.\" Copyright (c) 2023 The FreeBSD Foundation . .\" This documentation was written by Robert Clausecker .\" under sponsorship from the FreeBSD Foundation. . .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. . .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ''AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE . .Dd August 5, 2023 .Dt SIMD 7 .Os .Sh NAME .Nm simd .Nd SIMD enhancements . .Sh DESCRIPTION On some architectures, the .Fx .Em libc provides enhanced implementations of commonly used functions, replacing the architecture-independent implementations used otherwise. Depending on architecture and function, an enhanced implementation of a function may either always be used or the .Em libc detects at runtime which SIMD instruction set extensions are supported and picks the most suitable implementation automatically. On .Cm amd64 , the environment variable .Ev ARCHLEVEL can be used to override this mechanism. .Pp Enhanced functions are present in the following architectures: .Bl -column FUNCTION__ aarch64_ arm_ amd64_ i386_ ppc64_ -offset indent .It Em FUNCTION Ta Em AARCH64 Ta Em ARM Ta Em AMD64 Ta Em I386 Ta Em PPC64 .It bcmp Ta Ta Ta S Ta S .It bcopy Ta Ta S Ta S Ta S Ta SV .It bzero Ta Ta S Ta S Ta S .It div Ta Ta Ta S Ta S .It index Ta S Ta Ta S1 .It ldiv Ta Ta Ta S Ta S .It lldiv Ta Ta Ta S .It memcmp Ta Ta S Ta S Ta S .It memcpy Ta S Ta S Ta S Ta S Ta SV .It memmove Ta S Ta S Ta S Ta S Ta SV .It memset Ta Ta S Ta S Ta S .It rindex Ta S .It stpcpy Ta Ta Ta S .It strcat Ta Ta Ta S Ta S .It strchr Ta S Ta Ta S1 Ta S .It strchrnul Ta Ta Ta S1 .It strcmp Ta Ta S Ta S Ta S .It strcpy Ta Ta Ta S Ta S Ta S2 .It strlen Ta Ta S Ta S1 .It strncmp Ta Ta S Ta Ta S .It strncpy Ta Ta Ta Ta Ta S2 .It strrchr Ta S Ta Ta Ta S .It swab Ta Ta Ta Ta S .It wcschr Ta Ta Ta Ta S .It wcscmp Ta Ta Ta Ta S .It wcslen Ta Ta Ta Ta S .It wmemchr Ta Ta Ta Ta S .El .Pp .Sy S Ns :\ scalar (non-SIMD), .Sy 1 Ns :\ amd64 baseline, .Sy 2 Ns :\ x86-64-v2 or PowerPC\ 2.05, .Sy 3 Ns :\ x86-64-v3, .Sy 4 Ns :\ x86-64-v4, .Sy V Ns :\ PowerPC\ VSX. . .Sh ENVIRONMENT .Bl -tag .It Ev ARCHLEVEL On .Em amd64 , controls the level of SIMD enhancements used. If this variable is set to an architecture level from the list below and that architecture level is supported by the processor, SIMD enhancements up to .Ev ARCHLEVEL are used. If .Ev ARCHLEVEL is unset, not recognised, or not supported by the processor, the highest level of SIMD enhancements supported by the processor is used. .Pp A suffix beginning with .Sq ":" or .Sq "+" in .Ev ARCHLEVEL is ignored and may be used for future extensions. The architecture level can be prefixed with a .Sq "!" character to force use of the requested architecture level, even if the processor does not advertise that it is supported. This usually causes applications to crash and should only be used for testing purposes or if architecture level detection yields incorrect results. .Pp The architecture levels follow the AMD64 SysV ABI supplement: .Bl -tag -width x86-64-v2 .It Cm scalar scalar enhancements only (no SIMD) .It Cm baseline cmov, cx8, x87 FPU, fxsr, MMX, osfxsr, SSE, SSE2 .It Cm x86-64-v2 cx16, lahf/sahf, popcnt, SSE3, SSSE3, SSE4.1, SSE4.2 .It Cm x86-64-v3 AVX, AVX2, BMI1, BMI2, F16C, FMA, lzcnt, movbe, osxsave .It Cm x86-64-v4 AVX-512F/BW/CD/DQ/VL .El .El . .Sh DIAGNOSTICS .Bl -diag .It "Illegal Instruction" Printed by .Xr sh 1 if a command is terminated through delivery of a .Dv SIGILL signal, see .Xr signal 3 . .Pp Use of an unsupported architecture level was forced by setting .Ev ARCHLEVEL to a string beginning with a .Sq "!" character, causing a process to crash due to use of an unsupported instruction. Unset .Ev ARCHLEVEL , remove the .Sq "!" prefix or select a supported architecture level. .Pp Message may also appear for unrelated reasons. .El . .Sh SEE ALSO .Xr string 3 , .Xr arch 7 .Rs .%A H. J. Lu .%A Michael Matz .%A Milind Girkar .%A Jan Hubi\[u010D]ka \" \(vc .%A Andreas Jaeger .%A Mark Mitchell .%B System V Application Binary Interface .%D May 23, 2023 .%T AMD64 Architecture Processor Supplement .%O Version 1.0 .Re . .Sh HISTORY Architecture-specific enhanced .Em libc functions were added starting with .Fx 2.0 for .Cm i386 , .Fx 6.0 for .Cm arm , .Fx 6.1 for .Cm amd64 , .Fx 11.0 for .Cm aarch64 , and .Fx 12.0 for .Cm powerpc64 . SIMD-enhanced functions were first added with .Fx 13.0 for .Cm powerpc64 and with .Fx 14.0 for .Cm amd64 . .Pp A .Nm manual page appeared in .Fx 14.0 . . .Sh AUTHOR .An Robert Clausecker Aq Mt fuz@FreeBSD.org . .Sh CAVEATS Other parts of .Fx such as cryptographic routines in the kernel or in OpenSSL may also use SIMD enhancements. These enhancements are not subject to the .Ev ARCHLEVEL variable and may have their own configuration mechanism. . .Sh BUGS Use of SIMD enhancements cannot be configured on powerpc64.