| //===- MemRefDependenceCheck.cpp - MemRef DependenceCheck Class -*- C++ -*-===// |
| // |
| // Copyright 2019 The MLIR Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // ============================================================================= |
| // |
| // This file implements a pass to run pair-wise memref access dependence checks. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "mlir/Analysis/AffineAnalysis.h" |
| #include "mlir/Analysis/AffineStructures.h" |
| #include "mlir/Analysis/Passes.h" |
| #include "mlir/IR/Builders.h" |
| #include "mlir/IR/BuiltinOps.h" |
| #include "mlir/IR/StmtVisitor.h" |
| #include "mlir/Pass.h" |
| #include "mlir/StandardOps/StandardOps.h" |
| #include "llvm/Support/Debug.h" |
| |
| #define DEBUG_TYPE "memref-dependence-check" |
| |
| using namespace mlir; |
| |
| namespace { |
| |
| // TODO(andydavis) Add common surrounding loop depth-wise dependence checks. |
| /// Checks dependences between all pairs of memref accesses in an MLFunction. |
| struct MemRefDependenceCheck : public FunctionPass, |
| StmtWalker<MemRefDependenceCheck> { |
| SmallVector<OperationStmt *, 4> loadsAndStores; |
| explicit MemRefDependenceCheck() {} |
| |
| PassResult runOnMLFunction(MLFunction *f) override; |
| // Not applicable to CFG functions. |
| PassResult runOnCFGFunction(CFGFunction *f) override { return success(); } |
| |
| void visitOperationStmt(OperationStmt *opStmt) { |
| if (opStmt->isa<LoadOp>() || opStmt->isa<StoreOp>()) { |
| loadsAndStores.push_back(opStmt); |
| } |
| } |
| static char passID; |
| }; |
| |
| } // end anonymous namespace |
| |
| char MemRefDependenceCheck::passID = 0; |
| |
| FunctionPass *mlir::createMemRefDependenceCheckPass() { |
| return new MemRefDependenceCheck(); |
| } |
| |
| // Adds memref access indices 'opIndices' from 'memrefType' to 'access'. |
| static void addMemRefAccessIndices( |
| llvm::iterator_range<Operation::const_operand_iterator> opIndices, |
| MemRefType memrefType, MemRefAccess *access) { |
| access->indices.reserve(memrefType.getRank()); |
| for (auto *index : opIndices) { |
| access->indices.push_back(cast<MLValue>(const_cast<SSAValue *>(index))); |
| } |
| } |
| |
| // Populates 'access' with memref, indices and opstmt from 'loadOrStoreOpStmt'. |
| static void getMemRefAccess(const OperationStmt *loadOrStoreOpStmt, |
| MemRefAccess *access) { |
| access->opStmt = loadOrStoreOpStmt; |
| if (auto loadOp = loadOrStoreOpStmt->dyn_cast<LoadOp>()) { |
| access->memref = cast<MLValue>(loadOp->getMemRef()); |
| addMemRefAccessIndices(loadOp->getIndices(), loadOp->getMemRefType(), |
| access); |
| } else { |
| assert(loadOrStoreOpStmt->isa<StoreOp>()); |
| auto storeOp = loadOrStoreOpStmt->dyn_cast<StoreOp>(); |
| access->memref = cast<MLValue>(storeOp->getMemRef()); |
| addMemRefAccessIndices(storeOp->getIndices(), storeOp->getMemRefType(), |
| access); |
| } |
| } |
| |
| // For each access in 'loadsAndStores', runs a depence check between this |
| // "source" access and all subsequent "destination" accesses in |
| // 'loadsAndStores'. Emits the result of the dependence check as a note with |
| // the source access. |
| // TODO(andydavis) Clarify expected-note logs. In particular we may want to |
| // drop the 'i' from the note string, tag dependence destination accesses |
| // with a note with their 'j' index. In addition, we may want a schedme that |
| // first assigned unique ids to each access, then emits a note for each access |
| // with its id, and emits a note for each dependence check with a pair of ids. |
| // For example, given this code: |
| // |
| // memref_access0 |
| // // emit note: "this op is memref access 0' |
| // // emit note: "dependence from memref access 0 to access 1 = false" |
| // // emit note: "dependence from memref access 0 to access 2 = true" |
| // memref_access1 |
| // // emit note: "this op is memref access 1' |
| // // emit note: "dependence from memref access 1 to access 2 = false" |
| // memref_access2 |
| // // emit note: "this op is memref access 2' |
| // |
| static void checkDependences(ArrayRef<OperationStmt *> loadsAndStores) { |
| for (unsigned i = 0, e = loadsAndStores.size(); i < e; ++i) { |
| auto *srcOpStmt = loadsAndStores[i]; |
| MemRefAccess srcAccess; |
| getMemRefAccess(srcOpStmt, &srcAccess); |
| for (unsigned j = i + 1; j < e; ++j) { |
| auto *dstOpStmt = loadsAndStores[j]; |
| MemRefAccess dstAccess; |
| getMemRefAccess(dstOpStmt, &dstAccess); |
| bool ret = checkMemrefAccessDependence(srcAccess, dstAccess); |
| srcOpStmt->emitNote("dependence from memref access " + Twine(i) + |
| " to access " + Twine(j) + " = " + |
| (ret ? "true" : "false")); |
| } |
| } |
| } |
| |
| // Walks the MLFunction 'f' adding load and store ops to 'loadsAndStores'. |
| // Runs pair-wise dependence checks. |
| PassResult MemRefDependenceCheck::runOnMLFunction(MLFunction *f) { |
| loadsAndStores.clear(); |
| walk(f); |
| checkDependences(loadsAndStores); |
| return success(); |
| } |
| |
| static PassRegistration<MemRefDependenceCheck> |
| pass("memref-dependence-check", |
| "Checks dependences between all pairs of memref accesses."); |