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1 //==--AnalyzerStatsChecker.cpp - Analyzer visitation statistics --*- 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 // This file reports various statistics about analyzer visitation.
10 //===----------------------------------------------------------------------===//
11 #include "ClangSACheckers.h"
12 #include "clang/AST/DeclObjC.h"
13 #include "clang/Basic/SourceManager.h"
14 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
15 #include "clang/StaticAnalyzer/Core/Checker.h"
16 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.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 
24 using namespace clang;
25 using namespace ento;
26 
27 #define DEBUG_TYPE "StatsChecker"
28 
29 STATISTIC(NumBlocks,
30           "The # of blocks in top level functions");
31 STATISTIC(NumBlocksUnreachable,
32           "The # of unreachable blocks in analyzing top level functions");
33 
34 namespace {
35 class AnalyzerStatsChecker : public Checker<check::EndAnalysis> {
36 public:
37   void checkEndAnalysis(ExplodedGraph &G, BugReporter &B,ExprEngine &Eng) const;
38 };
39 }
40 
checkEndAnalysis(ExplodedGraph & G,BugReporter & B,ExprEngine & Eng) const41 void AnalyzerStatsChecker::checkEndAnalysis(ExplodedGraph &G,
42                                             BugReporter &B,
43                                             ExprEngine &Eng) const {
44   const CFG *C = nullptr;
45   const SourceManager &SM = B.getSourceManager();
46   llvm::SmallPtrSet<const CFGBlock*, 32> reachable;
47 
48   // Root node should have the location context of the top most function.
49   const ExplodedNode *GraphRoot = *G.roots_begin();
50   const LocationContext *LC = GraphRoot->getLocation().getLocationContext();
51 
52   const Decl *D = LC->getDecl();
53 
54   // Iterate over the exploded graph.
55   for (ExplodedGraph::node_iterator I = G.nodes_begin();
56       I != G.nodes_end(); ++I) {
57     const ProgramPoint &P = I->getLocation();
58 
59     // Only check the coverage in the top level function (optimization).
60     if (D != P.getLocationContext()->getDecl())
61       continue;
62 
63     if (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>(D) || isa<ObjCMethodDecl>(D)) {
98     const NamedDecl *ND = cast<NamedDecl>(D);
99     output << *ND;
100   }
101   else if (isa<BlockDecl>(D)) {
102     output << "block(line:" << Loc.getLine() << ":col:" << Loc.getColumn();
103   }
104 
105   NumBlocksUnreachable += unreachable;
106   NumBlocks += total;
107   std::string NameOfRootFunction = output.str();
108 
109   output << " -> Total CFGBlocks: " << total << " | Unreachable CFGBlocks: "
110       << unreachable << " | Exhausted Block: "
111       << (Eng.wasBlocksExhausted() ? "yes" : "no")
112       << " | Empty WorkList: "
113       << (Eng.hasEmptyWorkList() ? "yes" : "no");
114 
115   B.EmitBasicReport(D, this, "Analyzer Statistics", "Internal Statistics",
116                     output.str(), PathDiagnosticLocation(D, SM));
117 
118   // Emit warning for each block we bailed out on.
119   typedef CoreEngine::BlocksExhausted::const_iterator ExhaustedIterator;
120   const CoreEngine &CE = Eng.getCoreEngine();
121   for (ExhaustedIterator I = CE.blocks_exhausted_begin(),
122       E = CE.blocks_exhausted_end(); I != E; ++I) {
123     const BlockEdge &BE =  I->first;
124     const CFGBlock *Exit = BE.getDst();
125     const CFGElement &CE = Exit->front();
126     if (Optional<CFGStmt> CS = CE.getAs<CFGStmt>()) {
127       SmallString<128> bufI;
128       llvm::raw_svector_ostream outputI(bufI);
129       outputI << "(" << NameOfRootFunction << ")" <<
130                  ": The analyzer generated a sink at this point";
131       B.EmitBasicReport(
132           D, this, "Sink Point", "Internal Statistics", outputI.str(),
133           PathDiagnosticLocation::createBegin(CS->getStmt(), SM, LC));
134     }
135   }
136 }
137 
registerAnalyzerStatsChecker(CheckerManager & mgr)138 void ento::registerAnalyzerStatsChecker(CheckerManager &mgr) {
139   mgr.registerChecker<AnalyzerStatsChecker>();
140 }
141