check_doc_keyword: don't alloc string for emptiness check

check_doc_alias_value: get argument as Symbol to prevent needless string convertions

check_doc_attrs: don't alloc vec, iterate over slice. Vec introduced in rust-lang#83149, but no perf run posted on merge

replace as_str() check with symbol check

get_single_str_from_tts: don't prealloc string

trivial string to str replace

LifetimeScopeForPath::NonElided use Vec<Symbol> instead of Vec<String>

AssertModuleSource use BTreeSet<Symbol> instead of BTreeSet<String>

CrateInfo.crate_name replace FxHashMap<CrateNum, String> with FxHashMap<CrateNum, Symbol>

src/driver/jit.rs

@@ -288,8 +288,8 @@ fn load_imported_symbols_for_jit(
         match data[cnum.as_usize() - 1] {
             Linkage::NotLinked | Linkage::IncludedFromDylib => {}
             Linkage::Static => {
-                let name = &crate_info.crate_name[&cnum];
-                let mut err = sess.struct_err(&format!("Can't load static lib {}", name.as_str()));
+                let name = crate_info.crate_name[&cnum];
+                let mut err = sess.struct_err(&format!("Can't load static lib {}", name));
                 err.note("rustc_codegen_cranelift can only load dylibs in JIT mode.");
                 err.emit();
             }