diff options
| -rw-r--r-- | compiler/rustc_abi/src/layout.rs | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/compiler/rustc_abi/src/layout.rs b/compiler/rustc_abi/src/layout.rs index 0b0fea4c500..f15fb877d51 100644 --- a/compiler/rustc_abi/src/layout.rs +++ b/compiler/rustc_abi/src/layout.rs @@ -1,4 +1,5 @@ use super::*; +use std::fmt::Write; use std::{borrow::Borrow, cmp, iter, ops::Bound}; #[cfg(feature = "randomize")] @@ -72,12 +73,30 @@ pub trait LayoutCalculator { .expect("alt layout should have a niche like the regular one"); let alt_head_space = niche.offset.bytes(); let alt_niche_len = niche.value.size(dl).bytes(); + let alt_tail_space = alt_layout.size.bytes() - alt_head_space - alt_niche_len; debug_assert_eq!(layout.size.bytes(), alt_layout.size.bytes()); let prefer_alt_layout = alt_head_space > head_space && alt_head_space > tail_space; + debug!( + "sz: {}, default_niche_at: {}+{}, default_tail_space: {}, alt_niche_at/head_space: {}+{}, alt_tail: {}, num_fields: {}, better: {}\n\ + layout: {}\n\ + alt_layout: {}\n", + layout.size.bytes(), + head_space, + niche_length, + tail_space, + alt_head_space, + alt_niche_len, + alt_tail_space, + layout.fields.count(), + prefer_alt_layout, + format_field_niches(&layout, &fields, &dl), + format_field_niches(&alt_layout, &fields, &dl), + ); + if prefer_alt_layout { return Some(alt_layout); } @@ -1015,3 +1034,28 @@ fn univariant( size, }) } + +fn format_field_niches( + layout: &LayoutS, + fields: &IndexSlice<FieldIdx, Layout<'_>>, + dl: &TargetDataLayout, +) -> String { + let mut s = String::new(); + for i in layout.fields.index_by_increasing_offset() { + let offset = layout.fields.offset(i); + let f = fields[i.into()]; + write!(s, "[o{}a{}s{}", offset.bytes(), f.align().abi.bytes(), f.size().bytes()).unwrap(); + if let Some(n) = f.largest_niche() { + write!( + s, + " n{}b{}s{}", + n.offset.bytes(), + n.available(dl).ilog2(), + n.value.size(dl).bytes() + ) + .unwrap(); + } + write!(s, "] ").unwrap(); + } + s +} |