This is a tradeoff which saves jumps for smaller sizes while making
the 8-16 range slower (roughly in line with the other cases).
Tested with glibc test suite.
For example size 3 (most common with vfs namecache) (ops/s):
before: 407086026
after: 461391995
The regressed range of 8-16 (with 8 as example):
before: 540850489
after: 461671032
See the review for sample test results.
Reviewed by: kib (kernel part)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18401
Handling sizes of > 32 backwards will be updated later.
Reviewed by: kib (kernel part)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18387
For non-ERMS case the code used handle possible trailing bytes with
movsb first and then followed it up with movsq. This also happened
to alter how calculations were done for other cases.
Handle the tail with regular movs, just like when copying forward.
Use leaq to calculate the right offset from the get go, instead of
doing separate add and sub.
This adjusts the offset for non-rep cases so that they can be used
to handle the tail.
The routine is still a work in progress.
Sponsored by: The FreeBSD Foundation
Instead of jumping to locations which store the exact number of bytes,
use displacement to move the destination.
In particular the following clears an area between 8-16 (inclusive)
branch-free:
movq %r10,(%rdi)
movq %r10,-8(%rdi,%rcx)
For instance for rcx of 10 the second line is rdi + 10 - 8 = rdi + 2.
Writing 8 bytes starting at that offset overlaps with 6 bytes written
previously and writes 2 new, giving 10 in total.
Provides a nice win for smaller stores. Other ones are erratic depending
on the microarchitecture.
General idea taken from NetBSD (restricted use of the trick) and bionic
string functions (use for various ranges like in this patch).
Reviewed by: kib (previous version)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17660
- tidy up memset to have rax set earlier for small sizes
- finish the tail in memset with an overlapping store
- align memset buffers to 16 bytes before using rep stos
Sponsored by: The FreeBSD Foundation
The function is of limited use and is an almost a direct clone of
memmove/memcpy (with arguments swapped). Introduction of ERMS variants
of string routines would mean avoidable growth of libc.
bcopy will get redefined to a __builtin_memmove later on with this
symbol only left for compatibility.
Reviewed by: kib
Approved by: re (gjb)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17539
bcopy is left alone as it is expected to be converted to a C func.
Due to header mess ALIGN_TEXT is temporarily defined explicitly in memmove.S
Reviewed by: kib
Approved by: re (gjb)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17538
See r339205 for details.
An unused ERMS support is retained in the macro. It will be activated
after ifunc support lands.
Reviewed by: kib
Approved by: re (gjb)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17405
This is a depessimization, see r334537 for an explanation. Routines
remain significantly slower than they have to be.
bzero was removed from the kernel but remains in libc. Macroify to
accommodate differences to memset (no return value, always setting to 0).
The bzero.S file is left in place due to libc build magic which pulls in
a C variant if a matching .S file is missing.
Reviewed by: kib
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D17355
Both are significantly slower than hand-coded loops. See r338963 for
kernel commit.
bcmp differs from memcmp by always returning 1 when a difference is
found, as opposed to going for a value bigger or lower than 0
depending on what it is. This means it can do less work. For now the
code is duplicated and modified. This will get deduplicated after
another round of optimization when memcmp will get a longer-term form.
Both tested with the glibc suite. While the suite does not have a test
for bcmp, I created a wrapper routine which verified that values match
(0 vs 0, 1 vs non-zero).
Reviewed by: kib
Approved by: re (gjb)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17336
The change resembles what was done in r334537 for kernel routines.
While here take care of i386 variants. Note that primitives remain
suboptimal.
Reviewed by: kib (previous version)
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D17167
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
- Remove .c files which duplicate entries in MISRCS.
- Use the same, less merge conflict prone style in all cases.
- Use MDSRCS for mips (.c and .S files both ended up in SRCS).
- Remove pointless sparc64 Makefile.inc.
- Remove uninformative foreign VCS ID entries.
Reviewed by: emaste, imp, jhb
MFC after: 1 week
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D9841
is used to set the ELF size attribute for functions. It isn't normally
critical but some things can make use of it (gdb for stack traces).
Valgrind needs it so I'm adding it in. The problem is present on all
branches and on both i386 and amd64.
a return instruction. (The latter is discouraged by the Opteron
optimization manual because it disables branch prediction for the return
instruction.)
Reviewed by: bde
