Port metadata reuse to cg_clif.

Author: cjgillot

compiler/rustc_codegen_cranelift/src/driver/aot.rs

@@ -56,6 +56,21 @@ impl OngoingCodegen {
         backend_config: &BackendConfig,
     ) -> (CodegenResults, FxIndexMap<WorkProductId, WorkProduct>) {
         let mut work_products = FxIndexMap::default();
+
+        if !backend_config.disable_incr_cache {
+            if let Some(path) = self.metadata.path() {
+                if let Some((id, product)) =
+                    rustc_incremental::copy_cgu_workproduct_to_incr_comp_cache_dir(
+                        sess,
+                        "metadata",
+                        &[("rmeta", path)],
+                    )
+                {
+                    work_products.insert(id, product);
+                }
+            }
+        }
+
         let mut modules = vec![];
 
         for module_codegen in self.modules {