Don't use Lock for heavily accessed CrateMetadata::cnum_map. #50532
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… r=Zoxc Don't use Lock for heavily accessed CrateMetadata::cnum_map. The `cnum_map` in `CrateMetadata` is used for two things: 1. to map `CrateNums` between crates (used a lot during decoding) 2. to construct the (reverse) post order of the crate graph For the second case, we need to modify the map after the fact, which is why the map is wrapped in a `Lock`. This is bad for the first case, which does not need the modification and does lots of small reads from the map. This PR splits case (2) out into a separate `dependencies` field. This allows to make the `cnum_map` immutable (and shifts the interior mutability to a less busy data structure). Fixes rust-lang#50502 r? @Zoxc
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… r=Zoxc Don't use Lock for heavily accessed CrateMetadata::cnum_map. The `cnum_map` in `CrateMetadata` is used for two things: 1. to map `CrateNums` between crates (used a lot during decoding) 2. to construct the (reverse) post order of the crate graph For the second case, we need to modify the map after the fact, which is why the map is wrapped in a `Lock`. This is bad for the first case, which does not need the modification and does lots of small reads from the map. This PR splits case (2) out into a separate `dependencies` field. This allows to make the `cnum_map` immutable (and shifts the interior mutability to a less busy data structure). Fixes rust-lang#50502 r? @Zoxc
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Rollup of 18 pull requests Successful merges: - #49423 (Extend tests for RFC1598 (GAT)) - #50010 (Give SliceIndex impls a test suite of girth befitting the implementation (and fix a UTF8 boundary check)) - #50447 (Fix update-references for tests within subdirectories.) - #50514 (Pull in a wasm fix from LLVM upstream) - #50524 (Make DepGraph::previous_work_products immutable) - #50532 (Don't use Lock for heavily accessed CrateMetadata::cnum_map.) - #50538 ( Make CrateNum allocation more thread-safe. ) - #50564 (Inline `Span` methods.) - #50565 (Use SmallVec for DepNodeIndex within dep_graph.) - #50569 (Allow for specifying a linker plugin for cross-language LTO) - #50572 (Clarify in the docs that `mul_add` is not always faster.) - #50574 (add fn `into_inner(self) -> (Idx, Idx)` to RangeInclusive (#49022)) - #50575 (std: Avoid `ptr::copy` if unnecessary in `vec::Drain`) - #50588 (Move "See also" disambiguation links for primitive types to top) - #50590 (Fix tuple struct field spans) - #50591 (Restore RawVec::reserve* documentation) - #50598 (Remove unnecessary mutable borrow and resizing in DepGraph::serialize) - #50606 (Retry when downloading the Docker cache.) Failed merges: - #50161 (added missing implementation hint) - #50558 (Remove all reference to DepGraph::work_products)
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The
cnum_mapinCrateMetadatais used for two things:CrateNumsbetween crates (used a lot during decoding)For the second case, we need to modify the map after the fact, which is why the map is wrapped in a
Lock. This is bad for the first case, which does not need the modification and does lots of small reads from the map.This PR splits case (2) out into a separate
dependenciesfield. This allows to make thecnum_mapimmutable (and shifts the interior mutability to a less busy data structure).Fixes #50502
r? @Zoxc