Improve canonicalization performance by introducing TypingMode::ErasedNotCoherence

[jdonszelmann]

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r? @lcnr

This introduces TypingMode::ErasedNotCoherence. Most typing modes contain a list of opaque types, which are quite often unused during canonicalization. With this change, any time we try canonicalization, we replace whichever typing mode we're currently in with ErasedNotcoherence, attempt to canonicalize, and if that fails retry in the original typing mode. If erased mode succeeds, this is beneficial because that way the opaque types don't end up in the cache key, allowing more cache reuse.

This seems to have a small (0.5%) slowdown on most programs, but a dramatic (>60%) speedup in specific cases like the rustc-perf wg-grammar benchmark. Some more improvements are expected with "eager normalization", which is work that's under way right now.

[jdonszelmann]

@bors try

[jdonszelmann]

@bors try parent=14196dbfa3eb7c30195251eac092b1b86c8a2d84

[jdonszelmann]

@rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: db1df07 (db1df07682e37be559858ab003b949a2c17b5b3b, parent: 14196dbfa3eb7c30195251eac092b1b86c8a2d84)

[rust-timer]

Finished benchmarking commit (db1df07): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

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

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.8%	[0.2%, 1.8%]	11
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.6%	[-1.0%, -0.2%]	2
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -0.9%, secondary 1.7%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.1%	[1.1%, 1.1%]	1
Regressions ❌ (secondary)	1.7%	[1.0%, 2.6%]	7
Improvements ✅ (primary)	-2.8%	[-2.8%, -2.8%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.9%	[-2.8%, 1.1%]	2

Cycles

Results (primary -2.4%, secondary 28.5%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	28.5%	[28.5%, 28.5%]	1
Improvements ✅ (primary)	-2.4%	[-2.4%, -2.4%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.4%	[-2.4%, -2.4%]	1

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 491.114s -> 492.029s (0.19%)
Artifact size: 394.23 MiB -> 394.80 MiB (0.14%)

[rustbot]

changes to the core type system

cc @lcnr

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[rust-log-analyzer]

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

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

---- [run-make] tests/run-make-cargo/rustc-crates-on-stable stdout ----

error: rmake recipe failed to complete
status: exit status: 1
command: cd "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-make-cargo/rustc-crates-on-stable/rmake_out" && env -u RUSTFLAGS -u __RUSTC_DEBUG_ASSERTIONS_ENABLED -u __STD_DEBUG_ASSERTIONS_ENABLED -u __STD_REMAP_DEBUGINFO_ENABLED AR="ar" BUILD_ROOT="/checkout/obj/build/x86_64-unknown-linux-gnu" CARGO="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools-bin/cargo" CC="cc" CC_DEFAULT_FLAGS="-ffunction-sections -fdata-sections -fPIC -m64" CXX="c++" CXX_DEFAULT_FLAGS="-ffunction-sections -fdata-sections -fPIC -m64" HOST_RUSTC_DYLIB_PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" LD_LIBRARY_PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/bootstrap-tools/x86_64-unknown-linux-gnu/release/deps:/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/lib/rustlib/x86_64-unknown-linux-gnu/lib" LD_LIB_PATH_ENVVAR="LD_LIBRARY_PATH" LLVM_BIN_DIR="/checkout/obj/build/x86_64-unknown-linux-gnu/ci-llvm/bin" LLVM_COMPONENTS="aarch64 aarch64asmparser aarch64codegen aarch64desc aarch64disassembler aarch64info aarch64utils abi aggressiveinstcombine all all-targets amdgpu amdgpuasmparser amdgpucodegen amdgpudesc amdgpudisassembler amdgpuinfo amdgputargetmca amdgpuutils analysis arm armasmparser armcodegen armdesc armdisassembler arminfo armutils asmparser asmprinter avr avrasmparser avrcodegen avrdesc avrdisassembler avrinfo binaryformat bitreader bitstreamreader bitwriter bpf bpfasmparser bpfcodegen bpfdesc bpfdisassembler bpfinfo cas cfguard cgdata codegen codegentypes core coroutines coverage csky cskyasmparser cskycodegen cskydesc cskydisassembler cskyinfo debuginfobtf debuginfocodeview debuginfodwarf debuginfodwarflowlevel debuginfogsym debuginfologicalview debuginfomsf debuginfopdb demangle dlltooldriver dtlto dwarfcfichecker dwarflinker dwarflinkerclassic dwarflinkerparallel dwp engine executionengine extensions filecheck frontendatomic frontenddirective frontenddriver frontendhlsl frontendoffloading frontendopenacc frontendopenmp fuzzercli fuzzmutate globalisel hexagon hexagonasmparser hexagoncodegen hexagondesc hexagondisassembler hexagoninfo hipstdpar instcombine instrumentation interfacestub interpreter ipo irprinter irreader jitlink libdriver lineeditor linker loongarch loongarchasmparser loongarchcodegen loongarchdesc loongarchdisassembler loongarchinfo lto m68k m68kasmparser m68kcodegen m68kdesc m68kdisassembler m68kinfo mc mca mcdisassembler mcjit mcparser mips mipsasmparser mipscodegen mipsdesc mipsdisassembler mipsinfo mirparser msp430 msp430asmparser msp430codegen msp430desc msp430disassembler msp430info native nativecodegen nvptx nvptxcodegen nvptxdesc nvptxinfo objcarcopts objcopy object objectyaml option orcdebugging orcjit orcshared orctargetprocess passes plugins powerpc powerpcasmparser powerpccodegen powerpcdesc powerpcdisassembler powerpcinfo profiledata remarks riscv riscvasmparser riscvcodegen riscvdesc riscvdisassembler riscvinfo riscvtargetmca runtimedyld sandboxir scalaropts selectiondag sparc sparcasmparser sparccodegen sparcdesc sparcdisassembler sparcinfo support supportlsp symbolize systemz systemzasmparser systemzcodegen systemzdesc systemzdisassembler systemzinfo tablegen target targetparser telemetry textapi textapibinaryreader transformutils vectorize webassembly webassemblyasmparser webassemblycodegen webassemblydesc webassemblydisassembler webassemblyinfo webassemblyutils windowsdriver windowsmanifest x86 x86asmparser x86codegen x86desc x86disassembler x86info x86targetmca xray xtensa xtensaasmparser xtensacodegen xtensadesc xtensadisassembler xtensainfo" LLVM_FILECHECK="/checkout/obj/build/x86_64-unknown-linux-gnu/ci-llvm/bin/FileCheck" PYTHON="/usr/bin/python3" RUSTC="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" RUSTDOC="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustdoc" SOURCE_ROOT="/checkout" TARGET="x86_64-unknown-linux-gnu" TARGET_EXE_DYLIB_PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" __BOOTSTRAP_JOBS="4" __RMAKE_VERBOSE_SUBPROCESS_OUTPUT="1" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-make-cargo/rustc-crates-on-stable/rmake"
stdout: none
--- stderr -------------------------------
command failed at line 41
LD_LIBRARY_PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-make-cargo/rustc-crates-on-stable/rmake_out:/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib:/checkout/obj/build/x86_64-unknown-linux-gnu/bootstrap-tools/x86_64-unknown-linux-gnu/release/deps:/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/lib/rustlib/x86_64-unknown-linux-gnu/lib" RUSTC="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" RUSTC_STAGE="0" RUSTFLAGS="-Zallow-features=" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools-bin/cargo" "build" "--manifest-path" "/checkout/Cargo.toml" "--no-default-features" "--target-dir" "target" "-p" "rustc_type_ir" "-p" "rustc_next_trait_solver" "-p" "rustc_pattern_analysis" "-p" "rustc_lexer" "-p" "rustc_abi" "-p" "rustc_parse_format" "-p" "rustc_hashes"
output status: `exit status: 101`
=== STDOUT ===



=== STDERR ===
   Compiling unicode-ident v1.0.22
---
   Compiling rustc_type_ir v0.0.0 (/checkout/compiler/rustc_type_ir)
error: cannot find derive macro `GenericTypeVisitable` in this scope
##[error]   --> compiler/rustc_type_ir/src/solve/mod.rs:334:33
    |
334 | #[derive(TypeVisitable_Generic, GenericTypeVisitable, TypeFoldable_Generic, Lift_Generic)]
    |                                 ^^^^^^^^^^^^^^^^^^^^
    |
help: consider importing one of these derive macros
    |
  3 + use crate::GenericTypeVisitable;

For more information how to resolve CI failures of this job, visit this link.

[jdonszelmann]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

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

[rust-bors]

⌛ Trying commit dd5b434 with merge 0a137a1…

To cancel the try build, run the command @bors try cancel.

Workflow: https://github.com/rust-lang/rust/actions/runs/25226911955

[jdonszelmann]

@rust-timer cancel

[rust-timer]

Command cannot be empty

[jdonszelmann]

@bors try cancel

[rust-bors]

Try build cancelled. Cancelled workflows:

• https://github.com/rust-lang/rust/actions/runs/25226911955

[rust-bors]

☔ The latest upstream changes (presumably #156072) made this pull request unmergeable. Please resolve the merge conflicts.