Add inline to pure field-access accessors

These accessors have pure field/index accesses -- no calls.  The
auto-inline heuristic from Rust PR 116505 should already cover these.
Let's annotate to confirm that in profiling.

Maybe or maybe not we'd want to add these anyway as documentation of
intent and a safety net against later changes that would cause the
heuristic to fail.

Author: traviscross

compiler/rustc_ast_ir/src/visit.rs

@@ -16,9 +16,13 @@ impl VisitorResult for () {
     #[cfg(not(feature = "nightly"))]
     type Residual = core::convert::Infallible;
 
+    #[inline]
     fn output() -> Self {}
+    #[inline]
     fn from_residual(_: Self::Residual) -> Self {}
+    #[inline]
     fn from_branch(_: ControlFlow<Self::Residual>) -> Self {}
+    #[inline]
     fn branch(self) -> ControlFlow<Self::Residual> {
         ControlFlow::Continue(())
     }
@@ -27,15 +31,19 @@ impl VisitorResult for () {
 impl<T> VisitorResult for ControlFlow<T> {
     type Residual = T;
 
+    #[inline]
     fn output() -> Self {
         ControlFlow::Continue(())
     }
+    #[inline]
     fn from_residual(residual: Self::Residual) -> Self {
         ControlFlow::Break(residual)
     }
+    #[inline]
     fn from_branch(b: Self) -> Self {
         b
     }
+    #[inline]
     fn branch(self) -> Self {
         self
     }

compiler/rustc_middle/src/ty/consts.rs

@@ -40,10 +40,12 @@ impl<'tcx> rustc_type_ir::inherent::IntoKind for Const<'tcx> {
 }
 
 impl<'tcx> rustc_type_ir::Flags for Const<'tcx> {
+    #[inline]
     fn flags(&self) -> TypeFlags {
         self.0.flags
     }
 
+    #[inline]
     fn outer_exclusive_binder(&self) -> rustc_type_ir::DebruijnIndex {
         self.0.outer_exclusive_binder
     }

compiler/rustc_middle/src/ty/consts/kind.rs

@@ -23,6 +23,7 @@ pub struct Expr<'tcx> {
 }
 
 impl<'tcx> rustc_type_ir::inherent::ExprConst<TyCtxt<'tcx>> for Expr<'tcx> {
+    #[inline]
     fn args(self) -> ty::GenericArgsRef<'tcx> {
         self.args
     }

compiler/rustc_middle/src/ty/consts/valtree.rs

@@ -80,6 +80,7 @@ impl fmt::Debug for ValTree<'_> {
 impl<'tcx> rustc_type_ir::inherent::IntoKind for ty::ValTree<'tcx> {
     type Kind = ty::ValTreeKind<TyCtxt<'tcx>>;
 
+    #[inline]
     fn kind(self) -> Self::Kind {
         *self.0
     }
@@ -226,10 +227,12 @@ impl<'tcx> Value<'tcx> {
 }
 
 impl<'tcx> rustc_type_ir::inherent::ValueConst<TyCtxt<'tcx>> for Value<'tcx> {
+    #[inline]
     fn ty(self) -> Ty<'tcx> {
         self.ty
     }
 
+    #[inline]
     fn valtree(self) -> ValTree<'tcx> {
         self.valtree
     }

compiler/rustc_middle/src/ty/context.rs

@@ -86,10 +86,12 @@ impl<'tcx> rustc_type_ir::inherent::DefId<TyCtxt<'tcx>> for DefId {
 }
 
 impl<'tcx> rustc_type_ir::inherent::Safety<TyCtxt<'tcx>> for hir::Safety {
+    #[inline]
     fn safe() -> Self {
         hir::Safety::Safe
     }
 
+    #[inline]
     fn unsafe_mode() -> Self {
         hir::Safety::Unsafe
     }
@@ -131,6 +133,7 @@ impl<'tcx> rustc_type_ir::inherent::Features<TyCtxt<'tcx>> for &'tcx rustc_featu
 }
 
 impl<'tcx> rustc_type_ir::inherent::Span<TyCtxt<'tcx>> for Span {
+    #[inline]
     fn dummy() -> Self {
         DUMMY_SP
     }

compiler/rustc_middle/src/ty/mod.rs

@@ -487,10 +487,12 @@ impl<'tcx> rustc_type_ir::inherent::IntoKind for Ty<'tcx> {
 }
 
 impl<'tcx> rustc_type_ir::Flags for Ty<'tcx> {
+    #[inline]
     fn flags(&self) -> TypeFlags {
         self.0.flags
     }
 
+    #[inline]
     fn outer_exclusive_binder(&self) -> DebruijnIndex {
         self.0.outer_exclusive_binder
     }

compiler/rustc_middle/src/ty/pattern.rs

@@ -115,6 +115,7 @@ impl<'tcx> IrPrint<PatternKind<'tcx>> for TyCtxt<'tcx> {
 
 impl<'tcx> rustc_type_ir::inherent::IntoKind for Pattern<'tcx> {
     type Kind = PatternKind<'tcx>;
+    #[inline]
     fn kind(self) -> Self::Kind {
         *self
     }

compiler/rustc_middle/src/ty/predicate.rs

@@ -63,10 +63,12 @@ impl<'tcx> rustc_type_ir::inherent::IntoKind for Predicate<'tcx> {
 }
 
 impl<'tcx> rustc_type_ir::Flags for Predicate<'tcx> {
+    #[inline]
     fn flags(&self) -> TypeFlags {
         self.0.flags
     }
 
+    #[inline]
     fn outer_exclusive_binder(&self) -> ty::DebruijnIndex {
         self.0.outer_exclusive_binder
     }

compiler/rustc_middle/src/ty/region.rs

@@ -19,6 +19,7 @@ pub struct Region<'tcx>(pub Interned<'tcx, RegionKind<'tcx>>);
 impl<'tcx> rustc_type_ir::inherent::IntoKind for Region<'tcx> {
     type Kind = RegionKind<'tcx>;
 
+    #[inline]
     fn kind(self) -> RegionKind<'tcx> {
         *self.0.0
     }
@@ -183,6 +184,7 @@ impl<'tcx> rustc_type_ir::inherent::Region<TyCtxt<'tcx>> for Region<'tcx> {
         Region::new_placeholder(tcx, placeholder)
     }
 
+    #[inline]
     fn new_static(tcx: TyCtxt<'tcx>) -> Self {
         tcx.lifetimes.re_static
     }
@@ -368,6 +370,7 @@ impl EarlyParamRegion {
 }
 
 impl rustc_type_ir::inherent::ParamLike for EarlyParamRegion {
+    #[inline]
     fn index(self) -> u32 {
         self.index
     }

compiler/rustc_middle/src/ty/sty.rs

@@ -285,6 +285,7 @@ pub struct ParamTy {
 }
 
 impl rustc_type_ir::inherent::ParamLike for ParamTy {
+    #[inline]
     fn index(self) -> u32 {
         self.index
     }
@@ -319,6 +320,7 @@ pub struct ParamConst {
 }
 
 impl rustc_type_ir::inherent::ParamLike for ParamConst {
+    #[inline]
     fn index(self) -> u32 {
         self.index
     }
@@ -927,10 +929,12 @@ impl<'tcx> Ty<'tcx> {
 }
 
 impl<'tcx> rustc_type_ir::inherent::Ty<TyCtxt<'tcx>> for Ty<'tcx> {
+    #[inline]
     fn new_bool(tcx: TyCtxt<'tcx>) -> Self {
         tcx.types.bool
     }
 
+    #[inline]
     fn new_u8(tcx: TyCtxt<'tcx>) -> Self {
         tcx.types.u8
     }
@@ -1130,10 +1134,12 @@ impl<'tcx> rustc_type_ir::inherent::Ty<TyCtxt<'tcx>> for Ty<'tcx> {
         Ty::new_unsafe_binder(interner, ty)
     }
 
+    #[inline]
     fn new_unit(interner: TyCtxt<'tcx>) -> Self {
         interner.types.unit
     }
 
+    #[inline]
     fn new_usize(interner: TyCtxt<'tcx>) -> Self {
         interner.types.usize
     }
@@ -2191,6 +2197,7 @@ impl<'tcx> rustc_type_ir::inherent::Tys<TyCtxt<'tcx>> for &'tcx ty::List<Ty<'tcx
 }
 
 impl<'tcx> rustc_type_ir::inherent::Symbol<TyCtxt<'tcx>> for Symbol {
+    #[inline]
     fn is_kw_underscore_lifetime(self) -> bool {
         self == kw::UnderscoreLifetime
     }