bendns' repos / rust-analyzer
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support nonzero* niche optimizations
Browse Source
hkalbasi 2022-12-04
parent 86b5b60 · commit f2c9502
Diffstat
-rw-r--r--crates/hir-ty/src/layout/adt.rs50
-rw-r--r--crates/hir-ty/src/layout/tests.rs13
-rw-r--r--crates/test-utils/src/minicore.rs10
3 files changed, 73 insertions, 0 deletions
diff --git a/crates/hir-ty/src/layout/adt.rs b/crates/hir-ty/src/layout/adt.rs
index e353034eb9..9244353f3a 100644
--- a/crates/hir-ty/src/layout/adt.rs
+++ b/crates/hir-ty/src/layout/adt.rs
@@ -4,6 +4,7 @@ use std::{
cmp::{self, Ordering},
iter,
num::NonZeroUsize,
+ ops::Bound,
};
use chalk_ir::TyKind;
@@ -18,6 +19,8 @@ use hir_def::{
};
use la_arena::{ArenaMap, RawIdx};
+struct X(Option<NonZeroUsize>);
+
use crate::{
db::HirDatabase,
lang_items::is_unsafe_cell,
@@ -137,7 +140,38 @@ pub fn layout_of_adt_query(
Abi::Aggregate { sized: _ } => {}
}
st.largest_niche = None;
+ return Ok(st);
+ }
+
+ let (start, end) = layout_scalar_valid_range(db, def);
+ match st.abi {
+ Abi::Scalar(ref mut scalar) | Abi::ScalarPair(ref mut scalar, _) => {
+ if let Bound::Included(start) = start {
+ let valid_range = scalar.valid_range_mut();
+ valid_range.start = start;
+ }
+ if let Bound::Included(end) = end {
+ let valid_range = scalar.valid_range_mut();
+ valid_range.end = end;
+ }
+ // Update `largest_niche` if we have introduced a larger niche.
+ let niche = Niche::from_scalar(dl, Size::ZERO, *scalar);
+ if let Some(niche) = niche {
+ match st.largest_niche {
+ Some(largest_niche) => {
+ // Replace the existing niche even if they're equal,
+ // because this one is at a lower offset.
+ if largest_niche.available(dl) <= niche.available(dl) {
+ st.largest_niche = Some(niche);
+ }
+ }
+ None => st.largest_niche = Some(niche),
+ }
+ }
+ }
+ _ => user_error!("nonscalar layout for layout_scalar_valid_range"),
}
+
return Ok(st);
}
@@ -591,6 +625,22 @@ pub fn layout_of_adt_query(
Ok(best_layout.layout)
}
+fn layout_scalar_valid_range(db: &dyn HirDatabase, def: AdtId) -> (Bound<u128>, Bound<u128>) {
+ let attrs = db.attrs(def.into());
+ let get = |name| {
+ let attr = attrs.by_key(name).tt_values();
+ for tree in attr {
+ if let Some(x) = tree.token_trees.first() {
+ if let Ok(x) = x.to_string().parse() {
+ return Bound::Included(x);
+ }
+ }
+ }
+ Bound::Unbounded
+ };
+ (get("rustc_layout_scalar_valid_range_start"), get("rustc_layout_scalar_valid_range_end"))
+}
+
pub fn layout_of_adt_recover(
_: &dyn HirDatabase,
_: &[String],
diff --git a/crates/hir-ty/src/layout/tests.rs b/crates/hir-ty/src/layout/tests.rs
index 9543b4dcbc..1cd6d4eae2 100644
--- a/crates/hir-ty/src/layout/tests.rs
+++ b/crates/hir-ty/src/layout/tests.rs
@@ -147,6 +147,19 @@ fn tuple() {
}
#[test]
+fn non_zero() {
+ check_size_and_align(
+ r#"
+ //- minicore: non_zero, option
+ use core::num::NonZeroU8;
+ struct Goal(Option<NonZeroU8>);
+ "#,
+ 1,
+ 1,
+ );
+}
+
+#[test]
fn niche_optimization() {
check_size_and_align(
r#"
diff --git a/crates/test-utils/src/minicore.rs b/crates/test-utils/src/minicore.rs
index 69d2e62b25..af9efd2600 100644
--- a/crates/test-utils/src/minicore.rs
+++ b/crates/test-utils/src/minicore.rs
@@ -29,6 +29,7 @@
//! index: sized
//! iterator: option
//! iterators: iterator, fn
+//! non_zero:
//! option:
//! ord: eq, option
//! pin:
@@ -680,6 +681,15 @@ mod macros {
}
// endregion:derive
+// region:non_zero
+pub mod num {
+ #[repr(transparent)]
+ #[rustc_layout_scalar_valid_range_start(1)]
+ #[rustc_nonnull_optimization_guaranteed]
+ pub struct NonZeroU8(u8);
+}
+// endregion:non_zero
+
// region:bool_impl
#[lang = "bool"]
impl bool {