Add support for Windows host and targets, ARM64 and x86_64

platforms/BUILD.bazel

@@ -93,3 +93,19 @@ platform(
         "@platforms//cpu:wasm64",
     ],
 )
+
+platform(
+    name = "windows-x86_64",
+    constraint_values = [
+        "@platforms//os:windows",
+        "@platforms//cpu:x86_64",
+    ],
+)
+
+platform(
+    name = "windows-aarch64",
+    constraint_values = [
+        "@platforms//os:windows",
+        "@platforms//cpu:aarch64",
+    ],
+)

toolchain/BUILD.llvm_repo.tpl

@@ -30,10 +30,13 @@ exports_files(glob(
 filegroup(
     name = "clang",
     srcs = [
-        "bin/clang",
-        "bin/clang++",
-        "bin/clang-cpp",
-    ],
+       "bin/clang",
+       "bin/clang++",
+       "bin/clang-cpp",
+    ] + glob([
+       "bin/clang-cl",
+       "bin/lld-link",
+    ], allow_empty = True),
 )
 
 filegroup(
@@ -42,7 +45,10 @@ filegroup(
     srcs = [
         "bin/ld.lld",
         "bin/ld64.lld",
-    ] + glob(["bin/wasm-ld"], allow_empty = True),
+    ] + glob([
+        "bin/wasm-ld",
+        "bin/lld-link",
+    ], allow_empty = True),
 )
 
 filegroup(

toolchain/BUILD.llvm_repo_windows.tpl

@@ -0,0 +1,209 @@
+# Copyright 2021 The Bazel Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+package(default_visibility = ["//visibility:public"])
+
+# Some targets may need to directly depend on these files.
+exports_files(glob(
+    [
+        "bin/*",
+        "lib/**",
+        "include/**",
+        "share/clang/*",
+    ],
+    allow_empty = True,
+))
+
+## LLVM toolchain files
+
+ALL_DLLS = glob(["bin/*.dll"], allow_empty=True)
+
+filegroup(
+    name = "clang",
+    srcs = [
+        "bin/clang.exe",
+        "bin/clang++.exe",
+        "bin/clang-cpp.exe",
+        "bin/clang-cl.exe",
+        "bin/lld-link.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "ld",
+    # Not all distributions contain wasm-ld.
+    srcs = [
+        "bin/ld.lld.exe",
+        "bin/ld64.lld.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "include",
+    srcs = glob(
+        [
+            "include/**/c++/**",
+            "lib/clang/*/include/**",
+        ],
+    ),
+)
+
+filegroup(
+    name = "all_includes",
+    srcs = glob(
+        ["include/**"],
+        allow_empty = True,
+    ),
+)
+
+# This filegroup should only have source directories, not individual files.
+# We rely on this assumption in system_module_map.bzl.
+filegroup(
+    name = "cxx_builtin_include",
+    srcs = [
+        "include/c++",
+        "lib/clang/{LLVM_VERSION}/include",
+    ],
+)
+
+filegroup(
+    name = "extra_config_site",
+    srcs = glob(["include/*/c++/v1/__config_site"], allow_empty = True)
+)
+
+filegroup(
+    name = "bin",
+    srcs = glob(["bin/**"]),
+)
+
+filegroup(
+    name = "lib",
+    srcs = [],
+)
+
+filegroup(
+    name = "lib_legacy",
+    srcs = [], # no reported Windows exec usage on older version of Bazel
+)
+
+filegroup(
+    name = "ar",
+    srcs = [
+        "bin/llvm-ar.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "as",
+    srcs = [
+        "bin/clang.exe",
+        "bin/llvm-as.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "nm",
+    srcs = [
+        "bin/llvm-nm.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "llvm-lib",
+    srcs = [
+        "bin/llvm-lib.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "objcopy",
+    srcs = [
+        "bin/llvm-objcopy.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "objdump",
+    srcs = [
+        "bin/llvm-objdump.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "profdata",
+    srcs = [
+        "bin/llvm-profdata.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "dwp",
+    srcs = [
+        "bin/llvm-dwp.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "ranlib",
+    srcs = [
+        "bin/llvm-ranlib.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "readelf",
+    srcs = [
+        "bin/llvm-readelf.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "strip",
+    srcs = [
+        "bin/llvm-strip.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "symbolizer",
+    srcs = [
+        "bin/llvm-symbolizer.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "clang-tidy",
+    srcs = [
+        "bin/clang-tidy.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "clang-format",
+    srcs = [
+        "bin/clang-format.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "git-clang-format",
+    srcs = [
+        "bin/git-clang-format.exe",
+    ] + ALL_DLLS,
+)
+
+filegroup(
+    name = "libclang",
+    srcs = ["lib/libclang.lib"],
+)

toolchain/aliases.bzl

@@ -27,4 +27,5 @@ aliased_tools = [
     "llvm-cov",
     "llvm-profdata",
     "llvm-symbolizer",
+    "llvm-rc",
 ]