From: Jeff King Date: Fri, 17 Jan 2014 01:22:56 +0000 (-0500) Subject: diff_filespec: reorder is_binary field X-Git-Tag: v1.9-rc1~14^2~1 X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/b38f70a82b9628d80f5a9bc938a8861ee4dcf49e?hp=b38f70a82b9628d80f5a9bc938a8861ee4dcf49e diff_filespec: reorder is_binary field The middle of the diff_filespec struct contains a mixture of ints, shorts, and bit-fields, followed by a pointer. On an x86-64 system with an LP64 or LLP64 data model (i.e., most of them), the integers and flags end up being padded out by 41 bits to put the pointer at an 8-byte boundary. After the pointer, we have the "int is_binary" field, which is only 32 bits. We end up wasting another 32 bits to pad the struct size up to a multiple of 64 bits. We can move the is_binary field before the pointer, which lets the compiler store it where we used to have padding. This shrinks the top padding to only 9 bits (from the bit-fields), and eliminates the bottom padding entirely, dropping the struct size from 88 to 80 bytes. On a 32-bit system, there is no benefit, but nor should there be any harm (we only need 4-byte alignment there, so we were already using only 9 bits of padding). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano ---