1 //===- CFGPrinter.cpp - DOT printer for the control flow graph ------------===//
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 //
10 // This file defines a '-dot-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/Compiler.h"
27 #include "llvm/Support/GraphWriter.h"
28 #include "llvm/Config/config.h"
29 #include <iosfwd>
30 #include <sstream>
31 #include <fstream>
32 using namespace llvm;
33 
34 /// CFGOnly flag - This is used to control whether or not the CFG graph printer
35 /// prints out the contents of basic blocks or not.  This is acceptable because
36 /// this code is only really used for debugging purposes.
37 ///
38 static bool CFGOnly = false;
39 
40 namespace llvm {
41 template<>
42 struct DOTGraphTraits<const Function*> : public DefaultDOTGraphTraits {
43   static std::string getGraphName(const Function *F) {
44     return "CFG for '" + F->getName() + "' function";
45   }
46 
47   static std::string getNodeLabel(const BasicBlock *Node,
48                                   const Function *Graph) {
49     if (CFGOnly && !Node->getName().empty())
50       return Node->getName() + ":";
51 
52     std::ostringstream Out;
53     if (CFGOnly) {
54       WriteAsOperand(Out, Node, false);
55       return Out.str();
56     }
57 
58     if (Node->getName().empty()) {
59       WriteAsOperand(Out, Node, false);
60       Out << ":";
61     }
62 
63     Out << *Node;
64     std::string OutStr = Out.str();
65     if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
66 
67     // Process string output to make it nicer...
68     for (unsigned i = 0; i != OutStr.length(); ++i)
69       if (OutStr[i] == '\n') {                            // Left justify
70         OutStr[i] = '\\';
71         OutStr.insert(OutStr.begin()+i+1, 'l');
72       } else if (OutStr[i] == ';') {                      // Delete comments!
73         unsigned Idx = OutStr.find('\n', i+1);            // Find end of line
74         OutStr.erase(OutStr.begin()+i, OutStr.begin()+Idx);
75         --i;
76       }
77 
78     return OutStr;
79   }
80 
81   static std::string getEdgeSourceLabel(const BasicBlock *Node,
82                                         succ_const_iterator I) {
83     // Label source of conditional branches with "T" or "F"
84     if (const BranchInst *BI = dyn_cast<BranchInst>(Node->getTerminator()))
85       if (BI->isConditional())
86         return (I == succ_begin(Node)) ? "T" : "F";
87     return "";
88   }
89 };
90 }
91 
92 namespace {
93   struct VISIBILITY_HIDDEN CFGViewer : public FunctionPass {
94     static char ID; // Pass identifcation, replacement for typeid
95     CFGViewer() : FunctionPass(&ID) {}
96 
97     virtual bool runOnFunction(Function &F) {
98       F.viewCFG();
99       return false;
100     }
101 
102     void print(std::ostream &OS, const Module* = 0) const {}
103 
104     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
105       AU.setPreservesAll();
106     }
107   };
108 }
109 
110 char CFGViewer::ID = 0;
111 static RegisterPass<CFGViewer>
112 V0("view-cfg", "View CFG of function", false, true);
113 
114 namespace {
115   struct VISIBILITY_HIDDEN CFGOnlyViewer : public FunctionPass {
116     static char ID; // Pass identifcation, replacement for typeid
117     CFGOnlyViewer() : FunctionPass(&ID) {}
118 
119     virtual bool runOnFunction(Function &F) {
120       CFGOnly = true;
121       F.viewCFG();
122       CFGOnly = false;
123       return false;
124     }
125 
126     void print(std::ostream &OS, const Module* = 0) const {}
127 
128     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
129       AU.setPreservesAll();
130     }
131   };
132 }
133 
134 char CFGOnlyViewer::ID = 0;
135 static RegisterPass<CFGOnlyViewer>
136 V1("view-cfg-only",
137    "View CFG of function (with no function bodies)", false, true);
138 
139 namespace {
140   struct VISIBILITY_HIDDEN CFGPrinter : public FunctionPass {
141     static char ID; // Pass identification, replacement for typeid
142     CFGPrinter() : FunctionPass(&ID) {}
143     explicit CFGPrinter(void *pid) : FunctionPass(pid) {}
144 
145     virtual bool runOnFunction(Function &F) {
146       std::string Filename = "cfg." + F.getName() + ".dot";
147       cerr << "Writing '" << Filename << "'...";
148       std::ofstream File(Filename.c_str());
149 
150       if (File.good())
151         WriteGraph(File, (const Function*)&F);
152       else
153         cerr << "  error opening file for writing!";
154       cerr << "\n";
155       return false;
156     }
157 
158     void print(std::ostream &OS, const Module* = 0) const {}
159 
160     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
161       AU.setPreservesAll();
162     }
163   };
164 }
165 
166 char CFGPrinter::ID = 0;
167 static RegisterPass<CFGPrinter>
168 P1("dot-cfg", "Print CFG of function to 'dot' file", false, true);
169 
170 namespace {
171   struct VISIBILITY_HIDDEN CFGOnlyPrinter : public CFGPrinter {
172     static char ID; // Pass identification, replacement for typeid
173     CFGOnlyPrinter() : CFGPrinter(&ID) {}
174     virtual bool runOnFunction(Function &F) {
175       bool OldCFGOnly = CFGOnly;
176       CFGOnly = true;
177       CFGPrinter::runOnFunction(F);
178       CFGOnly = OldCFGOnly;
179       return false;
180     }
181     void print(std::ostream &OS, const Module* = 0) const {}
182 
183     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
184       AU.setPreservesAll();
185     }
186   };
187 }
188 
189 char CFGOnlyPrinter::ID = 0;
190 static RegisterPass<CFGOnlyPrinter>
191 P2("dot-cfg-only",
192    "Print CFG of function to 'dot' file (with no function bodies)", false, true);
193 
194 /// viewCFG - This function is meant for use from the debugger.  You can just
195 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
196 /// program, displaying the CFG of the current function.  This depends on there
197 /// being a 'dot' and 'gv' program in your path.
198 ///
199 void Function::viewCFG() const {
200   ViewGraph(this, "cfg" + getName());
201 }
202 
203 /// viewCFGOnly - This function is meant for use from the debugger.  It works
204 /// just like viewCFG, but it does not include the contents of basic blocks
205 /// into the nodes, just the label.  If you are only interested in the CFG t
206 /// his can make the graph smaller.
207 ///
208 void Function::viewCFGOnly() const {
209   CFGOnly = true;
210   viewCFG();
211   CFGOnly = false;
212 }
213 
214 FunctionPass *llvm::createCFGPrinterPass () {
215   return new CFGPrinter();
216 }
217 
218 FunctionPass *llvm::createCFGOnlyPrinterPass () {
219   return new CFGOnlyPrinter();
220 }
221 
222