remove pref_align_of intrinsic

Author: RalfJung

compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs

@@ -821,7 +821,7 @@ pub(crate) fn codegen_intrinsic_call<'tcx>(
             dest.write_cvalue(fx, val);
         };
 
-        pref_align_of | needs_drop | type_id | type_name | variant_count, () {
+        needs_drop | type_id | type_name | variant_count, () {
             let const_val =
                 fx.tcx.const_eval_instance(ParamEnv::reveal_all(), instance, None).unwrap();
             let val = crate::constant::codegen_const_value(

compiler/rustc_codegen_ssa/src/mir/intrinsic.rs

@@ -103,11 +103,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     bx.const_usize(bx.layout_of(tp_ty).align.abi.bytes())
                 }
             }
-            sym::pref_align_of
-            | sym::needs_drop
-            | sym::type_id
-            | sym::type_name
-            | sym::variant_count => {
+            sym::needs_drop | sym::type_id | sym::type_name | sym::variant_count => {
                 let value = bx
                     .tcx()
                     .const_eval_instance(ty::ParamEnv::reveal_all(), instance, None)

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -62,11 +62,6 @@ crate fn eval_nullary_intrinsic<'tcx>(
             ensure_monomorphic_enough(tcx, tp_ty)?;
             ConstValue::from_bool(tp_ty.needs_drop(tcx, param_env))
         }
-        sym::pref_align_of => {
-            // Correctly handles non-monomorphic calls, so there is no need for ensure_monomorphic_enough.
-            let layout = tcx.layout_of(param_env.and(tp_ty)).map_err(|e| err_inval!(Layout(e)))?;
-            ConstValue::from_machine_usize(layout.align.pref.bytes(), &tcx)
-        }
         sym::type_id => {
             ensure_monomorphic_enough(tcx, tp_ty)?;
             ConstValue::from_u64(tcx.type_id_hash(tp_ty))
@@ -155,14 +150,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 self.write_scalar(Scalar::from_machine_usize(result, self), dest)?;
             }
 
-            sym::pref_align_of
-            | sym::needs_drop
-            | sym::type_id
-            | sym::type_name
-            | sym::variant_count => {
+            sym::needs_drop | sym::type_id | sym::type_name | sym::variant_count => {
                 let gid = GlobalId { instance, promoted: None };
                 let ty = match intrinsic_name {
-                    sym::pref_align_of | sym::variant_count => self.tcx.types.usize,
+                    sym::variant_count => self.tcx.types.usize,
                     sym::needs_drop => self.tcx.types.bool,
                     sym::type_id => self.tcx.types.u64,
                     sym::type_name => self.tcx.mk_static_str(),

compiler/rustc_span/src/symbol.rs

@@ -981,7 +981,6 @@ symbols! {
         pre_dash_lto: "pre-lto",
         precise_pointer_size_matching,
         precision,
-        pref_align_of,
         prefetch_read_data,
         prefetch_read_instruction,
         prefetch_write_data,

compiler/rustc_typeck/src/check/intrinsic.rs

@@ -164,7 +164,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
             sym::abort => (0, Vec::new(), tcx.types.never),
             sym::unreachable => (0, Vec::new(), tcx.types.never),
             sym::breakpoint => (0, Vec::new(), tcx.mk_unit()),
-            sym::size_of | sym::pref_align_of | sym::min_align_of | sym::variant_count => {
+            sym::size_of | sym::min_align_of | sym::variant_count => {
                 (1, Vec::new(), tcx.types.usize)
             }
             sym::size_of_val | sym::min_align_of_val => {

library/core/src/intrinsics.rs

@@ -808,11 +808,6 @@ extern "rust-intrinsic" {
     /// The stabilized version of this intrinsic is [`core::mem::align_of`].
     #[rustc_const_stable(feature = "const_min_align_of", since = "1.40.0")]
     pub fn min_align_of<T>() -> usize;
-    /// The preferred alignment of a type.
-    ///
-    /// This intrinsic does not have a stable counterpart.
-    #[rustc_const_unstable(feature = "const_pref_align_of", issue = "none")]
-    pub fn pref_align_of<T>() -> usize;
 
     /// The size of the referenced value in bytes.
     ///