Messages in this thread | | | Date | Mon, 11 Feb 2013 23:12:49 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [tip:x86/mm] x86, mm: Use a bitfield to mask nuisance get_user() warnings |
| |
Just to be sure, I re-ran the comparison using gcc 4.6.3 instead of gcc 4.7.2. With gcc 4.6.3 I consistently get a few hundred bytes longer with the bitfield variant than with the pre-get_user() baseline.
I looked at some of the diffed disassembly, and the differences seem to be in the code generated downstream of __get_user_1 and __get_user_2, which I guess is to be expected, mostly in the form of padding.
Annoyingly enough in *both* cases I found unnecessary instructions like:
+c12f6fbb: 0f b7 d2 movzwl %dx,%edx
-hpa
| |