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interpret/visitor: make memory order iteration slightly more efficient

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This commit is contained in:
Ralf Jung 2024-08-29 16:53:07 +02:00
parent 6cf068db56
commit de34a91350
2 changed files with 15 additions and 17 deletions
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19
compiler/rustc_const_eval/src/interpret/visitor.rs
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@ -25,14 +25,15 @@ pub trait ValueVisitor<'tcx, M: Machine<'tcx>>: Sized {
}
/// This function provides the chance to reorder the order in which fields are visited for
/// `FieldsShape::Aggregate`: The order of fields will be
/// `(0..num_fields).map(aggregate_field_order)`.
/// `FieldsShape::Aggregate`.
///
/// The default means we iterate in source declaration order; alternative this can do an inverse
/// lookup in `memory_index` to use memory field order instead.
/// The default means we iterate in source declaration order; alternatively this can do some
/// work with `memory_index` to iterate in memory order.
#[inline(always)]
fn aggregate_field_order(_memory_index: &IndexVec<FieldIdx, u32>, idx: usize) -> usize {
idx
fn aggregate_field_iter(
memory_index: &IndexVec<FieldIdx, u32>,
) -> impl Iterator<Item = FieldIdx> + 'static {
memory_index.indices()
}
// Recursive actions, ready to be overloaded.
@ -172,9 +173,9 @@ pub trait ValueVisitor<'tcx, M: Machine<'tcx>>: Sized {
&FieldsShape::Union(fields) => {
self.visit_union(v, fields)?;
}
FieldsShape::Arbitrary { offsets, memory_index } => {
for idx in 0..offsets.len() {
let idx = Self::aggregate_field_order(memory_index, idx);
FieldsShape::Arbitrary { memory_index, .. } => {
for idx in Self::aggregate_field_iter(memory_index) {
let idx = idx.as_usize();
let field = self.ecx().project_field(v, idx)?;
self.visit_field(v, idx, &field)?;
}