[experimental, do not merge!] a faster implementation of Polonius

[tage64]

This is an experiment to use a more lazy approach to Polonius by only invoking the
location-sensitive analysis when needed and using NLL otherwise. This means all programs that
currently compile will still use NLL for borrow checking, and the experimental location-sensitive
analysis will only be triggered if NLL encounters an invalid access. The idea is that it should not affect
performance significantly for existing programs that compile with NLL. However, it still alters the
computation of active loans in rustc_borrowck, and I want a perf run to measure the performance
impact. I expect a slight regression but hopefully not so much.

r? lqd

[rustbot]

Some changes occurred in src/tools/compiletest

cc @jieyouxu

[lqd]

We don't plan on landing this as-is (no need for reviews), but want to see the overhead on NLLs.

@bors try @rust-timer queue

[bors]

⌛ Trying commit 95e1a43 with merge 77f7e0d0156c8e753ba3018f883f09a1ba0ff4a6...

[bors]

☀️ Try build successful - checks-actions
Build commit: 77f7e0d (77f7e0d0156c8e753ba3018f883f09a1ba0ff4a6)

[rust-timer]

Finished benchmarking commit (77f7e0d): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

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 may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.9%	[0.2%, 6.2%]	31
Regressions ❌ (secondary)	1.6%	[0.1%, 4.5%]	22
Improvements ✅ (primary)	-0.2%	[-0.6%, -0.1%]	9
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	9
All ❌✅ (primary)	0.7%	[-0.6%, 6.2%]	40

Max RSS (memory usage)

Results (primary 71.0%, secondary 24.4%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	76.5%	[2.1%, 197.6%]	13
Regressions ❌ (secondary)	43.4%	[0.7%, 81.6%]	10
Improvements ✅ (primary)	-1.2%	[-1.2%, -1.2%]	1
Improvements ✅ (secondary)	-2.8%	[-7.2%, -0.5%]	7
All ❌✅ (primary)	71.0%	[-1.2%, 197.6%]	14

Cycles

Results (primary 2.2%, secondary 1.5%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.2%	[0.9%, 4.5%]	8
Regressions ❌ (secondary)	1.5%	[0.5%, 3.6%]	11
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.2%	[0.9%, 4.5%]	8

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 775.275s -> 776.64s (0.18%)
Artifact size: 365.51 MiB -> 365.37 MiB (-0.04%)

[rust-log-analyzer]

The job x86_64-gnu-llvm-19 failed! Check out the build log: (web) (plain)

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

#18 exporting to docker image format
#18 sending tarball 20.3s done
#18 DONE 26.8s
##[endgroup]
Setting extra environment values for docker:  --env ENABLE_GCC_CODEGEN=1 --env GCC_EXEC_PREFIX=/usr/lib/gcc/
[CI_JOB_NAME=x86_64-gnu-llvm-19]
[CI_JOB_NAME=x86_64-gnu-llvm-19]
debug: `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` configured.
---
sccache: Listening on address 127.0.0.1:4226
##[group]Configure the build
configure: processing command line
configure: 
configure: build.configure-args := ['--build=x86_64-unknown-linux-gnu', '--llvm-root=/usr/lib/llvm-19', '--enable-llvm-link-shared', '--set', 'rust.randomize-layout=true', '--set', 'rust.thin-lto-import-instr-limit=10', '--set', 'build.print-step-timings', '--enable-verbose-tests', '--set', 'build.metrics', '--enable-verbose-configure', '--enable-sccache', '--disable-manage-submodules', '--enable-locked-deps', '--enable-cargo-native-static', '--set', 'rust.codegen-units-std=1', '--set', 'dist.compression-profile=balanced', '--dist-compression-formats=xz', '--set', 'rust.lld=false', '--disable-dist-src', '--release-channel=nightly', '--enable-debug-assertions', '--enable-overflow-checks', '--enable-llvm-assertions', '--set', 'rust.verify-llvm-ir', '--set', 'rust.codegen-backends=llvm,cranelift,gcc', '--set', 'llvm.static-libstdcpp', '--set', 'gcc.download-ci-gcc=true', '--enable-new-symbol-mangling']
configure: build.build          := x86_64-unknown-linux-gnu
configure: target.x86_64-unknown-linux-gnu.llvm-config := /usr/lib/llvm-19/bin/llvm-config
configure: llvm.link-shared     := True
configure: rust.randomize-layout := True
configure: rust.thin-lto-import-instr-limit := 10
---
test [crashes] tests/crashes/135122.rs ... ok
test [crashes] tests/crashes/134654.rs ... ok
test [crashes] tests/crashes/135528.rs ... ok
test [crashes] tests/crashes/135617.rs ... ok
2025-05-21T14:32:05.122057Z ERROR compiletest::runtest: fatal error, panic: "crashtest no longer crashes/triggers ICE, hooray! Please give it a meaningful name, add a doc-comment to the start of the test explaining why it exists and move it to tests/ui or wherever you see fit. Adding 'Fixes #<issueNr>' to your PR description ensures that the corresponding ticket is auto-closed upon merge. If you want to see verbose output, set `COMPILETEST_VERBOSE_CRASHES=1`."
test [crashes] tests/crashes/135646.rs ... FAILED
test [crashes] tests/crashes/125323.rs ... ok
test [crashes] tests/crashes/135845.rs ... ok
test [crashes] tests/crashes/135570.rs ... ok
test [crashes] tests/crashes/135718.rs ... ok
---
failures:

---- [crashes] tests/crashes/135646.rs stdout ----

error: crashtest no longer crashes/triggers ICE, hooray! Please give it a meaningful name, add a doc-comment to the start of the test explaining why it exists and move it to tests/ui or wherever you see fit. Adding 'Fixes #<issueNr>' to your PR description ensures that the corresponding ticket is auto-closed upon merge. If you want to see verbose output, set `COMPILETEST_VERBOSE_CRASHES=1`.

thread '[crashes] tests/crashes/135646.rs' panicked at src/tools/compiletest/src/runtest/crashes.rs:17:18:
fatal error
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace