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