codegen: use new {re,de,}allocator annotations in llvm
This obviates the patch that teaches LLVM internals about
_rust_{re,de}alloc functions by putting annotations directly in the IR
for the optimizer.
The sole test change is required to anchor FileCheck to the body of the
`box_uninitialized` method, so it doesn't see the `allocalign` on
`__rust_alloc` and get mad about the string `alloca` showing up. Since I
was there anyway, I added some checks on the attributes to prove the
right attributes got set.
While we're here, we also emit allocator attributes on
__rust_alloc_zeroed. This should allow LLVM to perform more
optimizations for zeroed blocks, and probably fixes #90032. [This
comment](https://github.com/rust-lang/rust/issues/24194#issuecomment-308791157)
mentions "weird UB-like behaviour with bitvec iterators in
rustc_data_structures" so we may need to back this change out if things
go wrong.
The new test cases require LLVM 15, so we copy them into LLVM
14-supporting versions, which we can delete when we drop LLVM 14.
This commit is contained in:
Augie Fackler
parent
2fdbf075cf
commit
130a1df71e
14 changed files with 356 additions and 4 deletions
26
src/test/codegen/box-maybe-uninit-llvm14.rs
Normal file
26
src/test/codegen/box-maybe-uninit-llvm14.rs
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@ -0,0 +1,26 @@
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// compile-flags: -O
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// Once we're done with llvm 14 and earlier, this test can be deleted.
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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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// FIXME: add a test for a bigger box. Currently broken, see
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// https://github.com/rust-lang/rust/issues/58201.
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// Hide the LLVM 15+ `allocalign` attribute in the declaration of __rust_alloc
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// from the CHECK-NOT above. We don't check the attributes here because we can't rely
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// on all of them being set until LLVM 15.
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// CHECK: declare noalias{{.*}} @__rust_alloc(i{{[0-9]+}}, i{{[0-9]+.*}})
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@ -1,4 +1,5 @@
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// compile-flags: -O
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// min-llvm-version: 15.0
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#![crate_type="lib"]
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use std::mem::MaybeUninit;
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@ -16,3 +17,9 @@ pub fn box_uninitialized() -> Box<MaybeUninit<usize>> {
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// FIXME: add a test for a bigger box. Currently broken, see
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// https://github.com/rust-lang/rust/issues/58201.
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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 noalias ptr @__rust_alloc(i{{[0-9]+}}, i{{[0-9]+}} allocalign) 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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144
src/test/codegen/vec-calloc-llvm14.rs
Normal file
144
src/test/codegen/vec-calloc-llvm14.rs
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@ -0,0 +1,144 @@
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// compile-flags: -O
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// only-x86_64
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// ignore-debug
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#![crate_type = "lib"]
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// CHECK-LABEL: @vec_zero_bytes
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#[no_mangle]
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pub fn vec_zero_bytes(n: usize) -> Vec<u8> {
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK-NOT: call {{.*}}llvm.memset
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// CHECK: call {{.*}}__rust_alloc_zeroed(
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK-NOT: call {{.*}}llvm.memset
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// CHECK: ret void
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vec![0; n]
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}
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// CHECK-LABEL: @vec_one_bytes
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#[no_mangle]
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pub fn vec_one_bytes(n: usize) -> Vec<u8> {
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc_zeroed(
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// CHECK: call {{.*}}__rust_alloc(
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// CHECK: call {{.*}}llvm.memset
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc_zeroed(
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// CHECK: ret void
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vec![1; n]
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}
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// CHECK-LABEL: @vec_zero_scalar
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#[no_mangle]
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pub fn vec_zero_scalar(n: usize) -> Vec<i32> {
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK: call {{.*}}__rust_alloc_zeroed(
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK: ret void
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vec![0; n]
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}
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// CHECK-LABEL: @vec_one_scalar
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#[no_mangle]
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pub fn vec_one_scalar(n: usize) -> Vec<i32> {
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc_zeroed(
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// CHECK: call {{.*}}__rust_alloc(
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc_zeroed(
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// CHECK: ret void
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vec![1; n]
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}
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// CHECK-LABEL: @vec_zero_rgb48
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#[no_mangle]
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pub fn vec_zero_rgb48(n: usize) -> Vec<[u16; 3]> {
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK: call {{.*}}__rust_alloc_zeroed(
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK: ret void
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vec![[0, 0, 0]; n]
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}
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// CHECK-LABEL: @vec_zero_array_16
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#[no_mangle]
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pub fn vec_zero_array_16(n: usize) -> Vec<[i64; 16]> {
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK: call {{.*}}__rust_alloc_zeroed(
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK: ret void
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vec![[0_i64; 16]; n]
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}
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// CHECK-LABEL: @vec_zero_tuple
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#[no_mangle]
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pub fn vec_zero_tuple(n: usize) -> Vec<(i16, u8, char)> {
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK: call {{.*}}__rust_alloc_zeroed(
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc(
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// CHECK: ret void
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vec![(0, 0, '\0'); n]
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}
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// CHECK-LABEL: @vec_non_zero_tuple
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#[no_mangle]
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pub fn vec_non_zero_tuple(n: usize) -> Vec<(i16, u8, char)> {
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc_zeroed(
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// CHECK: call {{.*}}__rust_alloc(
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// CHECK-NOT: call {{.*}}alloc::vec::from_elem
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// CHECK-NOT: call {{.*}}reserve
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// CHECK-NOT: call {{.*}}__rust_alloc_zeroed(
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// CHECK: ret void
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vec![(0, 0, 'A'); n]
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}
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@ -1,6 +1,7 @@
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// compile-flags: -O
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// only-x86_64
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// ignore-debug
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// min-llvm-version: 15.0
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#![crate_type = "lib"]
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@ -142,3 +143,8 @@ pub fn vec_non_zero_tuple(n: usize) -> Vec<(i16, u8, char)> {
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// CHECK: ret void
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vec![(0, 0, 'A'); n]
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}
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// Ensure that __rust_alloc_zeroed gets the right attributes for LLVM to optimize it away.
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// CHECK: declare noalias ptr @__rust_alloc_zeroed(i64, i64 allocalign) unnamed_addr [[RUST_ALLOC_ZEROED_ATTRS:#[0-9]+]]
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// CHECK-DAG: attributes [[RUST_ALLOC_ZEROED_ATTRS]] = { {{.*}} allockind("alloc,zeroed,aligned") allocsize(0) uwtable "alloc-family"="__rust_alloc" {{.*}} }
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