Shrink struct RExC_state_t #23441
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Shrink struct RExC_state_t #23441
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khwilliamson
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Jul 15, 2025
ilmari
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Leont
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Jul 16, 2025
Combined with the previous previous commits on this branch this shrinks the size of the struct on a 64-bit Linux non-debugging build from: /* size: 368, cachelines: 6, members: 63 */ /* sum members: 363, holes: 1, sum holes: 4 */ /* padding: 1 */ /* last cacheline: 48 bytes */ to: /* size: 344, cachelines: 6, members: 63 */ /* padding: 5 */ /* last cacheline: 24 bytes */ And on a debugging build from: /* size: 408, cachelines: 7, members: 69 */ /* sum members: 403, holes: 2, sum holes: 5 */ /* last cacheline: 24 bytes */ to: /* size: 384, cachelines: 6, members: 69 */ /* sum members: 379, holes: 1, sum holes: 1 */ /* padding: 4 */
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There are lots of
I32fields in theRExC_state_tstruct that are only everused as booleans. This series of commits converts them to actual booleans,
and then reorders the fields in the struct to elminate alignment holes.
This PR shrinks the size of the struct on a 64-bit Linux non-debugging build
from:
to:
And on a debugging build from:
to: