LLVM API Documentation
00001 //===- CFGPrinter.cpp - DOT printer for the control flow graph ------------===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This file defines a '-print-cfg' analysis pass, which emits the 00011 // cfg.<fnname>.dot file for each function in the program, with a graph of the 00012 // CFG for that function. 00013 // 00014 // The other main feature of this file is that it implements the 00015 // Function::viewCFG method, which is useful for debugging passes which operate 00016 // on the CFG. 00017 // 00018 //===----------------------------------------------------------------------===// 00019 00020 #include "llvm/Function.h" 00021 #include "llvm/Instructions.h" 00022 #include "llvm/Pass.h" 00023 #include "llvm/Analysis/CFGPrinter.h" 00024 #include "llvm/Assembly/Writer.h" 00025 #include "llvm/Support/CFG.h" 00026 #include "llvm/Support/GraphWriter.h" 00027 #include "llvm/Config/config.h" 00028 #include <sstream> 00029 #include <fstream> 00030 using namespace llvm; 00031 00032 /// CFGOnly flag - This is used to control whether or not the CFG graph printer 00033 /// prints out the contents of basic blocks or not. This is acceptable because 00034 /// this code is only really used for debugging purposes. 00035 /// 00036 static bool CFGOnly = false; 00037 00038 namespace llvm { 00039 template<> 00040 struct DOTGraphTraits<const Function*> : public DefaultDOTGraphTraits { 00041 static std::string getGraphName(const Function *F) { 00042 return "CFG for '" + F->getName() + "' function"; 00043 } 00044 00045 static std::string getNodeLabel(const BasicBlock *Node, 00046 const Function *Graph) { 00047 if (CFGOnly && !Node->getName().empty()) 00048 return Node->getName() + ":"; 00049 00050 std::ostringstream Out; 00051 if (CFGOnly) { 00052 WriteAsOperand(Out, Node, false, true); 00053 return Out.str(); 00054 } 00055 00056 if (Node->getName().empty()) { 00057 WriteAsOperand(Out, Node, false, true); 00058 Out << ":"; 00059 } 00060 00061 Out << *Node; 00062 std::string OutStr = Out.str(); 00063 if (OutStr[0] == '\n') OutStr.erase(OutStr.begin()); 00064 00065 // Process string output to make it nicer... 00066 for (unsigned i = 0; i != OutStr.length(); ++i) 00067 if (OutStr[i] == '\n') { // Left justify 00068 OutStr[i] = '\\'; 00069 OutStr.insert(OutStr.begin()+i+1, 'l'); 00070 } else if (OutStr[i] == ';') { // Delete comments! 00071 unsigned Idx = OutStr.find('\n', i+1); // Find end of line 00072 OutStr.erase(OutStr.begin()+i, OutStr.begin()+Idx); 00073 --i; 00074 } 00075 00076 return OutStr; 00077 } 00078 00079 static std::string getEdgeSourceLabel(const BasicBlock *Node, 00080 succ_const_iterator I) { 00081 // Label source of conditional branches with "T" or "F" 00082 if (const BranchInst *BI = dyn_cast<BranchInst>(Node->getTerminator())) 00083 if (BI->isConditional()) 00084 return (I == succ_begin(Node)) ? "T" : "F"; 00085 return ""; 00086 } 00087 }; 00088 } 00089 00090 namespace { 00091 struct CFGPrinter : public FunctionPass { 00092 virtual bool runOnFunction(Function &F) { 00093 std::string Filename = "cfg." + F.getName() + ".dot"; 00094 std::cerr << "Writing '" << Filename << "'..."; 00095 std::ofstream File(Filename.c_str()); 00096 00097 if (File.good()) 00098 WriteGraph(File, (const Function*)&F); 00099 else 00100 std::cerr << " error opening file for writing!"; 00101 std::cerr << "\n"; 00102 return false; 00103 } 00104 00105 void print(std::ostream &OS, const Module* = 0) const {} 00106 00107 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 00108 AU.setPreservesAll(); 00109 } 00110 }; 00111 00112 RegisterAnalysis<CFGPrinter> P1("print-cfg", 00113 "Print CFG of function to 'dot' file"); 00114 00115 struct CFGOnlyPrinter : public CFGPrinter { 00116 virtual bool runOnFunction(Function &F) { 00117 bool OldCFGOnly = CFGOnly; 00118 CFGOnly = true; 00119 CFGPrinter::runOnFunction(F); 00120 CFGOnly = OldCFGOnly; 00121 return false; 00122 } 00123 void print(std::ostream &OS, const Module* = 0) const {} 00124 00125 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 00126 AU.setPreservesAll(); 00127 } 00128 }; 00129 00130 RegisterAnalysis<CFGOnlyPrinter> 00131 P2("print-cfg-only", 00132 "Print CFG of function to 'dot' file (with no function bodies)"); 00133 } 00134 00135 /// viewCFG - This function is meant for use from the debugger. You can just 00136 /// say 'call F->viewCFG()' and a ghostview window should pop up from the 00137 /// program, displaying the CFG of the current function. This depends on there 00138 /// being a 'dot' and 'gv' program in your path. 00139 /// 00140 void Function::viewCFG() const { 00141 ViewGraph(this, "cfg" + getName()); 00142 } 00143 00144 /// viewCFGOnly - This function is meant for use from the debugger. It works 00145 /// just like viewCFG, but it does not include the contents of basic blocks 00146 /// into the nodes, just the label. If you are only interested in the CFG t 00147 /// his can make the graph smaller. 00148 /// 00149 void Function::viewCFGOnly() const { 00150 CFGOnly = true; 00151 viewCFG(); 00152 CFGOnly = false; 00153 } 00154 00155 FunctionPass *llvm::createCFGPrinterPass () { 00156 return new CFGPrinter(); 00157 } 00158 00159 FunctionPass *llvm::createCFGOnlyPrinterPass () { 00160 return new CFGOnlyPrinter(); 00161 } 00162