nixpkgs-xthead-toolchains

A Nix flake with overlays for toolchains with support for xthead extensions

Configuration

Add to your flake input:

inputs.xthead-toolchains.url = "github:milkv-community/nixpkgs-xthead-toolchains";

Then add to your overlays:

nixpkgs.overlays = [
  xthead-toolchains.overlays.default
];

The overlay defines several packages under xthead which you can install:

# For your riscv64 native host:
environment.systemPackages = with pkgs; [
  # xthead.binutils_2_42
  xthead.gcc14
  # xthead.llvmPackages_17.clang
];

# For cross-compiling from your non-riscv64 native host to riscv64:
# NOTE: this prefixes tools with `riscv64-unknown-linux-gnu-`
environment.systemPackages = with pkgs.pkgsCross.riscv64.buildPackages; [
  # xthead.binutils_2_42
  xthead.gcc14
  # xthead.llvmPackages_17.clang
];

Note that the gcc14 package automatically includes binutils version 2.42 since that version is needed to assemble the new xtheadvector instructions.

Usage

GCC 14 (with binutils 2.42)

Compile using gcc with xtheadvector via:

gcc -O3 -march=riscv64gc_xtheadvector -mcpu=thead-c906

LLVM 17.0.6

This version of LLVM is compiled from the ruyisdk/llvm-project repository.

See here for further information on the implementation and how to use the xtheadvector extension in detail.

Below is a quick summary.

clang

Compile using clang with xtheadvector via:

clang -march=rv64gc_xtheadvector

llc

Compile LLVM IR using llc with xtheadvector via:

llc -mtriple=riscv64 -mattr=+xtheadvector