Rollup merge of #72689 - lcnr:common_str, r=estebank

add str to common types

I already expected this to be the case and it may slightly improve perf.

Afaict if we ever want to change str into a lang item this would have to get reverted.
As that would be fairly simple I don't believe this to cause any problems in the future.

src/librustc_codegen_llvm/common.rs

@@ -206,7 +206,7 @@ impl ConstMethods<'tcx> for CodegenCx<'ll, 'tcx> {
         let len = s.as_str().len();
         let cs = consts::ptrcast(
             self.const_cstr(s, false),
-            self.type_ptr_to(self.layout_of(self.tcx.mk_str()).llvm_type(self)),
+            self.type_ptr_to(self.layout_of(self.tcx.types.str_).llvm_type(self)),
         );
         (cs, self.const_usize(len as u64))
     }

src/librustc_middle/ty/context.rs

@@ -143,6 +143,7 @@ pub struct CommonTypes<'tcx> {
     pub u128: Ty<'tcx>,
     pub f32: Ty<'tcx>,
     pub f64: Ty<'tcx>,
+    pub str_: Ty<'tcx>,
     pub never: Ty<'tcx>,
     pub self_param: Ty<'tcx>,
 
@@ -816,6 +817,7 @@ impl<'tcx> CommonTypes<'tcx> {
             u128: mk(Uint(ast::UintTy::U128)),
             f32: mk(Float(ast::FloatTy::F32)),
             f64: mk(Float(ast::FloatTy::F64)),
+            str_: mk(Str),
             self_param: mk(ty::Param(ty::ParamTy { index: 0, name: kw::SelfUpper })),
 
             trait_object_dummy_self: mk(Infer(ty::FreshTy(0))),
@@ -2149,14 +2151,9 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
-    #[inline]
-    pub fn mk_str(self) -> Ty<'tcx> {
-        self.mk_ty(Str)
-    }
-
     #[inline]
     pub fn mk_static_str(self) -> Ty<'tcx> {
-        self.mk_imm_ref(self.lifetimes.re_static, self.mk_str())
+        self.mk_imm_ref(self.lifetimes.re_static, self.types.str_)
     }
 
     #[inline]

src/librustc_typeck/astconv.rs

@@ -2787,7 +2787,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     hir::PrimTy::Int(it) => tcx.mk_mach_int(it),
                     hir::PrimTy::Uint(uit) => tcx.mk_mach_uint(uit),
                     hir::PrimTy::Float(ft) => tcx.mk_mach_float(ft),
-                    hir::PrimTy::Str => tcx.mk_str(),
+                    hir::PrimTy::Str => tcx.types.str_,
                 }
             }
             Res::Err => {