CVS commit: src/sys/arch/x86/x86

["Jaromir Dolecek" <jdolecek%netbsd.org@localhost>]

Module Name:    src
Committed By:   jdolecek
Date:           Sat Feb  6 21:24:20 UTC 2021

Modified Files:
        src/sys/arch/x86/x86: pmap.c

Log Message:
use __builtin_assume_aligned() on places where the memset() or memcpy()
parameters are known to be PAGE_SIZE-aligned, so compiler doesn't need
to emit atrocious alignment check code when inlining them

this particularly improves pmap_zero_page() and pmap_copy_page(),
which are now reduced to only 'rep stosq', and close to what a hand-written
assembly would do

Note: on CPUs supporting ERMS, 'rep stosb' would still be slightly faster, but
this is a solid stop-gap improvement

suggested by Mateusz Guzik in:
http://mail-index.netbsd.org/tech-kern/2020/07/19/msg026620.html


To generate a diff of this commit:
cvs rdiff -u -r1.408 -r1.409 src/sys/arch/x86/x86/pmap.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.