Dart LLDB JIT Debug Plugin

This plugin enables debugging of JIT-compiled Dart code using LLDB. It integrates with Dart's internal JIT system to provide source-level debugging for dynamically generated code.

Building

Prerequisites

• CMake 3.10+
• LLDB development libraries
• C++ compiler with C++17 support

Linux

# Install LLVM/LLDB development packages
echo "deb http://apt.llvm.org/$(lsb_release -cs)/ llvm-toolchain-$(lsb_release -cs)-19 main" | sudo tee /etc/apt/sources.list.d/llvm.list
wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
sudo apt-get update
sudo apt-get install -y llvm-19-dev liblldb-19-dev python3-lldb-19

sudo apt-get install lldb-19
cd /usr/bin
sudo ln -S ./lldb ../lib/llvm-19/bin/lldb

MacOS

Download LLVM package with brew:

$ brew install llvm@19
$ pip install pyyaml

Build lldb from source, since there is no package available.

$ wget https://github.com/llvm/llvm-project/archive/refs/tags/llvmorg-19.1.7.zip
$ unzip llvmorg-19.1.7.zip
$ cd llvm-project-llvmorg-19.1.7/ && mkdir build_lldb && cd build_lldb
$ cmake ../llvm -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;lldb" -DLLVM_ENABLE_ASSERTIONS=ON -DLLDB_INCLUDE_TESTS=OFF -DLLDB_ENABLE_PYTHON=1 -GNinja
$ ninja

Build steps

Linux

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -GNinja ..
ninja

MacOS (a bit more complex ATM - will simplify this)

$ cmake -GNinja .. -DLLVM_DIR=/opt/homebrew/opt/llvm@19/lib/cmake/llvm -DLLVM_BUILD_ROOT=/path/to/llvm-project-llvmorg-19.1.7/build_lldb -DLLVM_SRC=/path/to/llvm-project-llvmorg-19.1.7/ -DLLVM_TABLEGEN_EXE=/opt/homebrew/opt/llvm@19/bin/llvm-tblgen -DCMAKE_CXX_FLAGS="-Wno-deprecated-declarations"

Installation (optional)

sudo ninja install

This will install the plugin to /usr/local/lib and the dart-lldb script to /usr/local/bin.

Usage

Local

$ dart-lldb --pending-breakpoints 'RunningIsolates.isolateShutdown;RemovingTransformer.transformNamedExpressionList;InterfaceType.get_hasNonObjectMemberAccess' ./out/DebugX64/dart --gdb-jit-interface basic.dart

Remote (Still experimental)

1. Start Dart under QEMU with gdbserver mode:

qemu-arm -g 1234 -L /path/to/sysroot /path/to/dart --gdb-jit-interface your_script.dart

2. In another terminal, connect using dart-lldb:

 dart-lldb --remote localhost:1234 --sysroot /path/to/sysroot /path/to/dart

Commands

Once the plugin is loaded, you can use these commands:

• dart-jit-setup - Initialize JIT debugging for the current target
• dart-jit list - List all JIT-compiled functions
• dart-jit break <function-name> - Set a breakpoint in a JIT-compiled function
• dart-jit add <address> <size> <name> [file] - Manually register a JIT function (for testing)

Integration with Dart VM

This plugin works with Dart's JIT compiler. The Dart VM must be compiled with GDB JIT interface support and run with the --gdb-jit-interface flag https://github.com/syrmia/dart-sdk/tree/feature/gdb-jit-interface.