36 lines
1.1 KiB
Rust
36 lines
1.1 KiB
Rust
// skip-filecheck
|
|
// unit-test: CopyProp
|
|
//
|
|
// This attempts to mutate `a` via a pointer derived from `addr_of!(a)`. That is UB
|
|
// according to Miri. However, the decision to make this UB - and to allow
|
|
// rustc to rely on that fact for the purpose of optimizations - has not been
|
|
// finalized.
|
|
//
|
|
// As such, we include this test to ensure that copy prop does not rely on that
|
|
// fact. Specifically, if `addr_of!(a)` could not be used to modify a, it would
|
|
// be correct for CopyProp to replace all occurrences of `a` with `c` - but that
|
|
// would cause `f(true)` to output `false` instead of `true`.
|
|
|
|
#![feature(custom_mir, core_intrinsics)]
|
|
#![allow(unused_assignments)]
|
|
extern crate core;
|
|
use core::intrinsics::mir::*;
|
|
|
|
#[custom_mir(dialect = "analysis", phase = "post-cleanup")]
|
|
fn f(c: bool) -> bool {
|
|
mir!({
|
|
let a = c;
|
|
let p = core::ptr::addr_of!(a);
|
|
let p2 = core::ptr::addr_of_mut!(*p);
|
|
*p2 = false;
|
|
RET = c;
|
|
Return()
|
|
})
|
|
}
|
|
|
|
fn main() {
|
|
assert_eq!(true, f(true));
|
|
}
|
|
|
|
// EMIT_MIR mutate_through_pointer.f.CopyProp.diff
|