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// compile-flags: -O
// only-x86_64
// ignore-debug: the debug assertions get in the way
#![crate_type = "lib"]
#![feature(iter_repeat_n)]
#[derive(Clone)]
pub struct NotCopy(u16);
impl Drop for NotCopy {
fn drop(&mut self) {}
}
// For a type where `Drop::drop` doesn't do anything observable and a clone is the
// same as a move, make sure that the extra case for the last item disappears.
#[no_mangle]
// CHECK-LABEL: @iter_repeat_n_next
pub fn iter_repeat_n_next(it: &mut std::iter::RepeatN<NotCopy>) -> Option<NotCopy> {
// CHECK-NEXT: start:
// CHECK-NOT: br
// CHECK: %[[COUNT:.+]] = load i64
// CHECK-NEXT: %[[COUNT_ZERO:.+]] = icmp eq i64 %[[COUNT]], 0
// CHECK-NEXT: br i1 %[[COUNT_ZERO]], label %[[EMPTY:.+]], label %[[NOT_EMPTY:.+]]
// CHECK: [[NOT_EMPTY]]:
// CHECK-NEXT: %[[DEC:.+]] = add i64 %[[COUNT]], -1
// CHECK-NEXT: store i64 %[[DEC]]
// CHECK-NOT: br
// CHECK: %[[VAL:.+]] = load i16
// CHECK-NEXT: br label %[[EMPTY]]
// CHECK: [[EMPTY]]:
// CHECK-NOT: br
// CHECK: phi i16
// CHECK-SAME: [ %[[VAL]], %[[NOT_EMPTY]] ]
// CHECK-NOT: br
// CHECK: ret
it.next()
}
// And as a result, using the iterator can optimize without special cases for
// the last iteration, like `memset`ing all the items in one call.
#[no_mangle]
// CHECK-LABEL: @vec_extend_via_iter_repeat_n
pub fn vec_extend_via_iter_repeat_n() -> Vec<u8> {
// CHECK: %[[ADDR:.+]] = tail call noundef dereferenceable_or_null(1234) ptr @__rust_alloc(i64 noundef 1234, i64 noundef 1)
// CHECK: tail call void @llvm.memset.p0.i64(ptr noundef nonnull align 1 dereferenceable(1234) %[[ADDR]], i8 42, i64 1234,
let n = 1234_usize;
let mut v = Vec::with_capacity(n);
v.extend(std::iter::repeat_n(42_u8, n));
v
}
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