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Auto merge of #98675 - eddyb:cg-array-literal, r=nikic

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rustc_codegen_ssa: use `project_index`, not `project_field`, for array literals.

See https://github.com/rust-lang/rust/pull/98615#issuecomment-1170082774 for some context.

In short, we were using `project_field` even for array `mir::Rvalue::Aggregate`s, which results in benchmarks like `deep-vector.rs` (and presumably also some real-world usecases?) being impacted by how we handle non-array aggregate fields.

(This is a separate PR so that we can measure the perf effects in isolation)

r? `@nikic`
This commit is contained in:
bors 2022-07-07 12:23:26 +00:00
commit 20dd693013
1 changed files with 6 additions and 1 deletions
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7
compiler/rustc_codegen_ssa/src/mir/rvalue.rs
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@ -123,7 +123,12 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
// Do not generate stores and GEPis for zero-sized fields.
if !op.layout.is_zst() {
let field_index = active_field_index.unwrap_or(i);
let field = dest.project_field(&mut bx, field_index);
let field = if let mir::AggregateKind::Array(_) = **kind {
let llindex = bx.cx().const_usize(field_index as u64);
dest.project_index(&mut bx, llindex)
} else {
dest.project_field(&mut bx, field_index)
};
op.val.store(&mut bx, field);
}
}