coverage: Avoid a query stability hazard in function_coverage_map
#119514
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When rust-lang#118865 started enforcing the `rustc::potential_query_instability` lint in `rustc_codegen_llvm`, it added an exemption for this site, arguing that the entries are only used to create a list of filenames that is later sorted. However, the list of entries also gets traversed when creating the function coverage records in LLVM IR, which may be sensitive to hash-based ordering. This patch therefore changes `function_coverage_map` to use `FxIndexMap`, which should avoid hash-based instability by iterating in insertion order.
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r? @wesleywiser (rustbot has picked a reviewer for you, use r? to override) |
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The detailed comment was very helpful in this case, because I could immediately see that its reasoning was incorrect, which prompted me to do a proper audit of how the list of entries is actually used. |
wesleywiser
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Jan 2, 2024
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🌲 The tree is currently closed for pull requests below priority 100. This pull request will be tested once the tree is reopened. |
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…wiser coverage: Avoid a query stability hazard in `function_coverage_map` When rust-lang#118865 started enforcing the `rustc::potential_query_instability` lint in `rustc_codegen_llvm`, it added an exemption for this site, arguing that the entries are only used to create a list of filenames that is later sorted. However, the list of entries also gets traversed when creating the function coverage records in LLVM IR, which may be sensitive to hash-based ordering. This patch therefore changes `function_coverage_map` to use `FxIndexMap`, which should avoid hash-based instability by iterating in insertion order. cc `@Enselic`
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Rollup of 21 pull requests Successful merges: - rust-lang#119086 (Query panic!() to useful diagnostic) - rust-lang#119239 (Remove unnecessary arm in `check_expr_yield`) - rust-lang#119298 (suppress change-tracker warnings in CI containers) - rust-lang#119319 (Document that File does not buffer reads/writes) - rust-lang#119434 (rc: Take *const T in is_dangling) - rust-lang#119444 (Rename `TyCtxt::is_closure` to `TyCtxt::is_closure_or_coroutine`) - rust-lang#119474 (Update tracking issue of naked_functions) - rust-lang#119476 (Pretty-print always-const trait predicates correctly) - rust-lang#119477 (rustdoc ui: adjust tooltip z-index to be above sidebar) - rust-lang#119479 (Remove two unused feature gates from rustc_query_impl) - rust-lang#119487 (Minor improvements in comment on `freshen.rs`) - rust-lang#119492 (Update books) - rust-lang#119494 (Deny defaults for higher-ranked generic parameters) - rust-lang#119498 (Update deadlinks of `strict_provenance` lints) - rust-lang#119505 (Don't synthesize host effect params for trait associated functions marked const) - rust-lang#119510 (Report I/O errors from rmeta encoding with emit_fatal) - rust-lang#119512 (Mark myself as back from leave) - rust-lang#119514 (coverage: Avoid a query stability hazard in `function_coverage_map`) - rust-lang#119523 (llvm: Allow `noundef` in codegen tests) - rust-lang#119534 (Update `thread_local` examples to use `local_key_cell_methods`) - rust-lang#119544 (Fix: Properly set vendor in i686-win7-windows-msvc target) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#119514 - Zalathar:query-stability, r=wesleywiser coverage: Avoid a query stability hazard in `function_coverage_map` When rust-lang#118865 started enforcing the `rustc::potential_query_instability` lint in `rustc_codegen_llvm`, it added an exemption for this site, arguing that the entries are only used to create a list of filenames that is later sorted. However, the list of entries also gets traversed when creating the function coverage records in LLVM IR, which may be sensitive to hash-based ordering. This patch therefore changes `function_coverage_map` to use `FxIndexMap`, which should avoid hash-based instability by iterating in insertion order. cc ``@Enselic``
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When #118865 started enforcing the
rustc::potential_query_instabilitylint inrustc_codegen_llvm, it added an exemption for this site, arguing that the entries are only used to create a list of filenames that is later sorted.However, the list of entries also gets traversed when creating the function coverage records in LLVM IR, which may be sensitive to hash-based ordering.
This patch therefore changes
function_coverage_mapto useFxIndexMap, which should avoid hash-based instability by iterating in insertion order.cc @Enselic