lib/Debugger/Debugger.cpp

   1 //===-- Debugger.cpp - LLVM debugger library implementation ---------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source 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 <memory>
  22 using namespace llvm;
  23
  24 /// Debugger constructor - Initialize the debugger to its initial, empty, state.
  25 ///
  26 Debugger::Debugger() : Environment(0), Program(0), Process(0) {
  27 }
  28
  29 Debugger::~Debugger() {
  30   // Killing the program could throw an exception.  We don't want to progagate
  31   // the exception out of our destructor though.
  32   try {
  33     killProgram();
  34   } catch (const char *) {
  35   } catch (const std::string &) {
  36   }
  37
  38   unloadProgram();
  39 }
  40
  41 /// getProgramPath - Get the path of the currently loaded program, or an
  42 /// empty string if none is loaded.
  43 std::string Debugger::getProgramPath() const {
  44   return Program ? Program->getModuleIdentifier() : "";
  45 }
  46
  47 static Module *
  48 getMaterializedModuleProvider(const std::string &Filename) {
  49   std::auto_ptr<MemoryBuffer> Buffer;
  50   Buffer.reset(MemoryBuffer::getFileOrSTDIN(&Filename[0], Filename.size()));
  51   if (Buffer.get())
  52     return ParseBitcodeFile(Buffer.get());
  53   return 0;
  54 }
  55
  56 /// loadProgram - If a program is currently loaded, unload it.  Then search
  57 /// the PATH for the specified program, loading it when found.  If the
  58 /// specified program cannot be found, an exception is thrown to indicate the
  59 /// error.
  60 void Debugger::loadProgram(const std::string &Filename) {
  61   if ((Program = getMaterializedModuleProvider(Filename)) ||
  62       (Program = getMaterializedModuleProvider(Filename+".bc")))
  63     return;   // Successfully loaded the program.
  64
  65   // Search the program path for the file...
  66   if (const char *PathS = getenv("PATH")) {
  67     std::string Path = PathS;
  68
  69     std::string Directory = getToken(Path, ":");
  70     while (!Directory.empty()) {
  71       if ((Program = getMaterializedModuleProvider(Directory +"/"+ Filename)) ||
  72           (Program = getMaterializedModuleProvider(Directory +"/"+ Filename
  73                                                                       + ".bc")))
  74         return;   // Successfully loaded the program.
  75
  76       Directory = getToken(Path, ":");
  77     }
  78   }
  79
  80   throw "Could not find program '" + Filename + "'!";
  81 }
  82
  83 /// unloadProgram - If a program is running, kill it, then unload all traces
  84 /// of the current program.  If no program is loaded, this method silently
  85 /// succeeds.
  86 void Debugger::unloadProgram() {
  87   if (!isProgramLoaded()) return;
  88   killProgram();
  89   delete Program;
  90   Program = 0;
  91 }
  92
  93
  94 /// createProgram - Create an instance of the currently loaded program,
  95 /// killing off any existing one.  This creates the program and stops it at
  96 /// the first possible moment.  If there is no program loaded or if there is a
  97 /// problem starting the program, this method throws an exception.
  98 void Debugger::createProgram() {
  99   if (!isProgramLoaded())
 100     throw "Cannot start program: none is loaded.";
 101
 102   // Kill any existing program.
 103   killProgram();
 104
 105   // Add argv[0] to the arguments vector..
 106   std::vector<std::string> Args(ProgramArguments);
 107   Args.insert(Args.begin(), getProgramPath());
 108
 109   // Start the new program... this could throw if the program cannot be started.
 110   Process = InferiorProcess::create(Program, Args, Environment);
 111 }
 112
 113 InferiorProcess *
 114 InferiorProcess::create(Module *M, const std::vector<std::string> &Arguments,
 115                         const char * const *envp) {
 116   throw"No supported binding to inferior processes (debugger not implemented).";
 117 }
 118
 119 /// killProgram - If the program is currently executing, kill off the
 120 /// process and free up any state related to the currently running program.  If
 121 /// there is no program currently running, this just silently succeeds.
 122 void Debugger::killProgram() {
 123   // The destructor takes care of the dirty work.
 124   try {
 125     delete Process;
 126   } catch (...) {
 127     Process = 0;
 128     throw;
 129   }
 130   Process = 0;
 131 }
 132
 133 /// stepProgram - Implement the 'step' command, continuing execution until
 134 /// the next possible stop point.
 135 void Debugger::stepProgram() {
 136   assert(isProgramRunning() && "Cannot step if the program isn't running!");
 137   try {
 138     Process->stepProgram();
 139   } catch (InferiorProcessDead &IPD) {
 140     killProgram();
 141     throw NonErrorException("The program stopped with exit code " +
 142                             itostr(IPD.getExitCode()));
 143   } catch (...) {
 144     killProgram();
 145     throw;
 146   }
 147 }
 148
 149 /// nextProgram - Implement the 'next' command, continuing execution until
 150 /// the next possible stop point that is in the current function.
 151 void Debugger::nextProgram() {
 152   assert(isProgramRunning() && "Cannot next if the program isn't running!");
 153   try {
 154     // This should step the process.  If the process enters a function, then it
 155     // should 'finish' it.  However, figuring this out is tricky.  In
 156     // particular, the program can do any of:
 157     //  0. Not change current frame.
 158     //  1. Entering or exiting a region within the current function
 159     //     (which changes the frame ID, but which we shouldn't 'finish')
 160     //  2. Exiting the current function (which changes the frame ID)
 161     //  3. Entering a function (which should be 'finish'ed)
 162     // For this reason, we have to be very careful about when we decide to do
 163     // the 'finish'.
 164
 165     // Get the current frame, but don't trust it.  It could change...
 166     void *CurrentFrame = Process->getPreviousFrame(0);
 167
 168     // Don't trust the current frame: get the caller frame.
 169     void *ParentFrame  = Process->getPreviousFrame(CurrentFrame);
 170
 171     // Ok, we have some information, run the program one step.
 172     Process->stepProgram();
 173
 174     // Where is the new frame?  The most common case, by far is that it has not
 175     // been modified (Case #0), in which case we don't need to do anything more.
 176     void *NewFrame = Process->getPreviousFrame(0);
 177     if (NewFrame != CurrentFrame) {
 178       // Ok, the frame changed.  If we are case #1, then the parent frame will
 179       // be identical.
 180       void *NewParentFrame = Process->getPreviousFrame(NewFrame);
 181       if (ParentFrame != NewParentFrame) {
 182         // Ok, now we know we aren't case #0 or #1.  Check to see if we entered
 183         // a new function.  If so, the parent frame will be "CurrentFrame".
 184         if (CurrentFrame == NewParentFrame)
 185           Process->finishProgram(NewFrame);
 186       }
 187     }
 188
 189   } catch (InferiorProcessDead &IPD) {
 190     killProgram();
 191     throw NonErrorException("The program stopped with exit code " +
 192                             itostr(IPD.getExitCode()));
 193   } catch (...) {
 194     killProgram();
 195     throw;
 196   }
 197 }
 198
 199 /// finishProgram - Implement the 'finish' command, continuing execution
 200 /// until the specified frame ID returns.
 201 void Debugger::finishProgram(void *Frame) {
 202   assert(isProgramRunning() && "Cannot cont if the program isn't running!");
 203   try {
 204     Process->finishProgram(Frame);
 205   } catch (InferiorProcessDead &IPD) {
 206     killProgram();
 207     throw NonErrorException("The program stopped with exit code " +
 208                             itostr(IPD.getExitCode()));
 209   } catch (...) {
 210     killProgram();
 211     throw;
 212   }
 213 }
 214
 215 /// contProgram - Implement the 'cont' command, continuing execution until
 216 /// the next breakpoint is encountered.
 217 void Debugger::contProgram() {
 218   assert(isProgramRunning() && "Cannot cont if the program isn't running!");
 219   try {
 220     Process->contProgram();
 221   } catch (InferiorProcessDead &IPD) {
 222     killProgram();
 223     throw NonErrorException("The program stopped with exit code " +
 224                             itostr(IPD.getExitCode()));
 225   } catch (...) {
 226     killProgram();
 227     throw;
 228   }
 229 }