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Rollup merge of #95221 - RalfJung:check_and_deref_ptr, r=oli-obk

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interpret/memory: simplify check_and_deref_ptr

*Finally* I saw a way to make this code simpler. The odd preprocessing in `let ptr_or_addr =` has bothered me since forever, but it actually became unnecessary in the last provenance refactoring. :)

This also leads to slightly more explicit error messages as a nice side-effect. 🎉

r? `@oli-obk`
This commit is contained in:
Matthias Krüger 2022-03-23 22:13:24 +01:00 committed by GitHub
commit 23ef234bf7
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GPG Key ID: 4AEE18F83AFDEB23
8 changed files with 14 additions and 24 deletions
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20
compiler/rustc_const_eval/src/interpret/memory.rs
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@ -427,22 +427,12 @@ fn check_offset_align(offset: u64, align: Align) -> InterpResult<'static> {
}
}
// Extract from the pointer an `Option<AllocId>` and an offset, which is relative to the
// allocation or (if that is `None`) an absolute address.
let ptr_or_addr = if size.bytes() == 0 {
// Let's see what we can do, but don't throw errors if there's nothing there.
self.ptr_try_get_alloc(ptr)
} else {
// A "real" access, we insist on getting an `AllocId`.
Ok(self.ptr_get_alloc(ptr)?)
};
Ok(match ptr_or_addr {
Ok(match self.ptr_try_get_alloc(ptr) {
Err(addr) => {
// No memory is actually being accessed.
debug_assert!(size.bytes() == 0);
// Must be non-null.
if addr == 0 {
throw_ub!(DanglingIntPointer(0, msg))
// We couldn't get a proper allocation. This is only okay if the access size is 0,
// and the address is not null.
if size.bytes() > 0 || addr == 0 {
throw_ub!(DanglingIntPointer(addr, msg));
}
// Must be aligned.
if let Some(align) = align {

2
src/test/ui/consts/const-deref-ptr.stderr
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@ -2,7 +2,7 @@ error[E0080]: could not evaluate static initializer
--> $DIR/const-deref-ptr.rs:4:29
|
LL | static C: u64 = unsafe {*(0xdeadbeef as *const u64)};
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 0xdeadbeef is not a valid pointer
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ dereferencing pointer failed: 0xdeadbeef is not a valid pointer
error: aborting due to previous error

4
src/test/ui/consts/const-eval/const_raw_ptr_ops2.stderr
View File

@ -2,13 +2,13 @@ error[E0080]: evaluation of constant value failed
--> $DIR/const_raw_ptr_ops2.rs:7:26
|
LL | const Z2: i32 = unsafe { *(42 as *const i32) };
| ^^^^^^^^^^^^^^^^^^^ 0x2a is not a valid pointer
| ^^^^^^^^^^^^^^^^^^^ dereferencing pointer failed: 0x2a is not a valid pointer
error[E0080]: evaluation of constant value failed
--> $DIR/const_raw_ptr_ops2.rs:9:26
|
LL | const Z3: i32 = unsafe { *(44 as *const i32) };
| ^^^^^^^^^^^^^^^^^^^ 0x2c is not a valid pointer
| ^^^^^^^^^^^^^^^^^^^ dereferencing pointer failed: 0x2c is not a valid pointer
error: aborting due to 2 previous errors

2
src/test/ui/consts/const-eval/ub-wide-ptr.32bit.stderr
View File

@ -296,7 +296,7 @@ error[E0080]: could not evaluate static initializer
--> $DIR/ub-wide-ptr.rs:135:5
|
LL | mem::transmute::<_, &dyn Trait>((&92u8, 0usize))
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ null pointer is not a valid pointer for this operation
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: null pointer is not a valid pointer
error[E0080]: could not evaluate static initializer
--> $DIR/ub-wide-ptr.rs:139:5

2
src/test/ui/consts/const-eval/ub-wide-ptr.64bit.stderr
View File

@ -296,7 +296,7 @@ error[E0080]: could not evaluate static initializer
--> $DIR/ub-wide-ptr.rs:135:5
|
LL | mem::transmute::<_, &dyn Trait>((&92u8, 0usize))
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ null pointer is not a valid pointer for this operation
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: null pointer is not a valid pointer
error[E0080]: could not evaluate static initializer
--> $DIR/ub-wide-ptr.rs:139:5

2
src/test/ui/consts/const-mut-refs/mut_ref_in_final_dynamic_check.stderr
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@ -4,7 +4,7 @@ error[E0080]: evaluation of constant value failed
LL | Some(&mut *(42 as *mut i32))
| ^^^^^^^^^^^^^^^^^^^^^^
| |
| 0x2a is not a valid pointer
| dereferencing pointer failed: 0x2a is not a valid pointer
| inside `helper` at $DIR/mut_ref_in_final_dynamic_check.rs:13:10
...
LL | const A: Option<&mut i32> = helper();

4
src/test/ui/consts/offset_ub.stderr
View File

@ -130,7 +130,7 @@ error[E0080]: evaluation of constant value failed
LL | unsafe { intrinsics::offset(self, count) as *mut T }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| 0x1 is not a valid pointer
| pointer arithmetic failed: 0x1 is not a valid pointer
| inside `ptr::mut_ptr::<impl *mut u8>::offset` at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
|
::: $DIR/offset_ub.rs:19:42
@ -158,7 +158,7 @@ error[E0080]: evaluation of constant value failed
LL | unsafe { intrinsics::offset(self, count) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| 0x7f..f is not a valid pointer
| pointer arithmetic failed: 0x7f..f is not a valid pointer
| inside `ptr::const_ptr::<impl *const u8>::offset` at $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
|
::: $DIR/offset_ub.rs:25:47

2
src/test/ui/error-codes/E0396-fixed.stderr
View File

@ -2,7 +2,7 @@ error[E0080]: evaluation of constant value failed
--> $DIR/E0396-fixed.rs:5:28
|
LL | const VALUE: u8 = unsafe { *REG_ADDR };
| ^^^^^^^^^ 0x5f3759df is not a valid pointer
| ^^^^^^^^^ dereferencing pointer failed: 0x5f3759df is not a valid pointer
error: aborting due to previous error