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Don't compute inlining status of mono items in advance. #112128

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Jun 1, 2023
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Don't compute inlining status of mono items in advance. #112128

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76 changes: 13 additions & 63 deletions compiler/rustc_monomorphize/src/collector.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -179,7 +179,6 @@ use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId};
use rustc_hir::lang_items::LangItem;
use rustc_index::bit_set::GrowableBitSet;
use rustc_middle::mir::interpret::{AllocId, ConstValue};
use rustc_middle::mir::interpret::{ErrorHandled, GlobalAlloc, Scalar};
use rustc_middle::mir::mono::{InstantiationMode, MonoItem};
Expand Down Expand Up @@ -220,78 +219,29 @@ pub struct InliningMap<'tcx> {
// The range selects elements within the `targets` vecs.
index: FxHashMap<MonoItem<'tcx>, Range<usize>>,
targets: Vec<MonoItem<'tcx>>,

// Contains one bit per mono item in the `targets` field. That bit
// is true if that mono item needs to be inlined into every CGU.
inlines: GrowableBitSet<usize>,
}

/// Struct to store mono items in each collecting and if they should
/// be inlined. We call `instantiation_mode` to get their inlining
/// status when inserting new elements, which avoids calling it in
/// `inlining_map.lock_mut()`. See the `collect_items_rec` implementation
/// below.
struct MonoItems<'tcx> {
// If this is false, we do not need to compute whether items
// will need to be inlined.
compute_inlining: bool,

// The TyCtxt used to determine whether the a item should
// be inlined.
tcx: TyCtxt<'tcx>,

// The collected mono items. The bool field in each element
// indicates whether this element should be inlined.
items: Vec<(Spanned<MonoItem<'tcx>>, bool /*inlined*/)>,
}

impl<'tcx> MonoItems<'tcx> {
#[inline]
fn push(&mut self, item: Spanned<MonoItem<'tcx>>) {
self.extend([item]);
}

#[inline]
fn extend<T: IntoIterator<Item = Spanned<MonoItem<'tcx>>>>(&mut self, iter: T) {
self.items.extend(iter.into_iter().map(|mono_item| {
let inlined = if !self.compute_inlining {
false
} else {
mono_item.node.instantiation_mode(self.tcx) == InstantiationMode::LocalCopy
};
(mono_item, inlined)
}))
}
}
type MonoItems<'tcx> = Vec<Spanned<MonoItem<'tcx>>>;

impl<'tcx> InliningMap<'tcx> {
fn new() -> InliningMap<'tcx> {
InliningMap {
index: FxHashMap::default(),
targets: Vec::new(),
inlines: GrowableBitSet::with_capacity(1024),
}
InliningMap { index: FxHashMap::default(), targets: Vec::new() }
}

fn record_accesses<'a>(
&mut self,
source: MonoItem<'tcx>,
new_targets: &'a [(Spanned<MonoItem<'tcx>>, bool)],
new_targets: &'a [Spanned<MonoItem<'tcx>>],
) where
'tcx: 'a,
{
let start_index = self.targets.len();
let new_items_count = new_targets.len();
let new_items_count_total = new_items_count + self.targets.len();

self.targets.reserve(new_items_count);
self.inlines.ensure(new_items_count_total);

for (i, (Spanned { node: mono_item, .. }, inlined)) in new_targets.into_iter().enumerate() {
for Spanned { node: mono_item, .. } in new_targets.into_iter() {
self.targets.push(*mono_item);
if *inlined {
self.inlines.insert(i + start_index);
}
}

let end_index = self.targets.len();
Expand All @@ -300,13 +250,14 @@ impl<'tcx> InliningMap<'tcx> {

/// Internally iterate over all items referenced by `source` which will be
/// made available for inlining.
pub fn with_inlining_candidates<F>(&self, source: MonoItem<'tcx>, mut f: F)
pub fn with_inlining_candidates<F>(&self, tcx: TyCtxt<'tcx>, source: MonoItem<'tcx>, mut f: F)
where
F: FnMut(MonoItem<'tcx>),
{
if let Some(range) = self.index.get(&source) {
for (i, candidate) in self.targets[range.clone()].iter().enumerate() {
if self.inlines.contains(range.start + i) {
for candidate in self.targets[range.clone()].iter() {
let is_inlined = candidate.instantiation_mode(tcx) == InstantiationMode::LocalCopy;
if is_inlined {
f(*candidate);
}
}
Expand Down Expand Up @@ -367,7 +318,7 @@ pub fn collect_crate_mono_items(
#[instrument(skip(tcx, mode), level = "debug")]
fn collect_roots(tcx: TyCtxt<'_>, mode: MonoItemCollectionMode) -> Vec<MonoItem<'_>> {
debug!("collecting roots");
let mut roots = MonoItems { compute_inlining: false, tcx, items: Vec::new() };
let mut roots = Vec::new();

{
let entry_fn = tcx.entry_fn(());
Expand All @@ -393,9 +344,8 @@ fn collect_roots(tcx: TyCtxt<'_>, mode: MonoItemCollectionMode) -> Vec<MonoItem<
// whose predicates hold. Luckily, items that aren't instantiable
// can't actually be used, so we can just skip codegenning them.
roots
.items
.into_iter()
.filter_map(|(Spanned { node: mono_item, .. }, _)| {
.filter_map(|Spanned { node: mono_item, .. }| {
mono_item.is_instantiable(tcx).then_some(mono_item)
})
.collect()
Expand All @@ -417,7 +367,7 @@ fn collect_items_rec<'tcx>(
return;
}

let mut neighbors = MonoItems { compute_inlining: true, tcx, items: Vec::new() };
let mut neighbors = Vec::new();
let recursion_depth_reset;

//
Expand Down Expand Up @@ -542,9 +492,9 @@ fn collect_items_rec<'tcx>(
formatted_item,
});
}
inlining_map.lock_mut().record_accesses(starting_point.node, &neighbors.items);
inlining_map.lock_mut().record_accesses(starting_point.node, &neighbors);

for (neighbour, _) in neighbors.items {
for neighbour in neighbors {
collect_items_rec(tcx, neighbour, visited, recursion_depths, recursion_limit, inlining_map);
}

Expand Down
7 changes: 4 additions & 3 deletions compiler/rustc_monomorphize/src/partitioning.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -424,7 +424,7 @@ fn place_inlined_mono_items<'tcx>(
// Collect all items that need to be available in this codegen unit.
let mut reachable = FxHashSet::default();
for root in old_codegen_unit.items().keys() {
follow_inlining(*root, cx.inlining_map, &mut reachable);
follow_inlining(cx.tcx, *root, cx.inlining_map, &mut reachable);
}

let mut new_codegen_unit = CodegenUnit::new(old_codegen_unit.name());
Expand Down Expand Up @@ -478,6 +478,7 @@ fn place_inlined_mono_items<'tcx>(
return mono_item_placements;

fn follow_inlining<'tcx>(
tcx: TyCtxt<'tcx>,
mono_item: MonoItem<'tcx>,
inlining_map: &InliningMap<'tcx>,
visited: &mut FxHashSet<MonoItem<'tcx>>,
Expand All @@ -486,8 +487,8 @@ fn place_inlined_mono_items<'tcx>(
return;
}

inlining_map.with_inlining_candidates(mono_item, |target| {
follow_inlining(target, inlining_map, visited);
inlining_map.with_inlining_candidates(tcx, mono_item, |target| {
follow_inlining(tcx, target, inlining_map, visited);
});
}
}
Expand Down