https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121970
--- Comment #2 from Hongtao Liu <liuhongt at gcc dot gnu.org> --- According to documents, MOVE_MAX is for memory copy, STORE_BY_PIECE is for store only Macro: MOVE_MAX_PIECES A C expression used by move_by_pieces to determine the largest unit a load or store used to copy memory is. Defaults to MOVE_MAX. Macro: STORE_MAX_PIECES A C expression used by store_by_pieces to determine the largest unit a store used to memory is. Defaults to MOVE_MAX_PIECES, or two times the size of HOST_WIDE_INT, whichever is smaller.
