# LLVM/SPIR-V Bi-Directional Translator

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This repository contains source code for the LLVM/SPIR-V Bi-Directional Translator, a library and tool for translation between LLVM IR and [SPIR-V](https://www.khronos.org/registry/spir-v/).

The LLVM/SPIR-V Bi-Directional Translator is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.


## Directory Structure


The files/directories related to the translator:

* [include/LLVMSPIRVLib.h](include/LLVMSPIRVLib.h) - header file
* [lib/SPIRV](lib/SPIRV) - library for SPIR-V in-memory representation, decoder/encoder and LLVM/SPIR-V translator
* [tools/llvm-spirv](tools/llvm-spirv) - command line utility for translating between LLVM bitcode and SPIR-V binary

## Build Instructions

Master branch of this repo is aimed to be buildable with the latest LLVM version.

### Build with pre-installed LLVM

The translator can be built with the latest(nightly) package of LLVM. For Ubuntu and Debian systems LLVM provides repositories with nightly builds at http://apt.llvm.org/. For example the latest package for Ubuntu 16.04 can be installed with the following commands:
```
sudo add-apt-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial main"
sudo apt-get update
sudo apt-get install llvm-7-dev
```
The intalled version of LLVM will be used by default for out-of-tree build of the translator.
```
git clone https://github.com/KhronosGroup/SPIRV-LLVM-Translator.git
mkdir SPIRV-LLVM-Translator/build && cd SPIRV-LLVM-Translator/build
cmake ..
make llvm-spirv -j`nproc`
```

### Build with pre-built LLVM

If you have a custom build(based on the latest version) of LLVM libraries you can link the translator against it. 
```
git clone https://github.com/KhronosGroup/SPIRV-LLVM-Translator.git
mkdir SPIRV-LLVM-Translator/build && cd SPIRV-LLVM-Translator/build
cmake .. -DLLVM_DIR=<llvm_build_dir>/lib/cmake/llvm/
make llvm-spirv -j`nproc`
```
Where `llvm_build_dir` is the LLVM build directory.

### LLVM in-tree build

The translator can be built as a regular LLVM subproject. To do that you need to clone it to `llvm/projects` or `llvm/tools` directory. 
```
git clone http://llvm.org/git/llvm.git
cd llvm/project
git clone https://github.com/KhronosGroup/SPIRV-LLVM-Translator.git
```
Run(re-run) cmake as usually for LLVM. After that you should have `llvm-spirv` and `check-llvm-spirv` targets available.
```
mkdir llvm/build && cd llvm/build 
cmake ..
make llvm-spirv -j`nproc`
```

## Test instructions

All tests related to the translator are placed in the [test](test) directory.

Execute the following command to run translator tests:
```
llvm-lit test
```

## Run Instructions for `llvm-spirv`


To translate between LLVM IR and SPIR-V:

1. Execute the following command to translate `input.bc` to `input.spv`
    ```
    llvm-spirv input.bc
    ```

2. Execute the following command to translate `input.spv` to `input.bc`
    ```
    llvm-spirv -r input.spv
    ```

3. Other options accepted by `llvm-spirv`

    * `-o file_name` - to specify output name
    * `-spirv-debug` - output debugging information
    * `-spirv-text` - read/write SPIR-V in an internal textual format for debugging purpose. The textual format is not defined by SPIR-V spec.
    * `-help` - to see full list of options