e39bd407ba
The analyzer trims unnecessary nodes from the exploded graph before reporting path diagnostics. However, in some cases it can trim all nodes (including the error node), leading to an assertion failure (see https://llvm.org/bugs/show_bug.cgi?id=24184). This commit addresses the issue by adding two new APIs to CheckerContext to explicitly create error nodes. Unless the client provides a custom tag, these APIs tag the node with the checker's tag -- preventing it from being trimmed. The generateErrorNode() method creates a sink error node, while generateNonFatalErrorNode() creates an error node for a path that should continue being explored. The intent is that one of these two methods should be used whenever a checker creates an error node. This commit updates the checkers to use these APIs. These APIs (unlike addTransition() and generateSink()) do not take an explicit Pred node. This is because there are not any error nodes in the checkers that were created with an explicit different than the default (the CheckerContext's Pred node). It also changes generateSink() to require state and pred nodes (previously these were optional) to reduce confusion. Additionally, there were several cases where checkers did check whether a generated node could be null; we now explicitly check for null in these places. This commit also includes a test case written by Ying Yi as part of http://reviews.llvm.org/D12163 (that patch originally addressed this issue but was reverted because it introduced false positive regressions). Differential Revision: http://reviews.llvm.org/D12780 llvm-svn: 247859
102 lines
3.2 KiB
C++
102 lines
3.2 KiB
C++
//=== UndefResultChecker.cpp ------------------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This defines UndefResultChecker, a builtin check in ExprEngine that
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// performs checks for undefined results of non-assignment binary operators.
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//
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//===----------------------------------------------------------------------===//
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#include "ClangSACheckers.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/CheckerManager.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace clang;
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using namespace ento;
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namespace {
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class UndefResultChecker
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: public Checker< check::PostStmt<BinaryOperator> > {
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mutable std::unique_ptr<BugType> BT;
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public:
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void checkPostStmt(const BinaryOperator *B, CheckerContext &C) const;
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};
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} // end anonymous namespace
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void UndefResultChecker::checkPostStmt(const BinaryOperator *B,
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CheckerContext &C) const {
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ProgramStateRef state = C.getState();
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const LocationContext *LCtx = C.getLocationContext();
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if (state->getSVal(B, LCtx).isUndef()) {
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// Do not report assignments of uninitialized values inside swap functions.
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// This should allow to swap partially uninitialized structs
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// (radar://14129997)
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if (const FunctionDecl *EnclosingFunctionDecl =
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dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl()))
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if (C.getCalleeName(EnclosingFunctionDecl) == "swap")
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return;
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// Generate an error node.
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ExplodedNode *N = C.generateErrorNode();
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if (!N)
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return;
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if (!BT)
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BT.reset(
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new BuiltinBug(this, "Result of operation is garbage or undefined"));
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SmallString<256> sbuf;
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llvm::raw_svector_ostream OS(sbuf);
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const Expr *Ex = nullptr;
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bool isLeft = true;
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if (state->getSVal(B->getLHS(), LCtx).isUndef()) {
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Ex = B->getLHS()->IgnoreParenCasts();
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isLeft = true;
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}
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else if (state->getSVal(B->getRHS(), LCtx).isUndef()) {
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Ex = B->getRHS()->IgnoreParenCasts();
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isLeft = false;
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}
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if (Ex) {
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OS << "The " << (isLeft ? "left" : "right")
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<< " operand of '"
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<< BinaryOperator::getOpcodeStr(B->getOpcode())
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<< "' is a garbage value";
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}
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else {
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// Neither operand was undefined, but the result is undefined.
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OS << "The result of the '"
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<< BinaryOperator::getOpcodeStr(B->getOpcode())
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<< "' expression is undefined";
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}
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auto report = llvm::make_unique<BugReport>(*BT, OS.str(), N);
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if (Ex) {
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report->addRange(Ex->getSourceRange());
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bugreporter::trackNullOrUndefValue(N, Ex, *report);
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}
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else
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bugreporter::trackNullOrUndefValue(N, B, *report);
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C.emitReport(std::move(report));
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}
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}
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void ento::registerUndefResultChecker(CheckerManager &mgr) {
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mgr.registerChecker<UndefResultChecker>();
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}
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