[LiveIns] Improve recomputeLiveIns() #88951
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Some small changes to recomputeLiveIns() to improve performance: - Instead of copying the list of old live-ins, and then clearing them, a new method swaps the list for an empty one. - getLiveIns() now returns a constant reference to the list As result, the list-data is never copied. Depending on the implementation details of the vector container, it can also save calls to allocate and deallocate memory. I see a small improvement on CTMark with these changes.
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arsenm,
kosarev,
momchil-velikov,
nikic,
oskarwirga and
yozhu
arsenm
reviewed
Apr 16, 2024
| /// Convenience function for recomputing live-in's for a MBB. Returns true if | ||
| /// any changes were made. | ||
| static inline bool recomputeLiveIns(MachineBasicBlock &MBB) { | ||
| inline bool recomputeLiveIns(MachineBasicBlock &MBB) { |
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This needs the extern definition somewhere. Maybe just move the body out of line?
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Thanks - the static is there for ages, I forgot to remove it.
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Yes, I mean you need to put it back or ensure this is defined somewhere
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✅ With the latest revision this PR passed the C/C++ code formatter. |
arsenm
reviewed
Apr 16, 2024
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| auto newLiveIns = MBB.getLiveIns(); | ||
| return oldLiveIns != newLiveIns; | ||
| auto NewLiveIns = MBB.getLiveIns(); |
nikic
reviewed
Apr 17, 2024
Co-authored-by: Nikita Popov <[email protected]>
arsenm
approved these changes
Apr 17, 2024
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Some small changes to recomputeLiveIns() to improve performance:
them, a new method swaps the list for an empty one.
As result, the list-data is never copied. Depending on the implementation
details of the vector container, it can also save calls to allocate
and deallocate memory.
I see a small improvement on CTMark with these changes.