bors c241e14650 Auto merge of #136593 - lukas-code:ty-value-perf, r=oli-obk ... valtree performance tuning Summary: This PR makes type checking of code with many type-level constants faster. After https://github.com/rust-lang/rust/pull/136180 was merged, we observed a small perf regression (https://github.com/rust-lang/rust/pull/136318#issuecomment-2635562821). This happened because that PR introduced additional copies in the fast reject code path for consts, which is very hot for certain crates: 6c1d960d88/compiler/rustc_type_ir/src/fast_reject.rs (L486-L487) This PR improves the performance again by properly interning the valtrees so that copying and comparing them becomes faster. This will become especially useful with `feature(adt_const_params)`, so the fast reject code doesn't have to do a deep compare of the valtrees. Note that we can't just compare the interned consts themselves in the fast reject, because sometimes `'static` lifetimes in the type are be replaced with inference variables (due to canonicalization) on one side but not the other. A less invasive alternative that I considered is simply avoiding copies introduced by https://github.com/rust-lang/rust/pull/136180 and comparing the valtrees it in-place (see commit: 9e91e50ac5 / perf results: https://github.com/rust-lang/rust/pull/136593#issuecomment-2642303245), however that was still measurably slower than interning. There are some minor regressions in secondary benchmarks: These happen due to changes in memory allocations and seem acceptable to me. The crates that make heavy use of valtrees show no significant changes in memory usage.		2025-02-13 15:27:30 +00:00
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src	Auto merge of #136593 - lukas-code:ty-value-perf, r=oli-obk	2025-02-13 15:27:30 +00:00
.gitignore
Cargo.toml	Add hir::Attribute	2024-12-15 19:18:46 +01:00