LLVM/SPIR-V Bi-Directional Translator

The khronos/spirv-3.6.1 branch of this repository contains source code for the LLVM/SPIR-V Bi-Directional Translator, a library for translating between LLVM and 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.

Currently it accepts LLVM bitcodes compatible with SPIR 1.2/2.0 standards, and SPIR-V friendly format.

It also works together with Khronos OpenCL C compiler for SPIR-V to compile OpenCL C source code to SPIR-V.

Directory Structure

The files/directories are related to the translator:

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

Build Instructions

Follow the build instructions of Khronos OpenCL C compiler for SPIR-V.

Alternatively,

1. Clone the khronos/spirv-3.6.1 branch.
2. Follow LLVM build instructions.

Run Instructions for llvm-spirv

llvm-spirv only accepts SPIR 1.2/2.0 or LLVM bitcode following a SPIR-V friendly format.

The Khronos OpenCL C compiler can be used to compile OpenCL 1.2/2.0 C source code to SPIR 1.2/2.0 or SPIR-V. It has three branches: spir_12, spir_20_provisional, and spirv-1.0, corresponding to SPIR 1.2, SPIR 2.0, and SPIR-V, respectively. The spirv-1.0 branch emits SPIR-V directly. It is recommended to use the spirv-1.0 branch since SPIR 1.2/2.0 have limitations for representing sampler types and access qualifier of image and pipe types, which may result in incorrect SPIR-V in certain cases.

To translate between SPIR 1.2/2.0 and SPIR-V:

1. Follow the instructions provided by the Khronos OpenCL C compiler website to use clang to compile OpenCL C source code to SPIR 1.2/2.0 binary.

2. Execute the following command to translate input.bc to input.spv

   llvm-spirv input.bc
   

3. Execute the following command to translate input.spv to input.bc

   llvm-spirv -r input.spv
   

4. 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.