================ @@ -0,0 +1,625 @@ +//===-- NullPointerAnalysisModel.cpp ----------------------------*- C++ -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file defines a generic null-pointer analysis model, used for finding +// pointer null-checks after the pointer has already been dereferenced. +// +// Only a limited set of operations are currently recognized. Notably, pointer +// arithmetic, null-pointer assignments and _nullable/_nonnull attributes are +// missing as of yet. +// +//===----------------------------------------------------------------------===// + +#include "clang/Analysis/FlowSensitive/Models/NullPointerAnalysisModel.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/Decl.h" +#include "clang/AST/Expr.h" +#include "clang/AST/Stmt.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" +#include "clang/ASTMatchers/ASTMatchers.h" +#include "clang/Analysis/CFG.h" +#include "clang/Analysis/FlowSensitive/CFGMatchSwitch.h" +#include "clang/Analysis/FlowSensitive/DataflowAnalysis.h" +#include "clang/Analysis/FlowSensitive/DataflowEnvironment.h" +#include "clang/Analysis/FlowSensitive/DataflowLattice.h" +#include "clang/Analysis/FlowSensitive/MapLattice.h" +#include "clang/Analysis/FlowSensitive/NoopLattice.h" +#include "llvm/ADT/StringRef.h" +#include "llvm/ADT/Twine.h" + +namespace clang::dataflow { + +namespace { +using namespace ast_matchers; + +constexpr char kCond[] = "condition"; +constexpr char kVar[] = "var"; +constexpr char kValue[] = "value"; +constexpr char kIsNonnull[] = "is-nonnull"; +constexpr char kIsNull[] = "is-null"; + +enum class SatisfiabilityResult { + // Returned when the value was not initialized yet. + Nullptr, + // Special value that signals that the boolean value can be anything. + // It signals that the underlying formulas are too complex to be calculated + // efficiently. + Top, + // Equivalent to the literal True in the current environment. + True, + // Equivalent to the literal False in the current environment. + False, + // Both True and False values could be produced with an appropriate set of + // conditions. + Unknown +}; + +using SR = SatisfiabilityResult; + +// FIXME: These AST matchers should also be exported via the +// NullPointerAnalysisModel class, for tests +auto ptrToVar(llvm::StringRef VarName = kVar) { + return traverse(TK_IgnoreUnlessSpelledInSource, ---------------- Discookie wrote:
Apparently `TK_IgnoreUnlessSpelledInSource` is still required here. While getting `Value`s out of the framework is propagated correctly, *setting* values is not. When setting a new `Value`, only the outermost `Expr` will have that value set, which is not guaranteed to be a glvalue even if the underlying value is, and could be overwritten by the propagation done by `Transfer.cpp`. To set a value directly, we still need to bind to the root `Expr` in this case. This traversal has weird behavior with `nullptr` and some other casts - on `nullptr` we need to match the `NullToPointer` cast, and not the nullptr directly, and explicit casts also have the chance to not bind correctly to the root pointer. I'm not sure if there's a better way to bind to the "root" `Expr` that I haven't found yet, but the current solution has too many dragons. (Maybe this is also a case of X/Y problem, where if I assign atoms as `IsNull/IsNonnull` instead of formulas, I wouldn't need to re-assign `Value`s...) https://github.com/llvm/llvm-project/pull/84166 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
