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Rename/restructure memory ordering intrinsics.
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@m-ou-se
m-ou-se committed Jun 22, 2022
1 parent 8bf9c20 commit 2d02416
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Showing 11 changed files with 693 additions and 375 deletions.
1 change: 1 addition & 0 deletions compiler/rustc_codegen_ssa/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
#![feature(associated_type_bounds)]
#![feature(strict_provenance)]
#![feature(int_roundings)]
#![feature(if_let_guard)]
#![recursion_limit = "256"]
#![allow(rustc::potential_query_instability)]

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58 changes: 26 additions & 32 deletions compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
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Expand Up @@ -376,32 +376,23 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
}

// This requires that atomic intrinsics follow a specific naming pattern:
// "atomic_<operation>[_<ordering>]", and no ordering means SeqCst
name if name_str.starts_with("atomic_") => {
// "atomic_<operation>[_<ordering>]"
name if let Some(atomic) = name_str.strip_prefix("atomic_") => {
use crate::common::AtomicOrdering::*;
use crate::common::{AtomicRmwBinOp, SynchronizationScope};

let split: Vec<_> = name_str.split('_').collect();

let is_cxchg = split[1] == "cxchg" || split[1] == "cxchgweak";
let (order, failorder) = match split.len() {
2 => (SequentiallyConsistent, SequentiallyConsistent),
3 => match split[2] {
"unordered" => (Unordered, Unordered),
"relaxed" => (Relaxed, Relaxed),
"acq" => (Acquire, Acquire),
"rel" => (Release, Relaxed),
"acqrel" => (AcquireRelease, Acquire),
"failrelaxed" if is_cxchg => (SequentiallyConsistent, Relaxed),
"failacq" if is_cxchg => (SequentiallyConsistent, Acquire),
_ => bx.sess().fatal("unknown ordering in atomic intrinsic"),
},
4 => match (split[2], split[3]) {
("acq", "failrelaxed") if is_cxchg => (Acquire, Relaxed),
("acqrel", "failrelaxed") if is_cxchg => (AcquireRelease, Relaxed),
_ => bx.sess().fatal("unknown ordering in atomic intrinsic"),
},
_ => bx.sess().fatal("Atomic intrinsic not in correct format"),
let Some((instruction, ordering)) = atomic.split_once('_') else {
bx.sess().fatal("Atomic intrinsic missing memory ordering");
};

let parse_ordering = |bx: &Bx, s| match s {
"unordered" => Unordered,
"relaxed" => Relaxed,
"acquire" => Acquire,
"release" => Release,
"acqrel" => AcquireRelease,
"seqcst" => SequentiallyConsistent,
_ => bx.sess().fatal("unknown ordering in atomic intrinsic"),
};

let invalid_monomorphization = |ty| {
Expand All @@ -416,11 +407,14 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
);
};

match split[1] {
match instruction {
"cxchg" | "cxchgweak" => {
let Some((success, failure)) = ordering.split_once('_') else {
bx.sess().fatal("Atomic compare-exchange intrinsic missing failure memory ordering");
};
let ty = substs.type_at(0);
if int_type_width_signed(ty, bx.tcx()).is_some() || ty.is_unsafe_ptr() {
let weak = split[1] == "cxchgweak";
let weak = instruction == "cxchgweak";
let mut dst = args[0].immediate();
let mut cmp = args[1].immediate();
let mut src = args[2].immediate();
Expand All @@ -432,7 +426,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
cmp = bx.ptrtoint(cmp, bx.type_isize());
src = bx.ptrtoint(src, bx.type_isize());
}
let pair = bx.atomic_cmpxchg(dst, cmp, src, order, failorder, weak);
let pair = bx.atomic_cmpxchg(dst, cmp, src, parse_ordering(bx, success), parse_ordering(bx, failure), weak);
let val = bx.extract_value(pair, 0);
let success = bx.extract_value(pair, 1);
let val = bx.from_immediate(val);
Expand Down Expand Up @@ -460,11 +454,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let llty = bx.type_isize();
let ptr_llty = bx.type_ptr_to(llty);
source = bx.pointercast(source, ptr_llty);
let result = bx.atomic_load(llty, source, order, size);
let result = bx.atomic_load(llty, source, parse_ordering(bx, ordering), size);
// ... and then cast the result back to a pointer
bx.inttoptr(result, bx.backend_type(layout))
} else {
bx.atomic_load(bx.backend_type(layout), source, order, size)
bx.atomic_load(bx.backend_type(layout), source, parse_ordering(bx, ordering), size)
}
} else {
return invalid_monomorphization(ty);
Expand All @@ -484,20 +478,20 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
ptr = bx.pointercast(ptr, ptr_llty);
val = bx.ptrtoint(val, bx.type_isize());
}
bx.atomic_store(val, ptr, order, size);
bx.atomic_store(val, ptr, parse_ordering(bx, ordering), size);
return;
} else {
return invalid_monomorphization(ty);
}
}

"fence" => {
bx.atomic_fence(order, SynchronizationScope::CrossThread);
bx.atomic_fence(parse_ordering(bx, ordering), SynchronizationScope::CrossThread);
return;
}

"singlethreadfence" => {
bx.atomic_fence(order, SynchronizationScope::SingleThread);
bx.atomic_fence(parse_ordering(bx, ordering), SynchronizationScope::SingleThread);
return;
}

Expand Down Expand Up @@ -531,7 +525,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
ptr = bx.pointercast(ptr, ptr_llty);
val = bx.ptrtoint(val, bx.type_isize());
}
bx.atomic_rmw(atom_op, ptr, val, order)
bx.atomic_rmw(atom_op, ptr, val, parse_ordering(bx, ordering))
} else {
return invalid_monomorphization(ty);
}
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4 changes: 2 additions & 2 deletions compiler/rustc_error_codes/src/error_codes/E0093.md
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Original file line number Diff line number Diff line change
Expand Up @@ -24,12 +24,12 @@ functions are defined in `compiler/rustc_codegen_llvm/src/intrinsic.rs` and in
#![feature(intrinsics)]
extern "rust-intrinsic" {
fn atomic_fence(); // ok!
fn atomic_fence_seqcst(); // ok!
}
fn main() {
unsafe {
atomic_fence();
atomic_fence_seqcst();
}
}
```
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