tests/codegen/box-maybe-uninit.rs

   1 // compile-flags: -O
   2 // min-llvm-version: 15.0
   3 #![crate_type = "lib"]
   4
   5 use std::mem::MaybeUninit;
   6
   7 // Boxing a `MaybeUninit` value should not copy junk from the stack
   8 #[no_mangle]
   9 pub fn box_uninitialized() -> Box<MaybeUninit<usize>> {
  10     // CHECK-LABEL: @box_uninitialized
  11     // CHECK-NOT: store
  12     // CHECK-NOT: alloca
  13     // CHECK-NOT: memcpy
  14     // CHECK-NOT: memset
  15     Box::new(MaybeUninit::uninit())
  16 }
  17
  18 // https://github.com/rust-lang/rust/issues/58201
  19 #[no_mangle]
  20 pub fn box_uninitialized2() -> Box<MaybeUninit<[usize; 1024 * 1024]>> {
  21     // CHECK-LABEL: @box_uninitialized2
  22     // CHECK-NOT: store
  23     // CHECK-NOT: alloca
  24     // CHECK-NOT: memcpy
  25     // CHECK-NOT: memset
  26     Box::new(MaybeUninit::uninit())
  27 }
  28
  29 // Hide the `allocalign` attribute in the declaration of __rust_alloc
  30 // from the CHECK-NOT above, and also verify the attributes got set reasonably.
  31 // CHECK: declare noalias noundef ptr @__rust_alloc(i{{[0-9]+}} noundef, i{{[0-9]+}} allocalign noundef) unnamed_addr [[RUST_ALLOC_ATTRS:#[0-9]+]]
  32
  33 // CHECK-DAG: attributes [[RUST_ALLOC_ATTRS]] = { {{.*}} allockind("alloc,uninitialized,aligned") allocsize(0) uwtable "alloc-family"="__rust_alloc" {{.*}} }