args.";99 return;100 }101 collapseParallelLoops(rewriter, op, combinedLoops);102 });103 }104};105} // namespace106 107std::unique_ptr<Pass> mlir::createTestSCFParallelLoopCollapsingPass() {108 return std::make_unique<TestSCFParallelLoopCollapsing>();109}110