[experiment] Treat unoptimized always as usually

Author: saethlin

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -525,7 +525,11 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                         .emit();
                     InlineAttr::None
                 } else if list_contains_name(items, sym::always) {
-                    InlineAttr::Usually
+                    if tcx.sess.opts.optimize == rustc_session::config::OptLevel::No {
+                        InlineAttr::Usually
+                    } else {
+                        InlineAttr::Always
+                    }
                 } else if list_contains_name(items, sym::never) {
                     InlineAttr::Never
                 } else if list_contains_name(items, sym::usually) {