clang/unittests/StaticAnalyzer/SValSimplifyerTest.cpp

   1 //===- unittests/StaticAnalyzer/SValSimplifyerTest.cpp --------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "CheckerRegistration.h"
  10 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
  11 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
  12 #include "clang/StaticAnalyzer/Core/Checker.h"
  13 #include "clang/StaticAnalyzer/Core/PathSensitive/CallDescription.h"
  14 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
  15 #include "clang/StaticAnalyzer/Frontend/AnalysisConsumer.h"
  16 #include "clang/StaticAnalyzer/Frontend/CheckerRegistry.h"
  17 #include "llvm/ADT/Twine.h"
  18 #include "llvm/Support/raw_ostream.h"
  19 #include "gtest/gtest.h"
  20
  21 using namespace clang;
  22 using namespace ento;
  23
  24 static std::string toString(SVal V) {
  25   std::string Result;
  26   llvm::raw_string_ostream Stream(Result);
  27   V.dumpToStream(Stream);
  28   return Result;
  29 }
  30
  31 static void replace(std::string &Content, StringRef Substr,
  32                     StringRef Replacement) {
  33   std::size_t Pos = 0;
  34   while ((Pos = Content.find(Substr, Pos)) != std::string::npos) {
  35     Content.replace(Pos, Substr.size(), Replacement);
  36     Pos += Replacement.size();
  37   }
  38 }
  39
  40 namespace {
  41
  42 class SimplifyChecker : public Checker<check::PreCall> {
  43   const BugType Bug{this, "SimplifyChecker"};
  44   const CallDescription SimplifyCall{CDM::SimpleFunc, {"simplify"}, 1};
  45
  46   void report(CheckerContext &C, const Expr *E, StringRef Description) const {
  47     PathDiagnosticLocation Loc(E->getExprLoc(), C.getSourceManager());
  48     auto Report = std::make_unique<BasicBugReport>(Bug, Description, Loc);
  49     C.emitReport(std::move(Report));
  50   }
  51
  52 public:
  53   void checkPreCall(const CallEvent &Call, CheckerContext &C) const {
  54     if (!SimplifyCall.matches(Call))
  55       return;
  56     const Expr *Arg = Call.getArgExpr(0);
  57     SVal Val = C.getSVal(Arg);
  58     SVal SimplifiedVal = C.getSValBuilder().simplifySVal(C.getState(), Val);
  59     std::string Subject = toString(Val);
  60     std::string Simplified = toString(SimplifiedVal);
  61     std::string Message = (llvm::Twine{Subject} + " -> " + Simplified).str();
  62     report(C, Arg, Message);
  63   }
  64 };
  65 } // namespace
  66
  67 static void addSimplifyChecker(AnalysisASTConsumer &AnalysisConsumer,
  68                                AnalyzerOptions &AnOpts) {
  69   AnOpts.CheckersAndPackages = {{"SimplifyChecker", true}};
  70   AnalysisConsumer.AddCheckerRegistrationFn([](CheckerRegistry &Registry) {
  71     Registry.addChecker<SimplifyChecker>("SimplifyChecker", "EmptyDescription",
  72                                          "EmptyDocsUri");
  73   });
  74 }
  75
  76 static void runThisCheckerOnCode(const std::string &Code, std::string &Diags) {
  77   ASSERT_TRUE(runCheckerOnCode<addSimplifyChecker>(Code, Diags,
  78                                                    /*OnlyEmitWarnings=*/true));
  79   ASSERT_FALSE(Diags.empty());
  80   ASSERT_EQ(Diags.back(), '\n');
  81   Diags.pop_back();
  82 }
  83
  84 namespace {
  85
  86 TEST(SValSimplifyerTest, LHSConstrainedNullPtrDiff) {
  87   constexpr auto Code = R"cpp(
  88 template <class T> void simplify(T);
  89 void LHSConstrainedNullPtrDiff(char *p, char *q) {
  90   int diff = p - q;
  91   if (!p)
  92     simplify(diff);
  93 })cpp";
  94
  95   std::string Diags;
  96   runThisCheckerOnCode(Code, Diags);
  97   replace(Diags, "(reg_$0<char * p>)", "reg_p");
  98   replace(Diags, "(reg_$1<char * q>)", "reg_q");
  99   // This should not be simplified to "Unknown".
 100   EXPECT_EQ(Diags, "SimplifyChecker: reg_p - reg_q -> 0U - reg_q");
 101 }
 102
 103 } // namespace