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Remove {Pre,Post}InliningPartitioning.

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I find that these structs obfuscate the code. Removing them and just
passing the individual fields around makes the `Partition` method
signatures a little longer, but makes the data flow much clearer. E.g.

- `codegen_units` is mutable all the way through.
- `codegen_units`'s length is changed by `merge_codegen_units`, but only
  the individual elements are changed by `place_inlined_mono_items` and
  `internalize_symbols`.
- `roots`, `internalization_candidates`, and `mono_item_placements` are
  all immutable after creation, and all used by just one of the four
  methods.
This commit is contained in:
Nicholas Nethercote 2023-05-24 10:49:48 +10:00
parent b39b7098ea
commit 20de2ba759
2 changed files with 64 additions and 87 deletions
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55
compiler/rustc_monomorphize/src/partitioning/default.rs
View File

@ -15,9 +15,7 @@ use rustc_span::symbol::Symbol;
use super::PartitioningCx;
use crate::collector::InliningMap;
use crate::partitioning::{
MonoItemPlacement, Partition, PostInliningPartitioning, PreInliningPartitioning,
};
use crate::partitioning::{MonoItemPlacement, Partition};
pub struct DefaultPartitioning;
@ -26,7 +24,7 @@ impl<'tcx> Partition<'tcx> for DefaultPartitioning {
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
mono_items: &mut I,
) -> PreInliningPartitioning<'tcx>
) -> (Vec<CodegenUnit<'tcx>>, FxHashSet<MonoItem<'tcx>>, FxHashSet<MonoItem<'tcx>>)
where
I: Iterator<Item = MonoItem<'tcx>>,
{
@ -91,20 +89,15 @@ impl<'tcx> Partition<'tcx> for DefaultPartitioning {
codegen_units.insert(codegen_unit_name, CodegenUnit::new(codegen_unit_name));
}
PreInliningPartitioning {
codegen_units: codegen_units.into_values().collect(),
roots,
internalization_candidates,
}
(codegen_units.into_values().collect(), roots, internalization_candidates)
}
fn merge_codegen_units(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
initial_partitioning: &mut PreInliningPartitioning<'tcx>,
codegen_units: &mut Vec<CodegenUnit<'tcx>>,
) {
assert!(cx.target_cgu_count >= 1);
let codegen_units = &mut initial_partitioning.codegen_units;
// Note that at this point in time the `codegen_units` here may not be
// in a deterministic order (but we know they're deterministically the
@ -201,20 +194,14 @@ impl<'tcx> Partition<'tcx> for DefaultPartitioning {
fn place_inlined_mono_items(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
initial_partitioning: PreInliningPartitioning<'tcx>,
) -> PostInliningPartitioning<'tcx> {
let mut new_partitioning = Vec::new();
codegen_units: &mut [CodegenUnit<'tcx>],
roots: FxHashSet<MonoItem<'tcx>>,
) -> FxHashMap<MonoItem<'tcx>, MonoItemPlacement> {
let mut mono_item_placements = FxHashMap::default();
let PreInliningPartitioning {
codegen_units: initial_cgus,
roots,
internalization_candidates,
} = initial_partitioning;
let single_codegen_unit = codegen_units.len() == 1;
let single_codegen_unit = initial_cgus.len() == 1;
for old_codegen_unit in initial_cgus {
for old_codegen_unit in codegen_units.iter_mut() {
// 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() {
@ -266,14 +253,10 @@ impl<'tcx> Partition<'tcx> for DefaultPartitioning {
}
}
new_partitioning.push(new_codegen_unit);
*old_codegen_unit = new_codegen_unit;
}
return PostInliningPartitioning {
codegen_units: new_partitioning,
mono_item_placements,
internalization_candidates,
};
return mono_item_placements;
fn follow_inlining<'tcx>(
mono_item: MonoItem<'tcx>,
@ -293,14 +276,16 @@ impl<'tcx> Partition<'tcx> for DefaultPartitioning {
fn internalize_symbols(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
partitioning: &mut PostInliningPartitioning<'tcx>,
codegen_units: &mut [CodegenUnit<'tcx>],
mono_item_placements: FxHashMap<MonoItem<'tcx>, MonoItemPlacement>,
internalization_candidates: FxHashSet<MonoItem<'tcx>>,
) {
if partitioning.codegen_units.len() == 1 {
if codegen_units.len() == 1 {
// Fast path for when there is only one codegen unit. In this case we
// can internalize all candidates, since there is nowhere else they
// could be accessed from.
for cgu in &mut partitioning.codegen_units {
for candidate in &partitioning.internalization_candidates {
for cgu in codegen_units {
for candidate in &internalization_candidates {
cgu.items_mut().insert(*candidate, (Linkage::Internal, Visibility::Default));
}
}
@ -317,15 +302,13 @@ impl<'tcx> Partition<'tcx> for DefaultPartitioning {
}
});
let mono_item_placements = &partitioning.mono_item_placements;
// For each internalization candidates in each codegen unit, check if it is
// accessed from outside its defining codegen unit.
for cgu in &mut partitioning.codegen_units {
for cgu in codegen_units {
let home_cgu = MonoItemPlacement::SingleCgu { cgu_name: cgu.name() };
for (accessee, linkage_and_visibility) in cgu.items_mut() {
if !partitioning.internalization_candidates.contains(accessee) {
if !internalization_candidates.contains(accessee) {
// This item is no candidate for internalizing, so skip it.
continue;
}

96
compiler/rustc_monomorphize/src/partitioning/mod.rs
View File

@ -128,7 +128,7 @@ impl<'tcx> Partition<'tcx> for Partitioner {
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
mono_items: &mut I,
) -> PreInliningPartitioning<'tcx>
) -> (Vec<CodegenUnit<'tcx>>, FxHashSet<MonoItem<'tcx>>, FxHashSet<MonoItem<'tcx>>)
where
I: Iterator<Item = MonoItem<'tcx>>,
{
@ -141,12 +141,10 @@ impl<'tcx> Partition<'tcx> for Partitioner {
fn merge_codegen_units(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
initial_partitioning: &mut PreInliningPartitioning<'tcx>,
codegen_units: &mut Vec<CodegenUnit<'tcx>>,
) {
match self {
Partitioner::Default(partitioner) => {
partitioner.merge_codegen_units(cx, initial_partitioning)
}
Partitioner::Default(partitioner) => partitioner.merge_codegen_units(cx, codegen_units),
Partitioner::Unknown => cx.tcx.sess.emit_fatal(UnknownPartitionStrategy),
}
}
@ -154,11 +152,12 @@ impl<'tcx> Partition<'tcx> for Partitioner {
fn place_inlined_mono_items(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
initial_partitioning: PreInliningPartitioning<'tcx>,
) -> PostInliningPartitioning<'tcx> {
codegen_units: &mut [CodegenUnit<'tcx>],
roots: FxHashSet<MonoItem<'tcx>>,
) -> FxHashMap<MonoItem<'tcx>, MonoItemPlacement> {
match self {
Partitioner::Default(partitioner) => {
partitioner.place_inlined_mono_items(cx, initial_partitioning)
partitioner.place_inlined_mono_items(cx, codegen_units, roots)
}
Partitioner::Unknown => cx.tcx.sess.emit_fatal(UnknownPartitionStrategy),
}
@ -167,12 +166,17 @@ impl<'tcx> Partition<'tcx> for Partitioner {
fn internalize_symbols(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
post_inlining_partitioning: &mut PostInliningPartitioning<'tcx>,
codegen_units: &mut [CodegenUnit<'tcx>],
mono_item_placements: FxHashMap<MonoItem<'tcx>, MonoItemPlacement>,
internalization_candidates: FxHashSet<MonoItem<'tcx>>,
) {
match self {
Partitioner::Default(partitioner) => {
partitioner.internalize_symbols(cx, post_inlining_partitioning)
}
Partitioner::Default(partitioner) => partitioner.internalize_symbols(
cx,
codegen_units,
mono_item_placements,
internalization_candidates,
),
Partitioner::Unknown => cx.tcx.sess.emit_fatal(UnknownPartitionStrategy),
}
}
@ -189,26 +193,29 @@ trait Partition<'tcx> {
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
mono_items: &mut I,
) -> PreInliningPartitioning<'tcx>
) -> (Vec<CodegenUnit<'tcx>>, FxHashSet<MonoItem<'tcx>>, FxHashSet<MonoItem<'tcx>>)
where
I: Iterator<Item = MonoItem<'tcx>>;
fn merge_codegen_units(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
initial_partitioning: &mut PreInliningPartitioning<'tcx>,
codegen_units: &mut Vec<CodegenUnit<'tcx>>,
);
fn place_inlined_mono_items(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
initial_partitioning: PreInliningPartitioning<'tcx>,
) -> PostInliningPartitioning<'tcx>;
codegen_units: &mut [CodegenUnit<'tcx>],
roots: FxHashSet<MonoItem<'tcx>>,
) -> FxHashMap<MonoItem<'tcx>, MonoItemPlacement>;
fn internalize_symbols(
&mut self,
cx: &PartitioningCx<'_, 'tcx>,
partitioning: &mut PostInliningPartitioning<'tcx>,
codegen_units: &mut [CodegenUnit<'tcx>],
mono_item_placements: FxHashMap<MonoItem<'tcx>, MonoItemPlacement>,
internalization_candidates: FxHashSet<MonoItem<'tcx>>,
);
}
@ -240,44 +247,49 @@ where
// In the first step, we place all regular monomorphizations into their
// respective 'home' codegen unit. Regular monomorphizations are all
// functions and statics defined in the local crate.
let mut initial_partitioning = {
let (mut codegen_units, roots, internalization_candidates) = {
let _prof_timer = tcx.prof.generic_activity("cgu_partitioning_place_roots");
partitioner.place_root_mono_items(cx, mono_items)
};
for cgu in &mut initial_partitioning.codegen_units {
for cgu in &mut codegen_units {
cgu.create_size_estimate(tcx);
}
debug_dump(tcx, "INITIAL PARTITIONING", &initial_partitioning.codegen_units);
debug_dump(tcx, "INITIAL PARTITIONING", &codegen_units);
// Merge until we have at most `max_cgu_count` codegen units.
{
let _prof_timer = tcx.prof.generic_activity("cgu_partitioning_merge_cgus");
partitioner.merge_codegen_units(cx, &mut initial_partitioning);
debug_dump(tcx, "POST MERGING", &initial_partitioning.codegen_units);
partitioner.merge_codegen_units(cx, &mut codegen_units);
debug_dump(tcx, "POST MERGING", &codegen_units);
}
// In the next step, we use the inlining map to determine which additional
// monomorphizations have to go into each codegen unit. These additional
// monomorphizations can be drop-glue, functions from external crates, and
// local functions the definition of which is marked with `#[inline]`.
let mut post_inlining = {
let mono_item_placements = {
let _prof_timer = tcx.prof.generic_activity("cgu_partitioning_place_inline_items");
partitioner.place_inlined_mono_items(cx, initial_partitioning)
partitioner.place_inlined_mono_items(cx, &mut codegen_units, roots)
};
for cgu in &mut post_inlining.codegen_units {
for cgu in &mut codegen_units {
cgu.create_size_estimate(tcx);
}
debug_dump(tcx, "POST INLINING", &post_inlining.codegen_units);
debug_dump(tcx, "POST INLINING", &codegen_units);
// Next we try to make as many symbols "internal" as possible, so LLVM has
// more freedom to optimize.
if !tcx.sess.link_dead_code() {
let _prof_timer = tcx.prof.generic_activity("cgu_partitioning_internalize_symbols");
partitioner.internalize_symbols(cx, &mut post_inlining);
partitioner.internalize_symbols(
cx,
&mut codegen_units,
mono_item_placements,
internalization_candidates,
);
}
let instrument_dead_code =
@ -285,7 +297,7 @@ where
if instrument_dead_code {
assert!(
post_inlining.codegen_units.len() > 0,
codegen_units.len() > 0,
"There must be at least one CGU that code coverage data can be generated in."
);
@ -296,7 +308,7 @@ where
// the object file (CGU) containing the dead function stubs is included
// in the final binary. This will probably require forcing these
// function symbols to be included via `-u` or `/include` linker args.
let mut cgus: Vec<_> = post_inlining.codegen_units.iter_mut().collect();
let mut cgus: Vec<_> = codegen_units.iter_mut().collect();
cgus.sort_by_key(|cgu| cgu.size_estimate());
let dead_code_cgu =
@ -307,29 +319,17 @@ where
} else {
// If there are no CGUs that have externally linked items,
// then we just pick the first CGU as a fallback.
&mut post_inlining.codegen_units[0]
&mut codegen_units[0]
};
dead_code_cgu.make_code_coverage_dead_code_cgu();
}
// Finally, sort by codegen unit name, so that we get deterministic results.
let PostInliningPartitioning {
codegen_units: mut result,
mono_item_placements: _,
internalization_candidates: _,
} = post_inlining;
codegen_units.sort_by(|a, b| a.name().as_str().cmp(b.name().as_str()));
result.sort_by(|a, b| a.name().as_str().cmp(b.name().as_str()));
debug_dump(tcx, "FINAL", &codegen_units);
debug_dump(tcx, "FINAL", &result);
result
}
pub struct PreInliningPartitioning<'tcx> {
codegen_units: Vec<CodegenUnit<'tcx>>,
roots: FxHashSet<MonoItem<'tcx>>,
internalization_candidates: FxHashSet<MonoItem<'tcx>>,
codegen_units
}
/// For symbol internalization, we need to know whether a symbol/mono-item is
@ -341,12 +341,6 @@ enum MonoItemPlacement {
MultipleCgus,
}
struct PostInliningPartitioning<'tcx> {
codegen_units: Vec<CodegenUnit<'tcx>>,
mono_item_placements: FxHashMap<MonoItem<'tcx>, MonoItemPlacement>,
internalization_candidates: FxHashSet<MonoItem<'tcx>>,
}
fn debug_dump<'a, 'tcx: 'a>(tcx: TyCtxt<'tcx>, label: &str, cgus: &[CodegenUnit<'tcx>]) {
let dump = move || {
use std::fmt::Write;