//@ compile-flags: -C no-prepopulate-passes

#![crate_type = "lib"]

use std::mem::MaybeUninit;

// CHECK-LABEL: @zero_sized_elem
#[no_mangle]
pub fn zero_sized_elem() {
    // CHECK-NOT: br label %repeat_loop_header{{.*}}
    // CHECK-NOT: call void @llvm.memset.p0
    let x = [(); 4];
    opaque(&x);
}

// CHECK-LABEL: @zero_len_array
#[no_mangle]
pub fn zero_len_array() {
    // CHECK-NOT: br label %repeat_loop_header{{.*}}
    // CHECK-NOT: call void @llvm.memset.p0
    let x = [4; 0];
    opaque(&x);
}

// CHECK-LABEL: @byte_array
#[no_mangle]
pub fn byte_array() {
    // CHECK: call void @llvm.memset.{{.+}}(ptr {{.*}}, i8 7, i{{[0-9]+}} 4
    // CHECK-NOT: br label %repeat_loop_header{{.*}}
    let x = [7u8; 4];
    opaque(&x);
}

#[allow(dead_code)]
#[derive(Copy, Clone)]
enum Init {
    Loop,
    Memset,
}

// CHECK-LABEL: @byte_enum_array
#[no_mangle]
pub fn byte_enum_array() {
    // CHECK: call void @llvm.memset.{{.+}}(ptr {{.*}}, i8 {{.*}}, i{{[0-9]+}} 4
    // CHECK-NOT: br label %repeat_loop_header{{.*}}
    let x = [Init::Memset; 4];
    opaque(&x);
}

// CHECK-LABEL: @zeroed_integer_array
#[no_mangle]
pub fn zeroed_integer_array() {
    // CHECK: call void @llvm.memset.{{.+}}(ptr {{.*}}, i8 0, i{{[0-9]+}} 16
    // CHECK-NOT: br label %repeat_loop_header{{.*}}
    let x = [0u32; 4];
    opaque(&x);
}

// CHECK-LABEL: @nonzero_integer_array
#[no_mangle]
pub fn nonzero_integer_array() {
    // CHECK: br label %repeat_loop_header{{.*}}
    // CHECK-NOT: call void @llvm.memset.p0
    let x = [0x1a_2b_3c_4d_u32; 4];
    opaque(&x);
}

const N: usize = 100;

// CHECK-LABEL: @u16_init_one_bytes
#[no_mangle]
pub fn u16_init_one_bytes() -> [u16; N] {
    // CHECK-NOT: select
    // CHECK-NOT: br
    // CHECK-NOT: switch
    // CHECK-NOT: icmp
    // CHECK: call void @llvm.memset.p0
    [const { u16::from_be_bytes([1, 1]) }; N]
}

// CHECK-LABEL: @option_none_init
#[no_mangle]
pub fn option_none_init() -> [Option<u8>; N] {
    // CHECK-NOT: select
    // CHECK-NOT: br
    // CHECK-NOT: switch
    // CHECK-NOT: icmp
    // CHECK: call void @llvm.memset.p0
    [const { None }; N]
}

// If there is partial provenance or some bytes are initialized and some are not,
// we can't really do better than initialize bytes or groups of bytes together.
// CHECK-LABEL: @option_maybe_uninit_init
#[no_mangle]
pub fn option_maybe_uninit_init() -> [MaybeUninit<u16>; N] {
    // CHECK-NOT: select
    // CHECK: br label %repeat_loop_header{{.*}}
    // CHECK-NOT: switch
    // CHECK: icmp
    // CHECK-NOT: call void @llvm.memset.p0
    [const {
        let mut val: MaybeUninit<u16> = MaybeUninit::uninit();
        let ptr = val.as_mut_ptr() as *mut u8;
        unsafe {
            ptr.write(0);
        }
        val
    }; N]
}

#[repr(packed)]
struct Packed {
    start: u8,
    ptr: &'static (),
    rest: u16,
    rest2: u8,
}

// If there is partial provenance or some bytes are initialized and some are not,
// we can't really do better than initialize bytes or groups of bytes together.
// CHECK-LABEL: @option_maybe_uninit_provenance
#[no_mangle]
pub fn option_maybe_uninit_provenance() -> [MaybeUninit<Packed>; N] {
    // CHECK-NOT: select
    // CHECK: br label %repeat_loop_header{{.*}}
    // CHECK-NOT: switch
    // CHECK: icmp
    // CHECK-NOT: call void @llvm.memset.p0
    [const {
        let mut val: MaybeUninit<Packed> = MaybeUninit::uninit();
        unsafe {
            let ptr = &raw mut (*val.as_mut_ptr()).ptr;
            static HAS_ADDR: () = ();
            ptr.write_unaligned(&HAS_ADDR);
        }
        val
    }; N]
}

// Use an opaque function to prevent rustc from removing useless drops.
#[inline(never)]
pub fn opaque(_: impl Sized) {}