Whole Program LLVM in Rust (rllvm)

rllvm is a Rust port of gllvm and provides compiler wrappers to build whole-program LLVM bitcode files for projects with source codes.

For more details, please refer to gllvm or wllvm.

Installation

cargo install rllvm

Get Started

# Compile the source file. `--` is needed. Arguments after it will be
# passed to the wrapped compiler
rllvm-cxx -- -o hello tests/data/hello.cc

# Extract the bitcode file `hello.bc`
rllvm-get-bc hello

# Obtain readable `hello.ll` file
llvm-dis hello.bc

Configuration

Users can specify the configuration file by setting the environment variable RLLVM_CONFIG.

export RLLVM_CONFIG=/absolute/path/to/config/file.toml

Otherwise, the default configuration file ~/.rllvm/config.toml will be used. The configuration file will be automatically created, if it does not exist, with the following entries:

Configuration Key	Required?	Notes
llvm_config_filepath	Yes	The absolute filepath of llvm-config
clang_filepath	Yes	The absolute filepath of clang
clangxx_filepath	Yes	The absolute filepath of clang++
llvm_ar_filepath	Yes	The absolute filepath of llvm-ar
llvm_link_filepath	Yes	The absolute filepath of llvm-link
llvm_objcopy_filepath	Yes	The absolute filepath of llvm-objcopy
bitcode_store_path	No	The absolute path of the directory that stores intermediate bitcode files
llvm_link_flags	No	Extra user-provided linking flags for llvm-link
lto_ldflags	No	Extra user-provided linking flags for link time optimization
bitcode_generation_flags	No	Extra user-provided flags for bitcode generation, e.g., "-flto -fwhole-program-vtables"
is_configure_only	No	The configure only mode, which skips the bitcode generation (Default: false)
log_level	No	Log level (0: nothing, 1: error, 2: warn, 3: info, 4: debug, 5: trace)

Here is an example of the configuration file:

llvm_config_filepath = '/usr/local/Cellar/llvm/16.0.4/bin/llvm-config'
clang_filepath = '/usr/local/Cellar/llvm/16.0.4/bin/clang'
clangxx_filepath = '/usr/local/Cellar/llvm/16.0.4/bin/clang++'
llvm_ar_filepath = '/usr/local/Cellar/llvm/16.0.4/bin/llvm-ar'
llvm_link_filepath = '/usr/local/Cellar/llvm/16.0.4/bin/llvm-link'
llvm_objcopy_filepath = '/usr/local/Cellar/llvm/16.0.4/bin/llvm-objcopy'
bitcode_store_path = '/tmp/bitcode_store'
log_level = 3

Furthermore, we can override configurations by providing extra arguments before --. Currently, we only support override the compiler path and the log level, which is useful to sepcify relative paths while working with Bazel.

# Override the wrapped compiler path and show all logs
rllvm-cxx -c /path/to/compiler -vvvvv -- -o hello tests/data/hello.cc