RISC-V Custom Runtime (DLR)

This repository is a lightweight runtime for RISC-V utility. We uses TVM runtime to create a C++ interface that can be called by host.cpp to invoke runtime function. After saving a TVM module as .ll, .graph and .params, with supporting from LLVM and host.cpp. Users can further compile the program with riscv-gun-toolcahin and easily run the inference with Spike.

How to use

Build steps

There are 2 targets in DLR.

• A static library: libDLR.a
  • for compiling with host code
• An executable: DumpKernel
  • for generating kernel.inc from graph

Because libDLR.a is for compiling with host code and eventually be executed on Spike, it need to be compiled by gcc/g++ of riscv-gnu-toolchain.

On the other hand, DumpKernel can be executed directly, so it has no need to be compiled by gcc/g++ of riscv-gnu-toolchain.

##############################
#  RISCV-build for libDLR.a  #
##############################
# set RISCV to where riscv-gnu-toolchain installed
mkdir build-riscv
cd build-riscv

CC=$RISCV/bin/riscv64-unknown-elf-gcc \
  CXX=$RISCV/bin/riscv64-unknown-elf-g++ \
  cmake .. \
  -DCMAKE_INSTALL_PREFIX=../install-riscv
cmake --build .
cmake --install .

cd ..

#################################
#  normal build for DumpKernel  #
#################################
mkdir build && cd build

cmake .. \
  -DCMAKE_INSTALL_PREFIX=../install
cmake --build .
cmake --install .

cd ..

Example - Pre-quantized mobilenet v1 model

The example is shown in example/pre_quant_mobilenet_v1_tflite

• In build_model.py, we run the TVM routine and save the TVM module.
• In host.cpp, we invoke function in DLR for init, load input, and running.

After setting up the paths of dependences in Makefile, you can run all the flow easily, as illustrated in the figure above.

• RISCV_INSTALL: where riscv-gnu-toolchain is installed
• DLR_INSTALL: as the explanation in "Build Steps" section, we need to build DLR twice for different purpose. This one is for DumpKernel executable to generate kernel.inc.
• DLR_RISCV_INSTALL: This one is for libDLR.a static library, which is compiled by gcc/g++ of riscv-gnu-toolchain. The static library will be compiled with the host code and run on Spike.
• LLVM_INSTALL: modified LLVM with RISC-V P extension support.

make
make run

Dependent project

• LLVM
  • The version we used as target for TMV QNN with RISC-V P extension support is open source at here.
• riscv-gun-toolchain
  • To support our flow for TVM QNN, please use riscv-binutils and spike that we modified for supporting P extension

Acknowledgement

• Apache TVM