WasmLLVMRuntimeLibs: respect args.build_runtime_with_host_compiler (#82949)

This allows quickly building `WasmLLVMRuntimeLibs` product with the host toolchain (usually Swift nightly development snapshot toolchain) when `--skip-build-llvm --skip-build-swift --build-runtime-with-host-compiler` combination of options is passed to `build-script`.

Author: MaxDesiatov

utils/swift_build_support/swift_build_support/products/wasisysroot.py

@@ -147,10 +147,21 @@ def _build(self, host_target, enable_wasi_threads, compiler_rt_os_dir, target_tr
             build_dir=os.path.join(self.build_dir, target_triple))
 
         build_root = os.path.dirname(self.build_dir)
-        llvm_build_bin_dir = os.path.join(
-            '..', build_root, '%s-%s' % ('llvm', host_target), 'bin')
-        llvm_tools_path = cmake.args.native_llvm_tools_path or llvm_build_bin_dir
-        clang_tools_path = cmake.args.native_clang_tools_path or llvm_build_bin_dir
+
+        if self.args.build_runtime_with_host_compiler:
+            cc_path = self.toolchain.cc
+            cxx_path = self.toolchain.cxx
+            ar_path = self.toolchain.llvm_ar
+            ranlib_path = self.toolchain.llvm_ranlib
+        else:
+            llvm_build_bin_dir = os.path.join(
+                '..', build_root, '%s-%s' % ('llvm', host_target), 'bin')
+            llvm_tools_path = cmake.args.native_llvm_tools_path or llvm_build_bin_dir
+            clang_tools_path = cmake.args.native_clang_tools_path or llvm_build_bin_dir
+            ar_path = os.path.join(llvm_tools_path, 'llvm-ar')
+            ranlib_path = os.path.join(llvm_tools_path, 'llvm-ranlib')
+            cc_path = os.path.join(clang_tools_path, 'clang')
+            cxx_path = os.path.join(clang_tools_path, 'clang++')
 
         cmake_has_threads = 'TRUE' if enable_wasi_threads else 'FALSE'
 
@@ -181,14 +192,10 @@ def _build(self, host_target, enable_wasi_threads, compiler_rt_os_dir, target_tr
 
         cmake.cmake_options.define('CMAKE_SYSTEM_NAME:STRING', 'WASI')
         cmake.cmake_options.define('CMAKE_SYSTEM_PROCESSOR:STRING', 'wasm32')
-        cmake.cmake_options.define('CMAKE_AR:FILEPATH',
-                                   os.path.join(llvm_tools_path, 'llvm-ar'))
-        cmake.cmake_options.define('CMAKE_RANLIB:FILEPATH',
-                                   os.path.join(llvm_tools_path, 'llvm-ranlib'))
-        cmake.cmake_options.define('CMAKE_C_COMPILER:FILEPATH',
-                                   os.path.join(clang_tools_path, 'clang'))
-        cmake.cmake_options.define('CMAKE_CXX_COMPILER:STRING',
-                                   os.path.join(clang_tools_path, 'clang++'))
+        cmake.cmake_options.define('CMAKE_AR:FILEPATH', ar_path)
+        cmake.cmake_options.define('CMAKE_RANLIB:FILEPATH', ranlib_path)
+        cmake.cmake_options.define('CMAKE_C_COMPILER:FILEPATH', cc_path)
+        cmake.cmake_options.define('CMAKE_CXX_COMPILER:STRING', cxx_path)
 
         c_flags = []
         # Explicitly disable exceptions even though it's usually implicitly disabled by
@@ -234,7 +241,7 @@ def _build(self, host_target, enable_wasi_threads, compiler_rt_os_dir, target_tr
         cmake.cmake_options.define('UNIX:BOOL', 'TRUE')
 
         cmake.build_with_cmake([], cmake.args.build_variant, [],
-                               prefer_native_toolchain=True,
+                               prefer_native_toolchain=not self.args.build_runtime_with_host_compiler,
                                ignore_extra_cmake_options=True)
         cmake.install_with_cmake(
             ["install"], WASILibc.sysroot_install_path(build_root, target_triple))

utils/swift_build_support/swift_build_support/toolchain.py

@@ -68,6 +68,9 @@ def _getter(self):
 else:
     _register("ranlib", "ranlib")
     _register("ar", "ar")
+_register("llvm_ar", "llvm-ar")
+_register("llvm_nm", "llvm-nm")
+_register("llvm_ranlib", "llvm-ranlib")
 _register("sccache", "sccache")
 _register("swiftc", "swiftc")
 _register("swift_build", "swift-build")