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regression test for Cow<[u8]> layout #145411

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regression test for Cow<[u8]> layout #145411

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15 changes: 15 additions & 0 deletions tests/codegen-llvm/issues/cows-dont-have-branches-117763.rs
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//@ compile-flags: -Copt-level=3
//@ needs-deterministic-layouts

// Currently Vec<T> and &[T] have layouts that start with (pointer, len)
// which makes the conversion branchless.
// A nice-to-have property, not guaranteed.
#![crate_type = "cdylib"]

// CHECK-LABEL: @branchless_cow_slices
#[no_mangle]
pub fn branchless_cow_slices<'a>(cow: &'a std::borrow::Cow<'a, [u8]>) -> &'a [u8] {
// CHECK-NOT: br
// CHECK: ret { ptr, i64 }
&*cow
}
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