Rollup merge of rust-lang#107533 - pnkfelix:distinguish-generator-state-in-print-type-sizes, r=compiler-errors

Extend `-Z print-type-sizes` to distinguish generator upvars+locals from "normal" fields.

For example, for this code:

```rust
async fn wait() {}

async fn test(arg: [u8; 8192]) {
    wait().await;
    drop(arg);
}

async fn test_ideal(_rg: [u8; 8192]) {
    wait().await;
    // drop(arg);
}

fn main() {
    let gen_t = test([0; 8192]);
    let gen_i = test_ideal([0; 8192]);
    println!("expect {}, got: {}",
             std::mem::size_of_val(&gen_i),
             std::mem::size_of_val(&gen_t));
}
```

the `-Z print-type-sizes` output used to start with:

```
print-type-size type: `[async fn body@issue-62958-a.rs:3:32: 6:2]`: 16386 bytes, alignment: 1 bytes
print-type-size     discriminant: 1 bytes
print-type-size     variant `Suspend0`: 16385 bytes
print-type-size         field `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
print-type-size         field `.arg`: 8192 bytes
print-type-size         field `.__awaitee`: 1 bytes
...
print-type-size type: `std::mem::ManuallyDrop<[u8; 8192]>`: 8192 bytes, alignment: 1 bytes
print-type-size     field `.value`: 8192 bytes
...
```

but with this change, it now instead prints:

```
print-type-size type: `[async fn body@issue-62958-a.rs:3:32: 6:2]`: 16386 bytes, alignment: 1 bytes
print-type-size     discriminant: 1 bytes
print-type-size     variant `Suspend0`: 16385 bytes
print-type-size         upvar `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
print-type-size         local `.arg`: 8192 bytes
print-type-size         local `.__awaitee`: 1 bytes
...
print-type-size type: `std::mem::ManuallyDrop<[u8; 8192]>`: 8192 bytes, alignment: 1 bytes
print-type-size     field `.value`: 8192 bytes
```

(spawned off of investigation of rust-lang#62958 )

Author: matthiaskrgr

compiler/rustc_session/src/code_stats.rs

@@ -19,8 +19,26 @@ pub enum SizeKind {
     Min,
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub enum FieldKind {
+    AdtField,
+    Upvar,
+    GeneratorLocal,
+}
+
+impl std::fmt::Display for FieldKind {
+    fn fmt(&self, w: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            FieldKind::AdtField => write!(w, "field"),
+            FieldKind::Upvar => write!(w, "upvar"),
+            FieldKind::GeneratorLocal => write!(w, "local"),
+        }
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 pub struct FieldInfo {
+    pub kind: FieldKind,
     pub name: Symbol,
     pub offset: u64,
     pub size: u64,
@@ -145,7 +163,7 @@ impl CodeStats {
                 fields.sort_by_key(|f| (f.offset, f.size));
 
                 for field in fields {
-                    let FieldInfo { ref name, offset, size, align } = field;
+                    let FieldInfo { kind, ref name, offset, size, align } = field;
 
                     if offset > min_offset {
                         let pad = offset - min_offset;
@@ -155,16 +173,16 @@ impl CodeStats {
                     if offset < min_offset {
                         // If this happens it's probably a union.
                         println!(
-                            "print-type-size {indent}field `.{name}`: {size} bytes, \
+                            "print-type-size {indent}{kind} `.{name}`: {size} bytes, \
                                   offset: {offset} bytes, \
                                   alignment: {align} bytes"
                         );
                     } else if info.packed || offset == min_offset {
-                        println!("print-type-size {indent}field `.{name}`: {size} bytes");
+                        println!("print-type-size {indent}{kind} `.{name}`: {size} bytes");
                     } else {
                         // Include field alignment in output only if it caused padding injection
                         println!(
-                            "print-type-size {indent}field `.{name}`: {size} bytes, \
+                            "print-type-size {indent}{kind} `.{name}`: {size} bytes, \
                                   alignment: {align} bytes"
                         );
                     }

compiler/rustc_session/src/session.rs

@@ -1,6 +1,6 @@
 use crate::cgu_reuse_tracker::CguReuseTracker;
 use crate::code_stats::CodeStats;
-pub use crate::code_stats::{DataTypeKind, FieldInfo, SizeKind, VariantInfo};
+pub use crate::code_stats::{DataTypeKind, FieldInfo, FieldKind, SizeKind, VariantInfo};
 use crate::config::Input;
 use crate::config::{self, CrateType, InstrumentCoverage, OptLevel, OutputType, SwitchWithOptPath};
 use crate::errors::{

compiler/rustc_ty_utils/src/layout.rs

@@ -9,7 +9,7 @@ use rustc_middle::ty::layout::{
 use rustc_middle::ty::{
     self, subst::SubstsRef, AdtDef, EarlyBinder, ReprOptions, Ty, TyCtxt, TypeVisitable,
 };
-use rustc_session::{DataTypeKind, FieldInfo, SizeKind, VariantInfo};
+use rustc_session::{DataTypeKind, FieldInfo, FieldKind, SizeKind, VariantInfo};
 use rustc_span::symbol::Symbol;
 use rustc_span::DUMMY_SP;
 use rustc_target::abi::*;
@@ -881,6 +881,7 @@ fn variant_info_for_adt<'tcx>(
                 let offset = layout.fields.offset(i);
                 min_size = min_size.max(offset + field_layout.size);
                 FieldInfo {
+                    kind: FieldKind::AdtField,
                     name,
                     offset: offset.bytes(),
                     size: field_layout.size.bytes(),
@@ -960,6 +961,7 @@ fn variant_info_for_generator<'tcx>(
             let offset = layout.fields.offset(field_idx);
             upvars_size = upvars_size.max(offset + field_layout.size);
             FieldInfo {
+                kind: FieldKind::Upvar,
                 name: Symbol::intern(&name),
                 offset: offset.bytes(),
                 size: field_layout.size.bytes(),
@@ -983,6 +985,7 @@ fn variant_info_for_generator<'tcx>(
                     // The struct is as large as the last field's end
                     variant_size = variant_size.max(offset + field_layout.size);
                     FieldInfo {
+                        kind: FieldKind::GeneratorLocal,
                         name: state_specific_names.get(*local).copied().flatten().unwrap_or(
                             Symbol::intern(&format!(".generator_field{}", local.as_usize())),
                         ),

tests/ui/print_type_sizes/async.stdout

@@ -1,15 +1,15 @@
 print-type-size type: `[async fn body@$DIR/async.rs:8:36: 11:2]`: 16386 bytes, alignment: 1 bytes
 print-type-size     discriminant: 1 bytes
 print-type-size     variant `Suspend0`: 16385 bytes
-print-type-size         field `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
-print-type-size         field `.arg`: 8192 bytes
-print-type-size         field `.__awaitee`: 1 bytes
+print-type-size         upvar `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         local `.arg`: 8192 bytes
+print-type-size         local `.__awaitee`: 1 bytes
 print-type-size     variant `Unresumed`: 8192 bytes
-print-type-size         field `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         upvar `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
 print-type-size     variant `Returned`: 8192 bytes
-print-type-size         field `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         upvar `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
 print-type-size     variant `Panicked`: 8192 bytes
-print-type-size         field `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         upvar `.arg`: 8192 bytes, offset: 0 bytes, alignment: 1 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

tests/ui/print_type_sizes/generator.stdout

@@ -1,10 +1,10 @@
 print-type-size type: `[generator@$DIR/generator.rs:10:5: 10:14]`: 8193 bytes, alignment: 1 bytes
 print-type-size     discriminant: 1 bytes
 print-type-size     variant `Unresumed`: 8192 bytes
-print-type-size         field `.array`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         upvar `.array`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
 print-type-size     variant `Returned`: 8192 bytes
-print-type-size         field `.array`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         upvar `.array`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
 print-type-size     variant `Panicked`: 8192 bytes
-print-type-size         field `.array`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         upvar `.array`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
 print-type-size     variant `Suspend0`: 8192 bytes
-print-type-size         field `.array`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes
+print-type-size         upvar `.array`: 8192 bytes, offset: 0 bytes, alignment: 1 bytes

tests/ui/print_type_sizes/generator_discr_placement.stdout

@@ -2,10 +2,10 @@ print-type-size type: `[generator@$DIR/generator_discr_placement.rs:11:13: 11:15
 print-type-size     discriminant: 1 bytes
 print-type-size     variant `Suspend0`: 7 bytes
 print-type-size         padding: 3 bytes
-print-type-size         field `.w`: 4 bytes, alignment: 4 bytes
+print-type-size         local `.w`: 4 bytes, alignment: 4 bytes
 print-type-size     variant `Suspend1`: 7 bytes
 print-type-size         padding: 3 bytes
-print-type-size         field `.z`: 4 bytes, alignment: 4 bytes
+print-type-size         local `.z`: 4 bytes, alignment: 4 bytes
 print-type-size     variant `Unresumed`: 0 bytes
 print-type-size     variant `Returned`: 0 bytes
 print-type-size     variant `Panicked`: 0 bytes