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Auto merge of rust-lang#115794 - cjgillot:aggregate-no-box, r=davidtwco
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Do not create a DerefLen place for `Box<[T]>`.

Fixes rust-lang#115789
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bors committed Sep 20, 2023
2 parents ed33e40 + 82c05fe commit 4f5d3b9
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Showing 6 changed files with 492 additions and 1 deletion.
4 changes: 3 additions & 1 deletion compiler/rustc_mir_dataflow/src/value_analysis.rs
Original file line number Diff line number Diff line change
Expand Up @@ -758,7 +758,9 @@ impl Map {
self.value_count += 1;
}

if let Some(ref_ty) = ty.builtin_deref(true) && let ty::Slice(..) = ref_ty.ty.kind() {
if let ty::Ref(_, ref_ty, _) | ty::RawPtr(ty::TypeAndMut { ty: ref_ty, .. }) = ty.kind()
&& let ty::Slice(..) = ref_ty.kind()
{
assert!(self.places[place].value_index.is_none(), "slices are not scalars");

// Prepend new child to the linked list.
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,117 @@
- // MIR for `main` before DataflowConstProp
+ // MIR for `main` after DataflowConstProp

fn main() -> () {
let mut _0: ();
let _1: A;
let mut _2: std::boxed::Box<[bool]>;
scope 1 {
debug a => _1;
}
scope 2 (inlined <Box<[bool]> as Default>::default) {
let _3: std::ptr::Unique<[bool]>;
let mut _4: std::ptr::Unique<[bool; 0]>;
scope 3 {
debug ptr => _3;
}
scope 4 (inlined Unique::<[bool; 0]>::dangling) {
let mut _5: std::ptr::NonNull<[bool; 0]>;
scope 5 (inlined NonNull::<[bool; 0]>::dangling) {
let mut _7: usize;
scope 6 {
let _6: *mut [bool; 0];
scope 7 {
debug ptr => _6;
scope 11 (inlined NonNull::<[bool; 0]>::new_unchecked) {
debug ptr => _6;
let mut _8: *const [bool; 0];
scope 12 {
scope 13 (inlined NonNull::<T>::new_unchecked::runtime::<[bool; 0]>) {
debug ptr => _6;
let _9: !;
scope 14 (inlined ptr::mut_ptr::<impl *mut [bool; 0]>::is_null) {
debug self => _6;
let mut _10: *mut u8;
scope 15 {
scope 16 (inlined ptr::mut_ptr::<impl *mut T>::is_null::runtime_impl) {
debug ptr => _10;
let mut _11: usize;
scope 17 (inlined ptr::mut_ptr::<impl *mut u8>::addr) {
debug self => _10;
let mut _12: *mut ();
scope 18 {
scope 19 (inlined ptr::mut_ptr::<impl *mut u8>::cast::<()>) {
debug self => _10;
}
}
}
}
}
}
}
}
}
}
scope 8 (inlined align_of::<[bool; 0]>) {
}
scope 9 (inlined invalid_mut::<[bool; 0]>) {
debug addr => _7;
scope 10 {
}
}
}
}
}
}

bb0: {
StorageLive(_1);
StorageLive(_2);
StorageLive(_3);
StorageLive(_4);
StorageLive(_5);
StorageLive(_6);
StorageLive(_7);
_7 = const 1_usize;
_6 = const {0x1 as *mut [bool; 0]};
StorageDead(_7);
StorageLive(_8);
StorageLive(_10);
_10 = const {0x1 as *mut u8};
StorageLive(_11);
StorageLive(_12);
_12 = const {0x1 as *mut ()};
_11 = const 1_usize;
StorageDead(_12);
StorageDead(_10);
switchInt(const 1_usize) -> [0: bb2, otherwise: bb3];
}

bb1: {
StorageDead(_1);
return;
}

bb2: {
StorageDead(_11);
_9 = core::panicking::panic_nounwind(const "unsafe precondition(s) violated: NonNull::new_unchecked requires that the pointer is non-null") -> unwind unreachable;
}

bb3: {
StorageDead(_11);
_8 = const {0x1 as *const [bool; 0]};
_5 = const NonNull::<[bool; 0]> {{ pointer: {0x1 as *const [bool; 0]} }};
StorageDead(_8);
StorageDead(_6);
_4 = const Unique::<[bool; 0]> {{ pointer: NonNull::<[bool; 0]> {{ pointer: {0x1 as *const [bool; 0]} }}, _marker: PhantomData::<[bool; 0]> }};
StorageDead(_5);
_3 = const Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }};
StorageDead(_4);
_2 = const Box::<[bool]>(Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }}, std::alloc::Global);
StorageDead(_3);
_1 = A { foo: const Box::<[bool]>(Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }}, std::alloc::Global) };
StorageDead(_2);
drop(_1) -> [return: bb1, unwind unreachable];
}
}

Original file line number Diff line number Diff line change
@@ -0,0 +1,121 @@
- // MIR for `main` before DataflowConstProp
+ // MIR for `main` after DataflowConstProp

fn main() -> () {
let mut _0: ();
let _1: A;
let mut _2: std::boxed::Box<[bool]>;
scope 1 {
debug a => _1;
}
scope 2 (inlined <Box<[bool]> as Default>::default) {
let _3: std::ptr::Unique<[bool]>;
let mut _4: std::ptr::Unique<[bool; 0]>;
scope 3 {
debug ptr => _3;
}
scope 4 (inlined Unique::<[bool; 0]>::dangling) {
let mut _5: std::ptr::NonNull<[bool; 0]>;
scope 5 (inlined NonNull::<[bool; 0]>::dangling) {
let mut _7: usize;
scope 6 {
let _6: *mut [bool; 0];
scope 7 {
debug ptr => _6;
scope 11 (inlined NonNull::<[bool; 0]>::new_unchecked) {
debug ptr => _6;
let mut _8: *const [bool; 0];
scope 12 {
scope 13 (inlined NonNull::<T>::new_unchecked::runtime::<[bool; 0]>) {
debug ptr => _6;
let _9: !;
scope 14 (inlined ptr::mut_ptr::<impl *mut [bool; 0]>::is_null) {
debug self => _6;
let mut _10: *mut u8;
scope 15 {
scope 16 (inlined ptr::mut_ptr::<impl *mut T>::is_null::runtime_impl) {
debug ptr => _10;
let mut _11: usize;
scope 17 (inlined ptr::mut_ptr::<impl *mut u8>::addr) {
debug self => _10;
let mut _12: *mut ();
scope 18 {
scope 19 (inlined ptr::mut_ptr::<impl *mut u8>::cast::<()>) {
debug self => _10;
}
}
}
}
}
}
}
}
}
}
scope 8 (inlined align_of::<[bool; 0]>) {
}
scope 9 (inlined invalid_mut::<[bool; 0]>) {
debug addr => _7;
scope 10 {
}
}
}
}
}
}

bb0: {
StorageLive(_1);
StorageLive(_2);
StorageLive(_3);
StorageLive(_4);
StorageLive(_5);
StorageLive(_6);
StorageLive(_7);
_7 = const 1_usize;
_6 = const {0x1 as *mut [bool; 0]};
StorageDead(_7);
StorageLive(_8);
StorageLive(_10);
_10 = const {0x1 as *mut u8};
StorageLive(_11);
StorageLive(_12);
_12 = const {0x1 as *mut ()};
_11 = const 1_usize;
StorageDead(_12);
StorageDead(_10);
switchInt(const 1_usize) -> [0: bb3, otherwise: bb4];
}

bb1: {
StorageDead(_1);
return;
}

bb2 (cleanup): {
resume;
}

bb3: {
StorageDead(_11);
_9 = core::panicking::panic_nounwind(const "unsafe precondition(s) violated: NonNull::new_unchecked requires that the pointer is non-null") -> unwind unreachable;
}

bb4: {
StorageDead(_11);
_8 = const {0x1 as *const [bool; 0]};
_5 = const NonNull::<[bool; 0]> {{ pointer: {0x1 as *const [bool; 0]} }};
StorageDead(_8);
StorageDead(_6);
_4 = const Unique::<[bool; 0]> {{ pointer: NonNull::<[bool; 0]> {{ pointer: {0x1 as *const [bool; 0]} }}, _marker: PhantomData::<[bool; 0]> }};
StorageDead(_5);
_3 = const Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }};
StorageDead(_4);
_2 = const Box::<[bool]>(Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }}, std::alloc::Global);
StorageDead(_3);
_1 = A { foo: const Box::<[bool]>(Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }}, std::alloc::Global) };
StorageDead(_2);
drop(_1) -> [return: bb1, unwind: bb2];
}
}

Original file line number Diff line number Diff line change
@@ -0,0 +1,117 @@
- // MIR for `main` before DataflowConstProp
+ // MIR for `main` after DataflowConstProp

fn main() -> () {
let mut _0: ();
let _1: A;
let mut _2: std::boxed::Box<[bool]>;
scope 1 {
debug a => _1;
}
scope 2 (inlined <Box<[bool]> as Default>::default) {
let _3: std::ptr::Unique<[bool]>;
let mut _4: std::ptr::Unique<[bool; 0]>;
scope 3 {
debug ptr => _3;
}
scope 4 (inlined Unique::<[bool; 0]>::dangling) {
let mut _5: std::ptr::NonNull<[bool; 0]>;
scope 5 (inlined NonNull::<[bool; 0]>::dangling) {
let mut _7: usize;
scope 6 {
let _6: *mut [bool; 0];
scope 7 {
debug ptr => _6;
scope 11 (inlined NonNull::<[bool; 0]>::new_unchecked) {
debug ptr => _6;
let mut _8: *const [bool; 0];
scope 12 {
scope 13 (inlined NonNull::<T>::new_unchecked::runtime::<[bool; 0]>) {
debug ptr => _6;
let _9: !;
scope 14 (inlined ptr::mut_ptr::<impl *mut [bool; 0]>::is_null) {
debug self => _6;
let mut _10: *mut u8;
scope 15 {
scope 16 (inlined ptr::mut_ptr::<impl *mut T>::is_null::runtime_impl) {
debug ptr => _10;
let mut _11: usize;
scope 17 (inlined ptr::mut_ptr::<impl *mut u8>::addr) {
debug self => _10;
let mut _12: *mut ();
scope 18 {
scope 19 (inlined ptr::mut_ptr::<impl *mut u8>::cast::<()>) {
debug self => _10;
}
}
}
}
}
}
}
}
}
}
scope 8 (inlined align_of::<[bool; 0]>) {
}
scope 9 (inlined invalid_mut::<[bool; 0]>) {
debug addr => _7;
scope 10 {
}
}
}
}
}
}

bb0: {
StorageLive(_1);
StorageLive(_2);
StorageLive(_3);
StorageLive(_4);
StorageLive(_5);
StorageLive(_6);
StorageLive(_7);
_7 = const 1_usize;
_6 = const {0x1 as *mut [bool; 0]};
StorageDead(_7);
StorageLive(_8);
StorageLive(_10);
_10 = const {0x1 as *mut u8};
StorageLive(_11);
StorageLive(_12);
_12 = const {0x1 as *mut ()};
_11 = const 1_usize;
StorageDead(_12);
StorageDead(_10);
switchInt(const 1_usize) -> [0: bb2, otherwise: bb3];
}

bb1: {
StorageDead(_1);
return;
}

bb2: {
StorageDead(_11);
_9 = core::panicking::panic_nounwind(const "unsafe precondition(s) violated: NonNull::new_unchecked requires that the pointer is non-null") -> unwind unreachable;
}

bb3: {
StorageDead(_11);
_8 = const {0x1 as *const [bool; 0]};
_5 = const NonNull::<[bool; 0]> {{ pointer: {0x1 as *const [bool; 0]} }};
StorageDead(_8);
StorageDead(_6);
_4 = const Unique::<[bool; 0]> {{ pointer: NonNull::<[bool; 0]> {{ pointer: {0x1 as *const [bool; 0]} }}, _marker: PhantomData::<[bool; 0]> }};
StorageDead(_5);
_3 = const Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }};
StorageDead(_4);
_2 = const Box::<[bool]>(Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }}, std::alloc::Global);
StorageDead(_3);
_1 = A { foo: const Box::<[bool]>(Unique::<[bool]> {{ pointer: NonNull::<[bool]> {{ pointer: ByRef { alloc: ConstAllocation { .. }, offset: Size(0 bytes) }: *const [bool] }}, _marker: PhantomData::<[bool]> }}, std::alloc::Global) };
StorageDead(_2);
drop(_1) -> [return: bb1, unwind unreachable];
}
}

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