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Diffstat (limited to 'compiler/rustc_session/src/code_stats.rs')
| -rw-r--r-- | compiler/rustc_session/src/code_stats.rs | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/compiler/rustc_session/src/code_stats.rs b/compiler/rustc_session/src/code_stats.rs new file mode 100644 index 000000000..eede4d16e --- /dev/null +++ b/compiler/rustc_session/src/code_stats.rs @@ -0,0 +1,182 @@ +use rustc_data_structures::fx::FxHashSet; +use rustc_data_structures::sync::Lock; +use rustc_span::Symbol; +use rustc_target::abi::{Align, Size}; +use std::cmp::{self, Ordering}; + +#[derive(Clone, PartialEq, Eq, Hash, Debug)] +pub struct VariantInfo { + pub name: Option<Symbol>, + pub kind: SizeKind, + pub size: u64, + pub align: u64, + pub fields: Vec<FieldInfo>, +} + +#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] +pub enum SizeKind { + Exact, + Min, +} + +#[derive(Clone, PartialEq, Eq, Hash, Debug)] +pub struct FieldInfo { + pub name: Symbol, + pub offset: u64, + pub size: u64, + pub align: u64, +} + +#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] +pub enum DataTypeKind { + Struct, + Union, + Enum, + Closure, +} + +#[derive(PartialEq, Eq, Hash, Debug)] +pub struct TypeSizeInfo { + pub kind: DataTypeKind, + pub type_description: String, + pub align: u64, + pub overall_size: u64, + pub packed: bool, + pub opt_discr_size: Option<u64>, + pub variants: Vec<VariantInfo>, +} + +#[derive(Default)] +pub struct CodeStats { + type_sizes: Lock<FxHashSet<TypeSizeInfo>>, +} + +impl CodeStats { + pub fn record_type_size<S: ToString>( + &self, + kind: DataTypeKind, + type_desc: S, + align: Align, + overall_size: Size, + packed: bool, + opt_discr_size: Option<Size>, + mut variants: Vec<VariantInfo>, + ) { + // Sort variants so the largest ones are shown first. A stable sort is + // used here so that source code order is preserved for all variants + // that have the same size. + variants.sort_by(|info1, info2| info2.size.cmp(&info1.size)); + let info = TypeSizeInfo { + kind, + type_description: type_desc.to_string(), + align: align.bytes(), + overall_size: overall_size.bytes(), + packed, + opt_discr_size: opt_discr_size.map(|s| s.bytes()), + variants, + }; + self.type_sizes.borrow_mut().insert(info); + } + + pub fn print_type_sizes(&self) { + let type_sizes = self.type_sizes.borrow(); + let mut sorted: Vec<_> = type_sizes.iter().collect(); + + // Primary sort: large-to-small. + // Secondary sort: description (dictionary order) + sorted.sort_by(|info1, info2| { + // (reversing cmp order to get large-to-small ordering) + match info2.overall_size.cmp(&info1.overall_size) { + Ordering::Equal => info1.type_description.cmp(&info2.type_description), + other => other, + } + }); + + for info in sorted { + let TypeSizeInfo { type_description, overall_size, align, kind, variants, .. } = info; + println!( + "print-type-size type: `{type_description}`: {overall_size} bytes, alignment: {align} bytes" + ); + let indent = " "; + + let discr_size = if let Some(discr_size) = info.opt_discr_size { + println!("print-type-size {indent}discriminant: {discr_size} bytes"); + discr_size + } else { + 0 + }; + + // We start this at discr_size (rather than 0) because + // things like C-enums do not have variants but we still + // want the max_variant_size at the end of the loop below + // to reflect the presence of the discriminant. + let mut max_variant_size = discr_size; + + let struct_like = match kind { + DataTypeKind::Struct | DataTypeKind::Closure => true, + DataTypeKind::Enum | DataTypeKind::Union => false, + }; + for (i, variant_info) in variants.into_iter().enumerate() { + let VariantInfo { ref name, kind: _, align: _, size, ref fields } = *variant_info; + let indent = if !struct_like { + let name = match name.as_ref() { + Some(name) => name.to_string(), + None => i.to_string(), + }; + println!( + "print-type-size {indent}variant `{name}`: {diff} bytes", + diff = size - discr_size + ); + " " + } else { + assert!(i < 1); + " " + }; + max_variant_size = cmp::max(max_variant_size, size); + + let mut min_offset = discr_size; + + // We want to print fields by increasing offset. We also want + // zero-sized fields before non-zero-sized fields, otherwise + // the loop below goes wrong; hence the `f.size` in the sort + // key. + let mut fields = fields.clone(); + fields.sort_by_key(|f| (f.offset, f.size)); + + for field in fields { + let FieldInfo { ref name, offset, size, align } = field; + + if offset > min_offset { + let pad = offset - min_offset; + println!("print-type-size {indent}padding: {pad} bytes"); + } + + if offset < min_offset { + // If this happens it's probably a union. + println!( + "print-type-size {indent}field `.{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"); + } else { + // Include field alignment in output only if it caused padding injection + println!( + "print-type-size {indent}field `.{name}`: {size} bytes, \ + alignment: {align} bytes" + ); + } + + min_offset = offset + size; + } + } + + match overall_size.checked_sub(max_variant_size) { + None => panic!("max_variant_size {max_variant_size} > {overall_size} overall_size"), + Some(diff @ 1..) => println!("print-type-size {indent}end padding: {diff} bytes"), + Some(0) => {} + } + } + } +} |