[clang][deps] Avoid CompilerInvocation copies - #13201
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benlangmuir
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Jun 17, 2026
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By propagating cow upwards, I realized most of my |
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benlangmuir
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Jun 23, 2026
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Mostly LGTM; couple of questions
| llvm::function_ref<bool(std::string &)> Callback) { | ||
| // Ensure exclusive ownership of every option group, so that visitPathsImpl() | ||
| // doesn't affect any other invocations. | ||
| // FIXME: Do this only if \c Callback does decide to modify any strings in an |
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Is this implementable without a CowString?
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Yes, that's my next patch. I'll change the signature of Callback to say whether it wants to change the string and call ensureOwned on the owning options object before performing the modification.
benlangmuir
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This was referenced Jun 24, 2026
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When constructing the dependency graph for compilation caching, the dependency scanner needs to do some extra operations on the compiler invocations. Historically, these have not utilized the copy-on-write variant well. This patch takes care to minimize
CompilerInvocationcopies, which improves incremental scans with populated up-to-date scanning module cache by 16-18%. Together with llvm#203350 which operates in the same space, wall-times are improved by 1.54x and instruction counts by 1.66x.