Rollup merge of rust-lang#96581 - RalfJung:debug-size-align, r=oli-obk

make Size and Align debug-printing a bit more compact

In particular in `{:#?}`-mode, these take up a lot of space, so I think this is the better alternative (even though it is a bit longer in `{:?}` mode, I think it is still more readable).

We could make it even smaller by deviating further from what the actual code looks like, e.g. via something like `Size(4 bytes)`. Not sure what people would think about that?

Cc `@oli-obk`

Author: GuillaumeGomez

compiler/rustc_middle/src/mir/pretty.rs

@@ -448,6 +448,12 @@ impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
                 self.push(&format!("+ user_ty: {:?}", user_ty));
             }
 
+            let fmt_val = |val: &ConstValue<'tcx>| match val {
+                ConstValue::Scalar(s) => format!("Scalar({:?})", s),
+                ConstValue::Slice { .. } => format!("Slice(..)"),
+                ConstValue::ByRef { .. } => format!("ByRef(..)"),
+            };
+
             let val = match literal {
                 ConstantKind::Ty(ct) => match ct.val() {
                     ty::ConstKind::Param(p) => format!("Param({})", p),
@@ -457,7 +463,7 @@ impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
                         uv.substs,
                         uv.promoted,
                     ),
-                    ty::ConstKind::Value(val) => format!("Value({:?})", val),
+                    ty::ConstKind::Value(val) => format!("Value({})", fmt_val(&val)),
                     ty::ConstKind::Error(_) => "Error".to_string(),
                     // These variants shouldn't exist in the MIR.
                     ty::ConstKind::Placeholder(_)
@@ -467,7 +473,7 @@ impl<'tcx> Visitor<'tcx> for ExtraComments<'tcx> {
                 // To keep the diffs small, we render this like we render `ty::Const::Value`.
                 //
                 // This changes once `ty::Const::Value` is represented using valtrees.
-                ConstantKind::Val(val, _) => format!("Value({:?})", val),
+                ConstantKind::Val(val, _) => format!("Value({})", fmt_val(&val)),
             };
 
             self.push(&format!("+ literal: Const {{ ty: {}, val: {} }}", literal.ty(), val));

compiler/rustc_target/src/abi/mod.rs

@@ -276,12 +276,19 @@ impl ToJson for Endian {
 }
 
 /// Size of a type in bytes.
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Encodable, Decodable)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)]
 #[derive(HashStable_Generic)]
 pub struct Size {
     raw: u64,
 }
 
+// This is debug-printed a lot in larger structs, don't waste too much space there
+impl fmt::Debug for Size {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Size({} bytes)", self.bytes())
+    }
+}
+
 impl Size {
     pub const ZERO: Size = Size { raw: 0 };
 
@@ -485,12 +492,19 @@ impl Step for Size {
 }
 
 /// Alignment of a type in bytes (always a power of two).
-#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Encodable, Decodable)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)]
 #[derive(HashStable_Generic)]
 pub struct Align {
     pow2: u8,
 }
 
+// This is debug-printed a lot in larger structs, don't waste too much space there
+impl fmt::Debug for Align {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Align({} bytes)", self.bytes())
+    }
+}
+
 impl Align {
     pub const ONE: Align = Align { pow2: 0 };
 

src/test/mir-opt/const_debuginfo.main.ConstDebugInfo.diff

@@ -77,7 +77,7 @@
           _9 = const "hello, world!";      // scope 4 at $DIR/const_debuginfo.rs:14:13: 14:28
                                            // mir::Constant
                                            // + span: $DIR/const_debuginfo.rs:14:13: 14:28
-                                           // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [104, 101, 108, 108, 111, 44, 32, 119, 111, 114, 108, 100, 33], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [8191], len: Size { raw: 13 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 13 }) }
+                                           // + literal: Const { ty: &str, val: Value(Slice(..)) }
           StorageLive(_10);                // scope 5 at $DIR/const_debuginfo.rs:16:9: 16:10
           Deinit(_10);                     // scope 5 at $DIR/const_debuginfo.rs:16:13: 16:34
           (_10.0: bool) = const true;      // scope 5 at $DIR/const_debuginfo.rs:16:13: 16:34

src/test/mir-opt/const_prop/control_flow_simplification.hello.ConstProp.diff

@@ -22,7 +22,7 @@
                                            // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
                                            // mir::Constant
                                            // + span: $SRC_DIR/std/src/panic.rs:LL:COL
-                                           // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [101, 120, 112, 108, 105, 99, 105, 116, 32, 112, 97, 110, 105, 99], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [16383], len: Size { raw: 14 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 14 }) }
+                                           // + literal: Const { ty: &str, val: Value(Slice(..)) }
       }
 
       bb2: {

src/test/mir-opt/inline/inline_diverging.g.Inline.diff

@@ -43,7 +43,7 @@
 +                                          // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
 +                                          // mir::Constant
 +                                          // + span: $SRC_DIR/std/src/panic.rs:LL:COL
-+                                          // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [101, 120, 112, 108, 105, 99, 105, 116, 32, 112, 97, 110, 105, 99], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [16383], len: Size { raw: 14 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 14 }) }
++                                          // + literal: Const { ty: &str, val: Value(Slice(..)) }
       }
   }
 

src/test/mir-opt/inline/inline_into_box_place.main.Inline.32bit.diff

@@ -46,7 +46,7 @@
 -     bb2: {
 +                                          // + span: $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 +                                          // + user_ty: UserType(0)
-+                                          // + literal: Const { ty: alloc::raw_vec::RawVec<u32>, val: Value(ByRef { alloc: Allocation { bytes: [4, 0, 0, 0, 0, 0, 0, 0], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [255], len: Size { raw: 8 } }, align: Align { pow2: 2 }, mutability: Not, extra: () }, offset: Size { raw: 0 } }) }
++                                          // + literal: Const { ty: alloc::raw_vec::RawVec<u32>, val: Value(ByRef(..)) }
 +         Deinit((*_7));                   // scope 3 at $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 +         ((*_7).0: alloc::raw_vec::RawVec<u32>) = move _8; // scope 3 at $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 +         ((*_7).1: usize) = const 0_usize; // scope 3 at $SRC_DIR/alloc/src/vec/mod.rs:LL:COL

src/test/mir-opt/inline/inline_into_box_place.main.Inline.64bit.diff

@@ -46,7 +46,7 @@
 -     bb2: {
 +                                          // + span: $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 +                                          // + user_ty: UserType(0)
-+                                          // + literal: Const { ty: alloc::raw_vec::RawVec<u32>, val: Value(ByRef { alloc: Allocation { bytes: [4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [65535], len: Size { raw: 16 } }, align: Align { pow2: 3 }, mutability: Not, extra: () }, offset: Size { raw: 0 } }) }
++                                          // + literal: Const { ty: alloc::raw_vec::RawVec<u32>, val: Value(ByRef(..)) }
 +         Deinit((*_7));                   // scope 3 at $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 +         ((*_7).0: alloc::raw_vec::RawVec<u32>) = move _8; // scope 3 at $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
 +         ((*_7).1: usize) = const 0_usize; // scope 3 at $SRC_DIR/alloc/src/vec/mod.rs:LL:COL

src/test/mir-opt/issue_76432.test.SimplifyComparisonIntegral.diff

@@ -73,7 +73,7 @@
                                            // + literal: Const { ty: fn(&'static str) -> ! {core::panicking::panic}, val: Value(Scalar(<ZST>)) }
                                            // mir::Constant
                                            // + span: $SRC_DIR/core/src/panic.rs:LL:COL
-                                           // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [105, 110, 116, 101, 114, 110, 97, 108, 32, 101, 114, 114, 111, 114, 58, 32, 101, 110, 116, 101, 114, 101, 100, 32, 117, 110, 114, 101, 97, 99, 104, 97, 98, 108, 101, 32, 99, 111, 100, 101], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1099511627775], len: Size { raw: 40 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 40 }) }
+                                           // + literal: Const { ty: &str, val: Value(Slice(..)) }
       }
 
       bb2: {

src/test/mir-opt/issues/issue_59352.num_to_digit.PreCodegen.after.mir

@@ -92,7 +92,7 @@ fn num_to_digit(_1: char) -> u32 {
                                          // + literal: Const { ty: fn(&'static str) -> ! {core::panicking::panic}, val: Value(Scalar(<ZST>)) }
                                          // mir::Constant
                                          // + span: $SRC_DIR/core/src/option.rs:LL:COL
-                                         // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [99, 97, 108, 108, 101, 100, 32, 96, 79, 112, 116, 105, 111, 110, 58, 58, 117, 110, 119, 114, 97, 112, 40, 41, 96, 32, 111, 110, 32, 97, 32, 96, 78, 111, 110, 101, 96, 32, 118, 97, 108, 117, 101], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [8796093022207], len: Size { raw: 43 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 43 }) }
+                                         // + literal: Const { ty: &str, val: Value(Slice(..)) }
     }
 
     bb7: {

src/test/mir-opt/no_drop_for_inactive_variant.unwrap.SimplifyCfg-elaborate-drops.after.mir

@@ -26,7 +26,7 @@ fn unwrap(_1: Option<T>) -> T {
                                          // + literal: Const { ty: fn(&str) -> ! {begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
                                          // mir::Constant
                                          // + span: $SRC_DIR/std/src/panic.rs:LL:COL
-                                         // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [101, 120, 112, 108, 105, 99, 105, 116, 32, 112, 97, 110, 105, 99], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [16383], len: Size { raw: 14 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 14 }) }
+                                         // + literal: Const { ty: &str, val: Value(Slice(..)) }
     }
 
     bb2: {