llvm-6502/lib/Debugger/UnixLocalInferiorProcess.cpp

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//===-- UnixLocalInferiorProcess.cpp - A Local process on a Unixy system --===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides one implementation of the InferiorProcess class, which is
// designed to be used on unixy systems (those that support pipe, fork, exec,
// and signals).
//
// When the process is started, the debugger creates a pair of pipes, forks, and
// makes the child start executing the program. The child executes the process
// with an IntrinsicLowering instance that turns debugger intrinsics into actual
// callbacks.
//
// This target takes advantage of the fact that the Module* addresses in the
// parent and the Module* addresses in the child will be the same, due to the
// use of fork(). As such, global addresses looked up in the child can be sent
// over the pipe to the debugger.
//
//===----------------------------------------------------------------------===//
#include "llvm/Debugger/InferiorProcess.h"
#include "llvm/Constant.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/ModuleProvider.h"
#include "llvm/Type.h"
#include "llvm/CodeGen/IntrinsicLowering.h"
#include "llvm/ExecutionEngine/GenericValue.h"
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/ADT/StringExtras.h"
#include "FDHandle.h"
#include <cerrno>
#include <csignal>
#include <unistd.h> // Unix-specific debugger support
#include <sys/types.h>
#include <sys/wait.h>
using namespace llvm;
// runChild - Entry point for the child process.
static void runChild(Module *M, const std::vector<std::string> &Arguments,
const char * const *envp,
FDHandle ReadFD, FDHandle WriteFD);
//===----------------------------------------------------------------------===//
// Parent/Child Pipe Protocol
//===----------------------------------------------------------------------===//
//
// The parent/child communication protocol is designed to have the child process
// responding to requests that the debugger makes. Whenever the child process
// has stopped (due to a break point, single stepping, etc), the child process
// enters a message processing loop, where it reads and responds to commands
// until the parent decides that it wants to continue execution in some way.
//
// Whenever the child process stops, it notifies the debugger by sending a
// character over the wire.
//
namespace {
/// LocationToken - Objects of this type are sent across the pipe from the
/// child to the parent to indicate where various stack frames are located.
struct LocationToken {
unsigned Line, Col;
const GlobalVariable *File;
LocationToken(unsigned L = 0, unsigned C = 0, const GlobalVariable *F = 0)
: Line(L), Col(C), File(F) {}
};
}
// Once the debugger process has received the LocationToken, it can make
// requests of the child by sending one of the following enum values followed by
// any data required by that command. The child responds with data appropriate
// to the command.
//
namespace {
/// CommandID - This enum defines all of the commands that the child process
/// can respond to. The actual expected data and responses are defined as the
/// enum values are defined.
///
enum CommandID {
//===------------------------------------------------------------------===//
// Execution commands - These are sent to the child to from the debugger to
// get it to do certain things.
//
// StepProgram: void->char - This command causes the program to continue
// execution, but stop as soon as it reaches another stoppoint.
StepProgram,
// FinishProgram: FrameDesc*->char - This command causes the program to
// continue execution until the specified function frame returns.
FinishProgram,
// ContProgram: void->char - This command causes the program to continue
// execution, stopping at some point in the future.
ContProgram,
// GetSubprogramDescriptor: FrameDesc*->GlobalValue* - This command returns
// the GlobalValue* descriptor object for the specified stack frame.
GetSubprogramDescriptor,
// GetParentFrame: FrameDesc*->FrameDesc* - This command returns the frame
// descriptor for the parent stack frame to the specified one, or null if
// there is none.
GetParentFrame,
// GetFrameLocation - FrameDesc*->LocationToken - This command returns the
// location that a particular stack frame is stopped at.
GetFrameLocation,
// AddBreakpoint - LocationToken->unsigned - This command instructs the
// target to install a breakpoint at the specified location.
AddBreakpoint,
// RemoveBreakpoint - unsigned->void - This command instructs the target to
// remove a breakpoint.
RemoveBreakpoint,
};
}
//===----------------------------------------------------------------------===//
// Parent Process Code
//===----------------------------------------------------------------------===//
namespace {
class IP : public InferiorProcess {
// ReadFD, WriteFD - The file descriptors to read/write to the inferior
// process.
FDHandle ReadFD, WriteFD;
// ChildPID - The unix PID of the child process we forked.
mutable pid_t ChildPID;
public:
IP(Module *M, const std::vector<std::string> &Arguments,
const char * const *envp);
~IP();
std::string getStatus() const;
/// Execution method implementations...
virtual void stepProgram();
virtual void finishProgram(void *Frame);
virtual void contProgram();
// Stack frame method implementations...
virtual void *getPreviousFrame(void *Frame) const;
virtual const GlobalVariable *getSubprogramDesc(void *Frame) const;
virtual void getFrameLocation(void *Frame, unsigned &LineNo,
unsigned &ColNo,
const GlobalVariable *&SourceDesc) const;
// Breakpoint implementation methods
virtual unsigned addBreakpoint(unsigned LineNo, unsigned ColNo,
const GlobalVariable *SourceDesc);
virtual void removeBreakpoint(unsigned ID);
private:
/// startChild - This starts up the child process, and initializes the
/// ChildPID member.
///
void startChild(Module *M, const std::vector<std::string> &Arguments,
const char * const *envp);
/// killChild - Kill or reap the child process. This throws the
/// InferiorProcessDead exception an exit code if the process had already
/// died, otherwise it just kills it and returns.
void killChild() const;
private:
// Methods for communicating with the child process. If the child exits or
// dies while attempting to communicate with it, ChildPID is set to zero and
// an exception is thrown.
/// readFromChild - Low-level primitive to read some data from the child,
/// throwing an exception if it dies.
void readFromChild(void *Buffer, unsigned Size) const;
/// writeToChild - Low-level primitive to send some data to the child
/// process, throwing an exception if the child died.
void writeToChild(void *Buffer, unsigned Size) const;
/// sendCommand - Send a command token and the request data to the child.
///
void sendCommand(CommandID Command, void *Data, unsigned Size) const;
/// waitForStop - This method waits for the child process to reach a stop
/// point.
void waitForStop();
};
}
// create - This is the factory method for the InferiorProcess class. Since
// there is currently only one subclass of InferiorProcess, we just define it
// here.
InferiorProcess *
InferiorProcess::create(Module *M, const std::vector<std::string> &Arguments,
const char * const *envp) {
return new IP(M, Arguments, envp);
}
/// IP constructor - Create some pipes, them fork a child process. The child
/// process should start execution of the debugged program, but stop at the
/// first available opportunity.
IP::IP(Module *M, const std::vector<std::string> &Arguments,
const char * const *envp)
: InferiorProcess(M) {
// Start the child running...
startChild(M, Arguments, envp);
// Okay, we created the program and it is off and running. Wait for it to
// stop now.
try {
waitForStop();
} catch (InferiorProcessDead &IPD) {
throw "Error waiting for the child process to stop. "
"It exited with status " + itostr(IPD.getExitCode());
}
}
IP::~IP() {
// If the child is still running, kill it.
if (!ChildPID) return;
killChild();
}
/// getStatus - Return information about the unix process being debugged.
///
std::string IP::getStatus() const {
if (ChildPID == 0)
return "Unix target. ERROR: child process appears to be dead!\n";
return "Unix target: PID #" + utostr((unsigned)ChildPID) + "\n";
}
/// startChild - This starts up the child process, and initializes the
/// ChildPID member.
///
void IP::startChild(Module *M, const std::vector<std::string> &Arguments,
const char * const *envp) {
// Create the pipes. Make sure to immediately assign the returned file
// descriptors to FDHandle's so they get destroyed if an exception is thrown.
int FDs[2];
if (pipe(FDs)) throw "Error creating a pipe!";
FDHandle ChildReadFD(FDs[0]);
WriteFD = FDs[1];
if (pipe(FDs)) throw "Error creating a pipe!";
ReadFD = FDs[0];
FDHandle ChildWriteFD(FDs[1]);
// Fork off the child process.
switch (ChildPID = fork()) {
case -1: throw "Error forking child process!";
case 0: // child
delete this; // Free parent pipe file descriptors
runChild(M, Arguments, envp, ChildReadFD, ChildWriteFD);
exit(1);
default: break;
}
}
/// sendCommand - Send a command token and the request data to the child.
///
void IP::sendCommand(CommandID Command, void *Data, unsigned Size) const {
writeToChild(&Command, sizeof(Command));
writeToChild(Data, Size);
}
/// stepProgram - Implement the 'step' command, continuing execution until
/// the next possible stop point.
void IP::stepProgram() {
sendCommand(StepProgram, 0, 0);
waitForStop();
}
/// finishProgram - Implement the 'finish' command, executing the program until
/// the current function returns to its caller.
void IP::finishProgram(void *Frame) {
sendCommand(FinishProgram, &Frame, sizeof(Frame));
waitForStop();
}
/// contProgram - Implement the 'cont' command, continuing execution until
/// a breakpoint is encountered.
void IP::contProgram() {
sendCommand(ContProgram, 0, 0);
waitForStop();
}
//===----------------------------------------------------------------------===//
// Stack manipulation methods
//
/// getPreviousFrame - Given the descriptor for the current stack frame,
/// return the descriptor for the caller frame. This returns null when it
/// runs out of frames.
void *IP::getPreviousFrame(void *Frame) const {
sendCommand(GetParentFrame, &Frame, sizeof(Frame));
readFromChild(&Frame, sizeof(Frame));
return Frame;
}
/// getSubprogramDesc - Return the subprogram descriptor for the current
/// stack frame.
const GlobalVariable *IP::getSubprogramDesc(void *Frame) const {
sendCommand(GetSubprogramDescriptor, &Frame, sizeof(Frame));
const GlobalVariable *Desc;
readFromChild(&Desc, sizeof(Desc));
return Desc;
}
/// getFrameLocation - This method returns the source location where each stack
/// frame is stopped.
void IP::getFrameLocation(void *Frame, unsigned &LineNo, unsigned &ColNo,
const GlobalVariable *&SourceDesc) const {
sendCommand(GetFrameLocation, &Frame, sizeof(Frame));
LocationToken Loc;
readFromChild(&Loc, sizeof(Loc));
LineNo = Loc.Line;
ColNo = Loc.Col;
SourceDesc = Loc.File;
}
//===----------------------------------------------------------------------===//
// Breakpoint manipulation methods
//
unsigned IP::addBreakpoint(unsigned LineNo, unsigned ColNo,
const GlobalVariable *SourceDesc) {
LocationToken Loc;
Loc.Line = LineNo;
Loc.Col = ColNo;
Loc.File = SourceDesc;
sendCommand(AddBreakpoint, &Loc, sizeof(Loc));
unsigned ID;
readFromChild(&ID, sizeof(ID));
return ID;
}
void IP::removeBreakpoint(unsigned ID) {
sendCommand(RemoveBreakpoint, &ID, sizeof(ID));
}
//===----------------------------------------------------------------------===//
// Methods for communication with the child process
//
// Methods for communicating with the child process. If the child exits or dies
// while attempting to communicate with it, ChildPID is set to zero and an
// exception is thrown.
//
/// readFromChild - Low-level primitive to read some data from the child,
/// throwing an exception if it dies.
void IP::readFromChild(void *Buffer, unsigned Size) const {
assert(ChildPID &&
"Child process died and still attempting to communicate with it!");
while (Size) {
ssize_t Amount = read(ReadFD, Buffer, Size);
if (Amount == 0) {
// If we cannot communicate with the process, kill it.
killChild();
// If killChild succeeded, then the process must have closed the pipe FD
// or something, because the child existed, but we cannot communicate with
// it.
throw InferiorProcessDead(-1);
} else if (Amount == -1) {
if (errno != EINTR) {
ChildPID = 0;
killChild();
throw "Error reading from child process!";
}
} else {
// We read a chunk.
Buffer = (char*)Buffer + Amount;
Size -= Amount;
}
}
}
/// writeToChild - Low-level primitive to send some data to the child
/// process, throwing an exception if the child died.
void IP::writeToChild(void *Buffer, unsigned Size) const {
while (Size) {
ssize_t Amount = write(WriteFD, Buffer, Size);
if (Amount < 0 && errno == EINTR) continue;
if (Amount <= 0) {
// If we cannot communicate with the process, kill it.
killChild();
// If killChild succeeded, then the process must have closed the pipe FD
// or something, because the child existed, but we cannot communicate with
// it.
throw InferiorProcessDead(-1);
} else {
// We wrote a chunk.
Buffer = (char*)Buffer + Amount;
Size -= Amount;
}
}
}
/// killChild - Kill or reap the child process. This throws the
/// InferiorProcessDead exception an exit code if the process had already
/// died, otherwise it just returns the exit code if it had to be killed.
void IP::killChild() const {
assert(ChildPID != 0 && "Child has already been reaped!");
// If the process terminated on its own accord, closing the pipe file
// descriptors, we will get here. Check to see if the process has already
// died in this manner, gracefully.
int Status = 0;
int PID;
do {
PID = waitpid(ChildPID, &Status, WNOHANG);
} while (PID < 0 && errno == EINTR);
if (PID < 0) throw "Error waiting for child to exit!";
// Ok, there is a slight race condition here. It's possible that we will find
// out that the file descriptor closed before waitpid will indicate that the
// process gracefully died. If we don't know that the process gracefully
// died, wait a bit and try again. This is pretty nasty.
if (PID == 0) {
usleep(10000); // Wait a bit.
// Try again.
Status = 0;
do {
PID = waitpid(ChildPID, &Status, WNOHANG);
} while (PID < 0 && errno == EINTR);
if (PID < 0) throw "Error waiting for child to exit!";
}
// If the child process was already dead, then indicate that the process
// terminated on its own.
if (PID) {
assert(PID == ChildPID && "Didn't reap child?");
ChildPID = 0; // Child has been reaped
if (WIFEXITED(Status))
throw InferiorProcessDead(WEXITSTATUS(Status));
else if (WIFSIGNALED(Status))
throw InferiorProcessDead(WTERMSIG(Status));
throw InferiorProcessDead(-1);
}
// Otherwise, the child exists and has not yet been killed.
if (kill(ChildPID, SIGKILL) < 0)
throw "Error killing child process!";
do {
PID = waitpid(ChildPID, 0, 0);
} while (PID < 0 && errno == EINTR);
if (PID <= 0) throw "Error waiting for child to exit!";
assert(PID == ChildPID && "Didn't reap child?");
}
/// waitForStop - This method waits for the child process to reach a stop
/// point. When it does, it fills in the CurLocation member and returns.
void IP::waitForStop() {
char Dummy;
readFromChild(&Dummy, sizeof(char));
}
//===----------------------------------------------------------------------===//
// Child Process Code
//===----------------------------------------------------------------------===//
namespace {
class SourceSubprogram;
/// SourceRegion - Instances of this class represent the regions that are
/// active in the program.
class SourceRegion {
/// Parent - A pointer to the region that encloses the current one.
SourceRegion *Parent;
/// CurSubprogram - The subprogram that contains this region. This allows
/// efficient stack traversals.
SourceSubprogram *CurSubprogram;
/// CurLine, CurCol, CurFile - The last location visited by this region.
/// This is used for getting the source location of callers in stack frames.
unsigned CurLine, CurCol;
void *CurFileDesc;
//std::vector<void*> ActiveObjects;
public:
SourceRegion(SourceRegion *p, SourceSubprogram *Subprogram = 0)
: Parent(p), CurSubprogram(Subprogram ? Subprogram : p->getSubprogram()) {
CurLine = 0; CurCol = 0;
CurFileDesc = 0;
}
virtual ~SourceRegion() {}
SourceRegion *getParent() const { return Parent; }
SourceSubprogram *getSubprogram() const { return CurSubprogram; }
void updateLocation(unsigned Line, unsigned Col, void *File) {
CurLine = Line;
CurCol = Col;
CurFileDesc = File;
}
/// Return a LocationToken for the place that this stack frame stopped or
/// called a sub-function.
LocationToken getLocation(ExecutionEngine *EE) {
LocationToken LT;
LT.Line = CurLine;
LT.Col = CurCol;
const GlobalValue *GV = EE->getGlobalValueAtAddress(CurFileDesc);
LT.File = dyn_cast_or_null<GlobalVariable>(GV);
return LT;
}
};
/// SourceSubprogram - This is a stack-frame that represents a source program.
///
class SourceSubprogram : public SourceRegion {
/// Desc - A pointer to the descriptor for the subprogram that this frame
/// represents.
void *Desc;
public:
SourceSubprogram(SourceRegion *P, void *desc)
: SourceRegion(P, this), Desc(desc) {}
void *getDescriptor() const { return Desc; }
};
/// Child class - This class contains all of the information and methods used
/// by the child side of the debugger. The single instance of this object is
/// pointed to by the "TheChild" global variable.
class Child {
/// M - The module for the program currently being debugged.
///
Module *M;
/// EE - The execution engine that we are using to run the program.
///
ExecutionEngine *EE;
/// ReadFD, WriteFD - The file descriptor handles for this side of the
/// debugger pipe.
FDHandle ReadFD, WriteFD;
/// RegionStack - A linked list of all of the regions dynamically active.
///
SourceRegion *RegionStack;
/// StopAtNextOpportunity - If this flag is set, the child process will stop
/// and report to the debugger at the next possible chance it gets.
volatile bool StopAtNextOpportunity;
/// StopWhenSubprogramReturns - If this is non-null, the debugger requests
/// that the program stops when the specified function frame is destroyed.
SourceSubprogram *StopWhenSubprogramReturns;
/// Breakpoints - This contains a list of active breakpoints and their IDs.
///
std::vector<std::pair<unsigned, LocationToken> > Breakpoints;
/// CurBreakpoint - The last assigned breakpoint.
///
unsigned CurBreakpoint;
public:
Child(Module *m, ExecutionEngine *ee, FDHandle &Read, FDHandle &Write)
: M(m), EE(ee), ReadFD(Read), WriteFD(Write),
RegionStack(0), CurBreakpoint(0) {
StopAtNextOpportunity = true;
StopWhenSubprogramReturns = 0;
}
/// writeToParent - Send the specified buffer of data to the debugger
/// process.
///
void writeToParent(const void *Buffer, unsigned Size);
/// readFromParent - Read the specified number of bytes from the parent.
///
void readFromParent(void *Buffer, unsigned Size);
/// childStopped - This method is called whenever the child has stopped
/// execution due to a breakpoint, step command, interruption, or whatever.
/// This stops the process, responds to any requests from the debugger, and
/// when commanded to, can continue execution by returning.
///
void childStopped();
/// startSubprogram - This method creates a new region for the subroutine
/// with the specified descriptor.
///
void startSubprogram(void *FuncDesc);
/// startRegion - This method initiates the creation of an anonymous region.
///
void startRegion();
/// endRegion - This method terminates the last active region.
///
void endRegion();
/// reachedLine - This method is automatically called by the program every
/// time it executes an llvm.dbg.stoppoint intrinsic. If the debugger wants
/// us to stop here, we do so, otherwise we continue execution.
///
void reachedLine(unsigned Line, unsigned Col, void *SourceDesc);
};
/// TheChild - The single instance of the Child class, which only gets created
/// in the child process.
Child *TheChild = 0;
} // end anonymous namespace
// writeToParent - Send the specified buffer of data to the debugger process.
void Child::writeToParent(const void *Buffer, unsigned Size) {
while (Size) {
ssize_t Amount = write(WriteFD, Buffer, Size);
if (Amount < 0 && errno == EINTR) continue;
if (Amount <= 0) {
write(2, "ERROR: Connection to debugger lost!\n", 36);
abort();
} else {
// We wrote a chunk.
Buffer = (const char*)Buffer + Amount;
Size -= Amount;
}
}
}
// readFromParent - Read the specified number of bytes from the parent.
void Child::readFromParent(void *Buffer, unsigned Size) {
while (Size) {
ssize_t Amount = read(ReadFD, Buffer, Size);
if (Amount < 0 && errno == EINTR) continue;
if (Amount <= 0) {
write(2, "ERROR: Connection to debugger lost!\n", 36);
abort();
} else {
// We read a chunk.
Buffer = (char*)Buffer + Amount;
Size -= Amount;
}
}
}
/// childStopped - This method is called whenever the child has stopped
/// execution due to a breakpoint, step command, interruption, or whatever.
/// This stops the process, responds to any requests from the debugger, and when
/// commanded to, can continue execution by returning.
///
void Child::childStopped() {
// Since we stopped, notify the parent that we did so.
char Token = 0;
writeToParent(&Token, sizeof(char));
StopAtNextOpportunity = false;
StopWhenSubprogramReturns = 0;
// Now that the debugger knows that we stopped, read commands from it and
// respond to them appropriately.
CommandID Command;
while (1) {
SourceRegion *Frame;
const void *Result;
readFromParent(&Command, sizeof(CommandID));
switch (Command) {
case StepProgram:
// To step the program, just return.
StopAtNextOpportunity = true;
return;
case FinishProgram: // Run until exit from the specified function...
readFromParent(&Frame, sizeof(Frame));
// The user wants us to stop when the specified FUNCTION exits, not when
// the specified REGION exits.
StopWhenSubprogramReturns = Frame->getSubprogram();
return;
case ContProgram:
// To continue, just return back to execution.
return;
case GetSubprogramDescriptor:
readFromParent(&Frame, sizeof(Frame));
Result =
EE->getGlobalValueAtAddress(Frame->getSubprogram()->getDescriptor());
writeToParent(&Result, sizeof(Result));
break;
case GetParentFrame:
readFromParent(&Frame, sizeof(Frame));
Result = Frame ? Frame->getSubprogram()->getParent() : RegionStack;
writeToParent(&Result, sizeof(Result));
break;
case GetFrameLocation: {
readFromParent(&Frame, sizeof(Frame));
LocationToken LT = Frame->getLocation(EE);
writeToParent(&LT, sizeof(LT));
break;
}
case AddBreakpoint: {
LocationToken Loc;
readFromParent(&Loc, sizeof(Loc));
// Convert the GlobalVariable pointer to the address it was emitted to.
Loc.File = (GlobalVariable*)EE->getPointerToGlobal(Loc.File);
unsigned ID = CurBreakpoint++;
Breakpoints.push_back(std::make_pair(ID, Loc));
writeToParent(&ID, sizeof(ID));
break;
}
case RemoveBreakpoint: {
unsigned ID = 0;
readFromParent(&ID, sizeof(ID));
for (unsigned i = 0, e = Breakpoints.size(); i != e; ++i)
if (Breakpoints[i].first == ID) {
Breakpoints.erase(Breakpoints.begin()+i);
break;
}
break;
}
default:
assert(0 && "Unknown command!");
}
}
}
/// startSubprogram - This method creates a new region for the subroutine
/// with the specified descriptor.
void Child::startSubprogram(void *SPDesc) {
RegionStack = new SourceSubprogram(RegionStack, SPDesc);
}
/// startRegion - This method initiates the creation of an anonymous region.
///
void Child::startRegion() {
RegionStack = new SourceRegion(RegionStack);
}
/// endRegion - This method terminates the last active region.
///
void Child::endRegion() {
SourceRegion *R = RegionStack->getParent();
// If the debugger wants us to stop when this frame is destroyed, do so.
if (RegionStack == StopWhenSubprogramReturns) {
StopAtNextOpportunity = true;
StopWhenSubprogramReturns = 0;
}
delete RegionStack;
RegionStack = R;
}
/// reachedLine - This method is automatically called by the program every time
/// it executes an llvm.dbg.stoppoint intrinsic. If the debugger wants us to
/// stop here, we do so, otherwise we continue execution. Note that the Data
/// pointer coming in is a pointer to the LLVM global variable that represents
/// the source file we are in. We do not use the contents of the global
/// directly in the child, but we do use its address.
///
void Child::reachedLine(unsigned Line, unsigned Col, void *SourceDesc) {
if (RegionStack)
RegionStack->updateLocation(Line, Col, SourceDesc);
// If we hit a breakpoint, stop the program.
for (unsigned i = 0, e = Breakpoints.size(); i != e; ++i)
if (Line == Breakpoints[i].second.Line &&
SourceDesc == (void*)Breakpoints[i].second.File &&
Col == Breakpoints[i].second.Col) {
childStopped();
return;
}
// If we are single stepping the program, make sure to stop it.
if (StopAtNextOpportunity)
childStopped();
}
//===----------------------------------------------------------------------===//
// Child class wrapper functions
//
// These functions are invoked directly by the program as it executes, in place
// of the debugging intrinsic functions that it contains.
//
/// llvm_debugger_stop - Every time the program reaches a new source line, it
/// will call back to this function. If the debugger has a breakpoint or
/// otherwise wants us to stop on this line, we do so, and notify the debugger
/// over the pipe.
///
extern "C"
void *llvm_debugger_stop(void *Dummy, unsigned Line, unsigned Col,
void *SourceDescriptor) {
TheChild->reachedLine(Line, Col, SourceDescriptor);
return Dummy;
}
/// llvm_dbg_region_start - This function is invoked every time an anonymous
/// region of the source program is entered.
///
extern "C"
void *llvm_dbg_region_start(void *Dummy) {
TheChild->startRegion();
return Dummy;
}
/// llvm_dbg_subprogram - This function is invoked every time a source-language
/// subprogram has been entered.
///
extern "C"
void *llvm_dbg_subprogram(void *FuncDesc) {
TheChild->startSubprogram(FuncDesc);
return 0;
}
/// llvm_dbg_region_end - This function is invoked every time a source-language
/// region (started with llvm.dbg.region.start or llvm.dbg.func.start) is
/// terminated.
///
extern "C"
void llvm_dbg_region_end(void *Dummy) {
TheChild->endRegion();
}
namespace {
/// DebuggerIntrinsicLowering - This class implements a simple intrinsic
/// lowering class that revectors debugging intrinsics to call actual
/// functions (defined above), instead of being turned into noops.
struct DebuggerIntrinsicLowering : public DefaultIntrinsicLowering {
DebuggerIntrinsicLowering() { ShouldEmitDebugFunctions = true; }
virtual void LowerIntrinsicCall(CallInst *CI) {
Module *M = CI->getParent()->getParent()->getParent();
switch (CI->getCalledFunction()->getIntrinsicID()) {
case Intrinsic::dbg_stoppoint:
// Turn call into a call to llvm_debugger_stop
CI->setOperand(0, M->getOrInsertFunction("llvm_debugger_stop",
CI->getCalledFunction()->getFunctionType()));
break;
case Intrinsic::dbg_region_start:
// Turn call into a call to llvm_dbg_region_start
CI->setOperand(0, M->getOrInsertFunction("llvm_dbg_region_start",
CI->getCalledFunction()->getFunctionType()));
break;
case Intrinsic::dbg_region_end:
// Turn call into a call to llvm_dbg_region_end
CI->setOperand(0, M->getOrInsertFunction("llvm_dbg_region_end",
CI->getCalledFunction()->getFunctionType()));
break;
case Intrinsic::dbg_func_start:
// Turn call into a call to llvm_dbg_subprogram
CI->setOperand(0, M->getOrInsertFunction("llvm_dbg_subprogram",
CI->getCalledFunction()->getFunctionType()));
break;
default:
DefaultIntrinsicLowering::LowerIntrinsicCall(CI);
break;
}
}
};
} // end anonymous namespace
static void runChild(Module *M, const std::vector<std::string> &Arguments,
const char * const *envp,
FDHandle ReadFD, FDHandle WriteFD) {
// Create an execution engine that uses our custom intrinsic lowering object
// to revector debugging intrinsic functions into actual functions defined
// above.
ExecutionEngine *EE =
ExecutionEngine::create(new ExistingModuleProvider(M), false,
new DebuggerIntrinsicLowering());
assert(EE && "Couldn't create an ExecutionEngine, not even an interpreter?");
// Call the main function from M as if its signature were:
// int main (int argc, char **argv, const char **envp)
// using the contents of Args to determine argc & argv, and the contents of
// EnvVars to determine envp.
//
Function *Fn = M->getMainFunction();
if (!Fn) exit(1);
// Create the child class instance which will be used by the debugger
// callbacks to keep track of the current state of the process.
assert(TheChild == 0 && "A child process has already been created??");
TheChild = new Child(M, EE, ReadFD, WriteFD);
// Run main...
int Result = EE->runFunctionAsMain(Fn, Arguments, envp);
// If the program didn't explicitly call exit, call exit now, for the program.
// This ensures that any atexit handlers get called correctly.
Function *Exit = M->getOrInsertFunction("exit", Type::VoidTy, Type::IntTy,
(Type *)0);
std::vector<GenericValue> Args;
GenericValue ResultGV;
ResultGV.IntVal = Result;
Args.push_back(ResultGV);
EE->runFunction(Exit, Args);
abort();
}