Linux x86 64 -> Linux aarch64 cross builds

.github/workflows/cpu_linux_x86_64_linux_aarch64_build.yaml

@@ -60,9 +60,85 @@ jobs:
             --platforms=//common:linux_aarch64 \
             //cc/tests/cpu:all
 
+      - name: "Clang 18, Glibc 2.27, libc++ static linking | Testing..."
+        run: |
+          bazel build --color=yes \
+            --platforms=//common:linux_aarch64 \
+            --@rules_ml_toolchain//common:stdlib=libc++ \
+            --@rules_ml_toolchain//common:static_libcxx=true \
+            //cc/tests/cpu:all
+
       - name: "Bzlmod. Clang 18, Glibc 2.27 | Testing..."
         run: |
           bazel build --color=yes \
             --platforms=//common:linux_aarch64 \
             --config=bzlmod \
             //cc/tests/cpu:all
+
+      - name: "Bzlmod. Clang 18, Glibc 2.27, libc++ static linking | Testing..."
+        run: |
+          bazel build --color=yes \
+            --platforms=//common:linux_aarch64 \
+            --@rules_ml_toolchain//common:stdlib=libc++ \
+            --@rules_ml_toolchain//common:static_libcxx=true \
+            --config=bzlmod \
+            //cc/tests/cpu:all
+
+      - name: "Clang 21, Glibc 2.31 | Testing..."
+        run: |
+          bazel build --color=yes \
+            --platforms=//common:linux_aarch64 \
+            --repo_env=LLVM_VERSION=21 \
+            --repo_env=SYSROOT_DIST=linux_glibc_2_31 \
+            //cc/tests/cpu:all
+
+      - name: "Bzlmod. Clang 21, Glibc 2.31 | Testing..."
+        run: |
+          bazel build --color=yes \
+            --platforms=//common:linux_aarch64 \
+            --repo_env=LLVM_VERSION=21 \
+            --repo_env=SYSROOT_DIST=linux_glibc_2_31 \
+            --config=bzlmod \
+            //cc/tests/cpu:all
+
+      # TODO: Replace `build` to `test` and run //cc/tests/cpu:all when GitHub runners will be updated to Ubuntu 24
+      - name: "Bzlmod. Clang 22, Glibc 2.31 | Testing..."
+        run: |
+          bazel build --color=yes \
+            --platforms=//common:linux_aarch64 \
+            --repo_env=LLVM_VERSION=22 \
+            --repo_env=SYSROOT_DIST=linux_glibc_2_31 \
+            --config=bzlmod \
+            //cc/tests/cpu:all
+
+      - name: "Clang 21, Glibc 2.31, libc++ static linking | Testing..."
+        run: |
+          bazel build --color=yes \
+            --platforms=//common:linux_aarch64 \
+            --repo_env=LLVM_VERSION=21 \
+            --repo_env=SYSROOT_DIST=linux_glibc_2_31 \
+            --@rules_ml_toolchain//common:stdlib=libc++ \
+            --@rules_ml_toolchain//common:static_libcxx=true \
+            //cc/tests/cpu:all
+
+      # TODO: Replace `build` to `test` and run //cc/tests/cpu:all when GitHub runners will be updated to Ubuntu 24
+      - name: "Clang 22, Glibc 2.31, libc++ static linking | Testing..."
+        run: |
+          bazel build --color=yes \
+            --platforms=//common:linux_aarch64 \
+            --repo_env=LLVM_VERSION=22 \
+            --repo_env=SYSROOT_DIST=linux_glibc_2_31 \
+            --@rules_ml_toolchain//common:stdlib=libc++ \
+            --@rules_ml_toolchain//common:static_libcxx=true \
+              //cc/tests/cpu:all
+
+      - name: "Bzlmod. Clang 22, Glibc 2.31, libc++ static linking | Testing..."
+        run: |
+          bazel build --color=yes \
+            --platforms=//common:linux_aarch64 \
+            --repo_env=LLVM_VERSION=22 \
+            --repo_env=SYSROOT_DIST=linux_glibc_2_31 \
+            --@rules_ml_toolchain//common:stdlib=libc++ \
+            --@rules_ml_toolchain//common:static_libcxx=true \
+            --config=bzlmod \
+            //cc/tests/cpu:all

README.md

@@ -135,16 +135,15 @@ When the executor and the target are the same, a non-hermetic GPU build can stil
 
 For details, look at the `.bazelrc` file, specifically the `cuda_clang_local` configuration.
 
-<!--
 ### Cross-platform builds
 Project supports cross-platform builds only on Linux x86_64 executor 
 and allows build for such targets:
 * Linux aarch64
-* macOS aarch64
+<!--* macOS aarch64-->
 
 #### Build for Linux aarch64
 `bazel build //cc/tests/cpu/... --platforms=//common:linux_aarch64`
-
+<!--
 #### Build for macOS aarch64
 [Prepare SDK](cc/sysroots/darwin_aarch64/README.md) before run the following command.
 

cc/impls/linux_x86_64_linux_aarch64/BUILD

@@ -17,8 +17,7 @@
 # Tools: Linux x86_64, Sysroot: Linux aarch64
 # ==============================================================================
 
-load("@rules_cc//cc:defs.bzl", "cc_toolchain")
-
+load("//cc/config:constants.bzl", "LIBCXX_FLAGS")
 load("//third_party/rules_cc_toolchain:toolchain_config.bzl", "cc_toolchain_config")
 load("//third_party/rules_cc_toolchain/features:cc_toolchain_import.bzl", "cc_toolchain_import")
 load("//third_party/rules_cc_toolchain/features:features.bzl", "cc_toolchain_import_feature")
@@ -49,15 +48,33 @@ cc_toolchain_import_feature(
     toolchain_import = ":startup_libs",
 )
 
+alias(
+    name = "std_incs",
+    actual = select({
+        "//common:is_stdlib_libcxx": "@llvm_linux_aarch64//:std_incs" ,
+        "//conditions:default": "@sysroot_linux_aarch64//:std_incs",
+    })
+)
+
+alias(
+    name = "std_libs",
+    actual = select({
+        "//common:is_stdlib_libcxx": "@llvm_linux_aarch64//:std_libs" ,
+        "//conditions:default": "@sysroot_linux_aarch64//:std_libs",
+    })
+)
+
 # buildifier: leave-alone
 cc_toolchain_import(
     name = "imports",
     deps = [
-        "@sysroot_linux_aarch64//:std_incs",
+        ":std_incs",
         "@llvm_linux_x86_64//:compiler_incs",
         "@sysroot_linux_aarch64//:sys_incs",
         "@sysroot_linux_aarch64//:sys_libs",
-        "@sysroot_linux_aarch64//:std_libs",
+        ":std_libs",
+        "@sysroot_linux_aarch64//:openmp",
+        "@llvm_linux_aarch64//:libclang_rt",
     ],
     visibility = ["//visibility:public"],
 )
@@ -66,6 +83,10 @@ cc_toolchain_import_feature(
     name = "imports_feature",
     enabled = True,
     toolchain_import = ":imports",
+    static_link_flags = select({
+        "//common:is_static_libcxx": LIBCXX_FLAGS,
+        "//conditions:default": [],
+    }),
 )
 
 # buildifier: leave-alone
@@ -83,7 +104,7 @@ filegroup(
 filegroup(
     name = "compiler",
     srcs = [
-        ":all",
+        ":imports",
         ":wrappers",
         "@llvm_linux_x86_64//:clang",
         "@llvm_linux_x86_64//:clang++",
@@ -134,51 +155,52 @@ filegroup(
     ],
 )
 
+FEATURES_ESSENTIAL = [
+    "//third_party/rules_cc_toolchain/features:hermetic_libraries",  # Hermetic libraries feature required before import
+    ":imports_feature",
+
+    # Toolchain configuration
+    "//third_party/rules_cc_toolchain/features:warnings",
+    "//third_party/rules_cc_toolchain/features:errors",
+    "//third_party/rules_cc_toolchain/features:reproducible",
+    "//third_party/rules_cc_toolchain/features:language",
+    "//third_party/rules_cc_toolchain/features:use_lld",
+    "//cc/features:sysroot_linux_aarch64",
+    ":startup_libs_feature",
+    "//third_party/rules_cc_toolchain/features:coverage",
+    #"//cc/features:clang19",    # TODO: Add a selection mechanism based on the Clang version
+
+    # PIC / PIE flags
+    "//third_party/rules_cc_toolchain/features:supports_pic",
+    "//third_party/rules_cc_toolchain/features:position_independent_code",
+    "//third_party/rules_cc_toolchain/features:position_independent_executable",
+
+    # Optimization flags
+    "//third_party/rules_cc_toolchain/features:garbage_collect_symbols",
+    "//cc/features:constants_merge",
+    "//cc/features:dbg",
+    "//cc/features:fastbuild",
+    "//cc/features:opt",
+    "//cc/features:detect_issues",
+    "//cc/features:detect_issues_ext",
+
+    # C++ standard flags
+    "//third_party/rules_cc_toolchain/features:c++11",
+    "//third_party/rules_cc_toolchain/features:c++14",
+    "//third_party/rules_cc_toolchain/features:c++17",
+
+    # Other flags
+    "//cc/features:allow_shlib_undefined",
+    "//cc/features:supports_dynamic_linker",
+    "//cc/features:supports_start_end_lib_feature",
+]
+
 cc_toolchain_config(
     name = "config",
     archiver = "@llvm_linux_x86_64//:ar",
     c_compiler = "@llvm_linux_x86_64//:clang",
     cc_compiler = "@llvm_linux_x86_64//:clang++",
-    compiler_features = [
-        # Hermetic libraries feature required before import.
-        "//third_party/rules_cc_toolchain/features:hermetic_libraries",
-        ":imports_feature",
-
-        # Toolchain configuration
-        "//third_party/rules_cc_toolchain/features:warnings",
-        "//third_party/rules_cc_toolchain/features:errors",
-        "//third_party/rules_cc_toolchain/features:reproducible",
-        "//third_party/rules_cc_toolchain/features:language",
-        "//third_party/rules_cc_toolchain/features:use_lld",
-        "//cc/features:sysroot_linux_aarch64",
-        ":startup_libs_feature",
-        "//third_party/rules_cc_toolchain/features:coverage",
-        #"//cc/features:clang19",    # TODO: Add a selection mechanism based on the Clang version
-
-        # PIC / PIE flags
-        "//third_party/rules_cc_toolchain/features:supports_pic",
-        "//third_party/rules_cc_toolchain/features:position_independent_code",
-        "//third_party/rules_cc_toolchain/features:position_independent_executable",
-
-        # Optimization flags
-        "//third_party/rules_cc_toolchain/features:garbage_collect_symbols",
-        "//cc/features:constants_merge",
-        "//cc/features:dbg",
-        "//cc/features:fastbuild",
-        "//cc/features:opt",
-        "//cc/features:detect_issues",
-        "//cc/features:detect_issues_ext",
-
-        # C++ standard configuration
-        "//third_party/rules_cc_toolchain/features:c++11",
-        "//third_party/rules_cc_toolchain/features:c++14",
-        "//third_party/rules_cc_toolchain/features:c++17",
-
-        #
-        "//cc/features:allow_shlib_undefined",
-        "//cc/features:supports_dynamic_linker",
-        "//cc/features:supports_start_end_lib_feature",
-    ],
+    compiler_features = FEATURES_ESSENTIAL,
     linker = "@llvm_linux_x86_64//:ld",
     strip_tool = "@llvm_linux_x86_64//:strip",
     target_cpu = "aarch64",
@@ -196,5 +218,5 @@ cc_toolchain(
     strip_files = ":strip",
     supports_param_files = 1,
     toolchain_config = ":config",
-    toolchain_identifier = "toolchain_id_linux_x86_64_linux_aarch64",
+    toolchain_identifier = "toolchain_id_linux_x86_64_linux_aarch64_id",
 )

cc/llvms/llvm.bzl

@@ -21,17 +21,6 @@ load(
 _LLVM_VERSION = "LLVM_VERSION"
 _STATIC_LIBCXX = "STATIC_LIBCXX"
 
-def _get_platform_arch(ctx):
-    """Gets current platform architecture"""
-    if ctx.os.arch == "amd64":
-        return "x86_64"
-    else:
-        return ctx.os.arch
-
-def _is_compatible_arch(ctx):
-    """Checks if LLVM compatible with current platform"""
-    return ctx.attr.name.endswith(_get_platform_arch(ctx))
-
 def _get_llvm_version_flag(ctx):
     """Returns LLVM version put as environment variable"""
     return get_host_environ(ctx, _LLVM_VERSION)
@@ -62,11 +51,6 @@ def _create_version_file(ctx, major_version):
     )
 
 def _llvm_impl(ctx):
-    if not _is_compatible_arch(ctx):
-        _create_version_file(ctx, "")
-        ctx.file("BUILD", "")
-        return
-
     ver = _get_llvm_version(ctx)
     llvm_label = _get_llvm_label(ctx, ver)
     if not llvm_label: