Halide language experiments on RISC-V

This repository contains a number of examples written in Halide language which work on RISC-V CPU with RVV 0.7.1. Follow the steps below to reproduce the experiments or some of their parts.

NOTE: At this moment project relies on the Ahead-Of-Time (AOT) compilation of Halide kernels. However there are precompiled files for easy start.

Project uses OpenCV as a reference implementation for some algorithms. Also, we benchmark it to compare with Halide implemention. Fetch OpenCV source code by submodules update after clonning the repository.

git submodule update --init

Build and go

1. Download THead toolchain: Xuantie-900-gcc-linux-5.10.4-glibc-x86_64-V2.6.1-20220906.tar.gz (registration needed)

2. Clone Halide source code (no build required)

   git clone --depth 1 https://github.com/halide/Halide

3. Build a project for RISC-V CPU:

   export PATH=$HOME/Xuantie-900-gcc-linux-5.10.4-glibc-x86_64-V2.6.1/bin/:$PATH
   
   cmake \
       -DCMAKE_BUILD_TYPE=Release \
       -DCMAKE_TOOLCHAIN_FILE=$HOME/halide_riscv/riscv64-071.toolchain.cmake \
       -DHalide_INCLUDE_DIRS=$HOME/Halide/src/runtime \
       -S halide_riscv -B build_rv64
   
   cmake --build build_rv64 -j$(nproc --all)

4. Transfer build directory to the RISC-V board and run test_algo (accuracy tests) or perf_algo (performance tests).

   scp test_algo perf_algo libalgos.so opencv-prefix/src/opencv-build/lib/* sipeed@x.x.x.x:/home/sipeed/

   export LD_LIBRARY_PATH=./
   ./test_algo
   ./perf_algo

Performance results

HW: Sipeed Lichee RV Dock (Allwinner D1 aka XuanTie C906 CPU)

OS: 20211230_LicheeRV_debian_d1_hdmi_8723ds

Algorithm	Input	OpenCV (no RVV)	OpenCV (RVV)	Halide (no RVV)	Halide (RVV)
BGR2Gray	1080x1920x3 (interleaved)	32.18ms	264.66ms	34.18ms	30.78ms
	1080x1920x3 (planar)	--	--	38.13ms	6.65ms
Box filter	input: 1080x1920 output: 1078x1918	75.17ms	139.16ms	198.02ms	62.89ms
Histogram	input: 1080x1920x3 output: 256x3	57.35ms	67.32ms	92.44ms	--
Convolution input: 1x16x128x128 kernel: 32x16x3x3 stride: 1, pad: 0	(FP32) NCHW	829.13ms	338.02ms	4713.57ms	698.27ms
	(FP32) NHWC	--	--	1357.81ms	418.95ms

Generate AOT kernels

If you want regenerate AOT artifacts or add new algorithms, build the project on x86:

1. Build LLVM from https://github.com/dkurt/llvm-rvv-071/tree/rvv-071

   cmake -DCMAKE_BUILD_TYPE=Release \
     -DLLVM_ENABLE_PROJECTS="clang;lld" \
     -DLLVM_TARGETS_TO_BUILD="RISCV" \
     -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ASSERTIONS=ON \
     -DLLVM_ENABLE_EH=ON -DLLVM_ENABLE_RTTI=ON -DLLVM_BUILD_32_BITS=OFF \
     -GNinja \
     -S llvm-project/llvm -B llvm-build
   
   cmake --build llvm-build -j4

2. Build Halide with the following patch (tested on revision https://github.com/halide/Halide/commit/7963cd4e3c23856b82567c99e0a3d16035ffe895):

   diff --git a/src/CodeGen_RISCV.cpp b/src/CodeGen_RISCV.cpp
   index ba9abe04d..454558d11 100644
   --- a/src/CodeGen_RISCV.cpp
   +++ b/src/CodeGen_RISCV.cpp
   @@ -151,6 +151,7 @@ string CodeGen_RISCV::mattrs() const {
               arch_flags += ",+zvl" + std::to_string(target.vector_bits) + "b";
           }
   #endif
   +        arch_flags += ",-zve64x";
       }
       return arch_flags;
   }
   diff --git a/src/autoschedulers/CMakeLists.txt b/src/autoschedulers/CMakeLists.txt
   index 9b88f0a66..10088bb9b 100644
   --- a/src/autoschedulers/CMakeLists.txt
   +++ b/src/autoschedulers/CMakeLists.txt
   @@ -24,6 +24,6 @@ endfunction()
   
   add_subdirectory(common)
   
   -add_subdirectory(adams2019)
   +# add_subdirectory(adams2019)
   add_subdirectory(li2018)
   add_subdirectory(mullapudi2016)

   export LLVM_ROOT=$HOME/llvm-build
   
   cmake -DLLVM_DIR=$LLVM_ROOT/lib/cmake/llvm \
       -DClang_DIR=$LLVM_ROOT/lib/cmake/clang \
       -DCMAKE_BUILD_TYPE=Release \
       -DWITH_TESTS=OFF \
       -DWITH_TUTORIALS=OFF \
       -DWITH_PYTHON_BINDINGS=OFF \
       -S Halide -B halide-build
   
   cmake --build halide-build -j4
   cmake --install halide-build --prefix halide-install

3. Build a project on x86

   export LD_LIBRARY_PATH=$HOME/halide-build/src/autoschedulers/mullapudi2016:$LD_LIBRARY_PATH
   
   cmake \
       -DCMAKE_BUILD_TYPE=Release \
       -DHalide_DIR=$HOME/halide-install/lib/cmake/Halide \
       -S halide_riscv -B build
   
   cmake --build build -j$(nproc --all)

4. Run perf_algo once and find the generated *.h and *.s files in the working directory.