[ci] Use sccache for Windows CPU build. (#11979)

Author: trivialfis

.github/workflows/windows.yml

@@ -1,4 +1,4 @@
-name: XGBoost CI (Windows)
+name: Windows
 
 on: [push, pull_request]
 
@@ -28,7 +28,10 @@ jobs:
       - uses: actions/checkout@v6.0.1
         with:
           submodules: "true"
-      - run: powershell ops/pipeline/build-win64-gpu.ps1
+      - uses: dmlc/xgboost-devops/actions/msvc-dev-env@main
+      - uses: dmlc/xgboost-devops/actions/sccache@main
+      - run: ops/pipeline/build-win64.ps1 -variant gpu
+      - run: sccache --show-stats
       - name: Stash files
         shell: powershell
         run: |
@@ -51,7 +54,7 @@ jobs:
           submodules: "true"
       - uses: dmlc/xgboost-devops/actions/msvc-dev-env@main
       - uses: dmlc/xgboost-devops/actions/sccache@main
-      - run: powershell ops/pipeline/build-win64-cpu.ps1
+      - run: ops/pipeline/build-win64.ps1 -variant cpu
       - run: sccache --show-stats
 
   test-win64-gpu:

ops/pipeline/build-win64-cpu.ps1

@@ -0,0 +1,93 @@
+## Build XGBoost on Windows (CPU or GPU)
+##
+## Usage:
+##   build-win64.ps1 -variant <cpu|gpu>
+##
+## Parameters:
+##   -variant cpu  - Build CPU-only version (creates xgboost-cpu wheel)
+##   -variant gpu  - Build with CUDA support (creates default xgboost wheel, includes gtest)
+##
+## Examples:
+##   # Build CPU wheel (xgboost-cpu)
+##   ops/pipeline/build-win64.ps1 -variant cpu
+##
+##   # Build GPU wheel with CUDA
+##   ops/pipeline/build-win64.ps1 -variant gpu
+
+param(
+  [Parameter(Mandatory=$true)]
+  [ValidateSet("cpu", "gpu")]
+  [string]$variant
+)
+
+$ErrorActionPreference = "Stop"
+
+. ops/pipeline/enforce-ci.ps1
+
+# Build common CMake arguments
+$cmake_args = @(
+  "-G", "Ninja",
+  "-DCMAKE_BUILD_TYPE=Release",
+  "-DCMAKE_C_COMPILER_LAUNCHER=sccache",
+  "-DCMAKE_CXX_COMPILER_LAUNCHER=sccache"
+)
+
+if ($variant -eq "gpu") {
+  Write-Host "--- Build libxgboost on Windows with CUDA"
+  nvcc --version
+  if ($LASTEXITCODE -ne 0) { throw "Last command failed" }
+
+  # Add CUDA-specific flags
+  $cmake_args += @(
+    "-DUSE_CUDA=ON",
+    "-DGOOGLE_TEST=ON",
+    "-DUSE_DMLC_GTEST=ON"
+  )
+
+  # Only build SM75 for non-release branches (faster CI)
+  if ($is_release_branch -eq 0) {
+    $cmake_args += "-DGPU_COMPUTE_VER=75"
+  }
+} else {
+  Write-Host "--- Build libxgboost on Windows (CPU, minimal)"
+}
+
+# Run CMake configure
+mkdir build
+cd build
+& cmake .. @cmake_args
+if ($LASTEXITCODE -ne 0) { throw "Last command failed" }
+
+# Build
+cmake --build . -v
+if ($LASTEXITCODE -ne 0) { throw "Last command failed" }
+
+Write-Host "--- Build binary wheel"
+cd ..
+
+# For CPU variant, rename package to xgboost-cpu
+if ($variant -eq "cpu") {
+  conda activate
+  python ops/script/pypi_variants.py --use-suffix=cpu --require-nccl-dep=na
+  if ($LASTEXITCODE -ne 0) { throw "Last command failed" }
+}
+
+cd python-package
+conda activate
+& pip wheel --no-deps -v . --wheel-dir dist/
+if ($LASTEXITCODE -ne 0) { throw "Last command failed" }
+
+python -m wheel tags --python-tag py3 --abi-tag none `
+  --platform win_amd64 --remove `
+  (Get-ChildItem dist/*.whl | Select-Object -Expand FullName)
+if ($LASTEXITCODE -ne 0) { throw "Last command failed" }
+
+Write-Host "--- Upload Python wheel"
+cd ..
+if ($is_release_branch -eq 1) {
+  python ops/pipeline/manage-artifacts.py upload `
+    --s3-bucket 'xgboost-nightly-builds' `
+    --prefix "$Env:BRANCH_NAME/$Env:GITHUB_SHA" --make-public `
+    (Get-ChildItem python-package/dist/*.whl | Select-Object -Expand FullName)
+  if ($LASTEXITCODE -ne 0) { throw "Last command failed" }
+}