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Auto merge of rust-lang#115767 - matthiaskrgr:rollup-byf3lvq, r=matth…
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Rollup of 8 pull requests

Successful merges:

 - rust-lang#115548 (Extract parallel operations in `rustc_data_structures::sync` into a new `parallel` submodule)
 - rust-lang#115591 (Add regression test for LLVM 17-rc3 miscompile)
 - rust-lang#115631 (Don't ICE when computing ctype's `repr_nullable_ptr` for possibly-unsized ty)
 - rust-lang#115708 (fix homogeneous_aggregate not ignoring some ZST)
 - rust-lang#115730 (Some more small driver refactors)
 - rust-lang#115749 (Allow loading the SMIR for constants and statics)
 - rust-lang#115757 (Add a test for rust-lang#108030)
 - rust-lang#115761 (Update books)

r? `@ghost`
`@rustbot` modify labels: rollup
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@bors
bors committed Sep 11, 2023
2 parents e2b3676 + 059231f commit b4e54c6
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Showing 25 changed files with 447 additions and 201 deletions.
176 changes: 5 additions & 171 deletions compiler/rustc_data_structures/src/sync.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,19 +41,21 @@
//! [^2] `MTLockRef` is a typedef.

pub use crate::marker::*;
use parking_lot::Mutex;
use std::any::Any;
use std::collections::HashMap;
use std::hash::{BuildHasher, Hash};
use std::ops::{Deref, DerefMut};
use std::panic::{catch_unwind, resume_unwind, AssertUnwindSafe};

mod lock;
pub use lock::{Lock, LockGuard, Mode};

mod worker_local;
pub use worker_local::{Registry, WorkerLocal};

mod parallel;
#[cfg(parallel_compiler)]
pub use parallel::scope;
pub use parallel::{join, par_for_each_in, par_map, parallel_guard};

pub use std::sync::atomic::Ordering;
pub use std::sync::atomic::Ordering::SeqCst;

Expand Down Expand Up @@ -107,37 +109,6 @@ mod mode {

pub use mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode};

/// A guard used to hold panics that occur during a parallel section to later by unwound.
/// This is used for the parallel compiler to prevent fatal errors from non-deterministically
/// hiding errors by ensuring that everything in the section has completed executing before
/// continuing with unwinding. It's also used for the non-parallel code to ensure error message
/// output match the parallel compiler for testing purposes.
pub struct ParallelGuard {
panic: Mutex<Option<Box<dyn Any + std::marker::Send + 'static>>>,
}

impl ParallelGuard {
pub fn run<R>(&self, f: impl FnOnce() -> R) -> Option<R> {
catch_unwind(AssertUnwindSafe(f))
.map_err(|err| {
*self.panic.lock() = Some(err);
})
.ok()
}
}

/// This gives access to a fresh parallel guard in the closure and will unwind any panics
/// caught in it after the closure returns.
#[inline]
pub fn parallel_guard<R>(f: impl FnOnce(&ParallelGuard) -> R) -> R {
let guard = ParallelGuard { panic: Mutex::new(None) };
let ret = f(&guard);
if let Some(panic) = guard.panic.into_inner() {
resume_unwind(panic);
}
ret
}

cfg_if! {
if #[cfg(not(parallel_compiler))] {
use std::ops::Add;
Expand Down Expand Up @@ -229,44 +200,6 @@ cfg_if! {
pub type AtomicU32 = Atomic<u32>;
pub type AtomicU64 = Atomic<u64>;

pub fn join<A, B, RA, RB>(oper_a: A, oper_b: B) -> (RA, RB)
where A: FnOnce() -> RA,
B: FnOnce() -> RB
{
let (a, b) = parallel_guard(|guard| {
let a = guard.run(oper_a);
let b = guard.run(oper_b);
(a, b)
});
(a.unwrap(), b.unwrap())
}

#[macro_export]
macro_rules! parallel {
($($blocks:block),*) => {{
$crate::sync::parallel_guard(|guard| {
$(guard.run(|| $blocks);)*
});
}}
}

pub fn par_for_each_in<T: IntoIterator>(t: T, mut for_each: impl FnMut(T::Item) + Sync + Send) {
parallel_guard(|guard| {
t.into_iter().for_each(|i| {
guard.run(|| for_each(i));
});
})
}

pub fn par_map<T: IntoIterator, R, C: FromIterator<R>>(
t: T,
mut map: impl FnMut(<<T as IntoIterator>::IntoIter as Iterator>::Item) -> R,
) -> C {
parallel_guard(|guard| {
t.into_iter().filter_map(|i| guard.run(|| map(i))).collect()
})
}

pub use std::rc::Rc as Lrc;
pub use std::rc::Weak as Weak;
pub use std::cell::Ref as ReadGuard;
Expand Down Expand Up @@ -372,105 +305,6 @@ cfg_if! {

use std::thread;

#[inline]
pub fn join<A, B, RA: DynSend, RB: DynSend>(oper_a: A, oper_b: B) -> (RA, RB)
where
A: FnOnce() -> RA + DynSend,
B: FnOnce() -> RB + DynSend,
{
if mode::is_dyn_thread_safe() {
let oper_a = FromDyn::from(oper_a);
let oper_b = FromDyn::from(oper_b);
let (a, b) = rayon::join(move || FromDyn::from(oper_a.into_inner()()), move || FromDyn::from(oper_b.into_inner()()));
(a.into_inner(), b.into_inner())
} else {
let (a, b) = parallel_guard(|guard| {
let a = guard.run(oper_a);
let b = guard.run(oper_b);
(a, b)
});
(a.unwrap(), b.unwrap())
}
}

// This function only works when `mode::is_dyn_thread_safe()`.
pub fn scope<'scope, OP, R>(op: OP) -> R
where
OP: FnOnce(&rayon::Scope<'scope>) -> R + DynSend,
R: DynSend,
{
let op = FromDyn::from(op);
rayon::scope(|s| FromDyn::from(op.into_inner()(s))).into_inner()
}

/// Runs a list of blocks in parallel. The first block is executed immediately on
/// the current thread. Use that for the longest running block.
#[macro_export]
macro_rules! parallel {
(impl $fblock:block [$($c:expr,)*] [$block:expr $(, $rest:expr)*]) => {
parallel!(impl $fblock [$block, $($c,)*] [$($rest),*])
};
(impl $fblock:block [$($blocks:expr,)*] []) => {
::rustc_data_structures::sync::scope(|s| {
$(let block = rustc_data_structures::sync::FromDyn::from(|| $blocks);
s.spawn(move |_| block.into_inner()());)*
(|| $fblock)();
});
};
($fblock:block, $($blocks:block),*) => {
if rustc_data_structures::sync::is_dyn_thread_safe() {
// Reverse the order of the later blocks since Rayon executes them in reverse order
// when using a single thread. This ensures the execution order matches that
// of a single threaded rustc.
parallel!(impl $fblock [] [$($blocks),*]);
} else {
$crate::sync::parallel_guard(|guard| {
guard.run(|| $fblock);
$(guard.run(|| $blocks);)*
});
}
};
}

use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelIterator};

pub fn par_for_each_in<I, T: IntoIterator<Item = I> + IntoParallelIterator<Item = I>>(
t: T,
for_each: impl Fn(I) + DynSync + DynSend
) {
parallel_guard(|guard| {
if mode::is_dyn_thread_safe() {
let for_each = FromDyn::from(for_each);
t.into_par_iter().for_each(|i| {
guard.run(|| for_each(i));
});
} else {
t.into_iter().for_each(|i| {
guard.run(|| for_each(i));
});
}
});
}

pub fn par_map<
I,
T: IntoIterator<Item = I> + IntoParallelIterator<Item = I>,
R: std::marker::Send,
C: FromIterator<R> + FromParallelIterator<R>
>(
t: T,
map: impl Fn(I) -> R + DynSync + DynSend
) -> C {
parallel_guard(|guard| {
if mode::is_dyn_thread_safe() {
let map = FromDyn::from(map);
t.into_par_iter().filter_map(|i| guard.run(|| map(i))).collect()
} else {
t.into_iter().filter_map(|i| guard.run(|| map(i))).collect()
}
})
}

/// This makes locks panic if they are already held.
/// It is only useful when you are running in a single thread
const ERROR_CHECKING: bool = false;
Expand Down
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