ExprInspectionChecker.cpp revision 9852f58f50b4fc20914fbce5b4454135a42343f4 
1//==- ExprInspectionChecker.cpp - Used for regression tests ------*- C++ -*-==//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "ClangSACheckers.h"
11#include "clang/StaticAnalyzer/Core/Checker.h"
12#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
13#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
14#include "llvm/ADT/StringSwitch.h"
15
16using namespace clang;
17using namespace ento;
18
19namespace {
20class ExprInspectionChecker : public Checker< eval::Call > {
21  mutable OwningPtr<BugType> BT;
22
23  void analyzerEval(const CallExpr *CE, CheckerContext &C) const;
24  void analyzerCheckInlined(const CallExpr *CE, CheckerContext &C) const;
25
26  typedef void (ExprInspectionChecker::*FnCheck)(const CallExpr *,
27                                                 CheckerContext &C) const;
28
29public:
30  bool evalCall(const CallExpr *CE, CheckerContext &C) const;
31};
32}
33
34bool ExprInspectionChecker::evalCall(const CallExpr *CE,
35                                     CheckerContext &C) const {
36  // These checks should have no effect on the surrounding environment
37  // (globals should not be invalidated, etc), hence the use of evalCall.
38  FnCheck Handler = llvm::StringSwitch<FnCheck>(C.getCalleeName(CE))
39    .Case("clang_analyzer_eval", &ExprInspectionChecker::analyzerEval)
40    .Case("clang_analyzer_checkInlined",
41          &ExprInspectionChecker::analyzerCheckInlined)
42    .Default(0);
43
44  if (!Handler)
45    return false;
46
47  (this->*Handler)(CE, C);
48  return true;
49}
50
51static const char *getArgumentValueString(const CallExpr *CE,
52                                          CheckerContext &C) {
53  if (CE->getNumArgs() == 0)
54    return "Missing assertion argument";
55
56  ExplodedNode *N = C.getPredecessor();
57  const LocationContext *LC = N->getLocationContext();
58  ProgramStateRef State = N->getState();
59
60  const Expr *Assertion = CE->getArg(0);
61  SVal AssertionVal = State->getSVal(Assertion, LC);
62
63  if (AssertionVal.isUndef())
64    return "UNDEFINED";
65
66  ProgramStateRef StTrue, StFalse;
67  llvm::tie(StTrue, StFalse) =
68    State->assume(cast<DefinedOrUnknownSVal>(AssertionVal));
69
70  if (StTrue) {
71    if (StFalse)
72      return "UNKNOWN";
73    else
74      return "TRUE";
75  } else {
76    if (StFalse)
77      return "FALSE";
78    else
79      llvm_unreachable("Invalid constraint; neither true or false.");
80  }
81}
82
83void ExprInspectionChecker::analyzerEval(const CallExpr *CE,
84                                         CheckerContext &C) const {
85  ExplodedNode *N = C.getPredecessor();
86  const LocationContext *LC = N->getLocationContext();
87
88  // A specific instantiation of an inlined function may have more constrained
89  // values than can generally be assumed. Skip the check.
90  if (LC->getCurrentStackFrame()->getParent() != 0)
91    return;
92
93  if (!BT)
94    BT.reset(new BugType("Checking analyzer assumptions", "debug"));
95
96  BugReport *R = new BugReport(*BT, getArgumentValueString(CE, C), N);
97  C.emitReport(R);
98}
99
100void ExprInspectionChecker::analyzerCheckInlined(const CallExpr *CE,
101                                                 CheckerContext &C) const {
102  ExplodedNode *N = C.getPredecessor();
103  const LocationContext *LC = N->getLocationContext();
104
105  // An inlined function could conceivably also be analyzed as a top-level
106  // function. We ignore this case and only emit a message (TRUE or FALSE)
107  // when we are analyzing it as an inlined function. This means that
108  // clang_analyzer_checkInlined(true) should always print TRUE, but
109  // clang_analyzer_checkInlined(false) should never actually print anything.
110  if (LC->getCurrentStackFrame()->getParent() == 0)
111    return;
112
113  if (!BT)
114    BT.reset(new BugType("Checking analyzer assumptions", "debug"));
115
116  BugReport *R = new BugReport(*BT, getArgumentValueString(CE, C), N);
117  C.emitReport(R);
118}
119
120void ento::registerExprInspectionChecker(CheckerManager &Mgr) {
121  Mgr.registerChecker<ExprInspectionChecker>();
122}
123
124