src/bin/build-llvm: add utility to build llvm project

.gitignore

@@ -1,5 +1,2 @@
 out
 node_modules
-
-# Some executable folder that are intended to be invoked on-the-fly.
-/src/bin

src/bin/build-llvm.ts

@@ -0,0 +1,46 @@
+import yargs from 'yargs';
+import { hideBin } from 'yargs/helpers';
+import { llvmPackages } from '../build/llvmPackages.js';
+import path from 'path';
+import { buildPackage } from '../build/build.js';
+import { randomUUID } from 'crypto';
+import { arch } from 'os';
+
+const args = await yargs(hideBin(process.argv))
+    .version("0.0.0")
+    .option("src", {
+        describe: "Source directory to llvm-project",
+        demandOption: true,
+        type: "string",
+    })
+    .option("build", {
+        describe: "Build directory",
+        type: "string",
+    })
+    .option("prefix", {
+        describe: "Install prefix",
+        type: "string",
+    })
+    .help()
+    .parse();
+
+const src = path.resolve(args.src);
+const build = args.build ?? path.resolve(src, "build");
+const prefix = args.prefix ?? path.resolve(src, "install", randomUUID());
+
+const packages = llvmPackages({
+    src: args.src,
+    buildDir(packageName) {
+        return path.join(build, packageName);
+    },
+    installPrefix: prefix,
+    // FIXME: arguments to platform?
+    platform: {
+        buildPlatform: { arch: arch() },
+        hostPlatform: { arch: arch() },
+    }
+});
+
+for (const pkg of packages) {
+    await buildPackage(pkg);
+}