[Build] fix build issues for native Windows.

Added install_requirements.ps1 for build on native Windows.

Also fix issues block build on native Windows.

1. Get the Windows version of buck2 for Windows.
2. Check the path based on the build configuration for Windows in setup.py.
3. Avoid generating 'def flat.exe()' which is illegal python.
4. Add the Windows version of kernel_link_options.
5. Add links of pthreadpool and cpuinfo for custom_ops_aot_lib.
6. Define ssize_t for Windows.

Still have one link issue tracked with pytorch#4659.

For pytorch#4661

build/Utils.cmake

@@ -143,11 +143,21 @@ function(macos_kernel_link_options target_name)
   )
 endfunction()
 
+# Same as kernel_link_options but it's for MSVC linker
+function(msvc_kernel_link_options target_name)
+  target_link_options(
+    ${target_name} INTERFACE
+    "SHELL:LINKER:/WHOLEARCHIVE:$<TARGET_FILE:${target_name}>"
+  )
+endfunction()
+
 # Ensure that the load-time constructor functions run. By default, the linker
 # would remove them since there are no other references to them.
 function(target_link_options_shared_lib target_name)
   if(APPLE)
     macos_kernel_link_options(${target_name})
+  elseif(MSVC)
+    msvc_kernel_link_options(${target_name})
   else()
     kernel_link_options(${target_name})
   endif()

build/pip_data_bin_init.py.in

@@ -21,7 +21,9 @@ def _find_executable_files_under(dir):
     for filename in os.listdir(dir):
         filepath = os.path.join(dir, filename)
         if os.path.isfile(filepath) and os.access(filepath, os.X_OK):
-            bin_names.append(filename)
+            # avoid def flat.exe() on windows.
+            filename_without_ext = os.path.splitext(filename)[0]
+            bin_names.append(filename_without_ext)
     return bin_names
 
 # The list of binaries to create wrapper functions for.

build/resolve_buck.py

@@ -11,7 +11,6 @@
 import platform
 import stat
 import sys
-import tempfile
 import urllib.request
 
 from dataclasses import dataclass
@@ -85,6 +84,12 @@ class BuckInfo:
         archive_name="buck2-x86_64-apple-darwin.zst",
         target_versions=["3eb1ae97ea963086866b4d2d9ffa966d"],
     ),
+    ("windows", "x86_64"): BuckInfo(
+        archive_name="buck2-x86_64-pc-windows-msvc.exe.zst",
+        target_versions=[
+            "bf1685c4c4ddd9de4592b5a955cb7326fd01e6c4d5f561643422bed961a17401"
+        ],
+    ),
 }
 
 
@@ -135,6 +140,8 @@ def resolve_buck2(args: argparse.Namespace) -> Union[str, int]:
         os_family = "linux"
     elif sys.platform.startswith("darwin"):
         os_family = "darwin"
+    elif sys.platform.startswith("win"):
+        os_family = "windows"
 
     platform_key = (os_family, arch)
     if platform_key not in BUCK_PLATFORM_MAP:
@@ -193,12 +200,12 @@ def resolve_buck2(args: argparse.Namespace) -> Union[str, int]:
 
             buck2_archive_url = f"https://github.com/facebook/buck2/releases/download/{target_buck_version}/{buck_info.archive_name}"
 
-            with tempfile.NamedTemporaryFile() as archive_file:
+            try:
                 print(f"Downloading buck2 from {buck2_archive_url}...", file=sys.stderr)
-                urllib.request.urlretrieve(buck2_archive_url, archive_file.name)
+                archive_file, _ = urllib.request.urlretrieve(buck2_archive_url)
 
                 # Extract and chmod.
-                with open(archive_file.name, "rb") as f:
+                with open(archive_file, "rb") as f:
                     data = f.read()
                     decompressed_bytes = zstd.decompress(data)
 
@@ -207,6 +214,8 @@ def resolve_buck2(args: argparse.Namespace) -> Union[str, int]:
 
                 file_stat = os.stat(buck2_local_path)
                 os.chmod(buck2_local_path, file_stat.st_mode | stat.S_IEXEC)
+            finally:
+                os.remove(archive_file)
 
             return buck2_local_path
 

extension/data_loader/file_data_loader.cpp

@@ -17,7 +17,16 @@
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#ifndef _WIN32
 #include <unistd.h>
+#else
+#include <io.h>
+#endif
+
+#ifdef _WIN32
+#include <stddef.h>
+using ssize_t = ptrdiff_t;
+#endif
 
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/result.h>
@@ -58,6 +67,10 @@ FileDataLoader::~FileDataLoader() {
   std::free(const_cast<char*>(file_name_));
   // fd_ can be -1 if this instance was moved from, but closing a negative fd is
   // safe (though it will return an error).
+#ifdef _WIN32
+  if (fd_ == -1)
+    return;
+#endif
   ::close(fd_);
 }
 

extension/llm/custom_ops/CMakeLists.txt

@@ -101,6 +101,9 @@ if(EXECUTORCH_BUILD_KERNELS_CUSTOM_AOT)
   endif()
 
   target_link_libraries(custom_ops_aot_lib PUBLIC cpublas torch)
+  if(WIN32)
+    target_link_libraries(custom_ops_aot_lib PUBLIC pthreadpool cpuinfo)
+  endif()
   target_compile_options(
     custom_ops_aot_lib
     PUBLIC -Wno-deprecated-declarations -fPIC -frtti -fexceptions

runtime/core/exec_aten/util/tensor_util.h

@@ -15,6 +15,11 @@
 #include <cstddef> // size_t
 #include <limits>
 
+#ifdef _WIN32
+#include <stddef.h>
+using ssize_t = ptrdiff_t;
+#endif
+
 #include <executorch/runtime/core/array_ref.h>
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/exec_aten/exec_aten.h>

runtime/core/portable_type/tensor_impl.h

@@ -8,7 +8,12 @@
 
 #pragma once
 
+#ifndef _WIN32
 #include <sys/types.h> // TODO(T126923429): Include size_t, ssize_t
+#else
+#include <stddef.h>
+using ssize_t = ptrdiff_t;
+#endif
 
 #include <executorch/runtime/core/array_ref.h>
 #include <executorch/runtime/core/error.h>

setup.py

@@ -189,9 +189,9 @@ def src_path(self, installer: "InstallerBuildExt") -> Path:
             installer: The InstallerBuildExt instance that is installing the
                 file.
         """
-        # TODO(dbort): share the cmake-out location with CustomBuild. Can get a
-        # handle with installer.get_finalized_command('build')
-        cmake_cache_dir: Path = Path().cwd() / installer.build_temp / "cmake-out"
+        # share the cmake-out location with CustomBuild.
+        # Get a handle with installer.get_finalized_command('build')
+        cmake_cache_dir = Path(installer.get_finalized_command("build").cmake_cache_dir)
 
         # Construct the full source path, resolving globs. If there are no glob
         # pattern characters, this will just ensure that the source file exists.
@@ -397,7 +397,7 @@ def __init__(self):
         self.saved_env = {}
 
     def __enter__(self):
-        if os.geteuid() == 0 and "HOME" in os.environ:
+        if os.name != "nt" and os.geteuid() == 0 and "HOME" in os.environ:
             log.info("temporarily unsetting HOME while running as root")
             self.saved_env["HOME"] = os.environ.pop("HOME")
         return self
@@ -508,6 +508,9 @@ def run(self):
                 item for item in os.environ["CMAKE_BUILD_ARGS"].split(" ") if item
             ]
 
+        if os.name == "nt":
+            build_args += ["--config", cfg]
+
         # Put the cmake cache under the temp directory, like
         # "pip-out/temp.<plat>/cmake-out".
         cmake_cache_dir = os.path.join(repo_root, self.build_temp, "cmake-out")
@@ -545,6 +548,8 @@ def run(self):
             "build/pip_data_bin_init.py.in",
             os.path.join(bin_dir, "__init__.py"),
         )
+        # share the cmake-out location with _BaseExtension.
+        self.cmake_cache_dir = cmake_cache_dir
 
         # Finally, run the underlying subcommands like build_py, build_ext.
         build.run(self)
@@ -553,11 +558,21 @@ def run(self):
 def get_ext_modules() -> List[Extension]:
     """Returns the set of extension modules to build."""
 
+    debug = os.environ.get("DEBUG", 0)
+    cfg = "Debug" if debug else "Release"
+
     ext_modules = []
     if ShouldBuild.flatc():
-        ext_modules.append(
-            BuiltFile("third-party/flatbuffers/flatc", "executorch/data/bin/")
-        )
+        if os.name == "nt":
+            ext_modules.append(
+                BuiltFile(
+                    f"third-party/flatbuffers/{cfg}/flatc.exe", "executorch/data/bin/"
+                )
+            )
+        else:
+            ext_modules.append(
+                BuiltFile("third-party/flatbuffers/flatc", "executorch/data/bin/")
+            )
 
     if ShouldBuild.pybindings():
         ext_modules.append(
@@ -569,20 +584,35 @@ def get_ext_modules() -> List[Extension]:
             )
         )
     if ShouldBuild.llama_custom_ops():
-        ext_modules.append(
-            # Install the prebuilt library for custom ops used in llama.
-            BuiltFile(
-                "extension/llm/custom_ops/libcustom_ops_aot_lib.*",
-                "executorch/extension/llm/custom_ops/",
+        if os.name == "nt":
+            ext_modules.append(
+                BuiltFile(
+                    f"extension/llm/custom_ops/{cfg}/custom_ops_aot_lib.dll",
+                    "executorch/extension/llm/custom_ops",
+                )
             )
-        )
-        ext_modules.append(
-            # Install the prebuilt library for quantized ops required by custom ops.
-            BuiltFile(
-                "kernels/quantized/libquantized_ops_aot_lib.*",
-                "executorch/kernels/quantized/",
+            ext_modules.append(
+                # Install the prebuilt library for quantized ops required by custom ops.
+                BuiltFile(
+                    f"kernels/quantized/{cfg}/quantized_ops_aot_lib.dll",
+                    "executorch/kernels/quantized/",
+                )
+            )
+        else:
+            ext_modules.append(
+                # Install the prebuilt library for custom ops used in llama.
+                BuiltFile(
+                    "extension/llm/custom_ops/libcustom_ops_aot_lib.*",
+                    "executorch/extension/llm/custom_ops/",
+                )
+            )
+            ext_modules.append(
+                # Install the prebuilt library for quantized ops required by custom ops.
+                BuiltFile(
+                    "kernels/quantized/libquantized_ops_aot_lib.*",
+                    "executorch/kernels/quantized/",
+                )
             )
-        )
 
     # Note that setuptools uses the presence of ext_modules as the main signal
     # that a wheel is platform-specific. If we install any platform-specific