1 //===- CFGPrinter.cpp - DOT printer for the control flow graph ------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines a '-print-cfg' analysis pass, which emits the
11 // cfg.<fnname>.dot file for each function in the program, with a graph of the
12 // CFG for that function.
13 //
14 // The other main feature of this file is that it implements the
15 // Function::viewCFG method, which is useful for debugging passes which operate
16 // on the CFG.
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #include "llvm/Function.h"
21 #include "llvm/Instructions.h"
22 #include "llvm/Pass.h"
23 #include "llvm/Analysis/CFGPrinter.h"
24 #include "llvm/Assembly/Writer.h"
25 #include "llvm/Support/CFG.h"
26 #include "llvm/Support/GraphWriter.h"
27 #include <sstream>
28 #include <fstream>
29 using namespace llvm;
30 
31 /// CFGOnly flag - This is used to control whether or not the CFG graph printer
32 /// prints out the contents of basic blocks or not.  This is acceptable because
33 /// this code is only really used for debugging purposes.
34 ///
35 static bool CFGOnly = false;
36 
37 namespace llvm {
38 template<>
39 struct DOTGraphTraits<const Function*> : public DefaultDOTGraphTraits {
40   static std::string getGraphName(const Function *F) {
41     return "CFG for '" + F->getName() + "' function";
42   }
43 
44   static std::string getNodeLabel(const BasicBlock *Node,
45                                   const Function *Graph) {
46     if (CFGOnly && !Node->getName().empty())
47       return Node->getName() + ":";
48 
49     std::ostringstream Out;
50     if (CFGOnly) {
51       WriteAsOperand(Out, Node, false, true);
52       return Out.str();
53     }
54 
55     if (Node->getName().empty()) {
56       WriteAsOperand(Out, Node, false, true);
57       Out << ":";
58     }
59 
60     Out << *Node;
61     std::string OutStr = Out.str();
62     if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
63 
64     // Process string output to make it nicer...
65     for (unsigned i = 0; i != OutStr.length(); ++i)
66       if (OutStr[i] == '\n') {                            // Left justify
67         OutStr[i] = '\\';
68         OutStr.insert(OutStr.begin()+i+1, 'l');
69       } else if (OutStr[i] == ';') {                      // Delete comments!
70         unsigned Idx = OutStr.find('\n', i+1);            // Find end of line
71         OutStr.erase(OutStr.begin()+i, OutStr.begin()+Idx);
72         --i;
73       }
74 
75     return OutStr;
76   }
77 
78   static std::string getEdgeSourceLabel(const BasicBlock *Node,
79                                         succ_const_iterator I) {
80     // Label source of conditional branches with "T" or "F"
81     if (const BranchInst *BI = dyn_cast<BranchInst>(Node->getTerminator()))
82       if (BI->isConditional())
83         return (I == succ_begin(Node)) ? "T" : "F";
84     return "";
85   }
86 };
87 }
88 
89 namespace {
90   struct CFGPrinter : public FunctionPass {
91     virtual bool runOnFunction(Function &F) {
92       std::string Filename = "cfg." + F.getName() + ".dot";
93       std::cerr << "Writing '" << Filename << "'...";
94       std::ofstream File(Filename.c_str());
95 
96       if (File.good())
97         WriteGraph(File, (const Function*)&F);
98       else
99         std::cerr << "  error opening file for writing!";
100       std::cerr << "\n";
101       return false;
102     }
103 
104     void print(std::ostream &OS, const Module* = 0) const {}
105 
106     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
107       AU.setPreservesAll();
108     }
109   };
110 
111   RegisterAnalysis<CFGPrinter> P1("print-cfg",
112                                   "Print CFG of function to 'dot' file");
113 
114   struct CFGOnlyPrinter : public CFGPrinter {
115     virtual bool runOnFunction(Function &F) {
116       bool OldCFGOnly = CFGOnly;
117       CFGOnly = true;
118       CFGPrinter::runOnFunction(F);
119       CFGOnly = OldCFGOnly;
120       return false;
121     }
122     void print(std::ostream &OS, const Module* = 0) const {}
123 
124     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
125       AU.setPreservesAll();
126     }
127   };
128 
129   RegisterAnalysis<CFGOnlyPrinter>
130   P2("print-cfg-only",
131      "Print CFG of function to 'dot' file (with no function bodies)");
132 }
133 
134 /// viewCFG - This function is meant for use from the debugger.  You can just
135 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
136 /// program, displaying the CFG of the current function.  This depends on there
137 /// being a 'dot' and 'gv' program in your path.
138 ///
139 void Function::viewCFG() const {
140   std::string Filename = "/tmp/cfg." + getName() + ".dot";
141   std::cerr << "Writing '" << Filename << "'... ";
142   std::ofstream F(Filename.c_str());
143 
144   if (!F.good()) {
145     std::cerr << "  error opening file for writing!\n";
146     return;
147   }
148 
149   WriteGraph(F, this);
150   F.close();
151   std::cerr << "\n";
152 
153   std::cerr << "Running 'dot' program... " << std::flush;
154   if (system(("dot -Tps -Nfontname=Courier -Gsize=7.5,10 " + Filename
155               + " > /tmp/cfg.tempgraph.ps").c_str())) {
156     std::cerr << "Error running dot: 'dot' not in path?\n";
157   } else {
158     std::cerr << "\n";
159     system("gv /tmp/cfg.tempgraph.ps");
160   }
161   system(("rm " + Filename + " /tmp/cfg.tempgraph.ps").c_str());
162 }
163 
164 /// viewCFGOnly - This function is meant for use from the debugger.  It works
165 /// just like viewCFG, but it does not include the contents of basic blocks
166 /// into the nodes, just the label.  If you are only interested in the CFG t
167 /// his can make the graph smaller.
168 ///
169 void Function::viewCFGOnly() const {
170   CFGOnly = true;
171   viewCFG();
172   CFGOnly = false;
173 }
174 
175 FunctionPass *llvm::createCFGPrinterPass () {
176   return new CFGPrinter();
177 }
178 
179 FunctionPass *llvm::createCFGOnlyPrinterPass () {
180   return new CFGOnlyPrinter();
181 }
182 
183