1 files changed, 108 insertions, 0 deletions
diff --git a/tests/codegen-llvm/slice-init.rs b/tests/codegen-llvm/slice-init.rs
new file mode 100644
index 00000000000..950e0b0c10d
--- /dev/null
+++ b/tests/codegen-llvm/slice-init.rs
@@ -0,0 +1,108 @@
+//@ compile-flags: -C no-prepopulate-passes
+
+#![crate_type = "lib"]
+
+// 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]
+}
+
+// FIXME: undef bytes can just be initialized with the same value as the
+// defined bytes, if the defines bytes are all the same.
+// CHECK-LABEL: @option_none_init
+#[no_mangle]
+pub fn option_none_init() -> [Option<u8>; N] {
+    // CHECK-NOT: select
+    // CHECK: br label %repeat_loop_header{{.*}}
+    // CHECK-NOT: switch
+    // CHECK: icmp
+    // CHECK-NOT: call void @llvm.memset.p0
+    [None; N]
+}
+
+use std::mem::MaybeUninit;
+
+// FIXME: This could be optimized into a memset.
+// Regression test for <https://github.com/rust-lang/rust/issues/137892>.
+#[no_mangle]
+pub fn half_uninit() -> [(u128, MaybeUninit<u128>); N] {
+    // CHECK-NOT: select
+    // CHECK: br label %repeat_loop_header{{.*}}
+    // CHECK-NOT: switch
+    // CHECK: icmp
+    // CHECK-NOT: call void @llvm.memset.p0
+    [const { (0, MaybeUninit::uninit()) }; N]
+}
+
+// Use an opaque function to prevent rustc from removing useless drops.
+#[inline(never)]
+pub fn opaque(_: impl Sized) {}