cca32174fe
For index type of induction variable, the indexing math is better represented using affine ops such as `affine.delinearize_index`. This also further demonstrates that some of these `affine` ops might need to move to a different dialect. For one these ops only support `IndexType` when they should be able to work with any integer type. This change also includes some canonicalization patterns for `affine.delinearize_index` operation to 1) Drop unit `basis` values 2) Remove the `delinearize_index` op when the `linear_index` is a loop induction variable of a normalized loop and the `basis` is of size 1 and is also the upper bound of the normalized loop. --------- Signed-off-by: MaheshRavishankar <mahesh.ravishankar@gmail.com>
112 lines
3.8 KiB
C++
112 lines
3.8 KiB
C++
//===- ParallelLoopCollapsing.cpp - Pass collapsing parallel loop indices -===//
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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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#include "mlir/Dialect/SCF/Transforms/Passes.h"
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#include "mlir/Dialect/Affine/IR/AffineOps.h"
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#include "mlir/Dialect/SCF/IR/SCF.h"
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#include "mlir/Dialect/SCF/Utils/Utils.h"
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#include "mlir/Transforms/RegionUtils.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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namespace mlir {
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#define GEN_PASS_DEF_TESTSCFPARALLELLOOPCOLLAPSING
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#include "mlir/Dialect/SCF/Transforms/Passes.h.inc"
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} // namespace mlir
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#define DEBUG_TYPE "parallel-loop-collapsing"
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using namespace mlir;
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namespace {
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struct TestSCFParallelLoopCollapsing
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: public impl::TestSCFParallelLoopCollapsingBase<
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TestSCFParallelLoopCollapsing> {
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void runOnOperation() override {
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Operation *module = getOperation();
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// The common case for GPU dialect will be simplifying the ParallelOp to 3
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// arguments, so we do that here to simplify things.
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llvm::SmallVector<std::vector<unsigned>, 3> combinedLoops;
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// Gather the input args into the format required by
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// `collapseParallelLoops`.
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if (!clCollapsedIndices0.empty())
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combinedLoops.push_back(clCollapsedIndices0);
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if (!clCollapsedIndices1.empty()) {
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if (clCollapsedIndices0.empty()) {
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llvm::errs()
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<< "collapsed-indices-1 specified but not collapsed-indices-0";
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signalPassFailure();
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return;
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}
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combinedLoops.push_back(clCollapsedIndices1);
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}
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if (!clCollapsedIndices2.empty()) {
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if (clCollapsedIndices1.empty()) {
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llvm::errs()
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<< "collapsed-indices-2 specified but not collapsed-indices-1";
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signalPassFailure();
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return;
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}
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combinedLoops.push_back(clCollapsedIndices2);
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}
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if (combinedLoops.empty()) {
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llvm::errs() << "No collapsed-indices were specified. This pass is only "
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"for testing and does not automatically collapse all "
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"parallel loops or similar.";
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signalPassFailure();
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return;
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}
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// Confirm that the specified loops are [0,N) by testing that N values exist
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// with the maximum value being N-1.
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llvm::SmallSet<unsigned, 8> flattenedCombinedLoops;
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unsigned maxCollapsedIndex = 0;
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for (auto &loops : combinedLoops) {
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for (auto &loop : loops) {
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flattenedCombinedLoops.insert(loop);
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maxCollapsedIndex = std::max(maxCollapsedIndex, loop);
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}
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}
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if (maxCollapsedIndex != flattenedCombinedLoops.size() - 1 ||
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!flattenedCombinedLoops.contains(maxCollapsedIndex)) {
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llvm::errs()
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<< "collapsed-indices arguments must include all values [0,N).";
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signalPassFailure();
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return;
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}
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// Only apply the transformation on parallel loops where the specified
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// transformation is valid, but do NOT early abort in the case of invalid
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// loops.
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IRRewriter rewriter(&getContext());
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module->walk([&](scf::ParallelOp op) {
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if (flattenedCombinedLoops.size() != op.getNumLoops()) {
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op.emitOpError("has ")
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<< op.getNumLoops()
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<< " iter args while this limited functionality testing pass was "
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"configured only for loops with exactly "
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<< flattenedCombinedLoops.size() << " iter args.";
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return;
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}
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collapseParallelLoops(rewriter, op, combinedLoops);
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});
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}
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};
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} // namespace
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std::unique_ptr<Pass> mlir::createTestSCFParallelLoopCollapsingPass() {
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return std::make_unique<TestSCFParallelLoopCollapsing>();
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}
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