ExprInspectionChecker.cpp revision 651f13cea278ec967336033dd032faef0e9fc2ec 
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/BugReporter/BugType.h"
12#include "clang/StaticAnalyzer/Core/Checker.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 std::unique_ptr<BugType> BT;
22
23  void analyzerEval(const CallExpr *CE, CheckerContext &C) const;
24  void analyzerCheckInlined(const CallExpr *CE, CheckerContext &C) const;
25  void analyzerWarnIfReached(const CallExpr *CE, CheckerContext &C) const;
26  void analyzerCrash(const CallExpr *CE, CheckerContext &C) const;
27
28  typedef void (ExprInspectionChecker::*FnCheck)(const CallExpr *,
29                                                 CheckerContext &C) const;
30
31public:
32  bool evalCall(const CallExpr *CE, CheckerContext &C) const;
33};
34}
35
36bool ExprInspectionChecker::evalCall(const CallExpr *CE,
37                                     CheckerContext &C) const {
38  // These checks should have no effect on the surrounding environment
39  // (globals should not be invalidated, etc), hence the use of evalCall.
40  FnCheck Handler = llvm::StringSwitch<FnCheck>(C.getCalleeName(CE))
41    .Case("clang_analyzer_eval", &ExprInspectionChecker::analyzerEval)
42    .Case("clang_analyzer_checkInlined",
43          &ExprInspectionChecker::analyzerCheckInlined)
44    .Case("clang_analyzer_crash", &ExprInspectionChecker::analyzerCrash)
45    .Case("clang_analyzer_warnIfReached", &ExprInspectionChecker::analyzerWarnIfReached)
46    .Default(0);
47
48  if (!Handler)
49    return false;
50
51  (this->*Handler)(CE, C);
52  return true;
53}
54
55static const char *getArgumentValueString(const CallExpr *CE,
56                                          CheckerContext &C) {
57  if (CE->getNumArgs() == 0)
58    return "Missing assertion argument";
59
60  ExplodedNode *N = C.getPredecessor();
61  const LocationContext *LC = N->getLocationContext();
62  ProgramStateRef State = N->getState();
63
64  const Expr *Assertion = CE->getArg(0);
65  SVal AssertionVal = State->getSVal(Assertion, LC);
66
67  if (AssertionVal.isUndef())
68    return "UNDEFINED";
69
70  ProgramStateRef StTrue, StFalse;
71  std::tie(StTrue, StFalse) =
72    State->assume(AssertionVal.castAs<DefinedOrUnknownSVal>());
73
74  if (StTrue) {
75    if (StFalse)
76      return "UNKNOWN";
77    else
78      return "TRUE";
79  } else {
80    if (StFalse)
81      return "FALSE";
82    else
83      llvm_unreachable("Invalid constraint; neither true or false.");
84  }
85}
86
87void ExprInspectionChecker::analyzerEval(const CallExpr *CE,
88                                         CheckerContext &C) const {
89  ExplodedNode *N = C.getPredecessor();
90  const LocationContext *LC = N->getLocationContext();
91
92  // A specific instantiation of an inlined function may have more constrained
93  // values than can generally be assumed. Skip the check.
94  if (LC->getCurrentStackFrame()->getParent() != 0)
95    return;
96
97  if (!BT)
98    BT.reset(new BugType(this, "Checking analyzer assumptions", "debug"));
99
100  BugReport *R = new BugReport(*BT, getArgumentValueString(CE, C), N);
101  C.emitReport(R);
102}
103
104void ExprInspectionChecker::analyzerWarnIfReached(const CallExpr *CE,
105                                                  CheckerContext &C) const {
106  ExplodedNode *N = C.getPredecessor();
107
108  if (!BT)
109    BT.reset(new BugType(this, "Checking analyzer assumptions", "debug"));
110
111  BugReport *R = new BugReport(*BT, "REACHABLE", N);
112  C.emitReport(R);
113}
114
115void ExprInspectionChecker::analyzerCheckInlined(const CallExpr *CE,
116                                                 CheckerContext &C) const {
117  ExplodedNode *N = C.getPredecessor();
118  const LocationContext *LC = N->getLocationContext();
119
120  // An inlined function could conceivably also be analyzed as a top-level
121  // function. We ignore this case and only emit a message (TRUE or FALSE)
122  // when we are analyzing it as an inlined function. This means that
123  // clang_analyzer_checkInlined(true) should always print TRUE, but
124  // clang_analyzer_checkInlined(false) should never actually print anything.
125  if (LC->getCurrentStackFrame()->getParent() == 0)
126    return;
127
128  if (!BT)
129    BT.reset(new BugType(this, "Checking analyzer assumptions", "debug"));
130
131  BugReport *R = new BugReport(*BT, getArgumentValueString(CE, C), N);
132  C.emitReport(R);
133}
134
135void ExprInspectionChecker::analyzerCrash(const CallExpr *CE,
136                                          CheckerContext &C) const {
137  LLVM_BUILTIN_TRAP;
138}
139
140void ento::registerExprInspectionChecker(CheckerManager &Mgr) {
141  Mgr.registerChecker<ExprInspectionChecker>();
142}
143
144