enable custom llvm build flags (bytecodealliance#2000)

build-scripts/build_llvm.py

@@ -47,7 +47,7 @@ def query_llvm_version(llvm_info):
     return response['sha']
 
 
-def build_llvm(llvm_dir, platform, backends, projects, use_clang=False):
+def build_llvm(llvm_dir, platform, backends, projects, use_clang=False, extra_flags=''):
     LLVM_COMPILE_OPTIONS = [
         '-DCMAKE_BUILD_TYPE:STRING="Release"',
         "-DCMAKE_EXPORT_COMPILE_COMMANDS=ON",
@@ -143,7 +143,7 @@ def build_llvm(llvm_dir, platform, backends, projects, use_clang=False):
         + LLVM_INCLUDE_TOOLS_OPTION
     )
 
-    CONFIG_CMD = f"cmake {compile_options} ../llvm"
+    CONFIG_CMD = f"cmake {compile_options} {extra_flags} ../llvm"
     if "windows" == platform:
         if "mingw" in sysconfig.get_platform().lower():
             CONFIG_CMD += " -G'Unix Makefiles'"
@@ -227,6 +227,12 @@ def main():
         action="store_true",
         help="use clang instead of gcc",
     )
+    parser.add_argument(
+        "--extra-cmake-flags",
+        type=str,
+        default="",
+        help="custom extra cmake flags",
+    )
     options = parser.parse_args()
 
     # if the "platform" is not identified in the command line option,
@@ -275,7 +281,8 @@ def main():
         llvm_dir = clone_llvm(deps_dir, llvm_info["repo"], llvm_info["branch"])
         if (
             build_llvm(
-                llvm_dir, platform, options.arch, options.project, options.use_clang
+                llvm_dir, platform, options.arch, options.project, options.use_clang,
+                options.extra_cmake_flags
             )
             is not None
         ):