llvm/llvm/examples/OrcV2Examples/LLJITWithRemoteDebugging/LLJITWithRemoteDebugging.cpp

//===--- LLJITWithRemoteDebugging.cpp - LLJIT targeting a child process ---===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This example shows how to use LLJIT and JITLink for out-of-process execution
// with debug support.  A few notes beforehand:
//
//  * Debuggers must implement the GDB JIT interface (gdb, udb, lldb 12+).
//  * Debug support is currently limited to ELF on x86-64 platforms that run
//    Unix-like systems.
//  * There is a test for this example and it ships an IR file that is prepared
//    for the instructions below.
//
//
// The following command line session provides a complete walkthrough of the
// feature using LLDB 12:
//
// [Terminal 1] Prepare a debuggable out-of-process JIT session:
//
//    > cd llvm-project/build
//    > ninja LLJITWithRemoteDebugging llvm-jitlink-executor
//    > cp ../llvm/test/Examples/OrcV2Examples/Inputs/argc_sub1_elf.ll .
//    > bin/LLJITWithRemoteDebugging --wait-for-debugger argc_sub1_elf.ll
//    Found out-of-process executor: bin/llvm-jitlink-executor
//    Launched executor in subprocess: 65535
//    Attach a debugger and press any key to continue.
//
//
// [Terminal 2] Attach a debugger to the child process:
//
//    (lldb) log enable lldb jit
//    (lldb) settings set plugin.jit-loader.gdb.enable on
//    (lldb) settings set target.source-map Inputs/ \
//             /path/to/llvm-project/llvm/test/Examples/OrcV2Examples/Inputs/
//    (lldb) attach -p 65535
//     JITLoaderGDB::SetJITBreakpoint looking for JIT register hook
//     JITLoaderGDB::SetJITBreakpoint setting JIT breakpoint
//    Process 65535 stopped
//    (lldb) b sub1
//    Breakpoint 1: no locations (pending).
//    WARNING:  Unable to resolve breakpoint to any actual locations.
//    (lldb) c
//    Process 65535 resuming
//
//
// [Terminal 1] Press a key to start code generation and execution:
//
//    Parsed input IR code from: argc_sub1_elf.ll
//    Initialized LLJIT for remote executor
//    Running: argc_sub1_elf.ll
//
//
// [Terminal 2] Breakpoint hits; we change the argc value from 1 to 42:
//
//    (lldb)  JITLoaderGDB::JITDebugBreakpointHit hit JIT breakpoint
//     JITLoaderGDB::ReadJITDescriptorImpl registering JIT entry at 0x106b34000
//    1 location added to breakpoint 1
//    Process 65535 stopped
//    * thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
//        frame #0: JIT(0x106b34000)`sub1(x=1) at argc_sub1.c:1:28
//    -> 1   	int sub1(int x) { return x - 1; }
//       2   	int main(int argc, char **argv) { return sub1(argc); }
//    (lldb) p x
//    (int) $0 = 1
//    (lldb) expr x = 42
//    (int) $1 = 42
//    (lldb) c
//
//
// [Terminal 1] Example output reflects the modified value:
//
//    Exit code: 41
//
//===----------------------------------------------------------------------===//

#include "llvm/ExecutionEngine/Orc/Debugging/DebuggerSupport.h"
#include "llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h"
#include "llvm/ExecutionEngine/Orc/LLJIT.h"
#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
#include "llvm/ExecutionEngine/Orc/SimpleRemoteEPC.h"
#include "llvm/ExecutionEngine/Orc/ThreadSafeModule.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/TargetParser/Host.h"

#include "../ExampleModules.h"
#include "RemoteJITUtils.h"

#include <memory>
#include <string>

usingnamespacellvm;
usingnamespacellvm::orc;

// The LLVM IR file to run.
static cl::list<std::string> InputFiles(cl::Positional, cl::OneOrMore,
                                        cl::desc("<input files>"));

// Command line arguments to pass to the JITed main function.
static cl::list<std::string> InputArgv("args", cl::Positional,
                                       cl::desc("<program arguments>..."),
                                       cl::PositionalEatsArgs);

// Given paths must exist on the remote target.
static cl::list<std::string>
    Dylibs("dlopen", cl::desc("Dynamic libraries to load before linking"),
           cl::value_desc("filename"));

// File path of the executable to launch for execution in a child process.
// Inter-process communication will go through stdin/stdout pipes.
static cl::opt<std::string>
    OOPExecutor("executor", cl::desc("Set the out-of-process executor"),
                cl::value_desc("filename"));

// Network address of a running executor process that we can connect via TCP. It
// may run locally or on a remote machine.
static cl::opt<std::string> OOPExecutorConnectTCP(
    "connect",
    cl::desc("Connect to an out-of-process executor through a TCP socket"),
    cl::value_desc("<hostname>:<port>"));

// Give the user a chance to connect a debugger. Once we connected the executor
// process, wait for the user to press a key (and print out its PID if it's a
// child process).
static cl::opt<bool>
    WaitForDebugger("wait-for-debugger",
                    cl::desc("Wait for user input before entering JITed code"),
                    cl::init(false));

ExitOnError ExitOnErr;

int main(int argc, char *argv[]) { … }