Add cross-platform source build CI

.github/workflows/build.yml

@@ -0,0 +1,38 @@
+name: Build
+
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches: [main]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: build-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: linux-x86_64
+            runner: ubicloud-standard-8
+          - name: linux-arm64
+            runner: ubicloud-standard-8-arm
+          - name: macos-arm64
+            runner: macos-26
+    name: ${{ matrix.name }}
+    runs-on: ${{ matrix.runner }}
+    steps:
+      - uses: actions/checkout@v7
+      - name: Install Linux build tools
+        if: runner.os == 'Linux'
+        run: sudo apt-get update && sudo apt-get install -y cmake ninja-build pkg-config
+      - name: Set up source dependencies
+        run: tools/setup_source_deps.sh
+      - name: Build xmojo
+        run: ./bazelw build --config=public-cache @xmojo//:xmojo

DEV.md

@@ -75,23 +75,24 @@ Published wheels remain macOS-only. The experimental IREE runtime story is
 currently Metal-only; the interactive engine and compiler-only SPIR-V story
 build and run on both operating systems.
 
-Clone xmojo and its editable dependencies into one directory:
+Clone xmojo, then let its setup helper create the pinned sibling worktrees and
+enable LLVM's SPIR-V target in Modular:
 
 ```bash
 git clone --depth 1 https://github.com/AnswerDotAI/xmojo.git
-git clone --depth 1 https://github.com/modular/modular.git
-git clone --depth 1 https://github.com/iree-org/iree.git
-git clone --depth 1 https://github.com/nlohmann/json.git nlohmann-json
-git clone --depth 1 https://github.com/jupyter-xeus/xeus.git
-git clone --depth 1 https://github.com/jupyter-xeus/xeus-zmq.git
-git clone --depth 1 https://github.com/zeromq/libzmq.git
-git clone --depth 1 https://github.com/zeromq/cppzmq.git
-git -C iree submodule update --init --depth 1 third_party/flatcc
+cd xmojo
+tools/setup_source_deps.sh
 ```
 
-For a reproducible release build, check out the revisions in
-`bazel/versions.bzl` and the IREE revision in `docs/modular-gpu-pipeline.md`.
-Normal development intentionally uses the current local worktrees.
+The helper clones only missing dependencies and leaves existing worktrees
+untouched, so normal development can continue to use current local revisions.
+The experimental IREE runtime additionally needs the revision recorded in
+`docs/modular-gpu-pipeline.md` and its FlatCC submodule:
+
+```bash
+git clone --depth 1 https://github.com/iree-org/iree.git ../iree
+git -C ../iree submodule update --init --depth 1 third_party/flatcc
+```
 
 The open Modular build enables only its default LLVM targets. xmojo's SPIR-V
 backend needs one local root-module configuration line. Add it between the
@@ -103,10 +104,10 @@ llvm_configure.configure(extra_targets = ["SPIRV"])
 use_repo(llvm_configure, "llvm-project")
 ```
 
-This is the only local Modular edit. It selects code already present in
-Modular's pinned LLVM checkout; xmojo contains the target implementation.
-Keeping it in the root module means every xmojo build uses the same LLVM
-configuration and Bazel cache key.
+This is the only local Modular edit, and `tools/setup_source_deps.sh` applies it
+idempotently. It selects code already present in Modular's pinned LLVM checkout;
+xmojo contains the target implementation. Keeping it in the root module means
+every xmojo build uses the same LLVM configuration and Bazel cache key.
 
 Set up the editable Python project and its native command with:
 

tools/setup_source_deps.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+script_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+deps_root="${XMOJO_DEPS_ROOT:-$(dirname "$script_root")}"
+source "$script_root/bazel/versions.bzl"
+
+clone_revision() {
+  local name="$1" url="$2" revision="$3" destination="$deps_root/$1"
+  if [[ -e "$destination" ]]; then
+    if [[ ! -d "$destination/.git" ]]; then
+      echo "$destination exists but is not a git worktree" >&2
+      exit 2
+    fi
+    echo "Using existing $destination"
+    return
+  fi
+
+  echo "Cloning $name at $revision"
+  local temporary
+  temporary="$(mktemp -d "$deps_root/.xmojo-$name.XXXXXX")"
+  if git init -q "$temporary" &&
+      git -C "$temporary" remote add origin "$url" &&
+      git -C "$temporary" fetch -q --depth 1 origin "$revision" &&
+      git -C "$temporary" checkout -q --detach FETCH_HEAD; then
+    mv "$temporary" "$destination"
+  else
+    rm -rf "$temporary"
+    return 1
+  fi
+}
+
+mkdir -p "$deps_root"
+clone_revision modular https://github.com/modular/modular.git "$MODULAR_REVISION"
+clone_revision nlohmann-json https://github.com/nlohmann/json.git "$NLOHMANN_JSON_REVISION"
+clone_revision xeus https://github.com/jupyter-xeus/xeus.git "$XEUS_REVISION"
+clone_revision xeus-zmq https://github.com/jupyter-xeus/xeus-zmq.git "$XEUS_ZMQ_REVISION"
+clone_revision libzmq https://github.com/zeromq/libzmq.git "$LIBZMQ_REVISION"
+clone_revision cppzmq https://github.com/zeromq/cppzmq.git "$CPPZMQ_REVISION"
+
+module_file="$deps_root/modular/MODULE.bazel"
+spirv_config='llvm_configure.configure(extra_targets = ["SPIRV"])'
+if ! grep -Fqx "$spirv_config" "$module_file"; then
+  marker='use_repo(llvm_configure, "llvm-project")'
+  if [[ "$(grep -Fxc "$marker" "$module_file")" -ne 1 ]]; then
+    echo "Could not locate the LLVM repository declaration in $module_file" >&2
+    exit 2
+  fi
+  temporary="$module_file.xmojo"
+  awk -v marker="$marker" -v config="$spirv_config" \
+    '$0 == marker { print config } { print }' "$module_file" > "$temporary"
+  mv "$temporary" "$module_file"
+  echo "Enabled LLVM SPIR-V in $module_file"
+fi