Shrink `TyKind::FnPtr`.

By splitting the `FnSig` within `TyKind::FnPtr` into `FnSigTys` and
`FnHeader`, which can be packed more efficiently. This reduces the size
of the hot `TyKind` type from 32 bytes to 24 bytes on 64-bit platforms.
This reduces peak memory usage by a few percent on some benchmarks. It
also reduces cache misses and page faults similarly, though this doesn't
translate to clear cycles or wall-time improvements on CI.

1 files changed, 3 insertions, 3 deletions

diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 29d72183dd3..2dd0caf4f87 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -696,7 +696,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     p!(print(sig), " {{", print_value_path(def_id, args), "}}");
                 }
             }
-            ty::FnPtr(ref bare_fn) => p!(print(bare_fn)),
+            ty::FnPtr(ref sig_tys, hdr) => p!(print(sig_tys.with(hdr))),
             ty::Infer(infer_ty) => {
                 if self.should_print_verbose() {
                     p!(write("{:?}", ty.kind()));
@@ -1678,7 +1678,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     }
                 }
             }
-            ty::FnPtr(_) => {
+            ty::FnPtr(..) => {
                 // FIXME: We should probably have a helper method to share code with the "Byte strings"
                 // printing above (which also has to handle pointers to all sorts of things).
                 if let Some(GlobalAlloc::Function { instance, .. }) =
@@ -1741,7 +1741,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                 p!(write("{:?}", char::try_from(int).unwrap()))
             }
             // Pointer types
-            ty::Ref(..) | ty::RawPtr(_, _) | ty::FnPtr(_) => {
+            ty::Ref(..) | ty::RawPtr(_, _) | ty::FnPtr(..) => {
                 let data = int.to_bits(self.tcx().data_layout.pointer_size);
                 self.typed_value(
                     |this| {