1.\" Copyright (c) 2023 The FreeBSD Foundation 2. 3.\" This documentation was written by Robert Clausecker <fuz@FreeBSD.org> 4.\" under sponsorship from the FreeBSD Foundation. 5. 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14. 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ''AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE 26. 27.Dd August 23, 2023 28.Dt SIMD 7 29.Os 30.Sh NAME 31.Nm simd 32.Nd SIMD enhancements 33. 34.Sh DESCRIPTION 35On some architectures, the 36.Fx 37.Em libc 38provides enhanced implementations of commonly used functions, replacing 39the architecture-independent implementations used otherwise. 40Depending on architecture and function, an enhanced 41implementation of a function may either always be used or the 42.Em libc 43detects at runtime which SIMD instruction set extensions are 44supported and picks the most suitable implementation automatically. 45On 46.Cm amd64 , 47the environment variable 48.Ev ARCHLEVEL 49can be used to override this mechanism. 50.Pp 51Enhanced functions are present in the following architectures: 52.Bl -column FUNCTION__ aarch64_ arm_ amd64_ i386_ ppc64_ -offset indent 53.It Em FUNCTION Ta Em AARCH64 Ta Em ARM Ta Em AMD64 Ta Em I386 Ta Em PPC64 54.It bcmp Ta Ta Ta S1 Ta S 55.It bcopy Ta Ta S Ta S Ta S Ta SV 56.It bzero Ta Ta S Ta S Ta S 57.It div Ta Ta Ta S Ta S 58.It index Ta S Ta Ta S1 59.It ldiv Ta Ta Ta S Ta S 60.It lldiv Ta Ta Ta S 61.It memcmp Ta Ta S Ta S1 Ta S 62.It memcpy Ta S Ta S Ta S Ta S Ta SV 63.It memmove Ta S Ta S Ta S Ta S Ta SV 64.It memset Ta Ta S Ta S Ta S 65.It rindex Ta S 66.It stpcpy Ta Ta Ta S1 67.It strcat Ta Ta Ta S Ta S 68.It strchr Ta S Ta Ta S1 Ta S 69.It strchrnul Ta Ta Ta S1 70.It strcmp Ta Ta S Ta S Ta S 71.It strcpy Ta Ta Ta S1 Ta S Ta S2 72.It strcspn Ta Ta Ta S2 73.It strlen Ta Ta S Ta S1 74.It strncmp Ta Ta S Ta Ta S 75.It strncpy Ta Ta Ta Ta Ta S2 76.It strrchr Ta S Ta Ta Ta S 77.It strspn Ta Ta Ta S2 78.It swab Ta Ta Ta Ta S 79.It wcschr Ta Ta Ta Ta S 80.It wcscmp Ta Ta Ta Ta S 81.It wcslen Ta Ta Ta Ta S 82.It wmemchr Ta Ta Ta Ta S 83.El 84.Pp 85.Sy S Ns :\ scalar (non-SIMD), 86.Sy 1 Ns :\ amd64 baseline, 87.Sy 2 Ns :\ x86-64-v2 88or PowerPC\ 2.05, 89.Sy 3 Ns :\ x86-64-v3, 90.Sy 4 Ns :\ x86-64-v4, 91.Sy V Ns :\ PowerPC\ VSX. 92. 93.Sh ENVIRONMENT 94.Bl -tag 95.It Ev ARCHLEVEL 96On 97.Em amd64 , 98controls the level of SIMD enhancements used. 99If this variable is set to an architecture level from the list below 100and that architecture level is supported by the processor, SIMD 101enhancements up to 102.Ev ARCHLEVEL 103are used. 104If 105.Ev ARCHLEVEL 106is unset, not recognised, or not supported by the processor, the highest 107level of SIMD enhancements supported by the processor is used. 108.Pp 109A suffix beginning with 110.Sq ":" 111or 112.Sq "+" 113in 114.Ev ARCHLEVEL 115is ignored and may be used for future extensions. 116The architecture level can be prefixed with a 117.Sq "!" 118character to force use of the requested architecture level, even if the 119processor does not advertise that it is supported. 120This usually causes applications to crash and should only be used for 121testing purposes or if architecture level detection yields incorrect 122results. 123.Pp 124The architecture levels follow the AMD64 SysV ABI supplement: 125.Bl -tag -width x86-64-v2 126.It Cm scalar 127scalar enhancements only (no SIMD) 128.It Cm baseline 129cmov, cx8, x87 FPU, fxsr, MMX, osfxsr, SSE, SSE2 130.It Cm x86-64-v2 131cx16, lahf/sahf, popcnt, SSE3, SSSE3, SSE4.1, SSE4.2 132.It Cm x86-64-v3 133AVX, AVX2, BMI1, BMI2, F16C, FMA, lzcnt, movbe, osxsave 134.It Cm x86-64-v4 135AVX-512F/BW/CD/DQ/VL 136.El 137.El 138. 139.Sh DIAGNOSTICS 140.Bl -diag 141.It "Illegal Instruction" 142Printed by 143.Xr sh 1 144if a command is terminated through delivery of a 145.Dv SIGILL 146signal, see 147.Xr signal 3 . 148.Pp 149Use of an unsupported architecture level was forced by setting 150.Ev ARCHLEVEL 151to a string beginning with a 152.Sq "!" 153character, causing a process to crash due to use of an unsupported 154instruction. 155Unset 156.Ev ARCHLEVEL , 157remove the 158.Sq "!" 159prefix or select a supported architecture level. 160.Pp 161Message may also appear for unrelated reasons. 162.El 163. 164.Sh SEE ALSO 165.Xr string 3 , 166.Xr arch 7 167.Rs 168.%A H. J. Lu 169.%A Michael Matz 170.%A Milind Girkar 171.%A Jan Hubi\[u010D]ka \" \(vc 172.%A Andreas Jaeger 173.%A Mark Mitchell 174.%B System V Application Binary Interface 175.%D May 23, 2023 176.%T AMD64 Architecture Processor Supplement 177.%O Version 1.0 178.Re 179. 180.Sh HISTORY 181Architecture-specific enhanced 182.Em libc 183functions were added starting 184with 185.Fx 2.0 186for 187.Cm i386 , 188.Fx 6.0 189for 190.Cm arm , 191.Fx 6.1 192for 193.Cm amd64 , 194.Fx 11.0 195for 196.Cm aarch64 , 197and 198.Fx 12.0 199for 200.Cm powerpc64 . 201SIMD-enhanced functions were first added with 202.Fx 13.0 203for 204.Cm powerpc64 205and with 206.Fx 14.0 207for 208.Cm amd64 . 209.Pp 210A 211.Nm 212manual page appeared in 213.Fx 14.0 . 214. 215.Sh AUTHOR 216.An Robert Clausecker Aq Mt fuz@FreeBSD.org 217. 218.Sh CAVEATS 219Other parts of 220.Fx 221such as cryptographic routines in the kernel or in 222OpenSSL may also use SIMD enhancements. 223These enhancements are not subject to the 224.Ev ARCHLEVEL 225variable and may have their own configuration 226mechanism. 227. 228.Sh BUGS 229Use of SIMD enhancements cannot be configured on powerpc64. 230