Problem

__wt_page_modify wastes 7 bytes per modified page due to a bool alignment hole:

bool instantiated;        /* 1 byte at offset ~224 */
/* 7 bytes compiler padding */
WT_UPDATE **inst_updates; /* pointer, requires 8-byte alignment */

The trailing small fields (rec_result, restore_state, flags) are already packed together at the end of the struct (btmem.h ~533-543), but instantiated is declared separately just above page_lock / inst_updates, forcing 7 bytes of wasted padding before the next pointer.

Fix

Move instantiated to sit alongside rec_result, restore_state, and flags at the end of the struct. All four are uint8_t-sized (bool is 1 byte on this platform) and are used together during page reconciliation and instantiation, so grouping them is also a locality improvement. The change saves 7 bytes per WT_PAGE_MODIFY allocation with no semantic effect.

References

• src/include/btmem.h, struct __wt_page_modify, lines ~506-507 (instantiated declaration) and ~533-543 (trailing flag fields)