|author||Pavel Labath <email@example.com>||Thu Nov 11 19:54:39 2021 +0100|
|committer||Pavel Labath <firstname.lastname@example.org>||Tue Nov 30 14:16:08 2021 +0100|
[lldb] Introduce PlatformQemuUser This adds a new platform class, whose job is to enable running (debugging) executables under qemu. (For general information about qemu, I recommend reading the RFC thread on lldb-dev <https://lists.llvm.org/pipermail/lldb-dev/2021-October/017106.html>.) This initial patch implements the necessary boilerplate as well as the minimal amount of functionality needed to actually be able to do something useful (which, in this case means debugging a fully statically linked executable). The knobs necessary to emulate dynamically linked programs, as well as to control other aspects of qemu operation (the emulated cpu, for instance) will be added in subsequent patches. Same goes for the ability to automatically bind to the executables of the emulated architecture. Currently only two settings are available: - architecture: the architecture that we should emulate - emulator-path: the path to the emulator Even though this patch is relatively small, it doesn't lack subtleties that are worth calling out explicitly: - named sockets: qemu supports tcp and unix socket connections, both of them in the "forward connect" mode (qemu listening, lldb connecting). Forward TCP connections are impossible to realise in a race-free way. This is the reason why I chose unix sockets as they have larger, more structured names, which can guarantee that there are no collisions between concurrent connection attempts. - the above means that this code will not work on windows. I don't think that's an issue since user mode qemu does not support windows anyway. - Right now, I am leaving the code enabled for windows, but maybe it would be better to disable it (otoh, disabling it means windows developers can't check they don't break it) - qemu-user also does not support macOS, so one could contemplate disabling it there too. However, macOS does support named sockets, so one can even run the (mock) qemu tests there, and I think it'd be a shame to lose that. Differential Revision: https://reviews.llvm.org/D114509
This directory and its sub-directories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.
The README briefly describes how to get started with building LLVM. For more information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.
Taken from https://llvm.org/docs/GettingStarted.html.
Welcome to the LLVM project!
The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer. It also contains basic regression tests.
C-like languages use the Clang front end. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.
Other components include: the libc++ C++ standard library, the LLD linker, and more.
The LLVM Getting Started documentation may be out of date. The Clang Getting Started page might have more accurate information.
This is an example work-flow and configuration to get and build the LLVM source:
Checkout LLVM (including related sub-projects like Clang):
git clone https://github.com/llvm/llvm-project.git
Or, on windows,
git clone --config core.autocrlf=false https://github.com/llvm/llvm-project.git
Configure and build LLVM and Clang:
cmake -S llvm -B build -G <generator> [options]
Some common build system generators are:
Ninja--- for generating Ninja build files. Most llvm developers use Ninja.
Unix Makefiles--- for generating make-compatible parallel makefiles.
Visual Studio--- for generating Visual Studio projects and solutions.
Xcode--- for generating Xcode projects.
Some common options:
-DLLVM_ENABLE_PROJECTS='...' --- semicolon-separated list of the LLVM sub-projects you'd like to additionally build. Can include any of: clang, clang-tools-extra, compiler-rt,cross-project-tests, flang, libc, libclc, libcxx, libcxxabi, libunwind, lld, lldb, mlir, openmp, polly, or pstl.
For example, to build LLVM, Clang, libcxx, and libcxxabi, use
-DCMAKE_INSTALL_PREFIX=directory --- Specify for directory the full path name of where you want the LLVM tools and libraries to be installed (default
-DCMAKE_BUILD_TYPE=type --- Valid options for type are Debug, Release, RelWithDebInfo, and MinSizeRel. Default is Debug.
-DLLVM_ENABLE_ASSERTIONS=On --- Compile with assertion checks enabled (default is Yes for Debug builds, No for all other build types).
cmake --build build [-- [options] <target>] or your build system specified above directly.
The default target (i.e.
make) will build all of LLVM.
check-all target (i.e.
ninja check-all) will run the regression tests to ensure everything is in working order.
CMake will generate targets for each tool and library, and most LLVM sub-projects generate their own
Running a serial build will be slow. To improve speed, try running a parallel build. That's done by default in Ninja; for
make, use the option
-j NNN, where
NNN is the number of parallel jobs, e.g. the number of CPUs you have.
For more information see CMake
Consult the Getting Started with LLVM page for detailed information on configuring and compiling LLVM. You can visit Directory Layout to learn about the layout of the source code tree.