1 //==--AnalyzerStatsChecker.cpp - Analyzer visitation statistics --*- C++ -*-==//
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 // This file reports various statistics about analyzer visitation.
9 //===----------------------------------------------------------------------===//
10 #include "clang/AST/DeclObjC.h"
11 #include "clang/Basic/SourceManager.h"
12 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
13 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
14 #include "clang/StaticAnalyzer/Core/Checker.h"
15 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
16 #include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/ADT/SmallString.h"
21 #include "llvm/ADT/Statistic.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include <optional>
24 
25 using namespace clang;
26 using namespace ento;
27 
28 #define DEBUG_TYPE "StatsChecker"
29 
30 STATISTIC(NumBlocks,
31           "The # of blocks in top level functions");
32 STATISTIC(NumBlocksUnreachable,
33           "The # of unreachable blocks in analyzing top level functions");
34 
35 namespace {
36 class AnalyzerStatsChecker : public Checker<check::EndAnalysis> {
37 public:
38   void checkEndAnalysis(ExplodedGraph &G, BugReporter &B,ExprEngine &Eng) const;
39 };
40 }
41 
42 void AnalyzerStatsChecker::checkEndAnalysis(ExplodedGraph &G,
43                                             BugReporter &B,
44                                             ExprEngine &Eng) const {
45   const CFG *C = nullptr;
46   const SourceManager &SM = B.getSourceManager();
47   llvm::SmallPtrSet<const CFGBlock*, 32> reachable;
48 
49   // Root node should have the location context of the top most function.
50   const ExplodedNode *GraphRoot = *G.roots_begin();
51   const LocationContext *LC = GraphRoot->getLocation().getLocationContext();
52 
53   const Decl *D = LC->getDecl();
54 
55   // Iterate over the exploded graph.
56   for (const ExplodedNode &N : G.nodes()) {
57     const ProgramPoint &P = N.getLocation();
58 
59     // Only check the coverage in the top level function (optimization).
60     if (D != P.getLocationContext()->getDecl())
61       continue;
62 
63     if (std::optional<BlockEntrance> BE = P.getAs<BlockEntrance>()) {
64       const CFGBlock *CB = BE->getBlock();
65       reachable.insert(CB);
66     }
67   }
68 
69   // Get the CFG and the Decl of this block.
70   C = LC->getCFG();
71 
72   unsigned total = 0, unreachable = 0;
73 
74   // Find CFGBlocks that were not covered by any node
75   for (CFG::const_iterator I = C->begin(); I != C->end(); ++I) {
76     const CFGBlock *CB = *I;
77     ++total;
78     // Check if the block is unreachable
79     if (!reachable.count(CB)) {
80       ++unreachable;
81     }
82   }
83 
84   // We never 'reach' the entry block, so correct the unreachable count
85   unreachable--;
86   // There is no BlockEntrance corresponding to the exit block as well, so
87   // assume it is reached as well.
88   unreachable--;
89 
90   // Generate the warning string
91   SmallString<128> buf;
92   llvm::raw_svector_ostream output(buf);
93   PresumedLoc Loc = SM.getPresumedLoc(D->getLocation());
94   if (!Loc.isValid())
95     return;
96 
97   if (isa<FunctionDecl, ObjCMethodDecl>(D)) {
98     const NamedDecl *ND = cast<NamedDecl>(D);
99     output << *ND;
100   } else if (isa<BlockDecl>(D)) {
101     output << "block(line:" << Loc.getLine() << ":col:" << Loc.getColumn();
102   }
103 
104   NumBlocksUnreachable += unreachable;
105   NumBlocks += total;
106   std::string NameOfRootFunction = std::string(output.str());
107 
108   output << " -> Total CFGBlocks: " << total << " | Unreachable CFGBlocks: "
109       << unreachable << " | Exhausted Block: "
110       << (Eng.wasBlocksExhausted() ? "yes" : "no")
111       << " | Empty WorkList: "
112       << (Eng.hasEmptyWorkList() ? "yes" : "no");
113 
114   B.EmitBasicReport(D, this, "Analyzer Statistics", "Internal Statistics",
115                     output.str(), PathDiagnosticLocation(D, SM));
116 
117   // Emit warning for each block we bailed out on.
118   const CoreEngine &CE = Eng.getCoreEngine();
119   for (const BlockEdge &BE : make_first_range(CE.exhausted_blocks())) {
120     const CFGBlock *Exit = BE.getDst();
121     if (Exit->empty())
122       continue;
123     const CFGElement &CE = Exit->front();
124     if (std::optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
125       SmallString<128> bufI;
126       llvm::raw_svector_ostream outputI(bufI);
127       outputI << "(" << NameOfRootFunction << ")" <<
128                  ": The analyzer generated a sink at this point";
129       B.EmitBasicReport(
130           D, this, "Sink Point", "Internal Statistics", outputI.str(),
131           PathDiagnosticLocation::createBegin(CS->getStmt(), SM, LC));
132     }
133   }
134 }
135 
136 void ento::registerAnalyzerStatsChecker(CheckerManager &mgr) {
137   mgr.registerChecker<AnalyzerStatsChecker>();
138 }
139 
140 bool ento::shouldRegisterAnalyzerStatsChecker(const CheckerManager &mgr) {
141   return true;
142 }
143