LLVM API Documentation

CFGPrinter.cpp
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00001 //===- CFGPrinter.cpp - DOT printer for the control flow graph ------------===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file is distributed under the University of Illinois Open Source
00006 // License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file defines a '-dot-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/Analysis/CFGPrinter.h"
00021 #include "llvm/Pass.h"
00022 using namespace llvm;
00023 
00024 namespace {
00025   struct CFGViewer : public FunctionPass {
00026     static char ID; // Pass identifcation, replacement for typeid
00027     CFGViewer() : FunctionPass(ID) {
00028       initializeCFGOnlyViewerPass(*PassRegistry::getPassRegistry());
00029     }
00030 
00031     bool runOnFunction(Function &F) override {
00032       F.viewCFG();
00033       return false;
00034     }
00035 
00036     void print(raw_ostream &OS, const Module* = nullptr) const override {}
00037 
00038     void getAnalysisUsage(AnalysisUsage &AU) const override {
00039       AU.setPreservesAll();
00040     }
00041   };
00042 }
00043 
00044 char CFGViewer::ID = 0;
00045 INITIALIZE_PASS(CFGViewer, "view-cfg", "View CFG of function", false, true)
00046 
00047 namespace {
00048   struct CFGOnlyViewer : public FunctionPass {
00049     static char ID; // Pass identifcation, replacement for typeid
00050     CFGOnlyViewer() : FunctionPass(ID) {
00051       initializeCFGOnlyViewerPass(*PassRegistry::getPassRegistry());
00052     }
00053 
00054     bool runOnFunction(Function &F) override {
00055       F.viewCFGOnly();
00056       return false;
00057     }
00058 
00059     void print(raw_ostream &OS, const Module* = nullptr) const override {}
00060 
00061     void getAnalysisUsage(AnalysisUsage &AU) const override {
00062       AU.setPreservesAll();
00063     }
00064   };
00065 }
00066 
00067 char CFGOnlyViewer::ID = 0;
00068 INITIALIZE_PASS(CFGOnlyViewer, "view-cfg-only",
00069                 "View CFG of function (with no function bodies)", false, true)
00070 
00071 namespace {
00072   struct CFGPrinter : public FunctionPass {
00073     static char ID; // Pass identification, replacement for typeid
00074     CFGPrinter() : FunctionPass(ID) {
00075       initializeCFGPrinterPass(*PassRegistry::getPassRegistry());
00076     }
00077 
00078     bool runOnFunction(Function &F) override {
00079       std::string Filename = "cfg." + F.getName().str() + ".dot";
00080       errs() << "Writing '" << Filename << "'...";
00081       
00082       std::string ErrorInfo;
00083       raw_fd_ostream File(Filename.c_str(), ErrorInfo, sys::fs::F_Text);
00084 
00085       if (ErrorInfo.empty())
00086         WriteGraph(File, (const Function*)&F);
00087       else
00088         errs() << "  error opening file for writing!";
00089       errs() << "\n";
00090       return false;
00091     }
00092 
00093     void print(raw_ostream &OS, const Module* = nullptr) const override {}
00094 
00095     void getAnalysisUsage(AnalysisUsage &AU) const override {
00096       AU.setPreservesAll();
00097     }
00098   };
00099 }
00100 
00101 char CFGPrinter::ID = 0;
00102 INITIALIZE_PASS(CFGPrinter, "dot-cfg", "Print CFG of function to 'dot' file", 
00103                 false, true)
00104 
00105 namespace {
00106   struct CFGOnlyPrinter : public FunctionPass {
00107     static char ID; // Pass identification, replacement for typeid
00108     CFGOnlyPrinter() : FunctionPass(ID) {
00109       initializeCFGOnlyPrinterPass(*PassRegistry::getPassRegistry());
00110     }
00111 
00112     bool runOnFunction(Function &F) override {
00113       std::string Filename = "cfg." + F.getName().str() + ".dot";
00114       errs() << "Writing '" << Filename << "'...";
00115 
00116       std::string ErrorInfo;
00117       raw_fd_ostream File(Filename.c_str(), ErrorInfo, sys::fs::F_Text);
00118       
00119       if (ErrorInfo.empty())
00120         WriteGraph(File, (const Function*)&F, true);
00121       else
00122         errs() << "  error opening file for writing!";
00123       errs() << "\n";
00124       return false;
00125     }
00126     void print(raw_ostream &OS, const Module* = nullptr) const override {}
00127 
00128     void getAnalysisUsage(AnalysisUsage &AU) const override {
00129       AU.setPreservesAll();
00130     }
00131   };
00132 }
00133 
00134 char CFGOnlyPrinter::ID = 0;
00135 INITIALIZE_PASS(CFGOnlyPrinter, "dot-cfg-only",
00136    "Print CFG of function to 'dot' file (with no function bodies)",
00137    false, true)
00138 
00139 /// viewCFG - This function is meant for use from the debugger.  You can just
00140 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
00141 /// program, displaying the CFG of the current function.  This depends on there
00142 /// being a 'dot' and 'gv' program in your path.
00143 ///
00144 void Function::viewCFG() const {
00145   ViewGraph(this, "cfg" + getName());
00146 }
00147 
00148 /// viewCFGOnly - This function is meant for use from the debugger.  It works
00149 /// just like viewCFG, but it does not include the contents of basic blocks
00150 /// into the nodes, just the label.  If you are only interested in the CFG t
00151 /// his can make the graph smaller.
00152 ///
00153 void Function::viewCFGOnly() const {
00154   ViewGraph(this, "cfg" + getName(), true);
00155 }
00156 
00157 FunctionPass *llvm::createCFGPrinterPass () {
00158   return new CFGPrinter();
00159 }
00160 
00161 FunctionPass *llvm::createCFGOnlyPrinterPass () {
00162   return new CFGOnlyPrinter();
00163 }
00164