| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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. |
| */ |
| |
| /*! |
| * Out of bounds array access static analyzer. |
| */ |
| |
| #include <tvm/tir/transform.h> |
| |
| #include "../../arith/ir_visitor_with_analyzer.h" |
| #include "../../printer/text_printer.h" |
| #include "../schedule/error.h" |
| |
| namespace tvm { |
| namespace tir { |
| namespace transform { |
| struct OOBLocation { |
| Buffer buf; |
| size_t dimension; |
| ObjectRef index; |
| arith::IntSet index_bounds; |
| arith::IntSet shape_bounds; |
| }; |
| |
| class OOBError : public ScheduleError { |
| public: |
| OOBError(IRModule mod, std::vector<OOBLocation> locations) : mod_(mod), locations_(locations) {} |
| String FastErrorString() const final { return "Out of bound memory access"; } |
| |
| String DetailRenderTemplate() const final { |
| std::stringstream s; |
| for (const auto& oob : locations_) { |
| s << "Out of bounds memory access on buffer " << oob.buf->name << " dimension " |
| << oob.dimension << "."; |
| s << " index " << oob.index << " with bounds [" << oob.index_bounds.min() << ", " |
| << oob.index_bounds.max() << "] is outside the range [0, " << oob.shape_bounds.min() |
| << "]."; |
| s << "\n"; |
| } |
| return s.str(); |
| } |
| IRModule mod() const final { return mod_; } |
| Array<ObjectRef> LocationsOfInterest() const final { |
| std::vector<ObjectRef> locs; |
| for (auto loc : locations_) { |
| locs.push_back(loc.index); |
| } |
| return locs; |
| } |
| |
| private: |
| IRModule mod_; |
| std::vector<OOBLocation> locations_; |
| }; |
| class OOBCheckerVisitor final : public arith::IRVisitorWithAnalyzer { |
| using IRVisitorWithAnalyzer::VisitExpr_; |
| using IRVisitorWithAnalyzer::VisitStmt_; |
| |
| public: |
| void VisitStmt_(const BufferStoreNode* node) final { |
| for (size_t i = 0; i < node->buffer->shape.size(); i++) { |
| CheckBounds(node, i); |
| } |
| IRVisitorWithAnalyzer::VisitStmt_(node); |
| } |
| void VisitExpr_(const BufferLoadNode* node) final { |
| for (size_t i = 0; i < node->buffer->shape.size(); i++) { |
| CheckBounds(node, i); |
| } |
| IRVisitorWithAnalyzer::VisitExpr_(node); |
| } |
| |
| template <class T> |
| void CheckBounds(const T* node, size_t i) { |
| auto ind_bounds = analyzer_.int_set(node->indices[i]); |
| auto shape_bounds = analyzer_.int_set(node->buffer->shape[i]); |
| // We would expect that |
| // `analyzer_.CanProve(node->indices[i] < 0 || node->indices[i] >= node->buffer->shape[i])` |
| // would be the way to check if any out of bounds access occurs here, but `CanProve` checks if |
| // the statement is true for all possible values (universal quantification). For a mix of in |
| // bounds and out of bounds access, no out of bounds access would be reported. We instead want |
| // to check if there is any value for which the access is out of bounds (existential |
| // quantification). |
| // An solution would be to check that the index is in bounds for every possible value. This |
| // has the problem that some valid access patterns maybe be valid but not provably valid. We |
| // prefer that this analysis is conservative and only shows errors that are provable. This leads |
| // us to the following check: are the bounds of the index outside the bounds of the shape. |
| if (analyzer_.CanProve(ind_bounds.max() >= shape_bounds.min()) || |
| analyzer_.CanProve(ind_bounds.min() < 0)) { |
| errors.push_back({node->buffer, i, node->indices[i], ind_bounds, shape_bounds}); |
| } |
| } |
| |
| std::vector<OOBLocation> errors; |
| }; |
| |
| transform::Pass OOBChecker() { |
| auto pass_func = [=](tir::PrimFunc func, IRModule mod, transform::PassContext ctx) { |
| OOBCheckerVisitor checker; |
| checker(func->body); |
| if (checker.errors.size() > 0) { |
| // mod doesn't contain our function, so we construct a new mod with out function |
| IRModule func_mod({{GlobalVar("main"), func}}); |
| LOG(FATAL) << OOBError(func_mod, checker.errors).RenderReport("Out of bounds checker"); |
| } |
| return func; |
| }; |
| return transform::CreatePrimFuncPass(pass_func, 0, "tir.analysis.OOBChecker", {}); |
| } |
| |
| TVM_REGISTER_GLOBAL("tir.analysis.OOBChecker").set_body_typed(OOBChecker); |
| } // namespace transform |
| } // namespace tir |
| } // namespace tvm |