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add regression test for not memcpying padding bytes

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kadiwa 2023-08-22 14:43:53 +02:00
parent 95305899b8
commit 265c1b5d50
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1 changed files with 14 additions and 0 deletions
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46
tests/codegen/box-uninit-bytes.rs Normal file
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@ -0,0 +1,46 @@
// compile-flags: -O
#![crate_type = "lib"]
use std::mem::MaybeUninit;
// Boxing a `MaybeUninit` value should not copy junk from the stack
#[no_mangle]
pub fn box_uninitialized() -> Box<MaybeUninit<usize>> {
// CHECK-LABEL: @box_uninitialized
// CHECK-NOT: store
// CHECK-NOT: alloca
// CHECK-NOT: memcpy
// CHECK-NOT: memset
Box::new(MaybeUninit::uninit())
}
// https://github.com/rust-lang/rust/issues/58201
#[no_mangle]
pub fn box_uninitialized2() -> Box<MaybeUninit<[usize; 1024 * 1024]>> {
// CHECK-LABEL: @box_uninitialized2
// CHECK-NOT: store
// CHECK-NOT: alloca
// CHECK-NOT: memcpy
// CHECK-NOT: memset
Box::new(MaybeUninit::uninit())
}
#[repr(align(1024))]
pub struct LotsaPadding(usize);
// Boxing a value with padding should not copy junk from the stack
#[no_mangle]
pub fn box_lotsa_padding() -> Box<LotsaPadding> {
// CHECK-LABEL: @box_lotsa_padding
// CHECK-NOT: alloca
// CHECK-NOT: getelementptr
// CHECK-NOT: memcpy
// CHECK-NOT: memset
Box::new(LotsaPadding(42))
}
// Hide the `allocalign` attribute in the declaration of __rust_alloc
// from the CHECK-NOT above, and also verify the attributes got set reasonably.
// CHECK: declare {{(dso_local )?}}noalias noundef ptr @__rust_alloc(i{{[0-9]+}} noundef, i{{[0-9]+}} allocalign noundef) unnamed_addr [[RUST_ALLOC_ATTRS:#[0-9]+]]
// CHECK-DAG: attributes [[RUST_ALLOC_ATTRS]] = { {{.*}} allockind("alloc,uninitialized,aligned") allocsize(0) {{(uwtable )?}}"alloc-family"="__rust_alloc" {{.*}} }