Compute generator sizes with -Zprint_type_sizes

Author: compiler-errors

compiler/rustc_session/src/code_stats.rs

@@ -33,6 +33,7 @@ pub enum DataTypeKind {
     Union,
     Enum,
     Closure,
+    Generator,
 }
 
 #[derive(PartialEq, Eq, Hash, Debug)]
@@ -113,7 +114,7 @@ impl CodeStats {
             let mut max_variant_size = discr_size;
 
             let struct_like = match kind {
-                DataTypeKind::Struct | DataTypeKind::Closure => true,
+                DataTypeKind::Struct | DataTypeKind::Closure | DataTypeKind::Generator => true,
                 DataTypeKind::Enum | DataTypeKind::Union => false,
             };
             for (i, variant_info) in variants.into_iter().enumerate() {

compiler/rustc_ty_utils/src/layout.rs

@@ -826,6 +826,12 @@ fn record_layout_for_printing_outlined<'tcx>(
             return;
         }
 
+        ty::Generator(..) => {
+            debug!("print-type-size t: `{:?}` record generator", layout.ty);
+            record(DataTypeKind::Generator, false, None, vec![]);
+            return;
+        }
+
         _ => {
             debug!("print-type-size t: `{:?}` skip non-nominal", layout.ty);
             return;

src/test/ui/print_type_sizes/async.rs

@@ -0,0 +1,19 @@
+// compile-flags: -Z print-type-sizes
+// edition:2021
+// build-pass
+// ignore-pass
+
+#![feature(start)]
+
+async fn wait() {}
+
+async fn test(arg: [u8; 8192]) {
+    wait().await;
+    drop(arg);
+}
+
+#[start]
+fn start(_: isize, _: *const *const u8) -> isize {
+    let _ = test([0; 8192]);
+    0
+}

src/test/ui/print_type_sizes/async.stdout

@@ -0,0 +1,25 @@
+print-type-size type: `[static generator@$DIR/async.rs:10:32: 13:2]`: 16386 bytes, alignment: 1 bytes
+print-type-size     end padding: 16386 bytes
+print-type-size type: `std::future::from_generator::GenFuture<[static generator@$DIR/async.rs:10:32: 13:2]>`: 16386 bytes, alignment: 1 bytes
+print-type-size     field `.0`: 16386 bytes
+print-type-size type: `std::mem::ManuallyDrop<[u8; 8192]>`: 8192 bytes, alignment: 1 bytes
+print-type-size     field `.value`: 8192 bytes
+print-type-size type: `std::mem::MaybeUninit<[u8; 8192]>`: 8192 bytes, alignment: 1 bytes
+print-type-size     variant `MaybeUninit`: 8192 bytes
+print-type-size         field `.uninit`: 0 bytes
+print-type-size         field `.value`: 8192 bytes
+print-type-size type: `[static generator@$DIR/async.rs:8:17: 8:19]`: 1 bytes, alignment: 1 bytes
+print-type-size     end padding: 1 bytes
+print-type-size type: `std::future::from_generator::GenFuture<[static generator@$DIR/async.rs:8:17: 8:19]>`: 1 bytes, alignment: 1 bytes
+print-type-size     field `.0`: 1 bytes
+print-type-size type: `std::mem::ManuallyDrop<std::future::from_generator::GenFuture<[static generator@$DIR/async.rs:8:17: 8:19]>>`: 1 bytes, alignment: 1 bytes
+print-type-size     field `.value`: 1 bytes
+print-type-size type: `std::mem::MaybeUninit<std::future::from_generator::GenFuture<[static generator@$DIR/async.rs:8:17: 8:19]>>`: 1 bytes, alignment: 1 bytes
+print-type-size     variant `MaybeUninit`: 1 bytes
+print-type-size         field `.uninit`: 0 bytes
+print-type-size         field `.value`: 1 bytes
+print-type-size type: `std::task::Poll<()>`: 1 bytes, alignment: 1 bytes
+print-type-size     discriminant: 1 bytes
+print-type-size     variant `Ready`: 0 bytes
+print-type-size         field `.0`: 0 bytes
+print-type-size     variant `Pending`: 0 bytes

src/test/ui/print_type_sizes/generator.rs

@@ -0,0 +1,20 @@
+// compile-flags: -Z print-type-sizes
+// build-pass
+// ignore-pass
+
+#![feature(start, generators, generator_trait)]
+
+use std::ops::Generator;
+
+fn generator<const C: usize>(array: [u8; C]) -> impl Generator<Yield = (), Return = ()> {
+    move |()| {
+        yield ();
+        let _ = array;
+    }
+}
+
+#[start]
+fn start(_: isize, _: *const *const u8) -> isize {
+    let _ = generator([0; 8192]);
+    0
+}

src/test/ui/print_type_sizes/generator.stdout

@@ -0,0 +1,2 @@
+print-type-size type: `[generator@$DIR/generator.rs:10:5: 10:14]`: 8193 bytes, alignment: 1 bytes
+print-type-size     end padding: 8193 bytes