Fix build on Windows, re-enable Windows build CI job

.github/workflows/build-presets.yml

@@ -103,3 +103,40 @@ jobs:
         ./install_requirements.sh > /dev/null
         cmake --preset ${{ matrix.preset }}
         cmake --build cmake-out -j$(( $(nproc) - 1 ))
+
+  windows:
+    uses: pytorch/test-infra/.github/workflows/windows_job.yml@main
+    strategy:
+      fail-fast: false
+      matrix:
+        preset: [pybind, windows]
+    with:
+      job-name: build
+      ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
+      submodules: recursive
+      timeout: 90
+      script: |
+        set -eux
+        conda init powershell
+        powershell -Command "& {
+          Set-PSDebug -Trace 1
+          \$ErrorActionPreference = 'Stop'
+          \$PSNativeCommandUseErrorActionPreference = \$true
+
+          conda create --yes --quiet -n et python=3.12
+          conda activate et
+
+          python install_requirements.py
+          cmake --preset ${{ matrix.preset }} -T ClangCL
+          if (\$LASTEXITCODE -ne 0) {
+            Write-Host "CMake configuration was unsuccessful. Exit code: \$LASTEXITCODE."
+            exit \$LASTEXITCODE
+          }
+
+          \$numCores = [System.Environment]::GetEnvironmentVariable('NUMBER_OF_PROCESSORS') - 1
+          cmake --build cmake-out -j \$numCores
+          if (\$LASTEXITCODE -ne 0) {
+            Write-Host "CMake build was unsuccessful. Exit code: \$LASTEXITCODE."
+            exit \$LASTEXITCODE
+          }
+        }"

CMakeLists.txt

@@ -595,13 +595,22 @@ if(EXECUTORCH_BUILD_EXTENSION_DATA_LOADER)
   if(NOT WIN32)
     set(data_loader_exclude_pattern "*mman_windows.h")
   endif()
-  install(
-    DIRECTORY extension/data_loader/
-    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/executorch/extension/data_loader
-    FILES_MATCHING
-    PATTERN "*.h"
-    PATTERN ${data_loader_exclude_pattern} EXCLUDE
-  )
+  if(DEFINED data_loader_exclude_pattern)
+    install(
+      DIRECTORY extension/data_loader/
+      DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/executorch/extension/data_loader
+      FILES_MATCHING
+      PATTERN "*.h"
+      PATTERN ${data_loader_exclude_pattern} EXCLUDE
+    )
+  else()
+    install(
+      DIRECTORY extension/data_loader/
+      DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/executorch/extension/data_loader
+      FILES_MATCHING
+      PATTERN "*.h"
+    )
+  endif()
   list(APPEND _executorch_extensions extension_data_loader)
 endif()
 

backends/xnnpack/cmake/Dependencies.cmake

@@ -55,6 +55,14 @@ else()
   )
 endif()
 
+if(WIN32)
+  # These XNNPACK options don't currently build on Windows with Clang.
+  set_overridable_option(XNNPACK_ENABLE_AVX256SKX OFF)
+  set_overridable_option(XNNPACK_ENABLE_AVX256VNNI OFF)
+  set_overridable_option(XNNPACK_ENABLE_AVX256VNNIGFNI OFF)
+  set_overridable_option(XNNPACK_ENABLE_AVX512BF16 OFF)
+endif()
+
 set(XNNPACK_BUILD_ALL_MICROKERNELS
     OFF
     CACHE BOOL ""

tools/cmake/preset/pybind.cmake

@@ -21,16 +21,22 @@ set_overridable_option(EXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_DATA_LOADER ON)
 set_overridable_option(EXECUTORCH_BUILD_KERNELS_OPTIMIZED ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_MODULE ON)
-set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TRAINING ON)
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
   set_overridable_option(EXECUTORCH_BUILD_COREML ON)
+  set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TRAINING ON)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
   set_overridable_option(EXECUTORCH_BUILD_COREML ON)
+  set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TRAINING ON)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows" OR CMAKE_SYSTEM_NAME STREQUAL
                                                "WIN32"
 )
-  # Windows or other OS-specific code here
+  if(NOT CMAKE_GENERATOR_TOOLSET MATCHES "ClangCL")
+    message(
+      FATAL_ERROR
+        "ExecuTorch requires the ClangCL toolset on Windows. Please configure with -T ClangCL."
+    )
+  endif()
 else()
   message(
     FATAL_ERROR "Unsupported CMAKE_SYSTEM_NAME for pybind: ${CMAKE_SYSTEM_NAME}"

tools/cmake/preset/windows.cmake

@@ -9,15 +9,9 @@ set_overridable_option(EXECUTORCH_BUILD_EXTENSION_DATA_LOADER ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_EVALUE_UTIL ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_MODULE ON)
+set_overridable_option(EXECUTORCH_BUILD_EXECUTOR_RUNNER ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_RUNNER_UTIL ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TENSOR ON)
-
-# Below options are not yet buildable on Windows, but should be.
-set(EXECUTORCH_BUILD_PORTABLE_OPS
-    OFF
-    CACHE BOOL ""
-)
-# set_overridable_option(EXECUTORCH_BUILD_EXECUTOR_RUNNER ON)
-# set_overridable_option(EXECUTORCH_BUILD_KERNELS_OPTIMIZED ON)
-# set_overridable_option(EXECUTORCH_BUILD_KERNELS_QUANTIZED ON)
-# set_overridable_option(EXECUTORCH_BUILD_XNNPACK ON)
+set_overridable_option(EXECUTORCH_BUILD_KERNELS_OPTIMIZED ON)
+set_overridable_option(EXECUTORCH_BUILD_KERNELS_QUANTIZED ON)
+set_overridable_option(EXECUTORCH_BUILD_XNNPACK ON)