774268afc1
We're using `Layout` on both sides, so might as well skip the transmutes back and forth to `usize`. The mir-opt test shows that doing so allows simplifying the boxed-slice drop slightly, for example.
46 lines
1.6 KiB
Rust
46 lines
1.6 KiB
Rust
//@ compile-flags: -Copt-level=3
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#![crate_type = "lib"]
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use std::mem::MaybeUninit;
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// Boxing a `MaybeUninit` value should not copy junk from the stack
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#[no_mangle]
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pub fn box_uninitialized() -> Box<MaybeUninit<usize>> {
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// CHECK-LABEL: @box_uninitialized
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// CHECK-NOT: store
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// CHECK-NOT: alloca
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// CHECK-NOT: memcpy
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// CHECK-NOT: memset
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Box::new(MaybeUninit::uninit())
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}
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// https://github.com/rust-lang/rust/issues/58201
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#[no_mangle]
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pub fn box_uninitialized2() -> Box<MaybeUninit<[usize; 1024 * 1024]>> {
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// CHECK-LABEL: @box_uninitialized2
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// CHECK-NOT: store
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// CHECK-NOT: alloca
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// CHECK-NOT: memcpy
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// CHECK-NOT: memset
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Box::new(MaybeUninit::uninit())
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}
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#[repr(align(1024))]
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pub struct LotsaPadding(usize);
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// Boxing a value with padding should not copy junk from the stack
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#[no_mangle]
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pub fn box_lotsa_padding() -> Box<LotsaPadding> {
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// CHECK-LABEL: @box_lotsa_padding
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// CHECK-NOT: alloca
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// CHECK-NOT: getelementptr
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// CHECK-NOT: memcpy
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// CHECK-NOT: memset
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Box::new(LotsaPadding(42))
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}
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// Hide the `allocalign` attribute in the declaration of __rust_alloc
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// from the CHECK-NOT above, and also verify the attributes got set reasonably.
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// CHECK: declare {{(dso_local )?}}noalias noundef ptr @{{.*}}__rust_alloc(i{{[0-9]+}} noundef, i{{[0-9]+}} allocalign noundef range(i{{[0-9]+}} 1, {{-2147483647|-9223372036854775807}})) unnamed_addr [[RUST_ALLOC_ATTRS:#[0-9]+]]
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// CHECK-DAG: attributes [[RUST_ALLOC_ATTRS]] = { {{.*}} allockind("alloc,uninitialized,aligned") allocsize(0) {{(uwtable )?}}"alloc-family"="__rust_alloc" {{.*}} }
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