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b2c717fa33
I was looking into `array::IntoIter` optimization, and noticed that it wasn't annotating the loads with `noundef` for simple things like `array::IntoIter<i32, N>`. Turned out to be a more general problem as `MaybeUninit::assume_init_read` isn't marking the load as initialized (<https://rust.godbolt.org/z/Mxd8TPTnv>), which is unfortunate since that's basically its reason to exist. This PR lowers `ptr::read(p)` to `copy *p` in MIR, which fortuitiously also improves the IR we give to LLVM for things like `mem::replace`.
47 lines
1.8 KiB
Plaintext
47 lines
1.8 KiB
Plaintext
error[E0080]: evaluation of constant value failed
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--> $SRC_DIR/core/src/ptr/mod.rs:LL:COL
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= note: dereferencing pointer failed: alloc5 has size 4, so pointer to 4 bytes starting at offset 4 is out-of-bounds
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note: inside `std::ptr::read::<u32>`
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--> $SRC_DIR/core/src/ptr/mod.rs:LL:COL
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note: inside `_READ`
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--> $DIR/out_of_bounds_read.rs:12:33
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LL | const _READ: u32 = unsafe { ptr::read(PAST_END_PTR) };
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| ^^^^^^^^^^^^^^^^^^^^^^^
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error[E0080]: evaluation of constant value failed
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--> $SRC_DIR/core/src/ptr/mod.rs:LL:COL
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= note: dereferencing pointer failed: alloc5 has size 4, so pointer to 4 bytes starting at offset 4 is out-of-bounds
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note: inside `std::ptr::read::<u32>`
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--> $SRC_DIR/core/src/ptr/mod.rs:LL:COL
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note: inside `ptr::const_ptr::<impl *const u32>::read`
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--> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL
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note: inside `_CONST_READ`
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--> $DIR/out_of_bounds_read.rs:13:39
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LL | const _CONST_READ: u32 = unsafe { PAST_END_PTR.read() };
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| ^^^^^^^^^^^^^^^^^^^
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error[E0080]: evaluation of constant value failed
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--> $SRC_DIR/core/src/ptr/mod.rs:LL:COL
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= note: dereferencing pointer failed: alloc5 has size 4, so pointer to 4 bytes starting at offset 4 is out-of-bounds
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note: inside `std::ptr::read::<u32>`
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--> $SRC_DIR/core/src/ptr/mod.rs:LL:COL
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note: inside `ptr::mut_ptr::<impl *mut u32>::read`
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--> $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
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note: inside `_MUT_READ`
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--> $DIR/out_of_bounds_read.rs:14:37
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LL | const _MUT_READ: u32 = unsafe { (PAST_END_PTR as *mut u32).read() };
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: aborting due to 3 previous errors
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For more information about this error, try `rustc --explain E0080`.
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