mirror of
https://github.com/danog/gllvm.git
synced 2024-11-30 06:59:05 +01:00
97 lines
3.6 KiB
Markdown
97 lines
3.6 KiB
Markdown
# A Concurrent WLLVM in Go
|
|
|
|
[](https://travis-ci.org/SRI-CSL/gllvm)
|
|
[](https://goreportcard.com/report/github.com/SRI-CSL/gllvm)
|
|
|
|
**TL; DR:** A drop-in replacement for [wllvm](https://github.com/SRI-CSL/whole-program-llvm), that builds the
|
|
bitcode in parallel, and is faster.
|
|
|
|
|
|
## Overview
|
|
|
|
|
|
This project, `gllvm`, provides tools for building whole-program (or
|
|
whole-library) LLVM bitcode files from an unmodified C or C++
|
|
source package. It currently runs on `*nix` platforms such as Linux,
|
|
FreeBSD, and Mac OS X. It is a Go port of [wllvm](https://github.com/SRI-CSL/whole-program-llvm).
|
|
|
|
`gllvm` provides compiler wrappers that work in two
|
|
phases. The wrappers first invoke the compiler as normal. Then, for
|
|
each object file, they call a bitcode compiler to produce LLVM
|
|
bitcode. The wrappers then store the location of the generated bitcode
|
|
file in a dedicated section of the object file. When object files are
|
|
linked together, the contents of the dedicated sections are
|
|
concatenated (so we don't lose the locations of any of the constituent
|
|
bitcode files). After the build completes, one can use a `gllvm`
|
|
utility to read the contents of the dedicated section and link all of
|
|
the bitcode into a single whole-program bitcode file. This utility
|
|
works for both executable and native libraries.
|
|
|
|
For more details see [wllvm](https://github.com/SRI-CSL/whole-program-llvm).
|
|
|
|
## Prerequisites
|
|
|
|
To install `gllvm` you need the go language [tool](https://golang.org/doc/install).
|
|
|
|
To use `gllvm` you need clang/clang++ and the llvm tools llvm-link and llvm-ar.
|
|
`gllvm` is agnostic to the actual llvm version. `gllvm` also relies on standard build
|
|
tools such as `objcopy` and `ld`.
|
|
|
|
|
|
## Installation
|
|
|
|
To install, simply do
|
|
```
|
|
go get github.com/SRI-CSL/gllvm/cmd/...
|
|
```
|
|
This should install four binaries: `gclang`, `gclang++`, `get-bc`, and `gsanity-check`
|
|
in the `$GOPATH/bin` directory.
|
|
|
|
## Usage
|
|
|
|
`gclang` and
|
|
`gclang++` are the wrappers used to compile C and C++. `get-bc` is used for
|
|
extracting the bitcode from a build product (either an object file, executable, library
|
|
or archive). `gsanity-check` can be used for detecting configuration errors.
|
|
|
|
Here is a simple example. Assuming that clang is in your `PATH`, you can build
|
|
bitcode for `pkg-config` as follows:
|
|
|
|
```
|
|
tar xf pkg-config-0.26.tar.gz
|
|
cd pkg-config-0.26
|
|
CC=gclang ./configure
|
|
make
|
|
```
|
|
|
|
This should produce the executable `pkg-config`. To extract the bitcode:
|
|
```
|
|
get-bc pkg-config
|
|
```
|
|
|
|
which will produce the bitcode module `pkg-config.bc`.
|
|
|
|
|
|
If clang and the llvm tools are not in your `PATH`, you will need to set some
|
|
environment variables.
|
|
|
|
|
|
* `LLVM_COMPILER_PATH` can be set to the absolute path of the directory that
|
|
contains the compiler and the other LLVM tools to be used.
|
|
|
|
* `LLVM_CC_NAME` can be set if your clang compiler is not called `clang` but
|
|
something like `clang-3.7`. Similarly `LLVM_CXX_NAME` can be used to
|
|
describe what the C++ compiler is called. We also pay attention to the
|
|
environment variables `LLVM_LINK_NAME` and `LLVM_AR_NAME` in an
|
|
analogous way.
|
|
|
|
Another useful environment variable is `WLLVM_CONFIGURE_ONLY`. Its use is explained in the
|
|
README of [wllvm](https://github.com/SRI-CSL/whole-program-llvm).
|
|
|
|
`gllvm` does not support the dragonegg plugin. All other features of `wllvm`, such as logging, and the bitcode store,
|
|
are supported in exactly the same fashion.
|
|
|
|
## License
|
|
|
|
`gllvm` is released under the MIT license. See the file `LICENSE` for [details.](LICENSE)
|