aboutsummaryrefslogtreecommitdiff
path: root/lib/StaticAnalyzer/Checkers/ExprInspectionChecker.cpp
blob: f36ec2c687f5b3f3d1d3b8573583c1993a0915f1 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
//==- ExprInspectionChecker.cpp - Used for regression tests ------*- C++ -*-==//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "llvm/ADT/StringSwitch.h"

using namespace clang;
using namespace ento;

namespace {
class ExprInspectionChecker : public Checker< eval::Call > {
  mutable std::unique_ptr<BugType> BT;

  void analyzerEval(const CallExpr *CE, CheckerContext &C) const;
  void analyzerCheckInlined(const CallExpr *CE, CheckerContext &C) const;
  void analyzerWarnIfReached(const CallExpr *CE, CheckerContext &C) const;
  void analyzerCrash(const CallExpr *CE, CheckerContext &C) const;

  typedef void (ExprInspectionChecker::*FnCheck)(const CallExpr *,
                                                 CheckerContext &C) const;

public:
  bool evalCall(const CallExpr *CE, CheckerContext &C) const;
};
}

bool ExprInspectionChecker::evalCall(const CallExpr *CE,
                                     CheckerContext &C) const {
  // These checks should have no effect on the surrounding environment
  // (globals should not be invalidated, etc), hence the use of evalCall.
  FnCheck Handler = llvm::StringSwitch<FnCheck>(C.getCalleeName(CE))
    .Case("clang_analyzer_eval", &ExprInspectionChecker::analyzerEval)
    .Case("clang_analyzer_checkInlined",
          &ExprInspectionChecker::analyzerCheckInlined)
    .Case("clang_analyzer_crash", &ExprInspectionChecker::analyzerCrash)
    .Case("clang_analyzer_warnIfReached", &ExprInspectionChecker::analyzerWarnIfReached)
    .Default(nullptr);

  if (!Handler)
    return false;

  (this->*Handler)(CE, C);
  return true;
}

static const char *getArgumentValueString(const CallExpr *CE,
                                          CheckerContext &C) {
  if (CE->getNumArgs() == 0)
    return "Missing assertion argument";

  ExplodedNode *N = C.getPredecessor();
  const LocationContext *LC = N->getLocationContext();
  ProgramStateRef State = N->getState();

  const Expr *Assertion = CE->getArg(0);
  SVal AssertionVal = State->getSVal(Assertion, LC);

  if (AssertionVal.isUndef())
    return "UNDEFINED";

  ProgramStateRef StTrue, StFalse;
  std::tie(StTrue, StFalse) =
    State->assume(AssertionVal.castAs<DefinedOrUnknownSVal>());

  if (StTrue) {
    if (StFalse)
      return "UNKNOWN";
    else
      return "TRUE";
  } else {
    if (StFalse)
      return "FALSE";
    else
      llvm_unreachable("Invalid constraint; neither true or false.");
  }
}

void ExprInspectionChecker::analyzerEval(const CallExpr *CE,
                                         CheckerContext &C) const {
  ExplodedNode *N = C.getPredecessor();
  const LocationContext *LC = N->getLocationContext();

  // A specific instantiation of an inlined function may have more constrained
  // values than can generally be assumed. Skip the check.
  if (LC->getCurrentStackFrame()->getParent() != nullptr)
    return;

  if (!BT)
    BT.reset(new BugType(this, "Checking analyzer assumptions", "debug"));

  BugReport *R = new BugReport(*BT, getArgumentValueString(CE, C), N);
  C.emitReport(R);
}

void ExprInspectionChecker::analyzerWarnIfReached(const CallExpr *CE,
                                                  CheckerContext &C) const {
  ExplodedNode *N = C.getPredecessor();

  if (!BT)
    BT.reset(new BugType(this, "Checking analyzer assumptions", "debug"));

  BugReport *R = new BugReport(*BT, "REACHABLE", N);
  C.emitReport(R);
}

void ExprInspectionChecker::analyzerCheckInlined(const CallExpr *CE,
                                                 CheckerContext &C) const {
  ExplodedNode *N = C.getPredecessor();
  const LocationContext *LC = N->getLocationContext();

  // An inlined function could conceivably also be analyzed as a top-level
  // function. We ignore this case and only emit a message (TRUE or FALSE)
  // when we are analyzing it as an inlined function. This means that
  // clang_analyzer_checkInlined(true) should always print TRUE, but
  // clang_analyzer_checkInlined(false) should never actually print anything.
  if (LC->getCurrentStackFrame()->getParent() == nullptr)
    return;

  if (!BT)
    BT.reset(new BugType(this, "Checking analyzer assumptions", "debug"));

  BugReport *R = new BugReport(*BT, getArgumentValueString(CE, C), N);
  C.emitReport(R);
}

void ExprInspectionChecker::analyzerCrash(const CallExpr *CE,
                                          CheckerContext &C) const {
  LLVM_BUILTIN_TRAP;
}

void ento::registerExprInspectionChecker(CheckerManager &Mgr) {
  Mgr.registerChecker<ExprInspectionChecker>();
}