lib/codegen-meta moved into lib/codegen. (#423)

* lib/codegen-meta moved into lib/codegen.

* Renamed codegen-meta and existing meta.

lib/codegen/meta-python/build.py

@@ -0,0 +1,40 @@
+# Second-level build script.
+#
+# This script is run from lib/codegen/build.rs to generate Rust files.
+
+from __future__ import absolute_import
+import argparse
+import isa
+import gen_types
+import gen_instr
+import gen_settings
+import gen_build_deps
+import gen_encoding
+import gen_legalizer
+import gen_registers
+import gen_binemit
+
+
+def main():
+    # type: () -> None
+    parser = argparse.ArgumentParser(
+            description='Generate sources for Cranelift.')
+    parser.add_argument('--out-dir', help='set output directory')
+
+    args = parser.parse_args()
+    out_dir = args.out_dir
+
+    isas = isa.all_isas()
+
+    gen_types.generate(out_dir)
+    gen_instr.generate(isas, out_dir)
+    gen_settings.generate(isas, out_dir)
+    gen_encoding.generate(isas, out_dir)
+    gen_legalizer.generate(isas, out_dir)
+    gen_registers.generate(isas, out_dir)
+    gen_binemit.generate(isas, out_dir)
+    gen_build_deps.generate()
+
+
+if __name__ == "__main__":
+    main()