126 lines
4.7 KiB
C++
126 lines
4.7 KiB
C++
//===- TestMemRefDependenceCheck.cpp - Test dep analysis ------------------===//
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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 file implements a pass to run pair-wise memref access dependence checks.
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//
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//===----------------------------------------------------------------------===//
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#include "mlir/Dialect/Affine/Analysis/AffineAnalysis.h"
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#include "mlir/Dialect/Affine/Analysis/AffineStructures.h"
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#include "mlir/Dialect/Affine/Analysis/Utils.h"
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#include "mlir/Dialect/Affine/IR/AffineOps.h"
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#include "mlir/IR/Builders.h"
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#include "mlir/Pass/Pass.h"
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#include "llvm/Support/Debug.h"
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#define DEBUG_TYPE "test-memref-dependence-check"
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using namespace mlir;
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namespace {
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// TODO: Add common surrounding loop depth-wise dependence checks.
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/// Checks dependences between all pairs of memref accesses in a Function.
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struct TestMemRefDependenceCheck
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: public PassWrapper<TestMemRefDependenceCheck, OperationPass<>> {
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MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(TestMemRefDependenceCheck)
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StringRef getArgument() const final { return "test-memref-dependence-check"; }
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StringRef getDescription() const final {
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return "Checks dependences between all pairs of memref accesses.";
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}
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SmallVector<Operation *, 4> loadsAndStores;
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void runOnOperation() override;
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};
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} // namespace
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// Returns a result string which represents the direction vector (if there was
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// a dependence), returns the string "false" otherwise.
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static std::string
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getDirectionVectorStr(bool ret, unsigned numCommonLoops, unsigned loopNestDepth,
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ArrayRef<DependenceComponent> dependenceComponents) {
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if (!ret)
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return "false";
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if (dependenceComponents.empty() || loopNestDepth > numCommonLoops)
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return "true";
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std::string result;
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for (const auto &dependenceComponent : dependenceComponents) {
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std::string lbStr = "-inf";
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if (dependenceComponent.lb.has_value() &&
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dependenceComponent.lb.value() != std::numeric_limits<int64_t>::min())
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lbStr = std::to_string(dependenceComponent.lb.value());
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std::string ubStr = "+inf";
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if (dependenceComponent.ub.has_value() &&
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dependenceComponent.ub.value() != std::numeric_limits<int64_t>::max())
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ubStr = std::to_string(dependenceComponent.ub.value());
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result += "[" + lbStr + ", " + ubStr + "]";
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}
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return result;
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}
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// For each access in 'loadsAndStores', runs a dependence check between this
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// "source" access and all subsequent "destination" accesses in
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// 'loadsAndStores'. Emits the result of the dependence check as a note with
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// the source access.
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static void checkDependences(ArrayRef<Operation *> loadsAndStores) {
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for (unsigned i = 0, e = loadsAndStores.size(); i < e; ++i) {
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auto *srcOpInst = loadsAndStores[i];
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MemRefAccess srcAccess(srcOpInst);
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for (unsigned j = 0; j < e; ++j) {
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auto *dstOpInst = loadsAndStores[j];
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MemRefAccess dstAccess(dstOpInst);
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unsigned numCommonLoops =
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getNumCommonSurroundingLoops(*srcOpInst, *dstOpInst);
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for (unsigned d = 1; d <= numCommonLoops + 1; ++d) {
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FlatAffineValueConstraints dependenceConstraints;
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SmallVector<DependenceComponent, 2> dependenceComponents;
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DependenceResult result = checkMemrefAccessDependence(
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srcAccess, dstAccess, d, &dependenceConstraints,
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&dependenceComponents);
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if (result.value == DependenceResult::Failure) {
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srcOpInst->emitError("dependence check failed");
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} else {
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bool ret = hasDependence(result);
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// TODO: Print dependence type (i.e. RAW, etc) and print
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// distance vectors as: ([2, 3], [0, 10]). Also, shorten distance
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// vectors from ([1, 1], [3, 3]) to (1, 3).
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srcOpInst->emitRemark("dependence from ")
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<< i << " to " << j << " at depth " << d << " = "
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<< getDirectionVectorStr(ret, numCommonLoops, d,
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dependenceComponents);
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}
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}
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}
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}
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}
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/// Walks the operation adding load and store ops to 'loadsAndStores'. Runs
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/// pair-wise dependence checks.
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void TestMemRefDependenceCheck::runOnOperation() {
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// Collect the loads and stores within the function.
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loadsAndStores.clear();
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getOperation()->walk([&](Operation *op) {
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if (isa<AffineLoadOp, AffineStoreOp>(op))
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loadsAndStores.push_back(op);
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});
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checkDependences(loadsAndStores);
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}
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namespace mlir {
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namespace test {
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void registerTestMemRefDependenceCheck() {
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PassRegistration<TestMemRefDependenceCheck>();
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}
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} // namespace test
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} // namespace mlir
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