Allocate one vec, instead of one per invocation

[oli-obk]

potential alternative to #92928

r? @ghost

[oli-obk]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit d57fdcf with merge 38a6fb92aa4547ce389f02f56fb7135dd5b17ae9...

[rust-log-analyzer]

The job mingw-check failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

configure: rust.debug-assertions := True
configure: rust.overflow-checks := True
configure: llvm.assertions      := True
configure: dist.missing-tools   := True
configure: build.configure-args := ['--enable-sccache', '--disable-manage-submodu ...
configure: writing `config.toml` in current directory
configure: 
configure: run `python /checkout/x.py --help`
configure: 
---
skip untracked path cpu-usage.csv during rustfmt invocations
skip untracked path src/doc/book/ during rustfmt invocations
skip untracked path src/doc/rust-by-example/ during rustfmt invocations
skip untracked path src/llvm-project/ during rustfmt invocations
Diff in /checkout/compiler/rustc_infer/src/infer/canonical/query_response.rs at line 219:
         original_values: &OriginalQueryValues<'tcx>,
         query_response: &Canonical<'tcx, QueryResponse<'tcx, R>>,
         output_query_region_constraints: &mut QueryRegionConstraints<'tcx>,
-        obligations: &mut PredicateObligations<'tcx>
+        obligations: &mut PredicateObligations<'tcx>,
     ) -> Result<R, TypeError<'tcx>>
     where
         R: Debug + TypeFoldable<'tcx>,
Diff in /checkout/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs at line 1:
 use crate::infer::canonical::{
     Canonicalized, CanonicalizedQueryResponse, OriginalQueryValues, QueryRegionConstraints,
 };
-use crate::infer::{InferCtxt};
+use crate::infer::InferCtxt;
 use crate::traits::query::Fallible;
 use crate::traits::ObligationCause;
 use rustc_infer::infer::canonical::{Canonical, Certainty};
Diff in /checkout/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs at line 82:
         infcx: &InferCtxt<'_, 'tcx>,
         output_query_region_constraints: &mut QueryRegionConstraints<'tcx>,
         obligations: &mut PredicateObligations<'tcx>,
-    ) -> Fallible<(
-        Self::QueryResponse,
-        Option<Canonical<'tcx, ParamEnvAnd<'tcx, Self>>>,
-        Certainty,
-    )> {
+    ) -> Fallible<(Self::QueryResponse, Option<Canonical<'tcx, ParamEnvAnd<'tcx, Self>>>, Certainty)>
+    {
         if let Some(result) = QueryTypeOp::try_fast_path(infcx.tcx, &query_key) {
             return Ok((result, None, Certainty::Proven));
         }
Diff in /checkout/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs at line 101:
             infcx.canonicalize_query_keep_static(query_key, &mut canonical_var_values);
         let canonical_result = Self::perform_query(infcx.tcx, canonical_self)?;
-        let value = infcx
-        let value = infcx
-            .instantiate_nll_query_response_and_region_obligations(
-                &ObligationCause::dummy(),
-                old_param_env,
-                &canonical_var_values,
-                canonical_result,
-                output_query_region_constraints,
-                obligations,
-            )?;
+        let value = infcx.instantiate_nll_query_response_and_region_obligations(
+            &ObligationCause::dummy(),
+            old_param_env,
+            &canonical_var_values,
+            canonical_result,
+            output_query_region_constraints,
+            obligations,
+        )?;
 
         Ok((value, Some(canonical_self), canonical_result.value.certainty))
Build completed unsuccessfully in 0:00:13
Build completed unsuccessfully in 0:00:13
Running `"/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/rustfmt" "--config-path" "/checkout" "--edition" "2018" "--unstable-features" "--skip-children" "--check" "/checkout/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs" "/checkout/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs" "/checkout/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs" "/checkout/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs" "/checkout/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs" "/checkout/compiler/rustc_infer/src/infer/error_reporting/note.rs" "/checkout/compiler/rustc_infer/src/infer/canonical/query_response.rs" "/checkout/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs"` failed.
If you're running `tidy`, try again with `--bless`. Or, if you just want to format code, run `./x.py fmt` instead.

[bors]

☀️ Try build successful - checks-actions
Build commit: 38a6fb92aa4547ce389f02f56fb7135dd5b17ae9 (38a6fb92aa4547ce389f02f56fb7135dd5b17ae9)

[rust-timer]

Queued 38a6fb92aa4547ce389f02f56fb7135dd5b17ae9 with parent a34c079, future comparison URL.

[rust-timer]

Finished benchmarking commit (38a6fb92aa4547ce389f02f56fb7135dd5b17ae9): comparison url.

Summary: This change led to moderate relevant improvements 🎉 in compiler performance.

• Moderate improvement in instruction counts (up to -0.8% on incr-unchanged builds of externs debug)

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR led to changes in compiler perf.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf -perf-regression