2 files changed, 52 insertions, 5 deletions
diff --git a/tests/codegen/overaligned-constant.rs b/tests/codegen/overaligned-constant.rs
index 7cd8d19c211..e5540aca387 100644
--- a/tests/codegen/overaligned-constant.rs
+++ b/tests/codegen/overaligned-constant.rs
@@ -17,8 +17,6 @@ pub fn overaligned_constant() {
     // CHECK-LABEL: @overaligned_constant
     // CHECK: [[full:%_.*]] = alloca [32 x i8], align 8
     // CHECK: call void @llvm.memcpy.p0.p0.i64(ptr align 8 [[full]], ptr align 8 @0, i64 32, i1 false)
-    // CHECK: %b.0 = load i32, ptr @0, align 4
-    // CHECK: %b.1 = load i32, ptr getelementptr inbounds ({{.*}}), align 4
     let mut s = S(1);
 
     s.0 = 3;
diff --git a/tests/codegen/slice-init.rs b/tests/codegen/slice-init.rs
index 1c2dd3e8875..b36a5b5de3d 100644
--- a/tests/codegen/slice-init.rs
+++ b/tests/codegen/slice-init.rs
@@ -2,6 +2,8 @@
 
 #![crate_type = "lib"]
 
+use std::mem::MaybeUninit;
+
 // CHECK-LABEL: @zero_sized_elem
 #[no_mangle]
 pub fn zero_sized_elem() {
@@ -76,17 +78,64 @@ pub fn u16_init_one_bytes() -> [u16; N] {
     [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-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
-    [None; N]
+    [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.