RISC-V GNU/Linux as host platform

.github/workflows/ci.yml

@@ -297,6 +297,9 @@ jobs:
           - name: dist-powerpc64le-linux
             os: ubuntu-latest-xl
             env: {}
+          - name: dist-riscv64-linux
+            os: ubuntu-latest-xl
+            env: {}
           - name: dist-s390x-linux
             os: ubuntu-latest-xl
             env: {}

src/bootstrap/native.rs

@@ -111,6 +111,15 @@ impl Step for Llvm {
     /// Compile LLVM for `target`.
     fn run(self, builder: &Builder<'_>) -> PathBuf {
         let target = self.target;
+        let target_native = if self.target.starts_with("riscv") {
+            // RISC-V target triples in Rust is not named the same as C compiler target triples.
+            // This converts Rust RISC-V target triples to C compiler triples.
+            let idx = target.find('-').unwrap();
+
+            format!("riscv{}{}", &target[5..7], &target[idx..])
+        } else {
+            target.to_string()
+        };
 
         let Meta { stamp, build_llvm_config, out_dir, root } =
             match prebuilt_llvm_config(builder, target) {
@@ -164,8 +173,8 @@ impl Step for Llvm {
             .define("LLVM_ENABLE_BINDINGS", "OFF")
             .define("LLVM_ENABLE_Z3_SOLVER", "OFF")
             .define("LLVM_PARALLEL_COMPILE_JOBS", builder.jobs().to_string())
-            .define("LLVM_TARGET_ARCH", target.split('-').next().unwrap())
-            .define("LLVM_DEFAULT_TARGET_TRIPLE", target);
+            .define("LLVM_TARGET_ARCH", target_native.split('-').next().unwrap())
+            .define("LLVM_DEFAULT_TARGET_TRIPLE", target_native);
 
         if !target.contains("netbsd") {
             cfg.define("LLVM_ENABLE_ZLIB", "ON");
@@ -212,6 +221,17 @@ impl Step for Llvm {
             }
         }
 
+        if target.starts_with("riscv") {
+            // In RISC-V, using C++ atomics require linking to `libatomic` but the LLVM build
+            // system check cannot detect this. Therefore it is set manually here.
+            if !builder.config.llvm_tools_enabled {
+                cfg.define("CMAKE_EXE_LINKER_FLAGS", "-latomic");
+            } else {
+                cfg.define("CMAKE_EXE_LINKER_FLAGS", "-latomic -static-libstdc++");
+            }
+            cfg.define("CMAKE_SHARED_LINKER_FLAGS", "-latomic");
+        }
+
         if target.contains("msvc") {
             cfg.define("LLVM_USE_CRT_DEBUG", "MT");
             cfg.define("LLVM_USE_CRT_RELEASE", "MT");

src/ci/azure-pipelines/auto.yml

@@ -53,6 +53,7 @@ jobs:
       dist-powerpc-linux: {}
       dist-powerpc64-linux: {}
       dist-powerpc64le-linux: {}
+      dist-riscv64-linux: {}
       dist-s390x-linux: {}
       dist-x86_64-freebsd: {}
       dist-x86_64-musl: {}

src/ci/docker/host-x86_64/dist-riscv64-linux/Dockerfile

@@ -0,0 +1,31 @@
+FROM ubuntu:18.04
+
+COPY scripts/cross-apt-packages.sh /scripts/
+RUN sh /scripts/cross-apt-packages.sh
+
+COPY host-x86_64/dist-riscv64-linux/crosstool-ng.sh /scripts/
+RUN sh /scripts/crosstool-ng.sh
+
+COPY scripts/rustbuild-setup.sh /scripts/
+RUN sh /scripts/rustbuild-setup.sh
+USER rustbuild
+WORKDIR /tmp
+
+COPY host-x86_64/dist-riscv64-linux/build-toolchains.sh host-x86_64/dist-riscv64-linux/riscv64-unknown-linux-gnu.config /tmp/
+RUN ./build-toolchains.sh
+
+USER root
+
+COPY scripts/sccache.sh /scripts/
+RUN sh /scripts/sccache.sh
+
+ENV PATH=$PATH:/x-tools/riscv64-unknown-linux-gnu/bin
+
+ENV CC_riscv64gc_unknown_linux_gnu=riscv64-unknown-linux-gnu-gcc \
+    AR_riscv64gc_unknown_linux_gnu=riscv64-unknown-linux-gnu-ar \
+    CXX_riscv64gc_unknown_linux_gnu=riscv64-unknown-linux-gnu-g++
+
+ENV HOSTS=riscv64gc-unknown-linux-gnu
+
+ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
+ENV SCRIPT python3 ../x.py dist --target $HOSTS --host $HOSTS

src/ci/docker/host-x86_64/dist-various-1/build-riscv-toolchain.sh → src/ci/docker/host-x86_64/dist-riscv64-linux/build-toolchains.sh

@@ -19,9 +19,9 @@ exit 1
   set -x
 }
 
-mkdir -p /tmp/build-riscv
-cp riscv64-unknown-linux-gnu.config /tmp/build-riscv/.config
-cd /tmp/build-riscv
+mkdir build
+cd build
+cp ../riscv64-unknown-linux-gnu.config .config
 hide_output ct-ng build
 cd ..
-rm -rf build-riscv
+rm -rf build

src/ci/docker/host-x86_64/dist-various-1/crosstool-ng.sh → src/ci/docker/host-x86_64/dist-riscv64-linux/crosstool-ng.sh

@@ -1,4 +1,3 @@
-#!/bin/bash
 set -ex
 
 # Mirrored from https://github.com/crosstool-ng/crosstool-ng/archive/crosstool-ng-1.24.0.tar.gz

src/ci/docker/host-x86_64/dist-various-1/riscv64-unknown-linux-gnu.config → src/ci/docker/host-x86_64/dist-riscv64-linux/riscv64-unknown-linux-gnu.config

@@ -17,8 +17,6 @@ CT_CONFIGURE_has_gnu_m4_1_4_12_or_newer=y
 CT_CONFIGURE_has_python_3_4_or_newer=y
 CT_CONFIGURE_has_bison_2_7_or_newer=y
 CT_CONFIGURE_has_python=y
-CT_CONFIGURE_has_dtc=y
-CT_CONFIGURE_has_svn=y
 CT_CONFIGURE_has_git=y
 CT_CONFIGURE_has_md5sum=y
 CT_CONFIGURE_has_sha1sum=y

src/ci/docker/host-x86_64/dist-various-1/Dockerfile

@@ -47,18 +47,6 @@ RUN add-apt-repository ppa:team-gcc-arm-embedded/ppa && \
     apt-get update && \
     apt-get install -y --no-install-recommends gcc-arm-embedded
 
-COPY scripts/rustbuild-setup.sh host-x86_64/dist-various-1/build-riscv-toolchain.sh host-x86_64/dist-various-1/riscv64-unknown-linux-gnu.config host-x86_64/dist-various-1/crosstool-ng.sh /build/
-RUN ./crosstool-ng.sh
-
-# Crosstool-ng will refuse to build as root
-RUN sh ./rustbuild-setup.sh
-USER rustbuild
-
-RUN ./build-riscv-toolchain.sh
-
-USER root
-ENV PATH=/x-tools/riscv64-unknown-linux-gnu/bin:$PATH
-
 COPY host-x86_64/dist-various-1/build-rumprun.sh /build
 RUN ./build-rumprun.sh
 
@@ -158,7 +146,6 @@ ENV TARGETS=$TARGETS,riscv32imc-unknown-none-elf
 ENV TARGETS=$TARGETS,riscv32imac-unknown-none-elf
 ENV TARGETS=$TARGETS,riscv64imac-unknown-none-elf
 ENV TARGETS=$TARGETS,riscv64gc-unknown-none-elf
-ENV TARGETS=$TARGETS,riscv64gc-unknown-linux-gnu
 ENV TARGETS=$TARGETS,armebv7r-none-eabi
 ENV TARGETS=$TARGETS,armebv7r-none-eabihf
 ENV TARGETS=$TARGETS,armv7r-none-eabi
@@ -186,9 +173,6 @@ ENV CC_mipsel_unknown_linux_musl=mipsel-openwrt-linux-gcc \
     CFLAGS_aarch64_unknown_none_softfloat=-mstrict-align -march=armv8-a+nofp+nosimd \
     CC_aarch64_unknown_none=aarch64-none-elf-gcc \
     CFLAGS_aarch64_unknown_none=-mstrict-align -march=armv8-a+fp+simd \
-    CC_riscv64gc_unknown_linux_gnu=riscv64-unknown-linux-gnu-gcc \
-    AR_riscv64gc_unknown_linux_gnu=riscv64-unknown-linux-gnu-ar \
-    CXX_riscv64gc_unknown_linux_gnu=riscv64-unknown-linux-gnu-g++ \
     CC_riscv32i_unknown_none_elf=false \
     CC_riscv32imc_unknown_none_elf=false \
     CC_riscv32imac_unknown_none_elf=false \

src/ci/github-actions/ci.yml

@@ -341,6 +341,9 @@ jobs:
           - name: dist-powerpc64le-linux
             <<: *job-linux-xl
 
+          - name: dist-riscv64-linux
+            <<: *job-linux-xl
+
           - name: dist-s390x-linux
             <<: *job-linux-xl
 

src/librustc_llvm/build.rs

@@ -275,6 +275,11 @@ fn main() {
         "stdc++"
     };
 
+    // RISC-V requires libatomic for sub-word atomic operations
+    if target.starts_with("riscv") {
+        println!("cargo:rustc-link-lib=atomic");
+    }
+
     // C++ runtime library
     if !target.contains("msvc") {
         if let Some(s) = llvm_static_stdcpp {