lib/Debugger/Debugger.cpp

   1 //===-- Debugger.cpp - LLVM debugger library implementation ---------------===//
   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 contains the main implementation of the LLVM debugger library.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Debugger/Debugger.h"
  15 #include "llvm/Module.h"
  16 #include "llvm/ModuleProvider.h"
  17 #include "llvm/Bitcode/ReaderWriter.h"
  18 #include "llvm/Debugger/InferiorProcess.h"
  19 #include "llvm/Support/MemoryBuffer.h"
  20 #include "llvm/ADT/StringExtras.h"
  21 #include <cstdlib>
  22 #include <memory>
  23 using namespace llvm;
  24
  25 /// Debugger constructor - Initialize the debugger to its initial, empty, state.
  26 ///
  27 Debugger::Debugger() : Environment(0), Program(0), Process(0) {
  28 }
  29
  30 Debugger::~Debugger() {
  31   // Killing the program could throw an exception.  We don't want to progagate
  32   // the exception out of our destructor though.
  33   try {
  34     killProgram();
  35   } catch (const char *) {
  36   } catch (const std::string &) {
  37   }
  38
  39   unloadProgram();
  40 }
  41
  42 /// getProgramPath - Get the path of the currently loaded program, or an
  43 /// empty string if none is loaded.
  44 std::string Debugger::getProgramPath() const {
  45   return Program ? Program->getModuleIdentifier() : "";
  46 }
  47
  48 static Module *
  49 getMaterializedModuleProvider(const std::string &Filename,
  50                               LLVMContext& C) {
  51   std::auto_ptr<MemoryBuffer> Buffer;
  52   Buffer.reset(MemoryBuffer::getFileOrSTDIN(Filename.c_str()));
  53   if (Buffer.get())
  54     return ParseBitcodeFile(Buffer.get(), C);
  55   return 0;
  56 }
  57
  58 /// loadProgram - If a program is currently loaded, unload it.  Then search
  59 /// the PATH for the specified program, loading it when found.  If the
  60 /// specified program cannot be found, an exception is thrown to indicate the
  61 /// error.
  62 void Debugger::loadProgram(const std::string &Filename, LLVMContext& C) {
  63   if ((Program = getMaterializedModuleProvider(Filename, C)) ||
  64       (Program = getMaterializedModuleProvider(Filename+".bc", C)))
  65     return;   // Successfully loaded the program.
  66
  67   // Search the program path for the file...
  68   if (const char *PathS = getenv("PATH")) {
  69     std::string Path = PathS;
  70
  71     std::string Directory = getToken(Path, ":");
  72     while (!Directory.empty()) {
  73       if ((Program = getMaterializedModuleProvider(Directory +"/"+ Filename, C))
  74        || (Program = getMaterializedModuleProvider(Directory +"/"+ Filename
  75                                                                    + ".bc", C)))
  76         return;   // Successfully loaded the program.
  77
  78       Directory = getToken(Path, ":");
  79     }
  80   }
  81
  82   throw "Could not find program '" + Filename + "'!";
  83 }
  84
  85 /// unloadProgram - If a program is running, kill it, then unload all traces
  86 /// of the current program.  If no program is loaded, this method silently
  87 /// succeeds.
  88 void Debugger::unloadProgram() {
  89   if (!isProgramLoaded()) return;
  90   killProgram();
  91   delete Program;
  92   Program = 0;
  93 }
  94
  95
  96 /// createProgram - Create an instance of the currently loaded program,
  97 /// killing off any existing one.  This creates the program and stops it at
  98 /// the first possible moment.  If there is no program loaded or if there is a
  99 /// problem starting the program, this method throws an exception.
 100 void Debugger::createProgram() {
 101   if (!isProgramLoaded())
 102     throw "Cannot start program: none is loaded.";
 103
 104   // Kill any existing program.
 105   killProgram();
 106
 107   // Add argv[0] to the arguments vector..
 108   std::vector<std::string> Args(ProgramArguments);
 109   Args.insert(Args.begin(), getProgramPath());
 110
 111   // Start the new program... this could throw if the program cannot be started.
 112   Process = InferiorProcess::create(Program, Args, Environment);
 113 }
 114
 115 InferiorProcess *
 116 InferiorProcess::create(Module *M, const std::vector<std::string> &Arguments,
 117                         const char * const *envp) {
 118   throw"No supported binding to inferior processes (debugger not implemented).";
 119 }
 120
 121 /// killProgram - If the program is currently executing, kill off the
 122 /// process and free up any state related to the currently running program.  If
 123 /// there is no program currently running, this just silently succeeds.
 124 void Debugger::killProgram() {
 125   // The destructor takes care of the dirty work.
 126   try {
 127     delete Process;
 128   } catch (...) {
 129     Process = 0;
 130     throw;
 131   }
 132   Process = 0;
 133 }
 134
 135 /// stepProgram - Implement the 'step' command, continuing execution until
 136 /// the next possible stop point.
 137 void Debugger::stepProgram() {
 138   assert(isProgramRunning() && "Cannot step if the program isn't running!");
 139   try {
 140     Process->stepProgram();
 141   } catch (InferiorProcessDead &IPD) {
 142     killProgram();
 143     throw NonErrorException("The program stopped with exit code " +
 144                             itostr(IPD.getExitCode()));
 145   } catch (...) {
 146     killProgram();
 147     throw;
 148   }
 149 }
 150
 151 /// nextProgram - Implement the 'next' command, continuing execution until
 152 /// the next possible stop point that is in the current function.
 153 void Debugger::nextProgram() {
 154   assert(isProgramRunning() && "Cannot next if the program isn't running!");
 155   try {
 156     // This should step the process.  If the process enters a function, then it
 157     // should 'finish' it.  However, figuring this out is tricky.  In
 158     // particular, the program can do any of:
 159     //  0. Not change current frame.
 160     //  1. Entering or exiting a region within the current function
 161     //     (which changes the frame ID, but which we shouldn't 'finish')
 162     //  2. Exiting the current function (which changes the frame ID)
 163     //  3. Entering a function (which should be 'finish'ed)
 164     // For this reason, we have to be very careful about when we decide to do
 165     // the 'finish'.
 166
 167     // Get the current frame, but don't trust it.  It could change...
 168     void *CurrentFrame = Process->getPreviousFrame(0);
 169
 170     // Don't trust the current frame: get the caller frame.
 171     void *ParentFrame  = Process->getPreviousFrame(CurrentFrame);
 172
 173     // Ok, we have some information, run the program one step.
 174     Process->stepProgram();
 175
 176     // Where is the new frame?  The most common case, by far is that it has not
 177     // been modified (Case #0), in which case we don't need to do anything more.
 178     void *NewFrame = Process->getPreviousFrame(0);
 179     if (NewFrame != CurrentFrame) {
 180       // Ok, the frame changed.  If we are case #1, then the parent frame will
 181       // be identical.
 182       void *NewParentFrame = Process->getPreviousFrame(NewFrame);
 183       if (ParentFrame != NewParentFrame) {
 184         // Ok, now we know we aren't case #0 or #1.  Check to see if we entered
 185         // a new function.  If so, the parent frame will be "CurrentFrame".
 186         if (CurrentFrame == NewParentFrame)
 187           Process->finishProgram(NewFrame);
 188       }
 189     }
 190
 191   } catch (InferiorProcessDead &IPD) {
 192     killProgram();
 193     throw NonErrorException("The program stopped with exit code " +
 194                             itostr(IPD.getExitCode()));
 195   } catch (...) {
 196     killProgram();
 197     throw;
 198   }
 199 }
 200
 201 /// finishProgram - Implement the 'finish' command, continuing execution
 202 /// until the specified frame ID returns.
 203 void Debugger::finishProgram(void *Frame) {
 204   assert(isProgramRunning() && "Cannot cont if the program isn't running!");
 205   try {
 206     Process->finishProgram(Frame);
 207   } catch (InferiorProcessDead &IPD) {
 208     killProgram();
 209     throw NonErrorException("The program stopped with exit code " +
 210                             itostr(IPD.getExitCode()));
 211   } catch (...) {
 212     killProgram();
 213     throw;
 214   }
 215 }
 216
 217 /// contProgram - Implement the 'cont' command, continuing execution until
 218 /// the next breakpoint is encountered.
 219 void Debugger::contProgram() {
 220   assert(isProgramRunning() && "Cannot cont if the program isn't running!");
 221   try {
 222     Process->contProgram();
 223   } catch (InferiorProcessDead &IPD) {
 224     killProgram();
 225     throw NonErrorException("The program stopped with exit code " +
 226                             itostr(IPD.getExitCode()));
 227   } catch (...) {
 228     killProgram();
 229     throw;
 230   }
 231 }