Auto merge of #93670 - erikdesjardins:noundef, r=nikic

Apply noundef attribute to &T, &mut T, Box<T>, bool

This doesn't handle `char` because it's a bit awkward to distinguish it from `u32` at this point in codegen.

Note that this _does not_ change whether or not it is UB for `&`, `&mut`, or `Box` to point to undef. It only applies to the pointer itself, not the pointed-to memory.

Fixes (partially) #74378.

r? `@nikic` cc `@RalfJung`

1 files changed, 43 insertions, 20 deletions

diff --git a/src/test/codegen/function-arguments.rs b/src/test/codegen/function-arguments.rs
index 3e10e227e55..17b54d86cb0 100644
--- a/src/test/codegen/function-arguments.rs
+++ b/src/test/codegen/function-arguments.rs
@@ -3,6 +3,8 @@
 #![crate_type = "lib"]
 #![feature(rustc_attrs)]
 
+use std::mem::MaybeUninit;
+
 pub struct S {
   _field: [i32; 8],
 }
@@ -11,68 +13,79 @@ pub struct UnsafeInner {
   _field: std::cell::UnsafeCell<i16>,
 }
 
-// CHECK: zeroext i1 @boolean(i1 zeroext %x)
+// CHECK: noundef zeroext i1 @boolean(i1 noundef zeroext %x)
 #[no_mangle]
 pub fn boolean(x: bool) -> bool {
   x
 }
 
-// CHECK: @readonly_borrow(i32* noalias readonly align 4 dereferenceable(4) %_1)
+// CHECK: i8 @maybeuninit_boolean(i8 %x)
+#[no_mangle]
+pub fn maybeuninit_boolean(x: MaybeUninit<bool>) -> MaybeUninit<bool> {
+  x
+}
+
+// CHECK: @readonly_borrow(i32* noalias noundef readonly align 4 dereferenceable(4) %_1)
 // FIXME #25759 This should also have `nocapture`
 #[no_mangle]
 pub fn readonly_borrow(_: &i32) {
 }
 
-// CHECK: @static_borrow(i32* noalias readonly align 4 dereferenceable(4) %_1)
+// CHECK: @static_borrow(i32* noalias noundef readonly align 4 dereferenceable(4) %_1)
 // static borrow may be captured
 #[no_mangle]
 pub fn static_borrow(_: &'static i32) {
 }
 
-// CHECK: @named_borrow(i32* noalias readonly align 4 dereferenceable(4) %_1)
+// CHECK: @named_borrow(i32* noalias noundef readonly align 4 dereferenceable(4) %_1)
 // borrow with named lifetime may be captured
 #[no_mangle]
 pub fn named_borrow<'r>(_: &'r i32) {
 }
 
-// CHECK: @unsafe_borrow(i16* align 2 dereferenceable(2) %_1)
+// CHECK: @unsafe_borrow(i16* noundef align 2 dereferenceable(2) %_1)
 // unsafe interior means this isn't actually readonly and there may be aliases ...
 #[no_mangle]
 pub fn unsafe_borrow(_: &UnsafeInner) {
 }
 
-// CHECK: @mutable_unsafe_borrow(i16* noalias align 2 dereferenceable(2) %_1)
+// CHECK: @mutable_unsafe_borrow(i16* noalias noundef align 2 dereferenceable(2) %_1)
 // ... unless this is a mutable borrow, those never alias
 #[no_mangle]
 pub fn mutable_unsafe_borrow(_: &mut UnsafeInner) {
 }
 
-// CHECK: @mutable_borrow(i32* noalias align 4 dereferenceable(4) %_1)
+// CHECK: @mutable_borrow(i32* noalias noundef align 4 dereferenceable(4) %_1)
 // FIXME #25759 This should also have `nocapture`
 #[no_mangle]
 pub fn mutable_borrow(_: &mut i32) {
 }
 
-// CHECK: @indirect_struct(%S* noalias nocapture dereferenceable(32) %_1)
+// CHECK: @indirect_struct(%S* noalias nocapture noundef dereferenceable(32) %_1)
 #[no_mangle]
 pub fn indirect_struct(_: S) {
 }
 
-// CHECK: @borrowed_struct(%S* noalias readonly align 4 dereferenceable(32) %_1)
+// CHECK: @borrowed_struct(%S* noalias noundef readonly align 4 dereferenceable(32) %_1)
 // FIXME #25759 This should also have `nocapture`
 #[no_mangle]
 pub fn borrowed_struct(_: &S) {
 }
 
+// CHECK: @raw_struct(%S* %_1)
+#[no_mangle]
+pub fn raw_struct(_: *const S) {
+}
+
 // `Box` can get deallocated during execution of the function, so it should
 // not get `dereferenceable`.
-// CHECK: noalias nonnull align 4 i32* @_box(i32* noalias nonnull align 4 %x)
+// CHECK: noalias noundef nonnull align 4 i32* @_box(i32* noalias noundef nonnull align 4 %x)
 #[no_mangle]
 pub fn _box(x: Box<i32>) -> Box<i32> {
   x
 }
 
-// CHECK: @struct_return(%S* noalias nocapture sret(%S) dereferenceable(32){{( %0)?}})
+// CHECK: @struct_return(%S* noalias nocapture noundef sret(%S) dereferenceable(32){{( %0)?}})
 #[no_mangle]
 pub fn struct_return() -> S {
   S {
@@ -86,48 +99,58 @@ pub fn struct_return() -> S {
 pub fn helper(_: usize) {
 }
 
-// CHECK: @slice([0 x i8]* noalias nonnull readonly align 1 %_1.0, [[USIZE]] %_1.1)
+// CHECK: @slice([0 x i8]* noalias noundef nonnull readonly align 1 %_1.0, [[USIZE]] %_1.1)
 // FIXME #25759 This should also have `nocapture`
 #[no_mangle]
 pub fn slice(_: &[u8]) {
 }
 
-// CHECK: @mutable_slice([0 x i8]* noalias nonnull align 1 %_1.0, [[USIZE]] %_1.1)
+// CHECK: @mutable_slice([0 x i8]* noalias noundef nonnull align 1 %_1.0, [[USIZE]] %_1.1)
 // FIXME #25759 This should also have `nocapture`
 #[no_mangle]
 pub fn mutable_slice(_: &mut [u8]) {
 }
 
-// CHECK: @unsafe_slice([0 x i16]* nonnull align 2 %_1.0, [[USIZE]] %_1.1)
+// CHECK: @unsafe_slice([0 x i16]* noundef nonnull align 2 %_1.0, [[USIZE]] %_1.1)
 // unsafe interior means this isn't actually readonly and there may be aliases ...
 #[no_mangle]
 pub fn unsafe_slice(_: &[UnsafeInner]) {
 }
 
-// CHECK: @str([0 x i8]* noalias nonnull readonly align 1 %_1.0, [[USIZE]] %_1.1)
+// CHECK: @raw_slice([0 x i8]* %_1.0, [[USIZE]] %_1.1)
+#[no_mangle]
+pub fn raw_slice(_: *const [u8]) {
+}
+
+// CHECK: @str([0 x i8]* noalias noundef nonnull readonly align 1 %_1.0, [[USIZE]] %_1.1)
 // FIXME #25759 This should also have `nocapture`
 #[no_mangle]
 pub fn str(_: &[u8]) {
 }
 
-// CHECK: @trait_borrow({}* nonnull align 1 %_1.0, [3 x [[USIZE]]]* noalias readonly align {{.*}} dereferenceable({{.*}}) %_1.1)
+// CHECK: @trait_borrow({}* noundef nonnull align 1 %_1.0, [3 x [[USIZE]]]* noalias noundef readonly align {{.*}} dereferenceable({{.*}}) %_1.1)
 // FIXME #25759 This should also have `nocapture`
 #[no_mangle]
 pub fn trait_borrow(_: &Drop) {
 }
 
-// CHECK: @trait_box({}* noalias nonnull align 1{{( %0)?}}, [3 x [[USIZE]]]* noalias readonly align {{.*}} dereferenceable({{.*}}){{( %1)?}})
+// CHECK: @trait_raw({}* %_1.0, [3 x [[USIZE]]]* noalias noundef readonly align {{.*}} dereferenceable({{.*}}) %_1.1)
+#[no_mangle]
+pub fn trait_raw(_: *const Drop) {
+}
+
+// CHECK: @trait_box({}* noalias noundef nonnull align 1{{( %0)?}}, [3 x [[USIZE]]]* noalias noundef readonly align {{.*}} dereferenceable({{.*}}){{( %1)?}})
 #[no_mangle]
 pub fn trait_box(_: Box<Drop>) {
 }
 
-// CHECK: { i8*, i8* } @trait_option(i8* noalias align 1 %x.0, i8* %x.1)
+// CHECK: { i8*, i8* } @trait_option(i8* noalias noundef align 1 %x.0, i8* %x.1)
 #[no_mangle]
 pub fn trait_option(x: Option<Box<Drop>>) -> Option<Box<Drop>> {
   x
 }
 
-// CHECK: { [0 x i16]*, [[USIZE]] } @return_slice([0 x i16]* noalias nonnull readonly align 2 %x.0, [[USIZE]] %x.1)
+// CHECK: { [0 x i16]*, [[USIZE]] } @return_slice([0 x i16]* noalias noundef nonnull readonly align 2 %x.0, [[USIZE]] %x.1)
 #[no_mangle]
 pub fn return_slice(x: &[u16]) -> &[u16] {
   x
@@ -139,7 +162,7 @@ pub fn enum_id_1(x: Option<Result<u16, u16>>) -> Option<Result<u16, u16>> {
   x
 }
 
-// CHECK: { i8, i8 } @enum_id_2(i1 zeroext %x.0, i8 %x.1)
+// CHECK: { i8, i8 } @enum_id_2(i1 noundef zeroext %x.0, i8 %x.1)
 #[no_mangle]
 pub fn enum_id_2(x: Option<u8>) -> Option<u8> {
   x