88 lines
2.3 KiB
Rust
88 lines
2.3 KiB
Rust
//@compile-flags: -Zmiri-ignore-leaks
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// https://plv.mpi-sws.org/scfix/paper.pdf
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// 2.2 Second Problem: SC Fences are Too Weak
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// This test should pass under the C++20 model Rust is using.
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// Unfortunately, Miri's weak memory emulation only follows the C++11 model
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// as we don't know how to correctly emulate C++20's revised SC semantics,
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// so we have to stick to C++11 emulation from existing research.
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use std::sync::atomic::Ordering::*;
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use std::sync::atomic::{fence, AtomicUsize};
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use std::thread::spawn;
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// Spins until it reads the given value
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fn reads_value(loc: &AtomicUsize, val: usize) -> usize {
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while loc.load(Relaxed) != val {
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std::hint::spin_loop();
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}
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val
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}
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// We can't create static items because we need to run each test
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// multiple tests
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fn static_atomic(val: usize) -> &'static AtomicUsize {
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let ret = Box::leak(Box::new(AtomicUsize::new(val)));
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// A workaround to put the initialization value in the store buffer.
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// See https://github.com/rust-lang/miri/issues/2164
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ret.load(Relaxed);
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ret
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}
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fn test_cpp20_rwc_syncs() {
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/*
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int main() {
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atomic_int x = 0;
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atomic_int y = 0;
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{{{ x.store(1,mo_relaxed);
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||| { r1=x.load(mo_relaxed).readsvalue(1);
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fence(mo_seq_cst);
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r2=y.load(mo_relaxed); }
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||| { y.store(1,mo_relaxed);
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fence(mo_seq_cst);
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r3=x.load(mo_relaxed); }
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}}}
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return 0;
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}
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*/
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let x = static_atomic(0);
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let y = static_atomic(0);
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let j1 = spawn(move || {
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x.store(1, Relaxed);
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});
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let j2 = spawn(move || {
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reads_value(&x, 1);
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fence(SeqCst);
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y.load(Relaxed)
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});
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let j3 = spawn(move || {
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y.store(1, Relaxed);
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fence(SeqCst);
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x.load(Relaxed)
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});
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j1.join().unwrap();
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let b = j2.join().unwrap();
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let c = j3.join().unwrap();
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// We cannot write assert_ne!() since ui_test's fail
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// tests expect exit status 1, whereas panics produce 101.
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// Our ui_test does not yet support overriding failure status codes.
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if (b, c) == (0, 0) {
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// This *should* be unreachable, but Miri will reach it.
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unsafe {
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std::hint::unreachable_unchecked(); //~ERROR: unreachable
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}
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}
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}
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pub fn main() {
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for _ in 0..500 {
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test_cpp20_rwc_syncs();
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}
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}
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