1 //===- CFGPrinter.cpp - DOT printer for the control flow graph ------------===// 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 // 9 // This file defines a `-dot-cfg` analysis pass, which emits the 10 // `<prefix>.<fnname>.dot` file for each function in the program, with a graph 11 // of the CFG for that function. The default value for `<prefix>` is `cfg` but 12 // can be customized as needed. 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/Analysis/CFGPrinter.h" 21 #include "llvm/Pass.h" 22 #include "llvm/Support/FileSystem.h" 23 using namespace llvm; 24 25 static cl::opt<std::string> CFGFuncName( 26 "cfg-func-name", cl::Hidden, 27 cl::desc("The name of a function (or its substring)" 28 " whose CFG is viewed/printed.")); 29 30 static cl::opt<std::string> CFGDotFilenamePrefix( 31 "cfg-dot-filename-prefix", cl::Hidden, 32 cl::desc("The prefix used for the CFG dot file names.")); 33 34 namespace { 35 struct CFGViewerLegacyPass : public FunctionPass { 36 static char ID; // Pass identifcation, replacement for typeid 37 CFGViewerLegacyPass() : FunctionPass(ID) { 38 initializeCFGViewerLegacyPassPass(*PassRegistry::getPassRegistry()); 39 } 40 41 bool runOnFunction(Function &F) override { 42 F.viewCFG(); 43 return false; 44 } 45 46 void print(raw_ostream &OS, const Module* = nullptr) const override {} 47 48 void getAnalysisUsage(AnalysisUsage &AU) const override { 49 AU.setPreservesAll(); 50 } 51 }; 52 } 53 54 char CFGViewerLegacyPass::ID = 0; 55 INITIALIZE_PASS(CFGViewerLegacyPass, "view-cfg", "View CFG of function", false, true) 56 57 PreservedAnalyses CFGViewerPass::run(Function &F, 58 FunctionAnalysisManager &AM) { 59 F.viewCFG(); 60 return PreservedAnalyses::all(); 61 } 62 63 64 namespace { 65 struct CFGOnlyViewerLegacyPass : public FunctionPass { 66 static char ID; // Pass identifcation, replacement for typeid 67 CFGOnlyViewerLegacyPass() : FunctionPass(ID) { 68 initializeCFGOnlyViewerLegacyPassPass(*PassRegistry::getPassRegistry()); 69 } 70 71 bool runOnFunction(Function &F) override { 72 F.viewCFGOnly(); 73 return false; 74 } 75 76 void print(raw_ostream &OS, const Module* = nullptr) const override {} 77 78 void getAnalysisUsage(AnalysisUsage &AU) const override { 79 AU.setPreservesAll(); 80 } 81 }; 82 } 83 84 char CFGOnlyViewerLegacyPass::ID = 0; 85 INITIALIZE_PASS(CFGOnlyViewerLegacyPass, "view-cfg-only", 86 "View CFG of function (with no function bodies)", false, true) 87 88 PreservedAnalyses CFGOnlyViewerPass::run(Function &F, 89 FunctionAnalysisManager &AM) { 90 F.viewCFGOnly(); 91 return PreservedAnalyses::all(); 92 } 93 94 static void writeCFGToDotFile(Function &F, bool CFGOnly = false) { 95 if (!CFGFuncName.empty() && !F.getName().contains(CFGFuncName)) 96 return; 97 std::string Filename = 98 (CFGDotFilenamePrefix + "." + F.getName() + ".dot").str(); 99 errs() << "Writing '" << Filename << "'..."; 100 101 std::error_code EC; 102 raw_fd_ostream File(Filename, EC, sys::fs::OF_Text); 103 104 if (!EC) 105 WriteGraph(File, (const Function*)&F, CFGOnly); 106 else 107 errs() << " error opening file for writing!"; 108 errs() << "\n"; 109 } 110 111 namespace { 112 struct CFGPrinterLegacyPass : public FunctionPass { 113 static char ID; // Pass identification, replacement for typeid 114 CFGPrinterLegacyPass() : FunctionPass(ID) { 115 initializeCFGPrinterLegacyPassPass(*PassRegistry::getPassRegistry()); 116 } 117 118 bool runOnFunction(Function &F) override { 119 writeCFGToDotFile(F); 120 return false; 121 } 122 123 void print(raw_ostream &OS, const Module* = nullptr) const override {} 124 125 void getAnalysisUsage(AnalysisUsage &AU) const override { 126 AU.setPreservesAll(); 127 } 128 }; 129 } 130 131 char CFGPrinterLegacyPass::ID = 0; 132 INITIALIZE_PASS(CFGPrinterLegacyPass, "dot-cfg", "Print CFG of function to 'dot' file", 133 false, true) 134 135 PreservedAnalyses CFGPrinterPass::run(Function &F, 136 FunctionAnalysisManager &AM) { 137 writeCFGToDotFile(F); 138 return PreservedAnalyses::all(); 139 } 140 141 namespace { 142 struct CFGOnlyPrinterLegacyPass : public FunctionPass { 143 static char ID; // Pass identification, replacement for typeid 144 CFGOnlyPrinterLegacyPass() : FunctionPass(ID) { 145 initializeCFGOnlyPrinterLegacyPassPass(*PassRegistry::getPassRegistry()); 146 } 147 148 bool runOnFunction(Function &F) override { 149 writeCFGToDotFile(F, /*CFGOnly=*/true); 150 return false; 151 } 152 void print(raw_ostream &OS, const Module* = nullptr) const override {} 153 154 void getAnalysisUsage(AnalysisUsage &AU) const override { 155 AU.setPreservesAll(); 156 } 157 }; 158 } 159 160 char CFGOnlyPrinterLegacyPass::ID = 0; 161 INITIALIZE_PASS(CFGOnlyPrinterLegacyPass, "dot-cfg-only", 162 "Print CFG of function to 'dot' file (with no function bodies)", 163 false, true) 164 165 PreservedAnalyses CFGOnlyPrinterPass::run(Function &F, 166 FunctionAnalysisManager &AM) { 167 writeCFGToDotFile(F, /*CFGOnly=*/true); 168 return PreservedAnalyses::all(); 169 } 170 171 /// viewCFG - This function is meant for use from the debugger. You can just 172 /// say 'call F->viewCFG()' and a ghostview window should pop up from the 173 /// program, displaying the CFG of the current function. This depends on there 174 /// being a 'dot' and 'gv' program in your path. 175 /// 176 void Function::viewCFG() const { 177 if (!CFGFuncName.empty() && !getName().contains(CFGFuncName)) 178 return; 179 ViewGraph(this, "cfg" + getName()); 180 } 181 182 /// viewCFGOnly - This function is meant for use from the debugger. It works 183 /// just like viewCFG, but it does not include the contents of basic blocks 184 /// into the nodes, just the label. If you are only interested in the CFG 185 /// this can make the graph smaller. 186 /// 187 void Function::viewCFGOnly() const { 188 if (!CFGFuncName.empty() && !getName().contains(CFGFuncName)) 189 return; 190 ViewGraph(this, "cfg" + getName(), true); 191 } 192 193 FunctionPass *llvm::createCFGPrinterLegacyPassPass () { 194 return new CFGPrinterLegacyPass(); 195 } 196 197 FunctionPass *llvm::createCFGOnlyPrinterLegacyPassPass () { 198 return new CFGOnlyPrinterLegacyPass(); 199 } 200 201