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Don't query stability data when staged_api is off #76656

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Merged
merged 1 commit into from
Sep 14, 2020
Merged

Don't query stability data when staged_api is off #76656

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1 change: 1 addition & 0 deletions Cargo.lock
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Original file line number Diff line number Diff line change
Expand Up @@ -3703,6 +3703,7 @@ dependencies = [
"rustc_data_structures",
"rustc_errors",
"rustc_expand",
"rustc_feature",
"rustc_hir",
"rustc_hir_pretty",
"rustc_index",
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_metadata/Cargo.toml
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Expand Up @@ -17,6 +17,7 @@ rustc_middle = { path = "../rustc_middle" }
rustc_attr = { path = "../rustc_attr" }
rustc_data_structures = { path = "../rustc_data_structures" }
rustc_errors = { path = "../rustc_errors" }
rustc_feature = { path = "../rustc_feature" }
rustc_hir = { path = "../rustc_hir" }
rustc_hir_pretty = { path = "../rustc_hir_pretty" }
rustc_target = { path = "../rustc_target" }
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20 changes: 16 additions & 4 deletions compiler/rustc_metadata/src/rmeta/encoder.rs
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Expand Up @@ -40,6 +40,7 @@ use tracing::{debug, trace};
pub(super) struct EncodeContext<'a, 'tcx> {
opaque: opaque::Encoder,
tcx: TyCtxt<'tcx>,
feat: &'tcx rustc_feature::Features,

tables: TableBuilders<'tcx>,

Expand Down Expand Up @@ -1132,15 +1133,25 @@ impl EncodeContext<'a, 'tcx> {

fn encode_stability(&mut self, def_id: DefId) {
debug!("EncodeContext::encode_stability({:?})", def_id);
if let Some(stab) = self.tcx.lookup_stability(def_id) {
record!(self.tables.stability[def_id] <- stab)

// The query lookup can take a measurable amount of time in crates with many items. Check if
// the stability attributes are even enabled before using their queries.
if self.feat.staged_api || self.tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
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I wonder if we should optimize force_unstable_if_unmarked - we know the result of the query ahead of time if staged API is false, right?

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Is that flag used anywhere outside building libstd?

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No (well, rustc too), but speeding up compiler development if possible seems good.

if let Some(stab) = self.tcx.lookup_stability(def_id) {
record!(self.tables.stability[def_id] <- stab)
}
}
}

fn encode_const_stability(&mut self, def_id: DefId) {
debug!("EncodeContext::encode_const_stability({:?})", def_id);
if let Some(stab) = self.tcx.lookup_const_stability(def_id) {
record!(self.tables.const_stability[def_id] <- stab)

// The query lookup can take a measurable amount of time in crates with many items. Check if
// the stability attributes are even enabled before using their queries.
if self.feat.staged_api || self.tcx.sess.opts.debugging_opts.force_unstable_if_unmarked {
if let Some(stab) = self.tcx.lookup_const_stability(def_id) {
record!(self.tables.const_stability[def_id] <- stab)
}
}
}

Expand Down Expand Up @@ -1979,6 +1990,7 @@ fn encode_metadata_impl(tcx: TyCtxt<'_>) -> EncodedMetadata {
let mut ecx = EncodeContext {
opaque: encoder,
tcx,
feat: tcx.features(),
tables: Default::default(),
lazy_state: LazyState::NoNode,
type_shorthands: Default::default(),
Expand Down