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[clang][modules] Avoid storing command-line macro definitions into implicitly built PCM files
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Authored by jansvoboda11 on Aug 16 2023, 5:37 PM.

Details

Summary

With implicit modules, it's impossible to load a PCM file that was built using different command-line macro definitions. This is guaranteed by the fact that they contribute to the context hash. This means that we don't need to store those macros into PCM files for validation purposes. This patch avoids serializing them in those circumstances, since there's no other use for command-line macro definitions (besides "-module-file-info").

For a typical Apple project, this speeds up the dependency scan by 5.6% and shrinks the cache with scanning PCMs by 26%.

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Event Timeline

jansvoboda11 created this revision.Aug 16 2023, 5:37 PM
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jansvoboda11 requested review of this revision.Aug 16 2023, 5:37 PM
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benlangmuir accepted this revision.Aug 17 2023, 9:19 AM
benlangmuir added inline comments.
clang/test/Modules/module_file_info.m
44–45

CHECK-NOT: Predefined macros ?

This revision is now accepted and ready to land.Aug 17 2023, 9:19 AM