Add a build libcore-only nvptx64 test (using xargo).

This also disables the "integer_atomics" feature on nvptx/nvptx64.

library/stdarch/.travis.yml

@@ -56,6 +56,14 @@ matrix:
       script: ci/run.sh
     - name: "wasm32-unknown-unknown"
       env: TARGET=wasm32-unknown-unknown
+    - name: "nvptx64-nvidia-cuda - cross compiled, build libcore only"
+      env: TARGET=x86_64-unknown-linux-gnu CROSS_TARGET=nvptx64-nvidia-cuda-cross NORUN=1 NOSTD=1
+      install:
+        - travis_retry rustup target add $TARGET
+        - travis_retry rustup component add rust-src
+        - cargo install xargo
+        - xargo --version
+        - mkdir -p $HOME/.xargo
     - name: "thumbv6m-none-eabi - build libcore only"
       env: TARGET=thumbv6m-none-eabi NORUN=1 NOSTD=1
       script: ci/run.sh
@@ -103,7 +111,7 @@ matrix:
 install: travis_retry rustup target add $TARGET
 script:
   - cargo generate-lockfile
-  - ci/run-docker.sh $TARGET $FEATURES
+  - ci/run-docker.sh $TARGET $CROSS_TARGET $FEATURES
 
 notifications:
   email:

library/stdarch/ci/cross/nvptx64-nvidia-cuda.json

@@ -0,0 +1,15 @@
+{
+  "arch": "nvptx64"
+, "cpu": "sm_35"
+, "data-layout": "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v16:16:16-v32:32:32-v64:64:64-v128:128:128-n16:32:64"
+, "linker": false
+, "linker-flavor": "ld"
+, "llvm-target": "nvptx64-nvidia-cuda"
+, "max-atomic-width": 0
+, "obj-is-bitcode": true
+, "os": "cuda"
+, "panic-strategy": "abort"
+, "target-c-int-width": "32"
+, "target-endian": "little"
+, "target-pointer-width": "64"
+}

library/stdarch/ci/docker/nvptx64-nvidia-cuda-cross/Dockerfile

@@ -0,0 +1,5 @@
+FROM ubuntu:18.04
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  gcc \
+  libc6-dev \
+  ca-certificates

library/stdarch/ci/run-docker.sh

@@ -6,10 +6,18 @@
 set -ex
 
 run() {
-    echo "Building docker container for TARGET=${1}"
-    docker build -t stdsimd -f "ci/docker/${1}/Dockerfile" ci/
-    mkdir -p target
     target=$(echo "${1}" | sed 's/-emulated//')
+    cross="0"
+    if [ -z "${2}" ]; then
+        echo "Building docker container for TARGET=${1}"
+        docker build -t stdsimd -f "ci/docker/${1}/Dockerfile" ci/
+    else
+        target=$(echo "${2}" | sed 's/-cross//')
+        cross="1"
+        echo "Building docker container for CROSS_TARGET=${2}"
+        docker build -t stdsimd -f "ci/docker/${2}/Dockerfile" ci/
+    fi
+    mkdir -p target
     echo "Running docker"
     # shellcheck disable=SC2016
     docker run \
@@ -18,6 +26,8 @@ run() {
       --init \
       --volume "${HOME}"/.cargo:/cargo-h \
       --env CARGO_HOME=/cargo-h \
+      --volume "${HOME}"/.xargo:/xargo-h \
+      --env XARGO_HOME=/xargo-h \
       --volume "$(rustc --print sysroot)":/rust:ro \
       --env TARGET="${target}" \
       --env STDSIMD_TEST_EVERYTHING \
@@ -27,6 +37,7 @@ run() {
       --env NORUN \
       --env RUSTFLAGS \
       --env STDSIMD_TEST_NORUN \
+      --env CROSS="${cross}" \
       --volume "$(pwd)":/checkout:ro \
       --volume "$(pwd)"/target:/checkout/target \
       --workdir /checkout \
@@ -41,5 +52,5 @@ if [ -z "$1" ]; then
     run "${d}"
   done
 else
-  run "${1}"
+  run "${1}" "${2}"
 fi

library/stdarch/ci/run.sh

@@ -30,14 +30,34 @@ echo "FEATURES=${FEATURES}"
 echo "OBJDUMP=${OBJDUMP}"
 echo "STDSIMD_DISABLE_ASSERT_INSTR=${STDSIMD_DISABLE_ASSERT_INSTR}"
 echo "STDSIMD_TEST_EVERYTHING=${STDSIMD_TEST_EVERYTHING}"
+echo "CROSS=${CROSS}"
+
+cargo_setup() {
+    if [ "$CROSS" = "1" ]
+    then
+        export RUST_TARGET_PATH="/checkout/ci/cross"
+        echo "RUST_TARGET_PATH=${RUST_TARGET_PATH}"
+    fi
+}
 
 cargo_test() {
+    if [ "$CROSS" = "1" ]
+    then
+        cmd="/cargo-h/bin/xargo"
+    else
+        cmd="cargo"
+    fi
     subcmd="test"
     if [ "$NORUN" = "1" ]
     then
-        export subcmd="build"
+        if [ "$CROSS" = "1" ]
+        then
+            export subcmd="rustc"
+        else
+            export subcmd="build"
+        fi
     fi
-    cmd="cargo ${subcmd} --target=$TARGET $1"
+    cmd="$cmd ${subcmd} --target=$TARGET $1"
     if [ "$NOSTD" = "1" ]
     then
         cmd="$cmd -p coresimd"
@@ -52,11 +72,24 @@ cargo_test() {
         cmd="$cmd --quiet"
       fi
     fi
+    if [ "$CROSS" = "1" ]
+    then
+        cmd="$cmd --emit=asm"
+    fi
     $cmd
 }
 
+cargo_output() {
+    if [ "$CROSS" = "1" ]
+    then
+        find /checkout/target -name "*.s"
+    fi
+}
+
+cargo_setup
 cargo_test
 cargo_test "--release"
+cargo_output
 
 # Test targets compiled with extra features.
 case ${TARGET} in

library/stdarch/crates/coresimd/src/lib.rs

@@ -18,7 +18,6 @@
     simd_ffi,
     asm,
     proc_macro_hygiene,
-    integer_atomics,
     stmt_expr_attributes,
     core_intrinsics,
     no_core,
@@ -38,6 +37,14 @@
     powerpc_target_feature,
     wasm_target_feature
 )]
+// NB: When running nvptx/nvptx64 cross tests, enabling "integer_atomics" yields
+// a compile-time error: 'unknown feature `integer_atomics`'. This ought to be
+// investigated further, but for now just disable "integer_atomics" so we can
+// run _some_ test for the nvptx/nvptx64 targets.
+#![cfg_attr(
+    not(any(target_arch = "nvptx", target_arch = "nvptx64")),
+    feature(integer_atomics)
+)]
 #![cfg_attr(test, feature(test, abi_vectorcall, untagged_unions))]
 #![cfg_attr(
     feature = "cargo-clippy",